Corrosion-resistant structure of sodium aluminate solution evaporator and anti-crystallization method

Abstract

The invention discloses a corrosion-resistant structure of a sodium aluminate solution evaporator and an anti-crystallization method, and relates to the technical field of evaporators.The corrosion-resistant structure comprises the evaporator, a shell of the evaporator is composed of a first tank body and a second tank body, and two connecting assemblies are arranged on the front side and the rear side of the outer surface between the first tank body and the second tank body in a mirror image mode. Through cooperative use of the first protective sleeve, the first inner cylinder, the second inner cylinder and the second protective sleeve, the thicknesses of the first tank body and the second tank body are increased, use of a sodium aluminate solution is facilitated, meanwhile, an aluminum-based composite coating can be sprayed to enhance corrosion resistance, a U-shaped block is rotated to drive a spring, a positioning frame is moved to limit the U-shaped block, and the service life of the U-shaped block is prolonged. Then the first tank body and the second tank body can be separated by moving the first tank body upwards, the second protective sleeve and the first protective sleeve can be conveniently moved out and replaced, meanwhile, residues on the inner wall can be conveniently cleaned, the residues accumulated all the year round are prevented from corroding the tank body, and through the arrangement of the structure, the tank body can be conveniently opened to clean or replace the interior; and the service life is prolonged.

Description

Technical Field

[0001] This invention relates to the field of evaporator technology, specifically to a corrosion-resistant structure and anti-crystallization method for a sodium aluminate solution evaporator. Background Technology

[0002] Sodium aluminate solution evaporators are key equipment in the alumina production process for concentrating sodium aluminate solutions. Their primary task is to remove water from the solution through thermal evaporation, thereby increasing the concentration of sodium aluminate. This process places high demands on the corrosion resistance, heat transfer efficiency, and anti-crystallization capabilities of the equipment structure. In practical applications, evaporators typically need to withstand high temperatures and highly alkaline environments for extended periods, accompanied by high solid-liquid ratios and the risk of crystallization, which can easily lead to localized corrosion, blockage, or even failure.

[0003] Existing sodium aluminate evaporators generally employ a single-layer stainless steel tank structure, directly exposed to high-concentration sodium aluminate solutions. While possessing a certain degree of corrosion resistance, during continuous operation, crystals easily precipitate from the sodium aluminate solution and deposit on the heat exchange surface or the inner wall of the evaporator, forming a scale layer that severely impacts heat transfer efficiency. Especially in areas with large temperature gradients and uneven flow, localized crystallization blockage is more likely to occur, leading to thermal stress concentration, structural fatigue, or internal wall corrosion. Furthermore, since most existing equipment uses a monolithic welded structure, disassembly is difficult and maintenance is inconvenient, resulting in long cleaning cycles and high maintenance costs, further limiting the long-term stable operation of the equipment.

[0004] Furthermore, regarding the issue of crystallization control, most existing anti-crystallization technologies remain at the level of adjusting heating temperature or setting up simple stirring devices, lacking comprehensive control measures for the crystallization formation mechanism. Functions such as intelligent temperature regulation, local wall heating, and automatic spray rinsing have not yet been integrated, thus failing to effectively solve the problem of crystal accumulation during high-load, long-cycle operation.

[0005] Therefore, we need a corrosion-resistant structure for sodium aluminate solution evaporators to solve the above problems. Summary of the Invention

[0006] This invention provides a corrosion-resistant structure and anti-crystallization method for a sodium aluminate solution evaporator to solve the problems mentioned in the background art.

[0007] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows:

[0008] A corrosion-resistant structure for a sodium aluminate solution evaporator includes an evaporator. The outer shell of the evaporator is composed of a tank body one and a tank body two. Two connecting components are arranged in a mirror image on the outer surfaces of the tank body one and the tank body two. A liquid outlet pipe is provided in the middle of the lower surface of the tank body two, and a valve is provided on the outer surface of the liquid outlet pipe. An inlet pipe is provided on the upper left side of the outer surface of the tank body two, and a vapor discharge pipe is provided in the middle of the upper surface of the tank body one.

