US1872783A - Adsorption system - Google Patents

Description

ADSORPTION SYSTEM I decussa/@5| E E' I ,2z

Aug. 23, 1932. i E; B. MILLER DsoRP'x-Ion SYSTEM Filed Feb. 4, 1950 ll-llllII-l-g.

Patented Aug. 23, 1932 ERNEST B. MILLER, OF BALTIMORE, MARYLAND ansoarrIoN svs'rnu Appiieauon mea February 4, 1930. serial in. 425.883.

This invention relates to air conditioning apparatus and methods, and more particular,- ly to apparatus for dehumidifying or stripping air or gases in large quantities and continuously.

It is a general object of the present inven tion to provide novel methods and apparatus for continuously dehumidifying or stripping and tempering air or gases.

Among the features of novelty in this invention may be particularly enumerated the following:

(A) The use of several stages of adsorption arranged in the order of their saturation 1L for the removal of undesired constituents from air or gases. l

(B) The passage of air or gases over a plurality of batches of adsorbent, together with the coolingof the fluid in its passage 'between at least two of the batches.

(C) An arrangement whereby stripped air or gases delivered from adsorbers is mixed with a proportion of untreated air or gases and the ratio determined by the degree of saturation of the adsorbers.

(D) The use of a plurality of adsorbers whereby at least two are in the strippin' circuit, one in an activating circuit, an one in a cooling circuit.

(E) The use of a closed fiuid circuit provided with cooling means for removing the heat of activation from activated adsorbent. (F) The use of a plurality of adsorbers in gas treating apparatus wherein each adsorber is provided with as many inletducts as there are adsorbers, andwith a like number of outlet ducts.

(G) The arrangement of automatic dam er controlling mechanism for instantly shi ing each adsorber to a different phase in the process. v

(H) An arrangement foractivating saturated adsorbent by passing over it combustion gases diluted with av portion of such gases which have lalready passed over the adsorbent and with or without the addition of untreated air.

(I) The arrangement of adsorbent within an adsorbin chamber, together with inlet and outlet uctsY so positioned as to. give a maximum exposure of the adsorbent to fluids passed from an inlet to an outlet duct.

While the most important objects and features of the invention have been enumerated above, it will be apparent to those skilled in the art, upon a consideration of the accompanying drawings and following specification, that various other objects and features are involved and will be claimed. The invention is disclosed, for the sake of convenience, in several embodiments', each adapted for a particular use, but it is to be understood that these embodiments are in no sense limited to the uses for which they are disclosed, and that the invention ma be prac- 65. ticed in a number of ways which all within the scope of the claims.

In said drawings; Fi re 1 isa diagrammatic and schematic showing of a simple form of the invention as used for drying the air for blast furnaces;

Figure 2 is a view similar to Figure 1 show-l ing the apparatus arranged'for conditioning air in a building or the like;

'Figure 3 is a diagrammatic and schematic 75 view of the arrangement of the actual air y drying apparatus and accessories, wherein three adsorbers are used;

Figure4 is a com lete diagrammatic showing of a four-adsor r arrangement showing not only the' accessories for treatin the air, but the apparatus for controlling t e valves in the inlet and outlet ducts and for activating the adsorbent; and

Figure 5 is a longitudinal section through one of the damper controlling valves of Figure 4.

Although the invention is explained for convenience, in connection with air dehumidifying and tempering systems it should be '9 understood that the methods and apparatus are susceptible. to use for stripping various constituents from gases.

It has heretofore been proposed to remove more or less of the moisturev from atmos- 5 pheric air by various processes, foremost among which may be mentioned refrigeration and adsorption in agents such as calcium chloride and the like. These various processes of moisture removal have not been wholly successful, where practiced on a large scale, either due to the excessive cost of plant and operation, or because of the radical changes in temperature which are'sometimes imparted to the air, requiring furtherv expense to bring the air to the required temperature. Likewise the apparatus becomes bulky, expensive and requires too much manual attention. The present invention de.- parts from the well known methods of drying air and provides a method which is so eminently satisfactory and so cheap to operate that it has already been widely adopted .for drying the enormous quantity of air used in blast furnaces.

