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Publication > Issue > Articles

Biomass as a feedstock

Summary

Nitrogen & Syngas takes a look at current processes and projects for producing fuels from the gasification of biomass to syngas.

Abstract

 

 

 

Gasification offers a more flexible way of using biomass to produce fuels and chemicals than biological fermentation methods and can make use of plant waste and non-food crops. However, it brings with it its own set of issues.

 

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The global market for UAN

Summary

Andrea Valenti of Integer Research Ltd looks at the world market for urea ammonium nitrate (UAN), and how the start-up of the new Methanol Holdings Trinidad Ltd plant in Trinidad has impacted upon it.

Abstract

he global UAN market was has been evolving over recent years due to a number of factors. First the market was rocked by the economic crisis which began at the end of 2008 and continued through 2009, which caused UAN consumption to drop in most countries. At the same time, several major producers in Central and Eastern Europe were forced to fight for market share as they were hit by major increases in production costs. Finally, the emergence of Trinidad as a major UAN exporter in 2010 increased export competition. Integer has published a comprehensive study on the global UAN market including detailed data on demand, supply by company and country, trade, production cost economics and pricing, and a 10 year forecast. This article draws on the findings of the study.

Until 2009, the world UAN market had been growing steadily, reaching a peak of nearly 18 million tonnes in 2008 according to Integer estimates. The economic crisis led to a sharp reduction in UAN demand in most markets, and a reduction in nitrogen demand in general. In 2009, world UAN demand dropped to around 14 million tonnes, the lowest level since the beginning of the 2000s. The US, by far the biggest UAN market, shrank by an estimated 2.0 million tonnes year-on-year in 2009. Most UAN markets have rebounded strongly in 2010, with the global total estimated to have reached 15.5 million tonnes in that year, with the US market growing strongly.

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Ammonium nitrate regulatory update

Summary

Continuing use or rather misuse of ammonium nitrate in terrorist incidents worldwide is driving ever-more restrictive legislation in many countries around the world.

Abstract

The bomb blast in central Oslo on July 22nd, detonated by Anders Brevik before his killing spree on Utoya Island, was caused an ammonium nitrate-based device, and is believed to have been produced from AN fertilizer which he purchased completely legally. Coming just two weeks after a series of bomb attacks in Mumbai, also using ammonium nitrate, and a continuing bombing campaign in Pakistan and Afghanistan using calcium ammonium nitrate, it has focused the minds of regulators around the world, and prompted a new round of legislation seeking to tighten controls on the use of AN.

As reported in this magazine in 1996 (‘Ammonium nitrate on trial’, Nitrogen 219, Jan/Feb 1996, pp15-18), the April 1995 Oklahoma City bombing, which killed 169, itself following on the heels of the World Trade Center bombing of 1993, also prompted a similar round of legislation, and there was even speculation (‘The changing interpretation of liability law’, Nitrogen 221, May/Jun 1996, pp23-26) that ammonium nitrate as a fertilizer faced the ‘death of a thousand cuts’, with restrictions gradually piling upon each other until it was no longer viable as a fertilizer. Many countries, including Germany, Ireland, China, the Philippines and Colombia, have already banned fertilizer grade AN, and it is hard in the present climate to foresee anything but a slow decline into what amounts to a ban on its use outside of the explosives industry.

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Reducing N2O emissions from

Summary

With the introduction of a new secondary catalyst and additional technical services, based on its partnership with INS, Hereaus now offers a more comprehensive technology package for N2O reduction. The new catalyst has shown long-term stability and good performance in several nitric plants. Secondary catalyst systems can be designed for all typical process conditions. The absence of precious metals and harmful elements in the new secondary catalyst makes commercial handling easy. Thorsten Keller of Heraeus Materials Technology GmbH & Co. KG describes recent developments and technology achievements.

Abstract

Over the last 20-30 years, the necessity to reduce the emission of greenhouse gases has raised public awareness all over the world. N2O with a global warming potential 310 times larger than CO2 is a gas that has a significant impact on the greenhouse effect. Due to this high global warming potential it is estimated that about 10% of all greenhouse gas emissions result from N2O1. Of the major sources of N2O emissions, the chemical industry and the agricultural sector make up the largest portion. While agricultural N2O emissions are difficult to reduce due to their low concentration, it is typically easier to reduce industrial emissions as they appear in higher concentration from specific plants. Nitric acid plants are now the largest N2O emission source since the N2O emissions from adipic acid production were reduced significantly about ten years ago.

Since then the emission of N2O from nitric acid plants has moved more into the focus of the greenhouse gas discussion2,3. Plant and catalyst suppliers have been looking for ways to reduce the emission of N2O. Nowadays three methods are applied to reduce N2O emissions:

  • Special catalyst gauze packs that generate less N2O (primary abatement)
  • Additional catalyst directly downstream from the gauze pack (secondary abatement)
  • Additional catalyst in the tail gas section (tertiary abatement)

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Emissions control from AN prilling towers

Summary

Environmental regulations dictate that a cleaning system is required to treat the dust and ammonia emissions from ammonium nitrate prilling towers. M. Skorupka, C. Kawalec, and B.Koletka of PROZAP Engineering Ltd discuss the advantages of the PROZAP AN Cleaning Unit, which is suitable for both new and existing plants, complies with existing and future emissions regulations, can be used to treat large volumes of gas and has a low pressure drop system that results in substantial energy savings.

