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Corona Discharge and Vacuum Ultraviolet Ozone Systems Copyright. Prozone Pool Products. phone: 256-539-4570 fax: 256-539-4225 www.prozoneint.com Ozone and its Effects www.prozoneint.com phone: 256-539-4570 fax: 256-539-4225 Ozonation WHAT IS OZONE? •Ozone is a form of energetic oxygen that has three atoms of oxygen rather than the normal two. Oxygen = 02 Ozone = 03 •Ozone is the most powerful disinfectant and oxidant which is readily available •Does not produce harmful by-products •Generated on-site www.prozoneint.com phone: 256-539-4570 fax: 256-539-4225 Ozonation EFFECTS OF OZONATION •Ozone performs two major functions in water that are normally done by chlorine Oxidation Disinfection Oxidation + Disinfection = Water Treatment •Oxidation – Oxidation is a process by which contaminants (bather load) are removed from water •Disinfection – Disinfection is the destruction of bacteria and viruses www.prozoneint.com phone: 256-539-4570 fax: 256-539-4225 Ozonation Ozone and Oxidation •In a typical pool, 70 to 90 percent of chlorine is used up in oxidation of bather loading. This process creates byproducts (combined chlorines) which can cause the following problems: Chlorine Odor Eye Irritation Skin Irritation Hair Damage or Discoloration Cloudy Water Excessive Chlorine Consumption •Ozone oxidizes the bather loading reducing chlorine consumption •Ozone oxidizes combined chlorines, creating free chlorine and eliminating the problems listed above www.prozoneint.com phone: 256-539-4570 fax: 256-539-4225 Ozone and Oxidation Ozone Oxidation Disinfection Reacts with Bather Loading and Frees Chlorine Precipitation Filterable Compounds •Reduced Chlorine Use •Clarified Water •Reduced Combined Chlorines •Chlorine Effectiveness Increases •No chlorine odor or Irritation •Removes Metals Kills Bacteria, Viruses Precipitation Filterable Compounds •Improved Sanitation Characteristics of Ozone Chlorine Oxidation Strength Ozone High Highest Disinfection Strength High High Kill Time Fast Fast Stability Varies Generate On-Site Organism Resistance Yes No Major Byproducts Chloramines, No Combined Chlorines Staining Potential No Solubility No High High Stand Alone Yes No pH Dependent Yes No Chlorine Shock Equivalent Yes Yes Algicidal Properties High Medium Generating Ozone with Corona Discharge www.prozoneint.com phone: 256-539-4570 fax: 256-539-4225 Corona Discharge Corona: High voltage, low current electrical discharge across a discharge gap filled with gas (normally air or oxygen). The gas becomes partially ionized, resulting in a bluish glow. www.prozoneint.com phone: 256-539-4570 fax: 256-539-4225 Corona Discharge Translation: Air or oxygen is exposed to a high voltage field which converts a portion (typically 1 to 5 percent) of the air or oxygen to ozone. Oxygen (O2) Electrons Oxygen (O2) Ionized Oxygen (O- +O-) Ozone (O3) www.prozoneint.com phone: 256-539-4570 fax: 256-539-4225 Corona Discharge In addition to ionizing oxygen to create ozone, the corona process also breaks nitrogen bonds (in systems that are air fed or do not use pure oxygen) creating nitrogen oxides. Electrons Oxygen (O2) Ionized Nitrogen (N- +N-) Nitrogen Oxides (NOx) Electrons Oxygen (O2) Ionized Oxygen (O- +O-) www.prozoneint.com phone: 256-539-4570 fax: 256-539-4225 Corona Discharge Nitrogen Oxide Formation and Humidity: Air fed into corona devices should be extremely dry (dew point of -78 deg F, -61 deg C). In systems that run on air only, nitrogen oxide production increases with increasing dew point (moisture content). Nitrogen oxides convert to nitric acid in the presence of moisture. Nitric acid is extremely corrosive. Decreasing Ozone Production Formation of Nitrogen Compounds Increasing 14 deg F Increasing Moisture Content www.prozoneint.com phone: 256-539-4570 fax: 256-539-4225 Corona Discharge Effects of Heat: Heat is detrimental to ozone production as it inhibits formation of ozone and causes it to degrade faster. Increased temperature also contributes to the problem of nitrogen oxide formation. Representative Sample of the Effects of Heat on Ozone Production www.prozoneint.com phone: 256-539-4570 fax: 256-539-4225 Ozone Generation with Corona Discharge Corona discharge devices can be divided into two categories: Type I Generators •Use equipment to pretreat the feed air in order to remove nitrogen (10 percent or less) and moisture (Relative Humidity of -78 deg F or better) •Water or air is used to cool the ozone cell in order to keep it below 100 deg F •Generate high concentrations of ozone and are generally found only in commercial applications due to cost