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Magazine: 392 Nov-Dec 2024

Making RFNBO compliant ammonia competitive

One of the key challenges of producing RFNBO (renewable fuels of non-biological origin) compliant ammonia is managing the intermittency associated with renewable energy sources for hydrogen production. Furthermore, the additional costs associated with managing this intermittency can be significant. In this article, Dr Solomos Georgiou of AFRY Management Consulting explores those additional costs as well as potential ways to achieve cost savings and make RFNBO-compliant ammonia production competitive against conventional ‘grey’ ammonia.

Introducing ammonia flow-induced corrosion

In recent years, extensive and severe internal attack has been observed of carbon steel equipment and lines in aqua ammonia service at several Yara manufacturing sites across the globe. In all cases, the damage has a distinct flow-accelerated corrosion (FAC) signature which challenges the current understanding of FAC. All features typically observed for this kind of damage mechanism, that seem to be specific to the NH3 recovery section of ammonia plant, are reported. Upgrading the material of construction for this unit, will solve this failure mode, but a leak would potentially generate health and safety problem for the release of ammonia.

Conversion into hybrid ammonia plants

One challenge of a green revamp by stepwise injection of green hydrogen into existing ammonia/urea complexes is to cover the nitrogen demand for the ammonia synthesis while stepwise reducing the front-end load, usually by applying a cost-intensive air separation unit (ASU). thyssenkrupp Uhde GmbH has developed an advantageous concept whereby, instead of an ASU, the nitrogen gap is closed by the introduction of pretreated reformer flue gas back into the ammonia process, with the side effect to also enhance CO2 production.

Political threats loom large

While underlying supply and demand criteria continue to set floors and ceilings for nitrogen and other syngas derived products, political events as ever have the potential to derail all calculations. While much attention has focused on the US election, the escalating crisis in the Middle East continues to have the potential to threaten fertilizer trade in multiple ways. As this issue was going to press, Israel had just launched its retaliatory missile strike on Tehran, on October 26th, the latest in a series of tit for tat attacks between Israel and Iran, in particular an Iranian missile strike on Israel on October 1st. The Iranian government appeared to be downplaying the results as “limited”, but said that it considered itself “entitled and obligated to defend itself”.