Exhaust gas emissions

1. Exhaust gas emissions Complete combustion of hydrocarbons creates only CO2 and H2O. CO2 is a harmful greenhouse gas, but yet no limitations for ships. Thus high hydrogen content in fuel means ecologically good fuel. Non-complete combustion creates CO, VOC (Volatile Organic Compounds), PM (Particulate Matter). Carbon monoxide CO is toxic; rapidly oxidized in open air VOC promotes harmoful smog. Many of the VOC’s are also pathogenes, PAH. Particles are harmful, especially the smallest (<5m) to human respiratory system.

2. Exhaust gas emissions Sulphur is typically present in heavy fuel oil. All this sulphur is oxidized and produced energy. It creates during comubstion gaseous SO2 and SO3 that promote soil acification and smog. During combustion part of air nitrogen and fuel oil nitrogen are oxidized. These oxides (common name NOx) highly promote greenhouse effect, soil acification and smog.

3. Emission control Exhaust gas emissions receive high attention. Quantity limitations have led into locally and even globally valuable results. Sanctions have been introduced and some ships paid penalties for emitting visible smoke in Alaska. Stockholm in Sweden had introduced rewards in port and waterway fees for ships using environmental technology or fuel. Comparison with land based plants is not straigthforward. Oceans are not so vulnerable but many port and coastal areas are. Besides exhaust gas emission also volative cargo gases of oil tankers have received attention.

4. Exhaust gas emissions IMO, EU have announced limitations on fuel sulphur content. Alternatively sulphur removal of the gases is acceptable. HFO oil sulphur content depends on the crude oil base. Sulphur can be removed in refinery, but it is expensive. Compatibility problems can also be expected. Low sulphur fuels were not expensive during 1990ies. (HFO 100, MDO 150, LS-HFO 140 USD/1000 kg). High price raises in 2005 (HFO 200, MDO 350) cannot predict the price trend of low sulphur HFO. When demand will grow several times higher, the refinery capacity will be worldwide far insufficient.

5. Pakokaasupäästöt Amount of other gaseous and particulate emissions depends on the engine combustion process and engine load. Particles and visible smoke are created especially during rapid load increase. Smokeless engine is a marketing slogan. Diesel engine control so that emissions are low also outside nominal power is a hard target. Electronically controlled or common rail engines: Valve opening timing with hydraulic actuators and electronic control. Fuel oil injection timing electronically controlled. Fuel reservoir on the engine at 1200 ... 1600 bar pressure. Common reservoir for many cylinders, therefore called common rail engine.

6. Nitrogen oxides 201816141210 8 High combustion temperature and pressure are fabourable for engine fuel economy but also increase nitrogen osides emission. The continuous comubstion in gas turbines is more advantageous in this respect. IMO limit curve since 2000 stating emissions g/kWh vs. engine rpm. 0 500 1000 1500 2000

7. Alternative ways to limit diesel engine NOx emissions Guidance figures only, development in continued

8. CASS Turbocharger Fresh water tank Return line Suuttimen ohi kiertä-vä vesi Drain of the non-evaporated water Control unit

9. SCR Catalyst reactor fitted to 6- cylinder aux. engine NOx analysing unit Urea solution tank Control unit FI SCR reactor Pumping and injection unit

10. Wärtsilä SCR Converter / silencer Emission metering Temp. transmitter Press differ. transm. Converter NO Analyser & control unit Dust blowers Working air Static mixers Urea/air injector 40% urea solution 5 – 10 % of bunker capacity Pump/ filter unit Diesel engine Flow dresser

11. P&O Trial – Gas scrubber layout • Gas emerges under (green) inner plenum • Gas passes through 200mm water layer • Mixing vanes break up large gas paths, and keep water in contact with exhaust • Water recirculation spray cools gas as it travels upwards • Cleaned gas passes through mist-eliminator (yellow) • Cleaned gas is reheated by green plenum before passing upwards to outlet

12. Scrubbed & re-heated exhaust gases Scrubbed gas re-heat section Sea Water S.W. discharge to cyclone separator & heat exchanger S.W. Inlet Exhaust Gases P&O Trial – Gas scrubbing layout cont’d Intimate mixing of exhaust gas and sea water

13. P&O Trial – Gas scrubber pilot unit P&O Trial – mv Pride of Kent installation

14. P&O Trial – Gas scrubber pilot plant Sea Water Scrubbing – Key system components

15. P&O Trial – Gas scrubber pilot plant • SOx reduction ~ 95% • NOx reduction ~10 - 20% • Particulate reduction ~ 80% • Low weight • Minimal additional footprint • Low energy consumption • Low maintenance • Retention of unburnt hydrocarbons on board for safe disposal • Greater emissions benefit than using distillate fuel oil

16. P&O Scrubber gas cleaning program

17. P&O Trial – Gas scrubber pilot plant • Sea water scrubbing does not suit all vessel operators • For large ships operating within EU waters all the time the case is very challenging • CASE STUDY • Ferry consuming approximately 20kt/year • Estimated investment €2.0m • Cost over 10 years = €20/t • EC estimates premium €50/t for distillate fuel oil