US2281534A - Method and apparatus for hydrolyzing fats and oils - Google Patents

Description

April 28,1942. w. DAVEYETAL I2,281,534

METHOD AND APPARATUS FOR HYDROLYZING FATs AND oILs Filed Aug; 26, 1959 2 sheets-sheet 1 April 28, 1942. w. DAVEY Erm. 2,281,534`

` METHOD AND APPRATUS FOR HYDROLYZING FATS OILS Filed Aug. 26, 1939 2 Sheets-Sheet 2 'I atented 25,' i942 castrar METHDD APPTUS FOR HY- DROLYZIN G FATS AND GILS Warren Davey, Montclair, and Martin Hill Ittner,

Jersey City, N. J., assignors to Colgate-Palm-` olive-Peet Company, Jersey City, N. J., a corporation of Delaware Application August 26, 1939, Serial No. 292,056

(Cl. 26o-415) 13 Claims.

This invention relates to a process and apparatus for hydrolyzing fats and oils. It relates more particularly to an improvement on countercurrent hydrolysis processes such as are disclosed and described -in U. S. Patent No. 2,139,589 to Martin H, Ittner and U. S. Patent No. 2,156,863 to Victor Mills,`and the concurrentcountercurrent process disclosed in U. S. Patent No. 2,221,799 to Martin H. Ittner.

An object of this invention is to conserve and utilize the heat in' the fatty acid mixture and glycerine-water mixture produced, thus lessening the cost of production. Another object is to produce relatively pure, substantially unoxidized fatty acids and a glycerine-water mixture of high glycerine content.

In the Ittner process, fatty materials and water are treated ina 'vertical pressure'vessel at relatively high temperatures and at pressures which exceed` the pressure of saturated steam at the reaction temperature employed.

Both the fatty acids containing dissolved water and the glycerine-water produced are discharged from the pressure vessel at the pressure and. temperature of operation and contain a considerable amount of sensible heat. In any process involving hydrolysis of fats and oils care must be taken that the fatty acids at highI temperatures are not exposed to air or a material darkening will result, thus rendering them less desirable for use.

This sensible heat is available for many useful purposes if properly controlled and suitable means provided to take advantage thereof. A portion of the heat may be recovered by `the use of heat exchangers, for example, to preheat the reactants. Alternatively, the outcoming materials maybe ashedf thus evaporating part of the water content. However, since all of the liquids passing through the heat exchangers are under relatively high pressures (which may be in the order of 600 pounds per square inch, or over), the heat exchangers must be designed to withstand high pressures. Furthermore, the heat exchangers are preferably made of corrosion resistant alloys, due to the corrosive nature of the materials. Under the most favorable conditions of operation, the heat thus recovered will probably not exceed seventy -per cent of the heat available, and the glycerine- It has now been found that in a majority of cases there is enough sensiblel heat in the outcofming fatty acids and glycerine-water mixtures, if employed according to the principles of this invention, to not only vaporize practically all of the water in the glycerine-water mixture to yield glycerine of high concentration, but also to supply steam of various pressures which may be employed for preheating the incoming fatty materials and water to substantially 'high temperatures', for operating a vacuum ejector apparatus for maintaining a diminished pressure in an evaporator or glycerine concentrator, and for various other uses.

It -is preferable to iiash the glycerine-water mixture to a pressure and temperature well below the point at which glycerine will appreciably water, preferably distilled or. treated to remove impurities, 2 is a supply tankfor oil or fatty material, also'preferably treated for the removal of impurities.

The water is fed through pipe 3 to heat exchanger d, thence through pipe E to pump 6.

Oil or fatty material is fed through pipe 'i to heat exchanger 8, thence through pipe 9 to pump 6,.

Pump 6 is preferably a duplex single-acting pump of the plunger type, provided with a variable speedA drive and a separate device on each cylinder to vary the length of the stroke, so that any amounts of water and fatty material may be pumped in proper proportions, withintermittent or alternate discharge, although any type of pump or pressure producing mechanism may be employed. I

Pump 6 discharges water through pipe I0 and fatty materials through pipe II.

Pipe Ill leads to a high temperature heater t2 and discharges through pipe I3 into the upper portion of the pressure reaction vessel I4.

Pipe II leads to a high temperature heater I5 and discharges through pipe I6 into the lower portion of the pressure reaction vessel I4.

'The hydrolysis of the fatty material takes place in pressure vessel I4 forming fatty acids containing dissolved Water and a glycerine-water solution.

