Statutory Documents - IMO Publications and Documents - Resolutions - Marine Environment Protection Committee - Resolution MEPC.198(62) – 2011 Guidelines Addressing Additional Aspects to the Nox Technical Code 2008 with regard to Particular Requirements related to Marine Diesel Engines fitted with Selective Catalytic Reduction (SCR) Systems – (Adopted on 15 July 2011) - Annex – 2011 Guidelines Addressing Additional Aspects to the Nox Technical Code 2008 with regard to Particular Requirements related to Marine Diesel Engines fitted with Selective Catalytic Reduction (SCR) Systems - 2 General - 2.3 Definitions
2.3 Definitions
2.3.1 Unless provided otherwise, the terms in these guidelines have the same meaning as the terms defined in regulation 2 of MARPOL Annex VI and in section 1.3 of the NTC 2008.
2.3.2 "Engine system fitted with SCR" means a system consisting of a marine diesel engine, an SCR chamber and a reductant injection system. When a control device on NOx-reducing performance is provided, it is also regarded as a part of the system.
2.3.3 "Catalyst block" means a block of certain dimension through which exhaust gas passes and which contains catalyst composition on its inside surface to reduce NOx from exhaust gas.
2.3.4 "SCR chamber" means an integrated unit, which contains the catalyst block(s), and into which flows exhaust gas and reductant.
2.3.5 "Reductant injection system" means a system, which consists of the pump(s) to supply reductant to the nozzle(s), the nozzle(s) spraying reductant into the exhaust gas stream and control device(s) of the spray.
2.3.6 "AV (area velocity) value" means a value of the exhaust gas flow rate passing through the catalyst blocks (m3/h) per total active surface area of the catalyst blocks in the SCR chamber (m2). Therefore, unit of AV value is (m/h). The exhaust gas flow volume is the volume defined at 0°C and 101.3 kPa.
2.3.7 "SV (space velocity) value" means a value of the exhaust gas flow rate passing through the catalyst block(s) (m3/h) per total volume of the catalyst block(s) in the SCR chamber (m3). Therefore, unit of SV value is (1/h). The exhaust gas flow volume is the volume defined at 0°C and 101.3 kPa.
2.3.8 "Total volume of the catalyst block" means the volume (m3) based on outer dimensions of the catalyst block.
2.3.9 "LV (linear velocity) value" means a value of the exhaust gas flow rate passing through the catalyst blocks (m3/h) per catalyst block's section (m2) in a normal direction of exhaust gas flow. Therefore, unit of LV value is (m/h). The exhaust gas flow volume is the volume defined at 0°C and 101.3 kPa.
2.3.10 "Block section" means the cross-sectional area (m2) of the catalyst block based on the outer dimensions.
2.3.11 "NOx reduction rate η" means a value deriving from the following formula. Unit of η is (%):
Where:
- Cinlet is NOx concentration (ppm) as measured at the inlet of the SCR chamber;
- Coutlet is NOx concentration (ppm) as measured at the outlet of the SCR chamber.
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