Liquid level measuring device based on capacitive sensor

Abstract

The invention discloses a liquid level measuring device based on a capacitive sensor. The liquid level measuring device comprises a capacitance detection unit, an initialization unit and a control chip unit, wherein a plurality of capacitive sensors used for detecting a liquid level in a storage tank are arranged in the storage tank, and liquid level capacitive sensors used for carrying out real-time capacitance data detection on liquid level detection points are arranged at different vertical heights; the initialization unit is used for initializing a capacitance during no-load and a capacitance value during full-load; the control chip unit is used for making the plurality of capacitive sensors periodically measure capacitance data of an environment in the tank so as to obtain a state ofa current fixed point liquid level and judge whether a liquid reaches a liquid level height at the fixed point; and meanwhile, the capacitive sensor for detecting a gas is arranged at a top of the tank, a change curve of the capacitance in the gas along with a change of the liquid level of a liquefied natural gas in the sensor is counted, and the height of the current liquid level is calculated inan auxiliary mode through the capacitance value measured by the capacitive sensor for detecting the gas. The structure is simple, the number of leads is small, and device reliability is improved.

Description

technical field [0001] The invention relates to the technical field of liquid level detection, in particular to a liquid level measuring device based on a capacitive sensor. Background technique [0002] Fixed-point liquid level detection is to measure the liquid level at several fixed positions, such as upper and lower limit indications, segmental liquid level indications, etc. There are many liquid level measurement methods, such as capacitance method, resistance method, magnetostriction method, magnetic flap method, vibration method, float level gauge method, laser liquid level method, optical fiber liquid level method, differential pressure method, etc., liquid level switch method, safety valve method, servo liquid level gauge method, etc. [0003] The differential pressure method is currently one of the most commonly used methods for measuring the liquid level in a storage tank. This method can only ensure the accuracy of the measurement when the liquid density is cons...

AI Technical Summary

Problems solved by technology

[0006] The above detection method of the liquid level detector has the following disadvantages: the quality of liquefied natural gas will vary due to factors such as the place of origin, among which, the difference in the dielectric constant of different qualities of liquefied natural gas has the greatest impact on the capacitance of capacitive sensors

Then, in actual use, the closer the dielectric constant of the liquefied natural gas filled in the storage tank is to the dielectric constant of the liquefied natural gas D, the closer the liquid level displayed by the liquid level detector is to the actual level in the storage tank. The liquid level, that is, the more accurate the detection result is; when the dielectric constant of the LNG filled in the storage tank deviates too much from that of the LNG D, since the full-load capacitance CA is fixed, the real-time However, the capacitance CS will change greatly with the change of LNG dielectric constant, so the above detection method cannot accurately detect the liquid level of liquefied natural gas in the storage tank, which will hinder the normal filling, transportation and maintenance of the storage tank. Use brings a lot of inconvenience

Images