The focus of this study is to investigate the influence of memory effect and the relation of its existence with the dissociation temperature,using gas hydrate formation and dissociation experiments.This is beneficial ...The focus of this study is to investigate the influence of memory effect and the relation of its existence with the dissociation temperature,using gas hydrate formation and dissociation experiments.This is beneficial because memory effect is considered as an effective approach to promote the thermodynamic and dynamic conditions of gas hydrate nucleation.Seven experimental systems (twenty tests in total) were performed in a 1 L pressure cell.Three types of hydrate morphology,namely massive,whiskery and jelly crystals were present in the experiments.The pressures and temperatures at the time when visual hydrate crystals appeared were measured.Furthermore,the influence of memory effect was quantified in terms of pressure-temperature-time (p-T-t) relations.The results revealed that memory effect could promote the thermodynamic conditions and shorten the induction time when the dissociation temperature was not higher than 25℃.In this study,the nucleation superpressure and induction time decrease gradually with time of tests,when the earlier and the later tests are compared.It is assumed that the residual structure of hydrate dissociation,as the source of the memory effect,provides a site for mass transfer between host and guest molecules.Therefore,a driving force is created between the residual structures and its surrounding bulk phase to promote the hydrate nucleation.However,when the dissociation temperature was higher than 25 ℃,the memory effect vanished.These findings provide references for the application of memory effect in hydrate-based technology.展开更多
It is necessary to understand all the prerequisites, which result in gas hydrate formation for safe design and control of a variety of processes in petroleum industry. Thermodynamic hydrate inhibitors (THIs) are norma...It is necessary to understand all the prerequisites, which result in gas hydrate formation for safe design and control of a variety of processes in petroleum industry. Thermodynamic hydrate inhibitors (THIs) are normally used to preclude gas hydrate formation by shifting hydrate stability region to lower temperatures and higher pressures. Sometimes, it is difficult to avoid hydrate formation and hydrates will form anyway. In this situation, kinetic hydrate inhibitors (KHIs) can be used to postpone formation of gas hydrates by retarding hydrate nucleation and growth rate. In this study, two kinetic parameters including natural gas hydrate formation induction time and the rate of gas consumption were experimentally investigated in the presence of monoethylene glycol (MEG), L-tyrosine, and polyvinylpyrrolidone (PVP) at various concentrations in aqueous solutions. Since hydrate formation is a stochastic phenomenon, the repeatability of each kinetic parameter was evaluated several times and the average values for the hydrate formation induction times and the rates of gas consumption are reported. The results indicate that from the view point of hydrate formation induction time, 2 wt% PVP and 20 wt% MEG aqueous solutions have the highest values and are the best choices. It is also interpreted from the results that from the view point of the rate of gas consumption, 20 wt% MEG aqueous solution yields the lowest value and is the best choice. Finally, it is concluded that the combination of PVP and MEG in an aqueous solution has a simultaneous synergistic impact on natural gas hydrate formation induction time and the rate of gas consumption. Furthermore, a semi-empirical model based on chemical kinetic theory is applied to evaluate the hydrate formation induction time data. A good agreement between the experimental and calculated hydrate formation induction time data is observed.展开更多
The effect of diluted solution's magnetization on induction time and growth period of natural gas hydrate (NGH) has been investigated in quiescent reaction system at pressure of 4. 5 MPa and temperature of 274 K w...The effect of diluted solution's magnetization on induction time and growth period of natural gas hydrate (NGH) has been investigated in quiescent reaction system at pressure of 4. 5 MPa and temperature of 274 K with SDS as surfactant, by using volume fixed and pressure falling method. Experimental results show that magnetization will have effect on the induction time of NGH. After magnetization with magnetic field intensity of 0.33 T, the induction time of NGH has been reduced to 47 min (average) from 99 min (average) in which there is no magnetization. On the other hand, the induction time has been prolonged after magnetization of the diluted solution with magnetic field intensity of 0.05 T, 0. 11 T, 0.22 T, 0.44T. Especially with magnetic field intensity of 0.11 T, the induction time had even been prolonged to 431min (average). The effect of magnetization on the growth period of NGH has not been found at the experimental condition.展开更多
