US1576136A - Apparatus for concentrating solutions - Google Patents

Description

March 9 1926. 1,576,136

M. o. JOHNsoN APPARATUS FOR GONGENTRATING SOLUTIONS Filed Sept. 19, 1921 3 Sheets-Sheet 1 /A/ V NTOR t mi@ O, IF

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ATTRNEY March 9 1926. 1,576,136

M. o. JOHNSON APARAIUS FOR CONCENTRATING SOLUTIONS Filed Sept. 19, 1921 3 SheetS-Sheet 2 BRINE TANK COMPRLSSOR RECEIVER A T RNE Y Marchy 9 1926.

Mv O. JOHNSON APPARATUS FOR GONGENTRATING SOLUTIONS 1921 3 Sheets-Sheet 5 Filed Sept. 19

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l! [lill TOR Loc ooooooo Patented Mar. 9, 19.26.

UNITED STATES MAXWELL O. JOHNSON,A OF WAIPIO, TERRITORY 0F HAWAII- APPARATUS FOR CONCENTRATING SOLUTIONS.

Application led September 19, 1 921. Serial No. 501,855.

To all whom z't may concern;

Be it known that I, MAXWELL O. JOHN- soN, a citizen of the United States, residing at VV-aipio, in the county of Honolulu, Territory of Hawaii, have' invented certain new and useful Imprpvementsin Apparatus for Concentrating Solutions, of which the following is a specification. I

llhe invention" relates to a novel meansfor concentrating solutions, and more particularlyto such a means wherein the concen-- tration is effected by freezing, and regenerative features, or steps and means are employed.

Objects and advantages of the invention will be set forth in part hereinafter and in part will. be obvious herefrom, or may be learned by practice with the invention, the saine being realized and attained by vmeans of the instrumentalities and combinations pointed out in the appended claims.'

The invention consists in the novel means, parts, constructions, arrangements, steps,

.improvements herein shown and described.

Theaccompanying drawings, referred to herein and constituting a part hereof, illustrate exemplarily the present preferred form of means or apparatus employed 1n carrying out `the invention, and illustrate certain steps in the method or process; the d rawings being 4more or less diagrammatic in character.

Fig. 1 -is a transverse vertical section of one form of freezing and concentrating apparatus included in the invention;

Fig. 2 is a like vertical section of a somewhat different form of such apparatus;

Fig. 3 is a similar view showing a yet different form of such apparatus;

Fig. 4 is a diagrammatic elevation show-- ing.;r the regenerative steps in the process and the apparatus preferably employed in connection therewith; and

Fig. 5 is a diagrammatic elevation, ona smaller scale, of the same steps and a paratus, but showing certain parts in a dition to those shown in Fig. 4. l

The concentration of solutions of many various kinds and constituents are widely and generally effected by evaporation. and usually involve the application of relatively high temperatures. This""type of process is objectionable in case of very many solutions and for a number of reasons. This application of heat, especially at high temothers.

peratures, and for relatively long periods,

is very injurious to many solutions, and partici'ilarly to organic solutions such as fruit juices, milk, dye-wood extracts, and many In the-case of many such solutions the em loyment of relatively high temperatures e ects decomposition or dissociation of some of the highly organized compounds' essential to or characteristic ofthe solutions. 1t will be understood that the term solution herein is usedgenerally to designate" any relatively dilute liquid to be concentrated, and the term solvent to indicate the diluent, that is the part thereof which is separated out by the freezing action in order to concentrate the liquid.

These evils and disadvantages are obviated in concentrating by freezing, and this process usually improves or maintains the quality of the Yoriginal solution in the concentrate, as it avoids the breaking down of the highly organized compounds characteristic of the solutions, and avoids foaming and other'evils.

In connection with the freezing process also, certain features of easy and rapid separation of theconcentrated .fluid are realized,

together with capacity for maintaining Ya f I lcontinuous process, and also for employing regenerative steps or means which render the process easy, rapid and economical.

Referring now in detail to the present preferred manner of carrying out the process and the present preferred form of apparatus, and referring first to the direct step of freezing to concentrate the solution and to effect separation of the frozen solvent and of the remaining concentrated liquid, the

process is primarily described as applied to aqueous solutions, such a fruit juices, although it will be understood that in its main features the invention isv applicable to the concentration of otherkinds of solutions.

