A two-stage dual-cycle SCR flue gas waste heat recovery device and utilization system

Abstract

This invention relates to the field of waste heat recovery technology, and in particular to a two-stage dual-cycle SCR flue gas waste heat recovery device, comprising: a heat exchange assembly including a metal heat exchanger, a protective cylinder disposed at the outlet end of the metal heat exchanger, and a fluoroplastic heat exchanger disposed at the outlet end of the protective cylinder; a heat extraction assembly including heat-conducting plates spaced apart inside the protective cylinder; a dust prevention assembly including a filter screen disposed between the heat-conducting plates; a temperature control assembly including a wax-based thermistor disposed on the outlet side of the filter screen; a flow guiding assembly including a box disposed at the top of the protective cylinder, a flow guiding hole opened at the bottom of the box body and communicating with the protective cylinder, and a fan rotatably disposed inside the box body; and a cleaning assembly including a cleaning frame disposed on one side of the filter screen; capable of achieving dual protection for the metal heat exchanger and the fluoroplastic heat exchanger under complex operating conditions of high dust, high corrosion, and high temperature fluctuations, and ensuring efficient and stable recovery of flue gas waste heat.

Description

Technical Field

[0001] This invention relates to the field of waste heat recovery technology, and in particular to a two-stage dual-cycle SCR flue gas waste heat recovery device and utilization system. Background Technology

[0002] The flue gas produced during waste incineration contains a large amount of heat energy. After denitrification treatment, the flue gas (160~170℃) of traditional SCR systems is directly emitted, resulting in energy waste.

[0003] For example, CN104132541B discloses a flue gas waste heat recovery and cascade utilization system, which includes: a flue gas waste heat recovery device, a waste heat circulating water heating device, a waste heat power generation device, and connecting pipes. The system is characterized in that: the flue gas waste heat recovery device and the waste heat circulating water heating device undergo a first-stage heat exchange through a primary heat exchanger, and the waste heat circulating water heating device and the waste heat power generation device undergo a second-stage heat exchange through a secondary heat exchanger.

[0004] Current waste heat recovery technologies mainly recover heat through single-material heat exchangers, but they face the dual challenges of low-temperature corrosion and the pressure resistance of materials.

[0005] Although fluoroplastic heat exchangers are widely used in the chemical industry, the upper limit of the internal circulating water temperature resistance (usually ≤120℃) is difficult to meet the high temperature requirements of SCR outlet flue gas. While metal heat exchangers are resistant to high temperatures, they are prone to low-temperature corrosion in acidic flue gas environments, leading to a shortened system life and increased maintenance costs. Summary of the Invention

[0006] In view of the problems that single-material heat exchangers in the above or existing technologies cannot simultaneously meet the requirements of high-temperature pressure resistance and corrosion resistance, resulting in low system efficiency, poor reliability and high maintenance costs, this invention is proposed.

[0007] Therefore, the purpose of this invention is to provide a two-stage dual-cycle SCR flue gas waste heat recovery device and utilization system.

[0008] To solve the above-mentioned technical problems, the present invention provides the following technical solution:

[0009] A two-stage dual-cycle SCR flue gas waste heat recovery device includes:

[0010] A heat exchange assembly includes a metal heat exchanger, a protective sleeve disposed at the outlet end of the metal heat exchanger, and a fluoroplastic heat exchanger disposed at the outlet end of the protective sleeve; and,

[0011] A heat extraction assembly, including heat-conducting plates spaced apart inside the protective cylinder; and;

[0012] Dustproof components include a filter screen disposed between the heat-conducting plates; and,

[0013] Temperature control components include a wax-based thermistor can disposed on the air outlet side of the filter; and,

[0014] The airflow guiding assembly includes a housing disposed at the top of the protective cylinder, an airflow guiding hole opened at the bottom of the housing and communicating with the protective cylinder, and a fan rotatably disposed inside the housing; and,

[0015] The cleaning assembly includes a cleaning frame disposed on one side of the filter screen; wherein,

[0016] The flue gas passes through the guide hole via the thermal expansion switch of the wax-based thermal canister, causing the fan to rotate. The rotation of the fan drives the cleaning frame to clean the filter and heat-conducting plate.

[0017] As a preferred embodiment of the two-stage dual-circulation SCR flue gas waste heat recovery device of the present invention, the heat extraction component further includes a ring frame disposed on the inner wall of the protective cylinder, the heat conducting plate disposed on the inner wall of the ring frame, the filter screen disposed inside the ring frame and covering the gaps of the heat conducting plate, and the ring frame, heat conducting plate and filter screen combined cover the port of the protective cylinder.

