Design of a Bench-Scale Tubular Reactor Similar to Plug Flow Reactor for Gas-Phase Kinetic Data Generation-Illustration with the Pyrolysis of Octanoic Acid

Julien Gornay,Lucie Coniglio,Edouard Plasari,Pierre-Alexandre Glaude,Francis Billaud,Jean-François Portha

doi:10.3390/pr9122270

Abstract

The material described in this article deals with waste conversion into energy vectors by pyrolysis, steam cracking, or oxidation of liquid biomass, carried out at small to medium scale. The design of a bench-scale experimental setup devoted to gas phase kinetic data generation in a tubular reactor under laminar regime close to plug flow is detailed based on a very simple approach. Validation of the designed bench-scale setup was successfully carried out within the context of octanoic acid pyrolysis by generating kinetic data with satisfactory measurement repeatability and material balances. The key to this positive result is that axial dispersion coefficient is much smaller in gas-phase than in liquid-phase, thus allowing the designed small sized tubular reactor to be close to the plug flow reactor. Such a feature of the axial dispersion coefficient is not well known by the wider public. Besides, octanoic acid was selected as surrogate for carboxylic acids because of their key role in various industrial applications (combustion of ethyl biodiesel; production of biofuel and biosourced chemicals).

Highlights

For the reasons mentioned previously, the design of the experimental setup should satisfy the assumptions of the models implemented in the most commonly used software for reacting system simulation, i.e., CHEMKIN II [2] or Aspen plus®, combined with EXGAS for the automatic generation of the detailed kinetic mechanisms relating to the reacting systems considered [3,4,5,6,7]
On the basis of a very simple approach, a bench-scale experimental setup devoted to gas phase kinetic data generation in laminar plug flow reactor (PFR) at constant near-atmospheric pressure gas phase kinetic data generation in laminar PFR at constant near-atmospheric pressure has has been designed
Within the context of octanoic acid pyrolysis, a sample of kinetic data was was generated with satisfactory measurement repeatability and material balances, valigenerated with satisfactory measurement repeatability and material balances, validating the dating thebench-scale designed bench-scale result isbecause obtained the axial dispersion designed setup

Summary

Introduction

Validation of models developed to accurately depict reacting systems is usually achieved when good matching between experimental information and simulated information is obtained [1]. This step cannot be conducted successfully if the experimental devices used to generate experimental information do not at least meet the theoretical hypothesis underlying the developed models. For the reasons mentioned previously, the design of the experimental setup should satisfy the assumptions of the models implemented in the most commonly used software for reacting system simulation, i.e., CHEMKIN II [2] or Aspen plus® , combined with EXGAS for the automatic generation of the detailed kinetic mechanisms relating to the reacting systems considered [3,4,5,6,7]. No wall effects that would induce heterogeneous gas-solid catalytic or non-catalytic reactions between the inner surface of the reactor and the gas phase components should occur since these effects would be ignored by the model [8]

Objectives

Methods

Conclusion