THERMAL PLASMA SYSTEM APPLIED TO DESTROY C-BASED POLLUTANTS

Air pollution resulting from engines fueled by low quality oils (e.g. HFO) is considered responsible for around 400,000 premature deaths per year worldwide, at an annual cost to society of more than €58 billion. Moreover, the utilization of fossil fuels increases the GHG gases emission in the atmosphere. In relation to maritime sector, the main sources of C-based pollutants and GHGs gases, other than particulate matter (PM), are incinerators and engines. Engines fueled by HFO emit carbon dioxide, hydrocarbons and C-based particulate this latter with an emission factor of 0.56-2.21 g/kWh; engines fueled by LNG or LNG/HFO emit carbon dioxide, a reduced amount of C-based particulate but a larger amount of other methane, due to the methane slip phenomenon. The release of methane into atmosphere results in an increase of GHG impact, larger than the case of LFO use. This paper reports a quantitative assessment of the GHG impact due to methane slip for a commercial 18.3 MW engine and proposes a system to promote the oxidation of unconverted hydrocarbons downstream the turbocharger exit. The proposed system is based on the thermal plasma conversion: the size of an industrial equipment and that of the corresponding down-scaled experimental set-up is described. The plasma converting reactor (PCR) is applicable to flue gas with a good effectiveness in hydrocarbons conversion abatement but the electricity cost necessary to run it with large gas flow rates should be economically unfeasible. Thus, an estimation of electricity cost and capex is given.