SO3 Impact on Amine Emission and Emission Reduction Technology

Abstract

Mitsubishi Heavy Industries, Ltd. (MHI) in collaboration with Kansai Electric Power Co., Inc. (KEPCO) has developed a highly efficient chemical absorbent CO2 removal process called KM CDR Process TM. This process, together with the proprietary KS-1TM solvent has been applied to ten (10) commercial CO2 capture plants with a maximum CO2 capture capacity of 450 metric tons per day (tpd). These commercial plants are providing captured CO2 to the chemical and fertilizer industries, predominantly to enhance urea production. One (1) further commercial CDR plant, 500tpd capacity, is currently under construction in Qatar. Performance data and learnings from these commercial plants are used to make further process improvements and catalyse R&D activities.To provide a greenhouse gas mitigation solution for the power industry, MHI has adapted the KM CDR ProcessTM for coal fired power plant application. Beginning in 1999, MHI have performed a number of test programs assessing plant performance and optimization with coal fired flue gas while evaluating the impact of associated impurities at the 1 tpd pilot test facility in Hiroshima R&D Center. In 2006, MHI constructed a 10 tpd CO2 capture demonstration plant at a commercial 500MW coal fired power plant in Matsushima, Japan. Between 2006 and 2008, MHI operated the 10tpd pilot plant in excess of 6,000hours, trouble shooting and developing the technology. The Matsushima plant lead to MHI successfully beginning operation of the world's largest, 500 tpd, carbon capture plant for coal fired flue gas in June, 2011. The 500tpd capture plant, dubbed Southern Company (SoCo) 500, streams the equivalent of 25MW of flue gas from a coal fired boiler at Alabama Power's Plant Barry. The SoCo 500 plant is an integral part of the world's first fully integrated coal fired flue gas CCS project.In recent years, governments and regulators have begun to examine amine emissions, from amine based CO2 capture facilities, and the associated potential impacts to the environment and human health. It is envisaged that in the near future amine emission reduction will be become a critical requirement for all amine based CO2 capture OEMs.To reduce the amine emissions, MHI introduced the first optimized washing system within an absorber column in 1994, and developed a proprietary washing system in 2003. The washing system is currently operating in ten (10) commercial plants of KM CDR ProcessTM, as a result amine emissions from these plants have been lowered to the ppm level. MHI has continued to improve this technology for further reduction of amine emissions and established “advanced amine emission reduction system”. A series of amine emission test programs have been carried out with various flue gases at the 1 tpd pilot test facility in Japan and the 0.2 tpd mobile CO2 capture test unit, which has been installed at Southern Company's plant Yates in the USA, using both KS-1TM and MEA solvents. During these test programs, MHI found that an increasing SO3 content in flue gas caused a significant increase of amine emissions. The phenomenon was also observed at the SoCo 500 plant and a commercial plant. During the several test programs, MHI applied a proprietary washing system in the commercial CO2 capture plant to remove aerosols, including SO3 mist absorbed amine vapor, from the flue gas stream and confirmed that the amine emission were drastically reduced.MHI is also currently researching amine atmospheric chemistry, i.e. behavior of emitted amine compounds in air from CO2 capture plant, to better understand the potential issues with commercialization of this technology for CCS application.