Secondary air heater heat source system

Abstract

The utility model relates to a kind of secondary air heater heat source system, and the system includes flue gas cooling module, low-pressure heating module, warm air module and warm air heater water inlet total door. Among them, the water outlet pipeline of low-pressure heating module is communicated with the water inlet pipeline of former stage flue gas cooler and the water inlet pipeline of rear stage flue gas cooler respectively;The water inlet pipeline of warm air module is communicated with the water outlet pipeline of former stage flue gas cooler and the water outlet pipeline of low-pressure heating module respectively, and the water outlet pipeline of warm air module is communicated with the water inlet pipeline of low-pressure heating module. Above-mentioned secondary air heater heat source system, warm air module is connected in parallel with former stage flue gas cooler, uses the water inlet of former stage flue gas cooler as warm air heater heat source, medium returns low-pressure heating module after heat exchange, can eliminate air preheater cold section low temperature corrosion and heat storage element blockage phenomenon, avoid power station boiler air preheater heat storage element blockage fault and unit unplanned shutdown event occur, greatly reduce power station boiler unit damage loss.

Description

Technical Field

[0001] This utility model relates to the technical field of power plant boiler systems, and in particular to a secondary air heater heat source system. Background Technology

[0002] Boiler systems in thermal power plants typically employ a two-stage flue gas cooler design, integrated with the turbine's low-pressure heater system to recover waste heat. While this system achieves initial energy savings, it suffers from significant technical flaws: the reliability of the two-stage flue gas cooler and the stability of the heat source for the air heater are both insufficient. Furthermore, when the downstream flue gas cooler shuts down, the circulating water system cannot circulate, severely impacting the safe and reliable operation of the boiler. Utility Model Content

[0003] Therefore, it is necessary to provide a secondary air heater heat source system that can provide a stable heat source to address the above problems.

[0004] A secondary air heater heat source system includes:

[0005] Flue gas cooling module, used to control flue gas temperature;

[0006] The low-pressure heating module has its outlet pipe connected to the inlet pipe of the flue gas cooling module, and its inlet pipe is connected to the outlet pipe of the flue gas cooling module.

[0007] The heating module has its water inlet pipe connected to the water outlet pipe of the flue gas cooling module and the water outlet pipe of the low-pressure heating module, respectively. The water outlet pipe of the heating module is connected to the water inlet pipe of the low-pressure heating module.

[0008] In one embodiment, the heating module includes a first heater and a second heater;

[0009] The water inlet pipes of the first and second air heaters are respectively connected to the water inlet pipes of the flue gas cooling module, and the water outlet pipes of the first and second air heaters are respectively connected to the water outlet pipes of the low-pressure heating module.

[0010] In one embodiment, the low-pressure heating module includes a No. 6 low-pressure heater and a No. 5 low-pressure heater;

[0011] The outlet pipe of the No. 6 low-pressure heater is connected to the inlet pipe of the No. 5 low-pressure heater and the inlet pipe of the flue gas cooling module, respectively. The inlet pipe of the No. 5 low-pressure heater is connected to the outlet pipe of the flue gas cooling module.

[0012] In one embodiment, a T-shaped fitting is provided on the water inlet pipe of the pre-stage flue gas cooler, so that the water inlet pipe of the flue gas cooling module is connected to the water outlet pipe of the low-pressure heating module and the water inlet pipe of the warm air module respectively.

[0013] In one embodiment, a main water inlet valve for the heater is provided between the tee fitting and the heater module.

[0014] In one embodiment, the main water inlet valve for the heater includes a manual main water inlet valve and an electric main water inlet valve connected in series.

[0015] In one embodiment, a heater temperature regulator is provided on the water inlet pipe of the heater module.

[0016] In one embodiment, drainage pipes are provided at the outlets of both the first and second heaters, and the drainage pipes are connected to a drainage ditch.

[0017] In one embodiment, a drain valve is provided on the drain pipe, which is used to control the drain flow rate of the drain pipe.

[0018] In one embodiment, both the water outlet pipes of the first heater and the second heater are equipped with shut-off valves, which are used to control the water flow rate of the heating module.

