Analysing the facts: gas analysis in fertilizer production

Agrochemicals such as fertilizers play a critical role in facilitating the growth of crops and plants. By providing the right nutrients to the soil, fertilizers nurture crops to grow bigger and quicker, ready to be transported to supermarkets and into homes.

Faster-growing and higher-yielding crops are rising in importance because of the rapidly growing global population, which also means the demand for food is growing quickly.

Alongside an increasing population, the agricultural and food production industries face climate pressures; they are expected to reduce emissions and their usage of resources. All of this leads to a call for more efficiency and sustainability within these industries. Fertilizer production is no exception.

As fertilizer production scales up, the role of gas analysis becomes increasingly critical. It delivers three key benefits: safeguarding personnel and surrounding environments, optimising process efficiency, and enabling accurate emissions monitoring to support cleaner, more sustainable operations.

A process built on gas reactions

At the heart of fertilizer production are chemical reactions between gases. This is especially the case when manufacturing nitrogen-based fertilizers, which utilise ammonia (NH₃).

NH3 is a key ingredient in the production of these nitrogen fertilizers, with production using 80% of global ammonia supplies.1 However, to get this active ingredient, several chemical reactions must take place. At the very beginning of the production process, methane (CH₄) is separated into hydrogen (H₂) and carbon dioxide (CO₂) molecules through a reaction with water (H₂O). From here, the H₂ is combined with nitrogen (N₂) to form NH3. However, this process is slightly more complex, as carbon monoxide (CO) and CO₂ are both resulting products of the reaction.

Following the reformers, the feed undergoes a CO shift reaction, which converts the more dangerous gas, CO, to a safer gas, CO₂. From here, the resulting product goes through a CO₂ wash, removing the CO₂ from the feed, leaving N₂ and H₂.

The two pure gases are finally sent through a reactor, where a chemical reaction between them produces the NH₃.

Finally, the production of fertilizer can start. The NH₃ goes through another reactor, where it is combined with CO₂ before being dehydrated to form urea (CH₄N₂O).

Alternatively, ammonia is oxidised with air to create ammonium nitrate, which is used for nitrogen fertilizers.

Throughout all these gas-phase chemical reactions, process composition, purity and safety are paramount. Not only will these ensure process safety, but also the quality of the product.

The role of precise gas analysis

Gas analysis and monitoring allow managers to control processes and monitor the quality of the feed, maintaining consistency throughout the production process. Accurate and continuous monitoring also plays a part in ensuring processes are functioning as efficiently as possible, working to reduce waste by-products and energy consumption, and supporting compliance with local environmental regulations.

Several types of gas analysers are typically used in the production of agrochemicals, such as fertilizers, specifically at the beginning of the process where ammonia is being made.

During this process, rugged liquid and gas analysers are placed before and after several of the stages, such as the reformers, the CO shift, the CO₂ wash, and before the ammonia and urea reactors.

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