Design and cost estimation of a CO2 capture plant from cement flue gas for urea production in Nepal

Abstract

This paper presents a detailed design, cost estimation and sensitivity analysis for establishing a CO2 capture plant for use in urea manufacturing in the context of Nepal. The commercially proven post combustion capture process, monoethanolamine (MEA) solvent based scrubbing, was designed with the help of Aspen Plus to determine the size of scrubbing towers, accessory equipment's and the utilities for capturing 90% of CO2 from the flue gas. The flue gas stream data was obtained from a local cement industry. Our analysis showed that absorber and stripper columns of 10 m and 7 m packing height respectively are required to capture approximately 250 Ktons/year of CO2. The columns will have packing diameters of 6 m and 4 m respectively. The total capital cost and the production cost for the plant of this scale was calculated to be $10 million and $21 million respectively. The bulk of the total production cost, $18 million per year, was the utility (electricity) cost for regenerating the solvent. The profitability of the capture plant was found to be highly sensitive to the electricity cost which presents a huge opportunity for Nepal. Based on our estimate, the total cost per kg of CO2 capture in Nepal will be about $0.086. A 30% lower electricity cost would lower the capture cost to $0.063/kg CO2. The availability of cheap hydropower electricity (lower than $0.01/kWh) makes CO2 capture based urea manufacturing process to be a viable alternative for Nepal. We hope this economic evaluation data will serve as the baseline for the policy makers to undertake a more detailed study on the carbon capture and electrolysis based urea manufacturing plant in the country.