Thermal power station heat energy recovery system

Abstract

The invention discloses a heat energy recovery system of a thermal power station. The heat energy recovery system comprises a high-temperature air preheater, an economizer, a flue gas desulfurization device, a first wet type flue gas condenser, an ORC power generation system, a second wet type flue gas condenser and a heat pump system. Boiler flue gas enters a high-temperature air preheater and a coal economizer respectively to preheat air and heat boiler make-up water; low-temperature flue gas provides a heat source for the ORC power generation system through the first wet-type flue gas condenser and the flue gas desulfurization device, and power generation electric energy is transmitted to a power grid; the ORC waste gas is further subjected to heat energy recovery through a second wet type flue gas condenser, and a heat source is provided for a heat pump system. The heat pump system conveys heat energy to a regional heat supply pipe network, multi-stage recycling of the heat energy is achieved, the energy utilization efficiency is remarkably improved, and pollution emission is reduced.

Description

Technical Field

[0001] The invention relates to the technical field of thermal power generation, and in particular to a heat energy recovery system for a thermal power station. Background Art

[0002] Thermal power plants are one of the main sources of electricity in the world, but their energy efficiency is low, and a large amount of heat energy is lost in the form of flue gas and cooling water, and is not fully utilized. This not only causes energy waste, but also increases the emission of greenhouse gases and pollutants. Although there are some waste heat recovery measures in the prior art, most of them are only for a single link (such as boiler flue gas), and fail to achieve multi-stage waste heat recovery and comprehensive utilization, resulting in limited overall system efficiency. Therefore, there is an urgent need for an efficient and comprehensive heat recovery system that can cover the entire process from high-temperature flue gas to low-temperature waste heat, and realize the multi-purpose of power generation and heating. Summary of the invention

[0003] The object of the present invention is to provide a heat energy recovery system for a thermal power station.

[0004] To achieve the above object, the present invention is implemented according to the following technical solutions:

[0005] The present invention includes a high-temperature air preheater, an economizer, a flue gas desulfurization device, a first wet flue gas condenser, an ORC power generation system, a second wet flue gas condenser, and a heat pump system. The flue gas outlet of the boiler is output to the high-temperature air preheater and the economizer. The high-temperature air preheater preheats the air and guides part of the heat energy to the flue gas desulfurization device. The economizer recovers heat for heating boiler feed water and transmits the waste heat to the first wet flue gas condenser. The flue gas desulfurization device and the first wet flue gas condenser recover the waste heat of low-temperature flue gas as the heat source of the ORC power generation system. The ORC power generation system transmits the electric energy to the power grid. The second wet flue gas condenser further recovers the waste heat of the flue gas of the ORC power generation system and serves as the heat source of the heat pump system. The heat pump system transmits the recovered heat source to the regional heating network.

[0006] Furthermore, the high-temperature air preheater is a spiral heat exchanger or a plate heat exchanger, or both.

[0007] The heat energy recovery method of the heat energy recovery system of a thermal power station according to the present invention comprises the following steps:

[0008] S1: The high-temperature flue gas generated by boiler combustion is output from the flue gas outlet and divided into two paths. The first path enters the high-temperature air preheater to preheat the air entering the boiler to improve combustion efficiency. The second path enters the economizer to heat the boiler feed water through heat exchange to reduce the energy consumption of boiler steam generation;

[0009] S2: The high-temperature air preheater preheats the air and transmits part of the heat energy to the flue gas desulfurization device, reducing the flue gas temperature through heat exchange, providing suitable working conditions for subsequent treatment, and providing energy to support the material reaction and dust removal process of the desulfurization process;

[0010] S3: The economizer transfers the sensible heat in the flue gas to the boiler feed water, increases the feed water temperature, and reduces the boiler heating burden. The low-temperature flue gas at the economizer outlet is transported to the first wet flue gas condenser and enters the low-temperature waste heat recovery stage;

[0011] S4: The first wet flue gas condenser recovers the sensible heat and latent heat in the low-temperature flue gas, providing a suitable heat source for the ORC power generation system. The flue gas desulfurization device combines the low-temperature flue gas of the wet flue gas condenser to further recover heat and reduce pollutant emissions, while serving as an auxiliary heat source for the ORC power generation system;

[0012] S5: The ORC power generation system utilizes the heat energy recovered from the first wet flue gas condenser and the flue gas desulfurization device to drive the turbine through the evaporation of the low-boiling-point working fluid to generate electrical energy, and the generated electrical energy is transmitted to the power grid;

[0013] S6: The exhaust gas discharged from the ORC power generation system further enters the second wet flue gas condenser to further recover the low-temperature waste heat in the flue gas, reduce the exhaust gas temperature, and the recovered heat energy is used as the heat source of the subsequent heat pump system;

[0014] S7: The heat pump system uses the low-temperature heat source provided by the second wet flue gas condenser to raise the heat to a usable temperature through heat pump technology, and transmits the extracted heat energy to the regional heating network to meet the heating needs of the factory area or nearby residents.

