COAL-FIRED BOILER SYSTEM INCLUDING CARBON DIOXIDE RECOVERY SYSTEM

PROBLEM TO BE SOLVED: To effectively utilize heat of a CO2 recovery system using an absorbing liquid by focusing attention on heat which is hardly utilized due to a small temperature difference in the CO2 recovery system using the absorbing liquid.SOLUTION: By focusing on heat quantity to lower a lean liquid after heat exchange between the absorbing liquid (lean liquid) from which CO2 is desorbed, and the absorbing liquid (rich liquid) which absorbs CO2, to a temperature for absorbing CO2, the water from a steam condenser is used as its refrigerant. Further, the water from the steam condenser and the lean liquid after heat exchange between the lean liquid and the rich liquid, are made to easily exchange heat by using another medium, by providing temperature difference by a heat pump for compressing and expanding the medium. The water from the steam condenser is successively heated by using extraction steam from the steam turbine by a plurality of low-pressure supply water heaters connected in series. The water from the steam condenser is branched, so that one of them is supplied to an inlet of the most upstream low-pressure supply water heater, and the other is supplied to an inlet of the most downstream low-pressure supply water heater among the plurality of low-pressure supply water heaters, after increasing its temperature by the heat pump.