RU2359247C1 - Density metre-flow metre for liquid and gaseous media - Google Patents

Abstract

FIELD: instrument engineering; oil and gas industry.

SUBSTANCE: invention can be used in oil and gas extraction, oil processing, petrochemical and other industries. Density metre-flow metre includes loop-shaped pipe of equal section consisting of rising, horizontal and falling lines, 4 pressure samples installed correspondingly at the rising line (1^st pressure sampler), horizontal line (2^nd pressure sampler) and falling line (3^rd pressure sampler) of loop-shaped pipe and at thermometre casing of calibration liquid temperature sensor (4^th pressure sampler). The device also includes the 1^st and 2^nd pressure-difference transducers, absolute pressure sensor, working fluid temperature sensor, calibration liquid temperature sensor, pulse tubes with calibration liquid sensing pressure of working fluid and recording unit. The 1^st, 3^rd, 4^th pressure samplers and additional pressure sampler (5^th) installed at falling line of loop-shaped pipe are arranged at one level in loop lower end. The 2^nd pressure-difference transducer is connected to the 5^th and 1^st pressure sampler by means of pulse tubes. The 1^st pressure-difference transducer is connected to the 3^rd and 4^th pressure sampler. Thermometre is connected to the 2^nd pressure sampler. Liquid or gas density and flow rate is calculated from the specified expressions.

EFFECT: accuracy increase, extension of functional capabilities.

2 cl, 1 dwg

Description

The invention relates to the field of measuring parameters of a liquid or gas directly in the stream and can find application in oil and gas production, oil refining, petrochemical and other industries.

A well-known densitometer for liquids containing a vertical measuring column made in the form of two parallel pipes of the same diameter, impulse tubes with a “reference” liquid, pressure collectors located on the external bends of the upper and lower sections of the ascending and descending branches of the pipes at equal levels (utility model No. 15787, bull. No. 31, 2000).

The design drawback is the location of the impulse tubes with a “reference” fluid inside the measuring columns, therefore, at high fluid flow rates, vortexing occurs, which introduces an error in the pressure selection and, consequently, in the results of measuring fluid density.

-образную трубу, состоящую из восходящей, горизонтальной и нисходящей ветвей, три преобразователя давления, установленные соответственно на восходящей, горизонтальной и нисходящей ветвях трубы, два дифференциальных манометра и регистрирующий прибор (авт. св. СССР №1325328, бюл. №27, 23.07.1987 г.).Known densitometer for liquid media containing

-shaped pipe consisting of ascending, horizontal and descending branches, three pressure transducers mounted respectively on the ascending, horizontal and descending branches of the pipe, two differential pressure gauges and a recording device (ed. St. USSR No. 1325328, bull. No. 27, 23.07. 1987).

The disadvantage of the densitometer is the lack of automatic correction of the density of the “reference” liquid by temperature and pressure as applied to the operating conditions of the medium being measured, which affects the accuracy of measuring the density of the liquid.

-образную (петлеобразную) трубу равного сечения, состоящую из восходящей, горизонтальной и нисходящей ветвей, три отборника давления, установленные соответственно на восходящей, горизонтальной и нисходящей ветвях петлеобразной трубы, два датчика разности давления, датчик абсолютного давления, датчик температуры рабочей среды, импульсные трубки с «эталонной» жидкостью, воспринимающей давление рабочей среды непосредственно контактным методом, и регистрирующий блок. Для повышения точности измерения он снабжен дополнительным датчиком температуры «эталонной» жидкости, залитой в импульсные трубки, и дополнительным отборником давления, расположенным на корпусе для термометра. В качестве «эталонной» жидкости использована жидкость, контактирующая с рабочей средой, но не смешивающаяся с ней. Кроме того, отборники давления, установленные на восходящей, нисходящей ветвях петлеобразной трубы, и отборник давления, расположенный на корпусе для термометра, находятся на одном уровне в нижней части петли, а плотность жидкости или газообразных сред определяется соответственно по формуламKnown (utility model No. 67263, publ. 10.10.2007, bull. No. 28) densitometer of liquid or gaseous media, which is devoid of these shortcomings and contains