[0018] As a preferred embodiment of the two-stage dual-circulation SCR flue gas waste heat recovery device of the present invention, wherein: the two sides of the ring frame are symmetrically provided with receiving cavities, the heat-conducting plate is provided with a water tank, the two ends of the water tank are respectively connected to the receiving cavities on both sides, and the top of the receiving cavities on both sides are connected with an external pipe, the other end of the external pipe is located outside the protective cylinder.

[0019] As a preferred embodiment of the two-stage dual-circulation SCR flue gas waste heat recovery device of the present invention, wherein: a dust discharge port is provided at the bottom of the protective cylinder and below the ring frame, and a dust collection cover is provided at the bottom opening of the dust discharge port.

[0020] As a preferred embodiment of the two-stage dual-cycle SCR flue gas waste heat recovery device of the present invention, the temperature control component further includes a piston rod disposed inside the wax thermistor and a sealing cap disposed on the top of the guide hole, and a vertical rod is disposed between the top of the piston rod and the bottom of the sealing cap.

[0021] As a preferred embodiment of the two-stage dual-circulation SCR flue gas waste heat recovery device of the present invention, a supporting spring is provided between the top of the sealing cover and the inner top of the box body, and a mesh cylinder is provided at the bottom of the sealing cover, with the mesh cylinder and the guide hole being slidably connected vertically.

[0022] As a preferred embodiment of the two-stage dual-circulation SCR flue gas waste heat recovery device of the present invention, wherein: a return hole is opened at the end of the box body away from the guide hole, the fan is disposed between the guide hole and the return hole, a guide plate is disposed between the guide hole and the fan, the guide plate is inclined towards the side of the fan, and a transmission component is disposed between the fan and the cleaning frame.

[0023] As a preferred embodiment of the two-stage dual-cycle SCR flue gas waste heat recovery device of the present invention, the transmission assembly includes a support frame disposed on the inner wall of the protective cylinder, a crankshaft rotatably disposed at one end of the support frame, the other end of the crankshaft penetrating the protective cylinder and connected to the bottom shaft of the fan, a threaded sleeve disposed on the inner wall of the support frame, a lead screw disposed inside the threaded sleeve, one end of the lead screw being connected to a cleaning frame, a mounting seat rotatably disposed at the other end of the lead screw, a connecting rod hinged to the end of the mounting seat, and the other end of the connecting rod rotatably disposed on the outer surface of the crankshaft.

[0024] As a preferred embodiment of the two-stage dual-circulation SCR flue gas waste heat recovery device of the present invention, the cleaning frame has a square groove on the surface facing the filter screen, a brush is provided inside the square groove, a reset spring is provided between the inner side of the brush and the inner wall of the square groove, a retaining ring is provided at the outer port of the square groove, and the outer end of the brush penetrates through the retaining ring.

[0025] A two-stage dual-cycle SCR flue gas waste heat recovery and utilization system includes a two-stage dual-cycle SCR flue gas waste heat recovery device, and a circulating heating component connected to the SCR flue gas waste heat recovery device.

[0026] The metal heat exchanger and the fluoroplastic heat exchanger are arranged sequentially along the flue gas flow direction.

[0027] The circulating heating component includes a high-temperature section circulating loop and a low-temperature section circulating loop;

[0028] The high-temperature section circulation loop includes a high-temperature section circulating water pump P1, a primary air heater high-temperature section B1, a secondary air heater high-temperature section A1, and the metal heat exchanger connected by pipes, forming a first closed loop. The high-temperature section circulation loop is provided with a first external heating interface I1 / O1.

[0029] The low-temperature section circulation loop includes a low-temperature section circulating water pump P2, a primary air heater low-temperature section B2, a secondary air heater low-temperature section A2, and the fluoroplastic heat exchanger connected by pipes, forming a second closed loop. The low-temperature section circulation loop is provided with a second external heating interface I2 / O2.

[0030] As a preferred embodiment of the two-stage dual-cycle SCR flue gas waste heat recovery and utilization system of the present invention, it includes the following steps:

[0031] The high-temperature flue gas first enters the high-temperature section metal heat exchanger, where it exchanges heat with the circulating water in the high-temperature section circulation loop, and the flue gas temperature drops to below 140°C.

[0032] After cooling, the flue gas enters the low-temperature section fluoroplastic heat exchanger and exchanges heat with the circulating water in the low-temperature section circulation loop, further reducing the flue gas temperature to below 90°C.

[0033] The circulating water in the high-temperature section circulation loop is driven by the high-temperature section circulating water pump P1 to transfer heat to the high-temperature section B1 of the primary air heater and the high-temperature section A1 of the secondary air heater, and the heat is supplied to the outside through the first external heating interface I1 / O1.

[0034] The circulating water in the low-temperature section circulation loop is driven by the low-temperature section circulating water pump P2, which transfers heat to the low-temperature section B2 of the primary air heater and the low-temperature section A2 of the secondary air heater. The heat is then supplied to the outside through the second external heating interface I2 / O2.

