Silicon carbide film evaporator

Abstract

The invention discloses a silicon carbide film evaporator, and relates to the field of evaporators, the silicon carbide film evaporator comprises a shell and a tube plate arranged in the shell, an evaporation tube is arranged on the tube plate, and a distance plate is further arranged in the shell; a distance fixing plate is arranged on the evaporation pipe, a film distributor is arranged on the distance fixing plate in a sliding mode, part of the film distributor extends into the evaporation pipe, an inclined section is arranged in the evaporation pipe, a gap allowing a liquid film to pass through is formed between the film distributor and the inclined section, and the size of the gap is adjusted based on the distance between the film distributor and the inclined section. According to the silicon carbide film evaporator, when the injection amount of liquid is small, the film distributor is controlled to be close to the inclined section, and at the moment, the gap becomes small, and when the injection amount of the liquid is large, the film distributor is controlled to be away from the inclined section, and at the moment, the gap becomes large, so that the film distributor can adapt to liquid with different injection amounts.

Description

Technical Field

[0001] This invention relates to the field of evaporators, and more specifically to a silicon carbide thin-film evaporator. Background Technology

[0002] As is well known, silicon carbide is a semiconductor, and its production process requires concentration using a falling film evaporator. The main characteristic of a falling film evaporator is that it utilizes gravity to allow the liquid to form a thin film on the tube wall, generating steam through heat transfer, thereby achieving the purpose of concentration or evaporation. Among these factors, the uniformity of the film distribution is a direct factor affecting the evaporation effect. The film distribution mainly includes the liquid distribution on the surface of the tube sheet and the film distribution inside the evaporation tubes.

[0003] The liquid distribution on the tube sheet surface is as described in the Chinese patent document with authorization announcement number CN217472729U, announcement date of 2022-09-23, entitled "A Liquid Distribution Structure for a Falling Film Evaporator". It includes an upper distributor and a lower distributor. The upper distributor includes an upper tank body, and the lower distributor includes a lower tank body. The bottom of the lower tank body is provided with multiple annular film distribution groups. Each film distribution group includes multiple distribution holes, and a film distribution head is inserted into each distribution hole.

[0004] The film-forming device inside the evaporator tube, as described in the Chinese patent document with authorization announcement number CN106693420B, announcement date 2019-01-25, entitled "A Falling Film Evaporator", includes a shell, a feed inlet, a material distribution system, a liquid distribution plate, and a tube sheet. The material distribution system, liquid distribution plate, and tube sheet are arranged sequentially from top to bottom below the feed inlet. The material distribution system evenly distributes the liquid entering from the feed inlet onto the liquid distribution plate. Several evaporator tubes are evenly inserted into the tube sheet. Several distributors are provided on the lower surface of the liquid distribution plate. The distributors are arranged perpendicular to the liquid distribution plate, and the number and position of the distributors correspond one-to-one with the evaporator tubes. The fixing part is fixed to the liquid distribution plate, and the film-forming part is inserted into the evaporator tube.

[0005] The shortcoming of the existing technology is that, since the distance between the bottom of the film-forming device and the inner wall of the evaporation tube is constant, although the injection volume of silicon carbide liquid (hereinafter referred to as liquid for convenience based on the speed of seconds) can be adjusted, the film thickness of the liquid cannot be adjusted. When the liquid injection volume is small, the performance of the film-forming part is reduced or even fails to function, so that the film-forming effect cannot meet the expectations. Summary of the Invention

[0006] The purpose of this invention is to provide a silicon carbide thin film evaporator to overcome the above-mentioned shortcomings of the prior art.

[0007] To achieve the above objectives, the present invention provides the following technical solution:

[0008] A silicon carbide thin film evaporator includes a shell and a tube sheet disposed inside the shell, wherein evaporation tubes are disposed on the tube sheet, and a spacer plate is also disposed inside the shell.

[0009] A film distributor is slidably disposed on the fixed-distance plate, and part of the film distributor extends into the interior of the evaporation tube. An inclined section is provided inside the evaporation tube, and there is a gap between the film distributor and the inclined section that allows the liquid film to pass through. The size of the gap is adjusted based on the distance between the film distributor and the inclined section.

