PR-616-17607-R01 Sulfur Condensation in Pressure Reduction Equipment

Abstract

In natural gas transmission pipelines systems, there is a growing awareness of contamination due to the presence of sulfur vapor in the gas stream at sub ppm levels. Particularly at pressure reduction facilities, the sulfur vapor can desublimate out as solid elemental sulfur and then combine with other particle matter and trace liquids in the gas stream to form the observed contamination deposits. In order to better control the formation of the elemental sulfur, an improved understanding of the contribution that the design of pressure regulators make to this desublimation process is required. This research program has come to the challenge of this requirement. In the conducted program, two pressure regulators were tested at a common facility that was known to have an elemental sulfur deposition problem. Each pressure regulator was alternatively placed in service so as each was subjected to, as near as possible, identical operating conditions. A requirement for the selection of the two pressure regulators was that they had to have different internal design features. The quality of the natural gas supply was regularly sampled and analyzed, with the contamination deposits on the pressure regulator internals sampled and analyzed at the termination of the test period. These deposits were analyzed for both hydrocarbon and other liquid deposits as well as a range of metal and semi-metal compounds captured in the deposits.