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Safe handling of sulphur

Summary

Although sulphur is relatively inert and non-toxic in its solid form, it is flammable, and sulphur dust also presents a serious explosion hazard. Sulphur looks at hazards and mitigation strategies for safe handling of both solid and liquid sulphur.

Abstract

Safety is a major concern for those handling sulphur in both its solid and liquid forms. It is therefore necessary, at every stage in the sulphur handling process, to look at how different elements can be protected to ensure safe handling.
Depending on the crystalline form, solid sulphur’s melting point is between 112°C and 121°C. Sulphur is flammable in both its solid and liquid states. The ignition temperature in liquid form is between 261-268C, and for the solid form 190°C in dust clouds and 221°C in dust layers. The flash point is between 168 and 188°C. The explosive limits of the dust in air are also extremely important. The lower explosion limit (LEL) is approximately 35g/m3, and the upper explosion limit (UEL) is up to 1400g/m3.

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Sulphur in agriculture

Summary

On 16th June, in the latest in a series of webinars organised by jointly by The Sulphur Institute (TSI) and BCInsight, TSI's Don Messick examined sulphur's role in agriculture and asked participants to 'take a fresh look'.

Abstract

What is the first thing that comes to mind when you mention the word ‘sulphur’? A bad smell? Don Messick argued that sulphur has something of an identity problem, based around popular perceptions of hydrogen sulphide and the smell of matches and fireworks, not to mention sulphur dioxide and its association with acid rain and lung troubles. In fact, he argued, its many beneficial qualities are frequently overlooked, even though it is present all over the world we live in; the smell grapefruit juice, for example, is generated by volatile sulphur compounds. Indeed in earlier times it was used in treatments for many common ailments like scabies, ringworm, psoriasis, eczema and acne.
Indeed, sulphur is a key component of living creatures, both plants and animals, and is a constituent of a number of essential organic molecules like cysteine, methionine, coenzyme A, and iron-sulphur clusters. These compounds are involved in a number of essential cellular processes such as protein biosynthesis or the transfer of electrons and acyl groups.

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URS a leader in sour gas and sulphur technology

Summary

Johnny Johnson, URS VP of Technology & Development, showcases some of URS' key achievements in the sulphur sector.

Abstract

URS has built its significant position in the sulphur industry by providing one-of-a-kind technology and solutions to some of the world’s largest oil and gas companies for more than fifty years. Our core team of five Technology Directors responsible for sour gas processing and sulphur handling and recovery has a combined total of nearly 200 years of experience in the energy sector. This team is renowned for developing solutions to solve our clients’ most unique design and construction challenges for world-class facilities.
“We are proud of the fact that URS is sought out by Fortune 500 clients because of our reputation to resolve unique challenges in oil and gas production, sour gas treating and processing, and sulphur recovery and handling,” said Johnny Johnson, URS vice president of technology and development. “The more difficult a project, the higher value URS can offer.”

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Technology selection for gas processing units

Summary

Natural gas coming from the well contains hydrocarbons, CO2, H2S, and water together with many other impurities. Treatment of the gas is required to make it suitable for the various applications. A variety of gas processing systems are available to provide products that comply with specifications defined by the plant owner. This variety places a huge burden and challenges on owners to select the right technologies for the project circumstances to fulfill an optimised scheme meeting technological and economical targets. Given the magnitude of the investment in a gas-processing plant, it is appropriate to carry out a rigorous treating process selection study to identify the most cost effective and fit for purpose treatment package that removes contaminants in an environmentally friendly way. In this article, Saied Mokhatab, Process Technology Consultant, and Peter Meyer of CECA SA describe the most commonly used process technologies for designing the gas processing units and show how integration of process technologies and expert process knowhow make a difference.

Abstract

A typical scheme for most gas processing plants designed to produce pipeline gas from a sour gas feed is shown in Fig. 1. Field production, upon arrival at the processing plant, is processed in a slug catcher, which catches liquid slugs and then allows them to flow into downstream equipment and facilities at a rate at which the liquid can be properly handled. Produced gas from the outlet of the slug catcher is directed to a high-pressure (HP) separator, where final separation of liquid from gas takes place. The HP raw gas flows through to the gas sweetening unit (GSU), in which acidic components like H2S and CO2 are removed by means of chemical solvents. Simultaneous carbonyl sulphide (COS) removal in the GSU is also desired as it facilitates the downstream processing and purification steps and contributes to the reduction of the total sulphur content of the treated gas. The enriched acid gas from the GSU is processed to produce elemental sulphur in a sulphur recovery unit (SRU), consisting of a Claus unit and an associated tail gas treating unit (TGTU) if higher recovery rates are specified for the SRU itself. The final residual gas from the TGTU is incinerated.

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Mercaptans removal in molecular sieves

Summary

Molecular sieves can be used in a temperature-swing adsorption process downstream of an amine or physical solvent to remove traces of mercaptans. The design and operation of the mol sieve unit involves a number of challenges due to possible BTX co-adsorption and potentially fast deactivation of the sieves. In addition, the transient nature of the temperature-swing adsorption process introduces challenges in the design of the sulphur recovery unit (SRU) and the regeneration-gas treating for the mol sieve unit. Deactivation can be mitigated using a novel regeneration process, while transients in the regeneration gas can be smoothed using a peak-shaving scheme. BTX, COS and hydrocarbons may co-adsorb on the sieves and even be in competition with the mercaptans to be adsorbed. In sizing of mol sieve units for mercaptan removal these factors need to be taken into account. Future developments in the design of gas treating units for total sulphur species removal will aim at removing all sulphur species to such a low level that treatment of the individual products downstream of the NGL extraction unit is no longer required. In this article, C.J. Smit, A.F. Carlsson and T. Last of Shell Global Solutions International B.V. discuss the design and operational issues associated with mercaptan removal in a molecular sieve unit.

Abstract

Growing demand for natural gas is leading to an increase in the exploitation of contaminated natural gas fields. Significant reserves of natural gas in the Middle East and Central Asia containing H2S, CO2, COS, and mercaptans (RSH) are being developed to meet the growing demand. Although a wide range of gas compositions are possible, a typical composition may contain: 1-4 mol-% H2S, 1-4 mol-% CO2, 10-50 ppmv COS, and 50-400 ppmv RSH. To treat these contaminated gases to user specifications more complicated treatment schemes are required.
While the removal of acid-gas components such as H2S and CO2 from natural gas have been well established for decades, the removal of mercaptans and COS from natural gas in combination with H2S and CO2 are not as well established. A number of different gas processing options are possible, and different approaches have been used in various locations depending on the source, destination, and composition of the gas.

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