Some Innovative Readily Applicable Proposals for Chemical Separation and Sequestration of CO2 Emissions From Power Plants

Abstract

The goal of the present manuscript is the investigation of two novel systems for partial CO2 capture from the exhausts of fossil fuelled powerplants. These systems should be relatively cheap and easily applicable to existing powerplants with minor modification, in order to make them accessible by a large range of users and favour a significant diffusion of partial CO2 sequestration. Two basic processes were proposed: 1. Absorption with a liquid solution of water and NH3; 2. Absorber/desorber system with a liquid solution of water and phosphates. In the first one, the exhausts react into an absorber column with a liquid sorbent, which is a solution of water and ammonia. The process sequestrates the CO2 in carbammate and bicarbonate and the final product are salt of ammonia, i.e. ammonium carboamate (NH4HCO3) and ammonium bicarbonate (NH4NH2COO). The outgoing streams of this process are the exhaust gas with a reduced content of CO2 and a secondary product formed by salts of ammonium, which have an interesting market potential as fertilizers. The obtained CO2 reduction level was more than 40%, while the amount of secondary products is high enough to get it marketable. In the second process, the exhausts passing through an absorber column react with a liquid sorbent, which is a solution of water and sodium (or potassium) phosphate. The process sequestrates the CO2 in bicarbonate ions by means of the ions phosphate and the outlet stream is a solution of water and phosphate and carbonate ions. This stream is collected in a desorbing column, where the phosphate ions are almost completely regenerated. The CO2 reduction level is always higher than 20% and it can also reach very high values, depending on the parameters of process.

Comparative study of chemical absorbents in postcombustion CO2 capture

“…A novel method of reducing CO 2 emissions from power plants is given by the use of an aqueous ammonia solution, which makes it possible to capture CO 2 as a valuable solid product [3][4][5]. Thus we focused our research on the capture of ammonia salts, as this allows for a much more rational use of the CO 2 than the liquefaction and necessary storage of the gaseous carbon dioxide leaving the absorption process in the case of MEA (Monoethanolamine) and DGA (Diglycolamine).…”