Reducing Emissions from Shipping Wärtsilä s Solutions

Transcription

1 Reducing Emissions from Shipping Wärtsilä s Solutions Arnauld Filancia, Director, Marketing & Communications Wärtsilä Corporation, Services 1 Wärtsilä version 9.0 /Arnauld Filancia

2 Environmental Equation & Solution levers 2 Wärtsilä version 9.0 /Arnauld Filancia

3 Environment equation for the industries and regulators Reducing emissions Quantity Reduce speed Hull & propulsion design Paint coatings Machinery efficiency Recovery systems Training & Maintenance Quality Machinery efficiency Secondary technologies Gas, dual-fuel Bio fuel... while limiting CO 2 emission energy spoil Limit overall production of CO 2 from fuel extraction to stack outlet Best usage of our energy reserves 3 Wärtsilä version 9.0 /Arnauld Filancia

4 Wärtsilä, provider of Environmental Solutions for industry Secondary Technologies SCR Scrubbers Oily Water Separation Low Loss Concept Primary Technologies Common Rail Direct Water Injection Propeller design Thruster design Safety Environment Efficiency Ship Design Efficiency & Innovations Fuel Cell Oil lubricating stern tube bearings Pulse lubrication System Combo module Fuel & Gas Dual Fuel engine Bio fuel engine Gas Engines Conversions Hull optimization Podded Contra Rotating Propeller Double Acting Pusher Puller Barge Conceptual Design 4 Wärtsilä version 9.0 /Arnauld Filancia

5 - Case story - Helix Energy Solutions, MSV Q Wärtsilä version 9.0 /Arnauld Filancia

6 Helix Energy Solutions, MSV Q4000 Thrusters of a dynamic positioning vessel must be available virtually all the time. Hundreds of thousands of dollars in daily revenue, the on-time completion of multimillion dollar subsea construction projects, and sometimes even subsurface workers lives... All depend on the vessels six thrusters maintaining position within a few metres 24/7. boost reliability increases the efficiency of engines made more power available removed the need to install dedicated alternators 6 Wärtsilä version 9.0 /Arnauld Filancia

7 Helix, MSV Q4000 Reliability issues with the auto-transformers used to start the original fixed speed motors Wärtsilä s variable speed drive for Q4000 thruster motors improves reliability boosting operating efficiency of the power network from 50 to 80% SITUATION BEFORE SITUATION AFTER Wärtsilä s innovative use of a quasi-24 pulse arrangement of the thruster drives reduced capital outlay and installation costs. At the same time, the upgrade gave the vessel a variable speed thruster control system which produced a very low harmonic distortion on the vessel s distribution network. 7 Wärtsilä version 9.0 /Arnauld Filancia

8 Helix MSV Q4000 At the same time as the thruster upgrade, Helix installed a complete modular drilling package on board the Q4000. The new drilling process loads created a demand for more MW from the vessel. Prior to the conversion the vessel consumed around 40 cubic metres of Marine Diesel Oil (MDO) per day. Since the conversion, daily consumption is now in the low 20s. Due to the efficiency improvements gleaned from the thruster drive upgrade, no new generators were required to feed the drilling package. A huge savings in capital, maintenance costs, and environmental impact. 8 Wärtsilä version 9.0 /Arnauld Filancia

9 - Case story - MV Trygvason, Sweden 9 Wärtsilä version 9.0 /Arnauld Filancia

10 MV Trygvason Built in 1988, MV Trygvason is a single-screw trawler originally equipped with an open type, 2600mm-diameter CPP. The vessel is powered by a Wärtsilä Nohab F38A with an output of 1580kW, running on marine diesel oil. Owner was seeking a propulsion retrofit to save fuel. 10 Wärtsilä version 9.0 /Arnauld Filancia

11 Bollard pull: 21 -> 30 tons; Fuel reduction 30% It s much quieter onboard now, says MV Trygvason s Captain Støle Lønning. Wärtsilä s nozzle solution was the most effective. We can now use more efficient trawling equipment, and we haven t suffered any loss in sailing speed, something which has happened to others. The entire conversion process from initial discussions to sea trials of a new installation takes 6-12 months. The retrofit was carried out in Norway, Trawler out of operation for about two weeks. Bollard pull increase of 29%, 13% improvement in free-running efficiency. The ROI for this rebuilding was less than 2 years. 11 Wärtsilä version 9.0 /Arnauld Filancia

