METHOD OF RECOVERING CARBON DIOXIDE FROM MIXED GAS USING AQUEOUS AMMONIA WITH PREVENTING AMMONIA LOSS AND THE APPARATUS THEREOF

摘要

A method and an apparatus for producing carbon dioxide with a high purity by continuously recovering carbon dioxide contained in a mixed gas without loss of ammonia by using ammonia water as an absorbing solution are provided. An apparatus for producing carbon dioxide with a high purity continuously from a mixed gas containing carbon dioxide comprises: a first absorption tower(1) for selectively absorbing carbon dioxide from flue gas using ammonia water; a stripper(3) for stripping carbon dioxide from ammonia water containing carbon dioxide; a first circulation pump(9) for recirculating ammonia water from the stripper; a third absorption tower(6) for absorbing ammonia gas using water when the ammonia gas is contained in the stripped carbon dioxide in a very small amount; a second absorption tower(5) for removing an ammonia that is contained in a flue gas (14) from a top part of the first absorption tower in a very small amount using water, and sending ammonia-containing water to the third absorption tower; a first heat exchanger(2) for performing a heat exchanging operation between carbon dioxide-containing ammonia water from the first absorption tower and recirculated ammonia water from the stripper; a concentration tower(7) for recirculating a very small amount of ammonia-containing water to the second absorption tower while recirculating the concentrated ammonia water to the stripper by concentrating a portion of ammonia water from a bottom part of the stripper; a first reboiler(4) and a second reboiler(8) mounted on bottom parts of the stripper and the concentration tower; a second circulation pump(11) for recirculating a very small amount of ammonia-containing water discharged from the concentration tower to the second absorption tower; and a second heat exchanger(10) for performing a heat exchanging operation between water discharged from the concentration tower and carbon dioxide-containing ammonia water discharged from the first heat exchanger.