School of Energy & Environmental Engineering, Zhongyuan University of Technology, Zhengzhou 450007, China.
School of Energy & Environmental Engineering, Zhongyuan University of Technology, Zhengzhou 450007, China.
Waste Manag. 2019 Aug 1;96:198-205. doi: 10.1016/j.wasman.2019.07.023. Epub 2019 Jul 26.
In this study, gasification of sewage sludge in supercritical water using a batch reactor was investigated. The effects of temperature, retention time, and the oxidation coefficient on gas composition, gas yield, total organic carbon removal efficiency (X), gasification efficiency (GE), carbon gasification efficiency (CE), and phosphorus release rate (X) were investigated. The experimental results indicated that the yields for hydrogen, methane, and carbon dioxide increased with the increase in temperature from 380 °C to 460 °C. A maximum hydrogen molar fraction of 55.72% and a yield of 19.86 mol/kg were obtained at 460 °C and 27 MPa after 6 min. The GE, CE, X, and X also increased with the increase in temperature. An extension of the retention time promoted the gasification of sludge, thereby resulting in an increase in the hydrogen and methane molar fraction, yield, GE, CE, X, and X. Under the conditions of 420 °C and 27 MPa after 6 min, with an increase in the oxidation coefficient from 1.5 to 2.5, the oxidation reaction became dominant in the supercritical water. Hydrogen and methane were converted to carbon dioxide and water with an excess of hydrogen peroxide, which resulted in a lower hydrogen yield. However, the decomposition of organic compounds in the sludge was promoted with the addition of hydrogen peroxide, thereby resulting in an increase in the GE, CE, X, and X. When the oxidation coefficient reached 2.5, a maximum GE of 131.6% and X of 98.74% were obtained.
在本研究中，使用间歇式反应器对污水污泥进行超临界水气化。考察了温度、停留时间和氧化系数对气体组成、气体产率、总有机碳去除效率（X）、气化效率（GE）、碳气化效率（CE）和磷释放率（X）的影响。实验结果表明，随着温度从 380°C 升高至 460°C，氢气、甲烷和二氧化碳的产率均增加。在 460°C 和 27 MPa 下，停留时间为 6 min 时，氢气的摩尔分数达到最大值 55.72%，产率为 19.86 mol/kg。随着温度的升高，GE、CE、X 和 X 也增加。延长停留时间促进了污泥的气化，从而增加了氢气和甲烷的摩尔分数、产率、GE、CE、X 和 X。在 420°C 和 27 MPa 下停留 6 min 后，随着氧化系数从 1.5 增加到 2.5，氧化反应在超临界水中变得占主导地位。由于过氧的存在，氢气和甲烷转化为二氧化碳和水，导致氢气产率降低。然而，添加过氧促进了污泥中有机化合物的分解，从而增加了 GE、CE、X 和 X。当氧化系数达到 2.5 时，获得了最大的 GE 为 131.6%和 X 为 98.74%。
