Review of Major Chemical Safety Incidents in the Global Carbon Capture Industry

Reyson Dave Dela Cruz, Lady Trinity Enopia, and Michael Saura

Keywords: Carbon Capture Technology, Bowtie Analysis, Incident Data, Barrier-Based Risk Management, Process Hazard Analysis, Process Safety

Abstract. This study focused on the incident analysis and hazard analysis of Amine Absorber and Air Separation Unit (ASU) systems within Carbon Capture Technologies (CCT). The primary objective was review incident data related to CCT, identify associated hazards, and analyze these hazards to propose safety improvements using Bowtie Analysis. Data were collected and categorized by consequence type and operational CCT hazards from various secondary sources, including industry reports and safety databases. The methodology involved a comprehensive analysis using a mix of qualitative and quantitative methods. Findings highlighted a high frequency and severity of incidents related to Amine Absorbers and ASUs, primarily due to leaks, corrosion, overpressure, and mechanical failures. The study underscored the importance of integrating safety incident data and hazard analysis to identify critical safety concerns effectively. Detailed hazard analyses were conducted using Bowtie Analysis (BTA), identifying potential causes, consequences, and existing control measures. In this study, the conclusion highlights the effectiveness of combining incident data with hazard analysis as a robust approach to identifying and analyzing high-risk areas within CO2 capture, particularly in ASU and amine absorber units, which simplifies the analysis and emphasizes these areas as top concerns when conducting Bowtie analysis. Recommendations include utilizing industry incident data, integrating suitable hazard analysis methods, and regulating, investing, and innovating based on the principles of risk-based process safety.

Introduction

Since the industrial revolution, human activities have greatly increased carbon dioxide emissions, contributing to global warming. To combat this, advancements in CCTs over the past two decades have focused on reducing emissions from industrial plants and power generation. These methods—pre-combustion, post-combustion, and oxy-fuel combustion—are vital to meeting global climate goals outlined in the Paris Agreement, aiming to limit temperature rise below 2 °C, ideally 1.5 °C, by cutting emissions from sectors like electricity, transportation, and industry [1].

To date, three CCTs are widely accepted in industrial and power generation plants: post-combustion, pre-combustion, and oxy-combustion [2].

Fig. 1, Block flow diagram of CCT [2]

Post-Combustion. CO2 is separated from flue gasses after fossil fuel combustion in power plants using chemical absorption with amines or physical adsorption onto solid materials. Boilers generate steam for solvent regeneration, while steam turbines convert steam into power [3]. Amine scrubbing is a crucial purification technique, with the CO2-laden solution being regenerated by heating and depressurization [4].

Pre-Combustion. Carbonaceous fuels are gasified with oxygen and steam, producing syngas (H2 and CO). CO2 is separated from hydrogen using methods like wet gas scrubbing before combustion, reducing emissions. Combustion turbines then generate power by burning the fuel in a controlled environment [5]. Physical absorption and adsorption, such as PSA, are commonly used due to their efficiency in handling high-pressure gasses [4].

Oxy-Combustion. Fossil fuels are burned in nearly pure oxygen, producing mainly CO2 and water vapor. ASUs isolate oxygen from air, and Flue Gas Recirculation (FGR) controls combustion
parameters. This method simplifies CO2 capture but requires significant energy for oxygen separation [3, 5]. Membrane separation is particularly useful here, where advancements in materials science have led to high selectivity and durability for post-combustion CO2 separation [6].

CCTs face several hazards, including overpressure, which can lead to explosions if pressure exceeds design limits; overheating, which can degrade materials and cause equipment failure; leaks of CO2 or other gasses, posing safety and environmental risks; corrosion and erosion from chemical reactions and high flow rates, leading to equipment degradation; mechanical failure due to fatigue, stress, or manufacturing defects; and contamination, which can affect the efficiency and safety of the capture process [7, 8].

Understanding and mitigating the common hazards associated with CCTs is essential for optimizing their efficiency and safety, thereby supporting their broader adoption in reducing carbon emissions.

