Self-adaptive load combined preheating recovery system of power station boiler

Abstract

The invention relates to a power station boiler self-adaptive load combined preheating recovery system which comprises a preheating system, a monitoring module and a regulation and control module, and the preheating system comprises a heat pipe heat exchanger set and a heat pump system; the heat pipe heat exchanger set is used for recycling high-grade flue gas waste heat in a combustion system in a power station boiler to preheat water in a water supply pipeline. The heat pump system is used for recycling low-grade flue gas waste heat of a second flue in the power station boiler to preheat ambient air at the inlet end of the air conveying fan; the monitoring module is used for collecting flue gas data of a first flue and a second flue in the power station boiler and a current load mode of the power station boiler; and the regulation and control module is used for dynamically regulating operation parameters of the heat pipe heat exchanger group and / or the heat pump system based on the flue gas data of the power station boiler and the current load mode, so that the regulated heat pipe heat exchanger group and the regulated heat pump system are used for recovering flue gas waste heat for preheating. Waste heat efficient recovery and stable operation of the boiler within the range from full load to deep adjustment load are achieved.

Description

Technical Field

[0001] This application relates to the field of waste heat recovery and energy-saving technology for power plant boilers, and in particular to a combined preheating recovery system for adaptive load of power plant boilers. Background Technology

[0002] With the increasing proportion of renewable energy power, traditional coal-fired power plant boilers need to frequently participate in deep peak shaving, leading to greater load fluctuations. Under these conditions, boiler flue gas temperature fluctuates significantly, causing conventional waste heat recovery systems to face the following problems:

[0003] 1. Poor adaptability to heat source grade: Traditional heat pipe heat exchangers or single heat pump systems struggle to simultaneously recover high- and low-grade waste heat. For example, while heat pipe heat exchangers can efficiently recover high-grade flue gas waste heat at full load, their efficiency drops sharply under low load conditions due to the decrease in flue gas temperature. Although heat pumps can recover low-grade waste heat, their utilization of high-grade heat sources is insufficient when operating alone, limiting their overall energy-saving effect.

[0004] 2. Lack of dynamic control capability: Existing systems mostly adopt fixed operating modes and cannot adjust the heat recovery strategy in real time according to load changes. For example, although the flue gas waste heat recovery device disclosed in related technology (publication number: CN202210514736) adopts multi-stage heat exchange, it does not integrate an intelligent control module, and is prone to preheating efficiency fluctuations or equipment overload when the load changes suddenly.

[0005] 3. High equipment lifespan and maintenance costs: Conventional waste heat recovery devices are prone to corrosion and ash accumulation in low-temperature and high-humidity flue gas environments (such as the heat exchanger condensation problem mentioned in patent (publication number: CN202310875959)), resulting in frequent maintenance and reduced operational reliability.

[0006] To address the aforementioned issues, existing technologies attempt to improve waste heat recovery efficiency by modifying heat exchanger structures or optimizing heat pump parameters, but have not yet effectively resolved the technical contradiction between multi-grade waste heat synergistic recovery and wide-load adaptive operation. Related literature proposes a staged recovery strategy, but this strategy relies on manual valve opening adjustment, resulting in insufficient response speed and accuracy.

[0007] Therefore, there is an urgent need for a waste heat recovery system that can dynamically switch operating modes according to boiler load and integrate the advantages of multiple technologies to adapt to the flexible peak-shaving needs of the new energy power grid. Summary of the Invention

[0008] This application provides a combined preheating and recovery system for adaptive load of power plant boilers to solve the problems of poor heat source quality adaptability, insufficient dynamic control capability and low equipment reliability of existing power plant boiler waste heat recovery systems under wide load conditions.

[0009] This application provides a combined preheating and recovery system for adaptive load of a power plant boiler, applied to a power plant boiler. The power plant boiler includes a combustion system. The combined preheating and recovery system for adaptive load of the power plant boiler includes a preheating system, a monitoring module, and a control module. The preheating system includes a heat pipe heat exchanger group and a heat pump system. The heat pipe heat exchanger group consists of multiple parallel gravity heat pipes and is installed in the first flue between the economizer and the air preheater. It is used to recover the waste heat from the high-grade flue gas in the combustion system to preheat the water in the feedwater pipeline. The system includes a heat pump system for recovering waste heat from low-grade flue gas in the second flue to preheat ambient air at the inlet of the air delivery fan; a monitoring module for collecting flue gas data from the first and second flues in the power plant boiler and the current load mode of the power plant boiler; and a control module for dynamically adjusting the operating parameters of the heat pipe heat exchanger group and / or the heat pump system based on the flue gas data from the first and second flues and the current load mode of the power plant boiler, so as to utilize the adjusted heat pipe heat exchanger group and heat pump system to recover waste heat from the flue gas for preheating.

