US2100277A - Process for refining glyceride oil - Google Patents

Description

Nov. 23, 1937. a. CLAYTON PROCESS FOR REFINING GLYCERIDE OILS Original Filed Aug. 1, 1935 2 1d 5 m. Q 7 4/5 a a (I. 73 \\0N\ ulll 2 z 1 1 2 4 w M J w M z X e 2 x W a a 2 a 7 9 6% x J 3 J 0 v 5 5 \Nu 4 .0 E a Q Q L 0 u 7 u 4 lb. I: H M 2 w swam/tow,

Patented Nov. 23, 1937 UNITED STATES 2,100,277 PROCESS FOR DEFINING GLYOERIDE OIL Benjamin Clayton. Houston, Tex, asaignor to Be- Inc., Reno. New, a corporation of Ne- Application August 1. l0

newed September 20. 1937.

her 21, 1935 11 Claims.

This invention relates to a process and machine for separating heavy materials from light materials by centrifugal force in a continuous manner without the necessity of stopping the process int'ermittently for the purpose. of cleaning out the machine or opening clogged outlets.

The invention is especially adapted for the separation of soap stock from the oil after cottonseed oil or other glyceride oil has been treated with an alkaliin the refining process.

The invention also has special utility in connection with the separation of materials having similar problems of separation such as, for example, certain types of glue or other materials which are effected by contact with the walls of a centrifugal bowl which are heated to impart sensible heat thereto.

In the practical art of separating soap stock from glyceride type oils in the refining process, it has heretofore been impossible to continuously carry out the centrifugal separation in a truly continuous manner. An accumulation of soap stock has heretofore gradually built up along the inside surfaces of the centrifugal bowl and has necessitated frequent shut-downs and delays for manually cleaning relatively few hours out the machine. After a of operation, the amount of accumulated soap stock in the bowl of the cen-' trifugal has seriously interfered with proper separation, causing soap stock to be delivered with the oil and oil to be delivered with the soap stock. Various attempts have been made to overcome this difficulty by various expedients, including adiustments of centrifugals and modifications in design thereof, but without success.

My invention is based upon the discovery .that a centrifugal separator is an extremely efllcient refrigerating apparatus in that it rapidly cools down substances which are above room temperature in the bowl and in contact with the outer walls thereof. The rapidly revolving centrifugal bowl which in conventional machines may have a speed of 7,000 to 15,000 R. P. M. intensely agitates the air surrounding the bowl such that a very large amount of air is contacted therewith in a relatively short interval of time. The heat of substances within the bowl is rapidly conducted through the walls thereof and delivered to the large volume of air which constantly comes in contact with the outer surfaces of the bowl.

I have found that by heating the air or gaseous medium surrounding the bowl, this loss of heat can be prevented. It is, therefore, an object of my invention to provide an apparatus and a process of centrifugal separation wherein the Serial No. 34,358. lte- Canada In Decemloss of heat from substances within the bowl is prevented.

In glyceride oil refining processes I have usually found it necessary not only to prevent the loss of heat due to the refrigerating effect of the 5 revolving bowl but to supply heat to the soap stock in the bowl which is in contact with the inner walls thereof. According to the present invention the temperature of the gaseous medium surrounding the bowl may be increased so that the temperature of the heavy eilluent discharged from the bowl is higher than that of the entering materials.

Soap stock, which is a heavy viscous material, contains components which, in prior practice, contact the inner surfaces of the cool outer walls and portions thereof have the tendency to stick or adhere thereto, particularly because of the substantially lower temperature of these outer walls. The gradual accumulation of soap stock shifts the neutral zone of separation to such an extent that soap stock is discharged with the refined oil. I have found that by applying the proper amount of heat to the outer surface of the bowl, the soap stock can be made to slip or slide along the inner surfaces of the bowl. This sliding action has a scouring effect upon these surfaces such that any particles of soap stock which tend to adhere thereto are carried along by the sliding mass of soap stock. It is, therefore, another object of my invention to apply sufficient heat to the outer surfaces of the centrifugal to cause said slipping action.

