Project Synopsis

Provide process engineering support to evaluate the safe operating conditions and limits of a catalyst batch reaction production system.

Project Summary


The client, a catalyst manufacturer, was undertaking a proactive initiative to evaluate safety aspects of an existing batch reactor system.   As part of this effort Process Engineering Associates, LLC (PROCESS) was contracted to assist in the evaluation and definition of safe operating limits /safe control limits (SOLs / SCLs) for the process. Parts of NFPA 69 was used for guidance (Explosion Prevention Systems, Deflagration Prevention by Oxidant Concentration Reduction).

An initial site visit was made to the facility to review the process, procedures, and to collect operating data.  Based on this information, PROCESS developed a preliminary mass balance for the system.  The intent of this balance was to better define key aspects of the process and uncover any additional information that might be required prior to executing the full project scope.  Due to findings in this initial scoping effort, the evaluation basis was reduced to cover only the primary reaction step.

In the primary reaction step, an unquantified amount of a flammable component was vented from the reactor.  It was theorized that the introduction of two diluent gases into the system were sufficient to maintain concentrations in the non-flammable region; however, the addition rates of the diluent gasses were not known.  Furthermore, concentrations of the flammable component and oxygen in the effluent vent were unknown.  Using simplifying assumptions, the preliminary mass balance indicated the potential for a combustible mixture to exist in the reactor head space and/or downstream vent system.  For this reason, PROCESS recommended refocusing project efforts on better defining this area of the process.

For this new project scope, the facility made diluent gas rate measurements.  Simultaneously, PROCESS began devising correlations for peak gas generation rates relative to available reaction kinetics.  With this information, a more complete simulation model of the reaction step was developed.  Results from this model indicated that the vapor space likely operated in the flammable region for some portion of the process.  Analysis of the vent gas taken during operations were in good agreement with these model results and corroborated the finding.

At the client’s request, PROCESS developed a preliminary scheme to both monitor and control vapor concentrations within the reactor system.  As the required changes were not insignificant, the client has initiated additional monitoring and testing before proceeding with a final system design.

Industry Type

  • Catalyst Manufacturing

Utilized Skills

  • Safe operating limits evaluation

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