Method for determining volume of deposits in straight pipeline

Abstract

FIELD: pipelines.SUBSTANCE: maintenance and operation of external main and distribution pipelines of circular cross-section. It can be used in heat supply, water supply and oil supply to determine the actual dimensions of the pipeline cross-section under operating conditions. The method for determining the volume of deposits in a straight pipeline is based on the inverse relationship between the internal diameter of the pipeline and friction pressure losses. In a straight pipeline, a flow meter measures the volumetric flow rate of moving dropping liquid. In the case of a steady turbulent flow of a dropping liquid, the pressure loss due to friction is determined by the difference in the readings of the pressure gauges installed at the beginning and end of the straight pipeline, respectively. The temperature of the dropping liquid, required to find the density and kinematic viscosity of the dropping liquid according to reference data, is measured with a thermometer. The given internal diameter of a straight pipeline with deposits on the internal surface is calculated using a mathematical expression. Based on the known values of the internal diameter of a straight pipeline with and without deposits on the internal surface, the volume of deposits in the pipeline is calculated using a mathematical expression.EFFECT: increase of the accuracy and reliability of determining the volume of deposits on the inner surface of a straight pipeline using devices designed to measure the volumetric flow rate, the difference in excess static pressures and the temperature of a moving dropping liquid.1 cl, 2 dwg

Description

[0001] The invention relates to the maintenance and operation of external circular main and distribution pipelines. It can be used in heat, water, and oil supply to determine the actual cross-sectional dimensions of a pipeline under operating conditions.

[0002] A known method for determining the volume of deposits in a pipeline consists of installing two pressure sensors at the beginning and end of the pipeline, respectively, to determine pressure losses due to friction (RU No. 2816953, IPC F17D 3 / 00, publication date 08.04.2024). A highly viscous liquid is pumped into the pipeline using a mobile pump unit. The viscosity of the injected liquid differs from that of the liquid in the pipeline with a constant volumetric flow rate under turbulent flow conditions. The time it takes for the pipeline cavity between the pressure sensors to fill with the injected liquid is then recorded. The volume of deposits in the pipeline is calculated using the following mathematical expression (original designations and the author's explanations of physical quantities are provided):

[0003] , , (1)

[0004] where - average internal diameter of the pipeline along its length, ;

[0005] - pipeline length, ;

[0006] - the volume of high-viscosity liquid pumped into the pipeline, , numerically equal to the product of the volumetric flow rate of the liquid and the time it takes to fill the space of the pipeline between the pressure sensors.

[0007] The disadvantage of this method is the need to use a highly viscous fluid, which differs in its physical properties from the fluid moving in the pipeline. With a significant volume of highly viscous fluid injected into large diameter and long pipelines, high-performance pumping units will be required. Ensuring complete equality of volumetric flow rates between the highly viscous fluid and the fluid moving in the pipeline, thereby eliminating possible diffusion processes between the two different substances, is a technological challenge.

[0008] The closest to the claimed invention is a method for quantitative diagnostics of deposits in a pipeline, which consists of moving a liquid separator along the pipeline and recording the pressure at the beginning and end of the pipeline using pressure sensors (RU No. 2728011, IPC F17D 3 / 00, E21B 47 / 003, publication date 07 / 28 / 2020). A high-viscosity liquid of such a volume is used as a liquid separator that it ensures that the pressure sensors record the passage of this liquid by increasing the pressure by the required amount. The time it takes for the high-viscosity liquid to pass through the pipeline is estimated based on the points on the pressure change graph at the locations of the pressure sensors, where an increase in pressure is observed due to the appearance of the high-viscosity liquid. The required volume of the high-viscosity liquid in the pipeline is calculated using a mathematical expression (original designations and the author's explanations of the physical quantities are provided):

[0009] , , (2)

[0010] where - internal diameter of clean pipeline, ;

[0011] - an increase in pressure on pressure sensors (pressure gauges) after a highly viscous liquid passes through their zone, ;

[0012] And - coefficients of hydraulic resistance, respectively, during the movement of pipeline and high-viscosity liquid;

[0013] - the speed of movement of highly viscous liquid through the pipeline, ;

[0014] - average density of liquid in the pipeline, .

