(115b) Effect of Siloxane Present in Renewable Natural Gas On the Operation of Various Natural Gas Equipment

N.
N. Nair^a, J. Gutierrez^c, J. Chen^c, A. Divsalar^a,
A. Vas^a, T. Zhao^a, M. Lew^c,
F. N. Egolfopoulos^b, T. T. Tsotsis^a

^aDepartment of Chemical Engineering and
Materials Science, University of Southern California, CA 90089, USA

^bDepartment
of Aerospace and Mechanical Engineering, University of Southern California, CA
90089, USA

^c Engineering Analysis Center, ML SC723B, Southern
California Gas Company

Abstract

The goal of this project is to systematically
investigate, under well-controlled laboratory conditions, the operation of different
appliances when using simulated renewable natural gas (RNG), particularly as it
relates to the impact of siloxanes a key impurity found in such fuels. Two
different devices were investigated, namely a small electric generator
operating on RNG, and a typical household furnace. Both appliances have been
operated for extended periods of time when using siloxane-containing RNG and
their operation has been compared with similar appliances operating on
conventional natural gas. The impact of the siloxane combustion (which results
in solid components that tend to deposit and coat various surfaces) has been
investigated in greater detail. It has been shown that the presence of
siloxanes has a very detrimental impact on the life of the various sensors that
are utilized to control the operation of such devices. The same is true with the
impact on the operating life of catalyst beds which are connected to the
devices in order to reduce the pollutants emitted. In addition to coating the
various internal surfaces, silica microparticulates resulting from siloxane
combustion find their way into the condensate (in the case of the furnace) and
the spent oil (in the case of the engine). Studies are ongoing to identify the
complete failure mode of these devices and the results will be presented at the
meeting.

Keywords: Siloxanes, biomethane, biogas, renewable natural gas, SiO₂
particles

ACKNOWLEDGMENT:

The support of the support of the Southern
California Gas Company is gratefully acknowledged, as are many helpful
discussions with Dr. Siari Sosa, Mr. Scott Kysar, and Mr. Gilbert Ching