[0009] The inner cylinder of the tank body 2 is provided inside. A protective sleeve 1 is fixedly connected to the outer surface of the inner cylinder 1. A collar is fixedly connected to the middle of the upper surface of the inner cylinder 1. A sealing gasket 1 is fixedly connected to the upper surface of the collar. A sealing gasket 2 is provided on the upper surface of the tank body 2. The inner cylinder 2 is provided inside the tank body 1. A protective sleeve 2 is fixedly connected to the outer surface of the inner cylinder 2.

[0010] A further improvement of the technical solution of the present invention is that: the length of the inner cylinder II is less than the length of the protective sleeve II, the lower surface of the inner cylinder II forms a groove with the inner wall of the protective sleeve II, the outer surfaces of the collar and the sealing gasket I are inserted into the inside of the groove, and the upper surface of the sealing gasket II corresponds to the lower surface of the tank body I.

[0011] A further improvement of the technical solution of the present invention is that: the lower surface of the inner cylinder one is fixedly connected to the upper part of the outer surface of the liquid outlet pipe, and the outer surface of the liquid outlet pipe is slidably connected through the interior of the protective sleeve one and the tank body two.

[0012] A further improvement of the technical solution of the present invention is that: an opening is provided on the inner left side of the inner cylinder and the protective sleeve, corresponding to the inlet pipe; the outer surface of the inlet pipe is threaded through the inner part of the tank body; a rubber ring is fixedly connected to the right end of the inlet pipe; and the outer surface of the protective sleeve is tightly fitted to the right side of the rubber ring.

[0013] A further improvement of the technical solution of the present invention is that: the outer surface of the steam discharge pipe is slidably connected to the interior of the first tank body, and the lower end of the steam discharge pipe is fixedly connected to the upper surface of the second inner cylinder.

[0014] A further improvement of the technical solution of the present invention is that the material of the first protective sleeve and the second protective sleeve is 316L stainless steel, and the material of the second inner cylinder and the first inner cylinder is 304L stainless steel.

[0015] A further improvement of the technical solution of the present invention is that: the connecting components at the front and rear each include two fixing blocks, the surface of the upper fixing block is fixedly connected to the surface of the first tank, the surface of the lower fixing block is fixedly connected to the surface of the second tank, a blocking block is fixedly connected to the left side of the front of both the upper and lower fixing blocks, a connecting block is fixedly connected to the lower center of the front of the lower fixing block, an installation rod is fixedly connected to the center of the upper surface of the connecting block, a U-shaped block is movably connected through the outer surface of the installation rod, the inner side of the U-shaped block corresponds to the outer surface of the two blocking blocks, a spring is sleeved on the lower surface of the outer surface of the installation rod, and the upper and lower ends of the spring are fixedly connected to the surfaces of the U-shaped block and the connecting block, respectively.

[0016] A further improvement of the technical solution of the present invention is that: a T-shaped groove is provided on the right side of the front of the fixing block below, a T-shaped block is slidably connected inside the T-shaped groove, and a positioning frame is fixedly connected to the outer surface of the T-shaped block, the inner side of the positioning frame corresponds to the lower part of the outer surface of the U-shaped block.

[0017] The present invention also provides a method for preventing crystallization in a sodium aluminate solution evaporator, the method being applied to the sodium aluminate solution evaporator, specifically including the following steps:

[0018] S1. The wall temperature T1 of the inner cylinder 1 and the inner wall of the protective sleeve 1 is detected in real time by a temperature sensor;

[0019] S2. When the detected temperature T1 is lower than the sodium aluminate crystallization threshold temperature T0, the electric heating wire is activated to locally heat the protective sleeve, so that the wall temperature is maintained at T1≥T0.

