摘要
Abstract
Under the premise that deep peaking of thermal power units has become normal operation,it poses a higher challenge to transformation of industrial steam supply of thermal power units.Three steam supply schemes using reheater recirculation cooling as the core technology are proposed to meet the requirements of high-pressure steam supply transformation of 660 MW supercritical units.Moreover,the feasibility and economy of these schemes are analyzed by thermodynamic calculation under varying working conditions.The calculation results show that,all the three schemes can ensure the safe operation of the reheater under non-overtemperature conditions,and greatly improve the wide load high pressure steam supply capacity of the unit at 30%rated power load or above and under conditions that meet the demand of single unit with 200 t/h,6.0 MPa and 480℃steam supply.In order to avoid overspeed of the flow rate at the reheater outlet,it is necessary to coordinate the operation of the immediate pressure(IP)control valve to reduce the flow rate of the reheated steam by increasing the pressure of the reheated steam.With the decrease of the load,the reheater recirculation flow rate under the rated steam supply flow rate will increase.The recirculation flow rate under the whole working conditions of scheme 1 and scheme 3 is not much different,and the ratio of the recirculation flow rate under the high and low load of scheme 2 can reach more than 5 times.Among the three steam supply transformation schemes,scheme 2 is the most energy efficient,scheme 3 is second,and the three schemes can produce economic benefits of 39.51,44.45 and 41.78 million yuan each year,but in the implementation process,the selection of schemes should consider factors such as investment cost,operation and maintenance amount and energy saving income.关键词
高压供汽/再热器再循环/减温减压/蒸汽喷射器/背压机Key words
high pressure steam supply/reheater recirculation/temperature and pressure reduction/steam ejector/back pressure-type turbine
