US2348465A - Process of treating articles for removing grease and oils - Google Patents

Description

M y 1944- P. L. GEIRINGER PROCESS OF TREATING ARTICLES FOR REMOVING GREASE AND OILS Filed Dec. 11. 1940 2 Sheets-Sheet 1 kmzuuwm bw S 5315; n M H h h k 2 1 u g 6% u\ u ix ux 5x bu 22.; .pzm sw 1 1 l 1 I Q1 1% d M. w/

May 9, 1944. P. L. GEIRINGER 2,343,465

PRUCESS 0F TREATING -R'III'IQLIE S FOR REMOVING GREASE AND OILS Filed Dec. 11. 1940 2 Sheets-Sheet 2 TANK CAR INVENTOR 51111 L. Girl/Wye:-

ATTORNEY a Patented May 9, 1944 PROCESS OF TREATING ARTICLES FOR REMOVING GREASE AND OILS Paul L. Geiringer, New York, N. Y.

Application December 11, 1940, Serial No. 369,687 In Great Britain February 5, 1940 12 Claims.

This invention relates to processes for treating articles for removing grease and oils, and more particularly to processes for cleaning articles not readily cleaned or degreased by other methods, the interior surfaces of hollow containers or vessels, and articles introduced into a shell or container for cleaning.

This process is an improvement on well-known processes which comprise bringing a solvent or other cleaning agent, either in vapor or liquid form, into contact with the surfaces or articles to be cleaned. The cleaning agent (usually upon condensing, if a solvent in vapor form) dissolves or removes the fat and oil and thus degreases the surfaces. In previous experience in applying such processes, it has been found that larger or smaller parts of the cleaning agent could not be recovered from inaccessible spaces or pockets from which it could not be completely drained away. even by tilting, inverting or agitating the articles being cleaned. Experience further showed that some amount of uncondensed vapor was also lost. The agents used for such purposes are frequently expensive, and the recovery of the same after use is accordingly advantageous.

One of the principal objects of the present invention is to provide a method by which the maximum possible quantity of the agent used may be recovered after use, whether the same is in liquid or vapor form.

Another principal object is to render the cleaning or degreasing process more rapid than hitherto.

Another object is to provide a process which is more complete and thorough than processes previously used.

A further object is to provide a process which can be used upon articles which are not readily cleaned by other methods, such as objects having undrainable or inaccessible spaces or pockets, or for other reasons difficult to subject to cleaning processes.

Another object is to provide a process which may be used upon a large variety of types of arti-- cles, and for cleaning either interior or exterior surfaces.

Another object is to provide a process by which articles may be cleaned in situ.

Another object is to provide a process for cleaning articles where the removal of the agent, either in liquid or vapor form, cannot otherwise be achieved, to avoid interference with the further treatment or use of such articles.

Another object is to reduce the expense of the cleaning operation by minimizing the waste of the cleaning agent.

Another object is to deodorize the articles cleaned, by removing the odors of grease and oil and of the cleaning agent.

Another object is to avoid toxic poisoning and impairment of the health of attendants of the equipment; by using any vacuum no vapor can escape, such vapor being sucked into the plant for recovery.

Another object is to recover more clean liquid from distillation of a solvent for cleaning of the same after use, than by previous processes, at the same time avoiding danger of poisoning and saving heat.

Further objects and advantages of the invention will be in part set forth in the following specification, and in part will be obvious therefrom without being specifically pointed out.

With the above and other objects of the invention in view, the invention consists in the novel process set forth in the claims hereof, cer-. tain embodiments of the same being described in this specification and illustrated in the accompanying drawings.

In the drawings, which form a part of the specification,

Fig. 1 illustrates diagrammatically on arrangement of an apparatus suitable for carrying out my process by the use of a volatile solvent, for cleaning the interiors of drums, barrels, or other containers;

Fig. 2 illustrates diagrammatically an apparatus suitable for carrying out my process in a slightly modified manner, in which the articles to be cleaned are enclosed in a shell; and

Fig. 3 is a detail view, in section, below referred to.

In carrying my invention into effect by the use of an apparatus such as illustrated in either of said Figs. 1 and 2, many of the steps are the same as or similar to those of processes previously used, a known solvent (frequently trlchlorethylene or otherml lrvdfrgc arrblon solventl bfigwE porized in a s 0 us 1a "6r any suitable type. and brought into contact with the surfaces to be cleaned, and thereafter drained therefrom. The actual degreasing therefore may proceed as heretofore known, except as herein pointed out.

