An indirect heat exchange system for utilizing waste heat from flue gas at the tail end of a power plant boiler

Abstract

The present invention belongs to the field of heat exchangers, and specifically, is an indirect heat exchange system for utilizing waste heat from flue gas at the tail end of a power plant boiler, comprising an inlet and outlet flue of a flue gas heat exchanger; the middle of the inlet and outlet flue of the flue gas heat exchanger is connected with a flue gas heat exchanger body; the flue gas heat exchanger body is connected with a primary network circulating water pipeline; part of the primary network circulating water pipeline extends to the interior of the flue gas heat exchanger body; a flue gas heat exchanger water side inlet valve, an indirect heat exchanger heat source water inlet valve, an indirect heat exchanger heat source water outlet valve, a primary circulating water pump inlet valve, a primary circulating water pump, a primary circulating water pump outlet check valve, a primary circulating water pump outlet valve and a flue gas heat exchanger water side outlet valve are sequentially installed in the middle of the primary network circulating water pipeline; an indirect heat exchanger is added between the flue gas heat exchanger and the cold source working medium to isolate the flue gas from the cold source working medium, and the indirect heat exchanger is made of stainless steel, which is effectively anti-corrosive and ensures the safety of the operation of the cold source medium.

Description

Technical Field

[0001] The invention relates to the field of heat exchangers, in particular to an indirect heat exchange system used for utilizing waste heat of flue gas at the tail end of a power plant boiler. Background Art

[0002] A heat exchanger is a device that transfers part of the heat of a hot fluid to a cold fluid through heat conduction.

[0003] A flue gas heat exchanger is installed in the flue at the rear of the boiler, and the flue gas flows through the shell side of the heat exchanger and releases heat. The heat on the shell side of the heat exchanger is used to heat the cold source medium on the tube side, thereby achieving the purpose of utilizing the waste heat of the flue gas. Operational practice shows that since the flue gas temperature decreases after heat exchange, the moisture in the flue gas will condense on the heating surface of the flue gas heat exchanger. This moisture contains sulfur dioxide left after coal combustion, which causes a certain degree of corrosion to the heat exchange tubes, and the burst rate of the heat exchange tubes increases. With the occurrence of tube bursts, the condensed water in the flue gas will also enter the cold source medium, thereby polluting the cold source medium. This will lead to corrosion of the pipelines and equipment through which the cold source works, seriously affecting the safety of production, and also bringing disadvantages to the utilization of waste heat from flue gas;

[0004] Therefore, in order to solve the above problems, an indirect heat exchange system for utilizing the waste heat of flue gas at the tail end of a power plant boiler is proposed. Summary of the invention

[0005] In order to make up for the deficiencies of the prior art, at least one technical problem raised in the background technology is solved.

[0006] The technical solution adopted by the present invention to solve its technical problem is: the indirect heat exchange system for utilizing the waste heat of flue gas at the tail end of a power plant boiler described in the present invention comprises an inlet and outlet flue of a flue gas heat exchanger; the middle of the inlet and outlet flue of the flue gas heat exchanger is connected with a flue gas heat exchanger body; the flue gas heat exchanger body is connected with a primary network circulating water pipeline; part of the primary network circulating water pipeline extends to the interior of the flue gas heat exchanger body; a flue gas heat exchanger water side inlet valve, an indirect heat exchanger heat source water inlet valve, an indirect heat exchanger heat source water outlet valve, a primary circulating water pump inlet valve, a primary circulating water pump, a primary circulating water pump outlet check valve, a primary circulating water pump outlet valve and a flue gas heat exchanger water side outlet valve are sequentially installed in the middle of the primary network circulating water pipeline; the middle of the primary network circulating water pipeline is connected with The water supply pipeline; the middle of the water supply pipeline is connected with a pressure stabilizing tank; the primary network circulating water pipeline is installed with an indirect heat exchanger body at a position between the indirect heat exchanger heat source water inlet valve and the indirect heat exchanger heat source water outlet valve; the middle of the indirect heat exchanger body is connected with an indirect heat exchanger cold source water pipeline; the middle of the indirect heat exchanger cold source water pipeline is installed with an indirect heat exchanger cold source side bypass valve; the middle of the indirect heat exchanger cold source water pipeline is connected with an indirect heat exchanger cold source side inlet valve and an indirect heat exchanger cold source side outlet valve in sequence on both sides of the indirect heat exchanger cold source side bypass valve; the indirect heat exchanger cold source water pipeline between the indirect heat exchanger cold source side inlet valve and the indirect heat exchanger cold source side outlet valve extends into the indirect heat exchanger body; the flue gas enters the flue gas heat exchanger body from the flue gas heat exchanger inlet and outlet flues for heat exchange, and the flue gas after heat exchange is discharged from the flue gas heat exchanger body. The flue gas heat exchanger pipe side is connected to the external primary circulating water system. The primary circulating water system includes the primary network circulating water pipeline, valves (flue gas heat exchanger water side inlet valve, flue gas heat exchanger water side outlet valve, primary circulating water pump inlet valve, primary circulating water pump outlet check valve, primary circulating water pump outlet valve, indirect heat exchanger heat source water inlet valve, indirect heat exchanger heat source water outlet valve), primary circulating water pump, indirect heat exchanger body and water supply pipeline, and pressure regulating tank. After the indirect heat exchanger body on the flue gas heat exchanger tube side releases heat, it is sent to the flue gas heat exchanger body by the primary circulating water pump to absorb heat. The circulating water is closed-loop circulated in the primary network, and its water loss is very small. The system uses the external softened water supply pipeline for water supply, and the pressure regulating tank is used to stabilize the primary network. The secondary network of the system is the indirect heat exchanger cold source water pipeline. The cold source water exchanges heat with the primary network circulating water through the indirect heat exchanger. After absorbing heat, the cold source water is sent to the end user through the indirect heat exchanger outlet pipeline.

