Design and Costing of an ION Clean Energy CO2 Capture Plant Retrofitted to a 700 MW Coal-fired Power Station

Abstract

ION Clean Energy’s (ION) advanced solvent is one of the leading solvent systems currently under development for post-combustion carbon dioxide (CO2) capture. ION has partnered with Nebraska Power Public District (NPPD), Sargent & Lundy (S&L), Koch Modular Process Systems (KMPS), and Siemens to design a commercial-scale (700 MW) capture system utilizing ION’s advanced solvent. The resulting CO2 capture plant design utilizes ION’s ICE 21 solvent and was designed to take full advantage of the solvent benefits, which include an efficient physical plant layout, reduced energy requirements, less solvent degradation, lower emissions, and lower capital costs relative to systems built with (U.S. Department of Energy) DOE Bituminous Baselines Study (BBS) case benchmark solvents. This Front-End Engineering and Design (FEED) is the continuation of a successful pre-FEED study on a 300 MW capture system at NPPD’s Gerald Gentleman Station (GGS) in Nebraska, USA, where cost of capture was determined to be approximately $32 per tonne of CO2. The overall objective of this project is to provide a detailed design resulting in an accurate cost estimate for a commercial-scale CO2 capture facility retrofitted onto a 700 MW existing coal-fired power station. The engineering design and costing will be provided at an Association for the Advancement of Cost Engineering (AACE) Class 2 estimate, which will result in cost accuracy in the range of 15 to +20%, supported by completion of up to 70% of the engineering effort. This paper reviews the engineering work completed to support the cost estimate, which includes process flow diagrams, utility flow diagrams, and general arrangement drawings. Balance of plant (BOP) engineering design was also completed to support the costing effort and includes the necessary tie-ins to the power station for steam, electricity, cooling water, makeup water, and flue gas. The culmination of this work is a 3D model of the carbon capture system as integrated at GGS. The 3D model incorporates the capture island and all the BOP modifications and necessary subsystems for the inclusion of the CO2 capture plant and ensure that the necessary level of detailed engineering has been achieved to support the cost estimate. A preliminary cost evaluation is discussed projecting the expected capital cost, operation and maintenance (O&M) cost, and cost of capture outcome based on the above engineering work. The CO2 capture rate efficiency was not confined or restricted for the FEED project but when optimized for this design basis remained at approximately 90% for full load operation. During the periods of turndown for the power plant, the CO2 capture efficiency increases to over 95% from the flue gas to fully utilize the installed equipment. This paper will also discuss the design and engineering challenges encountered while striving to integrate a CO2 capture system onto an existing power station. These challenges are not unique to this installation and include: • Sizing the system to best match the power station demands in a flexible power market • Designing a steam supply system that covers operations at all load conditions • Designing a heat rejection system with limited availability of cooling water resources and other factors that are site specific The project team has integrated several independent studies into this FEED project to address these specific challenges and this paper will review these results.