A segmented pressure-reducing liquid seal method and system for handling high-temperature feed in a low-temperature evaporator

Abstract

This application belongs to the field of industrial evaporation and concentration technology, specifically a segmented pressure-reducing liquid seal method and system for treating high-temperature feed in a low-temperature evaporator, including the following steps: Step 1, setting a feed inlet at the bottom of a container tank, and connecting the feed inlet to the output end of a first centrifugal pump outside the container tank; Step 2, adding liquid into the container tank so that the liquid level is higher than the height of the feed inlet; Step 3, connecting the top of the container tank to the input end of a vacuum pump to preheat the container tank by reducing pressure; effectively solving the problems of impact on the equipment and steam entrainment caused by feed flash evaporation.

Description

Technical Field

[0001] This application belongs to the field of industrial evaporation and concentration technology, specifically a segmented pressure reduction liquid seal method and system for handling high-temperature feed in a low-temperature evaporator. Background Technology

[0002] In the past, the environmental protection industry used MVR system evaporation, which could reduce energy consumption. However, due to atmospheric pressure evaporation, the boiling point would rise sharply as the concentration of the mother liquor increased, resulting in extremely low heat exchange efficiency in the later stages of evaporation. Even with the mother liquor being recycled, the problem of high water content in the evaporation mother liquor could not be effectively solved, and it could not be applied to heat-sensitive materials.

[0003] With the advent of low-temperature dryers, stored MVR mother liquor has been processed, and low-temperature dryers have gained acceptance. This has led to a demand for directly connecting the MVR mother liquor outlet to the low-temperature dryer to create a continuous process. However, this has also brought about a new problem: flash evaporation. Previously stored MVR mother liquor had been cooled to room temperature due to air cooling, while the MVR mother liquor outlet is a high-temperature material above 90 degrees Celsius. Directly entering the low-temperature evaporator would cause severe flash evaporation, greatly affecting the stable operation of the low-temperature evaporator. Summary of the Invention

[0004] The purpose of this application is to address the shortcomings of existing technologies by designing a segmented pressure reduction liquid seal method and system for handling high-temperature feed in a low-temperature evaporator through a liquid seal preset method, thereby solving the problems of impact on the equipment caused by feed flash evaporation and steam entrainment.

[0005] To achieve the above objectives, the following technical solution is adopted: A segmented pressure-reducing liquid seal method for handling high-temperature feed in a low-temperature evaporator includes the following steps: Step 1: Set a feed inlet at the bottom of the container, and connect the feed inlet to the output end of the first centrifugal pump outside the container; Step 2: Add liquid to the container so that the liquid level is higher than the height of the feed inlet; Step 3: Connect the top of the container to the input of the vacuum pump to preheat the inside of the container by reducing the pressure.

[0006] Preferably, in step two, the distance between the feed inlet and the bottom of the container is 100mm, and the liquid level is 100-150mm above the feed inlet.

[0007] Preferably, step three further includes the following steps: Step three also includes the following steps: Step 1: Use a vacuum pump to evacuate the container to -55kPa, reduce the pumping speed / keep the container without evacuating for a period of time to allow the original liquid to evaporate slowly. When the evaporation is no longer intense, the vacuum level will rise / water production (LS01) is particularly slow, indicating that the liquid in the container has dropped to close to the evaporation temperature of 80 degrees Celsius. Step 2: After the evaporation in the first step is not intense, continue to use a vacuum pump to evacuate the container to -70 kPa. If the evaporation is intense, the vacuum level may decrease, allowing the original liquid to continue to evaporate on its own. If the evaporation is not intense, the vacuum level will increase / water production will be very slow, indicating that the liquid in the container has dropped to the evaporation temperature of 72 degrees Celsius. Maintain the pressure until it is stable. Step 3: After the evaporation in step 2 is no longer intense, use a vacuum pump to evacuate the container to -85 kPa. Continue to reduce the pump's pumping speed / maintain this for a period of time. If the evaporation is intense, the vacuum level in the container will decrease, allowing the original liquid to continue to evaporate on its own. If the evaporation is not intense, the vacuum level in the container will increase / water production will be very slow, indicating that the liquid in the container has now dropped to the evaporation temperature of 58 degrees Celsius. Maintain the pressure until it is stable. Step 4: After the evaporation in step 3 is no longer intense, use a vacuum pump to evacuate the container to -95 kPa and maintain this vacuum level. When water production is particularly slow, it means that the evaporation is already very slow, indicating that the liquid in the container has dropped to an evaporation temperature of about 40 degrees Celsius. This means that the heat from the material during the initial feeding and preheating process has been fully utilized, and preheating is complete.

