Study on the treatment of sewage (waste) water by large-scale ozone equipment

Study on the treatment of sewage (waste) water by large-scale ozone equipment

      With the rapid development of China's national economy, environmental science and technology workers are urgently required to shoulder the heavy responsibility of establishing sustainable development and building an environmentally-friendly society to completely change the increasingly serious environmental pollution and ecological deterioration. Large-scale ozone equipment technology has attracted much attention for its unique role in various environmental protection fields. Especially in the treatment of refractory, difficult to biochemical, toxic industrial sewage (waste) water.
Our company's scientific and technical personnel and many domestic environmental protection experts have worked together to make useful attempts and engineering explorations in the fields of petroleum, chemical, pharmaceutical, coking, printing and dyeing, and papermaking. The main large-scale ozone equipment process is now introduced:
First, the equipment process:

     
Second, the process points:
The large flow gas source usually adopts the screw machine, and its performance and beauty are better than the piston machine (the piston machine is often used for small flow below 3 m3/min). The gas supply volume and air pressure are both displayed and adjusted in the display, which can automatically detect and record the fault. The noise is ≤72dB and can be drained automatically. There are several screw machines produced or assembled in domestic and joint venture factories, especially the Atlas Models, but they are expensive.
The outlet temperature of the freeze dryer is ≤5 °C , and the microcomputer control device controls all the operating parameters. The refrigerating dryer is a device that uses the principle of freezing and dehumidification to dry the compressed air. Due to the use of high-quality imported components, the performance is reliable, the operation is stable, the noise is low, the energy consumption is small, and the application is extensive. The technical feature is that the hot and humid compressed air containing water enters the pre-cooler, exchanges heat with the cooled dry air to be discharged, reduces the saturation temperature of the air, and removes part of the water. The evaporator exchanges heat with the refrigeration system in the evaporator to reduce the burden on the evaporator and save energy. The compressed air discharged from the evaporator is in a low temperature state, and moisture, oil, impurities, etc. are condensed, separated by gas and water. After the separator is separated, it is discharged from the outside by an automatic drainer. The structure of the dryer is controlled by microcomputer (PLC), which controls all the operating parameters. The operation is simple, the preset interface can be remotely controlled with the calculation meter, the high pressure of the refrigerant and the low pressure of the refrigerant exceed the limit value, and the refrigerant compressor passes. When flowing, the compressor can be automatically turned off, and the double automatic balance function of the thermal expansion valve and the hot gas bypass valve ensures the stability of the dew point. All the heat exchangers, gas-liquid separators and air supply pipe surfaces are effectively insulated and insulated to ensure Cooling effect, the dryer usually has air-cooling and water-cooling. The inlet temperature is ≤45 °C , the outlet temperature is 2~5 °C , and the finished product dew point is usually around -23 °C .
The gas storage balance tank is a pressure vessel, which is used to balance the pressure fluctuation of the compressor. There should be a pressure vessel manufacturing license issued by the state, and the products subject to supervision and inspection by the labor department are qualified products. Users are often used when creating device files.
The main line filter is used to protect the entire system after the air compressor rear cooler and before other filters. It can filter out a large amount of liquid and solid-liquid particles ≤ 3μm, filter residual oil ≤ 5ppm, improve the function of downstream dryer, extend filter life and prevent component failure.
The pre-filter can filter solid-liquid particles ≤0.1μm and filter residual oil ≤0.01ppm.
The post filter can filter solid-liquid particles ≤0.01μm and filter residual oil ≤0.001ppm.
PSA dry oxygen generator (oxygen enrichment) is one of the key equipments of large-scale ozone equipment system. The dew point level and oxygen concentration value directly affect the ozone concentration and output until the reliability and stability of the whole system should be highly valued! The so-called dew point is to keep the pressure constant, and to cool the air containing water vapor. When it drops to a certain temperature, the water vapor in the air reaches a saturated state and starts to change from a gaseous state to a liquid state, which is called condensation. The temperature at this time is called dew point. . Its unit is °C , dew point is one of the expression methods of atmospheric humidity, and humidity refers to the amount of water vapor in the atmosphere. The measurement range is from 10-6 to the saturated vapor pressure. The method is absolute humidity (the amount of water vapor contained in a unit volume of air under a certain humidity and pressure, the unit is g/m3), relative humidity (the actual amount of water vapor contained in the air and the zui contained in the same temperature) The ratio of the large amount of water vapor, expressed as a percentage, in units of %RH) and dew point. Among the components of the Earth's atmosphere, nitrogen accounts for 78%, oxygen accounts for 21%, inert gas, other gases and water vapor account for only 1%. It can be seen that water vapor containing less than 1% of the atmospheric content is an ozone generator ( In particular, the "corona" of the corona type affects the yield, efficiency, and life of the ozone generator. The high dew point is high, the humidity is high, the ozone concentration is low, the yield is small, and the equipment failure rate is high. The air type ozone generator It also ionizes the combination of nitrogen oxides and water vapor into nitric acid corrosion equipment and severely affects ozone production until failure. The application of pure oxygen source in large-scale ozone equipment in China is actually to further ensure the low dew point characteristics of the gas source, avoid the interference of air water vapor, and ensure the normal operation of the equipment.
