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Upgrading acid gas streams

Summary

Using the ProTreat™ amine simulator, T. K. Khanmamedov of TKK Company and R. H. Weiland of Optimized Gas Treating, Inc. analyse how Highsulf™ can produce a Claus plant feedstock of excellent quality from sour gas streams such as sulphur plant tail gas and raw gases that would otherwise present disposal problems.

Abstract

In many instances it is not possible to remove the hydrogen sulphide from a gas stream and simultaneously produce a satisfactory sulphur plant feed using conventional gas treating technology. In these cases the H2S, once removed from the gas, can present a serious disposal problem because its concentration in the product acid gas stream is too low to be fed to a sulphur plant but is far too high to be incinerated. One option is to treat selectively the acid gas stream itself and raise its H2S content to a level suitable for a sulphur recovery unit. However, conventional enriching of the acid gas stream may still fail to yield satisfactory results.

Sulphur plants operate best with a feed containing 55% or more H2S. The balance of the SRU feed stream is CO2 and water, with small amounts of hydrocarbons, inerts, and other components. Lower concentrations of H2S can be processed only with increasing levels of sulphur plant complexity, larger equipment, and higher cost. Streams having less than 32% or so H2S are near the lower limit for a straight-through Claus process.

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The Al-Shaheen Refinery Project

Summary

A.F. Slavens, P. Wadhwa and K. W.-K Wong of Black & Veatch Energy and R. Srinivas of Qatar Petroleum provide an overview of the Al-Shaheen Refinery Project. Black & Veatch's role in the develop­ment of the sulphur recovery complex is described and QP's current plans for managing the sulphur product from the new facility are discussed.

Abstract

Production of 925 t/d of elemental sulphur may not sound much in these current times of 2,000+ t/d single train sulphur recovery units (SRUs), 5,000 - 10,000 t/d single-facility sulphur complexes, and 12,000 t/d sulphur product handling terminals; however, without a readily-available logistical outlet, 1,000 t/d of product generation would quickly become a roadblock to continued processing in any facility. This is precisely one of the challenges being faced by Qatar Petroleum (QP), in the development of the Al-Shaheen Refinery Project (SRP), a 250,000 bbl/d grassroots refinery being planned for installation at the Mesaieed Industrial Area in Qatar.

Although the nearby Ras Laffan Common Sulphur Project is gearing up for 12,000 t/d of solid sulphur export from the country, this capacity is reserved for product sulphur from existing and future gas processing projects associated with the North Field development. Thus, oil refiners in Qatar cannot rely on this massive development as a transportation solution, and must find their own independent means to move their product sulphur from processing facility to market.

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ASRL Review: Emerging technologies for bitumen upgrading and utilisation

Summary

Alberta oil sands bitumen, including heavy oils in other reservoirs and the bitumen in the carbonate trend are, in total, the largest hydrocarbon reserves worldwide, although current estimates for recoverable hydrocarbons put Alberta second to Saudi Arabia at around 300 billion barrels. The "green lobby" has raised some concerns about the environmental impact of oil sands with respect to CO2 emission and land disturbance although it should be noted that all lands will be restored to their original condition as plants close. Clearly, return of a mine-site to a rural landscape will take time but it is a requirement by law so, long term, oil sands developments pale into insignificance compared to any conurbation that one could find in California, Western Europe or any highly populated region.

Abstract

Alberta oil sands bitumen, including heavy oils in other reservoirs and the bitumen in the carbonate trend are, in total, the largest hydrocarbon reserves worldwide, although current estimates for recoverable hydrocarbons put Alberta second to Saudi Arabia at around 300 billion barrels. The “green lobby” has raised some concerns about the environmental impact of oil sands with respect to CO2 emission and land disturbance although it should be noted that all lands will be restored to their original condition as plants close. Clearly, return of a mine-site to a rural landscape will take time but it is a requirement by law so, long term, oil sands developments pale into insignificance compared to any conurbation that one could find in California, Western Europe or any highly populated region.

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The Canadian sulphur industry

Summary

Canada is the world's largest exporter of elemental sulphur, but the industry faces challenges ahead as sour gas processing gives way to increased refining of bituminous oil sands in northern Alberta.

Abstract

North America as a region is the largest producer of sulphur globally, with 17 million tonnes of sulphur produced last year, and 11 million tonnes consumed. While the United States is the major consuming nation, and also, via its refineries, the largest producer in North America, Canada’s combination of high production and relatively low consumption makes it the major global exporter of sulphur, and a power on the world market.

The Canadian sulphur industry is a mature one, and its roots date back to the first exploitation of sour natural gas in Alberta in the 1930s. Canada’s sour gas has long been the mainstay of its sulphur production, but processing of heavy oil fractions at domestic refineries also produces a share, and becoming increasingly important is sulphur from oil sands processing in Alberta.

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The changing Chinese sulphuric acid market

Summary

Over the past decade, rapid growth in China's phosphate industry has seen a corresponding expansion in the sulphuric acid sector. In the process pyrites have slipped from being the dominant source of sulphur, replaced by imported elemental sulphur from North America and the Middle East.

Abstract

China’s sulphuric acid market has seen dramatic changes over the past decade, and as a result not only has China greatly expanded its acid production capacity, it has also become a major importer of elemental sulphur in order to service this industry.

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Sulphuric acid by the surf

Summary

The Central Florida Section of AIChE held its 32nd Annual Clearwater Conference at the familiar and welcoming venue of the Sheraton Sand Key Resort, once again examining current issues in sulphuric and phosphoric acid operations and technology. The meeting remains a unique forum for the exchange of ideas and viewpoints - and an outstanding social occasion too.