Type II Generators •Stripped down corona discharge devices •No or limited provisions in place to control the environmental factors which affect corona discharge ozone production •Typically have erratic output, concentrations not comparable with commercial grade units www.prozoneint.com phone: 256-539-4570 fax: 256-539-4225 Corona Discharge Summary •Humidity and heat are detrimental to ozone production and require removal to maximize ozone generator performance and limit the production of undesirable byproducts •Clean air or oxygen free of contaminants and oil is required •Generally, these issues are can only be controlled adequately on on commercial grade equipment •Production of nitric acid by small units without air preparation Can cause damage and large pH variations in spas www.prozoneint.com phone: 256-539-4570 fax: 256-539-4225 Corona Discharge Generator Types www.prozoneint.com phone: 256-539-4570 fax: 256-539-4225 Corona Discharge Cell Designs There are a variety of designs available for generating ozone with corona discharge. The most common in the pool and psa industry are: •Surface Discharge (Only found on small spa type systems) •Flat Plate Design (Commercial Systems Only) -Single Dielectric -Dual Dielectric (maximizes life and efficiency) •Tubular Design (Used on spa and commercial Systems) www.prozoneint.com phone: 256-539-4570 fax: 256-539-4225 Corona Discharge Cell Designs Surface Discharge •Generate a corona discharge above a ceramic plate •Systems use ambient air and have rely on air flow for cooling •System output declines as it heats up •Use of unfiltered, humid air degrades performance •Used only in small applications •Low Reliability, performance decays over time www.prozoneint.com phone: 256-539-4570 fax: 256-539-4225 Corona Discharge Cell Designs Flat Plate Design •Systems generate ozone when air or oxygen is passed through the gap between enclosed flat plate electrode/dielectric (ceramic) •Systems can utilize single ceramic or dual ceramic plates (use of dual ceramics limits electrode erosion) •Systems are air cooled (water cooling is an option) •Oxygen is required for maximum performance • Used in commercial systems •Multiple cells for larger systems limit potential for catastrophic failure •High Reliability, Easy to Service/Replace www.prozoneint.com phone: 256-539-4570 fax: 256-539-4225 Corona Discharge Cell Designs Tubular Design •Systems generate ozone when air or oxygen is passed through concentric tubes, one of which is coated with a ceramic-interior designs vary •Oxygen and water cooling are required for maximum performance • Used in commercial systems (water cooled) and small systems (air cooled) •Capable of providing high quantities and concentrations of ozone •Maintenance can be difficult •Water cooling adds complexity in commercial systems •Replacements can be costly www.prozoneint.com phone: 256-539-4570 fax: 256-539-4225 Corona Discharge Systems www.prozoneint.com phone: 256-539-4570 fax: 256-539-4225 Corona Discharge System Elements Type I Devices (Commercial Grade) www.prozoneint.com phone: 256-539-4570 fax: 256-539-4225 Corona Discharge System Elements www.prozoneint.com phone: 256-539-4570 fax: 256-539-4225 Corona Discharge System Elements Oxygen Concentrator Ozone Module Boost Pump Contactor System Unit is Approximately 6 feet High www.prozoneint.com phone: 256-539-4570 fax: 256-539-4225 Corona Discharge System Elements Degas Valve Contacting Loop Contact/Degas Tank Corona Unit Venturi Boost Pump Oxygen Concentrator www.prozoneint.com phone: 256-539-4570 fax: 256-539-4225 Corona Discharge System Elements Type I Devices (Commercial Grade) Feed Gas Preparation •Feed Gas preparation normally consists of a: -Compressor -Oxygen Concentrator or Regenerative Drier -Aftercooler for Compressed Air (Larger Systems) -Air Filters and Oil Removal -Safety Interlocks •Smaller Oxygen Concentrators can be purchased with built in compressors www.prozoneint.com phone: 256-539-4570 fax: 256-539-4225 Corona Discharge System Elements Type I Devices (Commercial Grade) Feed Gas Preparation Oxygen Concentrators •The two main types used on pool installations are: -Pressure Swing Adsorption (PSA) -Rotary •Oxygen Concentrators dry the air and can be used for this function up to units which produce approximately 5 lbs/ozone per day •Systems larger than 5 lbs/ozone per day require an Air Dryer prior to the Oxygen Concentrator to ensure adequate performance and system life www.prozoneint.com phone: 256-539-4570 fax: 256-539-4225 Corona Discharge System Elements Type I Devices (Commercial Grade) Feed Gas Preparation-Oxygen Concentrators •Rotary-Advantages -Provide constant flow of oxygen -Compact design •Rotary-Disadvantages -Operate at low pressure -Mechanical parts are prone to failure -Hard to replace/repair components www.prozoneint.com phone: 256-539-4570 fax: 256-539-4225 Corona Discharge System Elements Type I Devices (Commercial Grade) Feed Gas Preparation-Oxygen Concentrators •Pressure Swing Adsorption-Advantages -Operate at higher pressures -More robust system -Easier to Service -Larger systems available •Pressure Swing Adsorption-Disadvantages -Typically more complex -Require surge tanks on larger units to provide steady output www.prozoneint.com phone: 256-539-4570 fax: 256-539-4225 Corona Discharge System Elements Type I Devices (Commercial Grade) Contacting System •There are a variety of ways to introduce ozone into water •The most common ways in the United States use all or some of the following elements: -Venturi Injector -Contacting Loops -Contact Tanks -Degassing Columns or Gas Separators •In the United States, systems are normally installed in a bypass configuration after the filter •System Performance requirements have a large impact on components selected www.prozoneint.com phone: 256-539-4570 fax: 256-539-4225 Corona Discharge System Elements Type I Devices (Commercial Grade) Contacting Systems •Contacting systems are designed to either mix the ozone rapidly and promote oxidation reactions or to hit a specific disinfection value (CT Value) which generates a residual of ozone in the water •Systems Designed for Oxidation -Requires least ozone -System typically includes Venturi, Contact Loop and a Degasser Also applicable for Vacuum Ultraviolet Systems www.prozoneint.com phone: 256-539-4570 fax: 256-539-4225 Corona Discharge System Elements Type I Devices (Commercial Grade) Contacting Systems •Systems Designed for Disinfection -Designed to kill toughest disease causing organisms (including cryptosporidium) -May be required for some installations -Requires highest amount of ozone -Typically results in excess capacity -Usually generates more off-gassing -Contact system requires Venturi, optional Contact Loop, Contact Tank and Degasser Also applicable for Vacuum Ultraviolet Systems www.prozoneint.com phone: 256-539-4570 fax: 256-539-4225 Corona Discharge System Elements Type I Devices (Commercial Grade) Ozone Destruction •The Ozone Destruct portion of the system removes excess ozone and or air •Components include: -Vent Valve -Catalyst to Destroy Excess Ozone -Water Traps •System usually incorporates portions of the contact system to collect excess ozone/air www.prozoneint.com phone: 256-539-4570 fax: 256-539-4225 Vacuum Ultraviolet Ozone Generation www.prozoneint.com phone: 256-539-4570 fax: 256-539-4225 Vacuum Ultraviolet Systems Translation: Air or oxygen is exposed to ultraviolet light at an ozone producing frequency (185 nm). Concentrations up to 1 percent can be produced. No nitrogen byproducts are produced. Oxygen (O2) UV Light Oxygen (O2) Ionized Oxygen (O- +O-) Ozone (O3) www.prozoneint.com phone: 256-539-4570 fax: 256-539-4225 Characteristics of Vacuum Ultraviolet Systems Low voltage operation Little or no operator adjustment required System can be installed, maintained and serviced by minimally trained service staff Operation in any environmental condition Easy installation, modular design Rugged when properly designed Readily configured for multiple injection points www.prozoneint.com phone: 256-539-4570 fax: 256-539-4225 Ozone Generators Vacuum Ultraviolet System Components •Ozone Producing Lamp(s) -Check lamp life -Check output drop over life of system -Check warranty •Ballast Electronic-Provide best performance and lowest energy consumption Magnetic •Housing •Compressor or Air Pump (Used for Specific Installations and Circumstances) •Installation Kit Proprietary and Confidential www.prozoneint.com phone: 256-539-4570 fax: 256-539-4225 Vacuum Ultraviolet System Types Proprietary and Confidential www.prozoneint.com phone: 256-539-4570 fax: 256-539-4225 Equipment Types Venturi Driven •Relies on pressure differential created by the venturi in a bypass installation to inject ozone into water Compressor Driven •Pressurizable lamp cartridges connected to diaphragm type air compressors •Used in bypass or direct injection installations •Large systems will include contact loops, degassing systems, and ozone destruct www.prozoneint.com phone: 256-539-4570 fax: 256-539-4225 Compressor Driven Systems Compressor driven systems are generally specified for: •Commercial or Public Facilities (Pool and Spa) •Heavily used or large residential pools •Installations below water level, with non-adjustable