Working with Exothermic Reactions during Lab and Scale up
Working with Exothermic Reactions is always a challenging task. Reactions which can be easily controlled in the lab become challenging at pilot scale and a nightmare during plant. We thought it is a good idea to summarize some of the best practices we have accumulated from long years of experience. Again, each situation is unique and we strongly advise you to consult our process experts at Amar for a discussion about your system. [email protected]
1. Heat Management:
- Heat Removal Capacity: Ensure the reactor cooling system can handle the maximum heat release from the reaction. Cooling systems might include cooling jackets, external heat exchangers, or cooling coils. For knowing the maximum heat release you will probably have to use an experimental technique such as DSC or RC. Sometimes an initial guess may be obtained via a simulation or a group contribution method but these can be unreliable at times. If you are lucky, you may find a literature reference to a reliable experimental study.
- Adiabatic Temperature Rise: Calculate the potential adiabatic temperature rise if all reactants were to react without any heat removal to assess worst-case scenarios.
2. Kinetic Studies:
- Rate of Reaction: Understand the rate of the reaction at various temperatures to predict how it might change upon scale-up.
- Activation Energy: Knowing the activation energy can help predict how the reaction rate will change with temperature.
3. Stirring and Mixing:
- Ensure adequate stirring to prevent hotspots and ensure homogeneity in the reactor. Mixing should be evaluated and optimized for the scale of the operation. Use the right stirrer for the right task. E.g. It is counterproductive to use an anchor on a low viscosity exothermic reaction system. Our Amar reactors come with a wide range of stirring options.
Typically mixing becomes worse as scale rises and this is a difficult problem to fix. Sometimes, a reactor design that works well at the lab scale might not be optimal for larger scales.
4. Temperature Control:
- Use accurate and reliable temperature probes to monitor the reactor temperature.
- Implement automatic temperature control systems that can adjust cooling rates or add quenching agents to maintain the desired temperature range.
5. Pressure Management:
- Ensure that the reactor is rated for the maximum pressure that might be encountered.
- Use pressure relief devices and ensure that they're appropriately sized. This can be a challenging task especially for two phase flows. Consult the AICHE DIERS methodology for additional help.
6. Safety Measures:
- Runaway Reactions: Develop a response plan for potential runaway reactions, which might include dumping the contents into a quenching bath or using an emergency cooling system.
- Safety Studies: Conduct safety studies, such as Differential Scanning Calorimetry (DSC) or Reaction Calorimetry, to understand potential hazards.
7. Pilot Scale Testing:
- Before scaling up to full production, run the reaction at a pilot scale to identify any unforeseen challenges or behaviors.
8. Batch vs. Continuous Processes:
- Consider the pros and cons of running the reaction as a batch or continuous process. Continuous processes can sometimes offer better control over exothermic reactions, but they might not be suitable for all chemistries or business models. Contact our flow team at Amar who can even screen your reaction at our in house flow reactor facility. [email protected]
Remember, every reaction and its scale-up will have unique challenges. The above guidelines serve as a foundation, but a thorough understanding of the specific reaction, backed by experimental data and safety studies, is essential. Safety should always be the top priority when scaling up exothermic reactions.
Please talk to our team at Amar for specific help on your system. [email protected]