Self-cleaning filtration system of nitrogen generator

Abstract

This invention relates to the field of nitrogen generator technology, and provides a self-cleaning filtration system for a nitrogen generator, including a primary pre-filtration chamber and a precision filtration chamber connected in series along the airflow direction, as well as a backflush air source system, a differential pressure monitoring device, a dust removal system, and a control system. The backflush air source system includes an air tank, a pressure reducing valve, and a backflush pipeline. The air inlet of the air tank is connected to the nitrogen outlet of the nitrogen generator through a branch pipe, and the air outlet is connected to the pressure reducing valve, the main backflush pipeline, and the backflush branch pipe. Each backflush branch pipe is connected to the backflush valve of the corresponding precision filter element on the precision filtration chamber. This invention can achieve online self-cleaning without stopping the machine, accurately match the cleaning time, use the nitrogen generated by the nitrogen generator as the backflush air source, simplify the structure, and reduce costs.

Description

Technical Field

[0001] This invention relates to the field of nitrogen generator technology, and more specifically, to a self-cleaning filtration system for nitrogen generators. Background Technology

[0002] As a key piece of equipment for obtaining nitrogen in industrial production, the efficiency and purity of nitrogen generators directly depend on the cleanliness of the incoming air. Existing nitrogen generators are usually equipped with an intake air filtration system to remove dust, impurities, and other contaminants from the air, in order to protect the downstream adsorbents (such as the carbon molecular sieves in PSA nitrogen generators) or membrane modules (such as the polymer membranes in membrane separation nitrogen generators) and prevent them from failing prematurely due to contamination.

[0003] However, traditional nitrogen generator filtration systems have significant drawbacks: First, filter elements are easily clogged by dust during long-term use, requiring manual replacement or disassembly for cleaning, which seriously affects the continuous operation of the nitrogen generator. This is especially true in high-dust industrial settings such as mining and metallurgy, where filter element replacement is extremely frequent, significantly increasing labor and consumable costs. Second, the timing of cleaning depends on manual judgment, which can easily lead to increased air intake resistance and decreased nitrogen generation efficiency due to untimely cleaning, or excessive cleaning resulting in energy waste. Third, some self-cleaning filtration solutions require additional high-pressure air sources, which are complex in structure and expensive, making them difficult to adapt to the industrialization needs of industrial scenarios.

[0004] To address the aforementioned issues, there is an urgent need to design a filtration system that is simple in structure, highly reliable, and capable of continuous online cleaning, adaptable to the industrial application scenarios of nitrogen generators, extending filter life and reducing maintenance costs. Summary of the Invention

[0005] To overcome the shortcomings mentioned above, this invention aims to provide a self-cleaning filtration system for nitrogen generators, which can achieve online self-cleaning without stopping the machine, accurately match the cleaning time, use nitrogen generated by the nitrogen generator as the backflushing gas source, simplify the structure and reduce costs.

[0006] The self-cleaning filtration system of the nitrogen generator includes a primary pre-filtration chamber and a precision filtration chamber connected in series along the airflow direction, as well as a backflush air source system, a differential pressure monitoring device, a dust removal system, and a control system.

[0007] The inlet of the primary pre-filtration chamber is connected to the outside air, and the outlet is detachably connected to the inlet of the precision filtration chamber. The outlet of the precision filtration chamber is connected to the inlet of the nitrogen generator through a pipeline. Multiple precision filter elements are installed in parallel inside the chamber, and each precision filter element is equipped with an independent inlet valve, outlet valve and backflush valve.

[0008] The backflush gas source system includes a gas storage tank, a pressure reducing valve, and a backflush pipeline. The gas inlet of the gas storage tank is connected to the nitrogen outlet of the nitrogen generator through a branch pipe. The gas outlet is connected to the pressure reducing valve, the backflush main pipeline, and the backflush branch pipe. Each of the backflush branch pipes is connected to the backflush valve corresponding to the precision filter element on the precision filter chamber.