[0015] As an improvement, the thermal energy recovery system of the thermal power station optimizes the heat distribution between modules through real-time monitoring and intelligent adjustment to ensure maximum thermal energy utilization efficiency.

[0016] Specifically, the real-time monitoring and intelligent adjustment are composed of sensors, monitoring systems, data analysis and anomaly detection units, and intelligent adjustment units. The sensors are temperature sensors, pressure sensors, flow meters, and electric energy meters. The monitoring system centrally collects and displays the data of the above sensors, and displays the system operation status in real time through a friendly graphical interface; the data analysis and anomaly detection unit analyzes the fluctuation trend of data such as temperature, pressure, and flow, detects whether the operating parameters are within the design range, predicts the parameter change trend under normal circumstances, and judges deviations; the intelligent adjustment unit uses a programmable logic controller for valve switching and pump speed adjustment, and adopts a distributed control system for collaborative control, including multi-module collaborative heat scheduling.

[0017] The beneficial effects of the present invention are:

[0018] The present invention is a thermal energy recovery system for a thermal power station. Compared with the prior art, the present invention realizes the step-by-step recovery of high-temperature, medium-temperature and low-temperature waste heat in boiler flue gas through the coordinated work of equipment such as a high-temperature air preheater, an economizer, a wet flue gas condenser, a flue gas desulfurization device and a heat pump system. Compared with traditional technologies, the energy utilization efficiency of the present invention is significantly improved: the comprehensive thermal energy utilization rate of the system is increased to more than 80%. Reduce flue gas and heat emissions, while reducing CO2 and pollutant emissions. Obtain additional income through waste heat power generation and regional heating, and reduce operating costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a system structure principle block diagram of the present invention. DETAILED DESCRIPTION

[0020] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments. The illustrative embodiments and descriptions of the present invention are used to explain the present invention but are not intended to limit the present invention.

[0021] like Figure 1 As shown: the present invention includes a high-temperature air preheater, an economizer, a flue gas desulfurization device, a first wet flue gas condenser, an ORC power generation system, a second wet flue gas condenser, and a heat pump system. The flue gas outlet of the boiler is output to the high-temperature air preheater and the economizer. The high-temperature air preheater preheats the air and guides part of the heat energy to the flue gas desulfurization device. The economizer recovers heat for heating boiler feed water and transmits the waste heat to the first wet flue gas condenser. The flue gas desulfurization device and the first wet flue gas condenser recover the waste heat of low-temperature flue gas as the heat source of the ORC power generation system. The ORC power generation system transmits electrical energy to the power grid. The second wet flue gas condenser further recovers the waste heat of flue gas of the ORC power generation system and serves as the heat source of the heat pump system. The heat pump system transmits the recovered heat source to the regional heating network.

[0022] High-temperature air preheater: Use the sensible heat of boiler flue gas to heat the air entering the boiler and increase the air temperature. Through this preheating process, the fuel consumption caused by the entry of low-temperature air during the boiler combustion process is reduced. The boiler combustion efficiency is significantly improved and the fuel usage is reduced.

[0023] Economizer: transfer part of the sensible heat in the flue gas to the boiler feed water through the heat exchanger, increase the feed water temperature, reduce the fuel consumption required for boiler heating, reduce the heat loss of the boiler, and reduce the discharge temperature of the high-temperature flue gas.

[0024] First wet flue gas condenser: Recover the sensible heat and latent heat of low-temperature flue gas, and capture more heat by condensing water vapor. Provide heat source for ORC power generation system. Utilize the latent heat of water vapor in flue gas to improve heat recovery efficiency.

[0025] Flue gas desulfurization device: Use wet or dry desulfurization technology to remove pollutants such as SO2 from flue gas while recovering heat. Realize dual recovery of pollutants and waste heat, and improve environmental friendliness.

[0026] ORC power generation system: uses low-boiling-point working fluid to absorb heat and evaporate, and drives the turbine to generate electricity, and then the condensed working fluid is circulated back. Low-grade thermal energy (such as waste heat of 100℃ to 150℃) can be used to achieve additional power generation.

[0027] Second wet flue gas condenser: Recover the residual heat in the exhaust gas discharged by the ORC power generation system, significantly reduce the exhaust gas temperature, provide heat source for the heat pump system, deeply recover low-temperature waste heat, and improve the overall energy utilization rate.

[0028] Heat pump system: Utilize the low-temperature heat source provided by the condenser, increase the temperature through the compressor, and convert the heat into high-temperature heat energy that can be used for district heating. This realizes the effective use of low-temperature heat energy and meets the heating needs.