[0035] The beneficial effects of the two-stage dual-cycle SCR flue gas waste heat recovery device and utilization system of the present invention are as follows: the waste heat utilization system is designed in two stages, with a metal heat exchanger in the high-temperature section and a fluoroplastic heat exchanger in the low-temperature section, which comprehensively utilizes the advantages of the two heat exchangers while avoiding their respective disadvantages.

[0036] It can provide dual protection for both metal heat exchangers and fluoroplastic heat exchangers under complex working conditions of high dust, high corrosion, and high temperature fluctuations, and ensure efficient and stable recovery of flue gas waste heat.

[0037] By installing heat extraction components inside the protective casing, the heat from the flue gas is transferred to the return water of the metal heat exchanger, ensuring that the metal wall temperature is always higher than the acid dew point, avoiding severe corrosion caused by acid condensation, and significantly extending the service life of the metal heat exchanger. The dustproof components intercept fly ash in the flue gas, and the heat extraction components cool and slow down the flow, making the flue gas entering the fluoroplastic heat exchanger clean and mild, thereby preventing it from failing due to high temperature or wear, and significantly improving the safety and durability of the fluoroplastic heat exchanger.

[0038] The temperature control component automatically detects the flue gas temperature. When the temperature is abnormal due to ash accumulation on the heat exchanger, the flow guide component is triggered, which drives the fan to rotate. The transmission mechanism then drives the cleaning component to clean the heat exchanger and filter, ensuring long-term stable operation of the system.

[0039] The transmission mechanism converts the fan's rotational power into a compound motion of reciprocating and rotating motion, enabling the cleaning components to fully cover and clean the filter and heat-conducting plate. The elastic brush design reduces friction and wear, improving cleaning efficiency and service life.

[0040] The device relies on the thermal and kinetic energy of the flue gas for automatic circulation, without the need for an additional electrical control system or external power, thus reducing energy consumption and potential failure points. Attached Figure Description

[0041] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the following description of the embodiments will be briefly introduced. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0042] Figure 1 This is a schematic diagram of the overall structure of a two-stage dual-cycle SCR flue gas waste heat recovery device and utilization system.

[0043] Figure 2 This is a schematic diagram of the dustproof component structure of a two-stage dual-cycle SCR flue gas waste heat recovery device and utilization system.

[0044] Figure 3 This is a schematic diagram of the flow guiding component structure of a two-stage dual-cycle SCR flue gas waste heat recovery device and utilization system.

[0045] Figure 4 This is a schematic diagram of the heat extraction components of a two-stage dual-cycle SCR flue gas waste heat recovery device and utilization system.

[0046] Figure 5 This is a schematic diagram of the transmission components of a two-stage dual-cycle SCR flue gas waste heat recovery device and utilization system.

[0047] Figure 6 This is a schematic diagram of the temperature control component structure of a two-stage dual-cycle SCR flue gas waste heat recovery device and utilization system.

[0048] Figure 7 This is a schematic diagram of the cleaning component structure of a two-stage dual-cycle SCR flue gas waste heat recovery device and utilization system.

[0049] Figure 8 This is a schematic diagram of a two-stage dual-cycle SCR flue gas waste heat recovery device and utilization system.

[0050] 1. Heat exchanger assembly; 11. Metal heat exchanger; 12. Fluoroplastic heat exchanger; 13. Protective casing; 2. Dustproof assembly; 21. Filter screen; 22. Dust outlet; 23. Dust collection cover; 3. Transmission assembly; 31. Support frame; 32. Crankshaft; 33. Lead screw; 34. Connecting rod; 35. Screw sleeve; 36. Mounting base; 4. Temperature control assembly; 41. Wax-based thermistor; 42. Piston rod; 43. Vertical rod; 44. 45. Mesh tube; 46. Sealing cover; 57. Support spring; 68. Cleaning assembly; 59. Cleaning frame; 50. Square groove; 51. Brush; 52. Return spring; 53. Retaining ring; 64. Flow guide assembly; 65. Box body; 66. Flow guide hole; 67. Flow guide plate; 68. Fan; 69. Return hole; 70. Heat extraction assembly; 71. Ring frame; 72. Receiving cavity; 73. Heat conduction plate; 74. Water tank; 75. External pipe. Detailed Implementation

[0051] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0052] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0053] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in different places in this specification does not necessarily refer to the same embodiment, nor is it a single or selective embodiment that is mutually exclusive with other embodiments.

[0054] Example 1

[0055] Reference Figures 1 to 7 This is the first embodiment of the present invention. This embodiment provides a two-stage dual-cycle SCR flue gas waste heat recovery device, which can effectively protect the fluoroplastic heat exchanger 12, maintain the metal heat exchanger 11 at a temperature above the acid dew point, and avoid acid corrosion and dust wear. It includes a heat exchange component 1, a heat extraction component 7, a dust prevention component 2, a temperature control component 4, a flow guiding component 6, and a cleaning component 5.

