McAdam, EwanHoulker, Samuel Thomas2023-10-122023-10-122019-03https://dspace.lib.cranfield.ac.uk/handle/1826/20366Hollow fibre membrane contactors (HFMC) are a gas-liquid contacting technology suggested as a successor to existing gas-liquid absorption columns for the selective separation of carbon dioxide (CO₂) from biogas i.e. biogas upgrading, which in the United Kingdom (UK) is a rapidly expanding sector for renewable heat production. Current incentivisation schemes also encourage process innovation to reduce cost, and those that enable the revaluation of waste. In response to these drivers, this thesis firstly describes the implementability of HFMC as a successor technology to packed columns for biogas upgrading, due to its capability for process intensification, and subsequently introduces how to employ environmentally sourced ammonia to drive chemical absorption in HFMC, thereby extending process intensification, whilst also reducing aeration costs and through a unique contribution of the membrane, enables the crystallisation of ammonium bicarbonate which can increase value as a new product. This thesis has introduced an assessment of mass transfer in multi-module configurations to further intensify the process and demonstrated that when producing a high purity methane product, a simplified mass transfer model, based on the overall mass transfer coefficient, can be used to determine gas product quality, process scale and membrane configuration. Mass transfer behaviour in commercially favoured transverse flow HFMC modules was compared to parallel flow HFMC modules, typically used in laboratory investigation which are known to suffer from maldistribution, to enable the reconciliation of maldistribution with a description of parallel flow and the translation of the overall mass transfer coefficient across module scale. The resilience of HFMC to industrial conditions, including gas-phase contaminants such as particulates, was assessed at a WWTW, demonstrating the primary mechanism of fouling to arise from the absorbent, in particular biological adsorption and clogging of the shell-side, which is readily reversible through chemical cleaning. Integration of an NH₃ chemically reactive absorbent for the co-production of a high purity methane product and recovery of ammonium bicarbonate demonstrates that the reduction in specific nucleation rate and preferential crystal growth in HFMC protects the system from blocking by the reaction product, in contrast the high specific nucleation rate and subsequent agglomeration of the reaction product induces process blocking during column operation.en© Cranfield University, 2019. All rights reserved. No part of this publication may be reproduced without the written permission of the copyright holder.Multi-module designmaldistributioncascadedimensionless correlationresistancepre-filtrationmembrane foulingmembrane crystallisationammoniaammonium bicarbonateThesis or dissertation