A heat energy recovery device and method for exhaust gas purification system

Abstract

The present invention relates to the field of heat recovery, specifically to a heat recovery device and method for an exhaust gas purification system, which includes a heat recovery mechanism, wherein the air inlet end of the heat recovery mechanism is connected to the air inlet pipe, and the air outlet end of the heat recovery mechanism is connected to the air outlet pipe; the heat recovery mechanism includes a heat exchange straight pipe and a plurality of heat exchange U-shaped pipes arranged on the heat exchange straight pipe, and a control system is used to control the exhaust gas flow path, and the number of pipe bending sections on the heat exchange path increases by four for each additional heat exchange U-shaped pipe through which the exhaust gas flows; temperature sensors are arranged in the air inlet pipe, the air outlet pipe, the liquid inlet pipe and the liquid outlet pipe, and a flow rate sensor for detecting the liquid flow rate is arranged in the heat exchange box. In the present invention, according to different use parameters, the number of bending sections and the number of heat exchange U-shaped pipes that need to be put into the path are calculated by a formula, so as to reduce the exhaust gas transportation resistance while ensuring heat recovery, reduce the heat energy loss caused by the temperature rise of the external pipeline of the heat exchange box, and reduce the working power of the exhaust gas transportation equipment.

Description

Technical Field

[0001] The present invention relates to the technical field of heat energy recovery, and in particular to a heat energy recovery device and method for an exhaust gas purification system. Background Art

[0002] There are many key equipment in the printing and dyeing industry, such as setting machines. These equipment will generate a large amount of high-temperature exhaust gas during operation, and the exhaust gas needs to be treated before it can be discharged. In order to recover heat energy, exhaust gas heat recovery devices came into being. This type of device mainly uses the heat energy contained in the exhaust gas, recovers it through a series of means and reuses it.

[0003] A Chinese patent with announcement number CN217287617U discloses a waste gas heat energy recovery device for silicone resin production. Through the design of a heat energy recovery mechanism and a waste gas filter assembly, the heat energy in the waste gas is converted into cold water in a heat energy recovery box by using a heat energy conversion tube in the heat energy recovery mechanism. The waste gas is then filtered by two sets of filter plates in the waste gas filter assembly and drained by an exhaust fan, and finally discharged from the exhaust pipe. This method achieves effective recovery of heat energy in the waste gas, avoids energy waste, improves energy utilization, and effectively avoids environmental pollution.

[0004] However, the above-mentioned disclosed solutions have the following shortcomings: the heat energy conversion tube is a curved tube with multiple bending sections. Although theoretically, the more bending sections there are, the better the heat energy recovery effect of the exhaust gas (the bending sections will induce turbulence and eddy currents in the fluid, and these flow forms increase the mixing of the fluid), the bending sections will increase the resistance to exhaust gas flow, thereby increasing the working power of the air delivery equipment, resulting in problems such as increased temperature rise and reduced transportation efficiency. The structure of the heat energy conversion tube in the disclosed technical solution is fixed, and the number of bending sections is also fixed. It is impossible to reasonably adjust the number of bending sections according to different exhaust gas heat energy recovery situations, so as to achieve the purpose of reducing temperature rise and improving transportation efficiency while ensuring the exhaust gas heat energy recovery effect. Summary of the invention

[0005] The purpose of the present invention is to address the problem in the background technology that the structure of the energy conversion tube is fixed and the number of bending sections cannot be specifically adjusted according to different exhaust gas heat energy recovery conditions, and to propose a heat energy recovery device and method for an exhaust gas purification system.

[0006] On the one hand, the present invention provides a heat recovery device for an exhaust gas purification system, comprising a heat exchange box, an air inlet pipe and a liquid inlet pipe are arranged on one side of the heat exchange box, and an air outlet pipe and a liquid outlet pipe are arranged on the other side; and further comprising a heat recovery mechanism, wherein the air inlet end of the heat recovery mechanism is connected to the air inlet pipe, and the air outlet end of the heat recovery mechanism is connected to the air outlet pipe;

[0007] The heat energy recovery mechanism includes a heat exchange straight pipe and a plurality of heat exchange U-shaped pipes arranged on the heat exchange straight pipe. A control system is arranged on the heat exchange box, and the control system is used to control the exhaust gas flow path. For each additional heat exchange U-shaped pipe through which the exhaust gas flows, the number of pipe bends on the heat exchange path increases by four.

