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Publication > Issue > Articles

ASRL Review

Summary

Chemistry of the Claus Furnace: The Claus furnace has been an integral part of sulphur recovery since the early 1940s. Surely we must have a good idea of what goes on in the furnace? Maybe, maybe not, says Dr Peter Clark.

Abstract

Before launching into the chemistry, I must first acknowledge support and encouragement from Hans Borsboom of Jacobs Nederland BV. Hans has taken a keen interest in our work and carried out theoretical studies to support some of the more interesting observations of our experimental programme. Also, it would be remiss of me not to acknowledge the help and encouragement of Steve Graville, Jason Norman and Dick Watson at BOC Gases, Jacques Koenig, now retired from Air Liquide, Hal Gunardson of Air Products & Chemicals Inc., and Dave Sikorski and Nick Roussakis at HEC Technologies. Last, and not least, I must thank Norm Dowling and Minming Huang at ASRL; they have been responsible for carrying out all of the difficult work of dealing with H2S at over 1000°C.

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New style, less flare

Summary

New options for relatively small scale desulphurisation are helping gas processors to meet ever-tighter regulatory limits and keep their neighbours happy, at an affordable capital cost. Chris Cunningham took to Alberta's prairies to see two processes in action.

Abstract

Combine seemingly endless demand for Albertan gas with increasingly high concentrations of hydrogen sulphide, then mix in a stringent environmental regime backed by a population that is highly sensitive to the issues of gas flaring. The result is increasing pressure on Canadian gas processors to release as much as possible of the sulphur entering their plants in its elemental form rather than as sulphur dioxide from the flare stack.

There is no shortage of technical options to suit the economics of relatively large scale production of sulphur. But small scale production, perhaps as low as 1 t/d of sulphur or less, means that installation of a Claus unit or one of its variants may not be a feasible proposition.

However, a range of technologies for small scale desulphurisation is emerging and Sulphur recently took an opportunity to see two debutants going through their paces close to the town of Bantry in south east Alberta.

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Economics of oxygen enrichment

Summary

Following her article on equipment evaluation in the last issue of Sulphur, Mahin Rameshni, Chief Process Engineer at Parsons Energy & Chemicals Group of Parsons, turns her attention to the economics of oxygen enrichment when revamping using Double Combustion technology.

Abstract

Oxygen enrichment can be applied to both new and existing sulphur recovery units (SRUs). The economics are clearly favourable for the revamp of modified Claus SRUs if an increase in sulphur production is required. New plants, on the other hand, have been designed to use oxygen enrichment when a refiner sees a need for peak shaving operation or the need to increase the capacity of a unit on a short-term basis to allow for the maintenance of a second unit. New Claus plants using oxygen without air are normally associated with gasification projects or gas plants, both of which can have a lean relatively constant composition feed.

The minimum modifications required for a typical revamp are:

  • New burner
  • Revised control system
  • Revised shutdown systems
  • Oxygen storage (if not already available)
  • Oxygen transfer line

 

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Titania-based Claus catalyst performance

Summary

Use of titania catalysts can often be justified when higher sulphur recovery is required. Over the past couple of years new titania-based Claus catalysts have been introduced. Lisa Connock reports on the performance of two of these catalysts: S-7001 and DD-931.

Abstract

Conventional activated alumina Claus catalysts have high activity for converting H2S and SO2 to sulphur under most normal conditions. However, alumina has two serious limitations. The first is its limited ability to decompose COS and CS2; the second is the overall activity under severe sulphating conditions for even the H2S/SO2 reaction. In these two situations the use of titania catalyst is recognised as the better solution, because of its ability to give high conversion of all the sulphur species to elemental sulphur, even under conditions when alumina is deactivated from sulphation.

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