[0019] The aforementioned secondary air heater heat source system connects the outlet pipe of the low-pressure heating module to the inlet pipe of the flue gas cooling module and the inlet pipe of the air heater. Similarly, the inlet pipe of the low-pressure heating module is connected to the outlet pipe of the flue gas cooling module and the outlet pipe of the air heater. This allows the air heater to be connected in parallel with the pre-stage flue gas cooler, using the inlet water of the pre-stage flue gas cooler as the heat source for the air heater. After heat exchange, the medium returns to the low-pressure heating module. The inlet water of the pre-stage flue gas cooler comes from the high-temperature condensate of the low-pressure heating module, and its heat source is independent of the downstream flue gas cooler. Connecting the inlet pipe of the pre-stage flue gas cooler to the inlet pipe of the air heater ensures that the air heater can still operate normally even when the downstream flue gas cooler is shut down. This ensures that the secondary air temperature at the air preheater inlet can be stably maintained at around 60℃, eliminating low-temperature corrosion in the cold section of the air preheater and blockage of the heat storage elements. This prevents blockage failures of the heat storage elements in the power plant boiler air preheater and unplanned unit shutdowns, significantly reducing damage and losses to the power plant boiler unit. The heat-exchanged medium returns to the pre-stage flue gas cooler and eventually flows into the low-pressure heating module, avoiding energy waste. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the heat source system of a secondary air heater according to an embodiment of the present invention;

[0021] Figure 2 This is a schematic diagram of the heat source system of a secondary air heater according to another embodiment of the present invention.

[0022] Figure label:

[0023] 10. Flue gas cooling module; 110. Pre-stage flue gas cooler; 120. Post-stage flue gas cooler; 130. Tee fitting; 140. Manual main water inlet valve for heater; 150. Electric main water inlet valve for heater; 160. Heater temperature control component; 20. Low-pressure heating module; 210. No. 6 low-pressure heater; 220. No. 5 low-pressure heater; 230. No. 7 low-pressure heater; 30. Heater module; 310. First heater; 320. Second heater; 330. Drainage pipe; 331. Drain valve; 340. Shut-off valve; 350. Water inlet valve; 40. Air preheater; 50. Dust collector. Detailed Implementation

[0024] To make the above-mentioned objects, features, and advantages of this utility model more apparent and understandable, the specific embodiments of this utility model will be described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a full understanding of this utility model. However, this utility model can be implemented in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of this utility model. Therefore, this utility model is not limited to the specific embodiments disclosed below.

[0025] In the description of this utility model, it should be understood that the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc., indicating the orientation or positional relationship are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this utility model and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this utility model.

[0026] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this utility model, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0027] In this utility model, unless otherwise explicitly specified and limited, the terms "installation," "connection," "joining," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this utility model according to the specific circumstances.

[0028] In this utility model, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "on top of," and "over" the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0029] It should be noted that when an element is referred to as being "fixed to" or "set on" another element, it can be directly on the other element or there may be an intervening element. When an element is considered to be "connected to" another element, it can be directly connected to the other element or there may be an intervening element. The terms "vertical," "horizontal," "upper," "lower," "left," "right," and similar expressions used herein are for illustrative purposes only and do not represent the only possible implementation.

[0030] This utility model specifically addresses the optimization of the heat source system for the secondary air heater in a thermal power plant boiler. In a coal-fired power generation unit (such as the SG1036 / 17.44-M865 boiler configured in a 2×320MW unit of a certain plant), the boiler flue gas system adopts a balanced ventilation design, including components such as a primary air fan, a forced draft fan, and an induced draft fan. To improve energy efficiency, the system reduces the exhaust gas temperature to approximately 90.0℃ through a flue gas cooler and increases the secondary air temperature to approximately 60.0℃ through a heater. The heater adopts a four-tube coil arrangement in a counter-current flow, with dimensions of 6.7×3.4×2 (m×m×m), and its heat source depends on the flue gas cooler system.

[0031] The boiler system of a thermal power plant adopts a two-stage flue gas cooler design, which is integrated with the turbine low-pressure heater (low-pressure heater) system to achieve waste heat recovery. The traditional secondary air heater heat source system includes a flue gas cooler, an air heater heat source supply system, and a condensate flow path.

[0032] The flue gas cooler consists of a pre-stage flue gas cooler and a post-stage flue gas cooler. The pre-stage flue gas cooler receives the condensate from the outlets of low-pressure heaters No. 7 and No. 6, absorbs heat, and then enters low-pressure heater No. 5. The post-stage flue gas cooler is supplied with circulating water through an expansion tank, forming a closed loop (post-stage flue gas cooler → air heater → post-stage flue gas cooler).

