Multi-stage vacuum unit drying method and drying system thereof

Abstract

The invention belongs to the technical field of vacuum drying equipment, and particularly relates to a multi-stage vacuum unit drying method and a drying system.The drying method comprises the following steps that S1, after a backing pump is started to reach low vacuum, part or all intermediate pumps are selectively started and stopped, and then a main pump is started to be stabilized to reach target vacuum matched with materials; s2, different drying devices with the same vacuum requirement are vacuumized through a pump vacuum buffer tank and a plurality of branch pipelines; s3, heating and auxiliary modules of the drying equipment are started, and the materials are heated and dried by combining the vacuum environment and pertinence; s4, the condensing device cools high-temperature exhaust gas of the unit and collects condensate; s5, the recovery device collects the accumulated liquid of the whole system and transfers the accumulated liquid for environment-friendly treatment; stepped vacuum is constructed through multiple stages of units, different material requirements are met, a single unit can supply multiple devices, cost is reduced, occupied space is reduced, vacuum stability is improved, and energy is saved. And in cooperation with a condensation and recovery device, material loss can be reduced, environmental influence is reduced, and environmental friendliness is improved.

Description

Technical Field

[0001] This invention belongs to the field of vacuum drying equipment technology, and particularly relates to a multi-stage vacuum unit drying method and its drying system. Background Technology

[0002] Vacuum drying, with its advantages of low drying temperature, uniform heating of materials, and minimal damage to active ingredients, is widely used in pharmaceuticals, chemicals, food, and other fields. In industrial production, different types of materials to be dried (such as powders, granules, and pastes) have significantly different requirements for vacuum levels. Even for the same material, different drying stages require gradient vacuum environments to achieve efficient drying.

[0003] Existing vacuum drying systems typically employ a single vacuum unit paired with a single drying device. This approach has significant limitations: firstly, when multiple drying devices of different types are present on the production line, multiple independent vacuum units are required, which not only increases equipment purchase costs and factory floor space but also raises the complexity of equipment operation and maintenance; secondly, the pumps of traditional vacuum units have fixed start-up and shutdown methods, making it impossible to selectively start and stop the intermediate pumps according to the actual vacuum requirements of the materials, often resulting in operation at the highest vacuum level throughout the entire process, leading to a significant waste of energy. Summary of the Invention

[0004] The purpose of this invention is to address the aforementioned technical problems by providing a multi-stage vacuum unit drying method and system. This system achieves the effect of adapting a single vacuum unit to multiple types of drying equipment for parallel operation, reducing purchase costs and site occupation, and allowing for adjustment of gradient vacuum according to material requirements, improving system vacuum stability, and avoiding energy waste.

[0005] In view of this, the present invention provides a multi-stage vacuum unit drying method, comprising the following steps: S1. Start the back pump of the multi-stage vacuum unit. After reaching the low vacuum standard, selectively start or stop some or all of the intermediate pumps. Finally, start the main pump so that the multi-stage vacuum unit can stabilize to different target vacuum levels according to the needs of the material to be dried. S2. Vacuuming is performed on different drying equipment under the same vacuum requirement through a pump vacuum buffer tank and multiple branch pipelines; S3. Start the heating and auxiliary modules of the drying equipment, and use the synergistic effect of the matched vacuum environment and targeted heating to vacuum dry the material. S4. Cool the high-temperature exhaust gas generated by the multi-stage vacuum unit and collect the condensate through a condensation device; S5. Collect the accumulated liquid produced by the drying equipment, multi-stage vacuum unit and condensation unit through the recycling device, and transfer it for environmental treatment.

[0006] In the above technical solution, further: By selectively turning on or off some or all of the intermediate pumps, a gradient vacuum based on low vacuum and adapted to different process requirements can be constructed, with the pumping speed ratio of adjacent pump stages being 1-2. The ultimate vacuum of the backing pump is 2000 Pa, and the relative vacuum degree is ≥-0.08 MPa; the ultimate vacuum of the first intermediate pump is 200 Pa, and the relative vacuum degree is ≥-0.09 MPa; the ultimate vacuum of the second intermediate pump is 20 Pa, and the relative vacuum degree is ≥-0.095 MPa; and the ultimate vacuum of the main pump is 1-2 Pa, and the relative vacuum degree is ≥-0.098 MPa.