[0008] Temperature sensors are arranged in the air inlet pipe, the air outlet pipe, the liquid inlet pipe and the liquid outlet pipe, and a flow rate sensor for detecting the liquid flow rate is arranged in the heat exchange box; the control system is connected with the temperature sensor and the flow rate sensor for data transmission.

[0009] Preferably, a plurality of tees are provided on the heat exchange straight tube, and every two adjacent tees form a pair, and both ends of the heat exchange U-shaped tube are respectively connected to two tees in a pair.

[0010] Preferably, a plurality of straight tube gate valves are arranged on the heat exchange straight tube, the straight tube gate valve is located between a pair of tees, and the handwheel of the straight tube gate valve is removed; U-shaped tube gate valves are arranged on the two vertical sections of the heat exchange U-shaped tube, the valve stems of the two U-shaped tube gate valves are in a horizontal state and are respectively located above the left and right sides of the straight tube gate valve, and the handwheels of the two U-shaped tube gate valves are removed; a control component is arranged on the heat exchange box, and the control component is used to control the opening and closing of the straight tube gate valve and the U-shaped tube gate valve.

[0011] Preferably, the following parameters are defined: the inner diameter D of the exhaust gas flow pipe, the initial temperature T1 of the exhaust gas, the design temperature T2 of the exhaust gas after heat recovery, the actual flow length L of the exhaust gas flow pipe, the number of bending sections Z of the exhaust gas flow pipe in the liquid medium box, the flow speed S of the liquid medium in the box, and the heat transfer coefficient h of the liquid medium, wherein the actual flow length L of the exhaust gas flow pipe = 2Z + 7; the number of bending sections , the calculation result is rounded up, the number of heat exchange U-tubes put into use is approximately calculated to be Z / 4, and the calculation result is rounded up.

[0012] Preferably, the control component synchronously controls the straight tube gate valve and the U-tube gate valve, and when the straight tube gate valve is opened, the two U-tube gate valves are closed, and the exhaust gas flows through the heat exchange straight tube; when the straight tube gate valve is closed, the two U-tube gate valves are opened, and the exhaust gas flows through the heat exchange U-tube; the control system is controlled and connected to each control component.

[0013] Preferably, the control assembly includes an extension rod resin-arranged on the top of the straight tube gate valve stem, an intermediate bevel gear and an extension rod gear arranged on the extension rod, a bevel gear arranged on the two U-tube gate valve stems and meshing with the intermediate bevel gear, a rotating shaft vertically and rotatably arranged on the top of the heat exchange box, and a lower gear of the rotating shaft arranged on the rotating shaft and meshing with the extension rod gear; a power module for driving the rotating shaft to rotate is arranged on the heat exchange box, and the control system is control-connected to the power module.

[0014] Preferably, the power module includes a gear on a rotating shaft arranged at the top of the rotating shaft, a rack slidably arranged on the top outer wall of the heat exchanger box, a fixed block arranged on the back of the rack, a mounting block arranged on the top outer wall of the heat exchanger box, and a telescopic device horizontally arranged on the mounting block, the telescopic end of the telescopic device is connected to the fixed block, and the control system is control-connected to the telescopic device.

[0015] Preferably, a plurality of heat recovery mechanisms are arranged in parallel in the width direction of the heat exchange box, and the ends of two adjacent straight heat exchange tubes are connected by a U-shaped connecting tube. The plurality of straight heat exchange tubes and the U-shaped connecting tube constitute a unidirectional exhaust gas flow route.

