The dissolution of limestone, coal fly ash and bottom ash in wet flue gas desulphurization

Show simple item record

dc.contributor.advisor Rutto, H. L. Koech, Lawrence 2017-06-01T03:49:39Z 2017-06-01T03:49:39Z 2015-03
dc.description M. Tech. (Department of Chemical Engineering, Faculty of Engineering and Technology): Vaal University of Technology en_US
dc.description.abstract Strict environmental regulation on flue gas emission has led to the implementation of FGD technologies in power stations. Wet FGD technology is commonly used because it has high SO2 removal efficiency, high sorbent utilization and due to availability of the sorbent (limestone) used. SO2 is removed by passing flue gas through the absorber where it reacts with the slurry containing calcium ions which is obtained by dissolution. This study presents the findings of the dissolution of a calcium-based material (limestone) for wet FGD process. This was done using a pH stat apparatus and adipic acid as acid titrant. Adipic acid was used because of its buffering effect in wet FGD process. The conditions used for this study are similar to what is encountered in a wet FGD process. The extent of dissolution was determined by analyzing the amount of calcium ions in solution at different dissolution periods. The dissolution kinetics were correlated to the shrinking core model and it was found out that chemical reaction at the surface of the particle is the rate controlling step. This study also investigated the dissolution of coal fly ash and bottom ash. Their dissolution kinetics showed that the diffusion through the product layer was the rate controlling step due to an ash layer formed around the particle. The formation of ash layer was attributed to pozzolanic reaction products which is calcium-alumino-silicate (anorthite) compounds were formed after dissolution. The effect of fly ash on the dissolution of rate of limestone was also studied using response surface methodology. Limestone reactivity was found to increase with increase in the amount of fly ash added and the pH was found to be strong function of the rate constant compared to other dissolution variables. The presence of silica and alumina in fly ash led to a significant increase in the specific surface area due to hydration products formed after dissolution. en_US
dc.description.sponsorship Eskom en_US
dc.format.extent xii, 134 leaves: illustrations en_US
dc.language.iso en en_US
dc.subject Flue gas emmission en_US
dc.subject Power stations en_US
dc.subject Limestone en_US
dc.subject Sorbent en_US
dc.subject Acid titrant en_US
dc.subject Adipic acid en_US
dc.subject Dissolution en_US
dc.subject Shrinking core model en_US
dc.subject Coal fly ash en_US
dc.subject Coal bottom ash en_US
dc.subject Pozzolanic reaction products en_US
dc.subject Silica en_US
dc.subject Alumiina en_US
dc.subject.ddc 628.53 en_US
dc.subject.lcsh Coal-fired power plants en_US
dc.subject.lcsh Flue gases -- Desulfurization en_US
dc.subject.lcsh Fly ash en_US
dc.title The dissolution of limestone, coal fly ash and bottom ash in wet flue gas desulphurization en_US
dc.type Thesis en_US

Files in this item

This item appears in the following Collection(s)

Show simple item record

Search DigiResearch

Advanced Search

My Account