[0056] Specifically, the heat exchange assembly 1 includes a metal heat exchanger 11, a protective cylinder 13 disposed at the outlet end of the metal heat exchanger 11, and a fluoroplastic heat exchanger 12 disposed at the outlet end of the protective cylinder 13. The metal heat exchanger 11 is located in the high-temperature section of the flue gas and is in direct contact with the high-temperature flue gas, and can withstand the primary heat exchange process. The fluoroplastic heat exchanger 12 is placed in the low-temperature section of the flue gas and is used to treat the flue gas that has been cooled, slowed down, and dusted. It obtains low-grade heat energy by taking advantage of the good corrosion resistance of plastic. The protective cylinder 13 serves as a transition cavity between the two, so that the fluoroplastic heat exchanger 12 can work under the premise of being protected, thus extending its service life.

[0057] The heat extraction component 7 includes heat-conducting plates 73 spaced apart inside the protective cylinder 13. The heat-conducting plates 73 transfer heat when the flue gas flows through the protective cylinder 13 and eventually return to the circulating water circuit of the metal heat exchanger 11. This can increase the return water temperature of the metal heat exchanger 11, ensuring that its wall temperature is higher than the acid dew point range and avoiding serious corrosion problems caused by condensed sulfuric acid.

[0058] The dustproof component 2 includes a filter screen 21 disposed between the heat-conducting plates 73. The filter screen 21 is used to intercept large particles of dust such as fly ash. Since dust will severely wear down the tube wall once it enters the fluoroplastic heat exchanger 12, the filter screen 21 is combined with the heat-conducting plates 73 to form a composite protective layer, which filters while absorbing heat.

[0059] The temperature control component 4 includes a wax thermistor 41 disposed on the air outlet side of the filter 21. The wax thermistor 41 expands or contracts according to the flue gas temperature, thereby driving the opening and closing of the guide hole 62. When the heat exchange component 7 is in normal heat exchange state, the flue gas temperature is reduced to a safe range, and the wax thermistor 41 will not operate. However, if the heat conduction plate 73 fails due to severe dust accumulation, the flue gas temperature cannot be reduced. The high-temperature airflow will cause the wax thermistor 41 to expand rapidly, pushing the guide path to open, without the need for an electric control switch.

[0060] The flow guiding component 6 includes a box 61 located at the top of the protective cylinder 13, a flow guiding hole 62 located at the bottom of the box 61 and connected to the protective cylinder 13, and a fan 64 rotatably located inside the box 61. After the temperature control component 4 is triggered, the flue gas is forced to form a directional airflow through the flow guiding hole 62, which drives the fan 64 to rotate. The rotation of the fan provides a power source for the subsequent cleaning component 5.

[0061] The cleaning assembly 5 includes a cleaning frame 51 disposed on one side of the filter screen 21. The cleaning frame 51 automatically enters the working state under the drive of the fan 64 to scrape and clean the dust deposited on the surface of the filter screen 21 and the heat conduction plate 73. Since the dust has strong adhesion in the high temperature flue gas, it will seriously reduce the heat exchange efficiency if it is not cleaned in time. The cleaning assembly is driven by wind power and does not require an additional power supply, making the cleaning process automated and energy-efficient.

[0062] Through the thermal expansion switch guide hole 62 of the wax thermistor tank 41, the flue gas blows the fan 64 to rotate through the guide hole 62. The rotation of the fan 64 drives the cleaning frame 51 to clean the filter screen 21 and the heat conduction plate 73. Using temperature abnormality as a trigger condition, an automatic response mechanism is formed. When the ash accumulation problem is solved, the flue gas temperature returns to normal, the wax thermistor tank 41 retracts, the guide path is closed, and the device returns to the normal heat exchange state. The entire cycle process does not require manual intervention or external electrical control, which greatly improves the reliability of the device.

[0063] During operation, the flue gas first undergoes primary cooling and releases high-temperature heat energy through the metal heat exchanger 11. Then, it enters the protective cylinder 13, where heat is further displaced at the heat conduction plate 73 and transferred back to the return water of the metal heat exchanger 11, ensuring that its temperature is higher than the acid dew point and avoiding the risk of acid corrosion. At the same time, the filter screen 21 removes dust from the flue gas, ensuring that it has low dust, low temperature, and low speed conditions before entering the fluoroplastic heat exchanger 12, reducing the risk of wear and burnout. When the heat extraction component 7 is severely dusty, causing abnormal temperature, the temperature control component 4 immediately triggers the flow to the cleaning process, realizing online self-cleaning and completing a closed-loop control cycle.

