Improved back-pressure steam turbine

The utility model provides an improved back-pressure steam turbine which comprises a high-pressure circulating part, a low-pressure vacuum part and an air ejector. According to the turbine, the air ejector is additionally arranged on a back-pressure steam turbine in the prior art and used for receiving high-pressure steam exhausted by the high-pressure part and the low-pressure part. A regulating stage nozzle set is improved, four nozzle steam lanes are arranged, forty regulating stage nozzles are arranged, a regulating stage structure of the steam turbine is improved, then steam inlet amount of the steam turbine is increased, the mobility of the steam is improved, and working loss of the steam is reduced; original 2-5 pressure stages are increased to be 6-10 pressure stages, as the average diameter of pressure is reduced, the leaf height must be increased, and loss of the leaf height is reduced; latent heat of vaporization of the low-vacuum exhaust steam can be directly recovered and utilized for backheating