u Process efficiency – technology choice: The cost of the ammonia feed is the primary cost factor in producing hydrogen from ammonia cracking. Therefore, it is essential to choose the most efficient and optimised technology available. Any losses or inefficiencies will directly affect the hydrogen yield and result in extra energy-related costs. It is important to optimise the ammonia cracking process to minimise losses and maximise hydrogen yield. Topsoe’s technology, H2Retake (see Figure 2 ), for instance, utilises the energy input in the side-fired ammonia cracker to drive the decomposition reaction and effectively preheat and evaporate the raw feed with minimal wastage. The high efficiency is achieved through a streamlined ammonia cracking design, optimised heat and off-stream integration, and careful catalyst selection, resulting in an impressive energy efficiency of 96%. v Catalyst selection: The choice of catalyst for ammonia cracking is crucial. Selecting a highly active, stable catalyst with high strength and minimum pressure drop is essential for an effective and energy-efficient process. Understanding the performance and durability of the catalyst under different operating conditions is important to ensure optimal conversion rates and minimise catalyst degradation. w Safety – location and permitting: Ammonia is both toxic and corrosive but also a long-standing and widely used substance. As a result, well- established safety procedures ensure proper safety measures are in place for the storage, handling, and transportation of ammonia. Assessing and implementing appropriate safety protocols, materiality of infrastructure, and training is critical to mitigate any potential risks associated with ammonia handling.
Haber-Bosch synthesis. This process involves reacting hydrogen with N 2 under high pressure and temperature in the presence of a catalyst. The resulting ammonia is then liquefied and stored for transportation. Transportation of ammonia: Ammonia is transported using existing infrastructure such as pipelines, ships, or trucks, as it is already produced and transported in large quantities on a global scale. The ammonia can be stored and transported as a liquid at -33°C, making it easier and safer than transporting hydrogen, which requires high-pressure or cryogenic storage. Conversion of ammonia back to hydrogen: At the destination, the stored ammonia is converted back to hydrogen through ammonia cracking. The process begins by heating and evaporating liquid ammonia, which is initially at -33°C. Once vaporised and heated to the reaction temperature, the ammonia is directed to the cracking section where ammonia cracking occurs. In ammonia cracking, the ammonia vapour is further heated to high temperatures in the presence of a catalyst. This causes the ammonia to decompose into N₂ and H₂ according to the reaction:
2NH₃ D N₂ + 3H₂.
The hydrogen produced from ammonia cracking can be used for various applications, such as in fuel cells, natural gas replacement, and in various chemical processes. This hydrogen can be stored, distributed, and utilised in the same way as hydrogen produced from other sources. The critical areas when choosing ammonia cracking as a new business opportunity are:
Renewable ener gy
Power
Green ammonia
H Retake Ammonia Cracker
Ammonia storage
Transport
Hydrogen
H
Natural gas
Blue ammonia
Figure 2 Topsoe’s H2Retake technology
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