1、 The development process and market status of bag filter. Bag filter is an older dust removal technology that has been applied since the 1880s. At that time, only some hanging bags were used, resulting in low work efficiency. In 1881, the commercial production of mechanical vibration cleaning bag dust collectors in German factories began. In 1954, the reverse jet type blowing ring dust cleaning technology was invented, which enabled the bag filter to; Continuous dust removal and cleaning operations have been achieved, resulting in a several fold increase in processing capacity and a relatively stable filter bag pressure. Especially the pulse jet type (pulse) bag filter invented in 1957 is considered a major discovery in bag dust removal technology. It not only operates and cleans continuously, but also stabilizes the pressure loss of the filter bag, further increases the processing capacity, and has no moving parts inside. The filter cloth has a long service life and a simple structure. After the 1970s, bag filter technology developed towards large-scale production. Some, combined with large-scale industrial production, have successively applied large-scale bag filters to coal-fired power plants, dry cement rotary kiln tail and electric furnace dust removal. There are many cases where the area of a single filter exceeds 10000m2. There is a huge demand for bag filters in China, and dust removal filter materials, especially fiber filter materials, have broad market development prospects. The 12th Five Year Plan of our country has put forward high demands for environmental protection, and filter materials will be widely used for water, gas, sound, and slag. The market prospects of the filter material industry are promising. Among them, in the treatment of smoke and dust, bag dust removal is increasingly widely used due to its ability to remove dust without causing secondary pollution and facilitate the recovery of dry materials, accounting for 80% of the dust removal equipment used. The steel industry is one of the main sources of air pollution. China's steel production has exceeded 300 million tons, and based on the application of bag dust removal in steel mills, 21 million square meters are needed. After calculation, 6 million square meters of filter material need to be replaced annually. 2、 Measures to deal with the humid environment of bag filters during use: The operating environment of bag filters is humid, as it can easily lead to equipment rusting and corrosion, affecting the normal operation of the equipment. So how can we solve the problem of humid operating environment for bag filters? Let's take a look below. 1. When the relative humidity of the air is high, the dusty air entering the dust removal system is prone to condensation. To prevent moisture from entering the bag filter and sticking to the filter material, a bypass pipeline should be installed. At this time, the bag filter can be avoided, allowing the dusty air to only pass through the dust collector and then be discharged into the atmosphere. 2. Smooth dust removal bags that are not easy to stick to lakes should be selected, such as smooth polyester filter materials, needle punched felt dust removal bags, etc. 3. A short cleaning cycle is beneficial for timely removal of lime dust on the surface of the bag, reducing the possibility of adhesion. Using a reverse air blower to clean the dust can remove the lime dust that has entered the filter material, and sufficient pressure is beneficial for cleaning the dust in the filter material. 4. High filtering wind speed will allow fine lime dust to enter the tortuous micropores and cause blockage. When the reverse blowing is ineffective in cleaning the dust, it will stay inside the bag for a long time and form a binder that blocks the filter holes. By adopting a low filtering wind speed, the above-mentioned problems can be avoided. 3、 The daily use of bag filters. In the daily operation of bag filters, changes in operating conditions or malfunctions can affect the normal operation and performance of the equipment. Regular inspections and appropriate adjustments are necessary to extend the life of filter bags, reduce power consumption, and recycle useful materials. Attention should be paid to the following issues: 1. Fluid resistance: The U-shaped differential pressure gauge can be used to determine the operating conditions: such as differential pressure, it means that the filter bag is clogged, there is water vapor condensation on the filter bag, the cleaning mechanism is malfunctioning, the ash hopper accumulates too much ash, causing blockage of the filter bag, and the gas flow rate increases. And a decrease in pressure difference means that the filter bag is damaged or loose, the inlet side pipeline is blocked, or the valve is closed. There are leakage phenomena or reduced fan speed between the box or compartments. 2. Operation record: Each ventilation and dust removal system should be equipped with and have test instruments installed. Regular measurements should be taken during daily operation, and accurate records should be kept. This allows for judgment based on the system's pressure difference, inlet and outlet gas temperature, main motor voltage, current, and other values and changes, and timely troubleshooting to ensure normal operation. The problems discovered through recording include: the working condition of the dust cleaning mechanism, the working conditions of the filter bag (such as damage, bag sticking, blockage, etc.), and changes in the system air volume. 3. Special attention should be paid to taking measures to prevent combustion, explosion, and fire accidents in bag filters. When dealing with combustion gases or high-temperature gases, unburned dust, sparks, and combustible and explosive gases often enter the system. Some dust has the property of spontaneous combustion or electrification. At the same time, most filter materials are easy to burn and generate static electricity through friction. Under such operating conditions, there is a risk of combustion and explosion accidents, and the consequences of such accidents are often serious. Good consideration should be given to taking measures, such as: (1) installing a combustion chamber or Mars trap in front of the dust collector to allow unburned dust to burn with gas or capture Mars. (2) Prevent the accumulation or buildup of dust to prevent spontaneous combustion and explosion of dust. (3) Before entering the bag room or pipeline for inspection or maintenance, it is necessary to ventilate and prevent CO poisoning. (4) Take measures to prevent static electricity accumulation, grounding each part with conductive materials, or adding conductive fibers during the manufacturing of filter materials. 4、 The reason for dust leakage in bag filters is that during normal operation, the sealing and wind speed selection of the equipment can cause dust leakage due to improper handling of the dust removal equipment, which in turn affects the normal operation of the bag filter and leads to emissions not meeting standards. Below, we will analyze the reasons for this. Mainly due to the following three reasons: 1. Selection of dust removal bags: As an important component of bag filters, dust removal bags play a role in the filtration process of bag filters. If the weight or density of the dust removal bag is insufficient, it will cause dust leakage from the bag filter, resulting in the dust removal equipment not meeting the standards. 2. Equipment sealing: The bag filter is assembled from the upper box and hopper of the clean air chamber. The inspection door and the connection between the upper box and the hopper are connected by screws. If a sealing strip is installed or the sealing strip does not meet the standard during the connection operation, it will cause dust leakage. 3. Filtering wind speed: The filter material of bag filter is generally divided into two types: normal temperature and high temperature. The normal temperature wind speed should be controlled within 1.0-2.0, and the high temperature wind speed should be controlled between 0.8-1. If the wind speed is too high, it will cause the dust to adhere too strongly to the surface of the filter bag. After pulse spraying, the dust will adhere to the surface of the bag, thereby increasing the resistance of the dust removal equipment and causing dust leakage.