A preferred type of pressure vessel consists of a high-Vertical, carbon steel, pressure-resistant shell clad with a thin layer of corrosion resistant material, having relatively the same coefficient of expansion as. the carbon steel, and an inner reaction chamber made from highly corrosionresistant material free to move in relation to the outer shell, the pressure around and within the inner chamber being equalized by introducing steam in the surrounding space.

The fatty acid mixture is discharged from presferred to, and the vapor released from the glycerine-water solution as ash steam, as well as vapors' generated by the absorption of heat from coils 35 and 39, discharges through pipe 42 into barometric condenser 43, and any air or noncondensable vapors are removed by vacuum ejecsure vessel I4 through pipe I'I and the glycerinewater mixture is discharged from pressure vessel I4 through pipe I8.

Vessel I9 is a pressure boiler fitted with closed heating coils 20.

The fatty acid mixture is passed through coils 20 under pressure, entering at the temperature at which it leaves the reaction pressure vessel I4.

Water is supplied to boiler I9 through pipe 2| and a considerable portion ofthe sensible heat in the fatty acid mixture is absorbed in evaporating this water into steam.

Suitable control valves (not shown) regulate the flow of water into boiler I9 and steam therefrom.

A portion of the steam thus generated is passed through pipe 22 to a vacuum ejector 23, and the balance is'passed through pipe 24 to oil heat exchanger 8. K

The condensate passes out of heater 8 through pipe 25 and trap 26. A drainage connection 2'I may be provided for emptying boiler I9.

The partially cooled mixture of fatty acids and water is now led through pipe 28 and is passed through closed coils 29 in another similar boiler 30.

The glycerine-water solution discharged 'from pressure vessel I4 through pipe I8- isv passed through a suitable relief valve 3I and allowed to flash into boiler 30.

vdrawn off through valves 50, 5I and 52 and receivers 53 and 54 into receiving tank 55.

A drainage connection 56 may be provided for n emptying evaporator 36.

Suitable control valves (not shown) are provided for the water level, pressure, etc. in evaporator 36.

. High pressure boiler 5'I supplies steam for heating the water in heater I2 and the fatty material in heater I5 up to the desired temperature.

The steam is passed up through pipes 58 and 59, and the condensate is returned to boiler 51 Another considerable portion of the sensible heat in the fatty acids-water mixture is absorbed in evaporating some of the water from the glyc-l crine-water solution fed to boiler 30. Steam thus generated together with steam liberatedby ashing is discharged through pipe 32. Suitable control valves (not shown) are provided for regulating the pressure and flow through boiler 30.

A drainage connection 33 may be provided for emptying boiler 30.

The fatty acids-water mixture is led through pipe 34 and passed through closed coils 35.to evaporator 36. Y

The partially concentrated glycerine-water solution leaving boiler 30 is passed through pipe 31 and allowed to ash into evaporator 36.

Another considerable portion of the sensible heat in the fatty acids-water mixture is absorbed in evaporator 36,A in further evaporation of some of the water from `the glycerine-water solution fed from boiler 30.

A portion of the steam discharged from boiler 30 through pipe 32 is led through pipe 38 and closed heating coils 39 in evaporator 36. The condensate from coils 39 passes out through pipe 40 and trap 4I.

Evaporator 36 may be of the cascade type (a more detailed description of which appears hereinafter), and is maintained at a diminished pressure by means of a vacuum ejector 23 above rethrough pipe 60.

sure vessel I4 through pipe 6 I, and any condensate may be removed through trap 62, or returned to boiler 5'I.

The above description is, in general, a diagrammatic disclosure of the process of this invention.

In order to present a more thorough understanding of the process, a specific example of its operation is given. Quantitiesl and proportions of fatty materials and water and glycerine, as well as temperatures and pressures, are taken from data obtained from actual operations.

It will be clear that there'may be an almost unlimited number of combinations of quantities and temperatures and pressures, and results will vary depending on the operating conditionsI selected, namely, as to the pressures and temperatures inthe various units and the amount of heating surfaces supplied to effect the nal result.I In any event, the fundamental principle may be better illustrated by the following example:

Quantities fed:

Fatty material (glycerides) lbs. per hour 5000 Water do 3000 Reaction temperature 244 C. (471 F.)

