Question 1

How to apply Process Safety into the Development Workflow?

Accepted Answer

Applying a safety-by-design approach within the development workflow has safety and cost benefits. Broadly speaking, process safety scale-up follows four main stages: Screening for potential hazards Evaluation of the main reactions, including possible unintended side reactions Evaluation of “what if” worst case scenarios and subsequently implementing mitigation and control strategies. These steps naturally map onto the product development funnel. At the top of the funnel, the tests need to be simple and quick to address the number of samples. At this stage, the information provided can be quite limited. At the bottom of the funnel, poor candidates have been eliminated from consideration, and more information is required. Tests at this stage will be longer, and the experimental complexity will be greater than in discovery.

Question 2

How does early raw material hazard screening speed up the decision process?

Accepted Answer

Rapid hazard screening of raw materials at the front end of development allows earlier decisions to be made on how to develop the desired reaction and the synthetic route. It is vital to know early in product development if the raw materials are likely to have thermal stability issues, such as the production of non-condensable gases, which could pose an explosion risk on scale-up. Key questions to answer are: What is the thermal decomposition profile of the raw material? In particular, does the decomposition of the raw material start to increase significantly at a ‘low’ temperature (onset decomposition temperature)? If the desired synthesis reaction reaches this onset temperature via an initial exothermic event, this could cause the reaction to increase further in temperature, creating a secondary thermal runaway.

Question 3

How Can The Operating Conditions Be Modified To Reduce The Risks Identified?

Accepted Answer

Stoessel diagrams can help us understand how risky chemical processes are, including desired reactions and secondary reactions (such as decomposition reactions). Stoessel classification identifies 5 possible scenarios, ranked from least dangerous to most dangerous. The commonality that the three first categories have, is that the maximum temperature of synthesis reaction (MTSR – the maximum temperature the reactor would reach if a failure in cooling occurs) stays under the temperature of decomposition (T d , temperature at which some of the reactants or products start to break down at a detectable rate).In the case of scenarios (D) (E), it is necessary to consider if the MTSR can be reduced by altering the conditions of the reaction to reduce the levels of accumulated reagent.

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Critical Considerations in Process Safety

Introduction

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Leaders in Scientific Equipment & Automation Software

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