Hot flue gas filtration: Laboratory tests and projected cost of a combined sorbent injection/filtration technique
This manuscript provides an update on the technology of flue gas filtration at high temperatures. In this technology the synergistic effects of sorbent injection and filtration are exploited. Calcium-based (or sodium-based) sorbents are sprayed in the post-flame zone of a furnace. The sorbent reacts with sulfur and chlorine in the furnace effluent to form stable salts of calcium. The partially-reacted sorbent is then collected in the filter, which is placed downstream of the sorbent injection point. The sorbent continues to react in the filter for a prolonged period of time. The primary advantage of this technique is that both the likelihood of contact and the period of contact between the solid sorbent particles and the gaseous pollutants (such as SO{sub 2}, H{sub 2}S, HCl, etc.) increase, since reaction takes place in the furnace upstream of the filter as well as inside the filter itself. Hence, the sorbent utilization (i.e., the conversion of sorbent CaO to CaSO{sub 4}, CaSO{sub 3}, CaCl{sub 2}, etc.) increases significantly. The filter is cleaned with periodic aerodynamic regeneration (backpulsing). Using this technique, most of the pollutants, such as SO{sub 2}, H{sub 2}S, HCl and particulate (soot, ash and tar) can be removed from the effluent. Any unburned carbon in the ash may be completely oxidized in the filter. Formation of dioxins in the effluent at lower temperatures should be minimized, since their precursors are captured by the filter. Results show That the sorbent/filter method appears to be less expensive than current technologies, on both capital cost ($/kW) and levelized coat ($/ton pollutant removed) bases, if a limestone/coal mixture is used as the sorbent for the fossil fuel plants. Capital costs for the filter/sorbent combination should be under $63/kW for a new plant, while those for a state of the art compounded wet limestone FGD/SCR/fabric filter at $250--400/kW. Since the existing technologies are designed for removing one pollutant at a time both their cost and space requirement are much higher than those of the technique discussed herein. Moreover, the levelized costs are projected to be as low as $103/ton of combined pollutant SO{sub 2} and NO{sub x} and particulates removed.
- Research Organization:
- Northeastern Univ., Boston, MA (US)
- Sponsoring Organization:
- National Science Foundation (NSF)
- OSTI ID:
- 20034330
- 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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