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The first part of the work principle of zirconia oxygen sensor
Product introduction:
Zirconia oxygen sensor is the oxygen potential using zirconia ceramic sensing element measuring various heating furnace or exhaust pipe, the chemical equilibrium principle to calculate the oxygen concentration of the corresponding, to monitor and control the combustion air-fuel ratio in the furnace, to ensure product quality measurement and exhaust emission standards, control is widely used in various types of coal combustion, oil burning, gas burning furnace atmosphere etc.. It is the best way to measure the combustion atmosphere, which has the advantages of simple structure, quick response, easy maintenance, easy to use, accurate measurement and so on. Using the sensor to measure and control the combustion atmosphere can not only stabilize and improve the product quality, but also shorten the production cycle and save energy.
Two, oxygen sensor working principle:
The oxygen sensor is designed to utilize the characteristics of the oxygen ion conduction in the stable two zirconia ceramic in the environment above 650. At a certain temperature, if the gas two zirconia ceramic block respectively on both sides of the existence of different oxygen pressure (i.e. oxygen concentration), two zirconia ceramic interior will produce a series of reactions, and the migration of oxygen ions. Then through the two extraction electrode of zirconia on both sides of the detected millivolt signal stability, we call the oxygen potential. It follows the Nernst equation: the oxygen potential (E) of the oxygen sensor output in the formula, Tk is the absolute temperature (K), and MV of the oxygen sensor in the furnace. The oxygen partial pressure of the gas on both sides of P1 and P2. In practical application, the air in the known oxygen concentration (usually air), which is called the reference gas, is the one of the two zirconia. The other side is the gas being measured, that is, we want to detect the atmosphere inside the furnace, as shown in figure 1. The signal of the oxygen sensor output is the oxygen potential signal. By the equation of the equation, we can get the relationship between the oxygen partial pressure and the oxygen potential in the atmosphere. When the reference gas is air, it can be expressed as: the type E is the oxygen sensor output oxygen potential; Tk is the absolute temperature of the furnace; P02 is the oxygen partial pressure in the furnace. Our oxygen sensor products with a self heating device, the general temperature of 700 degrees Celsius, so that the TK value is basically constant, so as to directly measure the oxygen partial pressure. Standard gas is used to calibrate the corresponding relationship between the output oxygen potential E and the oxygen partial pressure concentration PO2 of the oxygen sensor. This method is also recognized as the most accurate and direct method.
Second part HMP series oxygen sensor
Basic structure of a.HMP oxygen sensor:
The core components of the HMP oxygen sensor adopts imported zirconia oxygen sensor (see Figure 2), the zirconia oxygen sensor with intelligent heating device, provides stable constant control signal can be quickly achieved by using temperature, and ensure the constant temperature sensor in a continuous and stable work. The installation of the probe need to adjust the guide plate direction, try to make the board to guide the direction of the flow, so as to form a gas detection of atmosphere self flow. The following imported zirconia oxygen sensor typical performance characteristics: zero error: F + 0.2mv; AC resistance (1500 Hz): F (700 C) 100 thousand euro (1100 C); $5 thousand in europe. Response time: 1 f (700-1300 C)
Two.HMP oxygen sensor sampling, maintenance mode:
HMP oxygen sensor using atmosphere flow into the atmosphere by homing, detection, considering the environmental factor of engineering field, design of purge purge passage for purging the sampling pipe guide conveniently, in order to avoid the dust in the furnace, or pipe ash, oil and so on impurities plug the sampling tube, please refer to figure 3.
Three. Technical performance:
Use temperature: room temperature to 1100 DEG C; the oxygen potential display range: - 50 ~ 1240mV; the oxygen potential output accuracy: + 0.5mV; response time: less than 1 second; the service life of the normal use is not less than 18 months.
Installation of third part oxygen sensor
Reasonable installation is the key to ensure the reliable operation of the oxygen sensor, many problems are caused by improper installation of the oxygen sensor, hope that the user must pay special attention to this point, the oxygen sensor is installed please try to consider requirements for oxygen sensor installation:
Sampling measuring point:
Determining the measurement point is the most important task. The following principles should be followed:
(1) the selection of the measurement points can correctly reflect the atmosphere needed in the furnace, in order to ensure the authenticity of the output signal of the oxygen sensor, try to avoid the dead return;
(2) is too close to the burning point or nozzles and other parts of measuring points can not, these parts in the reaction atmosphere, will cause the oxygen sensor detection value volatility distortion; do not be too close to the fan of gas production equipment, in order to avoid the damage to the motor vibration scour sensor;
(3) to avoid the position of the possible collision, so as to avoid collision damage to the probe, to ensure the safety of the sensor;
Two. Installation and connection of oxygen sensor:
(1) the installation of HMP oxygen probe can be horizontal or vertical, vertical installation is an ideal way to install. No matter what the way, the direction of the probe sampling tube guide plate should be as far as possible to the direction of the airflow direction, in the initial installation of the process can be determined by understanding the basic direction. Finally determine the better guide direction, the need for the system through electric heating probe, the direction of the rotating sampling tube, the use of digital meters to observe the fluctuation of output oxygen potential to determine.
(2) the connection of the oxygen sensor installation is a special flange joint. If the user has other types of joints, as long as the installation of the same size, in accordance with the requirements of the seal can also replace the joint. Special joint oxygen sensor, according to requirements with asbestos pad crimp, to ensure the seal, or because of the negative pressure is generally in the furnace, the flange joint leak will affect the measurement accuracy or cause signal fluctuation.
(3) the signal of the oxygen sensor leads the line to be best to use the shield line, may eliminate the interference. The best way is to use 2 2 core cable, a 2 core shielded cable connected to the oxygen potential output signal, a 2 core KVV control cable connecting end of probe heating; if the condition does not have can be used directly to a 4 core KVV cable to connect the probe oxygen potential signal and the heating end. The aviation plug feet are as follows (see Figure 4): 1 heating control signals connected to a probe air plug 1, 2 feet, we have drawn red, yellow two colors can be directly connected with the control line, welding line; 3, 4 foot connecting 2 probe for measuring oxygen potential output signal, pay attention to the positive and negative millivolt signal connections 4 feet, 3 feet, white line is black line is negative, the signal line can be directly connected with a lead wire welding. (4) when it was detected the air intake of the HMP oxygen probe closed only when using the calibration gas; purge air inlet is connected with the pump or compressed air pipeline, blowing air intake with a solenoid valve control valve, a certain period of opening time, pass into the purge gas sampling tube, close the valve probe the normal test, there is no gas into the sampling tube. In this particular point, the use of compressed air purge probe must ensure that water does not contain compressed air, namely the compressed air must be processed gas water separation.
