Wang, Jue (PhD)

Fundamental modelling of membrane-assisted chemical looping reforming for H2 production with integrated CO2 capture

J. Wang, I. Roghair, M. van Sint Annaland
Room: STW 0.35, E-mail:
j.wang4@tue.nl

Introduction

A novel reactor concept for the production of ultra-pure hydrogen with integrated CO2 capture is proposed, based on membrane-assisted chemical-looping reforming of methane. The concept integrates various technologies, such as gas-solid fluidization, chemical looping, membrane reactors and chemical reactions. While the process has been found economically feasible and is a promising alternative to current industrial production of ultra-pure hydrogen, no design rules exist. The description of the reactor system and its scale-up should be performed with reliable and detailed models. The Two-Fluid modelling (TFM) approach is a Computational Fluid Dynamics approach that is very suitable to simulate fluidized bed membrane reactors at reasonably large scales, but with still enough details to have fundamental insight in flow characteristics.

The main objective of this project is to develop, validate and use a two-fluid model for gas-solid fluidized bed membrane reactors (i.e. discrete particle model and two-fluid model), including mass transfer, membrane separation and chemical reactions such that it can achieve an accurate description of multiphase flow and chemical reaction in the MA-CLR reactor. Using an existing Two-Fluid Model for gas-solid fluidized bed membrane reactors as a basis, the main focus lies on the modelling of the kinetics and on the heat balance equation in the system. Most notably, the solids redox kinetics needs to be included to account for an accurate description of the process, and an investigation to minimize the fuel slip (i.e. hydrogen or fuel that escapes the reactor without being consumed) will be performed. The simulation results obtained by the new model will be compared with the results obtained by experimental methods, which are also available in the SPI group.

Objective

The novelties for this study are two-fold:

  1. The MA-CLR concept is a novel concept in itself, and while some previous investigations have been performed in which the basic understanding and feasibility of the concept have been shown, the time is now to harvest and create actual design rules for industrial application. These design rules/correlations will be constructed using the proposed model, and will be used in industrial-scale phenomenological models, allowing to quickly simulate MA-CLR concepts.

    The model thus creates:

    1. Fundamental understanding of effects in the MA-CLR concept

    2. Design rules for membrane reactors

    3. Coarse-grained, phenomenological models for fast-paced simulation whilst maintaining accuracy

  2. Computational Fluid Dynamics models coupled to mass and heat transport and chemical reactions are already scarce in the open literature, but including gas-phase kinetics and solids phase redox kinetics is practically non-existent. By including solids redox kinetics models in the CFD model, we can for the first time fundamentally study the effectiveness of the solids phase, not only for the MA-CLR concept but for reactive fluidized beds in general.