[0010] In the aforementioned silicon carbide thin-film evaporator, the top of the evaporation tube is higher than the upper surface of the tube sheet.

[0011] The aforementioned silicon carbide thin-film evaporator has a hollow film distribution device.

[0012] In the aforementioned silicon carbide thin film evaporator, a limiting rod is fixedly connected to the tube sheet, and a limiting hole adapted to the limiting rod is provided on the film distributor. The limiting rod and the limiting hole are slidably connected.

[0013] In the aforementioned silicon carbide thin-film evaporator, the radial dimension of the top of the film distributor is greater than the radial dimension of the inclined section.

[0014] In the aforementioned silicon carbide thin-film evaporator, the film distributor is equipped with a sensor for detecting the moving distance of the film distributor.

[0015] The aforementioned silicon carbide thin film evaporator has a swirling assembly on the limiting rod for driving the film distributor to rotate.

[0016] In the aforementioned silicon carbide thin film evaporator, the swirling assembly includes an inclined groove formed on the limiting rod, and a transmission rod adapted to the inclined groove is formed inside the limiting hole, the transmission rod being slidably connected to the inclined groove.

[0017] The aforementioned silicon carbide thin-film evaporator includes a liquid distribution assembly on the film distributor for spreading the liquid on the surface of the tube sheet.

[0018] The aforementioned silicon carbide thin-film evaporator includes a liquid distribution assembly comprising a spreading rod fixed to the film distributor.

[0019] In the above technical solution, the silicon carbide thin film evaporator provided by the present invention has an inclined section inside the evaporation tube, and there is a gap between the film distributor and the inclined section that allows the liquid film to pass through. The size of the gap is adjusted based on the distance between the film distributor and the inclined section. That is, when the liquid injection volume is small, the film distributor is controlled to move closer to the inclined section, and the gap becomes smaller. When the liquid injection volume is large, the film distributor is controlled to move further away from the inclined section, and the gap becomes larger, so that the film distributor can adapt to different liquid injection volumes. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in this invention. For those skilled in the art, other drawings can be obtained based on these drawings.

[0021] Figure 1 This is a cross-sectional structural diagram provided for an embodiment of the present invention;

[0022] Figure 2 for Figure 1 Enlarged schematic diagram of a local structure at point A;

[0023] Figure 3 This is a schematic diagram of the connection structure between the limiting rod and the film applicator provided in an embodiment of the present invention;

[0024] Figure 4 This is a cross-sectional structural schematic diagram provided for another embodiment of the present invention;

[0025] Figure 5 for Figure 4 Enlarged schematic diagram of the local structure at point B;

[0026] Figure 6 This is a schematic diagram of the connection structure between the limiting rod and the film applicator provided in another embodiment of the present invention;

[0027] Figure 7 An exploded view of the limiting rod and the film applicator provided in another embodiment of the present invention;

[0028] Figure 8 This is a schematic diagram of the connection structure between the limiting rod and the film applicator provided in another embodiment of the present invention;

[0029] Figure 9 This is a top view of the limiting rod and film applicator provided in another embodiment of the present invention;

[0030] Figure 10 This is a partial cross-sectional structural schematic diagram provided for another embodiment of the present invention.

[0031] Explanation of reference numerals in the attached figures:

[0032] 1. Shell; 2. Tube sheet; 3. Evaporation tube; 4. Spacer plate; 5. Film distributor; 501. Spherical part; 502. Frustum part; 6. Inclined section; 7. Gap; 8. Limiting rod; 9. Limiting hole; 10. Inclined groove; 11. Transmission rod; 12. Spreading rod; 13. Liquid inlet; 14. Steam inlet; 15. Locking groove; 16. Evaporation chamber; 17. First side; 18. Second side. Detailed Implementation

[0033] To enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings.

[0034] In the description of this invention, it should be understood that, Figure 5 The orientation of the spacer plate 4 relative to the tube plate 2 is upward, and vice versa. The terms "center", "length", "width", "degree", "upper", "lower", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting the present invention.

