With the rapid development of installed capacity of clean energy such as wind power

hydropower and photo electricity

the domestic electricity consumption structure has undergone great changes. Deep peak shaving to low-load operation of large thermal power units has become normal. When the unit is deeply adjusted to lower load

the once-through boiler will change from dry to wet operation. Usually

the water separated by the boiler steam-water separator goes directly to the condenser or to the sewage system

which will cause lots of heat and mass loss. Thus

the operating economy of the unit will reduce significantly. In this paper

the characteristics of oncethrough boiler under wet operation have been researched and analyzed. Two high-energy heat-mass recovery technical solutions: through the flash tank to the deaerator and through the booster pump to the water supply pipeline have been proposed. Furthermore

the operating energy consumption before and after high-energy heat-mass recovery has been calculated and compared by Ebsilon software. The results show that

after recovery the energy consumption of the unit will reduce significantly and the economy will improve greatly.