Propylene carbonate system vacuum pump anti-coking device

Abstract

The utility model relates to a propylene carbonate system vacuum pump anti coking device. Its technical scheme is: in the upper end of propylene carbonate vacuum jar is connected the import end of primary roots pump through pipeline and primary filter, the import end of secondary roots pump is connected through pipeline secondary filter two secondary roots pump export end, the import end of screw pump is connected through pipeline and tertiary filter screw pump export end, and the export end is connected exhaust pipeline and silencer. Advantageous effects are: the utility model discloses through using multiple roots screw pump series connection to replace the vacuum unit of the volumetric W pump in parallel, through the compression ratio of each level equipment, calculates the amount of extraction, makes it between mutual matching, can improve the safety of equipment operation and can reduce the vacuum pump load, reduces the equipment and operating temperature, also has increased multistage filter, and regular cleaning can prevent carbonization long time accumulation influence the gas extraction efficiency, avoids causing equipment damage, prolongs equipment use cycle.

Description

Technical Field

[0001] This utility model relates to the field of propylene carbonate production technology, and in particular to an anti-coking device for a vacuum pump in a propylene carbonate system. Background Technology

[0002] Propylene carbonate is an important chemical product. With the development of the lithium battery industry, its usage has been increasing year by year. Propylene carbonate is synthesized by carbon dioxide and propylene oxide under high temperature and high pressure through catalyst catalysis. The product purification stage requires vacuum distillation, and vacuum pumps are used to reduce the system pressure to achieve energy saving. In the vacuum distillation stage, the waste gas and light components in the distillation system are extracted from the top of the column by a vacuum pump. However, since the existing vacuum pumps are vacuum units composed of parallel positive displacement W pumps, the equipment body temperature is high during operation, and the top gas phase carries some organic matter. When heated, it will carbonize and coke on the inner wall of the equipment, causing equipment damage. In severe cases, it will affect the normal production of the unit. Utility Model Content

[0003] The purpose of this invention is to address the aforementioned deficiencies in the existing technology by providing an anti-coking device for a vacuum pump in a propylene carbonate system. This device replaces the parallel positive displacement W pumps with multiple Roots screw pumps connected in series to form a vacuum unit. By calculating the pumping capacity through the compression ratio of each stage of the equipment, the device can be matched with each other, thereby improving the safety of equipment operation, reducing the load on the vacuum pump, lowering the equipment and operating temperature, and extending the service life of the device.

[0004] The present invention relates to a device for preventing coking of a vacuum pump in a propylene carbonate system. The technical solution is as follows: it includes a primary filter (2), a primary Roots pump (3), a secondary filter (4), a secondary Roots pump (5), a tertiary filter (6), a screw pump (7), and a silencer (8). The upper end of the propylene carbonate vacuum tank (1) is connected to the inlet end of the primary Roots pump (3) through a pipeline and the primary filter (2). The outlet end of the primary Roots pump (3) is connected to the inlet end of the secondary Roots pump (5) through a pipeline and the secondary filter (4). The outlet end of the secondary Roots pump (5) is connected to the inlet end of the screw pump (7) through a pipeline and the tertiary filter (6). The outlet end of the screw pump (7) is connected to an exhaust pipeline and a silencer (8).

[0005] Preferably, the compression ratio of the first-stage Roots pump (3) and the second-stage Roots pump (5) is 1:2.

[0006] Preferably, the pumping capacities of the first-stage Roots pump (3), the second-stage Roots pump (5), and the screw pump (7) are 2500L / S, 1200L / S, and 2250M3 / h, respectively.

[0007] Preferably, a first control valve (9) is installed on the pipeline between the upper end of the propylene carbonate vacuum tank (1) and the primary filter (2).

[0008] Preferably, a second control valve (10) is installed on the exhaust line at the outlet of the above-mentioned muffler (8).

[0009] Preferably, the rotors inside the first-stage Roots pump (3), the second-stage Roots pump (5), and the screw pump (7) are all coated with Hastelloy alloy.

[0010] Preferably, a pressure gauge (P) is installed on the upper part of the propylene carbonate vacuum tank (1).

