Method of regenerating NOx removal catalyst and method of operating heavy-oil fired combustion apparatus
AssigneeMitsubishi Hitachi Power Systems, Ltd.
InventorsKatsumi Nochi, Masashi Kiyosawa, Hideo Miyanishi
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Abstract
The method includes a pretreatment step during an operation of a boiler in which in a predetermined period of time before shutdown of the boiler, a part of combustion gas that has bypassed an economizer provided in a flue gas duct for flue gas from the boiler is supplied to an upstream of a NOx removal device having a NOx removal catalyst and mixed with the combustion flue gas from the economizer to generate mixed gas having a predetermined temperature equal to or higher than 360° C. (360° C. to 450° C.), the mixed gas is introduced into the NOx removal catalyst, thereby decomposing VOSO4 adhering to and accumulating on the NOx removal catalyst into V2O5.
Claims5
A method of operating a heavy-oil fired combustion apparatus that burns heavy oil in a boiler, wherein
- at an operating step before shutdown of a boiler, a part of combustion gas that has bypassed an economizer provided in a flue gas duct for flue gas from the boiler is supplied to an upstream of a NOx removal device and mixed with flue gas from the economizer, a temperature of mixed gas is increased to a predetermined temperature equal to or higher than 360° C., which is higher than a normal operating temperature condition, to have the NOx removal device in a high-temperature denitration condition, so that nitrogen oxide in flue gas is removed during an operation of the NOx removal device, and vanadyl sulfate (VOSO4) adhered and accumulated on a NOx removal catalyst is decomposed into vanadium pentoxide (V2O5), and
- sulfur oxide (SOx) produced at a time of decomposing vanadyl sulfate (VOSO4) into vanadium pentoxide (V2O5) at the operating step before shutdown is treated in an air pollution control facility on a downstream side of the NOx removal device.
Dependencies are inferred from the claim text.