[0008] Preferably, the internal heating of the container is achieved by a steam jacket on the outer bottom wall of the container.

[0009] Preferably, by installing a stirring shaft inside the container, the original liquid inside the container is fully mixed under the stirring action of the stirring shaft, thereby increasing the heat transfer efficiency.

[0010] Preferably, the steam outlet of the container is connected to a condenser, which cools the steam to form a liquid.

[0011] A system for performing the segmented pressure reduction liquid seal method for treating high-temperature feed in a low-temperature evaporator as described above includes a container tank, a first centrifugal pump, a second centrifugal pump, a first flow meter, a separator, a condenser, a vacuum pump, a second centrifugal pump, a water tank, and a second flow meter. The output end of the first centrifugal pump is connected to the first flow meter, and the output end of the first flow meter is connected to the feed inlet of the container tank, which is located below the container tank. A stirring shaft is provided inside the container tank, and stirring blades are provided on the stirring shaft. The top of the container tank is connected to the input end of the separator, and the output end of the separator is connected to the input end of the condenser. The output end of the condenser is connected to the input end of the vacuum pump through a first branch pipe, and the output end of the vacuum pump is connected to the water tank through a second branch pipe. The outlet of the water tank is connected to the input end of the second centrifugal pump, and the output end of the second centrifugal pump is connected to the input end of the second flow meter. A switch valve is provided between the two ends of the first branch pipe, and a switch valve is also provided between the output end of the first flow meter and the feed inlet of the container tank. A steam jacket is provided on the outer bottom wall of the container tank, and the output end of a steam delivery pipe is connected to the steam jacket.

[0012] Compared with the prior art, the beneficial effects of the technical solution of this application are: This application presents a segmented pressure reduction liquid seal method and system for handling high-temperature feed in a low-temperature evaporator by means of liquid seal preset, which solves the problems of impact on the equipment by feed flash evaporation and steam entrainment. Attached Figure Description

[0013] Figure 1 This is a schematic diagram of the structure of this application.

[0014] The components are as follows: 1. Container tank; 2. Feed inlet; 3. First centrifugal pump; 4. Vacuum pump; 5. Stirring shaft; 6. Condenser; 7. Water tank; 8. Switch valve; 9. Second centrifugal pump; 10. First flow meter; 11. Second flow meter; 12. Separator; 13. First branch pipe; 14. Second branch pipe; 15. Steam jacket; 16. Spiral blade; 17. Stirring blade. Detailed Implementation

[0015] Reference Figure 1 A segmented pressure-reducing liquid seal method for handling high-temperature feed in a low-temperature evaporator includes the following steps: Step 1: Set up an inlet 2 at the bottom of container tank 1, and connect the inlet 2 to the output end of the first centrifugal pump 3 outside container tank 1; the purpose of this setting is to facilitate the delivery of raw liquid into container tank 1 by the first centrifugal pump 3.

[0016] Step 2: Add liquid to container 1 so that the liquid level is higher than the height of the feed inlet 2; after this operation, a liquid seal is formed inside container 1.

[0017] Step 3: Connect the top of container 1 to the input of vacuum pump 4 to preheat the inside of container 1 by reducing pressure. This reduces the pressure inside container 1 via vacuum pump 4, thus allowing evaporation to occur more efficiently. As a preferred embodiment, in step two, the distance between the feed inlet 2 and the bottom of the container 1 is 100mm, and the liquid level is 100-150mm above the feed inlet. This ensures that the feed is isolated from the vacuum system.

