Vertical airflow pulse bag filter

1、 Background technology

At present, the country attaches great importance to the environmental protection industry, especially energy conservation and emission reduction projects, in which dust suppression and treatment have a significant effect on controlling the haze generated in the air. Bag filter has the highest market share among dust removal equipment, and its extremely high cost-effectiveness has enabled it to achieve a market share of90%above. The bag filter has extremely high dust removal efficiency (can reach)99.9%）Compared to mechanical dust collectors (with a dust removal efficiency of60—70%）Has higher dust removal efficiency; Compared to electrostatic precipitators, it has a lower price and is more easily accepted by polluting enterprises (with the same processing air volume, the cost is one-third of that of electrostatic precipitators); Compared to wet dust collectors, wet dust collectors are more unaffected by seasons (winter antifreeze has always been a difficult problem to solve), and there is no secondary discharge phenomenon (wet dust collectors require secondary discharge and require sedimentation tanks, especially in northern winter when sedimentation tanks freeze, which has always been a problem for wet dust collectors).

Due to the above characteristics, the market share of bag filters has been increasing year by year, but bag filters also have technical shortcomings. The core technologies of bag filter include flow rate design, pipeline air velocity design, filtration air velocity design, filtration area design, dust cleaning method design, equipment pressure design, air leakage rate control, and filter material selection. Bag dust collectorThe "heart" is the filtering material (i.e. bag), and the "lifespan" and filtering effect of the bag directly affect the lifespan and dust treatment efficiency of the bag filter. At present, the filtering materials on the market are mostly polyester needle punched felt, which are synthetic fiber products. Its strength has never been able to meet the long-term operation requirements of dust removal equipment. In practical cases, it is often the case that the dust removal equipment has a very good effect in the first few months of installation, but after a long time, the bag will be damaged, reducing the dust removal effect. The main reason for bag damage is due to the design of the filtering wind speed being too fast (theoretically, the required design wind speed is)0.95~2.0m/min）The faster the filtering wind speed, the smaller the filtering space, and the lower the equipment cost, but it also reduces the service life of the bag; The dust particle size is too large (the dust particle size that can cause damage to the bag is generally larger than75µ m).

Our company has developed a pulse bag filter that can control the flow rate of dusty gas to address the above issues.

2、 Invention content

To control the flow rate of dusty gas entering the dust removal equipment, an airflow control room is installed on one side of the inlet hole (by3~4The dusty gas (composed of vertical baffles or herringbone baffles) first flows through the airflow control chamber and then enters the filter bag chamber. The advantage of this invention is that compared to traditional bag filters, the dust containing gas flows through the airflow control room first. The airflow control room mainly has two functions:1The dust collector has truly achieved the goal of reducing the filtering wind speed in actual operation0.95~2.0m/min；2Make the particle size larger than40µ m dust particles fall into the ash hopper by gravity and have a primary dust removal effect. This invention greatly improves the service life of the cloth bag and enhances the dust removal effect.

threeWorking principle of vertical airflow pulse bag filter

The operation of a vertical airflow bag filter mainly consists of two steps:

1When the dusty airflow enters the dust collector airflow control room from the pipeline, the airflow velocity is reduced due to the expansion of the cross-section. Dust particles with a settling velocity greater than the airflow velocity settle down. The vertical airflow bag filter is divided into upward airflow type and downward airflow type according to the intake position. In order to control the filtering wind speed and remove large particle size dust, vertical or herringbone baffles are installed in the dust collector. On the one hand, its purpose is to change the direction of airflow movement. This is because dust particles have a large inertia and cannot change direction together with the gas. When they collide with the baffle, they lose the kinetic energy to continue flying and settle into the ash hopper below; On the other hand, it is to extend the travel distance of dust and gradually settle it under the action of gravity, while reducing the filtering wind speed. The vertical baffle can also be changed to a herringbone baffle, which aims to generate small vortices in the gas. Dust particles are separated from the gas by centrifugal force and collide with the chamber wall and baffle, causing them to settle down and enter the ash hopper.

2The remaining airflow enters under the pressure of the fanThe filter bag chamber of the dust collector. The filtering mechanism is the result of a comprehensive effect. Dust is generally distributed according to a certain dispersion curve, ranging from ultrafine particles to coarse particles. Its filtering effects include gravity, sieving, inertial collision, hook effect, diffusion, and electrostatic attraction.

When the dusty airflow passes through the filter bag, dust particles larger than the gap of the filter bag settle due to gravity or are blocked by fibers due to inertia. Dust particles smaller than the gap of the filter bag collide with the fibers of the filter bag or are hooked onto the fiber surface by the fibers when passing through the filter bag (i.e. hook effect). Smaller dust particles remain on the surface and in the gaps of the filter bag due to Brownian motion between molecules.

The pulse valve works within the set parameters, using compressed air as the cleaning power. The pulse blowing mechanism instantly releases compressed air, inducing several times the secondary air to enter the filter bag at high speed, causing the filter bag to shake. The dust attached to the filter bag is removed by the impact vibration and reverse airflow, and falls into the ash hopper after shaking.

5、 Specific implementation method

On one side of the dust removal equipment boxInstall three baffles with serial number 17 on one side of the bag. Make this part, numbered 16, form an airflow control room. The thickness of the baffle shall not be less than 5mm, and full welding shall be used at the connection with the box to ensure the strength and wind resistance of the baffle. The upper and lower baffles should form a "wolf tooth staggered" pattern, with a staggered size of no less than 100mm. The distance between the baffles should be greater than or equal to the diameter of the air inlet.