CA2130000A1 - A process for the production of granules suitable as wetting agents, detergents and/or cleaning products - Google Patents
A process for the production of granules suitable as wetting agents, detergents and/or cleaning productsInfo
- Publication number
- CA2130000A1 CA2130000A1 CA002130000A CA2130000A CA2130000A1 CA 2130000 A1 CA2130000 A1 CA 2130000A1 CA 002130000 A CA002130000 A CA 002130000A CA 2130000 A CA2130000 A CA 2130000A CA 2130000 A1 CA2130000 A1 CA 2130000A1
- Authority
- CA
- Canada
- Prior art keywords
- steam
- fluidized bed
- terized
- charac
- drying
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D1/00—Evaporating
- B01D1/16—Evaporating by spraying
- B01D1/18—Evaporating by spraying to obtain dry solids
-
- C—CHEMISTRY; METALLURGY
- C11—ANIMAL OR VEGETABLE OILS, FATS, FATTY SUBSTANCES OR WAXES; FATTY ACIDS THEREFROM; DETERGENTS; CANDLES
- C11D—DETERGENT COMPOSITIONS; USE OF SINGLE SUBSTANCES AS DETERGENTS; SOAP OR SOAP-MAKING; RESIN SOAPS; RECOVERY OF GLYCEROL
- C11D11/00—Special methods for preparing compositions containing mixtures of detergents ; Methods for using cleaning compositions
- C11D11/0082—Special methods for preparing compositions containing mixtures of detergents ; Methods for using cleaning compositions one or more of the detergent ingredients being in a liquefied state, e.g. slurry, paste or melt, and the process resulting in solid detergent particles such as granules, powders or beads
-
- C—CHEMISTRY; METALLURGY
- C11—ANIMAL OR VEGETABLE OILS, FATS, FATTY SUBSTANCES OR WAXES; FATTY ACIDS THEREFROM; DETERGENTS; CANDLES
- C11D—DETERGENT COMPOSITIONS; USE OF SINGLE SUBSTANCES AS DETERGENTS; SOAP OR SOAP-MAKING; RESIN SOAPS; RECOVERY OF GLYCEROL
- C11D11/00—Special methods for preparing compositions containing mixtures of detergents ; Methods for using cleaning compositions
- C11D11/02—Preparation in the form of powder by spray drying
-
- C—CHEMISTRY; METALLURGY
- C11—ANIMAL OR VEGETABLE OILS, FATS, FATTY SUBSTANCES OR WAXES; FATTY ACIDS THEREFROM; DETERGENTS; CANDLES
- C11D—DETERGENT COMPOSITIONS; USE OF SINGLE SUBSTANCES AS DETERGENTS; SOAP OR SOAP-MAKING; RESIN SOAPS; RECOVERY OF GLYCEROL
- C11D11/00—Special methods for preparing compositions containing mixtures of detergents ; Methods for using cleaning compositions
- C11D11/04—Special methods for preparing compositions containing mixtures of detergents ; Methods for using cleaning compositions by chemical means, e.g. by sulfonating in the presence of other compounding ingredients followed by neutralising
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F26—DRYING
- F26B—DRYING SOLID MATERIALS OR OBJECTS BY REMOVING LIQUID THEREFROM
- F26B21/00—Arrangements or duct systems, e.g. in combination with pallet boxes, for supplying and controlling air or gases for drying solid materials or objects
- F26B21/02—Circulating air or gases in closed cycles, e.g. wholly within the drying enclosure
- F26B21/04—Circulating air or gases in closed cycles, e.g. wholly within the drying enclosure partly outside the drying enclosure
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F26—DRYING
- F26B—DRYING SOLID MATERIALS OR OBJECTS BY REMOVING LIQUID THEREFROM
- F26B3/00—Drying solid materials or objects by processes involving the application of heat
- F26B3/02—Drying solid materials or objects by processes involving the application of heat by convection, i.e. heat being conveyed from a heat source to the materials or objects to be dried by a gas or vapour, e.g. air
- F26B3/10—Drying solid materials or objects by processes involving the application of heat by convection, i.e. heat being conveyed from a heat source to the materials or objects to be dried by a gas or vapour, e.g. air the gas or vapour carrying the materials or objects to be dried with it
- F26B3/12—Drying solid materials or objects by processes involving the application of heat by convection, i.e. heat being conveyed from a heat source to the materials or objects to be dried by a gas or vapour, e.g. air the gas or vapour carrying the materials or objects to be dried with it in the form of a spray, i.e. sprayed or dispersed emulsions or suspensions
Abstract
Granulates are produced from their aqueous solutions and/or suspensions by fluidized bed spray granulation in a hot fluidizing gas in the normal pressure range. Overheated steam is used as fluidizing gas and the granulate is evacuated from the granulator before it risks being damaged by heat exposure. If required, the storage-stable looseness and pourability of the partially dried substance is ensured by admixture of components capable of binding limited amounts of water and/or by a subsequent treatment. The system is a closed system in which a current of steam circulates, from which the water evaporated from the process substance is drawn as a partial current and to which the released thermal energy is supplied again. The process is free from exhaust fumes and contanimated waste waters, without diminishing the quality of the granulate produced on a large scale.
Description
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~0 93/15813 PC~/EP93/0026fi A proce~s for the pro~uctio~ of granule~ suitable as ~etting ~gent~, detergent~ a~d/or cle~ning pro~ucts This invention relates to a process for the production of pourable free-flowing granules of useful materials or mixtures thereof, which are suitable as and/or for use in wetting agents, detergents and/or cleaning products, from aqueous solutions and/or suspensions of such materials by fluidized-bed spray granulation in a hot fluidizing gas in the region of normal pressure.
Processes for the production of particles on an industrial scale from initially liquid products, i. 2. from solutions or suspensions, include in particular spray dry-ing, spray drying with integrated fluidized-bed agglomera-tion and fluidized-bed spray granulation. For decades now, spray drying has been typically used worldwid~ for the industrial-scale production of granules from aqueous preparations of useful materials of the type mentioned at the beginning. Hot air or mixtures of air and hot waste combustion gases are used as the drying gas stream.
Washing powders and useful materials and mixtures thereof for the production of laundry detergents in pourable free-flowing powder form are industrially obtained in so-called spray-drying towers generally operated at ambient pressure either in countercurrent or, occasionally, in co-current.
The use of fluidized-bed spray granulation for the production of detergent granules is also known from the prior art ~hlema~n in Chem.-Ing.-T~ch. 62 (1990), No. 10, pages 822 ~ 83~ and EPoB-163 836). In this process, which is carried out far more rarely for the production of powder-form wetting agents, detergents and cleaning prod-ucts, solid particles are kept suspended in an upwardly directed gas stream. In this state, the~ particles are separated from one another and are thus universally acces-- ~3~ o - ::
., ,, . ~, .
~0 93/15813 PC~/EP93/0026fi A proce~s for the pro~uctio~ of granule~ suitable as ~etting ~gent~, detergent~ a~d/or cle~ning pro~ucts This invention relates to a process for the production of pourable free-flowing granules of useful materials or mixtures thereof, which are suitable as and/or for use in wetting agents, detergents and/or cleaning products, from aqueous solutions and/or suspensions of such materials by fluidized-bed spray granulation in a hot fluidizing gas in the region of normal pressure.
Processes for the production of particles on an industrial scale from initially liquid products, i. 2. from solutions or suspensions, include in particular spray dry-ing, spray drying with integrated fluidized-bed agglomera-tion and fluidized-bed spray granulation. For decades now, spray drying has been typically used worldwid~ for the industrial-scale production of granules from aqueous preparations of useful materials of the type mentioned at the beginning. Hot air or mixtures of air and hot waste combustion gases are used as the drying gas stream.
Washing powders and useful materials and mixtures thereof for the production of laundry detergents in pourable free-flowing powder form are industrially obtained in so-called spray-drying towers generally operated at ambient pressure either in countercurrent or, occasionally, in co-current.
The use of fluidized-bed spray granulation for the production of detergent granules is also known from the prior art ~hlema~n in Chem.-Ing.-T~ch. 62 (1990), No. 10, pages 822 ~ 83~ and EPoB-163 836). In this process, which is carried out far more rarely for the production of powder-form wetting agents, detergents and cleaning prod-ucts, solid particles are kept suspended in an upwardly directed gas stream. In this state, the~ particles are separated from one another and are thus universally acces-- ~3~ o - ::
2 PCT/~P93/00266 sible to the droplets formed when liquid is sprayed into the fluidized bed. In addition, intensive heat exchange and mass transfer between the solid particles and the gas stream take place in this state.
Nows when a sprayed droplet meets a suspended par-ticle, the liquid product of the sprayed droplet spread~
over the solid substrate. The intensive heat exchange and mass transfer with the surrounding gas stream results in drying and solidification of the liquid film. As a result of repeated spraying, spreading and solidification, the particle grows like an onion. The particle with the required particle size is compact and also substantially round.
In the fluidized-bed spray granulation of aqueous preparations of the substan~es mentioned at the beginning, hot air is used as the fluidizing gas in the same way as in -~
spray drying. In addition, the use of nitrogen gas is mentioned in EP-B-163 836. -In addition to the discretionary availability of the gas phase, advantages of drying using hot air as the drying gas include inter alia the possibility of working in so-called open systems which enable the moisture-laden hot gas phase to be disposed of without difficulty by discharge into the outside atmosphere. In addition, intensive physicochemic~l investigations into the course followed by the drying process have shown that drying with hot air takes place effectively and quickly, even where compara-tively mild hot gas temperatures are used. The drying process on the moist particle actually begins at compara-tively low temperatures, for example at particle tempera-tures of around 40C, largely irrespective of the tempera-ture of the hot gas used and continues with a comparatively slow increase in the particle temperature to the boiling range of water under normal pressure. Overall, the drying process in hot air takes place quickly and very effective-;~30~)~0 . ` .~
Wo 93/158'3 3 PCT/EP93/30266 ly, even in the final stages, so that the useful materials are exposed to comparatively mild temperatures during drying to form the free-flowing particles.
Among the disadvantages and limitations of this type 5of process for the specialist field targeted by the inven-tion of the drying of useful materials or mixtures thereof in the production of laundry detergents and/or cleaning products, the following points are mentioned by way of example. Many of these useful materials are sensitive to 10oxidation, particularly in the case of organic components.
The treatment with hot air can lead to damage, particularly at relatively high temperatures. The drying of organic or substantially organic useful materials, for example surfac-tants based on natural materials, presents considerable 15problems through the risk of fire or even explosion of the material being dried. Important useful material compo-nents, more particularly detergent-range nonionic surfac-tants, show a more or less pronounced tendency towards pluming, i.e. the transfer of organic aerosols to the 20steam-laden waste air of the spray-drying towers. Overall, there is an increased danger of environmental pollution from the large quantities of aqueous, solid and gaseous matarials and auxiliaries involved in the process.
Thoughts of recirculating the drying gas stream have never 25materialized successfully in the industrial application of this process.
It is also known that superheated steam can be used instead of hot air as the drying gas in fluidized-bed ~ drying (Gehrmann, Chem.-Ing.-Tech. 62 (1990), No. 10, pages 30A 5512 - A 520). Particularly low emissions (wastewater, waste air) are achieved in this case through condensation o~ the vapors driven out. According to the prior art, however, this process can only be used for relatively heat-resistant products, such as for example lignite or treated 35sewage. The drying of paper pulp is mentioned as another ~L30~)~0 .` . i ~
` . :
~0 93/15813 4 PCT/~Ps3/00266 application. The same document refers to the use of vacuum dryers to reduce emissions in the dryiny of temperature-sensitive products, but at the same time refers to the difficulties involved in the continuous operation of such dryers with free-flowing bulk materials.
Problems are also encountered in the drying of temper-ature-sensitive products in steam fluidized-bed dryers.
This is because the dryi~g rate at temperatures around 150C is distinctly lower for superheated steam than for hot air. The drying rates can only be increased by raising the operating temperature to 250C. Accordingly, where superheated steam is used as the drying gas, useful materi-als of the type mentioned at the beginning can only be dried to typical residual moisture contents in acceptable 1~ drying times at high operating temperatures at which unacceptable damage to the material being dried occurs.
Accordingly, the problem addressed by the present invention was to improve the process mentioned at the beginning so that it could be carried out free from waste gases and free from polluted wastewater without any deteri-oration in the quality of the granules obtained where the process is carried out on an industrial scale.