[0020] S3. At the same time, diluent is periodically injected through the spray system. The spray liquid enters the protective sleeve (21) from the inlet pipe and washes the inner wall of the evaporation chamber, carrying any crystal particles that may precipitate into the outlet pipe for discharge.

[0021] S4. Control the continuous discharge of water vapor from the steam discharge pipe to maintain a stable evaporation environment and pressure, so as to prevent crystal deposition due to local supersaturation.

[0022] As a preferred technical solution of the present invention: the temperature threshold T0 is 60℃~75℃, and heating is automatically started when T1 is lower than this range. The spray system performs periodic spraying every 5~10 minutes, and each spraying lasts for 30~60 seconds. The electric heating wire is set in the interlayer between the protective sleeve (21) and the inner cylinder (22), and the constant power regulation method is used to maintain the constant wall temperature.

[0023] Due to the adoption of the above technical solution, the technical progress achieved by this invention compared to the prior art is as follows:

[0024] This invention provides a corrosion-resistant structure for a sodium aluminate solution evaporator. During use, the combined use of a protective sleeve, an inner cylinder, and an inner cylinder, along with the protective sleeve, increases the thickness of both tanks, facilitating the use of the sodium aluminate solution. An aluminum-based composite coating can be sprayed to enhance corrosion resistance. Rotating a U-shaped block drives a spring, which moves a positioning frame to limit the U-shaped block's position. Then, moving tank one upwards separates tank one and tank two, facilitating the removal and replacement of the protective sleeves. This also allows for easy cleaning of the inner wall to prevent corrosion from accumulated residues. This structure facilitates opening for internal cleaning or replacement, thus extending the service life.

[0025] The anti-crystallization method proposed in this invention effectively inhibits the precipitation of sodium aluminate solution on the evaporator wall and in structural dead corners through the synergistic effect of closed-loop temperature control and a spray dilution mechanism. When the wall temperature falls below a set threshold, the heating wire is automatically activated, and an intermittent spray system is used to rinse and clean the inner wall. This not only improves the ability to keep the heat exchange surface clean but also significantly reduces the rate of crystal accumulation. Through intelligent feedback adjustment of parameters such as temperature, flow rate, and pressure, the entire system can achieve continuous, stable, and low-fouling operation. Compared with traditional methods relying on manual periodic cleaning or single heating, this method offers advantages such as rapid response, precise control, long operating cycles, and low maintenance costs, significantly improving the stability and economy of sodium aluminate solution evaporators in industrial applications. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the structure of the present invention;

[0027] Figure 2 This is a schematic diagram of the exploded cross-section of the tank body of the present invention;

[0028] Figure 3 This is a schematic diagram of the bottom structure of the tank body of the present invention;

[0029] Figure 4 This is a schematic diagram of the connection component structure of the present invention.

[0030] In the diagram: 1. Tank body one; 11. Protective sleeve two; 12. Groove; 13. Inner cylinder two; 2. Tank body two; 21. Protective sleeve one; 22. Inner cylinder one; 23. Collar; 24. Sealing gasket one; 25. Sealing gasket two; 3. Connecting assembly; 31. Fixing block; 32. Blocking block; 33. Mounting rod; 34. Spring; 35. U-shaped block; 36. T-shaped groove; 37. T-shaped block; 38. Positioning frame; 4. Liquid outlet pipe; 5. Inlet pipe; 6. Steam discharge pipe. Detailed Implementation

[0031] To make the technical means, creative features, objectives and effects of this invention easier to understand, the invention will be further described below in conjunction with specific embodiments.

