Influence of operating conditions on ammonium bisulfate deposition in the rotary air preheater of coal-fired power plants

Abstract

Original scientific paper https://doi.org/10.2298/TSCI180524213W To achieve the maximum NOx reduction in coal-fired power plant, excess ammonia is injected into the selective catalytic reduction reactor, which leads to the formation of ammonium bisulfate due to the reaction between ammonia escaping from the selective catalytic reduction reactor and SOx in the flue gas. Ammonium bisulfate can condense in the rotary regenerative air-preheater, which would adversely affect the safe and efficient operation of the air-preheater. An improved radian number is proposed to estimate the ammonium bisulfate deposition. The operating conditions or modes of the air-preheater, i. e., air-flow bypass, cold--end protection and different splitting fluid sector arrangements, are comparatively studied to analyze the temperature and ammonium bisulfate deposition distributions. The hot air re-circulation is not helpful to mitigate the ammonium bisulfate deposition in medium matrix layer. The splitting gas sector arrangement would cause more serious plugging problem, but the splitting air sector arrangements can alleviate the ammonium bisulfate deposition. To increase the air bypass rate is more effective than the splitting air sector arrangements to alleviate the plugging problem. The improved radian number is more reasonable to reflect the ammonium bisulfate deposition compared with the original radian number.

Investigation of safe operating conditions for reducing acid corrosion and ABS deposition in rotary air preheater using computational fluid dynamics

“…The rate of ABS formation is given by the Radian number. Wang et al [21] proposed an improved Radian number while optimising the performance of rotary preheater using genetic algorithm. Zhou et al [22] carried out investigation on ABS formation temperature and stated that the ABS formation can be controlled by monitoring the concentrations of NH3 and SO3, fly ash and operating temperature.…”