Yields:

Pounds Fatty acids 4773 Water dissolved or mixed with fatty acids-- 850 Glycerine 550 Water in'glycerine solution (23% glycerineA concentration) 1827 The heat added to the pressure reaction vessel per hour is about 1,362,000 B t. u'. in 5,000 pounds of the fatty materials and about 1,362,000 B. t. u. in 3,000 pounds of water fed, a total of approximately 2,724,000 B. t. u. per hour. The heat in the materials removed from the pressure reaction vessel per hour is about 1,747,900 B. t. u. in 5,623 pounds of the fatty acids-water mixture and about 974,400 B. t. u. in 2,377 pounds of the glycerine-water solution, a total of approximately 2,722,300 B. t. u. per hour. Thus'it will be seen Pounds per square inch (absolute) 105 Y Pounds per square inch (absolute) Pounds per square inch (absolute) 3 The fatty acids-water mixture-leaves the pressure reaction vessel at about 471 F. and leaves coils 20, 29 and 35 at temperatures of about 344 F., 286 F. and 170 F., respectively.

Water fed to boiler I9"is taken at an initial temperature of 160 F. The drop in temperature of the fatty acids-water mixture in coils 20, from about 471 F. to 344 F., will give up approximately 534,000 B. t. u. which, when applied to the water fed into boiler I9, will vaporize about 500 pounds and convert it into 500 pounds of steam per hour at 105 pounds absolute pressure. Vacuum ejector 23 will require about 125'pounds of impelling steam per hour. This leaves 375 pounds of steam for use in 'heater 8. The available latent heat in this steam is about 332,000 B. t. u. per hour. The fatty material in supply tank 2 is taken at an initial temperature of 140 F. If the above 332,000 B. t. u. are applied to 5,000 pounds of fat introduced in heater 8 at 140 F., the temperature will be raised to 250 F.

To further heat the fatty material from 250 F. to 471 F. will require about 706,000 B. t. u. which will be supplied by high pressure steam from boiler 51.

. The glycerine-water solution at 471 F., passing `through relief valve 3l into boiler 30, will .partially flash into steam and thus become more concentrated. 'Ihe boiling point of pure water to about 168 pounds. The fatty acids-water mixture entering coils 35 in evaporator 36 at 286 F. and leaving at 1709 F. will give-up` approximately 452,000 B. t. u. which, when applied to the glycerine-water solution, will further evaporate about 433 pounds of the water therefrom and convert it into an equivalent amount of steam atv 3 pounds absolute.

The flash steam amounting to 168 pounds plus the additional generated steam amounting to 433 pounds make a total of 601 pounds, its evaporation thus leaving 475 pounds of water together with 550 pounds of glycerine in the glycerinewater solution. a concentration of about 54% glycerine.

In order to still further concentrate the glycerine solution to obtain a desirable concentration of about 94% it will benecessary to remove therefrom a further quantity of water, about 440 pounds.

at considerably higher temperatures than water,

, the boiling point of the above concentrated glycat 35 pounds absolute is 259.3 F. However, the

glycerine-water solution will boil at a slightly higher temperature or in the neighborhood of 266 F.

The amount of flash steam thus liberated due to the 'reduction in pressure and temperature of the glycerine-water solution will amount to about 505-pounds. The fatty acids-water mixture entering coils 23 in boiler 30 at. 344 F. and

leaving at 286 F. will give up approximately 231,000 B. t, u. which, when applied to the glycerine-water solution in boiler 30, will further evaporate about 246 pounds of the waterand'convert it into an equivalent amount of steaml at 35 pounds absolute. The flash steam amounting to 505 pounds plus the additional generated steam amounting to 246 pounds make a total of 751 pounds of steam discharged from boiler 30,

its evaporation thus leaving 1,076 pounds of water together with 550 pounds of glycerine in the glycerine-watersolution, a concentration of a little over 33% glycerine.

The solution now at about 266 F. passing into evaporator 36 operating under diminished pressure will again partially flash into steam and become further concentrated. The boiling point of pure water at 3 pounds absolute, the pressure in evaporator 36, is 141.5" F. However, the glycerine-water solution will boil at a slightly higher temperature or in the neighborhood of 145 F. The amount of flash steam thus liberated due to the further reduction in pressure and temperature of the glycerine-water solution amounts erine being in the neighborhood of 220 F. It will require approximately 461,000 B. t. u. to remove 440 pounds of waterv from this solution. Steam from boiler 30 at 35 pounds absolute and at 259 F. is passed through coils 39 in' evaporator 36, and it will require about 490 pounds thereof to heat the glycerine-water solution to 220 F. and evaporate 440 pounds of water and convert it into steam at 3 pounds absolute. The total steam discharged from boiler 30 was found to be 751 pounds. This leaves 261 pounds of steam from boiler 30 at 35 pounds absolute available for heating the Water passing through heat exchanger 4.

