Conventional Natural Gas Research Articles

Study of cellulose nanocrystals -enhanced natural gas foam performance and profile control & oil displacement mechanism

ABSTRACT To address the poor performance of conventional natural gas foam flooding in the tight conglomerate reservoirs of the Mahu region in Xinjiang, a high-activity green material, cellulose nanocrystals (CNC), was introduced to improve foam performance based on a conventional AOS+SDS foam system. However, the impact of CNC on the performance of the conventional foam system and the synergistic effects between CNC and surfactants are not yet clear. Therefore, this study evaluates the improvement effects of CNC on foam performance from both macroscopic and microscopic perspectives by analyzing the foam composite index and the synergistic effects between CNC and surfactants. The study also investigates the factors affecting foam performance and uses a planar visualization model to evaluate the enhanced gas foam flooding effects from a microscopic mechanism perspective. The results indicate that CNC increases the foam composite index by 26,850 mL·min on a macroscopic level. Microscopically, it makes the foam more compact, thickens the foam liquid film by 0.1 mm, improves the wettability reversal by 10%, and reduces the oil-water interfacial tension by 0.26 mN/m. After mixing 1 vol% crude oil, the foam volume and half-life decrease by 12% and 4%, respectively. At reservoir temperature and pressure, the foam volume decreases by 12.7% and 10.5%, but the half-life increases by 4 hours and 3.7 hours, respectively. At formation water mineralization conditions, the foam volume and half-life decrease by 6.6% and 1.7 hours, respectively. In summary, it still has good performance under reservoir conditions. The visualization model demonstrates from a microscopic perspective that the foam system has good gas shutoff capability. After foam flooding, the gas sweep efficiency increases by 54.12%, and the foam flooding and subsequent gas flooding improve the crude oil recovery by 20.32%.

Energetic and economic analysis of a novel concentrating solar air heater using linear Fresnel collector for industrial process heat

Industrial processes share a relevant portion of global energy consumption. A large variety of high energy-demanding industrial processes need hot air in the medium temperature range, provided by natural gas combustion or by electricity. Hot air is used as a medium in a large variety of processes such as drying, curing, and thermal treatments of several products and materials. Heat can be provided by solar thermal technologies aimed at the sustainable industry. Non-concentrating flat plate type solar collectors can directly heat air up to 100 °C while higher temperatures can be achieved using linear concentrating technology. In this study an innovative system using linear Fresnel collectors directly provides hot air for the industry up to 350 °C, avoiding the need for liquid heat transfer fluids. Accordingly, the installation is simplified, and lower installation and maintenance requirements are expected compared to other solar technologies. The present studies provide an energetic and economic analysis of the concentrating solar air heater, considering a medium-scale benchmark as a reference case in representative European locations. The results indicate that the solar technology here presented can be economically competitive with conventional natural gas heating, having a huge potential for fossil fuel source replacement in hot air based industrial processes.

Natural gas accumulation conditions and exploration directions of Carboniferous clastic rocks in the northeastern margin of Junggar Basin, China

The Carboniferous strata in the northeastern Junggar Basin are an important exploration field for natural gas in the basin. However, volcanic rocks have long been the primary exploration target. In contrast, the exploration and research of clastic rocks associated with source formations have been largely overlooked, resulting in an insufficient understanding of the reservoir forming conditions and exploration potential of Carboniferous clastic rocks. Through the evaluation of Carboniferous source rocks, effective source stove characterization, clastic reservoir evaluation, oil and gas source correlation, and reservoir formation model construction in this region, three key findings have been made. First, the Carboniferous in the northeastern Junggar Basin has developed three sets of high-quality gas source rocks: the Dishuiquan Formation, the Songkalsu B Member, and the Shiqiantan Formation. These formations correspond to three hydrocarbon source centers: the Sannan–Dishuiquan Sag, the Wucaiwan Sag–Dajing area, and the Dongdao Haizi Sag–Baijiahai High. Second, the Carboniferous system in the northeast has developed multiple types of large-scale reservoirs, including sand conglomerates, sandstones, turbidites, dolomitic rocks, and shale. These reservoirs are generally characterized by low porosity to ultra-low porosity and low permeability to ultra-low permeability reservoirs. There is a dissolution pore development zone at depths of 2900–4500 m. Third, a comparison of oil and gas sources reveals that all three sets of gas source rocks contribute to the natural gas found in the northeast, with obvious characteristics of near-source reservoir formation. The Carboniferous clastic rocks host two types of natural gas reservoirs: unconventional and conventional near-source reservoirs. It is predicted that there is an orderly accumulation pattern of shale gas, tight sandstone gas, and conventional natural gas reservoirs. This study reveals that the Carboniferous clastic rock source and reservoir configuration in the northeastern Junggar Basin is highly favorable, and the natural gas reservoirs in source and near-source clastic rocks represent important exploration directions.

