Design of dust cleaning system for pressure stabilizing air tank in bag filter

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1. The basic form of the air tank: https://pic4.zhimg.com/v2-d621b2cfb6d9473c6c7be187fbf9ddbd_r.jpg?source=1940ef5c2. The volume of the air tank is determined based on practical experience; after pulse jetting, the pressure drop within the tank should not exceed 30% of the original storage pressure. That is, the volume of the air source tank is determined by the maximum air consumption per pulse jet of the pulse valve selected as the base model. For a certain model of pulse valve, two air reservoirs with different volumes were used; blowing tests were conducted under the same air source pressure while maintaining identical pulse signals: https://pic1.zhimg.com/v2-78869b3180edea91496e69b7fb3192d0_r.jpg?source=1940ef5c. As can be seen from the comparison of the blowing parameters in the table: ① The pressure drop during the last blowing cycle for this pulse valve using the larger air reservoir was only 18% of the original pressure, and its peak blowing pressure was much higher than that achieved when using the smaller air reservoir ； ②This pulse valve delivers a large volume of air when spraying on the air tank. The greater the injection pressure, the more pronounced the effect of the air pocket size. It can be seen that when a pulse valve is equipped with a large air tank, the pulse jetting effect is significantly better than that with a small air tank. Therefore, it is reasonable and feasible to determine the volume of the air source tank based on the maximum air consumption of the pulse valve. The formula for calculating the minimum volume of the air tank is as follows: https://pic4.zhimg.com/v2-6e2c8b26c75edb30a1c6d59563caa4ee_r.jpg?source=1940ef5c3. Key points for air tank design: ① Design pressure: 0.4 MPa for low-pressure pulse valves and 0.7 MPa for high-pressure pulse valves; the hydraulic test requires a pressure equal to 1.3 times the design pressure. ②The material for the gas distribution box can be Q235, 20g, or 20R, and a steel quality certificate from the manufacturing unit is required. ③The gas distribution box uses single-sided welds, no non-destructive testing is performed, and the weld coefficient is set at 0.7. ④The corrosion allowance for the steel plates of the gas distribution box should be considered to be no less than 1 mm. ⑤Circular gas distribution boxes are generally made of 300–400 mm steel pipes, with standard elliptical end caps at both ends; they must comply with the relevant regulations of pressure vessel standards, and the height h of the straight edges of the end caps should be ≥ 25 mm. Standard elliptical head and circular flat cover heads are shown in the image: https://pic1.zhimg.com/v2-43a75172c57cdd6afa105d8045657f3d_r.jpg?source=1940ef5c. A row of pulse valves is installed on the gas distribution box; the connection between these valves and the piping is usually made using flanges. For circular gas distribution boxes, holes are made in the side of the cylinder body and flanges are welded to them; these flanges are connected to the submersed pulse valves, and their structural dimensions are shown in the figure. The outer diameter D and inner diameter of the flange should match those of the pulse valve chassis, while the thickness S3 should be 1–2 times the nominal thickness, and must not be less than 10 mm. ⑦Calculation of the cylinder thickness for simplified gas distribution boxes: https://pic2.zhimg.com/v2-f60ca718050a2e8554180dd53feeed22_r.jpg?source=1940ef5c4. Hebei Chuxin Environmental Protection produces and installs air tanks; these tanks come in various shapes. Whether they are designed with a circular or square cross-section, it is necessary to consider safety, reliability, and quality standards. Design can be carried out with reference to JB/T10191 \"Safety Requirements for Bag Filters – Air Distribution Boxes for Pulse-Jet Bag Filters\" or in accordance with pressure vessel standards. The diameter of the air inlet pipe for the air tank should be as large as possible to meet the air supply rate. For large-capacity air tanks, multiple air inlet pipelines can be designed. For large container air tanks, pipes of 3 inches or larger can be used to connect multiple tanks into a gas storage circuit. The pulse valve is installed at the top or side of the air tank, to prevent oil and moisture inside the air tank from being blown into the filter bags through the pulse valve. Each air pocket must be equipped with an automatic or manual oil and water discharge valve to periodically remove impurities from within the container. If the air tank is designed in accordance with pressure vessel standards and has a sufficiently large volume, its body itself functions as a stabilizing tank for compressed kiln gas, eliminating the need for an additional gas storage tank. When there is an additional pressure-stabilizing air storage tank in front of the air tank, it is necessary to install the pressure-stabilizing air storage tank as close as possible to the air tank, in order to prevent the compressed air from losing pressure as it passes through long and narrow pipes during transmission. After processing and production, the air tank must be continuously blown with compressed air to clean out the internal slag, before the valves can be installed. When testing pulse valves in the workshop, especially 3\" submersion valves, it is necessary to ensure the pressure of the compressed air in the air tank as well as the supply flow rate; otherwise, the pulse valve will not open or will leak air. If, after installation on site, it is found that the upper air outlet of the valve is leaking, this is due to impurities present in the air tank; these impurities such as dust particles, ice, rust, and other contaminants accumulate on the small diaphragm, preventing it from closing properly. It is necessary to remove the small diaphragm in order to clean it. The air tank should be equipped with a safety valve, pressure gauge, and exhaust valve. The safety valve can be configured with a spring-loaded slightly open safety feature.