Based on comparative analysis on domestic heating retrofit technologies

the heating retrofit scheme of small back-pressure turbine was selected as the heating retrofit scheme for No.7 and No.8 unit of Jingyuan Second Power Co.

Ltd.. In this scheme

the heating steam is extracted from the connection pipe between the medium and the low pressure cylinder of the No.7 and No.8 steam turbine generator unit. Part of the steam is sent into the back-pressure steam turbine generators to produce electricity

and the exhaust steam is sent into two primary heaters to heat the circulating water to 95 ℃. The other part of the steam is sent into the peak-load heaters to further heat the circulating water to 130 ℃ so as to supply heat. In the non-heating period

the heating system can be decomposed

and the extraction of steam from connection pipe of the main steam turbine can be stopped.The result shows that

under the condition with heating load of 107.2 MW and heating period of 150 days

after the heating retrofit project was carried out

the annual total heating supply is 1 389 826 GJ

the total reduction of standard coal consumption is 36 068.7 t/a

the reduction of CO2

SO2

NOx and dust emissions is 144 007.6 t/a

167.7 t/a

196.6 t/a and 196.4 t/a

respectively. The actual operation situation proves that

the small back-pressure turbine heating retrofit scheme

of which the system is clear and can stably operate

the energy conservation and emissions reduction of the project are profitable. Additionally

it can effectively reduce the auxiliary power consumption rate and increase the on-grid energy

which creates objective benefit for power plants. It is confirmed that the heating retrofit scheme technology of small back-pressure turbine is mature

and it is worth promoting in cities with stable heating load in North China.