A process for reducing nitrogen oxides in an exhaust stream, such as a vehicle exhaust stream, and apparatus for carrying out the process. The process comprises providing a first composition comprising aqueous urea, a second composition comprising ammonium carbamate and an exhaust stream comprising nitrogen oxides. A process for producing the ammonium carbamate is also provided. The second composition may be introduced into the exhaust stream (10) when the exhaust stream has a temperature below a threshold temperature and the first composition may be introduced into the exhaust stream when the exhaust stream has a temperature at or above the threshold temperature.

A flue gas denitration system includes a catalytic reactor accommodating a plurality of catalytic modules, into which a flue gas flows, and a flue gas heater provided on an upstream side of the catalytic reactor in a flow direction of the flue gas. In the flue gas denitration system, switched are a first denitration state in which the flue gas is denitrated by using the plurality of catalytic modules in the catalytic reactor and a second denitration state in which the flue gas is denitrated by using a catalytic module(s) less than those used in the first denitration state while a temperature of the flue gas flowing into the catalytic reactor is made higher than that in the first denitration state by using the flue gas heater. Thus, by making the temperature of the flue gas flowing into the catalytic reactor higher, it is possible to suppress deterioration in denitration performance in the case of using part of the plurality of catalytic modules for denitration.

Method and system for the removal of nitrogen oxides, from flue gas at low temperatures.

A nozzle including a first end and a second end. The first end includes at least a first inlet and a second inlet and the second end includes a plurality of outlets. An exterior surface extends from the first end to the second end of the nozzle. A plurality of vanes are disposed on the exterior surface and extend from the first end to the second end of the nozzle. A plurality of channels form along the exterior surface of the nozzle.

Disclosed is a system for integrally treating a composite waste gas including nitrogen oxides (NO.sub.x and N.sub.2O), chlorofluorocarbons (CFCs), hydrochlorofluorocarbons (HCFCs), hydrofluorocarbons (HFCs), and perfluorinated compounds (PFCs). The system includes a first wet processor configured to wash and adsorb dust including gases, SO.sub.x, and ash dissolved in water, a decomposing reactor configured to receive waste gas processed in the first wet processor and process nitrogen oxides (NO.sub.x and N.sub.2O), fluorocarbons (CFCs), hydrochlorofluorocarbons (HCFCs), hydrofluorocarbons (HFCs), and perfluorinated compounds (PFCs) in the waste gas, and a second wet processor configured to receive the waste gas processed in the decomposing reactor and wash and adsorb the received waste gas. The system can efficiently treat a large amount of composite waste gas.

A method for operating a flue gas purification system, comprising, in the flue gas purification system, equipped with a boiler which can burn oil fuel and coal fuel either simultaneously or switching therebetween, a denitration equipment having a reducing agent injector and a catalytic reactor, an inlet flue to guide flue gas discharged from the boiler to the denitration equipment, an outlet flue to guide flue gas discharged from the denitration equipment, a bypass flue which can guide flue gas from the inlet flue to the outlet flue so as to bypass the denitration equipment, and a bypass damper, opening the bypass damper and burning oil fuel in the boiler being in condition not yet suitable for coal combustion to allow the flue gas discharged from the boiler to dividedly flow to the denitration equipment and the bypass flue, switching the oil fuel to coal fuel when the boiler is in condition suitable for coal combustion to burn the coal fuel in the boiler, closing the bypass damper after switching the oil fuel to the coal fuel, and then injecting a reducing agent when the catalytic reactor is in condition suitable for a denitration reaction.

Disclosed is a dual pressure plant for the production of nitric acid on the basis of the oxidation of ammonia. The plant comprises a reactor configured to produce a burner gas stream; a gas cooling section configured to form a cooled burner gas; a condensation section configured to form an aqueous nitric acid condensate and an uncondensed nitrogen oxides gas stream; an absorption section configured to produce raw nitric acid and a tail gas; and a tail gas treatment system configured to form a purified tail gas. In a tail gas heating section a further heat exchanger configured to receive heat from the burner gas stream, said further heat exchanger being positioned relatively close to the reactor.

A catalyst body for an electrically heated catalyst has an electrical contacting assembly, which is arranged on the catalyst body and comprises an electrical conductor embedded in the catalyst body and extending in a longitudinal direction of the catalyst body and at least up to one end face of the catalyst body.

The present application provides a mobile selective catalyst reduction system for use at a remote location. The mobile selective catalyst reduction system may include a first trailer with an ammonia delivery system and a tempering air system mounted thereon in whole or in part and a second trailer with a selective catalyst reduction section mounted thereon in whole or in part. The ammonia delivery system, the tempering air system, and/or the selective catalyst reduction section are permanently mounted on the first trailer or the second trailer for use at the remote location.

Axial-radial flow reactor comprising a catalytic bed (1) of a hollow cylindrical shape, having a vertical axis (2), a base (5), a radial gas inlet section (3b), an axial gas inlet section (6) and a radial gas outlet section (4b), wherein the catalytic bed (1) comprises: a first cylindrical annular region (10) containing a layer of a first catalyst (A) and a layer of a second catalyst (B), the layer of the first catalyst being above the layer of the second catalyst; a second cylindrical annular region (9) coaxial to the first annular region and containing only the first catalyst (A).