In my invention, the solvent is applied to the surfaces to be cleaned, within a closed space, as below more fully referred to, and after finishin the degreasing process, the surfaces of the parts being cleaned are subjected to a diminished pressure, with the result that any remaining portion of the solvent which has been condensed on said surfaces (or in the shell containing such articles) is immediately again vaporized. Such vapor (including also any vapor not previously condensed) is sucked out by the suction which creates such diminished pressure in such enclosed space. Usually the diminished pressure is below atmospheric pressure, forming a greater or less vacuum, but this is not always essential. The pressure need Only be reduced to such an extent that the flashing or vaporization of the liquid solvent takes place, and that at the same time the vapors are sucked off into a condenser and carried to suitable recovery means. It is usually necessary to also add heat, either externally or internally, directed to the condensed liquid, sufficient to cause complete vaporization. In this way, the parts to be cleaned are completely degreased, and substantially the maximum amount of solvent is recovered for re-use.

The process may also include, .as a further improvement, if required, the use of hot air as a means for recovering the last remainder of vaporized or liquid solvent, which could not otherwise be recovered, and for deodorizing. This rinsing with hot air brought into contact with such remainder may be very short, being done either directly after the pressure is reduced or at the same time.

A further feature of my invention is that the reduction of air pressure may also be applied at the beginning of the degreasing process. This is not essential, but is advantageous, as extracting the air permits the hot vapor to more easily beat the surfaces to be degreased. The raising of the vapor pressure as far as practicable above atmospheric pressure is advantageous, for the acceleration of the process and also to have a larger pressure drop at disposal for the pressure-reduction period of the process. Sometimes it is possible to eliminate the preliminary sucking off of the air by this increased pressure or by admitting the vapor at or near the particular surfaces to be degreased, or both.

The process may be further improved in some cases by increasing the temperature of the parts being degreased, or at least by maintaining a certain temperature level to increase the action of the cleaning agent on the surface, usually at, the start of the pnocess.

Means for thereafter cooling the surfaces being cleaned (or the shell enclosing such articles) may also be used, for increasing the speed of condensation, usually at the end of the process.

The process as carried out in the apparatus illustrated diagrammatically in the drawings, is described more in detail as follows:

The manner of carrying out the process which is illustrated in Fig. 1,'is adapted for the degreesing and cleaning of barrels, drums, cans, tanks, tank cars or tank trucks, or other structures, the interiors of which are to be cleaned and degreased. In this case the article to be cleaned, itself forms the shell. As illustrated in Fig. 1, a number of barrels, designated 5, are connected to the apparatus, as below described. The same may be applied, however, to tanks or the like in fixed position, that is to say, barrels or the like may be brought to stationary degreasing equipment, or transportable equipment may be carried to the objects to be cleaned. Connections by which the apparatus may be used for such purposes, are indicated in the drawings, at the point marked Tank car, at which the pipes are shown broken away beyond valves in pipes H and I2, below described.

As diagrammatically illustrated, the solvent is vaporized under pressure in a still l0, which may be any usual or suitable form of vaporizing means. The diminished pressure within the barrels is produced by a vacuum pump l1, connected therewith as below mentioned. The valves 40 and H being opened, the vaporized solvent passes to and thru pipe H and enters the barrels thru vertical pipes I la, suitable valves, not shown, being provided for the control of the flow of vapor thru the individual pipe Ila. These pipes are extended into the upper portion of the interior of the barrels. The vapor condenses on the interior surfaces thereof, and dissolves the grease, oil, etc, thereon. Heating means 30 are provided for reaching more quickly the temperature level necessary. The greater part of the solvent, with the matter dissolved therein, then flows down thru vertical pipes I2a into a horizontal pipe l2. Valve 43 being open and valve 44 closed, the solvent and dissolved matters flow down thru condenser l5 into receiver Hi. It will be understood that the operation of the pump I1 may be continued or not, as desired, depending on the amount of condensate which is set free and from the speed of its draining away, during this intermediate stage of the process which follows the initial use of suction above mentioned and precodes the final flashing-out.