jets, or with a potential for high head pressures at the injection point •Pools with infloor cleaners Venturi Systems are typically used on: •Residential Pools and Spas •Small commercial facilities •The use of a dedicated return in new residential construction is recommended to ensure a venturi system can be used Proprietary and Confidential www.prozoneint.com phone: 256-539-4570 fax: 256-539-4225 Benefits of Compressor Driven Systems •Higher output •Injects ozone in to water under pressure, improving effectiveness of ozone mixing •Allows operation in a wider range of pressures and hydraulic conditions Proprietary and Confidential www.prozoneint.com phone: 256-539-4570 fax: 256-539-4225 Venturi Systems www.prozoneint.com phone: 256-539-4570 fax: 256-539-4225 Compressor Systems www.prozoneint.com phone: 256-539-4570 fax: 256-539-4225 Large Compressor Systems www.prozoneint.com phone: 256-539-4570 fax: 256-539-4225 Vacuum Ultraviolet Ozone Installation www.prozoneint.com phone: 256-539-4570 fax: 256-539-4225 Bypass Basic Installation Venturi Ozone Generator Ozone Generator Extended Contact Distance Saddle or Tee Pool www.prozoneint.com phone: 256-539-4570 fax: 256-539-4225 Installation-Direct Injection Compressor Only Ozone Injection Extended Contact Distance Ozone Generator Saddle Pool or Tee www.prozoneint.com phone: 256-539-4570 fax: 256-539-4225 Ozone Generators Vacuum Ultraviolet • Lower Cost • Rugged • Easy Operation • Lower ozone concentration • High Reliability • Operation in almost any environment Corona Discharge • High Ozone Outputs available • High Ozone Concentrations available • Higher Cost up to 1 lb then lower • More Complex • Excellent performance when properly applied •May be required for large applications Proprietary and Confidential www.prozoneint.com phone: 256-539-4570 fax: 256-539-4225 Safety and Regulatory Issues www.prozoneint.com phone: 256-539-4570 fax: 256-539-4225 Sources of Ozone •Undissolved ozone released at water surface -Normal regulatory limit is .1 ppm -UL (Spas) or NSF (commercial systems) testing certify systems meet limit -Typically controlled by limiting system output or by ozone contact and/or destruct system •Surface Discharge -Flat Plate design only -Does not generate substantial quantities, but levels can be detected by smell -Controllable by ventilation www.prozoneint.com phone: 256-539-4570 fax: 256-539-4225 Sources of Ozone •Natural Leakage -Occurs as seals degrade or minor natural leaks -Can be a problem depending on severity •Line Breaks or Accidental Discharges -Safety interlocks can limit -Large systems may require emergency shutdown -Respirators required by some states -Vacuum ultraviolet units often allowed to substitute pressure switches which shut of the unit in the vent of a pressure drop (required for compressor systems only) www.prozoneint.com phone: 256-539-4570 fax: 256-539-4225 Sources of Ozone Air Detection Devices •Multiple Types on Market •Two basic types typically used: Low cost units which detect ozone and similar oxidant; and expensive lab grade equipment which detects ozone only, but is difficult to use and uneconomical for many pool applications •Low cost detectors can be set-off by chlorine and its byproducts •Background discharges from electrical equipment in the plant room or atmospheric ozone can also cause false alarms and unnecessary equipment shutdowns if interlocked with equipment www.prozoneint.com phone: 256-539-4570 fax: 256-539-4225 Installation Considerations www.prozoneint.com phone: 256-539-4570 fax: 256-539-4225 Checklist •Bather Loading -Adjustment in sizing may be required if excessive -Is system designed to meet a CT value or to act as a primary oxidizer? •Space Considerations-Is there enough space to install the unit? •Air Monitoring -Are chemicals or electrical equipment in the plant room which could cause erroneous readings? -May not be required for vacuum ultraviolet units •Look at Vendor Claims-ozone is not a stand alone Product, chlorine is still required www.prozoneint.com phone: 256-539-4570 fax: 256-539-4225 Installation Checklist •Training -Corona discharge units will require operator training for: safety, operation and maintenance -Vacuum ultraviolet units require less training •Maintenance and Repair -Review maintenance costs and cost of spares -Check warranty and any warranty exclusions -Check on service an support form vendor -Consider a spares package to limit down time in the event of a component failure -Verify maintenance schedule (Daily, Weekly, Monthly, Annual) -Keep a maintenance log (corona systems) www.prozoneint.com phone: 256-539-4570 fax: 256-539-4225