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Coal to syngas and chemicals in China

Summary

China, with its abundance of coal, has a strong demand for coal gasification to produce chemicals, olefins, ammonia, methanol, synthetic natural gas and power. Producing products such as ammonia and methanol from syngas derived from the gasification of coal requires tailor made solutions that can differ significantly from those utilised in natural gas based plants.

Abstract

 

Nowadays, most of the world ammonia and methanol production is based on natural gas as feedstock. However, in recent years there has been a new trend to exploit different types of feedstock, like coal and petroleum coke, that are abundant and less expensive in some parts of the world.

China has led this revolution, with the construction and commissioning of several ammonia and methanol plants based on coal gasification and reaching almost 33% of world ammonia production and 25% of world methanol production. Coal-based ammonia and methanol production in China accounts for 75% and 60% respectively of total domestic production.

China is the second largest energy consumer in the world, it has a fast growing economy and a booming demand for liquid fuels due to the largest automobile market. The country also has an attractive and profitable petrochemical sector and diversification of petrochemical feedstocks.

Although limited in oil and gas resources, China has an abundance of coal and a strong demand for coal gasification to produce chemicals, olefins, ammonia, synthetic natural gas and power.

Operators in China want technologies with strong environmental performance to address new emissions standards and regulations. Increasing environmental regulations promote the pursuit of clean coal technologies to produce syngas from coal.

The Chinese marketplace is looking for solutions with affordable CAPEX and OPEX. Operators want low cost, highly reliable technology that is manufactured within the country.

Until recently, coal projects have been the domain of large NOCs, but smaller owners and operators with access to coal are now starting to develop projects to monetise coal assets.

 

 

Keywords:

TRIG

™, KBR, Guandong, KRES, ThyssenKrupp, Uhde, HTW, PRENFLO, Casale, Isothermal Methanol Converter, Anhui Huainan Chemical Group, Johnson Matthey Catalysts, Davy Process Technology, KATALCO K8-11, KATALCO 51-series, KATALCO APICO, SNG 

 

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Urea plant designs up to 6,000 t/d

Summary

The trend for larger, single-train urea plants to take advantage of economy of scale continues. The major urea process licensors have all carried out detailed studies and evaluations based on past experiences, state-of-the-art technology and knowhow and using the latest analysis tools to verify urea plant designs that take world scale urea plants currently with a capacity of 3,000-4,000 t/d to the next stage with capacities of up to 6,000 t/d.

Abstract

he world population in 2011 exceeded 6.9 billion and is forecast to reach 9.3 billion in 2050. As the world population continues to grow, there is a greater demand for primary resources to deal with increasing needs for food and welfare. Urea is a crucial building block in the world’s food chain and will remain essential for world food supply for decades to come.

Driven by economy of scale and the ever increasing demand for urea, over the past decade the fertiliser industry has moved toward ever larger fertilizer complexes. These large capacities have so far been attained by using parallel production trains, together with an integrated utility plant. Today’s largest single scale urea plants have urea capacities in the range of 3,000-4,000 t/d. However, the realisation of 3,300 t/d ammonia plants and the availability of large quantities of natural gas, coal and pet coke has stimulated the development of larger single train urea plants capable of matching these large scale ammonia plants.

All of the leading urea process licensors are currently ready to offer larger single train urea plants with capacities of 5,000+ t/d and up to 6,000 t/d.

The economy of scale for large urea plants up to 6,000 t/d continues to be beneficial with regard to capital expenditure in relation to the total costs per tonne. However, the operating expenditure, represented by raw material and energy costs, remain the main cost driver for the total cost per tonne. Figure 1 shows how gas price affects total production costs per tonne of urea for multiple plant capacities. The positive influence on the margin per tonne of urea still generates significant benefits at large scale and acts as a driving force from an economic perspective.

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Central Asia looks outwards

Summary

Monetising the untapped gas resources of central Asia has been a major concern for the states of the region since the break-up of the Soviet Union. With pipeline access to major markets often constrained, gas-based chemical projects are gradually coming to become a key part of the picture.

Abstract

Oil and natural gas remain the mainstays of the economies of many of the central Asian states. Gas reserves are considerable; in 2010 Turkmenistan’s gas reserves were put at 8 trillion cubic metres (tcm), about the same size as Saudi Arabia and the fourth largest in the world. Azerbaijan, Uzbekistan and Tajikistan also have considerable reserves, and relatively limited export opportunities. This makes much of the region’s gas supplies effectively ‘stranded’ – some of the more remote gas in the world.

 

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Urea: strong fundamentals

Summary

Demand for urea continues to maintain a strong rise, but major tranches of new capacity are expected in Africa, China, the Middle East and FSU, while natural gas availability and policies on export and subsidy continue to dominate urea trade.

Abstract

Urea continues to be the world’s nitrogen fertilizer of choice; high analysis (46% nitrogen by weight), easily transportable, and easy to apply in developing countries where more sophisticated liquid-based delivery systems are unavailable. It is not subject to the same shipping, handling and storage regulations which have restricted ammonium nitrate’s use as a fertilizer.

