Flash evaporator with top condenser

Abstract

The utility model discloses a flash evaporator with a top condenser. Comprising an upper section, a lower section and a transition section connected between the upper section and the lower section, the diameter of the upper section is smaller than that of the lower section, and the ratio of the diameter of the upper section to the diameter of the lower section is about 1: 1.5-1: 3. The flash evaporator is simple and compact in structure, the U-shaped tube heat exchanger can be integrally drawn out, and manufacturing is facilitated. The circular baffle plate and the cone seal form an annular flow channel, 360-degree air inflow enables air inflow of the condenser to be even, no dead zone exists in the heat exchange pipe, the heat exchange efficiency is improved, and the operation cost is reduced. The conical seal or the elliptical seal head of the flash evaporator forms integral equipment, so that the occupied area of the equipment is reduced. Meanwhile, the ratio of the length to the diameter of the barrel of the flash evaporation part is controlled to be 1: 1-2: 1, heat interference of the two parts is reduced, and the occupied area of equipment is reduced.

Description

Technical Field

[0001] The utility model relates to the field of reactor design, in particular to a flash evaporator with a top condenser. Background Art

[0002] In the field of chemical engineering, especially in the production of synthetic fibers, caprolactam is an important chemical. Typically, caprolactam needs to be concentrated and purified through specific processes. Flash evaporation is a commonly used process that can be used to concentrate and purify caprolactam. During the flash evaporation process, the pressure of a liquid mixture under high temperature and high pressure is suddenly reduced, causing part of the solvent to quickly vaporize, thereby concentrating the solute. In the field of energy-saving technology, how to efficiently utilize energy and reduce energy consumption is an important research direction. In the field of chemical engineering, energy-saving technology can be applied to various processes to improve energy utilization efficiency and reduce operating costs. In the field of reactor design, the design of the reactor directly affects the efficiency and energy consumption of the process. Reasonable reactor design can improve the efficiency of the process, reduce energy consumption, and reduce operating costs.

[0003] Figure 1 This is a schematic diagram of the structure of a prior art device. A steam jet pump generates vacuum, flashing a 99%wt aqueous solution of caprolactam within a flash tank. The flash vapor is then pumped through the steam jet pump into a subsequent condenser for condensation. 99.99%wt caprolactam is obtained at the bottom of the tank. The prior art solution primarily utilizes a flash evaporator and a steam jet pump to concentrate and purify the caprolactam. During the flash evaporation process, the pressure of the high-temperature, high-pressure liquid mixture is suddenly reduced, causing some of the solvent to rapidly vaporize, thereby concentrating the solute. The vaporized solvent is then removed by the steam jet pump, achieving the desired concentration and purification.

[0004] However, existing technical solutions present several challenges. First, because the large amount of steam generated during the flash evaporation process removes a significant amount of heat, a large number of cold sources are required to condense this steam, resulting in significant energy consumption and high operating costs. Second, in existing technical solutions, the heat removed by the flash steam and the bulky condenser equipment require high steam jet pump capacity, large pipeline dimensions, a large floor space, and high construction investment. These issues limit the application and development of existing technical solutions. Utility Model Content

[0005] The present invention aims to improve upon the shortcomings of the prior art and provides a flash evaporator with a top condenser, which improves heat utilization efficiency, reduces energy consumption, reduces the size and floor space of the equipment, reduces construction investment, reduces the capacity requirements of the steam jet pump, and improves the reliability and economy of the equipment. The present invention is achieved through the following technical solutions:

[0006] The utility model discloses a flash evaporator with a top condenser, which comprises a flash tank, a tank top condenser arranged at the upper part of the flash tank, and a condensate collector located below the tank top condenser. The flash tank comprises an upper section, a lower section and a transition section connecting the upper section and the lower section. The diameter of the upper section is smaller than that of the lower section, and the ratio of the diameter of the upper section to the diameter of the lower section is approximately 1:1.5-1:3. A flash gas outlet is provided on the side wall of the upper section, a caprolactam inlet is provided on the side wall of the lower section, a caprolactam outlet is provided on the bottom of the lower section, a condensate outlet connected to the condensate collector is further provided on the side wall of the lower section, and the tank top condenser is sealed to the upper section.