[0009] The differential pressure monitoring device includes a differential pressure sensor. The high-pressure end interface of the differential pressure sensor is connected to the air inlet side of the filter element of the precision filter chamber, the low-pressure end interface is connected to the air outlet side of the filter element of the precision filter chamber, and the signal output end is connected to the control system.

[0010] The dust removal system includes a conical dust collection hopper and an electric dust removal valve. The upper end of the conical dust collection hopper is connected to the bottom dust discharge port of the precision filter chamber, and the lower end is connected to the electric dust removal valve. The control terminal of the electric dust removal valve is electrically connected to the control system.

[0011] The control system includes a PLC controller and a touch screen. The signal input terminal of the PLC controller is connected to a differential pressure sensor, and the signal output terminal is connected to the air inlet valve, the air outlet valve, the backflush valve, and the electric dust removal valve, respectively.

[0012] Furthermore, the primary pre-filtration chamber has a built-in primary metal mesh filter element with a filtration accuracy of 10μm, and a rainproof and dustproof cap is installed at the air inlet.

[0013] Furthermore, both the precision filter chamber and the primary pre-filter chamber are made of 304 stainless steel, and the precision filter element has a filtration accuracy of 0.1μm and is made of polytetrafluoroethylene.

[0014] Furthermore, the gas storage tank has a volume of 50L, and the pressure reducing valve adjusts the nitrogen pressure to 0.6-. The differential pressure sensor is a diffused silicon type, with a measurement range of 0-0.2MPa and an accuracy of 0.5 grade. The signal output terminal is connected to the PLC controller through a shielded cable.

[0015] Furthermore, the dust removal system also includes a dust collection bag, which is fitted onto the outlet end of the electric dust removal valve.

[0016] Furthermore, the intake valve, the outlet valve, and the backflush valve are all pneumatic solenoid valves.

[0017] Furthermore, the touch screen of the control system is connected to the PLC controller for setting the differential pressure threshold, backflushing duration and dust removal duration, and displaying the equipment's working status in real time.

[0018] Compared with the prior art, the beneficial effects of the present invention are:

[0019] ① In this invention, online self-cleaning without stopping the machine can be achieved. The precision filter chamber adopts a multi-filter element parallel structure. Each filter element is equipped with an independent valve, which can be isolated and cleaned separately. The other filter elements work normally, ensuring that the nitrogen generator's air intake is uninterrupted and improving the equipment's continuous operation capability.

[0020] ② In this invention, the filter element clogging status is monitored in real time by a differential pressure sensor, and cleaning is automatically triggered when a preset threshold is reached, avoiding the subjectivity of manual judgment and preventing untimely or excessive cleaning.

[0021] ③ In this invention, nitrogen generated by the nitrogen generator is used as the backflushing gas source, eliminating the need for additional air compressors and other gas source equipment. This also simplifies pipeline design and reduces equipment purchase and operating costs.

[0022] ④ In this invention, dust adhering to the surface of the filter element is removed by regular backflushing cleaning, which extends the life of the filter element, reduces the frequency of filter element replacement, and reduces the cost of consumables and labor maintenance. Attached Figure Description

[0023] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used in conjunction with embodiments of the invention to explain the invention and do not constitute a limitation thereof. In the drawings:

[0024] Figure 1 This is a schematic diagram of the overall structure of the self-cleaning filtration system of the nitrogen generator;

[0025] Figure 2 This is a partial sectional view of the structure;

[0026] Figure 3 This is a schematic diagram of the interior of a precision filter chamber;

[0027] Figure 4 This is a partial structural diagram of the self-cleaning filtration system of a nitrogen generator.

