Gas Plant Research Articles

Interfacial tension measurements of methane + propane binary and methane + propane + n-heptane ternary mixtures at low temperatures

The interfacial tension (IFT) between a liquid and a gas is essential in the design of liquid-gas separators as it determines the size of liquid droplets which can become entrained in the gas phase. In liquefied natural gas (LNG) plants, the scrub column is designed to remove components heavier than propane. However, if this column is poorly designed, these heavier components can carry over in the top product and potentially cause a solids formation problem in the main cryogenic heat exchanger. Therefore, accurate measurements and predictions of IFT are required to ensure good separation of heavy components prior to the liquefaction of the natural gas. In this work, reference-quality IFT measurements of methane + propane binary mixtures and methane + propane + n-heptane ternary mixtures were conducted at low temperatures (204 to 230) K and pressures up to the mixtures’ critical points using the differential capillary rise method in a high-pressure visual sapphire cell. The combined standard absolute uncertainties of the measured IFT were between (0.04 and 0.96) mN·m−1. The absolute deviations of measured IFT from values predicted with a Parachor model were within 3 mN⋅m−1, while a Linear Gradient Theory model over predicts mixtures’ IFT by up to 5.2 mN⋅m−1. The reference-quality IFT experimental data provided by this work should facilitate improvements of prediction models and allow separators in LNG plants to be designed with more confidence.

Is the ETS an effective environmental policy? Undesired interaction between energy-mix, fuel-switch and electricity prices

We consider the optimal energy-mix decision for the electricity sector subject to an emission trading system (ETS) under uncertain demand. Under the assumption that power producers maximize the expected profit of their sector, we show that an ETS introduces weird effects to the emission reduction target. On one hand, in terms of generation merit order, it certainly favors fuel switching between coal and gas plants. However, in the long run, the ETS hinders the expansion of renewable technology capacity, rather than promoting it. Moreover, expected emissions increase with respect to a business-as-usual scenario. Moreover, our analysis shows that under certain conditions, not unusual in real life, the equilibrium price of emission certificates is not just the expectation of a payoff for a binary option. A third value is possible. It coincides with the price that makes generation by coal- or gas-fired plants indifferent.

Design of Pile Foundation for Distillation Column

Abstract Equipment foundation is one of the most critical facility in every petrochemical, fertilizer, oil and gas plants. This equipment comprises distillation columns, vertical vessels, horizontal vessels, high pressure exchangers, reactors etc. Out of this equipment, distillation column is one of the most critical equipment due to its large diameter and height hence resulting into heavy dead load and heavy transverse loads at the base of column. Hence proper foundation system should be designed to cater all these loading without affecting the strength and serviceability of the foundation system. In most of the cases due to poor bearing capacity of soil one need to go for pile foundation. This paper summarizes the Indian code and process industry practices, design loads and load combinations to be adopted for design of pile foundation. One sample example is solved to evaluate the no of piles for column foundation by assuming suitable loading and vessel data.

Human factor analysis and classification system for the oil, gas, and process industry

AbstractHuman error can cause severe problems in industrial oil, gas, and chemical processes. Although human factors analysis and classification systems (HFACSs) for the oil and gas industry (HFACS‐OGI) and the small‐scale chemical industry (HFACS‐CSMEs) have been independently developed, there are some limitations in providing detailed information on the contributing factors. Therefore, a new HFACS must be developed that can be commonly applied to the oil, gas, and chemical fields. This paper develops an integrated HFACS that can be applied to the oil, gas, chemical, and power plants, called HFACS‐OGAPI, by analyzing 45 accidents that occurred in domestic and overseas oil, gas, chemical, and power plants, based on the HFACS‐OGI system. An integrated HFACS‐OGAPI that can be applied to the oil, gas, chemical, and power plants is developed. The framework effectively identifies the contributing factors by providing specific information on Tiers 1, 2, 3, and 4 for Levels 1, 2, 3, 4, and 5. The contributing factors are effectively identified by analyzing the BP Texas Refinery explosion (2005), the Kleen Energy natural gas explosion (2010), and the Aghorn Operating Waterflood Station accidents (2019) with the developed framework. A checklist suitable for the HFACS‐OGAPI is developed by considering the contents developed by the National Aeronautics and Space Administration and the Department of Defense to determine the contributing factors. The developed checklist is expected to effectively identify and improve on the causes of human error through periodic inspection.

