Chemical Conditioning

Conditioning can enhance collection efficiency by reducing resistivity to prevent back corona, increasing cohesivity of the collected layer, enhancing the electric field by increasing the space charge contribution (see below), and increasing agglomeration of small particles. Some exhaust gas conditioning methods which have been used to enhance ESP performance are cooling by in-leakage of cold air, heat exchange to a waste heat boiler, evaporative spray, and chemical conditioning. The latter has proven most popular in utility applications.

Most commonly, sulfur is combusted and the SO2 produced is catalytically converted to SO3. On combination with the combustion exhaust, SO3 hydrolyses to produce H2SO4, sulfuric acid. The acid deposits efficiently on fly ash particles, decreasing the particle surface resistivity. SO3 is added at levels of 1-10 ppm; up to 30 ppm can be added without significant increase in sulfur emission from the ESP. Significant SO2 is produced on combustion of even low sulfur coal, but only about 1% is converted to the useful SO3. Knowledge of the importance of SO3 was initially gained through experience with conditioning of smelter dusts by sulfide ores.

Ammonium salts were found to be effective when H. J. White was consulted on the problem of decreased ESP efficiency which resulted from a change in petroleum cracker catalyst. He found that replacing ammonia, released by the initial catalyst, recovered ESP performance. As NH3 increases collection efficiency with both low and high resisitivity boiler ash, and may or may not decrease resistivity, it is thought that this conditioner functions by furnishing salt particles which increase the space charge contribution to the electric field and, by increasing dust cohesiveness, reduce rapping losses.

Solar Panel Basics

Solar Panel Basics

Global warming is a huge problem which will significantly affect every country in the world. Many people all over the world are trying to do whatever they can to help combat the effects of global warming. One of the ways that people can fight global warming is to reduce their dependence on non-renewable energy sources like oil and petroleum based products.

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