[0007] In the above technical solution, further, in step S1: During the operation of a multi-stage vacuum unit, the back pump, multiple intermediate pumps, and the main pump are cooled synchronously by a cooling medium.

[0008] In the above technical solution, further, in step S3: S31: The vacuum trap system of the single cone vacuum dryer is connected through the first branch pipeline via the single cone vacuum buffer tank and the tube heat exchanger. The vacuum trap system achieves vacuum filtration, starts the ribbon agitator and heating components of the single cone dryer, drives the material to move in the inverted cone cylinder and completes heat exchange, thereby achieving material drying. S32: The vacuum head system of the vacuum tube device at one end of the double cone vacuum dryer is connected to the second branch pipeline through the double cone vacuum filter. Vacuum filtration is achieved through the double cone vacuum filter. Steam or hot water is introduced into the jacket of the double cone dryer. The low-speed motor is started to drive the tank to rotate, so that the material is turned over and heat exchange is completed, thereby achieving material drying. S33: The vacuum system is connected to the vacuum tube device at the bottom of the two plate vacuum ovens through the third branch pipe and the fourth branch pipe respectively. The heat source is introduced into the heating coil of the plate vacuum oven. The heat source is one of hot water, steam or heat transfer oil. The material is placed in the drying tray inside the oven and static drying is achieved through heat conduction.

[0009] In the above technical solution, further: The start and stop of each level of vacuum unit are automatically controlled through feedback from the electric contact pressure gauge and the electric contact vacuum gauge, which monitor the vacuum level in real time and trigger corresponding start and stop commands.

[0010] This invention provides a drying system for a multi-stage vacuum unit drying method, comprising: A multi-stage vacuum unit, comprising a backing pump, multiple intermediate pumps and a main pump connected in sequence; The pump vacuum buffer tank is connected to the inlet end of the main pump and has multiple branch pipelines leading out from it. Drying equipment, including single-cone vacuum dryer units, double-cone vacuum dryer units, and box dryers, are connected to multiple branch pipelines respectively; A condenser is connected to the outlet of the backing pump and is used to condense the exhaust gas from the multi-stage vacuum unit and collect the condensate. The recycling unit, connected to the drying equipment, pump vacuum buffer tank, multi-stage vacuum unit, and condensation device, is used to collect the generated liquid and transport it for environmental treatment.

[0011] In the above technical solution, further: The backing pump is an oil-free vertical vacuum pump; Both the intermediate stage pump and the main stage pump are Roots vacuum pumps; The system consists of a main pump, multiple intermediate pumps, and a back pump connected in sequence, with a check valve installed on the outlet side of the back pump.

[0012] In the above technical solution, further: The single cone vacuum dryer unit includes a single cone dryer, a vacuum trap connected to the single cone dryer, a heat exchanger connected to the vacuum trap, and a single cone vacuum buffer tank connected between the heat exchanger and the pump vacuum buffer tank. The double cone vacuum dryer unit includes a double cone dryer and a vacuum filter connected between the double cone dryer and the pump vacuum buffer tank.

[0013] Furthermore, the above technical solution also includes: The cooling device is connected to the multi-stage vacuum unit and is used to simultaneously cool the backing pump, multiple intermediate pumps, and the main pump using a cooling medium.

[0014] In the above technical solution, further: The back pump is connected to a liquid collection tank; The recovery device includes a recovery pipeline, a liquid pump, and a storage tank. The liquid pump is connected to the recovery pipeline and the storage tank. One end of the recovery pipeline is connected to the liquid pump, and the other end is connected to a box dryer, a vacuum filter, a vacuum trap, a single cone vacuum buffer tank, a pump vacuum buffer tank, a liquid collection tank, and a condensation device.

[0015] The beneficial effects of this invention are as follows: 1. A multi-stage vacuum unit is constructed by using multi-stage vacuum pumps. Based on the pre-stage pump and the main stage pump, a stepped vacuum is built. By selectively turning on or off some or all of the intermediate pumps, the system vacuum is adjusted to meet the vacuum requirements of different materials. Through multiple branch pipelines, a single vacuum unit can supply vacuum to multiple different drying equipment under the same vacuum requirements, reducing purchase costs and space occupation, improving system vacuum stability, and avoiding energy waste.