Combining life cycle sustainability assessment and fuzzy multicriteria decision making method for prioritizing the flare technologies in the oil, gas, and chemical plants

AbstractLife cycle sustainability assessment (LCSA) of flare technologies can assist the stakeholders/decision‐makers to choose the most sustainable flare technology in life cycle outlook among multiple options. This article purposes in developing a framework of life cycle sustainability decision‐support for prioritizing the flare technologies by integrating the LCSA concepts and fuzzy multicriteria decision making (MCDM) method. A novel fuzzy MCDM (FMCDM) technique that can handle linguistic variables in the decision‐making matrix was progressed by integrating SWARA–WASPAS approach and fuzzy evaluation (fuzzy SWARA–fuzzy WASPAS). Using fuzzy SWARA is obtained the weights of the metrics for LCSA and then, fuzzy WASPAS is employed to prioritize the alternatives with considering the metrics. Finally, the findings of fuzzy SWARA show the “Production cost,” having the topmost weight with value of 0.5094, is the foremost metric that overshadows the choice of suitable and sustainable flare technology. The results obtained from the fuzzy WASPAS suggest that “Steam‐assisted flare,” is the highest prioritized and thus, the most significant alternative to employ flare technology in oil, gas, and chemical plants. The results indicate that combining LCSA and MCDM can effectively rank industrial systems and equipment under data uncertainties.

Performance evolution of industrial radiant syngas cooler with radiation screens using numerical simulation

AbstractRadiant syngas cooler (RSC) is an important piece of equipment for heat recovery and steam generation in the gasification plant. In this work, the industrial RSC model of an opposed multi‐burner coal‐water‐slurry gasification device is established, and the heat recovery performance of RSC is studied by numerical simulation method. The simulation result of the total heat transfer rate is compared with the industrial operation data. The effect of different operating parameters on RSC is further studied, including the operating load, inlet syngas temperature, and ash deposition thickness. The results show that there is a spindle‐shaped high‐temperature zone on the circumferential membrane wall surface with a distance of 6.5 m from the top under the basic operating conditions. There is also an obvious high‐temperature zone in the mid‐upper section of the fire side for the radiation screen. When the operating load decreases from 100% to 60%, the outlet syngas temperature decreases by 167 K, and the steam output decreases by 22%. The influence of inlet syngas temperature on outlet syngas temperature and steam output is approximately linear. For every 10 K drop of inlet syngas temperature, the outlet syngas temperature decreases by 10 K, and the steam output decreases by 0.91 × 103 kg/h. With the increase of the ash deposition thickness, the surface temperature and heat flux of the water wall rise and the outlet syngas temperature increases, while the steam output decreases. The research provides guidance for the design and stable operation of RSC in the radiation‐quenching gasification process.

Elevated CO2 effect on the response of stomatal control and water use efficiency in amaranth and maize plants to progressive drought stress

