Query: propane hydrate reaction rate

title: Methane propane hydrate formation and memory effect study with a reaction kinetics model
abstract: Although natural gas hydrates and hydrate exploration have been extensively studied for decades, the reaction kinetics and nucleation mechanism of hydrate formation is not fully understood. In its early stage, gas hydrate formation can be assumed to be an autocatalytic kinetic reaction with nucleation and initial growth. In this work, a reaction kinetics model has been established to form structure II methane propane hydrate in an isochoric reactor. The computational model consists of six pseudo elementary reactions for three dynamic processes: (1) gas dissolution into the bulk liquid, (2) a slow buildup of hydrate precursors for nucleation onset, and (3) rapid and autocatalytic hydrate growth after onset. The model was programmed using FORTRAN, with initiating parameters and rate constants that were derived or obtained from data fitted using experimental results. The simulations indicate that the length of nucleation induction is determined largely by an accumulation of oligomeric hydrate precursors up to a threshold value. The slow accumulation of precursors is the rate limiting step for the overall hydrate formation, and its conversion into hydrate particles is critical for the rapid, autocatalytic reaction. By applying this model, the memory effect for hydrate nucleation was studied by assigning varied initial amounts of precursor or hydrate species in the simulations. The presence of pre existing precursors or hydrate particles could facilitate the nucleation stage with a reduced induction time, and without affecting hydrate growth. The computational model with the performed simulations provides insight into the reaction kinetics and nucleation mechanism of hydrate formation.

title: Reaction rate constant of propane hydrate formation
abstract: Experimental data on the rate of formation of propane hydrates were obtained using a particle size analyzer capable of detecting particles with diameters as small as 0.6 nm, while operating in a closed loop system. Experiments were carried out at temperatures around 274 K and pressures between 315 and 340 kPa in a semi batch stirred tank crystallizer. The experimental data were analyzed using a newly developed kinetic model based on crystallization theory and as a result, the actual reaction rate constant for propane hydrate formation was successfully determined. A value of 2.15 x 10 7 m/s is reported at 274.2 K, while it was found that the dissolution rate of propane at the vapor liquid water interface was enhanced by a factor of five during the growth stage, compared to the value obtained during typical solubility experiments.

title: Kinetic study of the effect of amino acids on methane (95% propane (5% hydrate formation
abstract: The motivation for this study is the potential of environmental friendly amino acids such as alanine, histidine, phenylalanine and valine to be examined as inhibitors on methane (95% propane (5% hydrate formation together with the hydrodynamic examination of three different flows in hydrate formation process. The outcomes indicated that valine and alanine behave as promoters while histidine and phenylalanine behave as inhibitors. From hydrodynamic perception radial flow shows less induction time values and better rate of hydrate formation due to better gas liquid contact compared to mixed flow experiments.

title: Comparison of emission concentrations during the combustion of a double hydrate propane methane at different temperatures in a muffle furnace
abstract: In recent years, more and more attention in the world has been paid to the development of environmentally friendly technology for combustion gas hydrates. In this work, experimental studies of the combustion of a propane methane double gas hydrate at different temperatures in a muffle furnace of 650 degC and 950 degC were performed. The increase in temperature in the muffle furnace allowed to reduce harmful emissions and reduce fuel loss. With increasing temperature, the CO concentration decreases by 2.2 2.5 times, CO2 from 7 8% to 3 4% and NOX changes by 1.2 1.5 times, which is associated with an increase in the reaction rate. Emissions of NOX gases during combustion of coal water suspensions are many times higher than the obtained values of NOX concentrations of methane propane gas hydrates.

title: Study on Pressure Turbulence for Growth Process Promotion of Propane Hydrate
abstract: In order to acquire fast formation method of gas hydrate,visual experiments of propane hydrate formation have been carried out to study the influence of pressure turbulence on growth process promotion and formation parameters including layer thickness,growth rate and driving force have been analyzed with driving force calculation in formation process.The results show that,after35 hours' suspension,hydrate reaction restarts when the pressure was increased to the initial pressure,0.1 MPa higher than that before turbulence,and thickness at gas liquid interface linearly increases at the rate of 0.5 mm/h in first two hours and sharply decreases subsequently,and average growth rate is 0.04 mm/h in 175 hours after turbulence.

