Heat exchanger special for waste heat recovery of purified flue gas after desulfurization of absorption tower

Abstract

The utility model belongs to the technical field of heat exchangers, and particularly relates to a heat exchanger special for waste heat recovery of purified flue gas after desulfurization of an absorption tower. The structure of the heat exchanger comprises a perforated outer pipe unit of which the two ends are respectively used for connecting an air outlet pipe and a smoke pipe of an absorption tower, and a heat exchange inner pipe unit which is inserted into the perforated outer pipe unit and of which the length direction is parallel to that of the perforated outer pipe unit, the upper end and the lower end of the heat exchange-supporting dual-purpose plate body unit are arranged on the lower surface of the heat exchange inner pipe unit and the inner bottom surface of the perforated outer pipe unit respectively. The heat exchanger at least has the beneficial effects that the length direction of the heat exchange inner pipe unit is parallel to the length direction of the perforated outer pipe unit, so that the heat exchange inner pipe unit can provide a sufficient and effective heat exchange area, it is guaranteed that the heat recovery function is relatively efficient and thorough, and the heat exchanger is particularly suitable for clean flue gas with the relatively low temperature.

Description

Technical Field

[0001] This application belongs to the field of heat exchanger technology, and in particular relates to a heat exchanger specifically used for waste heat recovery of the clean flue gas after desulfurization in an absorption tower. Background Technology

[0002] Wet desulfurization towers, also known as the absorption towers mentioned above, are commonly used in coal-fired power plants and steel mills. The main functions of these absorption towers are: reducing SO2 emissions, removing harmful gases from flue gas, and recovering and reusing desulfurization byproducts (such as gypsum).

[0003] Correspondingly, the working principle of the absorption tower is as follows: sulfur-containing flue gas generated by boilers or other combustion equipment passes through the spray zone, oxidation zone, solid-liquid separation zone, and clean flue gas demisting zone in sequence to achieve the above-mentioned functions, while the clean flue gas meets the emission standards.

[0004] Generally, the waste heat recovery step, which is paired with this absorption tower, can be installed on both the sulfur-containing flue gas pipeline before desulfurization and the clean flue gas pipeline after desulfurization. The advantage of the former waste heat recovery step is mainly the high flue gas temperature, generally above 120℃, resulting in high heat recovery value. The main disadvantage is that it is significantly limited by the site. When setting it up in a plant area, it is generally difficult to leave a large space for pipeline installation between the boiler and the absorption tower, which makes it difficult to install various heat exchangers, especially large heat exchangers.

[0005] The latter's waste heat recovery step after desulfurization has the exact opposite advantages and disadvantages to the former. Meanwhile, the temperature of the clean flue gas is still around 50℃, which still has some heat recovery value for the boiler feedwater temperature of around 20℃ and the city heating return water temperature of around 30℃.

[0006] Therefore, there is already a type of heat exchanger specifically designed for waste heat recovery in clean flue gas pipelines. For example, Chinese utility model patent with authorization announcement number CN220472409U and authorization announcement date of February 9, 2024 discloses a waste heat recovery device for the tail flue after desulfurization, whose main structural components include: an outer tube, an inner tube, spiral fins, and a blower.

[0007] The main advantage of the waste heat recovery device after desulfurization in this utility model patent is that it is basically effective in recovering heat from white smoke (i.e., the clean flue gas mentioned above).

[0008] However, when this desulfurization waste heat recovery device is in normal use, it still has at least the following impractical problems, specifically:

[0009] Its inner and outer combined pipe structure is perpendicular to the length of the white smoke pipe, therefore even if it is attached Figure 1 , 2As shown, setting up the above-mentioned three combined inner and outer pipe structures at a certain point in the white smoke pipeline also has the problems of relatively low heat exchange efficiency and poor practicality. The reason for this is that the temperature of the white smoke (i.e. the above-mentioned clean flue gas) itself is relatively low. Utility Model Content

[0010] This application provides a heat exchanger specifically for waste heat recovery of clean flue gas after desulfurization in an absorption tower. The technical problem it aims to solve is: how to make the heat exchanger more practical and efficient in recovering heat from the clean flue gas.

[0011] The technical solution adopted by this application to solve the above problems is: a heat exchanger for waste heat recovery of clean flue gas after desulfurization in an absorption tower. The structure includes a perforated outer tube unit with both ends for connecting the gas outlet pipe and the dust pipe of the absorption tower, a heat exchange inner tube unit inserted into the perforated outer tube unit and parallel to the length direction of the perforated outer tube unit, and a heat exchange-support dual-purpose plate unit with its upper and lower ends respectively set on the lower surface of the heat exchange inner tube unit and the inner bottom surface of the perforated outer tube unit.