12 Wärtsilä's Propulsion Services 12 Wärtsilä version 9.0 /Arnauld Filancia

13 Sulphur Regulation Means of Compliance 13 Wärtsilä version 9.0 /Arnauld Filancia

14 Marine Seawater Scrubber (SWS) system, typical flows Exhaust Gas OPEN LOOP Parasitic losses 3% fuel consumption Scrubber Open loop is often met for seawater scrubber, the sulphur is neutralized by water alkalinity. 500 m3/h 10 MW 500 m3/h 10 MW Water Treatment Sludge tank Seawater ph management >500 m3/h 10 MW ph 14 Wärtsilä version Do 9.0 not /Arnauld copy, utilize Filancia or distribute any part of this presentation without express confirmation in writing from the author.

15 Marine Fresh Water Scrubber (FWS) system, typical flows Closed loop works with freshwater, to which NaOH is added for the neutralization of SOx. NaOH unit 100 m3/h 10 MW ph Exhaust Gas Scrubber ph 1 m3/h 10 MW Fresh water Water Treatment CLOSED LOOP = Zero discharge in enclosed area Parasitic losses 1% fuel consumption Sludge tank Cooling Process tank Holding tank Seawater 1,77 m3/h 10 MW 1,7 m3/h 10 MW 15 Wärtsilä version 9.0 /Arnauld Filancia

16 Parasitic losses of FW scrubbers 16 Wärtsilä version 9.0 /Arnauld Filancia

17 Operating Expenditures, FWS vs SWS If a ship clearly is intended to operate only in alkaline waters, and local wash water regulations allow effluent discharges in the intended operational areas, SWS and FWS will compete on commercial terms. However, this is still not the case anywhere in the world. Seawater Scrubbers Pumping costs 2-3 % of fuel cost Freshwater Scrubbers Pumping costs 0,5-1 % of fuel cost NaOH cost ~2 % of fuel cost in average OPEX are similar in both cases Fresh Water cost is negligible. Pumping cost of evaporator pumps are marginal, very small pumps. Evaporators need heat, which should be waste heat and free of charge. If a (2-stage) reverse osmosis plant is selected, there will be pumping costs, but this is the reason we recommend evaporators. The evaporator is, however, a CAPEX item. 17 Wärtsilä version 9.0 /Arnauld Filancia

18 SO 2 chemistry 18 Wärtsilä version 9.0 /Arnauld Filancia

19 Sulphurous acid and Bisulphite ion H 2 SO 3 Sulphurous Acid Upon dissolution in water, SO 2 forms the hydrate SO 2 H 2 O or sulphurous acid H 2 SO 3, which dissociates rapidly to form the bisulphite ion HSO 3- which in turn oxidized to sulphate. 100% % of total sulphurious acid 0% Sulphur dioxide Sulphurous Acid SO 2,gas SO 2,aq + H 2 O H 2 SO 3 HSO - SO 2- Sulphurous Acid Bisulphite ion H 2 SO H 2 SO 3 H + + HSO 3- Bisulphite ion H + + HSO 3-2H + + SO 3 2- At seawater ph: 80% SO % HSO 3 - Each molecule of neutralized Sulphur will release protons. 19 Wärtsilä version 9.0 /Arnauld Filancia

20 Alkalinity, the driving parameter for neutralization Alkalinity reflects the ability to react with acids and neutralize them Total Alkalinity (A T ) A T = [HCO 3 ] T + 2.[CO 3 ] T + [OH ] T [H + ] sws [HSO 4 ] + [B(OH) ] T + 2.[PO 4 ] T + [HPO 4 ] T + [SiO(OH) ] T When acid is added to high alkalinity water, the ph of water decreases and the buffering capacity is used slow ph decrease to 6 rapid drop from ph 6 to 5.5 weak buffering capacity from ph 5.5 to 4.5 buffering capacity used at ph 4.5, no alkalinity left 20 Wärtsilä version 9.0 /Arnauld Filancia

21 Sulphur reduction versus water PH 100% SO 2 reduction Alkaline power reduces as neutralization takes effect. 50% 0% ph Wärtsilä version 9.0 /Arnauld Filancia

