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 mixture of a fatty ester of an alkoxylated polyol and 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 mixture of a fatty ester of an alkoxylated polyol and a fatty ester of alkoxylated glycerol.

2. The method according to claim 1 wherein the polyol is a sugar.

3. The method according to claim 2 wherein the sugar is sucrose.

4. The method according to claim 1 wherein the fatty esters are derived from fatty acids and/or derivatives thereof.

5. The method according to claim 4 wherein the fatty acids comprise soya bean fatty acids.

6. The method according to claim 4 wherein the composition of the fatty acid residues of the fatty ester of an alkoxylated polyol are the same as the fatty acid residues of the fatty ester of alkoxylated glycerol.

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

8. The method according to claim 1 wherein the ratio of the number of ester bonds in the fatty ester of an alkoxylated polyol, to hydroxyl groups present in the polyol starting material, is 0.3 to 0.7:1.

9. The method according to claim 1 wherein the fatty ester of alkoxylated glycerol comprises 1.3 to 1.8 ester bonds.

10. The method according to claim 1 wherein the fatty ester of an alkoxylated polyol comprises a polyalkylene oxide chain and wherein the total number of alkylene oxide groups in the polyalkylene oxide chains of the fatty ester of an alkoxylated polyol is 40 to 90.

11. The method according to claim 1 wherein the fatty ester of alkoxylated glycerol comprises a polyalkylene oxide chain and wherein the total number of alkylene oxide groups in the polyalkylene oxide chains of the fatty ester of alkoxylated glycerol is 12 to 35.

12. A stillage and product derived therefrom comprising a mixture of a fatty ester of an alkoxylated polyol and a fatty ester of alkoxylated glycerol.

13. A separation additive comprising a mixture of a fatty ester of an alkoxylated polyol and a fatty ester of alkoxylated glycerol.

14. The separation additive according to claim 13 obtainable by alkoxylating a mixture of a polyol and a triglyceride.

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

16. The method according to claim 15, wherein the stillage is selected from whole stillage, thin stillage, and concentrated stillage.

17. The method according to claim 15, wherein the oil is corn oil.

Description

EXAMPLE 1

[0081] A mixture of a fatty ester of alkoxylated sucrose and a fatty ester of alkoxylated glycerol was produced in a one pot process using the materials listed in Table 1.

TABLE-US-00001 TABLE 1 Molar Raw Material Wt (g) Ratio Wt. % Sucrose (co-milled with 14.5% 92.5 1.0 5.8 Potassium Stearate) Soya Bean Oil (ex Cargill) 552.5 2.7 35.0 Ethylene Oxide 934.0 92 59.2 Total 1578 100.0 KOH (45%) 2.0 ~0.07 H.sub.3PO.sub.4 2.0

Reaction Process:

[0082] 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.

[0083] ii) The reactor was heated slowly to 100° C. with agitation and nitrogen sweep on.

[0084] iii) As the temperature was increased, vacuum was applied to remove water.

[0085] iv) Once the residual water was reduced to below 0.2% at temperature range of 90 to 100° C., the sucrose (co-milled with potassium stearate at 14.5%) was added.

[0086] v) With agitation on, the reaction mixture was purged with nitrogen and the reactor temperature increased to 130° C.

[0087] 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.

[0088] 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.

[0089] 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.

[0090] 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. The reaction product had an acid value of 0.6 mg KOH/g, a hydroxyl value of 87.6 mg KOH/g and a saponification value of 82.1 mg KOH/g.

EXAMPLE 2

[0091] The product produced in Example 1 was used as a separation additive in the corn oil separation test described herein using stillage sample from different corn ethanol plants. 5 samples from 3 stillages (Stillages A, B and C) were treated and the height of the clear oil layer (indicating the separation performance) was measured in millimetres (mm) for each sample. The average height was calculated. The results are shown in Table 2. Stillage A, Stillage B and Stillage C are representative stillages from different types of corn at different ages of harvest.

TABLE-US-00002 TABLE 2 Sample No Average 1 2 3 4 5 (mm) Stillage A 3 5 5 4 4 4.2 Stillage B 5 5 5 5 5 5 Stillage C 5 5 5 5 5 5

EXAMPLE 3

[0092] 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.

TABLE-US-00003 TABLE 3 Average Sample No (mm) Stillage A 5.4 Stillage B 1 Stillage C 3

[0093] The above examples illustrate the improved properties of a separation additive, and use thereof, according to the present invention.

[0094] 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.