[0012] A further preferred technical solution is that it also includes an auxiliary heat exchange plate unit disposed on the upper surface of the heat exchange inner tube unit.

[0013] A further preferred technical solution is that the perforated outer tube unit includes an outer tube with two ends for connecting the gas outlet pipe and the dust pipe of the absorption tower, respectively, and two insertion holes respectively set at both ends of the outer tube for installing the heat exchange inner tube unit.

[0014] A further preferred technical solution is that the heat exchange inner tube unit includes a heat exchange inner tube disposed inside the outer tube and whose length direction is parallel to the length direction of the outer tube, an end connecting pipe disposed on all the heat exchange inner tubes, and an inlet / outlet pipe disposed on the end connecting pipe and passing through the insertion hole.

[0015] A further preferred technical solution is that the heat exchange-support dual-purpose plate unit includes a horizontal plate disposed on the lower surface of all the heat exchange inner tubes, and a heat exchange vertical plate disposed on the lower surface of the horizontal plate and used for support on the inner bottom surface of the outer tube.

[0016] A further preferred technical solution is that the auxiliary heat exchange plate unit includes a rectangular heat exchange plate body, and two vertical baffles disposed on the upper surface of the heat exchange inner tube unit and located on both sides of the rectangular heat exchange plate body, and used for vertically installing the rectangular heat exchange plate body.

[0017] A further preferred technical solution is that the perforated outer tube unit further includes a heat insulation sleeve sleeved on the outer tube and located between the two insertion holes, and two T-shaped mounting plates disposed on the outer tube and respectively located on both sides of the heat insulation sleeve.

[0018] A further preferred technical solution is that the heat exchange inner tube unit further includes an L-shaped locking plate disposed on the lower surface of the heat exchange inner tube and used for mounting the horizontal plate.

[0019] A further preferred technical solution is that the heat exchange-support dual-purpose plate unit further includes a heat-insulating elastic sheet disposed on the lower surface of the heat exchange vertical plate and used to press the horizontal plate onto the lower surface of the heat exchange inner tube.

[0020] A further preferred technical solution is that the perforated outer tube unit further includes a positioning plate disposed on the inner bottom surface of the outer tube and used to laterally engage the heat-insulating elastic sheet.

[0021] The beneficial effects of this application include at least the following three points.

[0022] First, the length of the inner heat exchange tube unit is parallel to the length of the perforated outer tube unit, which allows the former to provide a sufficient and effective heat exchange area, ensuring that the heat recovery function is relatively more efficient and thorough, making this heat exchanger particularly suitable for clean flue gas with relatively low temperature.

[0023] Secondly, the heat exchange inner tube unit has the dual advantages of being stable during installation and having moderate difficulty in disassembly and assembly compared to the perforated outer tube unit.

[0024] Third, the heat exchange-support dual-purpose plate unit and auxiliary heat exchange plate unit can further improve the heat recovery efficiency of the heat exchange inner tube unit. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the structure of this application.

[0026] Figure 2 This is a schematic diagram illustrating how this application is used.

[0027] Figure 3 This is a schematic diagram of the heat exchanger inner tube unit in this application.

[0028] Figure 4 This is a schematic diagram of the location and structure of the heat exchange-support dual-purpose plate unit in this application.

[0029] Figure 5 This is a schematic diagram showing the location and shape of the thermal insulation elastic sheet in this application.

[0030] Figure 6 This is a schematic diagram illustrating the usage of the auxiliary heat exchange plate unit in this application.

[0031] Figure 7 This is a schematic diagram of the unused auxiliary heat exchange plate unit in this application.

[0032] Figure 8 This is a schematic diagram showing the position and shape of the T-shaped mounting plate in this application.

[0033] The meanings of the markings in the diagram are as follows.

[0034] Absorption tower outlet pipe a, flue pipe b, connector c;

[0035] Perforated outer tube unit 1, heat exchange inner tube unit 2, heat exchange-support dual-purpose plate unit 3, auxiliary heat exchange plate unit 4;

[0036] Outer pipe 101, heat insulation sleeve 103, T-shaped mounting plate 104, positioning plate 105;

[0037] Heat exchanger inner tube 201, end connecting pipe 202, inlet and outlet pipes 203, L-shaped clamping plate 204, plug 205;

[0038] Horizontal plate 301, vertical plate for heat exchange 302, heat insulation elastic sheet 303, vent hole 304;

[0039] Rectangular heat exchange plate 401, vertical baffle 402, limiting plate 403. Detailed Implementation

[0040] The following description is merely a preferred embodiment of this application and is not intended to limit the scope of this application.

