The higher power consumption of motor-driven feed water pump set is a common problem in coal-fired unit. The transformation of turbine-driven feed water pump combined with industrial steam supply is considered as an effective approach to solve this problem. Taking a domestic 330 MW direct air-cooled unit for example

the scheme of adding a back pressure turbine for 50% capacity feed water pump is determined based on comprehensive consideration of low load expectations and the current status of steam supply. The economics of three steam supply schemes

including combination scheme of original pressure adaptors and third-stage extraction

scheme of back pressure turbine source for feed water pump from cold section exhaust of reheating

and scheme of back pressure turbine source for feed water pump from hot section exhaust of reheating

are calculated quantitatively. The results show that

compared with the original scheme

the net coal consumption rate of scheme of back pressure turbine source from cold section exhaust of reheating decreases by 1.6 g/(k W·h) and the net coal consumption rate of scheme of back pressure turbine source from hot section exhaust of reheating decreases by 3.0 g/(kW·h). The steam pump transformation scheme of back pressure turbine driven feed water pump set and exhaust steam directly for industrial steam supply has a good energy saving effect with a high degree of energy cascade utilization

a short static payback period with a low total investment

a good feasibility with controllable security risk.