[0032] Example 1: As Figures 1 to 4 As shown, this invention provides a corrosion-resistant structure for a sodium aluminate solution evaporator, including an evaporator whose outer shell is composed of a tank 1 and a tank 2. Two connecting components 3 are mirror-image arranged on the outer surfaces of the tank 1 and the tank 2, facilitating the loading and unloading of the tank 1 and the tank 2. A liquid outlet pipe 4 is provided in the middle of the lower surface of the tank 2, facilitating the discharge of materials. A valve is provided on the outer surface of the liquid outlet pipe 4, which is convenient for opening or closing operations and is closed after sodium aluminate solution enters. An inlet pipe 5 is provided on the upper left side of the outer surface of the tank 2, facilitating the entry of sodium aluminate solution into the evaporator. A steam discharge pipe 6 is provided in the middle of the upper surface of the tank 1, facilitating the heating and evaporation of sodium aluminate solution by the internal heating structure of the evaporator, allowing steam to be discharged through the steam discharge pipe 6. In addition, the steam discharge pipe 6 is connected to a plate condenser in the prior art via a conveying pipe.

[0033] In addition, a heating rod and a heating wire can be installed inside the protective sleeve 21 of the tank body 2 to heat and evaporate the sodium aluminate solution inside the protective sleeve 21.

[0034] Example 2: Figures 1 to 4As shown, the inner cylinder 22 is provided inside the tank body 2. A protective sleeve 21 is fixedly connected to the outer surface of the inner cylinder 22. A collar 23 is fixedly connected to the middle of the upper surface of the inner cylinder 22. The collar 23 facilitates the connection and installation of the tank body 2. A sealing gasket 24 is fixedly connected to the upper surface of the collar 23. A sealing gasket 25 is provided on the upper surface of the tank body 2. The sealing gaskets 24 and 25 are made of fluororubber, which has excellent corrosion resistance and needs to be replaced periodically. They provide a sealing effect after the tank body 1 and tank body 2 are installed. The sealing gaskets 24 and 25 are bonded to the sleeve 23 and the surface of the tank body 2 with adhesive. The inner cylinder 13 is provided inside the tank body 1. The outer surface of the inner cylinder 13 is fixedly connected to... There is a protective sleeve 21, and the length of the inner cylinder 2 13 is less than the length of the protective sleeve 21. The lower surface of the inner cylinder 2 13 forms a groove 12 with the inner wall of the protective sleeve 21. The groove 12 facilitates the insertion of the collar 23 and the sealing gasket 1 24 into the interior for initial positioning. The outer surfaces of the collar 23 and the sealing gasket 1 24 are inserted into the interior of the groove 12. The upper surface of the sealing gasket 2 25 corresponds to the lower surface of the tank body 1. In addition, the protective sleeve 1 21 and the protective sleeve 2 11 are made of 316L stainless steel, and the inner cylinder 2 13 and the inner cylinder 1 22 are made of 304L stainless steel. The use of two types of stainless steel facilitates the use of sodium aluminate solution. At the same time, the outer surfaces of the two types of stainless steel can be sprayed with an aluminum-based composite coating to enhance corrosion resistance, thereby improving the corrosion resistance of the evaporator.

[0035] The lower surface of the inner cylinder 22 is fixedly connected to the upper part of the outer surface of the outlet pipe 4. The outer surface of the outlet pipe 4 slides through the interior of the protective sleeve 21 and the tank body 2. Both the inner cylinder 22 and the protective sleeve 21 have openings on their inner left sides corresponding to the inlet pipe 5. These openings facilitate the entry of sodium aluminate solution into the evaporator. The outer surface of the inlet pipe 5 is threaded through the interior of the tank body 2, allowing for easy disassembly. A rubber ring is fixedly connected to the right end of the inlet pipe 5. The rubber ring is made of the same material as the sealing gasket and also needs to be replaced periodically. The outer surface of the side protective sleeve 21 fits tightly, and the lower part of the outer surface of the steam discharge pipe 6 slides through the interior of the tank body 1. The lower end of the steam discharge pipe 6 is fixedly connected to the upper surface of the inner cylinder 2 13. In addition, the outer surfaces of the protective sleeve 21 and the protective sleeve 2 11 are placed in the tank body 1 and the tank body 2 respectively. With this structure, when disassembling, after the tank body 1 and the tank body 2 are separated, the protective sleeve 21 and the protective sleeve 2 11 can be moved, which will drive the inner cylinder 22 and the inner cylinder 2 13, so as to facilitate disassembly and replacement. It also makes it easy to clean the internal residue after disassembly, thus improving the service life.