-shaped (loop-shaped) pipe of equal cross-section, consisting of ascending, horizontal and descending branches, three pressure selectors installed respectively on the ascending, horizontal and descending branches of the loop-shaped pipe, two pressure difference sensors, absolute pressure sensor, medium temperature sensor, impulse tubes with a “reference” fluid that perceives the pressure of the working medium directly by the contact method, and a recording unit. To increase the accuracy of measurement, it is equipped with an additional temperature sensor of the "reference" liquid, which is filled into the pulse tubes, and an additional pressure selector located on the housing for the thermometer. As a "reference" fluid used fluid in contact with the working medium, but not miscible with it. In addition, the pressure sampling devices installed on the ascending, descending branches of the loop-shaped pipe and the pressure sampling device located on the housing for the thermometer are at the same level in the lower part of the loop, and the density of the liquid or gaseous media is determined respectively by the formulas

where ρ _W , ρ _g - the density of the liquid and gas, ^kg / _m ³ , respectively

- плотность «эталонной» жидкости, приведенная к рабочим условиям, ^кг/_м ³,

- the density of the "reference" fluid, reduced to the operating conditions, ^kg / _m ³ ,

ΔP ₁ is the pressure difference between the column of the "reference" fluid and the sum of the hydrostatic pressure, the measured fluid (gas) and pressure loss on the ascending branch, Pa,

ΔP ₂ is the pressure difference between the column of the "reference" liquid and the difference of the hydrostatic column of the measured liquid (gas) and pressure losses on the descending branch, Pa,

g is the acceleration of gravity, ^m / _s ² ,

h is the distance between the upper and lower pressure sampling points, m,

h _to - the height of the compensation column "reference" fluid, m

In addition, an absolute pressure sensor, two pressure difference sensors, sensors for the temperature of the working medium and the temperature of the “reference” liquid are connected to the recording unit (Prototype).

The design drawback is the low accuracy in determining the mass flow rate due to the need to introduce corrections for the difference in readings (ΔР ₂ -ΔР ₁ ) ± ΔР when determining the mass flow rate due to the peculiarity of connecting pressure difference sensors.

The objective of the invention is to increase the accuracy of measuring the parameters of the liquid and gas and expand the functionality of the device by determining the composition of liquid two-component media, the absolute humidity of the gas and measuring the mass flow rate of liquid or gas with variable density.

This problem is solved due to the fact that in a densitometer-flowmeter of liquid or gaseous media containing a loop-shaped pipe of equal cross-section, consisting of ascending, horizontal and descending branches, three pressure selectors installed respectively on the ascending, horizontal and descending branches of the loop-shaped pipe, the first and second pressure difference sensors, absolute pressure sensor, medium temperature sensor, “reference” liquid temperature sensor, pressure sampler located on the sensor thermometer body and the temperatures of the “reference” fluid, impulse tubes with the “reference” fluid, perceiving the pressure of the working medium directly by the contact method, and a recording unit, while pressure taps mounted on the ascending, descending branches of the loop-shaped pipe and a pressure tester located on the body of the temperature sensor thermometer "Reference" fluid, located at the same level in the lower part of the loop. The device is equipped with an additional pressure sampler located at the same level as the pressure samplers installed on the descending branch of the loop-shaped pipe, the second pressure difference sensor is connected by impulse tubes with a “reference” liquid to the additional pressure sampler on the descending branch and to the pressure sampler on the ascending branch, and the first the pressure difference sensor is connected to the pressure sampler on the descending branch and to the pressure sampler located on the thermometer body connected to the upper discharge rnikom pressure on the horizontal portion of the loop, disposed symmetrically with respect to the shoulders descending and ascending branches of the loop-shaped pipe, while the density of the liquid or gas is determined respectively by the formulas

the mass flow rates of a liquid or gas are determined respectively by the formulas

and the composition of liquid two-component media (“oil-water”) and the absolute humidity of the gas are determined respectively by the formulas taken from the source (6):

- плотность «эталонной» жидкости, приведенная к рабочим условиям, ^кг/_м ³,Where

- the density of the "reference" fluid, reduced to the operating conditions, ^kg / _m ³ ,

ΔР ₁ is the upper calculated pressure drop depending on the density change under operating conditions (pressure difference between the column of the “reference” liquid and the difference in hydrostatic pressure, measured liquid (gas) and pressure losses on the descending branch, Pa),

