同©大学 Tongji University Advanced Oxidation Yulin Tang
Tongji University Advanced Oxidation Yulin Tang
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Tongji University
同©大学 Tongji University Ozone properties Unstable:readily decompose,only produced onsite Blue gas with distinct odor Toxic and explosive(20%weight in air Strong oxidizing power Produce no residuals of secondary pollution
Tongji University Ozone properties Unstable: readily decompose, only produced onsite Blue gas with distinct odor Toxic and explosive (20% weight in air ) Strong oxidizing power Produce no residuals of secondary pollution
同海大学 Tongji University I.Ozone Chemistry Some of the chemical properties displayed by ozone may be described by its decomposition reaction,which are proceed as following: O3+H20→HO3+OH (11-35) HO3+OH→2HO2 (11-36) 03+H02→H0+20, (11-37) H0+H02→H2O+O2 (11-38)
Tongji University Ⅰ. Ozone Chemistry Some of the chemical properties displayed by ozone may be described by its decomposition reaction, which are proceed as following: + O + H O HO + OH 3 2 3 + HO + OH 2HO 3 2 O + HO HO+ 2O 3 2 2 HO+ HO H O+ O 2 2 2 (11-35) (11-36) (11-37) (11-38)
同海大学 Tongji University The free radicals formed,H0,and HO,have great oxidizing powers,and are probab/y the active form in the disinfection process. These free radicals also possess the oxidizing power to react with other impurities in aqueous solution. (refractory organics,such as pesticides,algae)
Tongji University The free radicals formed, HO2 and HO, have great oxidizing powers, and are probably the active form in the disinfection process. These free radicals also possess the oxidizing power to react with other impurities in aqueous solution. (refractory organics, such as pesticides, algae)
同燎大学 Tongji University II.Ozone Disinfection Systems Components A complete ozone disinfection system is comprised of the following components (Fig.11-7) (1) Power supply (electricity), (2) Facilities for the preparation of the feed gas (air, oxygen), (3) The ozone generation facilities (generator), (4) Facilities for contacting the ozone with the liquid to be disinfected (contact tank), (5) Facilities for the destruction of the off-gas (decomposer)
Tongji University Ⅱ. Ozone Disinfection Systems Components A complete ozone disinfection system is comprised of the following components (Fig.11-7) (1) Power supply (electricity), (2) Facilities for the preparation of the feed gas (air, oxygen), (3) The ozone generation facilities (generator), (4) Facilities for contacting the ozone with the liquid to be disinfected (contact tank), (5) Facilities for the destruction of the off-gas (decomposer)
G 同©大号 Tongji University Figure 11-7 Schematic flow diagram for complete ozone disinfection evetom Power Exhaust gas supply destruction Dry Air Gas gas preparation Treated Alternate oxygen Ozone Contact water source generator basin Oxygen High-purity oxygen storage Water to be treated
Tongji University Figure 11-7 Schematic flow diagram for complete ozone disinfection system
同©大学 Tongji University ●Energy requirement The major requirement for power is the conversion of oxygen into ozone.(02:6.6-13.2)or (Air:13.2- 19.8)KWh/Kg03 Addition power is required for preparation of the feed gas,contacting the ozone,destroying the residual ozone (off-gas),and for the controls,instrumentation 器)，and monitoring facilities
Tongji University Energy requirement The major requirement for power is the conversion of oxygen into ozone. (O2:6.6-13.2) or (Air:13.2- 19.8)KWh/KgO3 Addition power is required for preparation of the feed gas, contacting the ozone, destroying the residual ozone (off-gas), and for the controls, instrumentation (仪 器), and monitoring facilities
同傍大学 Tongji University Preparation of Feed Gas Ozone can be generated using air,oxygen-enriched air,or high -purity oxygen. If air is used for ozone generation,it must be conditioned by removing the moisture and particulate matter before being introduced into the ozone generator. the following steps are involved in conditioning the air: (1) gas compression, (2) air cooling and drying, (3) air filtration
Tongji University Preparation of Feed Gas Ozone can be generated using air, oxygen-enriched air, or high –purity oxygen. If air is used for ozone generation, it must be conditioned by removing the moisture and particulate matter before being introduced into the ozone generator. the following steps are involved in conditioning the air: (1) gas compression, (2) air cooling and drying, (3) air filtration
同傍大学 Tongji University ●Ozone Generation Because ozone is chemically unstable,it decomposes to oxygen very rapidly after generation.It must be generated onsite. The most efficient method of producing ozone today is by electrical discharge.Ozone is generated from either air or high-purity oxygen when a high voltage is applied across the gap of narrowly spaced electrodes.(Fig.11-8). The high-energy corona created by this arrangement dissociates one oxygen molecules,which re-forms with two other oxygen molecules to create two ozone molecules
Tongji University Ozone Generation Because ozone is chemically unstable, it decomposes to oxygen very rapidly after generation. It must be generated onsite. The most efficient method of producing ozone today is by electrical discharge. Ozone is generated from either air or high-purity oxygen when a high voltage is applied across the gap of narrowly spaced electrodes. (Fig.11-8). The high-energy corona created by this arrangement dissociates one oxygen molecules, which re-forms with two other oxygen molecules to create two ozone molecules. Ozone rate: 1-3% for air; 3-10% for pure oxygen by weight