Abstract

The annual AIChE Clearwater Conference offers a thoroughly well-proven formula: provide a forum for the best and brightest in the sulphuric acid and phosphates industries, all in a relaxed, family-friendly ambiance by Florida’s Sunshine Coast. The meeting regularly attracts around 250 participants and in addition to the opportunities to exchange ideas during the sessions and the refreshment breaks, participants have the further chance to meet in the evenings and enjoy the hospitality of companies supplying equipment, engineering and specialised products to the phosphate and sulphuric acid industry.

This year’s Clearwater meeting was held on Friday and Saturday, 6-7 June and consisted of two half-day sessions. The Friday afternoon session was the Annual Sulphuric Acid Workshop – now in its 11th year – and was again chaired by Rick Davis and Jim Dougherty. The topic was Design, Operation and Maintaining of Gas-to-Gas Heat Exchangers, and the workshop took the form of presentations from key industry players and a panel discussion.

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A unique common sulphur project

Summary

With continuing growth of Qatar's LNG, GTL, natural gas and NGL production, the Qatargas Common Sulphur Facility (CSF) is being developed as the optimum means for collecting, processing and shiploading of the sulphur by-product from the multiple producers. R. Layfield of Qatargas Common Sulphur Project and J. Johnson of WGI Middle East outline the execution and technical aspects of the project.

Abstract

The Common Sulphur Facility (CSF) in Qatar is a world class sulphur processing facility located within Ras Laffan City (RLC). The completed facilities will include a molten sulphur collection pipelines network that runs throughout RLC to receive a nominal daily average design flow of up to 12,000 t/d molten sulphur by-product from multiple natural gas, LNG and GTL facilities. The collected molten sulphur will be delivered to the existing berth area where the primary processing equipment will form the sulphur into premium-grade solid granules, provide temporary storage, and then load the product onto ships for use in other industries.

The concept of a “common sulphur collection, processing and ship loading” facility was chosen through careful study by a group of sulphur producers with representatives from other existing or future operating companies within the RLC complex. The “common” approach was determined as the safest, most economical and environmentally friendly means to ensure that by-product sulphur from the facilities could be marketed without disrupting the RLC infra-structure and daily activities – and without jeopardising continuous production of much more valuable products from the individual processing facilities.

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Two for one analysis

Summary

A prototype gas analyser that uses both UV and IR spectroscopy for the measurement of hydrogen sulphide and hydrocarbons in the acid gas feed to the reaction furnace of a Claus sulphur recovery unit is in the testing phase at a natural gas plant in Alberta, Canada. R. Hauer, K. Harris and D. Potter of Ametek Process Instruments describe the development of the new gas analyser and report on recent field test results.

Abstract

Amine gas treating, or sweetening, is a process using amine solutions to remove acid gases (H2S and CO2) from hydrocarbon gas in refineries and gas plants. Once the acid gases have been removed, they are typically further treated in a Claus SRU. A perfect version of this process would completely separate acid gases from the hydrocarbons (HCs), so that the treated gas would contain no acid gases and the gas sent to the SRU would have no HCs. Hydrocarbons do end up in the acid gas, creating SRU operating issues including unstable off-ratio operation and reduction in catalyst activity. The unstable operation can reduce efficiency and also potentially damage downstream equipment such as the amine solvent in the tail gas clean up unit.

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Making it last

Summary

Storing molten sulphur in reinforced concrete pits is common practice, but thermodynamic stresses, chemical attack, and high acidity often accelerate their deterioration, resulting in costly and repetitive repair work. Des Owen of Sulphur highlights important considerations for sulphur pit design, and outlines techniques to ensure repair work stands the test of time.

Abstract

Sulphur compounds extracted from petroleum were once an unwanted by-product of hydrocarbon refining. Yet today, sulphur is a valued commodity and the storage and distribution of sulphur in its liquid form is preferred by many in the petroleum industry, as well as other end uses including match head and soap manufacturers. Handling and storing molten sulphur can avoid issues associated with odour and sulphur dust, and allows for the product to be easily transferred and extracted from storage and transport vessels.

Yet storing molten sulphur requires purpose built storage facilities capable of withstanding high temperatures, corrosion, acid attack and other pressures. This presents a challenge for operators of these facilities, and deterioration of sulphur storage structures is common. This is partly due to the aggressive nature of molten sulphur, but also due to the materials used in construction.

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Sulphur in review

Summary

On July 17th the Sulphur Institute (TSI) gave its first-ever 'webinar' presentation of its views on the sulphur market. Sulphur listened in.

Abstract

The sulphur market has seen dramatic developments in recent years. TSI’s new president and CEO Catherine Randazzo, opening the presentation, stated that several variables or situations will impact both production and consumption within the coming decade. “Developments in West Asian gas-recovered sulphur and US oil-recovered sulphur as well as the evolution of Canadian oil sands will dominate the production scene,” noted Randazzo. Various activities in these areas, as well as in China and Kazakhstan, will be focal points as we move through the next decade, she added. “Where, when and how much?” will be what TSI will be watching to prepare industry for the challenges ahead.

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Better sulphur filtration

Summary

The combustion of liquid sulphur is an important process in the production of sulphuric acid. Before the liquid sulphur is burned, the sulphur is filtered to protect the catalyst in the down­stream converter. Jan Hermans of Sulphurnet.com discusses the latest trends in sulphur filtration.

Abstract

Today, high sulphur prices and the shortage of sulphur mean that some companies have no option but to buy whatever quality sulphur comes on the market. All types of new sulphur sources are taken into account, even volcanic rock sulphur containing up to 15% ashes. These high levels of ash, organics and other impurities require a good sulphur cleanup procedure to prevent catalyst poisoning in the converter of a sulphuric acid plant. The sulphur processing and filtration processes originate from the early 1950s and have remained virtually unchanged despite changing sulphur sources and technology advances.

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