A waste incineration flue gas waste heat recovery system and method

Abstract

This application relates to a waste incineration flue gas waste heat recovery system and method, belonging to the field of waste heat recovery and utilization. The waste heat recovery system includes a flue gas exhaust assembly, a flue gas heat exchanger, an electric heat exchange pipe, a heating network heat exchange pipe, and a condensate circulation assembly. The flue gas exhaust assembly guides the flue gas out; the condensate circulation assembly circulates condensate; the flue gas heat exchanger includes a shell, a baffle, a first heat exchange tube, and a second heat exchange tube; the first heat exchange tube is located between the shell and the baffle, and the second heat exchange tube is located inside the baffle; the baffle has a vent; when the vent is open, the flue gas flows through the second heat exchange tube for heat exchange; when the vent is closed, the baffle isolates the second heat exchange tube. The electric heat exchange pipe guides the condensate through the first heat exchange tube to exchange heat with the flue gas; the heating network heat exchange pipe guides the heating network water through the second heat exchange tube to exchange heat with the flue gas. This application has the effect of reducing the impact of heating on turbine power generation.

Description

Technical Field

[0001] This application relates to the field of waste heat recovery and utilization, and in particular to a waste incineration flue gas waste heat recovery system and method. Background Technology

[0002] With the rapid development of my country's economy, the demand for urban household waste disposal is increasing. As a mainstream disposal method, waste incineration contains a large amount of residual heat resources in its flue gas emissions.

[0003] Currently, in order to make reasonable use of the heat from the high-temperature flue gas generated by waste incineration, related technologies typically employ combined heat and power (CHP) mode. Specifically, on the one hand, heat exchangers are used to recover the heat from the high-temperature flue gas and preheat the condensate flowing back to the turbine, thereby reducing the coal consumption of the generator set; on the other hand, to meet the urban heating demand, a portion of the working steam (i.e., extracted steam) is usually extracted from the turbine and used to heat the urban heating network circulating water through the heating network heater, thus achieving the cascade utilization of energy.

[0004] However, when the heating load demand is high in winter, in order to ensure heating supply, the steam extraction rate of the steam turbine must be increased, which reduces the amount of steam that the steam turbine can use for power generation, thus affecting the power generation. Summary of the Invention

[0005] To reduce the impact of heating on the power generation of steam turbines, this application provides a waste incineration flue gas waste heat recovery system and method.

[0006] Firstly, the waste incineration flue gas waste heat recovery system provided in this application adopts the following technical solution: A waste incineration flue gas waste heat recovery system includes a flue gas exhaust assembly, a flue gas heat exchanger, an electric heat exchange pipe, a heating network heat exchange pipe, and a condensate circulation assembly. The smoke exhaust assembly is used to guide the smoke out; the condensate circulation assembly is used to circulate condensate. The flue gas heat exchanger includes a shell, a baffle, a first heat exchange tube, and a second heat exchange tube; the first heat exchange tube is located between the shell and the baffle, and the second heat exchange tube is located inside the baffle; the baffle is provided with a vent. When the vent is opened, the flue gas flows through the second heat exchange tube for heat exchange; When the blocking member closes the vent, the blocking member isolates the second heat exchange tube.

[0007] The electric heat exchange pipe is used to guide condensate through the first heat exchange pipe to exchange heat with flue gas; the heating network heat exchange pipe is used to guide heating network water through the second heat exchange pipe to exchange heat with flue gas.

[0008] By adopting the above technical solution, during winter heating, by opening the ventilation openings, the high-temperature flue gas can exchange heat with the first heat exchange tube and the second heat exchange tube simultaneously, realizing dual heating of condensate and heating network water, and making full use of the waste heat of flue gas.

[0009] During the non-heating season, by closing the vents, the baffles insulate the second heat exchange tube from the high-temperature flue gas, reducing the possibility of stagnant water in the second heat exchange tube being damaged by overpressure due to heat or the tube wall accumulating ash and hardening. At the same time, closing the vents allows the flue gas to flow only through the space between the shell and the baffles, improving the reliability of the contact between the flue gas and the first heat exchange tube, thereby increasing the heat exchange effect between the flue gas and the first heat exchange tube and improving the power generation efficiency.