22 Sulphur reduction versus water PH Alkaline power reduces as neutralization takes effect, it is then controlled by: adjusting flow in sea water scrubbers, or adjusting caustic quantity in fresh water scrubbers % Efficiency ph 7 1 st stage 2 nd stage 50% The second stage of scrubber increases efficiency 0 Time in scrubber 0% 22 Wärtsilä version 9.0 /Arnauld Filancia

23 CO 2 chemistry 23 Wärtsilä version 9.0 /Arnauld Filancia

24 Ocean absorbs million tons CO 2 each year 100% In seawater, dissolved CO 2 and carbonates are related as follows: 50% H 2 CO 3 H 2 O + CO 2 H 2 O + CO 2(aq) CO 2 (aq) H 2 CO 3 HCO 3 - CO 3 2- H 2 O + H 2 CO 3 HCO 3- + H 3 O + Bicarbonate 0% Relative abundance of carbonic acid, bicarbonate ion and carbonate ion in seawater. At seawater ph: 24 Wärtsilä version 9.0 /Arnauld Filancia 75% HCO 3-25% CO 3 2- H 2 O + HCO 3 - CO H 3 O + Carbonate Addition of sulphuric acid shift the above chemical equations to the left hence releasing some molecules of CO 2 for each S.

25 Sodium Oxide NaOH Sodium Oxide The hydration of sulphuric acid is thermodynamically favourable ( H = 880 kj/mol). The affinity of sulphuric acid for water is sufficiently strong that it will take hydrogen and oxygen atoms out of other compounds: Wellmann-Lord process 2.NaOH + SO 2 Na 2 SO 3 Na 2 SO 3 + SO 2 2.NaHSO 3 Sodium Oxide Sulphur dioxide Anhydrous Sodium Sulphite An.Sodium Sulphite Sulphur dioxide Sodium Bisulphate In Freshwater scrubbers, SO 2 is bind to a salt and consequently does not react with natural bicarbonate of sea water. There is no release of CO 2. 2.NaOH + SO 2 Na 2 SO 3 + H 2 O NaOH + 2.H 2 SO 4 NaHSO 4 + H 2 O Sodium Hydrogen Sulphate Na 2 SO 3 +SO 2 +H 2 O 2.NaHSO 3 Sodium Bisulphate 2.NaOH + H 2 SO 4 Na 2 SO H 2 O Sodium Sulphate 25 Wärtsilä version 9.0 /Arnauld Filancia

26 Creation of CO 2 in FW (caustic soda) scrubbers? H 2 SO 3 + NaHCO 3 NaHSO 3 + H 2 CO 3 NaHSO 3 + CO 2 + H 2 O Sulphurous Acid Sodium Bicarbonate Sodium Bisulphate Carbonic Acid 100% H 2 CO 3 At seawater ph: 75% HCO 3-25% CO % HCO 3 - CO 3 2-0% Relative abundance of carbonic acid, bicarbonate ion and carbonate ion in seawater. The ph of the effluent does not allow the existence of H 2 CO 3, hence there are not creation of CO 2 when discharging effluent from freshwater scrubber system at sea. 26 Wärtsilä version 9.0 /Arnauld Filancia

27 CO 2 in different systems 27 Wärtsilä version 9.0 /Arnauld Filancia

28 Theoretical calculation of CO 2 creation Molar masses: CO 2 = 44,0095 g/mol S = g/mol 1kg of S 75% HCO 3-25% CO 3 2-2x H 3 O + 2x H 3 O + 80% SO > 0,200 kg S 2x CO 2 per SO 2 1x CO 2 per SO 2 { 60% ; 2 } { 20% ; 1 } -> 0,600 kg S -> 1,647 kg CO 2 -> 0,274 kg CO 2 1x H 3 O + 1x H 3 O + 20% HSO 3 - -> 0,050 kg S 1x CO 2 per SO 2 0,5x CO 2 per SO 2 { 15% ; 1 } { 5% ; 0,5 } -> 0,150 kg S -> 0,206 kg CO 2 -> 0,034 kg CO 2 1 kg S ~ 2,16 kg CO 2 Theoretically, in sea water process It actually is lower than 2 as activation energy is not available. 28 Wärtsilä version 9.0 /Arnauld Filancia

