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The coming sulphur crunch for shipowners

Summary

How the shipping industry will cope with one of the most significant reductions in sulphur fuel content in recent times remains a headache for refiners and shipowners alike.

Abstract

Current plans to tighten the regulation of sulphur content of marine fuels are continuing to cause headaches for both shipowners and refiners as some of the more stringent deadlines loom. Marine fuel oils have already tripled in price since 2000, and not all of this has been driven solely by hikes in oil prices. The marine sector accounts for a major slice of demand for fuel oil, which has always traditionally been the ‘bottom of the barrel’ – the remains after higher and lighter fractions of the crude have been recovered. As such fuel oil has tended to be the dumping ground for unwanted fractions of the oil, like sulphur. Fuel oil has traditionally represented about 15% of each barrel of crude. However, demand for fuel oil has been falling, initially in the power sector as power producers switch to gas or coal, and now it is about to see its major slice of demand – the marine bunker fuel sector – also take a hit. Average fuel oil yields have dropped to about 10%, and in the US the fall has been even steeper, from about 6.5% in the 1990s to 3.2% in 2011. So marked has the fall in fuel oil output been that in fact prices reached levels of over $720/t earlier this year, far in excess of its usual $150-250/t price range, driven in part by increased consumption for power production in the wake of a large-scale nuclear shut-down following Fukushima. Keywords: MARPOL, IMO, ECA, SCRUBBING, LSFO, FUEL OIL

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A topical scrutiny

Summary

It was standing room only during the sessions of the 36th Annual Clearwater Convention, organised by the Central Florida Section of the American Institute of Chemical Engineers (AIChE). The annual assessment of topical issues on sulphuric acid and phosphoric acid technology has spotlighted more facets in the collective understanding of these topics and prompted further discussion and debate.

Abstract

It is almost a matter of routine to report well-attended Clearwater meetings and enthusiastic audiences, and the 36th Annual Clearwater Convention of the Central Florida Section of the American Institute of Chemical Engineers (AIChE) on 8-9 June matched the established standards that participants have come to expect. As customary, the 2012 AIChE Clearwater Convention comprised two half-day sessions, commencing on the Friday afternoon of 8 June with the Sulphuric Acid Workshop, which is now well established as a curtain-raiser to the main event. Again under the exemplary chairmanship of Rick Davies and Jim Dougherty, the 15th Annual Sulphuric Acid Workshop focused on Sulphuric Acid Coolers. The topic centred on anodically-protected shell-and-tube heat exchangers: these have dominated the sulphuric acid industry for over two decades, replacing cast iron coils, which were prone to acid leaks. These coolers have gained an excellent reputation for reliability and have become established as the industry norm. However, they require full maintenance and proper operation to ensure continued reliability. Keywords: sulphuric acid coolers; anodically-protected acid coolers; corrosion control; cooling water treatment; hydrogen safety

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Better Claus TGTU performance

Summary

Patented HIGHSULF ™ technology always leads to better TGTU performance over a conventional TGTU plant. Even if higher H2S content is not required for good sulphur plant operation itself, eliminating CO2 reduces the gas load on a sulphur plant thereby increasing its capacity and the sulphur recovery level. MDEA based HIGHSULF provides H2S-rich feeds in a single step, thereby eliminating the need for more expensive solvents. T.K. Khanmamedov of TKK Company, D. Tunnell, of BSDT Seminars and V.A. Khodakovsky, of OJSC "Yuzhniigirpogaz" discuss the merits of using HIGHSULF in tail gas treating units.

Abstract

The operation of a sulphur plant depends on the quality of the feed, as shown on Figs. 1 and 2. This is most important for gas processing plants with a tail gas treating unit (TGTU) with an amine section (SCOT or SCOT type units). The acid gas produced in the amine section of the TGTU is recycled back to the SRU and this acid gas contains a huge amount of CO2 that dilutes the feed to the SRU. HIGHSULF TGTU is a patented process from TKK Company that can be applied incrementally in the amine section of any existing TGTU. HIGHSULF TGTU actually takes steps to increase the H2S content of the feed gas to the amine section of the TGTU itself. Keywords: tail gas treating, solvent selectivity, SCOT, generic MDEA, speciality solvent, AGE, HIGHSULF

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ASRL Review: How do Claus tail gas reduction catalysts work?

Summary

A twice yearly review contributed by Alberta Sulphur Research Ltd. P.D. Clark, Director of Research, Alberta Sulphur Research Ltd and Professor of Chemistry, University of Calgary and, N.I. Dowling and M. Huang, Alberta Sulphur Research Ltd.

