Patente US5725835 - Device for initiating and/or promoting chemical or physical processes in a ...

DEVICE FOR INITIATING AND/OR
PROMOTING CHEMICAL OR PHYSICAL
PROCESSES IN A MATERIAL

BACKGROUND OF THE INVENTION 1. Field of the Invention

The invention relates to a microwave heating device and more it concerns novel arrangements for moving a container for materials to be heated between loading and heating positions.

DESCRIPTION OF THE RELATED ART

In analytical chemistry and in particular for the preparation of materials, preferably specimen materials, or for the transformation of initial materials into reaction products it is common practice to perform the treatment under heat and pressure (excess pressure) as the desired process can only be realized or improved or forced under these conditions.

In a device are described in the DE-A-39 33 992. by irradiation of a gas under pressure with long wavelength electromagnetic waves a shorter wavelength radiation is generated with which the initial materials are irradiated, or the initial materials themselves are placed under reduced pressure and are irradiated directly with the long wavelength electromagnetic waves. For this purpose there serves a device with a heating chamber surrounded by a housing on all sides and closeable in a sealed manner in which an initial material introduced into an open or closeable receptacle can be heated under reduced pressure which is generated by an air pump connected with the heating chamber (FIG. 1 and 4) or, in the case of a closeable receptacle, connected with the receptacle (FIG. 2 and 3 of this publication) by means of an evacuation line.

A device of the kind mentioned in the introduction can be found in DE 40 38 273 Al in various configurations in which, for the purpose of opening a housing surrounding the reaction chamber, the side wall (FIG. 1). lid (FIG. 2) or base (FIG. 3) of the housing in DE 40 38 273 Al is displaceable by means of a displacement device between the closed position and an open position. There is arranged, on the respective wall part of the housing which is to be opened, a mounting, e.g. a locating plate, for at least one specimen receptacle, so that the latter can be moved into the reaction chamber or out of it with the respective displacement movement of the wall part. Through this the placement and removal of at least one specimen receptacle in the reaction chamber or the housing is facilitated, but a special mounting for the at least one specimen receptacle is necessary. Also a simple positioning of the specimen receptacle(s) on the floor of the housing is not possible. Furthermore on account of the presence of the mounting device and also for further constructional reasons this known device is not constructed in a way that would allow the placing of the specimen material directly in the housing, i.e. without a special specimen receptacle. A further disadvantage of the known device is to be seen in that in the configuration with a liftable lid for the reaction chamber (FIG. 2) the accessability to the reaction chamber is very much restricted in the open position: although the lid is lifted from the housing, because of its position above the housing the accessability of the upperside housing opening is made more difficult.

A device of the kind under consideration can be found in WO/93/22650 in several configurations, in which, for receiving several pot-like specimen receptacles, a mounting device is provided in the form of a rotor in a reaction chamber, whereby the specimen receptacle can be inserted.

by a horizontal movement, between a positioning plate engaging below the specimen receptacle and a lid which engages above the specimen receptacle—with its upper side opening—thereby effecting closure. The latter lid is part of

5 the mounting device, which remains on the mounting device upon removal of the specimen receptacle. With this known device it is necessary to manually grasp the specimen receptacle upon insertion or withdrawal from the mounting device, which is possible only with difficulty in particular

10 after the material treatment if only on account of the increased temperature. Furthermore it must be taken into consideration that the specimen material must be inserted into the mounting device purposively. Furthermore this known device is not suitable for a reaction chamber of larger

15 dimensions, as manual handling is not possible on account of the resulting weight. In the event that several specimen materials are to be treated simultaneously several specimen receptacles are therefore required with this known configuration, which must be purposively inserted into their

20 working positions with respective horizontal movements and withdrawn again after the treatment.

SUMMARY OF THE INVENTION

The object of the invention is further to configure a device

25 of the kind mentioned in the introduction in such a way that a more simple loading of the reaction chamber is possible.

