Efficient energy-saving heat exchange system for flue gas waste heat of coal-fired boiler

Abstract

The invention discloses a coal-fired boiler flue gas waste heat efficient energy-saving heat exchange system which is characterized in that an inlet of a smoke inlet main flue is communicated with a smoke outlet of a boiler, and an outlet of the smoke inlet main flue is communicated with an inlet of a smoke exhaust main flue through two parallel smoke exhaust branch flues; an H-shaped finned tube heat exchange module and a spiral flat tube heat exchange module are sequentially arranged in the first smoke exhaust branch flue in the smoke flowing direction, a gas-gas heat exchange channel is arranged on one side of the second smoke exhaust branch flue, and an induced draft fan is arranged in the gas-gas heat exchange channel. A flat pipe heat pipe heat exchange module is arranged between the gas-gas heat exchange channel and the second smoke exhaust branch flue, an evaporation section of the flat pipe heat pipe heat exchange module is arranged in the second smoke exhaust branch flue, and a condensation section of the flat pipe heat pipe heat exchange module is arranged in the gas-gas heat exchange channel. A vacuum heat pipe heat exchange module and an electric dust remover are sequentially arranged in the smoke exhaust main flue in the smoke flowing direction. The system has the advantage of high flue gas waste heat utilization rate.

Description

Technical Field

[0001] The invention relates to the technical field of coal-fired boiler flue gas waste heat recovery and utilization, and in particular to a coal-fired boiler flue gas waste heat high-efficiency energy-saving heat exchange system. Background Art

[0002] Nearly 2 / 3 of my country's energy is consumed by coal-fired boilers. The heat loss of coal-fired boilers includes: exhaust loss, chemical incomplete combustion loss, heat dissipation loss, ash physical heat loss and other items. Among them, exhaust loss is the most important part, accounting for about 70%-80% of the total boiler heat loss; Therefore, it is necessary to recover the waste heat of the flue gas generated by the coal-fired boiler to reduce the heat loss. For every 15°C reduction in exhaust temperature, the thermal efficiency of the boiler increases by 1%. Reducing the exhaust temperature is an effective solution to improve the efficiency of the boiler. Therefore, it is urgent to design a system that can efficiently recover the waste heat of the flue gas of coal-fired boilers. Summary of the invention

[0003] The object of the present invention is to provide a high-efficiency and energy-saving heat exchange system for waste heat of coal-fired boiler flue gas, which can efficiently recover and utilize waste heat of coal-fired boiler flue gas.

[0004] To achieve the above-mentioned purpose, the present invention adopts the following technical scheme: a coal-fired boiler flue gas waste heat high-efficiency energy-saving heat exchange system, including a main smoke inlet flue, a main smoke exhaust flue, a flat tube heat pipe heat exchange module, an H-type fin tube heat exchange module, a spiral flat tube heat exchange module, and a vacuum heat pipe heat exchange module; the inlet of the main smoke inlet flue is connected with the smoke exhaust port of the boiler, and the outlet of the main smoke inlet flue is connected to the inlet of the main smoke exhaust flue through two parallel smoke exhaust branch flues, and the two parallel branch flues are respectively defined as a first smoke exhaust branch flue and a second smoke exhaust branch flue, and intelligent and adjustable heat exchange devices are provided at the inlet and outlet of the first smoke exhaust branch flue. An adjusting valve is provided, an H-type fin tube heat exchange module and a spiral flat tube heat exchange module are sequentially arranged along the flue gas flow direction in the first smoke exhaust branch flue, an air-to-air heat exchange channel is arranged on one side of the second smoke exhaust branch flue, an induced draft fan is arranged in the air-to-air heat exchange channel, a flat tube heat pipe heat exchange module is arranged between the air-to-air heat exchange channel and the second smoke exhaust branch flue, the evaporation section of the flat tube heat pipe heat exchange module is arranged inside the second smoke exhaust branch flue, the condensation section of the flat tube heat pipe heat exchange module is arranged inside the air-to-air heat exchange channel, and a vacuum heat pipe heat exchange module and an electrostatic precipitator are sequentially arranged along the flue gas flow direction in the main smoke exhaust flue.

[0005] Furthermore, in the aforementioned coal-fired boiler flue gas waste heat high-efficiency energy-saving heat exchange system, balancing guide plates are installed at the corners inside the second exhaust branch flue and at the entrance of the main exhaust flue.

