Combined SO{sub 2}/NO{sub x} removal in the ThioNO{sub x} process -- Regeneration of chelates
Conference
·
OSTI ID:257118
Removing NO{sub x} in wet FGD scrubbers is an attractive option for utility boilers currently equipped with scrubbers to control the emission of SO{sub 2}. Dravo Lime Company (DLC) has developed the ThioNO{sub x} process capable of removing SO{sub 2} and NO{sub x} simultaneously in magnesium-enhanced lime scrubbers. The removal of NO{sub x} was achieved by adding metal chelates into the scrubbing liquor. In a previous proof-of-concept testing of this technology at DLC`s pilot plant using iron-EDTA as the chelate, about 35% of the NO{sub x} was removed across the scrubber by when the plant was operated at the retrofit mode. About 60% of NO{sub x} was removed when the plant was operated in the new plant mode. The corresponding SO{sub 2} removals were 99.5 and 99.9% when the plant was operated in the retrofit and new plant mode, respectively. A key issue remained to be resolved is the economic regeneration of ferrous-EDTA from ferric-EDTA. It is the ferrous chelates that can complex NO and result in its removal from the flue gas. Presented in this paper are the data obtained from tests utilizing a 5 kW scale bench scrubber while thermal, chemical and electrochemical regeneration techniques were evaluated. The last two regeneration techniques are considered equally viable to keep the chelate in the ferrous form. The economics of the ThioNO{sub x} process will also be discussed. Although 50% NO{sub x} reduction was achieved at the pilot plant operated in the retrofit mode earlier this year, it is envisioned that the ThioNO{sub x} process following low NO{sub x} burners is the best retrofit option which can achieve 75% NO{sub x} reduction at costs lower than those associated with the competing ammonia-based SCR technology.
- OSTI ID:
- 257118
- Report Number(s):
- CONF-950952--
- Country of Publication:
- United States
- Language:
- English
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