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Summary
In the first part of this article, M. Rameshni of Rameshni & Associates Technology & Engineering LLC (RATE) discusses thermal combustion design criteria for the Claus reaction furnace including: refractory, the SRU burner, reaction furnace, waste heat boiler and steam drum. In the second part of this article, P.D. Clark et al of Alberta Sulphur Research Ltd (ASRL) introduce a new concept for the destruction of BTX in the Claus furnace in which the conventional thermal reaction furnace is replaced by a catalytic combustion chamber.Abstract
Refractory design
In a conventional modified Claus sulphur plant, hydrogen sulphide-rich gases are processed through the reaction furnace (combustion chamber) followed by the waste heat boiler.
Temperatures in a Claus unit can reach up to 1,538°C when air is used in the process and up to 2,760°C when oxygen is used. A refractory lining insulates the walls of the unit from the high temperature inside of the unit for operation with air. Such refractory linings are undesirable because of the time and expense required to install the lining, the time required to heat the lining during start-up of the unit, the time required to cool the lining during shutdown of the unit, and the expense and lost on-stream time and sulphur production caused by damage to or failure of the lining, which requires that the unit be shut down for repairs.
Summary
Process technology and catalyst suppliers to the sulphuric acid industry are constantly looking at new processes and improved equipment and catalysts to address the needs of the sulphuric acid industry. With regard to the environment, how to further reduce SO2 emissions is constantly under the spotlight. In this article, Topsøe discusses the improvements that have been made by the introduction of new catalysts and its new WSA-DC (wet gas sulphuric acid double condensation) technology, introduced in 2011, and MECS reports on the development of a new regenerative SO2 process designed to reduce emissions, reduce energy consumption and lower capital investment.Abstract
Haldor Topsøe
Topsøe’s contribution to reduction of SO2 emissions from sulphuric acid plants is two-fold in the sense that Topsøe supplies both process technology and catalysts. The Topsøe sulphuric acid catalysts are supplied both to conventional dry gas plants and to Topsøe’s proprietary WSA and WSA-DC wet gas sulphuric acid technologies.
Sulphuric acid catalysts
In recent years, more stringent environmental regulations have made it necessary for sulphuric acid producers and other industrial plants to reduce SO2 emissions. One way Topsøe has responded to this challenge is by introducing new advanced types of catalyst to meet the new requirements.
Summary
Will the gasification of coal and other heavy feedstocks become a larger-scale source of Claus sulphur in future?Abstract
While most elemental sulphur is extracted from oil and gas, coal’s share of primary energy production is roughly equivalent to the other two fossil fuels. However, the sulphur contained within coal is usually recovered downstream of combustion, as a product of flue gas desulphurisation (FGD), and it forms either gypsum or ammonium sulphate, never passing into the sulphur industry. However, cost and environmental concerns have driven an increasing interest in gasifying coal to produce both power and chemicals, which would necessitate removal of sulphur from a gaseous (syngas) feed prior to chemical or power production. Coal was the main feedstock for the world’s chemical industry until 50 years ago, and during the period of high oil and gas prices a few years ago there were suggestions that coal-rich countries like China, India and the US could see themselves returning to those days.
The main routes from coal to chemicals can thus be summarised as follows:
l To ammonia, and then fertilisers (urea, ammonium nitrate, etc.)
l To methanol, and then: methanol-to-olefins (MTO), producing ethylene, propylene and some higher olefins, or methanol to gasoline (MTG), or otherwise into downstream methanol-derived products such as acetic acid, formaldehyde and diethyl ether (DME).
l To liquid fuels via Fischer-Tropsch (coal to liquids – CTL).
Summary
The siting of new refinery projects shows that there is a continuing drift in capacity towards non-OECD production. As well as the Middle East, there is now a new focus on developing Asia, especially China, and also South America. Although the period following the 2008 crash saw some capacity postponed, there are now several million barrels per day of new refining capacity due to come on-stream in the medium term future.Abstract
Around the world there are around 650 refineries with a combined processing capacity of 85 million bbl/d. However, the global refining industry is in a period of major restructuring, as the nature and location of oil and refined product demand shifts. Demand in OECD countries has peaked and appears to be in long-term decline, while demand in non-OECD countries continues to increase rapidly. The upshot of this is that there is a growing refinery surplus in Europe, North America and the Pacific OECD countries (basically Japan, South Korea, Australia and New Zealand), and a rapidly growing deficit in places such as China, India and Brazil.
