Efficiency of an Electrostatic Precipitator

Zhibin, Z. and Guoquan, Z. Investigations of the Collection Efficiency of an Electrostatic Precipitator with Turbulent Effects. Aerosol Science and Technology. 20 (1994) 2, pp. 169-176. 

Resistivity of dust The electrical resistivity of a dust, which is one of the factors that influences the practical efficiency of an electrostatic precipitator. 

Given the mass density function of particles, the overall collection efficiency of an electrostatic precipitator can be expressed as... 

The utility of the concept of aerosol particle electrical drift velocity can be shown by using it to estimate the theoretical efficiency of an electrostatic precipitator. For simplicity it is assumed that the collector is cylindrical, having a radius R (although this assumption does not affect the results), and that an aerosol is uniformly distributed across the entrance of the collector. In addition, turbulent flow in the collector is assumed such that the uncollected aerosol remains uniformly distributed at any distance from the entrance of the tube. If the electrical drift velocity is constant, the chance of a particle 4> being collected in a time At is... 

You have been requested to calculate the collection efficiency of an electrostatic precipitator containing three ducts with plates of a given size, assuming a uniform distribution of particles. Also determine the collection efficiency if one duct is fed 50% of the gas and the other passages 25% each. Operating and design data include ... 

Electrostatic precipitators are operated near the sparking limit i.e., corona voltage is continuously adjusted to maximize the collection efficiency. This is normally achieved at the sparking rate of 10-50 sparks per minute. Sparking occurs mostly in the front section(s) of an electrostatic precipitator. In the case of high-resistivity (>10 O cm) dust, special techniques must be... 

Fractional efficiency curves describing the performance of a specific model of an electrostatic precipitator have been compiled by a vendor. Although you do not possess these curves, you are told that the cut diameter (50% efficiency) for a precipitator with a 10-in. plate spacing is 0.9 pm. The vendor claims that this particular model will perform with an efficiency of 98% under your operating conditions. You are asked to verify this claim and to make certain that the effluent loading does not exceed 0.2 gr/ft. ... 

A coal combustion pilot plant is used to obtain efficiency data on the collection of particulate matter by an electrostatics precipitator (ESP). The ESP performance is varied by changing the surface area of the collecting plates. Figure E2.2 shows the data collected to estimate the coefficients in a model to represent efficiency 17 as a function of the specific collection area A, measured as plate area/volumetric flow rate. 

Wet Wall Electroinertial Precipitator. The wet wall electroinertial precipitator (WWEP) air cleaner was developed to meet the requirements of high operating efficiency, low maintenance, low operating cost, and simplicity of design. To achieve high efficiency with low pressure loss, an electrostatic precipitation was the best candidate method. A wet wall was desirable to flush the precipitate away and to minimize maintenance. Inertial effects were added to assist in moving material toward the wall and to improve the cleaning action of the water on the wall (20). 

In general, this increase in field strength does not offset the reduction in corona current. Hence the net effect of small particles in an electrostatic precipitator is a lowering of collection efficiency. 

An electrostatic precipitator is to be used to control emission of 0.5-p.m-diameter particles from a paper mill. An efficiency for the collector of 99.6 percent is desired. If the total design flow through the unit is to be 6500 ft3/min, how many square feet of collector surface are required Assume w = 7.5 cm/s. 

The reader is left the exercise of calculating the rate of ash discharged from the boiler in the flue gas. An electrostatic precipitator (ESP) or baghouse (fabric filter) is normally used to treat the flue gas to reduce the quantity of ash discharged to the atmosphere. Particulate and/or ash collection efficiencies rarely are below 99% by mass most operate in excess of 99.5% efficiency. 

Solution dH Several investigators (2, 12, 13) have indicated that the solution pH is an important determinant in the precipitation efficiency, and the optimum pH level will vary with both the protein (12) and the polyelectrolyte (5). However, the optimum pH for precipitation of protein by CMC did not change with the degree of substitution (DOS) of the CMC (12). This dependence is expected for the formation of an electrostatic complex. Changes in pH will affect the charge on the polyelectrolyte and the charge distribution on the protein. 

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