[0018] As a preferred embodiment, step three further includes the following steps: Step 1: Use vacuum pump 4 to evacuate the container 1 to -55kPa, reduce the pumping speed / keep the container without evacuating for a period of time to allow the original liquid to evaporate slowly. When the evaporation is not intense, the vacuum level will rise / water production (LS01) is particularly slow, indicating that the liquid in the container has dropped to close to the evaporation temperature of 80 degrees. Step 2: After the first stage of evaporation is not intense, continue to use vacuum pump 4 to evacuate the container 1 to -70kPa. If the evaporation is intense, the vacuum level may decrease, allowing the original liquid to continue to evaporate on its own; if the evaporation is not intense, the vacuum level will increase / water production will be very slow, indicating that the liquid in the container 1 has dropped to the evaporation temperature of 72 degrees, and the pressure is maintained until it is stable. Step 3: After the evaporation in step 2 is no longer intense, use vacuum pump 4 to evacuate the container 1 to -85 kPa, and continue to reduce the pump's pumping speed / maintain this for a period of time. If the evaporation is intense, the vacuum level in container 1 will decrease, allowing the original liquid to continue to evaporate on its own; if the evaporation is not intense, the vacuum level in container 1 will increase / water production will be very slow, indicating that the liquid in container 1 has now dropped to the evaporation temperature of 58 degrees Celsius, and the pressure should be maintained until it is stable. Step 4: After the evaporation in step 3 is no longer intense, use vacuum pump 4 to evacuate the container 1 to -95 kPa and maintain this vacuum level. When water production is particularly slow, it means that the evaporation is already very slow, indicating that the liquid in container 1 has dropped to an evaporation temperature of about 40 degrees Celsius. The heat of the material during the initial feeding and preheating process has been fully utilized, and the preheating is completed.

[0019] As a preferred method, the internal heating of container tank 1 is achieved by a steam jacket on the outer bottom wall of the container tank 1. During the evaporation process, the feed temperature is 90 degrees Celsius. Since the feed inlet is below the liquid surface, a liquid seal is achieved, and direct flash evaporation is not achieved. Instead, heat is transferred to the low-temperature material inside container tank 1 through direct contact heat exchange. During the evaporation process, the amount of water produced every 10 minutes (second flow meter 11) is used to replenish the original liquid (first flow meter 10).

[0020] As a preferred method, by setting a stirring shaft 5 inside the container tank 1, the original liquid inside the container tank is fully mixed under the stirring action of the stirring shaft, thereby increasing the heat transfer efficiency.

[0021] As a preferred embodiment, the steam outlet of the container 1 is connected to a condenser 6, which cools the steam to form a liquid.

[0022] A system for performing the segmented pressure reduction liquid seal method for treating high-temperature feed in a low-temperature evaporator as described above includes a container tank 1, a first centrifugal pump 3, a second centrifugal pump 9, a first flow meter 10, a separator 12, a condenser 6, a vacuum pump 4, a second centrifugal pump 9, a water tank 7, and a second flow meter 11. The output end of the first centrifugal pump 3 is connected to the first flow meter 10, and the output end of the first flow meter 10 is connected to the feed inlet 2 of the container tank 1. The feed inlet 2 is located below the container tank 1. The container tank 1 is equipped with a stirring shaft 5, and the stirring shaft 5 is equipped with stirring blades 17. The top of the container tank 1 is connected to the input end of the separator 12. The output end of 2 is connected to the input end of the condenser 6. The output end of the condenser 6 is connected to the input end of the vacuum pump 4 through the first branch pipe 13. The output end of the vacuum pump 4 is connected to the water tank 7 through the second branch pipe 14. The outlet of the water tank 7 is connected to the input end of the second centrifugal pump 9. The output end of the second centrifugal pump 9 is connected to the input end of the second flow meter 11. A switch valve 8 is provided between the two ends of the first branch pipe 13. A switch valve 8 is also provided between the output end of the first flow meter 10 and the feed inlet 2 of the container tank 1. A steam jacket 15 is provided on the outer bottom wall of the container tank 1. The output end of the steam conveying pipe 16 is connected to the steam jacket 15.

[0023] The steam jacket 15 heats the container tank 1 during the evaporation process to facilitate evaporation. During the preheating stage, flash evaporation may occur due to vacuuming. A spiral blade 16 is installed at the connection pipe between the container tank 1 and the separator 12. If the flash evaporation is intense, the rising airflow velocity is very high, and the spiral blade 16 will also rotate very quickly due to the thrust. It automatically rotates using the thrust of the evaporated steam. The more entrained material it carries, the faster it rotates, and the more entrained material it removes. This can effectively throw large entrained material to the wall and back into the container tank 1.

Claims

1. A segmented pressure-reducing liquid seal method for handling high-temperature feed in a low-temperature evaporator, characterized in that, Includes the following steps: Step 1: Set a feed inlet (2) at the bottom of the container (1) and connect the feed inlet (2) to the output end of the first centrifugal pump (3) outside the container (1); Step 2: Add liquid into container (1) so that the liquid level is higher than the height of the feed inlet (2); Step 3: Connect the top of container (1) to the input end of vacuum pump (4) to preheat the container (1) by depressurization.