By my. invention, an apparatus is provided for freezing a solution in a can, tank or other suitable container of heat-conducting materia-l, one level or portion of the container being subjected to freezing temperature, and another level orcpoi'tion being maintained above the freezing temperature, the aqueous or other more dilute part of the solution being frozen Within the con- I tainer, and the condensed residue ofthe solution 'collecting in that part of the container which is maintained above freezing temperature.v As embodied, a refrigerating medium is applied to the exterior of a. part of the can or compartment, and preferably to the upper part thereof, and the lower part ofthe can or container is maintained above the freezing temperature. The aqueous or other thin part ofthe solution in such a can or container under these con-- ditions, will freeze out in an almost pure condition as ice on the sides or walls of the container, while the concentrated 4solution, W ich is of greater specific gravity than the dilute solution, will settle into the bottom or non-freezing portion or part of the container.

When the desired or required4 degree of concentration is reached, the concentrated fluid or solution may be drawn off without disturbing the ice or frozen original dilute solution. j

This will remove the greater part of the concentrated solution, but by allowing the portion of the can or compartment which was subject to freezing to lrise in temperature above the freezing point, the ice in the can will gradually thaw or melt, and the remainder of the concentrated part-of the solution (which is of intermediate concentration betweenk the very dilute and highly concentrated parts) will come ofi' in the f irst drainin as it forms a softer or mushier ice o'r ike solid. Practically all of 'this string concentrated solution may be drained off before the pure or harder ice begins to melt and at this time almost pure ice is leftin the can or container, and the concentrated juice is practically entirely drained off, thus effecting an easy, rapid, economical andcomplete separation of the two.

If desired, the blocks of ice formed in the can may be thawed loose, lifted out7 broken up and Acentrifuged to recover the relatively small residue ,of concentrated juice. This, however, is usually unnecessary where the draining, thawing and again draining process as just described is employed. The pure ice secured may be broken up and f used in the regenerative process hereinafter described.

Referring now in detail to Fig. 1 of the drawings, a can 1 of sheet metal or other highly heat conductive material is employed as a container for the solution to be concentrated. I have found that the most eiiicient form of can is one which is relatively deep vertically and of comparatively small horizontal cross-section. This permits a better and more efficient heat interchange Withthe circulating refrigerating medium,

The can may be of any suitable or desired form, but is preferably relatively narrow and deep, and rectangular, oblong orr cylindrical in horizontal cross-section. Means are provided for applying a refrigerating medium, and preferably a'circulating refrigerating medium, to a portion of the exreater part of thepart of thejacket may be conveniently termed the' freezing portion, and the portion 5 thereof external to and belowthe jacket 2 may be termed the non-freezing por-tion of the can. The lrelative size of these. portions will depend partly on the degreefof concentration desired. Usually about one-half to twothirds of the water in a solution is as much as it is convenient to remove in one oper-l ation. A ratio of about four or five to one between the freezing and non-freezing portions of the can or container is approximately correct and efficient for this amount of concentration'. This also allows or causes a core of concentrated solution to extend through the center of the can, as shown in Fig. 1, and shortens the time of Vfrcezinfr o b l since the ice need not be frozen solid through the diameter of the can 1 to effect the desired concentration. o

Means are provided for diainino` off the concentrated solution', and as embodied a pipe 6 communicates with the bottom of the can 1, and is provided with a valv'e 7.- Any suitable supply may be provided for the dilute solution, and the process may be practically continuous. It will beunderstood that the ice must be periodically removed, which can be accomplished by slightly thawing and then liftin out the ice block, and this may be done either with or without the step of thawing to ,recover the remainder of the concentrate as ,already described.

In Fig. 2 a Vertical section is shownthrough a somewhat different form of can kor tank. In this form, the can or tank 10 is one of a series, and rests on `supports 11` and 12. Between this can 10 and the adjoining cans are spacing blocks 13 and 14, resting upon the blocks or supports 11 and 12. Over these blocks and around the can 10 there is poured or placed a waterproof, heat insulating compound or material 15, such as pitch, or any other suitable inate.'ial. This is filled in to such a depth as will give the desired proportion between the freezing and non-freezing portions of thecan or tank 10, as already explained in connection with Fig. 1. l

The cans or tanks 10 are separated at or near their top by means of bars 16 and 17,. Through the spaces 1K8 between the cans' or tanks, the refrigerating medium, such as cold brine, is circulated in the same manner as within the jacket 2 of the can or tank of F ig. 1. Suitable inlets and outlets (not shown) will be provided.

In this figure, hooks 19 and 20 are shown which are connectedby a cross yoke 21 and are suspended from the top edges of the can by their hook ends 22, and become imbedded in the ice during the freezing operation. An eye 23 is formed in the cross ban 21, to lwhich 'a hook or other device may be attached to lift out the cake of ice after it has been suiiiciently thawed. The pipe 24 communicating with the bottom of can 10 serves for the drawing olf of the con.-

centrated liquid in the bottom of the can, and is provided with a valve 25.