[0016] 2. By adding a condensation device to cool the high-temperature exhaust gas and collect the condensate, and in conjunction with a recovery device to collect the accumulated liquid in the entire vacuum drying system, it helps to reduce material loss, reduce the environmental impact of exhaust gas and accumulated liquid, extend the service life of equipment, and improve the environmental friendliness of the system.

[0017] 3. Synchronous cooling of the forepump, intermediate pump and main pump during unit operation helps control the temperature rise of each pump during operation, which can extend the service life of the pump set to a certain extent, reduce pump failures caused by high temperature, and ensure the stability of unit operation. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the drying system of the present invention; Figure 2 This is the present invention. Figure 1 Enlarged view of section A; Figure 3 This is the present invention. Figure 1 Enlarged view of section B; Figure 4 This is the present invention. Figure 1 Enlarged view of section C; The markings in the diagram represent: 1. Foreboard pump; 2. Intermediate pump; 3. Main pump; 4. Pump vacuum buffer tank; 5. Branch pipeline; 6. Single cone vacuum dryer unit; 60. Single cone dryer; 61. Vacuum trap; 62. Heat exchanger; 63. Single cone vacuum buffer tank; 7. Double cone vacuum dryer unit; 70. Double cone dryer; 71. Vacuum filter; 8. Box dryer; 9. Condensation device; 10. Recovery device; 100. Recovery pipeline; 101. Liquid pump; 102. Storage tank; 11. Check valve. Detailed Implementation

[0019] The technical solutions of the embodiments of this application will be clearly described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application are within the scope of protection of this application.

[0020] Example 1: This embodiment provides a multi-stage vacuum unit drying method, including the following steps: S1. Start the back pump 1 of the multi-stage vacuum unit. After reaching the low vacuum standard, selectively start or stop some or all of the intermediate pumps 2. Finally, start the main pump 3 so that the multi-stage vacuum unit can stabilize to different target vacuum levels according to the needs of the material to be dried. S2. Vacuuming is performed on different drying equipment under the same vacuum requirement through the pump vacuum buffer tank 4 and multiple branch pipelines 5; S3. Start the heating and auxiliary modules of the drying equipment, and use the synergistic effect of the matched vacuum environment and targeted heating to vacuum dry the material. S4. Cool the high-temperature exhaust gas generated by the multi-stage vacuum unit through the condensation device 9 and collect the condensate; S5. Collect the accumulated liquid produced by the drying equipment, multi-stage vacuum unit and condensation device 9 through the recycling device 10, and transfer it for environmental treatment.

[0021] As can be seen from this embodiment, a multi-stage vacuum unit is formed by using multi-stage vacuum pumps. Based on the pre-stage pump 1 and the main stage pump 3, a stepped vacuum is constructed. By selectively turning on or off some or all of the intermediate pumps 2, the system vacuum is adjusted to meet the vacuum requirements of different materials. Through multiple branch pipelines 5, a single vacuum unit can supply vacuum to multiple different drying equipment under the same vacuum requirements, thereby reducing purchase costs and site occupation, improving system vacuum stability, and avoiding energy waste. Meanwhile, a condensation device 9 is added to cool the high-temperature exhaust and collect the condensate. Together with the recovery device 10, the accumulated liquid of the entire vacuum drying system is collected, which helps to reduce material loss, reduce the environmental impact of exhaust and accumulated liquid, extend the service life of the equipment, and improve the environmental friendliness of the system.

[0022] Example 2: This embodiment provides a multi-stage vacuum unit drying method, which, in addition to the technical solutions of the above embodiments, also has the following technical features: By selectively turning on or off some or all of the intermediate pumps 2, a gradient vacuum based on low vacuum and adapted to different process requirements is constructed, and the pumping speed ratio of adjacent pumps is 1-2. Among them, the ultimate vacuum of the forestage pump 1 is 2000 Pa, and the relative vacuum degree is ≥-0.08 MPa; the ultimate vacuum of the first intermediate pump 2 is 200 Pa, and the relative vacuum degree is ≥-0.09 MPa; the ultimate vacuum of the second intermediate pump 2 is 20 Pa, and the relative vacuum degree is ≥-0.095 MPa; the ultimate vacuum of the main pump 3 is 1-2 Pa, and the relative vacuum degree is ≥-0.098 MPa.