According to the invention, the solution to this pro~lem is characterized in that superheated steam is used as the fluidizing gas, the granules are discharged from the granulator before they can be damaged by heat and the long-te~m pourability and flowability of the material thus dried is optionally established by addition of mixture constitu-ents capable of binding limited quantities of water and/or by an aftertreatment and in that the process is carried out in a closed-loop system comprising a steam circuit from which the water evaporated from the starting material is removed as a partial stream and the thermal energy released is returned. Energy can be supplied outside the drying vessel by superheating the steam and/or inside the drying - 2~30~o
Nows when a sprayed droplet meets a suspended par-ticle, the liquid product of the sprayed droplet spread~
over the solid substrate. The intensive heat exchange and mass transfer with the surrounding gas stream results in drying and solidification of the liquid film. As a result of repeated spraying, spreading and solidification, the particle grows like an onion. The particle with the required particle size is compact and also substantially round.
In the fluidized-bed spray granulation of aqueous preparations of the substan~es mentioned at the beginning, hot air is used as the fluidizing gas in the same way as in -~
spray drying. In addition, the use of nitrogen gas is mentioned in EP-B-163 836. -In addition to the discretionary availability of the gas phase, advantages of drying using hot air as the drying gas include inter alia the possibility of working in so-called open systems which enable the moisture-laden hot gas phase to be disposed of without difficulty by discharge into the outside atmosphere. In addition, intensive physicochemic~l investigations into the course followed by the drying process have shown that drying with hot air takes place effectively and quickly, even where compara-tively mild hot gas temperatures are used. The drying process on the moist particle actually begins at compara-tively low temperatures, for example at particle tempera-tures of around 40C, largely irrespective of the tempera-ture of the hot gas used and continues with a comparatively slow increase in the particle temperature to the boiling range of water under normal pressure. Overall, the drying process in hot air takes place quickly and very effective-;~30~)~0 . ` .~
Wo 93/158'3 3 PCT/EP93/30266 ly, even in the final stages, so that the useful materials are exposed to comparatively mild temperatures during drying to form the free-flowing particles.
Among the disadvantages and limitations of this type 5of process for the specialist field targeted by the inven-tion of the drying of useful materials or mixtures thereof in the production of laundry detergents and/or cleaning products, the following points are mentioned by way of example. Many of these useful materials are sensitive to 10oxidation, particularly in the case of organic components.
The treatment with hot air can lead to damage, particularly at relatively high temperatures. The drying of organic or substantially organic useful materials, for example surfac-tants based on natural materials, presents considerable 15problems through the risk of fire or even explosion of the material being dried. Important useful material compo-nents, more particularly detergent-range nonionic surfac-tants, show a more or less pronounced tendency towards pluming, i.e. the transfer of organic aerosols to the 20steam-laden waste air of the spray-drying towers. Overall, there is an increased danger of environmental pollution from the large quantities of aqueous, solid and gaseous matarials and auxiliaries involved in the process.
Thoughts of recirculating the drying gas stream have never 25materialized successfully in the industrial application of this process.
It is also known that superheated steam can be used instead of hot air as the drying gas in fluidized-bed ~ drying (Gehrmann, Chem.-Ing.-Tech. 62 (1990), No. 10, pages 30A 5512 - A 520). Particularly low emissions (wastewater, waste air) are achieved in this case through condensation o~ the vapors driven out. According to the prior art, however, this process can only be used for relatively heat-resistant products, such as for example lignite or treated 35sewage. The drying of paper pulp is mentioned as another ~L30~)~0 .` . i ~
` . :
~0 93/15813 4 PCT/~Ps3/00266 application. The same document refers to the use of vacuum dryers to reduce emissions in the dryiny of temperature-sensitive products, but at the same time refers to the difficulties involved in the continuous operation of such dryers with free-flowing bulk materials.
Problems are also encountered in the drying of temper-ature-sensitive products in steam fluidized-bed dryers.
This is because the dryi~g rate at temperatures around 150C is distinctly lower for superheated steam than for hot air. The drying rates can only be increased by raising the operating temperature to 250C. Accordingly, where superheated steam is used as the drying gas, useful materi-als of the type mentioned at the beginning can only be dried to typical residual moisture contents in acceptable 1~ drying times at high operating temperatures at which unacceptable damage to the material being dried occurs.
Accordingly, the problem addressed by the present invention was to improve the process mentioned at the beginning so that it could be carried out free from waste gases and free from polluted wastewater without any deteri-oration in the quality of the granules obtained where the process is carried out on an industrial scale.
According to the invention, the solution to this pro~lem is characterized in that superheated steam is used as the fluidizing gas, the granules are discharged from the granulator before they can be damaged by heat and the long-te~m pourability and flowability of the material thus dried is optionally established by addition of mixture constitu-ents capable of binding limited quantities of water and/or by an aftertreatment and in that the process is carried out in a closed-loop system comprising a steam circuit from which the water evaporated from the starting material is removed as a partial stream and the thermal energy released is returned. Energy can be supplied outside the drying vessel by superheating the steam and/or inside the drying - 2~30~o
3 5 PCT/EP93/00266 vessel via integrated heat exchangers.
Earlier patent application DB-A 40 30 688 describes a process for obtaining fine-particle, solid, pourable or flowable useful materials or mixtures thereof for wetting agents, detergents andJor cleaning products from aqueous preparations of the materials, in which superheated steam is used as the drying ho~ gas stream and drying of the particulate material i5 terminated before it is damaged by heat. If necessary, the long-term pourability or flowabil-ity of the material thus partly dried is established by addition of mixture constituents which are capable of binding limited quantities of water. In addition to or instead of this measure, the particulate material may also be aftertreated to homogenize its residual moisture content and/or subsequently dried under moderate conditions.
However, spray drying is used for the production of granules in this earlier application. Fluidized-bed drying -is merely mentioned as an option for the aftertreatment of the dried material. ;
The present invention, which is described hereinafter, -relates to a specific embodiment of the process according to the earlier application cited above. In the interests of full and complete disclosure of the invention, the dis-closure of this earlier application is specifically in-cluded in the disclosure of the present invention.
It is important in this connection to bear in mind the fact that practical experience in the application of drying processes using superheated steam as the drying gas has ;-Ibeen very llmited up till now although, basically, this technology has been known since the beginning of this century and has been repeatedly described in the litera- j ture. Earlier application DE-A 40 30 688 deals in detail with the relevant prior-art literature. Reference is made here to the corresponding observations in the earlier application and solely to the following publications which z~30~0 .
Wo 93/15813 6 PCT/BP93/00266 in turn cite numerous publications on this sub~ect: A.M.
Trommale~ et al. "Ev~poration an~ Drying of Drop~ in ~uper-heate~ V~pors~' AIChE Journal ~6 tl970) 857 867; Col~ Beeby ~t ~1. "~T~ 1 DRYING" Pl~n~ry Lecture, Pro~s. 4th Int.
5 Drying 8y~n. Ryoto ~a~. R,, Toei and Arun ~. ~u~ a~-) lQ~, Vol. 1, 51-68 ~nd W.A. ~tei~ "Berechnung der Verdampfung ~on Flu~igkait au~ feuahte~ Produkte~l im 8pruhturDI (C~lcu-latiIIg the 13vaporation of Liquid from Moi~t Products in ~pr y Drying ~ow~r~", Verf~hr~nYtechnik 7 (1973), 262-267.
There is a fundamental difference between drying with hot air and drying with superheated steam which is crucial to the understanding of the invention: where hot air is used, the drying process begins effectively at relatively low material temperatures. The removal of water is so pronounced that drying is almost complete on reaching a material temperature of around 100C. For example, up to about 90% of the total water present has already been removed from the droplet by this time. The temperature profile of the droplet is completely different where superheated steam is used. By condensation of the super-heated steam on the cooler starting material and release of the heat of condensation to the material to be dried, the aqueous drop is spontaneously heated to the boiling temper-ature of the water under the operating conditions, i.e. to temperatures of ~round 100C where drying is carried out under normal pressure. This boiling temperature is main-tained as a minimum temperature in the drop of material - throughout the entire drying pro~ess. The particular level of charging of the aqueous phase with the dry materialc to be obtained leads to individual upward deviations of the temperature profile at an earlier or later stage, depending on the degree of drying of the drop.
In the process according to the invention, in which certain limitations regarding the result of drying in the 3 end product are intentionally accepted, use is made of the 3~ 0 WO 93~15813 7 PCT/BP93/00266 various advantages of replacing hot air by superheated steam in fluidized-bed spray granulation precisely in the case of the temperature-sensitive material with which the invention is concerned. According to the invention, a crucial element in this regard is the acceptance in the dried material of residual moisture contents which can be quite considerable, depending on the particular case, and at the same time the establishment of the long-term pour-ability and flowa~ility of the granular material thus dried either by optional auxiliaries and/or by an aftertreatment, for example after~drying. The auxiliaries used may in turn be selected useful materials for the application envisaged or inert materials, as will be explained hereinafter.
According to the invention, it is thus possible to maintain the quality standards of the well known complex require-ments which the multicomponent mixtures based on organic and inorganic components, for example laundry detergents, with which the invention is concerned, are expecte~ to satisfy without any reduction in quality and without losing any of the advantages of drying with superheated steam.
Oxidation processes involving vulnerable components of the - wetting agents, detergents and cleaning preparations are suppressed, dangers of fire and explosions are eliminated.
Since the drying steam is circulated, no unwanted compo-nents are discharged into the surrounding atmosphere. Only the vapors formed from the material to be dried have to be removed from the circuit and cleaned. Any fractions of material removed in the process are utilised. Other tech-nological advantages regarding the design of the corre-sponding apparatus can also be utilized.
The energy introduced into the steam circuit outsidethe fluidized bed may be introduced in any known form, althouqh indirect heat transfer is preferred. The use of tube-bundle systems, throu~h which heating gases of any origin on the one hand and - separately therefrom - the 2~3~ 0 ~O 93/15813 8 PCT/~P93/00266 steam to be heated on the other hand flow, is mentioned as an example.
In one particularly important embodiment of the invention, this indirect introduction of energy into the steam circuit is carried out by one or more ,ntegrated burners with indirect transfer of heat to the steam, the hot combustion gases heing directly introduced into the heat exchanger - integrated in the steam circuit - on the burner side. The temperature of the combustion gases may be, for example, in the range from about 400 to 1000C and, more particularly, is in the range from about 650 to 960C.
In the interests of optimal heat utilization and hence to reduce the costs of the process as a whole, it can be useful if the waste gases are also partly and, preferably, substantially completely circulated. For example, at least 30% by volume and preferably more than 40% by volume of the hot waste gases can be recirculated after leaving the integrated heat exchanger for the further utilization of energy. The quantity of waste gases recirculated preferab-ly amounts to more than 60% by volume and often to around 70% by volume of the combustion gases introduced. The burner may be operated with any of the usual fuel gases, more particularly natural gas or comparable lower hydrocar-bons or hydrocarbon mixtures and/or hydrogen.
In the process according to the invention, thermal energy is mainly supplied to the superheated steam through internal or external heat exchangers, the superheated steam serving as transfer medium. The reliable and total absence of pollutants, particularly oxygen and carbon dioxide, in the drying gas ensures that the material to be dried does not undergo unwanted oxidation and also rules out the formation of carbonate salts or carbonate deposits that are unavoidable in the mostly basic useful materials with which the invention is concerned where drying gases containing waste gas are used. The use of heat exchangers integrated 2~30~0 WO 93/15813 9 PCT/EP~3/00266 in the fluidized bed for additional heating provides for the particularly effective transfer of heat and for a considerably lower steam temperature than heating solely by introduction of superheated steam to obtain the same residual moisture content so that thermal stressing of the material to be dried i5 minimal. This variant of the process is particularly suitable for drying materials of medium temperature sensitivity. In the drying of thermally more sensitive useful materials and mixtures thereof, it is of greater advantage to use only external heat exchangers with shorter` residence times than in the case of heat exchangers integrated in the fluidized bed.
The process according to the invention is carried out in a closed-loop system with a steam circuit from which the water evaporated from the starting material is removed while the energy released in particular in the drying step is returned to the circuit. In one important embodiment, the steam removed is first freed from entrained fractions of the starting material and put to another use as process steam~ if desired after its temperature and pressure have been adapted to the conditions prevailing there. In another embodiment of the process according to the inven-tion, it is useful to condense at least part of the steam removed. The aqueous liquid phase accumulating together with the fractions of the useful material present therein (having been removed from the circuit) is used, preferably after concentration, for the preparation of the aqueous solutions and/or suspensions to be dried.
In another preferred embodiment, the process is carried out with internal pressures of the steam-filled system in the region of normal pressure. In this embodi-ment, however, such elevated pressures are established in the circuit that air can be reliably prevented from pene-tratin~ the steam-filled circuit, for example in damaged area~ which can never be completely ruled out in industrial ~3~ ) [)O
..