[0041] like Figures 1-8 As shown, a heat exchanger for waste heat recovery of clean flue gas after desulfurization in an absorption tower has the following structure: a perforated outer tube unit 1 with both ends for connecting the gas outlet pipe a and the flue gas pipe b of the absorption tower respectively; a heat exchange inner tube unit 2 inserted into the perforated outer tube unit 1 and parallel to the length direction of the perforated outer tube unit 1; and a heat exchange-support dual-purpose plate unit 3 with its upper and lower ends respectively disposed on the lower surface of the heat exchange inner tube unit 2 and the inner bottom surface of the perforated outer tube unit 1.

[0042] In this embodiment, the heat exchanger is generally tubular in shape, and its main body is made of stainless steel or plastic. The reasons why it can be "specifically used for the clean flue gas after desulfurization in the absorption tower" mainly include the following three points:

[0043] First, the length direction of the heat exchange inner tube unit 2 is parallel to the length direction of the perforated outer tube unit 1, that is, parallel to the flow direction of the clean flue gas. At this time, there is enough time for the clean flue gas and the heat exchange inner tube unit 2 to transfer heat, making the heat exchange operation more thorough. This is very necessary and effective for the clean flue gas with a relatively low temperature.

[0044] Second, the length of the heat exchange inner tube unit 2 is set to be at least 80% of the length of the perforated outer tube unit 1, and the former has a common main pipe and branch pipe combination structure. The number of branch pipes is set to be at least 3, which are the main implementation parts of the heat exchange operation, further improving the efficiency of the heat exchange operation.

[0045] Third, one of the functions of the heat exchange-support dual-purpose plate unit 3 is to increase the effective heat exchange area of ​​the heat exchange inner tube unit 2, which also improves the efficiency of heat exchange operation.

[0046] For specific instructions on the installation and use of this heat exchanger, please refer to the attached document. Figure 2 The connector c is a commercially available product, and its main function is to provide effective connection and a thorough seal. Correspondingly, this heat exchanger, along with the absorber tower outlet pipe a and flue gas pipe b, can differ in cross-sectional shape and size, but none of these differences affect the final effect of effective connection and thorough sealing.

[0047] Furthermore, the perforated outer tube unit 1 can be fixed to the factory wall or supported on the ground by a mounting frame. The heat exchange inner tube unit 2 is used in conjunction with a fan or water pump, allowing the clean flue gas to be heated by either cold air or cold water.

[0048] Finally, the second function of the heat exchange-support dual-purpose plate unit 3 is to vertically fix the heat exchange inner tube unit 2 on the perforated outer tube unit 1, preventing the latter from falling on the inner bottom surface of the former. Otherwise, the adverse effects mainly include the following two:

[0049] First, the heat exchange inner tube unit 2 is located relatively low, which prevents it from fully contacting the clean flue gas, thus greatly reducing the heat exchange efficiency.

[0050] Secondly, if the aforementioned falling phenomenon occurs during use, the heat exchange inner tube unit 2 itself will be stretched significantly, which may easily lead to harmful problems such as disconnection at its interface.

[0051] The structure of the heat exchanger also includes an auxiliary heat exchange plate unit 4 disposed on the upper surface of the inner heat exchange tube unit 2.

[0052] In this embodiment, the main function of the auxiliary heat exchange plate unit 4 is to increase the effective heat exchange area of ​​the heat exchange inner tube unit 2.

[0053] However, it should be noted that the use of the heat exchange inner tube unit 2 and the auxiliary heat exchange plate unit 4 will significantly reduce the flow rate of the clean flue gas in the perforated outer tube unit 1. Therefore, when the former two absorb heat from the clean flue gas, they also need to control and adjust their own degree of obstruction to the clean flue gas to avoid the heat exchange operation significantly affecting the normal exhaust effect of the entire desulfurization process.

[0054] Therefore, the auxiliary heat exchange function of the auxiliary heat exchange plate unit 4 is set to be switchable. The auxiliary heat exchange function of each of the auxiliary heat exchange plate units 4 can be turned on or off independently. When it is turned on, the blocking and deceleration effect on the clean flue gas is relatively obvious. Conversely, when it is turned off, the blocking and deceleration effect is relatively insignificant.

