System and method for indirectly heating air heater through extracted low-level steam in waste heat cascade utilization mode

Abstract

The invention provides a system and method for indirectly heating an air heater through extracted low-level steam in a waste heat cascade utilization mode. The system comprises a gas-gas heater arranged between a boiler rear smoke channel air preheater and an electric dust remover, the air heater arranged in front of an air side inlet of the air preheater and a circulating water pipe for connecting the gas-gas heater and the air heater and condensation water, primary cold air and secondary cold air in the air heater are heated through the condensation water at an outlet of a No.7 low-pressure heater, return water of an outlet of the air heater is returned to an inlet of a No. 8 low-pressure heater, the flow of the condensation water of the No.7 low-pressure heater and the No. 8 low-pressure heater is increased, the flow of No.8 extracted steam and No.7 extracted steam is increased, and the purpose of indirectly heating the air heater through the No.8 extracted steam and the No.7 extracted steam is achieved; part of condensation water led out by an inlet of a No.6 low-pressure heater is conveyed to the gas-gas heater to absorb heat and is led back to a regenerative system through an outlet of the No.6 low-pressure heater, the flow of the condensation water of the No.6 low-pressure heater is decreased, the flow of the No.6 extracted steam is decreased accordingly, a part of the squeezed out No.6 extracted steam is conveyed to a steam turbine to conduct acting, and the economical efficiency of a unit is improved.

Description

technical field [0001] The invention relates to the technical field of thermal power generation, in particular to a low-energy extraction steam indirect heating air heater system and method for cascaded utilization of waste heat. Background technique [0002] With the rising global energy prices and the deteriorating climate around the world, the country has more stringent requirements for energy conservation and consumption reduction. How to deeply tap the energy-saving potential of existing power plant units and reduce the production and operation costs of enterprises has become a common concern of every enterprise. important question. [0003] Most power plant boiler units in northern my country are equipped with heater systems to solve the problems of low-temperature corrosion at the cold end of the air preheater and clogging of dust accumulation caused by low air temperature at the inlet of the air preheater in winter or low exhaust gas temperature under low load . The...

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Problems solved by technology

In general, every 20°C increase in exhaust gas temperature will increase the heat loss of exhaust gas by 0.6% to 1.0%, which will have an adverse impact on the economy of the unit.

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