The kinetic inhibiting effect of a number of chitosans on hydrate formation was investigated using methane and methane/ethane gas mixtures.The results indicated that chitosan was a good kinetic inhibitor.The induction...The kinetic inhibiting effect of a number of chitosans on hydrate formation was investigated using methane and methane/ethane gas mixtures.The results indicated that chitosan was a good kinetic inhibitor.The induction time of gas hydrate formation evidently increased with the degree of deacetylation (DD),however,when DD was higher than 80%,the effect of DD on the induction time was negligible.Moreover,it was found that the molecular weight (MW) of chitosan and the addition of polyethylene oxide (PEO) had little effect on the induction time.The optimal concentration of chitosan was found to be 0.6 wt%.Finally,the mechanisms of the kinetic inhibitor on the hydrate formation were discussed.展开更多
In the present work we studied the induction periods of hydrate formation of natural gas in pure water, aqueous solutions of surfactants, and in the presence of surfactant together with aluminum oxide nanopowder, the ...In the present work we studied the induction periods of hydrate formation of natural gas in pure water, aqueous solutions of surfactants, and in the presence of surfactant together with aluminum oxide nanopowder, the activity of which as hydrate formation inducer was studied previously. Sodium dodecyl sulfate(SDS) or neonol AF-9-12 were used as the surfactants. It was demonstrated that the addition of either surfactants or aluminum oxide powder under our experimental conditions causes a decrease in the induction period of hydrate formation from;05 min for pure water to 30–35 min for water with additives. In the case of the simultaneous presence of surfactants and aluminum oxide powder in the system, induction period decreased to;0 min. So, the synergistic effect of the combination of surfactant and oxide powder on gas hydrate nucleation was demonstrated. Possible reasons of this effect have been discussed.展开更多
In this paper, the effect of adding different concentrations of kinetic inhibitors on the induction time of hydrogen sulfide hydrate formation in a reactor equipped with automatic adjustable temperature controller is ...In this paper, the effect of adding different concentrations of kinetic inhibitors on the induction time of hydrogen sulfide hydrate formation in a reactor equipped with automatic adjustable temperature controller is studied. A novel method namely "sudden cooling" is used for performing the relevant measurements, in which the induction time of H2S hydrate in the presence/absence of PVP and L-tyrosine with different concentrations (100, 500, and 1000 ppm) is determined. As a result, PVP with the concentration of 1000 ppm in aqueous solution is detected as a more suitable material for increasing the induction time of H2S hydrate formation among the investigated kinetic hydrate inhibitors.展开更多
Gas hydrate reserves are potential source of clean energy having low molecular weight hydrocarbons trapped in water cages.In this work,we report how organic compounds of different chain lengths and hydrophilicities wh...Gas hydrate reserves are potential source of clean energy having low molecular weight hydrocarbons trapped in water cages.In this work,we report how organic compounds of different chain lengths and hydrophilicities when used in small concentration may modify hydrate growth and either act as hydrate inhibitors or promoters.Hydrate promoters foster the hydrate growth kinetics and are used in novel applications such as methane storage as solidified natural gas,desalination of sea water and gas separation.On the other hand,gas hydrate inhibitors are used in oil and gas pipelines to alter the rate at which gas hydrate nucleates and grows.Inhibitors such as methanol and ethanol which form strong hydrogen bond with water have been traditionally used as hydrate inhibitors.However,due to relatively high volatility a significant portion of these inhibitors ends up in gas stream and brings further complexity to the safe transportation of natural gas.In this study,organic additives such as oxalic acid,succinic acid and L-aspartic acid(all three)having––COOH group(s)with aspartic acid having an additional––NH2 group,are investigated for gas hydrate promotion/inhibition behavior.These compounds are polar in nature and thus have significant solubility in liquid water;the presence of weak acidic and water loving(carboxylic/amine groups)moieties makes these organic acids an excellent candidate for further study.This study would pave ways to identify a novel(read better)promoter/inhibitor for gas hydrate formation.Suitable thermodynamic conditions were generated in a stirred tank reactor coupled with cooling system;comparison of gas hydrate formation kinetics with and without additives were carried out to identify the effect of these acids on the formation and growth of hydrates.The possible mechanisms by which these additives inhibit or promote the hydrate growth are also discussed.展开更多
