Method of recovering carbon dioxide from gas and apparatus therefor

Abstract

Provided is a method including the steps of: cooling exhaust gas to a given temperature by use of cold energy of liquefied natural gas; spraying water in a minute-ice generator having been cooled to a given temperature by use of the cold energy of the liquefied natural gas to generate minute ice; and introducing the minute ice and the cooled exhaust gas into a gas hydrate generator so as to cause the minute ice and carbon dioxide in the exhaust gas to react with each other in the gas hydrate generator, thereby generating carbon dioxide hydrate.

Description

TECHNICAL FIELD[0001]The present invention relates to a carbon dioxide separating and recovering method that involves: contacting exhaust gas with particulate ice at a low temperature by use of cold energy of LNG (liquefied natural gas) to generate carbon dioxide hydrate; and then fixing carbon dioxide (CO2) in the exhaust gas to the gas hydrate, thereby recovering the carbon dioxide from the exhaust gas, and also relates to an apparatus therefor.BACKGROUND ART[0002]Recently, methods of recovering carbon dioxide (CO2) included in exhaust gas are developed from the viewpoint of global environmental protection, etc. These methods include, for example, a chemical absorption method, a physical adsorption method, a membrane separation method, and the like.[0003]A chemical absorption method is a method in which carbon dioxide is separated and recovered by making use of properties of an amine absorbing solution which absorbs carbon dioxide at 40° C. to 50° C. and releases carbon dioxide at...

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Benefits of technology

[0009]This invention has been made on the basis of the research and experimental results. The present invention is directed to provide a method of recovering carbon dioxide and an apparatus therefor that consume a less amount of energy by improving gas hydrate formation reaction that generally shows an extremely low production rate at a low temperature and by effectively making use of unused cold energy wasted when LNG used as a fuel is gasified in gas-turbine combined cycle power facilities.

[0025]In addition, according to this apparatus, by recovering unused cold energy wasted when LNG is gasified and by effectively making use of the cold energy, it becomes possible to efficiently recover carbon dioxide hydrate with novel means that allows less energy consumption than that with conventional methods.

Problems solved by technology

However, the chemical absorption method or the physical adsorption method needs the reproduction of an absorbent and an adsorbent, and consume a large amount of energy as well.

As such, it is not necessarily suitable as a method of separating carbon dioxide for fixing carbon dioxide.

However, because the nitrogen molecule and the carbon dioxide molecule included in combustion exhaust gas have substantially the same size, the two kinds of molecules are difficult to separate by this method.

Moreover, it is also said that the purity of the recovered carbon dioxide is low.

However, the method of separating carbon dioxide with gas hydrate, in any case, has difficulty in generating gas hydrate including high-concentration carbon dioxide from exhaust gas with a small content of carbon dioxide such as gas turbine exhaust gas.

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