US2848468A - Method and apparatus for neutralizing fatty oils - Google Patents

Description

Aug. .19, 1958 J. WIJNBIIERG I I ,4

METHOD AND APPARATUS FOR NEUTRALIZING FATTY OILS Filed March 2a. 1955 '5 Sheets-Sheet 1 :B/IZ

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INVENTOR. Jan Yl/ijn berg Aug. 19, 1958 J. WlJNBERG 2,343,468

METHOD AND APPARATUS FOR NEUTRALIZING FATTY OILS Filed March 28, 1955 5 Sheets-Sheet 2 Fig.2

/N VE N TOP. Jan Z/l'jnberg Aug. 19, 1958 J. WIJNBERG METHOD AND APPARATUS FOR NEUTRAL-IZING FATTY OILS 3 Sheets-Sheet 5 Filed March 28, 1955 II I I I II IIV I Unite tales METHOD AND APPARATUS FOR NEUTRALIZING FATTY OHJS Jan Wijnberg, Wormerveer, Netherlands, assignor to Aktiebolaget Separator, Stockholm, Sweden, 21 .corporation of Sweden Application March 28, 1955, Serial No. 497,084

8 Claims. (Cl. 260-425) this chamber filled with oil during the feeding, the lye being led directly into and mixed with the oil mass rotating with and filling the chamber, feeding the resulting mixture into the separating chamber of the centrifugal bowl to divide it into oil and soap, and separately discharging the oil' and soap from the centrifuge.

The apparatus disclosed in the above-mentioned patent application consists of a centrifuge, including a centrifugal bowl rotatable on a vertical axis and having a separating chamber provided with separate outlets for oil and neutralization products, a hollow spindle extending from the bowl and forming a rotating feed chamber opening directly into theseparating chamber, a fixed reagent supply tube extending through the hollow spindle into the feed chamber, an oil supply tube fixed in surrounding relation to the first tube and forming therewith an oil passage, and means forming an hermetically sealed passage between the oil supply tube and the outer por- 7 tion of the bowl spindle.

The results stated in said patent application have been obtained on a pilot plant scale, but when treating fatty oils having a high percentage of free fatty acids on a factory scale, the results have not been quite satisfactory.

I have found that when treating oils having a high percentage of free fatty acids on a factory scale, substantially improved refining results (a better degree of neutralization) are obtained in the method referred to above by heating the oil and possibly the lye prior to the neutralization operation, passing the oil-lye mixture for a period of time of less than a second in turbulence-producing passages through the rotating chamber, and feeding the mixture immediately from this chamber to the separating chamber.

When refining fatty oils with alkali, it is desirable to obtain an absolutely neutral oil while keeping the saponification losses low. To this end, it is essential to effect an intense neutralization during a very short period of contact between the oil and the alkali so as to avoid undesired saponification of the oil. In order to obtain a complete neutralization, an excess of alkali must be used.

In the method disclosed in the above-mentioned patent application, lye at room temperature is mixed with the oil at a temperature of 85 C. and the period of contact between the oil and lye is about one second. In the improved method, however, it has been possible to make the neutralization reaction more intense and con- H sequently to shorten the period of contact between the oil and lye by pretreating the lye to the refining temperaateint O ment of the apparatus according to the invention.

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ture and causing increased turbulence of the reaction mixture during the passage through said rotating chamber. In this way, it has been possible to use a contact time of less than 0.5 second. Preferably, a contact time of 0.1 second or less, for example 0.05 second, is used. Furthermore, it has been found advantageous to preheat the oil as well as the lye to a temperature of at least C., preferably about to C. The strength of the lye may vary according to the acidity of the oil to be neutralized and may, for instance, be 35 N. This relatively high temperature increases the velocity of the neutralization reaction, counteracts formation of emulsion, and facilitates the separation due to reduced viscosity.

The invention also includes apparatus for carrying out the present method. This apparatus comprises a centrifuge as described above, which centrifuge is modified by providing turbulence-producing passages for the oil-reagent mixture in the feed chamber. According to the preferred embodiment, these passages are formed by providing discs in the feed chamber perpendicular to its axis of rotation and spaced at intervals along said axis, each of the discs forming openings displaced in relation to corresponding openings in adjacent discs, reckoned in the axial direction. The discs can advantageously be supported by a rod extending coaxially through the feed chamber from the inner end of the hollow spindle and fixed at this end, for instance by means of a cap supporting the rod and screwed onto the inner end of the spindle. This rod and the discs form together an easily detachable sub-assembly located in the immediate vicinity of the openings through which the oil-reagent mixture discharges from the feed chamber and is supplied to the separating chamber of the centrifuge.

