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Working with Indigo Technologies, Whitehead Construction has become well versed in the fabrication and installation of bipolar agglomerators for particulate emissions control. The Indigo FPCSystem (Fine Particle Control System) is an easily retrofitted device which agglomerates fine particles to large particles in the flue gases created by fossil (coal/wood) burning boilers, prevalent in the energy and cement industries, to enhance their extraction by electrostatic precipitation or other filtration methods. With 13 worldwide installations to date, the Indigo FPCSystem has established performance improvements as great as a 70% reduction in opacity and 50% reduction of PM2.5, creating a clear stack (emission plume). Due to the high efficiency mixing component of its fluidic processes, the Indigo FPCSystem has also demonstrated marked improvements in sorbent injection efficiencies and utilization.

The Indigo FPCSystem is located in the high velocity ductwork between the air pre-heater and the filtration devices. (ESPs, fabric filters, scrubbers.) It uses both electrostatic and fluidic methods to pre treat all of the dust particles entering the downstream APC equipment by attaching the small to large particles in the gas stream. The larger agglomerates are subsequently more easily collected in an ESP, which is inefficient for removing particles less than three microns. Specifically, the electrostatic process charges the dust half positively and half negatively and then mixes them in a specially designed mixing field. The fluidic process uses a highly specialized, secondary mixing regime to increase the interaction, and therefore impact rate, between the large and small particles, agglomerating them. This same mixing feature can enhance mercury removal with Activated Carbon Injection and, under certain conditions, has been shown to facilitate mercury removal utilizing LOI carbon present in the flue gas stream.

Because the Indigo FPCSystem improves particle to particle interaction, it can also enhance SO3 mitigation with trona, lime and SBS. Due to both utilization of SO3 in the gas stream and enhanced collection efficiencies in the ESP, it also enhances SO3 conditioning and in two installations allowed SO3 conditioning systems to be decommissioned.

Another important benefit provided by the Indigo FPCSystem is its ability to allow a plant to have a greater choice in fuels, which could lower operating and maintenance costs, thereby reducing other pollutant concentrations (sulphur oxides, mercury) whilst still maintaining PM regulatory compliant emission levels that could not have previously been met.

The fine particles addressed by the FPCSystem are some of the most dangerous to the environment as they contain the majority of heavy metal toxins (cyanide etc.) and are easily carried by air movement, sometimes traveling large distances. These fine particles are also the most respirable, resulting in major health risks and have been implicated in contributing to global greenhouse conditions.

The Indigo FPCSystem provides a zero footprint, totally retrofit solution for compliance with the new PM 2.5 emission standards. Removing the fine particulate also has a beneficial effect on bag houses as it is this fraction of the PM that causes pressure drop and bag blinding.  By reducing bag blinding, the bags will require less frequent cleaning, extending bag life and reducing operating costs.

Ongoing developments include enhancements in other applications. Indigo Technologies can be contacted directly for further information: (412) 358-0171, or http://www.indigotechnologies-us.com/.