Application of Synthetic Diesel Fuels

Transcription

1 Application of Synthetic Diesel Fuels Future Fuels : Issues and Opportunties 11 th Diesel Engine Emissions Reduction Conference, Chicago, August 21-25, 25 Paul Schaberg, Sasol Technology

2 Presentation Outline Description of synthetic diesel fuel production processes Description of synthetic diesel fuel properties Overview of Sasol s current GTL and CTL plans Possible market introduction scenarios Combustion and exhaust emissions with GTL diesel fuel and blends Opportunities for engine optimisation Summary and concluding remarks

3 Generic xtl Process Syngas Production Fischer-Tropsch Synthesis Product Upgrading coal gas oil biomass light gas FTBO return light gas carbon source oxygen source steam reformer / gasifier syngas FT reactor condensate (< C2 ) wax (> C2 ) hydroprocessing distillation naphtha jet/kero diesel H 2 O wax FTBO feed heavy fraction

4 Diesel Fuel Properties Clear, odourless liquid Highly paraffinic (total aromatics < 1%, polycyclic aromatics <.5%) Density ~ 77 g/l H/C ratio ~ 2.1 mol/mol LHV ~ 43.8 MJ/kg Cetane number > 7 Very low sulphur (< 1ppm) Good thermal stability Distillation range determined by: Density at 2 C (g/l) Boiling Point ( C) Applicable specifications (T9, flash point, cold flow properties) 15 Jet / kerosene production 1 European maximum and minimum limits FBP constrained by T95 specification Flash point ~6 C ~55 C IBP constrained by flash point n-alkyl Cyclo Hexanes n-alkyl Benzenes n-paraffins Carbon Number Yield maximised with full boiling range diesel fuel n-paraffins T95 ~ 36 C CFPP ~ -2 C 2-Methyl-i-paraffins Carbon Number

5 Current GTL and CTL Plans USA Evaluating Opportunities Qatar Sasol / Qatar Petroleum 34 bpd (Oryx I) Under construction Iran Sasol Study on GTL opportunity progressing Qatar SasolChevron / Qatar Petroleum 65 bpd (Oryx II) - MOU 13 bpd - LOI China Sasol / Shenua / Ningxia 2 X 8 bpd Feasibility Stage Nigeria CNL / NNPC 34 bpd EPC contract awarded + Gas-to-Liquids Coal-to-Liquids South Africa Sasol I and II 16 bpd In operation Australia SasolChevron Study on GTL opportunity progressing

6 Oryx GTL, Qatar 34 bpd initial capacity, expansion to 1 bpd Startup end Q1 26 FT reactor Mass = 22 tons Height = 6m Diameter = 1m

7 GTL Diesel Relativity France 61, bpd Europe 3,5, bpd London bus fleet 1,75 bpd Global automotive diesel market 13,, bpd Italy 45, bpd UK 38, bpd Germany 54, bpd Oryx 23, bpd EGTL 23, bpd Worldscale GTL plant 1, bpd Current Sasol Chevron projects 25, bpd Total GTL projects under development 75, bpd

8 Some Application Scenarios Volume of synthetic fuel available Refinery blendstock -> premium diesel Refinery blendstock -> conventional diesel Refinery blendstock -> new premium diesel -> standard and optimised engines Neat fuel -> niche market application New applications -> HCCI, FC Neat fuel -> optimised engines Conforms to current specification Does not conform to current specification Time

9 Exhaust emissions with GTL diesel fuel, conventional engines Typically obtain reductions in all regulated emissions (HC, CO, NOx, PM) Reductions in CO 2 and other unregulated emissions NOx and PM critical: 13% avg. NOx reduction 26% avg. PM reduction PM Reduction (%) NOx Reduction (%) Heavy Duty Light Duty Source : NREL SAE Paper

10 Passenger Car Emission Tests Tests performed with a Mercedes E22 CDI (Euro 3) vehicle and engine Neat GTL diesel fuel and blends compared with sulphur-free EN59 diesel fuel All calibration parameters kept constant during steady-state tests Blends showed disproportionate reductions in soot / PM in both vehicle and engine tests Disparity in NOx response between vehicle test and engine tests : nonoptimal engine calibration for lower density, higher cetane fuels. Relative NOx (%) Relative Level (%) NEDC Vehicle emission tests EU Diesel 5:5 EU-GTL Diesel GTL Diesel HC CO NOx PM CO2 FC Steady-state engine bench tests EU Diesel 8:2 EU-GTL 5:5 EU-GTL GTL Diesel Operating Point

11 Injection System Performance Common-rail FIE Injection rates for the two fuels are similar at low loads Expected deviation due to density difference is evident at higher loads No negative effects on operation of FIE Besides lower density, lower viscosity of GTL diesel fuel could to be influencing parameter Injector Flowrate (g/s) Injector Flowrate (g/s) min -1, 2 bar bmep P rail = 57 bar Time (ms) 4 min -1, full load P rail = 156 bar Time (ms) GTL Diesel Fuel EN59 Diesel Fuel GTL Diesel Fuel EN59 Diesel Fuel

12 Injection System Performance Unit Injector FIE Injection rate for the GTL diesel fuel is lower than EN59 diesel fuel at low loads Deviation at higher loads is smaller No negative effects on operation of FIE Besides density, lower bulk modulus of GTL diesel fuel could be an influencing parameter Injector Flowrate (g/s) Injector Flowrate (g/s) min -1, 2 bar bmep EN59 Diesel GTL Diesel Fuel Time (ms) 4 min -1, full load EN59 Diesel Fuel GTL Diesel Fuel Time (ms)

13 Combustion Properties Combustion processes of GTL diesel fuel have been compared to EN59 diesel fuel, using both classical and advanced incylinder diagnostics As expected, differences in ignition properties and soot formation have been observed Difference in ignition delay is a non-linear function of cylinder pressure and temperature (load). Cylinder Pressure (bar) ROHR (kj/m 3.deg) min -1, 3.3 bar bmep EU Diesel GTL Diesel 5:5 EU-GTL 8:2 EU-GTL Crank Angle ( ATDC) 18 ATDC, 2 min -1, 7 bar bmep EU Diesel GTL Diesel

14 Opportunities for Optimisation 35% reduction in both soot and NOx through software optimisation Hardware optimisation (combustion system, FIE) is expected to compliment this further End result could be reduced requirement for exhaust gas aftertreatment, i.e. cost saving Relative Soot (%) PM (g/km) 5:5 EU- GTL Diesel Blend GTL Diesel 35% Potential Reduction in both NOx and Soot with GTL Diesel fuel 8:2 EU-GTL Diesel Blend EU Diesel Relative NOx (%) with DPF NOx (g/km) Software optimisation Hardware + software optimisation

15 Summary Dawn of the synthetic fuels age Synthetic fuels technology is enabling the production of clean, very high quality fuels from diverse feedstocks, including non-petroleum and renewable feedstocks Plans for a significant number of large scale GTL production plants have been announced, the first of which will start up in 26 Relative synthetic fuel volumes will be small for many years global impact will be small, but regional impact can be significant Developing an understanding of the combustion and emissions properties of synthetic diesel fuels in order to: Ensure problem-free operation in both neat and blended form Quantify the benefits Understand opportunities for engine optimisation Understand the opportunities for future combustion systems

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