Theoretical Investigation on the Partial Load Feedwater Heating System with Thermal Vapor Compressor in a Coal-fired Power Unit

When a coal-fired unit operates at a partial load, the decrease at regenerative steam pressure leads to a decrease in boiler feedwater temperature, affecting not only the thermal economical efficiency, but also the selective catalytic reduction (SCR) denitrification effect and the boiler combustion stability. A feedwater system with the thermal vapor compressor has been studied in the present paper. The high pressure regenerative steam is injected by the live steam to heat boiler feedwater to increase its temperature. Mathematical models of the thermal vapor compressor, boiler and turbine regenerative system are established to calculate the performance of a 660MW supercritical air cooling unit at a 60% load. It was found that although the energy-saving effect is small, it is positive to improve the SCR denitrification effect and stabilize the boiler combustion. (C) 2015 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license.