Modelling and experimental studies of a water–gas shift catalytic membrane reactor

• A 2D-axisymmetric CMR model was developed using FLUENT.
• There was close agreement between the model and the prototype.
• Loading extra catalyst would lead to temperatures beyond recommended ranges.
• Reducing permeation side pressure is a key factor to maximise the CO conversion levels.
• The permeation pressure of the CMR defines the maximum limit of H2 yield.

A 2-dimensional, axis-symmetric CFD model of a tubular CMR has been developed using a commercial software package FLUENT for the purposes of guiding the design and operation of a HTWGS-CMR for the processing of coal-derived syngas. Development of the model has been approached in a stepwise manner through the successive incorporation of sub-models for the CMR processes. For each step, performance of model was checked and validated against measurements using a prototype CMR with same set-up applied in simulation.The optimum catalyst loading, which yield the maximum CO conversion within targeted operating reactor temperatures (350–450 °C), was found to be 11.6 kg/(COmol/s) for the inlet syngas temperature of 350 °C with a reactor having a 1″ shell diameter. The CMR model was validated experimentally with a simulated coal-derived syngas (64.5% of CO, 33.0% of H2 and 2.5% of CO2 with a 3:1 steam to carbon (S:C) ratio) at a total dry gas flow of 4 LN/min and a feed pressure of 15 barg. These tests were performed using a prototype reactor which incorporated with a tubular (0.1 mm thick, 150 cm2, 3/8″ OD) Pd/Ag23 wt% membrane. The CMR model was simulated using a wider range of operating parameters (namely permeation rate, inlet temperature, catalyst loading, pressure at permeate side and S:C ratios) to examine its sensitivity to these variables. Outcomes of these parametric analyses have enhanced our understanding of CMR operation in order to optimise its performance.