This object is by means of a generally horizontal guide for displacing a material containing housing underpart relative to a lid after a lifting device has begun to lift the lid from a

30 closed or working position and a ready position.

With this embodiment according to the invention the housing underpart which encloses the reaction chamber or its lid is displaceable into an opening ready position not only

35 by means of a lifting device, but the housing underpart or the lid is also displaceable approximately horizontally into a loading position and back again, so that the accessability of the reaction chamber is significantly improved and thus the specimen material or specimen materials can be placed directly or in specimen receptacles into the reaction chamber in a simple and ready way. The displacement of the lid or the housing underpart can be effected manually or by means of a motorised drive. For the approximately vertical displacement of the lid or the housing underpart a motorised drive is

45 advantageous, as the weight involved must be overcome. Furthermore, such a displacement device can at the same time form the closure device for the housing. For the approximately horizontal displacement of the lid or the underpart of the housing a manual displacement in a guide

5Q is advantageous for the purpose of simplification of the device and its control.

In the subclaims there are features which contribute to achievement of the object, simplify construction, make possible a simpler, faster and thus more economical and

55 reliable treatment, improve energy consumption and economy and make possible an advantageous and reliable control of the treatment process.

Further, the invention relates to a particular construction of the device which is distinguished not only by a simple and

60 economical and compact construction, and convenient operation, but also ensures a high degree of utilization of the heating energy and can thus be operated economically and reliably.

Furthermore, the invention relates to a further advanta65 geous construction, in which the pressure regulation elements of the device are arranged in a particular constructional component which is separate from the reaction

3 4

chamber, which may be connected with the reaction cham- 13 which is detachably fastenabie to the housing underpart

ber merely by means of a connecting line, and to advanta- 12. The fastening device for the lid 13 on the housing

geous arrangements of pressure control elements such as underpart 12 is not illustrated for reasons of simplicity. It

valves, which ensure a trouble-free and reliable process may comprise either screws 11a which are schematically

development. 5 illustrated or oppositely arranged locking ring halves lib of

U-shaped cross-section which, horizontally opposed to one

BRIEF DESCRIPTION OF THE DRAWINGS another, are moveable between a closing position (shown) in

which they engage above the lid 13 and below the edge

Below, the invention and further advantages achievable flange 12a and an outwardly offset release position (not

thereby will be described in more detail with reference to shown) either by hand or by a motorised drive,

preferred exemplary embodiments and to the drawings, in The housing 11 is a metal housing. The microwave

which: coupling into the housing 11 is effected from below through

FIG. 1 is a device with a reaction chamber according to a base I4 °f toe housing, which base is preferably arched

the invention in largely schematic sectional side view; downwardly. A cooling device generally designated as 15 is

FIG. 2 is an exemplary embodiment of the reaction 15 ass«dat^ with the housing 11 which has one or several

chamber of the device of FIG. 1 in a vertical sectional view coolm8 ^ " coolmS channels ^n^d ***** mslde,°r

and to a larger scale; outside along the walls of the housing 11. through which a

__,„ „ . . . . , . coolant, in this case water, is delivered by means of a pump

FIGS. 3 to 5 are fragmentary views which show, in u and C£m be cookd in a 16fl

schematic, modifications of a lid and container actuation

arrangement according to the present invention; 20

The housing 13 is preferably lined on the inside with a

corrosion and heat resistant and preferably also heat

FIG. 6 is a perspective view, partially in section, of a insulating lining material. With the present exemplary

heating device according to the present invention which embodiment a pot-like lining part 17a which is adapted to

incorporates the lid and container actuation arrangement of the mner profile of me housing underpart 12 and a lining lid

FIG. 3; and ^ plate Ylb arranged on the lower side of the lid 13 are

FIG. 7 is an elevational view, partially in section, showing provided, which lining lid plate preferably engages into the

a reaction chamber used in the heating device of the present lining part 17a with a projection 17c projecting downwardly,

invention. Preferably there is present between the base part 17a" of

the lining part 17a and the base 14 of the underpart 12 of the

DETAILED DESCRIPTION OF THE ^ housjng ^ additional plate-shaped lining base part 17e of

