Case Study: Thermal Hazards in the Synthesis of a Grignard Reagent

Objective

To evaluate the thermal hazards associated with synthesizing a Grignard reagent under different dosing rates.

Requirement

Assess the effect of dosing rate on thermal accumulation and runaway reaction risk. Identify the most hazardous phase in the process to improve safety measures.

Solution

A reaction calorimeter (SIMULAR) was used to analyze the heat release during Grignard reagent synthesis at different dosing rates (0.5–2.0 g·min⁻¹). Results showed that lower dosing rates significantly reduced heat accumulation and overall reaction risk.

Results

The synthesis process exhibited a high heat release, with total reaction enthalpies ranging from 362.69 to 397.11 kJ·mol⁻¹. A lower dosing rate (0.5 g·min⁻¹) minimized thermal accumulation, reducing the risk of thermal runaway. The most hazardous phase was the induction period, where heat buildup was highest.

Conclusion

The study demonstrated that dosing rate is a critical parameter in managing the thermal hazards of Grignard reagent synthesis. A lower dosing rate significantly reduces heat accumulation and mitigates the risk of runaway reactions, making the process safer. Additionally, while the Grignard reagent remains stable under normal conditions, careful control of the induction phase is essential to prevent hazardous thermal accumulation. These findings provide valuable insights for safer scale-up and industrial applications.

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Case Study: Vent Sizing for Runaway Reactions in Organic Peroxide Processing

Objective

To determine appropriate vent sizing for emergency pressure relief in the processing of organic peroxides, specifically dicumyl peroxide (DCP), using Phi-TEC II adiabatic calorimetry. The study aims to provide accurate thermal data to design effective relief systems and prevent catastrophic failures.

Requirements

• Identify critical thermal parameters, including onset temperature, maximum self-heating rate, and pressure rise.
• Assess the impact of initial back pressure and fill level on gas generation.
• Scale up experimental findings to design an effective emergency relief system.
• Ensure compliance with safety standards and best practices for process safety management.

Solution

To address these requirements, a series of low thermal inertia experiments were conducted using Phi-TEC II. The approach included:

• Kinetics Analysis: Examined the rate of decomposition and self-heating behavior to determine reaction speed and predict escalation scenarios.
• Thermodynamic Characterization: Measured adiabatic temperature rise and energy release to quantify the thermal hazard and energy balance in runaway conditions.
• Fluid Dynamics Evaluation: Assessed gas generation and pressure buildup dynamics to ensure appropriate vent design for handling multiphase flows.
• These experiments allowed the simulation of worst-case industrial scenarios and provided high-fidelity data for relief system design.

Results

• Integrated Hazard Understanding: Faster decomposition reactions combined with high thermal energy release and variable gas generation rates necessitate vent designs that accommodate rapid pressure escalation and multiphase flow conditions.
• Influence of Initial Pressure and Fill Level: Higher back pressure significantly increased maximum temperature and pressure rise rates, while gas generation was up to 2.3 times higher in open-cell experiments than in closed systems.
• Vent Sizing Considerations: Traditional models underestimated gas generation and pressure rise, emphasizing the necessity of accounting for non-equilibrium gas expansion in vent design.
• Process Safety Enhancement: Incorporating Phi-TEC II data led to more accurate vent sizing, reducing the risk of under-designed relief systems and improving overall safety strategies.

Conclusion

This case study emphasizes that an accurate approach to vent sizing must integrate kinetics, thermodynamics, and fluid dynamics to ensure comprehensive safety assessments. By leveraging Phi-TEC II adiabatic calorimetry, industrial facilities can design effective emergency relief systems, ensuring safe and efficient operation. This approach enhances process safety and risk management strategies, preventing potential accidents and ensuring compliance with industry standards.