[0007] When the primary network needs maintenance or an accident occurs, open the bypass valve on the cold source side of the indirect heat exchanger, close the inlet valve and outlet valve on the cold source side of the indirect heat exchanger, and the secondary network will not be disturbed by the primary network and can operate normally.

[0008] Further, the indirect heat exchanger cold source side bypass valve is connected in parallel with the indirect heat exchanger cold source side inlet valve and the indirect heat exchanger cold source side outlet valve; the indirect heat exchanger cold source side inlet valve is connected in series with the indirect heat exchanger cold source side outlet valve.

[0009] Furthermore, the primary circulation water pump inlet valve, the primary circulation water pump, the primary circulation water pump outlet check valve and the primary circulation water pump outlet valve are arranged in parallel in the middle of the primary network circulating water pipeline.

[0010] Furthermore, a first positioning plate is fixedly connected to the middle of the primary network circulating water pipeline located inside the flue gas heat exchanger body; a second positioning plate is fixedly connected to the middle of the primary network circulating water pipeline; a heat sink is fixedly connected between the first positioning plate and the second positioning plate; the heat sink is in contact with the primary network circulating water pipeline; a water storage box is slidably connected to the middle of the primary network circulating water pipeline between the first positioning plate and the second positioning plate; a spring is connected between the water storage box and the first positioning plate; by providing a slidable water storage box in the middle of the primary network circulating water pipeline, when smoke passes through the inside of the flue gas heat exchanger body, the heat of the smoke passes through the primary network circulating water pipeline The heat is conducted to the fluid inside the primary network circulating water pipe through the heat sink to heat the fluid. When the water vapor mixed with the flue gas is liquefied on the primary network circulating water pipe and the heat sink, part of the liquid will flow into the water storage box. When there is a lot of liquid accumulated inside the water storage box, it will slide downward in the middle of the primary network circulating water pipe. At this time, the impurities remaining in the middle of the primary network circulating water pipe and the heat sink can be scraped off, reducing the residual impurities in the middle of the primary network circulating water pipe and the heat sink. At the same time, the residual condensed water in the middle of the flue gas heat exchanger body and the heat sink is reduced, reducing the corrosion problem caused by the condensed water of the flue gas on the primary network circulating water pipe and the heat sink.

[0011] Furthermore, a fixing rod is fixedly connected to the inner wall of the water storage box; a friction plate is fixedly connected to the end of the fixing rod close to the heat sink; a plurality of bristles are fixedly connected to the middle of the friction plate; the bristles are in contact with the heat sink; by providing bristles on the inner wall of the water storage box in contact with the heat sink, the bristles can clean the heat sink when the water storage box slides on the heat sink, further reducing residual impurities on the heat sink and reducing heat conduction of impurities to the heat sink and the primary network circulating water pipeline.