[0010] Optionally, the blocking component includes a support base, a sealing plate, and a driving component; the vent is disposed on the support base; the driving component is disposed on the housing, the support base is disposed inside the housing, the second heat exchange tube is located inside the support base, and the sealing plate is connected to the driving component; the driving component drives the sealing plate to move, opening or closing the vent.

[0011] By adopting the above technical solution, the movement of the sealing plate on the support base is controlled by the driving component, realizing the automatic control of the opening and closing of the ventilation opening, so that the system can easily switch between heating mode and non-heating mode.

[0012] Optionally, the condensate circulation assembly includes a condenser, a first preheating element, a deaerator, and a condensate pipeline; the condenser, the first preheating element, and the deaerator are connected through the condensate pipeline. The condenser is used to form condensate; the first preheater is used to preheat the condensate; the deaerator is used to remove oxygen from the condensate; the condensate passes through the first preheater and the deaerator in sequence via the condensate pipe; the condensate pipe is connected to the electric heat exchange pipe.

[0013] By adopting the above technical solution, the condensate generated by the condenser is preheated by the preheating component, which reduces the energy consumption required for subsequent heating. At the same time, the deaerator removes oxygen from the condensate, which effectively reduces the possibility of oxidation and corrosion of pipelines and boilers and improves the safety of system operation.

[0014] Optionally, the first preheating element is used to collect steam leaking from the turbine shaft seal and preheat the condensate; the condensate enters the electric heat exchange pipeline after passing through the first preheating element.

[0015] By adopting the above technical solution, the first preheating component recovers the steam heat leaked from the turbine shaft seal, reducing energy loss and improving energy utilization.

[0016] Optionally, the condensate circulation assembly further includes a second preheating element, which is connected to the condensate pipeline and is located between the first preheating element and the deaerator; the second preheating element is used to extract steam from the turbine and preheat the condensate.

[0017] By adopting the above technical solution, the second preheating element is used to extract part of the steam from the turbine to preheat the condensate in multiple stages, thereby increasing the temperature of the condensate before it enters the deaerator when the flue gas heat exchanger is shut down.

[0018] Optionally, a heat dissipation assembly is also included, which includes a water tank and a detection element. The detection element is used to detect the temperature of the second heat exchange tube. When the second heat exchange tube is switched to be connected to the water tank, a water flow circulation is formed between the water tank and the second heat exchange tube.

[0019] By adopting the above technical solution, during non-heating periods, the second heat exchange tube is switched to be connected to the water tank, thereby reducing the temperature of the second heat exchange tube and reducing the risk of leakage at the connection due to the increase in water temperature. At the same time, it reduces the problem of fly ash caking caused by high temperature pipe walls and improves the service life of the second heat exchange tube.

[0020] Secondly, this application provides a method for recovering waste heat from waste incineration flue gas, using the aforementioned flue gas waste heat recovery system, comprising the following steps: S1. The exhaust assembly guides the flue gas through the flue gas heat exchanger. S2. Adjust the flow path of condensate according to the operating status of the flue gas heat exchanger; when the flue gas heat exchanger is in normal use, the condensate is allowed to return to the condensate circulation assembly after heat exchange through the first heat exchange tube; when the flue gas heat exchanger is out of use, the condensate is allowed to pass through the condensate circulation assembly. S3. Adjust the opening and closing state of the blocking component according to the heating demand; S4. When heating is required, the blocking member opens the vent to allow the flue gas to exchange heat with the second heat exchange tube; when heating is not required, the blocking member closes the vent to isolate the second heat exchange tube from the flue gas.

[0021] By adopting the above technical solution, the system's operating status can be flexibly adjusted according to seasonal changes. While ensuring heating needs in winter, the system also protects the equipment and improves power generation efficiency by isolating the second heat exchange tube during the non-heating season.