Performance assessments of ground source heat pump assisted by various solar panels to achieve zero energy buildings in cold climate conditions

This paper aims to perform a comprehensive performance analysis of a solar-assisted ground source heat pump (SAGSHP) system connected to various types of solar panels to enhance overall energy efficiency. While previous studies have examined integrating solar panels with heat pumps, comprehensive solutions like those presented here and performance evaluations in the zero energy building context have been lacking. This study developed various scenarios using three types of solar panels, photovoltaic (PV), photovoltaic-thermal (PVT), and solar thermal collectors (ST), to explore their simultaneous use. TRNSYS software was employed to analyze the complex system, comparing it to a conventional natural gas boiler system as a baseline. The findings revealed that the on-site energy use intensity (EUI) decreased from 78.6 kWh/m2 to 53.3 kWh/m2, a reduction of approximately 33 %, due to the SAGSHP's implementation. The combination of PVT and PV panels emerged as the most suitable option for the SAGSHP, aligning with the net zero energy concept. The SAGSHP system achieved a low EUI of 10.4 kWh/m2 in terms of primary energy. Additionally, the solar fraction, indicating the proportion of solar energy used, reached approximately 90 %. Thus, this study underscores the significance of evaluating various solar panel configurations during the preliminary design phase of SAGSHP systems to optimize energy performance and progress toward zero energy buildings.

Assessment of Greenhouse Gas Emissions isplaced by Molten Salt Storage in CSP Plants Compared to Conventional Power Plants

Molten salts are the most widely used thermal energy storage system in Concentrated Solar Power (CSP) plants, accounting for 50% of the installed capacity. Many studies have conducted life cycle assessments of the Greenhouse Gas (GHG) emissions produced within the CSP ecosystem; however, it has not yet been standardized for molten salt storage. This study compares GHG emissions of molten salt storage in CSP with conventional coal and natural gas power plants, to measure the environmental impact they can have in the CSP ecosystem. This was achieved with the use of simulations for 48 operational CSP plants worldwide using the system advisor model with their respective operation conditions. Results show that for the three configurations studied, CSP plants would result in annual 3,99 MMtCO2eq of emissions displaced when compared to a coal power plant and 1,61 MMtCO2eq compared to a natural gas power plant.

Life cycle-based multi-objective model for optimal gaseous fuel generation and portfolio allocation in gas grids: A strategic decarbonization

Biomethane and hydrogen are acknowledged as transformative opportunities for decarbonizing the conventional gas grid. Essential to this transformation is the modeling of the gaseous fuel supply chain, particularly with hydrogen and biomethane, offering crucial insights for decision-makers. This study introduces a life cycle thinking-based multi-objective optimization model for the integrated design of biomethane and hydrogen gaseous fuel supply chain networks. The model determines optimal resource allocation for the production of the two fuels, integrating them into the conventional gas network. Moreover, it allocates conventional natural gas, biomethane, and hydrogen optimally across building, industry, and transport sectors, considering the life cycle environmental and economic performance of fuel integration paths. Objective functions include minimization of life cycle emissions and levelized cost of energy while maximizing revenue from fuel sales. Integrating life cycle assessment and cost analysis tools, the optimization model quantifies emissions and life cycle costs for biomethane and hydrogen paths. Results identify Pareto-optimal fuel production paths and portfolios, revealing that integrating the alternative fuels into the current gas grid can significantly reduce emissions (up to 250 tonCO2eq/year) and generate substantial carbon tax savings (up to $16,250/year). This model is useful for gaseous fuel industry stakeholders, offering a comprehensive view of supply chain costs and detailed insights into emission benefits when integrating alternative fuels into existing gas networks.

