Article
Energy & Fuels
Qi-Rong Zuo, Ming Gao, Peng Kong, Li-Xin Zhang
Summary: The microscopic characteristics and agglomerating morphologies of hydrate crystals are crucial for flow assurance and heat transfer in hydrate reaction equipment. In this study, experimental quartz tubes with small diameters were used to investigate the effects of supercooling, solution concentration, tube diameter, and flow rate on hydrate blockage time and agglomeration morphology. The research findings suggest that the density of single crystal hydrate formed in 10 wt%-20 wt% TBAB hydrate solution is low, with a needle-like or sword-like crystal front, promoting mass and heat transfer. High concentration TBAB solution (30 wt%-40 wt%) results in dense hydrate crystals with weakened tip effect. Increasing flow rate inhibits the growth of large crystals and promotes the formation of new nuclei in low concentration TBAB solution. Adjustable flow rates can produce grout solutions with different particle sizes. The initial morphology of TBAB hydrate crystals includes spherical and cylindrical shapes, and their morphological evolution process is similar. A microscopic physical model of TBAB hydrate growth and agglomeration process was established.
Article
Energy & Fuels
Vafa Feyzi, Vahid Mohebbi
Summary: The multifaceted benefits of natural gas, as the cleanest fossil fuel, have led to a significant shift towards natural gas in various sectors in recent years. Gas hydrate has gained attention as a solution for purification and storage of natural gas, while naturally occurring methane hydrate deposits can secure global energy demand for decades. Further studies on mixed CO2+CH4 hydrate formation kinetics are necessary for commercializing SNG technology and exploiting methane hydrate reservoirs.
Article
Thermodynamics
Xiaoya Zang, Jing Wang, Yong He, Xuebing Zhou, Deqing Liang
Summary: In this study, TBAB hydrates were synthesized and their carbon capture capacity from a ternary gas mixture of CH4/CO2/N-2 was investigated. The addition of TBAB increased the specific surface area of the hydrate crystals and transformed the hydrate structure. These findings are important for the development of hydrate gas separation technology.
Article
Energy & Fuels
Yue Ma, Qiang Gao, Jian Guan, Chi Zhang, Jianzhong Zhao
Summary: In this study, experiments were conducted to dissociate mixed CO2 + CH4 hydrates by depressurization and thermal stimulation. The kinetics, fluid production behavior, heat transfer characteristics, and separation factors were examined during the hydrate formation and dissociation processes. The results showed consistent gas consumption and phase saturation, with a stochastic induction time ranging from 38 to 58 minutes. The hydrate exhibited a strong selectivity to CH4 during the gas mixture hydrate formation process, and the gas production increased with decreasing depressurization pressure.
Article
Thermodynamics
Xinlu Han, Marco Lubrano Lavadera, Christian Brackmann, Zhihua Wang, Yong He, Alexander A. Konnov
Summary: The formation of nitric oxide (NO) in methane (CH4) flames has been extensively studied, but discrepancies between simulations using different kinetic mechanisms and experimental results persist. Experimental data was collected for NO formation in post-flame zones of CH4+O2+N2 flames with varying oxygen ratios. Analysis showed that thermal-NO production plays a key role in the increase of NO mole fraction in stoichiometric and fuel-lean flames as oxygen ratio increases.
COMBUSTION AND FLAME
(2021)
Article
Energy & Fuels
Yingmei Wang, Aili Niu, Wenze Jiao, Ji Chen, Peng Zhang, Jinping Li
Summary: Carbon dioxide hydrate formation rate is improved by using different accelerator systems. The combination of nanographite-TBAB and SDS-TBAB shows better performance in reducing the nucleation time. TBAB shows the best nucleation amount, formation rate, and conversion rate among the single acceleration systems.
Article
Polymer Science
Angel de J. Montes Luna, Nidia C. Fuentes Lopez, Griselda Castruita de Leon, Odilia Perez Camacho, Claudia Y. Yeverino Miranda, Yibran A. Perera Mercado
Summary: In this study, polybenzimidazole (PBI) and natural zeolite-based mixed matrix membranes (MMMs) were prepared and their transport properties for binary and ternary mixed-gas separation were investigated. The MMMs showed improved perm-selectivity properties compared to the PBI polymeric membranes, favoring the permeation of CO2 and N-2. Through thermal properties analysis and X-Ray Diffraction, it was found that the MMMs membranes have higher thermal stability and the zeolite signals combine with the amorphous dome from the polymeric matrix.
JOURNAL OF APPLIED POLYMER SCIENCE
(2021)
Article
Engineering, Environmental
Yu-Hsuan Ho, Yau Zu Khoo, Yan-Ping Chen, Ryo Ohmura, Li-Jen Chen
Summary: This study investigates the thermodynamic and kinetic influence of polyethylenimine (PEI) on the formation of methane and carbon dioxide hydrates. It is found that PEI acts as a thermodynamic inhibitor, inhibiting the formation of hydrates. However, it has different effects on methane and carbon dioxide hydrates kinetically, inhibiting methane hydrate formation and promoting carbon dioxide hydrate formation.