[0033] Heat source supply for the air heater: The circulating water of the downstream flue gas cooler serves as the sole heat source for the air heater. The inlet water temperature is approximately 86.0℃, and the outlet water temperature is 60-70℃, ensuring that the secondary air temperature at the air preheater inlet remains stable at around 60.0℃.

[0034] Condensate flow path system: After the condensate from the outlets of low-pressure heaters No. 7 and No. 6 is combined, part of it enters the pre-stage flue gas cooler, and the other part is diverted through a three-way valve to the expansion tank as the water source for the post-stage flue gas cooler. This is intended to reduce the exhaust gas temperature and increase the air temperature, in line with energy-saving requirements.

[0035] However, traditional technologies rely excessively on a single heat source (the downstream flue gas cooler) and lack redundancy or backup solutions. While highly integrated, these systems are also vulnerable and cannot handle heat source switching demands during equipment failures. The downstream flue gas cooler operates in a harsh environment (low flue gas temperature, poor corrosion resistance of the tube bundle material), making it prone to leaks after prolonged operation. Leaks increase system resistance, affecting the safe operation of the electrostatic precipitator and induced draft fan, often forcing system shutdown. When the downstream flue gas cooler shuts down, its circulating water system ceases operation, depriving the air heater of its heat source. This directly results in the air preheater inlet secondary air temperature failing to maintain the design requirement of 60.0℃, exacerbating low-temperature corrosion in the cold section and blockage of heat storage elements. Each 320MW unit incurs losses exceeding 500,000 RMB annually due to downtime and efficiency reduction. Therefore, an optimized solution is urgently needed to ensure a stable heat source for the air heater even when the downstream flue gas cooler is shut down, improving system robustness while reducing maintenance and downtime risks, thereby eliminating safety hazards and economic losses.

[0036] In one exemplary embodiment, such as Figure 1 As shown, this utility model provides a secondary air heater heat source system, including: a flue gas cooling module 10, a low-pressure heating module 20 and a warm air module 30.

[0037] The flue gas cooling module 10 is used to control the flue gas temperature.

[0038] Optionally, the flue gas cooling module 10 includes a pre-stage flue gas cooler 110 and a post-stage flue gas cooler 120.

[0039] The water outlet pipe of the low-pressure heating module 20 is connected to the water inlet pipe of the flue gas cooling module 10.

[0040] Optionally, such as Figure 2As shown, X represents cold air, Y represents hot air, and Z represents hot flue gas from the economizer. The diagram also includes an air preheater 40 and a dust collector 50, both part of the power plant boiler system. The air preheater 40 is a heat exchange device in the boiler's tail flue, used to recover waste heat from the flue gas to preheat the combustion air (primary / secondary air) entering the boiler. The dust collector 50 is a flue gas purification device that adsorbs dust particles from the flue gas through a high-voltage electric field, ensuring emissions meet standards. The low-pressure heating module 20 includes a No. 5 low-pressure heater 220, a No. 6 low-pressure heater 210, and a No. 7 low-pressure heater 230. The condensate from the outlets of the No. 7 low-pressure heater 230 and the No. 6 low-pressure heater 210 enters the pre-stage flue gas cooler 110 to absorb heat, and can also be diverted to the expansion tank via a three-way pipe fitting 130 as a water source for the downstream system. The water outlet of the pre-stage flue gas cooler 110 returns to the No. 5 low-pressure heater 220 for further heating. The medium after heat exchange in the warm air module 30 is connected to the return water pipe of the pre-stage flue gas cooler 110 through the water outlet pipe, and finally flows into the inlet of the No. 5 low-pressure heater 220, forming a closed-loop heat recovery.

[0041] Optionally, the flue gas cooling module 10 is arranged in the flue between the outlet of the air preheater and the inlet of the electrostatic precipitator at the tail end of the power plant boiler, to reduce the exhaust gas temperature from the design value to approximately 90.0°C, thereby achieving waste heat recovery. The inlet of the pre-stage flue gas cooler 110 receives condensate from the low-pressure heating module 20, specifically the high-temperature water flowing from the outlets of low-pressure heaters 230 (number seven) and 210 (number six), at a temperature of approximately 86.0°C. The condensate after heat exchange in the pre-stage flue gas cooler 110 returns to the low-pressure heater 220 (number five) of the low-pressure heating module 20 via its outlet.