Abstract

Reduction of Claus tail gas sulphur species to H2S and recycle of that H2S is, perhaps, the most effective technology for achieving >99.9% sulphur recovery in a large scale plant. This process (Figure 1) has undergone numerous refinements over the years, with production of catalysts that operate at low temperature (<250°C) being one of the more important adaptations. However, under some circumstances, formation of COS and, occasionally, methyl mercaptan in the reduction reactor may prevent a plant operating at super high efficiency (>99.9% total recovery). Over the years, a mechanistic picture of how Claus tail gas reduction catalysts work has built up but little evidence has been published to support the general picture. For example, it is said that SO2 is reduced to H2S by H2 on MoS2 sites (Figure 2) but, since the catalyst uses alumina as a support material, it would seem that the facile Claus reaction must also occur. Sulphur formed in the Claus reaction would then be reduced to H2S by H2 at MoS2 sites. Also, it is assumed that residual CS2 and COS are hydrolysed to H2S on alumina sites of the reduction catalyst. This all seems very logical given the very high H2O content of the tail gas, but the temperature of most reduction units is 300°C at best and, with high activity catalyst, <250°C. These temperatures are too low for CS2 hydrolysis, so what really happens? The water gas shift reaction (WGSR) (Figure 2) is a vital function of reduction catalysts since it makes H2 available from the reducing equivalent of CO. This process may well be linked to COS formation as net production of COS, as mentioned, is sometimes observed. Keywords: SHIFT, COS, MERCAPTAN, COBALT, MOLYBDENUM, TITANIA

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Very low sulphur fuels

Summary

How feasible or indeed desirable is it to reach very low levels of sulphur content in fuels?

Abstract

Tightening environmental regulations are gradually driving reductions in sulphur levels in fuels all over the world. Sulphur levels in road vehicle fuels are now down to “ultra low” levels of around 10ppm in Europe and Japan and 15 ppm in the United States for diesel fuels. The Worldwide Fuel Charter (WWFC), produced in 2006 by a consortium of vehicle and engine manufacturers, recommends 10ppm sulphur in its ‘Category 4’ standards for gasoline and diesel, in order to allow the most advanced catalytic emissions reduction technologies to work at their most efficient, with benefits for levels of NOx and hydrocarbon emisisons, and, for diesel, particulate matter, as well as improve engine life. While 10ppm is recognised as a practical limit, the WWFC report notes that the best fuels would be literally sulphur free, and it also includes data on tests conducted with fuel sulphur levels as low as 2-3ppm. But are levels as low as this possible, and, even if they are, is it sensible to try and reach such low levels? Limitations to HDS Sulphur removal in gasoline is relatively straightforward by current catalytic hydrodesulphurisation (HDS) processes, which use a cobalt/molybdenum/alumina catalyst. The challenge in the deep desulphurisation of fluid catalytic cracker (FCC) naphtha, however, is in selective conversion of sulphur compounds without saturating the olefinic compounds which contribute to higher octane numbers. Keywords: HYDROTREAT, HYDRODESULPHURISATION, HDS, THIOPHENE

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Flue gas cleaning alternatives

Summary

As oil reserves diminish, energy companies are forced to turn to heavy crude oil with high content of sulphur in order to satisfy demand for petroleum. At the same time they have to strive for high energy efficiency and low emission levels. Refineries wanting to reduce SO2 emissions from their FCCs or those using petcoke and/or heavy residue as a fuel for generation of steam and electrical power are finding that conventional methods of flue gas desulphurisation (FGD) using limestone wet scrubbing are becoming significantly more expensive and troublesome to operate as fuel sulphur content increases. Alternative processes can offer several advantages such as lower operating costs, no waste disposal, less water consumption and high heat efficiency.

Abstract

Confronted with growing energy demands and declining supplies of sweet crude oil, oil companies are starting to process more and more heavy crude oil with high content of non-volatile carbon and high sulphur. There are indications that the switch to heavy oil and tar sands could double or even triple refinery emissions emitting several gigatons of carbon dioxide to the atmosphere annually1. Delayed coking, visbreaking and thermal cracking are some of the ways of converting heavy fractions into more valuable, lighter products in refineries. The resulting petcoke and heavy residue by-products contain typically at least half of the sulphur content of the original crude oil. Keywords: HSFO; NOx removal; SNOX; LABSORB; EDV; LoTOx

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Enhanced energy recovery with SteaMax HRS™

Summary

In recent years, sulphuric acid plant engineers have searched for ways to reduce plant energy and operating costs. One way to reduce costs is the use of advanced heat recovery technologies. MECS, Inc. (MECS), a wholly owned subsidiary of DuPont, who pioneered heat recovery systems in sulphuric acid plants and has accumulated over 25 years of experience with its proprietary HRS™ technology, is now ready to announce the newest breakthrough in energy recovery, the SteaMax HRS™ System.