Rising CO2 concentration ([CO2]) in the atmosphere may modulate the response of crop plants to drought stress. This study aimed to investigate the response of leaf gas exchange and plant growth of two C4 species representing both dicot (amaranth) and monocot (maize) to progressive drought under two different [CO2] (ambient (a[CO2], 400 ppm) and elevated (e[CO2], 800 ppm)). The soil water status in the pots was expressed as the fraction of transpirable soil water (FTSW). The results showed that as compared to a[CO2], e[CO2] significantly increased net photosynthetic rate (An) at non-stress condition (An max) for both species, while the increase was more pronounced in maize than in amaranth. Stomatal conductance (gs) at non-stress condition was significantly lower at e[CO2] in both species. The FTSW threshold, at which An starts to decrease, was higher in maize grown at e[CO2] than at a[CO2], whereas it was not affected in amaranth. In both species, gs decreased at higher FTSW threshold when grown at e[CO2] than at a[CO2]. e[CO2] decreased stomatal density (SD) in amaranth but increased it in maize; drought increased SD in amaranth but not in maize. Intrinsic water use efficiency (WUEi) was significantly enhanced by e[CO2] and drought stress at FTSW ranged from 0.0 to 0.6, particularly in maize. e[CO2] increased leaf area of well-watered plants in maize and decreased specific leaf area in amaranth. In amaranth, water consumption of well-watered plants was increased and plant WUE was decreased at e[CO2]. The varied responses of leaf gas exchange and WUE to soil water deficits and e[CO2] among the two C4 species imply their different mechanisms in stomatal control over carbon gain versus water loss in dicot and monocot plants, which is essentially important for selecting crop species and developing strategies to optimize crop WUE in a future drier and CO2-enriched climate. The more physiological and biochemical response from soil, stomatal to plant scale related to various environments would be considered in further investigation.

Principal component analysis and partial least square regression models to understand sorption-enhanced biomass gasification

Gasification represents a potential technology for the conversion of biomass into usable energy. The influence of the main gasification parameters, i.e. the type of biomass used and its composition, as well as the composition of the outlet gas, were studied by a multivariate statistical analysis based on principal component analysis (PCA) and partial least square (PLS) regression models in order to identify the main correlations between them and to the contents of methane, ethylene and tar in the outlet gas. In this work, the experimental data used as input for the multivariate statistical analysis came from a TRL-4 gasification plant running under sorption enhanced conditions, i.e. using steam as the gasifying agent and CaO as the bed material. The composition of the biomass feed played an important role in the quality of the outlet gas composition. In fact, biomasses with high ash and sulphur contents (municipal solid waste) increased ethylene content, while those with high-volatile matter content and fixed C content (wood pellets, straw pellets and grape seeds) mainly increased CO and CO2 formation. By increasing the gasification bed temperature and the CaO/C ratio, it was possible to reduce the methane and the collected tar contents in the outlet gas. Other light hydrocarbons could also be reduced by controlling the Treactor and TFB. Methane, ethylene and tar contents were modelled, cross-validated and tested with a new set of samples by PLS obtaining results with an average overall error between 8 and 26%. The statistically significant variables to predict methane and ethylene content were positively associated to the thermal input and negatively to the CaO/C ratio. The biomass composition was also remarkable for both variables, as mentioned in the PCA analysis. As far as the tar content, which is undesirable in all gasification processes, the decrease in the tar content was favoured by high bed temperature, low thermal input and biomass with high-volatile matter content. In order to produce an outlet gas with adequate quality (e.g. low tar content), a compromise should be found to balance average bed temperature, sorbent-to-mass ratio, and ultimate and proximate analyses of the biomass feed.Graphical abstract

Air Pollution Resulted from Coal, Oil and Gas Firing in Thermal Power Plants and Treatment: A Review

Air pollution is a worldwide and a local issue caused by energy generation. It refers to global warming deterioration in human environmental health and local-global sustainability. This review provides information on the generation and consumption of energy with their air pollution mixture of many pollutants; gases, liquids and particles. These pollutants have become one of the leading environmental hazards to human and planet health. The components of pollutants that result from burning fossil fuels (oil and gas) and coal have been studied, such as sulfur dioxide, carbon dioxide, nitrogen oxides and particles. Both sulfur dioxide and nitrogen oxides interact with water to produce acid rain. Both gas and oil-fired thermal power plants emission today and in the future might be transformed to work on renewable energy sources. The results stated that gas-fired power plants are more generally faster efficient, less pollution than oil and coal power plants. A complete assessment of exhaust gas treatment was conducted. Carbon dioxide capture, desulfurization, denitrification, and particle collection were all successful as treatment control mechanisms. So, previous studies presented some methods for reducing nitrogen oxides and sulfur oxides through water injection and exhaust gas recycling. The addition of nano-additives in diesel emulsion fuel (W/D) has recently been shown to increase the characteristics and performance of the fuel while reducing the quantity of emitted hydrogen chloride (HC) and carbon monoxide (CO). It was determined that the best nano-additives for W/D were Aluminum Oxide (Al2O3), copper(ii) oxide, magnesium oxide (MgO), manganese oxide (MnO), and zinc oxide (ZnO), among others (E10).

