Browsing by Author "Moore, Andrew"
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Item Open Access Data supporting: 'CO2 absorption into aqueous ammonia using membrane contactors: Role of solvent chemistry and pore size on solids formation for low energy solvent regeneration'(Cranfield University, 2022-10-13 16:42) Bavarella, Salvatore; Luqmani, Ben; Thomas, Navya; Brookes, Adam; Moore, Andrew; Vale, Peter; Pidou, Marc; McAdam, EwanSolids formation can substantially reduce the energy penalty for ammonia solvent regeneration in carbon capture and storage (CCS), but has been demonstrated in the literature to be difficult to control. This study examines the use of hollow fibre membrane contactors, as this indirect contact mediated between liquid and gas phases in this geometry could improve the regulation of solids formation. Adoption of a narrower pore size membrane was shown to dissipate wetting after crystallisation in the solvent, illustrating membrane contactors as a stable platform for the sustained separation of CO2 coupled with its simultaneous transformation into a solid. Through resolving previous challenges experienced with solids formation in multiple reactor configurations, the cost benefit of using ammonia as a solvent can be realised, which is critical to enabling economically viable CCS for the transition to net zero, and can be exploited within hollow fibre membrane contactors, eliciting considerable process intensification over existing reactor designs for CCS.Item Open Access Demonstrating commercial hollow fibre membrane contactor performance at industrial scale for biogas upgrading at a sewage treatment works(MDPI, 2021-01-13) Houlker, Sam; Rutherford, Tony; Herron, Daniel; Brookes, Adam; Moore, Andrew; Vale, Peter; Pidou, Marc; McAdam, Ewan J.Hollow fibre membrane contactor (HFMC) technology has been developed for CO2 absorption primarily using synthetic gas, which neglects the critical impact that trace contaminants might have on separation efficiency and robustness in industrial gases. This study, therefore, commissioned a demonstration-scale HFMC for CO2 separation at a full-scale anaerobic digester facility to evaluate membrane integrity over six months of operation on real biogas. The CO2 capture efficiency identified using real biogas was benchmarked at comparable conditions on synthetic gas of an equivalent partial pressure, and an equivalent performance identified. Two HFMC were subsequently compared, one with and one without a pre-treatment stage that targeted particulates, volatile organic compounds (VOCs) and humidity. Similar CO2 separation efficiency was again demonstrated, indicating limited impact within the timescale evaluated. However, gas phase pre-treatment is advised in order to ensure robustness in the long term. Over longer-term operation, a decline in CO2 separation efficiency was observed. Membrane autopsy identified shell-side deposition, where the structural morphology and confirmation of amide I and II groups, indicated biofouling. Separation efficiency was reinstated via chemical cleaning, which demonstrated that proactive maintenance could minimise process risk.Item Open Access Mitigating phase changes in the gas-phase that disrupt CO2 capture in membrane contactors: CO2-NH3-H2O as a model ternary system(Elsevier, 2024-06-01) Liqmani, Ben A.; Nayak, Vignesh; Brookes, Adam; Moore, Andrew; Vale, Peter C. J.; Pidou, Marc; McAdam, Ewan J.Solid and liquid products can form in the gas phase of membrane contactors applied to reactive ternary systems for CO2 absorption, which poses a critical barrier for carbon capture applications. The mechanism initiating these unwanted phase changes in the gas phase is unclear. This study therefore systematically characterises CO2 absorption in distinct regions of the vapour-liquid equilibrium (VLE) within an illustrative ternary system (CO2-NH3-H2O), to provide an explanation for the formation and mitigation of these solid and liquid products in the gas-phase. Unstable CO2 absorption and increased pressure drop indicated product formation within the gas-phase, which occurred at high CO2 capture ratios. Temporal analysis of gas-phase composition enabled gas-phase products to be related to the relative ternary composition. This was subsequently correlated to distinct regions of the VLE. Consequently, mitigation strategies can be developed with recognition for where products are least likely to form. Pressurisation was proposed to modify the relative gas-phase ammonia composition to reposition conditions within the VLE. The commensurate increase of CO2 into the solvent shifts the ammonia-ammonium equilibrium towards ammonium to indirectly reduce vapour pressure. This synergistic strategy allows sustained operation of membrane contactors for CO2 separation within reactive ternary systems which are critical to delivering carbon capture economically at scale.