[0010] Optionally, the input end of the combustion system is connected to the air inlet pipe, the output end of the combustion system is connected to one end of the economizer and the first flue, the other end of the economizer is connected to the output end of the water supply pipe, the input end of the water supply pipe is connected to the heat pipe heat exchanger group, and the second flue is located between the air preheater and the chimney of the power plant boiler.

[0011] Optionally, the heat pipe heat exchanger group includes: a first group of heat pipe heat exchangers disposed in the first flue, used to absorb the waste heat of high-grade flue gas for evaporative heat exchange; and a second group of heat pipe heat exchangers disposed in the water supply pipe, the second group of heat pipe heat exchangers being connected to the first group of heat pipe heat exchangers, used to preheat the water in the water supply pipe by releasing heat from condensed steam.

[0012] Optionally, the heat pump system includes: an evaporator, a condenser, a compressor, and an expansion valve. The evaporator is arranged within the second flue and is used to recover low-grade waste heat from the second flue. One end of the compressor is connected to the other end of the condenser, and the other end of the compressor is connected to the evaporator within the second flue, used to pressurize the low-grade waste heat to obtain pressurized working gas. The condenser is used to condense and cool the pressurized working gas and deliver the cooled working liquid to the expansion valve. One end of the expansion valve is connected to one end of the condenser, and the other end of the expansion valve extends into the second flue, used to depressurize the cooled working liquid and return the cooled and depressurized working liquid to the evaporator. The condenser is also used to preheat ambient air, and the preheated air is sent to an air preheater for secondary preheating via an air delivery fan, and then sent to the combustion system for combustion via an air inlet pipe.

[0013] Optionally, the monitoring module includes: a data acquisition unit, used to acquire flue gas data from the first flue and the second flue, and the current load and current load mode of the power plant boiler; and a detection unit, used to detect that the current load mode of the power plant boiler is a first load mode when the current load of the power plant boiler is greater than or equal to a first preset load value, to detect that the current load mode of the power plant boiler is a second load mode when the current load of the power plant boiler is less than or equal to a second preset load value, and to detect that the current load mode of the power plant boiler is a third load mode when the current load of the power plant boiler is greater than the second preset load value and less than the first preset load value.

[0014] Optionally, it further includes: a heat pipe valve group, which is connected to the heat pipe heat exchanger group and is used to open or close the corresponding heat pipe heat exchanger in the heat pipe heat exchanger group.

[0015] Optionally, the control module includes: a first control unit, configured to control the heat pipe valve group to open all heat pipe heat exchanger groups and start the heat pump system to maximum power when the current load mode of the power plant boiler is the first load mode; a second control unit, configured to control the heat pipe valve group to close part of the heat pipe heat exchangers according to a preset ratio, while reducing the compressor frequency to a preset frequency and adjusting the speed of the air conveying fan when the current load mode of the power plant boiler is the second load mode; and a third control unit, configured to dynamically adjust the operating parameters of the heat pipe heat exchanger groups and the heat pump system according to the flue gas data of the first and second flues when the current load mode of the power plant boiler is the third load mode.

[0016] Optionally, the acquisition unit includes: a first set of sensors disposed in the first flue, for acquiring flue gas temperature, pressure and flue gas flow rate in the first flue; and a second set of sensors disposed in the second flue, for acquiring flue gas temperature, pressure and flue gas flow rate in the second flue.

[0017] Optionally, the surface of the first set of heat pipe heat exchangers is coated with an anti-corrosion coating, and the second set of heat pipe heat exchangers adopts a honeycomb fin structure.

[0018] Optionally, the contact surface between the evaporator and the second flue is a corrugated plate structure.

[0019] In the above embodiments, a heat pipe heat exchanger group recovers high-grade flue gas waste heat from the combustion system to preheat water in the feedwater pipeline, and a heat pump system recovers low-grade flue gas waste heat from the second flue to preheat ambient air at the inlet of the air delivery fan. A monitoring module collects flue gas data from the first and second flues within the power plant boiler, along with the current load mode of the boiler. A control module dynamically adjusts the operating parameters of the heat pipe heat exchanger group and / or the heat pump system based on this data, allowing the recovered waste heat to be used for preheating. This solves the problems of poor heat source grade adaptability, insufficient dynamic control capability, and low equipment reliability in existing power plant boiler waste heat recovery systems under wide load conditions. It integrates the advantages of high-efficiency heat transfer from heat pipes and low-grade heat pump recovery, improving boiler thermal efficiency, significantly reducing coal consumption and carbon emissions, and achieving efficient waste heat recovery and stable operation of the boiler within the full load to deep-load range.

