Abstract
This paper deals with the design of a suitable microreactor for the catalytic oxidation of volatile organic compounds (VOCs). There are a number of ways to release VOCs into the atmosphere, typically during processing of natural gas and handling petroleum products. As VOCs are harmful to our health, there is increased scientific interest in developing technologies for their destruction. Catalytic oxidation is one of them. Microreactors have showed higher efficiency than the conventional ones, mainly due to their large surface area to volume ratio and excellent heat and mass transfer properties. The design of a microreactor can be explored based on simulation results obtained by using computational fluid dynamics (CFD) package of COMSOL Multiphysics. The first design step, based on cold flow simulation, was the selection of the most suitable microreactor geometry and configuration. Four different geometries had been proposed and simulated to evaluate the fluid behaviour in the microchannels. One of them, Type A2, allowed the most uniform flow distribution in all channels, as assessed through relative standard deviation calculations. The second design step involved the investigation of the VOCs catalytic oxidation, using propane as model molecule, occurring in the microreactor with the geometry/configuration previously found. The proposed microreactor consists of eleven parallel channels of square cross-section, with 0.5 × 10 -3 m width, 0.5 × 10 -3 m height and 0.1 m length. The catalytic microreactor was simulated for temperatures between 563 K and 663 K and inlet flow velocities from 0.01 to 1.00 m·s -1 . The exit propane conversion increased rapidly with increasing temperature for a fixed inlet flow velocity. For a fixed temperature, the propane conversion increased as the inlet flow velocity decreased.
Highlights
In recent years, constraints imposed by the increasingly stringent environmental regulations and safety awareness, coupled with increasing competition, have put great stress on traditional chemical industry
The relative standard deviations are an order of magnitude less for type A2, A3, and A4
It appears that the observed effect is linked to the dead space in the manifold
Summary
Constraints imposed by the increasingly stringent environmental regulations and safety awareness, coupled with increasing competition, have put great stress on traditional chemical industry. Development and implementation of more sustainable chemistry and chemical technologies is one of the most essential requirements for the chemical industry to survive for the future These challenges drive innovations in both chemistry and chemical engineering. Implementation of any chemical engineering development that leads to substantially smaller, cleaner, and more energy-efficient technologies is probably the most popular strategy for developing new chemical processes and equipment [1]. This is possible by challenging technologies for sustainable manufacturing such as the use of ecoeffeciency, inherent safety with improved quality of the product, reduced environmental impact, rapid plant response and great possibilities for distributed manufacturing [2,3]. There were a number of process intensification approaches and these include intensification of mass transfer in static mixers [4,5], micromixers [6,7] and rotating packed bed [8,9], intensification of heat transfer using compact/micro heat exchangers [10,11] and nanofluids [12], integration of processes in one multifunctional step to reduce plant size and increase process efficiency, for instance, reactive distillation and membrane reactor [13,14,15], and adoption of new reactors such as compact/microreactors [16,17], heat exchange reactor [18], spinning disk [19], impinging jets reactors [20] and ZoneFlowTM reactor [21]
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