Technical Measures for Application of Bag Dust Collector
1. Hygroscopic and deliquescent dust Hygroscopicity and deliquescent dust such as CaO, Na2CO3, NaHCO3, NaCI, etc. are easy to absorb moisture on the surface of the filter cloth, or become deliquescent after deliquescing, which may cause difficulty in dust removal, increase pressure loss, and even force filter bag dust Device stops. In this case, the general precautions for handling hygroscopic and deliquescent dust are listed below. ① Use a lint-free and lint-free filter cloth. Such as the use of felt filters. Surface treatment should be performed. The selection principles are: a. Chemical fiber is better than glass fiber, puffed glass fiber is better than general glass fiber; thin, short, and crimp fiber is better than thick, long, and smooth fiber; b, felt is better than fabric. Needle-punching is used to strengthen the entanglement between fibers. The satin fabric is superior in the fabric. The brushing on the surface of the fabric is also a measure to improve the wear resistance. C. Post-treatment such as surface coating and calendering can also improve the wear resistance. For glass fiber filter media, silicone oil, graphite, and Teflon resin treatment can change the wear resistance and folding resistance. ② The off-line cleaning operation system should be adopted. During the stop working time, the dust on the surface of the filter cloth is fully eliminated. ③ The bag filter should not be operated continuously regardless of the operation of the dust source facilities. The bag filter should be operated only when the dust source facilities are operated. When dust is accumulated on the filter cloth, moisture-containing air should not be allowed to pass through. The exhaust gases of many dryers and sintering furnaces are mostly high-temperature and high-humidity gases. When the bag filter is stopped, the temperature drops and the humidity rises, which makes it easy to absorb moisture. For this reason, a small hot air generator should be installed on the dust removal equipment. In this way, when the operation of the dust source device is stopped, hot air can be sent to keep the internal temperature of the bag filter
in its original state. The pre-coating method is adopted, that is, in the case of local dust collection with a low dust concentration, a layer of other powder can be pre-coated on the filter cloth, that is, the other powder is only supplied to the pipeline, and after a period of operation, A layer of this kind of dust is attached to the filter cloth, and then the wet dust to be collected is collected.
2. Dust-containing gas containing tar mist It is difficult to treat the gas containing only tar mist with a bag filter, but it can be filtered when the oil mist in the gas is not large and the dust content is quite large. For example, in the asphalt concrete plant, the flue gas of the stone dryer, plus the dust from the conveyor and other exhaust gases, all enter the bag filter, and in addition. At the mixer and unload the finished product. The tar mist produced by the heated asphalt concrete also entered the bag filter. In this case, the amount of dust accumulated on the filter cloth far exceeds the amount of oil mist, which can prevent the trouble of oil mist sticking and ensure the stable operation of the bag filter.
In the production of electrodes, molded carbon products, etc., tar mist is also generated in the process of mixing powder into the thermal adhesive. At this time, if the main purpose is to deal with the dust generated during crushing and transportation, only a part of the tar mist can be used. However, if there is more tar in the flue gas in the coke tank on the tail tar furnace, a suitable amount of coke powder should be added to the coke mist before the flue gas enters the dust collector to obtain satisfactory results.
If the gas contains only a small amount of oil mist, it can be treated separately. That is, by adding an appropriate amount of powder to the pipe as a filter aid, a bag filter can be used. After the added dust absorbs the tar mist, it should be returned to the manufacturing process and used as much as possible.
3. High-dust-concentration gas For the treatment of high-dust-concentration gas, a cyclone or gravity precipitator can be installed as pre-dust, but this will increase the resistance of the system and increase the power consumption. Therefore, when the classification of dust or finished materials is not required, most of them use bag dust collectors directly.
Not all bag filters can handle gases with high dust concentrations. Only bag filters with a wide separation between the filter bags and a continuous dust removal device in the form of a filter on the outside of the bag are suitable for processing gases with a high dust concentration.
When handling high dust content, the structure of the bag type dust collector should try to make the dust fall directly into the ash hopper or add some baffles to reduce the amount of dust attached to the filter bag; to prevent friction damage to the filter cloth, you should not The dust moving at high speed directly hits the filter cloth.
The shape and structure of the inlet and inlet baffle of the bag filter are shown in the figure. The latter uses the middle part of the box as a pre-dust collector, and also serves as a dynamic sedimentation chamber for dust and a branching chamber for inlet gas.
Although the bag type dust collector used for pneumatic conveying device to collect dust, although it has less air volume, high dust concentration, and the cabinet requires pressure resistance, it is more cylindrical. Qualified enterprises can replace bag-type dust collectors with plastic burner dust collectors.
The inlet of the cylindrical box is made in a tangential direction, so that it has a separation function. Many rotary reverse blow bag dust collectors are in this form. Sometimes the ash bucket is made in the form of a cyclone dust collector. The bag type dust collector of the pneumatic conveying system, because of the large amount of powder, the ash bucket volume and the diameter of the ash discharge port must be designed larger, and the capacity of the dust discharge device must be left to a sufficient extent to prevent the powder from being trapped in the ash bucket. material.