Evaluate the burner system of an existing silane fume incineration system at a semiconductor related products specialty chemicals plant to ensure that it could operate as designed when firing the new fuel gas stream.
The client has an existing silane fume incineration system designed many years ago for the thermal destruction of several silane and disilane containing waste gas streams. The fume incineration system includes a burner system that fires into a combustion chamber where the waste gas streams are added, and a dilution chamber that cools the combustion gas before it enters a baghouse based gas cleaning system.
The burner is currently fired with an auxiliary fuel gas with a composition similar to natural gas. Over the years, the character of the waste vent streams being fired in the burner has changed. The client now desires to incorporate the ability to fire a new auxiliary fuel gas that is richer in C2 and C3 compounds than the current auxiliary fuel gas. Process Engineering Associates, LLC (PROCESS) was contracted to evaluate the burner system to ensure that it could operate as designed when firing the new fuel gas stream.
For this project, PROCESS developed a number of Heat and Mass Balance (HMB) cases in order to evaluate the impact of the new fuel gas composition on the incineration system. The intent of the calculations was to:
- Compare the new fuel gas and the original fuel gas firing the original waste gas streams and the current waste gas streams
- Evaluate the performance and impact of firing the new fuel gas and current waste gas streams relative to thermal efficiency and waste gas destruction.
Based on the HMB results, it was concluded that the client should have no issues switching to the new auxiliary fuel, nor should any modifications to the burner be required. This conclusion assumes that the actual primary and secondary air flows, the original auxiliary fuel flows and vent flows, and the auxiliary fuel and vent compositions are consistent with those provided in the process design basis.
The new auxiliary fuel will yield overall over 30 percent more heat per volume flow than the current auxiliary fuel. Thus, the new auxiliary fuel will result in a higher air requirement and higher burner and combustion chamber offgas temperatures for the same air input rates relative to the current auxiliary fuel. In general, higher combustion chamber offgas temperatures are concluded to be beneficial for complete combustion of the silanes as long as there is enough air available.
Semiconductor Materials Chemical Manufacturing
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