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Publication > Issue > Articles

DME's second wind

Summary

Methanol derivative dimethyl ether (DME) has grown from a small-scale derivative used as an aerosol propellant to a market of several million t/a as a substitute for LPG, particularly in China, but market saturation and concerns over illegal blending have seen growth level off there. Now, however, a new push for DME use as a commercial vehicle fuel may see demand take off again over the next decade.

Abstract

Dimethly ether (DME) has made a major transition over the past decade from primarily a CFC-free aerosol propellant to an alternative fuel. This has been especially true in China, which now accounts for the vast majority of the global DME market. In the process the global DME market has increased from a couple of hundred thousand tonnes per year to several million tonnes. But now the compound is on the threshold of another potential step change which could see demand increase still further. DME is potentially usable as a fuel in three different ways; in power plants, as a substitute for diesel in road vehicles, and as a substitute for liquid petroleum gas (LPG) in home heating and cooking applications. It has been as a blendstock with LPG to extend the availability of expensive propane (in the current climate of high oil prices) that it has made its greatest strides so far, but it seems that DME’s greatest promise could be as a substitute for diesel as a clean-burning vehicle fuel; as an oxygenated fuel it burns more cleanly than straight hydrocarbons. Keywords: LPG, Volvo, truck, ship, shipping

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One hundred years of ammonia production

Summary

This year marks the centenary of the first industrial production of ammonia, by BASF in Germany. Gerald Williams of Plant Surveys International and Venkat Pattabathula of Incitec Pivot consider the significant contribution to feeding the world that the process has provided.

Abstract

One hundred years ago, in 1913, BASF (then Badische Anilin und Soda Fabrik) began operation of the world’s first commercial ammonia plant in Oppau, Germany, 3 km north of the company’s large Ludwigshafen site (Figure 1). The Oppau plant used what is now called the Haber-Bosch process to synthesise ammonia by reacting hydrogen and nitrogen over an iron-based catalyst. The initial plant capacity was 30 t/d of ammonia. Coal and coke were used to produce steam and coke oven gas which was purified and compressed ahead of ammonia synthesis, which was converted to ammonium sulphate for sales. The Haber-Bosch Process Fritz Haber, an industrial chemist, and Carl Bosch, a chemical engineer, have been named as the world’s most influential scientists of all time by readers of the UK Institute of Chemical Engineers’ magazine The Chemical Engineer in March 2010. The German duo were responsible for devising the Haber-Bosch process, perhaps the most recognised chemical process in the world, to capture nitrogen from the air and convert it to ammonia for use in fertilizers. Keywords: Haber, Bosch, BASF, Kellogg, AIChE

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Regulation of greenhouse gas emissions

Summary

Regulations on the emission of carbon dioxide and other greenhouse gases from process industries continues to tighten, particularly in Europe, with potential knock-on effects on the ammonia and nitric acid industries, but there are considerable uncertainties over the direction of future policy.

Abstract

The fact that the world has experienced rising temperatures over the past decades is beyond dispute, and while there has been debate about the extent to which this has been down to man-made or ‘anthropogenic’ emissions of carbon dioxide, the scientific consensus has gradually hardened towards that conclusion. The question of what should be done about this has however been an extremely vexed one. Developing countries have argued that they have inherited a situation created by developed countries – which can now afford to reduce emissions – while developing countries which are still industrialising argue that reducing their own emissions would prevent them from reaching developed world status, while developed countries argue that their own emission reductions are lost in the new emissions being generated by developing countries. Keywords: CDM, CER, ETS, EU, trading, N2O, carbon tax, carbon leakage

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Improving efficiency and profitability

Summary

Many factors affect the performance and economics of nitric acid plants. A close relationship between the technology/catalyst supplier and its customers is important when striving to achieve the best plant performance and profitabilty. In this article, Heraeus, Johnson Matthey and MECS report on how their technologies are helping the nitric acid industry to improve their operations.

