Optimisation of the system fuel, engine hardware and engine calibration for lowest emissions using the example of GTL

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Shell Global Solutions (Deutschland) GmbH 2013 1

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Optimisation of the system fuel, engine hardware and engine

calibration for lowest emissions using the example of GTL

1^st international conference on

Tailor-made Fuels from Biomass

June 20^th 2013, Aachen

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Copyright of Shell Global Solutions (Deutschland) GmbH June 2013 2

Table of content

Introduction

GTL production and GTL properties

Impact on combustion / Methodology of optimisation

Example results

Summary

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Synthetic fuels offer specific properties which allow optimisation for lowest emissions and high

efficiency

Special production process of synthetic fuels allow alternative (bio-) fuels to be produced in a narrow range of properties

This offers the chance to optimise the engine design in terms of calibration and hardware for specific fuel parameters leading to minimised emissions and/or improved fuel economy

Optimisation helps to get a maximum out of the fuel

Using the example of GTL, the potential of a system optimisation

will be shown

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Table of content

Introduction

GTL production and GTL properties

Impact on combustion / Methodology of optimisation

Example results

Summary/Outlook

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GTL production is running on an industrial scale

Air separation

Heavy Paraffin Synthesi s

Hydrocracking

Water Syngas

manufactur e

CO+H₂ -(CH₂)_n- Natural gas

Fuels

Base Oil Feedstoc k

Chemical s

O

₂

1993: ~300 000 t/a (Shell, Malaysia)

2007: ~1 200 000 t/a (QP/SASOL, Qatar)

2012: ~ 1 200 000 t/a (SASOL, Nigeria)

2012: ~ 3 000 000 t/a (QP/Shell, Qatar)

Shell GTL Plant, Qatar

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SHELL GTL Fuel

More than 30 years experience in GTL development

6

Labor Amsterdam Gramm/t

Pilotanlage Amsterdam 3 bbl/d

Bintulu/Malaysia 14,700 bbl/d

Pearl GTL/Qatar 140,000 bbl/d

1973 1983 1993 HEUTE

FORTSCHREITENDE TECHNISCHE ENTWICKLUNG

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Properties of GTL are unique but allow drop-in use

Virtually free of sulphur and aromatics Very high cetane number

Property Unit Limits GTL Limits EN590

min max min max

Cetane number 70,0 - 51,0 -

Density at 15 °C kg/m³ 770,0 800,0 820,0 845,0

Total aromatics %(m/m) - 1,0

content

Polycyclic aromatic %(m/m) - 0,1 - 8,0

hydrocarbons content

Total olefin content %(m/m) - 0,1

Sulfur content mg/kg - 5,0 - 10,0

Flash point °C >55 - >55 -

Copper strip corrosion Rating (3h at 50°C) class 1 class 1 class 1 class 1

Oxidation stability g/m³ - 25 - 25

Lubricity, corrected wear scar diameter (wsd 1,4) at 60°C

μm - 460 - 460

Viscosity at 40°C mm²/s 2,00 4,50 2,0 4,5

Distillation 95% (V/V) °C 360 360

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Fuel properties

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Property Units EN 590

Diesel

GTL Fuel

Density (15°C) kg/m³ 830 785

Viscosity (40°C) mm²/s 2.9 3 Cetane Number

CFR

- 56 >75

IBP °C 170 210

FBP °C 360 350

Sulphur mg/kg <10 0

Hydrogen content %w 13.6 15

Carbon content %w 86.3 85

Calorific value MJ/kg 42.9 44

MJ/l 35.6 34.1

FAME content Vol.% 0 0

Fuel properties of EN 590 Diesel und GTL fuel used for light duty optimisation study

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Table of content

Introduction

GTL production and GTL properties

Impact on combustion / Methodology of optimisation

Example results

Summary/Outlook

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Specific GTL properties reduce emissions instantaneously

Virtually free of sulphur and

poly-aromatic hydrocarbons - leading to lower particulate emissions

High cetane number reduces ignition delay and pre-mixed combustion phase

Various tests have shown emissions reduction potential over a wide range of different Diesel engines

Average local emission reduction (in %) vs. EN 590 diesel

PM/Soot NOx HC CO

EURO I 18 16 13 22

EURO II 18 15 23 5

EURO III 10 - 34 5 - 19 < 9 16

EURO IV 31 - 38 5 - 16 10 - 28 0 - 9

EURO V 23 - 33 5 - 37 19 - 23 8 - 22

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Heat release rate in light duty common rail engine

Ignition delay of the pilot injection is reduced by high cetane number

Smaller impact on ignition delay of main combustion at higher

loads

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Heat release rate in marine engine with inline pump

Response to GTL depends on injection system

Heat release rate and therefore temperature profile is impacted by GTL

Marine Gas Oil

GTL

1400rpm, full load, research engine

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GTL improves Soot-NO

_x

trade off instantaneously

Typically instantaneous relaxation of the Soot – NO

_x

trade off More freedom in calibration “space”

Enables further optimisation for lowest NO

_x

emissions or lowest

fuel economy e.g.