End-Member Mixing Model for Methane Carbon Isotope Fractionation During Shale Gas Desorption and Its Application.

Unlike conventional natural gas reservoirs, shale gas development involves systematic changes in methane carbon isotopes that cannot be effectively described by existing isotope fractionation models and mechanisms. Therefore, based on fundamental theories such as Rayleigh fractionation, mass transfer flow, and mass conservation, this study established isotopic fractionation equations for methane in adsorbed and free gas. By considering adsorbed and free gases as two end-members and using an isotope mixing model, a fractionation model for methane carbon isotopes during shale gas desorption was constructed. This model quantifies the isotopic fractionation effects during shale gas desorption and elucidates the mechanism of methane carbon isotope fractionation. Using on-site desorbed gas content and isotope data, parameter fitting and model calculations were conducted to characterize methane carbon isotope variations throughout the process of shale core field desorption. The results show a pattern of "initially negative and then turning positive," consistent with those of physical simulation experiments. It was clarified that differences in mixing the two end-members and isotopic fractionation play key roles in the variation of methane carbon isotopic composition in shale gas. By applying the methane carbon isotope fractionation model, the contribution of adsorbed gas during shale gas production was explored. It was found that in the early stage of development, the adsorbed gas in Well JY 1 was negligible. After nearly seven years of development, the contribution of adsorbed gas in the later stage has only reached nearly 15%, indicating that the production contribution of adsorbed gas is still less than 0.3 million cubic feet per day. The open flow of Well JY 6-2 is more conducive to the production of adsorbed gas, but the production capacity is still mainly contributed by free gas, indicating that the shale gas production capacity in the later stage in the Jiaoshiba gas field is still primarily dominated by free gas.

Progress, Challenges, and Strategies for China’s Natural Gas Industry Under Carbon-Neutrality Goals

In recent years, the Chinese government has introduced a series of energy-saving, emission-reducing, and environmentally protective policies. These policies have gradually decreased the proportion of high carbon-emitting energy consumption, such as coal, in China’s energy structure. The proportion of natural gas consumption as a clean energy source has been increasing year by year. In the future, with the deepening decarbonization of the energy structure, the applied scope of natural gas utilization will expand, increasing demand. Therefore, this study first evaluated the development of China’s natural gas industry from the perspectives of development evolution, technological applications, and industry achievements. Secondly, based on the current situation of conventional and unconventional natural gas development, both resources and technological potential were analyzed. By taking several typical projects in the natural gas industry as examples, medium- and long-term prospects for natural gas development were planned and predicted. Building on this analysis, we employed the SWOT method to examine the development prospects of China’s natural gas industry and propose development goals. Finally, based on top-level design considerations and previous research analysis, suggestions and measures were proposed for technology implementation, regional layout, industrial chain collaboration, and support policies. These recommendations aim to provide planning support and management references for the development of China’s natural gas industry.

Exploring the role of hydrogen in decarbonizing energy-intensive industries: A techno-economic analysis of a solid oxide fuel cell cogeneration system

Industry is nowadays one of the most energy-demanding sectors representing a major contributor of global greenhouse gas emissions. The simultaneous need for electricity and high-temperature heat is what makes some industrial processes difficult to decarbonize via current commercially available technologies. As the demand for materials and goods is expected to grow in the upcoming years, it is crucial to define which strategies and technologies will serve as the cornerstone of sustainable development. This study addresses the imperative need for emission reduction of energy-intensive sectors by proposing a novel hydrogen-based cogeneration system in the framework of the paper and pulp industry, with the aim of providing general insights relevant to a broader spectrum of similar applications. The comparative analysis presented in this work focuses on three cogeneration options aimed at satisfying the paper mill energy needs: a conventional natural gas-fuelled gas turbine, a Solid Oxide Fuel Cell (SOFC) fed with grey hydrogen produced via steam methane reforming, and a SOFC operating using green hydrogen produced on-site. The latter involves an integrated multi-energy system with photovoltaic panels, electrolyzers, compressors, and storage tanks. Indeed, the SOFC potential of supplying electricity and high-temperature heat in the form of pressurized steam for industrial applications has not been well investigated yet and represents one of the main objectives of this work. Building on the real consumption profiles of a paper mill facility, techno-economic analyses are carried out for many system configurations, varying components size and layout to assess their performance with respect to CO2 emissions and two key economic parameters, the Levelized Cost of Hydrogen (LCOH) and the net present cost. An in-house-developed flexible simulation framework is presented and expanded for the purposes of this study, including a detailed model that accounts for design and off-design performance of a SOFC cogeneration unit. Results demonstrate that integrating a SOFC with a heat recovery steam generator result in a 75% reduction in the mass flow of generable pressurized steam in comparison to a gas turbine. Additionally, in the cost-optimal scenario, CO2 emissions are 25% lower than the conventional gas turbine-based configuration, achieving complete independence from the electricity grid and an LCOH of 5.81€/kg without considering revenues from electricity sold.

