US2585638A - Apparatus for recovering volatile materials - Google Patents

Description

Feb. 12, 1952 E. F. DREW 2,585,638

APPARATUS FOR RECOVERING VOLATILE MATERIALS Original Filed Aug. 23, 1945 IPEMO #441 OVER/"10W coo $754M A INVENTOR. [RA/57 F 025w Patented Feb. 12. 1952 APPARATUS FOR RECOVERING VOLATILE MATERIALS Ernest F. Drew, New York, N. Y., assignor to E. F. Drew & 00., Inc., New York, N. Y., a corporation of Delaware Original application August 23, 1945, Serial No. 612,275. Dividedrand thisapplication July 24, 1948, Serial No. 40,504

4 Claims. (Cl. 23-283) .The present invention is directed to oils and j fats and more particularly to an apparatus for the treatment of waste and objectionable vapors emanating from the splitting of such oils and fats" for the production of free fatty acids. The application is a division of copending applicaation Serial No. 612,275 filed August 23, 1945, entitled Method of Recovering Volatile Materials, now Patent No. 2,471,942.

In said application the prior art was discussed inwhich it has been common practice to treat vegetable and other oils and fats which are glyc'erides ofmixed higher fatty acids in order to hydrolyze the same and to split the fatty acids from the glycerine. This has been accomplished by the use of such splitting agents as mineral acids, Twitchell reagent and the like, under the application of heat and sometimes of pressure.

Such processes give rise to vapors having undesirable and. often disagreeable odors which in many cases-presented a great nuisance to the surrounding community if such vapors were allowed to escape during the process. Such vapors include in most cases, in addition to the disagree "able odo1"s,vapors of water, mineral acid, fatty acid and glycerine. derived from the sulphonating or splitting agent Some of the vapors may he used in the process. Attempts have been made to prevent the diffusion of such vapors into the outside air both to abate the nuisance caused by such vapors in a community and to prevent the unnecessary loss i of valuable ingredients in said vapors. However, efforts to economically recover such vapors have present invention to provide a means for fractionating the fatty acids of certain oils and fats whereby a mixture of lower fatty acids contained in such oils may be recovered.

In practicing the present invention, there is provided an absorption tower into which the waste vapors are led and allowed to pass upwardly through the same. In the center of the tower is an absorption unit having a solution ofcaus'tic soda passing downwardly counter-current to the upwardly traveling vapors. A body *of caustic alkali solution is maintained in the bottom of the tower with a pump or the like for circulating the same over the absorption unit. The cycle of treatment is maintained until a certain concentration of fatty acid has been absorbed in the caustic alkali in the form of soap. Usually from 4 to 5% of fatty acid in the solution is considered sufficient to enable economical recovery of the fatty acid from the solution. It is desirable to have a minimum concentration of caustic alkali in the solution of about 2% in order to avoid interference by foaming of the soap in the solution. It is also important that the solution being circulated be kept at a relatively high temperature, usually in the neighborhood of the boiling point of water in order that there shall be a minimum of absorption of water vapor from the mixed vapors being treated. This contributes greatly to the effectiveness of the operation.

'Such a process enables the recovery of substantially all of the fatty acids which may be present in the vapors and the absorption is in such a form that the fatty acids may be readily recovered therefrom. Simultaneously therewith, the objectionable odors present in the vapors are also absorbed and are eliminated from the atmosphere. When such oils as the coconut type of oil is treated, the vapors thereof contain the lower fraction of the fatty acids present in the original oil and the absorption of such fatty acids from the vapors is capable of providing the mixed lower fatty acids, which as a unit are eminently suitable for adaptation in commerce, as for example, in the form of the polyalkylenc glycols for use as plasticizers.

In the accompanying'drawing constituting a part hereof and in which like reference characters indicate like parts, the single figure is a' vertical cross-sectional view taken through an apparatus made in accordance with the present application, some parts being shown in elevation and other parts being shown diagrammatically. In the treating vessel I, there is performed the operation of splitting the oil or fat by any of the usual reagents. The vapors produced in the-process pass through duct or pipe 2 which extends vertically upward through the central part of the bottom 3 of a vertical tower 4. The upper end 5 of duct 2 is provided with a series of openings to allow the vapors to escape into the tower. A cap; is' provided at the top of pipe 2 to prevent accidental en'trance of solution into the same: g

along with the same.

in the tank becomes too high, the liquid passes through pipe I into overflow-chamber I l and out through l2 for re-use.

