Waste heat recovery system and recovery method for thermal power generation

Abstract

The invention provides a waste heat recovery system for thermal power generation and a using method, the waste heat recovery system for thermal power generation comprises a breather pipe connected with a boiler flue, the breather pipe is connected with a flue gas collecting mechanism, the flue gas collecting mechanism is connected with a combustion-supporting mechanism, the combustion-supporting mechanism is connected with an auxiliary boiler mechanism, and the auxiliary boiler mechanism is connected with a heat exchanger. The auxiliary boiler mechanism is connected with a heat recovery mechanism, and the heat recovery mechanism is connected with a flue gas purification mechanism; according to the system, flue gas is filtered through the flue gas collecting mechanism, the situation that the flue gas is condensed and deposited on the inner wall of the flue at the low temperature, and consequently serious abrasion and corrosion are caused is avoided, the service life of equipment is prolonged, the maintenance cost is reduced, and then through the combustion-supporting mechanism, the auxiliary boiler mechanism and the heat recovery mechanism, the heat recovery efficiency is improved. Waste heat in smoke is utilized, heat is transferred to a boiler system through the heat exchange principle, secondary utilization of energy is achieved, the heat efficiency of the boiler is improved, the smoke exhaust temperature is lowered, and heat loss is reduced.

Description

Technical Field

[0001] The present invention belongs to the technical field of thermal power generation, and in particular to a waste heat recovery system and a recovery method for thermal power generation. Background Art

[0002] As an important part of electricity supply, the basic principle of thermal power generation is to utilize the huge heat energy released by combustible materials such as coal, natural gas, and oil during combustion. This heat energy is then converted into mechanical energy and finally converted into electrical energy through generators. In the process of utilizing the huge heat energy released by combustible materials such as coal, natural gas, and oil during combustion, some heat energy will be discharged into the atmosphere along with the flue gas, resulting in the occurrence of room temperature effect, heat waste, and low energy conversion rate. Improving energy conversion efficiency and reducing energy waste have become the key to improving the economic benefits and environmental friendliness of thermal power plants.

[0003] In order to improve the energy conversion rate of thermal power generation, waste heat recovery technology has been proposed, which aims to capture and effectively utilize the excess heat generated during the power generation process, thereby increasing the power output of the power plant and significantly improving the overall energy utilization efficiency. In the waste heat recovery system of a thermal power plant, the commonly used waste heat recovery devices are economizer, low-temperature economizer and flue gas reheater (MGGH); among them, the economizer is usually installed in the tail flue of the boiler, using the waste heat in the flue gas to preheat the boiler feed water, reducing the amount of main steam required for subsequent heating, and effectively reducing energy consumption; the low-temperature economizer is an improved device of the economizer, which can recover heat in a lower temperature range, usually used to heat desalted water or condensate, further improving the energy recovery efficiency. The flue gas reheater (MGGH) is mainly used for reheating flue gas after desulfurization to avoid flue corrosion and white smoke from the chimney caused by too low flue gas temperature, and also provides an additional way for waste heat recovery. The above-mentioned devices generally adopt a fin heat exchange structure, which significantly improves the heat exchange efficiency by increasing the heat exchange area and optimizing the fluid flow path; however, since the flue gas often contains corrosive substances (such as sulfur oxides, nitrogen oxides, etc.) and solid particles, these components are more likely to condense and deposit on the surface of the heat exchanger at low temperatures, resulting in severe wear and corrosion, which not only shortens the service life of the equipment, but may also affect the heat exchange efficiency and increase maintenance costs. Summary of the invention

[0004] In order to solve the problem that after the existing flue gas waste heat recovery device recovers the heat in the flue gas, the flue gas is kept at a low temperature, which causes some substances in the flue gas to condense and deposit in the flue gas waste heat recovery device, resulting in wear and corrosion in the flue gas waste heat recovery device and shortening the service life of the device, the present invention provides a waste heat recovery system and recovery method for thermal power generation.