[0020] Additional aspects and advantages of the present application will be given in part in the description below, and in part will become apparent from the description below, or will be learned through practice of the present application. Attached Figure Description

[0021] The above and / or additional aspects and advantages of the present application will become apparent and easily understood from the following description of the embodiments in conjunction with the accompanying drawings, in which:

[0022] Figure 1 This is a schematic diagram of a combined preheating and recovery system for adaptive load of a power plant boiler, provided according to an embodiment of this application.

[0023] Figure 2 This is a schematic diagram of a combined preheating and recovery system for adaptive load of a power plant boiler according to a specific embodiment of this application;

[0024] Figure 3 This is a partial structural schematic diagram of a heat pipe heat exchanger assembly according to an embodiment of this application;

[0025] Figure 4This is a schematic diagram of heat transfer within a heat pipe heat exchanger assembly according to an embodiment of this application;

[0026] Figure 5 This is a schematic diagram of heat transfer in a first flue and a second flue according to an embodiment of this application;

[0027] Figure 6 This is a schematic diagram of the working fluid circulation path and air preheating path of a heat pump system according to an embodiment of this application;

[0028] Figure 7 This is a schematic diagram of the working fluid circulation path of a heat pump system according to an embodiment of this application;

[0029] Figure 8 This is a schematic diagram of the control process under deep load mode according to an embodiment of this application. Detailed Implementation

[0030] The following describes in detail embodiments of the present application, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present application, and should not be construed as limiting the present application.

[0031] The following describes a combined preheating and recovery system for adaptive load of a power plant boiler, based on embodiments of the present application, with reference to the accompanying drawings. Addressing the problems mentioned in the background art regarding the poor adaptability of existing power plant boiler waste heat recovery systems under wide load conditions, insufficient dynamic control capabilities, and low equipment reliability, this application provides a combined preheating and recovery system for adaptive load of a power plant boiler. In this system, a heat pipe heat exchanger group recovers high-grade flue gas waste heat from the combustion system to preheat water in the feedwater pipeline, and a heat pump system recovers low-grade flue gas waste heat from the second flue to preheat ambient air at the inlet of the air delivery fan. A monitoring module collects flue gas data from the first and second flues within the power plant boiler and the current load mode of the power plant boiler. A control module dynamically adjusts the operating parameters of the heat pipe heat exchanger group and / or the heat pump system based on the flue gas data from the first and second flues and the current load mode of the power plant boiler, so as to utilize the adjusted heat pipe heat exchanger group and heat pump system to recover flue gas waste heat for preheating. This solves the problems of poor heat source quality adaptability, insufficient dynamic control capability, and low equipment reliability of existing power plant boiler waste heat recovery systems under wide load conditions. It integrates the advantages of high-efficiency heat transfer of heat pipes and low-grade heat recovery of heat pumps, improves boiler thermal efficiency, significantly reduces coal consumption and carbon emissions, and achieves efficient waste heat recovery and stable operation of boilers from full load to deep-load range.

[0032] Specifically, Figure 1This is a schematic diagram of a combined preheating and recovery system for adaptive load of a power plant boiler, provided as an embodiment of this application.

[0033] like Figure 1 As shown, the combined preheating and recovery system for the adaptive load of the power plant boiler includes: a preheating system 1, a monitoring module 2, and a control module 3.

[0034] Among them, the combined preheating and recovery system 10 for adaptive load of power plant boiler is applied to the power plant boiler, which includes a combustion system 40.

[0035] The preheating system 1 includes a heat pipe heat exchanger group 101 and a heat pump system 200. The heat pipe heat exchanger group 101 consists of multiple parallel gravity heat pipes and is located in the first flue A between the economizer 10 and the air preheater 20. It is used to recover the waste heat of high-grade flue gas in the combustion system 40 to preheat the water in the feedwater pipe 31. The heat pump system 200 is used to recover the waste heat of low-grade flue gas in the second flue B to preheat the ambient air at the inlet of the air conveying fan. The monitoring module 2 is used to collect flue gas data from the first flue A and the second flue B in the power plant boiler and the current load mode of the power plant boiler. The control module 3 is used to dynamically adjust the operating parameters of the heat pipe heat exchanger group 101 and / or the heat pump system 200 based on the flue gas data from the first flue A and the second flue B and the current load mode of the power plant boiler, so as to utilize the adjusted waste heat of flue gas recovered by the heat pipe heat exchanger group 101 and the heat pump system 200 for preheating.