Uo 93/15813 10 PCT/~P93~00266 installations.
Working in the region of normal pressure enables the process to be carried out relatively free from complica-tions, even in industrial plants, with the necessar~ high throughputs per unit of time. Since foreign gas, particu-larly air, is unable to penetrate into the stea~-filled circulation system, secondary damage to the high product quality required is reliably avoided. Suitable working pressures are, for example, in the range up to about 150 mbar, preferably up to about 75 mbar and, more preferably, below 50 mbar excess pressure. The range from about 5 to 15 mbar excess pressure can be of particular advantage.
Drying with superheated steam in accordance with the invention is of course also possible in prinaiple at reduced pressures, particularly moderate reduced pressures, although in this case increased outlay on equipment is necessary for ensuring the absence of possible damaged areas in the circulation system which could initiate the unwanted penetration of air.
The fact that optimal drying results by the effect of superheated steam on the end process product are not necessary is a crucial aspect of the teaching according to the invention. Residual moisture contents, even of a significant level, can be tolerated providing the composi-tion of the material ensures that the residual water is bound so extensively by a form of "internal drying" that the long-term pourability and free flow of the dry material is guaranteed.
If the temperature sensitivity of the useful material or mixture of useful materials to be dried means that considerable quantities of water have to remain in the product subjected to the main drying process, so that this residual water may have to be bound to ensure the long-term pourability and free flow of the dried material, auxili-aries capable of fixing water, preferably in the form of 2~3~0 ~O 93/15813 11 PCT/EP93/00266 particulate solids, are used in accordance with the inven-tion. In this case, residual water may be fixed, for example, by binding as water of crystalliæation. However, limited quantities of water in solid particles of the type in question here can also be bound purely by absorption without causing any unwanted tackiness or adhesion of the particles to one another The auxiliaries are at least used in guantities sufficient to guarantee pourability and stability in storage despite the residual moisture present in the material.
In one embodiment of the invention, the aux:iliaries used to bind the residual water may be added to the dried fresh material, best immediately after it has left the granulator, and intensively mixed therewith. In a prefer-red embodiment, however, the auxiliaries are at leastpartly added to the aqueous solutions or suspensions before spray granulation in the fluidized bed. This particular embodiment may always be applied when the particular temperature sensitivity of the material to be dried allows drying to be carried out to such an extent that the residu-al moisture remaining in the product can be adequately absorbed and bound by the auxiliaries used.
In one embodiment of the process according to the invention of particular advantage in this regard, corre-sponding useful materials from the field of wetting agents,detergents and/or cleaning products which themselves are sufficiently immune to temperature are used as the auxilia-ries capable of binding residual water. Typical examples of such materials are inorganic materials capable of binding water of crystallization from the classes of builder components, washing alkalis and/or so-called fillers, for example silicate compounds capable of binding water of crystallization, more particularly zeolites. One example particularly characteristic of laundry detergents is detergent-quality zeolite NaA which has a calcium 2~L30~00 j`^ ~ I
binding power of 100 to 200 mg CaO/g (cf. D~ 2~ 12 837).
Examples of washing alkalis which bind water of crystal-lization are soda or sodium bicarbonate while sodium sulfate as neutral salt or fillers are capable of binding considerable ~uantities of water of crystallization.
However, in addition to or instead of the above-mentioned auxiliaries capable of binding water of crystallization, the residual water may also be bound by auxiliaries or corresponding useful materials capable of binding water by absorption. Thus, it is known that known starch- or cellulose-based redeposition inhibitors, fabric softeners, particularly those based on inorganic swellable silicates, and also a num~er of organic surfactant compounds which are solid under normal conditions are capable of absorbing considerable quantities of water without reacting by developing unwanted surface tackiness.
Depending on the temperature sensitivity of the useful materials or mixtures of useful materials used on the one hand and the nature and quantity of the auxiliaries used on the other hand, considerable residual water contents may remain in the dried material without endangering its long-term pourability and free flow. According to the inven-tion, therefore, drying with superheated steam is termi-nated at residual water contents of the materials removed from the fluidized bed in the range from about 1 to 20% by weight, residual water contents in the range from about 5 to 15% by weight being preferred. The ranges mentioned relate to the weight of the material discharged from the fluidized bed. In another preferred embodiment of the invention, the amount of residual water which is not bound as water of crystallization is limited to at most about 10%
by weight and preferably to no more than about 3 to 4% by weight. The foregoing observations on the percentages by weight apply in this case, too.
The working conditions of the process according to the 2~301~0 `
Wo 93/15813 13 PCT/EP93/00266 invention enable high temperatures of the circulated ~team phase to be applied in fluidized-bed drying. If the heat is introduced slowly via the steam phase, wor~ing tempera-tures in the range from about 270 to 350C in the steam - 5 phase are particularly suitable. These temperature values apply to the temperature of the optimally heated steam delivered to the fluidized bed.
Where a heat exchanger integrated into the fluidized bed is used, the heat is largely introduced throuqh this heat exchanger. The steam phase is used for fluidization.
In this case, the preferred steam entry temperatures are considerably lower, i.e. in the range from 150 to 180C.
The lower drying rate is equalized through the greater length and/or height of the bed and hence through the longer residence time in the drying zone. Accordingly, one of the two embodiments is more advantageous, depending on the temperature sensitivity of the material to be dried.
Considerations based largely on energy factors, including the intended su~sequent use of the steam to be removed from the circuit, determine the quantitative ratios between the quantity of water to be evaporated and the quantity of superheated steam delivered. Embodiments which provide only for a limited reduction in the steam tempera-ture after leaving the fluidized bed are possible in this regard whereas, in other embodiments, the thermal energy of the steam can be further utilized to reduce the temperature of the steam to the vicinity of the condensation tempera-ture. It is also possible, as known per se, to divide the fluidized bed into various zones: high-temperature and medium-temperature zones and also a cooling zone.
In one particularly interesting embodiment of the invention, the heat of condensation of the steam removed from the circuit is recovered and utilized. By adopting suitable measures, it is even possible to recycle the small amounts of useful material which have left the primary Z3.3~ )0 !
~o 93/15813 14 PC~/EP93/00266 steam circuit via the superheated steam removed therefrom.
To this end, the following procedure, for example, may be adopted using the heat of condensation of the steam removed from the circuit:
Using the heat of condensation of the steam removed from the circuit, the steam condensate is concentrated in a preferably multipl~-stage evaporation unit. The residual concentrate accumulating is returned to the primary process circuit. More particularly, this residual ~oncentrate may be added to the slurry of useful material to be dried by superheated steam.
If necessary, a residual gas phase charged with minimal quantities of useful material, which may possibly accumulate during condensation of the superheated steam removed from the primary circuit, may be subsequently worked up, for example by incineration or by treatment in - biofilters or in washing units. By this combination of substantially complete recycling of the particular streams and the reliable destruction of final residual traces, the process according to the invention makes it possible for the first time in the industrial field with which the invention is concerned to recover useful materials and mixtures of useful materials from the field of detergents and cleaning products free from waste air and free from pollu~ed wastewater.
In addition to or instead of using auxiliaries capable of binding residual water, the invention also provides for after-treatment of the partly dried granules initially obtained. The aftertreatment may be carried out by two methods which may even be combined with one another.
The first of these methods is based on the fact that the individual degree of drying of the particular particle in question is determined by its particle size. If, in accordance with the invention, the drying process is terminated at a time when considerable quantities of ~30~QO `~
WO 93/15~13 15 PCT/EP93/OQ266 residual moisture are still present in the material, integral consideration of the residual moisture content does only partial justice to reality. By differential consideration of the distribution of this residual moisture over the individual fractions of material, it has been found that the fine or ultrafine fractions can be dried very extensively or completely while the coarser fractions are still so moist that the material removed from the fluidized bed is not guaranteed long-term pourability and free flow. In one important embodiment of the process ~ ;
according to the invention, therefore, "after-drying" of the primary material from the fluidized bed is achieved by an additional, at least single-stage aftertreatment step which - without exposing the powder-form material to the risk of developing tackiness - leads to homogenization of the moisture content over the material as a whole irrespec-tive of the individual particle size. In this way, so much residual moisture can be introduced into the fine and ultrafine material from the still comparatively moist coarse particles of the material that, after this homogen-ization step, the long-term pourability and free flow of tha dried material are guaranteed without further quanti-ties of moisture having to be additionally eliminated from the bulk material.
This aftertreatment step may be carried out by any method which equalizes the moisture content of the indi-vidual particles and, at the same time, prevents them from adhering to one another. Circulation, mixing or shaking of the material initially obtained either continuously or dis-continuously are mentioned as examples of such methods.
Aftertreatment of the material in another following fluid-ized bed can be particularly suitable.
Any gases, preferably ambient air, may be used for this purpose. Damage to the material by oxidation and unwanted contamination of the waste air is minimal or non-~30 [:)00 . . . .
WO 93/15813 16 ~CT~P93/00266 existent and is easy to control. Since the material to be dried is removed from the fluidized bed at elevated temper-ature, typically of the order of 105-C, a further slight reduction in the residual moisture content can be obtained by this subsequent homogenization of moisture in a fluid-ized bed.
However, in addition to or instead of this auxiliary measure, provision can also be made in the process accord-ing to the invention for a further reduction in the residu-al moisture content by additional drying in one or morestages. The after-drying treatment is characterized in that it is carried out under conditions which do not damage the useful materials in the material to be dried. Examples of process parameters for reducing risk include reducing the temperature of the hot gas phase, dispensing with superheated steam as the hot gas and replacing it with drying gases of different origin, for example air and/or inert gas, and changing over to another drying technology.
The process of fluidized-bed spray granulation is based on the growth of nuclei which are either formed in the fluidized bed itself by non-colliding, solidifying spray droplets or are produced through abrasion of solid particles already present or which are delivered to the fluidized bed from outside. If the process is to be carried out continuously, uniform granulation conditions must prevail. All the granules removed from the fluidized bed have to be replaced by an equivalent number of new nuclei. On the other hand, the waste gas has to be freed I from fine particles of material entrained therein. How-ever, these fine particles are also nuclei. In order,therefore, to ensure equalization of the above-mentioned particle balance in a particularly simple and economic manner, the fine particles of material escaping from the fluidized bed with the waste gas are separated and returned to the fluidized bed as nuclei for the formation of gran-2~30~
.
WO 93/15813 17 ~CT/EP93/00266 ules, more particularly internally by means of a dustfilter arranged over the fluidized bed. The fine particles may be separated from the waste gas in cyclones. In one advantageous embodiment, however, the waste gas is cleaned by means of cloth filter~ integrated in the head of tne granulator and arranged above the fluidized bed. This is a space-saving solution because the waste gases have to be cleaned in any event and the fine particles returned to the fluidized bed.
To ensure that only granules of the r~quired size are removed from the fluidized bed, another embodiment of the invention is characterized in that the granules are dis-charged from the fluidized bed through one or more classi-fiers. These classifiers are advantageously arranged in lS the feed section of the fluidized bed to save space.
Countercurrent gravity classifiers are particularly advan-tageous.
Aqueous preparations of useful materials and combina-tions thsreof from the field of wetting agents, det~rgents and/or cleaning products which are not damaged significant-ly, if at all, by brief exposure to water or steam at a material temperature of 100 to 120C are particularly suitable for use in the process according to the invention.
Components of this type which are not damaged by exposure to temperatures in the range mentioned for at least about 5 s to 5 mins. under the working conditions are particular-ly suitable useful materials. It is crucial that the period of exposure to temperatures in this range is kept so ~short in the process according to the invention that substantial damage to the material to be dried does not occur under the working conditions selected. For example, even surfactant compounds which are basically vulnerable to - hydrolysis are largely undamaged by exposure to these working conditions for a few seconds to a few minutes providing certain boundary conditions known to the relevant ~31)~)~0 .: !
WO 93/15813 18 PCT/~P93/00266 expert are observed. Thus, aqueous preparations of water-soluble and/or insoluble organic and/or inorganic useful materials from wetting agents, detergents and/or cleaning products which may be assigned, for example, to the follow-5 ing classes may be subjected to drying ~n the drying process according to the invention: surfactant or emul-sifier components, inorganic and/or organic builders or builder components, washing alkalis, fillers or neutral salts, fabric softeners, bleach activators, auxiliaries for improving the soil suspending power of the liquors, such as redeposition inhibitors or even a~rasives.