[0023] As can be seen from this embodiment, by setting the pumping speed ratio between adjacent pumps at each stage to 1-2, it helps to improve the stability of gradient vacuum establishment and reduce load fluctuations during the operation of multi-stage vacuum units; and by limiting the ultimate vacuum and relative vacuum range of each pump, the adjustment of vacuum level is made more targeted, which can better adapt to the precise vacuum requirements of different processes and help improve drying efficiency.

[0024] Example 3: This embodiment provides a multi-stage vacuum unit drying method, which, in addition to the technical solutions of the above embodiments, also has the following technical features, in step S1: During the operation of the multi-stage vacuum unit, the forestage pump 1, multiple intermediate pumps 2, and main pump 3 are synchronously cooled by the cooling medium.

[0025] As can be seen from this embodiment, by simultaneously cooling the forepump 1, intermediate pump 2 and main pump 3 during the operation of the multi-stage vacuum unit, it is helpful to control the temperature rise of each pump during operation, which can extend the service life of the pump unit to a certain extent, reduce pump failures caused by high temperature, and ensure the stability of the multi-stage vacuum unit operation.

[0026] Example 4: This embodiment provides a multi-stage vacuum unit drying method, which, in addition to the technical solutions of the above embodiments, also has the following technical features, in step S3: S31: The vacuum trap 61 of the single cone vacuum dryer is connected to the single cone vacuum buffer tank 63 and heat exchanger 62 through the branch pipe 5. Vacuum filtration is achieved through the vacuum trap 61. The agitator and heating components of the single cone dryer 60 are started, which drives the material to move in the inverted cone cylinder and complete the heat exchange, thereby achieving material drying. S32: Connected to the double cone vacuum dryer via branch pipe 5 and vacuum filter 71, vacuum filtration is achieved through vacuum filter 71, steam or hot water is introduced into the jacket of double cone dryer 70, and a low-speed motor is started to drive the tank to rotate, so that the material is turned over and heat exchange is completed, thereby achieving material drying. S33: Connected to the box dryer 8 via branch pipe 5, hot water, steam or heat transfer oil is introduced into the heating coil of the box dryer 8, and the material is placed in the drying tray of the box dryer 8 to achieve static drying through heat conduction.

[0027] As can be seen from this embodiment, multiple branch pipes 5 are used to connect various drying equipment according to the characteristics of different vacuum dryers, which helps to adapt to different types of drying equipment and ensure the drying effect of different drying equipment on materials. By equipping the single cone dryer 60 with a vacuum trap 61 and the double cone dryer 70 with a vacuum filter 71, impurities can be filtered simultaneously during the drying process to prevent material from being carried out. At the same time, a heat exchanger 62 is provided for the single cone dryer 60 to condense the high-temperature airflow generated by the single cone dryer 60 and collect it in the single cone vacuum buffer tank 63. This prevents the high-temperature airflow from entering the pumps at each stage, which would cause the pump body temperature to become too high, affecting the sealing performance and the life of each stage of the pump.

[0028] Example 5: This embodiment provides a multi-stage vacuum unit drying method, which, in addition to the technical solutions of the above embodiments, also has the following technical features: The start and stop of each level of vacuum unit are automatically controlled through feedback from the electric contact pressure gauge and the electric contact vacuum gauge, which monitor the vacuum level in real time and trigger corresponding start and stop commands. The specific structures of the electric contact pressure gauge and the electric contact vacuum gauge are existing mature technologies, which are known to those skilled in the art from traditional devices, and will not be described in detail here.

[0029] As can be seen from this embodiment, automatic start-stop control of the pump group is achieved through feedback from the electric contact pressure gauge and the electric contact vacuum gauge. This allows for real-time monitoring of vacuum changes and timely triggering of control commands, reducing errors caused by manual intervention, helping to maintain the stability of the system's vacuum environment, and lowering manual operation and maintenance costs.

