Backwash dust filter device for dry-type screw pump

Abstract

The utility model relates to a backwash dust filter device for a dry-type screw pump. The backwash dust filter device comprises a filter shell consisting of a cylindrical shell and a conical hopper at the lower part, wherein the cylindrical shell is connected up and down; a gas outlet is formed in one side of the upper part of the cylindrical shell, and a compressed gas inlet is formed in the other side; a purge gas inlet pipe is arranged at the compressed gas inlet; an air inlet is formed in one side of the lower part of the cylindrical shell; a partition plate is arranged between the air inlet and the air outlet, a plurality of evenly-distributed stainless steel filter screen cylinders are arranged below the partition plate, the bottom face of the blowing gas inlet pipe is connected with a plurality of evenly-distributed pulse nozzles, and the pulse nozzles correspond to the stainless steel filter screen cylinders one to one. And a reverse blowing electromagnetic valve and a flow regulating valve are arranged on the outer side of the compressed air inlet flange. The double-acting mode of cyclone separation and filter screen filtration is adopted, the filtering effect is better, the structure is simple, and use and maintenance are convenient.

Description

Technical Field

[0001] This utility model relates to the field of dust filtration technology, and in particular to a backwashing dust filter device for a dry screw pump. Background Technology

[0002] Dry screw vacuum pumps are widely used in vacuum drying and degassing processes in chemical, pharmaceutical, and new energy material preparation industries. Examples include vacuum stirring of polar materials for lithium batteries; polycrystalline silicon production in solar cells; vacuum drying of pharmaceutical powders; vacuum degassing during plastic extrusion; and vacuum melting furnaces for precious metals. These processes involve a large amount of dust during vacuuming. Since the meshing clearance between the rotors of a dry vacuum pump is very small, large dust particles can easily enter the pump chamber if it is not effectively filtered, leading to rotor jamming and equipment blockage. Traditional solutions often use bag filters or single-stage cyclone separators, but these have the following drawbacks:

[0003] (1) When using a bag filter, the bag material has low strength, is easily damaged, and has poor high temperature resistance (usually below 150℃), making it unsuitable for high-temperature process environments; the filtration accuracy is limited by the fiber density of the bag, and high-precision filter bags are easily clogged, requiring frequent shutdowns for backflushing, which affects production efficiency; the backflushing airflow is difficult to penetrate the bag evenly, and residual dust can easily cause secondary clogging.

[0004] (2) The single-stage cyclone separator relies solely on centrifugal force to separate dust, resulting in low separation efficiency for small particles (<10μm); lack of subsequent filtration protection means that unseparated dust will still enter the vacuum pump; manual cleaning of accumulated dust is required, leading to high maintenance costs. Summary of the Invention

[0005] The purpose of this invention is to overcome the above-mentioned shortcomings and provide a backwashing dust filter device for a dry screw pump. Through cyclone separation and stainless steel filter screen dual-stage filtration, combined with pulse backflushing and intelligent differential pressure control, it significantly extends the filter element life, reduces maintenance costs, and ensures the continuous and stable operation of the vacuum pump under dusty conditions.

[0006] The purpose of this utility model is achieved as follows:

[0007] A backwashing dust filter device for a dry screw pump includes a cylindrical shell connected at the top and bottom and a conical hopper at the bottom, wherein the cylindrical shell and the conical hopper constitute a filter housing; the top of the cylindrical shell is open, and a quick-release cover is provided on the top of the cylindrical shell; a support leg is provided on the left and right sides of the conical hopper for supporting the housing.

[0008] The upper part of the cylindrical shell has an air outlet on one side and a compressed gas inlet on the other side. The compressed gas inlet is located on the opposite side of the air outlet on the cylindrical shell. A compressed air inlet flange is provided at the compressed gas inlet. A purge gas inlet pipe passes through the compressed air inlet flange inside the compressed gas inlet. One end of the purge gas inlet pipe extends out of the compressed gas inlet, and the other end is located near the air outlet.

[0009] An air inlet is provided on one side of the lower part of the cylindrical shell, and an air inlet pipe is provided inside the air inlet; a partition is provided between the air inlet and the air outlet, and the partition is located near the air outlet, with the edge of the partition fixed to the inner wall of the cylindrical shell; multiple evenly distributed stainless steel filter cylinders are provided below the partition, and the top surface of the stainless steel filter cylinders is open, with the top surface of the stainless steel filter cylinders located on the bottom surface of the partition.

