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Tag: Casale

Nitriding in ammonia converters: behaviour, experience, and solution

The internals of ammonia synthesis converters are generally made of austenitic stainless steel to withstand the harsh operating conditions (high temperature, high pressure and synthesis gas containing hydrogen and ammonia). Since nitriding is the most critical material degradation for the converter internals, Casale has set up a large nitriding analysis campaign. In the last decade, samples of materials operated under different pressures and temperatures and for different time spans have been tested and analysed. The data obtained has been used to increase nitriding knowledge and to establish a correlation to predict nitriding rate to allow the most suitable material and relevant thickness to be selected. L. Redaelli and G. Deodato of Casale report on how this correlation was established and provide valuable insight on this phenomenon and how to predict and control it.

Safe handling and start-up of ammonia synthesis catalyst

Ammonia synthesis catalysts have long lives and catalyst replacement is an infrequent activity. Many people will go through their careers in the ammonia industry without ever having to replace a synthesis catalyst and the infrequent nature of catalyst replacement means that many plants may not have direct experience of this activity. Ammonia synthesis catalyst can present a range of hazards throughout the replacement process, from transport through loading, reduction, start-up, shutdown and discharge, but the good practice illustrated in this article, and collaboration between catalyst suppliers and end users can ensure safe and successful catalyst changeouts.

NOx reduction from steam methane reformers

NOx emissions from chemical processes such as steam methane reforming contribute to air pollution. The chemical industry is required to take steps to lower such emissions. Technology, developed for related industries, can be designed and optimised to reduce NOx emissions from steam methane reformers. Emission control experts can use a combination of modelling and experience to guide plant operators in recommending and designing optimum, sometimes tailor-made solutions. In this article different options are discussed including low NOx burners, selective catalytic reduction, selective non-catalytic reduction and high emissivity ceramic coatings.