[0006] Furthermore, the aforementioned coal-fired boiler flue gas waste heat high-efficiency energy-saving heat exchange system, wherein: the structure of the flat tube heat pipe heat exchange module includes: a flat tube heat pipe support frame, one end of the flat tube heat pipe support frame is arranged in the second exhaust branch flue, and the other end of the flat tube heat pipe support frame extends into the air-to-air heat exchange channel from the connection between the second exhaust branch flue and the air-to-air heat exchange channel, and a middle partition is arranged in the middle of the flat tube heat pipe support frame, and the middle partition is arranged at the connection between the second exhaust branch flue and the air-to-air heat exchange channel. The middle partition closes the connection between the second smoke exhaust branch flue and the gas-to-gas heat exchange channel so that the second smoke exhaust branch flue and the gas-to-gas heat exchange channel are relatively independent gas channels. A plurality of neatly arranged flat tube heat pipes are supported in the flat tube heat pipe support frame. Each flat tube heat pipe is arranged to be inclined upward from the second smoke exhaust branch flue to the gas-to-gas heat exchange channel. The lower sections of all flat tube heat pipes are located in the second smoke exhaust branch flue, and the upper sections of all flat tube heat pipes are sealed and passed through the middle partition and are located in the gas-to-gas heat exchange channel.

[0007] Furthermore, the aforementioned coal-fired boiler flue gas waste heat high-efficiency energy-saving heat exchange system, wherein: the structure of the flat tube heat pipe includes: a flat tube heat pipe body composed of a hollow tube body, and an upper head and a lower head respectively installed at the tube openings on both sides of the tube body, the cross-section of the tube body is elliptical and the long axis direction of the ellipse is along the flue gas flow direction, the upper head changes diameter axially outward to form an external thread section protruding from the flat tube heat pipe body, a filled emptying pipe is inserted in the upper head, one end of the filled emptying pipe extends inwardly into the tube body cavity, and the other end of the filled emptying pipe extends axially through the external thread section to An upper head, a sealing sleeve is provided on the outer sleeve of the upper head, one end of the sealing sleeve is closed and the other end is open, the inner wall of the open end of the sealing sleeve is provided with an internal thread section threadedly matched with the external thread section of the upper head, when the sealing sleeve is threadedly connected to the external thread section of the upper head through the internal thread section of the open end, the sealing sleeve is just sleeved on the outside of the filled drain pipe, and the closed end of the sealing sleeve just rests against the pipe mouth of the closed filled drain pipe; a drain port is provided on the outer end face of the lower head and axially penetrates to the inner cavity of the tube body, and a sealing plug that can seal the drain port is provided at the drain port.

[0008] Furthermore, in the aforementioned coal-fired boiler flue gas waste heat high-efficiency and energy-saving heat exchange system, the sealing plug is detachably mounted on the lower head by a plurality of set screws, the end face of the sealing plug in sealing contact with the outer end face of the lower head is serrated, and the outer end face of the lower head in contact with the serrated end face of the sealing plug is serrated matching the serrated end face of the sealing plug.

[0009] Furthermore, the aforementioned coal-fired boiler flue gas waste heat high-efficiency energy-saving heat exchange system, wherein: a plurality of middle support plates are installed in the flat tube heat pipe support frame, a plurality of through holes are evenly distributed on each middle support plate, the through holes on each middle support plate correspond to each flat tube heat pipe one by one, and a sheath for the corresponding flat tube heat pipe to pass through is installed at the through hole of each middle support plate, and each flat tube heat pipe in the flat tube heat pipe support frame is inserted into the corresponding sheath of the corresponding through hole of the corresponding middle support plate.

[0010] Furthermore, the aforementioned coal-fired boiler flue gas waste heat high-efficiency and energy-saving heat exchange system, wherein: the structure of the vacuum heat pipe heat exchange module includes: a vacuum heat pipe support frame, in which a plurality of vacuum heat pipes are vertically supported in the vacuum heat pipe support frame, and each vacuum heat pipe is neatly arranged into a plurality of rows distributed in sequence along the flue gas flow direction, the lower section of each vacuum heat pipe is located in the main exhaust flue and the outside of the lower section of each vacuum heat pipe is wrapped with spiral fins, the upper section of each vacuum heat pipe extends upward out of the main exhaust flue, and a sleeve is sleeved on the outside of the upper section of each vacuum heat pipe, and the upper and lower ends of each sleeve are sealed and welded to the outer wall of the corresponding vacuum heat pipe to form an annular refrigerant chamber between the sleeve and the corresponding vacuum heat pipe, and the annular refrigerant chambers of all sleeves are interconnected to form a refrigerant flow channel, the inlet of the refrigerant flow channel is connected to the first water inlet header outside the main exhaust flue, and the outlet of the refrigerant flow channel is connected to the first water outlet header outside the main exhaust flue.