Natural gas hydrates easily form in pipelines,causing potential safety issues during oil and gas production and transportation.Injecting gas hydrate inhibitors is one of the most effective methods for preventing gas h...Natural gas hydrates easily form in pipelines,causing potential safety issues during oil and gas production and transportation.Injecting gas hydrate inhibitors is one of the most effective methods for preventing gas hydrate formation or aggregation.However,some thermodynamic hydrate inhibitors are toxic and harmful to the environment,whereas degradation of kinetic inhibitors is difficult.Therefore,environmentally friendly and easily biodegradable novel green inhibitors have been proposed and investigated.This paper provides a short but systematic review of the inhibitory performance of amino acids,antifreeze proteins,and ionic liquids.For different hydrate formation systems,the influences of the inhibitor type,structure,and concentration on the inhibitory effects are summarized.The mechanism of green inhibitors as kinetic inhibitors is also discussed.The progress described here will facilitate further developments of such green inhibitors for gas hydrate formation.展开更多
In this study, visualizations and experiments are carried out on the influence of static and rotating magnetic fields on the characteristics of HCFC-141b gas hydrate formation, such as crystallization form, formation ...In this study, visualizations and experiments are carried out on the influence of static and rotating magnetic fields on the characteristics of HCFC-141b gas hydrate formation, such as crystallization form, formation temperature and induction time. It has been found that a proper rotating magnetic field can considerably improve the low-pressure gas hydrate formation process, especially in increasing the formation temperature and shortening the induction time. The mor- phology of the gas hydrate formation appears rather complex and compact. However, a proper static magnetic field can make the gas hydrate crystal more organized, which will be benefit to heat transfer.展开更多
Low-pressure refrigerant gas hydrates have brilliant prospects as a cool storage me-dium for air-conditioning systems. Intensive effects of some specific magnetic fields on the forma-tion process of HCFC-141b refriger...Low-pressure refrigerant gas hydrates have brilliant prospects as a cool storage me-dium for air-conditioning systems. Intensive effects of some specific magnetic fields on the forma-tion process of HCFC-141b refrigerant gas hydrate are depicted experimentally. Under influence of these specific magnetic fields, the orientation and growth region of gas hydrate are altered; induc-tion time of hydrate crystallization can be shortened extremely, and it can be shortened to 40 min from 9 h; hydrate formation mass can be enhanced considerably, and hydration rate can arrive at 100% in some instances. Meanwhile, the relations of induction time and hydration rate changed with magnetic field intensity are depicted, and some elementary regulations are found.展开更多
As the oil and gas industries continue to increase their activity in deep water, gas hydrate hazards will become more serious and challenging, both at present and in the future. Accurate predictions of the hydrate-fre...As the oil and gas industries continue to increase their activity in deep water, gas hydrate hazards will become more serious and challenging, both at present and in the future. Accurate predictions of the hydrate-free zone and the suitable addition of salts and/or alcohols in preparing drilling fluids are particularly important both in preventing hydrate problems and decreasing the cost of drilling operations. In this paper, we compared several empirical correlations commonly used to estimate the hydrate inhibition effect of aqueous organic and electrolyte solutions using experiments with ethylene glycol (EG) as a hydrate inhibitor. The results show that the Najibi et al. correlation (for single and mixed thermodynamic inhibitors) and the Ostergaard et al. empirical correlation (for single thermodynamic inhibitors) are suitable for estimating the hydrate safety margin of oil-based drilling fluids (OBDFs) in the presence of thermodynamic hydrate inhibitors. According to the two correlations, the OBDF, composed of 1.6 L vaporizing oil, 2% emulsifying agent, 1% organobentonite, 0.5% SP-1, 1% LP-1, 10% water and 40% EG, can be safely used at a water depth of up to 1900 m. However, for more accurate predictions for drilling fluids, the effects of the solid phase, especially bentonite, on hydrate inhibition need to be considered and included in the application of these two empirical correlations.展开更多
