Multistage impulsion type steam turbine with damp being removed and heat being regained inside machine

The invention provides a build-in dehumifying reheating multiple stage turbine. The steam reheater is set between the adjacent grades in the cylinder of the turbine, leads the new steam from the main steam tube behind the main valve of the turbine to the reheater to heat expansion desiccation and steam and falls its humidity to protect the turbine from the water erosion; the outlet of the reheater connects the sparse liquid expansion box through the sparse box valve and the exhausting aperture of the expansion box connects the condensator. The invention can directly desiccate and reheat the steam between the grades.