[0007] As a further improvement, the transition section of the present invention is a conical seal or an elliptical seal head. As a further improvement, the condenser of the present invention is a U-tube heat exchanger, comprising an upper tube box, a refrigerant inlet and refrigerant outlet opened above the tube box, a tube sheet sealed to the lower port of the tube box, and U-tubes fixed to the tube sheet, with the periphery of the tube sheet sealed to the opening of the upper section of the flash evaporator.

[0008] As a further improvement, the U-shaped tube of the present invention is arranged in the center and fully occupies the inner cavity of the upper section.

[0009] As a further improvement, the ratio of the length to the diameter of the cylinder of the lower section described in the present invention is between 1:1 and 2:1.

[0010] As a further improvement, the outer surface of the lower section of the present invention is provided with a heating coil and / or the outer surface of the bottom of the lower section is provided with a heating jacket.

[0011] As a further improvement, the U-shaped tube of the condenser described in the present invention is provided with a support plate, an arched baffle and a circular baffle in sequence from top to bottom, and the arched baffles are respectively arranged on different planes of the upper section.

[0012] As a further improvement, the circular baffles described in the present invention are located in the transition section or below the transition section, and flow channels are formed between the circular baffles and the inner wall of the flash evaporator, and between each arched baffle and the support plate.

[0013] As a further improvement, each baffle described in the utility model includes a baffle tube hole for passing the heat exchange tube, the baffle tube hole is elliptical, square, triangular or polygonal, the cross-section of the baffle tube hole is larger than the cross-section of the heat exchange tube, and a condensate flow channel is formed between the heat exchange tube and the baffle tube hole. There are 2-12 intersection points between the cross-section of the heat exchange tube and the cross-section of the baffle tube hole.

[0014] As a further improvement, the condensate collector of the present invention is U-shaped or Y-shaped corresponding to the shape of the bottom end of the U-shaped tube, and the distance between the condensate collector and the bottom end of the U-shaped tube is 10-200 mm.

[0015] The beneficial effects of the utility model are as follows:

[0016] 1) Because the large amount of steam generated during the flash evaporation process carries away a large amount of heat, a large amount of cold source is required to condense the steam, resulting in very high energy consumption and high operating costs. This technical solution improves heat utilization efficiency and reduces energy consumption by optimizing the design of the flash evaporator and condenser.

[0017] 2) The heat removed by the flash vapor and the condenser equipment are bulky, requiring high steam jet pump capacity, large pipeline dimensions, large floor space, and high construction investment. This technical solution reduces the size and floor space of the equipment and reduces construction investment by optimizing the design of the flash evaporator and condenser.

[0018] 3) Due to the heat removed by the flash vapor and the large size of the condenser equipment, the steam jet pump capacity requirements are high, resulting in high equipment costs and difficult maintenance. This technical solution reduces the steam jet pump capacity requirements by optimizing the design of the flash evaporator and condenser, improving the reliability and cost-effectiveness of the equipment.

[0019] 4) The flash evaporator adopts a U-tube heat exchanger with the cold source entering and exiting from the top, which realizes the complete separation of the cold zone and the hot zone, reduces interference and improves energy utilization.

[0020] 5) A heating coil or jacket is installed at the bottom of the flash evaporator to maintain the temperature inside the tank and improve energy utilization efficiency.

[0021] 2. Reduce operating costs.

[0022] 6) The flash evaporator of this utility model has a simple and compact structure, and the U-tube heat exchanger can be withdrawn as a whole, facilitating manufacturing. The circular baffles and conical seals form an annular flow channel, and the 360-degree air intake ensures uniform air flow to the condenser. The heat exchange tubes have no dead zones, improving heat exchange efficiency and reducing operating costs.

[0023] 7) The flash evaporator's conical seal or elliptical head forms an integrated unit, reducing the equipment footprint. Furthermore, the flash evaporator's cylinder length-to-diameter ratio is controlled between 1:1 and 2:1, minimizing heat interference between the two sections and reducing the equipment footprint.