[0012] Furthermore, an elastic rod is fixedly connected to the middle of the friction plate; a first magnet is fixedly connected to the end of the elastic rod; and a plurality of second magnets are fixedly connected to the middle of the heat sink; by providing the first magnet on the friction plate, when the water storage box slides on the heat sink, the first magnet and the second magnet approach and move away one by one, and the first magnet can swing on the heat sink, thereby driving the friction plate and the bristles to vibrate, shaking off impurities on the bristles and improving the cleaning effect of the bristles on the heat sink.

[0013] Furthermore, a plurality of water permeable holes are opened in the middle of the water storage box; a plurality of elastic pads are fixedly connected inside the water permeable holes; a push rod is fixedly connected at the top of the second positioning plate and at the position corresponding to the water permeable holes; by providing a push rod at the top of the second positioning plate, when the water storage box moves to the top of the second positioning plate, the push rod can push open the elastic pads to discharge the liquid inside the water storage box, and then the water storage box can be reset under the pull of the spring.

[0014] Furthermore, a plurality of guide holes are provided in the middle of the push rod; the guide holes are arranged in an arc shape; by providing the guide holes in the middle of the push rod, when the push rod pushes the elastic pad open, part of the liquid can be discharged from the guide holes, thereby further improving the discharge speed of the liquid inside the water storage box.

[0015] The present invention is beneficial in that:

[0016] 1. The present invention adds an indirect heat exchanger between the flue gas heat exchanger and the cold source medium to isolate the flue gas from the cold source medium. The indirect heat exchanger is made of stainless steel, which is effectively anti-corrosive and ensures the safety of the operation of the cold source medium.

[0017] 2. In the present invention, the hot circulating water on the primary side of the boiler flue gas waste heat exchange is a closed cycle, with little water loss. Except for regular sewage discharge, there is no other water loss. The amount of water replenishment on the primary side during operation is small, and water replenishment is made by a pressure-stabilizing tank, which can reduce the frequency of starting the water replenishment pump. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0019] Figure 1 This is a schematic diagram of the working process structure of the heat exchanger of Example 1;

[0020] Figure 2 This is a schematic diagram of the structure of a flue gas heat exchanger according to Embodiment 1;

[0021] Figure 3 It is a schematic cross-sectional structural diagram of a flue gas heat exchanger of Embodiment 1;

[0022] Figure 4 It is a partial structural schematic diagram of the primary network circulating water pipeline of Example 1;

[0023] Figure 5 It is a partial cross-sectional structural schematic diagram of the primary network circulating water pipeline of Example 1;

[0024] Figure 6It is an enlarged view of the structure at A of Example 1;

[0025] Figure 7 It is an enlarged view of the structure at B of Example 1;

[0026] Figure 8 This is a schematic diagram of the top rod structure of Example 2.

[0027] In the figure: 1. Inlet and outlet flues of flue gas heat exchanger; 2. Flue gas heat exchanger body; 3. Primary network circulating water pipeline; 4. Inlet valve of flue gas heat exchanger water side; 5. Outlet valve of flue gas heat exchanger water side; 6. Inlet valve of primary circulating water pump; 7. Primary circulating water pump; 8. Outlet check valve of primary circulating water pump; 9. Outlet valve of primary circulating water pump; 10. Inlet valve of heat source water of indirect heat exchanger; 11. Outlet valve of heat source water of indirect heat exchanger; 12. Indirect heat exchanger; 13. Inlet valve of cold source side of indirect heat exchanger; 1 4. Outlet valve on the cold source side of the indirect heat exchanger; 15. Bypass valve on the cold source side of the indirect heat exchanger; 16. Cold source water pipeline of the indirect heat exchanger; 17. Water supply pipeline; 18. Pressure regulating tank; 21. First positioning plate; 22. Second positioning plate; 23. Heat sink; 24. Water storage box; 25. Spring; 31. Fixed rod; 32. Friction plate; 33. Brush; 41. Elastic rod; 42. First magnet; 43. Second magnet; 51. Water permeable hole; 52. Elastic pad; 53. Push rod; 61. Diversion hole. DETAILED DESCRIPTION

