The structure of the double reheat and heat regeneration system was presented.Key technologies including the number of regeneration stage

the external steam cooler

HARP

double reheat and the new MC system were discussed.Taking an ultra supercritical 800MW unit as the example

comparison between and among the unit applying the double reheat heat regeneration system and that combined with MC system and that applying single reheat heat regeneration system was performed.The results showed that

under the second reheat condition

the main steam pressure increased by 1.4MPa

while the main steam temperature dropped by 5℃

the unit heat consumption decreased by about 226kJ/(kW·h)

and the heat efficiency rose by 1.4%.Compared with the single reheat system

for the MC system

the main steam pressure increased by3.8MPa

while the main steam temperature dropped by 5℃

the unit heat consumption decreased by about 235kJ/(kW·h)

and the heat efficiency rose by about 1.45%.The system efficiency of the MC system increased little than that of the typical double reheat and heat regeneration system.However

the technical advantage of the MC system relies on further improvement of the high back pressure turbine.