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Optimisation of calibration - EGR variation

Different optimisation strategies possible, e.g.:



Lowest NO

_x

(A)



Lowest fuel consumption (B)



Lowest fuel consumption and noise (C)

Possible optimisation parameters



Injection timing and pressure, pilot and main



Boost pressure, air flow



Swirl flap position

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Table of content

Introduction

GTL production and GTL properties

Impact on combustion / Methodology of optimisation

Example results



Passenger car



Heavy Duty engine

Summary/Outlook

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NEDC emissions for GTL as drop-in fuel

Significant emissions improvements even with Diesel calibration

Higher fuel consumption corresponds to the lower volumetric heating value indicating the same engine efficiency

Small CO

₂

benefit from GTL’s beneficial H/C ratio (on ‘tank to wheel’

basis)

NEDC Results

Diesel Base Calibration GTL Fuel Base Calibration

particulates measured w/o DPF

particulates [g/km]

EURO 5 limits EURO 6 limits

CO [g/km]

HC: -47%

-61%

NOx[g/km]

HC + NO x[g/km]

NOx [g/km]

-37%

fuel consumption [l/100 km]

4.8%

CO 2 [g/km]

Vehicle: Audi A4 2.7 tdi

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NEDC emissions with GTL optimised calibration

NO

_x

emissions can be reduced by 52% (calibration strategy A)

When optimized for minimum fuel consumption a 10% benefit for CO

₂

emissions was achieved (strategy B) while simultaneously reducing NO

_x

, particulates and HC

NEDC Results

Diesel Base Calibration GTL Fuel Base Calibration GTL Fuel Calibration A GTL Fuel Calibration B GTL Fuel Calibration C

particulates [g/km]

CO [g/km]

NOx [g/km]

-52%

-30%

-24 %

NOx [g/km]

HC + NO x[g/km]

NOx [g/km]

-61%

3%

CO 2 [g/km]

-10%

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Modification of the engine hardware for GTL

Reduced compression ratio by 10%



Usually leads to deterioration of HC/CO emissions

 Less critical with GTL fuel due to lower initial HC/CO emissions

Reduced nozzle hole diameter (25% reduction of hydraulic flow rate - HFR)

 Due to significant reduction of particulates with GTL fuel higher potential for HFR reduction

BSFC [g/kWh]

~50%

baseline engine

reduced compression ratio

reduced compression ratio + reduced HFR

NOx-Emission [g/kWh]

Black Smoke [FSN]

~35%

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NEDC results with modified hardware for GTL

Possible to stay below the EU-5 target by calibration changes alone

With the additional hardware measures the EU-6 NO

_x

limits are approached Steep gradients indicate full potential has been identified for this engine

NEDC Results Baseline engine

Diesel Base Calibration GTL Fuel Base Calibration GTL Fuel Calibration A GTL Fuel Calibration B GTL Fuel Calibration C Dedicated hardware

GTL Fuel Calibration A

particulates [g/km]

CO [g/km]

NOx [g/km]

HC + NO x[g/km]

NOx [g/km]

-52%

-66%

CO 2 [g/km]

-4.4%

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Example: Heavy Duty Engine without EGR

EU-IV/V engine without EGR

Even without EGR system - optimisation is possible



Injection timing



Injection pressure



Boost pressure

Benefits and optimisation potential depend on cycle

Fuel efficiency was kept constant

6 8 10 12 14 16 18 20

drop-in optimised

reduction in %

Vocational cycle

NOx % CO % PM %

6 8 10 12 14 16 18 20 22 24 26

drop-in optimised

reduction in %

ETC cycle

NOx % CO % PM %

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Summary

Shell GTL fuel is commercially available for heavy duty vehicles in captive fleets and other special applications

Specific properties of GTL lead to immediate emissions benefit when used in conventional Diesel engines

A dedicated calibration for GTL reduces the emissions even further Full potential of GTL fuel is enabled by optimised engine hardware and ECU calibration

Reduced engine out emissions might allow a simplified exhaust

after-treatment system to be used or could reduce the UREA

consumption of SCR exhaust after-treatment system

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Acknowledgement

I. Mahlke, D. Liebig, R. Wardle, A. Kolbeck

M. Kind, M. Lamping

R. v. Doorn

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SHELL GTL Fuel – worldwide experience

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London Toyota trial

China

Michelin Bibendum Challenge

Japan Fleet trial

Japan

Aichi hybrid buy

China

Bus trial Shanghai China

Shanghai Taxi Dubai airport

Bus and truck trial

Germany Fleet trial with Volkswagen London

Bus trial USA

Dept. of Transport Yosemite Water

Netherlands

Bus trial Connexxion Field test van

Gansewinkel Germany

Bus trial ESWE

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SHELL GTL Fuel

Die Forschung nach Alternativen findet keinen Königsweg!

25

2010 Status Quo

2025

Einfaches Mosaik

2050

Komplettes Mosaik

Wasserstoff

Biokraftstoff

Elektrizität

Erdgas

90erAnfang 2000erHeuteBald? Die “wahre” Antwort

Versorgungs- sicherheit

Emissionen

Kosten