A high-efficiency and long-life heat exchanger

Abstract

The present invention relates to a high-efficiency, long-life heat exchanger, comprising a housing, a central rotor, a compartment, and a heat exchange element. The heat exchange element comprises three layers of material: a metal substrate, a transition layer, and a working layer. The working layer comprises the following components in specific weights: 30-65 wt% of a film-forming material, 10-25 wt% of a high-thermal-conductivity ceramic powder, 15-20 wt% of a high-thermal-conductivity whisker, 5-10 wt% of an organic solvent, 3-9 wt% of a curing agent, and 2-6 wt% of a dispersant. The high-efficiency, long-life heat exchanger of the present invention improves the strength and adhesion of the coating in the heat exchange element by establishing a high-thermal-conductivity transition layer. By adding high-thermal-conductivity ceramic powder and whiskers to the film-forming material, a working layer with a three-dimensional heat-conducting network is constructed, resulting in the heat exchange element having advantages such as high strength, strong thermal conductivity, a smooth surface, and resistance to dust and airflow erosion. The heat exchange element also exhibits the advantages of self-cleaning, high-temperature resistance, and high thermal conductivity, significantly improving the heat exchange efficiency of the heat exchanger and extending its service life.

Description

Technical Field

[0001] The present invention relates to the technical field of heat exchangers, and in particular to a high-efficiency and long-life heat exchanger and a manufacturing method thereof. Background Art

[0002] Heat exchangers are energy exchange equipment commonly used in chemical, light industry, energy, pharmaceutical, machinery and other industrial fields. The flue gas heat exchanger of the boiler in coal-fired power plants is an important equipment for improving the utilization rate of boiler waste heat. However, the working environment of the heat exchanger is relatively extreme. Its heat exchange elements need to work in extreme environments such as high temperature, acidic, and dusty gases. Therefore, traditional enamel heat exchangers have problems such as low thermal conductivity, breakage, acid corrosion, ash blockage, and falling off during the working process, which seriously affect the efficiency and life of the heat exchanger.

[0003] Chinese patent CN 113531578A discloses a high-efficiency rotary heat exchanger. Although the patent improves the heat exchange efficiency by improving the mechanical structure of the heat exchanger, it does not fundamentally solve the problems existing in the operation of the heat exchanger. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to solve the problems of low thermal conductivity, damage, acid corrosion, ash blockage, and shedding that occur during the working process of the heat exchanger due to the relatively extreme working environment of the heat exchanger.

[0005] To this end, the present invention provides a high-efficiency and long-life heat exchanger and a manufacturing process thereof, so that the heat exchanger has excellent corrosion resistance, self-cleaning ability, and high erosion resistance while having a long service life and excellent efficiency.

[0006] In order to solve the above technical problems, the present invention provides the following technical solutions:

[0007] A high-efficiency and long-life heat exchanger, comprising a shell, a central rotor, a compartment and a heat exchange element, wherein the compartment is rotatably connected to the shell via the central rotor, and the heat exchange element is arranged in the compartment; the heat exchange element comprises three layers of material: a metal substrate, a transition layer and a working layer; the transition layer is coated on the outer surface of the metal substrate, and the working layer is coated on the outer surface of the transition layer; the working layer comprises the following components in specific gravity: 30-65wt% of a first film-forming material, 10-25wt% of a high thermal conductivity ceramic powder, 15-20wt% of a high thermal conductivity whisker, 5-10wt% of an organic solvent, 3-9wt% of a curing agent, and 2-6wt% of a dispersant.

[0008] The heat exchange element is composed of three layers of material, the second layer is coated on the first layer, and the third layer is coated on the second layer. The first layer is a metal matrix, the second layer is a transition layer with high strength, high adhesion, and high thermal conductivity on the surface of the matrix, and the third layer is a working layer on the surface of the transition layer with high thermal conductivity, high temperature resistance, good erosion resistance, and self-cleaning.

