Working principle and installation precautions of industrial dust collector vacuum hood
There are two ways of airflow movement at the suction hood mouth of the dust collector:
One is the inhalation flow of the air flow at the suction port; the other is the blowing flow of the air flow at the blowing port. The former is widely used. The air flow at the suction port can be considered as an air flow way of the surrounding air flowing to the middle.
When the suction port of the dust collector inhales, a negative pressure is formed near the suction port, and the surrounding air flows to the suction port from all directions, forming a suction airflow or confluence. When the area of the suction port is small, it can be regarded as a “point sink” of the airflow. The airflow forms a radial line centered on the suction port and a constant velocity sphere centered on the suction port.
It can be seen from the above formula that the flow velocity at a point outside the point sink is inversely proportional to the square of the distance from the point to the suction port. Therefore, when designing the gas collecting hood, the distance from the hood mouth to the pollution source should be minimized to improve the capture efficiency.
If a baffle is added around the suction port, the suction range is reduced by half, and its constant velocity area is reduced to a hemisphere, then the suction volume of the suction port will cause the same suction at the same distance. When the air velocity is high, the suction volume without baffles at the suction port is twice as large as that with baffles. Therefore, when designing the external air collecting hood, the suction range should be minimized to reduce the working principle of the air collecting hood and enhance the control effect.
Notes when installing the suction hood:
(1) The place where the suction hood is installed should try to maintain the negative pressure in the suction hood Balanced to avoid dust-laden airflow escaping from the hood or sucking powder out. For example, when the unloading chute and the belt conveyor are inclined to deliver materials, the suction hood should be arranged in front of the chute; when the unloading chute and the belt conveyor are vertically delivered, the suction hood should be located in front of and behind the chute.
(2) Generally, when handling or conveying hot materials, a suction hood should be set at the top of the closed device; or a suction hood should be set at the upper and lower positions of the feeding point or the receiving point.
(3) The suction hood of the dust collector should not be close to the holes in the open sky (such as operation holes, observation holes, discharge ports, etc.), so as not to inhale the air outside the hood and increase the workload of the dust collector. For example, a dust curtain (can be made of rubber belt, canvas belt, etc.) must be set before the suction hood of the material receiving point of the tape machine.
(4) The principle is that the position of the suction hood does not affect the operation and maintenance. A section of the pipeline connected to the cover should preferably be set vertically to avoid blockage of the pipeline caused by the entering material.
