miolo sho2009_indices v8 - Departamento de Produção e Sistemas ...

heavy structural damage in a radius of 150 ft, one fatality, three serious injuries, and 18 lessserious injuries [2].Sho2009All these facts and other similar evidences show that EO production has high potential accidentwith serious consequences. Therefore many studies have been done to minimize the risk ofaccidents in EO production process. This paper, however, is only focused on the EO reactordue to high sensitivity of reaction runaway, overpressure, and explosion. It is prepared on thebasis of a study carried out at Chalmers University of Technology [5]. The objective of the studyis to identify all possible hazards which could cause runaway in the EO reactor and to improvethe safety feature in this regard.Colóquio internacional sobre segurança e higiene ocupacionaisMETHODOLOGYUnderstanding of the existing system is one of the most important requirements for theimprovement. Based on the understanding, the weaknesses and hazards existing in the systemcan be identified and then the improvement can be introduced. Studying of the previousaccidents was done in order to find the root causes in the area of interest. Furthermore, thehazardous scenarios and the causes of accidents were identified by applying HAZOP study andFailure Mode and Event Analysis (FMEA). HAZOP is used to find hazardous scenarios relatedto operating procedure; while FMEA was used to analyze potential failure in the eachequipment.In the HAZOP method, hazard identification will be done in the comprehensive and systematicway, section by section in each part base on the process and instrument flow diagram.Systematically question is introduced to drive what deviation can give rise to hazards. Thus, thehazards related with operating procedure were found. In the FMEA method, all potential failuresin the equipment and their effects to the system were identified. Several actions and safeguardswere introduced to prevent the failures.RISK EVALUATIONS AND THE RESULTSTo analyze the safety in the EO reactor, HAZOP and FMEA analysis is done using P&ID in theFigure 1. Two possible reactions may happen inside the reactor resulting Ethylene oxideformation and Ethylene combustion.Ethylene Oxide Formation:Ethylene Combustion:C2H4+ 0.5O2→ C2H4OC2H4+ 3 O2→ 2CO2+ 2H2OThe reaction is exothermic, which can release 900 BTU/lb EO reacted [2].Fatal accident such as explosion in the reactor can be triggered by exceeding of the twoparameters, such as temperature and oxygen concentration. Temperature is controlled byreactor cooling system, while oxygen concentration is controlled by oxygen analyzer. To help tocontrol reactor temperature, gas ballast is introduced into the feed stream to absorb some of theEO reaction heat. In this plant, methane is utilized as gas ballast since it has inert characteristicand high heat capacity.102