[0009] Preferably, the transition layer comprises the following components in proportion: 60-75 wt% of a second film-forming material, 10-16 wt% of a thermally conductive reinforcing body, 5-10 wt% of an organic solvent, 8-10 wt% of a curing agent, and 2-4 wt% of a dispersant.

[0010] Preferably, the second film-forming material is polyester-modified silicone resin; and the thermal conductivity reinforcement includes one or more of graphene and nanotubes.

[0011] Preferably, the second film-forming material is an organosilicon-modified epoxy resin with methyl and phenyl groups; the high thermal conductivity ceramic powder includes one or more of aluminum oxide, silicon nitride, and silicon carbide; and the high thermal conductivity whiskers include one or more of aluminum oxide whiskers, silicon nitride whiskers, and silicon carbide whiskers.

[0012] Preferably, the diameter of the high thermal conductivity whisker is 0.5-2 μm, and the aspect ratio is greater than 10.

[0013] High thermal conductivity whiskers must have an aspect ratio greater than 10 to form a heat conduction network. If the aspect ratio is too small, it will be difficult to form a network, reducing the heat conduction efficiency.

[0014] Preferably, the metal substrate is a ferritic stainless steel plate.

[0015] Preferably, the thickness of the metal substrate is 1000-1100 μm, the thickness of the transition layer is 50-200 μm, and the thickness of the working layer is 100-300 μm.

[0016] Preferably, the heat exchanger is a rotary flue gas heat exchanger.

[0017] A method for preparing the above-mentioned high-efficiency and long-life heat exchanger comprises the following steps:

[0018] (1) The metal substrate sheet is formed according to the design requirements and the surface is roughly ground and cleaned, that is, the surface of the ferritic stainless steel substrate obtained by casting is polished and cleaned, and then allowed to stand and dry;

[0019] (2) modifying the graphene surface and mixing it with a film-forming material, an organic solvent, a dispersant, and a curing agent, and dispersing the mixture in a high-speed disperser to obtain a transition layer coating;

[0020] (3) modifying the surface of the high thermal conductivity powder and the high thermal conductivity whisker and mixing them with a film-forming material, an organic solvent, a dispersant, and a curing agent, and dispersing the mixture in a high-speed disperser to obtain a working layer coating;

[0021] (4) applying the transition layer coating to the surface of the metal substrate, allowing it to dry, thereby forming the transition layer; and then applying the working layer coating to the surface of the transition layer, allowing it to level, thereby forming the working layer;

[0022] (5) After coating, the heat exchange element is placed in a heating furnace and heated and cured to obtain the heat exchange element;

[0023] (6) The lower shell of the outer shell is installed and fixed, and then the central rotor and the compartment are assembled on the lower shell of the outer shell. After completion, the upper shell of the outer shell is installed on the lower shell of the outer shell, and the positions of the installed parts are adjusted. Then, the prepared heat exchange element is installed in the compartment of the heat exchanger. Finally, the central rotor flange is fine-machined and the outer shell is polished to obtain the high-efficiency and long-life heat exchanger.

[0024] Preferably, in step (2), curing is carried out by keeping the temperature at 150-300° C. in a heating furnace for 30-60 minutes.

[0025] Preferably, in step (4), the coating is carried out by spraying, the spraying pressure of the spray gun is controlled to be 0.15-0.30 MPa, the distance between the nozzle and the component is about 200-300 mm, and the coating is evenly swept from left to right until the coating thickness requirement is met.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] 1. In the working layer, high thermal conductivity ceramic powder and high thermal conductivity whiskers overlap each other to form a three-dimensional thermal conductive structure. While the heat exchanger maintains high thermal conductivity, the organic combination of ceramic powder and silicone-modified epoxy resin with good temperature resistance also significantly improves the heat exchanger's resistance to dust erosion, thereby greatly extending the service life of the heat exchanger.