The latent or available heat in this steam is about 245,000 B. t. u.Y per hour. The water in supply tank I is taken at an initialV temperature of "F. The above 245,000 B. t'. u. applied to 3,000 pounds of waterintroduced in heater 4 vat 100 F. will raise the temperature thereof to about F. To further heat this Water from 180 F. to 471 F. will require about 913,000 B; t. u.; which will be supplied by high pressure steam from The total heat furnished by boiler 5l will, therefore, be

B. t. u. for heating the fatty material 706,000 B. t. u. for heating the water -913,000 B. t. u. for radiation loss 66,200

B. t. u. per hour or approximately The figure 1,700,000 B. t. u. per hour represents all of the heat required forhydrolyzing 5000 pounds of fatty material to 4773 pounds of fatty acid and 550 pounds of glycerine and evaporating the glycerine solution to 94% concentration.'

It is also Well within the scope of this inven- 'tion to further recover considerable. additional heat from traps 26, 4I and 45, or to re-use all or a part of the condensate from thes-e traps in the process.

Of the 3000 pounds of water fed, about 323 pounds is absorbed chemically in the process and 2677 pounds is accounted for as 850 pounds of dissolved or mixed water with the fatty acids and 1827 pounds of water in the glycerine solution.

Concentrated glycerine solutions boill It is advantageous to use -in the process a cascade evaporator or one which is constructed in stages so that liquids and vapors passing therethrough are successively at higher temperatures or vice versa.

Figs. 2, 3, and 4 show a type of a so-called "cascade evaporator, Fig. 3 being an end view and Figs. 2 and 4 horizontal and vertical sections,

respectively.

Theglycerine-water solution entering the evaporator through pipe 3l will flash at a comparatively low temperature in the pan in the upper section.

Since it is desired to cool the fatty acids-water mixture to as low a temperature as possible, it is introduced through coils 35, where the glycerine-water solution is coolest and the temperature differential between them is greatest.v

As the temperature of the glycerine-water solution increases materially as the concentration increases, steam from boiler 3U under a pressure of 35 pounds absolute and having a temperature of about 259 F. may be used in coils 39 in the section of evaporator 38 where the glycerinewater solution has become more concentrated and a higher temperature is necessary for its vaporization.

The final concentration of the glycerine-Water solution may, of course, be accomplished in one or more vessels, but the advantages of using -a cascade" evaporator arranged as shown will become evident.

It is, of course, to beunderstood that all of the above temperatures and quantities of steam and vapor and concentration of glycerine solution produced may be varied considerably due to the exact arrangement of the apparatus employed and the amount of heating surfaces supplied in the several units; furthermore, an almost unlimited number of combinations may be evolved by changing the pressures on the various pieces of apparatus or by using more or fewer units, aiming, however, to accomplish the same results. The water content of the outcoming fatty acids and of the glycerine-water solutions varies with the kind and amount of fatty' materials introduced, andthe reaction pressure and temperature employed as well as with the proportion of fat and water used. The example given is clearly one of many similar or related possible arrangements, all of which embody the principles of this invention, to accomplish the desired results and is simply given to show the principle of the process involved.

We claim:

1. The process of producing fatty acids and concentrated glycerine which comprises hydrolyzing fats or oils under superatmospheric pressure and-at an elevated temperature, separately removing fatty acids containing some dissolved water and a glycerine-water solution from the hydrolyzing chamber, utilizing a portion of the heat in the fatty acid-water mixture to generate steam under pressure, preheating the oil or fat before introduction into lthe hydrolyzing chamber with at least a portion of the steam so generated, employing a portion of said steam for producing a vacuum, flashing the glycerinewater solutionv to evaporate a portion of the water therefrom as steam under pressure, utilizing a further portion of the heat in the out- 'coming Vfatty acids-water" mixture to further evaporate water vfrom the glycerine-water solution as steam under pressure, preheating the Water before introduction into the hydrolyzing agaemssst chamber with a. portion of the steam generated from the glycerine-water solution, utilizing another portion of the steam thus generated to further evaporate water from the concentrated glycerine-water solution at a lower pressure, flashing the partially concentrated glycerinewater solution to evaporate a portion of the water therein, and using a portion of the heat remaining in the fatty acids-water mixtureto further evaporate water from the concentrated glycerine-water solution at the lower pressure, the evaporation of water yfrom the concentrated glycerine solution being further assistedby reducing the pressure thereon below atmospheric.

