A regeneration tower 7 of a CO 2 recovery unit includes an upper regeneration portion 51 that has a tray portion 45 , a lower regeneration portion 52 provided below the upper regeneration portion 51 and having a liquid dispersion portion 46 , and a supply line L 5 that supplies absorbing liquid stored in the tray portion 45 to the liquid dispersion portion 46 . The supply line L 5 is provided with a heat exchanger 53 , and the absorbing liquid is circulated using the density difference between the absorbing liquid flowing before the heat exchanger 53 and the absorbing liquid flowing after the heat exchanger 53 as a driving force. This reduces the cost of equipment while reducing the power in the delivery of the absorbing liquid in the regeneration portion.
1. A CO 2 recovery unit comprising:
an absorbing tower that allows absorbing liquid to absorb CO 2 in exhaust gas; and
a regeneration tower that allows the absorbing liquid that absorbed CO 2 in the absorbing tower to discharge CO 2 ,
wherein the absorbing liquid that discharged CO 2 in the regeneration tower is reused in the absorbing tower,
wherein the regeneration tower includes:
a first regeneration portion having a first packing layer in which the absorbing liquid that has absorbed CO 2 comes in contact with steam to heat the absorbing liquid and a first tray portion that stores the absorbing liquid that has passed the first packing layer;
a second regeneration portion provided below the first regeneration portion and having a second tray portion, a second packing layer in which the absorbing liquid that has passed the first regeneration portion comes in contact with steam to heat the absorbing liquid, and a liquid dispersion portion that supplies the second packing layer with the absorbing liquid that has passed the first regeneration portion;
a first supply pipe that connects the first tray portion and the liquid dispersion portion to supply the absorbing liquid stored in the first tray portion to the liquid dispersion portion;
a second supply pipe that connects the second tray portion and a part below the second tray portion to supply the absorbing liquid stored in the second tray portion to the part below the second tray portion; and
a reboiler that is provided on the second supply pipe and that is adapted to produce steam by heating the absorbing liquid; and
a heating portion is adapted to produce gaseous CO2 and steam by heating the absorbing liquid,
wherein the first supply pipe includes the heating portion that heats the absorbing liquid to circulate the absorbing liquid using a density difference between the absorbing liquid flowing before the heating portion and the absorbing liquid flowing after the heating portion as a driving force, and
wherein the driving force for circulating the absorbing liquid is generated by the gaseous CO2 and steam generated from the absorbing liquid in the heating portion.
2. The CO 2 recovery unit according to claim 1 , wherein the supply pipe does not have a pumping device that pumps the absorbing liquid or a control portion other than the supply pipe itself that controls a flow rate of the absorbing liquid.
3. The CO 2 recovery unit according to claim 1 , wherein a hydraulic head difference caused by pressure loss in the supply pipe and the heating portion relative to the liquid dispersion portion of the second regeneration portion is equal to or larger than a height difference between the tray portion and the liquid dispersion portion.
4. The CO 2 recovery unit according to claim 1 , wherein the supply pipe does not include a section where gas accumulates.