[0035] Reference Figure 1-10 The present invention provides a silicon carbide thin film evaporator, including a shell 1 and a tube sheet 2 disposed inside the shell 1. Evaporation tubes 3 are disposed on the tube sheet 2, and a spacer plate 4 is also disposed inside the shell 1.

[0036] A film distributor 5 is slidably disposed on the spacer plate 4, and the film distributor 5 extends into the interior of the evaporation tube 3. An inclined section 6 is disposed inside the evaporation tube 3. There is a gap 7 between the film distributor 5 and the inclined section 6 that allows the liquid film to pass through. The size of the gap 7 is adjusted based on the distance between the film distributor 5 and the inclined section 6.

[0037] Specifically, the shell 1 is a vertically arranged tank-like structure with an evaporation chamber 16 inside. It has a liquid inlet 13 at the top and a steam inlet 14 on the side, which is connected to a fan or other gas supply components. Multiple evaporation tubes 3 are evenly arranged on the tube sheet 2. The evaporation tubes 3 are preferably made of a thermally conductive material. The specific evaporation process is as follows: liquid is added into the evaporation chamber 16 through the liquid inlet 13, preferentially falling onto a distribution plate (not shown). The holes on the distribution plate are staggered from the inlets of the evaporation tubes 3, and the liquid flows through the holes on the distribution plate. The liquid flows downwards to the surface of tube sheet 2, and finally enters the evaporator tube 3. It flows downwards along the inner wall of the evaporator tube 3, forming a thin film on the inner wall. Steam is then injected into the evaporation chamber 16 through the gas supply assembly. The heat provided by the steam is used to concentrate the liquid. This is existing technology and will not be elaborated further. One of the core innovations of this invention is that an inclined section 6 is provided inside the evaporator tube 3. The inclined section 6 is located at the position where the evaporator tube 3 overlaps with the tube sheet 2, and the inner diameter of the inclined section 6 is arranged sequentially from top to bottom. To reduce the size of the liquid film, the liquid film distributor 5 is preferably frustum-shaped, meaning its radial dimension increases from top to bottom. The distributor 5 is coaxially arranged with the evaporator tube 3, and there is an annular gap 7 between the distributor 5 and the inclined section 6 for the liquid film to pass through. This arrangement ensures that after the liquid enters the evaporator tube 3 from the surface of the tube sheet 2, it slides down the inner wall of the evaporator tube 3. Some of the liquid flowing to the outer circumference of the distributor 5 will flow back down the inner wall of the evaporator tube 3 along the distributor 5, and finally down the gap between the distributor 5 and the inclined section 6. The liquid flows down through the gap 7 to form a uniform liquid film. However, the amount of liquid injected is affected by external factors and cannot be controlled to a completely constant value. Therefore, the size of the gap 7 can be adjusted by controlling the distance between the film distributor 5 and the inclined section 6 through a linear reciprocating drive component such as an electric push rod. That is, when the amount of liquid injected is small, the film distributor 5 is controlled to move downward, and the gap 7 becomes smaller. When the amount of liquid injected is large, the film distributor 5 is controlled to move upward, and the gap 7 becomes larger, so that the film distributor 5 can adapt to different amounts of liquid injected.

[0038] Preferably, the top of the evaporator tube 3 is higher than the upper surface of the tube sheet 2. This allows the liquid to overflow into the evaporator tube 3 after falling onto the tube sheet 2, thereby improving the film distribution effect.

[0039] Preferably, the radial dimension of the top of the film-covering device 5 is greater than the radial dimension of the inclined section 6. Specifically, the film-covering device 5 includes a spherical part 501 and a frustum-shaped part 502, with the spherical part 501 located above the frustum-shaped part 502. The radial dimension of the spherical part 501 at its maximum position is greater than the radial dimension of the inclined section 6 at its maximum position. The purpose of this arrangement is that when no liquid is injected into the evaporator, the spherical part 501 abuts against the inner edge of the end of the inclined section 6, which can seal the top of the evaporation tube 3. This prevents dust from entering the evaporation tube 3 from the end during evaporator shutdown, thereby minimizing the possibility of scaling inside the evaporation tube 3.