Integration of membrane technology for decarbonization of gasification power plants: A techno-economic and environmental investigation

• Integration of membrane technology for decarbonization of gasification power plants. • Techno-economic and environmental assessment of decarbonized gasification plants. • Membrane-based CO 2 capture system increases the overall plant energy efficiency. • Membrane reduces capital cost (9%), operational cost (10%) and electricity cost (7%). • Decarbonized gasification plants are economic viable for current 75 €/t carbon tax. Membrane technology is one promising technology for CO 2 capture from industrial gases. The application of membrane system in gasification-based power plants is particularly appealing considering the elevated pressure of syngas subject to decarbonization resulting in lower energy and economic penalties for CO 2 capture. As key novelty element of this work, the membrane technology was evaluated in both alone and hybrid configuration with gas-liquid absorption in view of decarbonization of Integrated Gasification Combined Cycle power plants. Assessed decarbonized gasification-based power plant concepts produce about 450 MW net output with 90% CO 2 capture rate. An integrated techno-economic and environmental evaluation methodology (based on modelling, simulation and process integration) was applied to quantify the most important plant performance indicators. For comparison, similar IGCC designs without decarbonization feature or with decarbonization by chemical and physical gas-liquid absorption were also analysed. The overall conclusion is that the membrane technology has important techno-economic benefits in comparison to chemical and physical absorption e.g. greater overall net energy efficiency (up to about one net percentage point), lower specific capital investment costs (down to 9%), lower operational & maintenance costs (down to 10%), lower electricity production costs (down to 7%), lower CO 2 capture costs (down to 50%).

Mineralogical Characterization of Gasification Ash with Different Particle Sizes from Lurgi Gasifier in the Coal-to-Synthetic Natural Gas Plant.

The Lurgi gasifier in China is one of the most suitable technologies to produce synthetic natural gas (SNG) from coal; however, a large amount of byproduct ash is discharged during the Lurgi gasification process, causing many environmental problems. Based on ash samples collected from a commercial Lurgi gasifier in a Chinese coal-to-SNG plant, this paper studied the mineral composition and microscopic appearance of gasification ash with different particle sizes. The typical minerals were identified and investigated by comparing them with the ash from a laboratory fixed-bed reactor. The results showed that the main high-temperature minerals in the Lurgi gasification ash with different particle sizes under the gasification condition of 4 MPa and 1100 °C were anorthite (CaAl2Si2O8), augite (CaFeSi2O6), hematite (Fe2O3), and gehlenite (Ca2Al2SiO7). As the particle size of the Lurgi gasification ash increased, the quartz content increased but the residual carbon content decreased. Additionally, the high-temperature minerals were more likely to agglomerate with fine particles of the ash. The FactSage modeling showed that calcium-bearing minerals were formed earlier than iron-bearing minerals. The high Fe2O3 content in ash hindered the transformation of calcium-bearing minerals into the high-melting-point mullite, resulting in a low ash flow temperature. Additionally, the fine ash had a relatively high content of calcium-bearing minerals which was not conducive to its utilization as an additive in cement and concrete.

