Taking a subcritical 335 MW unit as the example

the variations of heat absorptions of each heating surface and the flue gas inlet temperature were calculated

when the reheat steam temperature was increased.Thus

the effect of increasing reheat steam temperature on boiler thermal performances was investigated

and the economic analysis was also carried out.The results show that:as the reheat steam temperature rose

the boiler thermal performance and exhaust gas temperature varied slightly;the heat absorptions and flue gas inlet temperatures of the heating surfaces arranged after the secondary and the last stage reheaters decreased gradually;moreover

the decrease degree weakened sequentially along the flue gas path;a rise of 10 ℃in reheat steam temperature may lead to about an increase of 5 MW in unit capacity and0.85%in cycle efficiency.Finally

a detailed scheme of improving reheat steam temperature from 538℃to566℃ was put forward.After transformation

the annual income of this system can be increased by3.957 2×106 yuan.