Natural gas hydrate(NGH) is considered as an alternative energy resource in the future as it is proven to contain about 2 times carbon resources of those contained in the fossil energy on Earth. Gas hydrate technology...Natural gas hydrate(NGH) is considered as an alternative energy resource in the future as it is proven to contain about 2 times carbon resources of those contained in the fossil energy on Earth. Gas hydrate technology is a new technology which can be extensively used in methane production from NGH, gas separation and purification, gas transportation, sea–water desalination, pipeline safety and phase change energy storage, etc. Since the 1980s, the gas hydrate technology has become a research hotspot worldwide because of its relatively economic and environmental friendly characteristics. China is a big energy consuming country with coal as a dominant energy.With the development of the society, energy shortage and environmental pollution are becoming great obstacles to the progress of the country. Therefore, in order to ensure the sustainable development of the society, it is of great significance to develop and utilize NGH and vigorously develop the gas hydrate technology. In this paper,the research advances in hydrate-based processes in China are comprehensively reviewed from different aspects,mainly including gas separation and purification, hydrate formation inhibition, sea–water desalination and methane exploitation from NGH by CH4–CO2 replacement. We are trying to show the relevant research in China, and at the same time, summarize the characteristics of the research and put forward the corresponding problems in a technical way.展开更多
Gas hydrates have drawn global attentions in the past decades as potential energy resources.It should be noted that there are a variety of possible applications of hydrate-based technologies,including natural gas stor...Gas hydrates have drawn global attentions in the past decades as potential energy resources.It should be noted that there are a variety of possible applications of hydrate-based technologies,including natural gas storage,gas transportation,separation of gas mixture,and seawater desalination.These applications have been critically challenged by insufficient understanding of hydrate formation kinetics.In this work,the literatures on growth kinetic behaviors of hydrate formation from water-hydrocarbon were systematically reviewed.The hydrate crystal growth,hydrate film growth and macroscopic hydrate formation in water system were reviewed,respectively.Firstly,the hydrate crystal growth was analyzed with respect to different positions,such as gas/liquid interface,liquid–liquid interface and gas–liquid–liquid system.Secondly,experimental and modeling studies on the growth of hydrate film at the interfaces between guest phase and water phase were categorized into two groups of lateral growth and thickening growth considering the differences in growth rates.Thirdly,we summarized the promoters and inhibitors reported(biological or chemical,liquid or solid and hydrophobic or hydrophilic)and analyzed the mechanisms affecting hydrate formation in bulk water system.Knowledge gaps and suggestions for further studies on hydrate formation kinetic behaviors are presented.展开更多
Four types of nanoparticles,amorphous carbon,ironⅢoxide,SiO2,and amino-coated SiO2,were tested to determine changes in tetrahydrofuran-water(THF-water)clathrate hydrate nucleation and agglomeration.Rates were experim...Four types of nanoparticles,amorphous carbon,ironⅢoxide,SiO2,and amino-coated SiO2,were tested to determine changes in tetrahydrofuran-water(THF-water)clathrate hydrate nucleation and agglomeration.Rates were experimentally found to determine their viability for preventing natural gas hydrates from developing during offshore drilling operations.THF-water clathrates were chosen as a model to represent gas hydrate growth at atmospheric pressure.Concentrations of each nanoparticle between 0.15%and 1.0%by weight were tested as a kinetic inhibitor to hydrate formation.Tests were repeated at various temperatures below the formation temperature of 4.4℃for THF-water clathrate hydrates.Measurements were made to identify how the concentration of THF affects the clathrate hydrates forming under static conditions between20%and 30%by mole of THF.The primary tests in this study were performed using a 20:80 THF/water ratio.Temperature increases during hydrate nucleation for THF-water were measured between-5 and 3℃.The range of ideal nanoparticle concentrations was found to be between 0.15%and 0.45%by weight for optimal static,kinetic inhibition of hydrate nucleation.At approximately 0.3%by weight,the most significant inhibition was observed under static conditions for all four types of nanoparticles tested.We found that functionalized amino-coated SiO2 nanoparticles,across all tests,significantly increased the time required for the formation of THF-water clathrate hydrates compared to the other three non-functionalized nanoparticles.The amorphous carbon and ironⅢoxide nanoparticles performed similarly across each test and were both the least effective in their inhibition of the clathrate hydrates of the four nanoparticles studied compared to a control.展开更多
In order to ensure safe drilling in deep water and marine gas hydrate bearing sediments, the needed characteristics of drilling fluid system were analyzed. Moreover, the effect of different agents on hydrate formation...In order to ensure safe drilling in deep water and marine gas hydrate bearing sediments, the needed characteristics of drilling fluid system were analyzed. Moreover, the effect of different agents on hydrate formation and the low-temperature rheology of designed polyalcohol drilling fluid were tested, respectively. The results show that clay can promote gas hydrate growth, while modified starch and polyalcohol can inhibit hydrate formation to some extent, and PVP K90 has a good performance on hydrate inhibition. The influence of clay on low-temperature rheology of polyglycols drilling fluid is notable. Therefore, the clay-free polyalcohol drilling fluid is suitable for deep water and marine gas hydrate drilling under optimal conditions.展开更多
