Effect of Flue Gas Recirculation on Reheated Steam Temperature of a 1000MW Ultra-supercritical Double Reheat Boiler

Abstract

In view of the problem that the reheat steam temperature is lower than the design value in the operation of a 1000MW ultra-supercritical double reheat boiler in a power plant, this paper puts forward the method of flue gas recirculation (FGR) to improve it. Two schemes are put forward:the extraction of flue gas from the economizer or the draft fan to the bottom burner of the furnace. Indifferentload conditions,using the standard method of boiler thermodynamic calculation,the influence of different FGR schemes on boiler operation parameters is calculated. The results show that above FGR schemescan obviously improve thereheat steam temperature; with the increase of the amount of recirculating gas, the rise of the reheat steam temperature increases; with the decrease of the load, the influence of FGR on steam temperature increase; the scheme of extracting recirculating flue gas from the economizer outlet has little effect on the boiler efficiency, which is more suitable for the boiler, and the reasonableFGR rate is about 10%.