Electrostatic precipitation applications

E. Bakke, On the Application of Wet Electrostatic Precipitators for Control of Emissions from Soderberg Aluminum Reduction Cells, A.I.M.E. Meeting, Dallas, Texas, February 1974. 

Precipitation Pamphlet, Western Precipitation Company C-103R-1, Los Angeles, Calif., 1952, p. 3, E. Bakke The Application of Wet Electrostatic Precipitators for Control of Fine Particulate Matter, Paper presented at Symposium on Control of Fine Particulate Emissions from Industrial Sources for the Joint U.S.-U.S.S.R. Working Group, Stationary Source Air Pollution Control Technology, San Francisco, Calif., January 15-18, 1974, pp. 6-7. 

Fabric filters can be more costly to operate and maintain than electrostatic precipitators, cyclones, and scrubbers however, fabric filters are more practicable for filtration of specific dusts. For example fabric systems are the typical control method for toxic dusts from insecticide manufacturing processes, salt fumes from heat treating, metallic fumes from metallurgical processes, and other applications. Any other control method may not be as efficient, nor economically feasible for such applications. 

Electrostatic precipitation is one of the fundamental means of separating solid or liquid particles from gas streams. This technique has been utilized in numerous applications, including industrial gas-cleaning systems, air cleaning in general ventilation systems, and household room air cleaners. 

Many of the typical features found in present-day electrostatic precipitators are based on work by W. A. Schmidt. One of his most important applications is the electrostatic precipitator that was installed at the Riverside Portland Cement Company in 1912. This plant handled a gas flow of 470 ni/s at the temperature of 400-500 °C. This was the first precipitator in which thin wire was used as discharge electrode. 

The development of electrostatic precipitators soon led to new applications, including the separation of metal oxide fumes. This was followed by various metal manufacturing processes such as the lead blast furnace, ore roaster, and reverberatory furnace. Electrostatic gas cleaning was soon applied also in cement kilns and in several exotic applications, such as recovering valuable metals from exhaust gases. 

In general, electrostatic precipitators have been shown to best suit those applications where high gas flows must be handled and relatively high efficiency is required. It must also be emphasized that the use of electrostatic precipitators is limited to those applications where the explosion risks are minimal. 

Most of the results presented in the previous chapters are based on idealized conditions. In practice, the performance of an electrostatic precipitator can be significantly influenced by the dust layers on discharge and collection electrodes i.e., dust layers may alter the electrical properties of the system. It is also possible that dust layers are not stable i.e., collected particles become loose, increasing the particle concentration in the outlet of the precipitator. These problems play a much smaller role if the surface collection electrode is continuously flushed with water. These wet elearostatic precipitators, however, cannot be used in all applications. 

Electrostatic precipitators have been used in various gas-cleaning applications almost for a century. During the past decades, a large number of modifi cations to electrostatic precipitators have been developed, the nn.ist common being duct and pipe types. The utilization of electrostatic precipitation extends from small household air cleaners up to huge industrial gas-cleaning systems. 

The two-stage electrostatic precipitators used in light-industry applications are compact devices which can be fitted into the ventilation system. These air cleaners are normally used to clean air from dusts, smokes, and fumes in industrial workplaces. The basic features of these devices are the separate sections for particle charging and collection. The charging section consists of thin metal wires installed between grounded metal plates. The distance... 

The most important application of electrostatic precipitation is, however, the solving of environmental pollution problems caused by many heavy-iiidus try processes. The dimensions, corona voltages, and currents of these gas-cleaning systems are much larger than for ventilation electrostatic precipitators. Typical applications of industrial electrostatic precipitators are... 

Pipe-type electrostatic precipitators are used to collect liquid aerosols (e.g., mists and fogs). They are also used in applications which require water flushing of collection electrodes. The diameter of precipitator pipes is typically in the range of 15 0 cm, and the length is in the range of 3-6 m. The number of pipes depends on the total gas flow. The gas-flow rates in pipe-type electro static precipitators is normally much lower than in duct-type precipitators. 

Table 4-15 illustrates some industrial application of electrostatic precipitators however, it is not intended to be all inclusive. 

Continuous-spray wet electrostatic precipitators have been applied on many applications, including ... 

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. 

Electrostatic fluidized-bed coating, 7 55-56 Electrostatic forces, 9 569, 570 11 800 and adsorbent selectivity, 1 584 in adsorption, 1 583 in solvent-solute interactions, 23 91-92 Electrostatic particle forces, in depth filtration theory, 11 339 Electrostatic precipitators (ESP), 11 714 13 180 23 552 26 699-706 advantages of, 26 700 applications of, 26 701-703, 705t design considerations related to,... 

The TSS has less potential for maximum emission control as the WGS and electrostatic precipitator (ESP). While all three technologies were designed to meet NSPS/ MACT, only the WGS and ESP can meet more stringent requirements. TSS performance can typically achieve d50 grade efficiency down to 2 microns. Most reported performance values result in emissions of 0.4-0.8 Ib/Mlb coke. Future PM2 5 regulations are a concern for TSS applications. By definition, TSS units cannot effectively remove small particles due to the cyclonic operation. 

A direct application to chemical process technology of the principle of electric wind is in electrostatic precipitators (Leonard et al.,1983) and electrocyclones for size separation of particles in powder technology (Nenu et al., 2009). Electrostatic precipitators applied to exhaust gas cleaning have recently been reviewed 0aworek et al., 2007). A particularly interesting development is that of a small electrocyclone with a diameter of 75 mm (Shrimpton and Crane, 2001). With this device it was shown that the separation quality of the smallest size particles with a diameter below 38 pm doubled upon application of the electric wind. Later experiments performed with submicron silica particles demonstrated that classification of such particles is possible by use of an electrical hydrocyclone (Nenu et al., 2009). 

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