Energy-saving Roots screw dry-type vacuum-pumping system

Abstract

The utility model relates to an energy-saving Roots screw rod dry type vacuum-pumping system, which comprises a prefilter, a Roots vacuum pump, an interstage condenser, an interstage filter, a liquid storage tank and a screw rod vacuum pump, the prefilter is connected with the Roots vacuum pump, the Roots vacuum pump is connected with the interstage condenser, the interstage condenser is respectively connected with the interstage filter and the liquid storage tank, and the screw rod vacuum pump is connected with the liquid storage tank. The interstage filter is connected with a screw vacuum pump; a first air outlet of the pre-filter is connected with a roots vacuum pump, and the roots vacuum pump is connected with a first motor; and the screw vacuum pump is connected with a second motor. The device is higher in air exhaust efficiency, more energy-saving and environment-friendly, high in condensable gas recovery capacity, low in noise, low in vibration and simple and convenient to maintain.

Description

Technical Field

[0001] This utility model relates to the field of vacuum technology, and in particular to an energy-saving Roots screw dry vacuum system. Background Technology

[0002] During the heating and extrusion process of plastic raw materials, plastic extruders generate various volatile organic gases. These gases must be removed promptly using vacuum equipment to prevent defects such as bubbles, bulges, uneven appearance, and poor surface gloss in the extruded plastic products. Furthermore, higher vacuum levels result in better internal quality and a more attractive appearance in the extruded plastic products. Therefore, continuous vacuuming of the extruder is necessary during the production of APET / PETG / PET plastics.

[0003] Currently, existing technologies generally use three-stage Roots water ring vacuum units for vacuuming. When a three-stage Roots water ring vacuum unit evacuates an extruder, the various organic gases mentioned above tend to accumulate inside the Roots vacuum pump after entering the vacuum unit. As the organic matter accumulates to a certain amount, it causes rotor friction overheating and quickly leads to pump seizure. Furthermore, the various organic substances continuously entering the forestage water ring vacuum pump mix with the working fluid (water) before being discharged to the gas-liquid separator. In the gas-liquid separator, the extracted gases are separated from the working fluid; the exhaust gas is discharged into the atmosphere through the filter's exhaust port, and the wastewater is discharged into a sewage collection tank. The large amount of wastewater discharged by the water ring vacuum pump results in significant treatment costs, and the gases emitted cause environmental pollution and health hazards to operators. Additionally, the noise from the water ring vacuum pump has a significant impact on the physical and mental health of operators. Summary of the Invention

[0004] The purpose of this invention is to overcome the above-mentioned shortcomings and provide an energy-saving Roots screw dry vacuum system.

[0005] The purpose of this utility model is achieved as follows:

[0006] An energy-saving Roots screw dry vacuum system includes a pre-filter, a Roots vacuum pump, an interstage condenser, an interstage filter, a liquid storage tank, a screw vacuum pump, and a control system. The pre-filter is connected to the Roots vacuum pump, the Roots vacuum pump is connected to the interstage condenser, the interstage condenser is connected to the interstage filter and the liquid storage tank, and the interstage filter is connected to the screw vacuum pump.

[0007] The pre-filter includes a first housing, with a first air inlet on the side, a first air outlet on the top surface, and a first drain outlet on the bottom surface; the pre-filter contains a filter screen assembly, and the first air inlet leads to the filter screen assembly; the interstage filter includes a second housing, with a second air inlet on the side, a second air outlet at the bottom, and a second drain outlet at the bottom; the second housing contains a stainless steel filter element, and the second air inlet leads to the stainless steel filter element.

[0008] The first outlet of the pre-filter is connected to a Roots vacuum pump, which is connected to a first electric motor; the screw vacuum pump is connected to a second electric motor.