It is not only necessary that the soap stock slide along the inner surfaces of the centrifugal bowl but it must move in a uniform manner. I have found that, in prior processes, a quantity of soap stock will adhere to the inner bowl surface or accumulate in the discharge ports and then suddenly be released. The balance of the columns of lighter and heavier eilluents is thus'disturbed and an oscillation or surging takes place. This results in quantities of soap stock being intermittently delivered with the lighter eiliuent or oil and quantities of oil being delivered with the soap stock. I have further found that by heat-- ing substantially the entire outer surface of the bowl, this tendency of the soap stock to intermittently adhere and release is entirely overcome and uniform movement of the soap stock accomplished. It is, therefore, another object of my invention to provide a process and appa ratus in which sumcient heat is applied to the outer surface of the bowl to cause uniform move- 65 meat of the soap stock along the surfaces in contact therewith.

The heat is preferably applied to the bowl by a heated gaseous medium in contact with substantially the entire outer surface thereof. An enclosed chamber, entirely surrounding the bowl with suitable inlet and outlet for steam or other heated gaseous medium such that the heating medium is in direct contact therewith, has been found to be extremely emcient. Also, a heating coil positioned within a closed chamber surrounding the bowl has been found satisfactory. The intense agitation of the air or gaseous medium in the chamber by the revolving bowl causes rapid and repeated contact of the gaseous particles with both the heating coil and the bowl so that heat is rapidly delivered from the coil to the bowl by the heated gaseous medium in the chamber. By providing a closed heating chamber around the bowl, direct contact of the gaseous heating medium with the material discharged from the centrifugal and therefore contamination of this material is prevented. A further object of my invention is, therefore, to provide a process and apparatus in which contact with the material discharged from the centrifugal by a medium used to heat the external walls of the bowl is prevented.

The employment of steam in direct contact with the bowl of a centrifugal was found to present a difficult problem in that the steam and condensate therefrom entered the centrifugal bearings and interfered with lubrication thereof. This problem was overcome in the apparatus of the presentinvention and, therefore, a still further object of the invention is to provide a centrifugal apparatus in which steam may be employed to heat substantially the entire outer sur face of the bowl by direct contact therewith, without interfering with proper lubrication of the centrifuge.

The process of the present invention may be very effectively carried out in the type of centrifugal machine illustrated in the accompanying drawing which is a vertical section, partly broken away, through such a machine.

In the drawing, reference character i indicates a frame or housing surrounding the main portion of a centrifugal machine. The housing is provided with a drain outlet 2 at the bottom thereof and is also provided with an internal ledge or support 3 near the bottom upon which the revolving centrifugal machine is supported. The upper end 4 of the housing I is closed except for a central opening that is provided with a gasket.

A pan 5 having an outlet 6 for light constituents is provided at the top and a pan 1 having an outlet 8 is provided below the pan 5 for heavy constituents. Links 9 pivoted on lugs I! on the lower side of the pan I are provided for holding this pan to lugs II on the housing I.

A vertically arranged centrifugal bowl I4 is provided with a conically-shaped cover I! that is screwed onto the bowl II. A circularly-shaped member I is provided inside the bowl it near the upper end thereof and is of smaller diameter than the inside diameter of the bowl ll, so that an annular space I1 is left around the periphery of the member I. The upper side of the member I is made conical and is spaced from the cover I of the bowl. A central opening is provided through the member I and is larger than the inlet or central pipe I! for the bowl H. The member i6 carries a pipe I! of slightly larger diameter than the inlet pipe II to leave a passage ll between the two. The upper end of the pipe it extends into the upper pan I. A pipe II of a larger diameter than the pipe II is concentric with the pipe is and is supported by the cover ll leaving an annular space between the pipes I! and II. An outwardly and downwardly extending lip 2| is provided at the upper end of the pipe I! which terminates in the lower pan 1.

A spring-pressed bearing 28 surounds the pipe Ill. This bearing 23 is mounted in a support 24 that is bolted to the lower side of the pan I.