[0030] Example 6: This embodiment provides a multi-stage vacuum drying system, including: A multi-stage vacuum unit, comprising a backing pump 1, multiple intermediate pumps 2 and a main pump 3 connected in sequence; The pump vacuum buffer tank 4 is connected to the inlet end of the main pump 3 and has multiple branch pipelines 5 leading out. The drying equipment includes a single-cone vacuum dryer unit 6, a double-cone vacuum dryer unit 7, and a box dryer 8, which are connected to multiple branch pipelines 5 respectively. The condenser 9 is connected to the outlet end of the back pump 1 and is used to condense the exhaust gas of the multi-stage vacuum unit and collect the condensate. The recycling device 10 is connected to the drying equipment, the pump vacuum buffer tank 4, the multi-stage vacuum unit, and the condensation device 9, and is used to collect the generated liquid and transfer it for environmental treatment. Among them, the pump vacuum buffer tank 4, the box dryer 8, and the condensing device 9 can be condensers and vacuum receiving tanks. Their specific structures are all existing mature technologies, which are known to the technical personnel in the relevant technical field from traditional equipment, and will not be described in detail here.

[0031] As can be seen from this embodiment, by connecting the pump vacuum buffer tank 4 to the inlet end of the main pump 3 and leading out multiple branch pipelines 5, the vacuum fluctuations during the parallel operation of multiple drying devices can be buffered, which helps to maintain the stability of the vacuum environment in each device. At the same time, the system integrates multiple types of drying equipment with an integrated recovery and condensation device 9, so that the system can adapt to the drying needs of different materials, while taking into account material recovery and environmental protection, thus improving the overall practicality of the system.

[0032] Example 7: This embodiment provides a multi-stage vacuum drying system, which, in addition to the technical solutions of the above embodiments, also has the following technical features: Backing pump 1 is an oil-free vertical vacuum pump; Both intermediate pump 2 and main pump 3 are Roots vacuum pumps; Among them, the main pump 3, multiple intermediate pumps 2 and the fore-pump 1 are connected in sequence, and the outlet side of the fore-pump 1 is equipped with a check valve 11. Meanwhile, the specific structures of the oil-free vertical vacuum pump, the Roots vacuum pump, and the check valve 11 are all existing mature technologies, which are known to those skilled in the art from traditional devices, and will not be elaborated here.

[0033] As can be seen from this embodiment, by using an oil-free vertical vacuum pump as the backing pump 1, the inability of the Roots vacuum pump to start under atmospheric pressure is avoided. Then, by using an oil-free vertical vacuum pump, the risk of oil contamination of materials can be reduced. At the same time, a check valve 11 is installed on the outlet side of the backing pump 1 to effectively prevent backflow of gas or liquid and reduce interference with the pump set and the vacuum environment of the system.

[0034] Example 8: This embodiment provides a multi-stage vacuum drying system, which, in addition to the technical solutions of the above embodiments, also has the following technical features: The single cone vacuum dryer unit 6 includes a single cone dryer 60, a vacuum trap 61 connected to the single cone dryer 60, a heat exchanger 62 connected to the vacuum trap 61, and a single cone vacuum buffer tank 63 connected between the heat exchanger 62 and the pump vacuum buffer tank 4. The double cone vacuum dryer unit 7 includes a double cone dryer 70 and a vacuum filter 71 connected between the double cone dryer 70 and the pump vacuum buffer tank 4; The specific structures of the single cone dryer 60, vacuum trap 61, heat exchanger 62, single cone vacuum buffer tank 63, double cone vacuum dryer, and vacuum filter 71 are all existing mature technologies, which are known to those skilled in the art from traditional equipment, and will not be described in detail here.

[0035] As can be seen from this embodiment, the addition of a single-cone vacuum buffer tank 63 and a heat exchanger 62 to the single-cone vacuum dryer unit 6 can further stabilize the vacuum environment of the single-cone dryer 60 and achieve heat exchange pretreatment. At the same time, the heat exchanger 62 is set on the single-cone dryer 60 to condense the high-temperature airflow generated by the single-cone dryer 60 and collect it in the single-cone vacuum buffer tank 63, so as to prevent the high-temperature airflow from entering the pumps of each stage and causing the pump body temperature to be too high, which would affect the sealing performance and avoid affecting the life of each stage of the pump. The double cone vacuum dryer unit 7 is equipped with a vacuum filter 71, which can filter impurities in the material in advance, thus helping to improve the final drying quality.