The method is a simple one and involves the adsorption of the moisture by bringing about an intimate contact between the air and one or' more batches of adsorbent material. While a large number of adsorbents are satisfactory for use it is preferred, and the present invention is described as using silica gel of the type manufactured by The Silica Gel Corporation of Baltimore.

The invention as previously mentioned is susceptible to a large number of uses, but two .of which are illustrated here.

Referring now to the drawings for a better understanding of the invention, Figure 1 shows an elementary form of apparatus for -drying the air for a blast furnace. Air enters the duct 10 under the suction of the wind engine, not shown, and passes through the air filter 11 into the duct 12 which has a branch 13 leading to a suitable adsorber, generally indicatedby the reference character 14 but which is in reality a more complex apparatus such as shown in Figures 3 and 4. In this adsorber a large portion of the moisture is adsorbedfrom the atmospheric air. Leavlngv the adsorbertheair passes into the duct 15 and thence into the aftercooler 16 which rei duces the temperature of the air which has been elevated due to the heat of adsorption. Thence the air passes into the duct 17 which is joined at 18 by the branch 19 leading off from the duct 12 ahead of the adsorber so that treated and untreated air meet iat 18 and com'- bine for delivery from the duct 20 leading to the wind engine.

The adsorber contains a suitable porous adserbent such, for instance, as silica gel previously mentioned,- and as this material becomes more and more saturated with the moisture abstracted from the atmosphere its rate of adsorption decrease. It is extremely important in blast furnace operation to maintain a substantially constant moisture .content vof the air delivered to the tuyres. This is more important than to have the mini# mum moisture contentfor it permits operation of the furnace to give a uniform output.

Since the rate of adsorption of the adsorbent 'is not uniform some means must be provided to permit delivery of air of a uniform moisalways maintaining asubstantially constant delivery of air lfrom the ipe 20. This regulation can be readily e ected by havin the dampers 21 and 22 inthe ducts 19 and 1 respectively so interconnected that as one opens` the other closes. These dempers can be automatically operated, for instance, by means of a hygrostat 23 in the outlet duct 20 so that the dampers are always set to give a uniform moisture content to the delivered air, which content is very much lower than that of the normal atmosphere. It will be appreciated that to maintain this 4constant humidity at the output irrespective of the humidity of the atmosphere the adsorber must have a capacity suicient to remove the greater part of the moisture from air on even the dampest day.

The use of a cooler such as the after-cooler 16 is optional in the system and'depends to some extent on the type of wind engine used.

It may be placed ahead of the adsorber where it will increase the efiiciency of adsorption which decreases as they temperature rises, or,

it may be placed after the adsorber to reduce the temperature and thus the volume of air necessary to be handled by the wind engines.

At 24 is indicated a group of accessories for the operation of the adsorber Vand they may include means for activating the adsorbent when it becomes saturated and other features which will be described in connection with the vFigures 3 and 4.

Figure 2 shows in'an elementary vform a device for `conditioning the atmosphere in a closed room or space where attention is directed mainly to the maximum dryness of the atmosphere rather than to4 any other conditions. This space, indicated by the reference character 25, isassumed to be substantiallyA tight and is provided with an inlet or air deliveryduct 26 and an outlet or air discharge duct 27. VIf the space is surrounded by walls which are substantially air tight, a suitable exhaust duct must be provided but under ordinary conditions there is suicient leakage around windows and entries to permit a large loss of atmosphere especially if the plenum system is used.

