Waste heat boiler power generation optimization method of gas-steam combined generator set

Abstract

The invention discloses a waste heat boiler power generation optimization method for a gas-steam combined generator set, and the method comprises the steps: deeply cooling the exhaust gas temperature to below 75 DEG C through a multi-stage anti-corrosion heat exchange device, and carrying out the heat exchange through an intelligent control heat medium water circulation loop; the recycled heat is distributed to natural gas preheating, refrigeration, heat supply, air preheating and the like according to the priority in a cascade mode. According to the system, efficient deep recovery and comprehensive utilization of flue gas waste heat are achieved, the energy efficiency and economical efficiency of the unit are remarkably improved, and safe and reliable operation of the system is ensured through intelligent anti-corrosion control.

Description

Technical Field

[0001] This invention belongs to the field of thermal energy engineering technology, specifically relating to an optimization method for waste heat boiler power generation in a gas-fired steam combined generator unit. Background Technology

[0002] Gas-fired combined cycle generator sets are widely used due to their high efficiency, but the flue gas temperature of the waste heat boiler is usually high (approximately 110-120℃), resulting in a large amount of low-temperature flue gas waste heat not being fully recovered, causing energy waste. While some flue gas waste heat recovery devices exist in the current technology, they often suffer from the following problems: 1. Low recovery efficiency: Traditional devices typically only reduce exhaust gas temperature to 90-100℃, leaving a significant amount of waste heat unutilized. 2. Limited utilization: Recovered heat is usually used for a single purpose, such as heating water or space heating, failing to achieve comprehensive cascade utilization. 3. Poor system adaptability: During unit changes in operating conditions or start-up and shutdown, the waste heat recovery system operates unstablely and may even be damaged due to low-temperature corrosion. 4. Lack of intelligent control: The waste heat recovery process cannot be dynamically optimized based on parameters such as unit load and ambient temperature, affecting overall energy efficiency. Summary of the Invention

[0003] This invention aims to overcome the aforementioned deficiencies of the prior art and provides a waste heat recovery boiler power generation system and method for a gas-fired steam combined generator set. It can significantly reduce flue gas temperature and achieve cascaded and efficient utilization of thermal energy.

[0004] To solve the above problems, the present invention adopts the following technical solution.

[0005] A waste heat recovery boiler power generation system for a gas-fired steam combined generator set includes: a multi-stage waste heat exchange device installed in the tail flue of the waste heat boiler, including a high-temperature heat exchange module and a low-temperature heat exchange module, used to perform multi-stage countercurrent heat exchange between heat medium water and flue gas to reduce the exhaust gas temperature to below 75°C. The heat transfer medium water circulation loop is connected to the multi-stage waste heat exchange device to form a closed loop; A multi-path thermal energy utilization device, connected to the heat medium water circulation loop, includes a natural gas heating device, an interface for connecting to a lithium bromide absorption chiller, an interface for connecting to the plant heating network, and an air preheater. The intelligent control system is used to monitor system operating parameters in real time and dynamically control the circulating water pump, regulating valve group, return bypass valve and start-up heater through optimization algorithms to achieve deep recovery of flue gas waste heat, cascade distribution of heat energy and system safety protection.

[0006] Furthermore, the high-temperature heat exchange module is made of ND steel (09CrCuSb) resistant to sulfuric acid dew point corrosion, and the low-temperature heat exchange module is made of fluoroplastic heat exchanger or glass tube heat exchanger resistant to low-temperature corrosion.

[0007] Furthermore, the intelligent control system includes: a data acquisition unit for real-time monitoring of flue gas temperature, heat transfer water temperature and flow rate, natural gas temperature, ambient temperature and unit load; The optimized control unit has a built-in optimization algorithm model to calculate the optimal target value of flue gas temperature, the flow distribution ratio of each heat energy utilization device, and output control commands. The execution unit, including a frequency converter, an electric regulating valve, and a soot blower controller, is used to execute control commands.

[0008] Furthermore, the algorithm model of the optimized control unit aims to maximize the overall economic benefits of the system and includes anti-corrosion safety constraints to ensure that the metal wall temperature of the heat exchanger is always higher than the acid dew point temperature of the flue gas.

[0009] Furthermore, it also includes an online automatic cleaning device, which is an acoustic soot blower or a shock wave soot blower, used to periodically remove ash accumulated on the outer wall of the heat exchange tubes.

[0010] Furthermore, the heat transfer medium circulation loop is equipped with a reflux bypass system, which is equipped with a regulating valve to adjust the amount of flue gas flowing into the heat exchanger according to the flue gas temperature.