[0028] In the diagram: 1. Primary pre-filtration chamber; 11. Primary metal mesh filter element; 2. Precision filtration chamber; 21. Precision filter element; 22. Inlet pipe; 23. Exhaust pipe; 24. Fixing ring; 25. Inlet valve; 26. Outlet valve; 27. Backflush valve; 3. Backflush air supply system; 31. Air storage tank; 32. Pressure reducing valve; 33. Backflush main pipe; 34. Backflush branch pipe; 35. Shut-off valve; 4. Differential pressure monitoring device; 5. Dust removal system; 51. Conical dust collection hopper; 52. Electric dust removal valve; 53. Dust collection bag; 6. Control system; 7. Nitrogen generator. Detailed Implementation

[0029] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0030] like Figure 1-4 As shown in the figure, this embodiment discloses a self-cleaning filtration system for a nitrogen generator. It includes a primary pre-filtration chamber 1, a precision filtration chamber 2, a backflushing air source system 3, a differential pressure monitoring device 4, a dust removal system 5, and a control system 6. The primary pre-filtration chamber 1 and the precision filtration chamber 2 are connected in series along the airflow direction. The backflushing air source system 3 and the precision filtration chamber 2 form a side loop. The differential pressure monitoring device 4 is installed on the precision filtration chamber 2. The dust removal system 5 is located directly below the precision filtration chamber 2. The control system 6 is electrically connected to each actuator and sensor via cables.

[0031] like Figure 1-4 As shown, the primary pre-filtration chamber 1 adopts a cylindrical cavity structure made of 304 stainless steel. It is placed vertically with the air inlet facing downwards and equipped with a rainproof and dustproof cap. The air outlet faces upwards and is detachably connected to the air inlet of the precision filtration chamber 2 via a flange. Inside, there is a built-in primary metal mesh filter element 11 (filtration accuracy 10μm). The primary filter element is placed vertically along with the cavity to intercept large particles of dust, leaves and other impurities in the outside air. This vertical placement design facilitates the initial settling of dust under gravity, reduces the surface adhesion pressure of the primary filter element, and also facilitates the later maintenance and replacement of the primary filter element.

[0032] like Figure 1-4 As shown, the precision filter chamber 2 is also a cylindrical cavity made of 304 stainless steel. It is placed vertically and connected to the inlet pipe 22 and the exhaust pipe 23. The bottom of the precision filter chamber 2 is provided with a dust discharge port for connection to the dust discharge system 5. The inlet pipe 22 is connected to the outlet flange of the primary pre-filter chamber 1, and the exhaust pipe 23 is connected to the inlet of the nitrogen generator 7 main unit (PSA type). Four precision filter elements 21 (filtration accuracy 0.1μm, material is polytetrafluoroethylene) are installed in parallel inside. The four filter elements are placed vertically and evenly distributed in the cavity. The precision filter element 21 adopts a cylindrical hollow structure and is cylindrical in shape. It is fixed to the inner wall of the precision filter chamber 2 by the fixing ring 24. The side wall of the filter element is a polytetrafluoroethylene filter membrane (with pores of only 0.1μm, used to intercept fine dust). It only allows gas to enter the inner side of the filter element (outlet side) through the filter membrane from the outside of the filter element (inlet side). It cannot pass through the sealing structure of the side wall of the filter element and the pore restriction of the filter membrane (non-gas flow path). The vertically placed filter element allows the dust that falls off during backflushing to slide directly to the bottom conical structure under the action of gravity, avoiding dust accumulation on the surface of the filter element or the inner wall of the chamber.

[0033] like Figure 1-4 As shown, each filter element has an inlet valve 25 and an outlet valve 26 installed at its upper sealing flange. The inlet valve 25 connects the inlet pipe 22 inside the precision filter chamber 2 to the outside of the filter element (inlet side), controlling the airflow into a single filter element. The outlet valve 26 connects the inside of the filter element (outlet side) to the outlet pipe inside the precision filter chamber 2, controlling the discharge of the filtered airflow from a single filter element. Each filter element has a backflush valve 27 installed at its lower sealing flange. The backflush valve 27 connects the backflush branch pipe 34 to the inside of the filter element (outlet side), controlling the entry of backflush nitrogen. The inlet valve 25, outlet valve 26, and backflush valve 27 are all pneumatic solenoid valves, connected to the control system 6 via independent cables to achieve independent control of a single filter element. The bottom conical structure of the precision filter chamber 2 has a dust discharge port for discharging dust that falls off during backflush.