In order to facilitate and hasten the condensation of the solvent on the interior surfaces of the barrels 5, cooling means are used, comprising as illustrated in this figure, water pipes 50 from which cool water is sprayed upon the upper portions of the barrels.

A sight-glass I 4 is inserted in pipe I2, to permit observation of the time at which the cleaning is completed and clean solvent accordingly begins to pass thru pipe l2. When this is seen, the inlet of vapor into the barrels is cut off, and the vacuum pump is operated to reduce the pressure sufficiently for the final flashing-out step of the process. At the same time or almost immediately thereafter, a small amount of heat is added. Steam, hot water, hot oil coils, hot air, or other means, could be used for the transfer of this small quantity of heat, but electric transmission of some kind, especially by means of special lamps or heating units, is preferable. Such heating units are indicated at 30 in the drawings.

This reduction of pressure, with the addition of heat when necessary, vaporizes any solvent which may be retained in undrainable and inaccessible places, and which would therefore otherwise be lost. The same is then sucked oil by the pump H, and passes down thru condenser l5 into receiver I6.

If desired, a short rinsing of the barrels by hot air, may now be used to complete the cleaning. This is done by means of pipe 26, connecting with pipe ll, air-heater 21, and blower 28. Any last remainder of solvent is vaporized by this means, and is either sucked off by the vacuum pump, or, if very small, is allowed to dissipate when the valves are closed and the barrels are removed from the apparatus. Such rinsing with hot air also serves the purpose of deodorizing the cleaned articles, both from the odor of any grease or oil and from the odor of the cleaning agent itself.

The solvent passing thru condenser I5 is carried into receiver l6, as above mentioned; in which the liquid portion accumulates in the bottom and is returned to the still I0, and from which the vacuum pump l1 exhausts any uncondensed vapor into a .second receiver, designated It, in which a portion is condensed and falls to the bottom, and the remaining vapor passes to a charcoal recovery plant I9. These portions of the equipment are of usual or any suitable construction for the purpose.

From one or both receivers and the recovery means, the liquid solvent is returned to the still by means of pipe 20 and pump 2!. As shown diagrammatically in the drawings, only one still is indicated, but in practice two would be usually used, the liquid being returned preferably to a second still rather than at once to the original vaporizing means. In either such second still or (as shown diagrammatically) in the original still, the solvent is cleaned of grease and oil dissolved therein, by vaporizing the same and passing it thru vertical pipe 33 to a second condenser 22, thru a water separator 23, and into a solvent tank 24, from which it is returned as desired, thru pipe 29, to the original vaporizing means for re-use. During or at the end of this operation, the vacuum pump H is used to produce an under-pressure in the still, by means of pipe 25, the various valves being operated in a manner which will be obvious without detailed description. The use of such under-pressure permits such cleaning-distillation to be carried out more completely and with the use of less heat; this produces a more satisfactory result, as well as the saving of heat, and also avoids the possible decomposition of the solvent which might otherwise result, and also avoids the consequent danger of poisoning from the decomposed solvent.

Various other valves are indicated in the drawlugs and not particularly referred to, the use of which will be clear from what has been said or from inspection of the drawings. Said drawings being diagrammatical, other parts such as pressure gages, thermometers, and numerous other items of equipment, are not indicated.

The pipes Ho. and I211 are preferably concentrically arranged, i. e., the pipe Ha, for a short distance below the entrance to the barrel, passes thru pipe Ho and then extends beyond it into the barrel, and the liquid solvent passes down thru pipe l2a surrounding the pipe Ila. This is illustrated in the fragmentary sectional view Fig. 3.

If desired to apply the process to a tank, tank car, or other vessel or structure which cannot be inserted in the apparatus, the connections may be made thru pipes 45 and 46, and the process carried out in a substantially similar manner, with adjustments due to the shape and particulars of the object to be cleaned.

In carrying the process into effect in the manner illustrated in Fig. 2, which is adapted for the degreasing of objects both exteriorly and interiorly, for the degreasing of vessels not withstanding pressure and vacuum, and of all objects having undrainable and inaccessible spaces or pockets or for other reasons diificult to clean to remove the cleaning solvent or to recover an expensive solvent, as, for instance, motor blocks, etc., the articles to be cleaned are enclosed in a shell, constructed to withstand both the pressure of the vapor, introduced therein surrounding the objects to be cleaned as well as entering the interiors thereof if hollow, and the pressure of the outside air when a high vacuum is created within the shell.