基金supported by the National Natural Science Foundation(No.50874040,No.50904026)Heilongjiang Provincial Natural Science Foundation(No.B2007-10)Harbin Innovation Talent of Science and Technology Foundation(No.2007RFXXS050,No.2008RFQXG111)
文摘The focus of this study is to investigate the influence of memory effect and the relation of its existence with the dissociation temperature,using gas hydrate formation and dissociation experiments.This is beneficial because memory effect is considered as an effective approach to promote the thermodynamic and dynamic conditions of gas hydrate nucleation.Seven experimental systems (twenty tests in total) were performed in a 1 L pressure cell.Three types of hydrate morphology,namely massive,whiskery and jelly crystals were present in the experiments.The pressures and temperatures at the time when visual hydrate crystals appeared were measured.Furthermore,the influence of memory effect was quantified in terms of pressure-temperature-time (p-T-t) relations.The results revealed that memory effect could promote the thermodynamic conditions and shorten the induction time when the dissociation temperature was not higher than 25℃.In this study,the nucleation superpressure and induction time decrease gradually with time of tests,when the earlier and the later tests are compared.It is assumed that the residual structure of hydrate dissociation,as the source of the memory effect,provides a site for mass transfer between host and guest molecules.Therefore,a driving force is created between the residual structures and its surrounding bulk phase to promote the hydrate nucleation.However,when the dissociation temperature was higher than 25 ℃,the memory effect vanished.These findings provide references for the application of memory effect in hydrate-based technology.
文摘It is necessary to understand all the prerequisites, which result in gas hydrate formation for safe design and control of a variety of processes in petroleum industry. Thermodynamic hydrate inhibitors (THIs) are normally used to preclude gas hydrate formation by shifting hydrate stability region to lower temperatures and higher pressures. Sometimes, it is difficult to avoid hydrate formation and hydrates will form anyway. In this situation, kinetic hydrate inhibitors (KHIs) can be used to postpone formation of gas hydrates by retarding hydrate nucleation and growth rate. In this study, two kinetic parameters including natural gas hydrate formation induction time and the rate of gas consumption were experimentally investigated in the presence of monoethylene glycol (MEG), L-tyrosine, and polyvinylpyrrolidone (PVP) at various concentrations in aqueous solutions. Since hydrate formation is a stochastic phenomenon, the repeatability of each kinetic parameter was evaluated several times and the average values for the hydrate formation induction times and the rates of gas consumption are reported. The results indicate that from the view point of hydrate formation induction time, 2 wt% PVP and 20 wt% MEG aqueous solutions have the highest values and are the best choices. It is also interpreted from the results that from the view point of the rate of gas consumption, 20 wt% MEG aqueous solution yields the lowest value and is the best choice. Finally, it is concluded that the combination of PVP and MEG in an aqueous solution has a simultaneous synergistic impact on natural gas hydrate formation induction time and the rate of gas consumption. Furthermore, a semi-empirical model based on chemical kinetic theory is applied to evaluate the hydrate formation induction time data. A good agreement between the experimental and calculated hydrate formation induction time data is observed.
基金supported by the National Natural Science Foundation of China (No. 50176051)the State Key Development Program for Basic Research of China (No. 2000026306).
文摘The effect of diluted solution's magnetization on induction time and growth period of natural gas hydrate (NGH) has been investigated in quiescent reaction system at pressure of 4. 5 MPa and temperature of 274 K with SDS as surfactant, by using volume fixed and pressure falling method. Experimental results show that magnetization will have effect on the induction time of NGH. After magnetization with magnetic field intensity of 0.33 T, the induction time of NGH has been reduced to 47 min (average) from 99 min (average) in which there is no magnetization. On the other hand, the induction time has been prolonged after magnetization of the diluted solution with magnetic field intensity of 0.05 T, 0. 11 T, 0.22 T, 0.44T. Especially with magnetic field intensity of 0.11 T, the induction time had even been prolonged to 431min (average). The effect of magnetization on the growth period of NGH has not been found at the experimental condition.
