Water and steam flow calculation method based on measurement of throttling device

Abstract

The invention discloses a water and steam flow calculation method based on measurement of a throttling device. The water and steam flow calculation method based on measurement of the throttling devicecomprises the steps of acquiring a throttling device front and back differential pressure signal, a throttling device front medium pressure signal and a throttling device front medium temperature signal; calculating to obtain a throttling device front and back pressure ratio; then obtaining the inner diameter of the throttling device, the inner diameter of a pipeline and the aperture ratio of thethrottling device at a working temperature; calculating to obtain the density, dynamic viscosity and isentropic index of a working medium; calculating a primary outflow coefficient by utilizing the aperture ratio of the throttling device; then obtaining the expansibility factor of the medium; further obtaining a flow measurement intermediate value and a Reynolds number intermediate value; finally, calculating to obtain an outflow coefficient; and combining the outflow coefficient, the diameter of the throttling device, the expansibility factor, the fluid density and the differential pressureof the throttling device to obtain a final flow value. By the method, accurate measurement and calculation of water and steam flow are realized, meanwhile, logic implementation is simple, and the requirements of industrial process operators to normal monitoring of a process system and accurate control and adjustment of a thermal process are met.

Description

technical field [0001] The invention belongs to the technical field of steam turbine power generation, and relates to a calculation method using a standard throttling device measurement, in particular to a water and steam flow calculation method based on the throttling device measurement. Background technique [0002] In the thermal production process of the industrial industry, the flow rate of fluid (water, steam, etc.) directly reflects the operating conditions such as equipment efficiency and load level, and some flow parameters participate in the control and adjustment of the thermal process. The differential pressure flowmeter composed of a standard throttling device and a differential pressure transmitter has been widely used in the flow measurement of industrial systems. The economic operation has a certain positive significance. [0003] The measurement principle of the standard throttling device is based on the fact that the throttling device is installed in a pip...

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Problems solved by technology

[0015] At present, the industrial production process is based on the above measurement principle, and the configuration calculation is carried out in the industrial process distributed control system (DCS). The conventional flow measurement calculation will divide the differential pressure value Δp and the density ρ of the medium under the working state from the formula (1) 1 The other parameters are simplified to an overall coefficient k, through the overall coefficient k and (The square root of the product of differential pressure and medium density) can be calculated to obtain the medium flow rate to be measured; the density ρ of the fluid in the working state 1 It is calculated by checking the enthalpy and entropy table through the actual measurement of the medium pressure and temperature, and realizes the compensation calculation when the medium parameters change. However, this calculation method cannot compensate other parameters in the formula (1) caused by the change of the medium parameters. After calculation, when the working pressure and temperature of the measured medium deviate from the original design working pressure and temperature seriously, it will cause the overall coefficient k to deviate from the original design value by more than 30% or even 50%, and the calculated medium flow accuracy Poor and unusable, which seriously affects the normal monitoring of operators and the control and adjustment of thermal process

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