Heat recovery system and heat recovery method

Abstract

A heat recovery system includes a preheater ( 4 ) in which heat exchange is performed between condensed water generated in a condenser ( 3 ) and CO2 in a CO2 recovery apparatus, a gas heater ( 5 ) in which heat exchange is performed between the condensed water heated in the preheater ( 4 ) and exhaust gas discharged from a boiler ( 7 ) and the boiler ( 7 ) to which the condensed water heated in the gas heater ( 5 ) is supplied as boiler supply water. With this configuration, an amount of steam extracted from a low-pressure steam turbine ( 2 ) is reduced.

1 . A heat recovery system comprising:
 a CO 2  recovery apparatus which includes an absorbing tower that absorbs CO 2  in exhaust gas into absorbing liquid and a regeneration tower that discharges CO 2  from the absorbing liquid that absorbed CO 2  in the absorbing tower to reuse the absorbing liquid that discharged CO 2  in the regeneration tower in the absorbing tower;   a steam turbine;   a condenser which condenses steam discharged from the steam turbine;   a first heat exchange portion in which heat exchange is performed between condensed water generated in the condenser and CO 2  recovered in the regeneration tower of the CO 2  recovery apparatus;   a second heat exchange portion in which heat exchange is performed between the condensed water heated in the first heat exchange portion and exhaust gas discharged from a boiler; and   the boiler to which the condensed water heated in the second heat exchange portion is supplied as boiler supply water.   
     
     
         2 . The heat recovery system according to  claim 1 , wherein an entire amount of condensed water generated in the condenser is used as the condensed water subjected to heat exchange in the first heat exchange portion and the second heat exchange portion. 
     
     
         3 . The heat recovery system according to  claim 1 , wherein a water supply heater which heats the condensed water generated in the condenser by steam extracted from the steam turbine and supplies the heated condensed water to the boiler is not included. 
     
     
         4 . The heat recovery system according to  claim 1 , further comprising a third heat exchange portion which heats the condensed water heated in the second heat exchange portion and returns the heated condensed water to the second heat exchange portion, and
 a control portion which switches between the boiler or the third heat exchange portion as a supply destination of the condensed water heated in the second heat exchange portion.   
     
     
         5 . A heat recovery method which uses a CO 2  recovery apparatus including an absorbing tower that absorbs CO 2  in exhaust gas into absorbing liquid and a regeneration tower that discharges CO 2  from the absorbing liquid that absorbs CO 2  in the absorbing tower and reuses the absorbing liquid that discharged CO 2  in the regeneration tower in the absorbing tower, the method comprising:
 a first step of condensing steam discharged from a steam turbine;   a second step of performing heat exchange between generated condensed water and CO 2  recovered in the regeneration tower of the CO 2  recovery apparatus in a first heat exchange portion;   a third step of performing heat exchange between the condensed water heated in the first heat exchange portion and exhaust gas discharged from a boiler in a second heat exchange portion; and   a fourth step of supplying the condensed water heated in the second heat exchange portion to the boiler as boiler supply water.   
     
     
         6 . The heat recovery method according to  claim 5 , further comprising a fifth step of heating the condensed water heated in the second heat exchange portion in a third heat exchange portion which is different from the boiler and heating the condensed water heated in the third heat exchange portion in the second heat exchange portion.