[0040] As an alternative to the aforementioned electric actuator controlling the vertical movement of the film distributor 5, the film distributor 5 has a hollow structure. This design allows the hollow structure of the film distributor 5 to float on the surface of the liquid under buoyancy, and to adjust its position according to changes in the liquid level. Specifically, when the liquid level rises, indicating an increase in the liquid injection volume, the film distributor 5 moves upward, causing its bottom frustum 502 to move upward, increasing the gap 7 to accommodate a larger injection volume into the evaporation chamber 16. Conversely, when the liquid level falls, indicating a smaller injection volume, the film distributor 5 moves downward, causing its bottom frustum 502 to move downward, decreasing the gap 7 to accommodate a smaller injection volume into the evaporation chamber 16. This allows the film distributor 5 to adaptively adjust the size of the gap 7 according to changes in the liquid level.

[0041] Furthermore, a limiting rod 8 is fixedly connected to the tube sheet 2, and a limiting hole 9 adapted to the limiting rod 8 is provided on the film distributor 5. The limiting rod 8 and the limiting hole 9 are slidably and sealingly connected. Specifically, the limiting rod 8 is preferably a cylindrical rod, which is fixed to the lower surface of the tube sheet 2, and there are multiple rods. Multiple film distributors 5 are arranged one-to-one with multiple evaporation tubes 3. Correspondingly, the limiting hole 9 is preferably a circular through hole adapted to the limiting rod 8. The purpose of this arrangement is to limit the horizontal direction of the film distributor 5 under the sliding connection between the limiting rod 8 and the limiting hole 9, so that the film distributor 5 can only move in the vertical direction along the limiting rod 8, thereby improving the stability of the film distributor 5 during the lifting process.

[0042] In a preferred embodiment of the present invention, the film distributor 5 is equipped with a sensor (not shown) for detecting the moving distance of the film distributor 5. Specifically, the sensor can be a displacement sensor or an infrared sensor, and the sensor is electrically connected to the gas supply assembly. It can be mounted on the top of the film distributor 5 to obtain the moving distance of the film distributor 5. There should be no less than one sensor, and preferably four. The four sensors are arranged in a rectangular pattern on the four film distributors 5. When the sensor detects that the film distributor 5 moves upward, it indicates that the liquid injection volume has increased. At this time, the liquid film thickness on the inner wall of the evaporation tube 3 also increases. Therefore, it is necessary to control the gas supply assembly to provide more steam to increase the heating of the liquid film. Conversely, when the sensor detects that the film distributor 5 moves downward, it indicates that the liquid injection volume has decreased. At this time, the liquid film thickness on the inner wall of the evaporation tube 3 also decreases. Therefore, it is necessary to control the gas supply assembly to provide less steam to complete the heating of the liquid film, thereby avoiding the occurrence of "dry wall" (i.e., the phenomenon of crystallization on the inner wall of the evaporation tube 3 after the liquid is overheated).

[0043] Furthermore, the limiting rod 8 is equipped with a swirling assembly for driving the film distributor 5 to rotate. Specifically, the swirling assembly can be a structure such as a motor to provide rotational force. During the film distribution process, it drives the liquid to rotate slightly, creating a spiral downward flow effect, thereby improving the film distribution effect.

[0044] As an alternative to the aforementioned motor-driven film distributor 5 rotation, the vortex assembly includes an inclined groove 10 formed on the limiting rod 8, and a transmission rod 11 adapted to the inclined groove 10 is formed inside the limiting hole 9. The transmission rod 11 is slidably connected to the inclined groove 10. Specifically, the transmission rod 11 is fixed to the inner circumferential surface of the limiting hole 9, and there are two of them. The two transmission rods 11 are symmetrically arranged about the central axis of the limiting hole 9. The inclined groove 10 is formed on the outer circumferential surface of the limiting rod 8, and the inclined groove 10 is not parallel to the central axis of the limiting rod 8 (e.g., ...). Figure 7 As shown, two inclined grooves 10 are also provided, and the two inclined grooves 10 are respectively arranged with respect to the two transmission rods 11. The purpose of this arrangement is that during the lifting and lowering of the film spreader 5, the transmission rods 11 will slide along the inclined grooves 10. Since the inclined grooves 10 and the central axis of the limiting rod 8 are not parallel, the film spreader 5 will be driven to rotate passively under the limiting effect of the inclined grooves 10 and the transmission rods 11. After the film spreader 5 has finished lifting and lowering, it will rise and fall slightly under the action of liquid flow. This slight rise and fall will drive the film spreader 5 to rotate slightly, thereby improving the film spreading effect.

