Risk assessment of reaction safety in fine chemical industry
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According to the \"Guiding Opinions of the State Administration for Work Safety on Strengthening the Risk Assessment of Safety in Fine Chemical Reactions\" (An Jian Zong Guan San [2017] No. 1), II. Accurately defining the scope and content of risk assessment for safety in fine chemical reactions: (I) For batch and semi-batch reactions in enterprises that involve hazardous chemical processes under strict supervision as well as metal-organic synthesis reactions (including Grignard reactions), a risk assessment of reaction safety is required if any of the following conditions apply: 1. A new process or formula is used for industrial production for the first time in China, or a new process introduced from abroad has not yet undergone a risk assessment of reaction safety； 2. Changes occur in the existing process routes, process parameters, or plant capacity, and there is no reaction safety risk assessment report ； 3. Incidents of production safety accidents that occurred due to problems with the reaction process. Guidelines for Safety Risk Assessment of Fine Chemical Reactions (Trial) 3 Safety Risk Assessment of Reactions 3.1 Process Information Process information includes the technical details related to a specific manufacturing process, such as the properties of the materials used, the proportions of these materials, the range of control for reaction temperature and pressure, reaction time, as well as the methods and rates of material addition. It also encompasses the necessary qualitative and quantitative analysis methods for control. For the chemical reactions involved in the production of the same product, different assessment agencies arrive at varying levels of hazard assessment; as a result, owners choose the agency that gives a lower rating. Is it worth it for companies in the same industry to keep investing resources in conducting experiments on basic data? Shouldn’t the basic data be improved by research institutions and other such organizations? The four temperature parameters (i.e., the process temperature, the highest temperature achievable under the given conditions, the temperature at which the maximum reaction rate is reached within 24 hours, and the highest temperature that an uncontrolled system can reach) are the most fundamental data; it’s really hard to understand the relevant documents and policies these days
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Even when the same product is manufactured using similar process methods, the results and conclusions of safety risk assessments for fine chemical reactions can vary due to differences in factors such as the performance of catalysts used, equipment size, parameters related to mixing and heat transfer, material ratios, feeding methods, process parameters, control schemes and safety interlocks, as well as corresponding protective measures. It is not possible to apply these assessments directly to different projects; rather, the methods used for safety risk assessment can serve as a reference.
The main safety risk in fine chemical production comes from the thermal risks associated with the process reactions. Conducting a reaction safety risk assessment means evaluating the thermal risks of the reaction. This has nothing to do with the feeding method, control scheme, or safety interlocks. This is the thermal risk data of the reaction – it’s the most basic data, right?
Take Article 2.1 of the \"Guidelines for Risk Assessment of Safety in Fine Chemical Reactions\" as an example; the worst-case scenario for an uncontrolled reaction system is adiabatic conditions. Under adiabatic conditions, the time required for an uncontrolled reaction to reach its maximum reaction rate is known as the time for the maximum reaction rate of the uncontrolled reaction to be attained; this can be simply understood as the detonation time. …” The \"time required for the uncontrolled reaction to reach its maximum reaction rate\" here is related to factors such as the catalyst performance under abnormal operating conditions. When abnormal temperature spikes occur in the reaction system, the reaction rate, product selectivity, and other parameters differ from those under normal operating conditions ； Moreover, catalysts of different grades or manufacturers may vary in terms of activation energy, activity, and product selectivity ； Therefore, the exothermic rate after the reaction gets out of control, as well as the time required to reach the maximum reaction rate, will also vary. If the impact of these factors is ignored, the results obtained from the evaluation will have little practical value.