[0022] Optionally, in step S2, when the flue gas heat exchanger is shut down, the condensate passes sequentially through the first preheating element, the second preheating element, and the deaerator.

[0023] By adopting the above technical solution, when the flue gas heat exchanger is shut down due to maintenance or malfunction, the condensate can be switched to another path to enter the deaerator, ensuring the continuity of the steam turbine power generation process, reducing downtime accidents caused by local equipment maintenance, and improving the reliability of power plant operation.

[0024] Optionally, in step S4, when the detection element detects that the temperature of the second heat exchange tube has reached a preset value, a water circulation is formed between the second heat exchange tube and the water tank.

[0025] By adopting the above technical solution, active thermal protection of the second heat exchange tube is achieved during the non-heating season, reducing the possibility of overheating damage to the flue gas heat exchanger and further improving the stability of system operation.

[0026] In summary, this application includes at least one of the following beneficial technical effects:

[0027] 1. With the flue gas heat exchanger of this application, during winter heating, by opening the vents, high-temperature flue gas can simultaneously exchange heat with the first and second heat exchange tubes, achieving dual heating of condensate and heating network water, and making full use of the waste heat of the flue gas; during the non-heating season, by closing the vents, the baffles insulate the second heat exchange tube from the high-temperature flue gas, reducing the possibility of stagnant water in the second heat exchange tube being damaged by overpressure due to heating or the tube wall accumulating ash and hardening; at the same time, closing the vents allows the flue gas to flow only through the space between the shell and the baffles, effectively reducing the flow cross-section, accelerating the flue gas velocity, thereby improving the heat exchange effect between the flue gas and the first heat exchange tube, and improving the power generation efficiency;

[0028] 2. The water temperature is monitored in real time by the detection device, and the heat dissipation cycle is started when the water temperature reaches the preset value to carry the heat out to the water tank. This reduces the risk of leakage at the connection due to the increase in internal pressure caused by the rise in water temperature. At the same time, it reduces the problem of fly ash caking caused by high temperature pipe walls and improves the service life of the second heat exchange tube.

[0029] 3. The flue gas waste heat recovery method of this application can flexibly adjust the system operation status according to seasonal changes, and while ensuring the heating needs in winter, it can protect the equipment and improve the power generation efficiency by isolating the second heat exchange tube in the non-heating season. Attached Figure Description

[0030] Figure 1 This is a schematic diagram of the overall structure of a waste incineration flue gas waste heat recovery system according to Embodiment 1 of this application;

[0031] Figure 2 This is a schematic diagram of the structure of a waste incineration flue gas heat exchanger, heat network heat exchange pipe and heat dissipation components of a waste incineration flue gas waste heat recovery system according to Embodiment 1 of this application;

[0032] Figure 3 This is a schematic diagram of the structure of a flue gas heat exchanger in a waste incineration flue gas waste heat recovery system according to Embodiment 1 of this application;

[0033] Figure 4 This is a structural cross-sectional view of a flue gas heat exchanger in a waste incineration flue gas waste heat recovery system according to Embodiment 1 of this application;

[0034] Figure 5 This is Embodiment 1 of the present application, a waste incineration flue gas waste heat recovery system. Figure 4 Enlarged view of a portion of point A inside;

[0035] Figure 6 This is a schematic diagram of the structure of the first heat exchange tube and the baffle in a waste incineration flue gas waste heat recovery system according to Embodiment 1 of this application;

[0036] Figure 7 This is an exploded structural diagram of the sealing plate and support base in a waste incineration flue gas waste heat recovery system according to Embodiment 1 of this application.

