Before the technology of the magnetic flap level gauge was reformed, domestic level gauges were accurately used in normal medium measurement. However, with the development of high-speed industries such as industrial chemicals, machinery, petroleum, and electricity, they often encounter special problems. The influence of the environment and special media makes the level gauge unable to use normally and does not reach the required state! The following example illustrates the next. For example, the measurement of the boiler drum water level is very important for the safe operation of the boiler. If the water level is too high or too low, the steam quality will deteriorate or the water cycle will deteriorate or even cause an accident. Measuring the liquid level on the air-boiler of large-scale boilers with the magnetic flap level gauge has the advantages of high sealing, anti-leakage and good reliability. However, in its sensors, the reed switch used for mechanical-electrical conversion is only able to work in working environments below 120 OC. Therefore, in the high temperature environment, the reed switch magnetic pole level gauge cannot output electrical signals. Need to find a new type of sensor to solve this problem. This paper presents a new type of capacitive gate magnetic level gauge. It is based on the reed switch magnetic level gauge, the use of capacitive sensors instead of the reed switch as a remote transmission device. Because the accuracy of the sensor directly affects the measurement result, in order to design the optimal sensor, the far field unit and the Trefftz finite element method are used to mathematically model the capacitance sensor. The simulation results of the two are compared with the experimental values. The Hybrid-Trefftz finite element is an effective method. The relative error between it and the true value is only 3.3%. The ANSYS large-scale finite element software was used to optimize the design of four different types of capacitive sensor plates and structures, so as to select the optimal structural parameters and develop a model prototype for capacitive sensors. Since the capacitance between the capacitance plates of the capacitive sensor is several pf, the small capacitance measurement circuit based on the charge-discharge principle is adopted in order to accurately detect the variation of the capacitance. The MSP430 single-chip microcomputer is used to control the gate of the capacitance plate in the capacitive gate sensor, data acquisition and processing, and the liquid level value is calculated and the PWM wave is output. The subsequent circuit is converted into a two-wire 4-20MA current signal. After the system is successfully debugged, analog detection measurement and temperature characteristic analysis are performed. The sensor can distinguish the flip state of the magnetic column, but its repeatability is different in the detection of each capacitor plate. The repeatability of the plate detection is better 0.035%, and the poor is 8.9%. The temperature characteristic is mainly determined by the temperature characteristics of the sensor and the detection circuit. The capacitive gate sensor can be made of a high temperature resistant material, and the detection circuit can be moved away from the measurement cylinder through the shield lead, and a heat sink can be added at the lead. In terms of design, stray capacitance circuits are used to reduce the effects of stray capacitance on the leads. Comprehensive test results show that this capacitive gate magnetic level gauge can achieve liquid level measurement and can meet system design requirements.
Until now, because of the technical innovation of the magnetic flap level gauge, there is now a high-temperature and high-pressure magnetic flap level gauge, which also reduces the cost for the majority of users. When the domestic level gauge does not reach the mature state, it uses imported liquid at a high price. Position meter. Only the continuous advancement of technology symbolizes the progress of the industry and symbolizes economic progress! !
Until now, because of the technical innovation of the magnetic flap level gauge, there is now a high-temperature and high-pressure magnetic flap level gauge, which also reduces the cost for the majority of users. When the domestic level gauge does not reach the mature state, it uses imported liquid at a high price. Position meter. Only the continuous advancement of technology symbolizes the progress of the industry and symbolizes economic progress! !