[0036] Example 9: This embodiment provides a multi-stage vacuum drying system, which, in addition to the technical solutions of the above embodiments, also has the following technical features and includes: The cooling device is connected to the multi-stage vacuum unit and is used to simultaneously cool the forepump 1, multiple intermediate pumps 2 and the main pump 3 through the cooling medium. The specific structure of the cooling device is existing technology, specifically the use of a circulating pump to supply the cooling medium, which is known to those skilled in the art from traditional cooling devices and will not be elaborated here.

[0037] As can be seen from this embodiment, by adding a cooling device and clarifying its synchronous cooling function, the temperature of each pump can be effectively controlled during operation, reducing the wear and tear on key components such as pump seals and bearings caused by high temperatures, which helps to extend the service life of the equipment and ensure the long-term stable operation of the system.

[0038] Example 10: This embodiment provides a multi-stage vacuum drying system, which, in addition to the technical solutions of the above embodiments, also has the following technical features: The back pump 1 is connected to a liquid collection tank; The recovery device 10 includes a recovery pipeline 100, a liquid pump 101, and a storage tank 102. The liquid pump 101 is connected to the recovery pipeline 100 and the storage tank 102. One end of the recovery pipeline 100 is connected to the liquid pump 101, and the other end is connected to the box dryer 8, the vacuum filter 71, the vacuum collector 61, the single cone vacuum buffer tank 63, the pump vacuum buffer tank 4, the liquid collection tank, and the condensation device 9, respectively. The pump 101 can be a diaphragm pump, and the pump 101, the storage tank 102, and the required number of opening and closing valves on the recovery pipeline 100 are all existing mature technologies, which are known to those skilled in the art from the conventional recovery device 10, and will not be described in detail here.

[0039] As can be seen from this embodiment, by adding a liquid collection tank at the front pump 1, the liquid generated during the operation of the front pump 1 can be collected in a targeted manner, reducing the impact of the liquid on the operation of the pump set. Meanwhile, the recycling device 10 can realize the centralized collection and transfer of liquid accumulated in the entire system, reduce the risk of liquid leakage, and improve the convenience of environmental protection treatment.

[0040] The embodiments of this application have been described above with reference to the accompanying drawings. Unless otherwise specified, the embodiments and features in the embodiments of this application can be combined with each other. This application is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms under the guidance of this application without departing from the spirit and scope of the claims, and all of these forms are within the protection scope of this application.

Claims

1. A multi-stage vacuum set of machines drying method, characterized in that, The method comprises the following steps: S1, starting the front-stage pump (1) of the multi-stage vacuum unit, after reaching the low vacuum standard, selectively starting or stopping part or all of the intermediate-stage pumps (2), and finally starting the main-stage pump (3), so that the multi-stage vacuum unit is correspondingly stabilized to different levels of target vacuum according to the requirements of the material to be dried; S2, through the pump vacuum buffer tank (4) and multiple branch pipelines (5), the different drying equipment is vacuumized under the same vacuum requirement; S3, starting the heating and auxiliary module of the drying equipment, and utilizing the synergistic effect of the matched vacuum environment and targeted heating to vacuumize and dry the material; S4, through the condensing device (9), the high-temperature exhaust gas generated by the multi-stage vacuum unit is cooled and the condensed liquid is collected; S5, through the recovery device (10), the accumulated liquid produced by the drying equipment, the multi-stage vacuum unit and the condensing device (9) is collected and transported for environmental protection treatment.

2. The multi-stage vacuum unit drying method according to claim 1, characterized in that: By selectively starting or stopping part or all of the intermediate-stage pumps (2), a gradient vacuum based on low vacuum is constructed to adapt to different process requirements, and the pumping speed ratio of adjacent stages is 1-2; Wherein, the limit vacuum of the front-stage pump (1) is 2000Pa, and the relative vacuum degree is ≥-0.08MPa; the limit vacuum of the first intermediate-stage pump (2) is 200Pa, and the relative vacuum degree is ≥-0.09MPa; the limit vacuum of the second intermediate-stage pump (2) is 20Pa, and the relative vacuum degree is ≥-0.095MPa; the limit vacuum of the main-stage pump (3) is 1-2Pa, and the relative vacuum degree is ≥-0.098MPa.

