Chemical and Biomolecular Engineering - Research Publications
Permanent URI for this collection
Search Results
1 - 4 of 4
-
ItemInternal polymeric coating materials for preventing pipeline hydrogen embrittlement and a theoretical model of hydrogen diffusion through coated steel(PERGAMON-ELSEVIER SCIENCE LTD, 2022-08-26)This work develops a theoretical analysis of the coating permeability necessary for use as internal coatings of transmission pipelines to prevent hydrogen embrittlement. Internal coating materials suitable to be applied in situ on existing steel pipelines are also evaluated. Twelve different commercially available coatings; crosslinked poly (vinyl alcohol) (PVA), poly (vinyl chloride) and bisphenol A diglycidyl ether (DGEBA)/polyetheramine (D-400) epoxy coatings prepared in-house were tested. Films fabricated from two commercial epoxies had hydrogen permeability of 0.40 Barrer and 0.35 Barrer respectively, which show potential as coating materials. A hydrogen permeability of 0.0084 Barrer was achieved with a crosslinked poly (vinyl alcohol) coating, indicating that this material shows the highest potential of all coatings tested. Unsteady-state hydrogen diffusion through coated steel was then modeled to evaluate the effect of the coating film in reducing hydrogen embrittlement. The result shows that with a 2 mm PVA coating, hydrogen permeation inside the coating will take seven years to reach equilibrium and the final hydrogen concentration on the steel surface will be 44% lower than that without a coating. Greater protection can be provided if coatings can be developed with lower hydrogen permeability.
-
ItemGas-liquid membrane contactors for carbon dioxide separation: A review(ELSEVIER SCIENCE SA, 2021-05-01)Membrane gas–liquid contactors have been developed to reduce the capital cost and energy consumption of conventional CO absorption and stripping columns. As a hybrid technology of membrane separation and amine absorption, these units can improve the gas absorption process by generating 400–1500% greater mass transfer area per unit volume leading to smaller equipment sizes. Regeneration of CO can occur within a membrane contactor below the boiling point of the solvent, leading to lower energy consumption. Over recent years, a vast array of polymeric and ceramic materials have been considered for membrane gas–liquid contactors and an array of solvents have been used including amines, potassium carbonate, ammonia and amino acids. The major technical challenge with membrane contactors is the wetting of the membrane pores with solvent, which reduces the mass transfer coefficient. However, other factors such as the choice of solvent, the placement of the solvent on the shell or lumen side and the operational temperature are also critical to success. This review describes the recent progress in membrane gas–liquid contactor technology for CO separation in terms of the materials, solvents, modules and processes and provides direction on where research can best be directed in the future to enhance the feasibility of the technology's industrial application. 2 2 2
-
ItemEfficient degumming of crude canola oil using ultrafiltration membranes and bio derived solvents(Elsevier BV, 2020-01-01)Vegetable oils derived from rapeseed and its genetic variant canola, are conventionally extracted from oilseeds by means of an organic solvent, typically hexane. Concerns regarding the toxicity of hexane have meant safer and more environmentally friendly solvents such as terpenes are becoming attractive. In this research, the degumming of canola oil/terpene mixtures using ultrafiltration is considered as a critical step in such an extraction process. Polysulfone (PSF) and polyethersulfone (PES) membranes were found to be ineffective in this application, as the oil appeared to cause swelling of the membrane structure. This meant that the original flux could not be restored after cleaning. Conversely, a ceramic membrane (MWCO 5 kDa) provided stable behaviour over several cycles of operation when cleaned with pure solvent at high cross velocity at 40 °C. This membrane showed high phospholipid retention (95 ± 2%), although some oil was also retained (16 ± 3%). Cymene emerged as the most attractive of the three terpenes tested, with higher permeate flux and phospholipid rejection than limonene or pinene.
-
ItemMembrane gas-solvent contactor pilot plant trials for post-combustion CO2 capture(Elsevier, 2020-04-15)Membrane gas-solvent contactors are a hybrid technology of solvent absorption with membrane separation that achieves efficient and compact carbon dioxide capture. Here, we report on a successful pilot plant trial of membrane contactor technology undertaking post-combustion carbon dioxide capture from flue gas generated by an Australian black coal fired power station. The pilot plant utilised membrane contactors to undertake CO2 absorption into 30 wt% monoethanolamine (MEA) and the subsequent solvent regeneration stage to produce a pure CO2 product. The pilot plant trials identified a commercially available non-porous poly dimethylsiloxane composite hollow fiber membrane as the most suitable for both CO2 absorption and solvent regeneration. The overall mass transfer coefficient for CO2 absorption across the membrane into the solvent was comparable to laboratory results, enabling a recovery of >90% CO2 from the flue gas. Over time the mass transfer coefficient decreased because of both solvent dilution and some MEA loss, which reduced the enhancement the reaction provides to mass transfer in the solvent boundary layer. The overall mass transfer of CO2 from the solvent into the steam sweep during solvent regeneration was greater than that observed in the laboratory for the same temperature. The energy demand of the pilot plant was higher than for conventional CO2 capture technology, given the pilot nature of the process, lack of energy integration and thermal losses from uninsulated membrane modules. Accounting for these factors, the energy duty of the membrane contactor process was evaluated to be less than 4.2 MJ/kg of CO2 captured. Critically, the pilot plant demonstrated the viability of membrane contactor technology for post-combustion carbon capture on an industrial scale.