CO2 Capture from Flue Gas in an Existing Coal-Fired Power Plant by Two Successive Pilot-Scale VPSA Units

CO2 capture and storage (CCS) is an effective method for achieving CO2 mitigation while simultaneously keeping energy supplies secure. To put CCS into practice, it is important to develop energy-efficient industrial technologies for CO2 capture. In this work, a pilot-scale demonstration of carbon capture from flue gas by adsorption technology was performed in an existing coal-fired power plant in China, and the power energy consumption to capture 1 kg of CO2 was measured onsite; furthermore, the feasibility and efficiency of adsorption technology for postcombustion CO2 capture were investigated. The pilot-scale carbon capture plant consisted of two successive VPSA units coupled with a dehumidifying unit. In the dehumidifying unit, water vapor in the desulfurized flue gas was removed by alumina adsorption. Then, CO2 in the dehumidified flue gas was captured by two successive VPSA units, where the three bed eight step VPSA process was employed in the first unit packed with zeolite 13X APG, and the second two-bed six-step VPSA unit was packed with pitched activated carbon beads. A roots blower was used to supply the desulfurized flue gas to the pilot-scale carbon capture plant at a controlled flow rate, and both a reciprocating pump and a diaphragm pump were employed to desorb adsorbents under vacuum pressure in the two stage units and recover high-purity CO2 for subsequent storage or utilization. Some key assessment parameters were measured onsite, including the flow rate of flue gas, CO2 recovery from flue gas, CO2 purity in the product gas, and power energy consumption to capture 1 kg of CO2, and the experimental results were verified by numerical simulations using a multibed VPSA modeling framework Based on the experimental and simulated results, CO2 capture from flue gas in an existing coal-fired power plant by two successive VPSA units was evaluated.