[0055] The perforated outer tube unit 1 includes an outer tube 101 with two ends for connecting the gas outlet pipe a and the dust pipe b of the absorption tower, and two insertion holes respectively set at both ends of the outer tube 101 for installing the heat exchange inner tube unit 2.

[0056] In this embodiment, the outer tube 101 can be either a round or rectangular tube, and the material is a variety of common low thermal conductivity materials. The insertion hole is located relatively close to the side on the outer tube 101, thereby leaving a relatively large effective installation area length for the heat exchange inner tube unit 2.

[0057] Furthermore, the opening of the socket can be oriented upwards, downwards, or to the side.

[0058] The heat exchange inner tube unit 2 includes a heat exchange inner tube 201 disposed inside the outer tube 101 and parallel to the length direction of the outer tube 101, an end connecting pipe 202 disposed on all the heat exchange inner tubes 201, and an inlet / outlet pipe 203 disposed on the end connecting pipe 202 and passing through the insertion hole.

[0059] In this embodiment, the inner heat exchange tube 201 is the main heat exchange location of the heat exchanger. It is made of a metal with relatively high thermal conductivity, and there are at least 3 tubes. They can be rectangular or round tubes and are parallel to the outer tube 101.

[0060] In addition, the end connecting pipe 202 can also be used for heat exchange. However, the inlet and outlet pipe 203 is not suitable for heat exchange, as most of its length is located outside the outer pipe 101, and its material can be set to be the same as that of the outer pipe 101.

[0061] Finally, the heat exchange inner tube 201 and the end connecting tube 202 are integrally formed, and the end connecting tube 202 is inserted into the inlet and outlet tubes 203. The inlet and outlet tubes 203 and the end connecting tube 202, as well as the inlet and outlet tubes 203 and the insertion hole, need to be fully sealed. The former is to prevent leakage of the air or water to be heated, and the latter is to prevent leakage of clean flue gas.

[0062] Correspondingly, the connection between the end connecting pipe 202 and the inlet / outlet pipe 203 can greatly simplify the disassembly and assembly of the heat exchange inner tube unit 2 and the entire heat exchanger.

[0063] The heat exchange-support dual-purpose plate unit 3 includes a horizontal plate 301 disposed on the lower surface of all the heat exchange inner tubes 201, and a heat exchange vertical plate 302 disposed on the lower surface of the horizontal plate 301 and used for support on the inner bottom surface of the outer tube 101.

[0064] In this embodiment, the horizontal plate 301 fully contacts the lower surfaces of all the heat exchange inner tubes 201. When the heat exchange inner tube 201 is a rectangular tube, its lower surface can fully and appropriately press against the upper surface of the horizontal plate 301; when the heat exchange inner tube 201 is a circular tube, an arc-shaped straight groove for fitting the heat exchange inner tube 201 is formed on the upper surface of the horizontal plate 301.

[0065] The heat exchange vertical plate 302 is perpendicular to the flow direction of the clean flue gas, while the horizontal plate 301 is parallel to the flow direction of the clean flue gas. Therefore, the main body of the "heat exchange" function of the heat exchange-support dual-purpose plate unit 3 is the heat exchange vertical plate 302, because its degree of obstruction to the clean flue gas is higher than that of the horizontal plate 301, and the residence and contact time of the clean flue gas on the heat exchange vertical plate 302 is longer than that on the horizontal plate 301.

[0066] Finally, the heat exchange-support dual-purpose plate unit 3 is generally T-shaped, and there are 3-20 of them. It is used to fully support the heat exchange inner tube unit 2, thereby reducing the stress on the entire heat exchange inner tube unit 2 suspended at the inlet and outlet pipes 203.

[0067] The auxiliary heat exchange plate unit 4 includes a rectangular heat exchange plate body 401 and two vertical baffles 402 disposed on the upper surface of the heat exchange inner tube unit 2, respectively located on both sides of the rectangular heat exchange plate body 401, and used for vertically installing the rectangular heat exchange plate body 401.

[0068] In this embodiment, the function and principle of the rectangular heat exchange plate 401 are the same as those of the heat exchange vertical plate 302; both can be considered as heat exchange fins of the inner heat exchange tube 201. Accordingly, when the rectangular heat exchange plate 401 is installed vertically, it is perpendicular to the flow direction of the clean flue gas.

