Quantitative Analysis Of Methane Hydrate In Closed System By Raman Spectroscopy

With the social and economic development, energy shortage is particularly urgent to besolved. Methane hydrate (lfammable ice) is a kind of new energy, which is widely distributed,and burning eiffciently and cleanly. It’s crucial to know the hydrate’s physical and chemicalproperties, so that we can exploit and use it reasonably in the future. The microscopic growthmechanism of hydrate and quantitative analysis is mainly studied by theoretical calculation,computer simulation, or traditional experimental ways (such as temperature, pressure,electrical resistivity, gas lfow rate, etc.). This thesis carries out experiments to investigate thedetails of hydrate growth mass transfer and phase change by Raman spectroscopy. We invertthe growth or decomposition process of hydrate, aiming to providing valuable reference forthe study of hydrate kinetic mechanism.The main work of this paper includes the following two aspects:(1) the growth processof methane hydrate was observed online in the capillary quartz tube, which were made bymethane-solution with different reaction conditions. The law of time and space at the processof hydrate formation was summed up.(2) An experiment method about quantitative analysisfor the calculation of methane hydrate in a closed system was established and the empiricalequation of methane hydrate content was summarized.Analysis on the Raman spectra characteristics of hydraet growth process showed that thehydrate forming the critical crystal nucleus with gather to form the visual forms of C-HRaman spectra are signiifcantly different. We take it the note of distinguishing the narrowinduction time and generalized induction time, which is more reliable than macroscopicmeasurements. When hydrate dissociates in the temperature above the phase equilibrium, themore time it keeping at that temperature, the longer the induction time is needed to show the"memory effect". Hydrate grows ifrstly near the interface between gas and liquid in thecapillary and the ifll rate of the big or small cages is higher than other region. The unsaturateddegree of cages in the region far away rfom the interface is higher. The content of dissolved methane at different positions show that the rate of diffusion of dissolved methane in thewater is lower than the growth rate of consumption of methane hydrate.Taking K2SO4solution as matrix, we establish a quantitative relationship of the intensityof Raman spectroscopy and mass concentration. By monitoring methane hydrate K2SO4solution system growth process online in a transparent capillary quartz tube, spectral intensitychanges response the changes of the mass concentration. Since the volume of the capillary isvery small, gas-liquid transfer and ion diiffision exists larger unevenness, the calculationresult in a large error. With ion parameters real-time detection device, we can sample at thesame pressure as the device. Repeat the above experiment, and to establish a relationship ofmethane hydrate content and solution Raman intensity quantitative calculation. We compareboth the amount of methane hydrate in the calculation in order to obtain the gas methanewithin the pressure change and the change of the concentration of the solution in the reactionapparatus. We also calculate the total amount of methane hydrate and ifnd the spectra in timecalculation result to be behind the change in the gas pressure.Finally, on the based on all the work, this paper make an outlook of this ifled，and put outseveral remarks on the hydrate kinetic mechanism research in the tfirther...