Method of separating oil

Abstract

A method of separating oil from a composition containing an oil and water emulsion, by adding a separation additive which is a fatty ester of alkoxylated glycerol, and performing at least one oil separation step. The method is particularly suitable for separating corn oil from stillage produced in a corn ethanol mill.

Claims

1. A method of separating oil from a composition comprising an oil and water emulsion, which comprises adding a separation additive to the composition and performing at least one oil separation step, wherein the separation additive comprises a fatty ester of alkoxylated glycerol having an average of less than 3 ester bonds or fatty chains.

2. The method according to claim 1 wherein the fatty ester is derived from fatty acids and/or derivatives thereof.

3. The method according to claim 2 wherein the fatty acids are selected from the group consisting of canola, soya bean, corn, tall, palm kernel, coconut, rapeseed, high erucic rapeseed, tallow fatty acids and mixtures thereof.

4. The method according to claim 1 wherein the fatty ester of alkoxylated glycerol comprises 1.0 to 2.0 ester bonds.

5. The method according to claim 1 wherein the fatty ester of alkoxylated glycerol comprises a polyalkylene oxide chain and wherein the average number of alkylene oxide groups in each polyalkylene oxide chain of the fatty ester of alkoxylated glycerol is 4 to 7.

6. The method according to claim 5 wherein the total number of alkylene oxide groups in the polyalkylene oxide chains of the fatty ester of alkoxylated glycerol is 12 to 30.

7. The method according to claim 1 wherein the separation additive is obtainable by alkoxylating a mixture of a triglyceride and glycerol.

8. The method according to claim 1 wherein the separation additive comprises greater than 75 wt % of fatty ester of alkoxylated glycerol.

9. The method according to claim 8 wherein the separation additive comprises 90 to 99.9 wt % of fatty ester of alkoxylated glycerol.

10. The method according claim 1 wherein the separation additive has a HLB value of 13 to 14.

11. A stillage and product derived therefrom comprising a fatty ester of alkoxylated glycerol having an average of less than 3 ester bonds or fatty chains.

12. The stillage according to claim 11 wherein the fatty ester is derived from fatty acids and/or derivatives thereof.

13. A separation additive comprising a fatty ester of alkoxylated glycerol obtainable by alkoxylating a mixture of a triglyceride and glycerol, wherein the fatty ester of alkoxylated glycerol comprises an average of less than 3 ester bonds or fatty chains.

14. The separation additive according to claim 13 wherein the fatty ester of alkoxylated glycerol comprises a polyalkylene oxide chain and wherein the average number of alkylene oxide groups in each polyalkylene oxide chain of the fatty ester of alkoxylated glycerol is 4 to 7.

15. The method according to claim 1 wherein the composition comprising an oil and water emulsion is stillage.

16. The separation additive according to claim 13, wherein the fatty ester of alkoxylated glycerol comprises an average of 1.0 to 2.5 ester bonds or fatty chains.

17. The separation additive according to claim 13, further comprising an alkoxylated fatty ester.

18. The separation additive according to claim 17, wherein the alkoxylated fatty ester is present in an amount ranging from 0.05 to 10 wt % based on the total weight of the separation additive.

19. The separation additive according to claim 13, further comprising an alkoxylated glycerol.

20. The separation additive according to claim 19, wherein the alkoxylated glycerol is present in an amount ranging from 0.05 to 8 wt % based on the total weight of the separation additive.

21. The separation additive according to claim 13, wherein the separation additive has a hydroxyl value ranging from 60 to 110 mgKOH/g.

22. The separation additive according to claim 13, wherein the separation additive has an acid value less than 3 mgKOH/g.

23. The separation additive according to claim 13, wherein the separation additive has a saponification value ranging from 30 to 100 mgKOH/g.

24. The separation additive according to claim 13, wherein the separation additive has a HLB value ranging from 11 to 16.

25. The separation additive according to claim 14, wherein the total number of alkylene oxide groups in the polyalkylene oxide chains of the fatty ester of alkoxylated glycerol is 12 to 30.

Description

EXAMPLE 1

(1) The fatty ester of alkoxylated glycerol was produced in a one pot process using the materials listed in Table 1.

(2) TABLE-US-00001 TABLE 1 Molar Raw Material Wt (g) Ratio Wt. % Glycerol 90.2 1.86 6.4 Soybean Oil (ex Cargill) 462.8 1.0 33.1 Ethylene Oxide 847.0 36.5 60.5 Sub-Total 1400 100.0 KOH (45%) 2.0 ~0.07 H.sub.3PO.sub.4 2.0

(3) Reaction Process:

(4) i) The soya bean oil and catalyst (caustic potash, 45%) were added to a clean and dry 2-L pressurized Parr reactor at ambient temperature.

(5) ii) The reactor was heated slowly to 100 C. with agitation and nitrogen sweep on.

(6) iii) As the temperature was increased, vacuum was applied to remove water.

(7) iv) Once the residual water was reduced to below 0.2% at temperature range of 90 to 100 C., the glycerol was added.

(8) v) With agitation on, the reaction mixture was purged with nitrogen and the reactor temperature increased to 130 C.

(9) vi) The ethylene oxide was fed into the reactor at the temperature range of 130 to 150 C. The ethylene oxide feeding rate was controlled so that the reactor pressure did not exceed 50 psig.

(10) vii) Once all the ethylene oxide had been added, the reactor pressure was allowed to decrease at the reaction temperature range of 140 to 150 C. After the pressure drop reached a steady low rate, the reaction was continued for another 2 hours.

(11) viii) Vacuum was gradually applied to 20 torr or less in order to remove any unreacted ethylene oxide. The reactor temperature and vacuum were held for another 1 to 2 hours.

(12) iix) The reactor temperature was allowed to cool to 60 to 65 C., the product was neutralized with phosphoric acid, and the reaction product was then discharged.

(13) The reaction product had an acid value of 0.07 mg KOH/g, a hydroxyl value of 85.2 mg KOH/g and a saponification value of 52.9 mg KOH/g.

EXAMPLE 2

(14) The product produced in Example 1 was used as a separation additive in the corn oil separation test described herein using a stillage sample from a corn ethanol plant. The stillage was treated and the height of the clear oil layer (indicating the separation performance) was measured in millimeters (mm) for 5 samples. The average height was calculated. The results are shown in Table 2.

(15) TABLE-US-00002 TABLE 2 Sample No Average 1 2 3 4 5 (mm) Stillage 3 3 3 3 3 3

EXAMPLE 3

(16) This is a Comparative Example not according to the invention. The procedure of Example 2 was repeated except that polysorbate 80 was used as the separation additive instead of the product produced in Example 1. The results are shown in Table 3.

(17) TABLE-US-00003 TABLE 3 Sample No Average 1 2 3 4 5 (mm) Stillage 2 2 2 2 2 2

(18) The above examples illustrate the improved properties of the separation additive, and use thereof, according to the present invention.

(19) It is to be understood that the invention is not to be limited to the details of the above embodiments, which are described by way of example only. Many variations are possible.