Zirconia oxygen temperature sensor

Principle and application of zirconia oxygen temperature sensor

Part I Working principle of zirconia oxygen temperature sensor

Ii. Working Principle of oxygen temperature sensor:

At a certain temperature, if the oxygen partial pressure on both sides of zirconia bulk ceramics is not the same, the interior of zirconia bulk ceramics will change. Through both ends, a steady millivolt level signal can be detected, which we call the oxygen potential. It follows nerister equation: in the equation, E is the oxygen potential (mV) output by the oxygen temperature sensor, Tk is the absolute temperature (K) in the furnace, P1 and P2 are the oxygen partial pressure of gas on both sides of zirconia respectively. In practice, one side of zirconia is fed into a gas with a known oxygen concentration, which is called the reference gas. On the other side is the measured gas, which is the atmosphere in the furnace that we want to detect. The signal output by the oxygen temperature sensor is the oxygen potential signal. The relationship between the oxygen partial pressure and the oxygen potential in the atmosphere of the furnace can be obtained through the Ninster equation. When the reference gas is air, it can be expressed as: where E is the output oxygen potential of the oxygen temperature sensor; Tk is the absolute temperature in the furnace; P02 is the partial pressure of oxygen in the furnace. Our oxygen temperature sensor product is equipped with self-heating device, and the general temperature is guaranteed at 700℃, so that the TK value is basically constant, so that the oxygen partial pressure concentration in the furnace can be directly measured through the above formula. In engineering applications, standard gas is used to calibrate the correspondence between oxygen potential E and oxygen partial pressure concentration PO2, which is the most commonly used method at present.

Part II HMP series oxygen temperature sensor

one Basic structure of HMP oxygen temperature sensor:

The HMP oxygen temperature sensor is basically imported zirconia oxygen temperature sensor, the zirconia oxygen temperature sensor is equipped with intelligent heating device, provides constant voltage control signal can quickly reach the use of temperature, and ensure the temperature sensor under the constant temperature continuous, stable work. To install the probe, it is necessary to adjust the direction of the guide plate so that the guide plate is facing the direction of airflow as far as possible, so as to form the gas self-guide flow for the detection atmosphere. Typical performance characteristics of imported zirconia oxygen temperature sensor are as follows: Zero error: ￡± 0.2mV; Ac resistance (1500 hz) :(700℃) : ￡100 kiloohms; ￡5,000 (1100℃). Response time (700-1300℃) : ￡1 second

two Technical performance:

Service temperature: room temperature ~ 1100℃; Oxygen potential display range: -50 ~ 1240mV; Oxygen potential output accuracy: ±0.5mV; Response time: ≤1 second; Normal service life: ≥1 year.

3. Sampling and maintenance methods of HMP oxygen temperature sensor:

The HMP oxygen temperature sensor adopts the atmosphere self-guiding mode to introduce the atmosphere to be tested. Considering the environmental factors on the project site, a purge and scavenging channel is designed to conveniently purge the sampling guide pipe to avoid dust, coal ash, oil impurities and so on blocking the sample pipe in the furnace or pipeline

Part III Installation of oxygen temperature sensor

Reasonable installation is the key to ensure the reliable operation of oxygen temperature sensor. Many problems in use are caused by improper installation of oxygen temperature sensor. We hope that users must pay special attention to this point.

I. Sampling and measurement points:

Determining the measuring point is the primary task. The following principles should be observed:

(1) The selected measuring point should reflect the required atmosphere in the furnace correctly, so as to ensure the authenticity of the output signal of the oxygen temperature sensor and avoid the dead Angle of the return wind as far as possible;

(2) The measurement point should not be too close to the combustion point or nozzle, etc. The atmosphere in these parts is in a violent reaction, which will cause the sharp fluctuation and distortion of the oxygen temperature sensor detection value; Also do not too close to the fan and other gas production equipment, in order to avoid the vibration of the motor erosion damage temperature sensor;

(3) Avoid placing it in a position where collision may occur, so as to avoid damaging the probe by collision and ensure the safety of the temperature sensor;

two Installation and connection of oxygen temperature sensor:

(1) The HMP oxygen probe can be installed in a horizontal or vertical manner, and vertical installation is an ideal installation mode. Regardless of the method used, the orientation of the probe sample guide plate should be as close as possible to the direction of the airflow under test, and the basic orientation can be determined by understanding the process during initial installation. In order to finally determine a good guiding direction, it is necessary to rotate the direction of the sampling tube after the heating probe is electrified in the system and use a digital multimeter to observe the fluctuation of the output oxygen potential.