Comments: The Stakes Grow Higher in Defining Green Energy

Not so long ago, defining green energy was generally straightforward: renewables. It may not have been quite that simple, but the development of agreed-upon definitions based on science has become much more complex and contentious, even within the past year. It’s not just a highbrow debate about semantics. The standardization of criteria or a widely accepted taxonomy is critical as the focus increases on not only greenwashing, but on the actual processes and technologies enabling what were thought of as at least “greener” energy. The hammering out of definitions is needed to keep the energy transition moving forward globally. This scrutiny affects the options for companies seeking alternatives in carbon markets where the price of permits for emitting a tonne of CO2 is escalating. In early February, the price of CO2 permits in the EU reached a record high above 96 Euros ($109)/tonne CO2. Reuters reported that the carbon price has risen more than 200% since the start of 2021, partly due to high natural gas prices and the switch made to coal by some power generators. This resulted in higher emissions and increased the demand for permits. In January, the EU Platform on Sustainable Finance, comprising members from utilities, banks, nongovernmental organizations, and corporations, rejected the EU Commission’s draft sustainable finance rules which proposed labeling nuclear power and natural gas as green transition fuels. Nuclear projects permitted until 2045 were to be classified as green, but only if countries can safely dispose of the radioactive waste. Gas was to be included until 2030 with emissions thresholds specified. The EU Platform concluded that even if a gas plant stays under the emissions threshold, it “is not green at any point in its life.” Nuclear energy was acknowledged as already being part of the transitioning energy system and having near to zero greenhouse-gas emissions, but it would not meet the taxonomy’s requirement to “do not significant harm” to the environment because of the toxic waste that cannot be recycled or reused. The EU Commission’s taxonomy will be sent to the European Parliament and Council for review. Blue hydrogen was questioned as a transition fuel by a peer-reviewed study published in August 2021 in Energy Science & Engineering by coauthors from Cornell and Stanford universities. They wrote, “Far from being low-carbon, greenhouse-gas emissions from the production of blue hydrogen are quite high, particularly due to the release of fugitive methane. … Perhaps surprisingly, the greenhouse-gas footprint of blue hydrogen is more than 20% greater than burning natural gas or coal for heat and some 60% greater than burning diesel oil for heat, again with our default assumptions.” They added, “Our analysis assumes that captured carbon dioxide can be stored indefinitely, an optimistic and unproven assumption. Even if true though, the use of blue hydrogen appears difficult to justify on climate grounds.” In a study published last month in the Proceedings of the National Academy of Sciences, researchers at the University of Wisconsin-Madison combined econometric analyses, land use observations, and biophysical models to estimate the realized effects of the US Environmental Protection Agency’s Renewable Fuel Standard (RFS) mandate to partially replace petroleum-based fuels with biofuels. They found that the RFS increased corn prices by 30% and the prices of other crops by 20%, which, in turn, expanded US corn cultivation by 8.7% and total cropland by 2.4% in the years following the policy’s enactment (2008 to 2016). “These changes increased annual nationwide fertilizer use by 3 to 8%, increased water-quality degradants by 3 to 5%, and caused enough domestic land use change emissions such that the carbon intensity of corn ethanol produced under the RFS is no less than gasoline and likely at least 24% higher. These tradeoffs must be weighed alongside the benefits of biofuels as decision makers consider the future of renewable energy policies and the potential for fuels like corn ethanol to meet climate mitigation goals.” The move toward energy transition has been pivotal for our industry and many others. It could be argued that no country, business, or individual will remain unaffected by the changes in progress and yet to come. “Transition” is defined as “the process or a period of changing from one state or condition to another.” And this process will take time, effort, technology, buy-in, scientific study and verification … and consensus, which may be the most challenging piece of all. A significant announcement demonstrating the application and acceptance of a scientific taxonomy was Santos Ltd.’s recent booking of 100 million metric tons of CO2 storage capacity in the Cooper Basin in South Australia. The company believes it represents the industry’s first-ever booking to be made under SPE’s CO2 Storage Resource Management System.