[0037] In the diagram: 1. Smoke exhaust assembly; 11. Exhaust fan; 12. Chimney; 2. Flue gas heat exchanger; 21. Shell; 211. Inlet; 212. Outlet; 213. Drain; 22. Blocking component; 221. Support base; 2211. Ventilation opening; 2212. Sliding block; 222. Sealing plate; 2221. Slide groove; 223. Driving component; 23. First heat exchange tube; 24. Second heat exchange tube; 3. Electric heat exchange pipe; 31. Condensate heat exchange inlet pipe; 32. Condensate heat exchange outlet pipe; 33. First valve; 3 4. First circulating pump; 4. Heat exchanger pipe; 41. Heat exchanger inlet pipe; 42. Heat exchanger outlet pipe; 43. Second valve; 44. Second circulating pump; 5. Condensate circulation assembly; 51. Condenser; 52. First preheating component; 53. Deaerator; 54. Condensate pipe; 55. Second preheating component; 56. Third valve; 57. Third circulating pump; 6. Heat dissipation assembly; 61. Water tank; 62. Heat dissipation inlet pipe; 63. Heat dissipation outlet pipe; 64. Fourth valve; 65. Fourth circulating pump; 66. Detection component. Detailed Implementation

[0038] The following is in conjunction with the appendix Figure 1-7 This application will be described in further detail.

[0039] Example 1 Embodiment 1 of this application discloses a waste incineration flue gas waste heat recovery system, such as Figure 1 and Figure 2 As shown, the flue gas waste heat recovery system includes a flue gas exhaust assembly 1, a flue gas heat exchanger 2, an electric heat exchange pipe 3, a heat network heat exchange pipe 4, a condensate circulation assembly 5, and a heat dissipation assembly 6.

[0040] Specifically, such as Figure 1 As shown, the flue gas exhaust assembly 1 includes an induced draft fan 11 and a chimney 12, with the induced draft fan 11 located between the flue gas heat exchanger 2 and the chimney 12. Driven by the induced draft fan 11, the high-temperature flue gas generated from waste incineration passes sequentially through the flue gas heat exchanger 2 and the induced draft fan 11 before being discharged from the chimney 12. Before entering the flue gas heat exchanger 2, the high-temperature flue gas undergoes acid removal and dust removal treatment, thereby reducing corrosive components in the flue gas and minimizing the impact on the service life of the flue gas heat exchanger 2.

[0041] like Figure 1 As shown, the condensate circulation assembly 5 includes a condenser 51, a first preheating element 52, a second preheating element 55, a deaerator 53, and a condensate pipeline 54. A third valve 56 and a third circulation pump 57 are installed on the condensate pipeline 54. The third valve 56 is a solenoid valve. Steam from the turbine enters the condenser 51 to form condensate, which flows through the condensate pipeline 54 under the drive of the third circulation pump 57. The first preheating element 52 is a shaft seal heater, used to preheat the condensate using steam leaking from the turbine shaft seal. The second preheating element 55 is a low-pressure heater, used to extract some steam from the turbine to preheat the condensate. As the condensate passes sequentially through the first preheating element 52 and the second preheating element 55, the first and second preheating elements preheat the condensate, thereby reducing coal consumption in the boiler. Deaerator 53 is used to remove oxygen from condensate, reducing the possibility of boiler rust.

[0042] like Figure 3 and Figure 4 As shown, the flue gas heat exchanger 2 includes a shell 21, a baffle 22, a first heat exchange tube 23 and a second heat exchange tube 24, wherein the baffle 22 includes a support base 221, a sealing plate 222 and a driving component 223.

[0043] Specifically, such as Figure 4 As shown, the casing 21 has an air inlet 211 and an air outlet 212. Driven by the induced draft fan 11, the flue gas enters through the air inlet 211 and exits through the air outlet 212. At the same time, the casing 21 also has a drain port 213 to facilitate the discharge of liquid generated during the heat exchange process when the flue gas heat exchanger 2 is under maintenance.

[0044] like Figure 4 and Figure 5As shown, the first heat exchange tube 23 is fixedly installed inside the shell 21 and located in the cavity formed between the shell 21 and the support base 221. The second heat exchange tube 24 is fixedly installed inside the support base 221. The support base 221 is fixedly connected to the shell 21, and the sealing plate 222 is slidably connected to the support base 221. The sealing plate 222 has a sliding groove 2221, and a slider 2212 is fixedly connected to the support base 221. The slider 2212 is located within the sliding groove 2221. The cooperation between the slider 2212 and the sliding groove 2221 improves the stability of the relative sliding between the sealing plate 222 and the support base 221.

