US2301109A

US2301109A - Process of refining oil

Info

Publication number: US2301109A
Application number: US369510A
Authority: US
Inventors: Clayton Benjamin
Original assignee: REFINING Inc
Current assignee: REFINING Inc
Priority date: 1940-12-10
Filing date: 1940-12-10
Publication date: 1942-11-03
Anticipated expiration: 1959-11-03

Description

Nov. 3, 1942. B. CLAYTON 2,301,109

PROCESS OF REFINING OIL Filed Dec. lO, 1940 O/L HND SOAP-IN l i WHTEE /N l l A INVENTOR. Bezyamin Clayton BY n@ ,idd tf/74.4...-

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the oil is ordinarily Patented Nov. 3, l194712 PROCESS F REFINING OIL Benjamin- (nayton, Houston, Tex., assignor to Reilnin Nevada g, Inc., Reno, Nev., a corporation of Application December 10, 1940, Serial No. 369,510

12 Claims.

This invention relates to a process of refining animal and vegetable oils, and more particularly to a process of removing residual impurities from such oil after it has been treated with alkali and the resultant soapstock separated from the oil.

In the processes of refining animal and vegetable oils by alkali treatment, the oil, after the resultant soapstock has been separated therefrom either by a settling or a centrifugal separation step, contains small amounts of residual alkali, soap and water. Even in oil separated from soapstock by means of a very eiiicient centrifugal separation such as that effected by means of a centrifuge having a large diameter bowl and inclined discsbetween which the light effluent ls adapted to ow to render the separation more eiiective, it has been found that the oil thus separated may contain soap in the proportion of from 300 to 1500 parts per million. It is the practice now to wash this oil in separate equipment by the use of to 20% of water and if the soap particles left in the oil after separating the soapstock are very diiiicult to remove, even a second washing operation may be employed. Present commercial practice favors a refined oil in which the soapstock has been reduced to from 10-12 parts per million. Following the washing step subjected to a vacuum drying step to remove the last traces of water.

It has been found that relatively small quantities of water are ample to remove large quantities of soap if the water can be brought into sumciently intimate contact with the oil in order for the water to reach a soap concentration which is in equilibrium with the concentration of soap remaining in the oil. It will be seen that if such a small quantity of water as 1% is added to an oil containing 1,000 parts per million of soap, there would be approximately ten times as much water as the soap in the oil. If all the soap were extracted in a single step the resulting soap solution would only have a soap concentration of about 10%. Therefore, by eiiecting intimate con- Vtact between the oil and the water it is possible `to remove substantial quantities of the soap by means of a relatively small quantity of water.

The present invention. contemplates the intro- Cil duction of a small amount of wash water into the centrifugal bowl which is used for separating the oil from the soapstock or into the centrifuge which is being used for the rst washing operation. -In either event the water is brought into contact with the oil just after the oil has been separated from either the soapstock or the wash water is introduced inside the neutral zone. 'I'he wash water thus extracts a considerable quantity of soap from thefseparatedkoil and then flows outwardly in the centrifugal bowl to join the heavy eilluent composed of either soapstock or Wash water. In this manner the centrifugal separation and one washing step can be accomplished in a single centrifuge, or two washing steps may be conducted simultaneously within a single centrifuge.

It is the principal object oi the present invention to provide a method of washing refined oil in which small quantities of la washing liquid the oil in a centrifuge just after the oil has been separated from a' washing liquid.

Another object of the present invention is to provide a centrifuge which permits the introduction of a heavy washing liquid into a light eiiiuent after the light eiiluent has been separated from the heavyeiiiuent.

Other objects and advantages of the invention will appear in the following description 0I the process and apparatus shown in thel drawing, in which Fig. 1 represents a vertical section through a centrifugal bowl which may be used to carry out the present invention.

