Anti-corrosion heat exchanger for waste heat recovery

Abstract

The utility model provides a kind of anticorrosion heat exchanger for waste heat recovery belongs to heat exchanger technical field.Its structure includes: heat exchange module is fixedly connected with bolt and nut on support frame, flue gas inlet and flue gas outlet are respectively arranged on the upside and downside of heat exchange module, and graphite packing is arranged on heat exchange module;Graphite pipe is integrally formed by extrusion from thermosetting high molecular phenolic resin and graphite;Circulating water flows through in graphite pipe, and flue gas flows through outside graphite pipe;Tube sheet of heat exchange module is sealed by O-shaped sealing ring, and the O-shaped sealing ring is arranged in sealing groove.The utility model not only improves the heat exchange capacity of heat exchanger, but also improves its pressure-bearing capacity and corrosion resistance, so that the heat exchanger has wider application field and can better meet the use requirements under various corrosion conditions.In addition, the utility model greatly reduces the maintenance cost of heat exchanger in use process through the improvement of mounting structure and sealing structure, and has significant technical advantages.

Description

Technical Field

[0001] This utility model relates to the field of heat exchanger technology, specifically to a corrosion-resistant heat exchanger for waste heat recovery. Background Technology

[0002] Currently, most corrosion-resistant heat exchangers for waste heat recovery on the market use enamel-lined tubes. Enamel coating is a glass or ceramic coating that protects the metal substrate, preventing corrosion and oxidation, and also provides insulation. Due to its superior corrosion resistance, high hardness, strong oxidation resistance, and low price, it is widely used in air preheaters. However, despite its good corrosion resistance, enamel-lined tubes can still fail.

[0003] Large-diameter bubbles reduce the effective thickness of the coating. The sharp corners of the bubbles are stress concentration points, which are the root cause of cracks. Under the action of temperature and stress, the cracks propagate, causing the coating to crack and peel off.

[0004] The high temperature during welding can damage the coating, and the uneven distribution of elements at the weld makes it difficult to form a dense coating. Corrosive media can easily corrode the metal substrate through areas with insufficient thickness.

[0005] Enamel coating and metal substrate are two materials with significantly different physical properties, and their coefficients of thermal expansion differ greatly. Under the action of thermal deformation of the metal substrate, cracking is easily triggered.

[0006] The uneven thickness of the enamel-lined pipe leads to preferential corrosion in thinner areas and regions where alkali metals accumulate in the coating. Alkali metals readily react with HCl and dissolve in the solution, leaving behind porous SiO2 in the enamel coating, ultimately causing coating failure. Summary of the Invention

[0007] This utility model aims to address the technical deficiencies of existing technologies by providing a corrosion-resistant heat exchanger for waste heat recovery, thereby solving the technical problems that conventional corrosion-resistant heat exchangers for waste heat recovery need to improve in terms of corrosion resistance and heat exchange performance.

[0008] Another technical problem that this invention aims to solve is: how to improve the overall performance of corrosion-resistant heat exchangers for waste heat recovery, reduce the damage rate, and extend their service life.

[0009] To achieve the above technical objectives, the present invention adopts the following technical solution:

[0010] A corrosion-resistant heat exchanger for waste heat recovery includes a support frame, a flue gas inlet, a heat exchange module, a flue gas outlet, bolts, nuts, and graphite packing. The heat exchange module is fixedly connected to the support frame by bolts and nuts. A flue gas inlet and a flue gas outlet are respectively provided on the upper and lower sides of the heat exchange module. Graphite packing is provided on the heat exchange module.

[0011] Preferably, the graphite tube is integrally formed by extrusion of thermosetting polymer phenolic resin and graphite; circulating water flows inside the graphite tube, and flue gas flows outside the graphite tube.

[0012] Preferably, the tube sheet of the heat exchange module is sealed with an O-ring, which is disposed in a sealing groove.

[0013] Preferably, a cold-side inlet and a cold-side outlet are provided at both ends of the tube side of the heat exchange module, and a hot-side inlet and a hot-side outlet are provided at both ends of the shell side of the heat exchange module.

[0014] Preferably, the heat exchange module is provided with a tube box exhaust port and a tube box liquid drain port on the upper and lower sides respectively.

