A commonly accepted practice of removing solid particles from a flue gas includes the utilization of an electrostatic precipitator to hold the solid particles without inhibiting the flow of the flue gas. Typically, an electrostatic precipitator is positioned in the flue between the outlet of a boiler and a smokestack.
The ordinary construction of an electrostatic precipitator includes a plurality of large, flat, metal plates which are spaced from each other. The metal plates may have a height of up to 30 feet or more, and a width of up to 10 feet or more. It is to be appreciated that the specific size of the plates in a given precipitator is dependent upon the particular precipitator construction for a given application. Ideally, the flat plates are equidistantly spaced from each other. A second plurality of elongated electrodes is positioned among the plates. The electrodes are positioned between each pair of adjacent plates. Ideally, the elongated electrodes are equidistantly spaced from the adjacent plates.
The uniform spacing of the elongated electrodes from the plates is necessary to have a uniform electrostatic charge between the elongated electrodes and the plates. A uniform electrostatic charge generates uniform collection of solid particles on the plates. Typically, the solid particles are removed from the plates by rapping the plates to vibrate the plates and, thereby, cause the collected solid particles to drop off the plates in clusters into collectors under the plates.
The flue gas which enters the electrostatic precipitator is hot. Commonly, additional heat enters the precipitator in the form of fires caused by problems in the operation of the boiler. Exposure of the plates to excessive heat as well as other factors can cause the plates to warp or buckle. The warping or buckling of the plates destroys the uniform spacing between adjacent surfaces of adjacent plates and uniform spacing between each of the elongated electrodes and the respective adjacent plates. Thereby, the effectiveness of the precipitator in removing solid particles from a flue gas is reduced so that the precipitator has a lower capacity. Consequently, the capacity of the boiler, which produces the flue gas, must also be lowered to comply with emissions regulations. In the case of a power generation unit, as the capacity of the boiler is reduced, the capacity of a power generating system connected to the boiler is also reduced. In order to maintain an electrostatic precipitator fully effective, it is desirable to maintain the spaced plates of the precipitator in an equidistantly spaced relationship to each other and to the electrodes.
The concept of providing spacers to hold electrostatic precipitator plates apart a uniform distance is known. U.S. Pat. No. 4,007,023, issued Feb. 8, 1977, to Batza et al, entitled, "Electrostatic Precipitator With Collector-electrode Spacers", discloses a construction wherein spacers are hingedly mounted on a pivot. U.S. Pat. No. 4,478,614, issued to John A. Jonelis on Oct. 23, 1984, entitled, "Electrostatic Precipitator Construction Having Spacers" discloses a construction wherein a plurality of individual spacers are positioned between electrostatic precipitator plates. These spacers are mounted directly to the plates or installed by use of a long probe. U.S. Pat. No. 4,479,813, issued to John A. Jonelis on Oct. 30, 1984, entitled, "Electrostatic Precipitator Construction Having Ladder Bar Spacers" teaches a construction wherein a plurality of spacer devices are positioned between electrostatic precipitator plates, each device consisting of a plurality of spacers. These spacers are mounted directly, or loaded from the top or bottom of the plates as practical. It is a principal object of this invention to provide a spacer assembly for use in an electrostatic precipitator wherein the spacer assembly may be interlocked with other spacer assemblies. In this way, more than one spacer assembly is connected together thus forming one construction made up of a plurality of spacers, and connected to the stiffeners of the plates. Spacer assemblies are locked together during installation within the precipitator, thus allowing the construction to be loaded from the top or bottom of the precipitator plates with greater facility than the previous construction. The installed construction can be more readily removed than previous constructions. In addition, the weight of the installed construction aids in the straightening of the collector plates, and the installed construction can be held in tension if required to aid in straightening the plates. The present assembly can be made to add structural strength along the length of the collector plate.