PREFERRED EMBODIMENTS microwave permeable material and/or plastics. For coupling

The main parts of the device which is generally desig- me microwaves a preferably central opening 18 is provided

nated as 1, are the reaction chamber 2, a heating device 3, in me base 14. in or below which a magnetron 19 or a

in particular a microwave heating device, for the reaction waveguide or an associated radiation element such as an

chamber 2. a pressure loading device 4 for the reaction 35 antenna 19a is arranged. On the upper edge of the opening

chamber 2. a pressure control block 5 for controlling the 18 a bowl-shaped or hollow-ball section-shaped radiation

pressure in the reaction chamber 2, and a control device 6 for element 21 of microwave-permeable material, preferably

the functional control of the device 1, here in particular the quartz, is arranged which is positioned in a correspondingly

heating device 3 and the pressure acting, whereby the formed recess of toe P3* l7e- The" ^ ^so be

respective associated addressable control parts are con- 40 provided a radiation element in the form of a cylinder having

nected by means of control lines of the control device 6. a vertical axis, into which the antenna 19a penetrates in an

The material to be treated can be placed either directly or aperture with play for movement in one or in several receptacles in the reaction chamber 2. A t^T1? P3* for me housmS 1115 de^gnated as 20. Insofar as one or several receptacles 7 (FIG. 2) are available, on *luch *e housm8 18 and- rf ... fasit may be advantageous for handling reasons to associate a 45 tened

carrier frame, in particular of plastics or microwave perme- 111 toe exemplary embodiment in accordance with FIG. 2

able or semi-permeable material, with the receptacle(s) 7, is provided, to improve the sealing between the lining

with which they may be readily placed in the reaction ud Plate 17b and the uPPef edge of the lining part 17a, a

chamber 2 and removed again. sealing lip 17/, which is formed preferably in one piece on

„ . ... .. . , u 50 the lid plate 17b and engages into the lining part 17a and

For this purpose the reaction chamber 2 has an upper i- 1 u • . .if • n .1. ;TM ... , ,

... • * »u • ^ J A 1 cKu sealingly bears against the inner wall thereof. The lid plate

loading opening for the introduction and removal of the m , «_ j CJ. ,. ■

material to be treated. "* f° over*e uPPf ed«e of th5 kmn8 Pf

17a on the outside, in this case by means of an annular

In the present embodiment the device 1 is a microwave- projection Ylg projecting downwardly, which engages into

autoclave functioning with high temperature and high pres- J5 an outer recess of CQrreSpondillg cross-section on the upper

sure for the treatment or preparation of materials, in par- edge of me ]ining part 17(J ^ upper edge 17fl is thus

ticular specimen materials for analysis purposes. tapered and engages mto a corresponding annular groove 17i

For controlling the pressure in the reaction chamber 2 in the lid plate 17i>.

several valves are provided, which are arranged in the m me present embodiment in particular the base region of

separately arranged control block 5 which is connected with w the housing 11 is well heat-insulated by means of the base

the reaction chamber 2 by means of a connecting line 9. part 17^ and the additional base part lie. Therefore the

which may be either a rigid or a flexible pipeline or a hose cooling device IS is arranged merely laterally next to the

line, in particular of plastics. reaction chamber 2 in or on the sheath of the housing

The reaction chamber 2 is surrounded by a housing 11. underpart 12. here in the form of an annular cooling channel

which for the purpose of loading the reaction chamber 2 is 65 22 in the wall of the housing underpart 12 which in the

preferably formed of a pot-shaped housing underpart 12 present case is preferably circular in horizontal cross

with an edge flange 12a and a preferably substantially flat lid section.