[0011] Furthermore, the aforementioned coal-fired boiler flue gas waste heat high-efficiency and energy-saving heat exchange system, wherein: the structure of the H-type fin tube heat exchange module includes: a fin tube support frame, in which a plurality of H-type fin tubes are laterally supported, and each H-type fin tube is neatly arranged into a plurality of rows distributed in sequence along the flue gas flow direction, and each H-type fin tube forms a plurality of independent and parallel H-type fin tube heat exchange flow channels through a plurality of first connecting elbows, and the inlets of all H-type fin tube heat exchange flow channels are simultaneously connected to the second water inlet header, and the outlets of all H-type fin tube heat exchange flow channels are simultaneously connected to the second water outlet header.

[0012] Furthermore, the aforementioned coal-fired boiler flue gas waste heat high-efficiency and energy-saving heat exchange system, wherein: the structure of the spiral flat tube heat exchange module includes: a spiral flat tube support frame, in which a plurality of spiral flat tubes are laterally supported, each spiral flat tube is neatly arranged into a plurality of rows distributed in sequence along the flue gas flow direction, each spiral flat tube forms a plurality of independent and parallel spiral flat tube heat exchange flow channels through a plurality of second connecting elbows, the inlets of all the spiral flat tube heat exchange flow channels are simultaneously connected to the third water inlet header, and the outlets of all the spiral flat tube heat exchange flow channels are simultaneously connected to the third water outlet header.

[0013] Furthermore, the aforementioned coal-fired boiler flue gas waste heat high-efficiency energy-saving heat exchange system, wherein: intelligent adjustable valves are provided at the inlet and outlet of the first exhaust branch flue and the second exhaust branch flue Through the implementation of the above technical scheme, the beneficial effects of the present invention are: through the step-by-step recovery and utilization of coal-fired boiler flue gas, the recovery and utilization rate of the waste heat of the coal-fired boiler flue gas is high, which can effectively help enterprises save energy and reduce emissions and create greater corporate economic benefits; the present invention arranges different heat exchange devices at different positions, and uses heat exchange devices with different structures to obtain the highest heat exchange efficiency, so as to maximize the recovery of flue gas waste heat, so that it has the advantage of super high comprehensive efficiency of flue gas waste heat utilization, and the comprehensive operation has the lowest cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is a schematic diagram of the structural principle of the high-efficiency and energy-saving heat exchange system for waste heat from flue gas of a coal-fired boiler according to the present invention.

[0015] Figure 2 It is a structural schematic diagram of the flat tube heat pipe heat exchange module.

[0016] Figure 3 for Figure 2 The schematic diagram of the structure is shown in FIG. 1 , in which part of the flat tube heat pipe support frame is hidden.

[0017] Figure 4 for Figure 3 An enlarged schematic diagram of site A shown in FIG.

[0018] Figure 5 It is a schematic diagram of the installation structure of the upper head and sealing sleeve of the flat tube heat pipe.

[0019] Figure 6 This is a schematic diagram of the structure of the upper head of the flat tube heat pipe.

[0020] Figure 7 It is a schematic diagram of the structure of the sealing sleeve.

[0021] Figure 8 It is a schematic diagram of the installation structure of the lower head and sealing plug of the flat tube heat pipe.

[0022] Fig. 9 for Figure 8 An enlarged schematic diagram of site B is shown in FIG.

[0023] Fig.10 Fig. 9 The structural schematic diagram of the sealing plug is omitted.

[0024] Fig.11 It is a schematic diagram of the structure of the sealing plug.

[0025] Fig.12 This is a schematic diagram of the structure of the vacuum heat pipe heat exchange module.

[0026] Fig.13 Schematic diagram of the structure of the annular refrigerant chamber.

[0027] Fig.14Schematic diagram of the connection relationship between the vacuum heat pipe and the sleeve.

[0028] Fig.15 It is a structural schematic diagram of the H-type fin tube heat exchange module.

[0029] Fig.16 This is a schematic diagram of the structure of the spiral flat tube heat exchange module. DETAILED DESCRIPTION

[0030] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments.