IVitli the construction of the can or tank just described, the difference in level and relative position of the freezing and non'- freezing parts of the can or tank are dependent on the difference in specific gravity of the dilute solution and the concentrated solution, the latter being the heavier. If in any case the concentrated liquidshould lighter, the' parts of the can would reversed. The cans or tanks may be provided with suitable closures, not shown.

In Fig. 3 a form of tank or can 30 is shown, adapted to be suspended in a brine tank which may be of the usual form. The

tank 30 is suspended by a ring 31 around the top edge thereof, resting upon a plate or supports 32 supported on the tank structure.

The non-freezingpart of the can or tank 30 is provided in this case by a layer or layers 33 of heat-insulating material, such as sheet cork or other suitable material.

A pipe 34, provided with a cock 35, serves to drain the concentrated solution from the can. If desired the can may be lifted from the brine tank and the concentrated solution may be poured out through the top of the can. This form of can, while adapted for use with a common or standard type of brine tank, is usually not as efficient as the two forms previously described, as some heat may be transmitted through thc insulation 33 and as a consequence some mushy ice may be formed in the concentrated solution, thereby rendering the separation more dificult.

lVith certain kinds of solutions the separation is more effectively -accomplished by agitation, and 4this may be e'ected by any known or other suitable means, such as a stream of air, a circulating pump, a rotating screw, or other suitable means.

With vcertain solutions, such'as fruit puces forexample, agitation may cause foaming and be objectionable on this account.

Referring now more particularly to the regenerative or energy conserving features of the invention, it may be stated generally that the ice formed during the concentrating process is employed ory consumed in cooling the ammonia, or other refrigerating medium, to effect or assist in el'ecting'tlie required reduction iny temperature, and it is also preferably employed to pre-cool the dilute solution, that is to cool it preparatory to concentration. As one feature of the regenerativeor energy-saving process, the coId concentrated solution is also preferably em-` ployed to pre-cool the dilute solution.

In the preferred embodied form thereof, it is shown` applied to a refrigerating system of the ammonia compression type, as this is the type in most common use, but it will operate equally Well with other types of refrigerating systems and other refrigerating media besides ammonia; or will operate with the ammonia absorption type or system, as the condenser or expansion coils.

'lower a solution to its freezing point is small compared to the capacity required to freeze out the solvent. If the ice be utilized in cooling the condenser of the refrigerating apparatus, the refrigerating work o-r energy expended in freezing the ice is returned to the system. Thus aside from radiation and mechanical losses, the only capacity required of the refrigerating apparatus is the small amount necessary to lower the temperature of the dilute solution to the freezing point..

The cooling ofthecondenser by 'the ice will lower the condensing pressure' in the refrigera'ting apparatus very materially. The efficiency of a refrigerating apparatus is proportionately greater the less the difference between the. condenser pressure and the low or expansion pressure. By melting the ice which was formed in the concentration process in the operation of cooling the condenser, agreat saving is secured or eifectl ed in the amount of energy required to operate the refrigerating apparatus; or the same refrigerating apparatus may be made to furnish increased capacity or roduct with the same energy consumption. 3y utilizing the outgoing cold concentrated soluf tion. and also the ice to cool `the incoming dilute solution an additional,v saving is efl fccted.

The mat-ters of tlieoiy just stated are true and ap licable to the best of my present knowle ge and experience, but it will be un- `refrigerating apparatus.

derstood that the invention is not ai'ected should any errors or discrepanciesbe later vfound therein.

is supplied from a centrifugal, or ice-breaker, operating in conjunct-ionwith the concentrating apparatus) dumps or poursl the broken ice. over the coils 41 of the condenser. The ice is rapidly melted by contact with the coils 41,`.and thel water is drawn oif through an overflow pipe 43. A baffle plate 44 may be employed to`keep the outlet clear.

Usually the hot ammonia Agas from the compressor passes into the fore-cooling coils 46, which coils are cooled by water running thereover, and if desired, this may be the water from the melted ice in the tank 40. Thus a considerable portion of the heat of compression is removed from the gas by this apparatus. `The supply of water to the co'il 46 is regulated so as to give a low condensing pressure, but not so much so as to cool the compressed gas so that it cannot l melt all the.ice around the submerged condensing coils 41. The gas at this desired temperature asses from the cooling coils 46 by pipe 47 t rough check valve 48 into the condensing coil 41. The liquid ammonia passes through the pipe '49 to the receiver.