[0015] The volume of deposits in the pipeline is calculated using a mathematical expression (original designations and author’s explanations of physical quantities are provided):

[0016] , , (3)

[0017] where - the length of the pipeline between two pressure gauges (pressure sensors), ;

[0018] - the flow rate of liquid through the pipeline is maintained at a constant value during the assessment of the volume of deposits, ;

[0019] - the chronological time of the first increase in pressure in the area of ​​the pressure gauge installed at the beginning of the pipeline due to the passage of the liquid separator, ;

[0020] - the chronological time of pressure increase in the area of ​​the pressure gauge installed at the end of the pipeline due to the passage of the liquid separator, .

[0021] The disadvantage of this method is the need to additionally use a highly viscous liquid as a liquid separator, which has different physical properties from the pipeline fluid. Recording the pressure increase at the end of the pipeline requires high-precision pressure sensors and a time period whose length depends on the velocity of the liquid separator within the pipeline. In the case of a long pipeline and a relatively low velocity of the liquid separator, it will take a significant amount of time to register the pressure increase at the end of the pipeline.

[0022] The technical result of the invention is to increase the accuracy and reliability of determining the volume of deposits on the inner surface of a straight pipeline using devices designed to measure the volumetric flow rate, the difference in excess static pressures and the temperature of a moving liquid droplet.

[0023] The technical result is achieved in that in the method for determining the volume of deposits in a straight pipeline, including placing pressure sensors at the beginning and end of a pipeline with a known internal diameter and length, measuring the volumetric flow rate of liquid in the pipeline, recording the pressure of the liquid at the beginning and end of the pipeline, according to the invention, a drip liquid is used as the liquid, pressure gauges measure the excess static pressure of the moving drip liquid at the beginning and end of a straight pipeline with deposits on the inner surface in order to determine pressure losses due to friction, a thermometer measures the temperature of the drip liquid, the reduced internal diameter of the straight pipeline with deposits on the inner surface is calculated using a mathematical expression:

[0024] ,(4)

[0025] where - volumetric flow rate of moving droplet liquid, ;

[0026] - the given internal diameter of a straight pipeline with deposits on the internal surface, ;

[0027] And - excess static pressure of the dripping liquid at the beginning and end of a straight pipeline with deposits on the inner surface, respectively, ;

[0028] - temperature of the dropping liquid, ;

[0029] - density of the liquid drop, ;

[0030] - length of a straight pipeline, ;

[0031] - equivalent roughness of a straight pipeline with deposits on the inner surface, ;

[0032] - kinematic viscosity of the dropping liquid, .

[0033] The volume of deposits on the inner surface of a straight pipeline is calculated using the mathematical expression:

[0034] , , (5)

[0035] where - the internal diameter of a straight pipeline without deposits on the internal surface, .

[0036] The invention is explained graphically (Fig. 1 - 2).

[0037] Figure 1 shows a longitudinal section of a straight pipeline of circular cross-section with deposits on the inner surface and moving droplet liquid, where 1 is a straight pipeline; 2 is deposits; 3 is droplet liquid; 4 is a flow meter; 5 is pressure gauges; 6 is a thermometer; - the internal diameter of a straight pipeline 1 without deposits 2 on the internal surface; - the given internal diameter of a straight pipeline 1 with deposits 2 on the internal surface; - length of straight pipeline 1; - volumetric flow rate of moving droplet liquid 3 in a straight pipeline 1; And - excess static pressure of the dripping liquid 3, respectively, at the beginning and at the end of the straight pipeline 1 with deposits 2 on the inner surface; - temperature of the droplet liquid 3 in the straight pipeline 1.

[0038] Figure 2 shows the solution of the mathematical expression (4) using the graph-analytical method, where - the given internal diameter of a straight pipeline with deposits on the internal surface.

[0039] According to Figure 1, in a straight pipeline 1 with deposits 2 on the inner surface there is a moving droplet liquid 3. The inner diameter of the straight pipeline 1 without deposits 2 is The given internal diameter of a straight pipeline 1 with deposits 2 is equal to The length of a straight pipeline 1 is equal to A flow meter 4 is installed on the straight pipeline 1 to measure the volumetric flow rate. moving droplet liquid 3. At the beginning and at the end of the straight pipeline 1 there are pressure gauges 5 for measuring the excess static pressure, respectively And dripping liquid 3. A thermometer 6 is installed in the upper part of the straight pipeline 1 to measure the temperature liquid drop 3.