[0042] The water inlet pipe of the heating module 30 is connected to the water outlet pipe of the flue gas cooling module 10 and the water outlet pipe of the low-pressure heating module 20, respectively, and the water outlet pipe of the heating module 30 is connected to the water inlet pipe of the low-pressure heating module 20.

[0043] In the aforementioned secondary air heater heat source system, the inlet water for the pre-stage flue gas cooler 110 comes from the high-temperature condensate of the low-pressure heating module 20. Its heat source is independent of the subsequent flue gas cooler 120. The inlet pipe of the pre-stage flue gas cooler 110 is connected to the inlet pipes of the first air heater 310 and the second air heater 320. This ensures that even when the subsequent flue gas cooler 120 is shut down, the air heater module 30 can still operate normally, guaranteeing that the secondary air temperature at the air preheater inlet can be stably maintained at around 60℃. This eliminates low-temperature corrosion in the cold section of the air preheater and blockage of the heat storage elements, preventing blockage failures of the heat storage elements in the power plant boiler air preheater and unplanned unit shutdowns, significantly reducing damage and losses to the power plant boiler unit. The heat-exchanged medium returns to the pre-stage flue gas cooler 110 and ultimately flows into the low-pressure heating module 20, avoiding energy waste.

[0044] In one exemplary embodiment, such as Figure 1As shown, the heating module 30 includes a first heater 310 and a second heater 320.

[0045] The water inlet pipe of the first heater 310 and the water inlet pipe of the second heater 320 are respectively connected to the water inlet pipe of the pre-stage flue gas cooler 110, and the water outlet pipe of the first heater 310 and the water outlet pipe of the second heater 320 are respectively connected to the water outlet pipe of the low-pressure heating module 20.

[0046] Optionally, the heating module 30 includes a first heater 310 and a second heater 320. The water inlet pipes of the first heater 310 and the second heater 320 are connected in parallel to the water inlet pipe of the pre-stage flue gas cooler 110. The water outlet pipes of the first heater 310 and the second heater 320 converge and connect to the return water pipe of the pre-stage flue gas cooler 110, ultimately returning to the No. 5 low-pressure heater 220 area of ​​the low-pressure heating module 20. The heating module 30 is equipped with an inlet valve 350 and a return water valve, i.e., a shut-off valve 340, which supports single-sided isolation or overall isolation (closing the main valve and the return water valve) to ensure system flexibility and reliability. Under normal operating conditions, high-temperature condensate (86°C) is output from the low-pressure heating module 20, flows through the three-way branch of the flue gas cooling module 10, enters the heating module 30, heats the secondary air to 60°C, and the return water flows back into the low-pressure heating module 20.

[0047] In one exemplary embodiment, such as Figure 1 As shown, the low-pressure heating module 20 includes a sixth low-pressure heater 210 and a fifth low-pressure heater 220.

[0048] The outlet pipe of the No. 6 low-pressure heater 210 is connected to the inlet pipe of the No. 5 low-pressure heater 220 and the inlet pipe of the flue gas cooling module 10, respectively. The inlet pipe of the No. 5 low-pressure heater 220 is connected to the outlet pipe of the flue gas cooling module 10.

[0049] For example, the low-pressure heating module 20 is responsible for recovering waste heat from the turbine extraction steam to increase the condensate temperature and achieve energy-saving goals. It includes a No. 6 low-pressure heater 210 and a No. 5 low-pressure heater 220. The No. 6 low-pressure heater 210 is located midway through the thermal system and its function is to initially heat the low-temperature condensate pumped from the condensate pump. The No. 6 low-pressure heater 210 uses the extraction steam from the turbine's low-pressure cylinder as a heat source to heat the condensate to a moderate temperature. The No. 5 low-pressure heater 220 is located downstream of the system, close to the boiler feedwater end. The condensate has absorbed heat through the flue gas cooler before entering the No. 5 low-pressure heater, which further heats the condensate to a higher temperature. The No. 5 low-pressure heater ensures optimized boiler feedwater temperature, reduces energy waste, and ultimately improves the overall unit efficiency.