[0028] 2. Because the epoxy-modified silicone resin in the working layer is mixed with a large amount of ceramic powder and whiskers, the contact area between the resin and the substrate is reduced, the adsorption effect becomes poor, the tensile strength of the coating is low, and the adhesion directly to the metal substrate is not high, which is very likely to cause it to fall off during use. Therefore, a transition layer is provided that can firmly bond to both the metal substrate and the working layer. In this transition layer, a polyester-modified silicone resin with better adhesion is used as the base material, mixed with graphene or nanotubes to form a high-strength, high-thermal conductivity transition layer. This not only solves the problem of excessive ceramic powder causing low tensile strength of the heat exchanger coating after heating, but also improves the adhesion between the coating and the substrate, thereby effectively extending the service life of the heat exchanger.

[0029] 3. The resins in the transition layer and the working layer undergo a polymerization reaction, resulting in a tight connection between the transition layer and the working layer. This not only ensures high tensile strength for the heat exchange element as a whole, but also ensures thermal conductivity and resistance to dust impact. Therefore, when used, this heat exchanger not only has the advantages of high temperature resistance, erosion resistance, and easy cleaning, but also has excellent heat exchange efficiency, achieving the goal of high efficiency and long life of the heat exchanger.

[0030] 4. The high-efficiency and long-life heat exchanger of the present invention improves the strength and adhesion of the coating in the heat exchange element by establishing a high-thermal-conductivity transition layer. By adding high-thermal-conductivity ceramic powder and whiskers to the film-forming material, a working layer with a three-dimensional thermal conductive network is constructed, which makes the heat exchange element have the advantages of high strength, strong thermal conductivity, smooth surface, and resistance to dust and airflow erosion. It has the advantages of self-cleaning, high-temperature resistance, and high thermal conductivity, which can greatly improve the heat exchange efficiency of the heat exchanger and extend the service life of the heat exchanger. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 It is a structural schematic diagram of the heat exchange element of the present invention. DETAILED DESCRIPTION

[0032] In order to make the objectives, technical solutions and advantages of the present invention more clear, the present invention will be described in further detail below with reference to the accompanying drawings.

[0033] Example 1:

[0034] Polish and clean the surface of the ferritic stainless steel substrate, then let it stand and dry; mix 600g of polyester modified silicone resin, 160g of modified graphene, 100g of organic solvent, 100g of curing agent and 40g of dispersant; mix 350g of silicone modified epoxy resin, 250g of modified alumina, 200g of alumina whiskers, 100g of organic solvent, 40g of curing agent and 60g of dispersant to obtain uniformly dispersed transition layer and working layer coatings. Add the obtained transition layer coating and working layer coating to the spray gun respectively, spray the coating in turn, sweep evenly from left to right, repeat several times until the required thickness of the coating is reached, and let it flow and stand. Then put the heat exchange element into the annealing furnace and keep it at 250℃ for 60 minutes to obtain Figure 1 The heat exchange element shown in the figure; install and fix the lower shell of the heat exchanger, then assemble the rotor and the compartment on the lower shell. After completion, install the upper and middle shells and the lower shell, and adjust the position of the installed parts. Then install the prepared heat exchange element in the compartment of the heat exchanger. Finally, finish the rotor flange and polish the outer shell to obtain a high-efficiency and long-life heat exchanger.

[0035] Example 2:

[0036] Polish and clean the surface of the ferritic stainless steel substrate, then let it stand and dry; mix 600g of polyester modified silicone resin, 160g of modified nanotubes, 100g of organic solvent, 100g of curing agent and 40g of dispersant; mix 500g of silicone modified epoxy resin, 150g of modified alumina, 150g of alumina whiskers, 100g of organic solvent, 70g of curing agent and 30g of dispersant to obtain uniformly dispersed transition layer and working layer coatings. Add the obtained transition layer coating and working layer coating to the spray gun respectively, spray the coating in turn, sweep evenly from left to right, repeat several times until the required thickness of the coating is reached, and let it flow and stand. Then put the heat exchange element into the annealing furnace and keep it at 250℃ for 60 minutes to obtain Figure 1 The heat exchange element shown in the figure; install and fix the lower shell of the heat exchanger, then assemble the rotor and the compartment on the lower shell. After completion, install the upper and middle shells and the lower shell, and adjust the position of the installed parts. Then install the prepared heat exchange element in the compartment of the heat exchanger. Finally, finish the rotor flange and polish the outer shell to obtain a high-efficiency and long-life heat exchanger.

