Causes of paste bags(3)

Structural paste bag

We classify all paste bags that are caused by improper design and structure of the dust collector and structural parts into structural paste bags.

Filter material structure and treatment

Some filter materials have loose needle-density fibers, and the filter surface fibers are loose. Even if the surface is singulated, fine dust can easily enter the filter material and reside therein. The dust accumulates to a certain extent inside, and the influence of water vapor in the flue gas gradually forms a blockage from the inside out.

In addition, some filter media have no or no singeing or calendering treatment, and the fiber ends retain the fiber ends, which actually provides “condensation nodules” for condensation, so that condensation begins first from the fiber ends. Dust will also form dust clusters at this position first. As the dust clusters become larger and larger, they will bridge each other, and a large area of paste bags will gradually form. In waste incineration power plants that use pure PTFE filter media, if there is no other treatment on the surface, stubborn dust crusts at the end of the fiber can often be found.

In addition, for working conditions with high humidity or risk of acid condensation, the filter material is not treated hydrophobically, and paste bags are more common.

Filter bag fit

We know that pulse cleaning is actually the impact of the pulsed airflow and the secondary airflow on the filter bag, so that the filter bag deforms from the top to the bottom in the latitudinal direction, the inertia of the deformation and the collision of the filter bag with the cage bone on the surface dust layer. Causes an “avalanche effect” that removes surface dust. The cleaning effect depends largely on the magnitude of the deformation inertia and the strength of the collision between the filter bag and the filter cage . In practical applications, due to the small size of the filter bag latitude or the degree of heat shrinkage of the filter material in use, the filter bag “bundled” cannot be separated on the filter cage after a period of use. At this time, the shape of the filter bag caused by pulse cleaning is small, the collision intensity between the filter bag and the filter cage is limited, and the surface dust cannot be effectively removed. Dust accumulation on the surface of the filter bag and long-term accumulation may cause a paste bag.

Pressure distribution in the blow pipe

At present, a large number of dust collectors are sprayed and cleaned. Each line consists of a blowpipe that is responsible for the cleaning of more than a dozen bags of the line. A small number of small injection holes or blowing pipes of the same size are uniformly distributed on the blowing pipe, and one small blowing hole or the blowing pipe corresponds to one bag. Theoretically speaking, when the compressed air advances in the blowing pipe, the gas dynamic pressure is gradually converted into static pressure, and such conversion directly causes the amount of compressed air obtained in each filter bag of the row to be different. The cleaning effect is different. The risk of poor paste cleaning is relatively high. At the scene, we also selected several filter bags of the same row in the same state to compare the air permeability. The difference between the highest and the lowest is relatively large. Indirectly explain the objective existence of this situation.

Insufficient injection pressure

Generally, the cleaning pressure at the site can be adjusted. If the cleaning pressure is not too good, the cleaning effect is not good, and dust accumulates on the surface of the filter bag. In the long run, the risk of the paste bag is relatively high. If this happens, there are two possibilities: one is the system design limitation, that is, the maximum pressure that the system can provide is too small; the other is that the blowing interval is too short, and the system pressure has not recovered after the first injection. At the required pressure, a second pulse is started.

Operation error

① Pre-spraying as required, so that the oil mist in the ignition directly invades the filter material, causing the paste bag.

② When the switch is turned on (especially before a long shutdown), the machine is not turned on and off in the correct way.

③When the boiler has an accident such as a pipe burst during operation, the filter bag is not properly handled and remedied.

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