Method for reducing the tar content in pyrolysis gas

Patent metadata

Field	Value
Publication number	US-11220644-B2
Application number	US-201816652648-A
Country	US
Kind code	B2
Filing date	Oct 12, 2018
Priority date	Oct 12, 2017
Publication date	Jan 11, 2022
Grant date	Jan 11, 2022

Abstract

Disclosed is a method for reducing the tar content in pyrolysis gas generated in a pyrolysis reactor (1). The method comprises the steps of: guiding the pyrolysis gas through a filter (2) to remove at least 90% of all the particles in the pyrolysis gas having a particle size down to 7μ and preferably down to 4μ from the pyrolysis gas, partially oxidizing the pyrolysis gas in a partial oxidation reactor (3) to remove tar from the pyrolysis gas, and guiding the pyrolysis gas through a coke bed (4) to further remove tar from the pyrolysis gas. Furthermore, a two-stage gasifier (6) is disclosed.

First claim

The invention claimed is:

1. A method for reducing the tar content in pyrolysis gas generated in a pyrolysis reactor, said method comprising the steps of:
guiding said pyrolysis gas through one or more filters to remove at least 90% of all the particles in said pyrolysis gas having a particle size down to 7 μm from said pyrolysis gas,
partially oxidizing said pyrolysis gas in a partial oxidation reactor to remove tar from said pyrolysis gas, and
guiding said pyrolysis gas through a coke bed to further remove tar from said pyrolysis gas,
wherein said coke bed is arranged external to said pyrolysis reactor and external to a gasifier arranged to gasify pyrolysis coke generated in said pyrolysis reactor.

2. A method according to claim 1 , wherein said method further comprises the step of guiding said pyrolysis gas through a cyclone to remove particles in said pyrolysis gas having a particle size down to 20 μm from said pyrolysis gas, before said pyrolysis gas is guided through said filter.

3. A method according to claim 2 , wherein said particles that are removed by said cyclone are guided into said coke bed to form part of said coke bed and/or into a gasifier.

4. A method according to claim 1 , wherein said particles that are removed by said one or more filters are guided into said coke bed to form part of said coke bed and/or into a gasifier.

5. A method according to claim 1 , wherein said filter removes at least 90% of all the particles in said pyrolysis gas having a particle size down to 2 μm from said pyrolysis gas.

6. A method according to claim 1 , wherein said partial oxidation raises the temperature of said pyrolysis gas to between 500 and 2,500° C.

7. A method according to claim 1 , wherein said coke bed has a temperature of between 400 and 2,000° C.

8. A method according to claim 1 , wherein said coke bed is a fluid bed coke bed.

9. A method according to claim 1 , wherein said pyrolysis reactor is a fluid bed pyrolysis reactor.

10. A method according to claim 1 , wherein said partial oxidation involves adding enough oxygen to combust all said pyrolysis gas between 5% and 70%.

11. A method according to claim 1 , wherein said pyrolysis gas has a temperature of between 100 and 1,000° C. when entering said partial oxidation reactor.

12. A method according to claim 1 , wherein said method comprises the step of generating said pyrolysis gas by heating biomass.

13. A method according to claim 1 , wherein material in said pyrolysis reactor is heated by forming a flow of oxygen and/or superheated steam into said pyrolysis reactor.

14. A method according to claim 1 , wherein said one or more filters remove at least 95% of all the particles in said pyrolysis gas having a particle size down to 4 μm from said pyrolysis gas.

15. A method according to claim 1 , wherein said one or more filters comprises a candle filter.

16. A two-stage gasifier arranged to remove tar from pyrolysis gas by means of a method according to claim 1 .

17. A method according to claim 1 , said step of guiding said pyrolysis gas through one or more filters removes at least 90% of all the particles in said pyrolysis gas having a particle size down to 4 μm.

18. A method according to claim 1 , wherein said method further comprises the step of guiding said pyrolysis gas through a cyclone to remove particles in said pyrolysis gas having a particle size down to 12 μm from said pyrolysis gas, before said pyrolysis gas is guided through said filter.

Assignees

• Univ Danmarks Tekniske

Inventors

• Henriksen Ulrik Birk
• Ahrenfeldt Jesper

Classifications

• C10K1/024

  by filtration · CPC title

• C10B53/02

  of cellulose-containing material (production of pyroligneous acid C10C5/00) · CPC title

• C10K3/005

  by partial oxidation · CPC title

• C10K1/046 Primary

  Reducing the tar content · CPC title

• C10B49/10

  according to the "fluidised bed" technique · CPC title