In the bottom 3 of the tower which slopes slightly and at the lowest point thereof, there is an exit opening 13 and a :pipe is leading .to

pump IS. A pipe I6 from the pump has a check valve Il therein, said pipe extending upwardly and then horizontally as shown at [8, passing into the tower at an intermediate point thereof intoqspace 19. .A spray head is adapted to .disseminate liquid into the tower. .Betweenwhorizontal perforated platesi2l and 22 .isan absorption unit 23 of 'any suitable type, such as the well-known Raschig .rings, .suitably packed in order to cause liquid to passdownwardly over the surfaces in contact with the vapors passing upwardly in the unit.

Above the spray 20 are a pair of similar horizontal perforated plates *24 and 25 having between the same a packing or filling 26 which may also be of Raschig rings. The spent gases and vapors 'after 'passage'through the unit 26 enter'upper end 21 of the tower and pass out therefrom through opening or stack 28.

, In the operation of the apparatus for thetreatmerit of the waste vapors, the caustic soda solution is maintained at about the boiling point ,of

'water and is continuously circulated by pump ll. Vapors are allowed to pass throughthe duct 2 out of openings 5 and upwardly through absorption unit 23. The vapors come into intimate contact with the hot caustic soda solution whereby all acid vaporsare absorbed and recovered from the vapors. Because of the high temperature of the solution, very little, if any, water vapor is absorbed therein and'itpasses up out of the absorption unit with other unabsorbed substances. The circulation of the liquid is continued, causing a gradual building up in the solution of fatty acid soaps. When the fatty acid content reaches l'to 5% or higher and the caustic soda content is down to about 2%, the solution may be removed for the recovery of the fatty acids. A 'fresh caustic soda solution is introduced and the cycle is continued.

Due to the fine sub-division of the solution as it is sprayed from-the spray head into 'the tower, and the upwardly flowing current of gases and vapors, some of the solution may be carried Therefore, the spray removal unit 26 is provided, which catches the spray on the packing material and the solution flows downwardly and eventually reaches the absorption unit. The temperature of the spray removal unit is also preferably maintained at about the boiling point of water so as not to dilute the solution. Therefore, the gases passing out through stack '28 contain substantially all of the water vapor which had been present in-the vapors in duct 2.

The solution "containing "the soaps may :then

the acidulated as by the use of sulphuric acid-in the usual. manner to split-the "soap :stock. The resulting product contains at least 99% of fatty 4 acids and they may be used as such or be redistilled or otherwise treated for further purification.

The present invention is adapted for use in all cases where fats and oils :ofia glyceride fatty acid typeare split to recover fatty 'acids. The invention is particularly adapted for use where the coconut type of oil is split. Such oils contain a substantial amount of lower fatty acids having-6, 8, '10, '12 and 14 carbon atoms in addition to the fatty acids of 16 and 18 carbon atoms which are present in practically all vegetable and animal oils. It has been found that the vapors produced in the splitting of, say, coconut oil, contain only the lower fatty acids present in such -oil having .from 6 to 12 carbon atoms. When such a mixture of fatty acids is recovered first in the form of soap and then in the form of the mixture of free fatty acids, the approximate composition thereof is as follows:

' Per cent 'Caproic (C6) "15.9 Caprylic '(Ca) "'5'6L8 Capric (C10) 119.4 Lauric-l-etc. (012+) 7.9

Therefore, the present invention .IPI'OVidCS .a simple and inexpensive means for Ifraction'ating the fatty acids of coconut oil to recover amixture of lower fatty acids- Thesehave been found eminently suitable for use as the :mixedpolyethylene glycol esters, as plasticizers for various resinous materials, synthetic rubber and the like.

Although the invention .has been describedby use of a certain specific example, the invention is not limited thereto as various modifications in the process and the apparatus :may "be-made within the scope of the invention. For-instance, the caustic soda solution may be used 1until-the concentration of. the fatty acid is greater than that specified herein, or the caustic soda content thereof may be replenished continuously or :in-'

termittently. Also, the process may zbeioperated so that a part of the caustic soda is withdrawn for the recovery of fatty acids and the volume replenished by fresh caustic soda solution. Other alkalis than sodium hydroxide may, of course, be used in the process. The minimum concentration of alkali may be less'than 2% in some cases.

The absorption units maybe of .differentcharacter and under suitable conditions the'units may be entirely omitted where the tower is sufficiently high and the absorption of .the'fatty acids and objectionable odors is-sufficiently completewithout the necessity of packing in the tower; The tower need not be made in a single vertical "unit but one or more of the elements suchas the container, absorption unit and'spray removal unit may be made separately and suitably coupled together. Such units may be'placed in a-vertical position or they may be horizontallydisplaced. In'place of steam, other meansmay 'beusedffor maintaining the desired temperature of the circulating solution.