The essential operation of the process is sub- 1| stantially the same, and similar parts of the apparatus have been given the same numerals as in Fig. l. The drawings indicate diagrammatically several containers and a motor block in place within the shell. My process will clean all portions, crevices and pockets thereof, and will nevertheless permit the recovery of the solvent even from very inaccessible portions thereof.

In addition to providing the closed shell, designated 35, for enclosing the articles, this modification provides the use of a spray or a relatively cool portion of the solvent itself as a facilitating means for the condensation of the vapor upon the articles, the same being sprayed thereon within the container, in lieu of the use of an external water spray as mentioned previously, and being supplied thru pipe 3| and applied in sprays or jets 32, at the desired stage of the process.

The process may obviously be carried out by the use of other apparatus, other than that diagrammatically illustrated and herein referred to.

Instead of using a solvent, the process may be carried out by means of other cleaning agents. Substantially similar steps, or such of the same as may be desired, can be employed with the use of a cleaning agent which removes grease and oil by saponiflcation, or by other chemical and/or physical process, and which agent can be vaporized.

Many of the advantages of my invention have been pointed out or alluded to in what has been above said, and need not be here set forth in detail; further advantages will also be evident to those skilled in the art.

I do not limit myself to the particular details of my process which have been set forth in the foregoing specification, as the same refer to and set forth only certain embodiments of my invention, and it is obvious that the same may be modified, within the scope of the appended claims, without departing from the spirit and scope of the invention.

Having thus described my invention, I claim:

1. A process for the cleaning of articles with hard surfaces to remove grease and oil from said surfaces, comprising the steps of diminishing the pressure in a closed space adjacent a surface to be cleaned, at the beginning of the operation; admitting into said closed space the vapor of a solvent and condensing said solvent vapor on said surface, said vapor being admitted under pressure to increase the speed of condensation; cooling said surface to further increase the speed of the proc ess: drawing oil the condensed solvent and continuing the operation until nearly clean solvent drains oil; then shutting oh the influx of vapor and extracting the last remainders of condensed solvent by diminishing the pressure to produce a high degree of vacuum and evaporating said remaining solvent and sucking off the vapor created by such final flashing-out, and applying heat to increase the speed of the evaporation and the sucking oif.

2. A process for the cleaning of articles with hard surfaces to remove grease and oil from said surfaces, comprising the steps of diminishing the pressure in a closed space adjacent a surface to be cleaned, at the beginning of the operation; admitting into said closed space the vapor of a solvent and condensing said solvent vapor on said surface, said vapor being admitted under pressure to increase the speed of condensation; cooling said surface to further increase the speed of the process; drawing off the condensed solvent and continuing the operation until nearly clean solvent drains off; then shutting off the influx of vapor and extracting the last remainders of condensed solvent by reducing the pressure to such an extent that the last remaining portions of liquid retained on said surface in undrainable pockets and inaccessible spaces are forcibly evaporated by reducing the evaporation point in said closed space by said reduction of pressure, and utilizin the latent heat in the solvent to be evaporated and also the heat emanated through the surfaces of the masses of material being cleaned to provide the heat required fOr evaporation, resulting in a flashing-out process and increasing the completeness of the recovery of solvent for re-condensing and re-use.

3. A process for treating the interior of vessels for removing grease and oil, comprising the steps of diminishing the pressure in a closed vessel, at the beginning of the operation; admitting into said vessel the vapor of a solvent and condensing said solvent vapor therein, said vapor being admitted under pressure to increase the speed of condensation; cooling a surface of said vessel to further increase the speed of the process; drawing of! the condensed solvent and continuin the operation until nearly clean solvent drains off; then shutting off the influx of vapor and extracting the last remainders of condensed solvent by diminishing the pressure to produce a high degree of vacuum and evaporating said remaining solvent and sucking of! the vapor created by such final flashing-out, and applying heat to increase the speed of the evaporation and the sucking off.

