[By our guest columnist, 'Thiophilos']
If any one person in the sulphur business was on top of the matter of measuring and interpreting the temperature of sulphur it was surely Earnie Emery, whose initials became his company name E2T, synonymous with Claus front end reaction furnace measurement in sulphur recovery systems. Earnie passed on late last year and it seems timely that this Sulphur column take the opportunity to both recognise Earnie’s contributions and the critical importance of measuring, understanding and controlling temperatures throughout the sulphur recovery process.
The Claus reaction furnace has been called the ‘heart’ of the SRU, in the thousands of such units that collect sulphur from where Mother Nature put a lot of it, to make it available to mankind where it is needed in this day and age of major commodity economics. The values of “T” in such units are well into the 1,000C plus range; hardly a trivial challenge to measure with confidence and accuracy. To make matters even more challenging, the chemical reactions that generate these temperatures produce conditions that are, to say the least of it, hard on the construction and measurement materials. But Earnie, with his background in rocket propulsion technology, was up to the task with his focus on infra-red radiation probes and their quantifiable sensitivity to the temperature of the generating source. So much of the early approach to Claus front end furnace technology regarded the unit as a waste disposal technology rather than a sophisticated and relatively complex chemical reactor whose efficiency depended very much on the monitoring and control of its operating temperature.
Earnie and others asked: at what temperature did you optimize the combustion product sulphur dioxide/ hydrogen sulphide ratio to feed to the downstream catalytic conversion units? At what temperature did the firebox lining, burner tips and tube sheet walls start to show unacceptable wear and tear? How much hydrogen was being produced in the furnace by direct thermal cracking of hydrogen sulphide for later use as a reducing agent to reduce emissions? How did ammonia and COS production vary with temperature? How valuable would so called “waste heat” from the FEF high temperature operation in the overall thermodynamics of an optimally functioning furnace be?
All of these (and more) factors became very much more relevant as the struggle to improve overall Claus efficiency from a barely adequate 70% sulphur recovery to the 99% target in today’s systems that is required to meet environmental standards. So often we forget that these kinds of targets can only be achieved if pioneers such as Earnie Emery have had the smarts to apply technology that helped lead from the rocket propelled way to the moon landing to the more mundane but, in its own, way equally important eco-friendly production of the stuff that makes the stuff that grows the stuff we eat?
Earnie’s efforts focused on the FEF and its temperature measurement and control, but it also drew attention to the more general importance of the temperature parameter in many other components of the sulphur production system. The efficiency of the catalytic stages of the Claus redox system which react the hydrogen sulphide and sulphur dioxide from the front end furnace to produce elemental sulphur are critically temperature dependent. Earnie’s infra red thermometers might not have such a seminal role inside a catalyst bed, but they sure worked in keeping an IR eye on the external temperature gradients on the outside of the reactor bed. Catalyst activity drops off inside the charge and the heat of reaction drops and this can be detected on the outside shell. We have a problem inside; let’s fix it and keep the recovery up in the high nineties. Stands to reason. Oh that more of us humans had a better handle on this essential of all civilised activities – reasoning.
But there is still more about the role of temperature in the overall sulphur business. There are few if any other chemical elements that go through as many fundamental changes as sulphur in such a readily accessible temperature range. Its orthorhombic solid crystalline form ‘morphs’ to monoclinic before melting to liquid cyclooctasulphur at 119C. As it heats up to 159C its eight-membered ring molecules break up and reform into a variety of so called Sx species, and finally into long chain polymers which hugely affect its viscosity and fluidity. When it cools down again to solidify, all these species have to reverse themselves and do so at a variety of rates leading to very complex solid sulphur mixtures which can effect the handling and storage properties! Who said temperature control wasn’t a critical factor in the sulphur business?
Thank you, Earnie Emery for your contribution.
‘Thiophilos’
Tuesday 1 February 2011
Is China running out of steam?
During 2010 we seem to have moved back into another commodity price boom, with all major commodities, from oil to metals, grains and of course sulphur all heading back to the kind of price levels last seen in 2007-8.
Much of the rise in markets has been sustained by activity in the developing world, especially China, where the economy surged forward last year. GDP has grown by 10.3% in 2010, up from 8.7% in 2009, with strongest growth in 4Q 2010 and projected to go forward into 1H 2011. The Chinese government has actually become concerned by the pace of growth and taken steps to try and throttle back the economy, raising the standards for bank lending seven times in an attempt to ease back the flow of credit, and it is forecast that interest rates may have to begin to rise soon. Some people in commodity markets have become concerned by this, saying that 2011 will be a year of “downside risks” and bear markets. Costs are rising in many commodity markets, they argue, as producers must pay for development costs in local currency but sell in dollars, a currency that has weakened against many currencies – especially the Chinese yuan - over the past two years. The fear is that the Chinese economy is trying to expand too quickly and will soon fall victim to its own success, bringing the current commodity boom down with it.