[0031] like Figure 1 As shown, the coal-fired boiler flue gas waste heat high-efficiency energy-saving heat exchange system comprises a main smoke inlet duct 1, a main smoke exhaust duct 2, a flat tube heat pipe heat exchange module 3, an H-type fin tube heat exchange module 4, a spiral flat tube heat exchange module 5, and a vacuum heat pipe heat exchange module 6; the inlet of the main smoke inlet duct 1 is connected to the smoke exhaust port of the boiler 7, and the outlet of the main smoke inlet duct 1 is connected to the inlet of the main smoke exhaust duct through two parallel smoke exhaust branch ducts, and the two parallel branch ducts are respectively defined as a first smoke exhaust branch duct 8 and a second smoke exhaust branch duct 9, and intelligent adjustable valves 1 are provided at the inlet and outlet of the first smoke exhaust branch duct 8, and at the inlet and outlet of the second smoke exhaust branch duct 9. 0, an H-type fin tube heat exchange module 4 and a spiral flat tube heat exchange module 5 are sequentially arranged along the flue gas flow direction in the first smoke exhaust branch flue 8, an air-to-air heat exchange channel 11 is arranged on one side of the second smoke exhaust branch flue 9, an induced draft fan 12 is arranged in the air-to-air heat exchange channel 11, a flat tube heat pipe heat exchange module 3 is arranged between the air-to-air heat exchange channel 11 and the second smoke exhaust branch flue 9, the evaporation section of the flat tube heat pipe heat exchange module 3 is arranged inside the second smoke exhaust branch flue 9, and the condensation section of the flat tube heat pipe heat exchange module 3 is arranged inside the air-to-air heat exchange channel 11, and a vacuum heat pipe heat exchange module 6 and an electrostatic precipitator 13 are sequentially arranged along the flue gas flow direction in the main smoke exhaust flue 2; In this embodiment, a balancing guide plate 14 is installed at the corner inside the second smoke exhaust branch flue 9 and at the entrance of the main smoke exhaust flue 2. By setting the balancing guide plate 14 and adding a vibration isolation plate to the heat exchanger body, the influence of the complex flue structure on the smoke flow field can be effectively eliminated, and the amount of vortex generated at the entrance of the heating surface can be reduced, so that the vibration of the heating surface can be effectively avoided, thereby greatly increasing the stability and safety of the system. In this embodiment, if Figure 2 , Figure 3 , Figure 4As shown, the structure of the flat tube heat pipe heat exchange module 3 includes: a flat tube heat pipe support frame 31, one end of the flat tube heat pipe support frame 31 is arranged in the second smoke exhaust branch flue 9, and the other end of the flat tube heat pipe support frame 31 extends from the connection between the second smoke exhaust branch flue 9 and the gas-to-gas heat exchange channel 11 into the gas-to-gas heat exchange channel 11. A middle partition 32 is provided in the middle of the flat tube heat pipe support frame 31, and the middle partition 32 is arranged at the connection between the second smoke exhaust branch flue 9 and the gas-to-gas heat exchange channel 11. The middle partition 32 closes the connection between the second smoke exhaust branch flue 9 and the gas-to-gas heat exchange channel 11 so that the second smoke exhaust branch flue 9 and the gas-to-gas heat exchange channel 11 are relatively independent gas channels. A plurality of neatly arranged heat pipes are supported in the flat tube heat pipe support frame 31. The flat tube heat pipe 33 is arranged to be inclined upward from the second smoke exhaust branch flue 9 to the gas-to-gas heat exchange channel 11. The lower sections of all the flat tube heat pipes 33 are located in the second smoke exhaust branch flue 9. The lower sections of the flat tube heat pipes located in the second smoke exhaust branch flue 9 are evaporation sections. The upper sections of all the flat tube heat pipes 33 are sealed and passed through the middle partition 32 and are located in the gas-to-gas heat exchange channel 11. The upper sections of the flat tube heat pipes located in the gas-to-gas heat exchange channel 11 are condensation sections. The cross section of the flat tube heat pipe 33 is elliptical and the long axis direction of the ellipse is along the flue gas flow direction. This elliptical heat pipe structure is streamlined. In the cross-swept airflow, the vortex area behind the pipe can be reduced. Moreover, the partial boundary of the elliptical tube is thinner than that of the circular tube, which is conducive to enhancing heat transfer and reducing flow resistance. In this embodiment, if Figure 5 , Figure 6 , Figure 7 , Figure 8 , Fig. 9 , Fig.10 , Fig.11As shown, the structure of the flat tube heat pipe 33 includes: a flat tube heat pipe body composed of a hollow tube body 331, and an upper head 332 and a lower head 333 respectively installed at the tube openings on both sides of the tube body 331, wherein the cross section of the tube body 331 is an ellipse and the long axis direction of the ellipse is along the flue gas flow direction, the upper head 333 changes its diameter axially outward to form an external thread section 334 protruding from the flat tube heat pipe body, and a filling exhaust pipe 335 is inserted in the upper head 332, and the filling exhaust pipe 335 is One end of the filling and emptying tube 335 extends inwardly into the inner cavity of the tube body, and the other end of the filling and emptying tube 335 extends out of the upper head 332 along the axial direction through the external thread section 334. A sealing plug sleeve 336 is provided on the outer sleeve of the upper head 332. One end of the sealing plug sleeve 336 is closed and the other end is open. The inner wall of the open end of the sealing plug sleeve 336 has an internal thread section 337 threadedly matched with the external thread section 334 of the upper head 332. The sealing plug sleeve 336 is threaded through the internal thread section 337 of the open end. When connected to the external thread section 334 of the upper end cap 332, the sealing sleeve 336 is just sleeved on the outside of the filling and emptying pipe 335, and the closed end 3361 of the sealing sleeve 336 just abuts against the pipe opening of the closed filling and emptying pipe 335; the outer end surface of the lower end cap 333 is provided with an emptying port 338 axially penetrating to the inner cavity of the pipe body, and the emptying port 338 is provided with a sealing plug 339 capable of sealing the emptying port 338; in this embodiment, the sealing plug 339 is connected to the outer thread section 334 of the upper end cap 332 by a plurality of set screws 3361. 