[0028] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0029] Embodiment 1

[0030] See also Figure 1-7As shown, an indirect heat exchange system for utilizing waste heat from flue gas at the tail end of a power plant boiler comprises an inlet and outlet flue 1 of a flue gas heat exchanger; a flue gas heat exchanger body 2 is connected to the inlet and outlet flue 1 of the flue gas heat exchanger in the middle; a primary network circulating water pipeline 3 is connected to the flue gas heat exchanger body 2; a portion of the primary network circulating water pipeline 3 extends to the interior of the flue gas heat exchanger body 2; a flue gas heat exchanger water side inlet valve 4, an indirect heat exchanger heat source water inlet valve 10, an indirect heat exchanger heat source water outlet valve 11, a primary circulating water pump inlet valve 6, a primary circulating water pump 7, a primary circulating water pump outlet check valve 8, a primary circulating water pump outlet valve 9 and a flue gas heat exchanger water side outlet valve 5 are sequentially installed in the middle of the primary network circulating water pipeline 3; a water supply pipeline 17 is connected to the middle of the primary network circulating water pipeline 3 between the indirect heat exchanger heat source water outlet valve 11 and the primary circulating water pump inlet valve 6; a stabilizing agent is connected to the water supply pipeline 17 in the middle. The pressure tank 18; the indirect heat exchanger body 12 is installed on the primary network circulating water pipeline 3 at a position between the indirect heat exchanger heat source water inlet valve 10 and the indirect heat exchanger heat source water outlet valve 11; the indirect heat exchanger body 12 is connected with the indirect heat exchanger cold source water pipeline 16 in the middle; the indirect heat exchanger cold source side bypass valve 15 is installed in the middle of the indirect heat exchanger cold source water pipeline 16; the indirect heat exchanger cold source side inlet valve 13 and the indirect heat exchanger cold source side outlet valve 14 are connected in sequence on both sides of the indirect heat exchanger cold source side bypass valve 15 in the middle of the indirect heat exchanger cold source water pipeline 16; the indirect heat exchanger cold source side inlet valve 13 and the indirect heat exchanger cold source side outlet valve 14 extend into the indirect heat exchanger body 12; the flue gas enters the flue gas heat exchanger body 2 from the flue gas heat exchanger inlet and outlet flues 1 for heat exchange, and the flue gas after heat exchange is discharged from the flue gas heat exchanger body 2. The tube side of the flue gas heat exchanger is connected to the external primary circulating water system. The primary circulating water system includes the primary network circulating water pipeline 3, valves (flue gas heat exchanger water side inlet valve 4, flue gas heat exchanger water side outlet valve 5, primary circulating water pump inlet valve 6, primary circulating water pump outlet check valve 8, primary circulating water pump outlet valve 9, indirect heat exchanger heat source water inlet valve 10, indirect heat exchanger heat source water outlet valve 11), primary circulating water pump 7, indirect heat exchanger body 12 and water supply pipeline 17, and pressure stabilizing tank 18. After the indirect heat exchanger body 12 on the flue gas heat exchanger tube side releases heat, it is sent to the flue gas heat exchanger body 2 by the primary circulating water pump 7 to absorb heat. The circulating water is closed-loop circulated in the primary network, and its water loss is very small. The system external softened water supply pipeline 17 is used for water replenishment, and the pressure stabilizing tank 18 is used to stabilize the pressure of the primary network. The secondary network of the system is the cold source water pipeline 16 of the indirect heat exchanger. The cold source water exchanges heat with the circulating water of the primary network through the indirect heat exchanger. After absorbing heat, the cold source water is sent to the end user through the outlet pipeline of the indirect heat exchanger.

[0031] When the primary network needs maintenance or an accident occurs, the bypass valve 15 on the cold source side of the indirect heat exchanger is opened, and the inlet valve 13 and the outlet valve 14 on the cold source side of the indirect heat exchanger are closed. The secondary network can operate normally without being disturbed by the primary network.

[0032] In order to prevent the sulfides in the flue gas from corroding the heat exchange tubes, the heat exchange tubes are made of 316L material, so that the corrosion will be limited to the primary heat exchange system, and the primary system is equipped with a bypass. When a problem occurs inside the primary system and needs to be repaired, the secondary system does not need to be shut down and can be operated through the bypass, thus avoiding the impact of flue gas on the safe operation of the secondary system.

[0033] The indirect heat exchanger cold source side bypass valve 15 is connected in parallel with the indirect heat exchanger cold source side inlet valve 13 and the indirect heat exchanger cold source side outlet valve 14; the indirect heat exchanger cold source side inlet valve 13 and the indirect heat exchanger cold source side outlet valve 14 are connected in series.

