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.

1 . A method of recovering carbon dioxide from exhaust gas by gas-hydrating the carbon dioxide, the method comprising the steps of:
 cooling the 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.   
     
     
         2 . The method of separating and recovering carbon dioxide from exhaust gas according to  claim 1 , characterized in that exhaust gas cooled to approximately −70° C. to −100° C. by use of the cold energy of the liquefied natural gas is caused to contact with minute ice having a particle diameter of approximately 0.1 μm to 10 μm to thereby generate carbon dioxide hydrate. 
     
     
         3 . An apparatus of recovering carbon dioxide from exhaust gas by gas-hydrating the carbon dioxide, the apparatus comprising:
 a spray nozzle;   a minute-ice generator which freezes particulate droplets of water sprayed from the spray nozzle by use of cold energy of liquefied natural gas to generate minute ice; and   a gas hydrate generator into which the minute ice and exhaust gas cooled by use of the cold energy of the liquefied natural gas are introduced to generate carbon dioxide hydrate.   
     
     
         4 . The apparatus of recovering carbon dioxide from exhaust gas according to  claim 3 , characterized in that
 the exhaust gas in the gas hydrate generator is circulated between the gas hydrate generator and a circulating-gas cooler outside the gas hydrate generator, and   the exhaust gas is cooled by the circulating-gas cooler which makes use of the cold energy of the liquefied natural gas.   
     
     
         5 . The apparatus of recovering carbon dioxide in exhaust gas according to  claim 3 , characterized in that
 reaction heat generated in the gas hydrate generator is removed by using the exhaust gas cooled by use of the cold energy of the liquefied natural gas.   
     
     
         6 . An apparatus of recovering carbon dioxide from exhaust gas, the apparatus comprising:
 an exhaust gas precooler which precools exhaust gas by using low temperature-low pressure exhaust gas that has been depressurized to near an atmospheric pressure after carbon dioxide separation and recovery;   an exhaust gas compressor which pressurizes the low temperature exhaust gas precooled by the exhaust gas precooler to a pressure necessary for gas hydrate generation;   an exhaust gas recooler which recools the exhaust gas compressed by the exhaust gas compressor by use of low temperature-high pressure exhaust gas after the carbon dioxide separation and recovery;   an exhaust gas expander which expands the high pressure exhaust gas up to an atmospheric pressure, the exhaust gas having been subjected to a rise in temperature by the exhaust gas recooler; and   a gas hydrate generating device,   wherein the gas hydrate generating device includes:
 a generation water pump which pressurizes generation water up to a pressure necessary for reaction; 
 an assist gas compressor which pressurizes part of the exhaust gas up to an assist gas pressure necessary for spraying of the generation water; 
 a spray nozzle which atomizes the generation water introduced therein together with assist gas; 
 a minute-ice generator which generates minute ice by freezing the droplets of water atomized by the spray nozzle by use of cold energy of liquefied natural gas; 
 a gas hydrate generator made up of a plurality of reaction vessels which are connected to each other meanderingly, and in which the minute ice and exhaust gas cooled by use of the cold energy of the liquefied natural gas are introduced; 
 an exhaust gas circulation loop which substantially circularly connects the reaction vessels to each other through communication tubes; and 
 a circulating-gas cooler which cools the exhaust gas circulating in the plurality of reaction vessels with the liquefied natural gas.