An exhaust gas purification system for an internal combustion engine includes a dual passage portion having a first passage and a second passage which are connected in parallel to each other. In the first passage, a first catalyst constructed of lean NOx catalyst is located and further a second catalyst constructed of oxidizing catalyst or three-way catalyst is located downstream of the first catalyst. In the second passage, a third catalyst constructed of oxidizing or three-way catalyst is located. A flow switching valve is provided so as to switch the flow of exhaust gas between the first passage and the second passage. The flow switching valve is switched so that exhaust gas flows through the third catalyst when the engine is being warmed-up and flows through the first catalyst and the second catalyst after the engine has been warmed-up.

Exhaust gas purification system for an internal combustion engine

A safe, reliable SCR system for reducing NOx emissions from a lean-burn internal combustion engine utilizes urea in aqueous solution. A modular assembly is provided for mounting inside an urea reagent tank (30) which enables controlled feeding of an aqueous urea solution to an injector. The assembly includes a reagent quality sensor (152), a reagent temperature sensor (143), a reagent level sensor (154) and a pump (137).

Reducing NOx emissions from an engine by temperature-controlled urea injection for selective catalytic reduction

Reduction of nitrogen oxides in flue gases

A safe, reliable SCR system for reducing NOx emissions from an internal combustion engine hydrolyzes urea or like reagent under sufficient pressure to assure generation of ammonia, without production of solids that could foul injectors or catalysts. The heat for hydrolysis can be provided by the exhaust or an auxiliary means.

Reducing no emissions from an engine by on-demand generation of ammonia for selective catalytic reduction

The present invention is directed to a fluidic system and method for controlling the airflow to a lean premix combustor. The system and method as disclosed allow for reduced power, which results in reduced emissions, while at the same time providing excellent performance. This is accomplished through the use of fluidic means, which do not have the problems associated with hot moving parts of prior art mechanical means. Specifically, the introduction of an airflow downstream from openings in the dilution section cause a local boundary layer separation forcing air into the dilution holes.

Airflow modulation technique for low emissions combustors

A process for reducing nitrogen oxides in a combustion effluent is presented. The process involves introducing a nitrogenous treatment agent into the effluent under conditions effective to create a treated effluent having reduced nitrogen oxides concentration such that ammonia is present in the treated effluent; and then contacting the treated effluent under conditions effective to reduce the nitrogen oxides in the effluent with a nitrogen oxides reducing catalyst.

Combined catalytic/non-catalytic process for nitrogen oxides reduction

Reduction of slagging is improved by targeting slag-reducing chemicals in a furnace with the aid of computational fluid dynamic modeling. Chemical utilization and boiler maintenance are improved.

Process for increasing the effectiveness of slag and/or corrosion control chemicals for combustion units

A process and apparatus is presented for the reduction of nitrous oxide in the effluent from the combustion of a carbonaceous fuel. The process comprises raising the temperature of the effluent to a temperature of at least about 1700° F. The apparatus utilized is a heating means which is disposed in a boiler at a location where the effluent is at a temperature of less than about 1700° F.

Process and apparatus for the thermal decomposition of nitrous oxide

A process is presented for the reduction of nitrogen oxides in the effluent from the combustion of a carbonaceous fuel while reducing the generation of nitrous oxide. The process comprises introducing a treatment agent comprising ammonium carbamate into the effluent in an amount effective to substantially avoid the presence of nitrous oxide.

Process for reducing nitrogen oxides without generating nitrous oxide

A process for reducing nitrogen oxides in a combustion effluent is presented. The process involves introducing a nitrogenous treatment agent other than ammonia into the effluent to create a treated effluent having reduced nitrogen oxides concentration such that ammonia is present in the treated effluent; introducing a source of ammonia into the effluent; and contacting the treated effluent with a nitrogen oxides reducing catalyst.

William H. Sun

Papers

Combined catalytic/non-catalytic process for nitrogen oxides reduction

Process for increasing the effectiveness of slag and/or corrosion control chemicals for combustion units

Process and apparatus for the thermal decomposition of nitrous oxide

Process for reducing nitrogen oxides without generating nitrous oxide

Highly efficient hybrid process for nitrogen oxides reduction