Electrostatic precipitator discharge electrodes

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. 

A very important parr of the gas-deatimg process is the removal of the collected particles from the cleaning system. This should be as controlled as possible in order to avoid particle reenrrainmenr to the gas flow. This can be accomplished in the case of liquid particles such as acid fume or tar or oil smoke. olid particles are normally removed by periodic rapping of discharge and collection electrodes. Solid particles can also be removed with the aid of water, as is done in wet electrostatic precipitators. 

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. 

An alternative to the filter bag is an electrostatic precipitator. In these baghouses, an electric field at high potential is established between discharge and collecting electrodes. The discharge electrode has a small cross-sectional area (e.g., a wire or piece of flat stock), while the collection electrode is large in surface area (e.g., a plate). 

Fig. 6.16. Parallel-plate electrostatic precipitator. 1 — chamber, 2 — collector plate, 3 — discharge electrode, 4 — section switch box, 5 — dust collector...

The electrostatic precipitator being used for the experiments is subdivided into two separate chambers, each one with three electric sections in series. The discharge electrodes of the reference chamber are flat serrated strips, while those of the experimental chamber , are 5 mm diameter round wires. The gas passage width of the experimental chamber may be varied between 300 and 500 mm other design characteristics of the electrostatic precipitator are reported in Table I. 

Previous attempts have been made to develop reactions using electrical oxidation of gas pollutants. One of these was an electrochemical flow reactor (essentially an electrostatic precipitator with a catalyst) developed to oxidize a large volume of gas with hydrocarbon pollutants. However, the reactor apparently precipitated the hydrocarbons to the inner wall (outer electrode) of the reactor in the presence of corona discharge [22]. In the present study, no precipitates or dye deposits were observed in the reaction vessel after bleaching had taken place. 

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