Electrostatic precipitator model

The heat exchanger models in Simprosys are based on Knudsen et al. (1997), Richard et al. (1997), Walas (1990), Kuppan (2000), Kakac and Liu (2002), McCabe et al. (2(XX)), and Minton and Morrison (2003). The cyclone models are based on Pell and Dunson (1997), Zenz (1999), and Reynolds et al. (2002). The electrostatic precipitator model is based on Pell and Dunson (1997) and Reynolds et al. (2002). The wet scrubber model is based on Pell and Dunson (1997) and Schifftner and Hesketh (1983). All the other unit operation models of Simprosys are based on Perry (1997). For more general information about Simprosys, please refer to Gong and Mujumdar (2008). For detailed information about the burner unit operation, please refer to Gong and Mujumdar (2014). 

FIG. 17-66 Electrostatic-precipitator-system model. (Nichols and Ogleshy, Electrostatic Precipitator Systems Analysis, AIChE annual meeting, 1970.)... 

For simplicity, the basic theoretical considerations of electrostatic precipitation are given in terms of cylindrical geometry, i.e., pipe-type electrostatic precipitation. This makes it possible to show most of the basic principles without numerical modeling. 

Particle trajectories can be calculated by utilizing the modern CFD (computational fluid dynamics) methods. In these calculations, the flow field is determined with numerical means, and particle motion is modeled by combining a deterministic component with a stochastic component caused by the air turbulence. This technique is probably an effective means for solving particle collection in complicated cleaning systems. Computers and computational techniques are being developed at a fast pace, and one can expect that practical computer programs for solving particle collection in electrostatic precipitators will become available in the future. 

A Del Electronics, Model ESP-100A, electrostatic precipitator was used for sample collection. Cigarette smoke particles were found to give approx the same particle distribution pattern on the collection filter paper as the gunshot residue, and since the smoke stains the paper, this provided a v rapid technique for optimizing operation conditions. With a flow rate of 15cfm and a corona current of 125 uA, the residue collects primarily on a narrow band across the sample paper. Samples were collected on Whatman No 1541 filter paper which lined the inside of the sample collection tube. The presence of this paper allowed air to flow only thru the center of the tube, so particle collection was made upon the filter paper exclusively. The filter paper samples were pelletized prior to neutron activation analysis... 

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. 

The electrostatic precipitator in Example 2.2 is typical of industrial processes the operation of most process equipment is so complicated that application of fundamental physical laws may not produce a suitable model. For example, thermodynamic or chemical kinetics data may be required in such a model but may not be available. On the other hand, although the development of black box models may require less effort and the resulting models may be simpler in form, empirical models are usually only relevant for restricted ranges of operation and scale-up. Thus, a model such as ESP model 1 might need to be completely reformulated for a different size range of particulate matter or for a different type of coal. You might have to use a series of black box models to achieve suitable accuracy for different operating conditions. 

Examine models 1 and 2 for the electrostatic precipitator. Is model 1 linear in A Model 2 The superposition test in each case is Does... 

Brown and Bern (26) cinalyzed the elemental composition of four card room dusts using X-ray fluorescence spectroscopy. Two of these were from filter cake material collected in two textile mills from which fine dusts (<20 ym) were separated by mechanical agitation (sonic sifting). The third sample was from filter cake material collected in a textile mill from which dust was removed by hexane washing followed by sonification of the bath, filtration and further sonification. The fourth sample came from dust collected on an electrostatic precipitator in a model card room. Results are shown in Table VI. 

Mittal, et al. reported the proximate chemical composition of a number of different samples collected in the model card room at North Carolina State University (31). Samples in this study included a coarse trash which was comprised of relatively large, mostly lint-free particulate matter that fell to the floor of the condenser filter chamber in a Pneumafil filter system (Model FCV8-3MTRK) (31). The second sample set was separated by the sonic sifting procedure from the condenser trash. Another set of samples was collected from an electrostatic precipitator located in the air conditioning return of the model card room. Results of ash analyses are shown in Table VII. 

TABLE VIII Minerals Identified in Electrostatic Precipitator Dusts Collected in a Model Card Room (16) ... 

Brown, Berni and Mitcham (17) report ash, aluminum, silicon and silica contents of four samples taken from an electrostatic precipitator in a model card room. The silica determinations were made using X-ray diffraction and IR spectroscopy. The results are shown in Table XIII. Based on these data, only a small fraction of the silicon can be attributed to silica. 

Helble, J.J. (2000) Model for the air emissions of trace metallic elements from coal combustors equipped with electrostatic precipitators. Fuel Processing Technology, 63(2), 125-47. 

Particulate emissions data for 21 studies of coal-fired power plants were compiled for use in receptor models. Enrichment factors were calculated (relative to Al) with respect to the earth s crust (EFcrust) and to the input coal (EFcoai). Enrichment factors for input coals relative to crustal material were also calculated. Enrichment factors for some elements that are most useful as tracers of coal emissions (e.g., As, Se) vary by more than ten-fold. The variability can be reduced by considering only the types of plants used in a given area, e.g., plants with electrostatic precipitators (ESPs) burning bituminous coal. For many elements (e.g., S, Se, As, V), EFcrust values are higher for plants with scrubbers than for plants with ESPs. For most lithophiles, EFcrust values are similar for the coarse (>2.5 ym) and fine (<2.5 ym) particle fractions. 

Fig. 2. Surface heterogeneity of a powder sample of sodium chloride computed from the adsorption of argon at 76.1 K using a two-dimensional gas model of adsorption, x, Sample prepared by electrostatic precipitation of a NaCl aerosol O, same sample but after annealing at 31(1 315°C in a dry nitrogen atmosphere at 600mmHg. (Reproduced from ref. 4 by courtesty of Academic Press, Inc.)...

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