In one important embodiment, the process according to the invention is used to dry mixtures of useful materials for the production of laundry detergents. The aqueous starting materials to be dried contain washing-active surfactants together with builders and, optionally, washing alkalis and/or neutral salts. At least part of the multi-component mixtures used is capable of binding and/or fixing residual water, more particularly in the form of water of crystallization. As in the spray drying of laundry deter-gents/ the laundry detergent component of mixtures of the type in question is generally not exposed in its entirety to fluidized-bed spray granulation. This is precluded by the extreme temperature sensitivity of peroxide-containing bleach components, such as perborate monohydrate or tetra-hydrate, and corresponding other particularly temperature-sensitive components. Enzymes, fragrances, bleach acti-vators and other minor components are mentioned as further examples. Accordingly, the teaching of the present inven-tion also provides inter alia for the production of so-called multicomponent tower powders which co~tain a large part of the components making up the final detergent in admixture with one another, but which are subsequently treated or mixed with other, liquid and/or solid active components. Known examples of such liquid components are, ~3~ 0 , . , ;;
. . . .
~o 93/15813 19 PCT/EP93/00266 in particular, readily volatile nonionic surfactant compo-nents which, although no longer discharged into the envi-ronment with the waste gas in the process according to the invention, can nevertheless readily be added to the deter-gent as a whole by subsequent spraying onto absorbent granules which have been prepared in accordance with the invention.
General particulars of useful materials for direct or indirect use in the production of wetting agents, deter-gents and/or cleaning products using the principles accord-ing to the invention are given in the following with reference to typical components of modern laundry deter-gents.
Suitable anionic surfactants are, for example, soaps of natural or synthetic, preferably saturated, fatty acids.
Soap mixtures derived from natural fatty acids, for example coconut oil fatty acid, palm kernel oil fatty acid or tallow fatty acid, are particularly suitable. Soap mix-tures of 5~ to 100% saturated C12l8 fatty acid soaps and 0 to 50% oleic acid soap are preferred.
Other suita~le synthetic anionic surfactants are those of the sulfonate and sulfate type. The process according to the invention can have particular significance for corresponding compounds of vegetablP and/or animal origin.
Suitable surfactants of the sulfonate type are alkyl-benzene sulfonates (C915 alkyl), olefin sulfonates, i.e.
mixtures of alkene and hydroxyalkane sulfonates, and sul-fonates of the type obtained, for example, from Cl2l8 mono-olefins with a terminal or internal double bond by sulfona-tion with gaseous sulfur trioxide and subsequent alkaline or acidic hydrolysis of the sulfonation products. Also suitable are the alkane sulfonates obtainable from Cl2la alkanes by sulfochlorination or sulfoxidation and subse-quent hydrolysis or n~utralization or by addition of bisulfites onto olefins and, more particularly, the esters ~30~0 ., ,, ` . I
~o 93/15813 20 PCT/EP93/00266 of ~-sulfofatty acids ~ester sulfonates), for example the ~-sulfonated methyl ester~ of hydrogenated coconut oil, palm kernel oil or tallow fatty acids.
Other important surfactant and emulsifier components in this regard are the so-called disalts which may be obtained by-saponification of the above-mentioned ~-sul-fonated fatty acid methyl esters or by direct sulfonation of fatty acids, more particularly saturated C12l8 fatty acids.
Suitable surfactants of the sulfate type are the sulfuric acid monoesters of primary alcohols of natural and synthetic origin, i.e. of fatty alcohols, for example coconut oil fatty alcohols, tallow fatty alcohols, oleyl alcohol, lauryl, myristyl, palmityl or stearyl alcohol, or the C1020 oxo alcohols and those of secondary alcohols having the same chain length. Sulfuric acid monoesters of the alcohols of natural and/or synthetic origin ethoxylated in particular with 1 to 6 moles ethylene oxide are also suitable components. Such compounds as 2-methyl-branched Cgll alcohols containing on average 3.5 moles ethylene oxide are mentioned as an example of synthetic alcohols. Sul-fated fatty acid monoglycerides are also suitable.
The anionic surfactants may be present in the form of their sodium! potassium and ammonium salts and also as soluble salts of organic bases.
Suitable nonionic surfactants are adducts of 1 to 40 moles and preferably 2 to 20 moles ethylene oxide with l mole of an aliphatic compound essentially containing 10 to 20 carbon atoms from the group consisting of alcohols, car-boxylic acids, fatty amines, carboxylic acid amides or alkane sulfonamides. Of particular importance are the adducts of 8 to 20 moles ethylene oxide with primary alco-hols, for example with coconut oil or tallow fatty alco-hols, with oleyl alcohol, with oxo alcohols or with second-ary alcohols containing 8 to 18 and preferably 12 to 18 2~3~3~QO
~O 93/15813 21 PCT/EP93/00266 carbon atom~. In addition to the water-soluble nonionics, however, water-insoluble or substantially water-insoluble polyglycol ethers containing 2 to 7 ethylene glycol ether units in the molecule are also of interest, particularly when they are u.~ed together with water-solubl nonionic or anionic surfactants. In the process according to the invention, the tendency of nonionic surfactants such as these to be carried over can be taken into consideration by completely or partly applying components of this type to the granules obtained after fluidized-bed spray granula-tion. The same also applies in particular to ~ionionic surfactants liquid at room temperature.
Other suitable nonionic surfactants are alkyl glyco-sides corresponding to the general formula R-O-(G)~, in which R is a primary linear or branched aliphatic radical containing 8 to 22 and preferably 12 to 18 carbon atoms, G
stands for a glycose unit containing 5 or 6 carbon atoms and the degree of oligomerization x is between 1 and 10.
Suitable organic and inorganic builders are soluble and/or insoluble components showing a mildly acidic, neutral or alkaline reaction which are capable of precipi-tating or complexing calcium ions. Suitable and, in par-ticular, ecologically safe builders are finely crystalline synthetic zeolites of the type already mentioned. Other builder components which, in particular, may be used together with the zeolites include (co)polymeric polycar-boxylates, such as polyacrylates, polymethacrylates and, in particular, copolymers of acrylic acid with maleic acid, preferably those with 50% to 10% maleic acid. The molecu-lar weight of the homopolymers is generally in the range from 1,000 to 100,000 while the molecular weight of the copolymers is in the range from 2,000 to 200,000 and preferably in the range from 50,000 to 120,000, based on free acid. A particularly preferred acrylic acid/maleic 3S acid copolymer has a molecular weight of 50,000 to 100,000.
~3~0 ~O 93/15813 22 PC~P93/002~6 Suitable, but less preferred compounds of this clas~ are copolymers of acrylic acid or methacrylic acid with vinyl ethers, such as vinyl methyl ether, in which the acid makes up at least 50%. Other suitable builders are polyacetal carboxylic acids, fcr example of the type described in US-PSS 4,144,226 and 4,146,49~, and also polymeric acids which are o~tained by polymerization of acrolein and subsequent disproportionation with alkalis and which are made up of acrylic acid units and vinyl alcohol units or acrolein units~
Suitable organic ~uilders are, for example, polycar-boxylic acids which are preferably used in the form of their sodium salts, such as citric acid and nitrilotriace-tate (NTA), providing there are no ecological objections to their use.
In cases where a phosphate content can be tolerated, it is also possible to use phosphates, more particularly pentasodium triphosphate, and even pyrophosphates and orthophosphates which act primarily as precipitants for lime salts.
Suitable inorganic non-complexing salts are the bicarbonates, carbonates, borates or silicates of the alkali metals which are also known as "washing alkalis".
Of the alkali metal silicates, sodium silicates with an Na2O
to Sio2 ratio of 1:1 to 1:3.5 are particularly suitable.
From the remaining groups of typical detergent ingredients, components from the classes of redeposition inhibitors (soil suspending agents), neutral salts and ~abric soften-ers are particularly suitable for use in the process according to the invention.
Suitable redeposition inhibitors are, for example, carboxymethyl cellulose, methyl cellulose, methyl hydroxy- -ethyl cellulose and mixtures thereof. The above-mentioned sodium sulfate is cited as a typical example of a suitable representative- of the neutral salts. Suitable softeners Z~30~0 '. ........................................................ !
Wo 93/15813 23 PCT/EP9~/00266 are, for example, swellable layer silicates of the montmor-illonite type, for example bentonite.
As mentioned above, typical ingredients of detergents and cleaning preparations sensitive to high temperatures, such as bleaches based on per compounds, enzymes from the class of proteases, lipases and amylases, or bacterial strains or fungi, stabilizers, ragrances, temperature-sensitive dyes and the like, are best mixed with the granules obtained beforehand.
Examples and test results of the process according to the invention are described in detail in the following.
Figure 1 diagrammatically illustrates the test instal-lation. It consists essentially of a fluidizing chamber 1 comprising a split, separately feedable slotted diEfusor 2, a star wheel 3 for the removal of product and a tube-bundle heat exchanger 4 which is integrated in the fluidizing chamber 1 and which is installed above the slotted diffusor 2. A screw conv~yor 5 with a feed hopper 6 is used to return oversize material after grinding. The material to be dried, i.e. the slurry, is pumped from a heated tank to a one-component nozzle through the pipe 7 and sprayed into the fluidized bed.
A blower 8 transports steam through a heat exchanger -9 used for reheating (superheating) into the fluidizing chamber 1. A throughflow meter and controller 10 is arranged between the blower 8 and the heat exchanger 9.
The issuing steam is freed from dust in a cyclone 11 and is returned by another fan 12. The excess vapors are removed !from the circuit at 13. A connection 14 to the steam circulation pipe is provided for starting the test.
At the beginning of the test, so-called "tower powder"
was introduced as the bed material. It had been produced by conventional drying with hot air in a production spray drying tower (apparent density 550 g/l, residual moisture approx. 12%). The tower powder contained approx. 16% by ~3~ 0 I
~o 93/15813 24 PCT/EPs~/00266 weight surfactants, approx. 15~ by weight soda and 28%
zeolite NaA, approx. 2% waterglass, Sokalan~, and typical minor components.
After ths bed material had been fluidized with hot air, the detergent slurry was sprayed in (approx 30 ~gfh at 6 bar spraying pressure) through the one-component nozzle (bore diameter 0.7 mm). The solids component of the slurry contained the constituents mentioned above.
The initial moisture content of the slurry was 50%.
The moist waste air was partly removed from the circuit, but largely circulated, the circulated air stream being reheated in the heat exchanger 9 before the fluidized bed.
The air stream removed from the circuit was replaced by fresh air. The temperature of the air on entexing the fluidized bed was approximately 145C; its exit temperature was approximately 90C.
Some of the granules produced were removed from the fluidized bed by the star wheel 3, ground up and returned to the fluidized bed by the screw conveyor 5 as granulation nuclei. The residence time of the product in the fluidized bed was approximately 20 minutes.
When no further increase in apparent density was observed after several hours; the system was switched to drying with superheated steam. The steam was circulated in the same way as the air. The steam was again superheated by the heat exchanger 9 before the fluidized bed and the tube-bundle heat exchanger 4 arranged therein. The average steam entry temperature was 150C, the temperature of the steam on leaving the fluidized bed being 105~C. The throughput of slurry was 30 kg/h. The granules produced in the previous tests based on drying with air were used as the bed material at the beginning of the steam drying phase. The residence tim~ of the product in the fluidized bed was approximately 20 minutes.
The test results are set out in Tables 1 and 2.
;2~30~
~O 93/15813 25 PCT/EP93/00266 Table 1 shows the apparent densities of three samples taken from the fluidized bed:
Sample 3 at the end of the tests with air drying - 5 Sample 6 after drying with steam and lx bed exchange Sample 7 after drying with steam and 2x bed exchanges Table 1 Sample 3 6 7 Recycle gas Air Steam Steam Gas entry temperature (C) 140 150 152 Gas exit temperature (C) 100 108 108 Gas throughput ~operating m3/h) 635 940 945 Product throughput ~kg/h~ 30 30 30 DM in (% by weight) 50 50 50 DM out (~ by weight) 94.3 94.9 94.3 Apparent density ~g/l) 687 780 820 DM = Dry matter content As can be seen, there.is a distinct increase in the apparent density from 687 g/l in the case of sample 3 to 782 g/1 in the case of sample 6 and finally to 820 g/l in the case of sample 7. In every case, the residual moisture content was approx. 5% (as measured by infrared drying for 7 mins. at 135C).
The sieve analyses (Table 2) indicate a shift towards larger particles in the steam drying phase.
