METHOD AND EQUIPMENT FOR GREASE PURIFICATION

Abstract

A method for grease purification is disclosed. The method comprises steps of: S1, feeding crude grease into a grease hydrolysis column to be hydrolysed so as to obtain aqueous phase, organic phase, and middle layer substances between the aqueous phase and the organic phase; S2, feeding the organic phase and the middle layer substances in the grease hydrolysis column into a flash stripping column to be flashed so as to obtain vaporized products and non-vaporized products; and S3, feeding the vaporized products in the flash stripping column into a separation column to be separated so as to obtain fatty acid. By this method, fatty acid with a high purity can be obtained; glycerin can be obtained as a co-product; and high value-added nutrients in the grease can be collected. Therefore, the use value of grease can be greatly improved.

Claims

1. A method for grease purification, comprising steps of: S1, feeding crude grease into a grease hydrolysis column to be hydrolysed so as to obtain an aqueous phase, an organic phase, and middle layer substances between the aqueous phase and the organic phase; S2, feeding the organic phase and the middle layer substances in the grease hydrolysis column into a flash stripping column to be flashed to obtain vaporized products and non-vaporized products; and S3, feeding the vaporized products in the flash stripping column into a separation column to be separated to obtain fatty acid.

2. The method according to claim 1, wherein the aqueous phase comprises glycerin and water; wherein the aqueous phase in the grease hydrolysis column is discharged therefrom and is fed into a first heat exchanger to exchange heat with crude grease, and the crude grease is fed into the grease hydrolysis column to be hydrolysed; and wherein the aqueous phase is heated by a second heat exchanger and is returned to the grease hydrolysis column for hydrolysis reaction.

3. The method according to claim 2, wherein the second heat exchanger uses hot stream with a temperature in a range from 150° C. to 200° C. obtained by a second solar energy collecting device as a heat source.

4. The method according to claim 1, wherein when a mass concentration of glycerin in the aqueous phase reaches 50% to 75%, part of the aqueous phase is discharged and water is supplemented to ensure that an upper surface of the aqueous phase in the grease hydrolysis column is in a middle part of the grease hydrolysis column.

5. The method according to claim 4, wherein when a mass concentration of glycerin in the aqueous phase reaches 60% to 70%, part of the aqueous phase is discharged and water is supplemented to ensure that an upper surface of the aqueous phase in the grease hydrolysis column is in a middle part of the grease hydrolysis column.

6. The method according to claim 1, wherein the crude grease is classified into high unsaturated fatty acid contained crude grease with a mass concentration of unsaturated fatty acid in a range from 15% to 50% and low unsaturated fatty acid contained crude grease with a mass concentration of unsaturated fatty acid lower than 15%; and wherein the high unsaturated fatty acid contained crude grease is hydrolysed by a medium pressure hydrolysis method, and the low unsaturated fatty acid contained crude grease is hydrolysed by a high pressure hydrolysis method.

7. The method according to claim 6, wherein a pressure of the high pressure hydrolysis method is in a range from 4.5 Mpa to 5.5 Mpa, and/or a temperature thereof is in a range from 245° C. to 300° C.; and wherein a pressure of the medium pressure hydrolysis method is in a range from 2.5 Mpa to 4.0 Mpa, and/or a temperature thereof is in a range from 210° C. to 240° C.

8. The method according to claim 2, wherein a mass ratio of the crude grease to the aqueous phase fed into the grease hydrolysis column is 1:2 to 1:4, and a total mass space velocity of the crude grease and the aqueous phase fed into the grease hydrolysis column is 0.1.sup.−1 to 1 h.sup.−1.

9. The method according to claim 8, wherein a total mass space velocity of the crude grease and the aqueous phase fed into the grease hydrolysis column is 0.15 .sup.−1 to 1 h.sup.−1.

10. The method according to claim 1, wherein operating conditions of the flash stripping column are: a temperature being in a range from 210° C. to 240° C., and/or a pressure being in a range from 0.3 KPa to 0.5 KPa.

11. The method according to claim 1, wherein the separation column is a cooling column; and wherein an operating temperature of the cooling column is in a range from 100° C. to 115° C., and/or the cooling column uses water as a cooling medium.