4. A process for treating the interior of vessels for removing grease and oil, comprising the steps of diminishing the pressure in a closed vessel adjacent a surface to be cleaned, at the beginning of the operation; admitting into said vessel the vapor of a solvent and condensing said solvent vapor on said surface, said vapor being admitted under pressure to increase the speed of condensation; cooling said surface to further increase the speedpf the process; drawing oil the condensed solvent and continuing the operation until nearly clean solvent drains off; then shutting oflf the influx of vapor and extracting the last remainders of condensed solvent by reducing the pressur to such an extent that the last remaining portions of liquid retained on said surface in undrainable pockets and inaccessible spaces are forcibly evaporated by reducing the evaporation point'in said closed space by said reduction of pressure, and utilizing the latent heat in the solvent to be evaporated and also the heat emanated through the surfaces of the masses of material being cleaned to provide the heat required for evaporation, resulting in a flashing-out process and increasing the completeness of the recovery of solvent for re-condensing and re-use.

i 5. A process for treating the interior of vessels for removing grease and oil, comprising the steps of diminishing the pressure in a closed vessel adjacent a surface to be cleaned, at the beginning of the operation; admitting into said vessel the vapor of a solvent and condensing said solvent vapor on said surface, said vapor being admitted under pressure to increase the speed of condensation; cooling said surface to further increase the speed of the process; drawing off the condensed solvent and continuing the operation until nearly clean solvent drains off; then shutting off the influx of vapor and extracting the last remainders of condensed solvent by diminishing the pressure to produce a high degree of vacuum and evaporating said remaining solvent and sucking 011' the vapor created by such finaLflashing-out, and applying heat to increase the speed of the evaporation and the sucking off together with maintaining a diminished pressure at an outlet of said vessel to increase the rate of flow of solvent vapor to said closed vessel from a still connected therewith in order to have always the hottest fresh vapor from said still available within all parts of the closed vessel and to increase the rate of evaporation of the solvent in said still and thus increase the quantity of condensation thereof in any given time on the surface to be cleaned, thereby reducing the degreasing time.

6. A process for treating the interior of vessels for removing grease and oil, comprising the steps of diminishing the pressure in a closed vessel adjacent a surface to be cleaned, at the beginning of the operation; admitting into said vessel the vapor of a solvent and condensing said solvent vapor on said surface, said vapor being admitted under pressure to increase the speed of condensation; drawing off the condensed solvent and continuing the operation until'nearly clean solvent drains off; then shutting off the influx of vapor and extracting the last remainders of condensed solvent, by reducing the pressure in said closed vessel and applying heat in addition to the latent heat of the solvent to be evaporated and the heat emanating through the surfaces of the masses of material being cleaned, said reduction of pressure and said heat being sufficient to cause the last remaining portions of liquid retained within said vessel in" undrainable pockets and inaccessible spaces to be forcibly evaporated and resulting in a flashing out process and increasing the completeness of the recovery of solvent for re-condensing and re-use.

7. A process for the cleaning, of articles with hard surfaces, to remove grease and oil from said surfaces, comprising the steps of enclosing an article to be cleaned within a. closed shell, diminishing the pressure in said shell adjacent a surface to be cleaned, at the beginning of the operation; admitting into said closed shell the vapor of a solvent and condensing said solvent vapor on said surface, said vapor being admitted under pressure to increase the speed of condensation; cooling said surface to further increase the speed of the process; drawing off the condensed solvent and continuing the operation until nearly clean solvent drains off; then shutting on the influx of vapor and extracting the last remainders of condensed solvent by diminishing the pressure to produce a high degree of vacuum and evaporating said remaining solvent and sucking off the vapor created by such final flashing-out, and applying heat to increase the speed of the evaporation and the sucking off.

8. A process for the cleaning of articles with hard surfaces to remove grease and oil from said surfaces, comprising the steps of enclosing an article to be cleaned within a closed shell, diminishing the pressure in said closed shell adjacent a surface to be cleaned, at the beginning of the operation; admitting into said closed shell the vapor of a solvent and condensing said solvent vapor on said surface, said vapor being admitted under pressure to increase the speed of condensation; cooling said surface to further increase the speed of the process; drawing off the condensed solvent and continuing the operation until nearly clean solvent drains off; then shutting off the influx of vapor and extracting the last remainders of condensed solvent by reducing the pressure to such an extent that the last remaining portions of liquid retained on said surface in undrainable pockets and inaccessible spaces are forcibly evaporated by reducing the evaporation point in said closed shell b said reduction of pressure, and utilizing the latent heat in the solvent to be evaporated and also the heat emanated through the surfaces of the masses of material being cleaned to provide the heat required for evaporation, resulting in a flashing-out process and increasing the completeness of the recovery of solvent for re-condensing and re-use.

