Solids circulation system and method for capture and conversion of reactive solids

Patent metadata

Field	Value
Publication number	US-9550950-B2
Application number	US-201514657654-A
Country	US
Kind code	B2
Filing date	Mar 13, 2015
Priority date	Nov 5, 2010
Publication date	Jan 24, 2017
Grant date	Jan 24, 2017

Abstract

A solids circulation system receives a gas stream containing char or other reacting solids from a first reactor. The solids circulation system includes a cyclone configured to receive the gas stream from the first reactor, a dipleg from the cyclone to a second reactor, and a riser from the second reactor which merges with the gas stream received by the cyclone. The second reactor has a dense fluid bed and converts the received materials to gaseous products. A conveying fluid transports a portion of the bed media from the second reactor through the riser to mix with the gas stream prior to cyclone entry. The bed media helps manipulate the solids that is received by the cyclone to facilitate flow of solids down the dipleg into the second reactor. The second reactor provides additional residence time, mixing and gas-solid contact for efficient conversion of char or reacting solids.

First claim

What is claimed is:

1. A system for processing a carbonaceous feedstock to create a final product gas stream, comprising:
a first reactor ( 500 ) having a fluidized bed and configured to receive a feedstock and steam, and output a syngas stream ( 600 ) via a first conduit ( 602 ), the syngas stream ( 600 ) comprising syngas, char, condensable organic compounds and aromatic hydrocarbons;
a second conduit ( 612 ) connected to the first conduit ( 602 ), the second conduit ( 612 ) configured to receive a portion of said syngas stream ( 602 ) as a first-stage product gas stream ( 610 );
a restriction orifice ( 660 ) positioned in the second conduit ( 612 ) and configured to reduce a pressure of said first-stage product gas stream ( 610 ); and
a second reactor ( 100 ) configured to receive char from the syngas gas stream ( 600 ) and an oxygen containing gas, and operated under conditions sufficient to convert the char into a second-stage product gas stream ( 910 ); wherein:
the system is further configured to combine said first-stage product gas stream ( 610 ) and said second-stage product gas stream ( 910 ), downstream of the restriction orifice ( 660 ) to form the final product gas stream ( 950 ).

2. The system according to claim 1 , further comprising:
a cooling pipe ( 180 ) protruding into the second reactor and connected to a source of elevated pressure steam to cool bed material in the second reactor.

3. The system according to claim 1 , wherein:
the first conduit ( 602 ) is connected to the second conduit ( 612 ) via a first cyclone ( 300 );
the first conduit ( 602 ) conveys the syngas stream ( 600 ) towards the first cyclone ( 300 ); and
the first cyclone ( 300 ) conveys the first-stage product gas stream ( 610 ) toward the second conduit ( 612 ).

4. The system according to claim 3 , wherein:
a freeboard region ( 160 ) of the second reactor ( 100 ) is connected to an input of a second cyclone ( 700 );
the second cyclone ( 700 ) conveys a second-stage product gas ( 710 ) from the second reactor ( 100 ) towards a third cyclone ( 900 );
the third cyclone ( 900 ) conveys the second-stage product gas stream ( 910 ) to the second conduit ( 612 ) where the second-stage product gas stream ( 910 ) combines with the first stage product gas stream ( 610 ) form the final product gas stream ( 950 ); and
the restriction orifice ( 660 ) is downstream of the first cyclone ( 300 ) and upstream of the third cyclone ( 900 ).

5. The system according to claim 4 , wherein:
the second reactor ( 100 ) has a fluidized bed containing bed solids;
the second cyclone ( 700 ) is external to the second reactor ( 100 ); and
an output of the second cyclone ( 700 ) is connected to the second reactor ( 100 ) to recycle one or more of char and bed solids captured by the second cyclone ( 700 ).

6. The system according to claim 1 , further comprising:
a fluidized bed containing bed solids in the second reactor ( 100 )
a first riser ( 200 ) connected to the second reactor ( 100 ) and configured to convey bed solids in a direction away from the second reactor ( 100 );
a first separation device ( 300 ) connected to the first reactor ( 500 ) and to the first riser ( 200 ); and
a dipleg ( 400 ) having a first end connected to the first separation device ( 300 ) and a second end connected to the second reactor ( 100 ).