zrepresents a fragmentary vertical section of a modiiied centrifugal bowl: and

Fig. 3 represents a fragmentaryplan section of the wash water inlet pipe. y

'I'he centrifuge in Fig. l is composed of a bowl Il mounted on a shaft I2 and secured thereto'by means of nut I3. The bottom of the bowl has an upwardly extending cylindrical portion through which the shaft I2 passes. A sleeve 4II having perforations IS therein is disposed around the cylindrical portion Il. 'I'he bottom of this sleeve rests upon the bottom of thebowl and the top of the sleeve is adapted to support a dished member I1 having an upstanding cylindrical portion Il surrounding the sleeve II. An

water4A` as the case may be. That ia'the wash 55 general contour of the bottom of the bowl and is supported in spaced relation thereto by means of inwardly extending flange 20. Thus, there is a passageway extending from the inside of the cylindrical member I5, through the perforations I6, between the cylindrical members I5 and I8 and between the dished member I1 in the bottom of the bowl. Spaced near the periphery of the dished member I1 are pipes 2l which extend upwardly from the dished member and are fastened thereto to provide a flow communication with the space between the bottom of the bowl and the dished member. This pipe 2| is provided with suitable perforations 22 through which the wash water may be discharged into the main portion of the bowl. The pipe 2I is preferably closed at the end so that the wash water will have to pass through holes 22 rather than directly out the end of the pipe. These pipes are preferably disposed inside the neutral zone of the bowl, that is, in'

side the interface between the heavy and light effluents.

Surrounding the cylindrical portion I8 of the dished member is a tubular member 23 which is flared out near the bottom of the bowl to provide a passageway between the dished member and the tubular member. The bottom of the tubular member 23 is disposed above the dished member to provide a passage 23' beneath the tubular member. This is accomplished by supporting the tubular member by means of ribs 24 which. rest upon the flange I9 of the dished member. The tubular member is provided with a plurality of outwardly extending ns 25 which in turn are provided with shoulders 26. A plurality of discs 21 are adapted to be slid over the tubular member and are provided with slots adapted to engage the shoulders 26 of the ribs 25, so that the discs will rotate with the tubular member. These discs may be of the conventional type employed in this type of centrifuge, in which case they would be provided with perforations 28. By suitably constructing the dished member I1 and the water pipe 2| the perforations in the disc may pass over and surround the water pipes. In this case it is preferred to have the perforations 28 of sufcient size so that after the discs are disposed over the water pipe there will still be sufcient room between the outside of the pipe and the adjacent disc to allow the passage of heavy efy fluent along the outside of the water pipe. In this manner the advantages obtained by means of the perforated discs are not lost by the use of these perforations to provide a space for the water pipe. Where the perforations in the disc are not necessary for efficient separation it is apparent that the water pipe may be of sufficient size to occupy the entire space made by the perforations. The discs 21 are provided with the usual means of spacing so that the discs will be supported in spaced relation with each other. Above the last discs is disposed dam member 29 which has a downwardly extending flange 30 which is disposed to permit only heavy effluent to pass beyond it. At its upper end the dam member 29 has an upwardly extending flange 3| -to which is attached the light eiiiuent discharge tube 32. This ltube has inwardly extending ribs 33 which engage the annular rib 34 of the tubular member 23 to hold the tube 32 in spaced relation with .the tubular member 23, thus providing a passage for the light effluent. The discs and the dam member 29 are held together by means of the spider member 35 which in turn is held in position by the closure member 36. The lock ring 31 serves to hold the entire assembly together. A ring dam 38 supported by a shoulder on the inner surface of the closure 36 is held in position by the nut 39. This ring dam serves to determine the neutral zone in the centrifuge and may be replaced by another of different size when it is desired to shift the neutral zone.

The feed mechanism is composed of a central feed tube 40 supported by cover 4I. The feed tube is provided with a spiral 42 which serves to feed the mixture to be centrifuged against the inside wall of the tubular member 23 and from there it may pass through the space between the tubular member 23 and the tube I8 and outV through passage 23. 'I'he wash water inlet 43 is disposed within the feed tube a'nd passes through the center of the feed spiral. It extends down a considerable distance into the centrifuge and passes through a hole in the flange I9. The cap 44 may be provided to cover the nut I3 on the end of the shaft I2.

In Fig. 2 I have illustrated a modification of the centrifuge in which the water pipe is disposed beyond the discs and inside the neutral zone. In this modification a support 45 between the inside of the bowl and the top of the water pipe may be provided since in this case the discs do not surround the water pipe and accordingly the water pipe cannot be supported by them.

Fig. 3 shows a modication of the present invention in which the perforations in the discs are of an elongated shape. The short dimension of the elongated perforation is disposed along a radius. The water pipe is brought in contact with the sides of the elongated perforation and in this manner the discs serve to support the water pipe. The space provided by the elongated perforation permits the passage of the heavy eiiluent alongside of the water pipe.

