根据超临界水氧化处理废水反应效率的影响机理,增加温度能明显促进反应速率,降低压力可以减小反应器壁厚、降低设备投资和运行成本、减缓腐蚀。通过实验研究了在水的过热近临界区域对废水氧化处理的可行性。选择焦化废水、青霉素废水、造纸厂废水、丙烯腈废水、TNT 废水5 种较难降解的典型有机废水进行净化处理实验。实验温度为420~530℃,压力为21~26MPa。实验结果表明:在恒压下随着温度增加,5 种典型废水的化学需氧量(CODcr)净化率都迅速增加;在恒温下随着压力增加,5 种典型废水的CODcr净化率只稍有上升;随着温度增加,不同压力下系统反应出水CODcr 的差值和净化率的差值都在逐渐减小。在温度520~530℃,压力21 MPa 时5 种典型废水净化后的CODcr 值均小于200 mg/L。通过对过热近临界水氧化技术的技术经济性分析,从工程实际考虑,对工业有机废水处理更适宜采用过热近临界水氧化技术,而不是超临界水氧化技术。
In this paper, the feasibility of waste water oxidation treatment in superheated near-critical region of water is studied through experiments. Five kinds of typical industrial organic wastewater which are difficult to biodegrade are chosen for purification experiments. They are coking wastewater, penicillin wastewater, papermaking wastewater, acrylonitrile wastewater and TNT wastewater, respectively. The temperature of the experiment is 420-530℃ and the pressure 21-26 MPa. The results show that at a constant pressure the CODcr removal ratios of the five kinds of wastewater are increasing rapidly with temperature increase,whereas at a constant temperature the CODcr removal ratios are only slightly increased as the pressure increases. Additionally, the differences of CODcr removal rates and purification rate of water in the outlet of the system at different pressures are gradually reduced as the temperature increases. Under conditions of temperature at 520-530℃ and pressure at 21 MPa, the purified CODcr values of the five typical kinds of wastewater are less than 200 mg/L, even less than 100 mg/L. Through a technological and economic analysis, it is pointed out that considering the engineering practice, the superheated and near-critical water oxidation is more suitable for industrial organic wastewater treatment, instead of the supercritical water oxidation technology.
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