The 2008 economic crash and the period that followed it saw a contraction in demand around the world of around 2 million bbl/day, but new capacity which had been started before the downturn continued to come on-stream. During 2008-09, around 1.5 million bbl/d of capacity was added at new refineries, while capacity expansions at existing sites, in China, Europe and the US, added another 1.1 million bbl/d. Non-refinery supply, biofuels, gas to liquids etc, added another 0.8 million bbl/d, leading to a total imbalance of 5.4 million bbl/d during that period.
Summary
P.D. Clark, Department of Chemistry, University of Calgary and Alberta Sulphur Research Ltd (ASRL), together with A. Primak, P. Alegre and H. Wan of ASRL discuss the strategic importance of sulphur in industry and agriculture, and methods for storage of excess production.Abstract
For much of the past 50 years, sulphur has been produced in excess of demand. This, under free market economics, has meant that its manufacturers have sold it at a discount, so subsidising industries that use the commodity. By 1990 it had become clear that sulphur produced on purpose, essentially that recovered by the Frasch process, would not needed to the same extent in the future, as sour oil and gas was likely to produce enough to satiate world appetites. Today, Poland is the only country producing sulphur via the Frasch method, but the 500,000 t/a produced in 2010 was insignificant compared to the 50 million t/a recovered that year from hydrocarbon processing.
Sulphur is a strategic commodity as it is linked to food supply. Via sulphuric acid, sulphur is used to produce soluble phosphate fertilizer, a vital component in high intensity agriculture. Because the hydrocarbon industry has been selling sulphur at highly discounted prices since 1980, it has, essentially, subsidised world food production. Indeed, the so-called ‘Green Revolution’ realised by the agriculturist Norman E. Borlaug and others, which eliminated hunger for billions of people, would not have been possible without fertilizers.
Summary
Sulphur Experts ran a one-day pre-conference course on Tail Gas Treating for Sulphur Recovery at Sulphur 2011 in Houston, Texas. More than 35 participants from around the globe gathered to increase their knowledge about Claus tail gas treating processes, comparing technologies, overall sulphur recovery efficiencies, economics and best practices to get the best performance from tail gas treating plants, based on Sulphur Experts' extensive knowledge and experience of troubleshooting and plant optimisation.Abstract
The Sulphur Experts course on Tail Gas Treating for Sulphur Recovery was held on 7 November, 2011 in the run up to the Sulphur 2011 Conference in Houston. John Sames, President of Sulphur Experts gave an overview of tail gas treating in the introduction before handing over to the main speakers: Jamie Swallow, Bruce Klint, Mike Cundall and Ben Spooner. The course covered selective oxidation processes, sub-dewpoint processes, amine-based H2S removal processes, oxidation and SO2 removal processes. In addition, there was a session on SO2 removal versus CO2 emissions and how the different process technologies compare. Table 1 compares the economics and sulphur recovery efficiency capabilities of different TGT processes.
Claus impact on TGU operations
Sulphur Experts stressed that in order to maximse the benefits of the TGU it is important to first optimise the Claus plant performance. The Claus plant should achieve high Claus conversions and overall recovery.
Summary
The Sulphur Institute (TSI) continues to examine Sulphur – an advantaged element®. This is the fourth part in a series taking a look at sulphur, its evolution, role in history and future focus. In this issue, we discuss the integral role sulphur plays in an array of industries, from ore leaching to textiles and more. Tom Dunn, TSI's director of industrial programs, continues the series.Abstract
In the first two issues of this series, TSI shared with its international audiences a background of the element which demonstrated the role sulphur has played in human history, as well as how Frasch sulphur mining yielded to the Claus method of oil and gas sulphur recovery. In the previous issue we discussed its necessary function in phosphate fertilizer production and its growing role as a fertilizer for crops. Let’s continue with a closer look at why TSI is promoting Sulphur – an advantaged element®. This instalment provides an overview of how sulphur is used across an array of industries in the world today: from ore leaching, textiles, and the pulp and paper industry, among others.
Summary
Sulphur's annual survey of recent, current and future sulphur recovery unit construction projects maps the developing shape of brimstone production from fuel and gas processing plants worldwide.Abstract