[0036] In this embodiment, the first flue A can also be referred to as the high-temperature flue, the second flue B can be referred to as the clean flue, and the current load mode can be one of the full load mode, the deep load mode, and the transition load mode.

[0037] The specific structure is as follows: Figure 2 As shown, the heat pipe heat exchanger group 101 arranged in the first flue A between the economizer 10 and the air preheater 20 is used to recover the high-grade flue gas waste heat in the combustion system 40 to preheat the feedwater in the feedwater pipeline; the heat pump evaporator 201 arranged in the second flue B after the air preheater 20, as well as the heat pump condenser 202 and the air conveying fan 203 at the ambient air inlet end, are used to recover the low-grade waste heat in the combustion system 40 to preheat the ambient air required for combustion.

[0038] The heat pipe heat exchanger assembly 101 and the heat pump system 200 form an independent air-water dual preheating loop.

[0039] The control module 3 dynamically adjusts the number of heat pipe heat exchanger groups 101 in operation, the frequency of heat pump compressor 204 in heat pump system 200, and the speed of air conveying fan 203 based on the flue gas data of the first flue A and the second flue B in the power plant boiler collected by the monitoring module 2 and the current load mode of the power plant boiler.

[0040] Optionally, in some embodiments, the heat pipe heat exchanger group 101 includes: a first heat pipe heat exchanger 101a disposed in the first flue A for absorbing waste heat from high-grade flue gas for evaporative heat exchange; and a second heat pipe heat exchanger 101b disposed in the water supply pipe 31, the second heat pipe heat exchanger 101b being connected to the first heat pipe heat exchanger 101a for preheating the water in the water supply pipe 31 by releasing heat from condensed steam.

[0041] In some embodiments, the surface of the first heat pipe heat exchanger 101a is coated with an anti-corrosion coating, and the second heat pipe heat exchanger 101b adopts a honeycomb fin structure.

[0042] Specifically, such as Figure 2 As shown, the first group of heat pipe heat exchangers 101a is installed in the first flue A, and the second group of heat pipe heat exchangers 101b is connected to the first group of heat pipe heat exchangers 101a through a pipe. The second group of heat pipe heat exchangers 101b is embedded in the water supply pipe 31.

[0043] In this heat pipe heat exchanger group 101, each heat pipe uses a sodium-potassium alloy working fluid. The surface of the first heat pipe heat exchanger 101a is coated with a silicon nitride anti-corrosion coating with a thickness of 0.2 mm. The installation angle is 15° to the flue gas flow direction to reduce dust accumulation. The second heat pipe heat exchanger 101b adopts a honeycomb fin structure with a spacing of 5 mm. The inner wall of the second heat pipe heat exchanger 101b is polished. The structures of the first heat pipe heat exchanger 101a and the second heat pipe heat exchanger 101b are as follows: Figure 3 As shown.

[0044] The heat transfer between the first group of heat pipe heat exchangers 101a and the second group of heat pipe heat exchangers 101b is as follows: Figure 4 As shown, the high-temperature flue gas preheats the water in the water supply pipeline 31 through the first set of heat pipe heat exchangers 101a and the second set of heat pipe heat exchangers 101b.

[0045] The heat transfer within the first flue A and the second flue B is as follows: Figure 5 As shown, the heat transfer in the first flue A is as follows: flue gas → heat pipe working medium (sodium-potassium alloy) → second heat pipe heat exchanger 101b → feed water; the heat transfer in the second flue B is as follows: flue gas → heat pipe working medium (R1234ze) → condenser 202 → ambient air.

[0046] Optionally, in some embodiments, the heat pump system 200 includes: an evaporator 201, a condenser 202, a compressor 204, and an expansion valve 205. The evaporator 201 is arranged within a second flue B for recovering low-grade waste heat from the second flue B. One end of the compressor 204 is connected to the other end of the condenser 202, and the other end of the compressor 204 is connected to the evaporator 201 within the second flue B for pressurizing the low-grade waste heat to obtain pressurized working gas. One end of the condenser 202 is used to release heat from the pressurized working gas and further... The condenser cools down to become a working fluid liquid, and the cooled working fluid liquid is transported to the expansion valve 205. One end of the expansion valve 205 is connected to one end of the condenser 202, and the other end of the expansion valve 205 extends into the second flue B. It is used to depressurize the cooled working fluid liquid and return the cooled and depressurized working fluid liquid to the evaporator 201. The condenser 202 is also used to preheat the ambient air, and the preheated air is sent to the air preheater 20 for secondary preheating by the air conveying fan 203, and then sent to the combustion system 40 for combustion through the air inlet pipe 41.

