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The Bulgarian fertilizer industry

Summary

Dr Kiril Petrov* looks at the recent troubles of the Bulgarian nitrogen fertilizer industry, and presents an up to date overview of the four major companies as the government attempts to find foreign buyers.

Abstract

The main products manufactured in the fertilizer sector in Bulgaria are ammonia, ammonium nitrate, urea, triple superphosphate (TSP), liquid nitrogen fertilizers (UAN) and ammonium sulphate. Complemen­tary product groups include caprolactam, carbamide, formalin, and technical gases. Fertilizer production is mainly exported to the Mediter­ranean, Balkan countries, Middle East, North America, West Europe, South America and Africa. In 1998, 62.9% of the ammonium nitrate, 91.8% of the urea, 97% of the ammonium sulphate and 96.9% of the TSP production were exported. The remainder was sold on the domestic market.

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High-efficiency mixing from Koch-Glitsch

Summary

Efficient oxidation of ammonia during nitric acid production is assisted by effective mixing of the reactants before they reach the catalyst gauze. Greg J. Archembeau of Koch-Glitsch, Inc. introduces his company's static mixing and flow conditioning technologies that are designed to increase efficiencies and prolong catalyst life by ensuring that the catalyst gauze receives a comprehensively mixed feed gas with an even velocity profile across the face of the gauze.

Abstract

Many nitric acid producers have been unable to achieve optimum rates of ammonia conversion or maximum catalyst life. These problems have resulted from inefficient mixing of ammonia and air, followed by poor distribution of the mixture to the platinum-based catalyst gauze inside the ammonia converter. The end result has been decreased run time and lower product yield. The Koch-Glitsch Mixing and Reaction Technology Group supplies solutions for these common problems in the form of our static mixing equipment and flow conditioning devices. These technologies have been proven in industry worldwide and installed at twenty installations over the last five years.

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Special materials for nitric acid

Summary

The materials used in nitric acid plants need to be able to withstand ­extremely demanding conditions due to the acid's highly corrosive nature. Nitrogen & Methanol looks these materials and focuses on the requirements for special steels in nitric acid plants.

Abstract

Nitric acid is very corrosive. Therefore, special corrosion-resistant materials are needed in nitric plants. The specific demands made of the materials used to construct nitric acid plants have led to the materials being modified for their particular uses. Special precautions need to be made to ensure that the materials have the right properties. Although advances have been made in materials for nitric acid plants, good process design as well as careful manufacture of equipmens need to be guaranteed to ensure successful plant operations.

Almost all nitric acid production is via the catalytic oxidation of ammonia. The oxidation can be carried out at single pressures of 3-5 atm or 8-13 atm, or through dual-pressure processes that normally use medium-pressure oxidation and high-pressure absorption stages. The processes have three steps:

  1. The Oxidation of ammonia to nitric oxide at high temperatures, over a platinum-rhodium catalyst: 4NH3 + 5O2 -> 4NO + 6H2O
  2. Further oxidation of nitric oxide to nitrogen dioxide: 2NO + O2 <-> 2NO2
  3. Absorption of nitrogen to form nitric acid: 2NO2 + O2 + H2O -> 4HNO

 

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Optimizing catalyst pack design for ammonia oxidation

Summary

Efficient oxidation of ammonia is a key part of economic nitric acid production. The catalysts used to promote the oxidation reaction contain precious metals and are, therefore, expensive. Louis du Chatelier* of Engelhard-CLAL explains how his company's Optimized Mass Transfer pack has been developed to maximise ammonia conversion while limiting precious metal losses by using several types of catalyst gauze in one pack.

Abstract

The oxidation of ammonia to nitric oxide is the first step in the manufacture of nitric acid from ammonia. The reaction is carried out at high temperatures over a platinum-rhodium catalyst gauze.

In the early 1970s, Roberts & Shah investigated ammonia oxidation and considered that the reaction’s kinetics were limited by the rate of mass transfer through the catalyst gauze pack, as the speed of reaction was extremely high. The company developed a model using an analogy with heat transfer calculations which gave a good correlation to the results found in practice (see Fig.1). At this time, woven gauzes only were available. In the 1990s, the Roberts & Shah concept is still the basis of catalyst bed sizing despite the introduction of new types of gauzes such as knitted and Bispin® gauzes.

Mass transfer is the effective determining factor for ammonia oxidation. In atmospheric plants, much greater amounts of precious metals are required than in high pressure plants due to the poor mass transfer experienced at lower pressures. If catalyst gauzes can be design­ed to maximise the mass transfer then the requirement for precious metals will be reduced.

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World scale, world class

Summary

Abu Qir Fertilizers Company's new ammonia-urea complex outside Alexandria, built by Krupp Uhde GmbH, went into operation late last year and was formally inaugurated on 25 February 1999. Alexander More was invited to take a look round the plant.

Abstract

The commissioning of Abu Qir III, the new ammonia-granular urea complex of Abu Qir Fertilizers Company (AFC) outside Alexandria in Egypt, marks the latest stage in a long period of growth and success for the company. The site now comprises the original Abu Qir I ammonia (330,000 t/a) and prilled urea (512,000 t/a) complex, commissioned in 1979, the Abu Qir II ammonia (330,000 t/a), nitric acid and ammonium nitrate (792,000 t/a) complex, commissioned in 1991, and now the new ammonia-granular urea complex described in detail in this article.

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Africa – a continent in transition

Summary

North Africa has long been a major producer of methanol and nitrogen fertilizers from the rich gas fields of Egypt, Libya and Algeria, but activity in sub-Saharan Africa has always been circumscribed by war and political instability. However, in the past decade the prospects for the region have changed. Oil and gas exploration is now proceeding rapidly and new finds are being discovered all the time.

Abstract

Africa has not yet managed to make a clean break with its past. Ethiopia and Eritrea remain locked in a debilitating war. The war in the Congo, formerly Zaire, has already sucked in Rwanda, Burundi and Nigeria. Angola’s and Sudan’s civil wars continue with no sign of a let-up, and following the failed UN intervention in Somalia, that country has gone from bad to worse.

Since the end of the Cold War, Africa has had the benefit of no longer being an ideological battle ground. However, it has also slipped down the international agenda, amid US attempts to disengage from the continent by encouraging regional peacekeeping forces to police Africa’s trouble spots. The failure of the West African Ecomog force, led by Nigeria, to solve Sierra Leone’s problems, followed by that country’s descent into anarchy, offers a salutary warning of the political risks that still remain in the region. Finally, the burden of outstanding debt still casts a long shadow, although there are at last some signs of movement on this issue.

However, the news is not all bad. South Africa has made a relatively smooth shift to majority rule, while countries like Mozambique and Namibia – and now hopefully Nigeria – have managed the transition to civilian rule with a minimum of disruption, and offer some hope for the region as a whole. With increasing political stability has come increased international oil and gas exploration activity, which is beginning to offer the promise of increased government revenues and, perhaps, the possibility of developing domestic fertilizer industries in a region where farmers’ use of nutrients to replenish soils has been patchy or non-existant, and where increased crop yields are desperately needed to feed rapidly growing populations.

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