12. The method according to claim 11, wherein cooling water from the cooling column is mixed with the aqueous phase discharged from the grease hydrolysis column to form a mixture, which is then heated by the second heat exchanger and returned to the grease hydrolysis column for hydrolysis reaction.

13. The method according to claim 1, wherein heat of the grease hydrolysis column and heat of the flash stripping column are provided by vapor from a third heat exchanger.

14. The method according to claim 13, wherein the third heat exchanger uses hot stream with a temperature in a range from 250° C. to 350° C. obtained by a first solar energy collecting device as a heat source.

15. The method according to claim 13, wherein vapor from the third heat exchanger is divided into a first vapor and a second vapor, wherein: the first vapor flows through the flash stripping column, and is then mixed with the second vapor to form a mixture, which then flows through the grease hydrolysis column and is then returned to the third heat exchanger.

16. An apparatus for use in the method according to claim 1, comprising a first solar energy collecting device, a second solar energy collecting device, an aqueous phase circulating system, and a grease purification and fatty acid production system, wherein the grease purification and fatty acid production system comprises a grease hydrolysis column, a flash stripping column, and a cooling column which are connected in sequence; wherein the first solar energy collecting device is connected to a third heat exchanger, which is connected to the grease hydrolysis column and the flash stripping column through vapor pipelines; and wherein the aqueous phase circulating system comprises a first heat exchanger, an aqueous phase storage tank, a second heat exchanger, and a grease hydrolysis column in sequence along a flow direction of an aqueous phase, wherein the first heat exchanger is provided on a crude grease feeding pipeline for heat exchange between the aqueous phase and the crude grease.

17. The apparatus according to claim 16, wherein a condensed water outlet of the cooling column is connected to the aqueous phase storage tank through a pipeline, and/or a vapor pipeline outlet of the grease hydrolysis column is connected to a vapor pipeline inlet of the flash stripping column; and wherein the first solar energy collecting device or the second solar energy collecting device comprises heat collectors.

18. The apparatus according to claim 17, wherein each heat collector is a trough heat collector, which comprises a trough reflector, a vacuum glass heat collecting pipe, and a bracket; and wherein the heat collectors are in series connection with one another to form heat collector groups, and the heat collector groups are in parallel connection with one another.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0033] The accompanying drawings provide further understandings of the present disclosure and constitute one part of the description. The drawings are used for interpreting the present disclosure together with the embodiments, not for limiting the present disclosure. In the drawings:

[0034] FIG. 1 is a flow chart according to one preferred embodiment of the present disclosure.

DETAILED DESCRIPTION OF THE EMBODIMENTS

[0035] The present disclosure will be illustrated in detail hereinafter in combination with the embodiments, but the present disclosure is not limited to the embodiments disclosed herein.

[0036] FIG. 1 is a flow chart according to one preferred embodiment of the present disclosure. Crude grease exchanges heat with aqueous phase in a first heat exchanger, and is fed into a grease hydrolysis column to be hydrolysed. In the grease hydrolysis column, high unsaturated fatty acid contained crude grease with a mass concentration of unsaturated fatty acid in a range from 15% to 50% is hydrolysed by a medium pressure hydrolysis method, and low unsaturated fatty acid contained crude grease with a mass concentration of unsaturated fatty acid lower than 15% is hydrolysed by a high pressure hydrolysis method. A pressure of the high pressure hydrolysis method is in a range from 4.5 Mpa to 5.5 Mpa, and/or a temperature thereof is in a range from 245° C. to 300° C. A pressure of the medium pressure hydrolysis method is in a range from 2.5 Mpa to 4.0 Mpa, and/or a temperature thereof is in a range from 210° C. to 240° C. The crude grease is hydrolysed in the grease hydrolysis column to obtain organic phase containing fatty acid in an upper layer, aqueous phase containing glycerin in a lower layer, and macromolecular insolubles in a middle layer between the aqueous phase and the organic phase. The organic phase and the middle layer substances (non-aqueous phase) obtained in the grease hydrolysis column are fed into a flash stripping column to be flashed so as to obtain vaporized products and non-vaporized products. Operating conditions of the flash stripping column are: a temperature being in a range from 210° C. to 240° C., and/or a pressure being in a range from 0.3 KPa to 0.5 KPa. The vaporized products from the flash stripping column are fed into a cooling column, and an operating temperature of the cooling column is in a range from 100° C. to 115° C. Light fraction of acid, aldehyde and ketone are discharged from a top of the cooling column, and fatty acid with a high purity can be obtained at a bottom of the cooling column. The cooling column uses water as a cooling medium. During this process, heat of the grease hydrolysis column and heat of the flash stripping column are provided by vapor from a third heat exchanger. The third heat exchanger uses hot stream with a temperature in a range from 250° C. to 350° C. obtained by a first solar energy collecting device as a heat source. Vapor with a high temperature from the third heat exchanger is divided into a first vapor and a second vapor. The first vapor flows into the flash stripping column to provide heat to the flash stripping column, and then flows out of the flash stripping column and is mixed with the second vapor to form a mixture, which then flows into the grease hydrolysis column to provide heat to the grease hydrolysis column, and is then returned to the third heat exchanger.