The invention is applicable not onlyito vapors resulting from the splitting of oils 'and fats-but also to vapors arising from various'otherwperations on glyceride oils, fats, fatty acids, soap stock, and others, wherein the 'vaporsicontainia'cid constituents, water vapor: and objectionable odors. These and other-changeszinxthe detailsbfithe practice of the inventionmay ibe mad-e'without departing from Y the spirit :thereof :and the iinvem tion is to -'be broadly construed :and not ":to :be

limited except by the spirit of the claims appended hereto.

I claim:

1. An apparatus for treating waste gases and vapors from the hydrolysis of oils and fats comprising a set of three vertically disposed chambers constituting a single tower, perforated plates between said chambers, an inlet pipe for said vapors extending centrally through the bottom of the lowest chamber and terminating at the top thereof, the top of said pipe having perforations in its sides and a cap on the upper end thereof, a spray head in the top of the intermediate chamber and packing material in the lower part thereof, a pipe connection from said spray head to the bottom of said lowest chamber, an overflow pipe in the upper part of said lowest chamber adapted to draw oif liquid from a point just below said perforations, distance between said overflow pipe and the bottom of said lowest chamber adapted to permit a deep body of liquid to be maintained therein, the area of said inlet pipe submerged in said liquid being suflicient to provide material heat exchange with said liquid, a heating coil for maintaining said body at about the boiling point of water surrounding said inlet pipe below said overflow pipe, packing material in the uppermost chamber, and an exit stack centrally of the top of said uppermost chamber.

2. An apparatus for treating waste gases and vapors from the hydrolysis of oils and fats com prising a set of three vertically disposed chambers constituting a single tower. perforated plates between said chambers, an inlet pipe for said vapors extending centrally through the bottom of the lowest chamber and terminating at the top thereof, the top of said pipe having perforations in its sides and a cap on the upper end thereof, a spray head in the top of the, intermediate chamber and packing material in the lower part thereof, a pipe connection from said spray head to the bottom of said lowest chamber, a pump in said connection for causing liquid to flow through said spray head, an overflow pipe in the upper part of said lowest chamber adapted to draw ofi liquid from a point just below said perforations, distance between said overflow pipe and the bottom of said lowest chamber adapted to permit a deep body of liquid to be maintained therein, the area of said inlet pipe submerged in said liquid being suflicient to provide material heat exchange with said liquid, a heating coil for maintaining said body at about the boiling point of water surrounding said inlet pipe below said overflow pipe,

packing material in the uppermost chamber, and a an exit stack centrally of the top of said uppermost chamber.

3. An apparatus for treating waste gases and vapors from the hydrolysis of oils and fats comprising a set of three vertically disposed chambers constituting a single tower, perforated plates between said chambers, an inlet pipe for said vapors extending centrally through the bottom of the lowest chamber and terminating at the top theret e top of said p pe having p rtorat oas in its sides and a cap on the upper end thereof, a spray head in the top of the intermediate chamber and packing material in the lower part thereof, the space surrounding said spray head being free from packing material, a pipe connection from said spray head to the bottom of said lowest chamber, an overflow pipe in the upper part of said lowest chamber adapted to draw off liquid from a point just below said perforations, distance between said overflow pipe and the bottom of said lowest chamber adapted to permit a deep body of liquid to be maintained therein, the area of said inlet pipe submerged in said liquid being sufiicient to provide material heat exchange with said liquid, a heating coil for maintaining said body at about the boiling point of water surrounding said inlet pipe below said overflow pipe, packing material in the uppermost chamber, and

an exit stack centrally of the top of said uppermost chamber.

4. An apparatus for treating waste gases and vapors from the hydrolysis of oils and fats comprising a set of three verticallydisposed chambers constituting a single tower, perforated plates between said chambers, an inlet pipe for said vapors extending centrally through the bottom of the lowest chamber and terminating at the top thereof, the top of said pipe having perforations in its sides and a cap on the upper end thereof and a cap thereon, a spray head in the top of the intermediate chamber and packing material in the lower part thereof, a pipe connection from said spray head to the bottom. of said lowest chamber, an overflow pipe in the upper part of said lowest chamber adapted to draw off liquid from a point just below said perforations, distance between said overflow pipe and the bottom of said lowest chamber adapted to permit a deep 1 body ofliquid to be maintained therein, the area of said inlet pipe submerged in said liquid being suflicient to provide material heat exchange with said liquid, a heating coil for maintaining said body at about the boiling point of water surrounding said inlet pipe below said overflow pipe, packing material in the uppermost chamber, and an exit stack centrally of the top of said uppermost chamber.

ERNEST F. DREW.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,226,898 Lummus May 22, 1917 1,470,116 Gray Oct. 9, 1923 1,928,495 Jacobson Sept. 26, 1933 2,161,122 Anderson June 6, 1939 FOREIGN PATENTS Number Country Date 120,304 Great Britain Nov. 7, 1918 211,542 Great Britain Feb. 28, 1924

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