Currently

the problem of improving low load combustion stability when(ultra) supercritical thermal power units participate deep peak regulation is lack of effective technology. On the basis of analyzing the basic theory of boiler ignition and stable combustion and comparing the existing boiler stable combustion technologies

this paper proposes a scheme to realize deep low load operation of the boiler through extraction steam heating. In this scheme

the superheat steam and reheat steam is extracted to heat the water at the economizer outlet and the primary air-coal mixture. As a result

the primary air temperature and waterwall temperature increased and the flame stability of the boiler at low load was improved. The application of this scheme in supercritical boilers can enhance the hydrodymanic performance of the waterwall at low load. This technical route has the advantages of high energy utilization efficiency

good transformation performance

clear principle

simple system

able to keep the boiler dry running at lower load

and has certain reference value for peak regulation transformation of large domestic thermal power units.