[0010] The air intake pipe is connected along the tangent of the cylindrical shell to form a cyclone separation chamber;

[0011] The bottom surface of the purge gas inlet pipe is connected to multiple evenly distributed pulse nozzles, each pulse nozzle corresponding to a stainless steel filter cylinder, with each pulse nozzle facing the center of its corresponding stainless steel filter cylinder; a back-purge solenoid valve and a flow regulating valve are provided on the outside of the compressed air inlet flange.

[0012] Furthermore, the backflush solenoid valve is a venting solenoid valve, which introduces inert gas or air to prevent dust explosion.

[0013] Furthermore, the bottom of the conical hopper is provided with a discharge port, and a dust discharge valve is provided at the discharge port.

[0014] Furthermore, an air inlet pneumatic valve is provided at the air inlet, and an air outlet pneumatic valve is provided at the air outlet.

[0015] Furthermore, a differential pressure transmitter is also provided on the outside of the cylindrical shell. The two ends of the differential pressure transmitter are connected to the outer wall positions of the corresponding upper and lower parts of the cylindrical shell of the stainless steel filter screen cylinder. The transmitter monitors the pressure difference between the two ends of the filter screen cylinder online and triggers the PLC control system to automatically execute the vacuum breaking, backflushing, and ash discharge process. It provides the control system with information on the filter screen blockage at any time, ensuring that the filtration system can achieve automatic purging and cleaning.

[0016] Furthermore, the inner walls of the cylindrical shell and the conical hopper are coated with a wear-resistant ceramic coating to extend their service life.

[0017] Furthermore, the stainless steel filter screen cylinder is detachably mounted on the partition.

[0018] An automatic dust and gas vacuum treatment device uses the aforementioned backwashing dust filter device for a dry screw pump. The outlet is connected to the dry vacuum pump via an air extraction pipe. The backwashing dust filter device for the dry screw pump is connected to the dry vacuum pump and an intelligent control box via an air extraction pipe to form an automatic dust and gas vacuum treatment device.

[0019] Compared with the prior art, the beneficial effects of this utility model are:

[0020] This utility model provides a backwashing dust filter device for a dry screw pump. It pre-removes large dust particles by forming a cyclone separation chamber through tangential air intake, combined with secondary filtration using a stainless steel filter cartridge, and integrates pulse backflushing and intelligent differential pressure control to achieve efficient and automated dust filtration. It has the following advantages:

[0021] (1) High-efficiency dual-stage filtration: Cyclone separation pre-removes more than 80% of large dust particles, reducing the load on the filter screen and greatly extending the cleaning cycle; the stainless steel filter screen has high precision (minimum interception particle size 1μm), preventing micro dust from entering the vacuum pump.

[0022] (2) Intelligent automation: The differential pressure transmitter is linked with the PLC to accurately control the backflushing frequency and reduce the number of ineffective cleanings; one-button operation completes vacuum breaking, backflushing and ash removal, reducing manual intervention;

[0023] (3) Easy maintenance: The quick-release cover design allows for filter replacement or deep cleaning within 5 minutes; the modular filter cartridge can be disassembled individually, reducing maintenance costs;

[0024] (4) Safe and reliable: The inert gas vacuum breaking design eliminates the risk of dust explosion; the stainless steel filter has a compressive strength of ≥10MPa, which greatly improves the service life compared with traditional filter bags. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the structure of this utility model.

[0026] Figure 2 This is a schematic diagram of the usage state of this utility model.

[0027] in:

[0028] 1. Cylindrical housing; 2. Air inlet; 2.1 Air inlet pneumatic valve; 3. Stainless steel filter screen; 4. Pulse nozzle; 5. Baffle; 6. Compressed gas inlet; 7. Backflush solenoid valve; 8. Flow regulating valve; 9. Purge gas inlet pipe; 10. Quick-release cover; 11. Air outlet; 11.1 Air outlet pneumatic valve; 12. Differential pressure transmitter; 13. Conical hopper; 14. Support leg; 15. Discharge port; 15.1 Dust discharge valve; 16. Dry vacuum pump; 17. Intelligent control box. Detailed Implementation

[0029] 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

[0030] See Figures 1-2 , Figure 1 A structural schematic diagram of this utility model has been drawn. As shown in the figure, this utility model relates to a backwashing dust filter device for a dry screw pump, which includes a split housing. The split housing is a leak-free filter housing composed of an upper cylindrical housing 1 and a lower conical hopper 13 welded together.