[0015] As a preferred option, a drain outlet and a manhole are provided on the pipe where the flue gas outlet is located.

[0016] As a preferred option, a pressure measuring port, a temperature measuring port, a manhole, and a flushing port are provided on the pipe where the flue gas inlet is located.

[0017] In the above technical solution, thermosetting phenolic resin and graphite are integrally formed into a high-molecular graphite tube by extrusion. The graphite tube serves as the main heat exchange element, with circulating water flowing inside the tube and low-temperature flue gas flowing outside. Through heat exchange in the graphite tube, the heat in the flue gas is transferred to the circulating water side for reuse.

[0018] The combination of phenolic resin and graphite endows the product with excellent corrosion resistance. Under the erosion of various acids, salts, chloride ions, and other chemicals, the pressed phenolic resin graphite tube remains stable, greatly satisfying the heat exchange requirements of hydrochloric acid, phosphoric acid, and sulfuric acid working media, while also meeting the high-intensity dew point corrosion conditions of various sulfur-containing and chlorine-containing flue gases.

[0019] Graphite itself has excellent thermal conductivity, which can easily achieve heat exchange with low temperature difference. It can meet the needs of deep heat exchange in important occasions such as waste heat recovery and gas condensation, and greatly improve energy utilization efficiency.

[0020] The heat exchanger adopts a top-inlet and bottom-outlet arrangement for flue gas. After the flue gas condenses, the condensate directly enters the bottom flue and is discharged through the condensate outlet, preventing water accumulation inside the heat exchanger and reducing the risk of heat exchanger corrosion.

[0021] O-rings are used for sealing. O-rings made of various types of rubber can meet almost all anti-corrosion requirements in industry. By utilizing the compressibility of the O-ring, the O-ring is installed in the sealing groove of the tube sheet. Then, the graphite tube is beveled and directly inserted. By designing a suitable compression amount for the O-ring, a sealing method that can withstand a maximum water pressure of 1.6MPa can be achieved.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] Given the limitations of traditional metal or non-metal flue gas heat exchangers in terms of performance and the need for optimized manufacturing processes, this invention utilizes phenolic resin graphite tubes to effectively improve the heat exchanger's heat transfer capacity. The specific raw materials combined with a rubber O-ring sealing method achieve a good balance between pressure resistance and corrosion resistance in the phenolic resin graphite tube flue gas heat exchanger, effectively enhancing its heat transfer and corrosion resistance. The resulting heat exchanger has a wider range of applications and can better meet the requirements of various corrosive conditions.

[0024] The modular installation structure and the use of cover plates at the pipe box allow for individual module cutting out for maintenance. Moreover, thanks to the O-ring seal, heat exchange tubes can be directly replaced on-site or plugs can be used to seal them, greatly reducing the maintenance costs of the flue water heat exchanger during use. Attached Figure Description

[0025] Figure 1 This is the front view of this utility model;

[0026] Figure 2 This is a side view of the present invention;

[0027] Figure 3 This is a top view of the present invention;

[0028] Figure 4 This is a partial view of the location of the sealing groove in this utility model;

[0029] In the picture:

[0030] 1. Support frame; 2. Flue gas inlet; 3. Heat exchange module; 4. Flue gas outlet; 5. Bolts; 6. Nuts; 7. Graphite packing.

[0031] L1~2, ​​drain outlet of the tubing box; A1~2, vent outlet of the tubing box; P1, pressure measuring port; T1, temperature measuring port; M1~2, manhole; F1, drain outlet; G1~2, flushing port; N1, hot side inlet; N2, hot side outlet; N3, cold side inlet; N4, cold side outlet. Detailed Implementation

[0032] The specific embodiments of this utility model will be described in detail below. To avoid excessive and unnecessary details, well-known structures or functions will not be described in detail in the following embodiments. The approximate language used in the following embodiments can be used for quantitative descriptions, indicating that a certain degree of variation in quantity is permissible without changing the basic function. Unless otherwise defined, the technical and scientific terms used in the following embodiments have the same meaning as commonly understood by those skilled in the art to which this utility model pertains.