基金supported by the National Nature Science Foundation of China (No.50776020 and No. 50836005)
文摘The kinetic inhibiting effect of a number of chitosans on hydrate formation was investigated using methane and methane/ethane gas mixtures.The results indicated that chitosan was a good kinetic inhibitor.The induction time of gas hydrate formation evidently increased with the degree of deacetylation (DD),however,when DD was higher than 80%,the effect of DD on the induction time was negligible.Moreover,it was found that the molecular weight (MW) of chitosan and the addition of polyethylene oxide (PEO) had little effect on the induction time.The optimal concentration of chitosan was found to be 0.6 wt%.Finally,the mechanisms of the kinetic inhibitor on the hydrate formation were discussed.
文摘In the present work we studied the induction periods of hydrate formation of natural gas in pure water, aqueous solutions of surfactants, and in the presence of surfactant together with aluminum oxide nanopowder, the activity of which as hydrate formation inducer was studied previously. Sodium dodecyl sulfate(SDS) or neonol AF-9-12 were used as the surfactants. It was demonstrated that the addition of either surfactants or aluminum oxide powder under our experimental conditions causes a decrease in the induction period of hydrate formation from;05 min for pure water to 30–35 min for water with additives. In the case of the simultaneous presence of surfactants and aluminum oxide powder in the system, induction period decreased to;0 min. So, the synergistic effect of the combination of surfactant and oxide powder on gas hydrate nucleation was demonstrated. Possible reasons of this effect have been discussed.
文摘In this paper, the effect of adding different concentrations of kinetic inhibitors on the induction time of hydrogen sulfide hydrate formation in a reactor equipped with automatic adjustable temperature controller is studied. A novel method namely "sudden cooling" is used for performing the relevant measurements, in which the induction time of H2S hydrate in the presence/absence of PVP and L-tyrosine with different concentrations (100, 500, and 1000 ppm) is determined. As a result, PVP with the concentration of 1000 ppm in aqueous solution is detected as a more suitable material for increasing the induction time of H2S hydrate formation among the investigated kinetic hydrate inhibitors.
基金the Department of Science and Technology, Science and Engineering Research Board, India for the project grant EMR/2017/000810the Department of Science and Technology-Science and Engineering Research Board, India for the award of National Postdoctoral Fellowship (Principal Investigator) and project grant DST-SERB-PDF-2017/003075
文摘Gas hydrate reserves are potential source of clean energy having low molecular weight hydrocarbons trapped in water cages.In this work,we report how organic compounds of different chain lengths and hydrophilicities when used in small concentration may modify hydrate growth and either act as hydrate inhibitors or promoters.Hydrate promoters foster the hydrate growth kinetics and are used in novel applications such as methane storage as solidified natural gas,desalination of sea water and gas separation.On the other hand,gas hydrate inhibitors are used in oil and gas pipelines to alter the rate at which gas hydrate nucleates and grows.Inhibitors such as methanol and ethanol which form strong hydrogen bond with water have been traditionally used as hydrate inhibitors.However,due to relatively high volatility a significant portion of these inhibitors ends up in gas stream and brings further complexity to the safe transportation of natural gas.In this study,organic additives such as oxalic acid,succinic acid and L-aspartic acid(all three)having––COOH group(s)with aspartic acid having an additional––NH2 group,are investigated for gas hydrate promotion/inhibition behavior.These compounds are polar in nature and thus have significant solubility in liquid water;the presence of weak acidic and water loving(carboxylic/amine groups)moieties makes these organic acids an excellent candidate for further study.This study would pave ways to identify a novel(read better)promoter/inhibitor for gas hydrate formation.Suitable thermodynamic conditions were generated in a stirred tank reactor coupled with cooling system;comparison of gas hydrate formation kinetics with and without additives were carried out to identify the effect of these acids on the formation and growth of hydrates.The possible mechanisms by which these additives inhibit or promote the hydrate growth are also discussed.
基金Supported by National Key Research and Development Plan of China(2017YFC0307306)the National Natural Science Foundation of China(51876211)
文摘Natural gas hydrates easily form in pipelines,causing potential safety issues during oil and gas production and transportation.Injecting gas hydrate inhibitors is one of the most effective methods for preventing gas hydrate formation or aggregation.However,some thermodynamic hydrate inhibitors are toxic and harmful to the environment,whereas degradation of kinetic inhibitors is difficult.Therefore,environmentally friendly and easily biodegradable novel green inhibitors have been proposed and investigated.This paper provides a short but systematic review of the inhibitory performance of amino acids,antifreeze proteins,and ionic liquids.For different hydrate formation systems,the influences of the inhibitor type,structure,and concentration on the inhibitory effects are summarized.The mechanism of green inhibitors as kinetic inhibitors is also discussed.The progress described here will facilitate further developments of such green inhibitors for gas hydrate formation.