2. The segmented pressure reduction liquid seal method for treating high-temperature feed in a low-temperature evaporator according to claim 1, characterized in that, In step two, the distance between the feed inlet (2) and the bottom of the container (1) is 100mm, and the liquid level is 100-150mm higher than the feed inlet.

3. The segmented pressure reduction liquid seal method for treating high-temperature feed in a low-temperature evaporator according to claim 1, characterized in that, Step three also includes the following steps: Step 1: Use vacuum pump (4) to evacuate the container (1) to -55kPa, reduce the pumping speed of vacuum pump / keep it without vacuum for a period of time, let the original liquid evaporate slowly, when the evaporation is not intense, the vacuum degree will rise / water production (LS01) is particularly slow, indicating that the liquid in the tank has dropped to close to the evaporation temperature of 80 degrees. Step 2: After the first step of evaporation is not intense, continue to use vacuum pump (4) to pump the container (1) to -70 kPa. If the evaporation is intense, the vacuum level may decrease, allowing the original liquid to continue to evaporate on its own; if the evaporation is not intense, the vacuum level will increase / water production is very slow, indicating that the liquid in the container (1) has dropped to the evaporation temperature of 72 degrees, and the pressure is maintained until it is stable. Step 3: After the evaporation in step 2 is not intense, use vacuum pump (4) to pump the container (1) to -85 kPa, continue to reduce the pumping speed / maintain for a period of time. If the evaporation is intense, the vacuum level in the container (1) will decrease, allowing the original liquid to continue to evaporate on its own; if the evaporation is not intense, the vacuum level in the container (1) will increase / water production will be very slow, indicating that the liquid in the container (1) has dropped to the evaporation temperature of 58 degrees, and the pressure is maintained until it is stable. Step 4: After the evaporation in step 3 is not intense, the vacuum pump (4) is used to pump the container (1) to -95 kPa and maintain this vacuum. When the water production is particularly slow, the evaporation is already very slow, indicating that the liquid in the container (1) has dropped to the evaporation temperature of about 40 degrees. The heat of the material during the first feeding and preheating process has been fully utilized, and the preheating is completed.

4. The segmented pressure reduction liquid seal method for treating high-temperature feed in a low-temperature evaporator according to claim 3, characterized in that, The internal heating of the container (1) is achieved by a steam jacket on the outer bottom wall of the container (1).

5. The segmented pressure reduction liquid seal method for treating high-temperature feed in a low-temperature evaporator according to claim 3, characterized in that, By setting a stirring shaft (5) inside the container (1), the original liquid inside the container (1) is fully mixed under the stirring action of the stirring shaft, thereby increasing the heat transfer efficiency.

6. The segmented pressure reduction liquid seal method for treating high-temperature feed in a low-temperature evaporator according to claim 4, characterized in that, The steam outlet of the container (1) is connected to a condenser (6), which cools the steam to form a liquid.

7. A system for performing the segmented pressure reduction liquid seal method for processing high-temperature feed in a low-temperature evaporator as described in claim 1, characterized in that, The system includes a container tank (1), a first centrifugal pump (3), a second centrifugal pump (9), a first flow meter (10), a separator (12), a condenser (6), a vacuum pump (4), a second centrifugal pump (9), a water tank (7), and a second flow meter (11). The output end of the first centrifugal pump (3) is connected to the first flow meter (10), and the output end of the first flow meter (10) is connected to the inlet (2) of the container tank (1). The inlet (2) is located below the container tank (1). The container tank (1) is equipped with a stirring shaft (5), and the stirring shaft (5) is equipped with stirring blades (17). The top of the container tank (1) is connected to the input end of the separator (12), and the output end of the separator (12) is connected to the condenser (6). The input end of the condenser (6) is connected to the input end of the vacuum pump (4) through the first branch pipe (13). The output end of the vacuum pump (4) is connected to the water tank (7) through the second branch pipe (14). The outlet of the water tank (7) is connected to the input end of the second centrifugal pump (9). The output end of the second centrifugal pump (9) is connected to the input end of the second flow meter (11). A switch valve (8) is provided between the two ends of the first branch pipe (13). A switch valve (8) is also provided between the output end of the first flow meter (10) and the feed inlet (2) of the container tank (1). A steam jacket (15) is provided on the outer bottom wall of the container tank (1). The output end of the steam conveying pipe (16) is connected to the steam jacket (15).

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