SU678307A1 - Method and apparatus for measuring medium stationary stream flowrate - Google Patents

Description

The invention relates to a measurement technique and can be used in various fields of measurement when measuring the flow rate of compressible and incompressible media. - -. d ....... A method is known that is based on / creating and measuring the final increments of the flow rate and pressure I. It is also known a device that implements this system. 2. The increments of the pressure flow are created by briefly discharging a part of the gas from the pipeline. constituting 0.5–5% of the main flow rate. This method is only suitable for measuring gas flow and for its implementation it is necessary that the measured flow be limited to two sections with supercritical pressure drops. The method of determining the flow of gas and liquid, based on the measurement of weight, proportional to the density and velocity of the medium {3. This method is carried out with the help of variable pressure flow meters, for which it is necessary to know the internal size of the pipeline and the size of the receiving transducer. However, the solvents of the solvents elements are determined with an error and may change due to corrosion, deposition of chemical products: reactions, etc. The aim of the invention is to improve the accuracy of flow measurement with unknown dimensions of the pipeline and receiving device. This goal is achieved by performing a short-term controlled discharge from the pipeline of the working part and determining the increment of pressure drop at the receiving transducer, and the flow rate is determined according to the formula -2 where C is the coefficient taking into account the compressibility of the medium; dP is the pressure drop across the receiving transducer prior to the reset operation; DC - the flow rate of the discharged flow; ) increment of differential pressure at the receiver transducer.

gas

K - 1

; p-vmq-;

.L. , Б-Р РО М V Р / J ЧсГР J р. where K is the adiabatic index;

PC, is the total flow pressure.

For fluid fc, 1.

FIG. 1 is a schematic diagram of a device implementing the proposed method in FIG. 2 - dependence of the coefficient on relative pressure drop and adiabatic exponent. ,

The device consists of a pipeline 1, to which a relief line, a receiving converter 4 and a variable pressure differential, a pressure difference increment meter 5 and a pressure gauge B are connected to the relief valve 2 and the flow meter 3.

In order to determine the flow rate of the steady-state flow of the medium, the pressure P0 is measured with a gauge b, the differential pressure cfP is measured with a differential gauge. Then open the relief valve 2 and a part of the medium is briefly passed into the discharge line. With the postcards, the relief valve 2 measures the flow rate: on the line-DS Reset with the help of the flow meter 3 and the increment of the differential pressure d () - with the gauge 5. After that, the relief valve 2 closes and the flow rate in the pipeline is measured by formulas (1) and ( 2).

The curves shown in FIG. 2 show that it is advisable to carry out measurements with small subcritical drops on the receiving transducer (up to O, 25-0.35). For large values, the error in determining and, therefore, the flow rate increases. When the gas velocity increases to a critical one, the compressibility factor tends to k infinity. With critical and supercritical pressure drops, the flow rate no longer depends on the value of the drop and it is sufficient to determine, as proposed in formulas (1) and (2), to measure the total diving in the flow and the increment to the flow and total pressure.

The proposed method and device allow for the verification, calibration and certification of installed working flow meters and meters on the site of their operation.

without dismantling and disconnection of dimensional sections from technological or transport highways.

Claims (3)

1. A method for measuring the mass flow rate of a steady flow of a medium, based on the measurement of pressure and pressure drop occurring at The variable pressure differential pressure transducer placed in the pipeline is 6 tons per hour, so that in order to improve the measurement accuracy with unknown pipe sizes. Yes, and the receiving converter, a short-term controlled discharge from the pipeline of a part of the working medium is carried out, and the increment of the differential pressure at the receiving the converter and the flow rate are determined according to the formula. BEFORE , G-2X; A (rfP) 25 - discharge rate flow; cfP - pressure drop over the receiving converter prior to resetting part of the working environment; d (sGH) is the increment of pressure drop across the receiving transducer; - coefficient taking into account the compressibility of the medium. 2. An apparatus for carrying out the method of claim 1, comprising a variable pressure differential flow receiver and pressure and differential pressure meters, 40 and 40, which is equipped with a relief line with a valve, a flow meter on the relief line and a differential pressure increment meter connected to the differential pressure meter 45 Sources of information taken into account during the examination Part USSR author's certificate. No. 431397, cl. G 01 F 5/00, 1974, 50 2. USSR Copyright Certificate No. 431398, cl. G 01 F 5/00, 1974. . 3. Kremlin P.P. Flowmeters and counters. Quantities. L., Mechanical Engineering, 1975.  J 2 f 0.1 0.2 0.3 O.tf 0.5 fpip IPiJi 2