Overall collection efficiency

Cyclone Efficiency. Most cyclone manufacturers provide grade-efficiency curves to predict overall collection efficiency of a dust stream in a particular cyclone. Many investigators have attempted to develop a generalized grade-efficiency curve for cyclones, eg, see (159). One problem is that a cyclone s efficiency is affected by its geometric design. Equation 15 was proposed to calculate the smallest particle size collectable in a cyclone with 100% efficiency (157). 

It is important to note tlmt tlic deposition rate is a strong function of particle dimneter tluough the term v, wliich appears twice in tlic deposition flux equation. Equation (9.7.10) must be modified to treat process gas streams discliarging particles of a given size distribution. The suggested procedure is somewhat simihu to tlial for calculating overall collection efficiencies for particulate control equipment (12). For this condition, the overall rale is given by... 

The collection efficiencies shown in column 4 of the table were read from Figure 10.45a at the scaled particle size, column 3. The overall collection efficiency satisfies the specified solids recovery. The proposed design with dimension in the proportions given in Figure 10.44a is shown in Figure 10.48. 

The flowrate of the gas is 10 m3-s 1 and the concentration solids is 12 g-m-3. The particles are to be separated in a scrubber with a collection efficiency curve shown in Figure 8.14. Estimate the overall collection efficiency and the concentration of solids in the exit gas. 

In a single stage installation, overall collection efficiency is not influenced by the external terminus of the gas discharge tube, whether a round elbow, Fig. 12(a), a mitered elbow, Fig. 12(b), or a volute housing,... 

The overall collection efficiency shown in Table 1 is determined from Fig. 2 of the text for the feed distribution given in Fig. 18. From Fig. 4 of the text at 80 grains/cu.ft, EL = 98.7%, therefore ... 

Example 7.1 In a test of the performance of a cyclone, a dust-laden gas with the particle mass flow rate of 600 kg/h is used. Given that the dust escape rate is 30 kg/h, what is the overall collection efficiency Plot the fractional efficiency curve to identify the cut-off size of this cyclone. The results of particle size analysis (by weight percentage [wt%]) at the inlet and outlet of the cyclone are given in Table E7.1. 

Example 7.2 Consider a dust-laden gas passing through an electrostatic precipitator. Assume that all particles have the same charge-to-mass ratio, q/m, and the electric field is uniform. Use the Deutsch equation to estimate the overall collection efficiency if the particle size distribution based on weight percentage (wt%) can be expressed by the mass density function, /M, as... 

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

The overall collection efficiency of this electrostatic precipitator is... 

A cyclone has an overall collection efficiency of 90 percent for dust-laden air at 1 atm and 25°C. The mass loading of dust to air is 5. The results of the particle size analysis are given in Table P7.1. 

A particulate-settling chamber is installed in a small heating plant that uses a traveling grate stoker. Determine the overall collection efficiency of the chamber, given the following operating conditions, chamber dimensions, and particle-size distribution ... 

Calculate the overall collection efficiency. This is the sum of each of the efficiencies from the previous step multiplied by the weight fraction of the corresponding particle size in the mixture in... 

Calculate the overall collection efficiency. This is done by (a) determining the midpoint size of each of the particle-size ranges in the statement of the problem, (b) using the expression from step 3 to calculate the collection efficiency corresponding to that midpoint size, (c) multiplying each collection... 

Thus an M X N electrostatic precipitator consists of M cliambers and N fields. A precipitator is "out of compliance" when its overall collection efficiency falls below a designated minimum because of bus section failures. Wlien several bus sections fail, tlie effect of the failures depends on where tliey are located. To detemiine directly whetlier a precipitator is out of compliance after a given nmnber of bus sections liave failed, it would be nec ssaiy to test all possible arrangements of tlie failure locations. The out of compliance probability is given by tlie percent of arrangements tliat result in overall collection efficiencies less tlian tlie prescribed minimmn standard. The nmnber of arrangements to be tested often makes tlie direct approach impractical. For example, Theodore et... 

Volumetric average particulate concentration at the exit of the bed, overall collection efficiency, X. 

Calculations of the overall collection efficiency for the fluidized bed filter begin with specification of the values of the superficial gas velocity, Uq, minimum fluidization velocity, bed height at minimum fluidization, void fraction at minimum... 

Figure 3 shows a comparison of the model prediction of the overall collection efficiency as a function of superficial gas velocity versus the experimental data of Tardos et al (12). Since the charge acquired on the collectors was not reported, assumed values shown in Figure 3 were employed. It should be noted that this assumed functional dependency between and was not entirely arbitrary, but qualitatively suggested by experimental measurements of the electric potential in the fluidized bed (12). An important aspect of Figure 3 is both the model prediction and experimental... 

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