[0069] At this time, the two vertical baffles 402 in pairs are used to maintain the vertical state of the rectangular heat exchange plate 401, so that the latter can fully block and contact the clean flue gas, ensuring that the latter has a relatively long heat exchange time.

[0070] The rectangular heat exchange plate 401 and the vertical baffle 402 are both made of high thermal conductivity metal. The second function of the latter is to provide auxiliary heat conduction between the rectangular heat exchange plate 401 and the heat exchange inner tube 201.

[0071] When the rectangular heat exchange plate 401 is removed between the two vertical baffles 402 and placed flat on the inner heat exchange tube 201, the auxiliary heat exchange plate unit 4 has its auxiliary heat exchange function turned off. At this time, the rectangular heat exchange plate 401 is parallel to the flow direction of the clean flue gas, and the vertical baffles 402 themselves are relatively small in size. The additional heat conduction between the clean flue gas and the inner heat exchange tube 201 by these two is relatively small, which can be regarded as the auxiliary heat exchange function being turned off.

[0072] On the other hand, when the exhaust velocity of the desulfurization process has become significantly low enough to affect the normal desulfurization effect, it is necessary to actively remove and flatten the rectangular heat exchange plate 401, or even remove and flatten part of the heat exchange-support dual-purpose plate unit 3. The auxiliary and additional heat exchange functions of the heat exchange-support dual-purpose plate unit 3 and the auxiliary heat exchange plate unit 4 have a lower priority than the most basic desulfurization effect.

[0073] The perforated outer tube unit 1 further includes a heat insulation sleeve 103 sleeved on the outer tube 101 and located between the two insertion holes, and two T-shaped mounting plates 104 disposed on the outer tube 101 and located on both sides of the heat insulation sleeve 103.

[0074] In this embodiment, the heat insulation sleeve 103 is made of commonly available rubber. It is fitted and fixed to the outer surface of the outer tube 101 by its own elasticity, without affecting the normal use of the T-shaped mounting plate 104 and the inlet / outlet pipe 203.

[0075] The T-shaped mounting plate 104 is provided with bolt mounting holes, which can be installed on the inner ceiling and vertical wall of the factory building.

[0076] The heat exchange inner tube unit 2 also includes an L-shaped locking plate 204 disposed on the lower surface of the heat exchange inner tube 201 and used to install the horizontal plate 301.

[0077] In this embodiment, the main function of the L-shaped locking plate 204 is to fully fit the upper surface of the horizontal plate 301 and the lower surface of the heat exchange inner tube 201, so that the heat absorbed by the heat exchange-support dual-purpose plate unit 3 can be quickly and to a large extent transferred to the heat exchange inner tube 201.

[0078] Accordingly, the length direction of the L-shaped locking plate 204 can be parallel to or perpendicular to the length direction of the heat exchange inner tube 201, ensuring that the heat exchange-support dual-purpose plate unit 3 can be plugged in and removed from the pair of L-shaped locking plates 204 as needed.

[0079] The heat exchange-support dual-purpose plate unit 3 also includes a heat-insulating elastic sheet 303 disposed on the lower surface of the heat exchange vertical plate 302 and used to press the horizontal plate 301 onto the lower surface of the heat exchange inner tube 201.

[0080] In this embodiment, the heat-insulating elastic sheet 303 is made of ordinary rubber, and its function includes at least:

[0081] First, the heat exchange inner tube 201 and the horizontal plate 301 are vertically clamped, so that the two can transfer heat more efficiently;

[0082] Second, thermal insulation is provided between the heat exchange vertical plate 302 and the outer tube 101 to prevent the heat received on the heat exchange vertical plate 302 from being transferred in large quantities to the outer tube 101 and the outside air, thereby improving the effective heat exchange efficiency of the heat exchange-support dual-purpose plate unit 3.

[0083] The perforated outer tube unit 1 also includes a positioning plate 105 disposed on the inner bottom surface of the outer tube 101 and used to laterally engage the heat insulation elastic sheet 303.

[0084] In this embodiment, the positioning plates 105 are arranged in pairs on the inner bottom surface of the outer tube 101, which laterally clamp the heat insulation elastic sheet 303, thereby reinforcing the vertical working state of the heat exchange-support dual-purpose plate unit 3 and preventing it from tipping over.

[0085] Correspondingly, this is also the third function of the heat-insulating elastic sheet 303.

[0086] Furthermore, both ends of the end connecting pipe 202 are provided with plugs 205. Different numbers and sizes of vent holes 304 can be provided on both the heat exchange vertical plate 302 and the rectangular heat exchange plate 401 as needed, so that a more suitable balance can be achieved between the two effects of heat exchange and blocking clean flue gas.