基金This work was supported by the National Natural Science Foundation of China(Grant Nos.20076046 and 59836230).
文摘In this study, visualizations and experiments are carried out on the influence of static and rotating magnetic fields on the characteristics of HCFC-141b gas hydrate formation, such as crystallization form, formation temperature and induction time. It has been found that a proper rotating magnetic field can considerably improve the low-pressure gas hydrate formation process, especially in increasing the formation temperature and shortening the induction time. The mor- phology of the gas hydrate formation appears rather complex and compact. However, a proper static magnetic field can make the gas hydrate crystal more organized, which will be benefit to heat transfer.
基金This work was supported by the National Natural Science Foundation of China(Grant No.59836230)the Major State Basic Research Program(Grant No.G2000026306)+1 种基金Superintendent Fund of Guangzhou Institute of Energy Conversionthe Chinese Academy of Sciences(Grant No.07-20406).
文摘Low-pressure refrigerant gas hydrates have brilliant prospects as a cool storage me-dium for air-conditioning systems. Intensive effects of some specific magnetic fields on the forma-tion process of HCFC-141b refrigerant gas hydrate are depicted experimentally. Under influence of these specific magnetic fields, the orientation and growth region of gas hydrate are altered; induc-tion time of hydrate crystallization can be shortened extremely, and it can be shortened to 40 min from 9 h; hydrate formation mass can be enhanced considerably, and hydration rate can arrive at 100% in some instances. Meanwhile, the relations of induction time and hydration rate changed with magnetic field intensity are depicted, and some elementary regulations are found.
基金supported by the National Natural Science Foundation (No. 50704028, 50904053)the Project 863 (No.2006AA09Z316)+1 种基金the Fundamental Research Funds for the Central Universities (No. CUGL100410)supported by the Opening Project of National Laboratory on Scientific Drilling, China University of Geosciences at Beijing (No. NLSD200901)
文摘As the oil and gas industries continue to increase their activity in deep water, gas hydrate hazards will become more serious and challenging, both at present and in the future. Accurate predictions of the hydrate-free zone and the suitable addition of salts and/or alcohols in preparing drilling fluids are particularly important both in preventing hydrate problems and decreasing the cost of drilling operations. In this paper, we compared several empirical correlations commonly used to estimate the hydrate inhibition effect of aqueous organic and electrolyte solutions using experiments with ethylene glycol (EG) as a hydrate inhibitor. The results show that the Najibi et al. correlation (for single and mixed thermodynamic inhibitors) and the Ostergaard et al. empirical correlation (for single thermodynamic inhibitors) are suitable for estimating the hydrate safety margin of oil-based drilling fluids (OBDFs) in the presence of thermodynamic hydrate inhibitors. According to the two correlations, the OBDF, composed of 1.6 L vaporizing oil, 2% emulsifying agent, 1% organobentonite, 0.5% SP-1, 1% LP-1, 10% water and 40% EG, can be safely used at a water depth of up to 1900 m. However, for more accurate predictions for drilling fluids, the effects of the solid phase, especially bentonite, on hydrate inhibition need to be considered and included in the application of these two empirical correlations.
基金Supported by the Key Program of National Natural Science Foundation of China(51736009)the National Natural Science Foundation of China(51476174)+4 种基金National Key R&D Program of China(2016YFC0304002,2017YFC0307306)the CAS Science and Technology Apparatus Development Program(YZ201619)Frontier Sciences Key Research Program of the Chinese Academy of Sciences(QYZDJ-SSW-JSC033)Special project for Marine Economy Development of Guangdong Province(GDME-2018D002)the National Natural Science Fund of Guangdong Province,China(2017A030313301)
文摘Natural gas hydrate(NGH) is considered as an alternative energy resource in the future as it is proven to contain about 2 times carbon resources of those contained in the fossil energy on Earth. Gas hydrate technology is a new technology which can be extensively used in methane production from NGH, gas separation and purification, gas transportation, sea–water desalination, pipeline safety and phase change energy storage, etc. Since the 1980s, the gas hydrate technology has become a research hotspot worldwide because of its relatively economic and environmental friendly characteristics. China is a big energy consuming country with coal as a dominant energy.With the development of the society, energy shortage and environmental pollution are becoming great obstacles to the progress of the country. Therefore, in order to ensure the sustainable development of the society, it is of great significance to develop and utilize NGH and vigorously develop the gas hydrate technology. In this paper,the research advances in hydrate-based processes in China are comprehensively reviewed from different aspects,mainly including gas separation and purification, hydrate formation inhibition, sea–water desalination and methane exploitation from NGH by CH4–CO2 replacement. We are trying to show the relevant research in China, and at the same time, summarize the characteristics of the research and put forward the corresponding problems in a technical way.