(2) The joint used for oxygen temperature sensor installation is a special flange joint. If the customer has other type of joint, this joint can be replaced as long as the installation size is the same and the sealing requirements are met. The special joint of oxygen temperature sensor shall be equipped with asbestos gasket as required to ensure the sealing, otherwise the leakage of gas at the flange joint will affect the measurement accuracy or cause signal fluctuation due to the negative pressure in the furnace.

(3) The signal outgoing line of oxygen temperature sensor is better to use shielding wire, which can eliminate interference. The best way is to use two 2-core cables, one 2-core shielded cable connected to oxygen potential output signal, and one 2-core KVV control cable connected to probe to heat the connection end. If field conditions are not available, a 4-core KVV cable can be used directly to connect the probe oxygen potential signal and the heating end. Description of aviation plug welding pin is as follows (see Figure 4) : 1. The heating control signal is connected to the probe's 1 and 2 pins. We have drawn red and yellow color lines. The control lines can be directly welded. 2. The probe measures the oxygen potential output signal connecting the 3 and 4 terminals. Note that the millivolt signal is connected to the positive and negative terminals. The 4 terminals white line is positive and the 3 terminals black line is negative. (4) The standard air port of HMP oxygen probe is generally closed during detection, but only used in the calibration of gas; The purge port is connected to the air pump or compressed air pipeline, and the inlet of the purge port is generally controlled by a valve such as a solenoid valve, which is opened once in a certain period to pass into the gas purge sample tube. The valve is closed when the probe is normally detected, and no other gas can enter the sample tube. In particular, the use of the factory's compressed air purge probe must ensure that the compressed air does not contain water, that is, the use of compressed air must be gas-water separation treatment.

The fourth part is the use and maintenance of HMP oxygen temperature sensor

one Connection heating control:

Special note: the temperature sensor can only work normally after the oxygen temperature sensor is connected to the heating control. The output of the temperature sensor in the cold state is random signal, which does not mean anything! After the HMP oxygen temperature sensor is connected to the heating control, normal atmosphere detection can be started at room temperature. In general, the probe zeroing is to measure the output millivolt value of the probe with a digital multimeter after heating the probe at room temperature by measuring the air. This value is the zero deviation value of the probe. The zero deviation should be added to the display instrument to correct the oxygen concentration displayed by the instrument.

two Points to note when installing or replacing oxygen temperature sensors:

Special reminder: when installing or replacing the oxygen temperature sensor, users should correct the oxygen concentration display value of the oxygen analyzer. Without this work, the oxygen concentration detected by the oxygen analyzer may be deviated from the actual concentration after the replacement of the new temperature sensor, thus affecting the production.

Principles and methods of oxygen concentration correction:

HMP oxygen temperature sensor direct measurement of the output is the difference in measured the concentration of the atmosphere and standard air electric potential value, we called the oxygen potential, the potential value at zero (i.e., air measurement) of different initial probe output potential bias, and the output voltage through model transformation output there may be errors when oxygen concentration, so the probe signal calibration correction in oxygen analyzer is a necessary work, otherwise show oxygen concentration of oxygen concentration and the actual measured atmosphere will, there is a big deviation doesn't satisfy the need of field production, even mislead the control impact the production.

When modifying parameters, the theoretical values provided in the final table can be referred to (this table is pure theoretical calculation values, deviation should be considered in the project), and the measurement system can be adjusted accordingly according to the engineering practice. The specific correction is generally carried out by standard gas calibration. The method is to pass the standard gas confirmed by measurement into the probe through the standard gas port, and then measure the output oxygen potential and the oxygen concentration displayed by the instrument. The oxygen concentration displayed by the instrument should be the same as that of the standard gas. Standard measurement requires at least three different standard gas calibration systems to be used. In this way, the linearity of the system can be corrected after three calibration repetitions to ensure the normal operation of the system.

