TECHNO-ECONOMIC EVALUATION OF SELEXOL-BASED CO2 CAPTURE PROCESS FOR ASHAKA CEMENT PLANT

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Department of Engineering

ABSTRACT
This research work assessed the technology used for cement plant by employing an old cement plant with post-combustion CO2 capture using a novel physical solvent (Selexol) commonly known as dimethyl ether polyethylene glycol. The CO2 capture plant was simulated using Aspen Hysys software after the flue gas analysis of the cement plant was carried out. The data obtained from the cement plant such as maximum operating capacity of about 1 million tonne of cement/year with CO2 released at about 500,000 tonnes per year, together with the information from the simulation was used to carry outthe economic evaluation to determine the major equipment size and cost analysis of the CO2 capture process from the cement industry. The capture unit was able to reduce the concentration of CO2 released into the atmosphere from 4.86% to 0.13% in the flue gas accounting for 97% CO2 captured. The CO2 capture cost per tonne of CO2 captured was found to be $58 (?9,333). The Total Operating Cost was estimated at $27,542,469 (?4.5Billion) and the Total Capital cost was estimated at $19,222,886 (?3.08 Billion). The raw material cost was the highest cost in the CO2 capture process with a value of $19,500,000 (?3.1 Billion) representing 71% of the total operating cost.Sensitivity analysis cases of the impact of absorber temperature, pressure and absorber inlet gas temperature on liquid and vapour flow, percentage CO2 recovery, energy consumption, annual operating and capital costs and cost of CO2 captured were studied. The overall result of the analysis shows that Selexol has proven to be thermally, chemically stable and commercially justifiable under the operating conditions used. It is recommended that, the simulation results obtained be retrofitted into the Ashaka cement plant in order to determine the best CO2 capture efficiency and performance which results to the choice of this capture technology.