Bag filter is a high-efficiency dust removal device for removing dust pollutants in exhaust gas. The dust removal mechanism is mainly using the dust cake attached to the surface of the filter material to filter dust. The outstanding feature is high dust removal efficiency. After the dust-containing exhaust gas is filtered by a bag filter, its emission concentration can generally be stable below 50mg/m3, and even reach 5mg/m3. Today, the demand for environmental protection is getting higher and higher, bag filter has the advantage that other dust removal methods are incomparable.
The bag filter is generally composed of an auxiliary system such as a host, a filter element (dust removal bag), and back-flush control. The dust bag is the core component of the bag filter. Its material, sewing, use and maintenance are related to the efficient and stable operation of the entire system. The dust volume, dust concentration, load balance, flue gas temperature and humidity, and corrosiveness of the dust removal system Such factors may cause damage to the dust bag. Among various types of dust bag breakage, wear is a common type and is closely related to the design, manufacture, and application of the dust collector.
The category and causes of the loss of dust bag breakage
Common dust bag damage effects mainly wear, burn and corrosion.
Filter bag wear means that during the use of the dust bag, due to repeated filtration and blowback state switching, the bag bulges and shrinks, relative movement occurs between the bag and the dust removal frame or other components, and local abrasion is caused by the erosion of the high-speed dust-containing airflow.
Dust bag damage is due to the abnormal high temperature, or high temperature dust particles, the temperature is higher than the filter temperature, so that the high temperature parts of the filter caused damage to damage.
The filter bag corrosion is caused by the chemical reaction of the filter material caused by harmful components in the flue gas, resulting in a decrease in the mechanical properties of the filter material and breaking the loss effect. The corrosion of filter bags often occurs when the components of the smoke gas are out of specification, which can be divided into gas corrosion and liquid corrosion. In the presence of liquids, the hazardous gas components are more likely to cause damage to the filter bag.
Due to the presence of liquid components (such as condensation) in the flue gas, the paste forms a paste with the dust and clogs the gap in the filter bag, causing the paste bag to cause dust removal failure.
Prevention and treatment of dust bag wear
Dust bag wear is the main type of bag breakage effect. After other damage types cause damage to the small hole, the erosion of dust-containing air flow also generates further wear. Wear is closely related to the structure of the bag filter, airflow organization, and backflushing. The occurrence of dust filter bag wear is divided into the following five situations: filter bag mouth, filter bag body, filter bag, filter bag bottom and filter bag inside, different parts of the wear and the different factors, the solution Also different.
Filter bag body wear
The wear of the dust bag body, the vertical strip wear marks in the middle of the common filter bag, is divided into several situations:
If the damage marks from the inside to the outside, damaged in the bag cage vertical bar contact, indicating that the bag cage vertical reinforcement off or corrosion, the filter bag is broken or high pressure injection, blowing too frequently, so that the filter bag and the bag cage The breakage of the contact position caused breakage. This kind of wear problem can be solved by replacing the bag cage or adjusting the blowing device.
If the damage marks from the outside to the inside, the damage is at the vertical contact of the bag cage. It is often seen that the outside of the filter bag (adjacent filter bag or box member) has scratches with the filter bag. This kind of wear is the deformation of the bag cage or the filter bag installation is too small, the filter bag diameter is large or loose, causing contact between the filter bag and filter bag, filter bag and dust collector box body components, in the back blowing process due to the filter bag The swelling rubs against each other to cause it to wear. It is generally necessary to change the bag cage and guarantee the installation quality. During the design of the bag filter, the distance between the filter bag and the distance between the filter bag and the box structure should be avoided.
Dust bag under wear
The lower part of the filter bag is mechanically abraded: The outer wear of the lower part of the filter bag is mostly found in the bottom of the filter bag up to 300 mm. The wear is more on one side, the lower part is more serious, and the upward part is gradually reduced. The local sewing thread will be worn off, and the sewing thread will have good strength at the place where it is not worn. This kind of wear is caused by the deformation of the board, the hole spacing is too small, the bag cage is deformed, the filter bag is too long and other reasons. Individual filter bags and dust collectors were damaged by friction. Damages of this type should be strictly checked on the level of flower boards, and well-made bag cages should be used.
The annular wear of the lower part of the filter bag: An annular wear hole is formed from the outside to the inside of the filter bag. This kind of abrasion is caused by the partial flushing of the filter bag by the dust-laden flue gas, which indicates that the local air velocity of the filter bag is too large. It is mostly found in dust collectors with high wind speeds or dusts with strong grinding properties. When the filter bag is damaged on one side, the dust is washed and broken diagonally, and the damage is continuously enlarged over time. The serious breakage of the filter bag can lead to ring fracture of the filter bag. .
The inner wear of the lower part of the filter bag is more common in the contact position with the bag cage, and most of the difference between the bottom diameter of the bag cage and the bottom of the bag cage is too large, which causes the filter bag to change the amplitude when cleaning and filtering, and the bag cage is rubbed and damaged. Replace the high-quality bag cage can be solved.
The dust bag is the heart of the entire dust collector. The failure of the filter bag can make the entire equipment unable to operate normally. The wear of the filter bag is mainly related to the design and application of the dust collector, manufacturing, and installation quality. The wear process begins locally, but as soon as a small wear hole is formed, it will spread quickly, causing greater damage to the filter bag. Therefore, strengthening the inspection and inspection during operation and early detection of small wear are also important factors to avoid causing large-scale filter bag wear.