[0045] like Figure 4 , Figure 6 and Figure 7 As shown, the body of the drive component 223 is fixedly connected to the housing 21, and the output end of the drive component 223 is fixedly connected to the sealing plate 222. Preferably, the drive component 223 is a motor. A vent 2211 is provided on the support base 221. The drive component 223 drives the sealing plate 222 to slide on the support base 221, thereby opening or closing the vent 2211. Both the first heat exchange tube 23 and the second heat exchange tube 24 are spiral-shaped.

[0046] like Figure 1 As shown, the electric heat exchange pipe 3 includes a condensate heat exchange inlet pipe 31 and a condensate heat exchange outlet pipe 32. One end of the condensate heat exchange inlet pipe 31 is connected to the condensate pipe 54 and located between the first preheating element 52 and the second preheating element 55, while the other end is connected to the inlet of the first heat exchange tube 23. One end of the condensate heat exchange outlet pipe 32 is connected to the condensate pipe 54 and located between the deaerator 53 and the second preheating element 55, while the other end is connected to the outlet of the first heat exchange tube 23. A first valve 33, which is a solenoid valve, is installed on both the condensate heat exchange inlet pipe 31 and the condensate heat exchange outlet pipe 32. A first circulating pump 34 is installed on the condensate heat exchange inlet pipe 31. By cooperating with the condensate heat exchange inlet pipe 31 and the condensate heat exchange outlet pipe 32, the condensate, driven by the first circulating pump 34, can enter the flue gas heat exchanger 2 after being preheated by the first preheating element 52 to exchange heat with the high-temperature flue gas, thereby realizing the heating of the condensate and effectively utilizing the heat of the flue gas.

[0047] like Figure 2As shown, the heat exchange pipeline 4 includes a heat exchange inlet pipe 41 and a heat exchange outlet pipe 42. The heat exchange inlet pipe 41 is connected to the inlet of the second heat exchange pipe 24, and the heat exchange outlet pipe 42 is connected to the outlet of the second heat exchange pipe 24. A second valve 43, which is a solenoid valve, is installed on both the heat exchange inlet pipe 41 and the heat exchange outlet pipe 42. A second circulation pump 44 is installed on the heat exchange inlet pipe 41. The heat exchange water in the heat network pipeline enters the second heat exchange pipe 24 through the heat exchange inlet pipe 41 and exchanges heat with the flue gas. After that, it returns to the heat network pipeline through the heat exchange outlet pipe 42, thus achieving the heating of the heat exchange water and effectively utilizing the heat of the flue gas.

[0048] It should be noted that when heating is required in winter, the drive unit 223 drives the sealing plate 222 to open the vent 2211, so that the high-temperature flue gas can exchange heat with the first heat exchange tube 23 and the second heat exchange tube 24 at the same time, thereby realizing the heating of condensate and heating network water.

[0049] When heating is not required, the drive unit 223 drives the sealing plate 222 to close. At this time, under the guidance of the support base 221 and the sealing plate 222, the high-temperature flue gas enters through the inlet 211 and exits through the outlet 212. During this process, the flue gas flows in the cavity between the support base 221 and the shell 21, which improves the reliability of heat exchange between the flue gas and the first heat exchange tube 23, thereby improving the heat exchange efficiency between the flue gas and the first heat exchange tube 23, and thus improving the power generation efficiency.

[0050] When heating is not provided, the hot water in the heating network is stagnant. As usage time increases, the flue gas temperature may heat the water stagnant in the second heat exchange tube 24. When the water temperature in the second heat exchange tube 24 rises, the pressure inside the tube increases, increasing the risk of damage and leakage at the connection between the tube 24 and the shell 21. Simultaneously, as the temperature of the second heat exchange tube 24 rises, the sticky fly ash adhering to it is prone to caking upon contact with the high-temperature tube wall, affecting the heat exchange performance of the tube 24.

