气封壁高浓度有机污染物超临界水氧化处理系统

利用干燥空气替换亚临界水作为蒸发壁流体,对传统蒸发壁超临界水氧化反应器进行了改进,即将干燥空气用作污染物超临界水氧化反应氧化剂的同时,又作为该超临界水氧化反应体系的密封介质,避免其与反应器内壁的直接接触,以改善超临界水氧化反应器的耐腐蚀性能。通过对采用城市活性污泥和异丙醇配制的高浓度难降解污染物悬浮液进行超临界水氧化处理后,发现反应器内衬陶瓷管在实验前后无论是外观形貌,还是结构组成均未发生明显变化;处理后液体COD降至80 mg/L以下,去除率达到99.6%以上,固体残渣量约为污染物总量的1%,且体系运行过程中压力和温度控制准确,可操作性强。进一步验证了将干燥空气作为超临界水氧化体系的密封介质具有可行性,同时表明,该气封壁超临界水氧化反应系统可用于高浓度难降解有机污染物的环境处理。

Gas seal supercritical water oxidation system for treatment of concentrated organic wastes

Improvement for conventional transpiring wall supercritical water oxidation reactors was explored by using dry air instead of water as the transpiring fluid. In the improved supercritical water oxidation reactor, dry air was not only served as the oxidant for wastes, but also the sealing medium to avoid direct contacting of corrosive reaction mixture with the inner wall of reactor, which intended to increase the corrosion resistance of the reactor. After the concentrated organic wastes composed of municipal sewage sludge and isopropyl alcohol were decomposed in the improved reactor, no obvious visual changes were observed for the alumina-tube which was used as transpiring wall, and its chemical composition remained same. COD of the wastewater could reduce to 80 mg/L by the treatment of this improved reactor, with a removal rate of more than 99.6%; and the quantity of snuff colored solid debris obtained was about 1% of the original wastes quantity. Pressure and temperature of the improved reactor were conveniently and precisely controlled during all experiments. All of the above validated the feasibility of using dry air as the sealing medium for transpiring wall supercritical water oxidation reactor, and verified the suitability of gas seal supercritical water oxidation system for the treatment of concentrated organic wastes.