310 is detachably mounted on the lower head 333, and the sealing plug end face 3391 sealingly contacting with the outer end face of the lower head is serrated, and the lower head outer end face 3331 contacting with the serrated end face 3391 of the sealing plug 339 is serrated to match the serrated end face 3391 of the sealing plug 339. In this installation structure of the sealing plug and the lower head, the serrated end face of the sealing plug and the serrated end face of the lower head form a sealing structure similar to a maze, and the sealing performance is better; During the actual installation process, the process of filling the flat tube heat pipe with working medium water is as follows: first, take the sealing plug sleeve 336 and the sealing plug 339, and then fill the working medium water into the tube body 331 through the filling and draining pipe 335. During the process of the working medium water filling the tube body 331, the air in the tube body 331 will be discharged from the drain port 338. After the tube body 331 is filled with a predetermined amount of working medium water, the sealing plug 339 is used to block the drain port 338, and then the sealing plug is fixed to the lower head 333 with the set screw 3310. At this time, the serrated end face of the sealing plug and the serrated end face of the lower head will form a sealing structure with excellent sealing performance similar to a maze, and then The tube body 331 is then heated to make the working medium water boil and form steam, which is then discharged from the filling and emptying pipe 335. During the process of steam being discharged from the filling and emptying pipe 335, the steam will completely discharge the remaining air in the tube body 331 from the tube body 331. After the air inside the tube body 331 is completely exhausted, the sealing plug sleeve 336 is threadedly connected to the external thread section 334 of the upper head 332 through the internal thread section 337 at the open end. At this time, the sealing plug sleeve 336 is just sleeved on the outside of the filling and emptying pipe 335, and the closed end 3361 of the sealing plug sleeve 336 just abuts against the pipe mouth of the closed filling and emptying pipe 335, thereby completing the filling process of the flat tube heat pipe; In this embodiment, a plurality of middle support plates 34 are installed in the flat tube heat pipe support frame 31, and a plurality of through holes are evenly distributed on each middle support plate 34. The through holes on each middle support plate 34 correspond to the flat tube heat pipes 33 one by one, and a sheath 35 for the corresponding flat tube heat pipe 33 to pass through is installed at the through hole of each middle support plate 34. Each flat tube heat pipe 33 in the flat tube heat pipe support frame 31 is inserted into the corresponding sheath 35 of the corresponding through hole of the corresponding middle support plate 34, and each sheath 35 is not fixed to the corresponding flat tube heat pipe 33 by welding; In this embodiment, if Fig.12 , Fig.13 , Fig.14 As shown, the structure of the vacuum heat pipe heat exchange module 6 includes: a vacuum heat pipe support frame 61, in which a plurality of vacuum heat pipes 62 are vertically supported, and each vacuum heat pipe 62 is neatly arranged into a plurality of rows distributed in sequence along the flue gas flow direction, and the lower section of each vacuum heat pipe 62 is located in the exhaust main flue 2 and the outer portion of the lower section of each vacuum heat pipe 62 is wound with a spiral fin 63, and the upper section of each vacuum heat pipe 62 extends upward from the exhaust main flue 2, and each vacuum heat pipe 62 is provided with a spiral fin 63. The outer part of the upper section 62 is covered with a sleeve 64, and the upper and lower ends of each sleeve 64 are sealed and welded to the outer wall of the corresponding vacuum heat pipe 62 to form an annular refrigerant chamber 65 between the sleeve 64 and the corresponding vacuum heat pipe 62. The annular refrigerant chambers 65 of all sleeves 64 are interconnected to form a refrigerant flow channel, and the inlet of the refrigerant flow channel is connected to the first water inlet header 66 outside the exhaust main flue 2, and the outlet of the refrigerant flow channel is connected to the first water outlet header 67 outside the exhaust main flue 2; In this embodiment, if Fig.15 As shown, the structure of the H-type fin tube heat exchange module 4 includes: a fin tube support frame 41, in which a plurality of H-type fin tubes 42 are laterally supported, each H-type fin tube 42 is neatly arranged into a plurality of rows distributed in sequence along the flue gas flow direction, each H-type fin tube 42 forms a plurality of independent and parallel H-type fin tube heat exchange channels through a plurality of first connecting elbows 43, the inlets of all H-type fin tube heat exchange channels are simultaneously connected to the second water inlet header 44, and the outlets of all H-type fin tube heat