[0036] Example 3: Figures 1 to 4 As shown, both the front and rear connecting components 3 include two fixing blocks 31. The two fixing blocks 31 facilitate the installation of the surface structure. The surface of the upper fixing block 31 is fixedly connected to the surface of tank 1, and the surface of the lower fixing block 31 is fixedly connected to the surface of tank 2. A blocking block 32 is fixedly connected to the left side of the front of both the upper and lower fixing blocks 31. The blocking block 32 facilitates the use of the U-shaped block 35 to limit the movement of the two blocking blocks 32. A connecting block is fixedly connected to the lower center of the front of the lower fixing block 31. The connecting block facilitates the fixed installation of the mounting rod 33. The mounting rod 33 is fixedly connected to the middle of the upper surface of the connecting block. The U-shaped block 35 is movably connected through the outer surface of the mounting rod 33. The movable connection allows the U-shaped block 35 to rotate, facilitating the opening or closing of the two blocking blocks 32. The inner side of the U-shaped block 35 corresponds to and cooperates with the outer surface of the two blocking blocks 32 to achieve the limiting function. A sleeve is attached to the lower part of the outer surface of the mounting rod 33. Spring 34 is fixedly connected to the surfaces of U-shaped block 35 and connecting block at its upper and lower ends, respectively. The spring 34 causes U-shaped block 35 to rotate and open or close, thus driving the spring 34. When U-shaped block 35 is released, the elasticity of the spring 34 causes U-shaped block 35 to reset, thus limiting the closure of the two blocking blocks 32. A T-shaped groove 36 is provided on the right side of the lower fixing block 31. A T-shaped block 37 is slidably connected inside the T-shaped groove 36. A positioning frame 38 is fixedly connected to the outer surface of T-shaped block 37. The inner side of the positioning frame 38 corresponds to the lower outer surface of U-shaped block 35. With this structure, rotating U-shaped block 35 drives spring 34. When rotated to the appropriate position, the positioning frame 38 moves, causing T-shaped block 37 to slide inside the T-shaped groove 36. When slid to the appropriate position, the positioning frame 38 inserts into the lower outer surface of U-shaped block 35, thus limiting the opening of U-shaped block 35 and facilitating the upward movement and disassembly of tank 1.

[0037] Example 4: Based on the above structural design, this example further introduces a method to prevent sodium aluminate solution from crystallizing inside the evaporator, applicable to continuous evaporation systems in sodium aluminate concentration processes. In actual operation, the sodium aluminate solution is injected into the main cavity of the evaporator through the inlet pipe 5. The heating chamber formed by the protective sleeve 21 and the inner cylinder 22 serves as the solution heating and evaporation area. Heating rods are installed inside, along with electric heating wires arranged along the inner wall of the protective sleeve for localized temperature maintenance.

[0038] To prevent sodium aluminate solution from crystallizing on the walls of the evaporation chamber, the system continuously monitors the real-time temperature of the inner walls of the protective sleeve 21 and the inner cylinder 22 using temperature sensors. When the detected temperature T1 is lower than the set crystallization critical temperature T0 (e.g., 68°C), the control system immediately drives the heating wire to heat the wall, causing the wall temperature to quickly rise to above 70°C, ensuring it remains within the temperature range where crystals are unlikely to form. Furthermore, to enhance the wall cleaning effect, an automatic spray dilution system is introduced in addition to heating and temperature maintenance. The system is equipped with a circulating pump and spray pipeline, automatically starting the spray every 8 minutes for 30 seconds. The spray solution used is a diluted sodium aluminate solution at approximately 10°C. After being introduced through the inlet pipe 5, the spray solution is evenly distributed on the inner wall surface, effectively flushing away the initially nucleated crystals and carrying away particle deposits.

