To Treat Substances in Air, Industrial Water and Wastewater for Sanitization
Ozone is emerging as the most efficient and ecologically sound oxidant to sanitize and treat both organic and inorganic substances in air, water and wastewater. A wide variety of ozone equipment configurations and sizes is available from Nancrede Engineering for municipal, industrial process and laboratory applications – backed by more than 30 years of experience. Smaller units are self-contained, while larger units are skid mounted or assembled on site.
In the latter half of the 20th century, numerous applications for ozone became evident. These discoveries occurred as the result of four contributing factors: research in ozone technology, the phenomenal increase in environmental pollution, recognition of limitations and biological hazards of historically used oxidants, and the development of commercial ozonators.
Attendant to the rising national concern for air and water quality, the demand for cleanup chemicals has significantly increased. Because ozone is an extremely efficacious oxidant, because it does not persist as a residual, and because the by-products of ozone reactions are ecologically benign, ozone is rapidly attaining preeminence as the chemical for air and water treatment. It is a very good option for water sanitization in industrial, municipal, commercial and laboratory water systems.
Unlike most chemicals, there is no natural resource for ozone, nor is it practicably containerized. The source for ozone is an ozone generator. An ozone generator with accessory equipment and controls is called an ozonator.
Ozonators Type, Capacity, Features
|Capacity||0.13-500 lb/day std.|
|Features||Integrated air compressor, filters, drying towers|
|Capacity||0.01-1000 lb/day std.|
|Features||Maximum output, high purity|
|Type||Ozone test chambers|
|Features||Conforms to ASTM, Mil-Specs, temp-controlled, ozone monitor included|
|Type||Ozone destruct modules|
|Capacity||99% destruct @ 50-100 scfm (85-170 m3/hr)|
|Features||Catalyst and heat destruct process, self-contained|
|Capacity||0-100 mg/SL (milligrams per standard liter)|
|Features||UV light absorption, digital readout, rugged and compact|
|Features||Porous stone or venturi type, high diffusion efficiency|
Ozonators Technical Description
The model designation nomenclature of Nancrede Engineering ozonators provides a key to the features of that model. Nancrede Engineering offers several series of ozonators that are customizable.
The H series are very large, skid-mounted ozonators for process applications; the D series are large ozonators for process applications; SP series ozonators are medium-sized for laboratory, pilot and medium-process applications; and the V series are small ozonators for laboratory and small process applications.
Within each series are models that have an “-AR” or “-O” suffix. Models having -AR operate from atmospheric air as the parent gas and incorporate air processing equipment, while models utilizing an -O operate from cylinder oxygen or cylinder air as the parent gas and do not incorporate air processing equipment.
Although Nancrede Engineering ozonators are available in a wide variety of sizes and configurations, certain significant design features are common to all models:
Ozonators Package, Module, Construction
All models having outputs below 25 lbs. ozone/day using air are complete and integral within an attractive painted steel cabinet with front-mounted instrument panel. Models in the D and H series have the air compressor located exterior to the ozonator package. Ozonators of sizes larger than the above are skid-mounted modules. Tonnage ozonators are on-site installations.
Ozonators Tubular, Water-Cooled Ozone Generators
Water-cooled ozone generators are installed in all industrial, process and laboratory ozonators. The operating temperature of ozone generator dielectrics is critical. Not only does ozone output vary as a function of generator temperature, but as ozone generator temperature increases, the dielectric material (i.e. glass, ceramic) changes thermal characteristics and is subject to rupture. As critical generator dielectric temperatures are relatively low (120° – 130°F), a considerable volume of air is required for air cooling, and unless the air is preconditioned by refrigeration (an expensive and power-consuming option), there is significant dependence upon the ambient environmental temperature. Water is a far more efficient medium for heat transfer than air and this is crucially significant where the ? T is low between the cooling medium and the critical temperature of the medium to be cooled. Water is an economical medium, is normally available at pressure, and, in the instance of ozonators, can be of any quality – even process water of very poor quality. Water passing through an ozonator does not have to have its quality degraded or changed.