7. The system according to claim 6 , wherein:
the first riser ( 200 ) conveys the bed solids ( 120 ) towards said syngas stream ( 600 );
the first separation device ( 300 ) is configured to receive a mixture of said bed solids ( 120 ) conveyed through the first riser ( 200 ) and said syngas stream ( 600 ), and separate said mixture into an intermediate solids mixture ( 650 ) and the first-stage product gas stream ( 610 ); and
the dipleg ( 400 ) conveys the intermediate solids mixture ( 650 ) from the first separation device ( 300 ) to the dense fluid bed ( 110 ) of the second reactor ( 100 ).

8. The system according to claim 7 , further comprising:
a gas-solids flow regulator ( 2000 ) interposed between a dipleg first section ( 402 ) connected to the first separation device ( 300 ) and a dipleg second section ( 404 ) connected to the second reactor ( 100 ); wherein:
the gas-solids flow regulator ( 2000 ) is provided with a fluidization media inlet ( 2130 ) configured to receive a fluidization media.

9. The system according to claim 6 , wherein:
the dipleg ( 400 ) and the riser ( 200 ) enter the second reactor ( 100 ) at locations that circumferentially spaced apart by at least 90 degrees.

10. The system according to claim 6 , wherein:
the first riser ( 200 ) comprises a conveying fluid inlet ( 240 ) which extends into the second reactor and terminates in a conveying fluid injector ( 242 ) configured to inject a conveying fluid into a riser entrance section ( 210 , 210 a ) at a point within the second reactor ( 100 ).

11. The system according to claim 10 , wherein:
the conveying fluid injector ( 242 ) comprises a bent tip which is configured to inject conveying fluid into the riser inlet ( 250 ) at a lowermost portion of the riser entrance section.

12. The system according to claim 10 , wherein:
the first riser ( 200 ) comprises an upwardly inclined riser entrance section ( 210 ) connected to the second reactor ( 100 ) and a vertical riser pipe ( 220 ) which is angled relative to the riser entrance section; and
the conveying fluid inlet extends along the upwardly inclined riser entrance section.

13. A method of processing a carbonaceous feedstock to create a final product gas stream, comprising:
introducing a carbonaceous feedstock and steam into a first reactor having a fluidized bed;
reacting the carbonaceous feedstock and steam to thereby produce a syngas stream comprising syngas, char, condensable organic compounds and aromatic hydrocarbons;
separating out a first stage product gas stream from the syngas stream;
passing the first stage product gas stream through a restriction orifice to reduce a pressure of said first-stage product gas stream;
introducing char from the syngas gas stream, and an oxygen containing gas, into a second reactor;
operating the second reactor under conditions sufficient to convert the char introduced into the second reactor into a second-stage product gas stream; and
combining said first-stage product gas stream and said second-stage product gas stream, downstream of the restriction orifice, to form the final product gas stream.

14. The method according to claim 13 , comprising:
operating the second reactor at a temperature of about 650° C. to about 1,200° C., and in a substoichiometric mode, to convert the char into the second-stage product gas stream.

15. The method according to claim 14 , wherein the second reactor has a fluidized bed containing bed materials, the method further comprising:
controlling the temperature of the bed material in the second reactor by introducing elevated pressure steam into cooling pipes which protrude into the bed material of the second reactor, to cool said bed material.

16. The method according to claim 15 , wherein:
the fluidized bed of the first reactor is a bubbling bed type; and
the fluidized bed of the second reactor is one from the group consisting of a circulating bed type, a turbulent bed type and a bubbling bed type.

17. The method according to claim 15 , comprising monitoring a fluid bed level of the second reactor.

18. The method according to claim 13 , further comprising:
adding sorbents to the second reactor to capture sulfur contaminan

Assignees

• Thermochem Recovery Int Inc

Inventors

• Chandran Ravi
• Zenz Jonathan A
• Newport Dave G
• Whitney Hamilton Sean Michael

Classifications

• C10J2300/1892

  with one stream being water/steam · CPC title

• B01J2208/00398

  inside the reactor bed · CPC title

• C10J2300/0916

  Biomass · CPC title

• C10J2300/1625

  with solids treatment · CPC title

• B01J8/004

  by means of a nozzle · CPC title