[0037] Example 3:

[0038] Polish and clean the surface of the ferritic stainless steel substrate, then let it stand and dry; mix 750g of polyester modified silicone resin, 100g of modified graphene, 50g of organic solvent, 80g of curing agent and 20g of dispersant; mix 650g of silicone modified epoxy resin, 100g of modified alumina, 150g of alumina whiskers, 50g of organic solvent, 30g of curing agent and 20g of dispersant to obtain uniformly dispersed transition layer and working layer coatings. Add the obtained transition layer coating and working layer coating to the spray gun respectively, spray the coating in turn, sweep evenly from left to right, repeat several times until the required thickness of the coating is reached, and let it flow and stand. Then put the heat exchange element into the annealing furnace and keep it at 250℃ for 60 minutes to obtain Figure 1 The heat exchange element shown in the figure; install and fix the lower shell of the heat exchanger, then assemble the rotor and the compartment on the lower shell. After completion, install the upper and middle shells and the lower shell, and adjust the position of the installed parts. Then install the prepared heat exchange element in the compartment of the heat exchanger. Finally, finish the rotor flange and polish the outer shell to obtain a high-efficiency and long-life heat exchanger.

[0039] Comparative Example 1:

[0040] The surface of the ferritic stainless steel substrate is polished and cleaned, and then allowed to dry; enamel is applied to the substrate surface and sintered to form a heat exchange element; the lower shell of the heat exchanger is installed and fixed, and the rotor and the compartment are assembled on the lower shell. After completion, the upper and middle shells are installed with the lower shell, and the positions of the installed parts are adjusted. The prepared heat exchange element is then installed in the compartment of the heat exchanger. Finally, the rotor flange is fine-machined and the outer shell is polished to obtain the heat exchanger.

[0041] Comparative Example 2:

[0042] The surface of the ferritic stainless steel substrate is polished and cleaned, and then allowed to dry. 350g of epoxy-modified silicone resin, 250g of modified alumina, 200g of alumina whiskers, 100g of organic solvent, 40g of curing agent, and 60g of dispersant are mixed to obtain a uniformly dispersed working layer coating. The obtained working layer coating is added to the spray gun and evenly swept from left to right. Repeat several times until the required coating thickness is reached, and then it is fluidized and allowed to stand. The heat exchange element is then placed in an annealing furnace and kept warm at 250°C for 60 minutes. The lower shell of the heat exchanger is installed and fixed, and the rotor and the compartment are assembled on the lower shell. After completion, the upper and middle shells are installed with the lower shell, and the positions of the installed parts are adjusted. The prepared heat exchange element is then installed in the compartment of the heat exchanger. Finally, the rotor flange is fine-machined and the outer shell is polished to obtain the heat exchanger.

[0043] Comparative Example 3:

[0044] The surface of the ferritic stainless steel substrate is polished and cleaned, and then allowed to dry. 600g of polyester-modified silicone resin, 160g of modified graphene, 100g of organic solvent, 100g of curing agent, and 40g of dispersant are mixed to obtain a uniformly dispersed transition layer coating. The resulting transition layer coating is added to a spray gun and evenly swept from left to right. Repeat several times until the coating reaches the required thickness, and then allowed to flow and stand. The heat exchange element is then placed in an annealing furnace and kept warm at 250°C for 60 minutes. The lower shell of the heat exchanger is installed and fixed, and the rotor and the compartment are assembled on the lower shell. After completion, the upper and middle shells are installed with the lower shell, and the positions of the installed components are adjusted. The prepared heat exchange element is then installed in the compartment of the heat exchanger. Finally, the rotor flange is fine-machined and the outer shell is polished to obtain the heat exchanger.

