Researches On Ozone Generation With Discharge Plasma And Discussion On Some Problems In Practice

In order to develop ozone technology in China, some problems on ozone generation with discharge plasma are investigated theoretically and practically. Moreover, studies on the contact reactor in the process of ozone application in water treatment are conducted. The main contents and conclusions in the dissertation are as follows:1. Based on mechanism of ozone synthesis in discharge plasma, a method of Dielectric Barrier Discharge (DBD) triggered by the bipolar narrow pulse is proposed. The test on ozone generation is conducted by the method using bipolar narrow pulse power with rotating spark-gap switch. The results demonstrate that the method has the merits of pulse streamer discharge and DBD. Comparing with traditional DBD, the energy efficiency to produce ozone is increased 30%~40% and at the lower concentration (3~4g/m3), the energy efficiency can reach 370~380g/kWh.2. It is studied on the testing apparatus that the characteristics of ozone generation varied with the concerned factors, such as fed gas, running voltage, frequency and others parameters. Based on testing works, the concentration, yield and energy efficiency of ozone generation are discussed. According to processes of the ozone synthesis and decompose, the empirical formula is given, which can describe concentration as a function of the discharge power density.3. The dynamic-load-characteristics of the DBD discharge reactor are studied, which include dynamic capacity, discharge power, V-I characteristics, and power factor. On the basis of those works, the suggestion is to solve the problems on designing the power and the matching between power and the reactor. High leakage reactance transformer is used to improve the stability and reliability in a ozonizer. And the control of the discharge power is realized with the method of PFM and PDM.4. The technology scheme is chosen middle frequency DBD to develop large-scale ozonizer. And based on above mention, the test prototype is realized successfully, when fed gas is oxygen, the test prototype can output 300g/h ozone gas, and the ozone concentration is about 50g/m3, the energy efficiency is 150g/kWh.5. The process of ozone transfer to water is discussed. A novel scheme is put forward for mass transfer intensification with electric field in ozonia bubbled column. The results showed that the concentration of ozone in water can be increased and mass transfer can be enhanced by the well perspective scheme.6. Furthermore, feasibility test for advanced oxidation is introduced, which is using ozone in treatment of the wastewater from synthetic ammonia plant.