_{ΔР 2ТР} - pressure loss _due to friction between the points of pressure selection on the descending and ascending branches of the loop-like pipe when the fluid moves, Pa,

g is the acceleration of gravity, ^m / _s ² ,

h is the distance between the upper and lower pressure sampling points, m,

h _to - the height of the compensation column "reference fluid", m,

d is the diameter of the pipeline, m,

α - correction factor, is determined by the results of the calibration of the device,

M _W - mass flow rate of liquid, kg / s,

M _g - mass flow rate of gas, kg / s,

W is the percentage of water in oil,%,

And the absolute humidity of the gas, kg / m ³ ,

ρ _in - the density of produced water, kg / m ³ is determined by laboratory data for each well,

ρ _n - the density of degassed oil, kg / m ³ is determined by laboratory data for each well,

ρ ₀ is the density of dry gas under standard conditions: T ₀ = 293.15 K,

P ₀ = 0.10325 MPa, kg / m ³ , is selected according to known tables,

T ₀ , P ₀ - standard conditions (293.15 K; 0.10325 MPa, kg / m ³ ),

P, T - pressure and temperature under operating conditions, MPa, K,

Z is the gas compressibility coefficient, is selected according to known tables,

ρ _g - gas density, measured under operating conditions, kg / m ³ ,

ρ _W - the density of the liquid, measured under operating conditions, kg / m ³ .

In the inventive densitometer, an absolute pressure sensor, two pressure difference sensors, a medium temperature sensor and a “reference” liquid temperature sensor are connected to the recording unit.

The drawing shows the inventive device.

The densitometer-flowmeter of liquid or gaseous media contains a loop-shaped pipe, consisting of ascending 1, horizontal 2 and descending 3 branches, impulse tubes 4, filled with a “reference” liquid that is directly in contact with the working medium, but not miscible with it, for example, organosilicon, which has known volume expansion and compression coefficients, four pressure sampling devices located at the same level 5-8 in the lower part of the loop, pressure sampling device 9 located on a horizontal branch at a distance h from the level of distribution zheniya lower pressure sockets. In this case, the pressure sampling device 5 is installed on the ascending branch 1, the pressure sampling devices 6 and 8 on the descending branch 3, and the pressure sampling device 7 is installed on the housing for the thermometer 10 with temperature sensor 11. Two pressure difference sensors 12 and 13 are connected to the ascending branch 1 and the descending branch 3 as follows: the "negative" chamber of the pressure difference sensor 12 is connected to the pressure sampler 5 on the ascending branch 1 by means of a pulse tube with a "reference" liquid, and the "positive" chamber of the specified sensor is connected to an additional pressure sampler I 8 on the descending branch 3, the "negative" chamber of the pressure difference sensor 13 is connected by a pulse tube to the sensor 6 on the descending branch, and the "plus" chamber of the specified sensor is connected to the pressure selector 7 on the housing for the thermometer. In the place of contact of the "reference" fluid and the working medium in the pressure tracers, mini-chambers for transmitting pressure are made.

The absolute pressure sensor 14 of the working fluid “Q” is installed in a straight section at the beginning of the ascending branch 1, and the temperature sensor of the working medium 15 is installed at the output of the descending branch 3. Pressure difference sensors 12 and 13, a thermometer 10, an absolute pressure sensor of the working medium 14 and a sensor the temperature of the working medium 15 is connected with the recording unit 16 (BOI - information processing unit), which, according to the program laid down in it, calculates the density of the working medium, its mass, composition for two-component liquid media or the absolute humidity of gaseous media and provides a visualization tool, such as a computer (not shown).

Density meter-flow meter of liquid or gaseous media works as follows.

The working fluid or gaseous medium (working medium "Q") enters the inlet of the ascending branch 1, where the absolute pressure sensor 14 measures the pressure of the working medium and passes to block 16. Next, the working medium rises along the ascending branch 1, while the pressure selector 5 transmits pressure to the pressure difference sensor 12 into its "negative" chamber, and enters the horizontal line 2, where pressure is transmitted through the pressure selector 9 to the "positive" chamber of the pressure difference sensor 13, the reading of which is transmitted to the recording unit 16. Next the working medium is lowered along the descending branch 3 and its pressure is transmitted through the pressure selector 6 to the "negative" chamber of the pressure difference sensor 13, the readings of which are sent to block 16, and the pressure of the same working medium through the pressure selector 8 enters the "positive" difference sensor chamber pressure 12. At the outlet in the descending branch, the temperature of the working medium is measured by a temperature sensor 15, the readings of which are sent to block 16.

