SU1516790A1 - Method of determining consumption of liquid medium running through pipe-line - Google Patents

Abstract

The invention relates to instrumentation, can be used in the petroleum and other industries, associated with the measurement of the flow of liquid media transported through pipelines, and is aimed at improving the accuracy of measurements in terms of varying density. A part of the fluid is passed through a Y-shaped tube 4 installed vertically in front of the restriction device 2, the pressure drops in the ascending and descending bends of the Y-shaped tube 4 between points at the same level 5.6 and 7.8 and pressure drop on the section of the pipeline 1 between the Y-shaped tube 4 and the restriction device 2. The ratio between the indicated pressure drops is maintained in accordance with the equality given in the claims. 1 il.

Description

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The invention relates to instrumentation and can be used in the petroleum industry and other branches of the national economy, associated with the measurement of the flow of liquid media transported through pipelines.

The purpose of the invention is to improve the accuracy and efficiency of measurements under varying density conditions.

The essence of the method is as follows.

A part of the liquid is passed through an i-shaped tube installed vertically above or below the axis of the pipeline. At the same time, in the knees of the U-shaped tube, the pressures P, P, P and F are measured on the sections (ah, it became hydraulically Pu

 L (Re) -b- f -YD P

5-6

tr

 , 7 (ReJ J1 f

V 2

--ii

where Re and Re „are the Reynolds numbers in the tube and in the u-tube. Assuming that under actual operating conditions of the pipe the Reynolds number is less than 10 and to calculate D, you can use the Blasius formula, we get

 l & Sfi (L, J

 V 5 n "p

 (4-G (U)

 D

n

D

V.,

(2)

bilized flow in length N.

Measurement of pressure drops in the knees of a U-shaped tube makes it possible to determine the density of a liquid medium, and therefore, the volume - I „-„ ..

liquid mass flow rates. Measurements of pressure drops at the constriction device and density in the lJ tube are carried out in different flow sections. This fact under conditions of rapidly varying density can give an error.

. The characteristic time of passage of a fluid through an i-shaped tube (the time of fluid renewal in the tube), where 1, is the length of the U-shaped tube, and Vy is the velocity of the fluid in it.

If a particle of liquid that does not enter the u-tube moves through the tube of the measuring section, then m L T L / V, where L is the distance between the tube and the narrowing device, and V is the velocity of the fluid in the tube, comes to narrowing down1

It follows from the formulas

dPr-

mf

 uSii.tA & - ".. 2

Substituting this into (2) and using (l), 2b finally we obtain that when measuring the density of a liquid particle passing through a restriction device, the relation

thirty

AP & fe ..- i yR „

PRC

1.2 f

2 (-Lv) -.

n

 L

(3)

shit

properties. If 4 With | d c, then the density meter will give the density of the portion of liquid that passes the constriction device at the time of measurement.

Thus, it is necessary to respect the ratios

45

L

 v

LV /

V b ... or --- --- (1)

We now find the ratio between the velocities V and Vy. Pressure drops

from the friction at lengths L in the tube and H in the u-tube can be written as

The drawing shows a diagram of an apparatus for carrying out the method.

Pipeline 1 has a tapering device 2 with a differential pressure gauge 3. Pipeline 1 is simultaneously connected with a vertical U-shaped tube between pressure sensors 5–8 and a regulating valve 9. Between the connection points of the U-shaped tube on Pipeline 1 has a flow divider 10. Pressure sensors 5-6 are connected to differential pressure gauge 11 by connecting lines 12, and pressure sensors 7 and 8 are connected to differential pressure gauge 13 by connecting 5Q lines. Between the flow divider 10 and the restriction device 2 on the pipeline 1, pressure sensors 14 and 15 are connected by connecting lines 16 to a differential pressure gauge 17.

When the device is operated, the liquid is transferred through the pipeline 1 and passes through the flow divider 10 through the stabilized flow section of length L

55

 L (Re) -F-Y

 , 7 (ReJ J1 f

V 2

--ii

where Re and Re „are the Reynolds numbers in the tube and in the u-tube. Assuming that under actual operating conditions of the pipe the Reynolds number is less than 10 and to calculate D, you can use the Blasius formula, we get

(L, J

V 5 n

Y (y)

 D

V.,

(2)

15

20

It follows from the formulas

dPr-

mf

 uSii.tA & - ".. 2

Substituting this into (2) and using (l), 2b finally we obtain that when measuring the density of a liquid particle passing through a restriction device, the relation

0

AP & fe ..- i yR „

PRC

1.2 f

2 (-Lv) -.

n

 L

(3)

51

and narrowing (its device 2. The differential pressure P on the restricting device 2 is measured by a differential pressure gauge 3. With the help of sensors I t and 15 differential pressure gauge 17, the differential pressure and Pmt are measured in the stabilized flow section of length L. Due to the differential pressure on the flow divider 10, a part of the liquid medium enters the bend of the U-shaped tube, passes it and again enters the pipeline 1 behind the flow divider 1P. At the same time, using sensors 5.6 and 7.8 of pressure and differential pressure gauges 11 and 13, respectively, the pressure drops and Pj-., and sections of the stabilized flow of length I. The calculation of the flow is carried out according to the measured equation in the formula of the invention. The required ratio (3) between the pressure drops is set using the control valve 9 When the flow rate of the liquid medium changes, the pressure drop across the divider 10, and consequently, on the U-shaped tube, changes in proportion to y2 | - ,,. L j the velocity of the medium in the pipeline 1, correspondingly square

CKopocTii y varies nponoininoо

pressure drop on a 1 - tube. Thus, when measuring rs, the ratio is (dP .. + P) / lR. will remain constant.

Claims (1)

Invention Formula The method for determining the flow of a liquid medium; flowing through the pipeline, which consists in measuring the pyrel-h / pressure on the constriction device and the density, which is also distinguished by the fact that, in order to increase the intensity and efficiency of measurements under conditions of varying density, a part of the fluid is passed through an i-shaped tube installed vertically in front of the narrowing tube (with its device, pressure drops in the ascending and descending knees of the U-shaped tube between points at the same level and the drop in gauge 16790 are measured nor in the pipeline section between the i-shaped tube and the constriction device, while maintaining the ratio between the pressure drops in the lenses of the i-shaped tube and in the pipeline section in accordance with the equality ..1AR / .. 2 (.1е) .н. (.5.} F l D t t j and R. t L and the volumetric and mass flow rates are calculated using the formulas ts where uPf and L Ru are pressure drops in the ascending and descending knees of the i-shaped tube; 25 thirty 35 40 45 50 D is the pressure drop over the pipeline section between the i-tube and the restriction device; Ly is the length of the i-shaped. -1 tube; L is the length of the section between the i-shaped tube and narrowing device; H is the length of the i-tube between the pressure points; d is the diameter of the U-shaped tube; D is the diameter of the pipeline; o (. - coefficient of consumption of the restriction device; f. - the area of its passage section; L P - pressure drop across the device; g - free fall acceleration.