Techno-economic and environmental analysis of hybrid energy systems for remote areas: A sustainable case study in Bangladesh

This study provides a comprehensive evaluation of the techno-economic and environmental performance of six hybrid energy systems (HESs) in Kunder Char, Bangladesh, incorporating both conventional (diesel and natural gas) and renewable energy sources (solar and wind). Using HOMER Pro software, a comparative analysis of five off-grid systems and one on-grid system are conducted for assessing their cost-effectiveness, energy efficiencies, and environmental impacts under various sensitivity conditions. After thorough evaluation the on-grid system has emerged as the most economically viable option, with a levelized cost of energy (LCOE) of $0.0436/kWh and a net present cost (NPC) of $1.43 million. It also produced minimal waste energy (0.381 %) but with high CO2 emissions. In contrast, the PV-Battery setup, though the most expensive with an LCOE of $0.266/kWh and an NPC of $3.36 million, offered the benefit of zero emissions and generated 40 % excess electricity. Sensitivity analyses highlighted the influence of solar radiation (4.45 kWh/m2/day), wind speed (4.81 m/s), and fuel price (Diesel: $1/L) on these systems, providing insights into their operational dynamics under varying environmental and economic scenarios. The findings highlight the trade-offs between cost, sustainability, and efficiency, promoting energy solutions customized to meet the specific needs of remote regions like Kunder Char. This study also helps in understanding the potential of hybrid systems to meet energy demands sustainably in challenging geographical and economic landscapes.

Emulsification characteristics and dehydration of shale oil emulsions under high-frequency electric field

In the face of depleting conventional oil and natural gas reserves, the exploitation of shale oil resources increasingly important. However, the high stability of shale oil emulsions presents a significant challenge to its extraction. In this paper, the differences between shale oil and conventional crude oil and the reasons for the stability of shale oil emulsions were explored. In addition, different dehydration technologies for shale oil emulsions were compared and optimum operating parameters were determined through laboratory-scale experiments. The results show that shale oil emulsions contain much smaller droplets (< 2.25 μm) compared with conventional crude oil emulsions. Further, the high wax content of shale oil allows it to form a high-strength interfacial film at the oil-water interface under the combined action of fracturing fluids and natural emulsifiers, making the emulsion highly stable. Demulsification experiments showed that the use of high-frequency alternating current (AC) pulsed electric fields is an effective method for breaking shale oil emulsions. The optimal demulsification parameters were found to be an electric field frequency of 4 kHz, a field strength of 150 kV·m-1, a residence time of 50 min, an operating temperature of 55 °C, and a demulsifier concentration of 100 ppm. Under these conditions, the dehydrated shale oil was able to meet the standards for commercial crude oil.

Co-feeding biomass and municipal solid waste for enhanced hydrogen and synthetic natural gas yields employing chemical looping process

Synthetic natural gas (SNG) is a promising alternative to conventional fossil natural gas. This study proposes a chemical looping hydrogen production (CLHP)-based route for SNG synthesis and elucidates the insights and necessities of appropriately co-feeding different types of feedstocks to maximize the yields of hydrogen and subsequent SNG. A study employing microalgae (MA) and refuse-derived fuel (RDF) as biomass and municipal solid waste representatives demonstrates that blending MA with RDF in a proportion of 40 %:60 % (0.4MA-0.6RDF) eradicates oxygen carrier splitting. This boosts fuel-to-hydrogen efficiency from 74.1 % to 77.8 %, as well as subsequent thermal and exergy efficiencies of SNG production from 59.07 % and 55.8 % to 61.3 % and 57.92 %, respectively, compared to the use of MA alone. Nonetheless, blending fuels does not yield substantial economic advantages, as evidenced by the levelized cost of SNG production using pure MA and the 0.4MA-0.6RDF blend remaining at approximately 0.63 USD/Nm3.

