(377c) Process Simulation of Removal Methyl Sulfide from Nitrogen Using Pressure Swing Adsorption Based on Aspen Adsorption

With the increasingly strict global environmental problems and the booming demand of chemical industry for raw material purification, desulfurization technology has gradually attracted researchers’ attention. Selective adsorption desulfurization was widely used due to its low energy consumption and ultra-deep desulfurization. Based on Aspen Adsorption process simulation software, a fixed bed adsorption model of methyl sulfide-nitrogen two-component system was established for pressure swing adsorption (PSA) process with Cu²⁺ modified NaY zeolite as adsorbent. The adsorption isotherms were obtained by Monte Carlo simulation. The given operating pressure and temperature were 1 bar and 301 K, respectively. The concentration of methyl sulfide was 2000 ppmv and the average diameter of adsorbent particles was ca. 1.0 mm. The dynamic data of gas phase composition, outlet concentration and pressure in the single tower process were obtained by simulation and the corresponding breakthrough time was 1380 min. Fixed-bed adsorption experiments were carried out under the same conditions. The results show that the simulation is well consistent with the experimental data. It demonstrates that the fixed-bed adsorption model established in this study can satisfactorily describe the purification process of methyl sulfide-nitrogen adsorption.

A two-column PSA model was established, on the basis of single column analysis. The concentration distribution of CH₃SCH₃ in the two-column process and the change of adsorbent adsorption amount with time were studied. The variation of gas phase concentration and the movement of mass transfer zone along the axis of the adsorption bed in the step of boosting, adsorption, depressurization and flushing were revealed. The effects of mass transfer coefficient, temperature and pressure on the purification efficiency of PSA were systematically analyzed. A more reasonable and efficient time sequence table of the two-tower PSA process was designed via optimizing the process conditions based on the specific physical parameters, which was expected to provide reliable prediction of the adsorption breakthrough process for the selection and design of separation schemes for practical adsorption and desulfurization projects.

Key words: Pressure swing adsorption; Process simulation; Aspen Adsorption; Desulfurization; Gas purification

* Corresponding author. E-mail: yonghou.xiao@dlut.edu.cn, hgaohong@dlut.edu.cn.