[0029] Furthermore, the high-temperature air preheater is a spiral heat exchanger or a plate heat exchanger, or both.

[0030] The heat energy recovery method of the heat energy recovery system of a thermal power station according to the present invention comprises the following steps:

[0031] S1: The high-temperature flue gas generated by boiler combustion is output from the flue gas outlet and divided into two paths. The first path enters the high-temperature air preheater to preheat the air entering the boiler to improve combustion efficiency. The second path enters the economizer to heat the boiler feed water through heat exchange to reduce the energy consumption of boiler steam generation;

[0032] S2: The high-temperature air preheater preheats the air and transmits part of the heat energy to the flue gas desulfurization device, reducing the flue gas temperature through heat exchange, providing suitable working conditions for subsequent treatment, and providing energy to support the material reaction and dust removal process of the desulfurization process;

[0033] S3: The economizer transfers the sensible heat in the flue gas to the boiler feed water, increases the feed water temperature, and reduces the boiler heating burden. The low-temperature flue gas at the economizer outlet is transported to the first wet flue gas condenser and enters the low-temperature waste heat recovery stage;

[0034] S4: The first wet flue gas condenser recovers the sensible heat and latent heat in the low-temperature flue gas, providing a suitable heat source for the ORC power generation system. The flue gas desulfurization device combines the low-temperature flue gas of the wet flue gas condenser to further recover heat and reduce pollutant emissions, while serving as an auxiliary heat source for the ORC power generation system;

[0035] S5: The ORC power generation system utilizes the heat energy recovered from the first wet flue gas condenser and the flue gas desulfurization device to drive the turbine through the evaporation of the low-boiling-point working fluid to generate electrical energy, and the generated electrical energy is transmitted to the power grid;

[0036] S6: The exhaust gas discharged from the ORC power generation system further enters the second wet flue gas condenser to further recover the low-temperature waste heat in the flue gas, reduce the exhaust gas temperature, and the recovered heat energy is used as the heat source of the subsequent heat pump system;

[0037] S7: The heat pump system uses the low-temperature heat source provided by the second wet flue gas condenser to raise the heat to a usable temperature through heat pump technology, and transmits the extracted heat energy to the regional heating network to meet the heating needs of the factory area or nearby residents.

[0038] As an improvement, the thermal energy recovery system of the thermal power station optimizes the heat distribution between modules through real-time monitoring and intelligent adjustment to ensure maximum thermal energy utilization efficiency.

[0039] Specifically, the real-time monitoring and intelligent adjustment are composed of sensors, monitoring systems, data analysis and abnormality detection units, and intelligent adjustment units. The sensors are temperature sensors, pressure sensors, flow meters, and electric energy meters.

[0040] Temperature sensors: monitor the temperature of boiler flue gas outlet, high temperature air preheater, economizer, flue gas condenser, ORC system and heat pump.

[0041] Pressure sensor: monitors the pressure of ORC working fluid, flue gas duct and heating network.

[0042] Flow meter: monitors flue gas flow, boiler feed water flow, condensate flow, etc.

[0043] Energy metering: monitor the output power of the ORC power generation system.

[0044] The monitoring system centrally collects and displays the above sensor data, and displays the system operation status in real time through a friendly graphical interface. The data collection cycle is 0.1-1 seconds, ensuring real-time response to highly dynamic processes;

[0045] The data analysis and abnormality detection unit analyzes the fluctuation trend of temperature, pressure, flow and other data, detects whether the operating parameters are within the design range, predicts the parameter change trend under normal conditions, and judges the deviation; distinguishes between normal operating conditions and abnormal conditions (such as sensor failure, pipeline blockage, heat exchanger scaling, etc.), and issues real-time alarms for abnormalities such as over-temperature, over-pressure, and low flow to remind operation and maintenance personnel;

[0046] The intelligent regulating unit adopts a programmable logic controller for valve switching and pump speed regulation, and adopts a distributed control system for collaborative control, including multi-module collaborative heat scheduling.

[0047] Dynamic adjustment strategy:

[0048] Flue gas diversion regulation: By adjusting the valve, the flue gas diversion ratio is adjusted according to real-time demand: more high-temperature flue gas is allocated to the high-temperature air preheater to improve boiler efficiency. More low-temperature flue gas is allocated to the economizer or wet flue gas condenser to balance waste heat recovery.

[0049] ORC power generation efficiency optimization: Dynamically adjust the operating conditions (such as evaporation pressure and flow rate) according to the evaporation temperature and ambient temperature of the ORC working fluid. Reduce the ORC power generation when the load is low to supply more heat to the heating system.

