The role of Venturi in dust filter bag and filter bag cage

In the bag filter, in order to improve the filtration efficiency, it will be equipped with a venturi dust filte bag cage. After the venturi tube is installed at the mouth of the filter bag cage, not only can the filtration be promoted, but also the ultra-long filter bag has an excellent dust removal effect.

There are two functions of the venturi in the filter bag mouth: one is to guide the air flow from the blowing tube to the dust filter bag to prevent the air flow from deflection; the other is to promote the full mixing of the ejected air with the secondary air induced by it for energy communicate with. These two functions make many pulse dust collectors equipped with venturi, which is especially obvious when the nozzle mouth of the nozzle and the filter bag mouth are not in a straight line. However, the venturi has the following disadvantages:

    1. Increased equipment resistance. When dust-laden gas enters the dust removal filter bag and flows from bottom to top to the bag mouth, it first passes through the venturi. Generally, the diameter of the dust filter bag is not less than 120mm, and the diameter of the throat of the greenhouse pipe is 40-80mm. During the passage of the airflow, the faster the speed will increase the resistance.

2. It may weaken the cleaning effect. A good dust removal effect can only be achieved under the conditions of a large amount of dust removal air and a short period of time when it enters the filter bag. And it is required that the passage of the dust removal air mass is dredged with low resistance. The existence of the venturi tube narrows the airflow channel, forming a bottleneck, prolonging the time when the cleaning air volume enters the dust bag, making the air mass become slender, and then weakening the impact on the wall of the filter bag, and the pressure inside the bag is waveform The peak value of the pressure is reduced, so that the original pressure waveform becomes a "flat" waveform, and the reverse acceleration is reduced.

 3. The filter area is reduced. The filter bag within the length of the venturi tube cannot be effectively cleaned. The surface area of the filter bag in this part is very thick, so it cannot filter. The temperature drop during this period of processing high-temperature flue gas can also easily cause condensation and blockage of the filter bag.