[0005] To achieve the above object, the present invention provides the following technical solutions: The present invention proposes a waste heat recovery system for thermal power generation, comprising a vent pipe connected to a boiler flue, the vent pipe being connected to a flue gas collecting mechanism, the flue gas collecting mechanism being connected to a combustion-supporting mechanism, the combustion-supporting mechanism being connected to an auxiliary boiler mechanism, the auxiliary boiler mechanism being connected to a heat recovery mechanism, and the heat recovery mechanism being connected to a flue gas purification mechanism; The smoke collecting mechanism comprises a flue, one end of which is connected to the vent pipe, and the other end of which is connected to the combustion-supporting mechanism. A scraper is provided on the inner wall of the flue, and a first telescopic rod is provided on the scraper; a filter is installed inside the scraper, and a second telescopic rod is provided inside the scraper at the side of the filter, and an elastic plate is connected to the second telescopic rod, and one end surface of the elastic plate is in contact with one end surface of the filter; The heat recovery mechanism includes a first spiral tube and a second spiral tube, the first spiral tube and the second spiral tube are installed on the auxiliary boiler mechanism, the air outlet of the first spiral tube is connected to the air inlet of the second spiral tube, the air outlet of the second spiral tube is connected to the flue gas purification mechanism, and the air inlet of the first spiral tube is connected to the combustion-supporting mechanism.

[0006] Preferably, the scraper is an annular plate, the outer wall of the annular plate is in contact with the inner wall of the flue, and the filter is arranged inside the annular plate.

[0007] Preferably, a boosting pipe is connected between the air inlet of the first spiral pipe and the air inlet of the second spiral pipe.

[0008] Preferably, the combustion-supporting mechanism comprises a combustion-supporting box, and the combustion-supporting box is symmetrically provided with two connecting holes, one of which is connected to the flue, and the auxiliary boiler mechanism is installed in the other connecting hole; The combustion-supporting box is provided with a smoke exhaust hole, and the smoke exhaust hole is connected to the air inlet of the first spiral tube; An igniter is installed in the combustion-supporting box.

[0009] Preferably, the auxiliary boiler mechanism comprises a hot water boiler and a cold water boiler, the hot water boiler is installed in the connecting hole, the first spiral tube is wound on the outer wall of the hot water boiler, and the second spiral tube is installed in the cold water boiler.

[0010] Preferably, a water pipe is connected between the hot water boiler and the cold water boiler; and a control valve is provided on the water pipe.

[0011] Preferably, a protective sleeve is provided on the water pipe.

[0012] Preferably, a heat-insulating sleeve is provided on the power-assisting pipe.

[0013] Preferably, the flue gas purification mechanism comprises a desulfurization tower and an absorption tower, the air inlet of the desulfurization tower is connected to the air outlet of the second spiral tube, and the air inlet of the absorption tower is connected to the air outlet of the desulfurization tower.

[0014] The present invention proposes a recovery method for a waste heat recovery system for thermal power generation, which is used to operate the above system, comprising the following steps: Step 1, guiding the flue gas generated by the boiler in the front thermal power unit into the flue gas collection mechanism through the ventilation pipe for collection and filtration; Step 2, the filtered flue gas enters the combustion-supporting mechanism to fully burn the unburned flue gas in the flue gas, and the heat generated by the combustion is recovered through the auxiliary boiler structure; Step 3, the burnt flue gas enters the heat recovery mechanism to recover the heat in the flue gas again; Step 4, the flue gas after heat recovery is passed into the flue gas purification mechanism for purification and then discharged.