基金Supported by the National Natural Science Foundation of China(41872182)China Postdoctoral Science Foundation(2018T110248,2015M580248)
文摘Gas hydrates have drawn global attentions in the past decades as potential energy resources.It should be noted that there are a variety of possible applications of hydrate-based technologies,including natural gas storage,gas transportation,separation of gas mixture,and seawater desalination.These applications have been critically challenged by insufficient understanding of hydrate formation kinetics.In this work,the literatures on growth kinetic behaviors of hydrate formation from water-hydrocarbon were systematically reviewed.The hydrate crystal growth,hydrate film growth and macroscopic hydrate formation in water system were reviewed,respectively.Firstly,the hydrate crystal growth was analyzed with respect to different positions,such as gas/liquid interface,liquid–liquid interface and gas–liquid–liquid system.Secondly,experimental and modeling studies on the growth of hydrate film at the interfaces between guest phase and water phase were categorized into two groups of lateral growth and thickening growth considering the differences in growth rates.Thirdly,we summarized the promoters and inhibitors reported(biological or chemical,liquid or solid and hydrophobic or hydrophilic)and analyzed the mechanisms affecting hydrate formation in bulk water system.Knowledge gaps and suggestions for further studies on hydrate formation kinetic behaviors are presented.
文摘Four types of nanoparticles,amorphous carbon,ironⅢoxide,SiO2,and amino-coated SiO2,were tested to determine changes in tetrahydrofuran-water(THF-water)clathrate hydrate nucleation and agglomeration.Rates were experimentally found to determine their viability for preventing natural gas hydrates from developing during offshore drilling operations.THF-water clathrates were chosen as a model to represent gas hydrate growth at atmospheric pressure.Concentrations of each nanoparticle between 0.15%and 1.0%by weight were tested as a kinetic inhibitor to hydrate formation.Tests were repeated at various temperatures below the formation temperature of 4.4℃for THF-water clathrate hydrates.Measurements were made to identify how the concentration of THF affects the clathrate hydrates forming under static conditions between20%and 30%by mole of THF.The primary tests in this study were performed using a 20:80 THF/water ratio.Temperature increases during hydrate nucleation for THF-water were measured between-5 and 3℃.The range of ideal nanoparticle concentrations was found to be between 0.15%and 0.45%by weight for optimal static,kinetic inhibition of hydrate nucleation.At approximately 0.3%by weight,the most significant inhibition was observed under static conditions for all four types of nanoparticles tested.We found that functionalized amino-coated SiO2 nanoparticles,across all tests,significantly increased the time required for the formation of THF-water clathrate hydrates compared to the other three non-functionalized nanoparticles.The amorphous carbon and ironⅢoxide nanoparticles performed similarly across each test and were both the least effective in their inhibition of the clathrate hydrates of the four nanoparticles studied compared to a control.
基金supported by "863" Program (No. 2006AA09Z316)the National Natural Science Foundation of China (Nos. 40974071, 50904053)the Natural Science Foundation of Hubei Province (No. 2010CDA056)
文摘In order to ensure safe drilling in deep water and marine gas hydrate bearing sediments, the needed characteristics of drilling fluid system were analyzed. Moreover, the effect of different agents on hydrate formation and the low-temperature rheology of designed polyalcohol drilling fluid were tested, respectively. The results show that clay can promote gas hydrate growth, while modified starch and polyalcohol can inhibit hydrate formation to some extent, and PVP K90 has a good performance on hydrate inhibition. The influence of clay on low-temperature rheology of polyglycols drilling fluid is notable. Therefore, the clay-free polyalcohol drilling fluid is suitable for deep water and marine gas hydrate drilling under optimal conditions.