Speciation, behaviour, and fate of mercury under oxy-fuel combustion conditions

Patricia Córdoba, M. Maroto-valer, Miguel Angel Delgado, Ruth Diego, Oriol Font, Xavier Querol

Research output: Contribution to journalArticle

14 Citations (Scopus)
69 Downloads (Pure)

Abstract

The work presented here reports the first study in which the speciation, behaviour and fate of mercury (Hg) have been evaluated under oxy-fuel combustion at the largest oxy-Pulverised Coal Combustion (oxy-PCC) demonstration plant to date during routine operating conditions and partial exhaust flue gas re-circulation to the boiler. The effect of the CO2-rich flue gas re-circulation on Hg has also been evaluated. Results reveal that oxy-PCC operational conditions play a significant role on Hg partitioning and fate because of the continuous CO2-rich flue gas re-circulations to the boiler. Mercury escapes from the cyclone in a gaseous form as Hg2+ (68%) and it is the prevalent form in the CO2-rich exhaust flue gas (99%) with lower proportions of Hg0 (1.3%). The overall retention rate for gaseous Hg is around 12%; Hg0 is more prone to be retained (95%) while Hg2+ shows a negative efficiency capture for the whole installation. The negative Hg2+ capture efficiencies are due to the continuous CO2-rich exhaust flue gas recirculation to the boiler with enhanced Hg contents. Calculations revealed that 44 mg of Hg were re-circulated to the boiler as a result of 2183 re-circulations of CO2-rich flue gas. Especial attention must be paid to the role of the CO2-rich exhaust flue gas re-circulation to the boiler on the Hg enrichment in Fly Ashes (FAs).
Original languageEnglish
Pages (from-to)154-161
Number of pages8
JournalEnvironmental Research
Volume145
Early online date14 Dec 2015
DOIs
Publication statusPublished - Feb 2016

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