Air from the atmosphere is drawn `through the duct 28 into the filter 29 where ICS tion' fan. 34 which acts to draw the air through the adsorber where there is some little friction. From the fan 34 air is delivered by the duct 35 -to the circulating. fan 36 andthe'nce to the duct 37, the main cooler 38 and into the duct 26 for delivery into the space 25 where it may be distributed -at'a plurality of points as 39.v The adsorption fan also draws a certain amount of air from the exhaust duct 27 which takes in air from a pluralit of points 40 within the space 25; through t e main filter 41; the duct 42 and into the duct 30 where it combines with the fresh air and takes the course just described. The circulating fan ma also draw a certain quantity of theair'passmg through the main filter 41 and the duct 43 which enters the 4duct 35 between the fans 34 and 36.

The system just described does not confresh air to the space 25, but delivers a portion of dried fresh air, a lportion of driedl return air and a portion of return air which is merely cooled. This reduces operating costs, for, under ordinary circumstances the air in the space 25 is not rapidly humidified and therefore is satisfactory for reuse if a portion of it is dried and mixed with some dried fresh air and returned. The function of the precooler is not only to cool the incoming fresh air but some of the air passing through the main filter which ma have been heated in the space 25. It likewlse contributes to the eiiiciency oadsorption. The main cooler removes the ,heat of adsorption and heat inthe direct return air and permits the vair to be delivered to the conditioned space at any temperature desired. These coolers as well as that shown in Figure l may be satisfactorily water cooled and are in effect large surface exchanges in which the water flows through a series of pipes in the air passages. Water is ordinarily available at temperaturesbelow 70 so that the air can be cooled to a point'satisfactoryl for use in buildings.v A great many chemical operations can be best carried out at certain substantially fixed humidities and this apparatus is particularly adapted for that purpose. No automatic -control of humidity is shown but'it lcan readily be constructed to operate substantially like that shownin Figure 1. The total amount of fresh air can be controlled by the damper 44 in the duct 30. The dampers 45 and 46 control the amount of treated air; damper 47 controls the amount of return untreatedV air and damper 48 controls the total amount of air circulated.

Figure 3l shows in diagrammatic'form an adsorber arrangement and particularly a system employing three adsorbers which have been marked #1, #2, and #3 for purposes of'identi'fication. The three adsorbers. are 'identical and each comprises a large chamber preferably of sheet metal in which the adsorber must pass through the layer or bed of adsorbent to reach an outlet duct.

The particular arrangement of the adsorbent forms no part of the resent invention. However, in accordance wlth the present invention it is found'best to provide the same number of linlet ducts and the same number of outlet ducts as there are adsorbers in the system and the reasons will appear as the description proceeds'.

Each adsorber in the embodiment of Fig*- ure 3, then has three' inlet ducts a, b,'and c which `as shown are at the bottom of theV drawings, and a like number and similarly lettered outlet ducts a, b, and c. In the description following it will be considered that when a fluid enters a duct it leaves by the correspondingly lettered duct which, however, is not directly opposite the entrance duct in order that the longest pass possible may be had through the adsorber. Each of the ducts, both inlet and outlet, is provided with a suitable valve to close. ofi' the duct and these valves are indicated in the conventional manner and `Willbe referred to by the letters applying tothe ducts. It is to be noted that the letters on the ducts of the various adsorbers are not arranged in the same livered to the duct 52 which is continued in the form of` manifold 53 whichv has three branch conduits 54, 55, and 56 leading respectively to the inlet ducts c, a, and b of adsorbers #1, #2, and #3. In the present instance it is considered that all of the a ducts .have their Valves open and that all of the remaining ducts in the adsorbers have their valves closed. Airtherefore passes through the conduit 55, through'the duct a into adsorber #2 and from exhaust duct a ofthat adsorber'through conduit 57 into the manifold 58 which is connected also to'the fold to 'the conduit 63 which enters the a i inlet of adsorber #3. lassin .through this adsorber the now thoroughly ried air leaves by the a outlet and enters the manifold 64 which is likewise `connected vto the 'b and c outlets' of adsorbers #l and #2. respectively. This manifold 64 delivers the air to the aftercooler (i5-which delivers itto the conduit 66 leading to the fan `67 which is instrumental in circulating the air, from whence it is delivered through the conduit 68 for the use desired.