[0047] In some embodiments, the contact surface between the evaporator 201 and the second flue B is a corrugated plate structure.

[0048] The working fluid of the heat pump system 200 is R1234ze, and the contact surface between the evaporator 201 and the second flue B is a corrugated plate structure.

[0049] The heat pump working fluid path in heat pump system 200 is as follows Figure 6 and 7 As shown: Evaporator 201 → Compressor 204 → Condenser 202 → Expansion Valve 205. Evaporator 201 is used to recover low-grade waste heat in the second flue B. Compressor 204 is used to pressurize the low-grade waste heat to obtain pressurized working gas. Condenser 202 releases heat from the pressurized working gas to the ambient air and condenses and cools it into working liquid. Expansion valve 205 depressurizes the waste heat of the cooled working liquid and returns the cooled and depressurized working liquid to evaporator 201.

[0050] The air preheating path of the heat pump system 200 is as follows: ambient air flows through the finned tube bundle of the condenser 202, is sent to the air preheater 20 by the air delivery fan 203, and enters the combustion system 40 for combustion through the air inlet pipe 41.

[0051] Optionally, in some embodiments, the monitoring module 2 includes: a data acquisition unit for acquiring flue gas data from the first flue A and the second flue B, and the current load and current load mode of the power plant boiler; and a detection unit for detecting the current load mode of the power plant boiler as a first load mode when the current load of the power plant boiler is greater than or equal to a first preset load value, detecting the current load mode of the power plant boiler as a second load mode when the current load of the power plant boiler is less than or equal to a second preset load value, and detecting the current load mode of the power plant boiler as a third load mode when the current load of the power plant boiler is greater than the second preset load value and less than the first preset load value.

[0052] It should be noted that the first preset load value and the second preset load value can be thresholds preset by the user, thresholds obtained through a limited number of experiments, or thresholds obtained through a limited number of computer simulations. No specific limitation is made here. For ease of explanation, in the embodiments of this application, the first preset load value is set to 85% of the rated load, and the second preset load value is set to 40% of the rated load.

[0053] In some embodiments, the data acquisition unit includes: a first set of sensors disposed in the first flue A for acquiring the flue gas temperature, pressure and flow rate in the first flue A; and a second set of sensors disposed in the second flue B for acquiring the flue gas temperature, pressure and flow rate in the second flue B.

[0054] The first set of sensors installed in the first flue A consists of: a flue gas temperature sensor 302a, a pressure sensor 302b, and a flow sensor 302c. The flue gas temperature sensor 302a is used to collect the flue gas temperature in the first flue A, the pressure sensor 302b is used to collect the pressure in the first flue A, and the flow sensor 302c is used to collect the flue gas flow rate in the first flue A. The configuration of the flue gas temperature sensor 302a, pressure sensor 302b, and flow sensor 302c is as follows: Figure 2 As shown.

[0055] The second set of sensors installed in the second flue B consists of: a flue gas temperature sensor 307a, a pressure sensor 307b, and a flow sensor 307c. The flue gas temperature sensor 307a is used to collect the flue gas temperature in the second flue B, the pressure sensor 307b is used to collect the pressure in the second flue B, and the flow sensor 307c is used to collect the flue gas flow rate in the second flue B. The configuration of the flue gas temperature sensor 307a, pressure sensor 307b, and flow sensor 307c is as follows: Figure 2 As shown.

[0056] The data acquisition unit also includes a temperature sensor 301 installed at the economizer inlet, temperature sensors 303 and 304 in the feedwater pipeline, and temperature sensors 305 and 306 at the air inlet and outlet of the air preheater, as detailed below. Figure 2 As shown. Among them, temperature sensor 301 at the inlet of economizer 10 is used to collect the temperature at the inlet of economizer 10, temperature sensor 303 at the inlet of water supply pipe is used to collect the temperature at the inlet of water supply pipe, temperature sensor 304 at the outlet of water supply pipe is used to collect the temperature at the outlet of water supply pipe, temperature sensor 305 at the air inlet of air preheater 20 is used to collect the temperature at the inlet of air preheater 20, and temperature sensor 306 at the air outlet of air preheater 20 is used to collect the temperature at the outlet of air preheater 20.

[0057] The further detection unit determines the current load mode of the power plant boiler as the first load mode (i.e., full load mode) when the current load is greater than or equal to the first preset load value (i.e., 85% of the rated load). When the current load is less than or equal to the second preset load value (40% of the rated load), the current load mode is determined as the second load mode (i.e., deep load adjustment mode). When the current load is greater than 40% of the rated load but less than 85% of the rated load, the current load mode is determined as the third load mode (i.e., transition load mode).

