How to choose an ozone generator must know the evaluation index of the ozone generator. Generally, the most basic indicators for evaluating an ozone generator are: ozone production, ozone concentration, reliability, service life, convenient and beautiful work, power consumption, etc. The power of ozone generators used in pharmaceutical factories is relatively small, and power consumption is a secondary condition.
(1) Basic knowledge
In order to better choose the ozone generator, first introduce a little basic knowledge about ozone and ozone generator.
Ozone concentration unit:
· Nominal ozone concentration by volume percentage concentration for international traffic. The ozone concentration of 1% air source is 12.9mg / L. The ozone concentration at 1% oxygen is 14.3mg / L.
· The sanitation and disinfection industry is accustomed to use ppm as the unit. That is one part per million. For ozone in the air, 1ppm = 2.14mg / M3.
1. Ozone concentration:
The ozone concentration at the outlet of the ozone generator. Generally, the unit is ppm or mg / L. 1ppm = 0.00214mg / L.
Surface discharge electrode: The outlet concentration of the ozone generator is low, generally 60-80ppm (generally less than 20PPM in air source).
Gap discharge electrode: The outlet concentration of the ozone generator is high, generally 25000-40000ppm.
2. The form of electrode discharge:
· Surface discharge type electrode (that is, glass tube is generally used as dielectric material, in-pipe ventilation and out-tube ventilation):
One is the aluminum mesh with the inner electrode attached to the inner wall of the glass tube, and the outer electrode is a conductive coating such as graphite. There is gas in the tube. The other is to fill the glass tube with nitrogen and a small amount
Argon or krypton gas, the inflation pressure is thousands of pa, the inner electrode is a nickel wire, and the outer electrode is an aluminum mesh sleeved on the outer wall of the glass tube. Gas passes outside the tube.
· For these two electrodes, only a small amount of gas flowing along the wall of the tube participates in the discharge, and the output is low. The accumulation of ozone output will gradually decrease with the use of time. At the same time, the reliability is poor,
Short life. (3000-6000 hours) But the cost is low, the production is simple, and a few people can assemble and produce. Generally there is no perfect inspection equipment.
· Gap discharge electrode:
One is to use a ceramic tube as the dielectric material, the outer wall is plated with a metal coating for the outer electrode, the metal tube is for the inner electrode, and the tube is cooled by water. Oxygen from the gap between the inner and outer electrodes
Pass in the gap. The other is a plate-type ceramic dielectric gap discharge electrode. Air cooling or water cooling, oxygen passes through the gap between the two electrodes.
For these two electrodes, the gas is discharged through the gap between the electrodes, with high output, high reliability and long life (over 30,000 hours). Ozone production and equipment
The use time is irrelevant, but the cost is high, it requires finishing, complicated assembly and debugging, and requires factory production. Have perfect testing equipment.
3. Air source
Most of the surface discharge type ozone generators use ambient air as the air source, which produces more nitrogen oxides. After the nitrogen oxides are in contact with the humidified air in the air duct, it is very easy
Sour gas (nitric acid) is generated. Decreasing the electrode life has an adverse impact on the environment.
Most of the gap discharge ozone generators use an oxygen source or a dry air source, which produces less nitrogen oxides, has a long electrode life, and is not harmful to the environment
influences. The oxygen source can be bottled oxygen, or an oxygen generator or dryer.
4. Power supply
The power supply is divided into power frequency, intermediate frequency, and high frequency. The power supply frequency is high and the number of discharges is high, the efficiency is high and the power consumption is saved, and the electrode volume is small.
5. Quality classification
· Low-grade products-built-in air source products-surface discharge type-industrial frequency power supply-poor protection function-installation requires air conditioning cooperation.
· Mid-end products-external air source products-gap discharge-with air dryer-air compressor-protection capability-installation has nothing to do with air conditioning.
· High-end products-external is an oxygen source product-gap discharge-bottled oxygen or oxygen generator-strong protection ability-installation has nothing to do with air conditioning.
(2) Test results of different electrodes
In order to verify the relationship between the nature of the gas source (oxygen source, air source) and the output, and the relationship between the different discharge forms (creep discharge \ gap discharge) and the output, the author, with the help of a research institute, inflated the tubular ozone discharge The electrodes, the tubular ozone electrode with non-inflatable surface discharge, the tubular ozone electrode with gap discharge, and the plate ozone electrode with gap discharge were tested. The results are as follows:
In order to unify the test conditions, the author tested the following four electrodes using an oxygen source, and the output was the highest output of these four electrodes.
A. ф29 × 265mm non-inflatable glass along-surface discharge tube ozone electrode. (The oldest electrode form)
· Electrode structure: glass tube electrode, the inner electrode is an aluminum mesh attached to the inner wall of the glass tube. The outer electrode is graphite coated. There is gas in the tube.
· Working principle: The transformer boosts the mains electricity to high voltage electricity, powers the electrodes, and generates ozone between the inner electrode and the inner wall of the glass tube. Pass oxygen into the discharge tube,
After energizing, measure the gas volume and ozone concentration.
Oxygen 2M3-4M3 / h, the highest ozone concentration is 50-70ppm; the calculation result is 3M3 / h × .60ppm × .2.14mg / m3 = 385mg = 0.39g / h per tube
(The ozone concentration in the air is 1ppm = 2.14mg / m3)
The surface area of this tube is: 0.029M × 3.14 × .265M = 0.024M2 The discharge tube required per square meter of discharge area is: 1M2 ÷ 0.024m2 = 41.