[0009] Furthermore, the filter assembly includes an upper plate and an inner mesh, a pull rod, an outer mesh, and a lower plate. The upper plate and the lower plate are arranged parallel to each other. The center of the upper plate and the lower plate is provided with corresponding through holes. The inner mesh is arranged in the through holes. The top end of the inner mesh extends out of the upper plate and the bottom end is set on the lower plate. An outer mesh is fitted over the inner mesh and is arranged between the upper plate and the lower plate.

[0010] Furthermore, at least two symmetrically arranged tie rods are provided between the upper plate and the lower plate, and the tie rods are arranged between the inner mesh and the outer mesh.

[0011] Furthermore, the interstage condenser includes a cylindrical body, with a condensate exhaust port on the upper side of the cylindrical body, a condensate inlet on the lower side of the cylindrical body, a condensate water inlet and a condensate drain on the bottom surface of the cylindrical body, and a condensate drain outlet on the bottom side of the cylindrical body.

[0012] Furthermore, a thermometer, a venting valve, a vacuum gauge, and a check valve are sequentially installed on the connecting pipeline between the interstage filter and the screw vacuum pump.

[0013] Furthermore, the screw vacuum pump is equipped with a cooling water pressure transmitter and a cooling water flow switch on its inlet pipe.

[0014] Furthermore, the storage tank is equipped with a level transmitter.

[0015] Furthermore, a pressure transmitter is provided on the connecting pipeline between the pre-filter and the Roots vacuum pump.

[0016] Furthermore, the screw vacuum pump is connected to the exhaust gas condenser.

[0017] Furthermore, the bottom side of the first housing is provided with symmetrically arranged supports, and the supports are provided with feet for support.

[0018] Compared with the prior art, the beneficial effects of this utility model are:

[0019] This invention provides an energy-saving Roots screw dry vacuum system, which has higher pumping efficiency in the high vacuum stage compared to a three-stage Roots water ring vacuum unit. The combination of the Roots vacuum pump and the screw vacuum pump enables the vacuum unit to have high-efficiency pumping capability, and can quickly reach and maintain the vacuum level required for the normal operation of the extruder.

[0020] This invention is more energy-efficient and environmentally friendly: the oil-free design of the screw vacuum pump avoids the secondary pollution caused by the use of working fluid or lubricating oil in traditional vacuum pumps, meeting the requirements of modern industry for energy conservation and environmental protection; at the same time, the efficient operation of the two-stage Roots screw vacuum unit reduces energy consumption and operating costs.

[0021] This invention has a strong ability to recover condensable gases: the two-stage recovery device enables the vacuum unit to better recover condensable gases, and the organic solvents in the gas are recovered and reused through condensation and separation technology, which reduces environmental pollution and creates additional economic benefits, and avoids the damage caused by condensable gases to the normal use of the vacuum pump.

[0022] This utility model features low noise and low vibration: the screw vacuum pump design achieves low noise and low vibration operation, providing a more comfortable working environment for staff.

[0023] This utility model is easy to maintain: the vacuum unit has a simple structure, is easy to disassemble and clean, reduces maintenance costs, and improves the reliability and service life of the equipment.

[0024] This invention features a high vacuum level: the Roots screw compressor unit can achieve a higher vacuum level, with an ultimate vacuum of 0.1 Pa, suitable for various applications requiring high vacuum.

[0025] This utility model has a wide range of applications: Roots screw vacuum pump units are widely used in chemical, pharmaceutical, semiconductor, solvent recovery, molding, crystallization, dry etching, sputtering, steam recovery and other fields. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the structure of this utility model.

[0027] Figure 2 This is a schematic diagram of the structure of the pre-filter of this utility model.

[0028] Figure 3 This is a schematic diagram of the filter assembly of this utility model.

[0029] Figure 4 This is a schematic diagram of the structure of the interstage condenser of this utility model.

[0030] Figure 5 This is a schematic diagram of the structure of the interstage filter of this utility model.

