Fluidized bed gasification process with reduction of fines entrainment by utilizing a separate transfer line burner stage

Claim 2

IN A PROCESS FOR THE PREPARATION OF A PRODUCT GAS BY REACTING STEAM WITH CARBONACEOUS SOLIDS IN A FLUDIZED BED REACTION ZONE WHEREIN SAID PRODUCT GAS IS TAKEN OFF OVERHEAD FROM SAID REACTION ZONE AND WHEREIN A STREAM OF SOLID CARBONACEOUS PARTICLE IN CONTINUOUSLY WITHDRAWN FROM THE SAID REACTION ZONE AND HEATED BY CONTACTING SAID PARTICLES WITH AN OXYGEN-CONTAINING GAS IN A TRANSFER LINER BURNER THE IMPROVEMENT WHICH COMPRISES SEPARAATING SOLID FINES FROM SAID PRODUCT GAS INTRODUCING SAID FINES INTO SAID TRANSFER LINE BURNER FOR COMBUSTING SAID FINES WITH SAID OXYGEN-CONTAINING GAS WHILE IN THE PRESENCE OF SAID STREAM OF CARBONACEOUS PARTICLES TO HEAT SAID CARBONACEOUS PARTICLES, AND THEREAFTER RETURNING THE HEATED CARBONACEOUS PARTICLES FROM SAID TRANSFER LINE BURNER TO SAID REACTION ZONE.

Claim 3

A process as defined by claim 1 including the additional steps of withdrawing gaseous combustion products from said transfer line burner, separating solid fines from said combustion products, and introducing the separated fines from said combustion products into said transfer line burner for combusting with said oxygen-containing gas in the presence of said stream of solid carbonaceous particles.

Claim 4

A process as defined by claim 1 wherein said fines separated from said product gas are injected into said stream of carbonaceous particles withdrawn from said reaction zone and said stream of solid particles containing said fines is then introduced into said transfer line burner.

Claim 5

A process as defined by claim 1 wherein said carbonaceous particles are coal char particles.

Claim 6

A process as defined by claim 1 wherein said reaction zone comprises a gasifier including an upper hydrogasification zone in which coal particles are carbonized and a lower steam gasification zone from which said stream of carbonaceous particles is withdrawn and to which said heated carbonaceous particles are returned.

Claim 7

A process as defined by claim 1 wherein said oxygen-containing gas is air.

Claim 8

A process as defined by claim 2 wherein said fines separated from said product gas and said fines separated from said combustion products are separately introduced into said transfer line burner.

Claim 9

A process as defined by claim 2 wherein said fines are separated from said combustion products in a plurality of stages.

Claim 10

A process as defined by claim 2 including the further steps of separating additional fines from said combustion products and cooling said additional fines in a heat exchanger.

Claim 11

A process as defined by claim 2 wherein at least part of said fines separated from said combustion products are entrained in a carrier gas before being introduced into said transfer line burner.

Claim 12

A process as defined by claim 2 including the further steps of separating additional fines from said combustion products and withdrawing part of said additional fines as ash.

Claim 13

A process as defined by claim 10 wherein said carrier gas is flue gas.

Claim 14

A process for the manufacture of a methane-rich gas from a sub-bituminous or higher grade coal which comprises: a. introducing finely divided particles of said coal and steam into a fluidized bed reaction vessel maintained at a temperature in the range of from about 1,450* to about 1,750* F. and a pressure in the range of from about 50 to about 1,000 psig, said vessel containing an upper hydrogasification zone and a lower steam gasification zone; b. withdrawing a methane-rich gas overhead from said fluidized bed reaction vessel and removing particulate solids less than about 5 microns in diameter from said methane-rich gas; c. withdrawing char particles from said steam gasification zone of said fluidized bed reaction vessel; d. passing said particulate solids and said char particles to a transfer line burner; e. introducing sufficient oxygen-containing gas into said transfer line burner to burn a portion of said particulate solids and heat said char particles to a temperature in the range between about 1,500* and about 1,950* F.; and f. recycling the heated char particles to said steam gasification zone in said fluidized bed reaction vessel.

Claim 15

A process for the manufacture of a methane-rich gas from a sub-bituminous or higher grade coal which comprises: a. introducing finely divided particles of said coal and steam into a fluidized bed reaction vessel maintained at a temperature in the range of from about 1,450* to about 1,750* F. and a pressure in the range of from about 50 to about 1,000 psig, said vessel containing an upper hydrogasification zone and a lower steam gasification zone; b. withdrawing a methane-rich gas overhead from said fluidized bed reaction vessel and removing particulate solids less than about 5 microns in diameter from said methane-rich gas; c. withdrawing char particles from said steam gasification zone of said fluidized bed reaction vessel; d. passing said particulate solids and said char particles to a transfer line burner; e. introducing sufficient oxygen-containing gas into said transfer line burner to burn a portion of said particulate solids and heat said char particles to a temperature in the range between about 1,500* and about 1,950* F.; and f. recycling the heated char particles to said steam gasification zone in said fluidized bed reaction vessel.

Claim 16

A process as defined by claim 13 including the additional steps of: g. withdrawing gaseous combustion products from said transfer line burner; h. separating entrained fines from said gaseous combustion products; and i. recycling at least a part of the separated fines to said transfer line burner.

Claim 17

A process as defined by claim 13 wherein said finely-divided coal particles and said steam are introduced into said fluidized bed reaction vessel in a ratio of from about 0.5 to about 2.0 pounds of steam per pound of coal.

Claim 18

A prOcess as defined by claim 13 wherein said finely-divided coal particles are less than about one-eighth inch in diameter.

Claim 19

A process as defined by claim 14 wherein said entrained fines are separated from said gaseous combustion products in two stages, the coarser fines being removed in a first stage and recycled to said transfer line burner and the smaller, lighter fines being removed in a second stage and withdrawn as ash.

Claim 20

A process as defined by claim 17 including the additional step of recovering heat from said smaller, lighter fines.