A quick and simple approach for reactor—emergency relief system design—for runaway chemical reactions is presented. A cookbook for system sizing with all main characteristic dimensions and parameters is shown on one realistic example from process industry. System design was done based on existing theories, standards, and correlations obtained from the literature, which were implemented for presented case. A simple and effective method for emergency relief system is shown, which may serve as an example for similar systems design. Obtained results may contribute to better understanding of blow down system frequently used in industrial plants, for increasing safety, decreasing explosion damage, and alleviating the ecological problems together with environmental pollution in case of industrial accidents. 1. Introduction In process industry, raw materials are converted into various commercial products using different techniques. One frequently used method is their conversion by exothermic chemical reactions which can lead to a reactor thermal runaway if the heat generation rate exceeds the heat removal rate during process [1]. Pressure build-up during the runaway is caused by an increasing vapor pressure of liquid components and by the production of noncondensable gases. Apart from the loss of reactor inventory due to an uncontrolled conversion process, a runaway reaction may lead to severely damaged equipment or even a physical explosion if pressure build-up inside the reactor exceeds the design pressure. The emergency relief system is composed of vent area, vent rupture membrane, safety relief valve, vent pipes, blow down tank, horizontal condenser, scrubber with absorber and vertical condenser, outflow chimney, corresponding pumps, fan, pipes, fitting, and supply system with electricity, cooling water, and neutralization medium. In case of reaction runaway, the vent rupture disc opens and the reactor mixture blows out into the vent pipes and flows into blow down tank. Due to short residence time of reactor mixture in the blow down tank, the volume changes and the pressure decreases at isothermal conditions, which results in the condensation of reaction mixtures. Remained two phases flow instantaneously blows into horizontal condenser, where it cools down, condensates, and flows into absorber with vertical condenser, where it is neutralized [2–4]. In present study, a detailed design of emergency relief system is shown based on Design Method for Emergency Relief Systems (DIERSs). It incorporates the state-of-the-art knowledge obtained from mechanical,
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