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Tag: Refinery

Start-up, shutdown and turndown

With the ongoing changes in gas field and refinery feedstock compositions, many sulphur recovery units around the world are facing turndown scenarios to such an extent that it is difficult to meet stringent environmental regulations. Equipment and instrumentation behave differently under turndown conditions, and not always in ways that are desirable. Start-ups and shutdowns can place demands on the equipment that are more severe than years of normal operation. In this article, Optimized Gas Treating, Sulfur Recovery Engineering and Comprimo share some of their learnings and experiences of these scenarios.

Improve asset integrity by predicting corrosion

Using case studies of a refinery amine unit and a sour water stripper (SWS), U. M. Sridhar of Three Ten Initiative Technologies LLP, N. A. Hatcher and R. H. Weiland of Optimized Gas Treating Inc. demonstrate the capabilities of a mechanistic, chemistry-based, truly predictive model for calculating corrosion rates for various amines and for sour water. At a time when asset integrity is much sought after, the utility of this fully predictive model is to prevent failures before they occur, rationally select materials of construction, enhance plant safety, and mitigate risk.

Hydrocarbon removal from sour water systems

Hydrocarbon contamination of sour water streams feeding sour water strippers is a well-known challenge in the refining and gas processing industry. The source of this challenge is the formation of a stable oil emulsion in an aqueous phase that may contain both H 2 S and NH 3 . The typical approach to the problem involves large residence time tanks with the assumption that droplet settling will occur over a long enough time frame. In practice, droplet settling is very slow due to a variety of reasons, and as a result, operators encounter sour water heat exchanger fouling, stripper fouling, hydrocarbon excursions to sulphur recovery units along with other operating challenges. M. Thundyil, D. Seeger and E. McIntosh of Transcend Solutions present a case study of the TORSEP™ oil and solids removal system for contamination removal from a sour water feed stream. The case study illustrates the effect on heat exchanger fouling along with the effect of the variation of several system parameters on operating performance and economics.