Acid gas recovery method and system and iron ion analysis method and system

1. An acid gas recovery method, comprising:

removing acid gas from a target gas by bringing the target gas containing the acid gas into gas-liquid contact with an absorbent amine solution and causing the absorbent amine solution to absorb the acid gas;

regenerating the absorbent amine solution by releasing the acid gas from the absorbent amine solution that has absorbed the acid gas;

causing a chelate resin to adsorb iron ions including iron ions dissolved from an iron device material, from the absorbent amine solution after contact with the target gas or after regeneration by causing the absorbent amine solution to pass through the chelate resin;

causing a regenerant solution to pass through the chelate resin having iron ions adsorbed thereon;

regenerating the chelate resin and obtaining a regenerant solution containing the iron ions; and

quantitatively measuring the iron ions in the regenerant solution containing the iron ions and calculating a concentration of iron ions in the absorbent amine solution.

2. The acid gas recovery method according to claim 1 , further comprising removing the iron ions from the absorbent amine solution after regeneration when the calculated concentration of iron ions in the absorbent amine solution is higher than a threshold value.

3. An acid gas recovery system, comprising:

an absorption tower that removes acid gas from a target gas by bringing the target gas containing the acid gas into gas-liquid contact with an absorbent amine solution and causing the absorbent amine solution to absorb the acid gas;

a regeneration tower that regenerates the absorbent amine solution by releasing the acid gas from the absorbent amine solution that has absorbed the acid gas in the acid gas absorption tower;

a sample preparing device for iron ion quantitative measurement that causes a chelate resin to adsorb the iron ions from the absorbent amine solution, separates the iron ions from the absorbent amine solution, desorbs the iron ions from the chelate resin, and provides a solution sample containing the desorbed iron ions;

an iron ion quantitative measurement device that is connected to the sample preparing device for iron ion quantitative measurement via a line capable of passing through the solution sample, and that quantitatively measures the iron ions in the solution sample provided by the sample preparing device; and

a controller that is communicably connected to on-off valves on an inlet and an outlet of the sample preparing device for iron ion quantitative measurement such that on and off of the on-off valves are controlled, that is communicably connected to the iron ion quantitative measurement device, and that calculates a concentration of iron ions in the absorbent amine solution from a result of quantitative measurement for the iron ions by the iron ion quantitative measurement device,

wherein the sample preparing device for iron ion quantitative measurement and the iron ion quantitative measurement device are located on a line for supplying the absorbent amine solution that has absorbed the acid gas from the absorption tower to the regeneration tower, or are located on a line for supplying the regenerated absorbent amine solution from the regeneration tower to the absorption tower.

4. The acid gas recovery system according to claim 3 , further comprising a device that is located on the line for supplying the regenerated absorbent amine solution from the regeneration tower to the absorption tower, that is communicably connected to the controller such that an operation thereof is controlled by the controller, and that removes the iron ions from the absorbent amine solution after regeneration when the calculated concentration of iron ions in the absorbent amine solution is higher than a threshold value.

5. An iron ion analysis method in an absorbent amine solution, comprising:

causing a chelate resin to adsorb iron ions from an absorbent amine solution by causing the absorbent amine solution to pass through the chelate resin;

desorbing the iron ions to regenerate the chelate resin by causing a regenerant solution to pass through the chelate resin with the iron ions adsorbed thereon, and obtaining the regenerant solution containing the desorbed iron ions; and

quantitatively measuring the iron ions in the regenerant solution containing the iron ions and calculating a concentration of iron ions in the absorbent amine solution.

6. The iron ion analysis method according to claim 5 , further comprising removing the iron ions from the absorbent amine solution when the calculated concentration of iron ions in the absorbent amine solution is higher than a threshold.

7. An iron ion analysis system in an absorbent amine solution, comprising:

a sample preparing device for iron ion quantitative measurement that causes chelate resin to adsorb the iron ions from the absorbent amine solution, separates the iron ions from the absorbent amine solution, desorbs the adsorbed iron ions from the chelate, and provides a solution sample containing the desorbed iron ions;

an iron ion quantitative measurement device that is connected to the sample preparing device for iron ion quantitative measurement via a line capable of passing through the solution sample, and that quantitatively measures the iron ions in the solution sample provided by the sample preparing device; and

a controller that is communicably connected to on-off valves on an inlet and an outlet of the sample preparing device for iron ion quantitative measurement such that on and off of the on-off valves are controlled, that is communicably connected to the iron ion quantitative measurement device, and that calculates a concentration of iron ions in the absorbent amine solution from a result of quantitative measurement for the iron ions by the iron ion quantitative measurement device.

8. The iron ion analysis system according to claim 7 , further comprising a device that is communicably connected to the controller such that an operation thereof is controlled by the controller, and that removes the iron ions from the absorbent amine solution before iron ion removal when the calculated concentration of iron ions in the absorbent amine solution is higher than a threshold value.