[0037] The aqueous phase in the lower layer of the grease hydrolysis column is discharged, and is fed into a first heat exchanger to exchange heat with the crude grease. The crude grease is heated, and is fed into the grease hydrolysis column. The aqueous phase is used in a circulating manner. During the aqueous phase circulation process, when a mass concentration of glycerin in the aqueous phase reaches 60% to 70%, part of the aqueous phase is discharged from an aqueous phase storage tank. Residual part of the aqueous phase is mixed with condensed water from the cooling column to form a mixture, which is fed into a second heat exchanger to be heated, and is then returned to the grease hydrolysis column to be hydrolysed. The second heat exchanger uses hot stream with a temperature in a range from 150° C. to 200° C. obtained by a second solar energy collecting device as a heat source.

Embodiment 1

[0038] A method for purifying waste grease (the waste grease has an unsaturated fatty acid content in a range from 7% to 15%, and is a low unsaturated fatty acid contained grease) and producing fatty acid, as well as glycerin and nutrients as co-products using solar energy. The method comprises following steps. Before waste grease purification, a N.sub.2 replacement system is used to remove the influence of oxygen on hydrolysis reaction. The waste grease exchanges heat with aqueous phase discharged from a grease hydrolysis column, and is fed into the grease hydrolysis column. Operating conditions of the grease hydrolysis column are: a pressure being in a range from 4.5 MPa to 5.0 MPa, and a temperature being 280° C. A mass ratio of the crude grease to the aqueous phase fed into the grease hydrolysis column is 1:3, and a total mass space velocity of the crude grease and the aqueous phase fed into the grease hydrolysis column is 0.5 W.sup.−1. In the grease hydrolysis column, the crude grease is hydrolysed to fatty acid and glycerin. Glycerin is mainly contained in the aqueous phase, and is in a lower layer of the grease hydrolysis column. Organic phase contains fatty acid and a small amount of aldehyde and ketone, and is in an upper layer of the grease hydrolysis column. Pigments, sterol, and vitamin are in a middle layer between the aqueous phase and the organic phase. The organic phase and the middle layer substances (non-aqueous phase) in the grease hydrolysis column are fed into a flash stripping column. An operating temperature of the flash stripping column is 230° C., and a pressure thereof is 0.35 Kpa. Fatty acid is immediately vaporized in the flash stripping column and then enters into a cooling column. Non-vaporized products in the flash stripping column include sterol, vitamin, DHA, EPA, chlorophyll, lutein and other substances. Vaporized products of the flash stripping column are cooled in the cooling column. An operating temperature of the cooling column is 100° C. Light fraction of acid, aldehyde and ketone are separated from fatty acid, and fatty acid with a purity of 98% is obtained.

[0039] The aqueous phase in the grease hydrolysis column is discharged therefrom, exchanges heat with crude grease, and enters into an aqueous phase storage tank. The aqueous phase is heated by a second heat exchanger, and is then returned to the grease hydrolysis column. The aqueous phase is used in a circulating manner. During the aqueous phase circulation process, when a mass concentration of glycerin in the aqueous phase reaches 70%, part of the aqueous phase is discharged and water is supplemented to ensure that an upper surface of the aqueous phase in the grease hydrolysis column is in a middle part of the grease hydrolysis column. The discharged aqueous phase is collected to obtain glycerin with a concentration of 70%.