exchange channels are simultaneously connected to the second water outlet header 45; In this embodiment, if Fig.16 As shown, the structure of the spiral flat tube heat exchange module 5 includes: a spiral flat tube support frame 51, in which a plurality of spiral flat tubes 52 are laterally supported, and each spiral flat tube 52 is neatly arranged into a plurality of rows distributed in sequence along the flue gas flow direction, and each spiral flat tube 52 forms a plurality of independent and parallel spiral flat tube heat exchange flow channels through a plurality of second connecting elbows 53, and the inlets of all the spiral flat tube heat exchange flow channels are simultaneously connected to the third water inlet header 54, and the outlets of all the spiral flat tube heat exchange flow channels are simultaneously connected to the third water outlet header 55; During operation, the flue gas generated by the coal-fired boiler is discharged from its flue gas outlet into the main smoke inlet duct 1. The high-temperature flue gas in the main smoke inlet duct 1 is divided into two paths, one of which enters the first smoke exhaust branch flue 8, and the other enters the second smoke exhaust branch flue 9. The high-temperature flue gas entering the first smoke exhaust branch flue 8 will pass through the H-type fin tube heat exchange module 4 and the spiral flat tube heat exchange module 5 in sequence. In the process of the high-temperature flue gas passing through the H-type fin tube heat exchange module 4 and the spiral flat tube heat exchange module 5, the high-temperature flue gas will exchange heat with the cold water passing through the H-type fin tube heat exchange module 4 and the spiral flat tube heat exchange module 5. The cold water absorbs the residual heat of the flue gas and is converted into hot water to be discharged into the subsequent process. The high-temperature flue gas forms low-temperature flue gas after heat exchange with the H-type fin tube heat exchange module 4 and the spiral flat tube heat exchange module 5 and is then discharged into the main smoke exhaust duct 2. The high-temperature flue gas entering the second smoke exhaust branch flue 9 will exchange heat with the working medium water in the lower section of the flat tube heat pipe 33 of the flat tube heat pipe heat exchange module 3. The working medium water in the lower section of the flat tube heat pipe 33 will evaporate to form high-temperature steam after heat exchange with the high-temperature flue gas in the second smoke exhaust branch flue 9. The high-temperature steam rises from the lower section to the upper section inside the flat tube heat pipe. After the high-temperature steam rises to the upper section of the flat tube heat pipe 3, since the upper section of the flat tube heat pipe 3 is located in the gas-to-gas heat exchange channel 11, the high-temperature steam will pass through the wall of the flat tube heat pipe 33 and the gas-to-gas heat exchange channel 12. The cold air introduced into the air-to-air heat exchange channel 11 by the induced draft fan 12 in the duct 11 is heat exchanged, and the cold air is converted into hot air after heat exchange with the high-temperature steam and discharged into the subsequent process, while the high-temperature steam is re-condensed into working medium water after heat exchange and descends to the lower section of the flat tube heat pipe, and the condensed working medium water descending to the lower section of the flat tube heat pipe is heat exchanged with the high-temperature flue gas discharged into the second exhaust branch flue 9 again; the high-temperature flue gas discharged into the second exhaust branch flue 9 is converted into low-temperature flue gas after heat exchange in the flat tube heat pipe heat exchange module 3 and then collected and discharged into the exhaust main flue 2; In the process of the flue gas entering the first smoke exhaust branch flue 8 and the second smoke exhaust branch flue 9 for heat exchange in two ways, the amount of flue gas distributed to the first smoke exhaust branch flue 8 and the second smoke exhaust branch flue 9 can be adjusted by controlling each intelligent adjustable valve 10 according to the actual operating conditions, so as to recover the flue gas waste heat to the maximum extent; The flue gas after the gas-to-gas heat exchange through the flat tube heat exchange module 3 and the gas-to-liquid heat exchange through the H-type fin tube heat exchange module 4 and the spiral flat tube heat exchange module 5 is collected and enters the exhaust main flue 2. The flue gas entering the exhaust main flue 2 will exchange gas-liquid heat with the working medium water in the vacuum heat pipe 62 of the vacuum heat pipe heat exchange module 6 in the exhaust main flue 2. After the heat exchange, the working medium water evaporates to form steam and rises to the upper section of the vacuum heat pipe 62. After entering the upper section of the vacuum heat pipe 62, the steam will exchange gas with the gas. The cold water in the annular refrigerant chamber 65 is heat exchanged, and the cold water forms heat after heat exchange and is discharged into the subsequent process. The steam condenses after heat exchange to form condensed water and then drops to the lower section of the vacuum heat pipe 65. The condensed working medium water dropped to the lower section of the vacuum heat pipe exchanges heat with the flue gas discharged into the exhaust main flue 2 again. The flue gas discharged into the exhaust main flue 2 is discharged after the waste heat is recovered by the vacuum heat pipe heat exchange module 6 to form low-temperature flue gas, and the low-temperature flue gas is discharged after dust removal by the electrostatic precipitator. After the above process, the waste heat of high-temperature flue gas is fully recovered and utilized, and the waste heat recovery rate of coal-fired boiler flue gas is high.