The accompanying drawings show a preferred embodithe drawings,

Fig. l is a vertical sectional view of the apparatus,

Fig. 2 is a similar view, on a larger scale, of the uppermost part of the hollow spindle with the centrifugal bowl mounted thereon;

Fig. 3 is a horizontal sectional view on line IIIIII in Fig. 2;

Fig. 4 is a vertical sectional view of the lowermost part of the apparatus, including oil and lye supply means, and

Fig. 5 is a sectional view along line V-V in Fig. 4.

Referring to the drawings, the apparatus comprises pipes or supply means 1 and 2 for oil and lye, respectively. As best shown in Figs. 4 and 5, the oil pipe 1 communicates with a hollow spindle 3 and the lye pipe 2 communicates with a stationary tube 4 which is fitted in and is coaxial with the hollow spindle 3. The tube 4 is best shown in Figs. 2 and 4. The hollow spindle 3 is double-journalled in the bearing housings 5 and 6 and is driven by driving means including a worm wheel 7 and a worm 8. On the spindle 3., above the bearing housing 5, is mounted a centrifugal bowl 9 of common design, which is surrounded by a housing 10. The oil and the soap are discharged separately through the outlets 11 and 12, respectively.

The hollow spindle 3 (Fig. 2) is supported laterally in the upper bearing housing by the bearing assembly 5a, which is yieldingly centered in the housing by radial springs, one of which is shown at 5b. The stationary tube 4 terminates at its upper end a short distance below a series of discs 13 which are located in and rotate with the hollow spindle. These discs are arranged a short distance below the supply openings 14 of the bowl 9. The discs 13 are spaced from each other along the axis of the hollow spindle 3 and are disposed horizontally, that is, in planes at right angles to this axis.

Each disc 13 fits closely in the spindle 3 but is provided with two opposite segment-shaped openings 15 which form passages for the mixture of oil and lye, as best shown in Fig. 3. The discs 13 are all secured to a central rod 16 on which they are placed in such relation to each other that the mixture of oil and lye cannot pass through the disc openings 15 in a linear path. In the embodiment shown, the segment-shaped openings 15 in alternate discs 13 are displaced 90 from the corresponding openings 15' in the other discs. The rod 16 is supported at its upper end by a cap 14:: screwed on the upper end of the spindle and forming the openings 14.

In Fig. 4, I have shown on a large scale the journalling of the hollow spindle 3 in the lower bearing housing 6. The hollow spindle 3 is rotatable in the bearing 17 and is provided with a seal 18, while the tube 4 is held stationary in the hollow spindle 3 by means of a fitting 19. The central channel 20 of the tube 4 communicates with the lye supply means 2 by way of channels 21 in the fitting 19. An extension In of the oil pipe is fixed in surrounding relation to the reagent tube 4 and forms therewith an oil passage.

It will be understood that the stream of lye discharges from the upper end of tube 4 into the surrounding oil stream flowing upward through hollow spindle 3, and the oil and lye are then immediately mixed together as they fiow upward through the turbulence-producing passages formed by the discs 13. The mixture then passes promptly through the openings 14 into the separating chamber of bowl 9, where it is rapidly separated into oil and soap. Due to the back pressure on the material fed into the bowl 9, the rotating sub-chamber containing the discs 13 is kept completely filled with oil and lye during the feeding. This sub-chamber forms in effect a rotating feed chamber opening directly into the separating chamber of the bowl 9. The sealing collar 18 forms an hermetically sealed flow passage between the stationary oil supply pipe 1 and the outer portion of the rotating hollow spindle 3 of the bowl.

The significance of the present method is illustrated in the following examples, in which the temperature of the oil and lye (caustic soda) was about 94 C. and the lye was used in an excess of about 20% of the amount necessary to neutralize the free fatty acids of the oil.

Example 1 Palm oil having a free fatty acid content of 3.5% was neutralized with lye of 4.5 N. After the separation the refining loss was 5.3% and the oil had a free fatty acid content of 0.05%.

Example 2 Soya bean oil having a free fatty acid content of 0.78% was neutralized with lye of 3.5 N. After the separation the refining loss was 1.1% and the oil had a free fatty acid content of 0.06%.

Example 3 Lard (white hog grease) having a free fatty acid content of 5.2% was neutralized with lye of 4.3 N. After the separation the refining loss was 7.8% and the oil had a free fatty acid content of 0.08%.

