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Research for the formation and stability of CO_2 hydrate in deep sea

深海CO_2水合物的形成及稳定性研究

基本信息

批准号：
07640581
负责人：
KOBAYASHI Yoshihiro
金额：
$ 1.41万
依托单位：
Kumamoto Institute of Technology
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1995
资助国家：
日本
起止时间：
1995 至 1997
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-07640581/
关键词：
Global warming CO_2 hydrate CO_2 diffusion CO_2 injection into sea CO_2 diffusion coefft CO_2 H_2O interface Density of CO_2 solution Power generation by CO_2 liquid CO_2深海投入水和物深海投入

项目摘要

Theoretical and experimental studies have been carried out on the physical behavior of CO_2 under the high pressure and low temperature corresponding to the deep ocean of 3000m depth level focusing on the liquid CO_2. Simultaneously the studies of the injection system of CO_2 into the deep ocean result in the conceptual design of new sophisticated devices aiming at a satble transfer and injection of CO_2 and CO_2 hydrate. CO_2 directly contacting with sea water will be diffused into sea water or hydrate will be formed at the interface of CO_2/water. In this study a pressure and temperature in the deep sea was produced in the pressure vessel then the following facts were observed at the interface of liquid CO_2 and water (1) Instant formation of hydrate film but very slow growth of it (2) Asseleration of formation by stirring the interface (3) Prompt dissolution of hydrate by collapsing a pressure or temperature from an equilibrium conditions accompanying a rapid temperature decrease (4) Hydrate once formed is very stable unless current shear force is imposed. In a pressure vessel of 50-300atm containing liquid CO_2 and water, three principal coefficients of molecular diffusion in water, mass transfer at interface and density change of CO_2 solution have been calculated by using the CFD program developed for this research analyzing the change of CO_2 concentration distribution with time. Basic research of power plant utilizing the low temperature of liquid CO_2 has also been carried out. Further research in future of (1) Longer range pursuit of hydrate change (2) Diffusion from gas CO_2 (3) Diffusion and hydrate on a particle of liquid CO_2 are kept in mind.

本文以液态CO_2为研究对象，对3000 m深海对应的高压低温条件下CO_2的物理行为进行了理论和实验研究。同时，通过对CO_2深海注入系统的研究，提出了以CO_2和CO_2水合物的稳定输送和注入为目标的新型复杂装置的概念设计。CO_2与海水直接接触会扩散到海水中或在CO_2/水界面生成水合物。在压力容器中产生深海压力和温度，在液态CO_2和水的界面上观察到：（1）水合物膜迅速形成，但生长缓慢;（2）搅拌界面使水合物膜形成稳定;通过使压力或温度从平衡条件崩溃并伴随着温度的快速下降而使水合物迅速溶解（4）一旦形成，除非施加电流剪切力，否则HYPOLYSIS非常稳定。在50- 300 atm的压力容器中，采用为研究CO_2浓度分布随时间的变化而开发的计算流体力学程序，计算了CO_2在水中的分子扩散系数、界面传质系数和CO_2溶液的密度变化系数。开展了利用低温液态CO_2发电的基础研究。今后的研究重点是（1）水合物变化的长期追踪（2）气体CO_2的扩散（3）液态CO_2颗粒的扩散和水合物。