[0016] On the other hand, the present invention provides a heat energy recovery method of a heat energy recovery device of an exhaust gas purification system, comprising the following steps:

[0017] S1. According to different usage parameters, the number of bending sections is calculated by the formula, and then the number of heat exchange U-tubes that need to be put into the path is calculated according to the number of bending sections;

[0018] S2. The control system controls the opening and closing states of different straight pipe gate valves and U-shaped pipe gate valves to adjust the exhaust gas flow path and obtain the required exhaust gas flow path;

[0019] S3. The exhaust gas enters the heat recovery mechanism through the air inlet pipe, circulates in the heat recovery mechanism and is discharged through the air outlet pipe. The exhaust gas transfers heat to the flowing liquid in the heat exchange box, completing the heat recovery of the exhaust gas.

[0020] Compared with the prior art, the present invention has the following beneficial technical effects: the exhaust gas enters the heat recovery mechanism through the air inlet pipe, circulates in the heat recovery mechanism and is discharged through the air outlet pipe, and the exhaust gas transfers heat to the flowing liquid in the heat exchange box to complete the heat recovery of the exhaust gas. According to different usage parameters, the number of bending sections is calculated by the formula, and then the number of heat exchange U-shaped tubes that need to be put into the path is calculated according to the number of bending sections. Finally, the control system controls the actions of different telescopic devices to complete the adjustment of the exhaust gas passing path and obtain the required exhaust gas flow path, thereby reducing the exhaust gas transportation resistance while ensuring heat recovery, reducing the heat energy loss caused by the temperature rise of the external pipeline of the heat exchange box, and reducing the working power of the exhaust gas transportation equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 A schematic diagram of the structure of an embodiment of the present invention;

[0022] Figure 2 for Figure 1 Schematic diagram of the internal structure of the heat exchange box;

[0023] Figure 3 for Figure 1 A is an enlarged schematic diagram;

[0024] Figure 4 for Figure 2 Schematic diagram of some structures in ;

[0025] Figure 5 It is a connection diagram of the multi-column heat recovery mechanism of the present invention.

[0026] Figure numerals: 1. heat exchange box; 2. liquid inlet pipe; 3. liquid outlet pipe; 4. air inlet pipe; 5. air outlet pipe; 6. heat exchange straight pipe; 7. tee; 8. straight pipe gate valve; 9. heat exchange U-tube; 10. U-tube gate valve; 11. extension rod; 12. bevel gear; 13. intermediate bevel gear; 14. extension rod gear; 15. rotating shaft; 16. strengthening sleeve; 17. rack; 18. fixing block; 19. mounting block; 20. telescopic device; 21. gear under the rotating shaft; 22. gear on the rotating shaft; 23. U-shaped connecting pipe. DETAILED DESCRIPTION

[0027] Embodiment 1, as Figure 1-Figure 2 As shown, a heat energy recovery device of an exhaust gas purification system proposed by the present invention comprises a heat exchange box 1, an air inlet pipe 4 and a liquid inlet pipe 2 are arranged on one side of the heat exchange box 1, and an air outlet pipe 5 and a liquid outlet pipe 3 are arranged on the other side. The flow direction of the liquid in the heat exchange box 1 is the same as the overall flow direction of the exhaust gas. In the present invention, the overall flow direction of the liquid and the exhaust gas is from left to right, so that the liquid with the lowest temperature can contact the exhaust gas with the highest temperature, thereby improving the heat exchange effect. In order to prevent the liquid from losing temperature to the outside through the heat exchange box 1, the heat exchange box 1 is a poor conductor of heat; it also comprises a heat energy recovery mechanism, the air inlet end of the heat energy recovery mechanism is connected to the air inlet pipe 4, and the air outlet end of the heat energy recovery mechanism is connected to the air outlet pipe 5;

