Ozone Library
How to Calculate Ozone Generator Capacity for Water Treatment Applications
In water treatment systems, the required ozone generator capacity depends on the water flow rate, target ozone dosage, transfer efficiency, temperature, and overall ozone demand of the water being treated.
The theoretical ozone production required for a given application can be estimated using the following equation:
Required Ozone Production = (Water Flow Rate) x (Ozone Dosage)
However, it’s important to ensure that the units are consistent. If the water flow rate is given in gallons per minute (GPM) and the ozone dosage is given in milligrams per liter (mg/l), we can use the following formula:
Required Ozone Production (mg/hr)= Water Flow Rate (GPM)×3.78 × 60 × Target Ozone Dose (mg/L)
Example: Ozone Generator Sizing for a 40 GPM Water Flow
A water treatment system operates at:
Flow rate: 40 GPM
Required ozone dosage: 2 mg/L
Ozone Production = 40 GPM x 3.78 L/gal x 60 min/hr x 2 PPM = 18144 mg/h (18.1 g/h)
This represents the minimum theoretical ozone generator output required under ideal laboratory conditions.
Practical Engineering Considerations
In real-world applications, the ozone generator must be sized above the theoretical requirement to compensate for mass transfer losses and ozone demand within the water matrix.
Ozone Mass Transfer Efficiency
Ozone must first transfer from the gas phase into the liquid phase before disinfection or oxidation can occur.
Typical transfer efficiencies:
- Venturi Injector: 60-95% Transfer Efficiency
Typical Dissolution Efficiency Based on Ozone Gas Concentration
| Ozone Gas Concentration(%wt) | Typical Dissolved Ozone from Total Produced |
|---|---|
| 1% wt | <10% |
| 3% wt | 20 -30 % |
| 5 – 7% wt | 50 -70 % |
| 8 – 10% wt | 80 – 90 % |
| 10 – 14% wt | 95% |
| 14 – 22% wt | 97% |
Effect of Water Temperature
The half-life of ozone refers to the amount of time required for half of a given quantity of ozone to decay into oxygen. Ozone is an unstable gas and readily decomposes into oxygen. Therefore, the half-life of ozone is an essential factor to consider when determining its effectiveness in various applications.
| Temperature (Celsius) | Half-life time (min) |
|---|---|
| 15 | 30 |
| 20 | 20 |
| 25 | 15 |
| 30 | 12 |
| 35 | 8 |
Interactive Ozone Generator Calculator
Use the calculator below to estimate the theoretical ozone production required for your specific application.
Ozone Production needed based on your water flow rate and ozone dosage (ppm)
Note: The result shows the amount of ozone in g/h needed to dose the water with the selected PPM of ozone. However, the actual ozone generator production may need to be higher due to factors such as mass transfer efficiency, water temperature, and the ozone demand of the water.
Ozone Conversions and Equations
A web resource dedicated to explaining the science behind the main ozone conversion formulas and equations.
OZONE CONCENTRATION IN WATER:
1 mg/l = 1 PPM O3 = 1 g O3/m3 water
1 ppm (One part per million) equals one unit for every one million units of the mixture. To put it in perspective, 1 g of ozone gas dissolved in 1 m3 of water will create a concentration of 1 ppm or 1 g/m3
OZONE CONCENTRATION IN AIR BY VOLUME:
1 g O3 / m3 = 467 PPMv O3
This means that a concentration of 1 gram of ozone per cubic meter equals 467 parts per million by volume of ozone in the air.
1 PPMv O3 = 2.14 mg O3/m3
This indicates that 1 part per million by volume of ozone equals a concentration of 2.14 milligrams of ozone per cubic meter.