2: The process of recovering heat obtained by splitting glycerine esters of fatty acids which comprises passing `the split fatty acids under pressure in indirect heat exchange relation with water to generate steam, then passing said acids in indirect heat exchange relation with the glycerine-water obtained from the. splitting, which glycerine-water has been flashed to a lower but still elevated pressure in order to generate steam and to concentrate the glycerine, then passing said fatty acids in indirect heat exchange relation with the concentrated glycerine from the second stage but at a reduced pressure inI order to generate additional steam and to yield a highly concentrated glycerine; the steam from the first stage of heat exchange being partially used for reducing the pressure by ejection and condensation for the third stage of heat exchange, a

part of the steam from the second stage of heat exchange beingV used for partially preheating one of the reactants for splitting, and the other part of the steam from the second stage of heat exchange being used for vaporizing water from the glycerine in the third stage of heat exchange by passing it in indirect heat exchange relation therewith; the steam- -from the third stage of heat exchange being condensed under vacuum generated by part of the steam from the first stage of heat exchange,

3. The process of producing fatty acids and a concentrated glycerine solution which comprises contacting glycerides of fatty acids and water by countercurrent flow at superatmospheric pressure and elevated temperature, separately removing the fatty acids and glycerine solution from the hydrolysis chamber, reducing the pressure upon the glycerine solution to permit the evaporation of some of the water from the glycerlne- I the evaporation of the water in at least one of.

the stages being promoted by -heating the glycerine-water solution by indirect contact with the fatty acids produced in the hydrolysis.

6. The process of recovering heat from fatsplittingwhich comprises passing the fatty acids in indirect heat exchange relation with water and glycerine-water to concentrate the glycerine and to generate steam, passing parts of the steam generated from such indirect heat exchange in acercar indlrectheat exchange relations with the reactants to partially preheat them, and electing a part of said steam at a high velocity to reduce the pressure on the glycerine in at least one stage of concentration thereof.

8. The process of concentrating glycerine from l fat-splitting which comprises flashing the glycerine-water solution and further concentrating the glycerine by utilizing the heat in the fatty acids by indirect heat exchange.

9. The process of producing substantially unoxidized fatty acids and concentrated glycerine which comprises hydrolyzing fatty acid esters of glycerol under superatrnospheric pressure and elevated temperature'in the presence of water,l

flashing the glycerine-Water solution produced by said hydrolysis and heating the glycerinewater solution by indirect contact with the fatty acids produced in said hydrolysis to concentrate the glycerine solution.

10. The process of .producing fatty acids and concentrated glycerine which comprises hydrolyzing fats or oils under superatmospheric pres-l sure and elevated temperature in the presence of water and utilizing at least a portion of the heat contained in the fatty acids to concentrate the glycerine-water solution by evaporating a portion ofthe water therefrom.`

l1. An apparatus for hydrolyzing -fats and oils and producing fatty acids and concentrated glyc- -erine which comprises, in combination with a pressure hydrolysis vessel, means lfor separately withdrawing fatty vacids and `glycerine solution therefrom, means for reducing the pressure on the glycerine solution, means for bringing the steam thus generated into indirect contact with the water feed to preheat it, means for bringing the fatty acids into indirect heat exchange relation with water to generate steam, means for bringing steam thus generated into indirect contact with the fat or oil feed, means for bringing the fatty acids into indirect heat relation with the glycerine-water solution, and means for further reducing the pressure on the concentrated glycerine solution to evaporate more water therefrom. Y

12. An apparatus for hydrolyzing fats and oils and producing fatty-acids and concentrated glyccrine which comprises a pressure hydrolysis Vessel, means for separately withdrawing fatty acids and glycerine solution from the hydrolysis vessel, and means for bringing the fatty acids into indirect heat relation with the glycerine solution While the glycerine solution is under a pressure lower than that in the hydrolysis Vessel to evaporate a portion of the Water from said glycerine solution.

13. An apparatus for hydrolyzing fats and oilsl and producing fatty acids and concentrated glycerine which comprises a pressure hydrolysis vessel, means for separately removing glycerine solution and fatty acids therefrom, means for reducing" the pressure on the glycerine solution to volatilize Water therefrom, and means for passing the fatty acids in indirect heat exchange with the glycerine-Water solution to further concentrate the glycerine.

- WARREN DAVEY. f

MARTIN HILL ITTNER..

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