Wet catalytic oxidation, the standard abbreviation CWO, refers to raising the temperature of wastewater to 180 ℃ - 325 ℃, using the oxygen in the air to increase the solubility with the increase of pressure. Under the action of catalyst, oxygen molecules and organics in wastewater undergo a rapid oxidation reaction, resulting in ring breaking and chain breaking of organics, which are collectively referred to as degradation.
The principle of degradation reaction is free radical chain reaction. The primary products of oxidative degradation are simple organic acids and organic alcohols below C4. Some of the degradation products will be deeply degraded and mineralized into carbon dioxide to form the removal of TOC. The degradation rule is that the higher the reaction temperature is, the greater the proportion of deep degradation to carbon dioxide is. The catalytic strength can reduce the energy level of degradation reaction and increase the speed of degradation reaction. The top of wet catalytic oxidation process is supercritical oxidation.
Medium temperature and medium pressure wet catalytic oxidation is a kind of wet catalytic oxidation. It refers to the process of wet catalytic air oxidation in the temperature range of 180 ℃ - 258 ℃ and the corresponding pressure range of 2.5mpa-5.0mpa.
A large number of engineering practices have proved that: wet catalytic oxidation in the middle temperature and middle pressure section can obtain good degradation effect and appropriate COD removal effect, supplemented by other low-cost sewage degradation means, can obtain the best economy (investment, operation, life).
(1) The maximum inlet temperature of medium temperature and medium pressure system shall not exceed 258 ℃, and the maximum operating pressure shall not exceed 5.0mpa. The pressure control is very stable, the service life of the equipment is long, and the failure rate is low.
(2) Under the operation condition of medium temperature and medium pressure system, the system has relatively small supplementary heat and low pressure, and the operation power consumption of air compressor is low. The main operating cost of wet oxygen process comes from air compressor and hot oil furnace. Therefore, the operating cost of medium temperature and medium pressure system is generally reduced by about 50% compared with that of high temperature and high pressure wet oxygen system.
(3) The system adopts our unique long-term fixed bed catalysis, namely heterogeneous catalysis system. Its advantage is that no heavy metal ions (commonly used homogeneous catalytic materials) are added into the tower materials to avoid secondary pollution caused by heavy metals and reduce the cost of operation catalysis.