[0034] like Figure 1-4 As shown, the backflush gas supply system 3 includes a gas storage tank 31, a pressure reducing valve 32, a backflush main pipeline 33, and a backflush branch pipe 34. The gas storage tank 31 has a volume of 50L. Its inlet end draws gas from the nitrogen outlet of the nitrogen generator 7 through the branch pipe. A shut-off valve 35 is installed on the branch pipe to control the gas supply. The input end of the pressure reducing valve 32 is connected to the outlet end of the gas storage tank 31 to adjust the nitrogen pressure to 0.8MPa (to meet backflush requirements). One end of the backflush main pipeline 33 is connected to the output end of the pressure reducing valve 32, and the other end is connected to the backflush branch pipe 34. The backflush branch pipe 34 is connected to the backflush valves 27 corresponding to the four filter elements on the precision filter chamber 2 to achieve precise backflush of a single filter element.

[0035] like Figure 1-4 As shown, the differential pressure monitoring device 4 uses a diffused silicon differential pressure sensor with a measurement range of 0-0.2 MPa and an accuracy of 0.5 grade. The high-pressure end interface of the differential pressure sensor is connected to the air inlet side of the filter element in the precision filter chamber 2 (i.e., the pipeline between the air inlet valve 25 and the filter element) through a copper pipe, and the low-pressure end interface is connected to the air outlet side of the filter element in the precision filter chamber 2 (i.e., the pipeline between the air outlet valve 26 and the filter element) through a copper pipe, which is used to collect the differential pressure data at both ends of a single filter element in real time. The signal output end of the differential pressure sensor is connected to the PLC controller of the control system 6 through a shielded cable to ensure stable signal transmission.

[0036] like Figure 1-4As shown, the dust removal system 5 includes a conical dust collection hopper 51, an electric dust discharge valve 52, and a dust collection bag 53. The upper end of the conical dust collection hopper 51 is connected to the dust discharge port at the bottom of the precision filter chamber 2 via a flange, and the inner wall is polished to facilitate dust sliding off. The electric dust discharge valve 52 is installed at the lower end of the conical dust collection hopper 51, and its control end is connected to the control system 6 via a cable. The dust collection bag 53 is fitted and fixed to the outlet end of the electric dust discharge valve 52 to collect the discharged dust and avoid secondary pollution. Optionally, a level sensor (capacitive type) is installed inside the conical dust collection hopper 51, and the signal output end of the level sensor is connected to the control system 6 to monitor the amount of dust accumulation.

[0037] like Figure 1-4 As shown, the control system 6 includes a PLC controller (model S7-200SMART), a touch screen (7-inch), and a relay module. The signal input terminals of the PLC controller are connected to a differential pressure sensor and a level sensor (optional), respectively. The signal output terminals are connected to the inlet valve 25, outlet valve 26, backflush valve 27, electric dust removal valve 52, and the shut-off valve 35 of the backflush air source system 3 through the relay module. The touch screen is connected to the PLC controller for setting parameters such as differential pressure threshold (in this embodiment, the initial differential pressure is 0.02MPa and the blockage threshold is 0.1MPa), backflush duration (set to 10s), and dust removal duration (set to 5s), and displays the differential pressure status of each filter element, valve working status, and fault alarm information in real time. The control system 6 is integrated into a wall-mounted control box, which is installed on the side of the nitrogen generator 7 main unit for easy operation and maintenance.