3. The multi-stage vacuum cluster drying method according to claim 1, wherein, In the step S1: During the operation of the multi-stage vacuum unit, the front-stage pump (1), the multiple intermediate-stage pumps and the main-stage pump (3) are synchronously cooled by a cooling medium.

4. The multi-stage vacuum cluster drying method of claim 1, wherein, In the step S3: S31: through the branch pipeline (5), the single-cone vacuum buffer tank (63) and the heat exchanger (62) are connected to the vacuum trap (61) of the single-cone vacuum dryer, vacuum filtration is realized through the vacuum trap (61), the stirrer and heating components of the single-cone dryer (60) are started, the material moves in the inverted-cone cylinder and completes heat exchange, and the material is dried; S32: through the branch pipeline (5), the vacuum filter (71) is connected to the double-cone vacuum dryer, vacuum filtration is realized through the vacuum filter (71), steam or hot water is introduced into the jacket of the double-cone dryer (70), the low-speed motor is started to drive the tank body to rotate, the material is turned over and heat exchange is completed, and the material is dried; S33: through the branch pipeline (5), the box dryer (8) is connected, one of hot water, steam or conductive oil is introduced into the heating coil of the box dryer (8), and the material is placed in the drying tray of the box dryer (8), and static drying is realized through heat conduction.

5. The multi-stage vacuum unit drying method according to claim 1, characterized in that: The start and stop of each stage of the vacuum unit is automatically controlled through the feedback of the electric contact pressure gauge and the electric contact vacuum gauge (12), the vacuum degree is monitored in real time, and the corresponding start and stop instructions are triggered.

6. A drying system for use in the multi-stage vacuum set drying method according to any one of claims 1 to 5, characterized in that, It comprises: A multi-stage vacuum unit comprising a front-stage pump (1), multiple intermediate-stage pumps (2) and a main-stage pump (3) connected in sequence; The pump vacuum buffer tank (4) is connected to the inlet end of the main pump (3) and has multiple branch pipelines (5) leading out. The drying equipment includes a single cone vacuum dryer (6), a double cone vacuum dryer (7) and a box dryer (8), and is connected to multiple branch pipelines (5) respectively; The condenser (9) is connected to the outlet end of the back pump (1) and is used to condense the exhaust gas of the multi-stage vacuum unit and collect the condensate. The recovery device (10) is connected to the drying equipment, the pump vacuum buffer tank (4), the multi-stage vacuum unit and the condensation device (9) to collect the generated liquid and transfer it for environmental treatment.

7. The multi-stage vacuum drying system according to claim 6, characterized in that: The forepump (1) is an oil-free vertical vacuum pump; Both the intermediate pump (2) and the main pump (3) are Roots vacuum pumps; The main pump (3), multiple intermediate pumps (2) and the fore-pump (1) are connected in sequence, and a check valve (11) is provided on the outlet side of the fore-pump (1).

8. The multi-stage vacuum drying system according to claim 6, characterized in that: The single cone vacuum dryer unit (6) includes a single cone dryer (60), a vacuum trap (61) connected to the single cone dryer (60), a heat exchanger (62) connected to the vacuum trap (61), and a single cone vacuum buffer tank (63) connected between the heat exchanger (62) and the pump vacuum buffer tank (4). The double cone vacuum dryer unit (7) includes a double cone dryer (70) and a vacuum filter (71) connected between the double cone dryer (70) and the pump vacuum buffer tank (4).

9. The multi-stage vacuum team drying system of claim 6, wherein, Also includes: The cooling device is connected to the multi-stage vacuum unit and is used to simultaneously cool the back pump (1), multiple intermediate pumps (2) and the main pump (3) through a cooling medium.

10. The multi-stage vacuum drying system according to claim 6, characterized in that: The fore-pump (1) is connected to a liquid collection tank (14). The recovery device (10) includes a recovery pipeline (100), a liquid pump (101) and a storage tank (102). The liquid pump (101) is connected to the recovery pipeline (100) and the storage tank (102). One end of the recovery pipeline (100) is connected to the liquid pump (101), and the other end is connected to the box dryer (8), the vacuum filter (71), the vacuum trap (61), the single cone vacuum buffer tank (63), the pump vacuum buffer tank (4), the liquid collection tank (14), and the condensation device (9).

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