[0058] Optionally, in some embodiments, the above-described combined preheating and recovery system 10 for adaptive load of power plant boiler further includes: a heat pipe valve group 102, which is connected to the heat pipe heat exchanger group 101 and is used to open or close the corresponding heat pipe heat exchanger in the heat pipe heat exchanger group 101.

[0059] The opening and closing control of the heat pipe heat exchanger group 101 is achieved through the heat pipe valve group 102. The valve response time is ≤2 seconds and the opening and closing interval between adjacent valves is ≥10 seconds.

[0060] Optionally, in some embodiments, the control module 3 includes: a first control unit, used to control the heat pipe valve group 102 to open all heat pipe heat exchanger groups 101 and start the heat pump system 200 to maximum power when the current load mode of the power plant boiler is the first load mode; a second control unit, used to control the heat pipe valve group 102 to close part of the heat pipe heat exchangers according to a preset ratio when the current load mode of the power plant boiler is the second load mode, while reducing the frequency of the compressor 204 to a preset frequency and adjusting the speed of the air conveying fan 203; and a third control unit, used to dynamically adjust the operating parameters of the heat pipe heat exchanger groups 101 and the heat pump system 200 according to the flue gas data of the first flue A and the second flue B when the current load mode of the power plant boiler is the third load mode.

[0061] It should be noted that the preset ratio and preset frequency can be thresholds set by the user, thresholds obtained through a limited number of experiments, or thresholds obtained through a limited number of computer simulations; no specific limitations are made here.

[0062] The control module 3 uses a PLC controller and a fuzzy PID algorithm to receive monitoring data from the monitoring module 2 and output control signals to the heat pipe valve group 102 and the heat pump system 200.

[0063] The control logic of the control module 3 is as follows: based on the flue gas data of the first flue A and the second flue B collected by the monitoring module 2 and the current load mode of the power plant boiler, the control module dynamically adjusts the number of heat pipe heat exchanger groups 101 in operation, the operating frequency of the heat pump compressor 204, and the speed of the air conveying fan 203, specifically including:

[0064] When the power plant boiler is in full load mode: that is, when the current load of the power plant boiler is ≥85% of the rated load, the control module 3 controls the heat pipe valve group 102 to open all heat pipe heat exchanger groups 101 and start the heat pump system 200 to maximum power.

[0065] When the power plant boiler is in deep load adjustment mode, such as Figure 8 As shown: When the power plant boiler load is ≤40% of the rated load, the control module 3 controls the heat pipe valve group 102 to close part of the heat pipe heat exchanger group a and open the heat pipe heat exchanger group b according to the preset ratio (a:b). At the same time, the frequency of the compressor 204 is reduced to the preset frequency to maintain the clean flue gas temperature and the speed of the air conveying fan 203 is adjusted.

[0066] When the power plant boiler is in transition load mode, that is, when the current load of the power plant boiler is in the range of 40%-85% load, the control module 3 adjusts the operating parameters of the heat pipe valve group 102 and the heat pump system 200 according to the linear interpolation of flue gas temperature and flow rate.

[0067] Optionally, in some embodiments, the input end of the combustion system 40 is connected to the air inlet pipe 41, the output end of the combustion system 40 is connected to one end of the economizer 10 and the first flue A, the other end of the economizer 10 is connected to the output end of the water supply pipe 31, the input end of the water supply pipe 31 is connected to the heat pipe heat exchanger group 101, and the second flue B is located between the air preheater 20 and the chimney 60 of the power plant boiler.

[0068] The connections of the combustion system 40 to the economizer 10, the first flue A, and the air inlet pipe 41; the connections of the economizer 10 to the feedwater pipe 31 and the first flue A; the connections of the feedwater pipe 31 to the second group of heat exchangers in the heat pipe heat exchanger group 101; and the connections of the second flue B to the air preheater 20 and the chimney 60 of the power plant boiler are as follows: Figure 2 As shown.

[0069] To enable those skilled in the art to further understand the combined preheating and recovery system for adaptive load of power plant boilers according to the embodiments of this application, the following detailed description is provided in conjunction with specific embodiments, such as... Figure 2 As shown.

