Ammonia Combustion: Energy Without Carbon

Ammonia (NH₃) is a promising compound increasingly seen as an energy carrier in the transition to a low-carbon future. What makes ammonia unique is that it contains no carbon atom. Therefore, no CO₂ is produced during combustion, making it an interesting alternative to traditional fossil fuels. Additionally, ammonia has high energy density per unit volume, is relatively easy to store and transport, and can be used both directly and indirectly in various applications within the energy and industrial sectors. 

The combustion of ammonia proceeds according to the following reaction equation:

4NH₃ + 3O₂ → 2N₂ + 6H₂O

This exothermic reaction produces nitrogen gas and water vapor, along with a significant amount of heat. This makes ammonia a potential fuel source for applications where direct combustion is required, such as in combustion engines, turbines, or industrial furnaces. 

Advantages of Ammonia Combustion:

• No CO₂ Emissions: Complete combustion produces only nitrogen gas and water vapour, with no carbon emissions. This makes it a valuable option in the pursuit of CO₂neutrality. 
• Use as a Hydrogen Carrier: Ammonia can be cracked at high temperatures, releasing nitrogen and hydrogen. The hydrogen can then be used as a clean fuel. This approach makes ammonia an efficient way to store and transport hydrogen. 
• Storage and Transport: Ammonia is liquid under relatively mild pressure and temperature conditions, which facilitates easy transport as compared to hydrogen. 
• Safer Combustion: Although ammonia is toxic, the risk of explosive combustion is lower than with hydrogen, making safety management easier 

Applications of Ammonia as a Fuel

The unique properties of ammonia make it suitable for multiple applications: 

• Power Generation: In gas turbines or combustion engines, ammonia can be used as an alternative fuel. The technology often requires modified ignition and afterburning to limit NO_x emissions. 
• Shipping: Ammonia is being investigated as a maritime fuel due to its high energy density and potential for emission-free sailing. 
• Hydrogen Production: ammonia is converted to hydrogen through thermal cracking, which can then be used in fuel cells or industrial processes. 
• Industrial Processes: ammonia can serve as a fuel or hydrogen carrier in sectors such as steel production etc.

Challenges in Ammonia Combustion

Despite the advantages, there are also important concerns:

• NO_x Emissions: At high temperatures, nitrogen oxides (NO and NO₂) can form. These gases are harmful to health and the environment. It is therefore essential to continuously monitor and control NO_x emissions, for example with a good de NO_x installation.
• Corrosion: Due to the presence of water vapor in the flue gases, materials can corrode more quickly, requiring suitable material choices in the design of combustion installations.
• HCN Formation with Additives: Adding methane (CH₄) to stabilize or improve combustion can produce hydrogen cyanide (HCN), requiring additional monitoring.

Analysis and Monitoring: Essential for Safe Application

For the safe and efficient application of ammonia combustion, high-quality measurement solutions are indispensable. Ravebo provides a complete package of measurement systems, including:

• FTIR Analysis (e.g., GT6000 Mobilis): This technique allows multiple gases to be monitored simultaneously, including nitrogen oxides, HCN, and ammonia. This system is available as a portable or stationary (QAL-certified) solution.
• Oxygen Measurements: The oxygen content in the combustion air is a critical parameter. Oxygen measurements help to optimally control the combustion process and limit NO_x emissions.

Ravebo offers solutions on both laboratory and industrial scales. This allows customers to accurately control and optimize the combustion of ammonia, which not only provides environmental benefits but also leads to a safer and more efficient process.

Conclusion

Ammonia combustion is a promising technology in the energy transition, thanks to its high energy density, the absence of CO₂ emissions, and versatile applications. At the same time, controlled combustion of ammonia requires attention to NO_x emissions, safety, and corrosion. With the right analysis techniques and monitoring equipment, such as those provided by Ravebo, these challenges can be effectively managed. Thus, ammonia contributes to a cleaner and more sustainable energy supply.