[0031] in:

[0032] 1. Pre-filter, 1.1 First housing, 1.2 First air inlet, 1.3 First air outlet, 1.4 First drain outlet, 1.5 Filter screen assembly, 1.51 Upper plate, 1.52 Inner screen, 1.53 Pull rod, 1.54 Outer screen, 1.55 Lower plate, 1.55 Support, 1.6 Support leg, 1.7 Roots vacuum pump, 2. First motor, 3. Interstage condenser, 4.1 Cylinder body, 4.2 Condensate air inlet, 4.3 Condensate exhaust outlet, 4.4 Condensate water inlet, 4.5 Condensate drain outlet, 4.6 Stage 5. Intermediate filter; 5.1. Second housing; 5.2. Second air inlet; 5.3. Second air outlet; 5.4. Second drain outlet; 5.5. Stainless steel filter element; 6. Liquid storage tank; 7. Liquid level transmitter; 8. Thermometer; 9. Air vent valve; 10. Vacuum gauge; 11. Check valve; 13. Screw vacuum pump; 13.1. Screw vacuum pump inlet; 13.2. Screw vacuum pump outlet; 14. Cooling water pressure transmitter; 15. Cooling water flow switch; 16. Second motor; 17. Exhaust gas condenser; 18. Pressure transmitter; 19. Control system. Detailed Implementation

[0033] To better understand the technical solution of this utility model, a detailed description will be provided below in conjunction with relevant illustrations. It should be understood that the specific embodiments described below are not intended to limit the specific implementation of the technical solution of this utility model, but are merely possible implementations of the technical solution of this utility model. It should be noted that the descriptions of the positional relationships of the components herein, such as component A being located above component B, are based on the relative positions of the components in the illustrations and are not intended to limit the actual positional relationships of the components. Example 1

[0034] See Figures 1-5 , Figure 1 A schematic diagram of the structure of this utility model has been drawn. As shown in the figure, this utility model relates to an energy-saving Roots screw dry vacuum system, which includes a pre-filter 1, a Roots vacuum pump 2, an interstage condenser 4, an interstage filter 5, a liquid storage tank 6, a screw vacuum pump 13, an exhaust gas condenser 17, and a control system 19. The pre-filter 1 is connected to the Roots vacuum pump 2, the Roots vacuum pump 2 is connected to the interstage condenser 4, the interstage condenser 4 is connected to the interstage filter 5 and the liquid storage tank 6 respectively, the interstage filter 5 is connected to the screw vacuum pump 13, and the screw vacuum pump 13 is connected to the exhaust gas condenser 17.

[0035] The pre-filter 1 includes a first housing 1.1, a first air inlet 1.2 on the side of the first housing 1.1, a first air outlet 1.3 on the top surface of the first housing 1.1, a first drain outlet 1.4 on the bottom surface of the first housing 1.1, and symmetrically arranged supports 1.6 on the bottom side of the first housing 1.1. Support legs 1.7 are provided below the supports 1.6 for support.

[0036] The pre-filter 1 is equipped with a filter assembly 1.5, which includes an upper plate 1.51, an inner screen 1.52, a pull rod 1.53, an outer screen 1.54, and a lower plate 1.55. The upper plate 1.51 and the lower plate 1.55 are arranged parallel to each other vertically. The upper plate 1.51 and the lower plate 1.55 have corresponding through holes at their centers. The inner screen 1.52 is installed in the through holes. The top end of the inner screen 1.52 extends out of the upper plate 1.51, and the bottom end is set on the lower plate 1.55. An outer screen 1.54 is fitted over the inner screen 1.52. The outer screen 1.54 is set between the upper plate 1.51 and the lower plate 1.55, that is, the top end of the outer screen 1.54 is fixed to the bottom surface of the upper plate 1.51, and the bottom end is fixed to the surface of the lower plate 1.55.

[0037] At least two symmetrically arranged tie rods 1.53 are also provided between the upper plate 1.51 and the lower plate 1.55, and the tie rods 1.53 are arranged between the inner mesh 1.52 and the outer mesh 1.54;

[0038] The first air inlet 1.2 leads to the filter assembly 1.5.