3. Influence of dust accumulation on oxygen temperature sensor and purging method:

Because the oxygen temperature sensor is long-term on-line detection measurement devices, such as boiler equipment (especially coal combustion furnace or kiln burning powder, etc.) can jam the dust air sampling pipelines, the atmosphere of the measured value distortion even atmosphere, can't be measured at this time must be regularly to purge the sample tube of dust, purging time long myopic degree determine sulphuric, this purging method requires oxygen analyzer has the corresponding function or supporting the use of oxygen temperature sensor device maintenance, if the user does not have these devices can only install manual valves control the compressed air or air pump the scavenging for regular access port to dust removal work of probe, However, the following situations must be noted:

(1) In the process of purging, the oxygen potential of the oxygen temperature sensor will drop, possibly to 1 or 2mV at the lowest. At this time, the detected oxygen potential does not represent the atmosphere in the furnace, which must be paid attention to;

(2) The flow rate of purge air should be ensured to remove ash. During the purge, attention should be paid to the oxygen potential output value of the oxygen temperature sensor. If the oxygen potential value does not decrease all the time, indicating that the air flow is too small and the dust has not been cleaned up, the purge pipe should be adjusted or checked.

(3) The channel of the purge port is directly connected with the furnace. After each purge, the valve should be closed to block the purge hole to prevent the negative pressure air in the furnace from entering and affecting the detection of the oxygen temperature sensor.

Because the work of carbon black burning is complex in the field environment, it is easy to cause human error operation. In order to improve the accuracy of the carbon potential temperature sensor detection and the service life, reduce the human error, preferably using my company's specially designed for my company oxygen temperature sensor HM - OS series oxygen analysis system, the system can provide regular purging instrument functions, control solenoid valve on-off regularly purge (details please refer to the relevant information, or consult our company).

Special note: oxygen temperature sensors should be considered as a separate component in the analysis of their quality. All wires connected to the oxygen temperature sensor should be disconnected when detecting the oxygen potential of the oxygen temperature sensor, and the oxygen potential should be directly detected at the output end of the oxygen temperature sensor with a digital meter with high internal resistance. The oxygen potential is measured and compared with the values in normal use.

Four. Ensure that the oxygen temperature sensor works properly for you during the warranty period:

Oxygen temperature sensor is a very precise detection device, its core components are ceramic, and long-term online work, correct use and careful maintenance is very necessary to ensure the normal operation of oxygen temperature sensor. The user shall strictly install, properly use and maintain the oxygen temperature sensor in accordance with the requirements of this manual. If the oxygen temperature sensor fails to solve itself, please contact us immediately, we will work with you to analyze the cause of the failure, timely repair. It is forbidden for users to disassemble the oxygen temperature sensor by themselves, otherwise irreparable damage will be caused and the shelf life will be invalid.

Five. Warranty of oxygen temperature sensor:

All oxygen temperature sensors sold by the company have a one-year free warranty period, and all temperature sensors that meet the warranty conditions will be repaired free of charge. For the temperature sensor damaged due to the user's failure to install, use and maintain in accordance with the requirements of this manual, the Company does not undertake the warranty obligation, only responsible for paid maintenance, depending on the specific circumstances of the maintenance fee.

The Company will not be responsible for the free warranty of the following temperature sensors:

1. Due to improper installation, neglect of maintenance or equipment failure, the temperature sensor seriously accumulates carbon, which cannot be recovered by normal carbon black burning.

2. temperature sensors that are not installed in accordance with the instructions, causing deformation and corrosion of the outer electrode tube.

3. A temperature sensor that ruptured an internal porcelain tube due to improper protection.

4. The user disassembled the temperature sensor.

5. Other temperature sensors damaged by failure to install, use or maintain as required by this manual.

Special reminder: all the temperature sensors issued by our company have specially designed packing boxes and reliable protective filling and damping materials. The temperature sensors will not be damaged during normal transportation if the packing boxes are in good condition. Users are requested to use the original packaging during handling. When the user needs to send the damaged temperature sensor back to our company for repair, please be sure to use the original packing box and original filling shock absorbers of our temperature sensor, and pack them reliably, and do not use other packaging. Please ship by rail or air, not by post!

If the porcelain tube inside the newly purchased or repaired temperature sensor is broken due to improper handling by the user or improper packaging or delivery of the repaired temperature sensor, we will not undertake the obligation of free warranty!