The rise in CCT has also led to more process safety incidents, such as fires and explosions. The growing complexity and scale of operations also increase the risks. There is a significant research gap in summarizing safety incidents and methods to prevent them. Moreover, studies often separate incident analysis [9, 10] and hazard assessment [11, 12], leading to a fragmented understanding of safety risks. The use of incident data refines risk estimates, providing a realistic understanding of potential incident likelihood and severity. Combining incident data with advanced hazard analysis tools is crucial for mapping out causal factors and evaluating existing safety barriers [13]. This approach is believed to improve safety protocols and risk management in carbon capture operations.

The theoretical framework for this study is based on Barrier-Based Risk Management (BBRM), utilizing Bowtie Analysis (BTA). BBRM identifies and maintains effective barriers to prevent or mitigate incidents [14]. BTA maps potential hazards, their causes, consequences, and control measures [15]. Combining risk analysis with actual incident data offers a comprehensive view of process safety risks in CO2 capture processes.

Fig. 2, Bowtie Framework [16]

Methodology

This study combines incident review and hazard analysis in developing safety recommendations for various CCTs.

Fig. 3, Methodology Flow Chart

Data Collection. Incident data were collected for nine types of industrial equipment: Gasifier, ASU, FGR, Boiler, Steam Turbine, Combustion Turbine, Amine Absorber, PSA, and Membrane. Secondary data sources included the Center for Chemical Process Safety, Mary Kay O’Connor Process Safety Center Process Safety Incident Database, National Response Center, US Chemical Safety and Hazard Investigation Board, European Commission’s Major Accident Reporting System, World Health Organization Chemical Incident Reporting System, and the International Association of Oil & Gas Producers.

Data Preparation. The collected data were structured in a spreadsheet and categorized by consequence type and operational hazards. Incidents were categorized by consequence type: explosion, fire, fatality, material release, and others. Additionally, operational hazards were classified as overpressure, overheating, leaks, corrosion and erosion, mechanical failure, and contamination.

Data Analysis. A combination of qualitative and quantitative methods was used. Incidents were aggregated by CCT. Stacked bar graphs, created using Python’s Matplotlib, visually compared operational hazard and consequence distribution across CCT.

Hazard Analysis. High-risk scenarios were subjected to BTA using Bowtie XP software, focusing on high-frequency, high-severity incidents. This analysis identified critical barriers and developed safety recommendations. The BTA involved identifying the top event, listing potential threats, and determining the consequences if the top event occurs [17].

Safety Recommendations. Preventive barriers were defined to prevent the threats from leading to the top event, and mitigative barriers were established to mitigate the consequences [17].

Results and Discussion

Frequency of Total Incidents

Fig. 4, Frequency of Global CCT Safety Incidents by Year

Fig. 4, shows the number of incidents that occurred each year. The highest number of incidents was reported in 2019, followed by 2018 and 2015. The trend is continuously increasing, which aligns with the growth in demand for CCTs. The use of CCTs has been growing steadily as part of global efforts to reduce carbon emissions [18]. The increasing number of incidents correlates with the expanding implementation of these technologies, indicating that as more CCTs are deployed, the potential for operational hazards rises.

Fig. 5, Frequency of Global CCT Safety Incidents by Country

Fig. 5, reveals the number of incidents by country. The USA has the highest number of incidents, followed by China and Canada. Countries with fewer incidents have been grouped as “Others.” These countries are among those with the highest number of power generation and chemical plants utilizing

CCTs and are also the ones highly incentivizing the use of these technologies. USA, China, and Canada lead in the number of operational carbon capture and storage projects, reflecting their significant investment in CCT infrastructure [19].

Fig. 6, Global CCT Safety Incident Distribution by Process Unit/ Equipment Type

It should be, In Fig. 6, Indicates the distribution of process safety incidents across various process unit/ equipment types. The Amine Absorber has the highest incidents at 41.1% followed by ASU accounting for 15.8% of incidents and gasifiers representing 10.5% of incidents. The Amine Absorber, ASU, and Gasifier show the highest incidence rates, reflecting the complex hazardous nature of their operations. The Amine Absorber is prone to leaks and corrosion, ASUs are susceptible to mechanical failure and contamination, and gasifiers face significant hazards from overpressure and leaks. [7, 8, 20]

