Process and injector for reducing the concentration of pollutants in an effluent

Claim 1

A multistage process for reducing the concentration of nitrogen oxides in an effluent passage containing effluent from the combustion of carbonaceous material in a boiler, using in a second stage an injector including an atomization conduit and a supply conduit, said atomization conduit having an inner diameter and an injector nozzle at one end positioned in said effluent passage, said supply conduit being operably connected with said atomization conduit by at least one jet penetrating the wall of said atomization conduit upstream of said nozzle; the process comprising: (a) in a first stage, injecting a first treatment fluid comprising urea, ammonia or a nitrogenated hydrocarbon or mixtures thereof into the effluent at a first temperature zone when the effluent is at a temperature of about 1350° F. to about 2200° F.; and (b) in a second stage, injecting a second treatment fluid comprising a hydrocarbon into the effluent at a second temperature zone when the effluent is at a temperature of about 800° F. to about 1400° F., wherein said step of injecting a second treatment fluid comprises supplying said second treatment fluid in an amount effective to reduce pollutants in said effluent through said supply conduit and through said at least one jet into said atomization conduit at a velocity of between about two to about sixty feet per second at a distance upstream of said nozzle of up to about thirty-two times the inner diameter of said atomization conduit; simultaneously supplying an atomization fluid through said atomization conduit to contact said second treatment fluid and inject said second treatment fluid into said effluent passage.