When coal-fired boiler is running at low load

there are some problems

such as the low inlet gas temperature causing SCR denitration system to be unable to operate normally

the low primary air temperature

and the insufficient drying capacity of the pulverizing system. In this study

taking a 600 MW coal-fired unit as an example

a comprehensive transformation scheme is proposed for cutting off part of the heat exchange surface of the horizontal low-temperature superheater and high-temperature economizer

increasing the heat exchange surface at the outlet of the SCR denitration system

and optimizing the flue gas flow field at the inlet of tubular pipe air preheater. After the transformation

under the load of 300 MW

the primary air temperature at the outlet of tubular pipe air preheater is increased by 26 ℃

the gas temperature at the inlet of the SCR denitration system increases by 28 ℃

the drying capacity of the pulverizing system is enhanced

and the adaptive ability of the SCR denitration system to depth peak regulation is greatly improved. The successful application of this technology provides ideas for the technical transformation of the same type of units.