There are so many types of ozone generator.
The non-corona discharge is in most use for small scale applications.
This article reviews key things to consider its relation to other ozone applications and cost impacts of the generator.
Four key things to consider here are:
Output from generator
Gas feed from generator
A proper selection will depend on the application.
Output From Generator
This is what the ozone generates in grammes per hour or pounds per day based on the application requirements.
It is an essential factor to consider when choosing a generator.
For removal of organic contaminants from water the amount of ozone will be relative to the efficiency and amount of organic in the water.
Ozone is frequently used for reduction of chemical oxygen demand (COD) in water.
COD is measured in milligrammes per litre - mg/l (ppm).
To get rid of COD, It can take 2mg of ozone for a mg of COD. Below is an example:
10,000 litres of water holding 50 mg of COD needs to be treated in an hour. It would require
The litre/hr * mg/l COD * Ozone/mg COD = X mg /hour.
Hence: 10,000*50*2 = 1,000,000mg/hr or 1,000 g/hr or 1 kg/hr
This means that 1 kg/h of ozone or 52.8 pounds of ozone daily needs to be dissolved.
Not all ozone in the water dissolves. Hence there is a need for calculating the transfer efficiency.
Minimum ozone of 90% can be dissolved if using a venturi injector.
Hence, for the above example it would require 1,000,000mg/h ÷ 0.90 = 1111111.11 mg/h or 58.7 pounds of ozone daily.
If the concentration of ozone rises, a given system will generate less ozone.
The dissolving ozone rate rises with rising ozone concentration.
This will establish the required size of the machine.
There is a need for pilot and laboratory studies to establish the needed amount of ozone.
Then an engineer can evaluate to choose the proper balance between generator size, concentration and ozone dose.
This evaluation comes at a cost.
This allows the comparism of generators that appears the same.
Concentrations produced by ozone can range from 1-12 weight percent.
For gas and water treatment, it is 1-3 and 5-10 weight percent respectively.
This concentration affects applications as well as machine output.
Ozone with high concentrations cost more as well as does more in some applications.
The essential part of ozone concentration is by comparing it with various generators.
Here is an instance:
Output (grams/hour) Concentration (%) cost
Seller 1 60 6 5,500dollars
Seller 2 60 4 3,800dollars
In related concentrations the result can change:
Seller 2 60 6 6,000dollars
One way to concentrate oxygen from air is through a process called pressure swing absorption (PSA).In PSA process a molecular sieve takes in water and nitrogen from the air with oxygen left out in the gas stream. Oxygen concentrations of 90-95% are attained. PSA process can be in small scale, for oxygen breathing or large scale for industrial use.
Generator produces heat that needs to be cooled. This can be done through air or water cooling. Water cooling is a more efficient means as it increases the size of generator that can be manufactured. Water cooled systems appear in quite a lot of variations. There are closed loop systems that make use of water chillers and recycle it in the generator.
There is also an indirect cooling loop that utilises ground water. Choice of water cooling systems and chillers is founded on an engineering study for the purpose of assessing larger generator size and chilling water costs.
Manufacturers often set a precise operating temperature for generators at 68-72 degrees Fahrenheit. If it is above the specific temperature, say 82 degrees, for example, it results in a production fall.
Here the generator can shut itself down to avoid damage.
- Identify the application with awareness of the volume and concentration of ozone necessary. If not aware, contract with a competent laboratory or engineering company to undertake the required studies.
- Be sure to compare ozone creation of various generators at similar ozone concentration to have fair price comparism.
- For applications that need more than 5 % ozone, oxygen is required for the feed gas. This will be usual for general water treatment applications.
- For applications that need low concentrations of ozone, choose dry air.
- For small or short applications air-cooled systems can be suitable. Otherwise, water cooled systems are more economical.