Analysis of Consequence Types

Fig. 7, Breakdown of Global CCT Safety Incident by Consequence Type

Fig. 7,shows that the ASU and Amine Absorber both exhibit the highest total number of high-severity incidents, with 16 counts each. ASUs are primarily driven by explosions and fires, while Amine Absorbers experience a mix of fires, explosions, fatalities, and material releases. Gasifiers have a high incidence of explosions, with six reported cases, underscoring the critical need for explosion prevention and control. Boilers have a moderate total number of incidents, predominantly explosions, indicating a need for stringent boiler safety protocols. The FGR, Steam Turbine, and Combustion Turbine show lower total incidents but include high-severity events such as leaks, fires, and explosions, highlighting specific areas for safety improvements. In contrast, the PSA and Membrane systems report no high-severity incidents, suggesting that effective safety measures are currently in place.

Analysis of Operational Hazards

Fig. 8, Breakdown of Global CCT Safety Incident by Operational Hazards

Fig. 8,reveals that the Amine Absorber stands out with the highest total number of incidents (18), primarily due to leaks and corrosion and erosion, indicating critical areas for safety improvements. The ASU also shows a high number of incidents (9), with significant contributions from mechanical failures, overpressure, and contamination. Gasifiers have a high total number of incidents (10), with overpressure being the dominant hazard, necessitating enhanced pressure control systems.

Amine Absorbers and ASUs have among the highest number of incidents, necessitating comprehensive safety strategies to address leaks, corrosion, and mechanical failures [21, 22]. The varied hazard profiles of Gasifier, steam turbine, combustion turbine, FGR, PSA, Boiler, and Membrane systems indicate the necessity for a broad and integrated approach to safety management. This analysis underscores the importance of addressing specific hazards in high-incidence equipment while maintaining effective safety measures across all equipment types.

To summarize, the findings reveal that due to the high frequency and severity of incidents, it is crucial to perform a detailed hazard analysis on ASUs and Amine Absorbers. Comprehensive safety strategies are necessary to mitigate explosion and fire risks [21, 22]. Identifying the top hazard categories will allow for more specific analyses and the recommendation of robust safety barriers
[17]. To address these concerns, a BTA was conducted for two specific equipment to identify the potential causes and consequences of hazards, along with the preventive and mitigative measures in place. The scenarios analyzed were: (1) Amine Absorber: Leaks, corrosion and erosion, and mechanical failure leading to fire and (2) ASU: Mechanical failure and overpressure leading to explosion.

Bowtie Analysis for Amine Absorption

Fig. 9, BTA for Amine Absorption Fire Scenario

Fig. 9, shows the BTA for amine absorption fire scenario. The top event for the Amine Absorber is a fire. The first threat identified is leaks, which can be caused by improper sealing or gaskets, valve or pipe failures, and high-pressure operations. Preventive barriers include regular inspections and maintenance, leak detection systems, pressure relief valves, and operator training. The second threat is corrosion and erosion, caused by chemical reactions with amine, high flow rates causing physical wear, and the presence of contaminants. Preventive measures involve using corrosion-resistant materials, regular inspections and maintenance, chemical inhibitors, and flow control measures. The third threat is mechanical failure, which can result from fatigue and stress, inadequate maintenance, and manufacturing defects. Preventive barriers include regular inspections and maintenance, quality assurance in manufacturing, operator training, and the use of high-quality parts [21, 23, 24].

The consequences of a fire include personnel injury or fatality, equipment damage, production loss, and environmental impact. Mitigative barriers for personnel injury or fatality include fire suppression systems, emergency response plans, personal protective equipment (PPE), and evacuation procedures. To mitigate equipment damage, fire suppression systems, secondary containment systems, and emergency shutdown systems are essential. Production loss can be minimized with emergency response plans, redundant systems, and insurance. Environmental impact mitigation includes secondary containment systems, emergency response plans, and continuous environmental monitoring [21, 23, 24].