The Energy to Change: A Sustainable World

The world is changing every day and with increased collective awareness of the damaging effects of fossil fuels. The Public health is a key issue in India. The air and water pollution emitted by coal and natural gas plants is linked with breathing problems, neurological damage, heart attacks, cancer, premature death, and a host of other serious problems. Most of these negative health impacts come from air and water pollution. In India Global warming Emission are extracted from the electricity sectors most of those emission come from fossil fuels like coal and natural gas. Clean energy technologies could provide a solution to this problem. The Government of India has been focusing in implementing clean energy technologies. The focus of this article is to bring to light the problems faced in India in terms of energy consumption as well as the hindrances faced by clean energy-based technologies. Government policies aimed at addressing these issues, as well as the current state of clean energy technologies in India are discussed, so as to analyse the possibility of a solution to the problems of finding a sustainable method to eradicate clean energy technologies in India. The research reveals that the Government of India has been unable to meet some of its unrealistic development goals, and in order to achieve the remaining goals it will have to take drastic steps. The Government will have to be more aggressive in the promotion of clean energy technologies in order to achieve sustainable development in India.

Logic Solver Diagnostics in Safety Instrumented Systems for Oil and Gas Applications

A safety instrumented system (SIS) is a complex unit composed of a set of hardware and software controls which are expressly used in critical process systems. A SIS should be specifically designed to obtain the failsafe state of the monitored plant or maintain safety of the procedure or a process when unacceptable or dangerous conditions occur. This paper focuses on condition monitoring and different diagnostic solutions used in safety instrumented systems, such as limit alarm trips, on-board diagnostics, and logic solver diagnostics. A case study consisting of the design of a safety loop using standard IEC 61508 for a complex safety instrumented system in the oil and gas field is presented in the paper using a diagnostics-oriented approach. The presented methodology aims at reaching the optimal tradeoff between IEC 61508 and the market requirements focusing on the best technological solutions to optimize diagnostics and safety and minimize the system’s response time in case of failure. The results of the application emphasize the importance of an accurate diagnostic strategy on safety instrumented systems for oil and gas plants.

Cement substitution by sludge-biomass gasification residue: Synergy with silica fume

The increasing volumes of sewage sludge and other wastes of biological origin force the use of downdraft gasifiers for waste utilization; however, thermal processes produce residues that need to be treated in an environmentally acceptable way. The object of the study is to evaluate the possible application of residue, derived from industrial sewage sludge-biomass gasification plants, with silica fume as a partial binder substitute in cement-based materials. At total cement replacement levels of 10 and 12%, the dosages of gasification residue and silica fume varied in the range of 2–6% and 6–10% by cement mass, respectively. The impact of synergy between silica fume and gasification residue on the hydration and microstructure development of cement paste was analysed using SEM-EDS, XRD, TGA and N2 sorption methods. The synergy of wastes was found to change the morphology and assemblage of hydration products and to accelerate the consumption of portlandite. N2 physisorption revealed that the synergy of both substitutes had a significant impact on the distribution of pores in the mesoporosity range up to 30 nm, representing small microcapillary pores. The synergistic impact of the substitutes on selected properties of cement mortars was determined after 7, 28 and 56 days. Compared with the reference, all blended mortars showed 5–40% higher mechanical strength and 25–50% lower water ingress during the entire hydration period. The compressive strength increased with the reduction in the residue-to-silica fume (R/SF) ratio, while the flexural strength and sorptivity were less dependent on the ratio. The results revealed that the total cement substitution level may be increased up to 12%, within 4–6% covered by gasification residue, without losing the mechanical strength and consequently, to reduce the resources of Portland cement and silica fume.

