In recent years the greenhouse effect due to CO2 has been pointed out as one of causes of the global warming, and a countermeasure against it is urgently required internationally to protect global environment. CO2 sources range various fields of human activities, including burning of fossil fuels, and demands to suppress their CO2 emission from these sources are on constant increase. In association with this, people have energetically studied means and methods for suppressing emission of CO2 from power generation facilities such as power plants which use an enormous amount of fossil fuels. One of the methods includes bringing combustion exhaust gas of boilers into contact with an amine-based CO2-absorbing solution. This method allows removal and recovery of CO2 from the combustion exhaust gas. Another method includes storing recovered CO2, i.e., not returning the recovered CO2 to the atmosphere.
Various methods are known to remove and recover CO2 from combustion exhaust gas using the CO2-absorbing solution. One of the methods includes contacting the combustion exhaust gas with the CO2-absorbing solution in an absorption tower, heating an absorbing solution having absorbed CO2 in a regeneration tower, and releasing CO2, regenerating the absorbing solution, and circulating the regenerated absorbing solution to the absorption tower again to be reused (Patent document 1).    Patent document 1: Japanese Patent Application Laid-Open No. H7-51537.