[0028] The heat energy recovery mechanism includes a heat exchange straight tube 6 and a plurality of heat exchange U-shaped tubes 9 arranged on the heat exchange straight tube 6. Specifically, a plurality of tees 7 are arranged on the heat exchange straight tube 6, and every two adjacent tees 7 form a pair. The two ends of the heat exchange U-shaped tube 9 are respectively connected to the two tees 7 in the pair. A plurality of straight tube gate valves 8 are arranged on the heat exchange straight tube 6. The straight tube gate valve 8 is located between the pair of tees 7, and the hand wheel of the straight tube gate valve 8 is removed; U-shaped tube gate valves 10 are arranged on the two vertical sections of the heat exchange U-shaped tube 9, and the valve stems of the two U-shaped tube gate valves 10 are in a horizontal state and are respectively located above the left and right sides of the straight tube gate valve 8. The handwheels of the U-tube gate valves 10 are removed; a control component is set on the heat exchange box 1, and the control component is used to control the opening and closing of the straight tube gate valve 8 and the U-tube gate valve 10; a control system is set on the heat exchange box 1, and the control system is used to control the exhaust gas flow path. For each additional heat exchange U-tube 9 through which the exhaust gas flows, the number of pipe bending sections on the heat exchange path increases by four; the number of appropriate bending sections is controlled to reduce the conveying resistance and improve the conveying efficiency while ensuring the recovery of exhaust gas heat energy, thereby improving the conveying efficiency, reducing the working power of the exhaust gas conveying equipment, and reducing the heat waste caused by the temperature rise of the pipeline outside the heat exchange box 1.

[0029] Temperature sensors are arranged in the air inlet pipe 4, the air outlet pipe 5, the liquid inlet pipe 2 and the liquid outlet pipe 3, and a flow rate sensor for detecting the liquid flow rate is arranged in the heat exchange box 1; the control system is connected with the temperature sensor and the flow rate sensor for data transmission.

[0030] A plurality of heat recovery mechanisms are arranged in parallel in the width direction of the heat exchange box 1. The ends of two adjacent heat exchange straight tubes 6 are connected by a U-shaped connecting tube 23. The plurality of heat exchange straight tubes 6 and the U-shaped connecting tube 23 constitute a unidirectional exhaust gas flow route. By arranging a plurality of heat recovery mechanisms, the length of the equipment can be shortened, making the structure more compact, and more bending sections can be provided. According to the actual heat exchange requirements, more bending sections can be provided.

[0031] Embodiment 2 is a heat recovery device for an exhaust gas purification system proposed by the present invention. Compared with embodiment 1, this embodiment introduces in detail a method for calculating the number of heat exchange U-tubes 9 put into use.

[0032] The following parameters are defined: the inner diameter D of the exhaust gas flow pipe, the initial temperature T1 of the exhaust gas, the design temperature T2 of the exhaust gas after heat recovery, the actual flow length L of the exhaust gas flow pipe, the number of bending sections Z of the exhaust gas flow pipe in the liquid medium box, the flow speed S of the liquid medium in the box, the heat transfer coefficient h of the liquid medium, where the actual flow length L of the exhaust gas flow pipe = 2Z + 7; the number of bending sections , the calculation result is rounded up, and the number of heat exchange U-tubes 9 put into use is approximately calculated to be Z / 4, and the calculation result is rounded up.

[0033] The design ideas of the above calculation formula are as follows:

[0034] Assuming that heat exchange follows Newton's law of cooling, we can express the heat exchange process as:

[0035]

[0036] Among them, Q is the heat transferred by heat exchange per unit time, h is the heat transfer coefficient of the liquid medium, and A is the heat exchange area. The heat exchange area A can be expressed as the product of the inner diameter D of the exhaust gas flow pipe and the length L of the exhaust gas flow pipe in the liquid medium box, that is: , L=2Z+7, therefore, Next, we need to consider the heat Q that the exhaust gas needs to transfer during the heat recovery process, which can also be expressed as:

[0037]

[0038] Where m is the mass flow rate of the exhaust gas and c is the specific heat capacity of the exhaust gas. In order for the exhaust gas to reach the design temperature T2, the following heat balance needs to be satisfied:

[0039]

[0040] Since T1-T2 exists on both sides of the equation, we can eliminate it and get:

[0041]

[0042] If c is known, we can solve for Z:

[0043] .

