Method for capturing CO
The present invention relates to a method for capturing CO 2 from exhaust gas in an absorber (A 1 ), wherein the CO 2 containing gas is passed through an aqueous absorbent slurry wherein said aqueous absorbent slurry comprises an inorganic alkali carbonate, bicarbonate and at least one of an absorption promoter and a catalyst, and wherein the CO 2 is converted to solids by precipitation in the absorber, said slurry having the precipitated solids is conveyed to a separating device (F 1 ), in which the solids are separated off, essentially all of at least one of the absorption promoter and catalyst is recycled together with the remaining aqueous phase to the absorber.
1. A method for capturing CO 2 from exhaust gas in an absorber, wherein the CO 2 containing gas is passed through an aqueous absorbent slurry, wherein the aqueous absorbent slurry comprises an inorganic alkali carbonate, bicarbonate and at least one of an absorption promoter and a catalyst, and wherein the CO 2 is converted to solids by precipitation in the absorber, and where the slurry having the precipitated solids is conveyed to a separating device, in which the solids are separated off in the form of a filter cake, which is washed, and, by which, essentially all of the at least one of the absorption promoter and the catalyst is recycled together with a remaining aqueous phase to the absorber, and the filter cake, containing a minimum of the promoter, is dewatered, heated and conveyed to a desorber for the release of CO 2 , and is subsequently returned to the absorber.
2. The method according to claim 1 ,
wherein the precipitated solids contain bound CO 2 as bicarbonate, as an aminoacid-salt/CO 2 -complex or as a complex with limited solubility formed by an amine and CO 2 .
3. The method according to claim 1 , wherein the inorganic alkali carbonate is at least one of the following: Li 2 CO 3 , Na 2 CO 3 and K 2 CO 3 .
4. The method according to claim 1 , wherein the at least one of the absorption promoter and the catalyst is: piperazine, N-2-hydroxyethylpiperazine, N-(hydroxypropyl)piperazine Diethanol triamine (DETA), 2-((2-aminoethyl)amino)ethanol (AEEA), monoethanolamine (MEA), diethanolamine (DEA), diisopropanolamine (DIPA), methylaminopropylamine (MAPA), 3-aminopropanol (AP), 2,2-dimethyl-1,3-propanediamine (DMPDA), 3-amino-1-cyclohexylaminopropane (ACHP), diglycolamine (DGA), 2-amino-2-methylpropanol (AMP), 1-amino-2-propanol (MIPA), 2-methyl-methanolamine (MMEA), piperidine (PE), arsenite, hypochlorite, sulphite, enzyme carbonic anhydrase; and amino acids selected from the group consisting of glycine, sarcosine, alanine N-secondary butyl glycine and pipecolinic acid.
5. The method according to claim 1 , wherein a temperature in the absorber is in a range of from 30 to 100° C.
6. The method according to claim 1 , wherein solid separation is performed in at least one of the following: a rotating filter, a stationary filter, a cyclone, a hydrocyclone and a sedimentation unit.
7. The method according to claim 1 wherein the absorber is a packed tower, a plate tower or a spray tower.