Abstract

The cost of nitric acid manufacturing by ammonia oxidation is governed by several factors. One large factor is the specific ammonia consumption, i.e. the amount of ammonia consumed to produce one tonne of acid. Another major factor is loss of precious metals from the precious metal based gauze catalyst. An increasing cost-driver is emissions, especially in the form of N2O. Depending on the local emission legislation and the emission level of the plant, these costs can reach the same level as precious metal losses. An additional but typically smaller influence on the total costs of ownership is the precious metal inventory, catalyst manufacturing and refining of the used catalyst gauzes. Heraeus Technologies Heraeus technologies offer various ways of improving the performance and economics of nitric acid plants. Depending on the situation of the individual plant it might be necessary to value a factor like emissions costs higher than others. In plants with low ammonia costs, conversion efficiency might be of less value than metal losses. Therefore Heraeus offers to prepare a comparison of different catalyst solutions for each individual plant, to help its customers to choose the optimum system. Keywords: catalyst gauze, catchment gauze, metal loss, campaign length, advanced coating technology.

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Critical high pressure equipment in urea plants

Summary

Process licensors, HP equipment fabricators and special stainless steel suppliers all have an important role to play to meet the growing demands of the global urea market in the coming years. In this article Stamicarbon discusses its latest design and construction considerations for critical high pressure equipment in Stamicarbon urea plants, Saipem discusses its latest advanced technology solutions and improved manufacturer qualification procedures and we report on some of the leading material and equipment suppliers for HP urea equipment.

Abstract

Market analysts have a positive outlook for the global urea market in the coming years. Magnus Brodin, Sandvik’s Global Product Manager, tube and pipe for the Chemical Segment, gave Nitrogen+Syngas his view on why the global urea market is set to enjoy a bright future: Urea remains the most popular and economical of all nitrogenous fertilizers. Whilst the vast majority (>90%) of urea supplies are used for nitrogenous fertilizers, other uses for urea include the manufacture of plastics and adhesives, explosives and even as a browning agent for pretzels. Urea has the highest nitrogen content of all common solid nitrogenous fertilizers, which gives it the lowest transportation costs per unit. Experts are confident that urea production will enjoy a significant upswing going forward. This optimism is supported by a consistent growth in demand for urea since 2004. This has risen by 3.5% year-on-year in China and by 2.6% across the rest of the world. Such trends are expected to continue until 2016, driven by the exploitation of shale gas in the United States, new gas fields in Brazil and political incentives in India, along with low-cost producers and inexpensive natural gas in the Middle East and Africa (MEA). Keywords: special stainless steels, corrosion, ammonium carbamate, oxygen passivation, materials, Safurex, leak detection, pool condenser, manufacturer qualifications, level measurement.

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New bayonet-U-tube WHB improves heat recovery

Summary

The synthesis gas waste heat boiler in an ammonia plant operates under challenging conditions, which in many ways requires a special design of boiler. Haldor Topsøe has recently patented a new bayonet-U-tube waste heat boiler to overcome the mechanical and corrosion phenomena experienced with typical synthesis gas waste heat boilers.

Abstract

Topsøe’s ammonia synthesis technology is based on radial flow converters for the synthesis of ammonia from hydrogen and nitrogen. Topsøe pioneered radial flow converters with the installation of the first radial flow converters in the 1960s. Since then, continuous development has resulted in a comprehensive portfolio of radial flow converter designs, which can be provided in various modules (with single-, double- and triple-beds), all of which comprise a pressure shell and separate internals, the latter containing the catalyst. The Topsøe S-200 ammonia synthesis converter, first introduced in 1976, is a two-bed radial flow converter with indirect cooling between the catalyst beds. The S-200 concept can still be supplied to existing users of S-200 baskets and for new plants where the two-bed solution is the optimal choice. Keywords: heat recovery, ammonia, synthesis loop, bayonet, U-tube, waste heat boiler, materials, hydrogen attack, HTHA, LTHA

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Plant Manager+ No. Problem No. 20 Unblocking pipelines after a urea plant shutdown