[0038] The working principle of the self-cleaning filtration system of the nitrogen generator 7 in this embodiment is as follows: The working process of this system includes a normal filtration stage, a differential pressure monitoring stage, a filter element isolation stage, a backflushing cleaning stage, a recovery stage, and a dust removal stage, as detailed below:

[0039] Normal filtration stage: Control system 6 controls the opening of the inlet valve 25 and outlet valve 26 of all precision filter elements 21, and the closing of the backflush valve 27; After the outside air is intercepted by large particulate impurities in the primary pre-filtration chamber 1, it enters the inlet chamber of the precision filtration chamber 2, and flows to the outside of each filter element (inlet side) through the opened inlet valve 25. Then the air passes through the polytetrafluoroethylene filter membrane on the side wall of the filter element (it can only permeate from the outside to the inside and cannot pass through the sealed part of the side wall of the filter element), and enters the inside of the filter element (outlet side). During this process, the fine dust in the air is intercepted by the filter membrane on the outside of the filter element; The filtered clean air enters the outlet chamber of the precision filtration chamber 2 through the opened outlet valve 26, and finally enters the nitrogen generator 7 main unit through the pipeline for nitrogen generation; At the same time, the gas storage tank 31 of the backflush gas source system 3 obtains clean nitrogen from the nitrogen outlet of the nitrogen generator 7 main unit through the branch pipe and stores it to the preset pressure (0.8MPa).

[0040] Differential pressure monitoring stage: The differential pressure sensor collects the differential pressure data at both ends of each filter element in real time and transmits the data to the PLC controller; the PLC controller compares the real-time differential pressure with the preset clogging threshold (0.1MPa) to determine whether the filter element is clogged.

[0041] Filter element isolation stage: When the real-time pressure difference of a filter element reaches 0.1MPa, the PLC controller determines that the filter element is blocked and immediately controls the corresponding air inlet valve 25 and air outlet valve 26 to close, isolating it from the main airflow; the other three filter elements keep the air inlet valve 25 and air outlet valve 26 open and continue to perform filtration operations, ensuring that the air inlet flow of the nitrogen generator 7 is stable and production is not interrupted.

[0042] Backflush cleaning stage: After the filter element is isolated, the PLC controller controls the backflush valve 27 corresponding to the filter element to open. High-pressure nitrogen gas (0.8MPa) in the gas tank 31 enters the inside of the filter element (outlet side) through the backflush main pipe 33 and backflush branch pipe 34. It impacts the filter membrane on the side wall of the filter element at high speed in the opposite direction to the normal filtration direction (from the inside to the outside), blowing off the dust intercepted on the outside of the filter element. The backflush time is maintained at 10 seconds to ensure that the dust is completely removed. The removed dust falls into the conical structure at the bottom of the precision filter chamber 2.

[0043] Recovery phase: After the backflushing cleaning is completed, the PLC controller controls the backflushing valve 27 to close, and after a 2-second delay, reopens the corresponding air inlet valve 25 and air outlet valve 26, and the filter element resumes its filtration function; at the same time, the PLC controller records the number of times and the time of cleaning of the filter element for easy traceability in subsequent maintenance.

[0044] Rotation cleaning mechanism: The PLC controller performs the above isolation, backflushing, and recovery processes on the filter elements that reach the pressure difference threshold in a preset order (from filter element 1 to filter element 4), thereby realizing the rotation cleaning of multiple filter elements and ensuring the continuous operation of the overall filtration.

[0045] Dust removal stage: The dust that falls off during backflushing falls into the conical dust collection hopper 51 at the bottom of the precision filter chamber 2; if a level sensor is configured, when the level sensor detects that the amount of dust accumulation has reached the preset value, the PLC controller controls the electric dust removal valve 52 to open, and the dust falls into the dust collection bag 53, with a dust removal time of 5 seconds; after the dust removal is completed, the electric dust removal valve 52 closes; if no level sensor is configured, a timed dust removal mode can be set, and the dust removal process will be automatically executed once after every 3 cleaning cycles.

