A Biomass Gasification System

Abstract

The present invention relates to a biomass gasification system providing tar and biochar and to a method wherein tars are fixed to the biochar surface. The present invention also relates to use of said system.

Claims

1.-11. (canceled)

12. A biomass gasification system comprising: a biomass gasification reactor having at least one fuel-inlet for injecting carbonaceous fuel and oxidant into the gasification reactor whereby, in a thermo-chemical reaction, synthesis gas is generated, the synthesis gas having a solid particle content and a tar content; wherein the gasification reactor further has a syngas exit pipe via which the synthesis gas is extracted from the gasification reactor, and wherein the thermo-chemical reaction in the gasification reactor further also generates hot biochar; a wet gas cleaning device for receiving the synthesis gas from the syngas exit pipe, the wet gas cleaning device being arranged to direct the synthesis gas through a water mist in order to remove tar from the synthesis gas thereby generating a tar-and-water liquid reject; a mixer for receiving the hot biochar from the gasification reactor and mixing it with water thereby generating a biochar-and-water mixture; a separator device for separating the tar-and-water liquid reject into a tar stream and first water stream; and means for conveying the first water stream from the separator device to the mixer thereby exposing any remaining tars in the first water stream to the biochar whereby such tars are fixed to the biochar surface resulting in a cleaning of the first water stream.

13. The gasification system according to claim 12, wherein the separator device for separating the tar-and-water liquid reject is a sedimentation vessel.

14. The gasification system according to claim 12, wherein the separator device for separating the tar-and-water liquid reject is a centrifuge.

15. The gasification system according to claim 12, wherein the separator device for separating the tar-and-water liquid reject is a filter.

16. The gasification system according to claim 12, wherein the carbonaceous fuel has a particle size of maximum 3 millimeters, and wherein the biomass gasification reactor is adapted to accept fuel with such small particle size, thereby providing a correspondingly finely divided biochar for cleaning of the first water stream.

17. The gasification system according to claim 12, wherein the mixer comprises a second separator device for providing a biochar-and-water liquid reject and a dewatered biochar.

18. The gasification system according to claim 17, wherein the separator device for providing a biochar-and-water liquid reject is a filter.

19. The gasification system according to claim 17, wherein the separator device for providing a biochar-and-water liquid reject is sedimentation vessel.

20. The gasification system according to claim 17, wherein the mixer comprises a device for separating the tar-and-water liquid reject.

21. The gasification system according to claim 20, wherein the device for separating the tar-and-water liquid reject is a sedimentation vessel.

22. The gasification system according to claim 12, wherein the mixer comprises an inlet to enable the tar-containing first water stream to encounter dewatered biochar

23. The gasification system according to claim 12, wherein the wet gas cleaning device is a quencher.

24. A method for gasifying carbonaceous material by use of a system according to claim 12, for minimizing usage of water at the same time enabling biochar to adsorb tar.

25. A method for gasifying carbonaceous material comprising: injecting a carbonaceous fuel and oxidant into a gasification reactor whereby, in a thermo-chemical reaction, synthesis gas having tar and a solid particle content is generated and also at the same time, biochar is generated; extracting the synthesis gas from the gasification reactor; cooling and scrubbing the synthesis gas such that a tar-and-water liquid reject is formed; separating the tar-and-water liquid reject into a tar stream and a first water stream; conveying the first water stream and exposing any remaining tars in the first water stream to the biochar whereby such tars are fixed to the biochar surface resulting in a cleaning of the first water stream.

26. The method according to claim 25, wherein the biochar is mixed with water creating a biochar and water mixture, whereupon the biochar is separated from the biochar and water mixture, providing a dewatered biochar, and exposing the remaining tars with the dewatered biochar.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0034] For exemplifying purposes, the invention will be described in closer detail in the following with reference to embodiments thereof illustrated in the attached drawings, wherein:

[0035] FIGS. 1 and 2 disclose previous systems.

[0036] FIGS. 3 and 4 disclose gasification systems in accordance with embodiments of the present invention as set out in the first aspect.

DETAILED DESCRIPTION OF THE INVENTION

[0037] In the following, non-limiting examples there is disclosed how the biomass gasification system may be made and the usage thereof.

EXAMPLES

[0038] In the following, embodiments of the present invention will be discussed with reference to the accompanying figures. It should be noted that this detailed description by no means limits the scope of the invention. The scope of the invention is defined by the appended claims. Further, that specific features are mentioned in connection to an embodiment of the invention does not mean that those features cannot be used to an advantage together with other embodiments of the invention.

[0039] FIG. 1 and FIG. 2 disclose previous systems.

[0040] In FIG. 1 the following figures/flows may be used:

[0041] Fuel: 1000 kg dry/h

[0042] Circulating water: about 20 m3/h

[0043] Charcoal: 10-50 kg dry/h, 40-200 kg/wet

[0044] FIG. 3 discloses one exemplary embodiment of the present invention that combines the tar and water separation system and the charcoal (biochar) handling. In said FIG. 3 the charcoal and the tar water separation units are combined. This reduces capex, reduces fresh water demand as well as the amount of excess water that must be bled off. In addition to the mixing of charcoal with tar laden process water improves the tar water separation (tar components will adsorb to the charcoal e.g. the charcoal acts as an activated carbon).

[0045] In FIG. 3 the following flow may be used:

[0046] Fuel: 1000 kg dry/h

[0047] FIG. 4 discloses a second exemplary embodiment wherein you use the excess water bleed off as make up water in the charcoal handling system.

[0048] This will reduce the excess water bleed off.

[0049] In FIG. 4 the following figures/flows may be used:

[0050] Fuel: 1000 kg dry/h

[0051] Circulating water: about 20 m3/h

[0052] Charcoal: 10-50 kg dry/h, 40-200 kg/wet

[0053] Preferred features of each aspect of the invention are as for each of the other aspects mutatis mutandis.

[0054] 5