· Therefore, 41 such electrodes can be obtained, which can produce 15.99 grams of ozone per hour using an oxygen source. If using a dried air source can produce
5.33 grams of ozone. This type of discharge tube also does not comply with the provisions of CJ / T3028.1-94, Article 5.3.2, the ozone output per square meter of discharge area should be greater than 30 grams.
B. Ø29 × 265 mm inflatable glass tube discharges ozone electrode along the surface. (Improved electrode, good looking during discharge, also known as discharge lamp, limited production increase)
Electrode structure: glass tube electrode, filled with nitrogen and a small amount of argon or krypton gas, the inflation pressure is thousands of pa, the inner electrode is a nickel wire, and the outer electrode is sheathed in glass
Aluminum mesh on the outer wall of the tube.
· Working principle: The transformer boosts the mains electricity to high voltage electricity, powers the electrodes, and generates ozone between the outer electrodes and the glass tube. Put this discharge tube into a closed
Oxygen is introduced into the UPVC pipe, and the gas volume and ozone concentration are measured after power is supplied.
Oxygen 2M3-4M3 / h, the highest ozone concentration is 60-80ppm; the calculation result is 3M3 / h × 70ppm × 2.14mg / m3 = 449mg = 0.45g / h
(The ozone concentration in the air is 1ppm = 2.14mg / m3)
The surface area of this tube is: 0.029M × 3.14 × .265M = 0.024M2 The number of discharge tubes required per square meter of discharge area is: 1M2 ÷ 0.024m2 = 41.
Therefore, 41 such electrodes can be obtained, using an oxygen source, which can produce 18.45 grams of ozone per hour. If using a dried air source can produce
About 6.15 grams of ozone. This type of discharge tube does not comply with the provisions of CJ / T3028.1-94 5.3.2 The ozone output per square meter of discharge area should be greater than 30 grams.
The CJ / T3028.1 standard requires dew point for gas source as follows:
5.3.1 The performance test of ozone generator products (including ozone generating power supply) shall be carried out under the following conditions:
A. With air as the air source, the dew point cannot be higher than minus 450C.
In the application of GMP air sterilization, the humidification system of the air conditioner humidifies the intake air. The dew point of the humidified air is much higher than minus 450C, which is generally only slightly lower than room temperature.
Therefore, using the circulating air of the air conditioning unit as the air source does not meet the dew point requirements of the air source of the CJ / T3028.1 standard.
★ The above two types of discharge tube electrodes, even in the case of using an oxygen source, have not yet reached the rated output. If an air source is used, it is even more pitiful.
★ The electrode is working under high voltage discharge, and it is not suitable to work in a humid environment. Otherwise, the output will drop significantly.
★ It is not difficult to see through the above test: If the equipment used to calibrate the ozone output with oxygen source, if air is used as the gas source. Its actual ozone output is only calibrated by famous brand
1/3 of output. That is, the original design was 10ppm dosage, but actually only added 3.3ppm.
★ Unfortunately, people who say that ozone sterilization is not as good as formaldehyde use this machine.
B. ф41 × 300 mm tubular ceramic dielectric gap discharge electrode.
The ceramic tube is used as the dielectric material, the outer wall is plated with a metal coating for the outer electrode, and the metal tube is the inner electrode, and the tube is cooled by water.
Oxygen passes through the gap between the inner and outer electrodes.
Oxygen is introduced in 0.8M3 / h, and the average ozone concentration is 50g / M3.
Calculation result The output of single tube is 0.8M3 / h × 50g / M3 = 40g / h The surface area of this tube is:
0.041M × 3.14 × 0.260M = 0.033M2 The discharge tubes required per square meter of discharge area are: 1M2 ÷ 0.033m2 = 30.
· Therefore, 30 such electrodes can be obtained. Using an oxygen source can produce 1,200 grams of ozone per hour. If an air source is used, it can produce about 400 grams of ozone per hour.
This type of discharge tube is much higher than the provisions of Article 5.3.2 of CJ / T3028.1-94.
C, 212CM2 plate ceramic dielectric gap discharge electrode.
The electrode is air-cooled. Oxygen is introduced in 0.5M3 / h, and the average ozone concentration is 50mg / L.
Calculation result: the output of a single group is 0.5M3 / h × 50mg / L × 1000 = 25000mg = 25g / h
The surface area of this board is: 0.021M2, and the discharge board required per square meter of discharge area is: 1M2 ÷ 0.021m2 = 47.6 sets.
· As a result, 47.6 sets of this type of electrode were obtained. Using an oxygen source can produce 1190 grams of ozone per hour. If an air source is used, it can produce about 397 grams of ozone per hour.
This type of discharge tube complies with the provisions of Article 5.3.2 of CJ / T3028.1-94.
With the above test data, you only need to understand the quality of the ozone generator by understanding the type of gas source, discharge electrode form, and power frequency. Even counting a few electrodes can roughly estimate how much ozone is produced.
Then choose the low-grade, medium-grade or high-grade ozone generator according to your needs.
★ In summary, there is no standard for ozone generator for GMP transformation. In order to regulate the application of ozone in GMP air purification, it is urgent to establish a unified standard for ozone equipment for GMP (Ministry-issued standards or industry standards)