Process for mixing gas jets or streams

• US 5,560,710 A
• Filed: 05/18/1992
• Issued: 10/01/1996
• Est. Priority Date: 12/23/1988
• Status: Expired due to Term

• Current Assignee: Gaswarme Institut EV, Thyssengas GmbH
• Original Assignee: Gaswarme Institut EV, Thyssengas GmbH
• Inventors: Simon, Horst, Klocke, Bernhard
• Primary Examiner(s): Stinson, Frankie L.
• Application Number:
  US07/887,237
• Time in Patent Office: 1,597 Days
• Field of Search: 237/8, 237/543, 366/336, 366/101, 366/337, 366/348, 431/10, 431/185, 431/9, 431/115, 431/116, 423/235, 423/239, 110/345, 208/120
• US Class Current: 366/336
• CPC Class Codes: B01D 2251/208 Hydrocarbons
• CPC Class Codes: B01D 53/56 Nitrogen oxides B01D53/60 takes precedence
• CPC Class Codes: B01F 25/3142 the conduit having a plurality of openings in the axial direction or in the circumferential direction

Abstract

In a process for continuously mixing streams of at least two fluid media, in particular for use in reburning or progressive combustion and for secondary NO.sub.χ -reduction in flue gases from industrial furnace plants an auxiliary gas stream is injected into a main gas stream by means of swirl-momentum nozzles which impart a characteristic axial impulse and an angular impulse to the fluid.

Claims

1. A process for reducing nitrogen oxides contained in flue gases of furnace installations, comprising the steps of:

returning a partial flow of the flue gases;

mixing the partial flow of the flue gases with hydrocarbons as reduction agents so as to increase the impulse of the reduction agents;

providing the partial flow with an angular momentum having a theoretical swirl number (a ratio of the swirl-momentum flow, normalized with the nozzle radius, to the axial impulse flow) of from 0.4 to 0.5, which ensures after injection, an intensive mixing with a flue gas flow; and

injecting the partial flow counter to the flue gas flow at an angle of 10°

to 80°

.

2. A process according to claim 1, wherein the injecting step includes injecting the partial flow at an injection angle having a theoretical angle number (a ratio of angular momentum flow, normalized with the nozzle radius, to axial impulse flow) that is from 0.4 to 5 times a critical angle number.

3. A process according to claim 1 wherein several sub-streams of auxiliary gas are injected into the main gas stream.

4. A process according to claim 3 wherein the sub-streams are injected into the main stream with different directions of flow.

5. A process according to claim 3 wherein the directions of at least some of the streams run counter to one another.

6. A process according to claim 3 wherein the sub-streams are injected in at least one plane.

7. A process according to claim 1 wherein the auxiliary gas stream is injected at an elevated temperature.

8. A process according to claim 7 wherein the mass flow ratio is adjustable.

9. A process according to claim 1 wherein the flue gas flow and the partial gas flow, per nozzle, have a mass flow ratio from 20 to 120.

10. A process according to claim 1 wherein a ratio of main gas flow to auxiliary gas flow per nozzle forms a momentum stream ratio of from 1 to 10.

11. A process according to claim 1 wherein a momentum stream ratio of main gas flow to auxiliary gas flow per nozzle is adjustable.

12. A process according to claim 1 wherein the mixing ratio of hydrocarbon to flue gas is from 1:

5 to 1;

40.

13. A process according to claim 1 wherein the mixing ratio of hydrocarbon to flue gas is adjustable.

14. A process according to claim 1 wherein at least one of the main gas temperature and the auxiliary gas temperature is within the respective ranges of from 300°

C. to 1200°

C. for the main gas temperature and from 100°

C. to 400°

C. for the auxiliary gas temperature.

15. A device for reducing nitrogen oxides contained in flue gases of furnace installations, comprising:

means for returning a partial flow of the flue gases;

means for mixing the partial flow of the flue gases with hydrocarbons as reduction agents; and

nozzle means for providing the partial flow with an angular momentum, said nozzle means including swirl plates for injecting the partial flow counter to a flue gas flow at an injection angle of 10°

to 80°

.

16. A nozzle according to claim 15 wherein the swirl plates comprise axial vanes inclined at an angle of from 10°

to 80°

to a longitudinal axis of a pipe of the nozzle means.

17. A device for reducing nitrogen oxides contained in flue gases of furnace installations, comprising:

means for returning a partial flow of the flue gases;

means for mixing the partial flow of the flue gases with hydrocarbons as reduction agents; and

nozzle means for providing the partial flow with an angular momentum and for injecting the partial flow counter to the flue gas flow at an injection angle of 10°

to 80°

, said nozzle means including a plurality of nozzles distributed around the periphery of a flue gas passage.

18. A device according to claim 17 wherein the nozzles are arranged in different planes extending at right angles to the axis of the passage.

19. A device according to claim 17 wherein at least some of the nozzles are at different angles counter to the direction of the main stream.