[0045] It should be noted that rapid liquid distribution on the surface of tube sheet 2 is particularly important in the initial stage of liquid injection or when abnormal conditions such as overpressure and overflow mentioned in authorization announcement number CN217472729U occur. In order to accelerate the liquid distribution speed on the surface of tube sheet 2, as another embodiment of the present invention, the film distributor 5 is provided with a liquid distribution assembly for spreading the liquid on the surface of tube sheet 2; the liquid distribution assembly includes a spreading rod 12 fixed to the film distributor 5. Specifically, in this embodiment, the top of the evaporator tube 3 is on the same horizontal plane as the upper surface of the tube sheet 2. The spreading rod 12 is a solid structure and is arranged radially along the film spreader 5. When the film spreader 5 floats on the liquid surface, part of the film spreader 5 will be located inside the liquid. The purpose of this arrangement is that when the liquid is first injected or when there is an abnormal overpressure current, the liquid surface will change significantly. At this time, the film spreader 5 will rise and fall, and during this period, the film spreader 5 will rotate horizontally, which will drive the spreading rod 12 to rotate synchronously, so that the spreading rod 12 has a stirring effect on the upper liquid surface, thereby accelerating the liquid distribution on the surface of the tube sheet 2.

[0046] Preferably, there are three paving rods 12, and the three paving rods 12 are arranged in an array on the film spreader 5. The three paving rods 12 can increase the leveling range of the paving rods 12, thereby further accelerating the liquid distribution speed on the surface of the tube sheet 2.

[0047] In another embodiment of the present invention, the paving rod 12 is arranged at an angle. Specifically, this angled arrangement means that the paving rod 12 is no longer arranged along the radial direction of the film spreader 5, but rather at a certain angle to the radial direction of the film spreader 5, preferably 45°. Furthermore, by controlling the inclination direction of the inclined groove 10, when the film spreader 5 moves upward, it drives the paving rod 12 to rotate clockwise around its central axis (i.e., as shown in the image). Figure 9 The film spreader 5 rotates clockwise, and when it moves downward, it drives the paving rod 12 to rotate counterclockwise around its central axis (i.e., as shown in the image). Figure 9The counterclockwise direction (as shown in the image) is configured such that, for ease of description, the surface of the paving rod 12 closest to the central axis of the film spreader 5 is designated as the first side surface 17, and the surface of the paving rod 12 furthest from the central axis of the film spreader 5 is designated as the second side surface 18. Regarding the operation of one of the film spreaders 5, when the film spreader 5 moves upward, that is, the liquid at the location of the film spreader 5 increases, causing the film spreader 5 to move upward and drive the paving rod 12 to rotate clockwise. Because the paving rod 12 is arranged at an angle, the liquid will pass through the second side surface 18 of the paving rod 12. 8. The liquid near the film spreader 5 is pushed away from the film spreader 5 to avoid excessive liquid in some areas. When the film spreader 5 moves downward, the liquid at the position of the film spreader 5 decreases, causing the film spreader 5 to move downward and drive the paving rod 12 to rotate counterclockwise. Since the paving rod 12 is arranged at an angle, the liquid near the film spreader 5 is pushed closer to the film spreader 5 through the first side 17 of the paving rod 12 to avoid insufficient liquid in some areas, thereby improving the liquid distribution effect.