Example 4 Cocoanut oil having a free fatty acid content of 4.3% was neutralized with lye of 2.4 N. After the separation the refining loss was 5.8% and the oil had a free fatty acid content of 0.04%.

I claim:

1. In the neutralization of fatty oils in a centrifuge by feeding separate streams of oil and aqueous alkali lye, respectively, into a rotating feed chamber forming a zone 4 of relatively low centrifugal force within the centrifuge, keeping said feed chamber filled with oil and lye during said feeding, the lye being led directly into and mixed with the oil mass rotating with said chamber, feeding the resulting mixture into a zone of relatively high centrifugal force formed by the separating chamber of said centrifuge to divide it into oil and soap, and separately discharging the oil and soap from said centrifuge, the improvement which comprises substantially heating at least the oil prior to the neutralization, passing the oillye mixture, during a period of time of less than a second, in turbulence-producing passages through said rotating feed chamber, and feeding said mixture immediately from said last chamber to the separating chamber.

2. The improvement according to claim 1, in which the oil and the lye are both heated to a temperature of about to C. prior to said neutralization.

3. The improvement according to claim 1, in which the oil-lye mixture is passed through said rotating feed chamber within a period of time less than 0.5 second.

4. The improvement according to claim 1, in which the oil-lye mixture is passed through said rotating feed chamber within a period of time in the order of 0.1 second.

5. In a centrifuge comprising a centrifugal bowl rotatable on a vertical axis and having a separating chamber provided with separate outlets for oil and neutralization products, respectively, a hollow spindle extending from the bowl and forming a rotating feed chamber opening directly into the separating chamber, a fixed reagent supply tube extending through the hollow spindle into the feed chamber, an oil supply pipe fixed in surrounding relation to the reagent tube and forming therewith an oil passage, and means forming an hermetically sealed passage between the oil supply pipe and the outer portion of the bowl spindle, the improvement comprising means in said feed chamber forming turbulence-producing passages for the oil-reagent mixture.

6. A centrifuge according to claim 5, in which said turbulence-producing means include discs disposed perpendicularly to the axis of rotation of said feed chamber and spaced from each other along said axis, each of said discs forming openings displaced angularly in relation to corresponding openings in adjacent discs.

7. A centrifuge according to claim 5, in which said turbulence-producing means include discs disposed perpendicularly to the axis of rotation of said feed chamber and spaced from each other along said axis, each of said discs forming openings displaced angularly in relation to corresponding openings in adjacent discs, and a rod extending axially through the feed chamber from the upper end of the hollow spindle and, supporting discs.

8. A centrifuge according to claim 5, in which said turbulence-producing means include discs disposed perpendicularly to the axis of rotation of said feed chamber and spaced from each other along said axis, each of said discs forming openings displaced angularly in relation to corresponding openings in adjacent discs, a rod extending axially through the feed chamber and supporting the discs, and a cap supporting the rod and secured to the upper end of the spindle, the cap forming an opening leading from said feed chamber to said separating chamber.

References Cited in the file of this patent UNITED STATES PATENTS 542,756 Ekenberg July 16, 1895 791,496 Ponten June 6, 1905 2,182,755 Clayton et al. Dec. 5, 1939 2,663,719 Ayres Dec. 22, 1953

Claims (1)

1. IN THE NEUTRALIZATION OF FATTY OILS IN A CENTRIFUGE BY FEEDING SEPARATE STREAMS OF OIL AND AQUEOUS ALKALI LYE, RESPECTIVELY, INTO A ROTATING FEED CHAMBER FORMING A ZONE OF RELATIVELY LOW CENTRIFUGAL FORCE WITHIN THE CENTRIFUGE, KEEPING SAID FEED CHAMBER FILLED WITH OIL AND LYE DURING SAID FEEDING, THE LYE BEING LED DIRECTLY INTO AND MIXED WITH THE OIL MASS ROTATING WITH SAID CHAMBER, FEEDING THE RESULTING MIXTURE INTO A ZONE OF RELATIVELY HIGH CENTRIFUGAL FORCE FORMED BY THE SEPARATING CHAMBER OF SAID CENTRIFUGE TO DIVIDE IT INTO OIL AND SOAP, AND SEPARATELY DISCHARGING THE OIL AND SOAP FROM SAID CENTRIFUGE, THE IMPROVEMENT WHICH COMPRISES SUBSTANTIALLY HEATING AT LEAST THE OIL PRIOR TO THE NEUTRALIZATION, PASSING THE OILLYE MIXTURE, DURING A PERIOD OF TIME OF LESS THAN A SECOND,

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