[0011] The beneficial effects of this utility model are as follows: This utility model uses multiple Roots screw pumps connected in series to replace the parallel positive displacement W pumps to form a vacuum unit. By calculating the pumping capacity through the compression ratio of each stage of the equipment, the pumps are matched with each other to form a new type of vacuum pumping unit. This can improve the safety of equipment operation and reduce the load on the vacuum pumps, as well as lower the equipment and operating temperature. In addition, the inner walls of the first-stage Roots pump, the second-stage Roots pump, and the screw pump are coated with an internal spray coating to improve wear resistance and smoothness, preventing organic matter from accumulating on the inner wall surface after coking. The rotors are all coated with Hastelloy material to prevent wear, corrosion, and deformation of internal parts, thus reducing the probability of organic gas phase carbonization and coking. Furthermore, a multi-stage filter is added. Regular cleaning can prevent the long-term accumulation of carbon deposits from affecting the pumping efficiency, avoiding equipment damage, and extending the service life of the equipment. Attached Figure Description

[0012] Figure 1 This is a structural schematic diagram of Embodiment 1 of this utility model; Figure 2 This is a structural schematic diagram of Embodiment 2 of this utility model; In the diagram above: 1. Propylene carbonate vacuum tank; 2. Primary filter; 3. Primary Roots pump; 4. Secondary filter; 5. Secondary Roots pump; 6. Tertiary filter; 7. Screw pump; 8. Silencer; 9. First control valve; 10. Second control valve; 11. Second screw pump. Detailed Implementation

[0013] The preferred embodiments of the present invention will be described below with reference to the accompanying drawings. It should be understood that the preferred embodiments described herein are for illustration and explanation only and are not intended to limit the present invention.

[0014] Example 1, referring to Figure 1The present invention relates to an anti-coking device for a vacuum pump in a propylene carbonate system, comprising a primary filter 2, a primary roots pump 3, a secondary filter 4, a secondary roots pump 5, a tertiary filter 6, a screw pump 7, and a silencer 8. The upper end of the propylene carbonate vacuum tank 1 is connected to the inlet of the primary roots pump 3 via a pipeline and the primary filter 2. The outlet of the primary roots pump 3 is connected to the inlet of the secondary roots pump 5 via a pipeline and the secondary filter 4. The outlet of the secondary roots pump 5 is connected to the inlet of the screw pump 7 via a pipeline and the tertiary filter 6. The outlet of the screw pump 7 is connected to an exhaust pipeline and the silencer 8.

[0015] Among them, the compression ratio of the first-stage Roots pump 3 and the second-stage Roots pump 5 is 1:2. The pumping capacities of the first-stage Roots pump 3, the second-stage Roots pump 5 and the screw pump 7 are 2500L / S, 1200L / S and 2250M3 / h respectively, which meets the mutual matching between the equipment and enables the organic gas to be discharged in time after compression.

[0016] The first control valve 9 is installed on the pipeline between the upper end of the propylene carbonate vacuum tank 1 and the primary filter 2, and the second control valve 10 is installed on the exhaust pipeline at the outlet of the silencer 8 for easy control.

[0017] The rotors inside the aforementioned primary Roots pump 3, secondary Roots pump 5, and screw pump 7 are all coated with Hastelloy alloy to prevent wear, corrosion, and deformation of internal components, thereby reducing the probability of organic gas phase carbonization and coking. In addition, the inner walls are each equipped with an internal spray coating to improve wear resistance and smoothness, preventing organic matter from accumulating on the inner wall surface after coking. Filters are added to the inlet of each vacuum pump and are required to be cleaned regularly to prevent carbon deposits from accumulating over a long period of time and affecting pumping efficiency.

[0018] The pressure gauge P is installed on the upper part of the propylene carbonate vacuum tank 1 to facilitate pressure measurement. The primary filter 2, secondary filter 4 and tertiary filter 6 are all equipped with filter screens to meet the filtration requirements.