29 Natural reaction, without seawater scrubber 19 Mt SO 2 19 Mt CO 2 created by SO 2 reacting with sea water Residual fuel 2,7%S is equivalent to 9,5 Mt/y S for a shipping consumption of 350 million tons/year Ship with no EGCS Ship Ocean naturally absorbs million tons CO 2 each year 2,7%S from stack creates 19 million tons CO 2 per year at sea 29 Wärtsilä version 9.0 /Arnauld Filancia

30 Ships with seawater scrubber 18, 6 Mt CO 2 Sulphur reduced to 0,1%S 0,1%S reacting with seawater at sea creates an additional 0,70 Mt CO 2 Residual fuel 2,7%S is equivalent to 9,5 Mt/y S for a shipping consumption of 350 million tons/year + 2-3% extra power needed Ship with SW scrubber Ship Seawater scrubber reduces Sulphur from stack down to 0,1%S 2-3% extra power creates its share of CO 2 Total CO 2 created with seawater scrubber is ~19,3 Mt CO 2 /year 30 Wärtsilä version 9.0 /Arnauld Filancia

31 Ships with freshwater scrubber No CO 2 created in FW scrubber Sulphur reduced to 0,1%S 0,1%S reacting with seawater at sea creates an additional 0,70 Mt CO 2 Residual fuel 2,7%S is equivalent to 9,5 Mt S for a shipping consumption of 350 million tons/year + 1% extra power needed Ship with FW scrubber 2,36 Mt CO 2 /year Freshwater scrubber reduces Sulphur from stack down to 0,1%S No CO 2 is created neither in scrubber nor at effluent discharge Total CO 2 created with fresh water scrubber: estimated to 3 Mt/year 31 Wärtsilä version 9.0 /Arnauld Filancia

32 Estimates from International Energy Agency David Martin Refining Analyst Oil Industry & Markets Division Heat Pressure / Catalyst Hydrogen All produce CO2 the cleaner and lighter the incremental product required, the higher the CO2 emissions generated. MT/year Simplistic approach Assume that more complex refinery capacity is available +53 Investment driven Assume that wide range of product is blended to meet bunkers +68 Real World Additional crude will need to be processed to meet shortfall MT for Hydrogen production needed in refinery process Raise in CO2 emission from refineries 32 Wärtsilä version 9.0 /Arnauld Filancia

33 Ships with Distillates >100 Mt CO 2 /year created in refineries SOx reacting with seawater at sea creates an additional 3,5 Mt CO 2 3,5 Mt SO 2 50 Mt CO 2 /year Residual fuel 0,5%S Residual fuel 0,5%S is equivalent to 1,75 Mt/y S for a shipping consumption of 350 million tons/year. All distillates reduces Sulphur from stack down to 0,5%S CO 2 is created in refineries and for production of Hydrogen: 150 Mt/year CO 2 is created from the remaining Sulphur in exhaust gases: 3,5 Mt/year 33 Wärtsilä version 9.0 /Arnauld Filancia

34 Summary of alternatives 2,7% All Distillates SW scrubber FW scrubber Sulphur 0,5% 0,1% 0,1% CO 2 19 Mt/y > 100 Mt/y 19,3 Mt/y 3 Mt/y 34 Wärtsilä version 9.0 /Arnauld Filancia

35 Wärtsilä's Marine Scrubber Certification Results 35 Wärtsilä version 9.0 /Arnauld Filancia

36 MT Suula Wärtsilä scrubber on Neste Oil MT Suula Test starts in Nob 8 th, 2008 and Certified September Wärtsilä version 9.0 /Arnauld Filancia

37 IMO Scrubber Guidelines 37 Wärtsilä version 9.0 /Arnauld Filancia

38 SO 2 reduction 38 Wärtsilä version 9.0 /Arnauld Filancia

39 NO x reduction 39 Wärtsilä version 9.0 /Arnauld Filancia

40 PARTICLE EMISSIONS - Suula Particle emissions were measured before and after the scrubber on two different fuels (high sulphur fuel and low sulphur fuel). ISO-8178 measurements Turku University of Applied Sciences Fuel sulphur contents were 1,5% and 2,1%. Five different scrubber load levels (10%, 25%, 50%, 75% and 100%) with both fuel sulphur contents. 40 Wärtsilä version 9.0 /Arnauld Filancia

41 ISO Results PARTICULATE MEASUREMENTS ISO-8178 Reduction (%) Reduction, S 1,5% Reduction, S 2,1% PM reduction (%) Engine test load(%) 41 Wärtsilä version 9.0 /Arnauld Filancia