[0034] The primary circulation water pump inlet valve 6 , the primary circulation water pump 7 , the primary circulation water pump outlet check valve 8 and the primary circulation water pump outlet valve 9 are arranged in parallel in the middle of the primary network circulation water pipeline 3 .

[0035] The primary network circulating water pipe 3 is fixedly connected with a first positioning plate 21 in the middle of the flue gas heat exchanger body 2; the second positioning plate 22 is fixedly connected with the middle of the primary network circulating water pipe 3; a heat sink 23 is fixedly connected between the first positioning plate 21 and the second positioning plate 22; the heat sink 23 is in contact with the primary network circulating water pipe 3; a water storage box 24 is slidably connected with the middle of the primary network circulating water pipe 3 between the first positioning plate 21 and the second positioning plate 22; a spring 25 is connected between the water storage box 24 and the first positioning plate 21; by providing a slidable water storage box 24 in the middle of the primary network circulating water pipe 3, when smoke passes through the inside of the flue gas heat exchanger body 2, the heat of the smoke passes through the primary network circulating water pipe 3 and the heat sink 23 are conducted to the fluid inside the primary network circulating water pipe 3 to heat the fluid. When the water vapor mixed with the flue gas is liquefied on the primary network circulating water pipe 3 and the heat sink 23, part of the liquid will flow into the water storage box 24. When the liquid inside the water storage box 24 accumulates more, it will slide downward in the middle of the primary network circulating water pipe 3. At this time, the bristles 33 can scrape off the impurities remaining in the middle of the primary network circulating water pipe 3 and the heat sink 23, reduce the impurities remaining in the middle of the primary network circulating water pipe 3 and the heat sink 23, and at the same time reduce the condensed water residue in the middle of the flue gas heat exchanger body 2 and the heat sink 23, and reduce the corrosion problem caused by the condensed water of the flue gas on the primary network circulating water pipe 3 and the heat sink 23.

[0036] A fixing rod 31 is fixedly connected to the inner wall of the water storage box 24; a friction plate 32 is fixedly connected to the end of the fixing rod 31 close to the heat sink 23; a plurality of bristles 33 are fixedly connected to the middle of the friction plate 32; the bristles 33 are in contact with the heat sink 23; by providing bristles 33 on the inner wall of the water storage box 24 in contact with the heat sink 23, the bristles 33 can clean the heat sink 23 when the water storage box 24 slides on the heat sink 23, thereby further reducing the residual impurities on the heat sink 23 and reducing the heat conduction of impurities to the heat sink 23 and the primary network circulating water pipeline 3.

[0037] An elastic rod 41 is fixedly connected to the middle of the friction plate 32; a first magnet 42 is fixedly connected to the end of the elastic rod 41; a plurality of second magnets 43 are fixedly connected to the middle of the heat sink 23; by providing the first magnet 42 on the friction plate 32, when the water storage box 24 slides on the heat sink 23, the first magnet 42 and the second magnet 43 approach and move away one by one, and the first magnet 42 can swing on the heat sink 23, which can drive the friction plate 32 and the bristles 33 to vibrate, shake off impurities on the bristles 33, and at the same time improve the cleaning effect of the bristles 33 on the heat sink 23.

[0038] A plurality of water permeable holes 51 are provided in the middle of the water storage box 24; a plurality of elastic pads 52 are fixedly connected inside the water permeable holes 51; a push rod 53 is fixedly connected at the top of the second positioning plate 22 and at the position corresponding to the water permeable holes 51; by providing the push rod 53 at the top of the second positioning plate 22, when the water storage box 24 moves to the top of the second positioning plate 22, the push rod 53 can push open the elastic pad 52 to discharge the liquid inside the water storage box 24, and then the water storage box 24 can be reset under the pull of the spring 25.

[0039] Embodiment 2

[0040] See also Figure 8 As shown, compared with Example 1, as another embodiment of the present invention, a plurality of guide holes 61 are opened in the middle of the push rod 53; the guide holes 61 are arranged in an arc shape; by opening the guide holes 61 in the middle of the push rod 53, when the push rod 53 pushes the elastic pad 52 open, part of the liquid can be discharged from the guide holes 61, thereby further improving the discharge speed of the liquid in the water storage box 24.

