Challenges in Design of Post Combustion CO2 Capture Facilities

Abstract

Abstract Abu Dhabi imports natural gas for domestic consumption since 2007 and at the same time injects natural gas in oilfields for enhanced oil recovery. Abu Dhabi presently emits significant quantity of CO2 to atmosphere due to its existing thermal power plants and other industries. An opportunity exists to inject CO2 instead of natural gas and release valuable supplies of natural gas for other uses while storing CO2 in acceptable geological formations to reduce greenhouse gas emissions. MASDAR have plans for number of Carbon Capture & Storage (CCS) projects to capture large quantities of CO2 from flue gases, which otherwise are emitted to the atmosphere. Efficient recovery of CO2 from flue gases is not only a technical challenge but also it is the most expensive step of any post combustion CCS project. Approximately 20 MMTPA CO2 is aimed to be captured from existing and future power plants, Aluminium smelter, industrial facilities and oil & gas processing plants from 2020 onwards. This paper presents some of the challenges faced by the design team in (a) flue gas characterization, (b) technology selection for post combustion CO2 capture, (c) provision of utilities, d) finalizing CO2 specifications and (e) assessing potential impact on the environment due to the carbon capture plant. Industry is presently flooded with claims of emerging technologies for capturing post combustion CO2. A brief overview of available technology and key issues — scale-up, high energy demand, validation of technology - is discussed. Large capacity carbon capture plants are associated with high demand for heating and cooling requirements, which lead to engineering challenges for managing such requirements. Strategy adopted to meet these challenges is discussed and a potential solution is proposed. Difficulties encountered in getting the design data, variability in flue gas flow and composition, flue gas treatment requirements are presented. Steps taken to characterize the flue gas composition for the design of the carbon capture plant are discussed. Results of flue gas testing and analysis are presented. Methodology adapted to identify the most promising technology for post combustion CO2 capture is described. Site specific design challenges such as (a) flue gas characterization, (b) technology selection for post combustion CO2 capture, (c) required CO2 specifications, d) heat integration with the existing plant, e) availability of steam and cooling water f) parasitic CO2 recovery, g) unit optimization and h) options for reducing the energy demand are discussed.