In operation the oil containing the soapstock to be separated therefrom is conducted into the feed pipe 40, is forced to the periphery of the feed pipe by` means of the spiral 42 at the end of which it is discharged against the inner wall of the tubular member 23 and flows downwardly through the space between this tubular member and the tube I8 and is distributed toward the periphery of the centrifuge bowl by means of the outwardly flared portion of the tube 23. The soapstock is thrown against the inside of the bowl while the oil is forced inwardly to pass between the discs 21. The wash water is introduced through the pipe 43, passes through the perforations I6, the space between the tubes I5 and Il and into the water pipe 2l from which it is distributed through the holes 22. This waterflows countercurrent to the inward flow of the oil and effects intimate contact with the oil, thus removing a substantial portion of the soapstock and other impurities from` the oil. Some of the wash water containing the soapstock and the impurities may discharge through the perforations 28 and the discs and thus take a short path to the heavy eilluent discharge. Other portions of the wash water pass outwardly between the discs and join the main portion of the soapstock which is withdrawn at the heavy effluent discharge. T he oil after passing the stream 0f wash water iiows inwardly along the surface of the discs and is discharged into the space between the ribs 25 and from there it flows upwardly through the space between the

tubes

32 and 23 and is discharged through the light effluent discharge.

The heavy effluent along the inner wall of the bowl passes around the flange 30 of dam member 29, up through the space 'between

members

29 and 36, over the ring dam 3l and out the heavy efiluent discharge.

It will be apparent that by means of the present process a single centrifuge may be used to effect the primary separation of impurities from the oil as well as to effect a substantial washing of the separated oil.

The washing accomplished by this small amount of water either makes a separate washing unnecessary or, in the case of oil from the primary separation containing an excessive amount of light floating soap, only one separate operation may be required.`

The present process may also be employedto effect a double washing within a single centrifuge. v

Thus, a refined oil from which the majority of the soapstock has been separated but which contains from 300 to 1500 parts per million of soap can be admixed with a considerable quantity of water, which mixture can be separated in the present centrifuge. This washing will remove up to 95% of the residual soapstock and by the use of additional wash water discharged into the separated washed oil it is possible to reduce the` than 1% may be found satisfactory in particular instances.

In the treament of certain oils it may be desirable to heat the material in the centrifuge. Thisv may be done in the manner disclosed in my Patent No. 2,100,277. Likewise, heat may be added by the use of hot water, even above its atmospheric boiling point if pressure is employed.

The present process is not limited to the removal of residual soapstock from a refined oil but may also be employed to wash any impurities from the oil after it has been subjected to any kind of refining treatment. For example, where the oil is subjected to a degumming treatment the present process may be employed to remove traces of gums and other impurities which have precipitated but which have remained with the oil and have not been separatedin-the primary separation. Likewise, it can be employed to remove residual traces of impurities as well as acid from an oil which has been subjected to acid refining.

Similarly, the present process while preferably employed in conjunction with the continuous reiining of oil, such as according to U. S. Patent No. 2,100,274, is not limited to continuous rening but may also be employed to remove residual impurities from oil refined according to the batch process.

The various modifications of the process of the present invention are applicable to vegetable and animal oils in general. Such vegetable oils as cottonseed oil, com oil, soya bean oil, linseed oil, sesame oil, etc. are within the contemplation of the invention. The term "animal oils is also intended to include fish oils, such as sardine, menhaden, or herring oils. By the employment of the terms oils or oil in the claims I intend to embrace glyceride fats or oils, irrespective of the viscosity thereof.

l While the description of the present invention has been particularly directed to the-use of the type of centrifuge illustrated, it will be apparent 75 that other types of centrifuge may be modified to perform the present invention.

It is apparent that other washing iiquids besides water may be used if desired. For example, various electrolytes may be employed particularly where the process is employed for the removal of gums and phosphatides. Likewise, in certain instances, soap solvents such as alcohols which are immiscible with the oil may be employed, either alone or in arlmixture` with other liquids such as water. Y

While various modifications have been disclosed` the invention is not to be limited thereto but it is to be understood that it may be varied within the scope of the appended claims.