Urea consumption

Because 80% of urea consumption is for agricultural uses, particularly for growing staple nitrogen-hungry cereal crops such as wheat, maize and rice, farm economics have a major impact on urea demand. Urea consumption has tended to increase at an average growth rate of about 3% year on year, driven by increasing populations in the developing world, and increasing wealth of consumers driving a preference towards diets richer in meat, which requires more grain to support it. According to figures recently released by the USDA, the US is looking at a record corn planting this year, and corn and wheat prices are expected to be supported by tight inventories, down 8% on last year for corn and 16% for wheat.

However, while the US applies a considerable amount of urea, there is also demand for direct application ammonia, DAP, UAN and a variety of other fertilizers. Europe and the FSU has a heavy reliance on ammonium nitrate and calcium ammonium nitrate. As a result, and as can be seen in Table 1, two countries have come to dominate urea consumption; India and China. Between them they represent 50% of all urea consumption, and fertilizer policy and domestic developments in India and China continue to have a major impact on the urea market.

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Making syngas underground

Summary

Since Nitrogen+Syngas last reported on underground coal gasification (UCG) in 2010, just two years ago, things seem to have moved very quickly indeed. In this article we review progress on commercialisation of UCG.

Abstract

Several years of high oil prices have driven people to take a fresh look at a variety of other ways of producing energy, as well as potential alternative feedstocks for chemicals. Coal retains one of the largest shares of global energy production, but has faced increasing environmental scrutiny due to its large carbon dioxide emissions relative to other fossil fuels such as natural gas. For a while, at the start of the previous decade, high oil and gas prices nevertheless encouraged considerable interest in coal as a feedstock, but since then the interest has waned, especially in the US, where the shale gas boom has lowered natural gas prices to unprecedentedly low levels, and many coal projects have consequently become less attractive and fallen by the wayside. However, this is not the case all over the world. China, which uses coal for 90% of its energy supply, has continued to forge ahead of the rest of the world in using coal for a variety of uses, from methanol to synthetic gasoline via Fischer Tropsch production (CTL) and even synthetic natural gas. Many other places around the world, from Europe to India, South Africa, Vietnam and Indonesia all have large coal reserves suitable for such use.

Coal gasification has been seen as one of the potential ways around coal’s shortfalls. It has been sold as a relatively cleaner technology, since it is much easier to remove and collect by-products, including carbon dioxide, lending itself to carbon capture and storage (CCS). Is also, however, also an expensive route to syngas, since solid fuel handling and processing and gasification sections must be added on to the front of any chemical or power plant. Furthermore, CCS remains an experimental and relatively untested technology, with the only successful applications involving re-injecting CO2 into oil wells for enhanced oil recovery (EOR), severely limiting the number of suitable sites.

Underground coal gasification (UCG) offers the possibility of overcoming these limitations, by gasifiying the coal in-situ in the ground, removing the need for expensive coal processing sections. Not only is it more efficient in producing syngas, it is also a more efficient way of using the coal, and the carbon dioxide produced is already contained and ready for sequestering.

Although there has been experimentation with UCG dating back to the Soviet Union in the 1930s, early trials met with very mixed success. Syngas produced was poor and variable, and in the US during trials in the 1970s and 80s, contamination of local ground water was blamed on the bores. As a result UCG gained a poor reputation and was largely shelved. It has been the rise of new seismic and drilling techniques, often connected with unconventional gas recovery (coalbed methane, shale gas etc), as well as computer modelling and process control advances which have encouraged a fresh look at the technique.

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Plant Manager+ Problem No. 12 Oil fouling of the high pressure stripper in a urea plant

Summary

The efficiency of the high pressure stripper is a very important parameter in the optimum operation of any urea plant. Fouling of the HP stripper can reduce the efficiency and oil is a typical cause of fouling. Oil can originate from, for example, oil seal systems of high pressure reciprocating ammonia and carbamate pumps and carbon dioxide compressors. Oil can easily cause fouling of the liquid distributor system in the top of the HP stripper (where small holes are present) as the oil can become thick due the stripping of the light components. What are the best methods of solving oil fouling problems and cleaning the HP stripper?

Abstract

Mr Malik Sohail

of Agritech Ltd in Pakistan introduces a very interesting practical problem that has a big impact on the performance of a urea plant We have a TEC ACES plant with a HP stripper of Stamicarbon design. There has been a problem with stripper efficiency and when the ferrules were opened during a
shutdown it was found that 150+ tubes (about 10%) had oil in the stripper bottom. The ferrules are OK. No blockage of holes was observed but there was evidence of pitting. The oil consumption at the NH3 feed pump was high before the shutdown and the HP stripper bottom temperature was on the high side with high NH3 slippage.
oil fouling in the high pressure stripper:

I would like to ask the following questions:

l How can the oil be removed?

l What are the possible causes of it?

l What procedure should be used to wash the stripper tubes?

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