In the measurement process, a method is used to compare the static indicators of the "reference" fluid with the changing parameters of the working medium.

The essence of the measurement is disclosed in the following example of calculating the parameters of a liquid or gaseous media.

The product works as follows.

The studied flow Q of liquid or gaseous media enters the inlet of the vertical branch and, passing through the horizontal branch and the descending branch, enters the outlet. In this case, the pressure drops ΔР ₁ on the descending branch and the pressure loss on friction _{ΔР 2ТР are measured} between the pressure take-off points on the descending and ascending branches of the pipe when the fluid moves, as well as the temperature t _{et of the} "reference" fluid in the impulse tube and the working medium in the pipeline and absolute pressure P in the pipeline. Since the upper pressure sampler 9 is located symmetrically with respect to the ascending and descending branches, and the density of the liquid (gas) is measured only on the descending branch, the values entered are 0.5ΔP _2TP , and the pressure drops ΔP ₁ and ΔP _{2TP are} determined by the following formulas:

wherein

or

откуда

where from

The pressure created by the "reference" fluid is determined by the formula

where ρ _{t et} - the density of the "reference" fluid, kg / m ³ ,

g is the acceleration of gravity, m / s ² ,

h is the distance (when measuring liquid media) between the points of "pressure selection", m,

ΔР _Ж - hydrostatic pressure of a liquid column equal to the distance h, Pa

Since the pipeline is of the same diameter (stainless steel pipe of increased accuracy), it can be assumed that the roughness coefficient on the ascending branch is approximately equal to the roughness coefficient in the descending branch (the loop is made from one section of the pipe)

Where

(see. Kremlevsky P.P. Flowmeters and counters of quantity. Reference book. L., Mechanical engineering, 1979)

here ρ _{20 et} is the density of the “reference” liquid under normal conditions (t = 20 ° C, P = 0.103 MPa);

β _t is the coefficient of volume expansion of the "reference" fluid with temperature, 1 ° C;

t is the temperature of the "reference" fluid, measured by a temperature sensor, ° C;

k _p is the volumetric compression coefficient of the "reference" fluid, 1 / MPa;

P is the absolute pressure, MPa;

β _t and k _p are taken from the state standard data system.

To select the measurement range of the gas density, it is necessary to introduce compensation of the pressure column of the "reference" liquid - h _to

;

;

,

;

;

,

then

,

,

, получаемdivide by

we get

where ΔP ₁ is the upper design pressure drop, depending on the change in density under operating conditions (pressure and temperature),

ρ _g - the gas density under standard conditions is known.

divide by gh, then

where from

or

The basis for measuring friction losses is the Bernoulli equation for a viscous fluid [3] with a constant cross-section of the pipeline

where h ₁ and h ₂ - height, m;

g is the acceleration of gravity, m / s;

ρ is the density of the liquid or gas, kg / m ³ ;

V ₁ and V ₂ - flow velocity, m / s;

α ₁ and α ₂ are the Coriolis coefficients;

P ₁ and P ₂ - pressure, Pa;

R _Tr - pressure loss on friction, Pa.

For the proposed densitometer-flowmeter, the diameter of the loop-shaped pipe is the same everywhere (stainless steel pipe of increased accuracy), therefore, the cross-sectional areas of the pipe along the entire length are the same and the speeds are the same, i.e. V ₁ = V ₂ , distances h ₁ = h ₂ , since the pressure testers are on the same level.

If the flow velocities are equal, the Coriolis coefficient α = 1,

α ₁ = α ₂ ,

then equation (17) can be written as follows:

or

From formula (18) we find the average flow rate of a viscous fluid, m / s:

Knowing the average flow rate during fluid movement, the diameter of the loop of the pipeline, the density of the liquid (gas), we can determine the mass of liquid or gas by the following formula:

Where

, в которой Q - расход жидкости или газа, м³/с.but

, in which Q is the flow rate of liquid or gas, m ³ / s.

Using the proposed product allows you to measure the density of liquid or gaseous media, to determine the amount of mass of liquid or gas and the composition of liquid two-component media, the absolute humidity of the gas and to measure the mass flow of liquid or gas with a variable density

Working drawings were developed for this product, an experimental sample was made, laboratory tests on water were carried out, positive results were obtained confirming the correctness of the calculations.