[0015] Compared with the prior art, the present invention has the following beneficial technical effects: The present invention proposes a waste heat recovery system for thermal power generation. The system first effectively intercepts the flue gas in the boiler flue through a flue gas collection mechanism. The scraper and filter screen structure arranged in the flue not only prevent large particle impurities in the flue gas from entering the subsequent system, but also realizes automatic cleaning of the filter screen surface through the cooperation of the scraper driven by the first telescopic rod and the second telescopic rod and the elastic plate, thereby avoiding the blockage of the filter screen, ensuring the smooth flow of flue gas and the stable operation of the system, and preventing the flue gas from condensing and depositing on the inner wall of the flue at low temperature, causing serious wear and corrosion, thereby improving the service life of the equipment and reducing maintenance Cost, the combustion-supporting mechanism utilizes the collected flue gas, and through proper treatment, it not only reduces the consumption of fresh air, but also improves the combustion efficiency, further reduces energy consumption. The heat recovery mechanism composed of the first spiral tube and the second spiral tube installed on the auxiliary boiler mechanism utilizes the waste heat in the flue gas, and transfers the heat to the boiler system through the heat exchange principle, thereby realizing the secondary utilization of energy, improving the thermal efficiency of the boiler, and also lowering the exhaust temperature and reducing heat loss. The flue gas after heat recovery enters the flue gas purification mechanism for further treatment to ensure that the discharged flue gas meets the national environmental protection standards and reduces pollution to the environment.

[0016] Furthermore, the scraper of the system is an annular plate, and its outer wall is closely fitted to the inner wall of the flue, which not only ensures the comprehensiveness of flue gas collection, but also improves the filtering effect of impurities in the flue gas through the effective setting of the filter.

[0017] Furthermore, in the system, a booster pipe is added between the air inlet of the first spiral tube and the air inlet of the second spiral tube, which can balance the pressure difference between the two spiral tubes, optimize the flue gas flow path, enhance the heat recovery efficiency, and ensure the stable operation of the system, thereby improving the overall performance of the waste heat recovery system.

[0018] Furthermore, the combustion-supporting mechanism in the present system realizes the connection between the flue gas and the auxiliary boiler mechanism through the combustion-supporting box and the two symmetrical connecting holes thereon, while ensuring the reasonable distribution of the flue gas flow direction. The smoke exhaust holes arranged on the combustion-supporting box provide a stable source of flue gas for the first spiral tube. Through the built-in igniter, effective combustion of the flue gas is achieved, the combustion efficiency of the flue gas is improved, the efficiency of waste heat recovery is enhanced, and by making full use of flue gas resources, energy consumption is further reduced, thereby improving the overall economy and environmental protection of the system.

[0019] Furthermore, the auxiliary boiler mechanism in the system realizes efficient graded utilization of heat through the combination of a hot water boiler and a cold water boiler. The hot water boiler is installed in the connecting hole to directly receive the flue gas treated by the combustion-supporting mechanism. The first spiral tube is wound on its outer wall to effectively absorb the heat in the flue gas and increase the temperature of the hot water. The second spiral tube is installed in the cold water boiler to further heat the water body using the heat transferred by the first spiral tube, thereby realizing deep heat recovery and improving energy utilization efficiency. The overall efficiency of the waste heat recovery system is enhanced through multi-level utilization of heat.

[0020] Furthermore, in the present system, a water pipe is added between the hot water boiler and the cold water boiler, and a control valve is provided, so as to realize flexible allocation of heat and precise control of the system. By adjusting the switch of the control valve, water exchange between the hot water boiler and the cold water boiler is realized, thereby improving the practicality of the present system.

[0021] The present invention proposes a recovery method for a waste heat recovery system for thermal power generation. The method guides the flue gas into the flue gas collection mechanism through a vent pipe, realizes the effective collection and preliminary filtration of the flue gas, and provides a clean flue gas source for subsequent steps. Then, the combustion-supporting mechanism fully burns the filtered flue gas, which not only improves the combustion efficiency but also reduces environmental pollution. Then, the heat recovery mechanism recycles the heat of the burned flue gas, realizes the deep utilization of energy, and significantly improves the energy utilization efficiency. Finally, the flue gas purification mechanism purifies the flue gas after the heat is recovered, ensuring that the environmental protection standards of the discharged flue gas are met. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is a structural schematic diagram of a waste heat recovery system for thermal power generation proposed by the present invention; Figure 2 A schematic diagram of the structure of a flue gas collection mechanism in a waste heat recovery system for thermal power generation proposed by the present invention Figure 3 A structural schematic diagram of a combustion-supporting mechanism in a waste heat recovery system for thermal power generation proposed by the present invention Figure 4 A schematic diagram of the structure of an auxiliary boiler mechanism in a waste heat recovery system for thermal power generation proposed by the present invention Figure 5 A schematic diagram of the structure of a heat recovery mechanism in a waste heat recovery system for thermal power generation proposed by the present invention. In the attached drawings: 1. ventilation pipe; 2. smoke collecting mechanism; 21. flue; 22. filter; 23. first telescopic rod; 24. scraper; 25. second telescopic rod; 26. elastic plate; 3. combustion-supporting mechanism; 31. combustion-supporting box; 32. connecting hole; 33. igniter; 34. smoke exhaust hole; 4. auxiliary boiler mechanism; 41. hot water boiler; 42. cold water boiler; 43. control valve; 5. heat recovery mechanism; 51. first spiral tube; 52. second spiral tube; 53. connecting tube; 54. power-assisting tube; 6. smoke purification mechanism. DETAILED DESCRIPTION

