Thermodynamics-Dynamics Model And Experiment Study Of Coal Bed Methane Hydrate Synthesized

Although there is abundant resource and great consuming potential of natural gas in China, the current ways of storing and transporting are restricted to a great extent by the geographical conditions. This makes gas business regional. The increasing demand of gas requires a new and effective way of storage and transportation to be developed to satisfy the crop of consumers in our country. Meanwhile, as Kyoto Protocol went into effect, we must make more effort to protect the natural environment, which requires us to be out to solve the problem of direct letting out of the coal bed methane.This thesis is trying from a new angle to work out the synthesized mechanism of coal bed methane and design the equipment experimentation. The stability and security of the gas-hydrate under certain conditions can help to turn coal bed methane into gas-hydrate so as to improve the efficiency of storing and transporting the gas from coal mine in its condense form.The thesis starts with microstructure of the gas-hydrate, introduces three basic structures of the gas-hydrate, including thespace constitution of each structure, different hydrate from the combination of different gases and water, and the thermodynamics and kinetics models of the gas-hydrate, and thus guides technologically the designing of the experimentation equipment and the synthesizing of gas-hydrate. We have designed and made the equipment to process the gas-hydrate through our comprehension of such processing conditions as temperature and stress. In order to enlarge the interface of gas and liquid, we employ the method of making the liquid circulate in the reactor instead of the traditional way of mechanical or magnet suspending mixing. By this method, liquid is drawn out from the bottom of the reactor, and then spouts back into the reactor from the tap on the lid, which greatly enlarges the interface of gas and liquid and overcomes such shortages as complicated fixing and consuming too much energy of the traditional methods. During the experiment of processing coal bed methane, we can clearly see three stages of the hydrate: the stage of gas-dissolution, the stage of induction, and the stage of hydrate quick-processing. At the same time, temperature and stress can also affect the processing of hydrate: low temperature and high stress will quicken the process. We study the reason of three stages of the hydrate and how the low temperature or high stress to improve the hydrate in mechanics. Gas-separation experiment is conducted according to the low purity of the coal bed methane. In the experiment, according to the rule that under the same temperature the major components of coalbed methane-methane, nitrogen and oxygen—give rise to different equilibrium stress, methane is turned into hydrate, while nitrogen and oxygen still existing in gaseity, which in the end separates the impure gas from coal bed methane. Comparative ideal separation effect can be reached in the experiment described in the thesis. To know whether this new technique can be industrially applied, the thesis also simply compares the NGH way to store and transport coal bed methane to some other routine ways from an economical prospect. It is found that the NGH way is superior to other ways in economy as well as in technology and security.