[0024] 8) Improved heat exchange efficiency: The flash evaporator's arcuate baffles are spaced apart in different planes. Combined with the support plates and circular baffles, the design creates a flow path that achieves a favorable gas flow pattern and improves heat exchange efficiency. The circular baffles and conical seals form an annular flow path, allowing for 360-degree airflow, ensuring uniform airflow to the condenser and eliminating dead zones in the heat exchange tubes, thus improving heat exchange efficiency.

[0025] 9) The U-bend of the flash evaporator of the present invention should be inserted to the transition section or below. The condensate collector is U-shaped or Y-shaped corresponding to the shape of the bottom end of the U-shaped tube, and its size is slightly larger than the U-bend, which is beneficial to reduce airflow interference and improve the collection efficiency of condensate.

[0026] 10) This technical solution has broad application prospects in chemical engineering, energy-saving technology, and reactor design, with significant market demand and excellent commercial value. By optimizing its design and structure, the flash evaporator of this utility model reduces heat loss from steam, lowers energy consumption, and improves energy efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a structural diagram of a prior art device;

[0028] Figure 2 This is a simplified structural diagram of the device of the utility model;

[0029] Figure 3 This is a schematic diagram of the specific structure of the device of the utility model;

[0030] Figure 4 This is a structural diagram of the baffle of the utility model.

[0031] In the figure: 1 is the caprolactam inlet, 2 is the caprolactam outlet, 3 is the flash gas outlet, 4 is the steam jet pump, 5 is the subsequent condenser, 6 is the flash tank, 7 is the condensate outlet, 8 is the condensate collector, 9 is the tank top condenser, 10 is the lower section, 11 is the transition section, 12 is the upper section, 13 is the refrigerant inlet, 14 is the refrigerant outlet, 15 is the support plate, 16 is the bow-shaped baffle, 17 is the circular baffle, 18 is the heating coil, 19 is the heating jacket, 21 is the condensate flow channel, 22 is the heat exchange tube, and 23 is the baffle tube hole. DETAILED DESCRIPTION

[0032] The technical solution of the present invention will be further described below with reference to the accompanying drawings through specific embodiments:

[0033] Figure 2 This is a simplified structural diagram of the device of the utility model; Figure 3 It is a schematic diagram of the specific structure of the device of the utility model.

[0034] Example 1

[0035] The utility model discloses a flash evaporator with a top condenser 9, comprising a flash tank, a tank top condenser 9 disposed in the upper portion of the flash tank, and a condensate collector located below the tank top condenser 9. The flash tank comprises an upper section 12, a lower section 10, and a transition section 11 connecting the upper section 12 and the lower section 10. The diameter of the upper section 12 is smaller than that of the lower section 10, and the ratio of the diameter of the upper section 12 to the diameter of the lower section 10 is approximately 1:2. A flash gas outlet 3 is formed on the side wall of the upper section 12, a caprolactam inlet 1 is formed on the side wall of the lower section 10, a caprolactam outlet 2 is formed at the bottom of the lower section 10, and a condensate outlet connected to the condensate collector is further formed on the side wall of the lower section 10. The tank top condenser 9 and the upper section 12 are sealed. The flash gas outlet 3 is connected to a steam jet pump 4, which is connected to a subsequent condenser 5.

[0036] Flash evaporation occurs at the bottom, condensation occurs at the top, and the intermediate condensate is collected and produced. A 99% aqueous caprolactam solution enters the flash tank from the lower middle portion for flash evaporation. The water vaporizes and flows upward, while the caprolactam, as a liquid, flows downward and is produced through the outlet, yielding 99.99% caprolactam. This process achieves flash evaporation. The flash vapor then flows upward and condenses through the condenser 9 at the top of the flash evaporator. The condensate is then produced through the central liquid collection tray. This process condenses the flash vapor and reduces gas volume.