[0046] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A self-cleaning filtration system for a nitrogen generator, characterized in that: It includes a primary pre-filter chamber (1) and a precision filter chamber (2) connected in series along the airflow direction, as well as a backflush air source system (3), a differential pressure monitoring device (4), a dust removal system (5), and a control system (6). The inlet of the primary pre-filtration chamber (1) is connected to the outside air, and the outlet is detachably connected to the inlet of the precision filtration chamber (2). The outlet of the precision filtration chamber (2) is connected to the inlet of the nitrogen generator (7) through a pipeline. Multiple precision filter elements (21) are installed in parallel inside the chamber. Each precision filter element (21) is equipped with an independent inlet valve (25), outlet valve (26) and backflush valve (27). The backflush gas source system (3) includes a gas storage tank (31), a pressure reducing valve (32) and a backflush pipeline. The gas inlet of the gas storage tank (31) is connected to the nitrogen outlet of the nitrogen generator (7) through a branch pipe. The gas outlet is connected to the pressure reducing valve (32), the backflush main pipeline (33) and the backflush branch pipe (34). Each of the backflush branch pipes (34) is connected to the backflush valve (27) on the precision filter chamber (2) corresponding to the precision filter element (21). The differential pressure monitoring device (4) includes a differential pressure sensor. The high-pressure end interface of the differential pressure sensor is connected to the air inlet side of the filter element of the precision filter chamber (2), the low-pressure end interface is connected to the air outlet side of the filter element of the precision filter chamber (2), and the signal output end is connected to the control system (6). The dust removal system (5) includes a conical dust collection hopper (51) and an electric dust removal valve (52). The upper end of the conical dust collection hopper (51) is connected to the bottom dust discharge port of the precision filter chamber (2), and the lower end is connected to the electric dust removal valve (52). The control terminal of the electric dust removal valve (52) is electrically connected to the control system (6). The control system (6) includes a PLC controller and a touch screen. The signal input terminal of the PLC controller is connected to a differential pressure sensor, and the signal output terminal is connected to the air inlet valve (25), the air outlet valve (26), the backflush valve (27), and the electric dust discharge valve (52), respectively.

2. The self-cleaning filtration system of the nitrogen generator according to claim 1, characterized in that: The primary pre-filtration chamber (1) has a built-in primary metal mesh filter element (11) with a filtration accuracy of 10μm, and a rainproof and dustproof cap is installed at the air inlet.

3. The self-cleaning filtration system of the nitrogen generator according to claim 1, characterized in that: The precision filter chamber (2) and the primary pre-filter chamber (1) are both made of 304 stainless steel. The precision filter element (21) has a filtration accuracy of 0.1μm and is made of polytetrafluoroethylene.

4. The self-cleaning filtration system of the nitrogen generator according to claim 1, characterized in that: The gas storage tank (31) has a volume of 50L, and the pressure reducing valve (32) adjusts the nitrogen pressure to 0.6-1.0MPa.

5. The self-cleaning filtration system of the nitrogen generator according to claim 1, characterized in that: The differential pressure sensor is a diffused silicon type, with a measurement range of 0-0.2MPa and an accuracy of 0.5 class. The signal output terminal is connected to the PLC controller through a shielded cable.

6. The self-cleaning filtration system of the nitrogen generator according to claim 1, characterized in that: The dust removal system (5) also includes a dust collection bag (53), which is fitted onto the outlet end of the electric dust removal valve (52).

7. The self-cleaning filtration system of the nitrogen generator according to claim 1, characterized in that: The air intake valve (25), the air outlet valve (26), and the backflush valve (27) are all pneumatic solenoid valves.

8. The self-cleaning filtration system of the nitrogen generator according to claim 1, characterized in that: The touch screen of the control system (6) is connected to the PLC controller for setting the differential pressure threshold, backflushing time and dust removal time, and displaying the working status of the equipment in real time.

Images