[0040] The volume of deposits in a straight pipeline is determined in the following sequence (Fig. 1):

[0041] 1. In a straight pipeline 1, the volumetric flow rate is measured by a flow meter 4 moving droplet liquid 3.

[0042] 2. In a straight pipeline 1, the excess static pressure is measured with pressure gauges 5 And moving droplet liquid 3.

[0043] 3. In a straight pipeline 1, thermometer 6 measures the temperature moving droplet liquid 3.

[0044] 4. Using reference data, find the density and kinematic viscosity of the liquid droplet 3 depending on the temperature .

[0045] 5. Using the mathematical expression (4), calculate the reduced internal diameter straight pipeline 1 with deposits 2 of known length .

[0046] 6. Using mathematical expression (5), calculate the volume of deposits 2 in a straight pipeline 1 with a known internal diameter. straight pipeline 1 without deposits 2 on the inner surface.

[0047] An example of a specific implementation of the method.

[0048] Let's determine the volume of deposits on the inner surface of the supply pipeline of the centralized heating system.

[0049] The initial data according to the mathematical expressions (4) and (5) are as follows:

[0050] 1. Inner diameter of pipeline ( ).

[0051] 2. Total pipeline length .

[0052] 3. Drop liquid - water.

[0053] 4. Volumetric water flow rate as indicated by the flow meter .

[0054] 5. Excess static water pressure at the beginning of the pipeline as indicated by the pressure gauge ( ).

[0055] 6. Excess static water pressure at the end of the pipeline as indicated by the pressure gauge ( ).

[0056] 7. Water temperature in the pipeline according to the thermometer reading .

[0057] 8. At temperature the density and kinematic viscosity of water, according to reference data, are respectively equal to And .

[0058] 9. The equivalent roughness of a straight pipeline with deposits on the inner surface is taken to be equal to .

[0059] According to Figure 2, the given internal diameter of a straight pipeline with deposits on the internal surface ( ).

[0060] Taking into account the initial and calculated data, the volume of deposits on the inner surface of a straight pipeline according to the mathematical expression (5) was:

[0061] .

[0062] The proposed method has the following advantages:

[0063] 1. Can be implemented under operating conditions, as it does not require disconnecting the sectioned section or connecting any additional measuring instruments that would disrupt the established movement of the droplet liquid.

[0064] 2. It is possible to use a portable flow meter to measure the volumetric flow rate of moving droplet liquid in a pipeline.

[0065] 3. Pressure gauges and thermometers or embedded structures for them can be located directly on the pipeline throughout the entire operating period.

[0066] 4. Does not require the use of high-viscosity liquids.

[0067] 5. It has a wide range of applications, including determining the deposit volume in the pipeline in which the dropping liquid is water or oil.

[0068] 6. Based on well-known laws of hydraulics: the Darcy-Weisbach equation, designed to determine pressure losses due to friction in a pipeline during developed turbulent flow of an incompressible fluid, and the Colebrook-White equation, designed to determine the hydraulic resistance coefficient in the zone of turbulent fluid flow in rough pipelines.

Claims

A method for determining the volume of deposits in a straight pipeline, which includes placing pressure sensors at the beginning and end of a pipeline with a known internal diameter and length, measuring the volumetric flow rate of liquid in the pipeline, recording the pressure of the liquid at the beginning and end of the pipeline, characterized in that a drip liquid is used as the liquid, manometers are used to measure the excess static pressure of the moving drip liquid at the beginning and end of the straight pipeline with deposits on the internal surface in order to determine pressure losses due to friction, a thermometer is used to measure the temperature of the drip liquid, the reduced internal diameter of the straight pipeline with deposits on the internal surface is calculated using the mathematical expression: , Where – volumetric flow rate of moving droplet liquid, ; – the given internal diameter of a straight pipeline with deposits on the internal surface, ; And – excess static pressure of the liquid droplet at the beginning and end of a straight pipeline with deposits on the inner surface, respectively, ; – temperature of the dropping liquid, ; – density of the liquid drop, ; – length of a straight pipeline, ; – equivalent roughness of a straight pipeline with deposits on the inner surface, ; – kinematic viscosity of the dropping liquid, , the volume of deposits on the inner surface of a straight pipeline is calculated using the mathematical expression: , , Where – the internal diameter of a straight pipeline without deposits on the internal surface, .

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