[0041] Working principle: the flue gas enters the flue gas heat exchanger body 2 from the flue gas heat exchanger inlet and outlet flue 1 for heat exchange, and the flue gas after heat exchange is discharged from the flue gas heat exchanger body 2. The flue gas heat exchanger tube side is connected to the external primary circulating water system. The primary circulating water system includes a primary network circulating water pipeline 3, valves (flue gas heat exchanger water side inlet valve 4, flue gas heat exchanger water side outlet valve 5, primary circulating water pump inlet valve 6, primary circulating water pump outlet check valve 8, primary circulating water pump outlet valve 9, indirect heat exchanger heat source water inlet valve 10, indirect heat exchanger heat source water outlet valve 11), primary circulating water pump 7, indirect heat exchanger body 12 and water supply pipeline 17, and pressure regulating tank 18. After the indirect heat exchanger body 12 on the flue gas heat exchanger tube side releases heat, it is sent to the flue gas heat exchanger body 2 by the primary circulating water pump 7 to absorb heat. The circulating water is circulated in a closed loop in the primary network, and its water loss is very small. The system uses an external softened water replenishment pipeline 17 for replenishment, and a pressure stabilizing tank 18 is used to stabilize the pressure of the primary network. The system secondary network is an indirect heat exchanger cold source water pipeline 16. The cold source water exchanges heat with the primary network circulating water through the indirect heat exchanger. After absorbing heat, the cold source water is sent to the end user through the indirect heat exchanger outlet pipeline. When the primary network needs maintenance or an accident, open the indirect heat exchanger cold source side bypass valve 15, close the indirect heat exchanger cold source side inlet valve 13 and the indirect heat exchanger cold source side outlet valve 14, and the secondary network can be unaffected by the primary network and operate normally.

[0042] By providing a slidable water storage box 24 in the middle of the primary network circulating water pipe 3, when smoke passes through the inside of the smoke heat exchanger body 2, the heat of the smoke is transferred to the fluid inside the primary network circulating water pipe 3 through the primary network circulating water pipe 3 and the heat sink 23, and the fluid is heated. When the water vapor mixed with the smoke is liquefied on the primary network circulating water pipe 3 and the heat sink 23, part of the liquid will flow into the water storage box 24. When a lot of liquid accumulates in the water storage box 24, it will flow downward in the middle of the primary network circulating water pipe 3. The brush 33 can then scrape off the impurities remaining in the middle of the primary network circulating water pipe 3 and the heat sink 23, thereby reducing the residual impurities in the primary network circulating water pipe 3 and the heat sink 23, and at the same time reducing the residual condensed water in the middle of the flue gas heat exchanger body 2 and the heat sink 23, thereby reducing the corrosion problem caused by the condensed water on the primary network circulating water pipe 3 and the heat sink 23; by providing a brush 33 on the inner side wall of the water storage box 24 to contact the heat sink 23, the water storage box 24 can be brushed when it slides on the heat sink 23. The bristles 33 clean the heat sink 23, further reducing the impurities remaining on the heat sink 23 and reducing the heat conduction of the impurities to the heat sink 23 and the primary network circulating water pipe 3; by providing the first magnet 42 on the friction plate 32, when the water storage box 24 slides on the heat sink 23, the first magnet 42 and the second magnet 43 approach and move away one by one, and the first magnet 42 can swing on the heat sink 23, and the friction plate 32 and the bristles 33 can be driven to vibrate, so as to shake off the impurities on the bristles 33 and lift the bristles 33 at the same time. 3. The cleaning effect of the heat sink 23 is improved; by providing a push rod 53 on the top of the second positioning plate 22, when the water storage box 24 moves to the top of the second positioning plate 22, the push rod 53 can push open the elastic pad 52 to discharge the liquid inside the water storage box 24, and then the water storage box 24 can be reset under the pull of the spring 25; by providing a guide hole 61 in the middle of the push rod 53, when the push rod 53 pushes open the elastic pad 52, part of the liquid can be discharged from the guide hole 61, thereby further improving the discharge speed of the liquid inside the water storage box 24.

[0043] In the description of this specification, the description with reference to the terms "one embodiment", "example", "specific example", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0044] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments, and the above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, and these changes and improvements all fall within the scope of the present invention to be protected.

