Gas separation: processes – Liquid contacting – Hydrate inhibitor
Reexamination Certificate
2001-06-07
2003-08-05
Smith, Duane S. (Department: 1724)
Gas separation: processes
Liquid contacting
Hydrate inhibitor
C095S236000, C096S235000, C423S220000, C423S226000, C585S015000
Reexamination Certificate
active
06602326
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a method for separation of gas constituents employing a hydrate promoter, more specifically, to a method for separation of gas constituents from a multicomponent gaseous mixture comprising the steps of reacting an aqueous solution containing a hydrate promoter with a multicomponent gaseous mixture to form a gas hydrate condensed with gas constituents of high gas hydrate forming power and dissociating a specific gas component from the gas hydrate.
BACKGROUND OF THE INVENTION
Carbon dioxide, methane and freon gases have been regarded as major causes of global warming, which drives researchers to develop methods for recovering the exhaust gases containing these gases generated from various industrial areas. The global warming gases, however, are emitted in the forms of multicomponent gaseous mixtures in most of the exhaust gases, rather than in a single gas component. Naturally, the needs have been increased to develop a method for separating and recovering a specific gas component from the exhaust gaseous mixtures.
The gas separation methods developed thus far, which are largely classified depending on the natures of separation system and desired gas component, include cryogenic fractionation, adsorption by solid adsorbents, gas absorption by liquid solvent, etc. These methods were partly successful in separating a gas component from a multicomponent gaseous mixture, but revealed a shortcoming of high energy consumption. The use of large quantity of energy is a major cause that lowers the economical efficiency in most industrial spots. For this reason, a variety of researches have been extensively made on developing methods for separating gas constituents from the multicomponent gaseous mixtures in an economical and efficient manner.
For example, U.S. Pat. No. 5,434,330 discloses a method for removing nitrogen gas from natural gas containing methane as a major component by dissociating a hydrate suspension formed by bringing an aqueous solution and multicomponent gaseous mixture into a contact to give an exhaust gas with decreased concentration of gas hydrate forming component. U.S. Pat. No. 5,700,311 teaches a method for selective removal of carbon dioxide from multicomponent gaseous mixtures employing a gas hydrate, which revealed defects caused by the nature of gas hydrate formation, i.e., the extremely high pressure for gas hydrate formation(e.g., 143 bar for nitrogen or 125 bar for oxygen), accompanies risky factors and requires an auxiliary pressure-resistant equipment. Naturally, it makes the separation and operation complicate and difficult, and shows very low cost-efficiency.
Under the circumstances, to overcome the problems of the prior art methods, there are strong reasons for developing and exploring a method for separating a specific gas component from a multicomponent gaseous mixture under the conditions of lower temperature and pressure in a safe and economical manner.
SUMMARY OF THE INVENTION
The present inventors have made an effort to develop a method for separating a specific gas component from a multicomponent gaseous mixture under mild conditions of low temperature and pressure, and discovered that: acetone, propylene oxide, 1,4-dioxane, or tetrahydrofuran(THF) employed to form a gas hydrate, bring promotion effect which increases gas hydrate equilibrium temperature with lowering pressure, and they play a role as a hydrate promoter to make possible the successful separation of a specific gas component from a multicomponent gaseous mixture under a low pressure for gas hydrate formation.
A primary object of the present invention is, therefore, to provide a method for separation of gas constituents from multicomponent gaseous mixtures by employing a hydrate promoter.
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Kang, et al.,SHhydrate equilibria of(methane+water+2-methylbutane=magnesium chloride), (methane+water+2,2-dimethylbutane+magnesium chloride), and (methane+water+methylcyclohexane+magnesium chloride);J. Chem. Thermodynamics31:763-772 (1999).
Kang Seong-Pil
Lee Huen
Knobbe Martens Olson & Bear LLP
Korea Advanced Institute of Science and Technology
Smith Duane S.
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