Composite dust collector

Composite dust collectorBased on the principle of electric charge, the Energy&Environmental Research Center (EERC) in North Dakota, USA, is researching embedded electric bag composite dust removal technology. They found through countless experiments that the shorter the path and time for charged dust to accumulate on the surface of the bag, the greater the permeability of the accumulated powder layer, and the higher the filtration wind speed at the same resistance.

Main features of composite dust collector

l Long term efficient and stable dust removal performance
Not affected by changes in coal type, smoke composition, and specific resistance, it can stably meet the requirement of ≤ 30mg/Nm for a long time³Emission requirements. Actual measurement of each engineering project: emission values are between 4-27mg/Nm³Range;
Charging effect improves the ability of filter bags to capture PM10 level fine particles.
l Low running resistance
The dust concentration in the bag area is low, and the structure formed by the accumulation of charged dust on the bag surface is "fluffy" with high breathability;
Engineering application comparison: Electric bag dust removal reduces resistance by 300Pa to 800Pa compared to bag dust removal.
l energy saving
Under the same emission conditions, electric bags save energy compared to other dust collectors.
l Extend the service life of filter bags
The dust removal mechanism improves the working conditions of the filter bag and extends its lifespan;
Strictly control the quality of bag packaging, ensuring quality control in terms of material, structure, and processing;
Engineering examples have confirmed that the electric bag dust removal system for coal-fired boilers has been in operation for 4.5 years, and multiple units have been in operation for over 3 years, with zero damage to the filter bags.
l Low operating costs
The number of bags equipped with electric bags has decreased by 20% compared to bag filters, and the service life of filter bags has been extended by more than 20%. After being put into operation, the cost of bag replacement has decreased by about 35% or more compared to the same period last year;
The electricity consumption of electric bags has decreased by 50% compared to the same period last year for electrostatic precipitators, which is equivalent to a 20% decrease in operating costs due to filter bag replacement factors.

Process flow:
In the FE type electric bag composite dust collector, the flue gas enters the front stage electric dust removal zone from the inlet horn. The smoke and dust are charged by the electric field corona current, and most of them are collected by the electric field. A small amount of charged but not captured dust slowly enters the rear stage bag dust removal zone with the flue gas, and is filtered by the filter bag to achieve the purpose of flue gas purification.

In the dust removal mechanism, the electrostatic precipitator zone plays two important roles in the principle of electric bag composite technology:

l Dust removal function
According to the multidimensional odd formula, electrostatic precipitator * electric field has the highest dust removal efficiency, with an efficiency of over 80%. When a large amount of smoke and dust are collected by the electric field, the smoke enters the bag filter area with a dust concentration of only 20% or less and a small particle size. The dust removal effect improves the working conditions of the filter bag, thereby reducing the resistance of the filter bag, extending the cleaning cycle, and prolonging the service life of the filter bag. In practical engineering applications, the start stop of the electric field significantly affects the variation of operating resistance. Figure 2 shows the data obtained from the test of Beijing Jingneng Thermal Power Unit # 1.

l Charging effect
Theory and practice have shown that the accumulation structure of charged dust plays a subtle role when it reaches the surface of the filter bag. The electric field produces a large number of negative ions and a small number of positive ions simultaneously during ionization. Negative ion charged dust causes mutual repulsion, and the dust accumulates on the surface of the filter bag in a regular and orderly manner with a "fluffy" structure; Additionally, a portion of positively charged dust particles attract and coalesce with negatively charged dust particles, resulting in an increase in particle size. Dust, under the action of two polar charges, improves the permeability of the powder layer, enhances the cleaning efficiency, improves the capture efficiency of fine particles (less than PM10), and prevents the fine powder layer from blocking the filter holes, making the filter bag highly efficient and low resistance. Figures 3 and 4 show the accumulation of charged dust on the surface of the filter bag, with and without charge, captured through experiments. Figure 5 shows the outlet emissions during the start stop electric field test of Beijing Jingneng Thermal Power Plant # 1 furnace electric bag dust removal operation, indicating that the charging effect increases the filter bag's ability to capture fine particles when the electric field is turned on.