[0044] Here is a specific example to illustrate the application of the formula:

[0045] Exhaust gas flow pipe inner diameter D = 0.1m

[0046] Exhaust gas initial temperature T1 = 500°C

[0047] Exhaust gas design temperature T2 = 300°C

[0048] Heat transfer coefficient of liquid medium h=1000W / m²·K

[0049] Mass flow rate of exhaust gas m=0.5kg / s

[0050] Specific heat capacity of exhaust gas c = 1000 J / kg·K

[0051] Substituting these values ​​into the formula, we get:

[0052] =4.46

[0053] Then Z / 4 is rounded up to 2, and the number of heat exchange U-tubes 9 in the input path is two, and the required exhaust gas path can be obtained by controlling the opening and closing of each gate valve through the control system. According to actual usage and a large amount of data verification of manual adjustment, the above formula can be well applied to different exhaust gas heat recovery situations.

[0054] According to different heat exchange scenarios, the required bending sections are calculated, and then the number of heat exchange U-tubes 9 that need to be put into use is obtained, while ensuring heat energy recovery and reducing exhaust gas transportation resistance.

[0055] Embodiment three, as Figure 3-Figure 5 As shown, a heat recovery device for an exhaust gas purification system proposed in the present invention, compared with the first or second embodiment, this embodiment introduces the structure of the control component in detail.

[0056] The control component synchronously controls the straight tube gate valve 8 and the U-tube gate valve 10, and when the straight tube gate valve 8 is opened, the two U-tube gate valves 10 are closed, and the exhaust gas flows through the heat exchange straight tube 6; when the straight tube gate valve 8 is closed, the two U-tube gate valves 10 are opened, and the exhaust gas flows through the heat exchange U-tube 9; the control system is controlled and connected to each control component.

[0057] Further, the control assembly includes an extension rod 11 resin-mounted on the top of the valve stem of the straight pipe gate valve 8, an intermediate bevel gear 13 and an extension rod gear 14 mounted on the extension rod 11, a bevel gear 12 mounted on the valve stems of the two U-shaped pipe gate valves 10 and meshing with the intermediate bevel gear 13, a rotating shaft 15 vertically and rotatably mounted on the top of the heat exchange box 1, and a lower shaft gear 21 mounted on the rotating shaft 15 and meshing with the extension rod gear 14. In order to improve the rotation stability of the rotating shaft 15, a vertically mounted inner wall on the top of the heat exchange box 1 is provided. The reinforcing sleeve 16, the rotating shaft 15 coaxially passes through the reinforcing sleeve 16, and multiple rotating shafts are arranged between the rotating shaft 15 and the reinforcing sleeve 16; a power module for driving the rotating shaft 15 to rotate is arranged on the heat exchange box 1, and the control system is connected to the control of the power module. A single action of the power module causes the rotating shaft 15 to rotate a set angle, which just makes the states of the straight tube gate valve 8 and the U-tube gate valve 10 interchange, that is, when the straight tube gate valve 8 turns from open to closed, the U-tube gate valve 10 turns from closed to open, and when the straight tube gate valve 8 turns from closed to open, the U-tube gate valve 10 turns from open to closed.

[0058] Embodiment 4, as Figure 3 As shown, a heat energy recovery device for an exhaust gas purification system proposed by the present invention, compared with the third embodiment, this embodiment introduces the structure of the power module in detail.

[0059] The power module includes a gear 22 on the rotating shaft arranged at the top of the rotating shaft 15, a rack 17 slidably arranged on the top outer wall of the heat exchange box 1, a fixed block 18 arranged on the back of the rack 17, a mounting block 19 arranged on the top outer wall of the heat exchange box 1, and a telescopic device 20 horizontally arranged on the mounting block 19, the telescopic end of the telescopic device 20 is connected to the fixed block 18, and the control system is controlled and connected to the telescopic device 20. When the telescopic device 20 is fully retracted, the straight tube gate valve 8 is opened and the U-shaped tube gate valve 10 is closed. When the telescopic device 20 is fully extended, the straight tube gate valve 8 is closed and the U-shaped tube gate valve 10 is opened.

