Double-reheat steam turbine heat regenerative energy utilizing system for primary air and secondary air of heating boiler

Abstract

The invention relates to a double-reheat steam turbine heat regenerative energy utilizing system for primary air and secondary air of a heating boiler. The system comprises a steam turbine power generating unit , a flue gas heating unit, an air overheating unit, an air preheating unit, a condensation water heating unit, a feedwater deoxidizing and heating unit, a feedwater heating unit, a primary air fan, a secondary air fan, a boiler furnace and a coal mill. According to the system, an air preheater which is necessarily arranged in the design of a conventional boiler is omitted, all stages of extracted steam of the steam turbine is utilized to heat air supplied by the primary air fan and the secondary air fan, it means that a set of heaters are arranged together with the condensation water heating unit and the feedwater heating unit, the heat regenerative range of the unit is greatly widened, and the cold source loss of the steam turbine is reduced; the secondary air temperature is significantly increased through the overheating degree of the extracted steam of all the stages, combustion of the boiler is enhanced, the stability of firing of the boiler is improved when the unit is operated at a low load, heat of a steam turbine heat regenerative system is effectively utilized, and the boiler fuel consumption is reduced.

Description

technical field [0001] The invention relates to the technical field of reheating steam extraction by reheating steam turbines and energy utilization of flue gas at the tail of boilers, in particular to a secondary reheating turbine regenerating energy utilization system for heating primary and secondary air of boilers. Background technique [0002] With the development of the economy, the society's demand for electricity continues to increase, and the protection of the environment is increasingly valued. More than 70% of my country's electricity is generated by coal-fired power stations. At present, the energy utilization rate of coal-fired power stations is low, and most of the heat is discharged into the environment. Among them, the thermal cycle efficiency of the steam turbine is low, and the loss of the cold source accounts for more than half of the thermal cycle loss; among the various losses of the boiler, the exhaust heat loss accounts for more than 70% of the total h...

AI Technical Summary

Problems solved by technology

Steam does work in each cylinder of the steam turbine, and its pressure drop exceeds the speed of temperature drop. Therefore, the extraction steam enthalpy and exhaust steam enthalpy are generally much larger than that of a reheated steam turbine unit. Even if more heat recovery stages are used, the loss of the cold source will increase Big

[0005] If the design feedwater temperature of the double-reheat turbogenerator set can exceed 3

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