Theoretical investigation on heat-electricity decoupling technology of low-pressure steam turbine renovation for CHPs

The power grid peaking capacity is insufficient due to the increasing installed capacity of renewable power. Moreover, it is also restricted by the operation mode of combined heat and power units (CHPs), the minimum electricity loads of which are determined by the heat load. It is significant to study the heat-electricity decoupling technologies for CHPs. Therefore, the low-pressure steam turbine renovation technology is studied in this paper with a 300MW unit as reference case. Results show that the minimum electric load rate and the coal consumption are decreased, and the heat-electricity ratio is increased significantly for CHP with low-pressure steam turbine renovation. When the heat load is 1200 GJ/h, the minimum electric load rate and coal consumption with low-pressure steam turbine renovation can be reduced by 32.4 and 30.9 % respectively. The heat-electricity ratio can be increased by 68.8 % after renovation of low-pressure steam turbine.