Summary

In several sections of a urea plant pipelines, and sometimes heat exchangers, can easily become blocked below a certain temperature and crystallisation can take place. In the evaporation section, urea melt is present which crystallises at about 133°C when in the pure form. Urea can also polymerise to form biuret, triuret and poly-urea with high crystallisation temperatures when urea is kept for a prolonged period at high temperatures. The internals of other equipment can also suffer from these problems (see picture below, showing poly-urea in the internals of a vacuum separator). In the recirculation section, ammonium carbamate is present which crystallises at about 153°C maximum when in the pure form. In the high pressure synthesis section, urea and carbamate mixtures are present. During normal operation the risk of lines and heat exchangers becoming blocked is small, however during a plant shutdown blocking can occur when the right measures are not taken. In other industries, applying heat may be a normal procedure when solids block a pipeline or heat exchanger. In a urea plant it is a little more complicated – when solid ammonium carbamate is heated up it decomposes into gaseous ammonia and carbon dioxide. When urea is heated up, however, it partly decomposes into gaseous ammonia and isocyanic acid and partly reacts to produce other products like biuret, triuret and other poly urea molecules, which have even higher melting points. Pure biuret, for example, has a melting point in the range of 185-190°C and pure triuret 231°C. Alternative measures are therefore required to unblock pipelines and heat exchangers. This discussion looks at which measures to take and what to do when a line is blocked and is a follow-up of an earlier Round Table Discussion.

Abstract

Mr Manzoor Ahmad Taraqfdar of Bangladesh Chemical Industries Corporation in Bangladesh introduces the problem of blockages in urea plants after shutdown: After a shutdown, when we are ready to start-up, on several occasions we have experienced a line blockage. We are not sure whether the white material is ammonium carbonate or ammonium carbamate. Normally this blockage can be removed by hot water, but when water washing is not possible without dismantling the pipeline we have tried flame heating of the pipe from the outside by removing the insulation. However, most of the time it was unsuccessful and it was necessary to dismantle the pipeline. Keywords: flushing, unblocking, crystallisation, ammonium carbamate, skin temperature measurement.

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Africa's gas rush

Summary

New deposits of gas continue to be discovered along Africa's east and west coasts, most recently in Tanzania and Mozambique. Will sub-Saharan Africa be the next cheap, stranded gas location to become the focus for the ammonia and methanol industries?

Abstract

Africa’s traditional gas development has mainly been in North Africa, with Algeria, Libya and Egypt the main producers. Below the Sahara, only Nigeria and to a lesser extent South Africa have been major producers. But a raft of new gas developments means that the region is now the focus for increasing interest in developing downstream gas-based petrochemical projects. Indeed, while in the rest of the world areas with so-called ‘stranded’ natural gas are becoming fewer and further between as urban areas are tied in via pipeline or LNG terminals to the global gas grid, sub-Saharan Africa offers one of the few remaining major regions where this is not the case and gas is this, potentially, relatively cheap. New gas discoveries Africa is currently one of the most active continents when it comes to licensing and exploration. In the past 20 years, Africa’s gas reserves have increased by more than 150%, and from 2000-2012 an estimated 60-70 billion barrels of oil equivalent has been discovered in terms of both oil and gas, representing 20% of total additions to global oil and gas reserves, and sub-Saharan Africa has represented 35-46 billion barrels of oil equivalent of this, or 13% of world oil and gas discoveries. In addition, so called ‘yet to find’ reserves are currently estimated at 4 trillion boe worldwide, of which Africa represents 1 trillion boe or 25%. Africa currently has 14 trillion cubic metres (tcm) of proved natural gas reserves, or about 7.5% of the world total, but technically recoverable reserves are substantially higher at 74 tcm, almost 10% of world total. Gas production in Africa is forecast to grow by 2.7% per year, expanding to 400 bcm by 2035. Keywords: LNG, Nigeria, Togo, Ghana, GTL, Angola, Tanzania, Mozambique, Kenya

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