[0050] The condensate (after heating) from the outlet of low-pressure heater 210 (No. 6) is directly piped to the inlet of low-pressure heater 220 (No. 5). Before entering low-pressure heater 220, the condensate flows through flue gas cooling module 10 for waste heat recovery. The outlet pipe of low-pressure heater 210 is connected to the inlet of the pre-stage flue gas cooler 110 of flue gas cooling module 10. Specifically, the condensate from the outlet of low-pressure heater 210 and the condensate from the outlet of low-pressure heater 230 (No. 7) merge to form a single water flow that enters the pre-stage flue gas cooler 110. This design achieves heat source sharing, ensuring that the flue gas cooler reduces the exhaust gas temperature (to approximately 90.0°C) while providing a high-temperature water source for the system.

[0051] The inlet pipe of the No. 5 low-pressure heater 220 is connected to the outlet of the pre-stage flue gas cooler 110. After the condensate absorbs heat in the pre-stage flue gas cooler 110 (the water temperature rises), it returns through the outlet pipe and enters the No. 5 low-pressure heater 220 for final heating. This connection forms a closed-loop heat recovery chain, avoiding energy loss. The piping design uses standard industrial pipe materials (such as DN250) to ensure stable flow and low resistance.

[0052] In the above embodiment, the first air heater 310 and the second air heater 320 are connected in parallel with the pre-stage flue gas cooler 110 via the No. 5 low-pressure heater 220 and the No. 6 low-pressure heater 210, respectively, sharing the heat source provided by the No. 6 low-pressure heater 210. When the post-stage flue gas cooler 120 is shut down, the air heater module 30 can still obtain high-temperature condensate through this flow path. By directly connecting the air heater module 30 to the No. 6 low-pressure heater 210 and the No. 5 low-pressure heater 220, the risk of heat source interruption is reduced. When the post-stage flue gas cooler 120 is shut down, the air heater can still be put into normal operation, ensuring that the air preheater inlet air temperature is stable at around 60°C, eliminating corrosion and blockage.

[0053] In one exemplary embodiment, such as Figure 1 As shown, a T-fitting 130 is installed on the water inlet pipe of the flue gas cooling module 10, so that the water inlet pipe of the pre-stage flue gas cooler 110 is connected to the water outlet pipe of the low-pressure heating module 20 and the water inlet pipe of the warm air module 30 respectively.

[0054] For example, the tee fitting 130 can be of DN250-DN250-DN200 specifications, serving as a hub for heat source distribution. It diverts a portion of the high-temperature condensate from the inlet pipe of the pre-stage flue gas cooler 110 out of the flow, thereby establishing a dynamic connection between the pre-stage flue gas cooler 110, the low-pressure heating module 20, and the warm air module 30, thus solving the problem of single reliance on the heat source. One DN250 main port is directly connected to the inlet pipe of the pre-stage flue gas cooler 110, ensuring that condensate flows normally into the flue gas cooler for heat exchange. The other DN250 main port is connected to the output end of the low-pressure heating module 20, specifically the condensate collection pipe of the outlets of low-pressure heaters 210 and 230 (No. 6 and No. 7), allowing the tee to directly receive high-temperature condensate from the low-pressure heating module 20 as the system's main heat source. A DN200 branch port connects to the inlet header (DN200 pipe) of the air heater, connecting to the inlet pipes of the first air heater 310 (A side) and the second air heater 320 (B side) of the air heater module 30. At the air heater inlet, this header is also equipped with an electric shut-off valve 340 and a manual shut-off valve 340 (DN200) as a main control valve, enabling flexible flow adjustment.

[0055] The 130 tee fitting, when used with valve systems, supports various operating conditions:

[0056] Normal operation: Open the manual main water inlet valve 140, the electric main water inlet valve 150, the inlet valve 350, and the shut-off valve 340. The heater and the pre-stage flue gas cooler 110 will operate in parallel.

[0057] Fault isolation: If a single heater needs to be maintained, closing the manual shut-off valve 340 will cut off the branch of the single heater without affecting the operation of the pre-stage flue gas cooler 110;

[0058] Heat source switching: When the downstream flue gas cooler 120 is shut down, the tee fitting 130 allows the heating module 30 to obtain heat directly from the low-pressure heating module 20 without going through the downstream flue gas cooler 120, thus avoiding interruption; ensuring the robustness of the system, with mutual backup between modules, so that if any module fails, the other parts can still work independently.

