New Energy Efficient Processes and Newly Developed Absorbents for Flue Gas CO2 Capture

Abstract

The Kansai Electric Power Co., Inc. (KEPCO), in collaboration with Mitsubishi Heavy Industries, Ltd. (MHI), has developed a variety of energy efficient chemical absorbents and economical processes (KM CDR ProcessTM) which aim to reduce the cost of CO2 capture. This work has been ongoing since 1991, using several Japan based R&D facilities, a CO2 capture pilot plant, located at Nanko Power Station in Osaka, Japan and a large scale demonstration plant at Southern Company's Plant Barry.Highly successful R&D has led to the rapid commercial deployment of ten (10) currently active, KM CDR ProcessTM, commercial CO2 capture plants. In addition one (1) plant is now under construction in Qatar (commissioning in 2014). These commercial plants are deployed exclusively in the chemical and fertilizer industries. The KM CDR ProcessTM and KS-1TM have also been utilized at the large scale CCS demonstration plant in the USA, the 500 tons per day (tpd) Southern Company Project, the first project in the world to demonstrate black coal ‘full chain’ CCS. Application for both natural gas and Coal flue gas highlights the versatility and robustness of both the solvent and the process.Recent work has focused on further developing energy efficient chemical absorbents and reducing the energy penalty for further cost reduction. To select absorbents which feature the best profile and fit to the actual operating conditions KEPCO and MHI have intensively evaluated the vapour-liquid equilibrium (VLE) and reaction kinetics for a range of newly developed absorbents. One of these absorbents has a reaction rate 1.4 times faster than that of KS-1TM, while having similar CO2 loading and reaction temperatures. The thermal energy requirement for CO2 recovery was reduced by 9% compared with KS-1TM to 1.19 t-steam/t-CO2 (in-plant auxiliary steam which corresponds to LP steam) following testing at the Nanko pilot plant using the combination of this absorbent and the commercial KM CDR ProcessTM.In parallel with these developments, KEPCO and MHI have continued to improve the KM CDRProcessTM by optimizing the pilot plant and further improving the thermal energy requirement to 1.09 t- steam/t-CO2 (in-plant auxiliary steam which corresponds to LP steam).In 2011, modifications to the Nanko CO2 capture Pilot Plant lead to the development of a new commercial application termed the “New Energy Efficient Process 3” or “NEEP3”. The combination of the newly developed absorbents and “NEEP3” achieved the lowest yet thermal energy requirement, 1.00 t-steam/t-CO2 (in-plant auxiliary steam which corresponds to LP steam). During the same testing period,KS-1TM achieved a thermal energy requirement of 1.03 t-steam/t-CO2 (in-plant auxiliary steam which corresponds to LP steam).This manuscript introduces and presents the current status of the KEPCO/MHI CO2 capture technology and concepts for future energy reduction improvements. The paper also includes test results in relation to the newly developed absorbent, and the “NEEP3” described above, which has enhanced the performance and markedly reduced the energy penalty of the CO2 capture process. KEPCO and MHI are continuing the development of efficient absorbents and optimizing processes, thus helping to facilitate the future wide scale deployment of CO2 capture technology as an effective counter measure against climate change.