Bowtie Analysis for ASU

Fig. 10, shows the BTA for ASU explosion scenario. The top event for the ASU is an explosion. The first threat identified is mechanical failure, which can be caused by fatigue and stress, inadequate maintenance, and manufacturing defects. Preventive barriers for mechanical failure include regular maintenance and inspection to ensure mechanical integrity and early detection of potential failures, quality assurance in manufacturing to prevent defects, and operator training to recognize signs of mechanical failure and take appropriate action. The second threat is overpressure, caused by the failure of pressure control systems, blockages or restrictions in gas flow, rapid temperature increases, and improper operation or human error. Preventive measures include pressure relief valves to automatically release excess pressure, regular pressure monitoring to detect and address overpressure conditions early, automated control systems to adjust pressure levels, and operator training to recognize and respond to signs of overpressure [22, 25, 26, 27].

Fig. 10, BTA for ASU Explosion Scenario

The consequences of an explosion include personnel injury or fatality, equipment damage, production loss, and environmental impact. Mitigative barriers for personnel injury or fatality include explosion suppression systems to detect and suppress explosions quickly, emergency response plans detailing responses to explosions, PPE for all personnel, and clear evacuation procedures. To mitigate equipment damage, explosion suppression systems, secondary containment systems, and emergency shutdown systems are essential. Production loss can be minimized with emergency response plans, redundant systems, and insurance. Environmental impact mitigation includes secondary containment systems, emergency response plans, and continuous environmental monitoring [22, 25, 26, 27].

Summary

This study focused on the safety concerns and incident analysis of Amine Absorber and ASU systems within CCT. The primary objective was to analyze incident data, identify common hazards, and propose safety improvements for these specific equipment types. Data were collected and categorized by consequence type and operational hazards from various secondary sources, including industry reports and safety databases. The methodology involved a comprehensive analysis using both qualitative and quantitative methods. Findings highlighted a high frequency and severity of incidents related to Amine Absorbers and ASUs, primarily due to leaks, corrosion, overpressure, and mechanical failures. To address these concerns, detailed hazard analyses were conducted using BTA, identifying potential causes, consequences, and existing control measures. The study underscored the importance of implementing comprehensive safety strategies to mitigate risks and enhance operational safety in CCT applications.

Conclusion

The study concluded that due to the high frequency and severity of incidents, it was crucial to perform detailed hazard analyses on ASUs and Amine Absorbers. These analyses needed to focus on mitigating explosion and fire risks by implementing comprehensive safety strategies. The integration of incident data analysis and hazard analysis was demonstrated to be effective in identifying and addressing critical safety concerns. Identifying the top hazard categories allowed for more specific
analyses and the recommendation of robust safety barriers. The integration of BTA in the study provided a clear mapping of potential hazards, causes, consequences, and control measures, further underscoring the need for preventive and mitigative barriers.

Recommendations

To enhance safety and reduce the frequency and severity of incidents in CCTs, particularly for Amine Absorbers and ASUs, several recommendations were proposed. First, comprehensive safety strategies should be implemented, including regular inspections and maintenance schedules to detect and address potential hazards early. This proactive approach could prevent leaks, corrosion, and mechanical failures before they escalated into serious incidents. Additionally, enhancing operator training programs was essential to ensure personnel could identify and respond to signs of mechanical failure, overpressure, and leaks effectively.

Specific safety measures were also necessary for different equipment types. For Amine Absorbers, the use of corrosion-resistant materials and chemical inhibitors was recommended, along with the installation of robust leak detection systems. These measures would address the primary causes of incidents in Amine Absorbers, which were leaks and corrosion. In the case of ASUs, ensuring high manufacturing standards and routine maintenance would prevent mechanical failures and contamination, which were significant contributors to incidents in these units.

Further research and implementation efforts should focus on refining hazard analysis methods and improving the accuracy of incident predictions. Conducting additional studies would provide a deeper understanding of the root causes of incidents and the effectiveness of existing safety measures. Developing and integrating advanced monitoring technologies would allow for continuous assessment of equipment conditions and operational safety, enabling timely interventions.

Lastly, advocating for stricter regulations and guidelines for CCT operations was necessary to ensure adherence to best safety practices. Policymakers should encourage investment in research and development to enhance the safety and efficiency of CCTs. By addressing these recommendations, it would be possible to reduce the frequency and severity of incidents, ultimately supporting the broader adoption of CCTs in reducing carbon emissions.

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