Gas Fracturing Simulation of Shale-Gas Reservoirs Considering Damage Effects and Fluid–Solid Coupling

With the increasing demand for energy and the depletion of traditional resources, the development of alternative energy sources has become a critical issue. Shale gas, as an abundant and widely distributed resource, has great potential as a substitute for conventional natural gas. However, due to the low permeability of shale-gas reservoirs, efficient extraction poses significant challenges. The application of hydraulic fracturing technology has been proven to effectively enhance rock permeability, but the influence of environmental factors on its efficiency remains unclear. In this study, we investigate the impact of gas fracturing on shale-gas extraction efficiency under varying environmental conditions using numerical simulations. Our simulations provide a comprehensive analysis of the physical changes that occur during the fracturing process, allowing us to evaluate the effects of gas fracturing on rock mechanics and permeability. We find that gas fracturing can effectively induce internal fractures within the rock, and the magnitude of tensile stress decreases gradually during the process. The boundary pressure of the rock mass is an important factor affecting the effectiveness of gas fracturing, as it exhibits an inverse relationship with the gas content present within the rock specimen. Furthermore, the VL constant demonstrates a direct correlation with gas content, while the permeability and PL constant exhibit an inverse relationship with it. Our simulation results provide insights into the optimization of gas fracturing technology under different geological parameter conditions, offering significant guidance for its practical applications.

Effects of leucine on hydrate formation: A combined experimental and molecular dynamics study

Compared to conventional natural gas storage and transportation methods, hydrates offer a safer, more compact alternative with broad future potential. To enhance hydrate formation, there has been considerable interest in environmentally friendly and cost-effective amino acid promoters, such as leucine. This study utilized a transparent vessel for CH4 hydrate formation experiments, identifying the optimal 0.5–0.6 wt% leucine concentration, which led to enhanced gas consumption, shorter induction time, and maximum gas storage density. In the leucine system, hydrates exhibited distinctive branching growth on container walls, both upward and downward. The formation of numerous microchannels amplified capillary effects, enhancing gas–liquid contact and fostering hydrate formation. Simultaneously, isobaric-isothermal molecular dynamics (MD) simulations integrated system growth configurations, structural parameters, radial distribution functions, energy barriers and mean square displacements, unveiling leucine’s microscopic impact on hydrate formation. Simulation results unequivocally show that leucine significantly accelerates CH4 hydrate growth by momentarily adsorbing at the solid–liquid interface, expediting water molecule ordering into cage-like structures. Leucine also enhances water molecule structural order around the mobile leucine molecule. Moreover, leucine lowers the energy barrier for methane transitioning from gas to liquid, facilitating gas molecule diffusion into the liquid phase and affording plenty interaction time for water and methane molecules, thereby providing favorable conditions for hydrate formation. These findings provide crucial perspectives for future research in the field of eco-friendly hydrate promoters, paving the way for innovative solutions in natural gas storage and transportation.

In Situ Gas Content Prediction Method for Shale.

Shale gas is a typical unconventional energy source and recently has received great attention around the world. Unlike conventional natural gas, shale gas mainly exists in two forms: free state and adsorbed state. Therefore, geologists have proposed the concept of gas content. The traditional calculation methods of gas content can be summarized as on-site gas desorption, logging interpretation, isothermal adsorption, and so on. However, all of the methods mentioned above have their shortcomings. In situ gas content is a new concept in the calculation of the gas content. In this paper, the in situ gas content is defined as the gas content obtained by direct measurement of core gas production through experimental or mathematical simulation of original reservoir conditions. In this work, a method to calculate the in situ gas content of shale is provided, which includes two parts: numerical simulation of the coring process and a gas content experiment. Compared with previous gas content prediction methods, this article considers the influence of the temperature field on gas content both in mathematical modeling and experiments. Then, the gas content of the Longmaxi Formation shale in the Sichuan Basin was calculated using both methods as an example. The results show that (1) the numerical model was considered to be reliable by analyzing the effects of coring speed and permeability on the loss of gas; (2) the total gas content predicted by numerical simulation of the coring process and the gas content experiment are approximately equal, with values of 5.08 m3/t and 4.95 m3/t, respectively; (3) the total gas content of the USBM method is only 4.28 m3/t, which is significantly lower than the above methods. In summary, this study provides an in situ gas content prediction method for shale from both mathematical modeling and experiments. The mutual verification of theory and experiment makes this method highly reliable.