title: Propane Clathrate Hydrate Formation Accelerated by Methanol.
abstract: The role of methanol as both an inhibitor and a catalyst for the formation of clathrate hydrates (CHs) has been a topic of intense study. We report a new quantitative study of the kinetics of propane CH formation at 253 K from the reaction of propane gas with <75 mm ice particles that have been doped with varying amounts of methanol. We find that methanol significantly accelerates the formation reaction with quite small doping quantities. Even for only 1 methanol molecule per 10 000 water molecules, the maximum uptake rate of propane into CHs is enhanced and the initiation pressure is reduced. These results enable more efficient production of CHs for gas storage. This remarkable acceleration of the CH formation reaction by small quantities of methanol may place constraints on the mechanism of the inhibition effect observed under other conditions, usually employing much larger quantities of methanol.

title: The Effect of Pressure Disturbance on the Formation Process of Propane Hydrate
abstract: In order to speed up the formation process of gas hydrate, we investigated the effect of pressure disturbance in the static formation process of propane hydrate in visual reaction cell. The results indicate that, compared with the process of no pressure disturbance, pressure disturbance could promote the formation process of propane hydrate effectively in 100 hours of the experimental process, improving the growth rate of propane hydrate. The average growth rate of propane hydrate reached the degree of 0.0526mm/h, it is 4 times as great as that of no pressure disturbance.

title: Numerical Simulation of a Laboratory scale Experiment for the Hydrate Dissociation Process in Porous Media by Acid Injection
abstract: In this study, to enhance gas recovery from a methane hydrate reservoir, experimental and numerical studies that considered the acid injection process as a secondary gas recovery process after the depressurization operation were conducted. First, we experimentally analyzed the dissociation behavior of propane hydrate (PGH) in porous media by using acid injection and confirmed that the dissociation condition of PGH was shifted to the sides of low temperature and high pressure. This enabled the dissociation to proceed easily as the concentration of the injected acid increased. Then, on the basis of experimental observation, we conducted history matching for the temperature change and gas production behavior during PGH dissociation by acid injection, by varying the initial hydrate saturation, the reaction rate constant for acid consumption, and the intrinsic dissociation rate constant as the calculation parameters. Through history matching, we confirmed the validity of the developed numerical model targeting the dissociation of hydrates in porous media by acid injection.

title: Ice Particle Size and Temperature Dependence of the Kinetics of Propane Clathrate Hydrate Formation
abstract: The effects of ice particle size and temperature on the conversion rate of ice to propane clathrate hydrate are presented in this work. Results from this study are interpreted in terms of the three stage shrinking core model: stage I, initiation of the water and propane enclathration reaction at the surface of the ice particles; stage II, mass transfer through pores on the outer clathrate hydrate shell; and stage III, diffusion of propane molecules through the hydrate layer surrounding the inner core of ice. For the smaller ice particles studied, the initial growth rate and total percent conversion are both higher than for larger particles due to a higher surface to volume ratio. Surprisingly, the peak conversion rate of propane clathrate hydrate increases with decreasing temperatures over the temperature range studied in this work, while the total percent conversion increases for higher temperatures, most likely due to improved mass transfer and diffusion in the later stages of the reaction. For the smal.

title: Experimental Simulation on Dissociation Behavior of Propane Hydrate by Methanol Glycol Solution Injection
abstract: The characteristics of propane hydrate dissociation by methanol injection(mass fraction of 30.0%,60.1%,80.2%,99.5% were investigated using a self made visual equipment.The results indicate that the liquid temperature decreased slowly and the pressure in the reactors grew linearly when the dissociation reaction began,moreover,the dissociation time decrease with the methanol concentration's increase,but the degree of decrease became weaker.The average dissociation rates are 0.020 59~0.045 35 mol/(min*L),and increase linearly with the concentration of methanol solution.Compared with pure water injection,methanol injection reduces dissociation heat of gas hydrate and accelerates gas hydrate dissociation rate.The enhancement of concentration of methanol is benefit to promote dissociation of hydrate.