US2215624A - Process of removing impurities from vegetable oils - Google Patents

Description

Sept. 24, 1940. G. J. STREZYNSKI 2,215,624

PROCESS OF REMOVT NG IMPURITI'ES FROM VEGETABLE OILS Filed July 16, 1937 COOK 5:?

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Patented Sept. 24, 1940 (PATENT OFFICE} rnoonss F REMOVING IMPURITIES FROM w VEGETABLE ons- George J L vStrezynski, Poughke'epsie, N. Y., assignor to The De Laval Separator Company, New York, N. Y.,' a corporation of New Jersey Application my, 16, 1937, Serial No. 153,901

B'Claims. (01. 260 -428) My invention is an improved process-for purifying vegetable oils, such as cottonseed oil, which, as they come from the press, contain considerable meal, someof which is coarse and settles out 5' quickly while a smaller quantityof finer meal settles very slowly. Such fine meal is not heavy enough to enable its separation to be centrifugally effected, nor would it be fluid enough if its separation could be effected to flow outof the bowl.

If, however, water is added to the oil, it will be absorbed by the meal and gravity or centrifugal subsidence is possible. But gravity settlement is impracticable, because the water soon enters into,

chemical combination with the meal, developing acids which are deleterious to the oil. I have found, however, that if, after addition to, for example, cottonseed oil, of a small quantity of water, immediately or within a very short time, and before the objectionable reaction has proceeded to a substantial extent, the oil be subjected to centrifugal separation, separation can be satisfactorily effected. The separated oil is brilliantly clear, though it has a small quantity (probably between .1% and 5%) of water in solution.

On standing for 12 or more hours this water precipitates compounds which (although not acid) act as emulsifying agents and cause a high refining loss. However, these compounds, with the watery meal, settle to the bottom and by drawing off about 10% of the oil and recentrifuging it, the watery meal, with such compounds, can be removed. This oil to be reoentrifuged can be mixed with the fresh oil and with it fed to the centrifuge.

The watery meal discharged from the machine contains considerable oil, but by pumping it back and mixing it with the fresh meal going to the cooker this oil is recovered at the presses. The water added may vary from five to ten per cent. Somewhat more than enough water to be taken up in combination with the impurities should be added, but the addition of considerably more than that amount is inadvisable. An addition of about 6% is preferred.

Though the separation of meal from the oil can be accomplished in any separator that will continuously discharge solids from one outlet and liquids from another, I prefer to use a separator 50 of the construction set forth in a patent issued to me December 3, 1935, No. 2,022,814, which has automatically operating valves controlling ports in the peripheral wall of the bowl.

In the accompanying drawing, which shows a 55 flow diagram of a plant using my process: a is a crusher for cottonseed, b a cooker for crushed seed, 6 a press for squeezing out the 011, d a storage tank with an outlet pipe having a valve 2. is a heater having an outlet, with a valve g, leading, through a strainer h, to a centrifugal separator i. a is a water tank having an outlet, with a valve It, also leading to the centrifuge.

. From the centrifuge one outlet 1 discharges into a tank m, from which a pump 11. discharges back to the cooker I), while the other outlet discharges l0 erally with the addition of a little water or steam, 2

at b. The meal is then put in blankets and placed under a hydraulic press c, where the oil is squeezed out and flows to a storage tank d, where it is held for about 24 hours. From the storage tank the oil, at a rate controlled by the valve e, 25 flows through the heater J, Where its temperature is raised to about 110 F. It then flows through a strainer it that removes very coarse particles. The oil, containing the remaining finer particles, flows toward the centrifugal separator 2'. On its 30 way thereto it is mixed with suflicient water (from tank a) to so saturate the meal as to make it enough heavier to be easily separated from the oil and to make it fluid enough to flow out of the bowl. In the separator the meal and water, 5 mixed together, are separated from the oil and discharged into the tank m, whence the pump n forces them back to the cooker. The nearly purified oil is discharged to the tank 0, whence the pump 12 forces it to one of the clean oil storage tanks q. After standing in these storage tanks for 12 hours or more the lower portion (from five to fifteen per cent. of the whole, preferably about 10% comprising oil containing watery meal and precipitated compounds, is slowly drawn off through a valve r to the heater 1, where it mixes with the stream of fresh oil and is recentrifuged. The remainder of the oil, free of impurities, isdrawn off through the valve s for shipment.

What I claim and desire to protect by Letters Patent is: a

1. The process of purifying vegetable oil containing fine solids, which comprises flowing such oil toward a locus of centrifugation, flowing water in much smaller rate toward the same locus and mixing it with the oil and substantially immediately, and before development of acids by reaction between the water and the solids, separating by centrifugal subsidence a major portion of the water and solids together with a minor fraction of the oil from a major portion of the oil containing a small percentage of water and solids, subjecting the last named centrifugally separated constituent to gravity settlement so prolonged as to separate said constituent into an upper stratum containing the bulk of the oil in a substantially completely purified condition and a lower stratum comprising an oil containing a small percentage of watery meal and precipitated compounds, separating the upper stratum of purified oil from said lower stratum of oil containing watery meal and precipitated compounds and subjecting the last named oil to centrifugal subsidence.

2. The process defined in claim 1 in which the duration of the gravity settlement is not less than twelve hours.

3. The process defined in claim 1 in which the percentage of water added is within the range of about 5 to 10%.

4. The process set forth in claim 1 in which a fresh stream of oil to be subjected to the first centrifugal subsidence operation specified and the last named oil containing a small percentage of watery meal and precipitated compounds are fed to a common locus and centrifuged together.

5. The process set forth in claim 1 in which the water containing most of the solids and some oil that is separated from the major portion of the oil in the centrifugal subsidence operation is mixed with fresh oil to be subjectedas specified to centrifugal subsidence.

6. The process of purifying vegetable oil containing fine solids, which comprises flowing such oil toward a locus of centrifugation, flowing water in much smaller rate toward the same locus and mixing it'with the oil and substantially immediately, and before development of acids by reaction between the water and the solids, separating by centrifugal subsidence a major portion of the water and solids together with a minor fraction of the oil from a major portion of the oil containing a small percentage of water and solids, subjecting the last named centrifugally separating constituent to gravity settlement so prolonged as to separate said constituent into an upper stratum containing the bulk of the oil in a substantially completely purified condition and a lower stratum comprising an oil containing a small percentage of watery meal and precipitated compounds, separating the upper stratum of purified oil from said lower stratum of oil containing watery meal and precipitated compounds, and 25 mixing with a stream of fresh oil flowing toward the locus of centrifugate the said oil containing a small percentage of watery meal and precipitated compounds that has been separated by prolonged gravity settlement and the said mixture of water, solids and a minor fraction of oil that has been separated by centrifugal subsidence.

GEORGE J. STREZYNSKI.

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