The PSA pressure swing adsorption dryer is a device that dries compressed air according to the principle of pressure swing adsorption. Under a certain pressure, the compressed air flows through the adsorbent layer (dry bed) from bottom to top. Under normal temperature and pressure, the adsorbent absorbs moisture in the air to make the compressed air dry. A small amount of dry air is contacted with the adsorbent to remove the moisture adsorbed by the desiccant and discharged out of the machine to regenerate the adsorbent. This is the pressure swing adsorption process of the dryer. The air dryer is divided into a non-thermal regenerative type and a micro-heat regenerative type, and the adsorbent is commonly used as an activated alumina and a molecular sieve. PSA technology features two adsorption towers alternately and continuously working, using PLC control, easy to operate, safe and reliable, scientific structure design, to ensure that desiccant and air are fully adsorbed, dew point stable, high reliability valve control device, safe to use Up to 1 million times, special gas diffusion device, automatic regeneration to ensure the service life of desiccant. After the PSA dryer, the finished product dew point is ≤ -40 °C (at normal pressure).
PSA pressure swing adsorption oxygen generator is a kind of equipment that performs air separation on oxygen, nitrogen and water molecules in compressed air according to the principle of pressure swing adsorption. The purified and dried compressed air enters the adsorption tower, and the adsorption capacity of the nitrogen gas is increased when the adsorbent layer (molecular sieve) is pressurized under the normal temperature and normal state by the molecular sieve, and the adsorption capacity of the nitrogen gas is reduced when the pressure is reduced. Forming a cyclic process of pressure adsorption and decompression desorption to achieve nitrogen and oxygen separation, and to obtain high-purity oxygen (oxygen concentration is usually 93±3%, oxygen pressure ≥0.1MPa), while utilizing the hydrophilicity and adsorption of the molecular sieve, The high-purity oxygen dew point can be separated from ≤-45 °C to achieve a large amount of ozone synthesis.
The PSA pressure swing adsorption oxygen enrichment machine is between the PSA pressure swing adsorption dryer and the PSA pressure swing adsorption oxygen generator. When considering the economic operation mode, the oxygen-enriched ozone production mode is often used, and the corresponding effect can also be achieved. Its working principle is the same as that of PSA pressure swing adsorption oxygen generator.
The precision filter usually has a special activated carbon permeation treatment, which can completely absorb the gas odor such as hydrocarbons, so as to achieve the quality of the air (oxygen) without odor and taste, such as food, medicine, breathing and other air and ozone generators. It can filter out residual oil ≤ 0.001ppm, and also filter out PSA pressure swing adsorption oxygen machine molecular sieve dust to reduce the maintenance of ozone discharge chamber.
Flow pressure measurement usually has a common high level. Advanced use of vortex flowmeter, pressure transmitter, temperature transmitter, dew point transmitter, ozone analyzer, ozone leakage alarm and other intelligent instruments, with pneumatic, electric control valve, combined with PLC to form a complete automated intelligent measurement and control system . The investment cost of this system is large, often depending on the needs of users.
The dew point analysis and control instrument is a new type of instrument for measuring the degree of dryness of gas on-line. The Finnish YAISALA imported sensor is often used in China, and the second intelligent digital display instrument is used. The Chinese menu is used to display the parameters in the measurement process. It is convenient to use. It can continuously measure the gas dew point value online, cooperate with the signal output interface and alarm function, and can be connected with the computer. Use, dew point range: -80 ~ 20 °C , measuring ambient pressure 0 ~ 2MPa, output signal for single channel 4 ~ 20mA analog signal and mouth output RS232, with automatic correction function, anti-condensation, free from oil and gas and most chemical gases Impact, easy to install. Low dew point value and long-term stable operation below -45 °C is the premise of normal operation of ozone equipment. The better the dew point problem is solved, the better the operation quality of ozone equipment, the less after-sales service, and the more satisfied users are, one stone and three birds, Don't be happy!
Large-scale ozone main equipment includes: power supply, measurement and control, and discharge room. Among them, power supply technology combined with measurement and control technology is the key technology. The discharge chamber is a strict mechanical structure with strict requirements. Only the matching load of the power supply and the discharge chamber is good, the system can operate stably, the failure rate is low, and the ozone production concentration is high. Attention should be paid to the overvoltage, overcurrent and overload protection of high-power power supplies, the continuous operating temperature and insulation strength of high-voltage transformers, and the protection of ozone reaction tower (pool) moisture return high-voltage discharge chamber. Only the system is carefully designed, constructed and protected. Can have a good running quality.
Third, the development direction: due to large investment in large-scale ozone equipment, high cost, difficult, is a high-tech ozone equipment, but also a major technical equipment. Its characteristics are advanced technology, difficult to develop, strong set, and high correlation. China is a developing country, the industrialization process has not yet been completed, and many departments of the national economy need a large amount of large-scale ozone equipment. In the long run, these equipment must be based on domestic. Therefore, the localization of major technical equipment is an important guarantee for the safe operation of the country and the realization of sustainable development and national modernization. Throughout the major technical equipment, all infiltration of information, intelligence, automation. Large-scale ozone equipment is no exception. Combining informationization, intelligence, automation and networking, it has improved the technical level and product grade of complete sets of equipment, improved the competitiveness of foreign manufacturers and participated in international competition. It is the inevitable development of large-scale ozone equipment. direction. At the same time, scientific and technological progress and social needs bring new technologies and materials for ozone complete sets of equipment, and also promote the vigorous development of the ozone industry, and the future is unlimited!