[0051] like Figure 2As shown, in this application, the heat dissipation assembly 6 dissipates heat from the second heat exchange tube 24 during the non-heating season, reducing the possibility of affecting the service life of the second heat exchange tube 24. Specifically, the heat dissipation assembly 6 includes a water tank 61, a detection element 66, a heat dissipation inlet pipe 62, and a heat dissipation outlet pipe 63. The heat exchange inlet pipe 41 of the heating network is connected to the water tank 61 through the heat dissipation outlet pipe 63. The connection point between the heat dissipation outlet pipe 63 and the heat exchange inlet pipe 41 is located between the second valve 43 of the heat exchange inlet pipe 41 and the second heat exchange tube 24. The heat exchange outlet pipe 42 of the heating network is connected to the water tank 61 through the heat dissipation inlet pipe 62. The connection point between the heat dissipation inlet pipe 62 and the heat exchange outlet pipe 42 is located between the second valve 43 of the heat exchange outlet pipe 42 and the second heat exchange tube 24. The water tank 61 is connected to the outside air. The detection element 66 is installed on the second heat exchange tube 24 and is a temperature sensor used to detect the temperature of the second heat exchange tube 24. A fourth valve 64 is installed on both the heat dissipation inlet pipe 62 and the heat dissipation outlet pipe 63. The fourth valve 64 is a solenoid valve. A fourth circulation pump 65 is installed on the heat dissipation outlet pipe 63.

[0052] During the non-heating season, the second valves 43 on the heat exchange inlet pipe 41 and the heat exchange outlet pipe 42 of the heating network are closed. At the same time, the fourth valves 64 on the heat dissipation inlet pipe 62 and the heat dissipation outlet pipe 63 are opened. Driven by the fourth circulation pump 65, the water flows between the water tank 61 and the second heat exchange pipe 24, thereby carrying out the heat of the second heat exchange pipe 24.

[0053] Meanwhile, in this application, both the inner and outer surfaces of the flue gas heat exchanger 2 are coated with anti-corrosion material, improving the corrosion resistance of the flue gas heat exchanger 2. Additionally, the support base 221 and the sealing plate 222 are filled with insulation material, further reducing the impact of flue gas heat on the second heat exchange tube 24 during non-heating periods.

[0054] In addition, such as Figure 2 As shown, when the flue gas heat exchanger 2 needs to be shut down for maintenance, the first valve 33 on the condensate heat exchange inlet pipe 31 and the condensate heat exchange outlet pipe 32 are both closed. At this time, the third valve 56 is opened, so that the condensate flows to the deaerator 53 through the condensate pipe 54 under the drive of the third circulation pump 57, thereby reducing the possibility of the flue gas heat exchanger 2 being shut down and affecting the power generation operation.

[0055] The implementation principle of a waste incineration flue gas waste heat recovery system in Embodiment 1 of this application is as follows: When heating is needed in winter, the second valve 43 is opened, and the fourth valve 64 is closed, allowing the heating network water to exchange heat with the high-temperature flue gas through the second heat exchange tube 24.

[0056] When heating is not required, the fourth valve 64 opens, and the second valve 43 closes. When the detection element 66 detects that the water temperature in the second heat exchange tube 24 has reached the preset value, the fourth circulation pump 65 drives the water flow to circulate between the water tank 61 and the second heat exchange tube 24, thereby achieving the cooling of the second heat exchange tube 24.

[0057] Example 2

[0058] Embodiment 2 of this application discloses a method for recovering waste heat from waste incineration flue gas, using the flue gas waste heat recovery system of Embodiment 1 of this application, including the following steps: S1. The exhaust assembly 1 guides the flue gas through the flue gas heat exchanger 2; S2. Adjust the flow path of condensate according to the operating status of the flue gas heat exchanger 2; when the flue gas heat exchanger 2 is in normal use, the condensate is allowed to return to the condensate circulation assembly 5 after heat exchange through the first heat exchange tube 23; when the flue gas heat exchanger 2 is not in use, the condensate is allowed to pass through the condensate circulation assembly 5. S3. Adjust the opening and closing state of the blocking component 22 according to the heating demand; S4. When heating is required, the blocking member 22 opens the vent 2211 to allow the flue gas to exchange heat with the second heat exchange tube 24; when heating is not required, the blocking member 22 closes the vent 2211 to isolate the second heat exchange tube 24 from the flue gas.