Abstract

SteaMax HRS™ provides for a significant increase in production of medium pressure steam, by upgrading low level heat and customising it for site specific energy requirements and site conditions. SteaMax HRS™ steam enhances commercial opportunities by providing electrical grid offsets or a revenue stream from the sale of the electrical energy. Sulphuric acid plants throughout the world can benefit from the enhanced steam generation provided by the MECS® SteaMax HRS™ System. Innovative advances Recent advances in HRS™ technology have introduced the concept of steam injection that upgrades low pressure steam by reacting it with SO3 in the vapour phase and recovering the exothermic heat of reaction and latent heat of condensation as medium pressure steam in the HRS™ tower/boiler. In these designs, about 33% of the water of reaction is added in the form of low pressure steam via the steam injector, thus increasing the amount of medium pressure steam generated. In comparison, SteaMax HRS™ uses a new steam injector and a new tower design, to innovatively address the challenges of mist generation and corrosion, thus extending the steam injection window to close to 100% and thereby eliminating the need for a diluter. Keywords: steam generation

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Heat management of the intermediate absorber

Summary

Outotec's sulphuric acid plants are designed as complete solutions. They incorporate highly efficient off-gas treatment facilities and the latest contact acid plants to achieve the lowest sulphur dioxide emissions and energy consumption levels required. In this article, Sebastien Gehrke of Outotec outlines design options for heat management in the intermediate absorption tower of a sulphuric acid plant to increase overall process efficiency. Considering that production circumstances vary, the most environmentally and hence the most economically sound solution involves fine-tuning the design concept to the individual customer's needs.

Abstract

According to 2011 figures, the world production of sulphuric acid reached almost 240 million tonnes per annum. The majority of acid is produced from elemental sulphur and is a highly exothermic process. Apart from being thermally self-sufficient, it can generate a considerable amount of steam. Thus, modern sulphuric acid plants commonly serve as “thermal power plants” for adjacent industrial complexes or they can generate electrical power without producing greenhouse gases via a turbine-generator set included in the plant facility. The energy flow from a conventional sulphuric acid plant consists of two main streams as shown in Fig. 1. About 57.5% of a plant’s energy intake is processed into high-pressure export steam. Reasonable steam production requires a more than moderate temperature level for heat transfer, which only the off-gases from sulphur combustion and the converter can deliver inside the acid plant. The heat transferred at a low temperature is normally dissipated as waste heat. This temperature is reached in the plant’s absorption section as hot sulphuric acid. Keywords: air cooler; HEROS; HIPROS

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In-line solutions provide enhanced sulphuric acid production

Summary

Process analyser technology has been making major inroads into the heart of production processes, including the sulphuric acid process. Helmut Berg of Bayer Technology Services discusses the development of this technology for improved process control and highlights some of the many benefits that can be achieved by employing these methods in the sulphur and sulphuric acid industries.

Abstract

Manufacturers are confronted with changing market conditions that have become even more challenging in recent years. Only high-performance companies can maintain and exceed their market position through quality, efficiency and reliability. This is where process analyser technology (PAT) comes into play. Having a clear understanding of the composition of streams and concentrations of components in the production process enables precise control of process steps and production based on real-time data to achieve the optimum operating conditions from both a technological and economic viewpoint. PAT has developed strongly in the last 20 years and has found its way from applications in the periphery of production facilities (off-gas, waste-water) right into the heart of production processes. It provides many benefits including: l unburdening of lab staff from routine work (in some cases shifts can even be cancelled) through employment of PAT, thus making significant cost savings; l precise end-point detection of batch processes; l continuous production closer to the specification limits, increasing yield and reducing energy consumption; l safeguarding of product quality through improved and quality-data based process control. Keywords: PAT, BAYQIK

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A look at India

Summary

Don Messick of The Sulphur Institute considers how the situation has changed for India as regards phosphate and sulphur fertilizers.

Abstract

India has been overshadowed by China for years despite the country’s continuing growth. In 1990, India had a gross domestic product of $327 billion. In 2011, the number had grown to $1.7 trillion (Source: World Bank). With that growth, India has seen a lot of changes in areas that impact the sulphur business. Let’s look at the Indian fertilizer industry and changes there. India has grown to be the third largest producer, second largest consumer and world’s largest importer of fertilizers. In 1906, India established its first single superphosphate (SSP) plant with real growth in the sector seen in the 1960s. Today, India has 137 fertilizer plants with 18.6 million tons (N+P2O5+K2O) of production capacity. The industry now has 19 complex fertilizer plants, including DAP facilities, and 82 SSP plants, so SSP remains a significant fertilizer source providing both phosphorus and sulphur. Keywords: BENTONITE, SSP, IFA, NUTRIENT, SUBSIDY

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