[0032] The advantages of the present invention are: by carrying out step-by-step recovery and utilization of coal-fired boiler flue gas, the recovery and utilization rate of the waste heat of the coal-fired boiler flue gas is high, which can effectively help enterprises save energy and reduce emissions and create greater corporate economic benefits; the present invention arranges different heat exchange devices at different positions, and uses heat exchange devices with different structures to obtain the highest heat exchange efficiency, so as to recover the waste heat of the flue gas to the maximum extent, so that it has the advantage of super high comprehensive efficiency of flue gas waste heat utilization, and the comprehensive operation has the lowest cost.

[0033] The above description is only a preferred embodiment of the present invention and does not constitute any other form of limitation to the present invention. Any modification or equivalent change made based on the technical essence of the present invention still falls within the scope of protection required by the present invention.

Claims

1. High-efficiency and energy-saving heat exchange system for waste heat from flue gas of coal-fired boilers, characterized by: The invention comprises a main smoke inlet duct, a main smoke exhaust duct, a flat tube heat pipe heat exchange module, an H-type finned tube heat exchange module, a spiral flat tube heat exchange module, and a vacuum heat pipe heat exchange module; the inlet of the main smoke inlet duct is connected with the smoke exhaust port of the boiler, and the outlet of the main smoke inlet duct is connected with the inlet of the main smoke exhaust duct through two parallel smoke exhaust branch ducts, and the two parallel branch ducts are respectively defined as the first smoke exhaust branch duct and the second smoke exhaust branch duct, and the H-type finned tube heat exchange module is arranged in sequence along the smoke flow direction in the first smoke exhaust branch duct. A module and a spiral flat tube heat exchange module are arranged, an air-to-air heat exchange channel is arranged on one side of the second smoke exhaust branch flue, an induced draft fan is arranged in the air-to-air heat exchange channel, a flat tube heat pipe heat exchange module is arranged between the air-to-air heat exchange channel and the second smoke exhaust branch flue, the evaporation section of the flat tube heat pipe heat exchange module is arranged inside the second smoke exhaust branch flue, the condensation section of the flat tube heat pipe heat exchange module is arranged inside the air-to-air heat exchange channel, and a vacuum heat pipe heat exchange module and an electrostatic precipitator are arranged in sequence along the flue gas flow direction in the main smoke exhaust flue.

2. The high-efficiency and energy-saving heat exchange system for waste heat from flue gas of a coal-fired boiler according to claim 1 is characterized in that: Balancing guide plates are installed at the corners inside the second smoke exhaust branch flue and at the entrance of the main smoke exhaust flue.

3. The high-efficiency and energy-saving heat exchange system for waste heat from flue gas of a coal-fired boiler according to claim 1 is characterized in that: The structure of the flat tube heat pipe heat exchange module includes: a flat tube heat pipe support frame, one end of the flat tube heat pipe support frame is arranged in the second smoke exhaust branch flue, and the other end of the flat tube heat pipe support frame extends into the air-to-air heat exchange channel from the connection between the second smoke exhaust branch flue and the air-to-air heat exchange channel, and a middle partition is arranged in the middle of the flat tube heat pipe support frame, and the middle partition is arranged at the connection between the second smoke exhaust branch flue and the air-to-air heat exchange channel. The middle partition closes the connection between the second smoke exhaust branch flue and the air-to-air heat exchange channel so that the second smoke exhaust branch flue and the air-to-air heat exchange channel are relatively independent gas channels, and a plurality of neatly arranged flat tube heat pipes are supported in the flat tube heat pipe support frame, and each flat tube heat pipe is arranged to be inclined upward from the second smoke exhaust branch flue to the air-to-air heat exchange channel, and the lower sections of all flat tube heat pipes are located in the second smoke exhaust branch flue, and the upper sections of all flat tube heat pipes are sealed and passed through the middle partition and are located in the air-to-air heat exchange channel.

