Solids circulation system and method for capture and conversion of reactive solids with fluidized bed temperature control

Patent metadata

Field	Value
Publication number	US-2017051217-A1
Application number	US-201615347079-A
Country	US
Kind code	A1
Filing date	Nov 9, 2016
Priority date	Nov 5, 2010
Publication date	Feb 23, 2017
Grant date	—

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) 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; (b) a second conduit ( 612 ) connected to the first conduit ( 602 ), the second conduit ( 612 ) configured to receive a portion of said syngas stream ( 600 ) as a first-stage product gas stream ( 610 ); (c) a second reactor ( 100 ) having a fluidized bed and configured to receive char from the syngas stream ( 600 ) and an oxygen containing gas, the second reactor configured to operate under conditions sufficient to convert the char into a second-stage product gas stream ( 910 ) containing at least carbon monoxide; and (d) a cooling pipe ( 180 ) protruding into the fluidized bed in the second reactor ( 100 ) to control bed operating temperature, the cooling pipe being connected to a source of elevated pressure steam as a coolant; wherein: the second reactor and the second conduit ( 612 ) are connected such that the second-stage product gas stream ( 910 ) is merged with the first-stage product gas stream ( 610 ) to form the final product gas stream ( 950 ); and the second reactor is configured to operate such that the cooling pipe superheats the elevated pressure steam.

2 . The system according to claim 1 , further comprising:
a restriction orifice ( 660 ) configured to reduce a pressure of said first-stage product gas stream ( 610 ), prior to being merged with the second-stage product gas stream ( 910 ).

3 . The system according to claim 2 , further comprising:
a first cyclone ( 300 ) configured to receive the syngas stream ( 600 ) via the first conduit ( 602 ); wherein: the second conduit ( 612 ) is connected to the first conduit ( 602 ) via the first cyclone ( 300 ); and the restriction orifice ( 660 ) is placed downstream of the first cyclone ( 300 ).

4 . The system according to claim 3 , further comprising:
a second cyclone ( 700 ) having an input connected to a freeboard region ( 160 ) of the second reactor ( 100 ); and a third cyclone ( 900 ) configured to receive a solids-laden second-stage product gas ( 710 ) from the second cyclone ( 700 ) and output the second-stage product gas stream ( 910 ); wherein: the third cyclone ( 900 ) is connected to the second conduit ( 612 ) such that the second-stage product gas stream ( 910 ) is merged with the first-stage product gas stream ( 610 ) to form the final product gas stream ( 950 ).

5 . The system according to claim 4 , wherein:
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 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 a 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 are circumferentially spaced apart from one another 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 ( 100 ) 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 11 , 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 . The system according to claim 1 , further comprising:
at least one heating conduit ( 170 ) protruding into the second reactor to heat the fluidized bed, upon startup.

14 . The system according to claim 1 , wherein:
the fluidized bed in the second reactor ( 100 ) contains hollow engineered particles, the hollow engineered particles being one or more from the group consisting of alumina, zirconia, sand, olivine sand, limestone, dolomite and metal catalyst.

15 . The system according to claim 14 , wherein:
bed material in the fluidized bed of the second reactor has a bulk density ranging from about 10 pounds per cubic foot to about 60 pounds per cubic foot.

16 . A method of processing a carbonaceous feedstock to create a final product gas stream, comprising:
(a) introducing a carbonaceous feedstock and steam into a first reactor having a fluidized bed; (b) reacting the carbonaceous feedstock and steam to thereby produce a syngas stream comprising syngas, char, condensable organic compounds and aromatic hydrocarbons; (c) separating out a first stage product gas stream from the syngas stream; (d) introducing char from the syngas gas stream and an oxygen containing gas, into a second reactor, said second reactor having a fluidized bed containing bed solids; (e) operating the second reactor under conditions sufficient to convert the char introduced into the second reactor to produce a second-stage product gas stream containing at least carbon monoxide; (f) controlling the temperature of bed solids in the second reactor by introducing elevated pressure steam into at least one cooling pipe protruding into the bed solids of the second reactor; and (g) combining said first-stage product gas stream and said second-stage product gas stream to form the final product gas stream.

17 . The method according to claim 16 , comprising:
operating the second reactor at a temperature of about 650° C. to about 1,200° C.,

Assignees

• Thermochem Recovery Int Inc

Inventors

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

Classifications

• C01B3/02

  Production of hydrogen; Production of gaseous mixtures containing hydrogen · CPC title

• C10J2300/1807

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

• C10J2300/1246

  by external or indirect heating · CPC title

• C10J2300/0976

  as steam · CPC title

• C10J2300/0959

  Oxygen · CPC title