[0011] A method for optimizing waste heat boiler power generation in a gas-fired steam combined generator unit, implemented using the system described in any one of claims 1-6, is characterized by comprising the following steps: Deep cooling process for flue gas: The flue gas is passed through a high-temperature heat exchange module and a low-temperature heat exchange module in sequence to exchange heat with the heat transfer medium water, thereby deeply cooling the flue gas temperature to below 75°C. Intelligent heat distribution steps: The intelligent control system dynamically adjusts the opening of the regulating valves in each channel according to the real-time heat demand priority and optimization algorithm, and distributes the recovered heat to natural gas preheating, cooling, heating and air preheating as needed. System safety protection steps: By monitoring key parameters through the intelligent control system, auxiliary heating and regulating bypass are activated during unit start-up, shutdown, or low-load conditions to prevent low-temperature corrosion.

[0012] Furthermore, in the intelligent heat distribution step, heat is preferentially used to heat the natural gas entering the gas turbine.

[0013] Furthermore, in the system safety protection steps, the acid dew point temperature is estimated in real time based on the sulfur content in the flue gas, and the temperature of the heat transfer water is controlled to always be more than 5°C higher than the acid dew point temperature.

[0014] Furthermore, it also includes a periodic online cleaning step: the online cleaning device is automatically activated according to a preset cycle or differential pressure signal to remove the accumulated dust on the heat exchange surface.

[0015] Compared with the prior art, the advantages of this invention are: (1) Significantly improved energy utilization efficiency: Through the cascade utilization and intelligent distribution of thermal energy, the recovered heat is utilized most effectively, realizing "making the most of heat", and the overall power generation efficiency can be improved by 1.5-2.5%.

[0016] (2) Enhanced system safety and adaptability: Intelligent anti-corrosion control, online cleaning and reflux bypass design ensure long-term safe and stable operation of the system under various working conditions and extend equipment life. Detailed Implementation

[0018] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installed," "equipped with," "sleeved / connected," "connected," etc., should be interpreted broadly. For example, "connection" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium; it can be a connection within a compatible component. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0019] A waste heat recovery boiler power generation system for a gas-fired steam combined generator set includes: a multi-stage waste heat exchange device installed in the tail flue of the waste heat boiler, including a high-temperature heat exchange module and a low-temperature heat exchange module, used to perform multi-stage countercurrent heat exchange between heat medium water and flue gas to reduce the exhaust gas temperature to below 75°C. The heat transfer medium water circulation loop is connected to the multi-stage waste heat exchange device to form a closed loop; A multi-path thermal energy utilization device, connected to the heat medium water circulation loop, includes a natural gas heating device, an interface for connecting to a lithium bromide absorption chiller, an interface for connecting to the plant heating network, and an air preheater. The intelligent control system is used to monitor system operating parameters in real time and dynamically control the circulating water pump, regulating valve group, return bypass valve and start-up heater through optimization algorithms to achieve deep recovery of flue gas waste heat, cascade distribution of heat energy and system safety protection.

[0020] Furthermore, the high-temperature heat exchange module is made of ND steel (09CrCuSb) resistant to sulfuric acid dew point corrosion, and the low-temperature heat exchange module is made of fluoroplastic heat exchanger or glass tube heat exchanger resistant to low-temperature corrosion.

[0021] Furthermore, the intelligent control system includes: a data acquisition unit for real-time monitoring of flue gas temperature, heat transfer water temperature and flow rate, natural gas temperature, ambient temperature and unit load; The optimized control unit has a built-in optimization algorithm model to calculate the optimal target value of flue gas temperature, the flow distribution ratio of each heat energy utilization device, and output control commands. The execution unit, including a frequency converter, an electric regulating valve, and a soot blower controller, is used to execute control commands.

[0022] Furthermore, the algorithm model of the optimized control unit aims to maximize the overall economic benefits of the system and includes anti-corrosion safety constraints to ensure that the metal wall temperature of the heat exchanger is always higher than the acid dew point temperature of the flue gas.

[0023] Furthermore, it also includes an online automatic cleaning device, which is an acoustic soot blower or a shock wave soot blower, used to periodically remove ash accumulated on the outer wall of the heat exchange tubes.

[0024] Furthermore, the heat transfer medium circulation loop is equipped with a reflux bypass system, which is equipped with a regulating valve to adjust the amount of flue gas flowing into the heat exchanger according to the flue gas temperature.

[0025] A method for optimizing waste heat boiler power generation in a gas-fired steam combined generator unit, implemented using the system described in any one of claims 1-6, is characterized by comprising the following steps: Deep cooling process for flue gas: The flue gas is passed through a high-temperature heat exchange module and a low-temperature heat exchange module in sequence to exchange heat with the heat transfer medium water, thereby deeply cooling the flue gas temperature to below 75°C. Intelligent heat distribution steps: The intelligent control system dynamically adjusts the opening of the regulating valves in each channel according to the real-time heat demand priority and optimization algorithm, and distributes the recovered heat to natural gas preheating, cooling, heating and air preheating as needed. System safety protection steps: By monitoring key parameters through the intelligent control system, auxiliary heating and regulating bypass are activated during unit start-up, shutdown, or low-load conditions to prevent low-temperature corrosion.