[0031] The top of the cylindrical housing 1 is open, and a quick-release cover plate 10 is provided on the top of the cylindrical housing 1 for quickly opening and closing the filter;

[0032] The conical hopper 13 is provided with a support leg 14 on each of its left and right sides for supporting the shell.

[0033] The cylindrical shell 1 has an air outlet 11 on one side of its upper part and a compressed gas inlet 6 on the other side. The compressed gas inlet 6 is located on the opposite side of the air outlet 11 on the cylindrical shell 1. The compressed gas inlet 6 is provided with a compressed air inlet flange. A purge gas inlet pipe 9 passes through the compressed air inlet flange inside the compressed gas inlet 6. One end of the purge gas inlet pipe 9 extends out of the compressed gas inlet 6, and the other end is located near the air outlet 11.

[0034] An air inlet 2 is provided on one side of the lower part of the cylindrical shell 1, and an air inlet pipe is provided inside the air inlet 2; a partition 5 is provided between the air inlet 2 and the air outlet 11, and the partition 5 is located near the air outlet 11, with the edge of the partition 5 fixed to the inner wall of the cylindrical shell 1; multiple evenly distributed stainless steel filter cylinders 3 are provided below the partition 5, and the top surface of the stainless steel filter cylinder 3 is open, with the edge of the top surface of the stainless steel filter cylinder 3 fixed to the bottom surface of the partition 5. During normal operation, dusty gas enters the filter cylinder from the outside to the inside, large dust particles are blocked on the outside of the filter, while small dust particles are allowed to enter.

[0035] The air inlet pipe is connected along the tangent of the cylindrical shell 1 to form a cyclone separation chamber, which forces the dust-laden gas to rise in a spiral. Large dust particles settle into the conical hopper 13 due to centrifugal force. After the gas enters the filter, it can only rotate. A large amount of dust is separated by the cyclone at the bottom of the filter and placed into the conical hopper 13 at the bottom of the filter, which prevents more dust from being adsorbed onto the filter screen and can extend the cleaning time of the filter screen.

[0036] The bottom surface of the purge gas inlet pipe 9 is connected to multiple evenly distributed pulse nozzles 4. Each pulse nozzle 4 corresponds to a stainless steel filter cylinder 3, with each pulse nozzle 4 facing the center of its corresponding stainless steel filter cylinder 3. The outside of the compressed air inlet flange is provided with a back-purge solenoid valve 7 and a flow regulating valve 8. The back-purge solenoid valve 7 is a venting solenoid valve that introduces inert gas (such as nitrogen) or air to prevent dust explosion.

[0037] The bottom of the conical hopper 13 is provided with a discharge port 15, and a dust discharge valve 15.1 is provided at the discharge port 15.

[0038] An air inlet pneumatic valve 2.1 is provided at the air inlet 2, and an air outlet pneumatic valve 11.1 is provided at the air outlet 11.

[0039] A differential pressure transmitter 12 is also provided on the outside of the cylindrical housing 1. The two ends of the differential pressure transmitter 12 are connected to the upper and lower parts of the outer wall of the cylindrical housing 1 corresponding to the stainless steel filter screen cylinder 3. The transmitter monitors the pressure difference between the two ends of the filter screen cylinder online and triggers the PLC control system to automatically execute the vacuum breaking, backflushing, and ash discharge process. The transmitter provides the control system with information on the filter screen blockage at any time, ensuring that the filtration system can achieve automatic purging and cleaning.

[0040] The cylindrical shell 1 is made of seamless tube or steel plate wound and welded, and the conical hopper 13 is a funnel-shaped annular shell ring made of steel plate wound and welded; the inner walls of the cylindrical shell 1 and the conical hopper 13 are sprayed with wear-resistant ceramic coating to extend their service life.

[0041] The stainless steel filter cylinder 3 is a detachable and replaceable standard filter element cylinder. The quantity is set according to the pumping capacity of the vacuum pump, and the density of the filter screen, i.e., the mesh size, is selected according to the specifications of the dry vacuum pump.

[0042] See Figure 2 , Figure 2A schematic diagram of the usage state of a backwashing dust filter device for a dry screw pump in Embodiment 1 is shown. As shown in the figure, in this embodiment 1, the air outlet 11 of the backwashing dust filter device for a dry screw pump is connected to a dry vacuum pump 16 through an air extraction pipe. The air extraction pipe, the dry vacuum pump 16, and the intelligent control system form a fully automatic dust gas vacuum treatment device; the intelligent control system is provided by the intelligent control box 17.