5 6

Preferably the lid plate 17* sits on the lid 13 with an Preferably a further bypass 9*3 is provided in which an

upper-side centering member 17L in a corresponding lower- electrically or preferably manually operable valve V3 is

side recess. Furthermore, the lid 13 has a lower-side cen- arranged, which as a further safety valve serves for the

tering member 13a. in the present case a centering ring, purpose of reducing the pressure in the reaction chamber

which engages into the circumferential wall of the housing 5 after a treatment process, by opening the valve, thus

underpart 12 thus centering the lid 13 in its closed position. enabling the access to the reaction chamber, in the event that

In the region of the housing 11 two temperature sensors the preferably programm controlled valve VI should not

Tl, T2 are provided. The first temperature sensorTl is in the function, with which is also possible to reduce the pressure

base region of the housing underpart 12 and serves for af^r me treatment process.

determining actual values for the regulation of the heating 10 The bypasses 9*1. 9*2, 9b3 are arranged in parallel to one

power and thus also of the temperature in the reaction another. i.e. each bypass can function independently of the

chamber 2. others, which is ensured by the parallel connection.

The second temperature sensor T2 serves for determining In the control block 5 there is also arranged a pressure

the sheath temperature of the housing 11 and for the regu- sensor PI for detecting the pressure in the reaction chamber

lation of the cooling device IS, for the purpose of preventing 15 2, arranged in particular in the region of the connection line

an overheating of the material of the walls of the housing. 9. which faces the housing 11.

The connecting line 9 is connected with the upper region In the region away from the housing 11 the bypasses are

of the reaction chamber 2, whereby it penetrates the lid 13 rejoined to the common connection line branch 9b, the

preferably centrally in the present embodiment. A relatively connection line branch 9b discharging into a container or

thin nominal cross-section suffices for the connection line 9. chimney (not shown) in the further course of the discharge

Preferably this nominal cross-section is approx. 6 mm, direction (see arrow 29).

whereby the connecting line 9 can preferably be a flexible The material to be treated, in particular specimen material

line of plastics, in order to be able to move the lid 13 on 31, can be introduced loose or preferably in one or several

closing and opening. 25 receptacles 7 into the reaction chamber 2. In the present

With the exemplary embodiment in accordance with FIG. embodiment there are shown two receptacles 7 which are 2 the connection line 9 branches in a T-shaped fitting 26 °Pen on the upper side, are in particular of hollow cylindriwhich is fitted or screwed into the housing 11, from above, cal shape ^ nave a level receptacle base 7a, in which in here into the lid 13. from which a connection line branch 9a addition to the specimen material 31 an additional material extends to the loading device 4 and the other connection line 30 e I- a reaction promoting material, in particular a solid or branch 9b extends to the control block 5. In the first- liquid chemical 32 is further arranged. The horizontal crossmentioned connection line branch 9a there are arranged an sectional size, in this case the diameter of the like recepair- or gas pump 20 and a non-return valve 27 which opens tacles 7. is only a fraction of the cross-sectional size of the in a flow direction towards the reaction chamber 2 and closes reaction chamber 2, so that between the outer circumferenin the opposite direction. In the present embodiment the 35 tial walls of an individual receptacle 7 and the inner cirfeed-through channel 9c, which forms the common connec- cumferential walls of the reaction chamber 2, or between the tion line section—here in the lid 13. is lined with a sleeve 28, latter and several receptacles 7 and between the receptacles, preferably with an inner flange 28a, of temperature and tnere is a free sPace which is preferably filled with a corrosion-resistant material, preferably plastics. The fitting microwave absorbent, in particular liquid, indirectly effec26 and associated threaded rings 26a, 26b and the connec- 40 tive heating agent, in the present embodiment water 33. up tion line 9 are also of a temperature and corrosion-resistant t0 approximately the height of the filling level of the material, in particular of plastics. receptacles 7.