Needless to say, others take a different view and say that fiscal moves in China will merely prevent overheating, and that Chinese demand remains robust. Among the bears, Danske Bank’s 2011 Commodities Report argues that we are still on the upswing of a 40-year demand-driven ‘super-cycle’ in commodity markets which last peaked in the mid-1970s (driven in the 1950s - 70s, it was argued, by post-war economic growth in Europe and Japan, and finally curtailed by the Oil Crisis) and which hit its trough around the turn of the millennium as markets were flooded in the wake of the collapse of the FSU and Eastern European economies. Seen in these terms, it argues, 2008 was merely a short-term correction to a continuing prevailing upward trend, now driven by Chinese (and to a lesser extent Indian) industrialisation, which may not peak until some time between 2015 and 2025. The super-cycle was an idea which gained a good degree of popularity in commodity markets in the 2005-08 period, was quietly brushed aside during the recession, but seems to be gaining traction again.
Certainly the future for base metals appears to be tighter markets and higher prices. Copper in particular is singled out for more record pricing – probably topping $11,000/t. Stocks to consumption ratios on the London Metal Exchange are standing at a historical low of 2.3 weeks and deficits are, according to some commentators, becoming “structural”. On the agricultural side, too, while wheat is roughly in balance, there are low stocks on the corn side – just 16% of annual demand and well below the 20-40% range that is generally considered a balanced market.
The impact on sulphur is harder to predict, dependent as it is upon various other commodities. But as we discuss in Sulphur in this issue, China’s hunger for copper has led to a major increase in sulphuric acid production from smelting in the region, while the buoyant nickel market is gradually having the reverse effect by driving increased acid consumption in leaching projects. Record phosphate prices continue to feed into sulphur demand for agriculture, but high oil and gasoline prices have driven major investment in refining capacity and increased sulphur production. Overall the pressure seems to be on the upside rather than the downside, and China has certainly become an engine of the sulphur market – in 2009 it imported 12.1 million tonnes, and the figure for 2010 will probably be 10.0 – 10.5 million tonnes. Sulphuric acid production was up 20% over the year. So far this has sustained sulphur prices in the range $165-175/tonne, and producers around the world are presumably making hay. The indications seem to be that China’s boom has at least a few more years to run, even if its sustainability in the long run is more open to question.
Much of the rise in markets has been sustained by activity in the developing world, especially China, where the economy surged forward last year. GDP has grown by 10.3% in 2010, up from 8.7% in 2009, with strongest growth in 4Q 2010 and projected to go forward into 1H 2011. The Chinese government has actually become concerned by the pace of growth and taken steps to try and throttle back the economy, raising the standards for bank lending seven times in an attempt to ease back the flow of credit, and it is forecast that interest rates may have to begin to rise soon. Some people in commodity markets have become concerned by this, saying that 2011 will be a year of “downside risks” and bear markets. Costs are rising in many commodity markets, they argue, as producers must pay for development costs in local currency but sell in dollars, a currency that has weakened against many currencies – especially the Chinese yuan - over the past two years. The fear is that the Chinese economy is trying to expand too quickly and will soon fall victim to its own success, bringing the current commodity boom down with it.
Needless to say, others take a different view and say that fiscal moves in China will merely prevent overheating, and that Chinese demand remains robust. Among the bears, Danske Bank’s 2011 Commodities Report argues that we are still on the upswing of a 40-year demand-driven ‘super-cycle’ in commodity markets which last peaked in the mid-1970s (driven in the 1950s - 70s, it was argued, by post-war economic growth in Europe and Japan, and finally curtailed by the Oil Crisis) and which hit its trough around the turn of the millennium as markets were flooded in the wake of the collapse of the FSU and Eastern European economies. Seen in these terms, it argues, 2008 was merely a short-term correction to a continuing prevailing upward trend, now driven by Chinese (and to a lesser extent Indian) industrialisation, which may not peak until some time between 2015 and 2025. The super-cycle was an idea which gained a good degree of popularity in commodity markets in the 2005-08 period, was quietly brushed aside during the recession, but seems to be gaining traction again.
Certainly the future for base metals appears to be tighter markets and higher prices. Copper in particular is singled out for more record pricing – probably topping $11,000/t. Stocks to consumption ratios on the London Metal Exchange are standing at a historical low of 2.3 weeks and deficits are, according to some commentators, becoming “structural”. On the agricultural side, too, while wheat is roughly in balance, there are low stocks on the corn side – just 16% of annual demand and well below the 20-40% range that is generally considered a balanced market.
The impact on sulphur is harder to predict, dependent as it is upon various other commodities. But as we discuss in Sulphur in this issue, China’s hunger for copper has led to a major increase in sulphuric acid production from smelting in the region, while the buoyant nickel market is gradually having the reverse effect by driving increased acid consumption in leaching projects. Record phosphate prices continue to feed into sulphur demand for agriculture, but high oil and gasoline prices have driven major investment in refining capacity and increased sulphur production. Overall the pressure seems to be on the upside rather than the downside, and China has certainly become an engine of the sulphur market – in 2009 it imported 12.1 million tonnes, and the figure for 2010 will probably be 10.0 – 10.5 million tonnes. Sulphuric acid production was up 20% over the year. So far this has sustained sulphur prices in the range $165-175/tonne, and producers around the world are presumably making hay. The indications seem to be that China’s boom has at least a few more years to run, even if its sustainability in the long run is more open to question.
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