The history of ozonator experience has established that reliability and continuous operation with minimum maintenance is best served by water-cooled ozonators, and therefore the vast majority of process ozonators throughout the world are cooled by water. Nancrede Engineering ozonators can be provided with recirculating water systems for operation in areas where water availability is nonexistent or critical.
Nancrede Engineering ozone generators are tubular rather than plate. Tubular design requires far less gasketing and therefore less opportunity for ozone leaks, and tubular ozone generators are more simple to install and replace. They will also operate at higher pressures (up to 30 psig in standard with most Nancrede Engineering ozonators).
Ozonators High-Pressure Air System
If the ozone generators are the tubular type, the ozonator designer has the option to design the ozonator to operate at low or high generator pressures. If the ozone generators are the plate type, the designer is restricted to providing an ozonator that operates and discharges ozone at only low pressure. There are significant advantages to an ozonator system that can operate at high pressures, such as micron and sub-micron filters can be used in the air system, ozone can be delivered against high head pressures and over long distances, and dehumidification is enhanced.
The importance of air filtration cannot be overemphasized in the maintenance and service of ozone generators. Particulates and aerosols in the parent air that passes through ozone generators lead to fouling of the generators and diminution of ozonator output.
Ozonators which operate at high pressures with attendant micron size filters will operate for extended intervals of time (many years) without the requirement for generator cleaning, as long as the presented air is dried to -60°F frost point.
Most Nancrede Engineering ozonators operate at high pressure, that is, the system pressure is 30 psig or above and the ozone generators will deliver ozone at pressures up to 30 psig.
Ozonators Integral Air Processing Equipment
All Nancrede Engineering ozonators, other than those that operate from cylinder oxygen, incorporate integral air processing equipment, and the user does not have to size or design auxiliary air processing equipment. This equipment includes air compressors, air filters, automatically cycling air processing (drying) towers, flowrators, pressure regulators, pressure relief valves, flow valves and limit switches.
Ozone Output Regulation
The output of an ozonator is a function of the voltage applied to the ozone generators. Nancrede Engineering modular ozonators incorporate variable voltage transformers whereby the applied voltage can be continuously adjusted over a wide range, down to 5% of the rated output of the ozonator. The variable voltage transformer adjustment is panel-mounted: a simple rotating knob in the instance of small transformers or a raise/lower switch in the instance of large, motor-driven transformers. Large skid-mounted may utilize multiple tap transformers rather than variable voltage transformers to achieve several fixed output voltages. A panel-mounted voltmeter and ammeter in conjunction with the variable voltage transformer allow the user versatility in ozone output to respond to high or low ozone demand of the system being ozonized.
Ozonators Interlock Features
All Nancrede Engineering ozonators can be provided with interlocks so that remote fans, blowers, pumps, solenoid valves, etc. will be activated upon startup of the ozonator or vice versa. Usually these interlocks are limited to a 5 ampere load.
Ozonators Safety Features
Nancrede Engineering ozonators are designed to be ozone tight so that there is no ozone in the vicinity of the ozonator. A chassis ground terminal is provided for system safety. Access doors through which the high voltage ozone generator transformer secondary terminals can be reached are interlocked to shut off the voltage when the access door is opened. High voltage transformers are either the dry type or use silicone transformer liquid.
Ozonators Supply Voltage
Standard ozonators are designed to operate from voltages which take the following power requirements of the ozonator into consideration, according to the following schedule:
- Ozonators below 6 lbs. ozone/day – 120 volt, 60 cycle AC
- Ozonators between 2 and 25 lbs. ozone/day – 230 volt, 60 cycle AC
- Ozonators above 25 lbs. ozone/day – 460 volt, 60 cycle AC
Ozonators can be equipped to operate at voltages other than cited above; for instance, a 15 lb./day ozonator can be equipped to operate at 460 volts. They can also be operated at 50 cycles, but when that happens, output is reduced 1/6 from advertised output.