The connection line branch 9b has a first blocking or Preferably a further indirectly effective heating agent of

regulation valve V in the control block 5, the valve member microwave-absorbent material is provided, which in the

of which opens the branch 9b above a certain pressure or 45 present embodiment is a level heating plate 34, which rests

pressure range in the reaction chamber 2 with increasing on ^ Preferably level upper side of the housing base 17a*

pressure or closes it with decreasing pressure. The valve and on the level upper side 34a of which the receptacle(s) 7

body of this valve V can be acted upon through the force of ^in extensive physical contact and thus in large-area heat

a spring e.g. a plate spring 29 or a spiral spring into its conducting contact.

blocking position and can be opened through the pressure in so The function of the device 1 is as follows:

branch 9b. In parallel therewith in the control block 5 two or For the treatment, in particular the preparation of the

three bypasses are arranged, in which respective control material 31 this is introduced into the reaction chamber 2 as

valves are arranged. An electrically operable valve VI is described above and the housing 11 is closed. Thereafter the

associated with a first bypass 9bl and a preferably smaller treatment of the material 31 under excess pressure and heat

cross-sectional, which valve is electrically driven (open/ 55 can begin, whereby the excess pressure, the heat and the

close) or regulated in dependence of the pressure in the treatment can be controlled automatically or manually,

reaction chamber 2 in such a way that a certain pressure is For a treatment process the loading device 4 is firstly

not exceeded or a desired pressure value is maintained. A switched on, in order to generate an initial pressure in the

pressure-safety valve V2 is associated with a second bypass reaction chamber 2, in the present exemplary embodiment

9b2, which valve opens preferably abruptly above a higher, 60 an initial pressure of e.g. 80 to 100 bar, which can be

predetermined pressure in the reaction chamber 2. In the maintained through switching on the loading device 4 for a

present embodiment this valve V2 is a rupture disk, which certain time or through the pressure sensor PI or a further

ruptures when the above-mentioned safety pressure value is pressure sensor. The pressure is generated through introduc

exceeded and thus opens the bypass 9*2. The branch 9b is tion or pumping in of air or a gas. e.g. an inert gas such as

preferably dimensioned to be larger in cross-section than the 65 nitrogen. Thereafter the heating device 3 is switched on.

first bypass 9*1. The second bypass 9*2 is preferably whereby in the present case the material is heated by

dimensioned to be larger still than the branch 9b. microwaves directly from below (in as far as the material

concerned is a microwave absorbent material) and the heating agent 33 and the heating plate 34 is likewise directly heated. On account of evaporation or reaction of material there is a significant increase in pressure and temperature in the reaction chamber 2 or in the pressure chamber, whereby 5 the material treatment is performed under these conditions.

Devices are provided with which certain temperature and/or pressure values or temperature and pressure ranges can be set or regulated, in order to be able to cany out the treatment at a certain pressure and/or a certain temperature, to Thereby it must be taken into account that with regard to the effects of the above-mentioned measures, there are crossover effects since the temperature may influence the pressure just as the pressure may influence the temperature (taking into account material reactions). 15

It is advantageous to associate a processor with the control device 6 of the device 1 and to control the device in accordance with a program in such a way that a material treatment can be automatically performed.

Below, regularly occurring operating process steps or 20 operating process steps which are possible in dependence on pressure and temperature development will be described as an advantageous exemplary embodiment.

In a first processing step a loading pressure which may 25 range from zero to 150 bar is generated in the reaction chamber 2 as a starting condition, by switching on the pump 20. Hereby, an initial gas pressure may be generated which may e.g. be approximately 80 bar.

After reaching the loading pressure, which is detected by J0 means of the pressure sensor PI which delivers a corresponding signal to the control device 6, the heating device 6 is switched on as processing step two and the material is heated directly or indirectly in the above-described manner. An excess pressure is thereby generated in the reaction 35 chamber 2. in a range up to approximately 150 bar with a simultaneous rise in temperature, whereby the treatment process takes place or is forced. With an excess pressure of e.g. approximately 120 bar the pressure sensor PI supplies a further pressure signal for the regulation of the electrically ^ controllable valve VI, which in consideration of the pressure desired-value of 120 bar is actuated in the opening direction and in the blocking direction so that the desired pressure value is maintained. With this second processing step the heating power is also controlled or regulated (switch 45 on/switch off) in accordance with a desired temperature value so that the desired temperature value is not exceeded, preferably maintained.