Claims

1. An indirect heat exchange system for utilizing waste heat from flue gas at the tail end of a power plant boiler, characterized in that: The invention comprises an inlet and outlet flue (1) of a flue gas heat exchanger; the middle of the inlet and outlet flue (1) of the flue gas heat exchanger is connected to a flue gas heat exchanger body (2); the flue gas heat exchanger body (2) is connected to a primary network circulating water pipeline (3); part of the primary network circulating water pipeline (3) extends into the interior of the flue gas heat exchanger body (2); the middle of the primary network circulating water pipeline (3) is sequentially installed with a flue gas heat exchanger water side inlet valve (4), an indirect heat exchanger heat source water inlet valve (10), an indirect heat exchanger heat source water outlet valve (11), a primary circulating water pump inlet valve (6), a primary circulating water pump (7), a primary circulating water pump outlet check valve (8), a primary circulating water pump outlet valve (9) and a flue gas heat exchanger water side outlet valve (5); the primary network circulating water pipeline (3 ) is connected to a water supply pipeline (17) in the middle between the indirect heat exchanger heat source water outlet valve (11) and the primary circulation water pump inlet valve (6); a pressure stabilizing tank (18) is connected to the water supply pipeline (17); an indirect heat exchanger body (12) is installed in the middle of the primary network circulation water pipeline (3) between the indirect heat exchanger heat source water inlet valve (10) and the indirect heat exchanger heat source water outlet valve (11); an indirect heat exchanger cold source water pipeline (16) is connected to the middle of the indirect heat exchanger cold source water pipeline (16); an indirect heat exchanger cold source side bypass valve (15) is installed in the middle of the indirect heat exchanger cold source water pipeline (16); the indirect heat exchanger cold source water pipeline (16) is connected in sequence on both sides of the indirect heat exchanger cold source side bypass valve (15) An indirect heat exchanger cold source side inlet valve (13) and an indirect heat exchanger cold source side outlet valve (14) are connected; an indirect heat exchanger cold source water pipeline (16) between the indirect heat exchanger cold source side inlet valve (13) and the indirect heat exchanger cold source side outlet valve (14) extends into the interior of the indirect heat exchanger body (12); the indirect heat exchanger cold source side bypass valve (15) is connected in parallel with the indirect heat exchanger cold source side inlet valve (13) and the indirect heat exchanger cold source side outlet valve (14); the indirect heat exchanger cold source side inlet valve (13) and the indirect heat exchanger cold source side outlet valve (14) are connected in series; a first positioning plate (21) is fixedly connected to the middle of the primary network circulating water pipeline (3) located inside the flue gas heat exchanger body (2); a first positioning plate (21) is fixedly connected to the middle of the primary network circulating water pipeline (3) A second positioning plate (22) is provided; a heat sink (23) is fixedly connected between the first positioning plate (21) and the second positioning plate (22); the heat sink (23) is in contact with a primary network circulating water pipeline (3); a water storage box (24) is slidably connected to the middle of the primary network circulating water pipeline (3) between the first positioning plate (21) and the second positioning plate (22); a spring (25) is connected between the water storage box (24) and the first positioning plate (21); a fixing rod (31) is fixedly connected to the inner wall of the water storage box (24); a friction plate (32) is fixedly connected to the end of the fixing rod (31) close to the heat sink (23); a plurality of bristles (33) are fixedly connected to the middle of the friction plate (32); and the bristles (33) are in contact with the heat sink (23).

2. The indirect heat exchange system for utilizing waste heat from flue gas at the tail end of a power plant boiler according to claim 1 is characterized in that: The primary circulation water pump inlet valve (6), the primary circulation water pump (7), the primary circulation water pump outlet check valve (8) and the primary circulation water pump outlet valve (9) are arranged in parallel in the middle of the primary network circulation water pipeline (3).

3. The indirect heat exchange system for utilizing waste heat from flue gas at the tail end of a power plant boiler according to claim 1 is characterized in that: An elastic rod (41) is fixedly connected to the middle of the friction plate (32); a first magnet (42) is fixedly connected to the end of the elastic rod (41); and a plurality of second magnets (43) are fixedly connected to the middle of the heat sink (23).

4. The indirect heat exchange system for utilizing waste heat from flue gas at the tail end of a power plant boiler according to claim 1 is characterized in that: A plurality of water-permeable holes (51) are provided in the middle of the water storage box (24); a plurality of elastic pads (52) are fixedly connected inside the water-permeable holes (51); and a top rod (53) is fixedly connected at a position corresponding to the water-permeable holes (51) on the top of the second positioning plate (22).

5. The indirect heat exchange system for utilizing waste heat from flue gas at the tail end of a power plant boiler according to claim 4 is characterized in that: A plurality of guide holes (61) are provided in the middle of the top rod (53); the guide holes (61) are arranged in an arc shape.

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