Photographs taken with an optical microscope show that the air-dried particles have a much smoother and more uniform surface than the steam-dried particles. At the 2~3~
Wo 93~15813 26 PCT/~P93/00266 same time, photographs of the part.icle interior shew that the air-dried granules have fewer and smaller pores than the steam-dried granules. This results in considerably ~
better solubility of the steam-dried particles. ~;
There was no sign of any caking on the heat exchanser
Earlier patent application DB-A 40 30 688 describes a process for obtaining fine-particle, solid, pourable or flowable useful materials or mixtures thereof for wetting agents, detergents andJor cleaning products from aqueous preparations of the materials, in which superheated steam is used as the drying ho~ gas stream and drying of the particulate material i5 terminated before it is damaged by heat. If necessary, the long-term pourability or flowabil-ity of the material thus partly dried is established by addition of mixture constituents which are capable of binding limited quantities of water. In addition to or instead of this measure, the particulate material may also be aftertreated to homogenize its residual moisture content and/or subsequently dried under moderate conditions.
However, spray drying is used for the production of granules in this earlier application. Fluidized-bed drying -is merely mentioned as an option for the aftertreatment of the dried material. ;
The present invention, which is described hereinafter, -relates to a specific embodiment of the process according to the earlier application cited above. In the interests of full and complete disclosure of the invention, the dis-closure of this earlier application is specifically in-cluded in the disclosure of the present invention.
It is important in this connection to bear in mind the fact that practical experience in the application of drying processes using superheated steam as the drying gas has ;-Ibeen very llmited up till now although, basically, this technology has been known since the beginning of this century and has been repeatedly described in the litera- j ture. Earlier application DE-A 40 30 688 deals in detail with the relevant prior-art literature. Reference is made here to the corresponding observations in the earlier application and solely to the following publications which z~30~0 .
Wo 93/15813 6 PCT/BP93/00266 in turn cite numerous publications on this sub~ect: A.M.
Trommale~ et al. "Ev~poration an~ Drying of Drop~ in ~uper-heate~ V~pors~' AIChE Journal ~6 tl970) 857 867; Col~ Beeby ~t ~1. "~T~ 1 DRYING" Pl~n~ry Lecture, Pro~s. 4th Int.
5 Drying 8y~n. Ryoto ~a~. R,, Toei and Arun ~. ~u~ a~-) lQ~, Vol. 1, 51-68 ~nd W.A. ~tei~ "Berechnung der Verdampfung ~on Flu~igkait au~ feuahte~ Produkte~l im 8pruhturDI (C~lcu-latiIIg the 13vaporation of Liquid from Moi~t Products in ~pr y Drying ~ow~r~", Verf~hr~nYtechnik 7 (1973), 262-267.
There is a fundamental difference between drying with hot air and drying with superheated steam which is crucial to the understanding of the invention: where hot air is used, the drying process begins effectively at relatively low material temperatures. The removal of water is so pronounced that drying is almost complete on reaching a material temperature of around 100C. For example, up to about 90% of the total water present has already been removed from the droplet by this time. The temperature profile of the droplet is completely different where superheated steam is used. By condensation of the super-heated steam on the cooler starting material and release of the heat of condensation to the material to be dried, the aqueous drop is spontaneously heated to the boiling temper-ature of the water under the operating conditions, i.e. to temperatures of ~round 100C where drying is carried out under normal pressure. This boiling temperature is main-tained as a minimum temperature in the drop of material - throughout the entire drying pro~ess. The particular level of charging of the aqueous phase with the dry materialc to be obtained leads to individual upward deviations of the temperature profile at an earlier or later stage, depending on the degree of drying of the drop.
In the process according to the invention, in which certain limitations regarding the result of drying in the 3 end product are intentionally accepted, use is made of the 3~ 0 WO 93~15813 7 PCT/BP93/00266 various advantages of replacing hot air by superheated steam in fluidized-bed spray granulation precisely in the case of the temperature-sensitive material with which the invention is concerned. According to the invention, a crucial element in this regard is the acceptance in the dried material of residual moisture contents which can be quite considerable, depending on the particular case, and at the same time the establishment of the long-term pour-ability and flowa~ility of the granular material thus dried either by optional auxiliaries and/or by an aftertreatment, for example after~drying. The auxiliaries used may in turn be selected useful materials for the application envisaged or inert materials, as will be explained hereinafter.
According to the invention, it is thus possible to maintain the quality standards of the well known complex require-ments which the multicomponent mixtures based on organic and inorganic components, for example laundry detergents, with which the invention is concerned, are expecte~ to satisfy without any reduction in quality and without losing any of the advantages of drying with superheated steam.
Oxidation processes involving vulnerable components of the - wetting agents, detergents and cleaning preparations are suppressed, dangers of fire and explosions are eliminated.
Since the drying steam is circulated, no unwanted compo-nents are discharged into the surrounding atmosphere. Only the vapors formed from the material to be dried have to be removed from the circuit and cleaned. Any fractions of material removed in the process are utilised. Other tech-nological advantages regarding the design of the corre-sponding apparatus can also be utilized.
The energy introduced into the steam circuit outsidethe fluidized bed may be introduced in any known form, althouqh indirect heat transfer is preferred. The use of tube-bundle systems, throu~h which heating gases of any origin on the one hand and - separately therefrom - the 2~3~ 0 ~O 93/15813 8 PCT/~P93/00266 steam to be heated on the other hand flow, is mentioned as an example.
In one particularly important embodiment of the invention, this indirect introduction of energy into the steam circuit is carried out by one or more ,ntegrated burners with indirect transfer of heat to the steam, the hot combustion gases heing directly introduced into the heat exchanger - integrated in the steam circuit - on the burner side. The temperature of the combustion gases may be, for example, in the range from about 400 to 1000C and, more particularly, is in the range from about 650 to 960C.
In the interests of optimal heat utilization and hence to reduce the costs of the process as a whole, it can be useful if the waste gases are also partly and, preferably, substantially completely circulated. For example, at least 30% by volume and preferably more than 40% by volume of the hot waste gases can be recirculated after leaving the integrated heat exchanger for the further utilization of energy. The quantity of waste gases recirculated preferab-ly amounts to more than 60% by volume and often to around 70% by volume of the combustion gases introduced. The burner may be operated with any of the usual fuel gases, more particularly natural gas or comparable lower hydrocar-bons or hydrocarbon mixtures and/or hydrogen.
In the process according to the invention, thermal energy is mainly supplied to the superheated steam through internal or external heat exchangers, the superheated steam serving as transfer medium. The reliable and total absence of pollutants, particularly oxygen and carbon dioxide, in the drying gas ensures that the material to be dried does not undergo unwanted oxidation and also rules out the formation of carbonate salts or carbonate deposits that are unavoidable in the mostly basic useful materials with which the invention is concerned where drying gases containing waste gas are used. The use of heat exchangers integrated 2~30~0 WO 93/15813 9 PCT/EP~3/00266 in the fluidized bed for additional heating provides for the particularly effective transfer of heat and for a considerably lower steam temperature than heating solely by introduction of superheated steam to obtain the same residual moisture content so that thermal stressing of the material to be dried i5 minimal. This variant of the process is particularly suitable for drying materials of medium temperature sensitivity. In the drying of thermally more sensitive useful materials and mixtures thereof, it is of greater advantage to use only external heat exchangers with shorter` residence times than in the case of heat exchangers integrated in the fluidized bed.
The process according to the invention is carried out in a closed-loop system with a steam circuit from which the water evaporated from the starting material is removed while the energy released in particular in the drying step is returned to the circuit. In one important embodiment, the steam removed is first freed from entrained fractions of the starting material and put to another use as process steam~ if desired after its temperature and pressure have been adapted to the conditions prevailing there. In another embodiment of the process according to the inven-tion, it is useful to condense at least part of the steam removed. The aqueous liquid phase accumulating together with the fractions of the useful material present therein (having been removed from the circuit) is used, preferably after concentration, for the preparation of the aqueous solutions and/or suspensions to be dried.
In another preferred embodiment, the process is carried out with internal pressures of the steam-filled system in the region of normal pressure. In this embodi-ment, however, such elevated pressures are established in the circuit that air can be reliably prevented from pene-tratin~ the steam-filled circuit, for example in damaged area~ which can never be completely ruled out in industrial ~3~ ) [)O
..
Uo 93/15813 10 PCT/~P93~00266 installations.
Working in the region of normal pressure enables the process to be carried out relatively free from complica-tions, even in industrial plants, with the necessar~ high throughputs per unit of time. Since foreign gas, particu-larly air, is unable to penetrate into the stea~-filled circulation system, secondary damage to the high product quality required is reliably avoided. Suitable working pressures are, for example, in the range up to about 150 mbar, preferably up to about 75 mbar and, more preferably, below 50 mbar excess pressure. The range from about 5 to 15 mbar excess pressure can be of particular advantage.
Drying with superheated steam in accordance with the invention is of course also possible in prinaiple at reduced pressures, particularly moderate reduced pressures, although in this case increased outlay on equipment is necessary for ensuring the absence of possible damaged areas in the circulation system which could initiate the unwanted penetration of air.
The fact that optimal drying results by the effect of superheated steam on the end process product are not necessary is a crucial aspect of the teaching according to the invention. Residual moisture contents, even of a significant level, can be tolerated providing the composi-tion of the material ensures that the residual water is bound so extensively by a form of "internal drying" that the long-term pourability and free flow of the dry material is guaranteed.
If the temperature sensitivity of the useful material or mixture of useful materials to be dried means that considerable quantities of water have to remain in the product subjected to the main drying process, so that this residual water may have to be bound to ensure the long-term pourability and free flow of the dried material, auxili-aries capable of fixing water, preferably in the form of 2~3~0 ~O 93/15813 11 PCT/EP93/00266 particulate solids, are used in accordance with the inven-tion. In this case, residual water may be fixed, for example, by binding as water of crystalliæation. However, limited quantities of water in solid particles of the type in question here can also be bound purely by absorption without causing any unwanted tackiness or adhesion of the particles to one another The auxiliaries are at least used in guantities sufficient to guarantee pourability and stability in storage despite the residual moisture present in the material.
In one embodiment of the invention, the aux:iliaries used to bind the residual water may be added to the dried fresh material, best immediately after it has left the granulator, and intensively mixed therewith. In a prefer-red embodiment, however, the auxiliaries are at leastpartly added to the aqueous solutions or suspensions before spray granulation in the fluidized bed. This particular embodiment may always be applied when the particular temperature sensitivity of the material to be dried allows drying to be carried out to such an extent that the residu-al moisture remaining in the product can be adequately absorbed and bound by the auxiliaries used.
In one embodiment of the process according to the invention of particular advantage in this regard, corre-sponding useful materials from the field of wetting agents,detergents and/or cleaning products which themselves are sufficiently immune to temperature are used as the auxilia-ries capable of binding residual water. Typical examples of such materials are inorganic materials capable of binding water of crystallization from the classes of builder components, washing alkalis and/or so-called fillers, for example silicate compounds capable of binding water of crystallization, more particularly zeolites. One example particularly characteristic of laundry detergents is detergent-quality zeolite NaA which has a calcium 2~L30~00 j`^ ~ I
binding power of 100 to 200 mg CaO/g (cf. D~ 2~ 12 837).
Examples of washing alkalis which bind water of crystal-lization are soda or sodium bicarbonate while sodium sulfate as neutral salt or fillers are capable of binding considerable ~uantities of water of crystallization.
However, in addition to or instead of the above-mentioned auxiliaries capable of binding water of crystallization, the residual water may also be bound by auxiliaries or corresponding useful materials capable of binding water by absorption. Thus, it is known that known starch- or cellulose-based redeposition inhibitors, fabric softeners, particularly those based on inorganic swellable silicates, and also a num~er of organic surfactant compounds which are solid under normal conditions are capable of absorbing considerable quantities of water without reacting by developing unwanted surface tackiness.
Depending on the temperature sensitivity of the useful materials or mixtures of useful materials used on the one hand and the nature and quantity of the auxiliaries used on the other hand, considerable residual water contents may remain in the dried material without endangering its long-term pourability and free flow. According to the inven-tion, therefore, drying with superheated steam is termi-nated at residual water contents of the materials removed from the fluidized bed in the range from about 1 to 20% by weight, residual water contents in the range from about 5 to 15% by weight being preferred. The ranges mentioned relate to the weight of the material discharged from the fluidized bed. In another preferred embodiment of the invention, the amount of residual water which is not bound as water of crystallization is limited to at most about 10%
by weight and preferably to no more than about 3 to 4% by weight. The foregoing observations on the percentages by weight apply in this case, too.
The working conditions of the process according to the 2~301~0 `
Wo 93/15813 13 PCT/EP93/00266 invention enable high temperatures of the circulated ~team phase to be applied in fluidized-bed drying. If the heat is introduced slowly via the steam phase, wor~ing tempera-tures in the range from about 270 to 350C in the steam - 5 phase are particularly suitable. These temperature values apply to the temperature of the optimally heated steam delivered to the fluidized bed.