[0037] The larger diameter at the bottom forms the flash evaporation area, where a larger diameter or volume is beneficial for flash evaporation. The smaller diameter at the top is primarily to accommodate condenser 9. On the one hand, the baffles provide lateral support for condenser 9, and on the other hand, the smaller diameter allows for a higher flow rate to facilitate heat exchange and improve the efficiency of condenser 9. A conical seal or elliptical head is then used to form a single integrated device.

[0038] The transition section 11 is a cone seal. The condenser 9 is a U-tube heat exchanger, comprising an upper tube box, a refrigerant inlet 13 and refrigerant outlet 14 opened above the tube box, a tube sheet sealed to the lower port of the tube box, and U-tubes fixed to the tube sheet. The periphery of the tube sheet is sealed to the opening of the flash evaporator upper section 12.

[0039] The U-tube is centrally located, completely filling the interior cavity of the upper section 12. The lower section 10 has a length-to-diameter ratio of 1:1. A heating coil 18 is installed on the outer surface of the lower section 10, and a heating jacket 19 is installed on the outer surface of the bottom of the lower section 10. Because the upper portion of the flash evaporator requires condensation, while the lower portion requires insulation for flash evaporation, a larger aspect ratio is beneficial for minimizing thermal interference between the two sections. However, a too large aspect ratio is detrimental to the smooth progress of the flash evaporation and gas-liquid separation processes. The heating coil 18 or jacket is installed on the lower portion of the shell primarily to maintain the internal temperature, as flash evaporation requires a certain temperature. The lack of a heating coil 18 or jacket at the top is primarily due to the fact that the top portion is designed for condensation and does not require additional heat input. The structure is simple and compact, and the U-tube heat exchanger can be withdrawn as a whole, facilitating manufacturing. The centrally located U-tube eliminates eccentric loads, ensuring good structural stability. The vertical heat exchange tubes 22 can be fully utilized as condensate flow paths, improving condensate recovery efficiency. The cooling source is pushed in and out from the top to achieve complete separation of the cold zone and the hot zone, reduce interference and improve energy utilization.

[0040] The U-shaped tubes of the condenser 9 are sequentially arranged, from top to bottom, with support plates 15, arched baffles 16, and circular baffles 17. The arched baffles 16 are positioned on different planes of the upper section 12, while the circular baffles 17 are located at or below the transition section 11. A flow channel is formed between the circular baffles 17 and the inner wall of the flash evaporator, and between each arched baffle 16 and the support plates 15. The circular baffles 17 and the conical seals form an annular flow channel, with a high-velocity area above and a low-velocity area below. This means that the U-bend should be a low-velocity area, which helps reduce airflow interference and improve condensate collection efficiency. Similarly, the shape of the intermediate liquid collection device is consistent with the U-bend, and the spacing between the device and the U-bend is controlled to reduce airflow interference and improve condensate collection efficiency. The circular baffles 17 and the conical seals form an annular flow channel, providing 360-degree airflow, ensuring uniform airflow to the condenser 9 and eliminating dead zones in the heat exchange tubes 22, thereby improving heat exchange efficiency. The asymmetrical arrangement of the arcuate baffles 16 is mainly to obtain a good gas flow pattern and improve heat exchange efficiency. The support plate 15 mainly plays a supporting role to prevent the pipeline from vibrating.

[0041] Each baffle plate in this utility model includes a baffle hole 23 through which the heat exchange tube 22 passes. The baffle hole 23 is an elliptical shape that is tangent to the heat exchange tube 22. The cross-section of the heat exchange tube 22 and the baffle hole 23 have two tangent points. The cross-section of the baffle tube 23 is larger than that of the heat exchange tube 22. A condensate flow channel 21 is formed between the heat exchange tube 22 and the baffle hole 23. This not only supports the tube bundle but also provides a flow path for the condensate. The condensate collector is U-shaped, corresponding to the bottom end of the U-shaped tube, and the distance between the condensate collector and the bottom end of the U-shaped tube is 50 mm.