In the case in which the pressure in the reaction chamber 2 exceeds the desired pressure value (120 bar), e.g. on 50 account of a strong process reaction, as a further process step three the heating power is reduced or switched off. e.g. at a pressure value of 140 bar.

In addition, as a further process step four, the pressure limiting valve V is provided, which operates at a pressure 55 higher than the desired pressure value, e.g. at approximately 150 bar. and limits the pressure to this pressure value. The pressure-limiting valve V can be regulated in such a way that it operates only when the regulation or controlling of the valve VI or the temperature regulation or control fails. ^

As a further safety valve, in accordance with the next process step five, the safety valve V2 is provided, which for the purpose of explosion protection opens or ruptures upon a sudden large pressure increase.

After completion of the process, the housing or reaction 65 chamber 2 is to be subject to pressure release, in order to make access possible. In accordance with a further process

step six. this can be achieved through opening the controllable valve VI or valve V3. The valve V3, which is arranged in the additional bypass 9b3, is preferably a manually operable valve in order to be able to perform the pressure reduction even in the event that the valve VI fails to function.

The control block 5. which is preferably pre-installable as a constructional unit B. is of pressure-resistant metal, in particular of steel. For the purpose of corrosion protection the channels 9b, 9bl. 9b2, 9b3 present in the control block 5 are lined with corrosion-resistant plastics. This may be effected in an advantageous manner in that firstly the channels are bored and are then lined with the plastics material, in particular by injecting the plastics. It is also possible to bore out the channels after their lining or to fill them with the plastics and then to bore out the plastics, so that the lining provides the channels.

Below, further details and advantages of the device according to the invention will be described.

The reaction chamber 2 is at the same time the pressure chamber and specimen chamber and it is protected from direct contact between the material and the pressureresistant pressure wall—in particular of stainless steel —of the housing 11 by means of an insulating lining. The lining is of a plastics, in particular of PTFE, and serves as thermal protection and corrosion protection. The inner lining as well as the circumferential wall can be cooled by means of the cooling device 15, for the purpose of avoiding damage caused by heat. In the reaction chamber, the initial pressure is built up before the beginning of the reaction in order to avoid condensation and losses through evaporation of materials, in particular of solvents. Through the heating of the material 31 with the heating device 3 a further pressure increase to a regulatable operating pressure is achieved. The thus achievable increased boiling points prevent losses of elements and compounds.

With spontaneous exothermal reactions the relatively large overall chamber volume, preferably approx. 3 to 3.5 dm3 provides an additional safety factor, as pressure peaks are avoided. Since, with the present embodiment, on account of the relatively large reaction chamber 2 a large quantity of material 31 can be introduced therein for treatment purposes, a relatively large heat of combustion may be released in the reaction chamber 2 during the treatment, which heat can however be taken up through the heat absorbing capacity of the indirectly effective heating agent 33 and through the relatively large chamber mass, so that temperature peaks arising from this cause are also avoided. Therefore, with the device according to the invention a large quantity of material 31 can be treated without functional problems arising.

With the device according to the invention, the receptacles 7 preferably made of plastics may be of simple and economically producible construction, since they are subjected to the same pressure conditions inside and outside. Thus, differing reactions are also avoided, in as far as they are dependent on differing pressure conditions. Also losses and entrainments from one receptacle to another are reduced to values which can be practically ignored, as the boiling point of the substances (solvents,, additional products etc.) is raised greatly on account of the pressure. I.e. treatments can be undertaken at increased temperatures and, despite this, with a closed system.

The measures according to the invention also lead to an automatic boiling point increase through a pressure increase of the liquid medium which forms the indirect heating agent 33. With an initial or loading pressure of e.g. 100 bar a water

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Device for initiating and/or promoting chemical or physical processes in a ...