Thirty years of operating experience with the Clauspol process

The Clauspol process, developed by IFP over thirty years ago, is a Claus Ta il Gas Treatment (TGT) process. Because of its simplicity, ease of operatio n and low cost, the process has gained more than 40 industrial references w orldwide, making it one of the most widespread TGT processes. From the begi nning, the process operability and technology have been continuously improv ed to the point where the latest version, Clauspol Booster 99.9+, enables c ombined Claus-Clauspol sulfur recoveries exceeding 99.9% to be achieved. In arriving at the current performance levels, the following operational issu es concerning industrial Clauspol plants were resolved: corrosion encountered in some of the first Clauspol plants is now well unde rstood and is avoided by applying simple rules in the unit's design, constr uction and operation; the catalyst stability has been improved by both lowering the temperature o f the solvent, replacing direct injection of water by a heat exchanger, cha nging the initial catalyst formulation and improving control of H2S/SO2 in the Claus tail gas; sulfur quality is assured by eliminating oxygen in the Clauspol feed via in stallation of an oxygen-scavenging catalyst layer in the first Claus conver ter, with particular attention to the sulfur boot design, by a regular cont rol of the liquid level in the bottom of the reactor and also by ensuring g ood control of H2S/SO2 ratio; with experience, the procedure of water-washing of the reactor every two to four years has become much simpler. Furthermore, new R&D results show that accumulations of solids in the reactor could be prevented, eliminating the need for periodic shutdowns and reducing the size of the reactor. The above issues are discussed in this article.