Gasification unit, a method for producing a product gas and use of such a method

Patent metadata

Field	Value
Publication number	US-11459518-B2
Application number	US-201816652621-A
Country	US
Kind code	B2
Filing date	Oct 12, 2018
Priority date	Oct 12, 2017
Publication date	Oct 4, 2022
Grant date	Oct 4, 2022

Abstract

Disclosed is a gasification unit (1) for producing a product gas. The gasification unit (1) comprises a co-current or counterflow pyrolysis unit (2) including a pyrolysis gas outlet (3) arranged at an upper part (4) of the pyrolysis unit (2) and a pyrolysis gas inlet (5) arranged at a lower part (6) of the pyrolysis unit (2). The gasification unit (1) further comprises a co-current or counterflow gasifier (7) including a product gas outlet (8) arranged at an upper part (9) of the gasifier (7) and a gasifier inlet (10) arranged at a lower part of the gasifier (7) and coke moving means (12) for allowing pyrolyzed coke (13) to move from the pyrolysis unit (2) to the gasifier (7). The gasification unit (1) also comprises recycling means (14) arranged to guide at least a part of the pyrolysis gas produced in the pyrolysis unit (2) from the pyrolysis gas outlet (3) and back to the pyrolysis gas inlet (5) and heating device (15) comprising an input conduit (16) arranged to guide pyrolysis gas from the pyrolysis gas outlet (3) to a combustion unit (17) in the heating device (15), wherein the combustion unit (17) is arranged to least a partially oxidize the pyrolysis gas from the pyrolysis unit (2), and wherein the heating device (15) comprises an output conduit (18) arranged to guide heating gas generated by the partial oxidization in the combustion unit (17) to the gasifier inlet (10), where in the heating device (15) is arranged external to the pyrolysis unit (2) and the gasifier (7) and wherein said gasification unit (1) further comprises heat exchange means (19) arranged for heating at least a portion of the pyrolysis gas before it enters the pyrolysis unit (2) through said pyrolysis gas inlet (5) by means of at least a part of the product gas exiting said gasifier (7) through said product gas outlet (8). Furthermore, a method for producing a product gas in a gasification unit (1) and use of such a method is disclosed.

First claim

The invention claimed is:

1. A gasification unit for producing a product gas, said gasification unit comprising,
a co-current or counterflow pyrolysis unit comprising a pyrolysis gas outlet arranged at an upper part of said pyrolysis unit and a pyrolysis gas inlet arranged at a lower part of said pyrolysis unit,
a co-current or counterflow gasifier comprising a product gas outlet arranged at an upper part of said gasifier and a gasifier inlet arranged at a lower part of said gasifier,
a coke mover for allowing pyrolyzed coke to move from said pyrolysis unit to said gasifier,
a recycler arranged to guide at least a part of the pyrolysis gas produced in said pyrolysis unit from said pyrolysis gas outlet and back to said pyrolysis gas inlet as recycled pyrolysis gas, and
a heating device comprising an input conduit arranged to guide pyrolysis gas from said pyrolysis gas outlet to a combustion unit in said heating device, wherein said combustion unit is arranged to at least partially oxidize said pyrolysis gas from said pyrolysis unit, and wherein said heating device comprises an output conduit arranged to guide heating gas generated by said partial oxidization in said combustion unit to said gasifier inlet,
wherein said heating device is arranged external to said pyrolysis unit and said gasifier and wherein said gasification unit further comprises a heat exchanger arranged for heating at least a portion of said recycled pyrolysis gas passing through said recycler before it reenters said pyrolysis unit through said pyrolysis gas inlet by at least a part of the product gas exiting said gasifier through said product gas outlet and wherein said recycler is arranged to guide said recycled pyrolysis gas from said pyrolysis gas outlet and back to said pyrolysis gas inlet without said recycled pyrolysis gas passing through said combustion unit in said heating device.

2. A gasification unit according to claim 1 , wherein said pyrolysis gas is heated by said product gas in the heat exchanger.

3. A gasification unit according to claim 1 , wherein said pyrolysis gas is heated in a first heat exchanger and said product gas delivers heat in a second heat exchanger and wherein a separate fluid flow ensures heat transfer between said first and said second heat exchangers.

4. A gasification unit claim 1 , wherein said heat exchanger comprises at least one plate heat exchanger.

5. A gasification unit claim 1 , wherein said gasification unit comprises a cooler for cooling said heating gas to a temperature between 600° C. and 1,200° C., preferably between 700° C. and 1,100° C. and most preferred between 800° C. and 1,000° C. before it enters said gasifier.

6. A gasification unit according to claim 5 , wherein said cooler adds steam to said heating gas and/or adds product gas to said heating gas to cool said heating gas.

7. A gasification unit claim 1 , wherein said co-current or counterflow pyrolysis unit is arranged on top of said co-current or counterflow gasifier.

8. A gasification unit claim 1 , wherein said coke mover comprises a screw conveyor.

9. A method for producing a product gas in a gasification unit, said method comprising the steps of:
feeding fuel to a co-current or counterflow pyrolysis unit,
circulating at least a part of the pyrolysis gas produced by said fuel in said pyrolysis unit directly back into said pyrolysis unit as recycled pyrolysis gas to form a flow of recycled pyrolysis gas up through said fuel,
heating at a heating device said pyrolysis gas before it re-enters said pyrolysis unit,
pyrolyzing said fuel by said re-entering heated pyrolysis gas,
enabling that said pyrolyzed fuel in said pyrolysis unit is moved to a gasifier,
combusting at a combustion unit in the heating device, at least a part of said pyrolysis gas outside said pyrolysis unit and said gasifier to form heating gas, and
guiding said heating gas into said gasifier to heat said pyrolyzed fuel to produce a product gas, wherein said recycled pyrolysis gas is heated by said product gas before said pyrolysis gas re-enters said pyrolysis unit;
wherein said recycled pyrolysis gas is guided from said pyrolysis gas outlet and back to a pyrolysis gas inlet without said recycled pyrolysis gas passing through the combustion unit in the heating device.

10. A method according to claim 9 , wherein said pyrolysis gas is heated by said product gas by guiding said pyrolysis gas and said product gas through the heat exchanger.

11. A method according to claim 9 , wherein said pyrolysis gas is heated by said product gas by guiding said pyrolysis gas through a first heat exchanger and guiding said product gas through second heat exchanger and establish a separate fluid flow between said first and said second heat exchangers to transfer heat between said first and said second heat exchangers.

12. A method according to claim 9 , wherein between 1% and 95%, preferably between 5% and 70% and most preferred between 10% and 50% of the pyrolysis gas produced by said fuel in said pyrolysis unit is circulated back into said pyrolysis unit to form a flow of pyrolysis gas up through said fuel.

13. Use of a method according to claim 9 for producing a product gas from biomass in a gasification unit.

Assignees

• Univ Danmarks Tekniske

Inventors

• Gadsbøl Rasmus Østergaard
• Henriksen Ulrik Birk
• Ahrenfeldt Jesper

Classifications

• C10J2300/0916

  Biomass · CPC title

• C10J3/36 Primary

  Fixed grates · CPC title

• C10J2300/1807

  Recycle loops, e.g. gas, solids, heating medium, water · CPC title

• C10J2200/158

  Screws · CPC title

• C10J3/66 Primary

  by introducing them into the gasification zone · CPC title