[0023] In the following, only some exemplary embodiments are briefly described. As those skilled in the art will appreciate, the described embodiments may be modified in various ways without departing from the spirit or scope of the present invention. Therefore, the drawings and descriptions are considered to be exemplary and non-restrictive in nature.

[0024] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0025] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0026] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, an electrical connection, or a communication; it can be a direct connection, or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0027] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may include that the first and second features are in direct contact, or may include that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, a first feature being "above", "above" and "above" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. A first feature being "below", "below" and "below" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply indicates that the first feature is lower in level than the second feature.

[0028] The embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0029] See also Figure 1~Figure 5 The present invention discloses a waste heat recovery system for thermal power generation. The system includes a vent pipe 1 connected to a boiler flue, a flue gas collecting mechanism 2 is connected to an interface at one end of the vent pipe 1, a combustion-supporting mechanism 3 is connected to the flue gas collecting mechanism 2, an auxiliary boiler mechanism 4 is connected to the combustion-supporting mechanism 3, a heat recovery mechanism 5 is connected to the auxiliary boiler mechanism 4, a flue gas purification mechanism 6 is connected to the heat recovery mechanism 5, and the flue gas collection mechanism 2 is connected to the flue gas collection mechanism 2 through the vent pipe 1 for collection and filtration, and then the filtered flue gas is passed into the combustion-supporting mechanism 3 for full combustion, and then the fully burned flue gas is passed into the heat recovery mechanism 5, the heat recovery mechanism 5 cooperates with the auxiliary boiler mechanism 4 to recover the heat carried in the fully burned flue gas for multiple times, so as to realize the waste heat recovery of thermal power generation. After the recovery is completed, the flue gas is filtered by the flue gas purification mechanism 6 and then discharged.

[0030] See also Figure 2The smoke collecting mechanism 2 includes a smoke duct 21, one end of the smoke duct 21 is connected to an end interface of the vent pipe 1 away from the boiler smoke duct, so that the smoke in the boiler smoke duct is quickly and conveniently guided into the smoke duct 21 through the vent pipe 1, and a scraper 24 is arranged on the inner wall of the smoke duct 21, and the scraper 24 is an annular plate, and the outer wall of the annular plate fits the inner wall of the smoke duct 21, and a first telescopic rod 23 is arranged on the scraper 24, and the telescopic head end of the first telescopic rod 23 is connected to the scraper 24, and the first telescopic rod 23 is connected to the first driving member, and the first telescopic rod 23 is moved along the axial direction of the smoke duct 21 by the first driving member, so as to The dust attached to the inner wall of the flue 21 is scraped off; a filter screen 22 is installed in the scraper 24, and the smoke entering the flue 21 is filtered through the filter screen 22 to filter out the dust carried in the smoke; a second telescopic rod 25 is arranged inside the scraper 24 at the side of the filter screen 22, and the telescopic head end of the second telescopic rod 25 is connected to an elastic plate 26, and one end surface of the elastic plate 26 is in contact with one end surface of the filter screen 22, and a second driving member is connected to the second telescopic rod 25, and the second telescopic rod 25 is moved along the radial direction of the scraper 24 by the second driving member, so as to scrape off the dust attached to the filter screen 22; See also Figure 3 The combustion-supporting mechanism 3 includes a combustion-supporting box 31, and connecting holes 32 are symmetrically arranged on two opposite end surfaces of the combustion-supporting box 31, one of which is connected to an end port of the flue 21 away from the ventilation pipe 1, so that the filtered flue gas in the flue 21 can quickly and conveniently enter the combustion-supporting box 31, and an igniter 33 is installed in the combustion-supporting box 31, and the igniter 33 ignites the unburned flue gas in the combustion-supporting box 31, so that the unburned flue gas burns and generates heat, and an auxiliary boiler mechanism 4 is installed in another connecting hole 32 on the combustion-supporting box 31, so that the flue gas carrying heat in the combustion-supporting box 31 heats the auxiliary boiler mechanism 4, that is, the heat carried by the flue gas in the combustion-supporting box 31 is preliminarily recovered by the auxiliary boiler mechanism 4, and a smoke exhaust hole 34 is arranged on the side of the connecting hole 32 where the auxiliary boiler mechanism 4 is installed on the combustion-supporting box 31, and the smoke exhaust hole 34 is connected to the heat recovery mechanism 5, so that the collected flue gas enters the heat recovery mechanism 5 for heat recovery again.

