A method of reducing NO.sub.x in tail gas obtained during startup of a plant for preparing nitric acid may involve heating the tail gas from a starting temperature T.sub.0, through a threshold temperature T.sub.G, to an operating temperature T.sub.B at which steady-state operation of the plant can occur (T.sub.0<T.sub.G<T.sub.B). NO.sub.x-containing tail gas may be passed through a storage medium and at least partially stored while the temperature of the tail gas is lower than the threshold temperature T.sub.G. The NO.sub.x may be released, preferably when the temperature of the tail gas has attained the threshold temperature T.sub.G. The NO.sub.x may be combined with a reducing agent in the presence of an SCR catalyst after the temperature of the tail gas has exceeded the threshold temperature T.sub.G, but not before, resulting in catalytic reduction of at least a portion of the NO.sub.x.

A thermal power generation system includes: a boiler; at least one steam turbine; a generator; a condenser; at least one low-pressure feed water; a high-pressure feed water pump; at least one high-pressure feed water heater capable of heating water pumped by the high-pressure feed water pump by utilizing extracted steam; a catalyst device including at least one kind of catalyst capable of promoting reduction reaction of nitrogen oxide and oxidation reaction of metallic mercury, the nitrogen oxide and the metallic mercury both being contained in the exhaust gas; at least one mercuric oxide removing device capable of removing mercuric oxide produced by the oxidation reaction of the metallic mercury from the exhaust gas; and an exhaust gas temperature adjustment device capable of adjusting a temperature of the exhaust gas at the catalyst device, by adjusting heating of the water by the at least one high-pressure feed water heater.

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.

An article includes a closed-environment air purification system that has a purifier through which air can be recirculated. The purifier is capable at a temperature of equal or less than 35° C. of converting hydrogen in the air to water and converting carbon monoxide in the air to carbon dioxide. The purifier has a reactor bed that includes media comprised of support particles and a metal catalyst disposed on the support particles.

Some embodiments of the present disclosure relate to a method of regenerating at least one filter medium comprising: providing at least one filter medium, wherein the at least one filter medium comprises: at least one catalyst material; and ammonium bisulfate (ABS) deposits, ammonium sulfate (AS) deposits, or any combination thereof; flowing a flue gas stream transverse to a cross-section of a filter medium, such that the flue gas stream passes through the cross section of the at least one filter medium, wherein the flue gas stream comprises: NOx compounds comprising: Nitric Oxide (NO), and Nitrogen Dioxide (NO.sub.2); and increasing an NOx removal efficiency of the at least one filter medium after removal of deposits.

A supported catalyst for decomposing an organic substance that includes a support and a catalyst particle supported on the support. The catalyst particle contains a perovskite-type composite oxide represented by A.sub.xB.sub.yM.sub.zO.sub.w, where the A contains at least one selected from Ba and Sr, the B contains Zr, the M is at least one selected from Mn, Co, Ni and Fe, y+z=1, x0.995, z0.4, and w is a positive value satisfying electrical neutrality. A film thickness of a catalyst-supporting film supported on the support and containing the catalyst particle is 5 m or more, or a supported amount as determined by normalizing a mass of the catalyst particle supported on the support by a volume of the support is 45 g/L or more.

An all-condition auxiliary denitration system and an operation method thereof are provided. The system includes a heat-storage medium heater, a low-temperature reheater, an economizer, and an SCR denitration device which are successively interconnected, and further including a heat-storage medium tank and a heat-storage medium and feedwater heat exchanger. A flow of a cold heat-storage medium entering the heat-storage medium heater is regulated, so that heat absorption of the heat-storage medium is matched with a boiler load. Flows of hot heat-storage medium and feedwater, which enter the heat-storage medium and feedwater heat exchanger, are regulated through a feedwater regulating valve and a hot heat-storage medium outlet regulating valve. A total feedwater flow is regulated with assistance of a bypass feedwater regulating valve, so that a temperature of flue gas entering the SCR denitration device is kept in an optimal operation range under different boiler loads, and denitration efficiency is ensured.

Some embodiments of the present disclosure relate to a method of regenerating at least one filter medium comprising: providing at least one filter medium, wherein the at least one filter medium comprises: at least one catalyst material; and ammonium bisulfate (ABS) deposits, ammonium sulfate (AS) deposits, or any combination thereof; flowing a flue gas stream transverse to a cross-section of a filter medium, such that the flue gas stream passes through the cross section of the at least one filter medium, wherein the flue gas stream comprises: NO.sub.x compounds comprising: Nitric Oxide (NO), and Nitrogen Dioxide (NO.sub.2); and increasing an NO.sub.x removal efficiency of the at least one filter medium after removal of deposits.

An indoor smoker includes a smoking chamber and an air handler for drawing a flow of smoke from the smoking chamber through an exhaust duct. A catalytic converter is positioned in the exhaust duct and includes a catalytic element and catalytic heater for heating the catalytic element to a temperature suitable for regulating emissions from the flow of smoke. A temperature sensor is used to monitor the temperature of the catalytic element, and smoke generation is stopped when the catalyst temperature drops below a temperature threshold or drops at a rate that exceeds a threshold rate, which may be indicative of a failure of the catalyst heater or air handler.

A method of operating and an arrangement for a steam boiler system including a furnace and along a following flue gas channel a number of superheaters, a number of economizers, and at least one air preheater located in the flue gas channel downstream of the economizers, a fabric filter baghouse located in the flue gas channel downstream of the air preheater, and downstream of the fabric filter baghouse is located a selective catalytic reduction (SCR) system including an SCR reactor, a high pressure steam coil heater upstream of the SCR reactor and a gas-gas heat exchanger connected upstream and downstream of the SCR reactor to transfer heat from flue gas after the SCR reactor to the flue gas upstream of the high pressure steam coil heater.