42 PM in diesel engine Example of simplified number and mass size distribution of particulates of diesel exhaust. After formation inside the cylinder, the nanometre-sized primary particles coagulate to form larger particulates to which are attached, as the exhaust gas cools, hydrocarbons and sulphates. Secondary particulates can be formed outside the engine combustion chamber as a result of the absorption and condensation processes. 42 Wärtsilä version 9.0 /Arnauld Filancia Wärtsilä study, presented at CIMAC in May 2007, in Vienna

43 Sizes & Physical Characteristics of various Dusts SIZE [micron] TYPICAL RANGE OF ATMOSPHERIC IMPURITIES TYPICAL RANGE OF COLLECTORS GRIT DUST FUME RAINDROP MIST FOG TOBACCO SMOKE PULVERISED COAL FLY ASH CARBON BLACK FOUNDRY SAND BACTERIA VIRUS POLLEN SO 3 MIST TEMP. ATMOSPHERIC IMPURITIES PERMANENT ATMOSPHERIC IMP. CEMENT DUST ZINC OXIDE FUME INCINERATOR DUST SETTLING CHAMBERS CYCLONES HIGH EFFICIENCY CYCLONES SCRUBBERS FABRIC FILTERS ELECTROSTATIC PRECIPITATORS Fuel and lube oil quality Engine combustion process Exhaust gas cleaning 43 Wärtsilä version 9.0 /Arnauld Filancia

44 WÄRTSILÄ CARES ABOUT CLEAN SKYS 44 Wärtsilä version 9.0 /Arnauld Filancia

45 AND CLEAN WATERS 45 Wärtsilä version 9.0 /Arnauld Filancia

46 Effluent quality 46 Wärtsilä version 9.0 /Arnauld Filancia

47 EFFLUENT - ph Scrubbing wash water ph is automatically monitored and controlled by NaOH dosing. The ph control assure that the ph of the discharge water is always over 6,5. 7,8 7,6 7,4 7,2 7 PH IN WASH WATER AND IN DISCHARGE WATER IMO limit: The ph of the discharge water should not be less than 6,5. Wash water Discharge water IMO limit ph 6,8 6,6 6,4 6,2 6 5,8 1,5 3,4 Fuel sulphur content (% m/m) 47 Wärtsilä version 9.0 /Arnauld Filancia

48 Water Treatment Unit Performance 48 Wärtsilä version 9.0 /Arnauld Filancia

49 EFFLUENT - Phenanthrene In the water treatment unit the phenanthrene reduction is in low sulphur fuel 97,9% and in high sulphur fuel 97,4%. PHENANTHRENE IN THE WASH WATER AND IN THE DISCHARGE WATER IMO limit: The phenanthrene concentration of the discharge water should not be over 1226 µg/l Wash water Discharge water IMO limit 800 µg/l ,5 3,4 Fuel sulphur content (% m/m) 49 Wärtsilä version 9.0 /Arnauld Filancia

50 Discharged water versus IMO limit 50 Wärtsilä version 9.0 /Arnauld Filancia

51 Documentation during certification 51 Wärtsilä version 9.0 /Arnauld Filancia

52 Documentation during certification 52 Wärtsilä version 9.0 /Arnauld Filancia

53 Safety concept 53 Wärtsilä version 9.0 /Arnauld Filancia

54 Certification by DNV and GL 54 Wärtsilä version 9.0 /Arnauld Filancia

55 55 Wärtsilä version 9.0 /Arnauld Filancia Case studies

56 Example of fresh water scrubber set-up Wärtsilä's CSS (Compact Silencer) 56 Wärtsilä version 9.0 /Arnauld Filancia

57 Wärtsilä Scrubber 57 Wärtsilä version 9.0 /Arnauld Filancia

58 58 Wärtsilä version 9.0 /Arnauld Filancia Case study - retrofit

59 Wärtsilä Integrated Scrubber Diesel-electric EG fan on cold side 59 Wärtsilä version 9.0 /Arnauld Filancia

60 Summary of integrated scrubber 1. Avoid increased exhaust gas back pressure caused by cleaning devices. 2. Reduce the amount of equipment needed for SOx-cleaning of exhaust gases from all relevant combustion units onboard. 3. Provide a higher cleaning performance in port conditions where the total flow of exhaust gases is smaller than in normal seagoing conditions, utilising such higher performance as inherent in some exhaust gas cleaning devices when operated at reduced exhaust gas flow. Thus all combustion units can use the same fuel in all areas and all conditions. 4. Substantially reduces the CAPEX 60 Wärtsilä version 9.0 /Arnauld Filancia