4. The high-efficiency and energy-saving heat exchange system for waste heat from flue gas of a coal-fired boiler according to claim 3 is characterized in that: The structure of the flat tube heat pipe includes: a flat tube heat pipe body composed of a hollow tube body, and an upper head and a lower head respectively installed at the tube openings on both sides of the tube body, wherein the cross section of the tube body is an ellipse and the long axis direction of the ellipse is along the flue gas flow direction, the upper head changes diameter outward along the axial direction to form an external thread section protruding from the flat tube heat pipe body, a filling and emptying pipe is inserted into the upper head, one end of the filling and emptying pipe extends inwardly into the tube body cavity, and the other end of the filling and emptying pipe extends out of the upper head along the axial direction through the external thread section, and a sleeve is provided on the outer sleeve of the upper head. A sealing plug sleeve, one end of which is closed and the other end is open, the inner wall of the open end of the sealing plug sleeve is provided with an internal thread section threadedly matched with the external thread section of the upper head, when the sealing plug sleeve is threadedly connected to the external thread section of the upper head through the internal thread section of the open end, the sealing plug sleeve is just sleeved on the outside of the filled drain pipe, and the closed end of the sealing plug sleeve just rests against the pipe mouth of the closed filled drain pipe; a drain port is provided on the outer end face of the lower head and axially penetrates to the inner cavity of the tube body, and a sealing plug that can seal the drain port is provided at the drain port.

5. The high-efficiency and energy-saving heat exchange system for waste heat from flue gas of a coal-fired boiler according to claim 4 is characterized in that: The sealing plug is detachably mounted on the lower head by a plurality of set screws, the end face of the sealing plug in sealing contact with the outer end face of the lower head is serrated, and the outer end face of the lower head in contact with the serrated end face of the sealing plug is serrated matching the serrated end face of the sealing plug.

6. The high-efficiency and energy-saving heat exchange system for waste heat from flue gas of a coal-fired boiler according to claim 3 is characterized in that: A number of middle support plates are installed in the flat tube heat pipe support frame, and a number of through holes are evenly distributed on each middle support plate. The through holes on each middle support plate correspond to each flat tube heat pipe one by one, and a sheath for the corresponding flat tube heat pipe to pass through is installed at the through hole of each middle support plate. Each flat tube heat pipe in the flat tube heat pipe support frame is inserted into the corresponding sheath of the corresponding through hole of the corresponding middle support plate.

7. The high-efficiency and energy-saving heat exchange system for waste heat from flue gas of a coal-fired boiler according to claim 1 is characterized in that: The structure of the vacuum heat pipe heat exchange module includes: a vacuum heat pipe support frame, in which a plurality of vacuum heat pipes are vertically supported, and the vacuum heat pipes are neatly arranged into a plurality of rows distributed in sequence along the direction of flue gas flow, the lower section of each vacuum heat pipe is located in the main exhaust flue and a spiral fin is wound around the outside of the lower section of each vacuum heat pipe, the upper section of each vacuum heat pipe extends upward out of the main exhaust flue, and a sleeve is sleeved on the outside of the upper section of each vacuum heat pipe, and the upper and lower ends of each sleeve are sealed and welded to the outer wall of the corresponding vacuum heat pipe to form an annular refrigerant chamber between the sleeve and the corresponding vacuum heat pipe, and the annular refrigerant chambers of all sleeves are interconnected to form a refrigerant flow channel, the inlet of the refrigerant flow channel is connected to the first water inlet header outside the main exhaust flue, and the outlet of the refrigerant flow channel is connected to the first water outlet header outside the main exhaust flue.

8. The high-efficiency and energy-saving heat exchange system for waste heat from flue gas of a coal-fired boiler according to claim 1 is characterized in that: The structure of the H-type fin tube heat exchange module includes: a fin tube support frame, in which a plurality of H-type fin tubes are laterally supported, each H-type fin tube is neatly arranged into a plurality of rows distributed in sequence along the flue gas flow direction, each H-type fin tube forms a plurality of independent and parallel H-type fin tube heat exchange flow channels through a plurality of first connecting elbows, the inlets of all H-type fin tube heat exchange flow channels are simultaneously connected to the second water inlet header, and the outlets of all H-type fin tube heat exchange flow channels are simultaneously connected to the second water outlet header.

9. The high-efficiency and energy-saving heat exchange system for waste heat from flue gas of a coal-fired boiler according to claim 1, characterized in that: The structure of the spiral flat tube heat exchange module includes: a spiral flat tube support frame, in which a plurality of spiral flat tubes are laterally supported, and each spiral flat tube is neatly arranged into a plurality of rows distributed in sequence along the flue gas flow direction, and each spiral flat tube forms a plurality of independent and parallel spiral flat tube heat exchange flow channels through a plurality of second connecting elbows, and the inlets of all the spiral flat tube heat exchange flow channels are simultaneously connected to the third water inlet header, and the outlets of all the spiral flat tube heat exchange flow channels are simultaneously connected to the third water outlet header.

10. The high-efficiency and energy-saving heat exchange system for waste heat from flue gas of a coal-fired boiler according to claim 1, characterized in that: Intelligent adjustable valves are provided at the inlet and outlet of the first smoke exhaust branch flue and the second smoke exhaust branch flue.

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