After retrofitting on high back pressure circulating water heating for a 200 MW unit

thermodynamic calculation was performed.The results show that

the heat net circulating water quantity and steam extraction amount(for heat supply)has little effects unit parameters such as heat consumption rate

unit output

heat load and circulating water outlet temperature.Under each working condition

the fuel utilization coefficient can reach about 90%

implying the energy comprehensive utilization effect is great.However

the unit back pressure is greatly affected by the heat net circulating water quantity and steam extraction amount.Moreover

the unit's operation regulating flexibility got poor and the retrofitting work capacity is pretty huge.The rotor changing time must be carefully selected after the retrofitting

and the units with very small heat load are not suitable for transformation.Due to small output of the 200 MW unit's low pressure(LP)cylinder

it suggests that the LP cylinder be split to reduce the modification range and simplify the steps.