Air-cooled reheating unit system with back pressure type small steam turbine driving water feed pump

The utility model discloses an air-cooled reheating unit system with a back pressure type small steam turbine driving a water feed pump. Specifically, the air-cooled reheating unit system comprises a reheating system, an air-cooled system, a back pressure type steam feed pump system and a regenerative system. In the back pressure type steam feed pump system, a steam inlet pipe of the back pressure type small steam turbine is connected with an exhaust pipeline of a high pressure cylinder or an ultra-high pressure cylinder of a steam turbine in the reheating system, and a steam exhaust pipeline of the back pressure type small steam turbine is connected with the regenerative system. Steam before reheating is used for allowing the back pressure type small steam turbine to drive the water feed pump, then the small steam turbine with the low overheating degree is used for steam extraction and steam exhaust, condensation water heating and water feed are carried out through a heater and/or a deaerization plant, the thermodynamic cycle efficiency of the system is improved, and the heat exchange area of a reheater is reduced. In addition, for a direct air-cooled unit, a small steam turbine condenser and a small steam turbine indirect air cooling tower do not need to be configured. For an indirect air-cooled unit, the heat exchange area of a mainframe indirect air-cooled tower is saved.