A feed pipe 25 for a mixture of materials that are to be separated from each other extends through a larger pipe 26 which is attached to the upper portion of the pan 5 and extends a considerable distance downwardly into the pipe I. The pipe ll of the bowl It extends downwardly to a lower member 28 into which it is screwed. The member 28 rests upon the bottom of the bowl I4 and has radial passages 20 communicating with the space 21 inside of the bowl. The member II has two stepped circular projections carrying two concentric cylinders SI and SI which extend to the lower side of the member ll. Openings '2 are provided through the walls of cylinder 8| near the lower end thereof, and openings 33 are provided through the cylinder 8! near the upper end thereof.

The bottom 35 of the bowl I4 is attached by bolts 36 to the flanged top 31 of the driving shaft 38. An annular depending flange I! is provided on the top 11. This flange 89 extends into a groove I in a stationary bearing member ll which is bolted to the support 42. The support 42 has a flange ll resting upon and bolted to the ledge or support I of the frame I with the gasket 44 to make an air-tight joint. Upper and lower ball-bearings 45 are provided for the shaft 38. An oil pipe 46 is provided for conducting oil to the upper bearing 48 and a drain pipe 41 is provided for draining oil from the lower bearing 45. The drive shaft 39 is provided with a pulley 49 at its lower end.

An inlet 50 for live steam is provided through the housing I and one or more outlets ll for condensates are provided above the flange or support 3. These outlets 5| may be provided with valves (not shown) if desired. Also, heating coil 52 having an inlet 53 and an outlet 54 may be located in the space surrounding the bowl II.

It will be noted that the support 42 for the lower bearing extends above the ledge 3 forming the bottom of the steam chamber and that a considerable amount of condensate can accumulate in the lower portion of the chamber without entering the lower bearing. Also, the flange ll constitutes an umbrella-shield, revolving at the same speed as the bowl, and because of its sloped upper surface and the fact that it overhangs the aperture leading to the lower bearing, centrifugal force prevents steam from flnding its way into the lower bearing and washing out the lubricant. A gasket or packing II is provided between the rotating pipe 20 forming part of the bowl and the upper portion 4 of the housing to prevent steam or other heating medium from reaching the upper bearing 21. It has been found that considerable back pressure may be built up in the heating chamber surrounding the bowl by partially closing the outlets ii therefrom, without interfering with the lubrication of the upper and lower bearings.

It will further be noted that the closed heating chamber prevents any contact by the heating medium with the materials being centrifuged at any time during the entrance, separating, or discharge thereof. However. in some cases it mayv be desirable to heat the upper portion of the discharge pipe II and discharge the small amount of heating medium thus used into the lower pan. For this purpose, a space It may be left between the upper side of the upper portion of the pipe 20 and the inner side of the neck It of the pan I. A circular perforated steam pipe 51 may be located in the lower portion of the space 85 and a connection (not shown) may supply steam to the pipe ll. In any case, however. the heating medium employed for heating the bowl is prevented from contacting with the discharged material.

In operating the machine for separating soap stock from a mixture of refined oil and soap stock, the mixture is introduced through the feed pipe II and passes through the outlets 29 into the lower portion of the bowl II. The heavy soap stock separates and slips upwardly along the inside of the wall of the bowl I 4 through the passage Bl between the cover It and member It and through the annular space It and over the lip 2| into the pan 1, and thence out through the outlet 0, while the lighter refined oil passes through the openings a into the space ll, thence downwardly and through the openings 32 into the space ll and upwardly through the space I! into the pan I and out through the outlet 8.

Steam is admitted through the pipe ll into the closed chamber surrounding the bowl it such that it contactssubstantially the entire outer surface of the bowl and imparts its heat thereto. Ines of heat from the substances within the bowl is prevented and, as stated above. in giyceride oil refining processes. the temperature of the steam is maintained sufficiently high to raise the temperature of the soap stock within the bowl and cause it to slip with uniform movement up the bowl walls. 'ihe condensate from the steam leaves the enclosing chamber around the bowl through the outlets ll.

