T. Hentrich and B. Nowak of VDM Metals provide an overview of the development of VDM® Alloy 699 XA, a new generation, metal dusting resistant alloy, available in a wide range of product forms, for demanding applications in the chemical process industry.
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.
To comply with stricter stack emission obligations, industries are required to recover more heat from flue gas and to clean it before it can be discharged into the atmosphere. J. Kitzhofer of APEX Group discusses the challenges and limitations of the majority of current heat recovery systems and reports on a new family of acid resistant tubular and plate-type heat exchangers developed by APEX Group that overcomes these problems. The new heat exchangers are resistant to dew point corrosion. The heat transfer elements are constructed from an acid resistant polymer composite with high thermal conductivity, allowing the design of new trouble-free heat recovery systems and the upgrade of existing systems to meet heat recovery and stack emission targets.
Metal dusting corrosion damage on steam reformers is no longer a major issue in modern methane steam reformer units. Nevertheless, failures related to metal dusting corrosion attack still take place in some specific designs and configurations that are more prone to experience this damage. Poor maintenance or deterioration of insulation components on transition areas might expose metallic surfaces to metal dusting attack. In this article, Dr P. Cardín and P. Imízcoz of Schmidt+Clemens Group describe different case studies, where the end users benefited from the experience of a collaboration to address potential risks and improve plant reliability against metal dusting corrosion damage.
A. Goudarzi of CECO Industrial Solutions discusses the science behind NOx content and how it impacts sulphuric acid producers. In a recent project in Korea, TWIN-PAK® candle filter technology was successfully used to reduce NOx emissions in metallurgical oleum tower production. After installation of the candle filter mist eliminators the plant was compliant with environmental regulations enabling the producer to operate the plant without penalties or shutdowns.
Production has begun at Ivanhoe Mines’ Kakula copper mine in the DRC. The company says that total production for this year is expected to be 80-95,000 t/a of copper in concentrate, with a phase two expansion to 400,000 t/a due to be completed by Q2 2022. Ivanhoe is working with China’s Zijin Mining on the development plan for phases 2 and 3 of the mine, as well as a feasibility study for the Kipushi zinc mine further to the east. Both projects lie close to the DRC’s southern border, with Angola and Zambia respectively. Phase 3 of Kamoa will lift capacity to an anticipated 600-800,000 t/a of copper in concentrate, making it the second largest copper mine in the world after Escondida in Chile. Canadian-based Ivanhoe expects to be digging 3.8 million t/a of ore at Kakula with 6% copper content in Phase 1.
The continuing spread of alkylation technology and the preference for the sulphuric acid route are leading to increased demand for acid in refineries.
Temperature monitoring and measurement of the Claus thermal reactor in sulphur recovery units is one of the most challenging applications in the oil and gas industry. Recently, market interest in unpurged thermocouples has increased with the introduction of new unpurged thermocouple designs utilising alternative thermowell materials such as monocrystalline sapphire.
Are the three “T”s (temperature, turbulence, time) of Claus unit ammonia destruction still meaningful with improved understanding of the thermal reactor? CFD models appear to be adequate at higher temperatures, e.g. 1,200°C, but not at lower temperatures, e.g. 800°C and 1,000°C. A. Keller, on behalf of the Amine Best Practices Group, reviews how meaningful the rules of thumb for Claus unit ammonia destruction really are.
New state-of-the-art equipment has been installed in the thermal stage of one of Europe’s largest Claus SRU units. Substoichiometric firing and a furnace designed with CFD calculations and a modern compact boiler system design based on detailed heat engineering and FEM calculations were key to the success of the retrofit. P. Foith of CS Combustion Solutions reports on the retrofit and how the novel combination of a CS low pressure swirl burner, additional mixing using a VectorWall™ and a new waste heat boiler design achieved the desired results.