Comprehensive waste heat utilization system for deep optimization of primary air preheating process

Abstract

The invention belongs to the technical field of power station energy conservation and discloses a comprehensive waste heat utilization system for deep optimization of the primary air preheating process. A front air preheater is adopted for the system to preheat primary air and secondary air; a dimidiate-bin rotating type air preheater is adopted for a secondary air preheater of a main flue to further heat secondary air; primary air is gradually heated to the needed temperature of an inlet of a coal mill through the front air prehater, a primary steam primary air preheater and a secondary steam primary air preheater; and a supplied water heater and a condensed water heater in a bypass flue are arranged in series and used for heating supplied water and condensed water. According to the system, primary air and secondary air are independently preheated, primary air is heated through low-temperature flue gas and extracted steam from a turbine in a grading manner; and exergy losses caused by cold and hot primary air mixing are avoided. Meanwhile, high-grade flue gas heat is displaced, supplied water and condensed water are heated, secondary air is heated in a grading manner through the front air preheater and the dimidiate-bin air preheater, deep energy conservation and consumption reduction of a coal-fired generating unit are fully achieved, and economic benefits are remarkable.

Description

technical field [0001] The invention belongs to the field of power station energy saving, and in particular relates to a comprehensive waste heat utilization system with deep optimization of primary air preheating process. Background technique [0002] Energy conservation and emission reduction has become an important strategy for my country to solve the energy crisis and environmental pollution problems. In order to alleviate my country's huge energy consumption and environmental pressure, large-scale coal-fired units have gradually carried out research and application of waste heat utilization to improve the energy efficiency of coal-fired power plant units. Utilization efficiency, optimal design of unit heat exchange equipment, and in-depth excavation of the energy-saving potential of coal-fired power plant units have become increasingly important topics for coal-fired power plants. [0003] Conventional coal-fired power plants generally use a three-chamber rotary air preh...

AI Technical Summary

Problems solved by technology

However, it does not change the air preheating process, and there is still a problem caused by primary air mixing. loss

[0005] The existing hot primary air heater and its system adopting a primary air and condensate heat exchanger at the outlet of the air preheater to reduce the temperature of the primary air cannot achieve a good energy-saving effect, because the total primary air absorbs heat and grinds coal The primary air temperature at the inlet of the pulverizer is fixed. This system can only adjust the air temperature at the inlet of the coal mill. Compared with the direct heat transfer from the flue gas to the condensate, the system increases the heat transfer process, resulting in irreversible heat transfer. Increased loss, unsatisfactory energy saving effect

Moreover, due to the high moisture content of the raw coal entering the pulverizing system in conventional coal-fired power stations, the primary air temperature at the inlet is relatively high due to the drying limitation of the pulverizing system.

Therefore, limited by many factors, there is a large energy waste in the existing air preheating system, and the existing technology cannot achieve a good energy saving goal.

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