Grade matching-based flue gas waste heat cascade heat supply system for thermal power plant

By introducing a bypass flue and a three-stage heat exchanger into the waste heat system of thermal power plant flue gas, the waste heat of flue gas can be utilized in stages, solving the problem of insufficient utilization of waste heat of flue gas, reducing the flue gas temperature and improving the energy efficiency and regulation capability of the system.

CN115949963BActive Publication Date: 2025-12-16TSINGHUA UNIVERSITY +1
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Patent Information

Application Number
CN202310075569.3
Authority / Receiving Office
CN · China
Patent Type
Patents(China)
Current Assignee / Owner
Filing Date
2023-01-13
Publication Date
2025-12-16
Estimated Expiration
2043-01-13

AI Technical Summary

Technical Problem

Existing technologies fail to effectively utilize the waste heat from flue gas in thermal power plants, resulting in high final discharge temperatures, and fail to simultaneously consider the combined impact of waste heat utilization and steam extraction for heating on the unit.

Method used

By introducing a bypass flue and a three-stage heat exchanger, the heat exchange is designed in stages. High-temperature, medium-temperature and low-temperature flue gas are used to heat the high-temperature, medium-temperature and low-temperature water of the regenerative steam extraction system, respectively, thereby reducing the heat exchange temperature difference and realizing cascade utilization. The amount of regenerative steam extraction is adjusted by regulating the bypass flue gas volume and the heat exchanger temperature.

Benefits of technology

It achieves deep utilization of flue gas waste heat, reduces the final exhaust temperature of flue gas to about 80°C, improves the energy efficiency of the system, and can adjust the amount of regenerative steam extraction, affecting the power generation and heat supply of the turbine unit.

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Abstract

The application discloses a kind of based on grade matching's thermal power plant flue gas waste heat cascade heat supply system, and its flue gas waste heat cascade utilization system includes flue, air pipeline, air preheater, three-stage heat exchanger and regenerative extraction system.Flue includes total flue, main flue, bypass flue and convergence flue;Air preheater is arranged on main flue and air pipeline;Three-stage heat exchanger's high-temperature heat exchanger, medium-temperature heat exchanger are sequentially arranged on bypass flue, and three-stage heat exchanger's low-temperature heat exchanger is arranged between the output end of convergence flue and flue gas dust collector;Regenerative extraction system is coupled with three-stage heat exchanger, and high-temperature flue gas in high-temperature heat exchanger, medium-temperature flue gas in medium-temperature heat exchanger, low-temperature flue gas in low-temperature heat exchanger are correspondingly used to heat part of high-temperature water, part of medium-temperature water and part of low-temperature water in regenerative extraction system.The application can utilize flue gas waste heat deeply, can effectively reduce flue gas final discharge temperature greatly, and simultaneously, can adjust the regenerative extraction amount of regenerative extraction system.
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Citation Information

Patent Citations

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    CN103062754A

  • Boiler flue gas waste heat heating system

    CN104235928A

  • Heat supply device of multi-pressure-grade multi-extraction-port same-type double-turbine engine unit

    CN112344412A

  • Flue gas waste heat recovery and energy storage system for thermal power plant

    CN114263924A