[0039] Under the synergistic effect of spraying and heating, the tendency for crystallization is significantly reduced, and the liquid is discharged from outlet pipe 4 to the rear recovery unit. Simultaneously, the steam outlet pipe 6 at the top of the evaporation chamber remains open, allowing the steam drawn from it to enter the condenser for cooling and recovery, thus controlling the pressure of the entire chamber to remain stable within the range of 0.1–0.2 MPa, further preventing wall crystallization deposition caused by oversaturation. The entire system is controlled in a closed-loop manner by a PLC automatic control unit, which collects key variables such as wall temperature, spray frequency, liquid concentration, and steam discharge rate, and adjusts the heating power and spray frequency in real time accordingly to achieve dynamic steady-state control, ensuring that the evaporator does not experience crystallization blockage during continuous operation.

[0040] By implementing this method, the anti-crystallization capability of sodium aluminate solution evaporators can be significantly improved, the operating cycle can be extended, the cleaning frequency can be reduced, and the corrosion risk caused by crystal adhesion can be avoided, thus possessing good industrial application value.

[0041] Working principle: The inner wall thickness of the evaporator is increased by the arrangement of protective sleeve 21, inner cylinder 22, inner cylinder 23, and protective sleeve 21, which facilitates the use of sodium aluminate solution. At the same time, the surface is sprayed with an aluminum-based composite coating to enhance corrosion resistance, thereby improving corrosion resistance. By rotating the U-shaped block 35, the spring 34 is driven, and the U-shaped block 35 is limited by the moving positioning frame 38. Then, by moving the tank body 1 upward, the groove 12 is separated from the inside of the collar 23, which facilitates the cleaning of internal residues. By removing the protective sleeve 21 and protective sleeve 21, the internal structure can be easily replaced, preventing the possibility of corrosion of the evaporator interior by residues accumulated over the years, thus extending the service life of the evaporator.

[0042] The present invention has been described in detail above. However, modifications or improvements can be made to it, which will be obvious to those skilled in the art. Therefore, any modifications or improvements that do not depart from the spirit of the present invention are within the scope of protection of the present invention.

Claims

1. A corrosion-resistant structure for a sodium aluminate solution evaporator, comprising an evaporator, characterized in that: The outer shell of the evaporator is composed of a tank body one (1) and a tank body two (2). Two connecting components (3) are arranged in a mirror image on the outer surface of the tank body one (1) and the tank body two (2). A liquid outlet pipe (4) is provided in the middle of the lower surface of the tank body two (2). A valve is provided on the outer surface of the liquid outlet pipe (4). An inlet pipe (5) is provided on the upper left side of the outer surface of the tank body two (2). A steam discharge pipe (6) is provided in the middle of the upper surface of the tank body one (1). The inner cylinder (22) is provided inside the tank body 2. A protective sleeve (21) is fixedly connected to the outer surface of the inner cylinder (22). A collar (23) is fixedly connected to the middle of the upper surface of the inner cylinder (22). A sealing gasket (24) is fixedly connected to the upper surface of the collar (23). A sealing gasket (25) is provided on the upper surface of the tank body 2 (2). The inner cylinder (13) is provided inside the tank body 1 (1). A protective sleeve (11) is fixedly connected to the outer surface of the inner cylinder (13).

2. The corrosion-resistant structure of a sodium aluminate solution evaporator according to claim 1, characterized in that: The length of the inner cylinder 2 (13) is less than the length of the protective sleeve 2 (11). The lower surface of the inner cylinder 2 (13) and the inner wall of the protective sleeve 2 (11) form a groove (12). The outer surfaces of the collar (23) and the sealing gasket 1 (24) are inserted into the inside of the groove (12). The upper surface of the sealing gasket 2 (25) corresponds to the lower surface of the tank body 1 (1).

3. The corrosion-resistant structure of a sodium aluminate solution evaporator according to claim 1, characterized in that: The lower surface of the inner cylinder (22) is fixedly connected to the upper part of the outer surface of the liquid outlet pipe (4), and the outer surface of the liquid outlet pipe (4) is slidably connected to the inside of the protective sleeve (21) and the tank body (2).