Information sources

1. Density meter for liquid media. Utility Model Certificate RU No. 15787, MKI ⁷ G01N 9/26, publ. Bull. No. 31, 2000

2. Density meter for liquid media. Auth. testimonial. USSR No. 1325328, MKI ⁴ G01N 9/26, publ. Bull. No. 27, 1987

3. Altshul A.D., Zhivotovsky L.S., Ivanov L.P. Hydraulics and aerodynamics. - M .: Stroyizdat, 1985

4. Density meter of liquid or gaseous media. Utility Model Patent RU No. 67263, IPC G01N 9/26, publ. 10/10/2007, bull. No. 28.

5. Kremlin P.P. Flow meters and quantity counters. Directory. L., "Engineering", 1979

6. Plotnikov V. M., Podreshetnikov V. A., Radkevich V. V., Teterevyatnikov L. N. Monitoring the composition and quality of natural gas. L., "The bowels", 1983

Claims (2)

1. A densitometer-flowmeter of liquid or gaseous media, containing a loop-shaped pipe of equal cross-section, consisting of ascending, horizontal and descending branches, three pressure detectors mounted respectively on the ascending, horizontal and descending branches of the loop-shaped pipe, the first and second pressure difference sensors, absolute sensor pressure, temperature sensor of the working medium, temperature sensor of the "reference" liquid, a pressure selector located on the thermometer housing of the temperature sensor of the "reference" liquid, pulse tubes with a “reference” liquid, which perceive the pressure of the working medium directly by the contact method, and a recording unit, while the pressure samples installed on the ascending, descending branches of the loop-shaped pipe and the pressure sampler located on the thermometer body of the temperature sensor of the “reference” liquid are located on one level in the lower part of the loop, characterized in that it is equipped with located on the same level with the above pressure testers additional pressure tester installed on the downward branches of the loop-like pipe, the second pressure difference sensor is connected by impulse tubes with a “reference” liquid to an additional pressure sampler on the descending branch and to the pressure sampler on the ascending branch, and the first pressure difference sensor is connected to the pressure sampler on the descending branch and to the pressure sampler located on the case of the thermometer connected to the upper pressure tester on the horizontal section of the loop, located symmetrically relative to the shoulders of the descending and ascending branches of the loop-shaped pipe, is density of the liquid or gas is determined respectively by the formulas:

,

,
and the mass flow rates of a liquid or gas are determined respectively by the formulas:

,

,
and the composition of liquid two-component media: "oil-water" and the absolute humidity of the gas are determined respectively by the formulas:

,

,
Where

- the density of the reference fluid, reduced to the operating conditions, kg / m ³ ;
ΔP ₁ - the upper design pressure drop, depending on the change in density under operating conditions, Pa;
_{ΔР 2ТР} - pressure loss _due to friction between the points of pressure selection on the descending and ascending branches of the loop-like pipe when the fluid moves, Pa;
g is the acceleration of gravity, m / s ² ;
h is the distance between the upper and lower pressure sampling points, m;
h _to - the height of the compensation column of the reference fluid, m;
d is the diameter of the pipeline, m;
α is the correction factor;
M _W - mass flow rate of liquid, kg / s;
M _g - mass flow rate of gas, kg / s;
W is the percentage of water in oil,%;
And - the absolute humidity of the gas, kg / m ³ ;
ρ _in - density of produced water, kg / m ³ ;
ρ _n - the density of degassed oil, kg / m ³ ;
ρ ₀ is the density of dry gas under standard conditions: T ₀ = 293.15 K °, P ₀ = 0.10325 MPa, kg / m ³ ;
T ₀ , P ₀ - standard conditions (293.15 K °; 0.10325 MPa, kg / m ³ );
P, T - pressure and temperature under operating conditions, MPa, K °;
Z is the gas compressibility coefficient;
ρ _g - gas density, measured under operating conditions, kg / m ³ ;
ρ _W - the density of the liquid, measured under operating conditions, kg / m ³ . 2. The density meter according to claim 1, characterized in that the absolute pressure sensor, two pressure difference sensors, a temperature sensor of the working medium and a temperature sensor of the "reference" liquid are connected to the recording unit.