Thermal management in vacuum pressure swing adsorption processes using phase change materials
Thermal management in vacuum pressure swing adsorption processes using phase change materials
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DOI：
10.1016/j.cej.2022.141262
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发表时间：
2023-02
影响因子：
15.1
通讯作者：
Yuta Sakanaka;Shotaro Hiraide;Yasuyuki Yamane;M. Miyahara;S. Watanabe
中科院分区：
文献类型：
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作者：
Yuta Sakanaka;Shotaro Hiraide;Yasuyuki Yamane;M. Miyahara;S. Watanabe
真空变压吸附（VPSA）是一种成熟的分离工艺;然而，鉴于目前的能源状况，需要进一步改进工艺操作。为此，在VPSA循环期间使用热能储存系统似乎是有希望的，因为已知由吸附和解吸产生的放热和吸热会降低工作容量。在这项研究中，我们研究了热管理，通过使用商业相变材料（PCM）组成的酚醛树脂和微胶囊化石蜡在VPSA过程中净化等摩尔的CH 4/CO2气体混合物，使用沸石13 X。在这里，VPSA过程模拟使用我们的一维非等温柱模型考虑的PCM的熔化和凝固。根据CO2产品的规格和塔长对PCM混合比的影响进行了评价，其中设计的VPSA工艺使CH 4产品的纯度和回收率满足规定的标准，以实现合理的比较。由于在吸附和排放步骤中分别产生的放热和吸热，在循环稳态下的温度变化（270-351 K）被PCM的潜热抑制到276-344 K，导致低CH 4共吸附和提高CO2产品的纯度。最后，我们提出了一种方法，涉及密集安装的PCM在柱的中心部分，并证明了通过混合的PCM实现的吸附剂性能的改善的优点超过了PCM体积增加的缺点，导致在较短的柱长度比在没有PCM的情况下。这些结果证明了安装PCM的VPSA系统的优越性。
Vacuum pressure swing adsorption (VPSA) is a mature separation process; however, given the current energy situation, further improvements in terms of process operations are required. To this end, the use of a thermal energy storage system during VPSA cycles appears promising, as the exothermic heat and endothermic heat generated by adsorption and desorption are known to reduce the working capacity. In this study, we investigated thermal management by using a commercial phase change material (PCM) composed of phenolic resin and microencapsulated paraffin wax in the VPSA process to purify an equimolar CH4/CO2gas mixture using zeolite 13X. Here, VPSA processes were simulated using our one-dimensional nonisothermal column model considering the melting and solidification of the PCM. The influence of the PCM mixing ratios was evaluated based on the specifications of CO2products and the column length, wherein the VPSA processes were designed, such that the purity and recovery of CH4products met the prescribed criteria to achieve a reasonable comparison. The temperature variation (270–351 K) in the cyclic steady state owing to the exothermic and endothermic heat produced during the adsorption and blowdown steps, respectively, was suppressed to 276–344 K by the latent heat of the PCM, resulting in low CH4co-adsorption and improved purity of the CO2product. Finally, we proposed a method involving the intensive installation of a PCM in the central part of the column and demonstrated that the advantages of improved adsorbent performance realized by mixing the PCM outweighed the disadvantages of increased PCM volume, resulting in a shorter column length than that in the case without the PCM. These results demonstrate the superiority of PCM-installed VPSA systems.