[0070] The combined preheating and recovery system for adaptive load of power plant boilers includes:

[0071] Heat pipe heat exchanger group 101: It consists of multiple parallel gravity heat pipes, including a first group of heat pipe heat exchangers 101a in the evaporation section and a second group of heat pipe heat exchangers 101b in the condensation section. The first group of heat pipe heat exchangers 101a is located in the first flue A and is connected to the second group of heat pipe heat exchangers 101b through a pipe. The second group of heat pipe heat exchangers 101b is located in the water supply pipe 31. The working fluid is sodium-potassium alloy and the working temperature range is 200-400℃.

[0072] Heat pump system 200: includes evaporator 201, condenser 202, compressor 204 and expansion valve 205. Evaporator 201 is arranged in the second flue B, and condenser 202 is connected to air delivery fan 203.

[0073] Monitoring module 2 monitors data from the first flue A and the second flue B, as well as the current load mode of the power plant boiler;

[0074] The control module 3 dynamically adjusts the operating parameters of the heat pipe heat exchanger group and / or heat pump system based on the data from the first flue A and the second flue B and the current load mode of the power plant boiler, so as to utilize the adjusted heat pipe heat exchanger group and heat pump system to recover waste heat from the flue gas for preheating.

[0075] Specific adjustment methods are as follows:

[0076] 1) If the boiler load is 100% (i.e. full load mode): the control module 3 controls the heat pipe valve group 102 to start all 12 heat pipe heat exchangers, preheat the feed water in the feed water pipe 31, the heat pump compressor 204 runs, the evaporator 201 absorbs the heat of the clean flue gas, and the condenser 202 preheats the air.

[0077] 2) Boiler load 30% (i.e. deep load adjustment mode): Control module 3 controls heat pipe valve group 102 to close 8 heat pipe heat exchangers, and the remaining 4 heat pipe heat exchangers are turned on to preheat the feed water in feed water pipe 31, control compressor 204 to reduce frequency, and condenser 202 to preheat ambient air.

[0078] In summary, the beneficial effects of this application are:

[0079] (1) Improved thermal efficiency: The overall thermal efficiency of the boiler is improved by recovering high and low grade waste heat through dual-loop coordinated recovery;

[0080] (2) Wide load adaptive: Enables stepless adjustment from full load to 20% deep load;

[0081] (3) Improve equipment reliability: The heat pipe heat exchanger group adopts silicon nitride anti-corrosion coating and honeycomb anti-clogging structure, and the heat pump system 200 selects low temperature resistant working fluid R1234ze to ensure stable operation in low temperature and high humidity flue gas.

[0082] The combined preheating and recovery system for adaptive load of power plant boilers proposed in this application utilizes a heat pipe heat exchanger group to recover high-grade flue gas waste heat from the combustion system to preheat water in the feedwater pipeline, and a heat pump system to recover low-grade flue gas waste heat from the second flue to preheat air. A monitoring module collects flue gas data from the first and second flues within the power plant boiler and the current load mode of the boiler. A control module dynamically adjusts the operating parameters of the heat pipe heat exchanger group and / or the heat pump system based on this data, thereby utilizing the adjusted parameters for preheating by recovering flue gas waste heat. This solves the problems of poor heat source grade adaptability, insufficient dynamic control capability, and low equipment reliability in existing power plant boiler waste heat recovery systems under wide load conditions. It integrates the advantages of high-efficiency heat transfer from heat pipes and low-grade heat recovery from heat pumps, improving boiler thermal efficiency, significantly reducing coal consumption and carbon emissions, and achieving efficient waste heat recovery and stable operation of the boiler within the full load to deep-load range.

[0083] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0084] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be understood to indicate or imply relative importance or implicitly specify the number of technical features indicated. Thus, a feature specified as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of this application, "N" means at least two, for example, two, three, etc., unless otherwise specifically defined.

Claims

1. A combined preheating and recovery system for adaptive load in a power plant boiler, applied to a power plant boiler, the power plant boiler including a combustion system, characterized in that, The power plant boiler adaptive load combined preheating and recovery system includes: a preheating system, a monitoring module, and a control module, wherein... The preheating system includes a heat pipe heat exchanger assembly and a heat pump system; The heat pipe heat exchanger assembly consists of multiple parallel gravity heat pipes and is located in the first flue between the economizer and the air preheater. It is used to recover the waste heat of the high-grade flue gas in the combustion system to preheat the water in the feedwater pipeline. A heat pump system is used to recover the waste heat of low-grade flue gas in the second flue of the power plant boiler to preheat the ambient air at the inlet of the air conveying fan. The monitoring module is used to collect flue gas data from the first and second flues inside the power plant boiler and the current load mode of the power plant boiler. The control module is used to dynamically adjust the operating parameters of the heat pipe heat exchanger group and / or the heat pump system based on the flue gas data of the first flue and the second flue and the current load mode of the power plant boiler, so as to utilize the adjusted heat pipe heat exchanger group and heat pump system to recover waste heat from the flue gas for preheating.