[0064] In summary, by using the metal heat exchanger 11, the protective cylinder 13, and the fluoroplastic heat exchanger 12, along with five major components for heat extraction, dust prevention, temperature control, flow guidance, and cleaning, the problems of poor strength and low temperature resistance of the fluoroplastic heat exchanger 12 and easy acid corrosion of the metal heat exchanger 11 have been successfully solved. The circulation process is driven by the energy of the flue gas itself, achieving fully automatic protection and cleaning, and significantly reducing operating risks and maintenance costs.

[0065] Example 2

[0066] Reference Figures 1 to 7 This is the second embodiment of the present invention. Unlike the previous embodiment, this embodiment provides a structural optimization of a two-stage dual-cycle SCR flue gas waste heat recovery device.

[0067] Specifically, the heat extraction component 7 also includes a ring frame 71 disposed on the inner wall of the protective cylinder 13, a heat-conducting plate 73 disposed on the inner wall of the ring frame 71, and a filter screen 21 disposed inside the ring frame 71 and covering the gaps between the heat-conducting plates 73. The ring frame 71, the heat-conducting plates 73, and the filter screen 21 together cover the port of the protective cylinder 13. The heat-conducting plates 73 are firmly supported by the ring frame 71 to prevent displacement. The filter screen 21 is close to the inner side of the ring frame 71 and covers the space between the heat-conducting plates 73, effectively preventing dust from directly entering the fluoroplastic heat exchanger 12 by bypassing the filter screen 21.

[0068] The ring frame 71 has symmetrically arranged receiving cavities 72 on both sides. The heat conduction plate 73 has a water tank 74 inside. The two ends of the water tank 74 are connected to the receiving cavities 72 on both sides respectively. The top of the receiving cavities 72 on both sides is connected to an external pipe 75. The other end of the external pipe 75 is located outside the protective cylinder 13. Through the connection between the water tank 74 and the receiving cavity 72, a closed heat exchange circulation channel is formed, realizing the efficient transfer of heat between flue gas and circulating water. The heated return water flows to the metal heat exchanger 11 through the external pipe 75, thereby improving the overall stability of the metal wall temperature and avoiding local low temperature points.

[0069] The bottom of the protective cylinder 13, located below the ring frame 71, has a dust discharge port 22. The bottom opening of the dust discharge port 22 is covered with a dust collection cover 23, which ensures that the dust scraped off during cleaning can be discharged in a concentrated manner, avoiding secondary flying and clogging risks. The dust collection cover 23 can be removed for cleaning, making it convenient for maintenance personnel to regularly remove the accumulated dust and further extend the operating cycle of the system.

[0070] Furthermore, the temperature control component 4 also includes a piston rod 42 disposed inside the wax-based thermal canister 41 and a sealing cap 45 disposed on the top of the guide hole 62. A vertical rod 43 is disposed between the top of the piston rod 42 and the bottom of the sealing cap 45. A support spring 46 is disposed between the top of the sealing cap 45 and the inner top of the housing 61. A mesh cylinder 44 is disposed at the bottom of the sealing cap 45. The mesh cylinder 44 is slidably connected to the guide hole 62. When the high-temperature flue gas triggers expansion, the piston rod pushes the vertical rod to lift the sealing cap, causing the guide hole to open rapidly. After the flue gas cools down, the support spring 46 pushes the sealing cap 45 back down, forming a reliable closing process, avoiding air leakage, improving the sensitivity and reliability of the temperature control component 4, and reducing the probability of malfunction.

[0071] The rest of the structure is the same as in Example 1.

[0072] During operation, the flue gas enters the protective cylinder 13 after primary heat exchange in the metal heat exchanger 11. It passes through the heat-conducting plate 73 and filter screen 21 supported by the ring frame 71. The heat-conducting plate 73 absorbs heat and feeds it back to the return water of the metal heat exchanger 11, maintaining the wall temperature above the acid dew point. In addition, the filter screen 21 effectively intercepts fly ash in the flue gas, reducing the risk of wear on the downstream fluoroplastic heat exchanger 12. When the heat-conducting plate 73 accumulates too much ash, causing the flue gas temperature to rise abnormally, the wax thermistor tank 41 activates the temperature control component 4, driving the sealing cover 45 to open the guide hole 62. The flue gas drives the fan 64 to rotate and drives the cleaning frame 51 to clean the heat-conducting plate 73 and filter screen 21 through the transmission component 3. After cleaning, the system returns to normal, realizing adaptive and closed-loop operation.

[0073] In summary, the ring frame 71 improves the stability and heat conduction of the internal components of the protective cylinder 13, and the dust outlet 22 and dust collection cover 23 enable centralized cleaning of dust. At the same time, the improved temperature control component 4 adds sealing and buffering functions, improving the stability of the triggering action.

[0074] Example 3

[0075] Reference Figures 1 to 7 This is the third embodiment of the present invention. Unlike the previous embodiment, this embodiment provides a structural optimization of a two-stage dual-cycle SCR flue gas waste heat recovery device.