Embodiment 2

[0040] A method for purifying microalgae grease (the microalgae grease has an unsaturated fatty acid content in a range from 20% to 30%, and is a high unsaturated fatty acid contained grease) and producing fatty acid, as well as glycerin and nutrients as co-products using solar energy. The method comprises following steps. Before microalgae grease purification, a N.sub.2 replacement system is used to remove the influence of oxygen on hydrolysis reaction. The microalgae grease exchanges heat with aqueous phase discharged from a grease hydrolysis column, and is fed into the grease hydrolysis column. Operating conditions of the grease hydrolysis column are: a pressure being in a range from 2.5 MPa to 3.0 MPa, and a temperature being 210° C. A mass ratio of the crude grease to the aqueous phase fed into the grease hydrolysis column is 1:3, and a total mass space velocity of the crude grease and the aqueous phase fed into the grease hydrolysis column is 0.75 h.sup.−1. In the grease hydrolysis column, the crude grease is hydrolysed to fatty acid and glycerin. Glycerin is mainly contained in the aqueous phase, and is in a lower layer of the grease hydrolysis column. Organic phase contains fatty acid and a small amount of aldehyde and ketone, and is in an upper layer of the grease hydrolysis column. Pigments, sterol, and vitamin are in a middle layer between the aqueous phase and the organic phase. The organic phase and the middle layer substances (non-aqueous phase) in the grease hydrolysis column are fed into a flash stripping column. An operating temperature of the flash stripping column is 210° C., and a pressure thereof is 0.3 Kpa. Fatty acid, aldehyde and ketone are immediately vaporized in the flash stripping column and enter into a cooling column. Non-vaporized products of the flash stripping column include sterol, vitamin, DHA, EPA, chlorophyll, lutein and other substances. Vaporized products of the flash stripping column are cooled in the cooling column. An operating temperature of the cooling column is 100° C. Light fraction of C.sub.2-C.sub.5 acid, aldehyde and ketone are separated from fatty acid, and fatty acid with a purity of 96% is obtained.

[0041] The aqueous phase in the grease hydrolysis column is discharged therefrom, exchanges heat with crude grease, and enters into an aqueous phase storage tank. The aqueous phase is heated by a second heat exchanger, and is then returned to the grease hydrolysis column. The aqueous phase is used in a circulating manner. During the aqueous phase circulation process, when a mass concentration of glycerin in the aqueous phase reaches 60% to 70%, part of the aqueous phase is discharged and water is supplemented to ensure that an upper surface of the aqueous phase in the grease hydrolysis column is in a middle part of the grease hydrolysis column. The discharged aqueous phase is collected to obtain glycerin with a concentration of 60% to 70%.

[0042] It should be noted that, the above embodiments are only used for explaining the present disclosure, rather than limiting the present disclosure. The present disclosure is described with reference to the exemplary embodiments, but it should be understood that words used therein are explanatory words, rather than definitive words. The present disclosure can be modified within the scope of the claims according to regulations. Also, amendments can be made to the present disclosure without departing from the scope and spirit thereof. Although the present disclosure relates to specific methods, materials, and embodiments, it is not intended that the present disclosure is limited to the specific embodiments disclosed herein. The present disclosure can be extended to all other methods and applications having same functions.

LIST OF REFERENCE SIGNS

[0043] 1—crude grease;

[0044] 2—organic phase and middle layer substances;

[0045] 3—aqueous phase;

[0046] 4—vaporized products;

[0047] 5—non-vaporized products (sterol, vitamin, pigment and so on);

[0048] 6—light fraction of acid, aldehyde and ketone;

[0049] 7—fatty acid;

[0050] 8—cooling water;

[0051] 9—vapor;

[0052] 10—second vapor;

[0053] 11—first vapor;

[0054] 12—hot stream with a temperature in a range from 250° C. to 350° C. obtained by a first solar energy collecting device;

[0055] 13—hot stream with a temperature in a range from 150° C. to 200° C. obtained by a second solar energy collecting device;

[0056] 14—first solar energy collecting device;

[0057] 15—third heat exchanger;

[0058] 16—grease hydrolysis column;

[0059] 17—flash stripping column;

[0060] 18—cooling column;

[0061] 19—crude grease tank;

[0062] 20—first heat exchanger;

[0063] 21—aqueous phase storage tank;

[0064] 22—second heat exchaner; and

[0065] 23—second solar energy collecting device.