[0039] The interstage condenser 4 includes a cylinder 4.1. A condenser exhaust port 4.3 is provided on the upper side of the cylinder 4.1, a condenser air inlet 4.2 is provided on the lower side of the cylinder 4.1, a condenser water inlet 4.4 and a condenser drain port 4.5 are provided on the bottom surface of the cylinder 4.1, and a condensate drain port 4.6 is also provided on the bottom side of the cylinder 4.1.

[0040] The structure of the exhaust gas condenser 17 is the same as that of the interstage condenser 4.

[0041] The interstage filter 5 includes a second housing 5.1, a second air inlet 5.2 on the side of the second housing 5.1, a second air outlet 5.3 at the bottom of the second housing 5.1, a second drain outlet 5.4 at the bottom of the second housing 5.1, and a stainless steel filter element 5.5 inside the second housing 5.1. The second air inlet 5.2 leads to the stainless steel filter element 5.5.

[0042] The screw vacuum pump 13 is provided with a screw vacuum pump inlet 13.1 and a screw vacuum pump outlet 13.2.

[0043] The first outlet 1.3 of the pre-filter 1 is connected to the Roots vacuum pump 2, and the Roots vacuum pump 2 is connected to the first motor 3; the liquid storage tank 6 is equipped with a liquid level transmitter 7; the connecting pipeline between the interstage filter 5 and the screw vacuum pump 13 is sequentially equipped with a thermometer 8, a venting valve 9, a vacuum gauge 10 and a check valve 11.

[0044] The screw vacuum pump 13 is equipped with a cooling water pressure transmitter 14 and a cooling water flow switch 15 on its inlet pipe, and the screw vacuum pump 13 is connected to a second motor 16.

[0045] A pressure transmitter 18 is installed on the connecting pipeline between the pre-filter 1 and the Roots vacuum pump 2.

[0046] The first motor 3, level transmitter 7, thermometer 8, vent valve 9, check valve 11, cooling water pressure transmitter 14, cooling water flow switch 15, second motor 16 and pressure transmitter 18 are respectively connected to the control system 19.

[0047] The gas being drawn in enters the side inlet at the top of the pre-filter through the connecting pipe between the pre-filter and the plastic extruder. The gas entering the pre-filter rotates along the annular space between the inner wall of the filter and the outer cylinder of the filter screen. During the rotation of the gas, large particles and liquids fall down the inner wall of the filter and into the bottom of the filter under the action of centrifugal force and gravity. The remaining gas and small dust particles move towards the filter screen in the middle of the filter with the airflow. Because the filter screen has a high precision, dust particles of a certain diameter can hardly pass through the filter screen. Only the gas passes through the filter screen and continues to move towards the outlet at the top of the filter, and enters the Roots vacuum pump through the connecting pipe between the filter and the inlet of the Roots vacuum pump.

[0048] The gas entering the Roots vacuum pump is compressed and then enters the interstage condenser from the exhaust port of the Roots vacuum pump. In the interstage condenser, condensable substances in the pumped gas are condensed, and the condensate enters the storage tank through the pipe at the bottom of the interstage condenser. The storage tank is equipped with a level transmitter. When the condensate in the storage tank reaches the set high level, the storage tank needs to be drained through the drain pipe. The remaining uncondensed gas is filtered again through the filter and then enters the screw vacuum pump through the inlet. Through the intake, compression, and exhaust process of the screw vacuum pump, the pumped gas enters the tail gas condenser. Since the tail gas condenser is at atmospheric pressure, almost all harmful condensable organic gases can be condensed.

[0049] The final emitted gas contains almost no harmful gases other than harmless gases such as air and nitrogen, so this novel invention can achieve zero emissions of harmful gases.