The bypass conduit 69 leads from the inlet conduit 52 to the conduit 66 and performs Athe same function as the by-pass 19 in Figure 1. A damper is shown at 70 in the byl pass conduit and another at 71 in the 4outlet conduit 66, andthese maybe regulated to control the degree of humidity of the ydischarged air.

Adsorber #l .which was not involved in the passage of air foradsorption purposes, in the circuit just described, is assumed to have been saturated previously and is thus on the activating phase of the cycle. For the purpose of driving off the adsorbed moisture, heated combustion gasesY are forced adsorber, moisture is taken up by the heated gases which are delivered from the a outlet of adsorber #l to the manifold 75 and thence to the fan 76 which causes their circulation,

' after which theyare delivered yinto a suitable stack or other means for disposing of them, a suitable damper 77 being provlded to regulate'the rate of low of these gases. Adsorber #2 which first receives the air to be treated, in the phase of the cycle just described, is the more nearly saturated of the two on adsorption so that'the 'gas passing through adsorber #3 which is least sat` urated has the last traces of its moisture re'- moved with certainty. When adsorber #2 becomes saturatedeach of the three adsorbers is shifted inthe circuits so that adsorber #3 first receives thev air'to be treated, adsorber #l which hasjust been activated and hence has the least amount of moisture con' tent is used as the cleanup adsorber at the vlast passage of the air and adsorber #2 is placed on'the activating phase.l This is all accomplished by simultaneously closing all of the Aa valves and opening all of the b 65 'Va1VeSf. This then will shift the position of each adsorber in thecircuits as just described ent instance permittin and the cycle will be continued as reviously. l

At each shift of the valves, adsorber moves one step or phase in the cycle thus each adsorber 1n succession is last 1n the ad. sorption phase, is then first in theadso tion phase and finally is on the activating p ase.

t mi ht be thought that a heated adsorber just rom the activating phase would not taker'up moisture but the outer layers of the adsorbent are almost instantly cooled by the cool air from the intercooler so that the small amount of moisture remaining inthe air is' readily taken up.

The aftercooler can be omitted if necessary I but it is highly desirable to always use the intercooler. Of course `a precooler'can be added if required.

' The aftercooler is used to bring the -temperature of the treated air to the desired degree Since lthe temperature of the airleaving the last adsorber in the cycle will be verA high at the beginning, owin to the ad-` to have a thermostat in the air outlet of the, g5

aftercooler as at 78 and to have this connected to a diaphragm valve 79' inA the inlet Water line SAO-of the aftercooler sothat' as the outlet airA temperature .tends to fall, the

water supply to the cooler willbe decreased,

thereby maintaining a constant temperature out of the aftercooler. v

In Figure 4 is shown a four adsorber planty and here it may be mentioned that any number of adsorbers may be used, each increase in the number adding tothe adsorbers which are on the adsorption phase or as in therp'resone of the adsorbers to be on a .cooling p ase after activation. It may better be stated that any number of adsorbers above four adds. to the' number on the adsorption phase sincethe cooling phase is desirable. The arrangement of the a paratu's of Figure 4 is substantially identlcal as regards iping, as that of Figure 3 and the whole escription will therefore not be repeated.` Each adsorber is seen to have one more inlet and one more outlet and there is one more manifold on the inlet side andan` other on the outlet side for connectionto these additional inlet and outlet ducts.-