[0059] In the above embodiment, the tee fitting 130 physically integrates the flue gas cooling module, low-pressure heating module, and warm air module into a parallel system. The low-pressure heating module 20 provides the heat source (condensate). After being diverted through the tee fitting 130, part of the water flows into the pre-stage flue gas cooler 110, and the other part is directly supplied to the warm air module 30. Finally, the heat-exchanged medium returns to the low-pressure heating module 20, forming a closed loop. Through parallel connection, the warm air heater no longer relies on the easily leaky downstream flue gas cooler 120 circulation system, but instead utilizes the stable and reliable condensate from the low-pressure heating module 20 to ensure that the secondary air temperature remains constant at around 60°C.

[0060] The following embodiments specifically describe the flow control principle between the modules of this application.

[0061] In one exemplary embodiment, such as Figure 1 As shown, a manual main valve 140 for the heater inlet is provided between the tee fitting 130 and the heater module 30.

[0062] In one exemplary embodiment, such as Figure 1 As shown, an electric water inlet valve 150 for the heater is installed between the manual water inlet valve 140 and the heater module 30.

[0063] In one exemplary embodiment, such as Figure 1 As shown, a heater temperature regulating component 160 is installed on the water inlet pipe of the heater module 30.

[0064] The tee fitting 130 (DN250-DN250-DN200) and the heating module 30 form a three-stage series valve system through the manual main water inlet valve 140, the electric main water inlet valve 150, and the heating unit temperature regulator 160, achieving precise control and safe isolation of the heat source. The heating unit temperature regulator 160 can be a heating unit temperature regulating valve.

[0065] The manual main inlet valve 140 (DN200) for the air heater serves as the first-stage valve, connecting to the outlet side of the DN200 branch port of the tee fitting 130. A manual shut-off valve 340, providing a mechanical locking function, can be used to completely cut off the heat source supply to the air heater. Together with the DN250 manual shut-off valve 340 at the outlet of the air heater on both sides (A / B), the entire air heater module 30 is isolated, avoiding the risk of condensate leakage during maintenance.

[0066] The electric main water inlet valve 15 for the heater serves as a second-stage valve, located downstream of the manual main water inlet valve 140 and upstream of the heater module 30, connected in series with the manual main water inlet valve 140. An electric shut-off valve 340 can be used, supporting remote operation from the control room to cut off the heat source within seconds in case of sudden failures. It is open during normal operation and can be remotely closed to protect the heater module 30 in case of a sudden failure of the downstream flue gas cooler 120, thus implementing a redundant safety mechanism. In case of electric failure, it can rely on the upstream manual main valve for physical isolation.

[0067] The heater temperature regulator 160, acting as a third-stage valve, is located between the heater inlet electric main valve 150 and the branch pipe of the heater module 30, directly controlling the condensate flow rate entering the A / B side heaters. By adjusting the valve opening, the flow rate of high-temperature condensate (86℃) is changed in real time, stabilizing the outlet secondary air temperature at approximately 60℃. The heater temperature regulator 160 can automatically compensate for heat load fluctuations based on inlet air temperature variations, preventing air preheater corrosion due to insufficient air temperature during cold seasons. Combined with the heater's four-pipe coil counter-current arrangement, it maximizes heat exchange efficiency and ensures the attainment of the target air temperature.

[0068] The following examples illustrate the hydrophobic design of the heat source system for the secondary air heater.

[0069] In one exemplary embodiment, such as Figure 1 As shown, both the outlet of the first heater 310 and the outlet of the second heater 320 are equipped with drainage pipes 330, which are connected to the drainage ditch.

[0070] In one exemplary embodiment, such as Figure 1 As shown, a drain valve 331 is installed on the drain pipe 330, and the drain valve 331 is used to control the drain flow rate of the drain pipe 330.

[0071] For example, the drainage system is a key safety component of the heating module 30, designed to handle residual liquid discharge during equipment shutdown or maintenance. Each of the first and second air heaters 310 and 320 has an independent drainage pipe 330 at the bottom of its outlet pipe, totaling two pipes corresponding to the A and B sides of the equipment respectively. The drainage pipes 330 are located at the lowest point of the air heater outlet, utilizing gravity to naturally collect and guide residual condensate, preventing liquid accumulation in dead corners. All drainage pipes 330 ultimately converge at the 0-meter trench, located at the power plant's reference level (0-meter layer), serving as a centralized drainage facility to collect wastewater and transport it to the plant's wastewater treatment system. The trench design ensures gravity-fed wastewater discharge, requiring no additional power equipment; the system is simple and easy to operate.