100 pphm (parts per hundred million) = 1 ppm (parts per million)
OZONE CONCENTRATION IN AIR BY WEIGHT:
100 g O3/m3 = 7.8% O3 (Approximate)
1% O3 = 12.8 g O3/m3 (Approximate)
1% O3 = 7,284 PPM Ozone
OZONE CONCENTRATION IN OXYGEN BY VOLUME:
100 g O3/m3 = 6.99% O3 (Approximate)
1% O3 = 14.3 g O3/m3 (Approximate)
1% O3 = 6,520 PPM Ozone
Conversion Table for Ozone Gas Phase Concentration in Oxygen
| Weight % | Volume % | Concentration g/m3 | Productivity g/hr at 1 l/min Gas flow |
|---|---|---|---|
| 1 % | 0.7 % | 14.3 g/m³ | 0.86 g/hr |
| 2 % | 1.3 % | 28.7 g/m³ | 1.72 g/hr |
| 3 % | 2.0 % | 43.3 g/m³ | 2.60 g/hr |
| 4 % | 2.7 % | 57.9 g/m³ | 3.47 g/hr |
| 5 % | 3.4 % | 72.6 g/m³ | 4.36 g/hr |
| 6 % | 4.1 % | 87.4 g/m³ | 5.24 g/hr |
| 8 % | 5.5 % | 117.3 g/m³ | 7.04 g/hr |
| 9 % | 6.2 % | 132.5 g/m³ | 7.95 g/hr |
| 10 % | 6.9 % | 147.70 g/m³ | 8.86 g/hr |
| 12 % | 8.3 % | 178.5 g/m³ | 10.71 g/hr |
| 14 % | 9.8 % | 209.7 g/m³ | 12.58 g/hr |
| 16 % | 11.3 % | 241.3 g/m³ | 14.48 g/hr |
| 18 % | 12.8 % | 273.4 g/m³ | 16.40 g/hr |
| 20 % | 14.3 % | 305.9 g/m³ | 18.36 g/hr |
| 22 % | 15.8 % | 338.9 g/m³ | 20.34 g/hr |
| 24 % | 16.8 % | 343.2 g/m³ | 22.13 g/hr |
| 25 % | 17.87 % | 382.38 g/m³ | 22.95 g/hr |
DETERMINE THE OUTPUT OF AN OZONE GENERATOR:
To determine the output of an ozone generator, we can use the following formula:
ozone production = (feed flow rate) x (ozone concentration) x (0.056)
For example, suppose the ozone concentration leaving the generator is 141.6 g/m3 and the oxygen flow rate is 6 liters per minute. The output can be calculated as follows:
ozone production = 6 L/min x 141.6 g/m3 x (1 m3/1,000 L) x (0.056) = 47.58 g/h
SAMPLE CONVERSIONS:
Convert 140 g/m3 to wt% (oxygen feed gas).
based on the conversion above, 100 g/m3 = 6.99 wt. %
therefore 140 g/m3 / 100 g/m3 x 6.99 wt. % = 9.8 wt.%
PHYSICAL PROPERTIES STANDARD CONDITIONS (P= 1013.25 MB, T = 273.3K)
Ozone density: 2.14 kg/m3.
Oxygen density: 1.43 kg/m3.
Air density: 1.29 kg/m3.
Water density: 1 kg/m3.
Ozone Molecular weight: 48 kg·mol−1.
Oxygen Molecular weight: 32 kg·mol−1.
BUNSEN COEFFICIENT(β)
The solubility of ozone can also be calculated with the Bunsen adsorption coefficienT. The formula that can be used to calculate the solubility is:
Cs = β * M * P
Cs = Concentration dissolved gas (kg/m3)
Β = Bunsen adsorption coefficient (-)
M = Density of the gas (kg/m3)
P = Partial pressure (Pa)
The Bunsen adsorption coefficient is expressed as a volume of gas at NTP (normal pressure and temperature), which is dissolved at equilibrium by a unit volume of liquid at a given temperature, when the partial pressure of the gas is the unit atmosphere. The Bunsen coefficient has no dimension.
β = Vg / Vl
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