Process for deodorizing edible oil

1. A process for deodorizing edible oil by a semi continuously operating steam distillation plant, comprising a stripping column with a plurality of separating stages configured to be shut off against each other, which are arranged therein, a degassing stage upstream of the stripping column and a downstream vapor scrubber, a vacuum generating plant connected with the degassing stage, the separating stages, and the vapor scrubber, one supply conduit each for stripping steam, which opens into the degassing stage and the separating stages, indirect heat exchanger surfaces each arranged in the separating stages of the upper and the lower portion of the stripping column, and a vapor discharge conduit opening into the vapor scrubber, which is connected with the separating stages arranged in upper and lower portions of the stripping column, the process comprising:

(i) first, generating a vacuum of 2 to 7 mbar in the distillation plant;

(ii) filling the degassing stage with a batch of feedstock edible oil;

(iii) automatically passing the batch through the degassing stage and the separating stages, one after the other, after predetermined retention times of 20 to 40 min per stage controlled in dependence on performance;

(iv) preheating the batch in the degassing stage with stripping steam to a temperature of 75 to 80° C., to obtain a preheated batch;

(v) heating up the preheated batch to a temperature of 150 to 180° C. in the separating stages of the upper portion of the stripping column, to obtain a first heated portion;

(vi) heating up the first heated portion in the separating stages of a middle portion of the stripping column to a temperature of 230 to 260° C., to obtain a second heated portion;

(vii) cooling the second heated portion in the separating stages of the lower portion of the stripping column to a temperature of 90 to 120° C.;

(viii) washing and condensing vapors discharged from the separating stages of the upper and the lower portion of the stripping column in the vapor scrubber with circulating sprayed fatty acid, to obtain a fatty acid mixed distillate;

(ix) indirectly heating at least the hatch present in a downstream first separating stage of the middle portion of the stripping column with high-pressure steam;

(x) indirectly cooling vapors discharged from the separating stages of the middle portion of the stripping column in at least a first condensation stage, a second condensation stage, and a third condensation stage; and

(xi) fractionating in pure-grade form, condensed vapors, from the indirectly cooling (x), into a first fatty acid phase rich in sterols and tocopherols and a second fatty acid phase poor in sterols and tocopherols,

wherein, in the third condensation stage, edible oil droplets entrained by the vapors are separated off.

2. The process of claim 1 , wherein the distillation plant is charged with at least two batches of the same feedstock edible oil in succession.

3. The process of claim 1 , wherein the first fatty acid phase is condensed in a first condensation stage, and

wherein the second fatty acid phase is condensed in a second condensation stage.

4. The process of claim 3 , wherein surface heat exchangers are used as condensation stages for the vapors.

5. The process of claim 4 , wherein the surface heat exchangers are cooled separate from each other.

6. The process of claim 1 , further comprising:

indirectly transferring heat obtained by indirect heat transfer from the preheated hatches present in the separating stages of the lower portion of the stripping column to the preheated batches present in the separating stages of the upper portion of the stripping column.

7. The process of claim 1 , wherein, of the batches present in the separating stages of the middle portion of the stripping column, at least the batch present in the downstream first separating stage is indirectly heated with high-pressure steam.

8. The process of claim 1 , comprising indirectly cooling a batch present in a downstream last separating stage of the stripping column.

9. The process of claim 4 , wherein the surface heat exchangers are cooled with tempered cooling water.

10. The process of claim 1 , wherein the heating in (v) and (vi) is gradual.

11. The process of claim 1 , wherein the cooling in (vii) is gradual.

12. The process of claim 1 , wherein the heating in (v) and (vi) is gradual, and

wherein the cooling in (vii) is gradual.

13. The process of claim 1 , wherein the second fatty acid phase is substantially free of sterols and tocopherols.

14. The process of claim 1 , wherein the second fatty acid phase is free of sterols and tocopherols.

15. The process of claim 1 , wherein vapors comprising most of the fatty acids, sterols, and tocopherols are obtained in the separating stages present in the middle portion of the stripping column.

16. The process of claim 1 , wherein batches present in the separating stages located in the upper portion of the distillation column are heated with heat obtained from the separating stages.

17. The process of claim 1 , further comprising:

changing a product grade of the edible oil when charging the edible oil without interruption of the deodorizing process.

18. The process of claim 1 , further comprising:

changing a product grade of the edible oil without draining the distillation plant.

19. The process of claim 1 , wherein control of the deodorizing process is effected using a process control system, by which individual process steps can be controlled and monitored automatically.

20. The process of claim 1 , wherein the first, second, and third condensation stages are within one cold trap, separate from the stripping column.