Catalytic after-treatment of lean VOC–air streams: Process intensification vs. plant reliability

•A traditional and an intensified plant for gas after-treatment have been compared.•Catalyst sintering and VOCs emissions are the most important undesired events.•The probability of occurrence of catalyst sintering is higher in the traditional plant.•The VOCs release is more probable in the reverse-flow reactor, but the associated risk is lower.

This paper compares two different processes for the treatment of a gaseous stream containing small amounts of volatile organic compounds (VOCs), namely a traditional plant, where a heat exchanger is used to recover heat from the hot gas obtained after VOCs combustion, and a plant with a reverse-flow reactor, where the catalyst is used for VOC removal and for a regenerative heat recovery. The analysis is focused on the reliability and the safety of both plants: the recursive operability analysis (ROA) is firstly used for hazards identification, pointing out that the sintering of the catalyst and the discharge of a gas with high VOCs concentration are the most critical top events. The fault trees are then extracted and quantified. Finally, an integrated dynamic decision analysis (IDDA) is carried out, with the goal of evaluating in more detail the plant behavior, for both cases, in the event of failure. Results show that the probability of occurrence of catalyst sintering is higher in the traditional plant, due to the fact that the control system used in the reverse-flow reactor is more complex and with more redundancies. With respect to the release of VOCs, this event is more probable in the reverse-flow reactor than in the traditional plant, but the associated risk is lower, although the difference is not very large.