[0050] Working principle:

[0051] This invention provides an energy-saving Roots screw dry vacuum system. A pre-filter is installed before the two-stage Roots screw vacuum unit. This filter is a multi-functional condensate separation and dust filtration and recovery device that integrates cyclone separation and filtration functions. It can cyclone separate, filter, and collect particulate matter and liquid media in the pumped gas. When the gas carrying particulate matter and liquid media enters the pre-filter, its linear motion in the inlet pipe changes to rotational motion inside the filter. Moreover, the cross-section of the air passage inside the filter is much larger than that of the inlet pipe. The airflow velocity decreases after entering the filter and is affected by the centrifugal force generated by the rotational motion. Therefore, condensable organic condensate and particulate matter in the pumped medium are centrifugally separated from the pumped gas inside the filter. Under the action of gravity, the condensate and particulate matter fall down the inner wall of the filter to the bottom of the filter. The pumped gas passes through the middle filter element and then enters the Roots vacuum pump from the top outlet of the filter.

[0052] After filtration and separation by the pre-filter, the amount of particulate matter and liquid entering the Roots vacuum pump is greatly reduced, thereby lowering the probability of the Roots vacuum pump seizure. A condensation trapping and filtration recovery device is installed between the exhaust port of the Roots vacuum pump and the intake port of the screw vacuum pump. This device includes a condenser, a liquid storage tank, an interstage filter, and level control and automatic drainage mechanisms. This reduces the amount of organic material in the pumped gas entering the forestage screw vacuum pump, protecting its long-term reliable operation and reducing gas emissions and environmental pollution. The condensation trapping device consists of a cylinder, an automatic inflation valve, an automatic shut-off valve, an automatic drainage valve, and high and low level sensors. The cylinder has an inlet, an exhaust port, and a drainage port. When condensate accumulates to the high level of the trap, the high level sensor signals the control system to activate the automatic drainage device. When the condensate reaches the low level, the low level sensor sends a control signal, and the control system automatically shuts off the drainage system.

[0053] Additionally, depending on actual needs, a tail gas condensation and capture device can be added to the exhaust port of the screw vacuum pump, enabling the entire vacuum system to achieve true zero gas emissions. The tail gas condensation and capture device performs secondary condensation and capture of the tail gas discharged from the screw vacuum pump under normal pressure. Based on the physical properties of the pumped gas, room temperature water or chilled water can be used as the refrigerant for the condenser, thus achieving complete capture of the pumped tail gas.

[0054] This invention addresses the issues of material damage to vacuum pumps, reduces energy consumption in vacuum equipment operation, and solves the environmental pollution problem caused by the pumped gases. Specifically, by incorporating a tail gas condenser, the pumped condensable gases undergo secondary condensation, achieving complete capture of harmful exhaust gases. This allows for the selection of a smaller Roots screw vacuum unit compared to a three-stage Roots water ring vacuum unit, significantly reducing motor power consumption. The refrigeration power required for condensing these gases is only 1 / 10 of the energy consumption of the original three-stage Roots water ring vacuum unit. Therefore, this invention achieves at least 35% energy savings compared to existing three-stage Roots water ring vacuum units, eliminates wastewater treatment costs, and allows the recovered organic matter to be sold or reused as byproducts, while achieving zero emissions during the production process.

[0055] The above are merely specific application examples of this utility model and do not constitute any limitation on the scope of protection of this utility model. All technical solutions formed by equivalent transformations or equivalent substitutions fall within the scope of protection of this utility model.

