Under the premise that deep peaking of thermal power units has become normal operation

it poses a higher challenge to transformation of industrial steam supply of thermal power units. Three steam supply schemes using reheater recirculation cooling as the core technology are proposed to meet the requirements of high-pressure steam supply transformation of 660 MW supercritical units. Moreover

the feasibility and economy of these schemes are analyzed by thermodynamic calculation under varying working conditions. The calculation results show that

all the three schemes can ensure the safe operation of the reheater under non-overtemperature conditions

and greatly improve the wide load high pressure steam supply capacity of the unit at 30% rated power load or above and under conditions that meet the demand of single unit with 200 t/h

6.0 MPa and 480 ℃ steam supply. In order to avoid overspeed of the flow rate at the reheater outlet

it is necessary to coordinate the operation of the immediate pressure(IP) control valve to reduce the flow rate of the reheated steam by increasing the pressure of the reheated steam. With the decrease of the load

the reheater recirculation flow rate under the rated steam supply flow rate will increase. The recirculation flow rate under the whole working conditions of scheme 1 and scheme 3 is not much different

and the ratio of the recirculation flow rate under the high and low load of scheme 2 can reach more than 5 times. Among the three steam supply transformation schemes

scheme 2is the most energy efficient

scheme 3 is second

and the three schemes can produce economic benefits of 39.51

44.45 and 41.78 million yuan each year

but in the implementation process

the selection of schemes should consider factors such as investment cost

operation and maintenance amount and energy saving income.