[0031] See also Figure 4 The auxiliary boiler mechanism 4 includes a hot water boiler 41 and a cold water boiler 42. The bottom of the hot water boiler 41 is installed in the connecting hole 32 located on the side of the smoke exhaust hole 34 of the combustion-supporting mechanism 3; the water outlet of the hot water boiler 41 is connected to the water inlet of the boiler through a pipeline for replenishing the boiler; a water pipe is connected between the hot water boiler 41 and the cold water boiler 42, and a protective sleeve is provided on the water pipe. The water pipe is used to provide a channel for water circulation between the hot water boiler 41 and the cold water boiler 42. A control valve 43 is connected to the water pipe for controlling the flow direction of the water pipe. The cold water boiler 42 is connected to an external water source through a pipeline.

[0032] See also Figure 5 The heat recovery mechanism 5 includes a first spiral tube 51, a second spiral tube 52, a connecting tube 53, and a boosting tube 54; wherein, one end interface of the connecting tube 53 is connected to the smoke exhaust hole 34 of the combustion-supporting box 31, and the other end interface of the connecting tube 53 is connected to the air inlet of the first spiral tube 51, and the air outlet of the first spiral tube 51 is connected to the air inlet of the second spiral tube 52. The first spiral tube 51 is wound on the outer surface of the water heater 41, and the flue gas carrying heat after combustion in the combustion-supporting box 31 is introduced into the first spiral tube 51 through the connecting tube 53, and the water in the water heater 41 is heated through the first spiral tube 51; the air outlet of the first spiral tube 51 is connected to the air inlet of the second spiral tube 52, and the second spiral tube 52 is arranged in the cold water furnace 42. The air outlet of the spiral tube 52 is connected to the flue gas purification mechanism 6, so that the flue gas in the first spiral tube 51 is introduced into the second spiral tube 52, and the water in the cold water boiler 42 is heated by the second spiral tube 52; a branch interface is provided on the connecting pipe 53 near the combustion-supporting box 31, and the branch interface is connected to one end interface of the boosting tube 54, and the other end interface of the boosting tube 54 is connected to the air inlet of the second spiral tube 52. When the temperature of the hot water boiler 41 is too high, the flue gas carrying heat after combustion in the combustion-supporting box 31 is directly introduced into the second spiral tube 52 through the cooperation of the boosting tube 54 and the connecting tube 53, so as to heat the water in the cold water boiler 42; an insulation sleeve is provided on the boosting tube 54, and the boosting tube 54 is insulated by the insulation sleeve to prevent heat loss.

[0033] The flue gas purification mechanism 6 includes a desulfurization tower and an absorption tower, both of which are installed in an installation box, and the air inlet of the desulfurization tower is connected to the air outlet of the second spiral tube 52 through a pipeline, and the air inlet of the absorption tower is connected to the air outlet of the desulfurization tower through a pipeline.