[0087] The embodiments of this application have been described in detail above with reference to the accompanying drawings. However, this application is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various modifications can be made without departing from the spirit of this application. These are non-inventive modifications and are protected by patent law as long as they are within the scope of the claims of this application.

Claims

1. A heat exchanger specially used for waste heat recovery of clean flue gas after desulphurization in an absorption tower, characterized in that: The structure comprises a perforated outer pipe unit (1) for connecting the gas outlet pipe (a) and the smoke pipe (b) respectively, a heat exchange inner pipe unit (2) which is inserted on the perforated outer pipe unit (1) and has the length direction parallel to the length direction of the perforated outer pipe unit (1), and a heat exchange-support dual-purpose plate unit (3) which is arranged on the lower surface of the heat exchange inner pipe unit (2) and the inner bottom surface of the perforated outer pipe unit (1) respectively.

2. A heat exchanger specially used for the absorption tower desulfurization of the flue gas after the waste heat recovery, according to claim 1, characterized in that: It also comprises an auxiliary heat exchange plate unit (4) arranged on the upper surface of the heat exchange inner pipe unit (2).

3. A heat exchanger specially adapted for use in waste heat recovery of clean flue gas after absorption tower desulphurization according to claim 1, characterized in that: The perforated outer pipe unit (1) comprises an outer pipe (101) for connecting the gas outlet pipe (a) and the smoke pipe (b) respectively, and two insertion holes arranged on the outer pipe (101) at the two end positions and used for installing the heat exchange inner pipe unit (2).

4. A heat exchanger specially used for the absorption tower desulfurization of the flue gas after the waste heat recovery, according to claim 3, characterized in that: The heat exchange inner pipe unit (2) comprises a heat exchange inner pipe (201) arranged in the outer pipe (101) and having the length direction parallel to the length direction of the outer pipe (101), a head communication pipe (202) arranged on all the heat exchange inner pipes (201), and an inlet and outlet pipe (203) arranged on the head communication pipe (202) and passing through the insertion hole.

5. A heat exchanger specially adapted for use in waste heat recovery of clean flue gas after absorption tower desulphurization according to claim 4, characterized in that: The heat exchange-support dual-purpose plate unit (3) comprises a horizontal plate (301) arranged on the lower surface of all the heat exchange inner pipes (201), and a heat exchange vertical plate (302) arranged on the lower surface of the horizontal plate (301) and used for supporting on the inner bottom surface of the outer pipe (101).

6. A heat exchanger exclusively for the flue gas desulphurization (FGD) unit as claimed in claim 2, wherein: The auxiliary heat exchange plate unit (4) comprises a rectangular heat exchange plate body (401), and two vertical baffles (402) arranged on the upper surface of the heat exchange inner pipe unit (2) and located at the two side positions of the rectangular heat exchange plate body (401) respectively and used for vertically installing the rectangular heat exchange plate body (401).

7. A heat exchanger as claimed in claim 3, wherein the heat exchanger is specially designed for recovering heat from the flue gas after desulphurization in an absorption tower. The perforated outer pipe unit (1) further comprises a heat insulation sleeve (103) which is sleeved on the outer pipe (101) and located between the two insertion holes, and two T-shaped mounting plates (104) which are arranged on the outer pipe (101) and located at the two side positions of the heat insulation sleeve (103) respectively.

8. A heat exchanger specially adapted for use in waste heat recovery of clean flue gas after absorption tower desulphurization according to claim 5, characterized in that: The heat exchange inner pipe unit (2) further comprises an L-shaped clamping plate (204) arranged on the lower surface of the heat exchange inner pipe (201) and used for installing the horizontal plate (301).

9. A heat exchanger exclusively for use in waste heat recovery of clean flue gas after absorption tower desulphurization according to claim 5, characterized in that: The heat exchange-support dual-purpose plate unit (3) further comprises a heat insulation elastic sheet (303) arranged on the lower surface of the heat exchange vertical plate (302) and used for pressing the horizontal plate (301) on the lower surface of the heat exchange inner pipe (201).

10. A heat exchanger exclusively for the flue gas desulphurization (FGD) unit as claimed in claim 9, wherein: The perforated outer pipe unit (1) further comprises a positioning plate (105) arranged on the inner bottom surface of the outer pipe (101) and used for transversely clamping the heat insulation elastic sheet (303).

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