[0059] Specifically, driven by the induced draft fan 11, the high-temperature flue gas after waste incineration passes through the flue gas heat exchanger 2, the induced draft fan 11 and the chimney 12 in sequence before being discharged. Before entering the flue gas heat exchanger 2, the flue gas undergoes acid removal and dust removal treatment to reduce its impact on the flue gas heat exchanger 2.

[0060] When it is necessary to use flue gas to heat the condensate, the first valve 33 on the condensate heat exchange inlet pipe 31 and the condensate heat exchange outlet pipe 32 is opened, and the third valve 56 is closed. At this time, driven by the first circulating pump 34, the condensate flowing out of the condenser 51 is first preheated by the first preheating element 52, and then sequentially passes through the condensate heat exchange inlet pipe 31, the first heat exchange tube 23, the condensate heat exchange outlet pipe 32, and the deaerator 53 before entering the boiler. The condensate exchanges heat with the high-temperature flue gas in the first heat exchange tube 23, effectively utilizing the heat of the flue gas.

[0061] When the flue gas heat exchanger 2 needs to be shut down for maintenance, the third valve 56 is opened, and the first valve 33 on the condensate heat exchange inlet pipe 31 and the condensate heat exchange outlet pipe 32 is closed. At this time, driven by the third circulating pump 57, the condensate flowing out of the first preheating element 52 passes through the second preheating element 55 and the deaerator 53 in sequence before returning to the boiler, allowing the steam turbine to continue generating electricity and reducing the possibility of power generation being affected by the shutdown of the flue gas heat exchanger 2.

[0062] When heating is required, the second valve 43 on the heat exchange inlet pipe 41 and the heat exchange outlet pipe 42 of the heating network is opened, and the fourth valve 64 on the heat dissipation inlet pipe 62 and the heat dissipation outlet pipe 63 is closed. At this time, driven by the second circulation pump 44, the heating network water passes through the heat exchange inlet pipe 41, the second heat exchange pipe 24 and the heat exchange outlet pipe 42 in sequence and returns to the heating network pipeline, where it exchanges heat with the flue gas in the second heat exchange pipe 24.

[0063] When heating is not required, open the fourth valve 64 on the heat dissipation inlet pipe 62 and the heat dissipation outlet pipe 63, and close the second valve 43 on the heat exchanger inlet pipe 41 and the heat exchanger outlet pipe 42. When the detection element 66 detects that the temperature of the second heat exchanger tube 24 has reached the preset value, the detection element 66 sends a feedback signal to the external controller, which controls the fourth circulation pump 65 to work, so that the water flows between the second heat exchanger tube 24 and the water tank 61, thereby reducing the possibility that the service life of the flue gas heat exchanger 2 will be affected by the excessive temperature of the second heat exchanger tube 24.

[0064] The above are all preferred embodiments of this application, and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1. A waste incineration flue gas waste heat recovery system, characterized in that, It includes a flue gas exhaust assembly (1), a flue gas heat exchanger (2), an electric heat exchange pipeline (3), a heat network heat exchange pipeline (4), and a condensate circulation assembly (5). The smoke exhaust assembly (1) is used to guide the smoke to be discharged; the condensate circulation assembly (5) is used to circulate condensate. The flue gas heat exchanger (2) includes a shell (21), a baffle (22), a first heat exchange tube (23), and a second heat exchange tube (24); the first heat exchange tube (23) is located between the shell (21) and the baffle (22), and the second heat exchange tube (24) is located inside the baffle (22); the baffle (22) is provided with a vent (2211). When the vent (2211) is opened, the flue gas flows through the second heat exchange tube (24) for heat exchange; When the blocking member (22) closes the vent (2211), the blocking member (22) isolates the second heat exchange tube (24); The electric heat exchange pipe (3) is used to guide condensate through the first heat exchange pipe (23) to exchange heat with flue gas; the heat network heat exchange pipe (4) is used to guide heat network water through the second heat exchange pipe (24) to exchange heat with flue gas.