[0026] Furthermore, in the intelligent heat distribution step, heat is preferentially used to heat the natural gas entering the gas turbine.

[0027] Furthermore, in the system safety protection steps, the acid dew point temperature is estimated in real time based on the sulfur content in the flue gas, and the temperature of the heat transfer water is controlled to always be more than 5°C higher than the acid dew point temperature.

[0028] Furthermore, it also includes a periodic online cleaning step: the online cleaning device is automatically activated according to a preset cycle or differential pressure signal to remove the accumulated dust on the heat exchange surface.

[0029] The above description is merely a preferred embodiment of the present invention; however, the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and its improved concepts, should be covered within the scope of protection of the present invention.

Claims

1. A waste heat recovery boiler power generation system for a gas-fired steam combined generator set, characterized in that, include: A multi-stage waste heat exchange device is installed in the tail flue of the waste heat boiler. It includes a high-temperature heat exchange module and a low-temperature heat exchange module. It is used to reduce the exhaust temperature to below 75°C by multi-stage countercurrent heat exchange between the heat medium water and the flue gas. The heat transfer medium water circulation loop is connected to the multi-stage waste heat exchange device to form a closed loop; A multi-path thermal energy utilization device, connected to the heat medium water circulation loop, includes a natural gas heating device, an interface for connecting to a lithium bromide absorption chiller, an interface for connecting to the plant heating network, and an air preheater. The intelligent control system is used to monitor system operating parameters in real time and dynamically control the circulating water pump, regulating valve group, return bypass valve and start-up heater through optimization algorithms to achieve deep recovery of flue gas waste heat, cascade distribution of heat energy and system safety protection.

2. The system according to claim 1, characterized in that, The high-temperature heat exchange module is made of ND steel (09CrCuSb) that is resistant to sulfuric acid dew point corrosion, and the low-temperature heat exchange module is made of fluoroplastic heat exchanger or glass tube heat exchanger that is resistant to low-temperature corrosion.

3. The system according to claim 1, characterized in that, The intelligent control system includes: a data acquisition unit for real-time monitoring of flue gas temperature, heat transfer water temperature and flow rate, natural gas temperature, ambient temperature and unit load; The optimized control unit has a built-in optimization algorithm model to calculate the optimal target value of flue gas temperature, the flow distribution ratio of each heat energy utilization device, and output control commands. The execution unit, including a frequency converter, an electric regulating valve, and a soot blower controller, is used to execute control commands.

4. The system according to claim 3, characterized in that, The algorithm model of the optimized control unit aims to maximize the overall economic benefits of the system and includes anti-corrosion safety constraints to ensure that the metal wall temperature of the heat exchanger is always higher than the acid dew point temperature of the flue gas.

5. The system according to claim 1, characterized in that, It also includes an online automatic cleaning device, which is an acoustic soot blower or a shock wave soot blower, used to periodically remove ash accumulated on the outer wall of the heat exchange tubes.

6. The system according to claim 1, characterized in that, The heat transfer medium circulation loop is equipped with a reflux bypass system, which is equipped with a regulating valve to adjust the amount of flue gas flowing into the heat exchanger according to the flue gas temperature.

7. A method for optimizing waste heat boiler power generation in a gas-fired steam combined generator unit, implemented using the system described in any one of claims 1-6, characterized in that, Includes the following steps: Deep cooling process for flue gas: The flue gas is passed through a high-temperature heat exchange module and a low-temperature heat exchange module in sequence to exchange heat with the heat transfer medium water, thereby deeply cooling the flue gas temperature to below 75°C. Intelligent heat distribution steps: The intelligent control system dynamically adjusts the opening of the regulating valves in each channel according to the real-time heat demand priority and optimization algorithm, and distributes the recovered heat to natural gas preheating, cooling, heating and air preheating as needed. System safety protection steps: By monitoring key parameters through the intelligent control system, auxiliary heating and regulating bypass are activated during unit start-up, shutdown, or low-load conditions to prevent low-temperature corrosion.

8. The method according to claim 7, characterized in that, In the aforementioned intelligent heat distribution step, heat is preferentially used to heat the natural gas entering the gas turbine.

9. The method according to claim 7, characterized in that, In the system safety protection steps, the acid dew point temperature is estimated in real time based on the sulfur content in the flue gas, and the temperature of the heat transfer water is controlled to always be more than 5°C higher than the acid dew point temperature.

10. The method according to claim 7, characterized in that, It also includes a periodic online cleaning step: the online cleaning device is automatically activated according to a preset cycle or differential pressure signal to remove the accumulated dust on the heat exchange surface.