Apparatus and method for producing biodiesel fuel

• US 20070260079A1
• Filed: 04/26/2007
• Published: 11/08/2007
• Est. Priority Date: 05/05/2006
• Status: Active Grant

• Current Assignee: Orbitek, Inc.
• Original Assignee: Orbitek, Inc.
• Inventors: Fleisher, Christian A.
• Granted Patent: US 7,420,072 B2
• Time in Patent Office: Days
• US Class Current: 554/174
• CPC Class Codes: C10G 2300/1011 Biomass
• CPC Class Codes: C10L 1/026 for compression ignition
• CPC Class Codes: C11C 3/003 by esterification of fatty acids with alcohols C11C3/02 takes precedence
• CPC Class Codes: Y02E 50/10 Biofuels, e.g. bio-diesel
• CPC Class Codes: Y02P 30/20 using bio-feedstock

Abstract

A continuous method and apparatus for making biodiesel fuel from glycerides such as vegetable oil employs a two-stage reactor provided with recycle. Yields of 95% and greater are readily achieved in a continuous mode of operation.

Claims

1. A process for the production of biodiesel grade, fatty acid alkyl esters comprising:

(a) reacting triglyceride, alcohol and catalyst in a first reaction zone to form a first intermediate reacted mixture which includes trans-esterified fatty acid ester product, glycerol, unreacted alcohol, and unreacted and partially reacted triglyceride;

(b) removing glycerol and unreacted alcohol from the first intermediate reacted mixture to form a second intermediate reacted mixture;

(c) feeding the second intermediate reacted mixture to a second reaction zone;

(d) adding a fresh feed of alcohol and catalyst into the second reaction zone to form fatty acid alkyl esters and glycerol from the second intermediate reacted mixture to form a third intermediate reacted mixture;

(e) separating alcohol, glycerol and a fraction of the fatty acid alkyl esters from the third intermediate reacted mixture; and

(f) recycling alcohol, glycerol and fatty acid alkyl esters recovered from the third intermediate reacted mixture to the first reaction zone.

2. The process according to claim 1, wherein the first and second reaction zones are tubular plug flow reactors operated at a pressure of from 50 psi to about 300 psi.

3. The process according to claim 1, wherein the reaction of triglyceride and alcohol is carried out in the presence of a catalyst.

4. A process according to claim 3, wherein the catalyst is an alkali selected from the group consisting of sodium hydroxide, potassium methoxide, sodium methoxide, sodium methylate and combinations thereof.

5. The process according to claim 1, wherein the alcohol includes methanol.

6. The process according to claim 1, wherein the alcohol and triglyceride are introduced into the first reaction zone in a mole ratio of alcohol to triglyceride of from about 4:

1 to about 8;

1.

7. The process according to claim 1, wherein the triglyceride feed stream is introduced into the first reaction zone at a temperature of from about 70°

C. to about 200°

C.

8. The process according to claim 2, wherein the triglyceride and the alcohol are introduced into the first reaction zone at a pressure of from 150 psi to 400 psi.

9. The process according to claim 8, wherein residence time in the tubular plug flow reactors is less than 3 minutes.

10. The process according to claim 1, wherein residence time in the first reaction zone is from 20 seconds to 30 seconds.

11. The process according to claim 1, wherein residence time in the second reaction zone is from 30 seconds to 60 seconds.

12. The process according to claim 1, wherein the amount of catalyst used is from 0.2 to about 2.0 percent by weight of triglyceride.

13. The process according to claim 1, wherein the total amount of catalyst used is from about 0.25 to about 1.25 percent by weight of triglyceride.

14. The process according to claim 1, wherein glycerol and unreacted alcohol is removed from the first intermediate reacted mixture with a hydroclone.

15. The process according to claim 1, wherein alcohol, glycerol and fatty acid ester are separated from the third intermediate reacted mixture with a hydroclone.

16. A process for the production of biodiesel fuel fatty acid alkyl esters comprising:

(a) feeding a fatty acid triglyceride, an alkanol and catalyst to a first tubular reaction zone;

(b) transesterifying the fatty acid triglyceride in the first tubular reaction zone to produce a first intermediate stream comprising fatty acid alkyl ester and glycerol;

(c) removing glycerol from said first intermediate stream to produce a second intermediate stream;

(d) feeding the second intermediate stream along with additional catalyst and additional alkanol to a second tubular reaction zone;

(e) transesterifying fatty acid triglyceride to produce fatty acid alkyl ester in said second tubular reaction zone to produce a third intermediate stream;

(f) separating the third intermediate stream into a crude product stream and an alkyl ester containing recycle stream; and

(g) recycling the recycle stream to the first reaction zone,

wherein the overall conversion of triglyceride to fatty acid alkyl ester in the process is greater than 95%.

17. The process according to claim 16, wherein the overall conversion of triglyceride to fatty acid alkyl ester in the process is greater than 99%.

18. The process according to claim 16, wherein the conversion of triglyceride at the end of the first reaction zone is from about 60% to about 80%.

19. The process according to claim 16, wherein said recycle stream includes at least 20% by volume of alkyl ester.

20. The process according to claim 16, wherein said recycle stream includes at least 35% by volume of alkyl ester.

21. An apparatus suitable for continuously producing biodiesel grade fatty acid alkyl esters comprising:

(a) a first tubular reactor adapted for receiving and reacting a mixture of an alkanol, triglyceride and catalyst at elevated temperature and pressure to form a first product stream including fatty acid alkyl esters, glycerol, alkanol, triglycerides and optionally monoglycerides and diglycerides;

(b) a first separator configured to receive the first product stream and separate glycerol and alkanol from the first product stream and to provide a second product stream comprising fatty acid alkyl esters, triglycerides and optionally monoglycerides and diglycerides;

(c) a second tubular reactor coupled to the first separator configured to receive the second product stream and adapted for reacting the second product stream with additional alkanol at elevated temperature and pressure to generate additional fatty acid alkyl esters in a third product stream;

(d) a second separator adapted to generate a fourth product stream comprising alkanol and fatty acid alkanol esters from the third product stream, the second separator also being configured to provide a recycle stream from the third product stream including alkanol, glycerin and not less than 20% by volume fatty acid alkyl ester; and

(e) a recycle line adapted to provide the recycle stream to the first tubular reactor.

22. The apparatus according to claim 21, wherein the first and second tubular reactors are adapted to operate at a temperature of from about 70°

C. to about 200°

C.

23. The apparatus according to claim 21, wherein the first and second tubular reactors are adapted to operate at a pressure of from about 150 psi to bout 400 psi.

24. The apparatus according to claim 21, wherein the first and second separators are hydroclones.

25. The apparatus according to claim 21, wherein the first and second tubular reactors have a diameter of from about ¼

″

to about 4″

.