4. The corrosion-resistant structure of a sodium aluminate solution evaporator according to claim 1, characterized in that: The inner left side of the inner cylinder (22) and the protective sleeve (21) are provided with openings corresponding to the inlet pipe (5). The outer surface of the inlet pipe (5) is threaded through the inside of the tank body (2). A rubber ring is fixedly connected to the right end of the inlet pipe (5), and the outer surface of the protective sleeve (21) on the right side of the rubber ring is tightly fitted.

5. The corrosion-resistant structure of a sodium aluminate solution evaporator according to claim 1, characterized in that: The outer surface of the steam discharge pipe (6) is slidably connected to the inside of the tank body (1) below the outer surface, and the lower end of the steam discharge pipe (6) is fixedly connected to the upper surface of the inner cylinder (13).

6. The corrosion-resistant structure of a sodium aluminate solution evaporator according to claim 1, characterized in that: The protective sleeve one (21) and the protective sleeve two (11) are made of 316L stainless steel, and the inner cylinder two (13) and the inner cylinder one (22) are made of 304L stainless steel.

7. The corrosion-resistant structure of a sodium aluminate solution evaporator according to claim 1, characterized in that: The connecting components (3) at the front and rear each include two fixing blocks (31). The surface of the upper fixing block (31) is fixedly connected to the surface of the first tank (1), and the surface of the lower fixing block (31) is fixedly connected to the surface of the second tank (2). A blocking block (32) is fixedly connected to the left side of the front of both the upper and lower fixing blocks (31). A connecting block is fixedly connected to the lower center of the front of the lower fixing block (31). An installation rod (33) is fixedly connected to the middle of the upper surface of the connecting block. A U-shaped block (35) is movably connected through the outer surface of the installation rod (33). The inner side of the U-shaped block (35) corresponds to and cooperates with the outer surfaces of the two blocking blocks (32). A spring (34) is sleeved on the lower side of the outer surface of the installation rod (33). The upper and lower ends of the spring (34) are fixedly connected to the surfaces of the U-shaped block (35) and the connecting block, respectively.

8. The corrosion-resistant structure of a sodium aluminate solution evaporator according to claim 7, characterized in that: A T-shaped groove (36) is provided on the right side of the front of the fixed block (31) below. A T-shaped block (37) is slidably connected inside the T-shaped groove (36). A positioning frame (38) is fixedly connected to the outer surface of the T-shaped block (37). The inner side of the positioning frame (38) corresponds to the lower part of the outer surface of the U-shaped block (35).

9. A method for preventing crystallization in a sodium aluminate solution evaporator, characterized in that, The method, when applied to the sodium aluminate solution evaporator according to claim 1, specifically includes the following steps: S1. The wall surface temperature T1 of the inner cylinder 1 (22) and the protective sleeve 1 (21) is detected in real time by a temperature sensor; S2. When the detection temperature T1 is lower than the sodium aluminate crystallization threshold temperature T0, the electric heating wire is started to locally heat the protective sleeve (21) so that the wall temperature is kept at T1≥T0. S3. At the same time, the diluent is periodically injected through the spray system. The spray liquid enters the protective sleeve (21) from the inlet pipe (5) and washes the inner wall of the evaporation chamber. It carries the crystal particles that may precipitate into the outlet pipe (4) and is discharged. S4. Control the steam discharge pipe (6) to continuously discharge water vapor, maintain a stable evaporation environment and pressure, and prevent crystal deposition due to local oversaturation.

10. The method according to claim 9, characterized in that: The temperature threshold T0 is 60℃~75℃. When T1 is below this range, heating is automatically started. The spray system sprays periodically every 5 to 10 minutes, and each spray lasts for 30 to 60 seconds. The electric heating wire is placed in the interlayer between the protective sleeve (21) and the inner cylinder (22), and the wall temperature is kept constant by constant power regulation.

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