Modeling and Simulation of Supersonic Natural Gas Dehydration using De Laval Nozzle

The purpose of this report is to provide an overview of the writer’s Final Year Project. Current techniques in dehydration of natural gas, such as absorption, adsorption and membrane require relatively large facilities, a large investment, complex mechanical work, and the possibility of having a negative impact on the environment. Separation with supersonic flow is proposed as a solution to some of the disadvantages of conventional methods. The objectives of the project is to perform simulation which model natural gas flow through a convergent-divergent nozzle which separates water from natural gas and study pressure and temperature drop as well as the effectiveness of the separation. FLUENT and GAMBIT are the major tool used in running the simulation. Simple explanation on the methods is provided in this report. Gas is accelerated up to velocities exceeding the sound propagation velocity in gas through a convergent-divergent nozzle due to transformation of a part of the potential energy of flow to kinetic energy the gas is cooled greatly. The result of the simulation shows velocity of gas increases significantly at the choke, resulting in temperature drop which condenses water vapour in the gas mixture. By removing water liquid droplets, water content in system can be reduced. Temperature, pressure, velocity and component mass fraction profiles are included in the report. Furthermore, effects of different inlet mass flow rate are studied. Higher inlet mass flow rate increases temperature drop, hence more water vapour is condensed and lower water content left in natural gas. For effective separation, sufficient inlet mass flow rate is required to achieve sonic flow in a 3-inch pipeline. Recommendations for future work expansion and continuation are provided at the end of the report

Preliminary assessment of Polytrichum commune extract as an antimicrobial soap ingredient

Mosses have long been used in traditional Chinese medicine due to the presence of secondary metabolites which have shown high biological activities. In particular, these secondary metabolites have demonstrated effective antibacterial activity against pathogenic microorganisms. In this study, the influence of different extraction solvents on the antibacterial activities of the Polytrichum commune was carried out using the disc diffusion method. Results showed that both 12.5 mg/mL of methanol moss extract and 6.25 mg/mL of ethanol moss extract were the most effective concentrations against Bacillus cereus and Pseudomonas aeruginosa. Additionally, the P. commune extracts were included as an added ingredient in soap bases to produce antibacterial soap prototypes where the effectiveness of the soaps containing the extracts in removing microorganisms from actual test individuals was carried out. Results of the thumb impression test of test individuals showed that the growth of microbial reduced after washing hands with the usage of both liquid and solid soap with the addition of P. commune extracts. Moreover, the antibacterial soaps performed better in eliminating microorganisms in comparison to control soaps without P. commune extracts. Taken together, P. commune extract could be a good candidate as a value-added ingredient utilized to produce antibacterial soaps due to its antibacterial properties

Progress in thermochemical co-processing of biomass and sludge for sustainable energy, value-added products and circular economy

To achieve the main goal of net zero carbon emission, the shift from conventional fossil-based energy/products to renewable and low carbon-based energy/products is necessary. Biomass has been perceived as a carbon–neutral source from which energy and value-added products can be derived, while sludge is a slurry waste that inherently contains high amount of minerals and organic matters. Hence, thermochemical co-processing of biomass wastes and sludge could create positive synergistic effects, resulting in enhanced performance of the process (higher conversion or yield) and improved qualities or characteristics of the products as compared to that of mono-processing. This review presents the current progress and development for various thermochemical techniques of biomass-sludge co-conversion to energy and high-value products, and the potential applications of these products from circular economy’s point of view. Also, these technologies are discussed from economic and environmental standpoints, and the outlook towards technology maturation and successful commercialization is laid out

A review on potential of green solvents in hydrothermal liquefaction (HTL) of lignin