9. A process for the cleaning of articles with hard surfaces, to remove grease and oil from said surfaces, comprising the steps of enclosing an article to be cleaned within a closed shell, diminishing the pressure in said closed shell adjacent a surface to be cleaned, at the beginning of the operation; admitting into said closed shell the vapor of a solvent and condensing said solvent vapor on said surface, said vapor being admitted under pressure to increase the speed of condensation; cooling said surface to further increase the speed of the process; drawing off the condensed solvent and continuing the operation until nearly clean solvent drains off then shutting off ,the influx of vapor and extracting the last remainders of condensed solvent by diminishing the pressure to produce a high degree of vacuum and evaporating said remaining solvent and sucking off the vapor created by such final flashing-out, and applying heat to increase the speed of the evaporation and the sucking off; together with maintaining a diminished pressure at an outlet of said closed shell to increase the rate of flow of solvent vapor to said closed space from a still connected therewith in order to have always the hottest fresh vapor from said still available at all parts of the closed space and to increase the rate of evaporation of the solvent in said still and thus increase the quantity of condensation thereof in any given time on the surface to be cleaned, thereby reducing the degreasing time.

10. A process for the cleaning of articles with hard surfaces, to remove grease and oil from said surfaces, comprising the steps of enclosing an article to be cleaned within a closed shell, diminishlng the pressure in said closed shell adjacent a surface to be cleaned, at the beginning of the operation; admitting into said closed shell the vapor of a solvent and condensing said solvent vapor on said surface, said vapor being admitted under pressure to increase the speed of condensation; cooling said surface to further increase the speed of the process; drawing off the condensed solvent and continuing the operation until nearly clean solvent drains off; then shutting off the influx of vapor and extracting the last remainders of condensed solvent, by reducing the pressure in said closed shell and applying heat in addition to the latent heat of the solvent to be evaporated and the heat emanating through the surfaces of the masses of material being cleaned, said reduction of pressure and said heat being sufficient to cause the last remaining portions of liquid retained on said surfaces in undrainable pockets and inaccessible spaces to be forcibly evaporated and resulting in a flashing out process and increasing the completeness of the recovery of solvent for re-condensing and reuse.

11. A process for the cleaning of articles with hard surfaces to remove grease and oil from said surfaces, comprising the steps of diminishing the pressure in a closed space adjacent a surface to be cleaned, at the beginning of the operation: admitting into said closed space the vapor of a solvent and condensing said solvent vapor on said surface, said vapor being admitted under pressure to increase the speed of condensation; cooling said surface to further increase the speed of the process; drawing off the condensed solvent and continuing the operation until nearly clean solvent drains ofi; then shutting off the influx of vapor and extracting the last remainders of condensed solvent b diminishing the pressure to produce a high degree of vacuum and evaporating said remaining solvent and sucklng off the vapor created by such final flashingout, and applying heat to increase the speed of the evaporation and the sucking ofi; together with maintaining a diminished pressure at an outlet of said closed space to increase the rate of flow of solvent vapor to said closed space from a still connected therewith in order to have always the hottest fresh vapor from said still available at all parts of the closed space and to increase the rate of evaporation of the solvent in said still and thus increase the quantity of condensation thereof in any given time on the surface to be cleaned, thereby reducing the degreasing time.

12. A process for the cleaning of articles with hard surfaces to remove grease and oil from said surfaces, comprising the steps of diminishing the pressure in a closed space adjacent a surface to be cleaned, at the beginning of the operation; admitting into said closed space the vapor of a solvent and condensing said solvent vapor on said surface, said vapor being admitted under pressure to increase the speed of condensation; cooling said surface to further increase the speed of the process; drawing off the condensed solvent and continuing the operation until nearly clean solvent drains off; then shutting off the influx of vapor and extracting the last remainders of condensed solvent, by reducing the pressure in said closed space and applying heat in addition to the latent heat of the solvent to be evaporated and the heat emanating through the surfaces of the masses of material being cleaned, said reduction of pressure and said heat being suflicient to cause the last remaining portions of liquid retained on said surfaces in undrainable pockets and inaccessible spaces to be forcibly evaporated and resulting in a flashing-out process and increasing the completeness of the recovery of solvent for re-condensing and re-use.

PAUL L. GEIRINGER.

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