Flammability Limits of a Premixed Gas with Steam Addition
Open Access
- Author:
- Kutzler, Patrick
- Graduate Program:
- Mechanical Engineering
- Degree:
- Master of Science
- Document Type:
- Master Thesis
- Date of Defense:
- April 18, 2008
- Committee Members:
- Kenneth K Kuo, Thesis Advisor/Co-Advisor
- Keywords:
- flammability limits
premixed gas
steam - Abstract:
- Many industrial processes utilized for synthesis gas production are carried out at elevated temperatures, and therefore knowledge of flammability boundaries is quite important for safety considerations. Any premixed gas combustion which results in a propagating flame or violent reaction is very unfavorable during the manufacturing process. Gaining a better understanding of flammability behavior will help ensure that pre-specified operating conditions at a pilot plant scale are safe and adequate. An existing high-pressure, high-temperature combustion chamber was modified and utilized for the determination of a flammability boundary as well as observation of flame-propagation processes and pressure responses of the premixed gaseous reactant mixture consisting of CH4, C2H6, and H2 (to simulate natural gas) combined with O2 and steam. Combustion was initiated by an electric match. The reactor was instrumented with photodetectors for flame-propagation speed measurement while multiple Setra and PCB transducers were used to record pressure-time traces. A pre-heater and a steam generator were used in combination to heat the gas mixture to temperatures near 170˚C. In this study, 29 tests were conducted and a V-shaped flammability boundary was determined as a function of initial chamber pressure and molar steam/carbon ratio for the premixed reactant flow. With steam addition at a steam-to-carbon ratio (S/C) near 0.020, the mixture was not flammable at any pressure tested (7.6 to 30.1 atm). It was also found that less steam was necessary to suppress combustion at lower pressures. Below 8.6 atm, any measureable steam addition (S/C > 0.003) was effective in preventing a propagating flame. For cases which resulted in sustained combustion, flame-propagation speed and pressure-time results were acquired, analyzed, and summarized.