[0042] Example 2

[0043] The utility model discloses a flash evaporator with a top condenser 9. The ratio of the diameter of the upper section 12 to the diameter of the lower section 10 is approximately 1:3. The transition section 11 is an elliptical end cap. The length-to-diameter ratio of the lower section 10 is 2:1. A heating coil 18 is provided on the outer surface of the lower section 10. The baffle holes 23 are triangular in shape, with three points of contact with the heat exchange tubes 22. The condensate collector is Y-shaped, corresponding to the shape of the bottom end of the U-shaped tube. The distance between the condensate collector and the bottom end of the U-shaped tube is 200 mm. The remaining technical features are the same as those of Example 1.

[0044] Those skilled in the art will understand that the above are merely preferred examples of the utility model and are not intended to limit the utility model. Although the utility model has been described in detail with reference to the above examples, those skilled in the art will still be able to modify the technical solutions described in the above examples or replace some of the technical features therein with equivalents. Any modifications, equivalents, etc. made within the spirit and principles of the utility model shall be included in the scope of protection of the utility model.

Claims

1. A flash evaporator with a top condenser, characterized in that: The invention comprises a flash tank, a tank top condenser arranged in the upper part of the flash tank, and a condensate collector located below the tank top condenser. The flash tank comprises an upper section, a lower section and a transition section connecting the upper section and the lower section. The diameter of the upper section is smaller than the diameter of the lower section. The ratio of the diameter of the upper section to the diameter of the lower section is approximately 1:1.5-1:

3. A flash gas outlet is provided on the side wall of the upper section, a caprolactam inlet is provided on the side wall of the lower section, a caprolactam outlet is provided on the bottom of the lower section, a condensate outlet connected to the condensate collector is also provided on the side wall of the lower section, and the tank top condenser is sealed to the upper section.

2. The flash evaporator with a top condenser according to claim 1, characterized in that: The transition section is a cone seal or an elliptical head.

3. The flash evaporator with a top condenser according to claim 2, characterized in that: The condenser is a U-tube heat exchanger, which includes an upper tube box, a refrigerant inlet and a refrigerant outlet opened above the tube box, a tube sheet sealed with the lower port of the tube box, and a U-shaped tube fixed to the tube sheet. The periphery of the tube sheet is sealed with the opening of the upper section of the flash evaporator.

4. The flash evaporator with a top condenser according to claim 3, characterized in that: The U-shaped tube is arranged in the center and occupies the entire inner cavity of the upper section.

5. The flash evaporator with a top condenser according to claim 1, 2, 3 or 4, characterized in that: The ratio of the length to the diameter of the cylinder of the lower section is between 1:1 and 2:

1.

6. The flash evaporator with a top condenser according to claim 5, characterized in that: The outer surface of the lower section is provided with a heating coil and / or the outer surface of the bottom of the lower section is provided with a heating jacket.

7. The flash evaporator with a top condenser according to claim 6, characterized in that: The U-shaped tube of the condenser is provided with a support plate, an arched baffle and a circular baffle in sequence from top to bottom, and the arched baffles are respectively arranged on different planes of the upper section.

8. The flash evaporator with a top condenser according to claim 7, characterized in that: The circular baffle is located in the transition section or below the transition section. A flow channel is formed between the circular baffle and the inner wall of the flash evaporator, and between each arched baffle and the support plate.

9. The flash evaporator with a top condenser according to claim 1 or 2 or 3 or 4 or 6 or 7 or 8, characterized in that: Each of the baffles includes a baffle tube hole for passing the heat exchange tube. The baffle tube hole is elliptical, square, triangular or polygonal. The cross-section of the baffle tube hole is larger than the cross-section of the heat exchange tube. A condensate flow channel is formed between the heat exchange tube and the baffle tube hole. There is a 2-12 tangent point between the cross-section of the heat exchange tube and the cross-section of the baffle tube hole.

10. The flash evaporator with a top condenser according to claim 9, characterized in that: The condensate collector is in a U-shape or a Y-shape corresponding to the shape of the bottom end of the U-shaped tube, and the distance between the condensate collector and the bottom end of the U-shaped tube is 10-200 mm.

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