Thermochemical Conversion of Biomass for Syngas Production: Current Status and Future Trends

The thermochemical conversion of different feedstocks is a technology capable of reducing the amount of biowaste materials produced. In addition, the gasification of feedstock using steam as a gasifying agent also produces hydrogen, which is a clean energy fuel. This article aimed to encapsulate the current status of biowaste gasification and to explain, in detail, the advantages and limitations of gasification technologies. In this review paper, different gasifying agents such as steam, air, and oxygen, as well as their effects on the quality of syngas production, are discussed. In addition, the effects of reactor configuration and different operating parameters, such as temperature, pressure, equivalence ratio, and incorporation of a catalyst, as well as their effects on the ratio of H2/CO, LHV, syngas yield, and tar production, were critically evaluated. Although gasification is a sustainable and ecologically sound biomass utilization technology, tar formation is the main problem in the biomass gasification process. Tar can condense in the reactor, and clog and contaminate equipment. It has been shown that an optimized gasifier and a high-activity catalyst can effectively reduce tar formation. However, key biowaste treatment technologies and concepts must first be improved and demonstrated at the market level to increase stakeholder confidence. Gasification can be the driving force of this integration, effectively replacing fossil fuels with produced gas. In addition, support policies are usually needed to make the integration of biomass gasification technology into the industry profitable with fully functional gasification plants. Therefore, to address such issues, this study focused on addressing these issues and an overview of gasification concepts.

The financial feasibility of compressed biomethane gas application in Thailand

BackgroundBiomethane is a clean fuel upgraded from biogas. It has similar properties to natural gas vehicle (NGV) and can be used as a substitute for fossil fuels in the transportation and industrial sectors. Currently, biomethane is not in widespread use as alternative energy because it depends on local biogas production. However, there are few replacement alternatives and the commercial system is only on a small scale. Therefore, the overall aim of this paper is to study the financial feasibility of local biogas aggregation for producing biomethane on various scales. The results of the study are expected to aid the decision-making of investors and governments in promoting the use of renewable and sustainable sources of energy.MethodsPrimary and secondary data are used in this research for descriptive and quantitative analysis, while net present value, internal rate of return, payback period, and cost per unit represent the financial instruments. The location and distance methods applied are Google Maps and Power BI software programs, based on biogas upgrading by water scrubbing.ResultsThe results indicate that 10 potential biomethane production areas exist in Thailand, with a total biogas production capacity of 6,000 m3/day or more under gas pipeline conditions not exceeding 50 km. Compressed biomethane gas plants with a capacity of less than 6 tons/day should be funded by the government at 30% of the total investment for a payback period of 5–6 years. Plants producing more than 6 tons/day provide a good return on investment even without government funding.ConclusionsWhile this study focuses solely on areas of Thailand, it is the researcher’s position that the integration of residual biogas plants provides greater benefit than flare, particularly in remote areas. The model proposed in this study can serve as a prototype for developing countries such as Malaysia, the Philippines, Latin America, etc. Furthermore, it can be used in developed countries committed to reducing greenhouse gas emissions in accordance with the Paris Agreement.

Investigation of Alkanol-Amine Solvents and their Blends for CO2 Removal from Natural Gas using Aspen-Hysys

The removal of carbon dioxide (CO2) from natural gas is vital towards meeting pipeline sales gas specifications and evading operational complications during the liquefaction of natural gas. Therefore, the removal of CO2 from natural gas is necessary for the efficient utilization of natural gas and for the reduction of global CO2 emission. It is also vital for the effective liquefaction process in the liquefied natural gas project A common and widespread technique used at natural gas plants in Nigeria is the removal of carbon dioxide (CO2) from natural gas through chemical absorption using alkanolamine solutions. In this research, an amine sweetening process is simulated using Aspen HYSYS V10 with a typical Nigerian natural gas composition. The simulation is used to investigate four different kinds of amines and their blends (mixed amines). The investigated amines are Monoethanolamine (MEA), Diethanolamine (DEA), Diglycolamine (DGA) and Methyldiethanolamine (MDEA) while the blends are MDEA + MEA, MDEA + DEA and MDEA + DGA. Results obtained from the simulation show that the mixed amine “MDEA + MEA” with lean amine strength of 11% MEA and 39% MDEA, absorbs 99.97% of CO2 present in the gas and hence, amine blends absorb carbon dioxide from natural gas better than the individual amines. It was also concluded that increasing the composition of the primary or secondary amine while decreasing the composition of the tertiary amine in the lean amine solution (amine blend) led to an increase in the amount of CO2 being absorbed. The study provides useful information on the absorption of CO2 using alkanolamine solvents and their blends in a standard amine sweetening plant.