[0072] Each drain pipe 330 is equipped with two manual drain valves 331. When the heater needs to be shut down for maintenance, the operator manually opens the drain valve 331 to drain the residual water in the pipe into the drain trench. If only the heater on side A needs maintenance, after closing the inlet and outlet water valves on side A, open its drain valve 331 to drain the residual liquid, while side B can continue to operate. In cold environments or when the equipment is shut down for a long time, timely drainage of liquid through the drain valves 331 prevents freezing expansion from damaging the pipes (risk of freezing and cracking) or causing corrosion due to impurities.

[0073] In one exemplary embodiment, such as Figure 1As shown, both the water outlet pipe of the first air heater 310 and the water outlet pipe of the second air heater 320 are equipped with shut-off valves 340, which are used to control the water flow rate of a single air heater.

[0074] For example, each of the first air heater 310 and the second air heater 320 is independently equipped with a manual shut-off valve 340, which is installed on the pipe downstream of the outlet manifold of each air heater and located upstream of the connection point of the drain pipe 330, to ensure that the air heater body can be completely isolated when the valve is closed.

[0075] For example, the secondary air heater heat source system is also adapted to the scenario where the pre-stage flue gas cooler 110 and the post-stage flue gas cooler 120 operate simultaneously, and the two work together to achieve flue gas temperature control and waste heat recovery.

[0076] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0077] The above embodiments only illustrate several implementation methods of this utility model, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the utility model patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this utility model, and these all fall within the protection scope of this utility model. Therefore, the protection scope of this utility model patent should be determined by the appended claims.

Claims

1. A secondary air heater heat source system, characterized in that, include: Flue gas cooling module, used to control flue gas temperature; A low-pressure heating module, wherein the water outlet pipe of the low-pressure heating module is connected to the water inlet pipe of the flue gas cooling module, and the water inlet pipe of the low-pressure heating module is connected to the water outlet pipe of the flue gas cooling module. The heating module has its water inlet pipe connected to the water outlet pipe of the flue gas cooling module and the water outlet pipe of the low-pressure heating module, and the water outlet pipe of the heating module is connected to the water inlet pipe of the low-pressure heating module.

2. The secondary air heater heat source system according to claim 1, characterized in that, The heating module includes a first heater and a second heater. The water inlet pipes of the first and second air heaters are respectively connected to the water inlet pipes of the flue gas cooling module, and the water outlet pipes of the first and second air heaters are respectively connected to the water outlet pipes of the low-pressure heating module.

3. The secondary air heater heat source system according to claim 1, characterized in that, The low-pressure heating module includes a No. 6 low-pressure heater and a No. 5 low-pressure heater; The outlet pipe of the No. 6 low-pressure heater is connected to the inlet pipe of the No. 5 low-pressure heater and the inlet pipe of the flue gas cooling module, respectively. The inlet pipe of the No. 5 low-pressure heater is connected to the outlet pipe of the flue gas cooling module.

4. The secondary air heater heat source system according to claim 1, characterized in that, The flue gas cooling module has a T-shaped fitting installed on its water inlet pipe, which connects the water inlet pipe of the flue gas cooling module to the water outlet pipe of the low-pressure heating module and the water inlet pipe of the warm air module.

5. The secondary air heater heat source system according to claim 4, characterized in that, A main water inlet valve for the heater is provided between the tee fitting and the heater module.

6. The secondary air heater heat source system according to claim 5, characterized in that, The main water inlet valve for the heater includes a manual main water inlet valve and an electric main water inlet valve connected in series.

7. The secondary air heater heat source system according to claim 1, characterized in that, A heater temperature regulating component is installed on the water inlet pipe of the heating module.

8. The secondary air heater heat source system according to claim 2, characterized in that, Both the outlet of the first heater and the outlet of the second heater are equipped with drainage pipes, which are connected to a drainage ditch.

9. The secondary air heater heat source system according to claim 8, characterized in that, A drain valve is installed on the drain pipe, and the drain valve is used to control the drain flow rate of the drain pipe.

10. The secondary air heater heat source system according to claim 2, characterized in that, Both the water outlet pipes of the first and second air heaters are equipped with shut-off valves, which are used to control the water flow rate of the air heater module.

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