Secondary reheating system and method achieving efficient regeneration and steam exhaust optimization

Abstract

The invention discloses a secondary reheating system and method achieving efficient regeneration and steam exhaust optimization, and relates to the field of thermal power generation. The system mainlycomprises a boiler, a regeneration steam turbine and a waste heat recovery system, wherein the waste heat recovery system replacing a traditional low-pressure heater is arranged between a condensatewater pump and feedwater of a seventh-stage low-pressure heater, condensate water is preliminarily heated by the waste heat recovery system through flue gas of the boiler and pipeline leaking steam ofthe regeneration steam turbine, and the waste heat recovery system is composed of a flue gas cooler, a low-temperature coal economizer and a sealing heater. The flue gas cooler, the low-temperature coal economizer and the sealing heater replace the traditional low-pressure heater to heat the feedwater, and steam exhaust energy losses of the steam turbine are reduced while heat of the boiler is recovered. The arrangement of a unit is optimized as a whole, efficient regeneration is further enhanced, and the complexity of the system is lowered. The coal consumption can be reduced by 2 g / kW.h to3 g / kW.h while the power supply efficiency of a traditional 1,000 MW secondary reheating unit is improved by 0.2% to 0.3%.

Description

[0001] Patent field [0002] The invention relates to the field of thermal power generation, in particular to a secondary reheating system and method for efficient heat recovery and optimized steam extraction. Background technique [0003] At present, large-capacity, high-parameter thermal power units have become the mainstream of thermal power units in my country. Currently, there are more than a dozen double reheat units approved or under construction. The main steam pressure is 28MPa~31MPa, and the main steam temperature is 600℃~ 620°C, higher steam parameters can improve the efficiency of the thermal power generation cycle system. Since the problem of high-temperature materials for thermal power units has not been resolved, the development projects of 700°C thermal power units in the world have encountered obstacles and will not happen in the short term. There are commercial applications, so it is necessary to continue to optimize the system from other directions to achieve ...

AI Technical Summary

Problems solved by technology

However, due to the high temperature of the main steam and the reheat steam of the double reheat unit, there is a problem that the superheated degree of the extraction steam of the regenerative heaters at all levels is very high, and the superheated extraction steam in these regenerative heaters comes from the steam turbine The pressure cylinder increases the energy loss of the double reheat unit and hinders the further improvement of the efficiency of the double reheat unit; therefore, a new system is urgently needed to solve the problem of overheating of the regenerative heater extraction steam

[0005] The traditional double reheat system increases the complexity of the system, and compared with the single reheat system, the inlet steam pressure of the low-pressure cylinder is lower and the volume flow is larger, resulting in greater energy loss. The efficiency of the low-pressure cylinder is The lowest among steam turbines, its extraction steam heats the feed water of the reheating system, which further increases the energy loss of the low-pressure cylinder, so it is necessary to optimize the overall optimization of the traditional double reheating system

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