A study of the effect of chloride on mercury removal in a fluidized bed combustion (FBC) system
Mercury exists in three forms, which are elemental mercury, inorganic mercury compounds, and organic mercury. Each form of mercury has a very different exposure potential. Oxidized mercury is soluble and has a tendency to associate with particles. Nearly all the post-combustion flue gas cleaning systems proposed to remove mercury may be categorized as either scrubbers or adsorbers. Therefore, the mercury sink in the cleaning system will be either the excess water of a wet scrubber or the mercury laden sorbent from an absorber. The major problem for post-combustion mercury capture systems is capturing the practically water-insoluble elemental mercury. Co-firing with high chlorine coal or RDF in utility boiler systems can provide an HCI atmosphere for the oxidation of elemental mercury in flue gas at relatively low temperatures (500--600 C). The objective of this study is to increase the efficiency of mercury emission cleaning methods by using HCl to convert elemental mercury to oxidized mercury species at low monetary costs and lower other toxic air emissions. When high chlorine (0.3--0.5%) coals were burned and a high intensity vortex flow (from secondary air) was used, around 70% of the total mercury in the fuel was condensed and absorbed by the fly ash (including calcium compounds). The remaining 30% of total fuel mercury was emitted in the gas phase in the flue gas. As for the gas phase mercury, about 98% of it exists in an oxidized form with a higher boiling temperature than elemental mercury and can be easily captured by an ESP or FGP apparatus. Only about 0.5% of the total fuel mercury was released to the atmosphere in elemental form.
- Research Organization:
- Western Kentucky Univ., Bowling Green, KY (US)
- Sponsoring Organization:
- Illinois Clean Coal Institute; Electric Power Research Institute
- OSTI ID:
- 20034327
- Resource Relation:
- Conference: 25th International Technical Conference on Coal Utilization and Fuel Systems, Clearwater, FL (US), 03/06/2000--03/09/2000; Other Information: PBD: 2000; Related Information: In: 25th international technical conference on coal utilization and fuel systems: Proceedings, by Sakkestad, B.A. [ed.], 969 pages.
- Country of Publication:
- United States
- Language:
- English
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