Instead of admitting steam into the space surrounding the bowl by means of the pipe I, steam or other heating medium, may'bepassed through the heating coil 52 to produce an equivalent effect. The rapid rotation of the centrifugal bowl produces an intense agitation of the air or other gaseous medium in the space between the bowl and the surrounding walls of the frame I. The particles of air rapidly contact the surface of the heating coil and the entire outside surface of the bowl to provide an extremely efficient heat transfer from the heating coils to the centrifugal bowl. In this case the air or other gaseous medium which transfers the heat from the coils to the bowl surfacesis, in fact. a gaseous heating medium in direct contact with the bowl. 1

It has been found that when. in accordance with prior practice, cottonseed oil, for example. was treated with a caustic soda solution and the treated oil was introduced into a centrifugal machine having a bowl of about 4% inches diameter and running at about 10,000 R. P. 11.. the machine choked up in a short while. Although the mixture was introduced at a temperature of 130 R, it was found that the refrigerating effect of the machine revolving at high speed cooled the heavy eiiiuent to a temperature of about 120' 1., at which temperature the soap stock would not pass out of the heavy eiliuent outlet.

On the other hand. when the same type of treated cottonseed oil was introduced into the machine described above. veryrspid and thoroughseparationof thesoapstockandtherefined all took place after steam was introduced the pipe It and heated the outside of the bowl ll. The machine was operated continuously for periods exceeding 24 hours and at the ends of such periods. the machine was still clean and operating without lowered efllciency. The temperature of the live steam should be varied in accordance with the type of mixtures that are being separated so that the proper temperature can be ascertained by trial, and increased temperatures can be obtained when desired by passing hot fluids through the coil 52. The outside, as well as the top and bottom of the bowl I, is heated so that the soap stock is heated and will slip or fiow and the heat does not reach the lighter constituents or refined oil. The greatest flow or slip of the soap stock appears to be at the contact between the inside surface of the bowl and the soap stock column so that the soap stock or heavy ellluent is a self-cleaning agent along the inside of the wall of the bowl. Thus clogging or stopping of the flow of the column of heavy efiluent is prevented, with the result that the shifting of the neutral or separating zone over into the light eiliuent column or refined oil column does not take place to cause appreciable amounts, of the soap stock to be carried out in the refined oil.

. It is necessary not only that actual clogging or complete stoppage of the outlet from the bowl be prevented, but the soap stock must be discharged in a steady or uniform manner. If the column of heavy eilluent stops or clogs its discharge port, the resistance to fiow is increased. and the pressure tending to move the columnv increases. While the column is stopped, .both eiiiuents will fail to separate or will remix and be discharged through the one flowing column. the light eiiluent column. The pressure increase may be sumcient to suddenly start the column of heavy eilluent and cause both eflluents to surge into the heavy eilluent column and back into the light eiiiuent column. Thus any intermittent sticking or irregular movement of the soap stock sets up an oscillation or surging of the two balanced columns of effluent. This results in quantities of the separated -oil being'discharged with, the soap stock or quantities of soap stock being discharged with the oil. It is only by heating the entire surface of the bowl in contact with the soap stock, that a uniform slipping of the soap stock over these surfaces and out of the discharge ports can be obtained so that a steady discharge of each effluent, without contamination by the other eilluent, is accomplished.

An improved feature of this invention is that the heating of the outside of the centrifugal bowl not only overcomes the refrigerating eflect of the revolving bowl, but it also causes the column of heavy effluent or soap stock to fiow at a rate that is correctly proportioned to the flow of the less viscous or refined oil efiiuent. At the same time, the heat changes the character of the heavy eilluent so that it can act as a scrubbing agent to prevent solid particles from collecting and forming a layer on the inside surface of the bowl. Thus the danger of separated dirt getting into therefined oil, and the danger of the opening I through which the heavy eiiiuent escapes being closed up, are avoided. Keepingthe inside of the bowl'free from accumulating layers of dirt also avoids the danger of the centrifugal force being reduced by the reduced diameter of the bowl that would occur if such layers were to accumulate on the inside wall thereof.

actual practice of this inventicm has conclusively demonstrated that with a mixture of cottonseed oil treated with a caustic soda solution and entering the machine at a temperature of 130' PL, the heat can be regulated by the steam entering the pipes 50 and I in the space around the centrifugal machine having a bowl 4% inches diameter and running at about 10,000 R. P. 11., sothatthedischarged soapstockhasatemperature of 160 F., and the refined oil has a temperature of 128 F., and that, under such conditions, the machine can be run for an indefinite length of time without clogging up. By noting the temperature of the efliuent soap stock, the user is guided as to the amount of heat that he should apply to the outside of the bowl II.