2. The waste incineration flue gas waste heat recovery system according to claim 1, characterized in that, The blocking member (22) includes a support base (221), a sealing plate (222), and a driving member (223); the vent (2211) is disposed on the support base (221); the driving member (223) is disposed on the housing (21), the support base (221) is disposed inside the housing (21), the second heat exchange tube (24) is located inside the support base (221), and the sealing plate (222) is connected to the driving member (223); the driving member (223) drives the sealing plate (222) to move, opening or closing the vent (2211).

3. The waste incineration flue gas waste heat recovery system according to claim 1, characterized in that, The condensate circulation assembly (5) includes a condenser (51), a first preheating element (52), a deaerator (53), and a condensate pipeline (54); the condenser (51), the first preheating element (52), and the deaerator (53) are connected through the condensate pipeline (54). The condenser (51) is used to form condensate; the first preheater (52) is used to preheat the condensate; the deaerator (53) is used to remove oxygen from the condensate; the condensate passes through the first preheater (52) and the deaerator (53) in sequence via the condensate pipe (54); the condensate pipe (54) is connected to the electric heat exchange pipe (3).

4. The waste incineration flue gas waste heat recovery system according to claim 3, characterized in that, The first preheating element (52) is used to collect steam leaking from the turbine shaft seal and preheat the condensate; the condensate enters the electric heat exchange pipe (3) after passing through the first preheating element (52).

5. A waste incineration flue gas waste heat recovery system according to claim 3, characterized in that, The condensate circulation assembly (5) further includes a second preheating element (55), which is connected to the condensate pipeline (54) and is located between the first preheating element (52) and the deaerator (53). The second preheating element (55) is used to extract steam from the turbine and preheat the condensate.

6. The waste incineration flue gas waste heat recovery system according to claim 1, characterized in that, It also includes a heat dissipation component (6), which includes a water tank (61) and a detection element (66). The detection element (66) is used to detect the temperature of the second heat exchange tube (24). When the second heat exchange tube (24) is switched to be connected to the water tank (61), a water flow circulation is formed between the water tank (61) and the second heat exchange tube (24).

7. A method for recovering waste heat from waste incineration flue gas, using the recovery system as described in any one of claims 1-6, characterized in that, Includes the following steps: S1. The exhaust assembly (1) guides the flue gas through the flue gas heat exchanger (2); S2. Adjust the flow path of condensate according to the operating status of the flue gas heat exchanger (2); when the flue gas heat exchanger (2) is in normal use, the condensate is allowed to return to the condensate circulation assembly (5) after heat exchange through the first heat exchange tube (23); when the flue gas heat exchanger (2) is out of use, the condensate is allowed to pass through the condensate circulation assembly (5). S3. Adjust the opening and closing state of the blocking component (22) according to the heating demand; S4. When heating is required, the blocking member (22) opens the vent (2211) to allow the flue gas to exchange heat with the second heat exchange tube (24); when heating is not required, the blocking member (22) closes the vent (2211) to isolate the second heat exchange tube (24) from the flue gas.

8. A method for recovering waste heat from waste incineration flue gas according to claim 7, characterized in that, In step S2, when the flue gas heat exchanger (2) is shut down, the condensate passes through the first preheater (52), the second preheater (55), and the deaerator (53) in sequence.

9. A method for recovering waste heat from waste incineration flue gas according to claim 7, characterized in that, In step S4, when the detection element (66) detects that the temperature of the second heat exchange tube (24) reaches a preset value, a water circulation is formed between the second heat exchange tube (24) and the water tank (61).

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