Thermodynamically Efficient, Low-Emission Gas-to-Wire for Carbon Dioxide-Rich Natural Gas: Exhaust Gas Recycle and Rankine Cycle Intensifications

Onshore gas-to-wire is considered for 6.5 MMSm3/d of natural gas, with 44% mol carbon dioxide coming from offshore deep-water oil and gas fields. Base-case GTW-CONV is a conventional natural gas combined cycle, with a single-pressure Rankine cycle and 100% carbon dioxide emissions. The second variant, GTW-CCS, results from GTW-CONV with the addition of post-combustion aqueous monoethanolamine carbon capture, coupled to carbon dioxide dispatch to enhance oil recovery. Despite investment and power penalties, GTW-CCS generates both environmental and economic benefits due to carbon dioxide’s monetization for enhanced oil production. The third variant, GTW-CCS-EGR, adds two intensification layers over GTW-CCS, as follows: exhaust gas recycle and a triple-pressure Rankine cycle. Exhaust gas recycle is a beneficial intensification for carbon capture, bringing a 60% flue gas reduction (reduces column’s diameters) and a more than 100% increase in flue gas carbon dioxide content (increases driving force, reducing column’s height). GTW-CONV, GTW-CCS, and GTW-CCS-EGR were analyzed on techno-economic and environment–thermodynamic grounds. GTW-CCS-EGR’s thermodynamic analysis unveils 807 MW lost work (79.8%) in the combined cycle, followed by the post-combustion capture unit with 113 MW lost work (11.2%). GTW-CCS-EGR achieved a 35.34% thermodynamic efficiency, while GTW-CONV attained a 50.5% thermodynamic efficiency and 56% greater electricity exportation. Although carbon capture and storage imposes a 35.9% energy penalty, GTW-CCS-EGR reached a superior net value of 1816 MMUSD thanks to intensification and carbon dioxide monetization, avoiding 505.8 t/h of carbon emissions (emission factor 0.084 tCO2/MWh), while GTW-CONV entails 0.642 tCO2/MWh.

Solar-Assisted Carbon Capture Process Integrated with a Natural Gas Combined Cycle (NGCC) Power Plant—A Simulation-Based Study

In the realm of Natural Gas Combined Cycle (NGCC) power plants, it is crucial to prioritize the mitigation of CO2 emissions to ensure environmental sustainability. The integration of post-combustion carbon capture technologies plays a pivotal role in mitigating greenhouse gas emissions enhancing the NGCC’s environmental profile by minimizing its carbon footprint. This research paper presents a comprehensive investigation into the integration of solar thermal energy into the Besmaya Natural Gas Combined Cycle (NGCC) power plant, located in Baghdad, Iraq. Leveraging advanced process simulation and modeling techniques employing Aspen Plus software, the study aims to evaluate the performance and feasibility of augmenting the existing NGCC facility with solar assistance for post-carbon capture. The primary objective of this research is to conduct a thorough simulation of the Besmaya NGCC power plant under its current operational conditions, thereby establishing a baseline for subsequent analyses. Subsequently, a solar-assisted post-combustion capture (PCC) plant is simulated and seamlessly integrated into the existing power infrastructure. To accurately estimate solar thermal power potential at the Baghdad coordinates, the System Advisor Model (SAM) is employed. The integration of solar thermal energy into the NGCC power plant is meticulously examined, and the resulting hybrid system’s technical viability and performance metrics are rigorously evaluated. The paper contributes to the field by providing valuable insights into the technical feasibility and potential benefits of incorporating solar thermal energy into conventional natural gas power generation infrastructure, particularly in the context of the Besmaya NGCC plant in Baghdad. The power generation capacity of the plant was set at 750 MW. With this capacity, the annual CO2 generation was estimated at 2,119,318 tonnes/year which was reduced to 18,064 tonnes/year (a 99% reduction). The findings aim to inform future decisions in the pursuit of sustainable and efficient energy solutions, addressing both environmental concerns and energy security in the region.

