A method is provided for reducing NOx in a combustion exhaust gas stream from a boiler. The method includes the steps of converting an aqueous solution of urea to ammonia by heating the urea solution to a temperature of 350°-650° F. in an injection lance system. The urea solution is pressurized to the pressure required to keep urea reaction products in the liquid phase and is contacted for a selected time with a conversion catalyst selected from the group of metals, metal oxides, or metal compounds consisting of chromium or molybdenum to provide a converted urea solution. The converted urea solution is injected from the injection lance system into the combustion exhaust gas for reducing NOx.

Method for converting urea to ammonia

The present invention relates to a process for reducing nitrogen oxides emissions from a diesel engine, which comprises preparing an emulsion of an aqueous urea solution in diesel fuel, and supplying said emulsion to a diesel engine for combusting therein, whereby combustion of the emulsion leads to a reduction in the nitrogen oxides emissions from the diesel engine when compared with combustion of diesel fuel alone.

Reduction of nitrogen oxides emissions from diesel engines

Methods are provided for decreasing the amount of nitrogen oxides released to the atmosphere as a component of combustion emissions. The methods are carried out by forming a combustion flue gas (34) in a combustion zone (22), the combustion flue gas (34) including nitrogen oxides, injecting overfire air and droplets of a solution or a powder of a selective reducing agent (38) into a burnout zone (24), and contacting the combustion flue gas (34) with the overfire air and the selective reducing agent (38) in the burnout zone (24) to thereby decrease the concentration of nitrogen oxides therein. The selective reducing agent is provided in an aqueous solution or powder which is injected into the overfire air in optimized droplet or particle form prior to or concurrently with injection of the overfire air into the burnout zone (24).

Method of reducing nox in a combustion flue gas

The invention presented is an injection apparatus (10) for distributing chemical agents into the effluent from the combustion of a carbonaceous fuel. The apparatus (10) permits relatively uniform distribution of the chemical agents throughout the effluent even in confined areas of the boiler where impingement on boiler walls or heat exchange tubes is undesirable.

Lance-type injection apparatus for introducing chemical agents into flue gases

An aqueous urea dosing system has a first tube through which the urea solution is conveyed to a small mixing chamber. Compressed air is continuously conveyed through an annular space between the outer surface of the first tube and the inner surface of a second tube which has a distal end that extends beyond a distal end of the first tube. The mixing chamber is positioned between the respective distal ends of the first and second tubes. The urea solution is discharged into the small mixing chamber, and subsequently immediately into an exhaust gas, in a series of discreet pulses, the width and period of which are controlled by a pulse-width-modulated flow control valve spaced from the exhaust gas.

System and method for dispensing an aqueous urea solution into an exhaust gas stream

A process and apparatus for reducing the concentration of pollutants in an effluent from the combustion of a fuel or waste material is presented The process and apparatus enables injection of an effluent treatment fluid at low treatment fluid flow rates yet provides an even dispersion of treatment fluid within an effluent passage with little or no clogging An atomization conduit, (40) positioned coaxially within a treatment fluid supply conduit, (30) extends into the effluent and supplies an atomization fluid, such as steam or air A treatment fluid is supplied through a supply conduit (30) and through at least one jet (42) in the atomization conduit wall (40) at a velocity of between 2 and 60 feet per second, causing atomization of the treatment fluid within the nozzle

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

A process and apparatus for reducing the concentration of pollutants in an effluent from the combustion of a fuel or waste material is presented. The process and apparatus enables injection of an effluent treatment fluid at low treatment fluid flow rates yet provides an even dispersion of treatment fluid within an effluent passage with little or no clogging. An atomization conduit, positioned coaxially within a treatment fluid supply conduit, extends into the effluent and supplies an atomization fluid, such as steam or air. A treatment fluid is supplied through a supply conduit and through at least one jet in the atomization conduit wall at a velocity of between 2-60 feet per second, causing atomization of the treatment fluid within the nozzle.

Vincent A. Devita

Papers

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

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