2. The combined preheating and recovery system for adaptive load of power plant boilers according to claim 1, characterized in that, The input end of the combustion system is connected to the air inlet pipe, the output end of the combustion system is connected to one end of the economizer and the first flue, the other end of the economizer is connected to the output end of the water supply pipe, the input end of the water supply pipe is connected to the heat pipe heat exchanger group, and the second flue is located between the air preheater and the chimney of the power plant boiler.

3. The combined preheating and recovery system for adaptive load of power plant boilers according to claim 2, characterized in that, The heat pipe heat exchanger assembly includes: The first set of heat pipe heat exchangers installed in the first flue is used to absorb the waste heat of high-grade flue gas for evaporative heat exchange. The second set of heat pipe heat exchangers is installed inside the water supply pipeline. The second set of heat pipe heat exchangers is connected to the first set of heat pipe heat exchangers and is used to preheat the water in the water supply pipeline by releasing heat from the condensed steam.

4. The combined preheating and recovery system for adaptive load of power plant boilers according to claim 3, characterized in that, The heat pump system includes: Evaporator, condenser, compressor, and expansion valve, among which, The evaporator is arranged in the second flue and is used to recover low-grade waste heat in the second flue. One end of the compressor is connected to the other end of the condenser, and the other end of the compressor is connected to the evaporator in the second flue, which is used to pressurize the low-grade waste heat to obtain pressurized working gas. One end of the condenser is used to release heat from the pressurized working gas, condense and cool it into a working liquid, and then deliver the cooled working liquid to the expansion valve. One end of the expansion valve is connected to one end of the condenser, and the other end of the expansion valve extends into the second flue. It is used to depressurize the cooled working liquid and return the cooled and depressurized working liquid to the evaporator. The condenser is also used to preheat the ambient air, and the preheated air is sent to the air preheater for secondary preheating by the air conveying fan, and then sent to the combustion system for combustion through the air inlet pipe.

5. The combined preheating and recovery system for adaptive load of power plant boilers according to claim 1, characterized in that, The monitoring module includes: The data acquisition unit is used to acquire flue gas data from the first flue and the second flue, as well as the current load and current load mode of the power plant boiler. The detection unit is configured to detect that the current load mode of the power plant boiler is a first load mode when the current load of the power plant boiler is greater than or equal to a first preset load value, detect that the current load mode of the power plant boiler is a second load mode when the current load of the power plant boiler is less than or equal to a second preset load value, and detect that the current load mode of the power plant boiler is a third load mode when the current load of the power plant boiler is greater than the second preset load value and less than the first preset load value.

6. The combined preheating and recovery system for adaptive load of power plant boilers according to claim 5, characterized in that, Also includes: A heat pipe valve assembly, which is connected to the heat pipe heat exchanger assembly, is used to open or close the corresponding heat pipe heat exchanger in the heat pipe heat exchanger assembly.

7. The combined preheating and recovery system for adaptive load of power plant boilers according to claim 6, characterized in that, The control module includes: The first control unit is used to control the heat pipe valve group to open all heat pipe heat exchanger groups and start the heat pump system to maximum power when the current load mode of the power plant boiler is the first load mode. The second control unit is used to control the heat pipe valve group to close part of the heat pipe heat exchanger according to a preset ratio when the current load mode of the power plant boiler is the second load mode, while reducing the frequency of the compressor to a preset frequency and adjusting the speed of the air conveying fan. The third control unit is used to dynamically adjust the operating parameters of the heat pipe heat exchanger group and the heat pump system based on the flue gas data of the first and second flues when the current load mode of the power plant boiler is the third load mode.

8. The combined preheating and recovery system for adaptive load of power plant boilers according to claim 5, characterized in that, The acquisition unit includes: The first set of sensors installed in the first flue is used to collect the flue gas temperature, pressure and flue gas flow rate in the first flue. The second set of sensors installed in the second flue is used to collect the flue gas temperature, pressure and flow rate in the second flue.

9. The combined preheating and recovery system for adaptive load of power plant boilers according to claim 3, characterized in that, The first set of heat pipe heat exchangers is coated with an anti-corrosion coating, and the second set of heat pipe heat exchangers adopts a honeycomb fin structure.

10. The combined preheating and recovery system for adaptive load of power plant boilers according to claim 4, characterized in that, The contact surface between the evaporator and the second flue is a corrugated plate structure.

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