Bag filters work based on bag filter technology. It filters and captures dust through bags. Its main parts include filter bags. It also includes pulse controllers, pulse valves, air inlets, and air outlets.
Structural design of the middle box
The middle box body is made up of several wall panels connected by continuous welding. The wall panels in the middle box body are typically made of ordinary steel plates with a thickness of 5mm. The inclined partition assembly is located at the center of the box body. It separates the dust gas chamber from the clean air chamber. The middle box body primarily focuses on the ability of the wall panels. It also considers inclined partitions. They must be able to withstand negative pressure. The middle box body’s pressure resistance is negative. It is typically calculated based on the fan’s total pressure. Its calculation is similar to that of the ash hopper part.
Structural design of upper box
The upper box body is a crucial component of the entire dust collector design. The quality of its design is directly proportional to its functionality. When designing the upper box body, arrange the flower plate holes in a reasonable manner. Consider the height and orientation of the offline holes. In the case of internal bypass, we must also consider the impact on offline holes. They are related to bypass holes. Verifying the strength of the upper box is key. The strength of the box is as important. When designing the upper box body, it should have a slope. This slope helps regulate the flow of rainwater.
Flower plate hole layout
The holes of the flower plate should be evenly arranged in the upper box. Based on what is on site and factory experience, when the filter bag is under 8m long, the gap between the holes is 1.5 times their diameter. For example, if a 160×6000 filter bag is used, the distance between the holes is 240mm.
Upper box cross section height
We mainly set the height of the top box to ensure even gas flow. This also ensures that the airflow resistance is not too high. This is because the upper box is not too small. If it is too small, the fan may not have enough suction and cannot work normally. I have years of design experience. The wind speed in the upper box should not exceed 3m/s.
Strength calculation of flower plate frame
The flower plate frame is covered with flower plate filter bags and bag cages. Installing them requires very strict flatness. The tolerance is generally 1:1000. In this case, the flower plate frame must be strong enough. The filter bag must be cleaned to prevent dust from gathering. Dust could harm the flatness of the flower plate. This harm would happen when operators inspect and maintain it.
Design of injection system
The injection system has a pulse valve. It also has an injection air bag, an injection pipe, and connector pipes. The injection system is the core component of the bag dust collector. Its design quality can determine whether the dust collector can be used normally. When designing the injection system, pay attention to the choice of the pulse valve. Also consider the size of the injection air bag and the design of the injection pipe’s structure.
Determination of air volume
The air bag must work even when a single pulse valve is blown. After this, the pressure in the air bag drops to 70% of its original pressure. When designing the air bag capacity, use the minimum capacity to find the bag’s minimum volume. Then, based on this, the volume of the air bag is expanded. The larger the volume of the air bag, the more stable the working air pressure in the air bag. We can also design the air bag’s specifications first. Then, we can calibrate it to the minimum working capacity. The design capacity should exceed the minimum working capacity. Generally, the air bag’s working capacity should be 2 to 3 times the minimum capacity.
Design of dust hopper for bag filter
When designing the hopper of a bag filter, attention should be paid to the stickiness of the dust. Another thing to note is the angle and capacity of the hopper. Large dust collectors usually have multiple hoppers. The hoppers have level meters. They also have vibrators, air cannons, detection doors, star-shaped dischargers, and screw conveyors. The angle between the wall and the ground should be greater than the body’s resting angle. The hopper of a bag filter can be blocked by a vibrating motor. An air cannon can break up the bonded ash. Air cannons are more commonly used in lime kiln dust removal systems.
Ash discharge device
The dust discharge device is a key part of the dust collector. It has a big impact on the operation and dust collection efficiency of the collector. The dust collector mostly operates at negative pressure. If there is air leakage, it will disrupt the air flow in its flow field. This disruption makes it hard to separate the dust from the gas. Data shows that for a cyclone dust collector, 5% air leakage cuts efficiency by 50%. At 15% leakage, efficiency falls to 0. So, the collector’s effectiveness depends a lot on how well the discharge device is sealed. There are various types of air lock devices installed here. They ensure the tightness of the dust discharge port. The commonly used dry dust discharge devices in China are flash valves and rotary valves.
Control cabinet
The bag filter control system has a few main parts. These include the pulse jet controller and BMC control cabinet. They also include a heat resistance thermometer. They have a static pressure point and a material level indicator. They also include other measuring elements. These parts work together. They keep the dust collector stable and efficient. The measuring element in the control system is the “sensing organ. It collects various operating parameters, like temperature, pressure, and material level, and accurately measures these components. It provides reliable data to the control system, ensuring it runs stably and efficiently.