[0060] Embodiment 5, a heat energy recovery method based on the heat energy recovery device embodiment of the exhaust gas purification system comprises the following steps:

[0061] S1. According to different usage parameters, the number of bending sections is calculated by a formula, and then the number of heat exchange U-shaped tubes 9 that need to be put into the path is calculated according to the number of bending sections;

[0062] S2, the control system controls the opening and closing states of different straight pipe gate valves 8 and U-shaped pipe gate valves 10 to adjust the exhaust gas flow path and obtain the required exhaust gas flow path;

[0063] S3. The exhaust gas enters the heat recovery mechanism through the air inlet pipe 4, circulates in the heat recovery mechanism and is discharged through the air outlet pipe 5. The exhaust gas transfers heat to the flowing liquid in the heat exchange box 1, completing the heat recovery of the exhaust gas.

[0064] In summary, when the present invention is in use, the exhaust gas enters the heat recovery mechanism through the air inlet pipe 4, circulates in the heat recovery mechanism and is discharged through the air outlet pipe 5. The exhaust gas transfers heat to the flowing liquid in the heat exchange box 1 to complete the heat recovery of the exhaust gas. According to different usage parameters, the number of bending sections is calculated by the formula, and then the number of heat exchange U-shaped tubes 9 that need to be put into the path is calculated according to the number of bending sections. Finally, the control system controls the actions of different telescopic devices 20 to complete the adjustment of the exhaust gas passing path and obtain the required exhaust gas flow path, thereby reducing the exhaust gas transportation resistance while ensuring heat recovery, reducing the heat loss caused by the temperature rise of the external pipeline of the heat exchange box 1, and reducing the working power of the exhaust gas transportation equipment.

[0065] The embodiments of the present invention are described in detail above with reference to the accompanying drawings, but the present invention is not limited thereto, and various changes can be made within the knowledge scope of technicians in the relevant technical field without departing from the purpose of the present invention.

Claims

1. A heat energy recovery device for an exhaust gas purification system, comprising a heat exchange box (1), wherein an air inlet pipe (4) and a liquid inlet pipe (2) are arranged on one side of the heat exchange box (1), and an air outlet pipe (5) and a liquid outlet pipe (3) are arranged on the other side; characterized in that: It also includes a heat recovery mechanism, wherein the air inlet end of the heat recovery mechanism is connected to the air inlet pipe (4), and the air outlet end of the heat recovery mechanism is connected to the air outlet pipe (5); The heat energy recovery mechanism comprises a heat exchange straight tube (6) and a plurality of heat exchange U-shaped tubes (9) arranged on the heat exchange straight tube (6); a control system is arranged on the heat exchange box (1); the control system is used to control the exhaust gas flow path; each time the exhaust gas flows through one more heat exchange U-shaped tube (9), the number of pipe bends on the heat exchange path increases by four; Temperature sensors are provided in the air inlet pipe (4), the air outlet pipe (5), the liquid inlet pipe (2) and the liquid outlet pipe (3); a flow rate sensor for detecting the flow rate of the liquid is provided in the heat exchange box (1); the control system is connected to the temperature sensor and the flow rate sensor for data transmission; A plurality of tees (7) are arranged on the heat exchange straight tube (6), and each two adjacent tees (7) form a pair, and both ends of the heat exchange U-shaped tube (9) are respectively connected to two tees (7) in a pair; A plurality of straight tube gate valves (8) are arranged on the heat exchange straight tube (6), the straight tube gate valve (8) is located between a pair of three-way valves (7), and the hand wheel of the straight tube gate valve (8) is removed; U-shaped tube gate valves (10) are arranged on the two vertical sections of the heat exchange U-shaped tube (9), the valve stems of the two U-shaped tube gate valves (10) are both in a horizontal state and are respectively located above the left and right sides of the straight tube gate valve (8), and the hand wheels of the two U-shaped tube gate valves (10) are removed; a control component is arranged on the heat exchange box (1), and the control component is used to control the opening and closing of the straight tube gate valve (8) and the U-shaped tube gate valve (10); The following parameters are defined: the inner diameter D of the exhaust gas flow pipe, the initial temperature T1 of the exhaust gas, the design temperature T2 of the exhaust gas after heat recovery, the actual flow length L of the exhaust gas flow pipe, the number of bending sections Z of the exhaust gas flow pipe in the liquid medium box, the flow speed S of the liquid medium in the box, the heat transfer coefficient h of the liquid medium, where the actual flow length L of the exhaust gas flow pipe = 2Z + 7; the number of bending sections , the calculation result is rounded up, the number of heat exchange U-tubes (9) put into use is calculated as Z / 4, and the calculation result is rounded up.

