Why do runaway reactions occur

Develop critical safety data for inclusion in SDS documents. Model transport of airborne virus aerosols to guide safe operations and ventilation upgrades. Model transport of contamination for source term and leak path factor analysis.

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Combustible dust. Recent Posts. Process Safety Considerations The following items should be considered in relation to a process safety hazard evaluation. Quantification of desired reactions: Determine the heat of reaction and off-gas rates for the desired and quench reactions, including the heat resulting from accumulation of reagents or slow forming intermediates, Determine the maximum adiabatic temperature for the reaction, and determine the basis of safety relative to the estimated boiling point of the reaction mixture, and Understand the relative rates of all chemical reactions.

Quantification of adverse reactions: Assess the thermal stability of the reaction mixture over a wide temperature range When optimizing the robustness of the process, consider other reaction variables, such as pH, concentration, conversion rate, off-gas rate, stability of starting and product substrates in solution and as a slurry Consider the potential and impact of unwanted vapor-phase reactions, and Develop a chemical-interaction matrix for materials present in the reaction mixture, classify the reactivity, and communicate this information to operational personnel Plant considerations: Conduct a basic energy balance to consider the heats during various additions, heat generated during the chemical reaction, and the heat removal capability of the plant reactor system.

Remember to include reactor agitation as a source of energy, Consider the impact of possible deviations from the intended reactant charges and operating conditions, Identify all heat sources connected to a reaction vessel and assume the maximum possible worst-case scenario, Determine the effect of the lowest possible temperature to which the reactor heat-transfer fluid could cool the reaction mixture, i.

General chemistry and engineering design concepts: Design reactions that occur fairly rapidly, if possible, Avoid batch reactions in which all the potential chemical energy is present at the onset of the reaction, unless absolutely necessary, Use semi-batch processes for exothermic reactions in which the batch temperature and any off-gassing can be maintained through controlled addition of the reagent, For highly exothermic reactions, avoid using temperature control of the reaction mixture as the only means for limiting the reaction rate, and When scaling up a reaction, account for the impact of vessel size on heat generation and heat removal: The volume of the reaction mixture increases by the cube of the vessel radius but the wetted heat-transfer area increases only by the square of the radius.

Training: It is important to have clear, concise and unambiguous batch directions with appropriate hazards warnings to clearly explain what must be done at each step in the process including the identification of required safeguards. Conclusion Having a documented process safety strategy or procedure in place allows for a standardized approach to hazard identification and organizing process safety information in a uniform manner. References Hendershot, Dennis C.

Kwasny, Richard S. AND OR. Add Another. Standard Search Advanced Search. Limit to results with full text. Select All Expand All. Collapse All. Citation Export Print. Javascript must be enabled for narrowing. Results 1 - 1 of 1. Search took: 0. Control of runaway reactions. Gustin, J. Abstract Abstract. Catastrophic accidents such as those of Bhopal, Seveso, Griesheim and others, proved that emergency relief systems should not only prevent vessels from bursting but also provide a reliable release containment system.

A two-phase release of the vessel inventory sprayed over the neighborhood is not acceptable. The size and cost of containment systems is such that one cannot afford to accommodate the worst credible scenario. Solenoid Valve Working and Types. Coriolis Flow Transmitter Working. Boiler Drum Level Control. Deluge Valve System Working. Proximity Sensor Working and Types. Thermocouple Working and Types. Tachometer Working and Types. Rotameter Working and Types.

Cascade Control and Ratio Control. Feed Back and Feed Forward Control. Venturi Meter versus Orifice Meter. Orifice Meter Structure and Working. Venturimeter Working Principle. Skip to content Process. More:- Chemical engineering World. Instruments Thermocouple Working and Types 29 Oct, Instruments Tachometer Working and Types 16 Oct, Instruments Rotameter Working and Types 15 Oct, Instruments Venturimeter Working Principle 22 May,