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The main test content and technical key of the steam flow standard device

(1) Measurement accuracy of electromagnetic flowmeter of measurement assurance system
The function of the condenser is to change the two-phase flow into a single-phase flow, that is, to change the gas-water mixture to condensed water. Errors may occur due to unstable heat transfer conditions. With regard to the determination of the scope of stability, how to maintain stability, etc., practical experiments and research are required.
Water flow standard devices use dynamic or static mass methods.
(2) Characteristics of sonic nozzles or venturi nozzles
The two-phase critical flow has a thermal imbalance of the fluid, and there is mass, momentum and heat transfer between the two-phase medium phase interfaces. Therefore, the characteristics of a sonic nozzle operating in a two-phase flow are much more complicated than a single-phase flow. The sonic nozzle is the main component of the device, and it is used as a flow standard for routine calibration of electromagnetic flowmeters. Furthermore, the sonic nozzle can be used as a standard vapor flow meter in the secondary flow standard device, so its characteristics should be explored in depth.
(three) orifice dryness meter
The mass flow rate of the differential pressure flow meter is a function of differential pressure and dryness, so it can be used to detect the dryness of the fluid in the pipeline. Since there are two unknowns (mass flow and dryness) in the flow equation, there must be two flow equations to solve. It can be solved by the flow equation of the superheated steam submersible electromagnetic flowmeter or sonic nozzle. The characteristics are related to the geometry of the flow device, the state parameters of the fluid medium, and the flow range. It is necessary to conduct experimental research on the specific conditions of each pipeline to improve the accuracy of the calculation.
(4) Superheated steam flowmeter
At higher flow rates, due to the limitations of the condenser cooling system capacity, the front superheated vapor flow meter is required as the flow standard. Increasing the metering accuracy can be calibrated individually using a condensing weighing system, or the entire set of throttling devices can be calibrated on the water unit. For the automatic correction of the rapidly changing fluid medium working state (pressure, temperature), the microcomputer can be used for instantaneous value display correction and timing accumulation.
The superheated steam flow meter is a flow meter working on single-phase medium, and has mature experience to be utilized. The problem is that practical measures must be taken to ensure the stability and improvement of the metering accuracy of the device.
(5) The work of the pressure regulation system
Whether the flow stability affects the measurement accuracy of instantaneous flow, it is necessary to explore the method to improve the flow stability. The instability of the gas source will affect the measurement accuracy of the system. Therefore, it is absolutely necessary to establish a high-precision adjustment system.
(6) Dryness adjustment system
The method used is to adjust the water addition site and water temperature, and change the water baking into the mixer to adjust the dryness of the fluid.

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