[0043] This embodiment of a backwashing dust filter device for a dry screw pump can be equipped with a parallel dual filter group (configured with a parallel dual filter group) during use, with one in use and one on standby, to achieve uninterrupted cleaning switching.

[0044] Working principle:

[0045] This utility model provides a backwashing dust filter device for a dry screw pump, including the following main components:

[0046] Backflush solenoid valve: The filter is in a vacuum state during use. The backflush valve introduces inert gas into the filter to change the pressure inside the filter from a vacuum state to a normal pressure state. This can prevent air from flowing back from the dry vacuum pump into the filter and causing dust explosions and other hazards. It plays a certain role in protecting the dry vacuum pump and the filter.

[0047] Dust pulse backflushing device: It consists of a backflushing solenoid valve, a flow regulating valve, a pulse nozzle and connecting pipes, and is installed in the center of the upper part of the filter. The flow regulating valve is used to regulate the flow rate of the backflushing gas, the backflushing solenoid valve is used to open or close the automatic backflushing, and the nozzle can spray compressed gas at a shock wave speed to every part of the filter, so that the dust adhering to the outer wall of the filter screen can be quickly removed from the filter screen and fall into the dust hopper at the bottom of the filter.

[0048] Discharge valve: When the filter discharges dust, the dust in the hopper can be discharged into the dust collection container through this valve; when discharging dust, open the discharge valve and open the solenoid valve of the pulse back-flushing device. Under the action of gravity and the pressure of compressed air blowing, the dust in the hopper is quickly discharged through the discharge valve.

[0049] The differential pressure transmitter monitors the pressure difference between the two ends of the filter cartridge online, providing the control system with information on filter clogging status at any time, ensuring that the filtration system can be automatically purged and cleaned.

[0050] Quick-release cover: Facilitates inspection of the filter cartridge for damage, or allows for deeper cleaning of dust that cannot be completely blown away, or filter cartridge replacement. The filter top cover is secured with multiple sets of quick-release bolts, allowing customers to quickly open and close the cover for rapid cleaning or replacement of the filter cartridge.

[0051] Dust-laden gas enters the filter inlet at a speed of approximately 30 m / s. After entering the filter through the inlet pipe, the gas velocity rapidly decreases to approximately 3 m / s because the filter housing diameter is much larger than the inlet pipe diameter. The dust-laden gas then moves upwards in a spiral motion along the inner ring of the filter housing. Large dust particles, whose suspension force is less than their own weight, fall into the hopper at the bottom of the filter under gravity. Smaller dust particles continue to move upwards under the suspension force of the vacuum pump. The dust reaches the outside of the filter screen, where most of the larger particles are blocked. A small portion of fine dust particles enters the vacuum pump through the gaps in the filter screen. The diameter of these fine dust particles is much smaller than the minimum clearance of the dry vacuum pump, therefore causing almost no damage to the pump. In a vacuum environment, a cyclone separator must be used to effectively separate most of the large dust particles from the pumped gas, forcing the dust to settle into the hopper at the bottom of the filter. This significantly reduces dust adsorption onto the filter screen, extends the filter screen washing cycle, and improves production efficiency.

[0052] When the dust filter is working, its interior is in a vacuum state. If online continuous vacuum pump blowing and dust removal is to be achieved, two sets of filter devices must be configured. One set of filter and vacuum pump runs continuously, while the other set of filter can automatically blow, clean, and automatically discharge dust.

[0053] This utility model's filter, besides being suitable for dry vacuum pumps drawing dusty gases, can also serve as a pre-filter for rotary vane vacuum pumps, slide valve vacuum pumps, liquid ring vacuum pumps, reciprocating vacuum pumps, and Roots screw vacuum units, providing protection for the reliable operation of vacuum pumps and vacuum units. When this utility model's filter is used for humid or dusty gases, a centrifugal separator must be installed before the filter to perform primary separation of the condensate, the drawn gas, and dust in the pre-separator before entering the backflushing filter; this will result in better filtration.

[0054] The automatic cleaning and purging process of the filter in this utility model is as follows:

[0055] (1) When the pressure difference between the two ends of the filter element reaches the preset value of the control system, the control system automatically closes the two pneumatic valves at the filter inlet and outlet.

[0056] (2) Open the vacuum breaking solenoid valve to break the vacuum inside the filter. Whether the gas used to break the vacuum is inert gas or air depends on the dust medium. Otherwise, improper operation may easily cause a dust explosion.