One of the greatest challenges in biorefinery is to reduce biomass’ recalcitrance and enable valorization of lignin into higher value compounds. Likewise, green solvents and hydrothermal liquefaction (HTL) with feasible economic viability, functionality, and environmental sustainability have been widely introduced in extraction and conversion of lignin. This review starts with the underscore of disadvantages and limitations of conventional pretreatment approaches and role of green solvents in lignin extraction. Subsequently, the effect of process parameters along with the reaction mechanisms and kinetics on conversion of lignin through HTL were comprehensively reviewed. The limitations of green solvents in extraction and HTL of lignin from biomass were discussed based on the current advancements of the field and future research scopes were also proposed. More details info on HTL of biomass derived lignin which avoid the energy-intensive drying procedures are crucial for the accelerated development and deployment of the advanced lignin biorefinery

Fractionation and extraction of bio-oil for production of greener fuel and value-added chemicals : Recent advances and future prospects

Bio-oil is a highly valuable product derived from biomass pyrolysis which could be used in various downstream applications upon appropriate upgrading and refining. Extraction and fractionation are two promising methods to upgrade bio-oil by separating the complex mixture of bio-oil compounds into distinct fine chemicals and fractions enriched in certain classes of chemical compounds. In this review, various extraction techniques for bio-oil (organic solvent extraction, water extraction, supercritical fluid extraction, distillation, adsorption, chromatography, membrane, electrosorption and ionic liquid extraction), their associated features (extraction mechanisms involved, advantages and disadvantages), the characteristics of bio-oil extracts and their applications are presented and critically discussed. It was revealed that the most promising technique is via organic solvent extraction. Furthermore, the technological gaps and bottlenecks for each separation techniques are disclosed, as well as the overall challenges and future prospects of oil palm biomass-based bio-oil value chain. This review aims to provide key insights on bio-oil upgrading via extraction and fractionation, and a proposed way forward via technology integration in establishing a sustainable palm oil mill-based biorefinery

Hydrogen sulfide (H2S) conversion to hydrogen (H2) and value-added chemicals : Progress, challenges and outlook

Hydrogen sulfide (H2S) is a toxic gas released from natural occurrences (such as volcanoes, hot springs, municipal waste decomposition) and human economic activities (such as natural gas treatment and biogas production). Even at very low concentrations, H2S can cause adverse health impacts and fatality. As such, the containment and proper management of H2S is of paramount importance. The recovered H2S can then be transformed into hydrogen (H2) and various value-added products as a major step towards sustainability and circular economy. In this review, the state-of-the-art technologies for H2S conversion and utilization are reviewed and discussed. Claus process is an industrially established and matured technology used in converting H2S to sulfur and sulfuric acid. However, the process is energy intensive and emits CO2 and SO2. This calls for more sustainable and energy-efficient H2S conversion technologies. In particular, recent technologies for H2S conversion via thermal, biological, plasma (thermal and non-thermal), electrochemical and photocatalytic routes, are critically reviewed with respect to their strengths and limitations. Besides, the potential of diversified value-added products derived from H2S, such as H2, syngas, carbon disulfide (CS2), ammonium sulphate ((NH4)2SO4), ammonium thiosulfate ((NH4)2S2O3), methyl mercaptan (CH3SH) and ethylene (C2H4) are elucidated in detail with respect to the technology readiness level, market demand of products, technical requirements and environmental impacts. Lastly, the technological gaps and way forward for each technology are also outlined

A NEW METHOD FOR IN SITU ANALYSIS OF CARBON DIOXIDE ABSORPTION IN AQUEOUS MONOETHANOLAMINE BY RAMAN SPECTROSCOPY

Aqueous phase characterization and thermodynamic modeling are important for designing and operating C02 capture systems, thus accurate determination of equilibrium of C02 in aqueous amine is of major interest. Many studies have been conducted on vapor liquid equilibria based on pressure change, but analysis on the liquid phase speciation is relatively scarce

A NEW METHOD FOR IN SITU ANALYSIS OF CARBON DIOXIDE ABSORPTION IN AQUEOUS MONOETHANOLAMINE BY RAMAN SPECTROSCOPY

Aqueous phase characterization and thermodynamic modeling are important for designing and operating C02 capture systems, thus accurate determination of equilibrium of C02 in aqueous amine is of major interest. Many studies have been conducted on vapor liquid equilibria based on pressure change, but analysis on the liquid phase speciation is relatively scarce