[0019] In use, after the crude propylene carbonate enters the distillation column, the vapor phase at the top of the column enters the condenser. The vapor phase at the top of the condenser is then drawn into the vacuum tank by a vacuum pump to maintain the system pressure below -95 kPa. After the non-condensable vapor in the propylene carbonate system enters the propylene carbonate vacuum tank 1, the tail gas first passes through a primary filter 2 and then enters a primary Roots pump 3 for primary suction and compression. Then, it passes through a secondary filter 4 and enters a secondary Roots pump 5 for secondary suction and compression. Finally, it passes through a tertiary filter 6 and enters a screw pump 7 for suction and compression, and the tail gas is finally discharged. The compression ratio of the primary Roots pump 3 and the secondary Roots pump 5 is 1:2. The pumping capacities of the primary Roots pump 3, the secondary Roots pump 5, and the screw pump 7 are 2500 L / s, 1200 L / s, and 2250 m³ / h, respectively, which meets the mutual matching between the equipment and ensures that the compressed organic gas can be discharged in a timely manner.

[0020] In addition, the rotors inside the first-stage Roots pump 3, the second-stage Roots pump 5, and the screw pump 7 are covered with Hastelloy material to prevent wear, corrosion, and deformation of internal parts, thereby reducing the probability of organic gas phase carbonization and coking. Furthermore, if coking does occur, it can be cleaned through a three-stage filter to prevent it from entering the next stage of equipment and causing damage, thus extending the service life of the equipment.

[0021] Example 2: The anti-coking device for a vacuum pump in a propylene carbonate system mentioned in this utility model includes a primary filter 2, a primary roots pump 3, a secondary filter 4, a secondary roots pump 5, a tertiary filter 6, a screw pump 7, and a silencer 8. The upper end of the propylene carbonate vacuum tank 1 is connected to the inlet end of the primary roots pump 3 via a pipeline and the primary filter 2. The outlet end of the primary roots pump 3 is connected to the inlet end of the secondary roots pump 5 via a pipeline and the secondary filter 4. The outlet end of the secondary roots pump 5 is connected to the inlet end of the screw pump 7 via a pipeline and the tertiary filter 6. The outlet end of the screw pump 7 is connected to an exhaust pipeline and the silencer 8.

[0022] The difference from Example 1 is: Reference Figure 2 Depending on actual needs, a second screw pump 11 can be added to meet different vacuum requirements.

[0023] The above description is merely a preferred embodiment of this utility model. Any person skilled in the art may modify this utility model or modify it into an equivalent technical solution using the technical solutions described above. Therefore, any simple modifications or equivalent transformations made based on the technical solutions of this utility model are within the scope of protection claimed by this utility model.

Claims

1. A device for preventing coking in a vacuum pump of a propylene carbonate system, characterized in that: Including Level 1 The filter (2), primary Roots pump (3), secondary filter (4), secondary Roots pump (5), tertiary filter (6), screw pump (7), and silencer (8) are connected to the inlet of the primary Roots pump (3) via a pipeline and the primary filter (2) at the upper end of the propylene carbonate vacuum tank (1). The outlet of the primary Roots pump (3) is connected to the inlet of the secondary Roots pump (5) via a pipeline and the secondary filter (4). The outlet of the secondary Roots pump (5) is connected to the inlet of the screw pump (7) via a pipeline and the tertiary filter (6). The outlet of the screw pump (7) is connected to the exhaust pipeline and the silencer (8).

2. The anti-coking device for a vacuum pump in a propylene carbonate system according to claim 1, characterized in that: The compression ratio of the first-stage Roots pump (3) and the second-stage Roots pump (5) is 1:

2.

3. The anti-coking device for a vacuum pump in a propylene carbonate system according to claim 2, characterized in that: The pumping capacities of the first-stage Roots pump (3), the second-stage Roots pump (5), and the screw pump (7) are 2500 L / s, 1200 L / s, and 2250 m3 / h, respectively.

4. The anti-coking device for a vacuum pump in a propylene carbonate system according to claim 1, characterized in that: A first control valve (9) is installed on the pipeline between the upper end of the propylene carbonate vacuum tank (1) and the primary filter (2).

5. The anti-coking device for a vacuum pump in a propylene carbonate system according to claim 4, characterized in that: A second control valve (10) is installed on the exhaust line at the outlet of the muffler (8).

6. A coking prevention device for a vacuum pump in a propylene carbonate system according to claim 1 or 3, characterized in that: The rotors inside the first-stage Roots pump (3), the second-stage Roots pump (5), and the screw pump (7) are all coated with Hastelloy alloy.

7. The anti-coking device for a vacuum pump in a propylene carbonate system according to claim 1, characterized in that: A pressure gauge (P) is installed on the upper part of the propylene carbonate vacuum tank (1).

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