The filter bag must be combined with the corresponding accessories in order to maintain the shape suitable for filtering and cleaning in the filtering and cleaning process, and to achieve the purpose of filtering or peeling the dust particles, so that the dust collector maintains the normal operation state. The combination of filter bags and accessories is called filtration unit.
There are two types of fittings used for the inner and outer filter units.
(1) Accessories sewn together with the filter bag. Such accessories need to be sewn to the filter bag during the process of sewing the filter bag. Such as the outer filter bag bag elastic ring, the inner filter bag anti-snapping ring and so on.
(2) Accessories for supporting or hanging filter bags. This type of fitting is not sewn together with the filter bag and must be installed together when the filter bag is mounted on the filter. Such as the frame of the outer filter bag, the hanging device of the inner filter bag.
A. Accessories for the outer filter unit
(1) Accessories that are sewn together with the filter bag – bag mouth elastic ring.
The bag mouth of the outer filter bag is fixed on the perforated plate and must be reliably sealed. Since the gas entering the perforated plate has been purified, any leaks at the perforated plate mounting filter bag will cause the dust-laden gas stream to enter the clean gas chamber, and the dust removal efficiency of the dust remover will be greatly reduced. The key to the sealing of the filter bag and the porous plate is two points. First, the processing of each hole in the perforated plate must meet the requirements. All holes must have the same size. The accuracy must be controlled within the range of minus 0 plus 0.3 mm. Second, the material of the bag mouth elastic ring must be a good elastic stainless steel or spring steel, according to the different mouth diameter of the bag using a thickness of 0.3 to 0.5 mm strip. After the elastic ring is made, it should also be affixed with a fillet suitable for the thickness of the perforated plate. The material of the fillet is the same type of filter material used in the filter bag, and generally the same type of filter material is used as scrap. When sewing the outer filter bag, the elastic ring should be sewn to the top of the filter bag.
The size of the elastic loop filter bag mouth in the inspection slot cannot be measured by the gage. The hole plate (hole size of the aperture plate is the aperture of the multi-hole plate) should be used for inspection.
(2) Supporting filter bag accessories – filter bag frame
The filter bag frame is used to support the filter bag in a state of being strained during the filtering and cleaning process, and maintains the shape favorable for filtering and cleaning. From this point of view, the frame is the “rib” of the filter bag. It should be light and easy to install and maintain. In particular, it should be smooth and straight without burrs, so that the filter bag will not be damaged.
The shape of the frame of the filter bag is consistent with the type of filter bag. The round filter bag is equipped with a round frame, the flat bag with a flat frame, and the envelope-shaped bag with an envelope-shaped frame.
Filter bag and frame and fit: Synthetic fiber filter bag and frame should be loosely fitted, filter bag diameter and length are greater than the frame diameter and length, the distance between the frame vertical bars should be less than or equal to 40 mm, glass fiber filter bag and The frame should be a tight fit. The diameter and length of the filter bag is equal to the diameter and length of the frame, and the distance between the vertical bars of the frame should be less than or equal to 20 mm.
The vertical bars of the frame should use φ3 to φ3.5 carbon steel depending on the length of the frame. Appearance should be made of corresponding anti-corrosion treatment, if necessary, should be made of stainless steel.
In addition to the frame, accessories for the outer filter unit include filter bag holders and venturis. In China, there are a lot of precipitator host processing porous board is the use of gas cutting this relatively backward process. Especially in the early small pulse bag filter, the porous plate was mostly gas-cut. The size is not accurate and rough. In retrofitting these dust collectors, an aluminum die-cast filter bag holder is often used. Each hole in the perforated plate can be fitted with a filter bag using a flexible ring pocket. Easy to install and repair. It also facilitates a reliable seal between the filter bag and the perforated plate.
The venturi is fixed on the frame short tube. The purpose is to increase the amount of air flow 5 to 7 times when blowing. However, according to recent data, the amount of vent gas installed in the Venturi tube is less than that of the Venturi tube. Of course, the advantage of the venturi tube is that it can concentrate the naturally diffusing gas flow, so that the ash pressure can be transmitted to the bottom of the filter bag. However, the use of a venturi increases the resistance of the duster.
B. Accessories for the inner filter unit
(1) Accessories that are sewn together with the filter bag – tamper-proof ring, bag mouth ring.
The dust removal of the inner filter bag is under the action of vibrating or reverse blowing airflow. The filter bag is forcibly deflated or bulged to remove dust. In order to make the filter bag deformation or collapse when the center of the filter bag can make the dust settle the channel. The anti-snaking rings must be sewn on the filter bag at regular intervals. The tamper-proof ring should be made of 3`5 mm carbon steel or stainless steel wire according to the diameter of the filter bag. The welding of the tamper-proof ring should be reliable, and it should not be detached and smooth without glitches. Carbon steel materials should be preserved.
The inner diameter of the tamper-proof ring should be equal to the outer diameter of the filter bag. When sewing, the same kind of filter material should be wrapped. Ordinarily scrap is also used. Two sutures are sewn on each side of the tamper-proof ring. The long arm double needle sewing machine is generally used for sewing. And there are strict requirements for the suture used.
The inner filter type filter bag is generally made of a stainless steel strip and a bag ring. In this way, when the bag cap is installed, the clips are not needed, and the installation is more convenient.
(2) Accessories for Hanging Filter Bags
When the inner filter type filter unit is installed, the lower end of the filter bag is put on the lower bag holder, and the dust-containing airflow enters the filter bag through the lower bag holder. The upper end of the filter bag is fitted with a bag cap made of carbon steel or stainless steel. Used for the sealing and hanging of the inner filter bag. And it is fixed on the beam of the dust collector by the hanging device.
The inner filter bag needs to maintain the set tension of the filter bag during filtration and cleaning. A 100 mm diameter filter bag requires 10 kg of tension. The 300 mm diameter filter bag requires 30 kg of tension. Insufficient tension will affect the filtration and cleaning of filter bags. Too much tension will cause premature failure of the filter bag when the tensile strength of the ultrafiltration bag is too high. The tension of the filter bag is set by the suspender adjusting hole or chain of the suspending device during installation, and the tension is maintained by a spring or a tension spring. Many inspections and adjustments will be required later.