In instances where the heavy eiiiuent tends to become too viscous in the outlet 20, and it is not objectionable to contact the heavy eflluent with heating medium, steam or other heating medium can be applied through the pipe "I.

Thus the apparatus above disclosed is particularly adapted for overcoming the refrigerating efiect of the centrifugal bowl upon materials delivered to the centrifugal above atmospheric temperatures and if necessary for supplying additional heat to the portion of the heavy eiliuent in contact with the bowl walls to raise its temperature. The apparatus also finds utility in low temperature processes of refining glyceride oils in which suitable proportions of an unrefined glyceride oil and an alkali solution are intimately mixed at temperatures Just high enough to permit the oil to satisfactorily flow, which temperatures are normally below R, and then delivered after a short interval of time, usually not over 8 minutes, to a heated centrifugal in which the temperature is high enough to agglomerate the foots, break arm hydrosol present, and centrifugally separate the soap stock from the oil. This latter process constitutes the subject matter of my copendlng application Serial No. 2,648 of which my copending application Serial No. 30,573, filed July 9, 1935, is a continuation in part. The amount and temperature of the heating medium supplied to the coil 52 or directly into the chamber surounding the bowl can be controlled to heat to the necessary temperature, the materials passing through the bowl.

Although the process, as described, has particular utility in the art of separating soap stock from refined gylceride oil or substances having similar problems of separation, such as certain types of glue, yet it is appreciated that the apparatus may be desirably employed in connection with the separation of numerous other heavy and light constituents of fluid mixtures.

This application constitutes a continuation in part of my application, Serial No. 678,574, filed July 1. 1933.

Having thus described my invention, I claim:

1. The method of continuously centrifugally separating soap stock from alkali treated glyceride oils, which comprises separating the soap stock from said oil by centrifugal force in a rotating centrifugal bowl, and discharging the oil and soap stock separately therefrom. applying heat to the material undergoing separation in an amount sumcient to maintain the temperature of the soap stock being discharged from the centrifugal from F. to at least as high as R, while preventing a substantial increase in the temperature of the 011 during separation.

2. The method of continuously centrifugally separating soa pstock from alkali treated glyceride oils, which comprises introducing the oils containing soap stock into the separating sons of a rotating centrifugal bowl, while said oils and soap stock are in a heated condition. sew rately discharging the oil and soap stock from said bowl, applying additional heat through the wall of the bowl to the material undergoing separation in an amount sufficient to raise the temperature of the soap stock being discharged above the temperature of the materials being introduced and sufficient to increase said temperature of said soap stock substantially above 120 F. while preventing a corresponding increase in temperature of the separated oil.

3. The method of continuously centrifugally separating soap stock from alkali treated glyceride oils. which comprises separating the soap stock from said oil by centrifugal force in a rotating centrifugal bowl, and discharging the oil and soap stock separately therefrom, applying heat to the outer surface of the soap stock in a sufficient amount to maintain the temperature of the soap stock being discharged from the centrifugal above 120 F. while preventing a corresponding increase in temperature of the separated oil.

4. The method of continuously oentrifugally separating soap stock from alkali treated glyceride oils, which comprises separating the soap stock from said oil by centrifugal force in a rotating centrifugal bowl, and discharging the oil and soap stock separately therefrom, applying heat to the outer surface of the soap stock in an amount sufficient to increase the temperature of the soap stock being discharged and sufficient to maintain the temperature thereof substantially above 120 F., while preventing a corresponding increase in temperature of the separated oil.