The untreated air'ilet is shown at 100as including a filterffrom whence theA air is delivered to the'conduit 101" and the manifold 102. With the assumption that all of the a las valves are open the air is delivered to adsorber #2 for partial drying andfrom that ad` f sorber is delivered to the manifold 103/ which leads to the intercooler 104, frm w ichthe air passes to the adsorption ifan 105, t ence is and the mixture is delivered by the pipe 115 into the furnace 116 where secondary air is delivered. from filter 112 by means of the pipe 117. From the furnace 116 the products of combustion pass through the filter 118 to remove any particles and are delivered to the -pipe 119 leading to the manifold 120 which delivers the filtered products of combustion into the a inletI of adsorber #l and from thence to the manifold 121; into the pipe 122 and to the activating fan 123 which serves to circulate these hot gases. From the fan a portion of the hot gases returned from the adsorber is delivered by the pipe 124 to the stack 125 and another portion is delivered into pipe 126 which joints the pipe 1119 so that some of the heated gases are recirculated without passing through the furnace. Suitable dampers, as shown, control the proportion exhausted to the `stack and delivered to pipe 126. At 127 is shown a damper controlled pipe which permits the products of combustion of the furnace to be delivered up the stack. This is particularly useful at starting when smoke is apt to be formed.

The remaining adsorber :#:4 is assumed t0 have just finished activating and is very hot. It is therefore connected in circuit with the gel cooler 130 from` which air is drawn through the conduit 131 by the fan 132 and delivered into the manifold 133. This air,`

cooled by the water iiowing through the cooler, passes through adsorber #4, is delivered through manifoldf134 and pipe 135, and re# turned in a closed circuit to the gel cooler. In other Words, air is merely circulated from the heated adsorber, through the-gel cooler in' a closed circuit. In this way there is no moisture added to the amount that the initial quantity of the air carries/so that the adsorbent is-not saturated during the cooling process.

of the a valves and open all of the b valves, each adsorber, asin the previous instance, moves in effect one position forward in the .cycleso that the` most saturated one is put on activation, the one justactivated is'put on cooling, and the one havingbeen on second When the valves are operated-to close allcylinder such as 140. These cylinders are in the form of the conventional cylinder of a steam engine and are .provided with pistons for operating the valves or dampers, which when at one end of their stroke close the valves and at the other open the valves. -It is preferred to use compressed air for operating the pistons and it will be seen that each cylinder is provided with a pair of pipes 141, one connected to the head end and the other to the rod end thereof. The head end pipes for all of the a valves are connected to distributor pipe 142 and the piston end pipes of the a valves to the distributor pipe 143 and those of the remaining valves likewise vare connected to their respective distributor pipes. A source of compressed air, including the motor driven compressor v144 and the reservoir tank 145, is connected by a pipe 146 to valves 1.47, 148, 149, and 150, eachalso .lettered a, b, 0, and d to indicate their relation to the groups of adsorber duct valves v which they respectively control.

Figu these valves. It is really a conventionall D valve of the type used on steam engines and the pipe 146 supplies the chamber 152 with compressed air which is delivered from the port 153 when the valve is in the position shown, while the port 154 is connected tothe exhaust passage 155i The D valve 156 is slidable so that it can open the port 154 to the compressed air arid associate the port 153 with the exhaust. The valve is normally held in the position shown in Figure 5 by means of the spring157 acting on its stern. The

' A stem protrudes as at 158 through the other re 5 shows in detail, infse'ctiom'one of ico end of the casing 152 and there is connected by means of a centrally pivoted lever 159 to a roller 160 operating on a cam 161.

In Figure 4, four cams are shown on the shaft 162 each with a lobe of substantially 90 extent and with the lobes positioned respectively in the four quadrants. This provides that but one of the valves 147, 148, 149, 150 is open against its spring, at any one time and in Figure 4 the upper valve lcontrolling the a valves of the adsorbers isshown open, that is', permitting air to be delivered to the ends of the cylinders 140 which 'causes opening of the. a valves. All of the remaining valves 148, 149, 150 are so held b their springs that the b, c, and d valves o the adsorbers are closed.

The shaft 162 is drivenby any suitable increases the number of inlets and outlets to eachV adsorber increases correspondingly, to i takecare of the additional manifolds leading additional adsorber but otherwise the construction would be substantially identical.