Claims

1. An energy-saving Roots-screw dry vacuum-pumping system, characterized by: It includes pre-filter (1), Roots vacuum pump (2), inter-stage condenser (4), inter-stage filter (5), liquid storage tank (6) and screw vacuum pump (13), the pre-filter (1) is connected Roots vacuum pump (2), the Roots vacuum pump (2) is connected inter-stage condenser (4), the inter-stage condenser (4) is connected inter-stage filter (5) and liquid storage tank (6) respectively, the inter-stage filter (5) is connected screw vacuum pump (13); The pre-filter (1) includes first housing (1.1), the side of first housing (1.1) is provided with a first air inlet (1.2), the top surface of first housing (1.1) is provided with a first air outlet (1.3), the bottom surface of first housing (1.1) is provided with a first blowdown (1.4), the pre-filter (1) is provided with filter screen assembly (1.5) in it, the first air inlet (1.2) leads to filter screen assembly (1.5), the inter-stage filter (5) includes second housing (5.1), the side of second housing (5.1) is provided with a second air inlet (5.2), the bottom end of second housing (5.1) is provided with a second air outlet (5.3), the bottom of second housing (5.1) is further provided with a second blowdown (5.4), the second housing (5.1) is provided with a stainless steel filter element (5.5) in it, the second air inlet (5.2) leads to the stainless steel filter element (5.5). The first air outlet (1.3) of the pre-filter (1) is connected to the Roots vacuum pump (2), and the Roots vacuum pump (2) is connected to the first motor (3); the screw vacuum pump (13) is connected to the second motor (16).

2. The energy-saving rotary screw dry vacuum pumping system according to claim 1, wherein: The filter screen assembly (1.5) includes upper plate (1.51), inner screen (1.52), pull rod (1.53), outer screen (1.54) and lower plate (1.55), the upper plate (1.51) and the lower plate (1.55) are arranged in parallel, the center of the upper plate (1.51) and the lower plate (1.55) is provided with a corresponding through hole, the inner screen (1.52) is arranged in the through hole, the top end of the inner screen (1.52) extends out of the upper plate (1.51), and the bottom end is arranged on the lower plate (1.55), the inner screen (1.52) is sleeved with an outer screen (1.54), and the outer screen (1.54) is arranged between the upper plate (1.51) and the lower plate (1.55).

3. The energy-saving rotary screw dry vacuum pumping system of claim 2, wherein: At least two symmetrical pull rods (1.53) are further arranged between the upper plate (1.51) and the lower plate (1.55), and the pull rod (1.53) is arranged between the inner screen (1.52) and the outer screen (1.54).

4. The energy-saving rotary screw dry vacuum pumping system of claim 1, wherein: The inter-stage condenser (4) includes a cylinder (4.1), one side of the upper part of the cylinder (4.1) is provided with a condensing exhaust port (4.3), one side of the lower part of the cylinder (4.1) is provided with a condensing air inlet (4.2), the bottom surface of the cylinder (4.1) is provided with a condensing water inlet (4.4) and a condensing water outlet (4.5), and one side of the bottom of the cylinder (4.1) is further provided with a condensate discharge port (4.6).

5. The energy-saving rotary screw dry vacuum pumping system of claim 1, wherein: A temperature gauge (8), a break valve (9), a vacuum gauge (10) and a check valve (11) are sequentially arranged on the connecting pipeline between the inter-stage filter (5) and the screw vacuum pump (13).

6. The energy-saving rotary screw dry vacuum pumping system of claim 1, wherein: A cooling water pressure transmitter (14) and a cooling water flow switch (15) are arranged on the water inlet pipeline of the screw vacuum pump (13).

7. The energy-saving rotary screw dry vacuum pumping system of claim 1, wherein: A liquid level transmitter (7) is arranged on the liquid storage tank (6).

8. The energy-saving rotary screw dry vacuum pumping system of claim 1, wherein: A pressure transmitter (18) is arranged on the connecting pipeline between the pre-filter (1) and the Roots vacuum pump (2).

9. The energy-saving rotary screw dry vacuum pumping system of claim 1, wherein: The screw vacuum pump (13) is connected with a tail gas condenser (17).

10. The energy-saving rotary screw dry vacuum pumping system of claim 1, wherein: The bottom side of the first shell (1.1) is provided with symmetrically arranged supports (1.6), and the lower side of the support (1.6) is provided with a supporting leg (1.7) for support.

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