[0034] The present invention also discloses a recovery method for a waste heat recovery system for thermal power generation, which is used to operate the above system to recover waste heat from thermal power generation, and specifically comprises the following steps: Step 1, guiding the flue gas generated by the boiler in the front thermal power unit into the flue gas collection mechanism through the ventilation pipe for collection and filtration; Specifically, the smoke generated by the boiler in the current thermal unit is collected through the ventilation pipe 1, so that the smoke enters the flue 21 in the smoke collection mechanism 2, and the smoke carried inside the smoke is filtered through the filter 22 in the flue 21 to filter out the dust particles carried in the smoke; During the use of the smoke collecting mechanism 2, the first telescopic rod 23 inside the smoke collecting mechanism 2 is used to clean the inner wall of the smoke duct 21, and the second telescopic rod 25 drives the elastic plate 26 to clean the filter 22, so as to remove the dust attached to the filter 22 after filtering the smoke, and directly return the dust to the boiler, so as to facilitate discharge; Step 2, the filtered flue gas enters the combustion-supporting mechanism to fully burn the unburned flue gas in the flue gas, and the heat generated by the combustion is recovered through the auxiliary boiler structure; Specifically, the filtered flue gas enters the combustion-supporting box 31 in the combustion-supporting mechanism 3, and the unburned flue gas is ignited by the igniter 33 provided in the combustion-supporting box 31, so that the flue gas entering the combustion-supporting box 31 is fully burned, and the heat generated during the combustion of the flue gas heats the water heater 41, thereby realizing the preliminary recovery of the waste heat of the flue gas; Step 3, the burnt flue gas enters the heat recovery mechanism to recover the heat in the flue gas again; Specifically, the burnt flue gas enters the heat recovery mechanism 5, and the first spiral tube 51 is used to assist in heating the hot water boiler 41, and the remaining flue gas with a certain amount of heat enters the second spiral tube 52 to heat the cold water boiler 42, and the heat carried by the burnt flue gas is recovered again; When the temperature of the heat recovery mechanism 5 is lower than the temperature of the hot water boiler 41, the heat is directly passed into the second spiral tube 52 through the booster pipe 54 to directly heat the cold water boiler 42, thereby recovering the heat carried by the burnt flue gas; Step 4, passing the flue gas after heat recovery into the flue gas purification mechanism 6 for purification, and then discharged; Specifically, the flue gas after heat recovery is passed into the desulfurization tower in the flue gas purification mechanism 6 for desulfurization, and then enters the absorption tower for filtration, and is discharged after filtration.

[0035] The above shows and describes the basic principles and main features of the present invention and the advantages of the present invention. It is obvious to those skilled in the art that the present invention is not limited to the details of the above exemplary embodiments, and the present invention can be implemented in other specific forms without departing from the spirit or basic features of the present invention. Therefore, no matter from which point of view, the embodiments should be regarded as exemplary and non-restrictive. The scope of the present invention is defined by the attached claims rather than the above description, and it is intended that all changes falling within the meaning and scope of the equivalent elements of the claims are included in the present invention. Any figure mark in the claims should not be regarded as limiting the claims involved.

[0036] In addition, it should be understood that although this specification is described in accordance with the implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other implementation modes that can be understood by those skilled in the art. The above content is only to illustrate the technical idea of ​​the present invention, and cannot be used to limit the protection scope of the present invention. Any changes made on the basis of the technical solution according to the technical idea proposed by the present invention shall fall within the protection scope of the claims of the present invention.

