Injector grid with two stage mixer

Patent metadata

Field	Value
Publication number	US-9649604-B2
Application number	US-201313850459-A
Country	US
Kind code	B2
Filing date	Mar 26, 2013
Priority date	May 10, 2012
Publication date	May 16, 2017
Grant date	May 16, 2017

Abstract

An injector mixer arrangement ( 10 ) for supplying a reducing agent in gaseous form into a flue gas flowing in a gas duct ( 14 ) communicating with a catalyst ( 18 a ) in a selective catalytic reduction (SCR) reactor ( 12 ) arranged downstream of said injector mixer arrangement ( 10 ). The injector mixer arrangement ( 10 ) comprises an injector grid ( 22 ) equipped with a plurality of nozzles ( 30 ) arranged horizontally within the gas duct ( 14 ). The nozzles ( 30 ) are adapted to supply said reducing agent to the gas duct ( 14 ). The injector mixer arrangement ( 10 ) further comprises first stage mixer plates ( 24 ) and second stage mixer plates ( 26 ) arranged in the gas duct ( 14 ) downstream of said nozzles ( 30 ) and upstream of SCR reactor 12.

First claim

The invention claimed is:

1. An injector mixer arrangement comprising:
a plurality of nozzles arranged on an upper surface and periphery side portions of an injector grid of a square or rectangular configuration arranged within a gas duct perpendicular to flue gas flow operable to supply reducing agent to the gas duct upstream of a catalyst arranged in a selective catalytic reduction reactor in communication with the gas duct;
a plurality of trapezoidal first stage mixer plates directly adjoined one to another at non-parallel sides forming a square or rectangular configuration arranged in the gas duct downstream of said nozzles, with the plurality of adjoined first stage mixer plates forming the square or rectangular configuration aligned with the square or rectangular configuration of the periphery side portions of the injector grid and the plurality of nozzles arranged on the periphery side portions of the injector grid, with exterior surfaces of the plurality of adjoined trapezoidal first stage mixer plates forming an angle of 25 to 55 degrees with respect to planar walls forming the gas duct; and
a plurality of non-adjoined second stage mixer plates arranged in the gas duct downstream of said adjoined trapezoidal first stage mixer plates, wherein each non-adjoined second stage mixer plate generates two vortices operative for intermixing a flue gas and the reducing agent within the gas duct prior to intermixed flue gas and reducing agent contact with the catalyst in the selective catalytic reduction reactor.

2. The injector mixer arrangement of claim 1 , wherein an upper surface of said injector grid is a distance of approximately 0.1 to 1 meter from an interior edge of the first stage mixer plates.

3. The injector mixer arrangement of claim 1 , wherein each first stage mixer plate and each second stage mixer plate has a trapezoidal geometry.

4. The injector mixer arrangement of claim 1 , wherein exterior edges of the first stage mixer plates are a distance of approximately 1 to 2 meters from minor parallel edges of the second stage mixer plates.

5. The injector mixer arrangement of claim 1 , wherein the plurality of nozzles arranged on the injection grid over a cross section of the gas duct provides at least one nozzle with at least one first stage mixer plate of the plurality of first stage mixer plates and at least one second stage mixer plate of the plurality of second stage mixer plates arranged in a downstream reducing agent flow from the at least one nozzle.

6. The injector mixer arrangement of claim 5 , wherein interior edges of the adjoined first stage mixing plates are relatively shorter than exterior edges of the adjoined first stage mixing plates and the interior edges of the adjoined first stage mixing plates are arranged within the gas duct in closer proximity to the injection grid than are the exterior edges of the adjoined first stage mixing plates.

7. The injector mixer arrangement of claim 1 , wherein each second stage mixing plate is arranged at an angle within the gas duct in vertical arrangement, and the plurality of second stage mixing plates occupies 30-50% of a horizontal cross sectional area of the vertically arranged gas duct.

8. The injector mixer arrangement of claim 1 , wherein interior edges of the adjoined first stage mixing plates are relatively shorter than exterior edges of the adjoined first stage mixing plates arranged within the gas duct at a turbulence inducing angle of 25-55 degrees with respect to a plane parallel to walls of the gas duct in vertical arrangement.

9. The injector mixer arrangement of claim 1 , wherein
the reducing agent is ammonia or urea supplied in gaseous form.

10. The injector mixer arrangement of claim 1 , wherein the second stage mixer plates are trapezoidal in form and generate oppositely rotating vortices operative for mixing flue gas and reducing agent flowing in the gas duct.

Assignees

• Alstom Technology Ltd
• General Electric Technology Gmbh

Inventors

• Tabikh Ali Mustapha
• Tu Haitao

Classifications

• B01F5/0619

  Operations & Transport · mapped topic

• B01D2257/404

  Nitrogen oxides other than dinitrogen oxide · CPC title

• B01D2251/206

  Ammonium compounds · CPC title

• F23J15/003 Primary

  for supplying chemicals to fumes, e.g. using injection devices · CPC title

• B01F5/0057 Primary

  Operations & Transport · mapped topic