Dust Suppression in Coal Transmission System

The dust of the coal transmission system of thermal power plants has the characteristics of extensiveness, diversity, and difficulty in treatment, which makes it difficult to control, but the dust sources can be mainly summarized into the following aspects:

1. Dust generated by coal points: such as screw unloader, bucket wheel stacker reclaimer, impeller coal feeder, blanking port of each transfer station and tail receiving groove of tape conveyor, etc., due to the height difference of blanking, the positive pressure induced wind generated by the material flow will bring fine material particles into the air to form diffuse dust.
2. Dust generated by open-pit coal storage yard: due to the high cost and small reserves of closed coal storage yard, open coal storage yard is adopted in our plant, especially in spring and autumn, the moisture content in coal storage is low, and the natural wind is large, and the natural wind will involve the coal storage into the air and produce quite serious dust.
3. Dust generated by the return belt of the belt conveyor: due to the existence of ovality such as the increased surface roller and the reversing roller of the belt conveyor and the sticky coal on the drum, the return belt of the tape machine is fiercely fanned during operation, resulting in fine material particles adhering to the return belt entering the air and generating dust.

Due to the leakage of the material in the transportation on the ground and the dust in the air settles on the ground, under the action of natural wind or wind generated by running machinery, it enters the air again and produces secondary pollution of dust.

For the dust generated above, the first thing is to prevent dust, followed by eliminating coal dust, and again strengthening management. The following mainly describes the dust suppression method.

The main way of dust suppression is mainly spray dust suppression, and spray dust suppression is one of the simplest ways to reduce dust. The reason why coal dust is caused by the low surface moisture of coal, if the surface moisture of coal reaches a certain level, then there is very little dust generated during stacking and transportation. Spray dust suppression is to spray water into the coal to increase the surface humidity. However, if the humidity is too large, it will affect the efficiency of the subsequent process and affect the economic benefits of the plant.

Therefore, the control of the amount of water spray for water spray dust suppression has become a key part. In the design process of spray dust suppression, the following problems need to be paid attention to:
First, the height of the nozzle from the belt should be moderate, so that the spray range of water is within the coal material, and it cannot be sprayed on the belt, which will make the belt slip and affect the operation; the second is the water source selection problem of spray dust removal, because the nozzle water spray hole is relatively small, if the water quality is not good, it is easy to block the nozzle, so that the spray dust suppression is in a paralyzed state; The third is the control problem of the spray dust suppression system, the spray device should start working best when the coal belt runs to produce dust, if you work in advance, the sprayed water exists on the belt, a part of the coal dust will stick to the belt, if lagging, it will cause dust to fly.
Therefore, it is recommended to adopt the method of manual opening and closing of the water spray device on the spot and the automatic opening and closing of the falling coal, that is, the water spray device is started when there is coal on the belt, and it is automatically closed when there is no coal.