[0076] Specifically, a return hole 65 is provided at the end of the housing 61 away from the guide hole 62. The fan 64 is located between the guide hole 62 and the return hole 65. A guide plate 63 is provided between the guide hole 62 and the fan 64. The guide plate 63 is inclined towards the side facing the fan 64. A transmission component 3 is provided between the fan 64 and the cleaning frame 51. The inclined angle design of the guide plate 63 can guide the flue gas to blow the fan 64 more concentratedly, thereby obtaining a stronger rotational torque and providing a stable power source for the transmission component 3. The return hole 65 ensures that some flue gas can be smoothly discharged after driving the fan 64, avoiding excessive resistance in the cavity.

[0077] The transmission assembly 3 includes a support frame 31 disposed on the inner wall of the protective cylinder 13. A crankshaft 32 is rotatably disposed at one end of the support frame 31, and the other end of the crankshaft 32 penetrates the protective cylinder 13 and is connected to the bottom shaft of the fan 64. A threaded sleeve 35 is disposed on the inner wall of the support frame 31, and a lead screw 33 is disposed inside the threaded sleeve 35. One end of the lead screw 33 is connected to the cleaning frame 51, and a mounting base 36 is rotatably disposed at the other end of the lead screw 33. A connecting rod 34 is hinged to the end of the mounting base 36, and the other end of the connecting rod 34 is rotatably disposed on the outer surface of the crankshaft 32. The transmission assembly 3 converts the power generated by the rotation of the fan 64 into a compound motion through the crankshaft 32. The compound motion effectively avoids dead corners caused by single scraping, making cleaning more thorough.

[0078] The cleaning frame 51 has a square groove 52 on its surface facing the filter screen 21. A brush 53 is installed inside the square groove 52. A return spring 54 is installed between the inner side of the brush 53 and the inner wall of the square groove 52. A retaining ring 55 is installed at the outer end of the square groove 52. The outer end of the brush 53 penetrates through the retaining ring 55. Under the action of the return spring 54, the brush 53 has flexible contact capability. When the cleaning frame 51 reciprocates, the brush 53 periodically presses into the filter screen 21, which can effectively remove the deposited dust and reduce wear caused by long-term friction. The retaining ring 55 restricts the stroke of the brush 53 to avoid structural damage due to excessive extension.

[0079] The rest of the structure is the same as in Example 1.

[0080] When in use, when the flue gas temperature is too high, the temperature control component 4 is triggered. The flue gas drives the fan 64 to rotate through the guide hole 62. The rotation of the fan 64 is transmitted to the cleaning frame 51 through the crankshaft 32, connecting rod 34 and lead screw 33, so that it performs reciprocating and rotating actions at the same time. The cleaning frame 51 drives the brush 53 to periodically contact the filter screen 21 and the heat conduction plate 73 to achieve dust removal and unblocking functions. Since the action has intermittent contact characteristics, continuous friction will not be formed, thereby reducing the wear rate. The process does not require manual intervention and automatically completes the dust accumulation detection and cleaning closed loop.

[0081] In summary, the transmission component 3 converts the rotation of the fan 64 driven by the kinetic energy of the flue gas into a compound motion, enabling the cleaning component 5 to have both reciprocating and rotating actions, thus achieving full-coverage cleaning of the filter screen 21 and the heat-conducting plate 73. At the same time, the brush 53 and the return spring 54 ensure the flexibility and durability of the cleaning process.

[0082] Example 4

[0083] Reference Figure 8 This is the fourth embodiment of the present invention. Unlike the previous embodiment, this embodiment provides a two-stage dual-cycle SCR flue gas waste heat recovery and utilization system, including a two-stage dual-cycle SCR flue gas waste heat recovery device in the above embodiment.

[0084] Specifically, it also includes a circulating heating component connected to the SCR flue gas waste heat recovery device;

[0085] Metal heat exchanger 11 and fluoroplastic heat exchanger 12 are arranged sequentially along the flue gas flow direction. Metal heat exchanger 11 is fixed in the flue through a welded flange, and fluoroplastic heat exchanger 12 is connected to the pipeline through a flange.

[0086] The circulating heating system includes a high-temperature section circulation loop and a low-temperature section circulation loop;

[0087] The high-temperature section circulation loop includes a high-temperature section circulating water pump P1, a primary air heater high-temperature section B1, a secondary air heater high-temperature section A1, and a metal heat exchanger 11 connected by pipes, forming a first closed loop. The high-temperature section circulation loop is equipped with a first external heating interface I1 / O1.

[0088] The low-temperature section circulation loop includes a low-temperature section circulating water pump P2, a primary air heater low-temperature section B2, a secondary air heater low-temperature section A2, and a fluoroplastic heat exchanger 12 connected by pipes, forming a second closed loop. A second external heating interface I2 / O2 is provided on the low-temperature section circulation loop.

