Common faults and causes of zirconia oxygen analyzers

1. System maintenance.

If the oxygen indicator shows zero or no oxygen indication in the oxygen quantity converter, first check whether the oxygen indication circuit open. If the circuit is normal, check whether the zirconia probe is normal. At a temperature of 700℃, measure the DC millolt value of the oxygen cell. If the potential is greater than 1 millivolt and the resistance is greater than 100Ω, it indicates the probe is aged and needs to be replaced with a sensor or probe. If the potential is less than 1 millivolt and the resistance is less than100Ω, it indicates an open circuit in the wiring, which should be checked and handled one by one.

2. constant temperature system failure.

(1) If the heating temperature cannot be maintained, check whether there is a short circuit or open circuit in the resistance wire inside the heating furnace The normal resistance of the heating furnace wire is about 60-80Ω. If the resistance wire is open or the resistance measured by the multimeter less than 60Ω, the heating furnace wire should be replaced.

(2) When the converter shows that the temperature is too high or out of control, it not only causes inaccurate oxygen display but also acceler the aging or damage of the zirconia head. At this point, you should immediately check if the thermocouple is open-circuited, or a multimeter to check the thermocouple. If the resistance is greater than 20Ω, it is judged that the thermocouple is open-cuited, and the thermocouple and zirconia head should be replaced; another reason for the temperature失控is: relay or temperature control circuit failure, relay or temperature control circuit failure will cause the oxygen converter to always be in one of the heating voltages of the heating furnace, thus leading to an increase in.

3. oxygen cell fault.

(1) After the oxygen cell has been used for a period of time, the contact points of its leads may become oxidized, resulting in contact or detachment. This can cause the Em value (in units of a multimeter) to fluctuate and become unstable. Observe the oxygen cell and take action.

(2) When the oxygen signal deviation is too large or inaccurate, it may be due to a short circuit in the zirconia electrode, which case the wiring of the zirconia cell should be checked for short circuits. When the temperature does not rise, if the internal resistance is less than 0Ω, it indicates a short circuit in the electrode, and the zirconia head needs to be replaced.

(3) During the operation of the oxygen measurement device, if the background potential exceeds 10mV or is less than -30mV, it must be recalibrated. If the background potential remains abnormal after calibration, it indicates that the probe has aged and can no longer be used.

4. pneumatic circuit failure.

(1) The zirconia head is clogged with ash, causing an obstruction in the reference gas circulation. This results in a decrease in probe output potential Em and an increase in the background potential Eo. In this case, blowing several times with a bulb syringe at the gas inlet of the will resolve the issue after the gas line is unclogged.

(2) Oxygen cell ash blockage: The probe should be removed from the ash blockage and the filter should be reinstalled.

(3) Probe leakage has a significant impact on the probe.

5. The oxygen content on both sides of the boiler is too high.

By adjusting the boiler combustion conditions, when starting or stopping the boiler fan or coal mill group, if the oxygen content deviation on both sides of the boiler is large, it is a normal phenomenon. Once the boiler combustion conditions stabilize, the oxygen content display will return to normal. If the unit adjustment is not in place and the deviation is large on both sides, it is necessary to check if the zirconia head is working properly by dismantling the transmitter for inspection. The device requires the operator to adjust the gas flow. The gaseous and reference state gases should continuously flow through the electrode without stopping, and there should be no dead ends. However, too large a flow will have a cooling effect, making the cell temperature uneven and causing errors. If the flow is too small, it is not only easy to form stagnant gas flow and dead zones but also may cause local changes in oxygen concentration due to the conduction of oxygen ions, thus affecting the accuracy of the measurement and causing deviations on both sides.

6. On-site interference causes failures.

For newly installed instruments, due to the strong electromagnetic field, when an unstable fault occurs, the first thing to consider is the interference issue.