What I claim is:

l. The process of separatingy impurities from glyceride oil which comprises subjecting said oil containing impurities to centrifugal separation in a centrifuge to remove a' portion of the impurities therefrom, washing the resultant separated oil by introducing a relatively small quantity of washing'liquid into said separated oil within said centrifuge immediately following separation.

2. 'I'he process'of separating impurities from glyceride oil which comprises subjecting said oil containing impurities to centrifugal separation ina centrifuge to remove a portion of the impurities therefrom, and washing the resultant separated oil by introducing a relatively small quantity of washing liquid into the separated oil inside the neutral zone of said centrifuge while said separation is being affected therein.

3.k The process of separating impurities from glyceride oil which comprises subjecting said oil containing impurities to centrifugal separation in a centrifuge to remove a portion of the impurities therefrom, introducing a relatively small quantity of. a washing liquid into the resultant separated oil while said oil is still within said centrifuge, and removing the washing liquid along with the previously separated impurities.

- 4. The process of separating soapstock from glyceride oil which comprises subjecting said oil containing soapstock to centrifugal separation in a centrifuge to remove a portion of the soapstock therefrom, introducing into the resultant separated oil while in said centrifuge a relatively small quantity of a washing liquid, and separating the washing liquid from the oil.

5. The process of separating soapstock from glyceride oil which comprises subjecting said oil containing soapstock to centrifugal separation in a centrifuge to remove a portion of the soapstock therefrom, introducing into the resultantseparated oil while in said centrifuge a relatively small quantity of water, and separating water from the oil.

6. The process of separating impurities from glyceride oil which comprises subjecting said oil containing impurities to centrifugal separation to remove a portion of the impurities therefrom, admixing the resultant separated oil with a quantity of washing liquid and subjecting the mixture to centrifugal separation, introducing into the resultant washed oil while in the centrifuge used for said last mentioned separation and immediately following separation from the washing liquid a relatively small quantity of washing liquid, and separating the washing liquId from the oil.

'1. The process of separating 50895150011 from glyceride oil which comprises separating the maior portion of the soaDStOCk from the ou ad mixing une separated ou with a quantity of Washing liquid, subjecting the mixture to centrifugal separation in a centrifuge to remove a portion of the washing liquid and residual soapstock therefrom, introducing into the resultant separated oil while in said centrifuge a relatively small quantity of washing liquid, and separating the washing liquid from the oil.

8. The method of refining glyceride oil which comprises treating the oil with an alkaline refining agent, separating the major portion of the resultant soapstock therefrom, admixing the resultant separated oil with a quantity of washing liquid, subjecting the mixture to centrifugal sepa-- ration in a centrifuge, and introducing into the separated oil while in said centrifuge a relatively small quantity of washing liquid to remove residual impurities from the oil.

9. The process of separating soapstock from glyceride oil which comprises subjecting a mixture of oil and washing liquid to centrifugal separation in a centrifuge to remove a portion of the residual soapstock therefrom, introducing into the resultant separated oil while in said centrifuge a relatively small quantity of washing liquid, and removing the washing liquid from the oil.

10. The process of separating impurities from glyceride oil which comprises subjecting said oil containing impurities to centrifugal separation in a centrifuge to remove a portion of the impurities therefrom, introducing a relatively small quantity of a washing liquid into the resultant separated oil within said centrifuge, removing the washing liquid along with the previously separated impurities and heating the bowl of the centrifuge during said separation to a relatively high temperature so as to lower the viscosity of the oil.

11. 'Ihe process of separating impurities from a glyceride oil which comprises introducing an cil containing impurities into a centrifuge, forming a layer of impurities and a layer of separated oil, said layers being separated by a neutral zone,in troducing into said separated oil layer a small quantity of a washing liquid, forcing said washing liquid through at least a portion of said separated oil, through said neutral zone and into said layer of impurities, and separately removing impurities and oil from said centrifuge.

12. The process of separating impurities from a glyceride oil, which comprises, subjecting said oil containing said impurities to centrifugal force in a centrifuge to separate said 'impurities from said oil, introducing a washing liquid into said oil while the same is still passing through said centrifuge and after a portion of said impurities has been separated from said oil, and separating washing liquid from said oil in said centrifuge to remove additional impurities therefrom.

BENJAMIN CLAYTON.