[0057] (3) After the vacuum is broken, place a dust collection container at the bottom of the filter and then open the dust discharge valve at the bottom of the filter;

[0058] (4) Open the compressed gas back-purge solenoid valve. This solenoid valve is pulse-opening and closing. In this way, the purging gas forms a shock wave impact airflow around the inside of the filter element after passing through the pulse nozzle. It cleans and washes the dust outside the filter screen at supersonic speed. The dust falls off the filter screen and into the hopper at the bottom of the filter and is discharged through the discharge valve.

[0059] (5) The purging time and opening and closing frequency of the solenoid valve have been preset in the PLC. Users can automatically purge and rinse the filter and automatically unload dust with just one key operation.

[0060] 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. A backflushing dust filter device for dry-running screw pumps, characterized in that: The utility model relates to a filter shell, which comprises a cylindrical shell (1) and a lower conical hopper (13) connected to each other, the top of the cylindrical shell (1) is open, a quick-release cover plate (10) is arranged above the top of the cylindrical shell (1), and a supporting leg (14) is arranged on each side of the conical hopper (13) for supporting the shell. An air outlet (11) is arranged on one side of the upper part of the cylindrical shell (1), a compressed gas inlet (6) is arranged on the other side of the upper part of the cylindrical shell (1), the compressed gas inlet (6) is arranged on the side opposite to the air outlet (11) of the cylindrical shell (1), a compressed air inlet flange is arranged at the compressed gas inlet (6), a purge gas inlet pipe (9) is arranged in the compressed gas inlet (6) through the compressed air inlet flange, one end of the purge gas inlet pipe (9) extends out of the compressed gas inlet (6), and the other end of the purge gas inlet pipe (9) is arranged close to the air outlet (11). An air inlet (2) is arranged on one side of the lower part of the cylindrical shell (1), the air inlet (2) is provided with an air inlet connecting pipe, a partition plate (5) is arranged between the air inlet (2) and the air outlet (11), the partition plate (5) is arranged close to the air outlet (11), the edge of the partition plate (5) is fixed to the inner wall of the cylindrical shell (1), a plurality of stainless steel filter screen cylinders (3) are arranged below the partition plate (5), the top surface of the stainless steel filter screen cylinder (3) is open, and the top surface of the stainless steel filter screen cylinder (3) is arranged on the bottom surface of the partition plate (5). The air inlet connecting pipe is connected along the tangent of the cylindrical shell (1) to form a cyclone separation chamber. The bottom surface of the purge gas inlet pipe (9) is connected with a plurality of uniformly distributed pulse nozzles (4), the pulse nozzles (4) correspond to the stainless steel filter screen cylinders (3) one by one, each pulse nozzle (4) is opposite to the center position of the corresponding stainless steel filter screen cylinder (3), and the outer side of the compressed air inlet flange is provided with a back purge solenoid valve (7) and a flow regulating valve (8).

2. A backflushing dust filter device for dry-running screw pumps according to claim 1, characterized in that The back purge solenoid valve (7) is a broken vacuum solenoid valve, inert gas or air is introduced into the broken vacuum solenoid valve (7) to prevent dust explosion.

3. A backflushing dust filter device for dry-running screw pumps according to claim 1, characterized in that: The bottom of the conical hopper (13) is provided with a discharge port (15), and the discharge port (15) is provided with a dust discharge valve (15.1).

4. A backflushing dust filter device for dry-running screw pumps according to claim 1, characterized in that: An air inlet pneumatic valve (2.1) is arranged at the air inlet (2), and an air outlet pneumatic valve (11.1) is arranged at the air outlet (11).

5. A backflushing dust filter device for dry-running screw pumps according to claim 1, characterized in that: The outer side of the cylindrical shell (1) is further provided with a differential pressure transmitter (12), the two ends of the differential pressure transmitter (12) are connected to the outer wall of the corresponding cylindrical shell (1) above and below the stainless steel filter screen cylinder (3), the pressure difference between the two ends of the filter screen cylinder is monitored in real time, the PLC control system is triggered to automatically execute the broken vacuum, back blowing and dust removal processes, the filter screen clogging condition is provided for the control system at any time, and the automatic blowing and cleaning of the filter system are ensured.

6. A backflushing dust filter device for dry-running screw pumps according to claim 1, characterized in that: The inner walls of the cylindrical shell (1) and the conical hopper (13) are sprayed with wear-resistant ceramic coating to prolong the service life.

7. A backflushing dust filter device for dry-running screw pumps according to claim 1, characterized in that: The stainless steel filter screen cylinder (3) is detachably arranged on the partition plate (5).

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