[0033] A corrosion-resistant heat exchanger for waste heat recovery, such as Figures 1-4 As shown, the system includes a support frame 1, a flue gas inlet 2, a heat exchange module 3, a flue gas outlet 4, bolts 5, nuts 6, and graphite packing 7. The heat exchange module 3 is fixedly connected to the support frame 1 via bolts 5 and nuts 6. The heat exchange module 3 has a flue gas inlet 2 and a flue gas outlet 4 on its upper and lower sides, respectively. The heat exchange module 3 is equipped with graphite packing 7. The graphite tubes are integrally formed by extrusion of thermosetting phenolic resin and graphite. Circulating water flows inside the graphite tubes, while flue gas flows outside. The tube sheet of the heat exchange module 3 is sealed with O-rings, which are positioned within sealing grooves. The heat exchange module 3 has a cold-side inlet and a cold-side outlet at both ends of the tube side, and a hot-side inlet and a hot-side outlet at both ends of the shell side. The heat exchange module 3 has a tube box exhaust port and a tube box drain port on its upper and lower sides, respectively. A drain outlet and a manhole are provided on the pipe where the flue gas outlet 4 is located. The pipe at flue gas inlet 2 is equipped with a pressure measuring port, a temperature measuring port, a manhole, and a flushing port.

[0034] The engineering process is as follows:

[0035] The components consist of phenolic resin graphite tubes, water-side tube boxes, steel structural frames, flue gas-side reducers, and heat exchange tube support plates.

[0036] (1) Prepare and cut materials according to the design drawings and actual conditions.

[0037] (2) Non-destructive testing: The pipe box and the pipe box cover plate are riveted and welded, and the weld of the pipe box and the cover plate is subjected to non-destructive testing. If necessary, heat treatment is carried out, and machining is carried out after the inspection is completed.

[0038] (3) Machining the sealing groove of the tube box and tube sheet. According to the tolerance range of the drawing, the sealing groove is machined. When designing the size of the sealing groove, the compression of the sealing ring should be within 15%~25%. After machining the sealing groove, blow away the oil, iron filings and other impurities in the sealing groove. Then, machine the sealing surface of the tube box and cover plate.

[0039] (4) The carbon steel frame and flue gas side diameter changer of the equipment shall be riveted and welded according to the drawings. The limit deviation of the linear dimensions of the machined and non-machined surfaces shall comply with the requirements of the drawings and the m and c grades in GB / T1804-2000.

[0040] (5) The pipe box and the frame are assembled and welded. During assembly, a positioning pipe should be placed to ensure that the control of the two pipe boxes is aligned. The positioning pipe can be removed only after the welding is completed.

[0041] (6) Apply anti-corrosion coating or glass flake anti-corrosion coating to the steel structure components on the flue gas side, especially the back of the tube sheet. The anti-corrosion thickness should meet the requirements of the drawings.

[0042] (7) After the flue gas side steel structure is protected against corrosion, the tube sheet sealing groove is cleaned a second time to remove the anti-corrosion coating and rust and iron filings in the sealing groove.

[0043] (8) Install heat exchange tube support plates. The support plates are selected from high temperature resistant non-metallic support plates, generally thermosetting resin support plates. The connection between the support plates and the steel structure frame is made of angle steel or channel steel coated with anti-corrosion paint and then fixed with corrosion-resistant metal bolts such as 2205.

[0044] (9) Install the sealing ring and heat exchange tube. First, install the sealing ring in the sealing groove of one side of the tube sheet. Then, insert the heat exchange tube from the other end and pass it out of the tube sheet on the side of the sealing ring by 100~200mm. After installing the sealing ring on the other side of the tube sheet, insert the heat exchange tube back from the other end to achieve the sealing of the heat exchange tube.

[0045] (10) Water pressure test: After the heat exchange tubes are installed, install the water side cover of the heat exchanger. The cover and the tube box sealing surface adopt the concave-convex groove seal. The sealing gasket is made of rubber. After installation, the tube bundle module is subjected to an overall water pressure test to find leaks. If there is a leak, mark the leaking pipe opening and depressurize before repairing the leak. If the sealing groove size is not up to standard, replace it with a sealing ring with a larger wire diameter. If there are impurities in the sealing groove, clean it and reinstall the heat exchange tubes.

