Application of pressure calibrator in the application of gas-liquid two-phase medium

In recent years, the adoption of ion-membrane method in the chemical industry in China has developed rapidly. The pressure calibrators were mostly imported in the past few years, including various on-line instruments. Now from the device to the instrument gradually localized, this can not only guarantee quality, but also can save a lot of foreign exchange.

A large-scale chemical plant in northwestern China discovered that the two float flowmeters installed on the cathode and anode bipolar pipes did not work properly during the trial production stage. The pressure calibrator pointer was always swinging and could not be read. The output current signal was also unstable. Realize the expected process adjustment and control objectives, and even affect the normal production. After on-site observation and analysis, the measured medium in the cathode and anode pipelines of the pressure calibrator is a non-uniform, proportional and non-fixed gas and liquid dual-phase medium; while the flowmeter is a conventional float flowmeter. .

One of the working principles of the metal tube float flow meter is the buoyancy law. The pressure calibrator is related to the density of the measured medium. When the density is unstable, the float will jump. Due to the fact that the fluid is accompanied by an indeterminate amount of gas, a pulsating flow is generated, resulting in the above phenomenon of the flow meter.

At present, all kinds of conventional flowmeters are not suitable for gas and liquid two-phase media. The flow rate of salt and alkali liquor in the process of pressure calibrators must be measured and controlled. That is, the flowmeter must be installed. Therefore, the use of an available flow meter or the improvement of an existing flow meter to meet the measurement requirements of this specific working condition becomes the next step.

The selection and determination of the implementation plan must meet at least the following 3 points:

(1) The wetted parts of the pressure calibrator must be able to withstand the strong oxidation and corrosion of the chlorine-containing salt solution and alkaline solution in the cathode and anode bipolar pipes;

(2) Pressure calibrator installation and connection dimensions should be the same as the original flow meter to reduce the workload;

(3) The pressure calibrator can effectively buffer and reduce the violent fluctuations caused by the random gas generation, achieve a reading that can be regarded as a stable value, and the fluctuation of the output current signal meets the requirements of the regulation system.

According to the above requirements, pressure calibrators, electromagnetic flow meters, turbine flow meters, vortex flow meters, float flow meters, and differential pressure flow meters were analyzed and compared. After that, it was considered that only necessary improvements were made to the metal tube float flow meters. It is feasible and the best solution. Therefore, Huai'an Central Control Automation Instrument Co., Ltd. has specially designed a pressure calibrator on the basis of its original product.

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