[0050] Heat pump operation mode optimization: adjust the heat pump operation mode (such as working fluid flow rate and compressor power) according to the heating demand. Store excess heat in the thermal storage system when the load is low.

[0051] Flue gas condenser efficiency adjustment: adjust the water flow or circulation pump speed of the condenser to prevent waste of resources due to insufficient heat recovery or overcooling.

[0052] The technical solution of the present invention is not limited to the above-mentioned specific embodiments. All technical variations made according to the technical solution of the present invention fall within the protection scope of the present invention.

Claims

1. A thermal energy recovery system for a thermal power station, characterized in that: It includes a high-temperature air preheater, an economizer, a flue gas desulfurization device, a first wet flue gas condenser, an ORC power generation system, a second wet flue gas condenser, and a heat pump system. The flue gas outlet of the boiler is output to the high-temperature air preheater and the economizer. The high-temperature air preheater preheats the air and guides part of the heat energy to the flue gas desulfurization device. The economizer recovers heat for heating boiler feed water and transmits the waste heat to the first wet flue gas condenser. The flue gas desulfurization device and the first wet flue gas condenser recover the waste heat of low-temperature flue gas as the heat source of the ORC power generation system. The ORC power generation system transmits the electric energy to the power grid. The second wet flue gas condenser further recovers the waste heat of flue gas of the ORC power generation system and serves as the heat source of the heat pump system. The heat pump system transmits the recovered heat source to the regional heating network.

2. The thermal energy recovery system for a thermal power plant according to claim 1, characterized in that: The high-temperature air preheater is a spiral heat exchanger or a plate heat exchanger, or both.

3. The thermal energy recovery system of a thermal power plant according to claim 1, characterized in that: The heat energy recovery method of the heat energy recovery system of the thermal power station comprises the following steps: S1: The high-temperature flue gas generated by boiler combustion is output from the flue gas outlet and divided into two paths. The first path enters the high-temperature air preheater to preheat the air entering the boiler to improve combustion efficiency. The second path enters the economizer to heat the boiler feed water through heat exchange to reduce the energy consumption of boiler steam generation; S2: The high-temperature air preheater preheats the air and transmits part of the heat energy to the flue gas desulfurization device, reducing the flue gas temperature through heat exchange, providing suitable working conditions for subsequent treatment, and providing energy to support the material reaction and dust removal process of the desulfurization process; S3: The economizer transfers the sensible heat in the flue gas to the boiler feed water, increases the feed water temperature, and reduces the boiler heating burden. The low-temperature flue gas at the economizer outlet is transported to the first wet flue gas condenser and enters the low-temperature waste heat recovery stage; S4: The first wet flue gas condenser recovers the sensible heat and latent heat in the low-temperature flue gas, providing a suitable heat source for the ORC power generation system. The flue gas desulfurization device combines the low-temperature flue gas of the wet flue gas condenser to further recover heat and reduce pollutant emissions, while serving as an auxiliary heat source for the ORC power generation system; S5: The ORC power generation system utilizes the heat energy recovered from the first wet flue gas condenser and the flue gas desulfurization device to drive the turbine through the evaporation of the low-boiling-point working fluid to generate electricity, and the generated electricity is transmitted to the power grid; S6: The exhaust gas discharged from the ORC power generation system further enters the second wet flue gas condenser to further recover the low-temperature waste heat in the flue gas, reduce the exhaust gas temperature, and the recovered heat energy is used as the heat source of the subsequent heat pump system; S7: The heat pump system uses the low-temperature heat source provided by the second wet flue gas condenser to raise the heat to a usable temperature through heat pump technology, and transmits the extracted heat energy to the regional heating network to meet the heating needs of the factory area or nearby residents.

4. The thermal energy recovery system of a thermal power plant according to any one of claims 1 to 3, characterized in that: The thermal energy recovery system of the thermal power station optimizes the heat distribution among the modules through real-time monitoring and intelligent regulation, thereby ensuring maximum thermal energy utilization efficiency.

5. The thermal energy recovery system for a thermal power plant according to claim 4, characterized in that: The real-time monitoring and intelligent regulation are composed of sensors, monitoring systems, data analysis and abnormality detection units, and intelligent regulation units. The sensors are temperature sensors, pressure sensors, flow meters, and electric energy meters. The monitoring system centrally collects and displays the data of the above sensors, and displays the system operation status in real time through a friendly graphical interface; the data analysis and abnormality detection unit analyzes the fluctuation trend of data such as temperature, pressure, and flow, detects whether the operating parameters are within the design range, predicts the parameter change trend under normal circumstances, and judges deviations; the intelligent regulation unit uses a programmable logic controller for valve switching and pump speed adjustment, and adopts a distributed control system for collaborative control, including multi-module collaborative heat scheduling.

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