Where a heat exchanger integrated into the fluidized bed is used, the heat is largely introduced throuqh this heat exchanger. The steam phase is used for fluidization.
In this case, the preferred steam entry temperatures are considerably lower, i.e. in the range from 150 to 180C.
The lower drying rate is equalized through the greater length and/or height of the bed and hence through the longer residence time in the drying zone. Accordingly, one of the two embodiments is more advantageous, depending on the temperature sensitivity of the material to be dried.
Considerations based largely on energy factors, including the intended su~sequent use of the steam to be removed from the circuit, determine the quantitative ratios between the quantity of water to be evaporated and the quantity of superheated steam delivered. Embodiments which provide only for a limited reduction in the steam tempera-ture after leaving the fluidized bed are possible in this regard whereas, in other embodiments, the thermal energy of the steam can be further utilized to reduce the temperature of the steam to the vicinity of the condensation tempera-ture. It is also possible, as known per se, to divide the fluidized bed into various zones: high-temperature and medium-temperature zones and also a cooling zone.
In one particularly interesting embodiment of the invention, the heat of condensation of the steam removed from the circuit is recovered and utilized. By adopting suitable measures, it is even possible to recycle the small amounts of useful material which have left the primary Z3.3~ )0 !
~o 93/15813 14 PC~/EP93/00266 steam circuit via the superheated steam removed therefrom.
To this end, the following procedure, for example, may be adopted using the heat of condensation of the steam removed from the circuit:
Using the heat of condensation of the steam removed from the circuit, the steam condensate is concentrated in a preferably multipl~-stage evaporation unit. The residual concentrate accumulating is returned to the primary process circuit. More particularly, this residual ~oncentrate may be added to the slurry of useful material to be dried by superheated steam.
If necessary, a residual gas phase charged with minimal quantities of useful material, which may possibly accumulate during condensation of the superheated steam removed from the primary circuit, may be subsequently worked up, for example by incineration or by treatment in - biofilters or in washing units. By this combination of substantially complete recycling of the particular streams and the reliable destruction of final residual traces, the process according to the invention makes it possible for the first time in the industrial field with which the invention is concerned to recover useful materials and mixtures of useful materials from the field of detergents and cleaning products free from waste air and free from pollu~ed wastewater.
In addition to or instead of using auxiliaries capable of binding residual water, the invention also provides for after-treatment of the partly dried granules initially obtained. The aftertreatment may be carried out by two methods which may even be combined with one another.
The first of these methods is based on the fact that the individual degree of drying of the particular particle in question is determined by its particle size. If, in accordance with the invention, the drying process is terminated at a time when considerable quantities of ~30~QO `~
WO 93/15~13 15 PCT/EP93/OQ266 residual moisture are still present in the material, integral consideration of the residual moisture content does only partial justice to reality. By differential consideration of the distribution of this residual moisture over the individual fractions of material, it has been found that the fine or ultrafine fractions can be dried very extensively or completely while the coarser fractions are still so moist that the material removed from the fluidized bed is not guaranteed long-term pourability and free flow. In one important embodiment of the process ~ ;
according to the invention, therefore, "after-drying" of the primary material from the fluidized bed is achieved by an additional, at least single-stage aftertreatment step which - without exposing the powder-form material to the risk of developing tackiness - leads to homogenization of the moisture content over the material as a whole irrespec-tive of the individual particle size. In this way, so much residual moisture can be introduced into the fine and ultrafine material from the still comparatively moist coarse particles of the material that, after this homogen-ization step, the long-term pourability and free flow of tha dried material are guaranteed without further quanti-ties of moisture having to be additionally eliminated from the bulk material.
This aftertreatment step may be carried out by any method which equalizes the moisture content of the indi-vidual particles and, at the same time, prevents them from adhering to one another. Circulation, mixing or shaking of the material initially obtained either continuously or dis-continuously are mentioned as examples of such methods.
Aftertreatment of the material in another following fluid-ized bed can be particularly suitable.
Any gases, preferably ambient air, may be used for this purpose. Damage to the material by oxidation and unwanted contamination of the waste air is minimal or non-~30 [:)00 . . . .
WO 93/15813 16 ~CT~P93/00266 existent and is easy to control. Since the material to be dried is removed from the fluidized bed at elevated temper-ature, typically of the order of 105-C, a further slight reduction in the residual moisture content can be obtained by this subsequent homogenization of moisture in a fluid-ized bed.
However, in addition to or instead of this auxiliary measure, provision can also be made in the process accord-ing to the invention for a further reduction in the residu-al moisture content by additional drying in one or morestages. The after-drying treatment is characterized in that it is carried out under conditions which do not damage the useful materials in the material to be dried. Examples of process parameters for reducing risk include reducing the temperature of the hot gas phase, dispensing with superheated steam as the hot gas and replacing it with drying gases of different origin, for example air and/or inert gas, and changing over to another drying technology.
The process of fluidized-bed spray granulation is based on the growth of nuclei which are either formed in the fluidized bed itself by non-colliding, solidifying spray droplets or are produced through abrasion of solid particles already present or which are delivered to the fluidized bed from outside. If the process is to be carried out continuously, uniform granulation conditions must prevail. All the granules removed from the fluidized bed have to be replaced by an equivalent number of new nuclei. On the other hand, the waste gas has to be freed I from fine particles of material entrained therein. How-ever, these fine particles are also nuclei. In order,therefore, to ensure equalization of the above-mentioned particle balance in a particularly simple and economic manner, the fine particles of material escaping from the fluidized bed with the waste gas are separated and returned to the fluidized bed as nuclei for the formation of gran-2~30~
.
WO 93/15813 17 ~CT/EP93/00266 ules, more particularly internally by means of a dustfilter arranged over the fluidized bed. The fine particles may be separated from the waste gas in cyclones. In one advantageous embodiment, however, the waste gas is cleaned by means of cloth filter~ integrated in the head of tne granulator and arranged above the fluidized bed. This is a space-saving solution because the waste gases have to be cleaned in any event and the fine particles returned to the fluidized bed.
To ensure that only granules of the r~quired size are removed from the fluidized bed, another embodiment of the invention is characterized in that the granules are dis-charged from the fluidized bed through one or more classi-fiers. These classifiers are advantageously arranged in lS the feed section of the fluidized bed to save space.
Countercurrent gravity classifiers are particularly advan-tageous.
Aqueous preparations of useful materials and combina-tions thsreof from the field of wetting agents, det~rgents and/or cleaning products which are not damaged significant-ly, if at all, by brief exposure to water or steam at a material temperature of 100 to 120C are particularly suitable for use in the process according to the invention.
Components of this type which are not damaged by exposure to temperatures in the range mentioned for at least about 5 s to 5 mins. under the working conditions are particular-ly suitable useful materials. It is crucial that the period of exposure to temperatures in this range is kept so ~short in the process according to the invention that substantial damage to the material to be dried does not occur under the working conditions selected. For example, even surfactant compounds which are basically vulnerable to - hydrolysis are largely undamaged by exposure to these working conditions for a few seconds to a few minutes providing certain boundary conditions known to the relevant ~31)~)~0 .: !
WO 93/15813 18 PCT/~P93/00266 expert are observed. Thus, aqueous preparations of water-soluble and/or insoluble organic and/or inorganic useful materials from wetting agents, detergents and/or cleaning products which may be assigned, for example, to the follow-5 ing classes may be subjected to drying ~n the drying process according to the invention: surfactant or emul-sifier components, inorganic and/or organic builders or builder components, washing alkalis, fillers or neutral salts, fabric softeners, bleach activators, auxiliaries for improving the soil suspending power of the liquors, such as redeposition inhibitors or even a~rasives.
In one important embodiment, the process according to the invention is used to dry mixtures of useful materials for the production of laundry detergents. The aqueous starting materials to be dried contain washing-active surfactants together with builders and, optionally, washing alkalis and/or neutral salts. At least part of the multi-component mixtures used is capable of binding and/or fixing residual water, more particularly in the form of water of crystallization. As in the spray drying of laundry deter-gents/ the laundry detergent component of mixtures of the type in question is generally not exposed in its entirety to fluidized-bed spray granulation. This is precluded by the extreme temperature sensitivity of peroxide-containing bleach components, such as perborate monohydrate or tetra-hydrate, and corresponding other particularly temperature-sensitive components. Enzymes, fragrances, bleach acti-vators and other minor components are mentioned as further examples. Accordingly, the teaching of the present inven-tion also provides inter alia for the production of so-called multicomponent tower powders which co~tain a large part of the components making up the final detergent in admixture with one another, but which are subsequently treated or mixed with other, liquid and/or solid active components. Known examples of such liquid components are, ~3~ 0 , . , ;;
. . . .
~o 93/15813 19 PCT/EP93/00266 in particular, readily volatile nonionic surfactant compo-nents which, although no longer discharged into the envi-ronment with the waste gas in the process according to the invention, can nevertheless readily be added to the deter-gent as a whole by subsequent spraying onto absorbent granules which have been prepared in accordance with the invention.
General particulars of useful materials for direct or indirect use in the production of wetting agents, deter-gents and/or cleaning products using the principles accord-ing to the invention are given in the following with reference to typical components of modern laundry deter-gents.
Suitable anionic surfactants are, for example, soaps of natural or synthetic, preferably saturated, fatty acids.
Soap mixtures derived from natural fatty acids, for example coconut oil fatty acid, palm kernel oil fatty acid or tallow fatty acid, are particularly suitable. Soap mix-tures of 5~ to 100% saturated C12l8 fatty acid soaps and 0 to 50% oleic acid soap are preferred.
Other suita~le synthetic anionic surfactants are those of the sulfonate and sulfate type. The process according to the invention can have particular significance for corresponding compounds of vegetablP and/or animal origin.
Suitable surfactants of the sulfonate type are alkyl-benzene sulfonates (C915 alkyl), olefin sulfonates, i.e.
mixtures of alkene and hydroxyalkane sulfonates, and sul-fonates of the type obtained, for example, from Cl2l8 mono-olefins with a terminal or internal double bond by sulfona-tion with gaseous sulfur trioxide and subsequent alkaline or acidic hydrolysis of the sulfonation products. Also suitable are the alkane sulfonates obtainable from Cl2la alkanes by sulfochlorination or sulfoxidation and subse-quent hydrolysis or n~utralization or by addition of bisulfites onto olefins and, more particularly, the esters ~30~0 ., ,, ` . I
~o 93/15813 20 PCT/EP93/00266 of ~-sulfofatty acids ~ester sulfonates), for example the ~-sulfonated methyl ester~ of hydrogenated coconut oil, palm kernel oil or tallow fatty acids.
Other important surfactant and emulsifier components in this regard are the so-called disalts which may be obtained by-saponification of the above-mentioned ~-sul-fonated fatty acid methyl esters or by direct sulfonation of fatty acids, more particularly saturated C12l8 fatty acids.
Suitable surfactants of the sulfate type are the sulfuric acid monoesters of primary alcohols of natural and synthetic origin, i.e. of fatty alcohols, for example coconut oil fatty alcohols, tallow fatty alcohols, oleyl alcohol, lauryl, myristyl, palmityl or stearyl alcohol, or the C1020 oxo alcohols and those of secondary alcohols having the same chain length. Sulfuric acid monoesters of the alcohols of natural and/or synthetic origin ethoxylated in particular with 1 to 6 moles ethylene oxide are also suitable components. Such compounds as 2-methyl-branched Cgll alcohols containing on average 3.5 moles ethylene oxide are mentioned as an example of synthetic alcohols. Sul-fated fatty acid monoglycerides are also suitable.
The anionic surfactants may be present in the form of their sodium! potassium and ammonium salts and also as soluble salts of organic bases.
Suitable nonionic surfactants are adducts of 1 to 40 moles and preferably 2 to 20 moles ethylene oxide with l mole of an aliphatic compound essentially containing 10 to 20 carbon atoms from the group consisting of alcohols, car-boxylic acids, fatty amines, carboxylic acid amides or alkane sulfonamides. Of particular importance are the adducts of 8 to 20 moles ethylene oxide with primary alco-hols, for example with coconut oil or tallow fatty alco-hols, with oleyl alcohol, with oxo alcohols or with second-ary alcohols containing 8 to 18 and preferably 12 to 18 2~3~3~QO
~O 93/15813 21 PCT/EP93/00266 carbon atom~. In addition to the water-soluble nonionics, however, water-insoluble or substantially water-insoluble polyglycol ethers containing 2 to 7 ethylene glycol ether units in the molecule are also of interest, particularly when they are u.~ed together with water-solubl nonionic or anionic surfactants. In the process according to the invention, the tendency of nonionic surfactants such as these to be carried over can be taken into consideration by completely or partly applying components of this type to the granules obtained after fluidized-bed spray granula-tion. The same also applies in particular to ~ionionic surfactants liquid at room temperature.
