Sequential‐based process modelling of VOCs photodegradation in fluidized beds

Abstract

Sequential modular simulation (SMS), as a new modelling approach, was developed to simulate the photocatalytic oxidation (PCO) of gaseous pollutants in fluidized bed reactors. In the experimental part, the PCO of gaseous acetone was studied in a fluidized bed photo-reactor (FBPR) and the influence of operating conditions (inlet concentration, relative humidity (RH) and superficial gas velocity) on both acetone conversion and mineralization was investigated. It was found that the RH, as a key factor in PCO reactions, had a contradictory effect on the conversion and mineralization of acetone. In the modelling part, the bed was divided into several sections in which the bubble and emulsion phases were considered as a plug flow and a completely mixed flow reactor, respectively. Dynamic two-phase model was adopted as the hydrodynamic sub-model and the Langmuir-Hinshelwood (LH) mechanism as the kinetic sub-model. Kinetic constants of the latter sub-model were estimated using experimental data from the literature. A new dimensionless number (HA number) was introduced to determine the optimum number of sections, as the most important factor in model predictions. The performance of the proposed model was compared with the experimental data obtained in this study and several sets of experimental data from the literature. The results showed that the simple and easy-to-achieve approach, which has the capability of integrating into the industrial process simulators such as Aspen Plus © and Aspen HYSYS © , can be used to simulate the behaviour of non-ideal FBPRs in PCO processes.

Towards an advanced reactor network modeling framework for fluidized bed biomass gasification: Incorporating information from detailed CFD simulations

“…Here, it is accepted that with increasing flow-rate conditions, additional expansion in the emulsion is expected along with some of the increased amount of gas flowing through the emulsion [24]. This TPT modeling approach has been applied under the name "Sequential-Based Process Modeling" with considerable success in modeling the gas-phase processes in fluidized bed natural gas combustion [25], volatile organic compound (VOC) photodegradation in a fluidized bed reactor [26] and coal volatile combustion in a fluidized bed reactor [27]. In each of these modeling approaches simple hydrodynamic sub-models of bubble growth and mass transfer between the bubble-phase and emulsion phase were employed to describe the bed geometry and flow characteristics.…”

Intrinsic kinetic model with variable light intensity of the emerging pollutants degradation in a photocatalytic differential reactor with immobilized TIO2: Experiments and CFD

“…[ 7 ] Therefore, AOPs and photocatalytic processes are an alternative to EP mineralization. [ 8 ] Photocatalytic processes use the catalyst and light intensity to produce oxidizing chemical species, generally hydroxyl radicals (OH•), a strong oxidizing agent capable of degrading emerging contaminants. Titanium dioxide (TiO 2 ) is one of the most commonly used catalysts.…”

Sequential modular simulation of circulating fluidized bed reactors

“…In the former, all governing equations, such as mass and energy balances, and chemical equilibrium for the whole process are solved simultaneously, demanding extensive programming efforts. Sequential modular approaches have mainly been used to simulate beds under a low‐velocity bubbling regime ( U ~ U mf ) . In this study, a novel sequence‐based modular approach has been developed wherein a complex CFBR is segmented into a series of well‐defined, ideal sub‐units, establishing a step‐by‐step modelling method.…”

“…Sequential modular approaches have mainly been used to simulate beds under a low-velocity bubbling regime (U~U mf ). [46][47][48][49][50][51][52][53] In this study, a novel sequencebased modular approach has been developed wherein a complex CFBR is segmented into a series of well-defined, ideal sub-units, establishing a step-by-step modelling method. Although some preliminary insights into modelling CFBR risers using SMS were given by the authors in a previous paper, [54] here we provide a thorough SMS package that can predict the performance of high velocity circulating fluidized beds (U >> U mf ).…”