咪唑类离子液体([Bmim][Tf_(2)N])吸收焦油CFD模拟探索

CFD Simulation of Tar Absorption by Ionic Liquids([Bmim][Tf_(2)N])

离子液体是一种新型的绿色溶剂,在吸收领域展现出特有的优势。前期研究表明,咪唑类离子液体([Bmim][Tf_(2)N])对焦油的脱除率可达98%,高于相同条件下的硅油溶剂。但对于焦油-离子液体体系,吸收塔传质规律的研究比较少见。利用吸收塔CFD模型,模拟离子液体吸收焦油模拟物,探究液气比、塔结构参数对塔内气液分布规律和传质特性的影响。模拟结果表明:增加液气比可提高焦油的吸收效果,液气比至0.6 L·m^(-3)后增速放缓,为最小液气比的2.2倍时,脱除率均达95%;增加填料调控孔隙率为0.6~0.8,可提高传质效率;喷嘴角度对苯酚和萘的影响更明显,过大或过小会导致传质恶化;液滴直径过大会降低塔内空间利用率,过小不利于气流稳定,较合适的液滴直径为2 mm。

Ionic liquid is a new type of green solvent,showing unique advantages in the field of absorption.The previous research showed that the tar removal rate of imidazole ionic liquids([Bmim][Tf_(2)N])could reach 98%,higher than that of silicone oil solvent under the same conditions.However,for the tar-ionic liquid system,the study of mass transfer law of absorption tower is still relatively rare.The CFD model of absorption tower was used to simulate the absorption of tar simulant by ionic liquid,and the effects of liquid-gas ratio and tower structure parameters on the gas-liquid distribution and mass transfer characteristics in the tower were explored.The simulation results showed that,increasing the liquid-gas ratio could improve the absorption effect of tar,and the growth rate slowed down after 0.6 L·m^(-3),when it was 2.2 times of the minimum liquid-gas ratio,the removal rate was 95%;The mass transfer efficiency was improved by adding fillers to regulate the porosity to 0.6~0.8;The influence of nozzle angle on phenol and naphthalene was more obvious,too large or too small could lead to the deterioration of mass transfer;Excessive droplet diameter could reduce the utilization rate of space in the tower,and too small droplet diameter was not conducive to the stability of the gas flow,and the more appropriate droplet diameter was 2 mm.