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Ammonia production, a cornerstone of global food security, carries a significant environmental footprint. While its output is essential for producing fertilizers to feed billions, it accounts for 1.8% of global CO₂ emissions, releasing around 500 million tonnes annually. The energy demands are also significant, consuming 3% – 5% of global natural gas and 1.8% of total energy output. Finding sustainable, less carbon-intensive production methods is essential for a low-carbon future, given the agricultural sector’s reliance on ammonia.

In an article published in Hydrocarbon Processing magazine, Michael Machuca highlights key strategies for reducing energy intensity and carbon emissions in ammonia production:

• Transitioning to green hydrogen (H₂) as feedstock eliminates the need for steam methane reforming (SMR) units and drastically reduces emissions.
• Implementing carbon capture and storage (CCS) on the CO₂ stream from the SMR and flue gas can capture up to 90% of those emissions. Co-locating with urea plants offers a direct use for captured CO₂.
• Optimizing existing steam methane reforming (SMR) units through better instrumentation and automation can yield incremental but significant energy efficiency improvements.

A diagram of a typical ammonia production unit using SMR to create hydrogen. The actual Haber-Bosch synthesis reaction is only the lower, right-hand quadrant.

Since the majority of ammonia production facilities use the Haber-Bosch process that relies heavily on SMR operations to generate hydrogen (H₂) feedstock from natural gas, the article focuses on outlining a practical and incremental approach to emissions reduction. This approach includes universally applicable solutions with the combined benefits of not only reducing energy use and emissions but also improving safety and decreasing costs. The suggested SMR optimization strategies include the following:

Effective combustion control requires operating as close to the stoichiometric balance as possible. A zirconia sensor used with an oxygen analyzer provides continuous measurement of excess oxygen from any combustion process, including SMR furnaces and boilers.

• Precise Fuel Flow Control: Using coriolis mass flowmeters to improve air-to-fuel ratio and reduce emissions.
• Effective Combustion Analysis: Using oxygen analyzers to maintain optimal oxygen levels in flue gas, as even small excesses can increase emissions significantly.
• Steam-to-Carbon Ratio Management: Using vortex flowmeters to ensure efficient steam usage and prevent safety hazards.
• CO₂ Removal Enhancement: Using coriolis mass flowmeters to monitor solvent flow and optimize CO₂ capture.
• Stage-by-Stage Optimization: Using process gas analyzers at various stages of the SMR process (reformer, shift converters, methanator, amine scrubber) to verify the efficiency of intermediate reactions by monitoring unreacted methane, CO, and CO₂ levels.
• Heat Exchanger Efficiency: Continuous monitoring with appropriate instrumentation, such as temperature, pressure, and flow measurements on both process and transfer fluids, can prevent significant energy waste due to fouling.

When the instruments monitoring heat exchanger parameters send their data to an analytics platform, such as Emerson’s Plantweb Insight application, efficiency is monitored continuously, and maintenance personnel are alerted when fouling may be forming.

Beyond emissions, safety is paramount. Detecting gas leaks (natural gas and ammonia) using acoustic, point, and open-path detectors, and rapidly identifying fires with flame detectors, are crucial. Continuous monitoring for corrosion using ultrasonic metal thickness sensors in critical areas such as the CO₂ removal stage enhances plant safety.

While green hydrogen and CCS offer substantial benefits, their widespread implementation faces challenges related to availability and infrastructure. However, the SMR operational improvements discussed in the article offer immediately applicable solutions that can simultaneously enhance sustainability and safety while reducing costs. Partnering with automation experts is key to implementing these solutions effectively.

Read the article for more information on how these advancements are vital for ensuring a sustainable future for ammonia production and the global agriculture it supports.

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