混合吸附质在废活性炭热再生过程中的受热脱附研究

Study on the Thermal Desorption of Mixed Adsorbent in the Thermal Regeneration Process of Waste Activated Carbon

摘要: 在废活性炭热再生过程中，吸附质受热脱附是关键过程。在实际脱附过程中，由于残余吸附质的存在，传统模型导致模拟结果不准确。本文建立了一个多相多孔介质传热传质模型，它可以计算废活性炭中混合吸附质的受热脱附特性并能体现残余吸附质的存在，与传统模型相比准确性有显著提高。通过计算仿真结果与实验结果的对比，验证了该模型应用的可行性。基于模拟与理论分析得出：在恒温加热条件下，废活性炭样品的温升和液相含量的变化趋势分别体现“快–慢–快”和“慢–快–慢”的特点；热再生样品内部的流体流动以蒸汽流动为主液体流动为辅，蒸汽流动中黏性流动占比90%，液体流动主要由达西摩擦力驱动。该模型可以帮助避免过多的加热时间，以确保吸附质的完全热脱附。

Abstract: In the thermal regeneration of spent activated carbon, thermal desorption of adsorbent is the key process. The conventional model, due to its inability to account for residual adsorbent, generates imprecise simulation outcomes. This paper presents an improved heat and mass transfer model for multi-phase porous media, which provides an accurate depiction of thermal desorption dynamics of diverse adsorbents in waste activated carbon, including the residual ones. This advancement nota-bly elevates the precision and reliability of predictions compared to the traditional model. A com-parative analysis of computational simulation results with experimental findings served to authen-ticate the model’s practical applicability. With the aid of these simulations and theoretical scrutiny, under stable heating conditions, a distinct behavior was identified in both the temperature rise and the liquid phase content of the waste activated carbon samples, which followed a “fast-slow-fast” and “slow-fast-slow” trajectory respectively. The analysis revealed that fluid movement within the thermally regenerated samples primarily involved vapor flow, augmented by liquid flow. Vapor flow was majorly constituted by viscous flow (about 90%), whereas the primary driver for liquid flow was found to be Darcy friction. The model can help avoid excessive heating times to ensure com-plete thermal desorption of the adsorbent.