5. The method of continuously centrifugally separating soap stock from alkali treated glyceride oils, which comprises separating the soap stock from said oil by centrifugal force in a rotating centrifugal bowl, and discharging the oil and soap stock separately therefrom, applying sufficient heat externally of the centrifugal bowl to maintain the temperature of the soap stock being discharged from the centrifugal above 120 F. while preventing a corresponding increase in temperature of the separated oil.

6. The method of continuously centrifugally separating soap stock from alkali treated glyceride oils, which comprises separating the soap stock from said oil by centrifugal force in a rotating centrifugal bowl, and discharging the oil and soap stock separately therefrom, applying steam to the outer surface of the bowl in sufficient amount to maintain the temperature of the soap stock being discharged from the bowl above 120 1",, while preventing a corresponding increase in temperature of the separated oil.

7. The method of continuously centrifugally separating soap stock from alkali treated glyceride oils, which comprises separating the soap stock from said oil by centrifugal force in a rotating centrifugal bowl, and discharging the oil and soap stock separately therefrom, applying heat to the soap stock in the bowl through the wall of the bowl in an amount sufiicient to maintain the temperature of the soap stock, as it is being discharged, to not substantially below 120 1'. while preventing a correspondingly high temperature being imparted to the separated oil eilluent.

8. In the art of refining glyceride type oils which comprises the steps of mixing an alkaline magentwiththecrudeslycerideoilstosecure nmtralimticn of the free fatty acids contained intheoiLcontinumislypassingthemixtui-etoa oentrifugaland separating thesoapstockthenfrom by centrifugal force, discharging theoil and soap separately therefrom. app yins heat to the soapstockinthebowlofthecentrimgai through the wall thereof in an amount suilicient to maintainthe tcmlleratureofthesoapstockbeingdischarged from the bowl above 120' I". and millcient to raise the temperature of the soap stock above the temperature at which the mixture is introduced into the bowl. while preventing a corresponding increase in the temperature of the separated refined eiiiuent as it passes through said centrifugal.

9. A continuous process of refining glyceride type oils, which comprises mixing an alkaline reagent with said oil to eifect neutralization of the free fatty acids contained in the oil. maintaining the oil heated during the neutraiimtion step. passing the mixture, in a heated condition, to a rotating centrifugal. separating the soap stock iromsaid oil by the centrifugal force of the rotating bowl, separately discharging the oil and soap stock therefrom, applying heat to the soap stock efluent through the wall of the bowl as it passes through the centrifugal in an amount sufiicient to raise the temperature of the soap stock as it is being discharged above 120 1''. and suiiicient to minimize sticking of the components of the soap stock to the wall of the bowl andbuilding up a layer thereon. while preventing a corresponding increaaeinthetemperatm-eoftheseparatedrefined eliumt as it passes through saidoentrifugai.

10. A continuous process of refining glyceride type oil which mprises mixing an alkaline reagentwithsaidoiltoeflectneutralizationofthe free fatty acids contained in the oil. maintaining the oil heated during the neutralization of the free fatty acids. continuously passing the mixture, while in a heated condition. to the separating none oi a rotating centrifugal bowl. sharply -wlyina additional heat to the mixture through the wall of the bowl, in an amount sumcient to maintain the temperature of the separated soap stock to substantially above 120 I"., as it is discharged, while preventing a co increase in temperature of the refined oil eiliuent, and discharging the separated oil and soap stock from the bowl.

ii. The method of continuously centrifugally separating soap stock containing sticky components from glyceride oils which'comprises: separating the soap stock containing sticky components from said oil by centrifugal force in a rotating centrifugal bowl, and discharging the oil and soap stock containing sticky components separately therefrom, applying heat to the soap stock containing sticky components in the bowl through the wall of the bowl in an amount sumcient to maintain the temperature of the soap stock containing sticky components, as they-are being discharged. to not substantially below 120 I"., while preventing a correspondingly high temperature being imparted to the separated oil eiiiuent.

BENJAMIN CLAYTON.

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