Oxy-fuel is a carbon capture technology for use in power generation, however it is yet to be demonstrated at full scale. One of the issues in its deployment is in the "back end" treatment and removal of flue gas impurities. Oxy-fuel flue gas must be compressed and purified prior to transport and in particular the removal of acid gases is essential to avoid pipeline corrosion. High pressure oxidation of NO_x and its absorption as a condensate is also expected to play a role in mercury capture. Previous oxy-fuel pilot studies have confirmed that compression of raw flue gas has the potential to remove NO_x and SO_x from the gas by the formation of acidic condensates. This is thought to occur principally via the "lead chamber process" involving high pressure NO oxidation followed by catalytic SO_2 oxidation by NO_2. This paper presents measurements of NO conversion (to NO_2) at pressures up to 30 bar using a similar apparatus to previous work at Imperial College. Current single step kinetic NO_x conversion models were found to adequately describe this dry process. A wet system was used which continuously bubbled a stream of NO_x gases through a set volume of water in a short bubble column. The wet pressurised conditions significantly reduced the amount of NO_2 exiting the reactor, producing nitrate and nitrite species in the liquid phase. Higher pressures increased the nitrate ions in the water up to 20 bar, while at higher pressures the nitrate concentrations were reduced in favour of nitrite ion production.
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