CHEMICAL ENGINEERING JOURNAL
(2023)
Article
Energy & Fuels
Hanmei Zhang, Chang Li, Jun Chen, Jianjian Wu, Xiaobing Lan, Zhikai Liang, Bin Deng
Summary: Heavy metal is a potential threat to human, and hydrate-based method was one possible approach for its removal. Molecular simulation using Gromacs-2020.3 software was conducted to investigate the mechanism of heavy metal removal by hydrate-based method. The simulation results showed that CH4 hydrate formed in NiCl2 solution, and the main solid structure was hydrate or interfacial hydrate. All nickel chloride was repelled out of CH4 hydrate during the simulation, indicating the salt-removing effect. Furthermore, the simulation results revealed that chloride ion promoted the nucleation of CH4 hydrate regardless of the cation being Na+ or Ni2+. In addition, both Structure I (sI) and Structure II (sII) CH4 hydrates were formed in NiCl2 solution, with sI type hydrate being the predominant structure.
Article
Thermodynamics
Xiaoya Zang, Jing Wang, Yong He, Xuebing Zhou, Deqing Liang
Summary: This study examined the formation kinetics of ternary gas mixture hydrates using synthesized cyclopentane and sodium dodecyl sulfate as additives. The results showed that the use of mixed additives can promote hydrate formation and enhance gas separation under specific conditions. Increasing the concentration of sodium dodecyl sulfate can smoothen the hydrate crystal surface, resulting in more complete crystallization.
Article
Energy & Fuels
Lanyun Wang, Yuan Yang, Yan Wang, Yongliang Xu, Yao Li, Jianping Wei, Xiaodong Feng, Kun Zhang
Summary: The slow formation rate and low storage capacity of gas hydrates, as well as the harsh conditions and contaminating promoters, pose major challenges to the application of carbon capture and storage (CCS) technology based on hydrate formation. In this study, three types of graphene nanoparticles (nonfunctionalized graphene, graphene oxide, and amino graphene) were tested as additives to accelerate CO2 and CH4 hydrate formation. The results showed that nonfunctionalized graphene promoted the thermodynamics of CO2 hydrate formation, while graphene oxide and amino graphene had no effect or even inhibited the formation. However, graphene oxide and amino graphene effectively enhanced gas consumption. Overall, nonfunctionalized graphene shortened the induction time, while graphene oxide and amino graphene showed potential as additives to improve gas consumption. The presence of oxidized and amine groups was found to inhibit gas hydrate nucleation.
Article
Engineering, Chemical
Zucheng Cheng, Weiguo Liu, Shaohua Li, Sijia Wang, Yingying Liu, Xiang Sun, Cong Chen, Lanlan Jiang, Yongchen Song
Summary: This study evaluated the performance of SDS in the separation efficiency of simulated biogas. The experimental results showed that higher driving forces led to a significant increase in gas capture, dominated by the CH4 component. Hydrate growth mainly occurred in the liquid phase, and the separation factor was positively correlated with the induction time. Gas capture per unit volume of solution could be improved at higher gas-liquid ratios, while high-pressure failure behavior was observed. The defoamer had no significant effect on hydrate generation kinetics and separation efficiency.
SEPARATION AND PURIFICATION TECHNOLOGY
(2022)
Article
Energy & Fuels
Meng-yang Li, Ming Gao, Qi-rong Zuo, Yu-gang Zhao, Li-xin Zhang
Summary: This study investigated the nucleation process of TBAB hydrate using high-speed photography and proposed a model for calculating the Gibbs free energy required for hydrate nucleation. The maximum critical nucleation size of A-type TBAB hydrate was calculated to be about 29 Å, and that of B-type TBAB hydrate was approximately 15.6 Å, providing insights for further research on hydrate formation kinetics.
Article
Energy & Fuels
Jia Liu, Jing Wang, Ti Dong, Deqing Liang
Summary: The formation of wax crystals and hydrates in deep-sea crude oil can affect the nucleation, growth, aggregation, and crystal structure of hydrates. Specifically, wax crystals inhibit hydrate formation, while hydrate formation reduces wax crystal aggregation, improving the flow characteristics of the hydrate slurry. Wax has no effect on the crystal structure of CH4 hydrate but impacts the distribution of the gas in cavities.
Article
Engineering, Chemical
Ting Wu, Ying Tu, Wen Liu, Zhen Sun, Meihua Zhu, Xuezhong He, Tian Gui, Xiangshu Chen, Hidetoshi Kita
Summary: In this study, a co-solvent strategy using isopropanol as the organic co-solvent was employed to synthesize AlPO-18 membrane. The addition of isopropanol not only accelerated the crystallization of AlPO-18 membrane, but also increased the size of crystals on the membrane, leading to a reduced synthesis time.
SEPARATION AND PURIFICATION TECHNOLOGY
(2023)