Institute of Urban Agriculture, Chinese Academy of Agricultural Sciences, Chengdu, China; Thermochemical Conversion of Biomass Research Group, Ghent University, Coupure Links 653, 9000, Ghent, Belgium.
Thermochemical Conversion of Biomass Research Group, Ghent University, Coupure Links 653, 9000, Ghent, Belgium.
Chemosphere. 2020 Jul;250:126213. doi: 10.1016/j.chemosphere.2020.126213. Epub 2020 Feb 18.
This work presents a continuous set-up for SCWO, which was operated at mild conditions (380 °C, 25 MPa, oxidant equivalence ratio of 2.0 and residence time of 26 s) to oxidize cellulose, lignin, and acetic acid as model compounds. The aim was to oxidize different organics consecutively to near completion in the same mild reaction conditions and set-up. These conditions can overcome some drawbacks associated to SCWO. To combine near complete oxidation with the applied mild process conditions, aqueous effluent from SCWO, containing intermediates from incomplete oxidation, was recycled for consecutive oxidation. Meanwhile, fresh feedstock was continuously fed to retain the process capacity. Upon recycling the aqueous effluent three to four times, depending on the feedstock, the oxidation efficiency increased from 63.9%, 45.3% and 28.3% in a single pass for cellulose, lignin, and acetic acid, respectively, to near 100%. The principle of effluent recirculation should allow a compact set-up to perform almost complete oxidation of different organics at mild conditions. The principles and effects of effluent recirculation are outlined, as well as practical consequences and perspectives of this novel principle to SCWO.
本工作提出了一种连续式超临界水氧化（SCWO）装置，在温和条件（380°C，25 MPa，氧化剂当量比为 2.0，停留时间为 26 s）下运行，以纤维素、木质素和乙酸作为模型化合物进行氧化。目的是在相同的温和反应条件和装置中连续氧化不同的有机物，使其接近完全氧化。这些条件可以克服与 SCWO 相关的一些缺点。为了将接近完全的氧化与所采用的温和工艺条件相结合，将含有不完全氧化中间产物的 SCWO 水相流出物进行循环，用于连续氧化。同时，连续进料以保持过程能力。根据进料的不同，将水相流出物循环三到四次后，氧化效率从纤维素、木质素和乙酸单次通过时的 63.9%、45.3%和 28.3%分别提高到接近 100%。废水再循环的原理应该允许采用紧凑的装置在温和条件下对不同有机物进行几乎完全的氧化。概述了废水再循环的原理和效果，以及该新原理对 SCWO 的实际影响和前景。
