1. The life of the filter
T = P/(N1*10-3*Qtη)
T---Use time of filter
P---Dust accumulation of filter
N1---Dust concentration of the air in front of the filter (mg/m3)
Q---Air volume of the filter (m3/h)
t---the running time of the filter in one day (h)
η---Filter efficiency
Compared with imported filter paper (LYDALL), the biggest drawback of domestic filter paper is depilation and high dust accumulation in the filter material background. This is related to the production environment and the lack of fine craftsmanship. In addition, high efficiency filter paper has high resistance at common filter speeds, but super high efficiency Filter paper has higher resistance and is more common.
Due to the high dust accumulation of domestic filter paper, the service life is not as long as that of imported filter paper.
N1 = M(1-S)(1-ηn)+Nrs(1-ηr)
M: atmospheric dust concentration
S: Circulating wind ratio
Nr: return air concentration
ηn: filter weight efficiency on the fresh air passage before the filter
ηr: filter weight efficiency on the return air passage before the filter
ηn = 1-(1- η1)(1- η2)(1- η3)
ηr = 1-(1- η2)(1- η2)(1- η3)
2. Filter speed and face wind speed
The ability to measure the air volume of the filter can be expressed in terms of surface speed or filtration speed:
Surface velocity (u): the velocity of the airflow passing through the filter section (m/s)
u = Q/(F*3600)
Filtration speed (v): the speed of air flow on the area of ??the filter material (cm/s)
v = 0.028*Q/f
Q---Air volume (m3/h)
F---The cross-sectional area of ??the filter is the windward area
f--Net area of ??filter material, that is, the area occupied by the removal of adhesion
The filtration rate reflects the passing capacity of the filter material, especially reflecting the filtration performance of the filter material. The lower the filtration rate used, the higher the efficiency will generally be obtained; the lower the filtration rate allowed by the primary air filter, the lower The filter material has a large resistance.
Under certain filter structure conditions, the unity reflecting surface speed and filtering speed is the rated air volume of the filter. Under the same cross-sectional area, the larger the rated air volume is expected to be allowed, the better, and the operation is lower than the rated air volume. The efficiency is improved and the resistance is reduced.
Three, the resistance of the filter
The fibers make the air flow around, creating little resistance. The sum of the resistance of countless fibers is the resistance of the paint factory filter.
The filter resistance increases with the increase of the air flow. By increasing the area of ??the filter material, the relative wind speed through the filter material can be reduced to reduce the filter resistance. Naming standard:
Filter type + frame material + filter material + category (number of bags) + external dimensions
For example:
TFK 1/2 F6-3 381/287*592*381
Expressed as bag filter, plastic frame, F6 green, 3 bags, size 287*592*381mm
Fourth, the principle of capturing dust
The particulate pollutants suspended in the air are composed of solid or liquid particles. Atmospheric dust can be divided into narrow atmospheric dust and general atmospheric dust: atmospheric dust in a narrow sense refers to solid particles in the atmosphere, that is, real dust; the modern concept of atmospheric dust includes both solid particles and polydisperse aerosols of liquid particles. It refers specifically to suspended particles in the atmosphere with a particle size of less than 10 μm, which is the broad sense of atmospheric dust. For particles larger than 10μm, because they are heavier, after a period of irregular Brownian motion, they will gradually sink to the ground under the action of gravity, which is the main target of ventilation and dust removal; 0.1---10μm in the atmosphere Dust particles also move irregularly in the air. Because of their light weight, they tend to float with the airflow and are difficult to settle on the ground.