Referring now to the pre-cooling ofthe dilute solution, in accordance with vcertain features of the invention, this is effected both by the action of the oold condensed liquid and also by the action of the ice .or frozen solid. AS embodied, the cold concentrated liquid enters thecounter-current apparatus 52 through a pipe 53, and passes out therefrom through a pipe- 54. The dilute solution to be cooled enters the counter-current apparatus 52 through a pipe 55, and passes out therefrom through a pipe 56. Thus some portion of the heatis abstracted from thewarm dilute solution bythe cold concentrated solution in ythe counter-current apparatus. l Y f In the' embodied` manner of utilizing the ice or frozen solid to cool the dilute solution, pipe 56 communicates with a pipe or pipe coils 57, over which the ice from the conveyor 42 passes to the condenser coils 41. The coils 57 are above the surface of the liquid in tank 40, and are spaced relativel far'I ther apart than are the condensing coils 41.

.pipe 58 to the cans or tanks, previously de- There is thus no tendency for the ice to block or hang on the coil 57 since it is being melted'below by the coils 41. The cool dilute solution passes from coils 57 through a scribed, for the freezing concentration process.

The concentrated solution and the melted ice or solvent, that is, thewaterV from the tank 40, leave the system but little below ordinary temperature, and thus their low temperatnres,"imparted during the concentration process, have been transferred very largely to` the refrigerating means and to the dilute solution, and but very little additional refrigerating capacity .or energy need be added or supplied to the system or cycle to keep it in operation.

The invention in its broader aspects is not limited to the precise form of apparatus shown and described, but changes may bemade therein without departing from the principles ofy the invention and without sacrificing its chief advantages.

1. An apparatus for concentrating solutions by freezing, comprising in combination a freezing tank, a compressor', a forecooler, means for further cooling the compressed refrigerant with ice from the freez ing tank, means forl expanding the refrigerant, means for extracting heat from the freezing tank through the medium of the expanded refrigerant, means for drawin off lthe cold unfrozen concentrated solution rom 100 the freezing tank, means for conducting dilute solution to the freezing tank, and a heat exchange device in which the incoming dilute solution is pre-cooled bymeans of the outgoing cold concentrated solution.

2. An apparatus for concentrating solutions by freezing comprising in comblnation a freezing tank, a compressor, a' fore-cooler, means for further cooling the compressed refrigerant with ice from the freezing tank, 1,10 a brine tank, means for expanding the refrigerant and cooling the brine and appl ing the cooled brine to the freezing tank means for drawing off the cold unfrozen solution from the freezing tank, means for leading the dilute solution `lto the freezing tank, and a heat exchange device for cooling the incoming dilute solution by bringing it into. heat -interchangin relationship with the outgoing cold un rozen concentrated solution.

3. An apparatus for concentrating solu` tions bfreezing comprising in combination-a reezing tank, a compressor, aforecooler, means for further cooling the compressed refrigerant with ice from the freezlng tank, a brine tank, means for expanding the refrigerant and cooling the ybrine and applying the cooled brine to the freezing tank, means for drawing olf-"the cold un- 13 tionship With. the outgoing'cold unfrozen drawing o frozen solution from the freezing tank, means for leading the dilute solution to the freezing tank, a heat exchange device for cooling the incoming dilute solution by bringing it into heat interchanging relaconcentrated solution, and means for additionally cooling the incoming dilute solution With ice from the freezing tank.

Ll. An apparatus for concentratingsolutions by freezing comprising in combination, a freezing tank, a compressor, a cooling tank containing ice from the freezing tank, for cooling the compressed refrigerant from the compressor, means for cooling the compressed refrigerant before it enters said cooling tank, with Water obtained from the melting of the ice in 'the cooling tank, means for the ycold unfrozen solution, means for supplying dilute solution to the freezing tank, a heat exchange device through which the cold unfrozen solution and the incoming dilute solution are passed, for pre-cooling the incoming dilute solution, a brine tank, means for expanding the refrigerant and cooling the brine and applying the cooled brine to the freezing tank for freezing the contents thereof, and means for additionally cooling the incoming dilute solution With ice from the freezing tank.

5. An Vapparatus for concentrating solutions by freezing, comprising in combination a freezing tank, a brine tank, means for` ,subjecting the upper part only of the freezing tank to the cooling action of the brine', a compressor, a forecooler, a cooling tank for the compressed refrigerant, containing ice from the freezing tank for 'further cooling the compressed refrigerant, means-for expanding the cooled refrigerant and cooling the brine therewith, means at the lower part of the freezing tank for conducting away the cold unfrozen solution, means for delivering dilute solution to the freezing tank, and a heat exchange device through which the dilute and concentrated solutions lare passed, for pre-cooling the dilute solution. In testimony whereof, I have signed my name to this specification. y

MAXWELL O. JOHNSON.

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