Oxygen Gas analyzer


Oxygen Gas Analyser




 

What is a Gas Analyzer?


Definition of a gas analyzer

A gas analyzer measures or traces the concentration of a specific gas in a sample gas.

In industry, gas analyzers are used to measure the concentration of oxygen, CO, NOx, SO2, or any other gas for the smooth operation of the process, fuel-saving, and environmental protection.

Oxygen gas analyzers

There are four types of oxygen measuring methods used in the industry. 

1. Zirconia type oxygen analyzer

 Zirconia is a solid electrolyte that exhibits a conductivity of oxygen ions at a high Temperature of 800 centigrade.

Working principle of zirconia gas analyzer

 In the zirconia gas analyzer porous Platinum electrodes are attached on both sides of the Zirconia element to be heated up and sample gases of different types having a partial oxygen concentration are brought into contact with respective surfaces of the Zirconia, so the device act as oxygen concentration cell. As shown in the figure below zirconia cell working is explained.



Ionization of oxygen gas in the sample causes an emf to be generated between both electrodes and voltage is induced on the electrodes,  the induced voltage is directly proportional to the oxygen concentration in the sample has of the gas analyzer. 

Zirconia analyzer Advantage

Zirconia oxygen analyzer Can be directly installed in a combustion process no sampling is required.

Zirconia analyzer Disadvantage

If a flammable gas is present in the sample a measurement error occurs in the zirconia analyzer, so it is not recommended to measure flammable gas. 

2. Paramagnetic type oxygen           analyzer

The paramagnetic oxygen measurement method uses the paramagnetic property of the oxygen. When oxygen is passed through a magnetic field, the oxygen ions are attracted by the magnetic field so the advantage is taken by this paramagnetic quality of the oxygen.

 A dumbble is used to deflect the light emitted by a light source and the deflection in light is detected by a light detector, the deflection of light is directly proportional to the concentration of oxygen gas in the sample. 

This analyzer is a dumbbell-type paramagnetic oxygen analyzer. Because this analyzer is based on that the magnetic susceptibility of oxygen gas is larger than coexisting gases, stable measurement is ensured which is unaffected by coexisting gases in the sample. 

A paramagnetic oxygen analyzer is suited for measuring the oxygen concentration in the inflammable gas. The principle of measurement of oxygen in the sample gas is dependent on the strong magnetic property of oxygen molecules. Therefore, measurement is almost unaffected by other molecules weaker in magnetic property than oxygen.

 Advantages of Paramagnetic gas analyzer 

 1. Paramagnetic type oxygen analyzer is Suitable for measuring oxygen concentration in the inflammable gas sample.

 2. Paramagnetic oxygen analyzer is Smallin size so it is manageable to handle.

 3. we can use a paramagnetic oxygen analyzer with a wide range of power supplies.

 4. The output of the paramagnetic type oxygen analyzer is linear.

 Working principle of paramagnetic oxygen analyzer

In a paramagnetic oxygen analyzer, two glass spheres filled with nitrogen gas are suspended with the support of a strong metal wire. At first, the spheres are kept in balance in an inhomogeneous magnetic field. 




When oxygen molecules having a large magnetic susceptibility flow in this magnetic field, the molecules are pulled toward the stronger magnetic field zone and the spheres are moved away from the zone. The resulting deviation of the spheres is detected with the light source, reflecting mirror, and the light-receiving element and a current is flowed through the feedback loop to control the imbalance, due to this current, spheres can return to the initial balanced state. The current flowing through the feedback loop is proportional to the oxygen concentration in the sample gas. Thus, the oxygen concentration is converted into an electric signal. 

3. Optical type oxygen analyzer

An optical type gas analyzer is also called TDL (Tunable Diode Laser). It is used to measure the concentration of gas. The quantity of lasers absorbed by the gas is directly proportional to the concentration of gas in the sample. So the more absorption of the laser means a high concentration of gas in a sample gas.




4. Electrochemical type oxygen analyzer

In this type of oxygen analyzer Oxygen is dissolved in an electrolytic solution. Two electrodes (anode and cathode) are used to measure the current passing through the electrolyte, this current is directly proportional to the concentration of oxygen in the solution. This is a very simple chemical method for oxygen analysis.





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