61 Where is the NOR going to be fitted? Nitrogen Oxide Reducer 61 Wärtsilä version 9.0 /Arnauld Filancia

62 Bro Sincero case Bro Sincero is a single-deck chemical and product tanker with a double hull and diesel-electric propulsion. She was upgraded in 2007, in 10 days. Wärtsilä s Nitogen Oxide Reducer (NOR) system helped Swedish Donsötank clean up its nitrogen oxides (NOx) emissions and get a leg up on its competitors. 62 Wärtsilä version 9.0 /Arnauld Filancia

63 Design Parameters Equipment on board Main engine(s) Auxiliairy engines Boiler(s) Operating routes Nbr of hours in ECA waters Nbr of hours out of ECA waters Current configuration Tank arrangement Actual back pressure Noise attenuation Available space in stack Exhaust diameter Elevation Ship design layout Load profile vs itinerary In port In maneuvering At sea, high load At sea, low load Other specifics, season loading ROI = CAPEX Savings per year Saving = f { HFO LS-HFO ; running hours in ECA } Capital investment ( /kw) reduces as plant size increases 63 Wärtsilä version 9.0 /Arnauld Filancia

64 Real feasibility studies Main engine power MCR kw Auxiliary engine power 3 x 900 kw Oil fired boiler capacity 2 x 30 ton / h Yearly bunker consumption ME ton Yearly bunker consumption AE 600 ton Yearly bunker consumption OFB ton 64 Wärtsilä version 9.0 /Arnauld Filancia ALT 1 Integrated scrubber ALT 2 Main stream scrubber ALT 3 Compliance by fuel Number of scrubbers Fuel HFO HFO, MGO MGO Scrubber technology Fresh water Fresh water - Applicable to ME, AE and OFB ME only ME, AE and OFB Fuel HFO HFO for ME MGO for AE and OFB Scrubber design capacity 100 % MCR main engine Integrated scrubber 100 % MCR main engine and 80 % MCR of one auxiliary engine in max sea going conditions Main stream scrubber Price of HFO 250,00 USD / ton Price of MGO 433,50 USD / ton MGO Running on MGO HFO [t/year] MGO [t/year] Fresh water [m 3 /year] NaOH 50% [m 3 /year] OPEX 3.6 M 3.9 M -1.8 M -1.5 M 5.4 M

65 Fuel Prices, Rotterdam 65 Wärtsilä version 9.0 /Arnauld Filancia

66 Abacus with CAPEX ranging from 80 /kw to 550 /kw 20,0 19,0 18,0 17,0 16,0 15,0 14,0 13,0 12,0 11,0 10,0 9,0 8,0 7,0 6,0 5,0 4,0 3,0 2,0 1,0 0, ROI <1 year 440 < CAPEX < < CAPEX < < CAPEX < < CAPEX < Wärtsilä version 9.0 /Arnauld Filancia Schematic curves for a given number of running hours in SECA. In this case hours per year of MDO were converted in HFO. These curves move up and down in the graph as this number of RH reduces or increases.

67 67 Wärtsilä version 9.0 /Arnauld Filancia Conclusions

68 Wärtsilä s Marine Scrubber solution Scrubbing is the cheapest way to comply Fresh water scrubber is the only technology to: Make zero effluent discharge possible Be always in control of reduction efficiency Have the smallest energy consumption Have no creation of CO 2 caused by neutralization process Wärtsilä fresh water scrubber solutions are fit for new building and retrofit, for any engines and boilers brands. 68 Wärtsilä version 9.0 /Arnauld Filancia

69 Contribution to the environment Reducing emissions Quantity Freshwater scrubber (FWS): Requires 0,5 to 1% power Quality Scrubbers reduces SOx to 0,1% Effect on PMs... while limiting CO 2 emission Fuel spoil FWS reduces relative CO2 emission Scrubbers allow best use of barrel 69 Wärtsilä version 9.0 /Arnauld Filancia