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

Patent metadata

Field	Value
Publication number	US-2020239792-A1
Application number	US-201816652621-A
Country	US
Kind code	A1
Filing date	Oct 12, 2018
Priority date	Oct 12, 2017
Publication date	Jul 30, 2020
Grant date	—

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

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 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, coke moving means for allowing pyrolyzed coke to move from said pyrolysis unit to said gasifier, recycling means 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, 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 least a 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 heat exchange means arranged for heating at least a portion of said pyrolysis gas before it enters said pyrolysis unit through said pyrolysis gas inlet by means of at least a part of the product gas exiting said gasifier through said product gas outlet.

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

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

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

5 . A gasification unit claim 1 , wherein said gasification unit comprises cooling means 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 cooling means comprises means for adding steam to said heating gas and/or adding 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 moving means 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 back into said pyrolysis unit to form a flow of pyrolysis gas up through said fuel, heating said pyrolysis gas before it re-enters said pyrolysis unit pyrolyzing said fuel by means of said re-entering heated pyrolysis gas enabling that said pyrolyzed fuel in said pyrolysis unit is moved to a gasifier combusting at least a part of said pyrolysis gas outside said pyrolysis unit and said gasifier to form heating gas, guiding said heating gas into said gasifier to heat said pyrolyzed fuel to produce a product gas, wherein said pyrolysis gas is heated by means of said product gas before said pyrolysis gas re-enters said pyrolysis unit.

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

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

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

• C10J2200/158

  Screws · CPC title

• C10J3/36 Primary

  Fixed grates · CPC title

• C10J2300/1807

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

• C10J3/66 Primary

  by introducing them into the gasification zone · CPC title

• C10J2300/1884

  with one stream being synthesis gas · CPC title