[0046] (11) Painted before shipment: After passing the water pressure test, the heat exchanger is painted before shipment.

[0047] (12) On-site modular assembly.

[0048] This heat exchanger is composed of a high-molecular-weight graphite tube, frame, and water tank, integrally formed by extrusion of thermosetting phenolic resin and graphite. It exhibits excellent corrosion resistance and high-efficiency heat transfer performance against condensate in acidic flue gas, making it suitable for low-temperature waste heat recovery applications. During manufacturing, phenolic resin graphite tubes are used as the heat exchange components, and O-rings are used for sealing, effectively improving the pressure resistance of the heat exchanger by ensuring a tight seal between the steel tube sheet and the phenolic resin graphite tubes. Corrosion protection is applied to the flue gas side according to the flue gas temperature, such as PTFE lining and glass flake corrosion protection. The heat exchange tubes are supported by high-temperature resistant SMC insulation boards, and the heat exchanger is divided into small heat exchange modules to prevent resonance caused by Karman vortex streets in the tube bundle. This equipment effectively reduces costs while improving the heat exchanger's corrosion resistance to low-temperature flue gas condensate, better meeting the needs of complex waste heat recovery applications.

[0049] This equipment is actually used in the waste heat recovery system of Zibo Gaoqing Lianli Thermal Power Plant. The flue gas waste heat recovery heat exchanger is installed at the midpoint between the exhaust port of the induced draft fan and the desulfurization tower. Demineralized water enters the heat exchange equipment through pipelines, transferring the waste heat of the flue gas to the demineralized water. The cooled flue gas directly enters the desulfurization tower for absorption and discharge, achieving the purpose of waste heat recovery, saving energy consumption, and assisting the manufacturer in energy conservation and consumption reduction.

[0050] After practical use, the heat exchanger's pressure resistance and corrosion resistance both met the requirements, and it achieved good heat recovery efficiency while being able to withstand the dew point corrosion of the flue gas before desulfurization.

[0051] The embodiments of this utility model have been described in detail above, but the content described is only a preferred embodiment of this utility model and is not intended to limit this utility model. Any modifications, equivalent substitutions, and improvements made within the scope of this utility model application should be included within the protection scope of this utility model.

Claims

1. A corrosion-resistant heat exchanger for waste heat recovery, characterized in that... It includes a support frame (1), a flue gas inlet (2), a heat exchange module (3), a flue gas outlet (4), bolts (5), nuts (6), and graphite packing (7). The heat exchange module (3) is fixedly connected to the support frame (1) by bolts (5) and nuts (6). The upper and lower sides of the heat exchange module (3) are respectively provided with a flue gas inlet (2) and a flue gas outlet (4). The heat exchange module (3) is provided with a graphite packing (7).

2. The corrosion-resistant heat exchanger for waste heat recovery according to claim 1, characterized in that, The graphite tube is integrally formed by extrusion of thermosetting polymer phenolic resin and graphite; circulating water flows inside the graphite tube, and flue gas flows outside the graphite tube.

3. The corrosion-resistant heat exchanger for waste heat recovery according to claim 1, characterized in that, The tube sheet of the heat exchange module (3) is sealed with an O-ring, which is set in the sealing groove.

4. The corrosion-resistant heat exchanger for waste heat recovery according to claim 1, characterized in that, The heat exchange module (3) has a cold side inlet and a cold side outlet at both ends of the tube side, and a hot side inlet and a hot side outlet at both ends of the shell side.

5. The corrosion-resistant heat exchanger for waste heat recovery according to claim 1, characterized in that, The heat exchange module (3) is provided with a tube box exhaust port and a tube box liquid drain port on the upper and lower sides respectively.

6. The corrosion-resistant heat exchanger for waste heat recovery according to claim 1, characterized in that, A drain outlet and a manhole are provided on the pipe where the flue gas outlet (4) is located.

7. The corrosion-resistant heat exchanger for waste heat recovery according to claim 1, characterized in that, A pressure measuring port, a temperature measuring port, a manhole, and a flushing port are provided on the pipeline where the flue gas inlet (2) is located.

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