Novel scrubbing system for post-combustion CO2 capture and recovery: Experimental studies

Abstract

Power plant emissions of flue gas to the atmosphere releases considerable CO2 which is considered to be the main contributor to global warming. Several gas absorption techniques are being investigated to reduce the capital and operating costs for CO2 capture from post-combustion flue gas. Conventional method of CO2 capture by an aqueous solution of monoethanolamine (MEA) and its subsequent stripping in a separate tower with steam at 120°C is highly energy intensive. The low partial pressure of CO2 in the flue gas inhibits the application of CO2-selective membranes unless methods are employed to increase the CO2 partial pressure in the flue gas to be treated. An absorption–stripping technique to potentially bypass the shortcomings of many existing approaches is described here. Bench-scale CO2 capture and recovery from simulated flue gas with and without moisture was demonstrated using an advanced hollow fiber membrane contactor. This was achieved by the use of a novel non-volatile absorbent, consisting of the ionic liquid [bmim][DCA] containing 20wt% polyamidoamine (PAMAM) dendrimer Gen 0. We have employed a simulated humidified flue gas containing around 14% CO2 and demonstrated successful removal of bulk of the CO2 and its recovery in a CO2-concentrated stream; the CO2 concentration achieved in the stripper out stream was ~92vol%. An estimate of the overall volumetric mass transfer coefficient (Kla) for the current CO2-IL-PAMAM Gen 0 system has been obtained.