Other suitable nonionic surfactants are alkyl glyco-sides corresponding to the general formula R-O-(G)~, in which R is a primary linear or branched aliphatic radical containing 8 to 22 and preferably 12 to 18 carbon atoms, G
stands for a glycose unit containing 5 or 6 carbon atoms and the degree of oligomerization x is between 1 and 10.
Suitable organic and inorganic builders are soluble and/or insoluble components showing a mildly acidic, neutral or alkaline reaction which are capable of precipi-tating or complexing calcium ions. Suitable and, in par-ticular, ecologically safe builders are finely crystalline synthetic zeolites of the type already mentioned. Other builder components which, in particular, may be used together with the zeolites include (co)polymeric polycar-boxylates, such as polyacrylates, polymethacrylates and, in particular, copolymers of acrylic acid with maleic acid, preferably those with 50% to 10% maleic acid. The molecu-lar weight of the homopolymers is generally in the range from 1,000 to 100,000 while the molecular weight of the copolymers is in the range from 2,000 to 200,000 and preferably in the range from 50,000 to 120,000, based on free acid. A particularly preferred acrylic acid/maleic 3S acid copolymer has a molecular weight of 50,000 to 100,000.
~3~0 ~O 93/15813 22 PC~P93/002~6 Suitable, but less preferred compounds of this clas~ are copolymers of acrylic acid or methacrylic acid with vinyl ethers, such as vinyl methyl ether, in which the acid makes up at least 50%. Other suitable builders are polyacetal carboxylic acids, fcr example of the type described in US-PSS 4,144,226 and 4,146,49~, and also polymeric acids which are o~tained by polymerization of acrolein and subsequent disproportionation with alkalis and which are made up of acrylic acid units and vinyl alcohol units or acrolein units~
Suitable organic ~uilders are, for example, polycar-boxylic acids which are preferably used in the form of their sodium salts, such as citric acid and nitrilotriace-tate (NTA), providing there are no ecological objections to their use.
In cases where a phosphate content can be tolerated, it is also possible to use phosphates, more particularly pentasodium triphosphate, and even pyrophosphates and orthophosphates which act primarily as precipitants for lime salts.
Suitable inorganic non-complexing salts are the bicarbonates, carbonates, borates or silicates of the alkali metals which are also known as "washing alkalis".
Of the alkali metal silicates, sodium silicates with an Na2O
to Sio2 ratio of 1:1 to 1:3.5 are particularly suitable.
From the remaining groups of typical detergent ingredients, components from the classes of redeposition inhibitors (soil suspending agents), neutral salts and ~abric soften-ers are particularly suitable for use in the process according to the invention.
Suitable redeposition inhibitors are, for example, carboxymethyl cellulose, methyl cellulose, methyl hydroxy- -ethyl cellulose and mixtures thereof. The above-mentioned sodium sulfate is cited as a typical example of a suitable representative- of the neutral salts. Suitable softeners Z~30~0 '. ........................................................ !
Wo 93/15813 23 PCT/EP9~/00266 are, for example, swellable layer silicates of the montmor-illonite type, for example bentonite.
As mentioned above, typical ingredients of detergents and cleaning preparations sensitive to high temperatures, such as bleaches based on per compounds, enzymes from the class of proteases, lipases and amylases, or bacterial strains or fungi, stabilizers, ragrances, temperature-sensitive dyes and the like, are best mixed with the granules obtained beforehand.
Examples and test results of the process according to the invention are described in detail in the following.
Figure 1 diagrammatically illustrates the test instal-lation. It consists essentially of a fluidizing chamber 1 comprising a split, separately feedable slotted diEfusor 2, a star wheel 3 for the removal of product and a tube-bundle heat exchanger 4 which is integrated in the fluidizing chamber 1 and which is installed above the slotted diffusor 2. A screw conv~yor 5 with a feed hopper 6 is used to return oversize material after grinding. The material to be dried, i.e. the slurry, is pumped from a heated tank to a one-component nozzle through the pipe 7 and sprayed into the fluidized bed.
A blower 8 transports steam through a heat exchanger -9 used for reheating (superheating) into the fluidizing chamber 1. A throughflow meter and controller 10 is arranged between the blower 8 and the heat exchanger 9.
The issuing steam is freed from dust in a cyclone 11 and is returned by another fan 12. The excess vapors are removed !from the circuit at 13. A connection 14 to the steam circulation pipe is provided for starting the test.
At the beginning of the test, so-called "tower powder"
was introduced as the bed material. It had been produced by conventional drying with hot air in a production spray drying tower (apparent density 550 g/l, residual moisture approx. 12%). The tower powder contained approx. 16% by ~3~ 0 I
~o 93/15813 24 PCT/EPs~/00266 weight surfactants, approx. 15~ by weight soda and 28%
zeolite NaA, approx. 2% waterglass, Sokalan~, and typical minor components.
After ths bed material had been fluidized with hot air, the detergent slurry was sprayed in (approx 30 ~gfh at 6 bar spraying pressure) through the one-component nozzle (bore diameter 0.7 mm). The solids component of the slurry contained the constituents mentioned above.
The initial moisture content of the slurry was 50%.
The moist waste air was partly removed from the circuit, but largely circulated, the circulated air stream being reheated in the heat exchanger 9 before the fluidized bed.
The air stream removed from the circuit was replaced by fresh air. The temperature of the air on entexing the fluidized bed was approximately 145C; its exit temperature was approximately 90C.
Some of the granules produced were removed from the fluidized bed by the star wheel 3, ground up and returned to the fluidized bed by the screw conveyor 5 as granulation nuclei. The residence time of the product in the fluidized bed was approximately 20 minutes.
When no further increase in apparent density was observed after several hours; the system was switched to drying with superheated steam. The steam was circulated in the same way as the air. The steam was again superheated by the heat exchanger 9 before the fluidized bed and the tube-bundle heat exchanger 4 arranged therein. The average steam entry temperature was 150C, the temperature of the steam on leaving the fluidized bed being 105~C. The throughput of slurry was 30 kg/h. The granules produced in the previous tests based on drying with air were used as the bed material at the beginning of the steam drying phase. The residence tim~ of the product in the fluidized bed was approximately 20 minutes.
The test results are set out in Tables 1 and 2.
;2~30~
~O 93/15813 25 PCT/EP93/00266 Table 1 shows the apparent densities of three samples taken from the fluidized bed:
Sample 3 at the end of the tests with air drying - 5 Sample 6 after drying with steam and lx bed exchange Sample 7 after drying with steam and 2x bed exchanges Table 1 Sample 3 6 7 Recycle gas Air Steam Steam Gas entry temperature (C) 140 150 152 Gas exit temperature (C) 100 108 108 Gas throughput ~operating m3/h) 635 940 945 Product throughput ~kg/h~ 30 30 30 DM in (% by weight) 50 50 50 DM out (~ by weight) 94.3 94.9 94.3 Apparent density ~g/l) 687 780 820 DM = Dry matter content As can be seen, there.is a distinct increase in the apparent density from 687 g/l in the case of sample 3 to 782 g/1 in the case of sample 6 and finally to 820 g/l in the case of sample 7. In every case, the residual moisture content was approx. 5% (as measured by infrared drying for 7 mins. at 135C).
The sieve analyses (Table 2) indicate a shift towards larger particles in the steam drying phase.
Photographs taken with an optical microscope show that the air-dried particles have a much smoother and more uniform surface than the steam-dried particles. At the 2~3~
Wo 93~15813 26 PCT/~P93/00266 same time, photographs of the part.icle interior shew that the air-dried granules have fewer and smaller pores than the steam-dried granules. This results in considerably ~
better solubility of the steam-dried particles. ~;
There was no sign of any caking on the heat exchanser
4 in the fluidized bed or of product damage through direct contact with the heat exchanger tubes.
~abl~ 2: 8iev~ a~aly~qi5 Sample 3 6 7 :
Larger than 1.6 mm 9.8 46.5 31.4 :
Larger than 0.8 mm 46.9 43.3 56.7 ~.
Larger than 0.4 mm 27.6 8.3 10.9 Larger than 0.2 mm 8.9 1.3 0.8 Larger than 0.1 mm 3.4 0.5 0.3 0.1 mm or smaller 3.5 0.2 0.2 .~`
~3~'~QO
WO 93/15813 27 YCT~P93/00266 List of referen~e numer~ls 1 Fluidizing chamber 2 Slotted diffusor (diffusorj 3 Star wheel 4 Heat exchanger Screw conveyor 6 Feed hopper 7 Pipe 8 Blower 9 Heat exchanger Throughflow meter and controller 11 Cyclone 12 Fan 13 Excess vapors 14 Connection
~abl~ 2: 8iev~ a~aly~qi5 Sample 3 6 7 :
Larger than 1.6 mm 9.8 46.5 31.4 :
Larger than 0.8 mm 46.9 43.3 56.7 ~.
Larger than 0.4 mm 27.6 8.3 10.9 Larger than 0.2 mm 8.9 1.3 0.8 Larger than 0.1 mm 3.4 0.5 0.3 0.1 mm or smaller 3.5 0.2 0.2 .~`
~3~'~QO
WO 93/15813 27 YCT~P93/00266 List of referen~e numer~ls 1 Fluidizing chamber 2 Slotted diffusor (diffusorj 3 Star wheel 4 Heat exchanger Screw conveyor 6 Feed hopper 7 Pipe 8 Blower 9 Heat exchanger Throughflow meter and controller 11 Cyclone 12 Fan 13 Excess vapors 14 Connection
Claims (25)
1. A process for the production, more particularly the continuous production, of pourable free-flowing granules of useful materials or mixtures thereof, which are suitable as and/or for use in wetting agents, detergents and/or cleaning products from aqueous solutions and/or suspensions of such materials by fluidized-bed spray granulation in a hot fluidizing gas in the region of normal pressure, characterized in that superheated steam is used as the fluidizing gas, the granules are discharged from the granulator before they can be damaged by heat and the long-term pourability and flowability of the material thus dried is optionally established by addition of mixture constitu-ents capable of binding limited quantities of water and/or by an aftertreatment and in that the process is carried out in a closed-loop system comprising a steam circuit from which the water evaporated from the starting material is removed as a partial stream and the thermal energy released is returned.
2. A process as claimed in claim 1, characterized in that thermal energy is introduced into the superheated steam both through heat exchangers integrated in the fluidized bed and through external heat exchangers.
3. A process as claimed in claim 1, characterized in that, in the drying of useful materials particularly sensitive to heat or mixtures thereof, thermal energy is introduced into the superheated steam solely through external heat exchangers, the residence time in the exter-nal heat exchangers being shorter than in the case of heat exchangers integrated into the fluidized bed.
4. A process as claimed in any of claims 1 to 3, charac-terized in that the steam removed from the steam circuit is freed from particles of the starting material entrained therein and put to other uses as recycle steam.
5. A process as claimed in any of claims 1 to 4, charac-terized in that at least part of the steam removed from the steam circuit is condensed and is reused together with the useful materials present therein, optionally after prelim-inary concentration, for preparing the aqueous solutions and/or suspensions to be dried.
6. A process as claimed in any of claims 1 to 5, charac-terized in that the steam-filled system is operated under internal pressures in the region of normal pressure, but preferably under such high pressures that air is unable to penetrate into the system, for example in damaged areas, internal system pressures below about 50 mbar excess pressure being preferred.
7. A process as claimed in any of claims 1 to 6, charac-terized in that auxiliaries are used for at least partly binding the residual water present in the incompletely dried product so that the long-term pourability and free flow of the dried material is guaranteed, the auxiliaries in question being at least partly incorporated in the aqueous solutions or suspensions before the fluidized-bed spray granulation process.
8. A process as claimed in claim 7, characterized in that components of the wetting agent, detergent or cleaning product, more particularly builders, washing alkalis and/or fillers, are used as the auxiliaries for binding the residual water.
9. A process as claimed in any of claims 1 to 8, charac-terized in that the drying with superheated steam in the fluidized bed is terminated at residual water contents in the range from about 1 to 20% by weight and, more par-ticularly, in the range from about 5 to 15% by weight and, at the same time, the content of free water not bound as water of crystallization is limited to values of at most about 10% by weight, based on the weight of the material discharged from the fluidized bed.
10. A process as claimed in any of claims 1 to 9, the heat being introduced solely via the steam phase, characterized in that steam having an entry temperature of about 270 to 350°C is used as the fluidizing gas for the fluidized bed.