Abstract

Most of the ammonium nitrate plants in operation around the globe are relatively old and, in order to conform to current environmental regulations, require retrofitting of emission control systems to remove dust and ammonia. Naturally, new ammonium nitrate plants should also be equipped with pollution abatement systems in order to comply with environmental regulations. The investment and running costs resulting from such installations differs radically depending on the equipment used and technology applied. Flexibility, efficiency and low power consumption are the main factors which should be considered in the selection process of an emission control system for an ammonium nitrate plant. PROZAP’s AN Cleaning Unit is one of the few pollution abatement systems which can be retrofitted in both old and new AN plants with minimal burden on their economical viability.

AN prilling tower emissions

The exit air from ammonium nitrate prilling towers contains AN dust and ammonia in quantities that exceed current regulations for environment protection. The air also contains gaseous ammonia in quantities which exceed regulations in most cases (Table 1).

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Flexibility is key to better economics

Summary

Achieving high performance in a nitric acid plant requires a catalyst system that meets the specific needs of each individual plant. Knut Burchard of Umicore AG & Co. KG examines the cost drivers and evaluates their economic impact. Thanks to it's unique production technology, Umicore's MKSprecise catalyst system can tailor the configuration of each gauze layer in the catalyst pack to maximise economic benefits, according to its alloy, wire diameter and knitting type, in order to optimise ammonia consumption, reduce PGM losses and maximise economic benefits.

Abstract

For the most efficient performance of the ammonia oxidation process it is important that the catalyst system adapts to the precise needs of each individual plant. For catalyst producers it is, therefore, advisable to attain the highest possible flexibility for all the gauze parameters: structure, alloy, and wire diameter.

Only with this adjustability, layer by layer, is a catalyst capable of taking care of these singular needs of individual plants. It must accurately adapt to the given parameters which result in lowest stable ammonia consumption, and low PGM losses and therefore generates the highest possible economic benefit.

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The chemistry within your catalysts, part 4: Ammonia synthesis

Summary

The synthesis of ammonia directly from its elements was first discovered by Haber over 100 years ago. Since this initial discovery the ammonia manufacturing process has improved significantly, however to this day the catalyst used, and the route of catalyst manufacture, remain almost the same. In this final article of the series, P.V. Broadhurst, M.D. Lunn, K. Young, R.M. Ward and F.E. Lynch of Johnson Matthey Catalysts discuss the ammonia synthesis reaction and how understanding and control of catalyst composition and chemistry can give rise to catalysts that remain active in service for up to 20 years.

Abstract

In the late 19th and early 20th centuries it was recognised that an increasing world population would require greatly increased amounts of nitrogen fertilizers far in excess of those available from natural sources. From 1908 an intensive search for a catalyst that could be used for the production of ammonia from hydrogen and nitrogen was begun by Haber and continued at BASF by Bosch and Mittasch1.

Iron-based catalysts were initially discounted as possible options due to their rapid deactivation during testing in early studies. A more exhaustive study of the catalytic materials osmium, uranium and uranium carbide showed that these were superior in activity and lifetime to iron, and work therefore focussed on these (Fig. 1). However, each of these heavy metal based materials had disadvantages: the cost of osmium and the irreversible oxidation of the uranium species in synthesis gas. Indeed, since then the health and safety aspects of these materials would also prove to be problematic.

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A single solution to four challenges

Summary

Typical problems and challenges experienced by ageing urea prilling plants include high ammonia and dust emissions, low prill quality, competition from granules in the market and demand from farmers for additional nutrients for their crops. In this article, Mark Brouwer of UreaKnowHow.com explains how the Rotoform pastillation system from Sandvik Process Systems meets these challenges and outlines a number of additional benefits.

Abstract

Most of the urea plants around the world operate a prilling tower; the majority of these plants are now several decades old and their capacities have been gradually pushed to about 120 to 130% of their original design capacity. These plants typically face several problems or challenges: high ammonia and dust emissions from the prilling tower, low prill quality, competition from granules in the market and demand from farmers for additional nutrients for their crops. The solution to all four challenges can be provided by Sandvik’s Rotoform pastillation system.

High emissions

In prilling towers the urea melt falls down inside a concrete structure, cooling and crystallising against a large quantity of upward-moving air. In some prilling towers this air flow is created using fans; in others natural draft is used. However while the draft is created, the air becomes loaded with urea dust particles and ammonia, and is typically emitted into the atmosphere from the top of the prilling tower.

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Plant Manager+ No 8: Urea prilling buckets

Summary

Prilling buckets are the oldest technology to form solid urea in a urea plant. In the top of a concrete prilling tower a bucket with numerous holes rotates releasing urea melt droplets, which cool and solidify against the rising air. At the bottom of the prilling tower solid urea prills are collected and sent to storage. It is estimated that about 80% of all urea plants worldwide produce prills. Various designs of prilling buckets are available in the market. What are the design criteria for prilling buckets and what are the experiences with the various designs?

Abstract

 

 

Mr Girish Prakash of Tata Chemicals Ltd in Babrala, India introduces an interesting topic to the Round Table:

What are the differences in technical features and performance of prilling buckets designed for Saipem and Stamicarbon plants? What are the design considerations for the prilling bucket?

Mr Mark Brouwer

of UreaKnowHow.com in the Netherlands replies:

When designing a prilling bucket the following criteria are important:

  • size distribution of the prills should be as even as possible
    maximum usage of the prill tower cross section to maximise
  • heat exchange between prills and air.

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