活性炭捕集燃煤烟气中二氧化碳的模拟分析

Simulation of capturing carbon dioxide from flue gas by activated carbon

为探究适合描述活性炭吸附CO_2的数学模型和蒸汽吹扫再生CO_2的固体吸附工艺,使用Aspen Adsorption模拟固定床动态吸附烟气中CO_2的过程.模拟与实验的穿透曲线的对比表明,与采用纯组分吸附、Particle MB传质模型得到的模拟结果相比,采用理想吸附-线性阻力模型(IAS-LDF组合模型)得到的模拟结果与实验数据的一致性更高.建立完整变温吸附模型,使用高温蒸汽和吸附后烟气分别加热和冷却再生床,分析吹扫温度、吸附/脱附时间对CO_2捕集率、产品纯度和分离能耗的影响.结果表明,提高吹扫温度能够较大地提升捕集率,并且需要增加的能耗较少,但是对产品纯度的提升较小.当吸附/脱附时间为2～4 min时,吹扫温度从100°C升到200°C,捕集率平均提高了11.1%,能耗提升了13.9%,产品纯度仅平均提高了1.7%.提高吸附/脱附时间能够显著提升产品纯度,但是会降低捕集率和增加较多的能耗.在100～200°C吹扫温度下,吸附/脱附时间从2 min增加到4 min,产品纯度平均提升了13.6%,CO_2捕集率平均下降了4.8%,能耗提升了43.1%.

Dynamical adsorption of CO2 in flue gas by fixed-bed was simulated by Aspen Adsorption to investigate the suitable mathematical model for CO2 adsorption by activated carbon and the solid adsorption process for regenerating CO2 using steam blowing.Comparison between simulative and experimental breakthrough curves showed that the simulation data with ideal adsorption solution-linear diver force(IAS-LDF)model was more coincident with experimental data than results of models using pure component adsorption or Particle MB model.A complete temperature swing adsorption model was established,and the fixed-bed was heated and cooled respectively by high-temperature steam and adsorbed flue gas.The effects of purge temperature,adsorption/desorption time on CO2 capture rate,product purity and energy consumption were analyzed.The results showed that the increase of purge temperature enhanced the capture rate significantly and raised energy consumption slightly,but had few effects on the product purity.When the purge temperature increased from 100°C to 200°C with the adsorption/desorption time of 2~4 min,the capture rate increased by 11.1%,the energy consumption increased by 13.9%,and the product purity increased by 1.7%.The increase of adsorption/desorption time greatly improved the product purity,but reduced the capture rate and increased the energy consumption obviously.When the adsorption/desorption time increased from 2 min to 4 min with the purge temperature of 100~200°C,the product purity increased by 13.6%,the capture rate of CO2 decreased by 4.8%,and the energy consumption increased by 43.1%.