A Theoretical Gas Quality Analysis of Natural Gas

A Theoretical Gas Quality Analysis of Natural Gas for Vehicles (NGV) in Thailand Yossapong Laoonual 1, 2, Sumrerng Jugjai 2, Somchai Chanchaona 2 1 College of Integrated Science and Technology, Rajamangala University of Technology Lanna, 2 Combustion and Engine Research Laboratory (CERL), Department of Mechanical Engineering, King Mongkut’s University of Technology Thonburi Nuwong Chollacoop and Subongkoj Topaiboul 3 3 Energy Research Technology Group, National Metal and Materials Technology Center (MTEC)

Outline • Introduction • Natural gas quality in Thailand • How to use the natural gas more efficient • Summary

Natural Gas Quality • Natural gas composition ØHydrocarbon ØInert gas ØSulfur • Natural gas properties ØWobbe index ØMethane number ØA/Fs

Typical Composition of Natural Gas • Methane CH 4 (70 -95%) • Rich gases C 2 H 6, C 3 H 8, C 4+ (0 -20%) • Inert gas N 2, CO 2, O 2 (0 -8%) • Sulfur H 2 S (0 -5%) • Rare gas He, Ne, Xe (trace)

Wobbe index (WI) WI quantifies the heat produced by the gas at a given time, after flowing through the fixed hole of gas injector. where WI = Wobbe index (J/m 3) H HV = high heating value (J/m 3) air = air density (kg/m 3) gas = gas density (kg/m 3) s = specific density

Methane Number (MN) Methane number is the parameter used to quantify knocking tendency of an internal combustion engine using gas as the fuel. MN = 1. 624×(MON)-119. 1 MON = -406. 14+508. 04(RHCR)-173. 55(RHCR)2+20. 17(RHCR)3

Composition/ Properties Natural gas standard SAE J 1616 (1994) CARB (1992) NZS 5442 (1999) CPUC Rule 30 (2002) CARB (Draft) CH 4 - 88% (max) - - - C 2 H 6 - 6% (max) - - - C 3 + - 3% (max) - - - C 4 + - - 1. 5% (max) C 6 + - 0. 2% (max) - - - CO 2 3% (max) 0. 1% (max) - 3% (max) - CO 2+N 2+O 2 - 1. 5 -4. 5 - 4% (max) Sulfur 8 -30 ppm 16 ppm (max) 50 mg/m 3 Wobbe Index (MJ/m 3) 48. 5 -52. 9 - 46 -52 ± 10% Not announce Methane number - - Min 80 (statewide) Min 73 (regional) Heating values - - - 36. 1 -42. 8 MJ/m 3 (max) - Specific density - - 0. 8 (max) - - 0. 75 grain/100 scf (max) 1 grain/100 scf (max)

Natural gas composition High N 2 => Nitric Oxide Formation N 2 N+ OH 2 N NO+O NO+H High CO 2 => Fe. CO 3 Corrosion in NG cylinder

Natural Gas Sources in Thailand North West South Northeast East

Composition CH 4 C 2 H 6 C 3 C 4 C 5 C 6+ N 2 CO 2 Sulfur Natural gas composition East (2006 -2009) West (2007) Khanom South Namphong Northeast Lankrabu North 74. 1 -77. 5% 72. 4% 62. 6 -69. 6% 95. 5% 84. 7 -85. 4% 5. 4 -6. 0% 1. 5 -2. 4% 0. 59 -0. 9% 0. 1 -0. 15% 0. 02 -0. 04% 2. 0 -2. 2% 12. 7 -14. 4% <16 ppm 3. 5% 1. 06% 0. 47% 0. 1% 0. 07% 16% 6. 2 -6. 4% 10 -19 ppm 8. 3 -9. 0% 0. 72 -5. 1% 0. 02 -0. 38% 0. 05 -0. 19% 0. 01 -0. 3% 0. 7 -0. 76% 20. 3 -21. 9% <16 ppm 0. 6% 0. 07% 0. 06% 0. 02% 1. 8% 2. 0% <500 ppm 11. 2 -11. 4% 1. 34 -1. 81% 0. 24 -0. 48% 0. 07 -0. 14% 0. 03 -0. 065% 0. 5 -0. 6% 1% -

Properties Natural gas properties East (2006 -2009) West (2007) Khanom South Namphong Northeast Lankrabu North High heating value 35. 75 -38. 96 (MJ/m 3)* 33. 23 31. 59 -40. 52 38. 64 43. 39 -44. 77 Wobbe Index (MJ/m 3)* 42. 18 -43. 73 39. 1 -39. 2 34. 6 -42. 14 50. 44 54. 5 -55. 2 Methane Number 76 -81 86 64 -80 105 75 -78 A/Fs 11. 8 -11. 95 11. 1 10. 0 -10. 6 15. 8 16. 4 *Calculated from DIN 51857 -1997

Wobbe index in Thailand

Wobbe Index around the world

Natural gas variation compared to east Components & Gas quality Variation (other sources-east)/east East West Khanom Nam Phong Lankrabu (2007) (2007) CH 4 -4% -13% 26% 12% C 2 H 6 -39% 52% -89% 98% CO 2 -54% 56% -85% -93% N 2 662% -65% -14% -74% Wobbe Index -9% 17% 28% Methane Number 9% -8% 34% -3% A/FS -7% -14% 33% 38%

How to use the natural gas more efficient Two ways to propose solutions • Suitable gas quality ØImprove gas quality e. g. install gas separation plant ØIssuing Thai natural gas standard • Suitable engine technology ØAdaptive electronic control unit (ECU) with wideband oxygen sensor ØWobbe index sensor or gas composition sensor

Summary • Significant gas quality variation in Thailand. • Required gas quality standard in Thailand. • Required qualitative engine performance and emission test from various gas sources. • Required proper engine technology.

Thank you & Any Questions ?