HAZID techniques for green ammonia plants

GREEN AMMONIA

HAZID techniques for green ammonia plants

Risk analysis tools such as hazard identification (HAZID), is often a first step in broader risk management and is especially valuable for green ammonia, where new technologies and processes introduce novel risks. This article explores various aspects of HAZID, from the basics of hazard identification to unique considerations specific to green ammonia facilities.

Hazard identification (HAZID) is a risk analysis tool used for early identification of potential hazards and threats to provide input to project development decisions. This leads to a safer and more cost-effective design with less chance of later design changes and cost penalties. HAZID predominantly addresses the hazards outside the envelope of the process equipment, whereas hazard operability (HAZOP) studies are concerned with deviations arising within process equipment and is used to identify abnormalities in the working environment and pinpoint the root causes of the abnormalities.

In the context of green ammonia production, thorough HAZID studies can be used to recognise unique risks associated with green ammonia, and implement best practices and safety standards to mitigate these risks.

The key objectives of HAZID studies in green ammonia plants are:

• Identify potential hazards: Recognise sources of risk related to ammonia synthesis, renewable energy integration, and storage.
• Assess likelihood and consequence: Evaluate how likely each hazard is to occur and the potential impact it could have on safety, operations, and the environment.
• Propose mitigation measures: Recommend preliminary actions or design modifications to minimise risks before proceeding with detailed engineering.
• Facilitate regulatory compliance: Support adherence to safety regulations, industry standards, and best practices by identifying all potential hazards and addressing them early.

Unique considerations in green ammonia HAZID studies include:

• Variable power supply: Renewable energy sources are inherently variable. This variability can create instability in energy supply, impacting ammonia synthesis and potentially leading to operational hazards.
• Electrolyser risks: The electrolysis process, critical in green ammonia production to produce hydrogen from water, introduces risks such as high voltages, high-pressure hydrogen, and potential leaks. Hydrogen, as a flammable and small molecule, is more challenging to contain.
• Water supply and quality: Green ammonia requires significant amounts of purified water for hydrogen production, and interruptions or contamination in water supply can impact operations and introduce risks.
• Battery storage: If battery systems are used to manage energy storage and distribution, they introduce specific hazards, including fire risks, toxic emissions, and thermal runaway events.
• Integration challenges: The integration of renewable energy systems with ammonia production must be carefully managed to prevent failures due to synchronisation issues or control system mismatches.

HAZID study for green ammonia plants

There are several steps to conducting a HAZID study for green ammonia plants.

Define the scope and objectives: Define the scope of the HAZID study to include all areas and systems in the green ammonia plant, from renewable energy input to ammonia synthesis and storage. Establish clear objectives to address unique risks associated with green ammonia production, considering both conventional ammonia hazards and new risks from renewable energy integration.

Assemble a multidisciplinary team: A successful HAZID study requires a team with diverse expertise, including process engineers, renewable energy specialists, control systems engineers, and safety professionals. In green ammonia projects, involving personnel experienced in renewable energy and hydrogen safety is essential.

Systematic Hazard Identification: Using checklists, brainstorming sessions, and structured techniques like “What-If” analysis, the team identifies potential hazards for each part of the plant.

Energy supply and management: Analyse hazards associated with energy variability, storage, and distribution systems.

Electrolysis units: Examine potential hydrogen leaks, high-pressure system failures, and risks associated with electrolysis operations.

Ammonia synthesis loop: Identify hazards in the ammonia synthesis loop, including temperature, pressure, and catalyst-related issues.

Storage and handling: Consider hazards related to ammonia storage, transport, and handling, especially concerning emergency shutdowns and potential leaks.

Risk assessment and ranking: Each identified hazard is assessed based on its likelihood and consequence. This ranking helps prioritise high-risk areas, allowing for a focused approach on mitigating the most critical risks. The aim is to determine if risks can be reduced to ALARP (As Low As Reasonably Practicable).

Develop mitigation strategies: For each high-priority hazard, propose mitigation measures to either eliminate or reduce the risk.

Documentation and review: Document the findings, mitigation measures, and any recommendations for further risk assessment or design review. Conduct a review of the HAZID findings to ensure all hazards have been addressed and that mitigation measures are reasonable and effective.

Best practices for HAZID studies

It is important to conduct HAZID early in the design phase to allow enough time to incorporate necessary changes. As green ammonia technology evolves, continuous hazard reviews ensure that new risks or process changes are effectively managed. Regular training should be provided to the HAZID team, focusing on new technologies and evolving safety standards in renewable energy and ammonia production. Lessons learned from similar projects and case studies can be used to understand what has worked well and what has posed challenges. Adhere to industry standards and guidelines for ammonia and hydrogen safety, including updates for renewable energy integration.

Synthesis gas compressor fires due to gas leaks

Synthesis gas compressor fires due to gas leaks pose significant safety and operational risks in ammonia plants. Based on the incidents reported by the conventional ammonia industry, several key conclusions can be drawn.

Gas leaks leading to fires often result from mechanical failures, such as disconnected instrument tubes, failed valve components, or compromised oil seals. Even small components like a missing rivet can lead to catastrophic events. Once a leak occurs, fires can spread quickly, causing extensive damage to compressors, buildings, and auxiliary equipment. The high-pressure, hydrogen-rich gas creates intense jet fires that are challenging to extinguish.

Early detection of gas leaks is crucial. Implementing comprehensive gas detection systems, regular inspections, and proper maintenance procedures can help prevent incidents or mitigate their severity. Having well-trained personnel and proper emergency response procedures is essential. This includes rapid plant shutdown protocols, effective firefighting strategies, and clear evacuation plans.

Compressor room fires can result in significant costs, including equipment damage, production losses, and implementation of additional safety measures. Proper design of compressor rooms, including adequate ventilation, fire suppression systems, and strategic placement of critical equipment, can help limit fire spread and damage.

Careful attention to start-up and shutdown procedures, as well as maintaining proper oil sealing systems, is critical to prevent gas leaks during transient operations. Regular inspections of all gas-carrying components, including small-bore piping and manual valves, are necessary to identify potential failure points before they lead to incidents.

Each incident provides valuable lessons for improving safety measures, operational procedures, and equipment design across the industry. Sharing these experiences is crucial for preventing similar occurrences in other facilities.

By addressing these aspects comprehensively, ammonia plant operators can significantly reduce the risk of synthesis gas compressor fires and improve overall plant safety and reliability.

By integrating preventive, mitigation, and administrative safeguards, the risk of syngas loss at the compressor can be effectively minimised. Gas detectors, automated isolation systems, and robust maintenance programs enhance safety and operational reliability. These measures work together to ensure early detection, containment, and controlled response to hazardous events.

Conclusion

HAZID studies remain a cornerstone of safety management in ammonia plants, regardless of whether the ammonia is green, grey, or brown. The hazards associated with ammonia production are constant, and comprehensive HAZID frameworks ensure that causes, consequences, and safeguards are systematically addressed. By fostering a culture of safety and leveraging lessons learned, organisations can enhance risk management, ensuring a safer and more sustainable production environment.

This article is based on the certified operator training programme by Fertilizer Academy, presented at the Nitrogen+Syngas 2025 Expoconference, Barcelona, 10 February 2025.