Coupling of oxygen-enriched combustion and CO 2 capture by membrane processes

This study aims to investigate a new technological solution for CO 2 capture from fossil fuel burning power plants. It consists of coupling an oxygen-enriched combustion (typically 30-80% O 2) with a CO 2 capture by membrane separation processes. This offers a CO 2 capture process with a greatly reduced energetic cost compared to conventional post-combustion or oxycombustion processes. The overall purpose of the present work is to maximize the energy production by combustion while ensuring a correct operation of the global process in compliance with environmental legislations. First, a feasibility study is performed with numerical simulations of the energy required for this "hybrid" process. In parallel, combustion kinetics simulations are performed in order to determine the best combustion conditions. This numerical approach is now under experimental validation in a counter-flow burner at LCD and in a model gas turbine chamber at CORIA. Introduction Carbon dioxide Capture and Storage (CCS) represents a promising option for the reduction of greenhouse gas emissions from fossil fuel-fired power plants [1]. Much of the research in this area focuses on minimizing the energy required for CO 2 capture. While pre-combustion capture offers the most promising alternative for integrated coal gasification combined cycle or natural gas combined cycle power plants [2], post-combustion is usually inescapable for other industrial plants (cement, steel, glass, refineries, chemical plants, etc). The application of this latter technology is still not developed because of high cost (around 40 € per ton of CO 2 captured) for which the capture step dominates, typically 60-80% of the overall cost of the capture-transportation-injection for storage chain. A reduction of this cost is then required. From a practical point of view, CO 2 capture in post-combustion process is currently envisaged through two aspects: i) High purity oxygen supply (oxycombustion) to avoid dilution with nitrogen, leading to the capture of concentrated CO 2 by a simple drying operation; ii) CO 2 capture in the exhaust gas of a conventional process with air supply (CO 2 content is usually between 4 and 15 % depending on the fuel type) using separation process like absorption in liquids (amine washing). The global objective is to ensure a CO 2 capture rate of 80 to 90% while producing a flue gas containing 80% of CO 2 (to allow transportation and sequestration) with a minimal energy consumption (typically less than 2GJ per ton of CO 2 captured) [3]. The investigation of a technological solution, allowing minimization of the energy requirement while ensuring high CO 2 concentration, is the major purpose of this study. The basic concept relies on a novel approach based on an association of combustion and capture,