[0089] The high-temperature section metal heat exchanger 11 is made of duplex stainless steel;

[0090] The high-temperature section metal heat exchanger 11 is divided into a high-temperature section and a low-temperature section along the flue gas or circulating water flow. The high-temperature section is made of ND steel or carbon steel, and the low-temperature section is made of duplex stainless steel.

[0091] The distinction between the high-temperature and low-temperature sections is based on a circulating water temperature of 130℃. The area with a circulating water temperature above 130℃ is the high-temperature section, and the area with a circulating water temperature below 130℃ is the low-temperature section.

[0092] The low-temperature section fluoroplastic heat exchanger 12 uses a PTFE tube bundle with a wall thickness of no more than 1.5 mm and a tube diameter of no more than 20 mm.

[0093] The first external heating interface I1 / O1 and / or the second external heating interface I2 / O2 are connected to the turbine condensate system or the boiler feedwater system;

[0094] It also includes a flue gas bypass valve and a standby heat exchanger group. The flue gas bypass valve is used to switch the flue gas to the standby heat exchanger group when an over-temperature is detected.

[0095] The material of the high-temperature section metal heat exchanger 11 can be replaced with Hastelloy C276; the material of the low-temperature section fluoroplastic heat exchanger 12 can be replaced with perfluoroalkoxy resin PFA.

[0096] Includes the following steps:

[0097] The high-temperature flue gas first enters the high-temperature section metal heat exchanger 11, where it exchanges heat with the circulating water in the high-temperature section circulation loop, and the flue gas temperature drops to below 140°C.

[0098] The cooled flue gas enters the low-temperature section fluoroplastic heat exchanger 12 and exchanges heat with the circulating water in the low-temperature section circulation loop, further reducing the flue gas temperature to below 90°C.

[0099] The circulating water in the high-temperature section circulation loop is driven by the high-temperature section circulating water pump P1 to transfer heat to the high-temperature section B1 of the primary air heater and the high-temperature section A1 of the secondary air heater, and / or the heat is supplied to the outside through the first external heating interface I1 / O1.

[0100] The circulating water in the low-temperature section circulation loop is driven by the low-temperature section circulating water pump P2 to transfer heat to the low-temperature section B2 of the primary air heater and the low-temperature section A2 of the secondary air heater, and / or the heat is supplied to the outside through the second external heating interface I2 / O2.

[0101] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A two-stage double-circulation SCR flue gas waste heat recovery device, characterized in that, The application relates to a heat exchange assembly (1) comprising a metal heat exchanger (11), a protective cylinder (13) arranged at the gas outlet end of the metal heat exchanger (11), and a fluoroplastic heat exchanger (12) arranged at the gas outlet end of the protective cylinder (13); a heat extraction assembly (7) comprising heat-conducting plates (73) arranged at intervals in the interior of the protective cylinder (13); a dustproof assembly (2) comprising filter screens (21) arranged between the heat-conducting plates (73); a temperature control assembly (4) comprising a waxy heat-sensitive tank (41) arranged at the air outlet side of the filter screens (21); a flow guide assembly (6) comprising a box body (61) arranged at the top of the protective cylinder (13), a flow guide hole (62) arranged at the inner bottom of the box body (61) and connected with the protective cylinder (13), and a fan (64) rotatably arranged in the interior of the box body (61); and a cleaning assembly (5) comprising a cleaning frame (51) arranged at one side of the filter screens (21). The heat expansion of the waxy heat-sensitive tank (41) opens or closes the flow guide hole (62), flue gas blows the fan (64) to rotate through the flow guide hole (62), and the rotation of the fan (64) drives the cleaning frame (51) to clean the filter screens (21) and the heat-conducting plates (73). The heat extraction assembly (7) further comprises a ring frame (71) arranged on the inner wall of the protective cylinder (13), the heat-conducting plates (73) are arranged on the inner wall of the ring frame (71), the filter screens (21) are arranged in the interior of the ring frame (71) and cover the interval gaps of the heat-conducting plates (73), and the ring frame (71), the heat-conducting plates (73) and the filter screens (21) combine to cover the port of the protective cylinder (13). The interior of the two sides of the ring frame (71) is symmetrically provided with containing cavities (72), the interior of the heat-conducting plates (73) is provided with water grooves (74), the two ends of the water grooves (74) are respectively connected with the containing cavities (72) on the two sides, the top of the containing cavities (72) on the two sides is connected with external connecting pipes (75), and the other end of the external connecting pipes (75) is located outside the protective cylinder (13). The bottom of the protective cylinder (13) and below the ring frame (71) is provided with a dust discharging port (22), and the bottom opening of the dust discharging port (22) is covered with a dust collecting cover (23). The temperature control assembly (4) further comprises a piston rod (42) arranged in the interior of the waxy heat-sensitive tank (41) and a sealing cover (45) arranged at the top of the flow guide hole (62), a vertical rod (43) is arranged between the top of the piston rod (42) and the bottom of the sealing cover (45), a supporting spring (46) is arranged between the top of the sealing cover (45) and the inner top of the box body (61), the bottom of the sealing cover (45) is provided with a mesh cylinder (44), and the mesh cylinder (44) is connected with the flow guide hole (62) in a sliding mode. ​ ​ ​ ​ 2. The two-stage, dual-circuit, SCR flue gas heat recovery device of claim 1, wherein: ​ 3. A two-stage, dual-circuit, SCR flue gas heat recovery device as claimed in claim 2, characterised in that: ​ 4. The two-stage, dual-circuit, SCR flue gas heat recovery device of claim 3, wherein: The box body (61) is provided with a backflow hole (65) at one end away from the flow guide hole (62), the fan (64) is arranged between the flow guide hole (62) and the backflow hole (65), a flow guide plate (63) is arranged between the flow guide hole (62) and the fan (64), one side of the flow guide plate (63) facing the fan (64) is arranged in an inclined manner, and a transmission assembly (3) is arranged between the fan (64) and the cleaning frame (51).

