Single optical fiber tracing type high precision continuous liquid level measuring method

Abstract

The preent invention relates to measurement and control technology. The end of single multiple-mode optical fiber is processed through electric arc smelting pull or optical grinding to form conic tipas sensing head, which is combined with computer controlled servo mechanism to realize the continuous liquid level measurement. The press invention features that the servo mechanism to drive the optical fiber sensing ehad consists of stepped motor, screw arbor, block and outer casing tube with guide groove; its motion direction to trace liquid surface is determined by the strength of the feedbacksignal from the sensing head and the liquid surface position is calculated from the step number of the stepped motor corresponding to the change in the feedback signal the sensing head produces whilepassing through the air-liquid interface. The method has a measurement precision within 0.1 mm in the 2 mm range, is not affected by the liquid density, has no long term drift, and may be used in thepetrochemical system.

Description

technical field [0001] The invention belongs to the technical field of measurement and control, relates to a high-precision liquid level continuous measurement method based on optical fiber frustrated total internal reflection sensing, and relates to the precise measurement and control of liquid levels in the petrochemical industry. Background technique [0002] Compared with traditional electrical sensors, optical fiber sensors have many advantages, such as high detection sensitivity, anti-electromagnetic interference and intrinsic safety, etc., and have been widely used in aerospace and petrochemical industries in recent years. At present, the continuous measurement of liquid level in the petrochemical industry mostly adopts the method of measuring pressure to convert liquid level. This method has the disadvantage that the measurement result is easily affected by the change of liquid density and the long-term drift of the sensor, and it is difficult to achieve high-precisio...

AI Technical Summary

Problems solved by technology

At present, the continuous measurement of liquid level in the petrochemical industry mostly adopts the method of measuring pressure to convert liquid level. This method has the disadvantage that the measurement result is easily affected by the change of liquid density and the long-term drift of the sensor, and it is difficult to achieve high-precision measurement.

Another method is to use optical fiber frustrated total internal reflection sensor to measure liquid level, such as patent (95231166.6) and patent (00252608.5). Although this type of sensor has high positioning accuracy, it can usually only perform discrete intermittent measurement or For fixed-point alarm or control

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