超临界CO_(2)干燥过程能耗分析及节能优化

Energy consumption analysis and energy saving optimization of supercritical CO_(2) drying process

为了优化超临界CO_(2)干燥过程,降低其能耗,利用Aspen Plus软件对超临界CO_(2)干燥制备SiO_(2)气凝胶工艺过程进行模拟和优化,同时进行能效分析和[火用]效分析,此外,利用响应面分析法对新系统的分离过程进行参数优化。结果表明:干燥过程中的能耗损失主要集中在加热和冷却单元,其中CO_(2)循环冷却耗能占比最大,占系统总损失的59.39%,通过改变加压方式并且利用冷却水循环建立热能回收利用系统,干燥系统的能效和[火用]效被提升到52.93%、13.06%,相比于当前系统提高了2.78%、7.19%,系统耗能由5756.65 kJ/h降低至2647.23 kJ/h。预测新系统的最佳分离条件为分离温度为48.7℃、分离压力为4 MPa,该条件下CO_(2)利用率为83.26%,乙醇残留率为1.19%。

In order to optimize the supercritical CO_(2) drying process and reduce its energy consumption,the process of preparing SiO_(2) aerogel by supercritical CO_(2) drying was simulated and optimized by Aspen Plus software.Energy efficiency analysis and exergy efficiency analysis were also carried out.Besides,response surface analysis was used to optimize the separation parameters of the new system.The results show that the energy consumption loss in the drying process is mainly concentrated in the heating and cooling units,and CO_(2) circulation cooling consumes the most energy,accounting for 59.39%of the total loss.By changing the compression mode and using the cooling water to recycle heat energy,the energy efficiency and the exergy efficiency of the drying system increase to 52.93%and 13.06%,which are 2.78%and 7.19%higher than that of the current system.The system energy consumption reduce from 5756.65 kJ/h to 2647.23 kJ/h.The optimal separation conditions of the new system are predicted as follows:the separation temperature and pressure of the new system are 48.7℃and 4 MPa,CO_(2) utilization rate is 83.26%and the ethanol residue rate is 1.19%.