11. A process as claimed in any of claims 1 to 9, the heat being additionally introduced through heat exchangers integrated in the fluidized bed, characterized in that the entry temperature of the steam is in the range from 150 to 180°C.
12. A process as claimed in claim 16, characterized in that it is carried out with at least partial recovery of the heat of condensation of the steam removed from the circuit and preferably with recycling of the discharged fractions of material to the primary circuit substantially free from waste gas and polluted wastewater.
13. A process as claimed in any of claims 1 to 12, charac-terized in that the residual moisture content of the granules obtained is homogenized in an at least one-stage aftertreatment step.
14. A process as claimed in claim 13, characterized in that the residual moisture content is homogenized in another fluidized bed with air as the fluidizing gas.
15. A process as claimed in any of claims 1 to 10, charac-terized in that the granules still containing residual water are agglomerated and after-dried or aftertreated under conditions which do not affect the useful material.
16. A process as claimed in any of claims 1 to 11, charac-terized in that the fine particles escaping from the fluidized bed with the waste gas are separated and returned to the fluidized bed as nuclei for granule formation, more particularly internally by means of a dust filter arranged over the fluidized bed.
17. A process as claimed in claim 16, characterized in that the waste gas is cleaned by cloth filters integrated in the head of the granulator and arranged above the fluidized bed.
18. A process as claimed in any of claims 1 to 17, charac-terized in that the granules are discharged from the fluidized bed through one or more classifiers, more par-ticularly countercurrent gravity classifiers, arranged in particular in the feed plate of the fluidized bed.
19. A process as claimed in any of claims 1 to 18, charac-terized in that aqueous preparations of useful materials or combinations of useful materials which are not damaged by brief exposure to water and steam at temperatures of 100 to 120°C and which, in the formulation used, withstand temper-atures in this range without damage for at least 5 s to 5 minutes are used.
20. A process as claimed in any of claims 1 to 19, charac-terized in that aqueous preparations of water-soluble and/or insoluble organic and/or inorganic useful materials from wetting agents, detergents and/or cleaning products, such as surfactants and emulsifiers, inorganic and/or organic builders or builder components, washing alkalis, fillers or neutral salts, fabric softeners, bleach acti-vators, auxiliaries for improving soil suspending power, such as redeposition inhibitors and abrasives, are sub-jected to the process.
21. A process as claimed in any of claims 1 to 20, charac-terized in that individual components of organic or inor-ganic character selected as useful materials from the classes of surfactants and emulsifiers or builders, more particularly from the field of useful materials for laundry detergents, are obtained as the free-flowing dry material.
22. A process as claimed in any of claims 1 to 21, charac-terized in that mixtures of useful materials for the production of laundry detergents containing surfactants together with builders and, optionally, washing alkalis and/or neutral salts are dried, at least part of the multicomponent mixtures being capable of binding and/or fixing residual water.
23. A process as claimed in any of claims 1 to 22 for the production of free-flowing surfactant solids, more particu-larly anionic surfactants based on natural materials, which are present in particular in admixture with soluble inor-ganic salts for ensuring free flow and/or pourability.
24. A process as claimed in any of claims 1 to 22 for the production of dried silicate-based useful materials which may be used in particular in laundry detergents and which comprise corresponding swellable and/or non-swellable representatives, such as layer silicates and/or zeolite compounds, more particularly detergent-quality zeolite NaA.
25. A process as claimed in any of claims 1 to 22 for the production of laundry detergent tower powders to which temperature-sensitive and or steam-volatile components are added for the production of the final laundry detergents.
Applications Claiming Priority (8)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE19924204090 DE4204090A1 (en) | 1992-02-12 | 1992-02-12 | SIMPLIFIED DRYING PROCESS FOR RECYCLING MATERIALS AND RECYCLING MATERIALS FROM THE AREA OF DETERGENT AND CLEANING AGENTS WITH OVERHEATED WATER VAPOR |
| DEP4204090.6 | 1992-02-12 | ||
| DEP4204035.3 | 1992-02-12 | ||
| DE4204035A DE4204035A1 (en) | 1992-02-12 | 1992-02-12 | IMPROVED METHOD FOR DRYING RECYCLING MATERIALS FOR DETERGENT AND CLEANING AGENT WITH OVERHEATED WATER VAPOR |
| DE19924206050 DE4206050A1 (en) | 1992-02-27 | 1992-02-27 | Drying wetting, washing and/or cleaning agent or component |
| DEP4206050.8 | 1992-02-27 | ||
| DE4206521A DE4206521A1 (en) | 1992-03-02 | 1992-03-02 | Drying wetting, washing and/or cleaning agent or component |
| DEP4206521.6 | 1992-03-02 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2130000A1 true CA2130000A1 (en) | 1993-08-19 |
Family
ID=27435391
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002130000A Abandoned CA2130000A1 (en) | 1992-02-12 | 1993-02-04 | A process for the production of granules suitable as wetting agents, detergents and/or cleaning products |
Country Status (11)
| Country | Link |
|---|---|
| US (1) | US5519948A (en) |
| EP (1) | EP0625921B1 (en) |
| JP (1) | JPH07503892A (en) |
| KR (1) | KR950700104A (en) |
| AT (1) | ATE135932T1 (en) |
| AU (1) | AU3494793A (en) |
| BR (1) | BR9305861A (en) |
| CA (1) | CA2130000A1 (en) |
| DE (1) | DE59302061D1 (en) |
| ES (1) | ES2086219T3 (en) |
| WO (1) | WO1993015813A1 (en) |
Families Citing this family (21)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE4340015C2 (en) * | 1993-11-24 | 1996-07-04 | Henkel Kgaa | Process for the production of anhydrous, free-flowing sugar surfactant powder and their use |
| WO1995014519A1 (en) * | 1993-11-24 | 1995-06-01 | Henkel Kommanditgesellschaft Auf Aktien | Process for producing anhydrous pourable sugar tenside powders |
| GB9606913D0 (en) * | 1996-04-02 | 1996-06-05 | Unilever Plc | Surfactant blends processes for preparing them and particulate detergent compositions containing them |
| US6122841A (en) * | 1998-05-07 | 2000-09-26 | Asj Holding Aps | Apparatus for the drying of moist particulate material in superheated steam |
| DE19911040A1 (en) * | 1999-03-12 | 2000-09-21 | Cognis Deutschland Gmbh | Surfactant granules |
| GB9913546D0 (en) | 1999-06-10 | 1999-08-11 | Unilever Plc | Granular detergent component containing zeolite map and laundry detergent compositions containing it |
| US20080000215A1 (en) * | 2000-03-02 | 2008-01-03 | Duncan Ronnie J | Engine systems and methods |
| DE10012949A1 (en) * | 2000-03-16 | 2001-09-27 | Henkel Kgaa | Mixtures of cyclic and linear silicic esters of lower alcohols and fragrance and/or biocide alcohols are used as fragrance and/or biocide in liquid or solid laundry and other detergents and in skin and hair cosmetics |
| US6837970B2 (en) | 2001-12-18 | 2005-01-04 | Kimberly-Clark Worldwide, Inc. | Wood pulp fiber morphology modifications through thermal drying |
| DE10256530A1 (en) * | 2002-12-04 | 2004-06-24 | Degussa Ag | Process for the preparation of anhydrous alkali sulfide |
| US20040203308A1 (en) * | 2003-04-09 | 2004-10-14 | Ko Young Chan | Process for making absorbent material |
| DE102004019264B4 (en) | 2004-04-21 | 2008-04-10 | Stockhausen Gmbh | Process for the preparation of an absorbent polymer by means of spread drying |
| EP1793187B1 (en) * | 2004-09-21 | 2011-11-23 | Vives Joan Iglesias | Method and machine for the sintering and/or drying of powder materials using infrared radiation |
| US20080005923A1 (en) * | 2006-07-07 | 2008-01-10 | Arthur Zwingenberger | Apparatus and method for drying instruments using superheated steam |
| EP2215200A2 (en) * | 2007-11-20 | 2010-08-11 | Emery Oleochemicals GmbH | Method for producing an organic composition containing an n-nonyl ether |
| IL204790A (en) * | 2010-03-28 | 2014-07-31 | Airgreen Ltd | Method of processing and drying waste in a cyclic continuous process |
| AT514275B1 (en) * | 2013-05-07 | 2015-05-15 | Andritz Tech & Asset Man Gmbh | Process for the production of salts with reduced content of water of crystallization |
| CA3005285A1 (en) * | 2015-12-11 | 2017-06-15 | Basf Se | Process for manufacturing granules |
| WO2018147361A1 (en) * | 2017-02-09 | 2018-08-16 | 株式会社アルバック | Vacuum drying apparatus and vacuum drying method |
| KR20220125354A (en) * | 2020-01-13 | 2022-09-14 | 리오 틴토 알칸 인터내셔널 리미티드 | Material handling apparatus and process using hydrogen |
| CN115151663A (en) * | 2020-01-13 | 2022-10-04 | 力拓加铝国际有限公司 | Calcination apparatus and process using hydrogen |
Family Cites Families (11)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US1787402A (en) * | 1927-02-25 | 1930-12-30 | Pilot Lab Inc | Bleaching agent and process of making the same |
| US2843942A (en) * | 1953-12-07 | 1958-07-22 | Phillips Petroleum Co | Process for drying wet carbon black pellets |
| US3212197A (en) * | 1961-06-08 | 1965-10-19 | James R Crawford | Drying method and apparatus |
| US3238634A (en) * | 1962-04-09 | 1966-03-08 | Phillips Petroleum Co | Process and apparatus for drying wet particulate solids |
| US4052794A (en) * | 1971-06-18 | 1977-10-11 | Struthers Scientific And International Corporation | Fluidized bed process |
| AT330930B (en) * | 1973-04-13 | 1976-07-26 | Henkel & Cie Gmbh | PROCESS FOR THE PRODUCTION OF SOLID, SPILLABLE DETERGENTS OR CLEANING AGENTS WITH A CONTENT OF CALCIUM BINDING SUBSTANCES |
| DE3565475D1 (en) * | 1984-04-07 | 1988-11-17 | Bayer Ag | Process and apparatus for the production of granules |
| JPS614795A (en) * | 1984-06-18 | 1986-01-10 | Ebara Infilco Co Ltd | Method for producing solid fuel from organic sludge |
| US4793783A (en) * | 1987-01-20 | 1988-12-27 | The Dow Chemical Company | Apparatus for producing prills |
| DE3803109C2 (en) * | 1988-02-03 | 1998-10-08 | Eirich Maschf Gustav | Process for drying moist material |
| DE4030688A1 (en) * | 1990-09-28 | 1992-04-02 | Henkel Kgaa | PROCESS FOR SPRUE DRYING OF MATERIALS AND MATERIAL MIXTURES USING OVERHEATED WATER VAPOR |
-
1993
- 1993-02-04 WO PCT/EP1993/000266 patent/WO1993015813A1/en active IP Right Grant
- 1993-02-04 JP JP5513750A patent/JPH07503892A/en active Pending
- 1993-02-04 AU AU34947/93A patent/AU3494793A/en not_active Abandoned
- 1993-02-04 CA CA002130000A patent/CA2130000A1/en not_active Abandoned
- 1993-02-04 ES ES93903908T patent/ES2086219T3/en not_active Expired - Lifetime
- 1993-02-04 AT AT93903908T patent/ATE135932T1/en not_active IP Right Cessation
- 1993-02-04 KR KR1019940702787A patent/KR950700104A/en not_active Application Discontinuation
- 1993-02-04 EP EP93903908A patent/EP0625921B1/en not_active Expired - Lifetime
- 1993-02-04 DE DE59302061T patent/DE59302061D1/en not_active Expired - Fee Related
- 1993-02-04 US US08/284,613 patent/US5519948A/en not_active Expired - Fee Related
- 1993-02-04 BR BR9305861A patent/BR9305861A/en not_active Application Discontinuation
Also Published As
| Publication number | Publication date |
|---|---|
| BR9305861A (en) | 1997-02-18 |
| EP0625921A1 (en) | 1994-11-30 |
| JPH07503892A (en) | 1995-04-27 |
| WO1993015813A1 (en) | 1993-08-19 |
| ES2086219T3 (en) | 1996-06-16 |
| KR950700104A (en) | 1995-01-16 |
| ATE135932T1 (en) | 1996-04-15 |
| AU3494793A (en) | 1993-09-03 |
| US5519948A (en) | 1996-05-28 |
| DE59302061D1 (en) | 1996-05-02 |
| EP0625921B1 (en) | 1996-03-27 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| FZDE | Discontinued |