Process and device for treating furnace gas

Abstract

A process and a device for treating a flow of furnace gas with a pressure of more than 1 bar flowing through a channel. A powder agent, such as a powder comprising alkali reagents, such as lime, and/or absorbents, such as activated coal, is injected under an overpressure into the furnace gas flow via an injector which is positioned centrally within the channel. The powder agent may be fluidized. The pressure for injecting the powder may be adjusted by controlling the volume of fluidization gas vented via a venting outlet.

Claims

1. A process for treating a flow of furnace gas with a pressure of more than 1 bar flowing through a channel, wherein a powder agent is injected into the furnace gas flow, wherein the powder agent is first fluidized in a fluidized bed and then added to the furnace gas flow via an injector which is positioned centrally within the channel, and wherein an injection velocity of the powder agent is adjusted by controlling a volume of fluidization gas vented via a venting outlet.

2. The process of claim 1, wherein the powder agent is radially injected into the furnace gas flow.

3. The process of claim 1, wherein the powder agent comprises one or more absorbents.

4. The process of claim 1, wherein the furnace gas flow is subsequently filtered.

5. The process of claim 1, wherein the powder agent comprises one or more alkaline components.

6. The process of claim 5, wherein the powder agent comprises one or more absorbents.

7. The process of claim 1, wherein the powder agent is injected under an overpressure into the furnace gas flow.

8. A device for treating a flow of furnace gas, the device comprising: a flow channel and an injector centrally arranged within the flow channel and provided with radially directed outlets, the injector comprising a chamber configured to contain a fluidized bed of a powder agent with a supply for a fluidizing gas configured to blow the powder agent via the radially directed outlets into the furnace gas flow; and a vent connecting the chamber to a fluidizing gas discharge outside the flow channel, wherein the vent is adjustable to control an injection velocity of the powder agent when it is injected into the furnace gas flow.

9. The device of claim 8, wherein the supply for the fluidizing gas comprises at least one gas permeable conduit.

10. The device of claim 9, wherein the at least one gas permeable conduit extends over a width and/or length of the fluidizing bed.

11. The device of claim 9, wherein the at least one gas permeable conduit is of a sintered metal.

12. The device of claim 9, wherein the at least one gas permeable conduit is retractable.

13. The device of claim 9, wherein the at least one gas permeable conduit is a filter mesh metal.

14. The device of any one of claim 8, comprising a downstream conical section extending in a flow direction from the radially directed outlets.

15. The device of any one of claim 8, comprising an upstream conical section extending from the radially directed outlets in a direction opposite to a flow direction.

16. The device of claim 8, wherein the injector is configured to blow the powder agent via the radially directed outlets into the furnace gas flow with an overpressure of at least 10 mbar relative to a pressure in the furnace gas flow.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Aspects of the invention will be explained with reference to the accompanying drawing, showing an exemplary embodiment.

(2) FIG. 1: shows a device for treating blast furnace gas in longitudinal cross section.

DETAILED DESCRIPTION OF THE ILLUSTRATIVE EMBODIMENT

(3) FIG. 1 shows a device 1 for treating a flow of blast furnace gas by injecting a dry powder agent 2 containing absorbent material, such as active carbon, and an alkaline agent, such as lime. The device 1 comprises a flow channel 3 defining a blast furnace gas flow path with a flow direction A. The channel 3 has a channel wall 4, typically a cylindrical channel wall. An injector 6 is arranged centrally within the flow channel 3. To show the injector 6, part of the wall 4 is broken away in FIG. 1. The injector 6 is provided with a ring of radially directed outlets 8. A first hollow conical section 10 of the injector 6 extends from the section with the radial outlets 8 and points downstream. A second hollow conical section 12 of the injector 6 extends in the opposite direction from the section with the radial outlets 8 and points upstream. The conical sections 10, 12 guide the blast furnace gas flow to minimize turbulence caused by the injector 6. Alternative configurations can also be used.

(4) The hollow interior of the second conical section 12 forms part of a fluidization chamber 14 containing the powder agent 2. The fluidization chamber 14 connects to an opening 16 in the channel wall 4 where the injector 6 is bolted to the channel wall by means of a flange connection 18. Outside the channel 3 the fluidization chamber 14 is extended with a section 20 connected to a powder inlet 22 for the supply of fresh powder agent, and an outlet 24 for venting fluidization gas substantially above the powder bed level in the fluidization chamber 14.

(5) The section of the chamber 14 between the conical section 12 and the channel wall 4 may have an aerodynamic cross section, e.g., pointing upwardly and pointing downwardly.

(6) A gas permeable conduit 26 of a sintered metal is positioned in a bottom section of the fluidization chamber 14 over the width and length of the fluidization chamber 14, e.g., extending from a fluidization gas inlet 28 at least to a center line of the second conical section 12.

(7) When the fluidization chamber 14 is filled with the powder agent 2, fluidization gas is blown into the fluidization chamber 14 through the powder bed. As a result the powder bed is fluidized. Powder escapes through the outlets 8 and is taken with the blast furnace gas flow A.

(8) The powder agent 2 is injected under pressure into the blast furnace gas flow A. The pressure can be adjusted by controlling the volume of the fluidization gas vented via the outlet 24.