Use of manganese compounds to improve the efficiency of and reduce back-corona discharge on electrostatic precipitators

Abstract

Manganese is added to a combustion fuel, combustion air, or the resulting combustion exhaust gas in order to improve the efficiency of an electrostatic precipitator in collecting the resulting fly ash. Further, manganese or other flame suppressant is added to a fuel, and / or combustion air, or combustion exhaust gas stream in order to reduce back-corona discharge that could otherwise occur in an electrostatic precipitator.

Description

FIELD OF THE INVENTION [0001] The present invention relates to improving the efficiency and operation of electrostatic precipitators in utility and industrial furnace systems. Specifically, the addition of manganese in fuel, in the combustion air, or in combustion exhaust gas (flue gas) increases the efficiency of an electrostatic precipitator in collecting the fly ash from the combustion gas. Further, the addition of manganese or other flame suppressant materials into fuel, into combustion air, or into combustion exhaust gas reduces back-corona discharge in electrostatic precipitators, thus also improving fly ash collection efficiency. BACKGROUND OF THE INVENTION [0002] The environmental issues and concerns with respect to smoke stack emissions are well recognized. One of the combustion exhaust gas products that receives considerable attention is fly ash. Much technology and effort has been dedicated to reducing fly ash emissions that are the result of the combustion of hydrocarbon...

AI Technical Summary

Benefits of technology

The use of manganese and other additives increases the efficiency of fly ash collection by maintaining optimal resistivity and preventing back-corona discharge, allowing for higher voltage operation and improved power generation without exceeding opacity regulations, resulting in a significant increase in power output and collection efficiency.

Problems solved by technology

Carbon in the fly ash lowers the resitivity so much that efficient collection in the ESP is impeded.

If the particles are highly conductive (i.e., have an excessively low resistivity), then the particles give up there charges very easily and are relatively difficult to retain on a collector plate.

An example of this is high carbon content in fly ash, which is known to contribute to electrostatic precipitator inefficiency.

After a relatively short period of time, the build up of those particles may block the electric flow necessary for the efficient operation of systems.

This build up of high resistivity particles on collector plates also presents other performance problems.

If the electrostatic precipitator voltage becomes too large because of excessively high resistivity of the fly ash (above 109 Ohm cm), gas trapped in this particle layer can ionize and break down, thereby causing a spark or flare that substantially reduces the efficiency of the electrostatic precipitator.

To inhibit this event, ESP controls back off on the potential between the electrodes (reduce the voltage to the electrodes), thereby leading to performance inefficiency and an increase in steady state exhaust opacity.

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