5. The two-stage, dual-circuit, SCR flue gas heat recovery device of claim 4, wherein: The transmission assembly (3) comprises a support frame (31) arranged on the inner wall of the protective cylinder (13), one end of the support frame (31) is rotatably provided with a crankshaft (32), the other end of the crankshaft (32) penetrates the protective cylinder (13) and is connected to the bottom shaft of the fan (64), the inner wall of the support frame (31) is provided with a threaded sleeve (35), the inside of the threaded sleeve (35) is provided with a lead screw (33), one end of the lead screw (33) is connected to the cleaning frame (51), the other end of the lead screw (33) is rotatably provided with a mounting seat (36), the distal end of the mounting seat (36) is hingedly provided with a connecting rod (34), and the other end of the connecting rod (34) is rotatably arranged on the outer surface of the crankshaft (32).

6. A two-stage, dual-circuit, SCR flue gas heat recovery device as set forth in Claim 5, characterized in that: The surface of the cleaning frame (51) facing the filter screen (21) is provided with a square groove (52), the inside of the square groove (52) is provided with a plate brush (53), the inner side of the plate brush (53) and the inner wall of the square groove (52) are provided with a return spring (54), and the outer end of the square groove (52) is provided with a check ring (55), and the outer end of the plate brush (53) penetrates the check ring (55).

7. A two-stage double-circulation SCR flue gas waste heat recovery system comprising the two-stage double-circulation SCR flue gas waste heat recovery device according to any one of claims 1-6, characterized in that: Further comprising a circulating heat supply assembly connected with the SCR flue gas waste heat recovery device; The metal heat exchanger (11) and the fluoroplastic heat exchanger (12) are arranged in sequence along the flue gas flow direction; The circulating heat supply assembly comprises a high-temperature section circulating loop and a low-temperature section circulating loop; The high-temperature section circulating loop comprises a high-temperature section circulating water pump P1, a primary air warm air heater high-temperature section B1, a secondary air warm air heater high-temperature section A1 and the metal heat exchanger (11) connected through pipelines, forming a first closed loop, and a first external heat supply interface I1 / O1 is arranged on the high-temperature section circulating loop; The low-temperature section circulating loop comprises a low-temperature section circulating water pump P2, a primary air warm air heater low-temperature section B2, a secondary air warm air heater low-temperature section A2 and the fluoroplastic heat exchanger (12) connected through pipelines, forming a second closed loop, and a second external heat supply interface I2 / O2 is arranged on the low-temperature section circulating loop.

8. The two-stage, dual-cycle, SCR flue gas heat recovery system of claim 7, wherein: The method comprises the following steps: S1, high-temperature flue gas first enters the high-temperature section metal heat exchanger (11), exchanges heat with circulating water in the high-temperature section circulating loop, and the flue gas temperature is reduced to below 140 DEG C; S2, the cooled flue gas enters the low-temperature section fluoroplastic heat exchanger (12), exchanges heat with circulating water in the low-temperature section circulating loop, and the flue gas temperature is further reduced to below 90 DEG C; S3, through the high temperature section circulating water pump P1 drive high temperature section circulating loop in the circulating water, the heat to the primary air heater high temperature section B1 and secondary air heater high temperature section A1, through the first external heat supply interface I1 / O1 will heat to external supply; S4, through the low temperature section circulating water pump P2 drive low temperature section circulating loop in the circulating water, the heat to the primary air heater low temperature section B2 and secondary air heater low temperature section A2, through the second external heat supply interface I2 / O2 will heat to external supply.

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