[0045] Effect example 1:

[0046] In order to verify the performance of the high-efficiency and long-life heat exchanger of the present invention, the heat exchangers in Examples 1-3 and Comparative Example 1 were subjected to thermal efficiency tests, adhesion tests of "cross-cut test of paint and varnish films", -20 to 250°C thermal shock cycle tests, and high-temperature erosion tests.

[0047] Among them, the conditions of the high-temperature erosion test are as follows: 40-70 mesh quartz sand is used as the scouring particle, the quartz sand content is 20g, the scouring pressure is 0.2-0.3Mpa, the scouring angle is 45°, the scouring time is 10h, and the test is carried out under hot air at a wind temperature of 280°C, and then the remaining mass percentage is detected.

[0048] The test results are shown in Table 1:

[0049] Table 1

[0050]

[0051] As can be seen from Table 1, the heat exchange efficiency of Comparative Examples 1-2 is far inferior to the high-efficiency, long-life heat exchanger obtained using the present invention. While the heat exchange efficiency of Comparative Example 3 is close to that of the Examples, its thermal shock resistance is far inferior to that of Examples 1-3. Under experimental conditions, the coating residue was only 78.9%, meaning that the heat exchanger would have a short lifespan in actual use and would not be able to function stably over the long term. Only Examples 1-3, using the present invention's solution, achieved a high-efficiency, long-life heat exchanger with extremely high heat exchange efficiency, excellent adhesion, and thermal shock resistance.

[0052] The above embodiments are merely descriptions of specific implementation methods of the present invention and do not limit the scope of the present invention. Those skilled in the art may make various modifications and changes based on the existing technology, such as adding other ceramic particles to the slurry. Without departing from the design spirit of the present invention, various modifications and improvements made by ordinary engineering technicians in this field to the technical solution of the present invention should fall within the scope of protection determined by the claims of the present invention.

Claims

1. A high-efficiency and long-life heat exchanger, characterized in that: The heat exchanger includes a shell, a central rotor, a cell and a heat exchange element, the cell is rotatably connected to the shell through the central rotor, and the heat exchange element is arranged in the cell; the heat exchange element includes three layers of materials: a metal substrate, a transition layer and a working layer; the transition layer is coated on the outer surface of the metal substrate, and the working layer is coated on the outer surface of the transition layer; the working layer includes the following components in specific gravity: 30~65wt% of a first film-forming material, 10~25wt% of a high thermal conductivity ceramic powder, 15~20wt% of a high thermal conductivity whisker, 5~10wt% of an organic solvent, 3~9wt% of a curing agent, and 2~6wt% of a dispersant; the transition layer includes the following components in specific gravity: 60~75wt% of a second film-forming material, 10~16wt% of a thermally conductive reinforcing body, 5~10wt% of an organic solvent, 8~10wt% of a curing agent, and 2~4wt% of a dispersant; the first film-forming material is an organosilicon-modified epoxy resin with methyl and phenyl groups; The second film-forming material is polyester-modified silicone resin.

2. The high-efficiency and long-life heat exchanger according to claim 1, characterized in that: The thermal conductivity reinforcement includes one or more of graphene and nanotubes.

3. The high-efficiency and long-life heat exchanger according to claim 1, characterized in that: The high thermal conductivity ceramic powder includes one or more of aluminum oxide, silicon nitride, and silicon carbide; and the high thermal conductivity whiskers include one or more of aluminum oxide whiskers, silicon nitride whiskers, and silicon carbide whiskers.

4. The high-efficiency and long-life heat exchanger according to claim 1, characterized in that: The diameter of the high thermal conductivity whisker is 0.5-2 μm, and the aspect ratio is greater than 10.

5. The high-efficiency and long-life heat exchanger according to claim 1, characterized in that: The metal matrix is ​​a ferritic stainless steel plate.

6. The high-efficiency and long-life heat exchanger according to claim 1, characterized in that: The thickness of the metal substrate is 1000-1100 μm, the thickness of the transition layer is 50-200 μm, and the thickness of the working layer is 100-300 μm.

7. The high-efficiency and long-life heat exchanger according to claim 1, characterized in that: The heat exchanger is a rotary flue gas heat exchanger.

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