Study on separation of CO2 condensation from natural gas based on cellular automaton method

ABSTRACT The CO2-containing natural gas is increasing, and there is an urgent need for green treatment of natural gas containing CO2 to realize the utilization of natural gas. Conventional natural gas decarbonization methods have drawbacks such as non-environmental friendliness, and the low-temperature condensation separation of carbon dioxide (snowing-separation) method as a green method of carbon capture is proposed in this paper. Aiming at the characteristics of CO2 condensation in the snowing-separation process, the growth process of CO2 crystals is obtained by simulation using the CA (Cellular Automata) method and finds that the effect of supersaturation on the growth of CO2 crystals is exponential. The snowing-separation process at .5 MPa is analyzed, and it is found that the condensation range is 158.51 K–173.86 K, the upper limit of CO2 mole fraction in natural gas is 10.1%, and the minimum separation time is 8.65 × 10−8s. Analyzing the influencing factors of CO2 separation efficiency, combining the simulation results with the experimental results, the maximum relative error is 13.93%, which can better predict the snowing-separation technology of CO2 in natural gas, and then promote the development of efficient low-temperature carbon capture process.

Prediction of Phase Equilibrium Conditions and Thermodynamic Stability of CO2-CH4 Gas Hydrate

With the large-scale promotion and application of CO2 flooding, more and more engineering problems have emerged. Due to the high CO2 mole fraction, the associated gas of CO2 flooding very easily forms solid hydrates, compared to conventional natural gas. This has resulted in production decline or shutdown. Understanding the phase equilibrium conditions for hydrate formation in production fluids is crucial for hydrate prevention and control. In this study, accurate predictions of CO2-CH4 mixed gas hydrate formation conditions were performed using theoretical models. The temperature and pressure ranges for hydrate formation were calculated for different CO2 mole fraction, ranging from −11.5 °C to 20.85 °C and from 0.81 MPa to −28.1 MPa, respectively. Based on the calculated phase equilibrium data, a multi-parameter empirical model was developed using polynomial fitting. The calculation errors for the multi-parameter empirical model were 3.09%. The multi-parameter empirical model established in this study can avoid complex thermodynamic equilibrium calculations and has the advantages of simplicity, high accuracy, and wide coverage of downhole conditions. Based on the calculated phase equilibrium data, the dissociation enthalpy of CO2-CH4 hydrate below and above the freezing point of water was calculated. The results showed that an increase in CO2 mole fraction led to an increase in hydrate dissociation enthalpy and enhanced thermodynamic stability, making hydrate prevention more challenging. Our work can contribute to the optimization of CO2 production fluid treatment processes and the development of hydrate prevention and control technologies.

Technical, Environmental, and Economic Analysis Comparing Low-Carbon Industrial Process Heat Options in U.S. Poly(vinyl chloride) and Ethylene Manufacturing Facilities.

Electrification and clean hydrogen are promising low-carbon options for decarbonizing industrial process heat, which is an essential target for reducing sector-wide emissions. However, industrial processes with heat demand vary significantly across industries in terms of temperature requirements, capacities, and equipment, making it challenging to determine applications for low-carbon technologies that are technically and economically feasible. In this analysis, we develop a framework for evaluating life cycle emissions, water use, and cost impacts of electric and clean hydrogen process heat technologies and apply it in several case studies for plastics and petrochemical manufacturing industries in the United States. Our results show that industrial heat pumps could reduce emissions by 12-17% in a typical poly(vinyl chloride) (PVC) facility in certain locations currently, compared to conventional natural gas combustion, and that other electric technologies in PVC and ethylene production could reduce emissions by nearly 90% with a sufficiently decarbonized electric grid. Life cycle water use increases significantly in all low-carbon technology cases. The levelized cost of heat of viable low-carbon technologies ranges from 15 to 100% higher than conventional heating systems, primarily due to energy costs. We discuss results in the context of relevant policies that could be useful to manufacturing facilities and policymakers for aiding the transition to low-carbon process heat technologies.