[0048] In another embodiment of the present invention, the transmission rod 11 is an elastic telescopic rod, and the inclined groove 10 has a locking groove 15 adapted to the transmission rod 11. The locking groove 15 is located on the movement stroke of the transmission rod 11. Specifically, the elastic telescopic rod consists of two sections that slide against each other, and an elastic structure such as a spring is provided between the two ends. When the film distributor 5 is normally raised and lowered, the spring inside the transmission rod 11 is in a compressed state, so that the end of the elastic telescopic rod generates a resisting force against the inner wall of the inclined groove 10. The end of the transmission rod 11 is preferably arc-shaped, and the locking groove 15 is also preferably arc-shaped. With this arrangement, during normal evaporation, the transmission rod 11 will slide inside the inclined groove 10, but the height of the liquid level rise is not enough for the transmission rod 11 to coincide with the locking groove 15. When there is a blockage at the evaporator inlet or the flow is not smooth, the liquid on the surface of the tube sheet 2 will increase abnormally, which will cause the film distributor 5 to move to a higher position. In this embodiment, the sensor can be connected to an alarm structure such as a buzzer (also When the sensor detects a large upward displacement of the film-covering device 5, it will trigger an alarm to indicate that the evaporator needs maintenance. When the film-covering device 5 drives the transmission rod 11 to align with the locking groove 15, the spring force of the transmission rod 11 is released, allowing the transmission rod 11 to engage with the locking groove 15. At this time, the transmission rod 11 provides a flexible fixing effect on the film-covering device 5, meaning that the spherical part 501 of the film-covering device 5 is suspended above the opening of the evaporator tube 3, facilitating the cleaning of the opening of the evaporator tube 3. After maintenance is completed, since the end of the transmission rod 11 is preferably arc-shaped and the locking groove 15 is also preferably arc-shaped, a downward force can be applied to the film-covering device 5 manually, allowing the end of the transmission rod 11 to be pulled out of the locking groove 15, thus resetting the transmission rod 11.

[0049] The foregoing has only described certain exemplary embodiments of the present invention by way of illustration. Undoubtedly, those skilled in the art can modify the described embodiments in various ways without departing from the spirit and scope of the present invention. Therefore, the foregoing drawings and descriptions are illustrative in nature and should not be construed as limiting the scope of protection of the claims of the present invention.

Claims

1. A silicon carbide thin-film evaporator, comprising a shell and a tube sheet disposed inside the shell, characterized in that, An evaporator tube is provided on the tube sheet, and a spacer plate is also provided inside the shell; A film distributor is slidably disposed on the fixed-distance plate, and the film distributor extends into the interior of the evaporation tube. An inclined section is provided inside the evaporation tube, and there is a gap between the film distributor and the inclined section that allows the liquid film to pass through. The size of the gap is adjusted based on the distance between the film distributor and the inclined section.

2. The silicon carbide thin-film evaporator according to claim 1, characterized in that, The top of the evaporator tube is higher than the upper surface of the tube sheet.

3. A silicon carbide thin-film evaporator according to claim 1, characterized in that, The membrane applicator has a hollow structure.

4. A silicon carbide thin-film evaporator according to claim 1, characterized in that, A limiting rod is fixedly connected to the tube sheet, and a limiting hole adapted to the limiting rod is provided on the film applicator. The limiting rod is slidably connected to the limiting hole.

5. A silicon carbide thin-film evaporator according to claim 1, characterized in that, The radial dimension of the top of the film applicator is greater than the radial dimension of the inclined section.

6. A silicon carbide thin-film evaporator according to claim 1, characterized in that, The film applicator is equipped with a sensor for detecting the moving distance of the film applicator.

7. A silicon carbide thin-film evaporator according to claim 4, characterized in that, The limiting rod is equipped with a swirl assembly for driving the film distributor to rotate.

8. A silicon carbide thin-film evaporator according to claim 7, characterized in that, The swirl assembly includes an inclined groove formed on the limiting rod, and a transmission rod adapted to the inclined groove is formed inside the limiting hole, and the transmission rod is slidably connected to the inclined groove.

9. A silicon carbide thin-film evaporator according to claim 7, characterized in that, The membrane spreader is equipped with a liquid distribution assembly for spreading the liquid on the surface of the tube sheet.

10. A silicon carbide thin-film evaporator according to claim 9, characterized in that, The liquid distribution assembly includes a spreading rod fixed to the film distributor.

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