The arrangement of the adsorbers so that lthe adsorption takes place in stages is of particular advantage, for the moisture upon being adsorbed gives up its latent heat thereby increasing the temperature of the adsorbent and the air, and decreasing theadsorbing qualities of the material. By arrangement in stages provision can bemade for intercolers between stages to keep the temperature of the air lower. Second, the air partially dried by the first stages is lastly passed through an adsorber which has just been activated and hence is at the height of its capacity so that it easily removes thel last remaining traces of moisture.

Having thus described the invention what is claimed as new and desired tombe secured by Letters Patent is: l. Apparatus for` drying air comprising, in combination, a plurality of adsorbers each containing an adsorbent, means to connect at least two of said adsorbers in circuit withair circulating means to dry the air, a source of heated gas to revivify saturated adsorbent, means to place another adsorber in circuit with said source of heated gas and a circulating means, an air cooler in circuit between thetwo adsorbers on the adsorption phase,

and valve means to periodically and automatically rearrange the adsorbers in the circuits to remove the most saturated one from the drying circuit .tov the revivi'ying circuit, said means insertingfa fresh adsorber in .the drying circuit and moving another from one side to the other of the cooler. l

2. Apparatus for dryin aircomprising in combination, a plurality o adsorber housings each containing a quantity of adsorbent, each housing having as many inlets as the number of housings and a like number of outlets, a separate conduit for each set of corresponding inlets, a separate conduit for each set of corresponding outlets, valves between each conduit and its associatedinletsor outlets,one of said inlet conduits being permanently connected to a source of air to be dried, one permanently connected to an air cooler and one permanently connectedto, a. source of heated activating gas, said valves being so arranged that but one housing ata time can be connected to any one inlet and outlet conduit. l

3. Apparatus for drying air comprising in activating gas, one of said outlet conduits I being permanently connected to deliver the treated air, one being permanently connected to said cooler and one permanently connected to eduction means for said heated gas, said valves being so arranged that but one housing at a time can be connected to any one inlet and outlet conduit.

4. Apparatus for dryin air comprising i-n combination, a plurality o? adsorber housings each containing a quantity of adsorbent, each housing having as many inlets as the number of housings and a like number of outlets, a separate conduit for each set of corresponding inlets, a separate conduit for each set of corresponding outlets, valves between each conduit and its associated, inlets or outlets, one of said inlet conduits being connected to a source of air to be dried, one to an 'air cooler and one to a source of heated activating gas, one of said outlet conduits being connected to said cooler and one to eduction means for said heated gas, said valves being so arranged that but one housing at a time can be connected to any one inlet and outlet conduit andmeans to periodically actuate said valves to change the connection of each .adsorber housing to the conduits.

ido

5. Apparatus for drying aircomprising in '.corresponding outlets, valves between each conduit and its associated inlets or outlets, one of said inlet conduits being connected to iis a source of air to be dried, one to a dried air cooler, one to a source of heated activating gas and one to an adsorbent cooler, one o`fsaid outlet conduits being connected to deliver the treated air, one being connected to said dried air cooler, one to eduction means for said activating gas and one to said adsorbent cooler, said valves havingl operating means to periodically connect the adsorber housings each to one of the inlet conduits onlyand one of the outlet conduits only following a predetermined order.

`6. An adsorber casing havinga plurality of inlets at one side thereof and a like number of outlets at the other side thereof, valves for v the casing longer t said outlets and inlets, means controlling the opening and closing of said valves whereby but one inlet and one outlet is open at any combination, a plurality of adsorber housings4 each containing a quantity of adsorbent, each housing having as many inlets as the number of housings and a like number of outlets, a separate conduit for each set of corresponding inlets, a separate conduit for each set of corresponding outlets, a valve between each conduit and its associated inlet or outlet, and means to periodically open one inlet valve and its corresponding outlet Valve for each casing and to simultaneously `close all of the other valves for said casing.

' In testimony whereof I hereunto ax my signature.

ERNEST B. MILLER.

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