2. The heat recovery device of the exhaust gas purification system according to claim 1, characterized in that: The control component synchronously controls the straight pipe gate valve (8) and the U-shaped pipe gate valve (10), and when the straight pipe gate valve (8) is opened, the two U-shaped pipe gate valves (10) are closed, and the exhaust gas flows through the heat exchange straight pipe (6); when the straight pipe gate valve (8) is closed, the two U-shaped pipe gate valves (10) are opened, and the exhaust gas flows through the heat exchange U-shaped pipe (9); the control system is controlled and connected to each control component.

3. The heat recovery device of the exhaust gas purification system according to claim 1, characterized in that: The control assembly comprises an extension rod (11) resin-mounted on the top of a valve stem of a straight pipe gate valve (8), an intermediate bevel gear (13) and an extension rod gear (14) mounted on the extension rod (11), a bevel gear (12) mounted on the valve stems of two U-shaped pipe gate valves (10) and meshing with the intermediate bevel gear (13), a rotating shaft (15) vertically and rotatably mounted on the top of a heat exchange box (1), and a lower rotating shaft gear (21) mounted on the rotating shaft (15) and meshing with the extension rod gear (14); a power module for driving the rotating shaft (15) to rotate is mounted on the heat exchange box (1), and the control system is control-connected to the power module.

4. The heat recovery device of the exhaust gas purification system according to claim 3, characterized in that: The power module comprises a gear (22) on a rotating shaft arranged at the top of the rotating shaft (15), a rack (17) slidably arranged on the top outer wall of the heat exchange box (1), a fixed block (18) arranged on the back of the rack (17), a mounting block (19) arranged on the top outer wall of the heat exchange box (1), and a telescopic device (20) horizontally arranged on the mounting block (19), the telescopic end of the telescopic device (20) being connected to the fixed block (18), and the control system being control-connected to the telescopic device (20).

5. The heat recovery device of the exhaust gas purification system according to claim 1, characterized in that: A plurality of heat energy recovery mechanisms are arranged in parallel in the width direction of the heat exchange box (1); the ends of two adjacent straight heat exchange tubes (6) are connected via a U-shaped connecting tube (23); and the plurality of straight heat exchange tubes (6) and the U-shaped connecting tube (23) form a unidirectional exhaust gas flow route.

6. A heat energy recovery method for a heat energy recovery device of an exhaust gas purification system according to claim 1, characterized in that: The following steps are involved: S1. Calculate the number of bending sections using a formula according to different usage parameters, and then calculate the number of heat exchange U-shaped tubes (9) that need to be put into the path according to the number of bending sections; S2, the control system controls the opening and closing states of different straight pipe gate valves (8) and U-shaped pipe gate valves (10) to adjust the exhaust gas flow path and obtain the required exhaust gas flow path; S3. The exhaust gas enters the heat recovery mechanism through the air inlet pipe (4), circulates in the heat recovery mechanism, and is discharged through the air outlet pipe (5). The exhaust gas transfers heat to the flowing liquid in the heat exchange box (1), thereby completing the heat recovery of the exhaust gas.

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