Claims

1. A waste heat recovery system for thermal power generation, characterized in that: The invention comprises a ventilation pipe (1) connected to a boiler flue, the ventilation pipe (1) being connected to a flue gas collecting mechanism (2), the flue gas collecting mechanism (2) being connected to a combustion-supporting mechanism (3), the combustion-supporting mechanism (3) being connected to an auxiliary boiler mechanism (4), the auxiliary boiler mechanism (4) being connected to a heat recovery mechanism (5), and the heat recovery mechanism (5) being connected to a flue gas purification mechanism (6); The smoke collecting mechanism (2) comprises a smoke duct (21), one end port of the smoke duct (21) is connected to the ventilation pipe (1), and the other end port of the smoke duct (21) is connected to the combustion supporting mechanism (3); a scraper (24) is arranged on the inner wall of the smoke duct (21), and a first telescopic rod (23) is arranged on the scraper (24); a filter screen (22) is installed inside the scraper (24), and a second telescopic rod (25) is arranged inside the scraper (24) at the side of the filter screen (22), and an elastic plate (26) is connected to the second telescopic rod (25), and one end surface of the elastic plate (26) is in contact with one end surface of the filter screen (22); The heat recovery mechanism (5) comprises a first spiral tube (51) and a second spiral tube (52), wherein the first spiral tube (51) and the second spiral tube (52) are mounted on the auxiliary boiler mechanism (4), an air outlet of the first spiral tube (51) is connected to an air inlet of the second spiral tube (52), an air outlet of the second spiral tube (52) is connected to the flue gas purification mechanism (6), and an air inlet of the first spiral tube (51) is connected to the combustion-supporting mechanism (3).

2. A waste heat recovery system for thermal power generation according to claim 1, characterized in that: The scraper (24) is an annular plate, the outer wall of the annular plate is in contact with the inner wall of the flue (21), and the filter screen (22) is arranged inside the annular plate.

3. The waste heat recovery system for thermal power generation according to claim 1, characterized in that: A boosting pipe (54) is connected between the air inlet of the first spiral tube (51) and the air inlet of the second spiral tube (52).

4. A waste heat recovery system for thermal power generation according to claim 3, characterized in that: The combustion-supporting mechanism (3) comprises a combustion-supporting box (31), and two connecting holes (32) are symmetrically arranged on the combustion-supporting box (31), wherein one of the connecting holes (32) is connected to the flue (21), and the auxiliary boiler mechanism (4) is installed in the other connecting hole (32); The combustion-supporting box (31) is provided with a smoke exhaust hole (34), and the smoke exhaust hole (34) is connected to the air inlet of the first spiral tube (51); An igniter (33) is installed in the combustion-supporting box (31).

5. A waste heat recovery system for thermal power generation according to claim 4, characterized in that: The auxiliary boiler mechanism (4) comprises a hot water boiler (41) and a cold water boiler (42); the hot water boiler (41) is installed in the connecting hole (32); the first spiral tube (51) is wound on the outer wall of the hot water boiler (41); and the second spiral tube (52) is installed in the cold water boiler (42).

6. A waste heat recovery system for thermal power generation according to claim 5, characterized in that: A water pipe is connected between the hot water boiler (41) and the cold water boiler (42); a control valve (43) is provided on the water pipe.

7. A waste heat recovery system for thermal power generation according to claim 6, characterized in that: A protective sleeve is arranged on the water pipe.

8. The waste heat recovery system for thermal power generation according to claim 4, characterized in that: The booster pipe (54) is provided with a heat-insulating sleeve.

9. The waste heat recovery system for thermal power generation according to claim 1, characterized in that: The flue gas purification mechanism (6) comprises a desulfurization tower and an absorption tower, the air inlet of the desulfurization tower is connected to the air outlet of the second spiral tube (52), and the air inlet of the absorption tower is connected to the air outlet of the desulfurization tower.

10. A method for recovering waste heat from a thermal power generation system, used to operate the system according to any one of claims 1 to 9, characterized in that: The following steps are involved: Step 1, guiding the flue gas generated by the boiler in the front thermal power unit into the flue gas collection mechanism through the ventilation pipe for collection and filtration; Step 2, the filtered flue gas enters the combustion-supporting mechanism to fully burn the unburned flue gas in the flue gas, and the heat generated by the combustion is recovered through the auxiliary boiler structure; Step 3, the burnt flue gas enters the heat recovery mechanism to recover the heat in the flue gas again; Step 4, the flue gas after heat recovery is passed into the flue gas purification mechanism 6 for purification, and then discharged.

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