The Statistical Experimental Design for Chemical Reactors Modeling

Graciela Prieto,Kazunori Takashima,Oscar Prieto,Carlos Gay,Teresa Unzaga,Akira Mizuno

doi:10.4236/am.2016.714133

Abstract

The Statistical Experimental Design techniques are the most powerful tools for the chemical reactors experimental modeling. Empirical models can be formulated for representing the chemical behavior of reactors with the minimal effort in the necessary number of experimental runs, hence, minimizing the consumption of chemicals and the consumption of time due to the reduction in the number of experimental runs and increasing the certainty of the results. Four types of nonthermal plasma reactors were assayed seeking for the highest efficiency in obtaining hydrogen and ethylene. Three different geometries for AC high voltage driven reactors, and only a single geometry for a DC high voltage pulse driven reactor were studied. According to the fundamental principles of chemical kinetics and considering an analogy among the reaction rate and the applied power to the plasma reactor, the four reactors are modeled following the classical chemical reactors design to understand if the behavior of the nonthermal plasma reactors can be regarded as the chemical reactors following the flow patterns of PFR (Plug Flow Reactor) or CSTR (Continuous Stirred Tank Reactor). Dehydrogenation is a common elimination reaction that takes place in nonthermal plasmas. Owing to this characteristic, a paraffinic heavy oil with an average molecular weight corresponding to C15 was used to study the production of light olefins and hydrogen.

Highlights

Nonthermal Plasma reactors have shown an increasingly attraction power due to their ability in destroying hazardous compounds in flue gases as well as their potentiality in producing more valuables compounds from raw materials of low value, sometimes representing waste or disposable materials.The plasmas generated by electrical discharge in gases have a variety of application fields
Taking advantage of the potentiality of the Statistical Experimental Design techniques, four types of nonthermal plasma reactors were assayed seeking for the highest efficiency in obtaining hydrogen and ethylene
In the case of the nonthermal plasma reactors, the areas under the curves represent the input power expressed in watts instead of the volume obtained from similar graphics for the Continuous Stirred Tank Reactor model (CSTR) and Plug Flow Reactor (PFR) reactors

Summary

Introduction

Nonthermal Plasma reactors have shown an increasingly attraction power due to their ability in destroying hazardous compounds in flue gases as well as their potentiality in producing more valuables compounds from raw materials of low value, sometimes representing waste or disposable materials. The calculated areas that, respond to mathematical models of the ideal CSTR and PFR reactors, are compared with the experimental values to infer the behavior of the nonthermal plasma reactors flow pattern. The high complexity of modeling nonthermal plasma reactors lies in the lack of thermal equilibrium between the gaseous mass (at near-room temperature) and the electrons that acquire high temperatures because of the strong electric field applied. One possible way is to use the experimental information to construct mathematical models capable of representing the actual state of the process These models must correlate target parameters, such as efficiency or yield, with those variables that may exert influence over them. A complete factorial experimental design at two levels was selected as a preliminary approach to a first-degree-polynomial model

Experimental

Results and Discussion

S C2H4 S H2 Eff H2 Eff C2H4