Helium recovery and purification by dual reflux pressure swing adsorption

Global demand for helium has risen over the past few decades driven by a vast range of applications based on its unique properties. Helium is often produced industrially from the vent streams of nitrogen rejection units (NRU) in liquefied natural gas (LNG) plants, where it accumulates because of its low boiling point. Further deep cryogenic processing stages are then required to upgrade its concentration to saleable levels. We report here an experimental and simulation-based investigation of an alternative, non-cryogenic process based on dual reflux pressure swing adsorption (DR PSA) cycles to recover and purify helium from model binaries including a 1 mol% He + 99 mol% N2 mixture representative of NRU vent streams. Binderfree zeolite 13X was used as the adsorbent in an experimental campaign employing a laboratory-scale DR PSA apparatus. The experimental runs validated a non-isothermal numerical model with an average deviation of 1 mol% between the simulated and experimental product compositions. The single-stage DR PSA experiments produced helium product streams with purities ranging from (30 to 99) mol% from feeds with concentrations ranging from (1 to 50) mol% He. Two DR PSA stages were required to upgrade mixtures containing 1 mol% He to a target product purity of > 99 mol%. A cascade arrangement of two DR PSA systems with a waste recycle enabled a 99.999 mol% He purity product at 95 % recovery, which is competitive with conventional cryogenic systems. This cascade DR PSA process used either two or three compressors depending on the feed gas pressure, with associated duty costs of 1.5 MJ∙(mol He produced)–1. This is lower than several membrane processes described in the literature and could be more cost-effective for smaller-scale applications than cryogenic processes with similar levels of separation performance.

Melatonin Improves Drought Stress Tolerance of Tomato by Modulating Plant Growth, Root Architecture, Photosynthesis, and Antioxidant Defense System.

Tomato is an important vegetable that is highly sensitive to drought (DR) stress which impairs the development of tomato seedlings. Recently, melatonin (ME) has emerged as a nontoxic, regulatory biomolecule that regulates plant growth and enhances the DR tolerance mechanism in plants. The present study was conducted to examine the defensive role of ME in photosynthesis, root architecture, and the antioxidant enzymes’ activities of tomato seedlings subjected to DR stress. Our results indicated that DR stress strongly suppressed growth and biomass production, inhibited photosynthesis, negatively affected root morphology, and reduced photosynthetic pigments in tomato seedlings. Per contra, soluble sugars, proline, and ROS (reactive oxygen species) were suggested to be improved in seedlings under DR stress. Conversely, ME (100 µM) pretreatment improved the detrimental-effect of DR by restoring chlorophyll content, root architecture, gas exchange parameters and plant growth attributes compared with DR-group only. Moreover, ME supplementation also mitigated the antioxidant enzymes [APX (ascorbate peroxidase), CAT (catalase), DHAR (dehydroascorbate reductase), GST (glutathione S-transferase), GR (glutathione reductase), MDHAR (monodehydroascorbate reductase), POD (peroxidase), and SOD (superoxide dismutase)], non-enzymatic antioxidant [AsA (ascorbate), DHA (dehydroascorbic acid), GSH (glutathione), and GSSG, (oxidized glutathione)] activities, reduced oxidative damage [EL (electrolyte leakage), H2O2 (hydrogen peroxide), MDA (malondialdehyde), and O2•− (superoxide ion)] and osmoregulation (soluble sugars and proline) of tomato seedlings, by regulating gene expression for SOD, CAT, APX, GR, POD, GST, DHAR, and MDHAR. These findings determine that ME pretreatment could efficiently improve the seedlings growth, root characteristics, leaf photosynthesis and antioxidant machinery under DR stress and thereby increasing the seedlings’ adaptability to DR stress.