Calculation method for judging blocking position of natural gas pipeline

Abstract

The invention belongs to the technical field of natural gas extraction and transportation, and provides a calculation method for judging the blockage position of a natural gas pipeline. The method comprises the following steps: acquiring a pipeline pressure rise curve caused by blockage to obtain pressure rise starting time and temperature; obtaining the amount of existing methane substances in the pipeline at the initial moment of pressure rise caused by blockage; the amount of methane substances injected into the pipeline and leaked from the pipeline is obtained, and the pore volume from the pipeline inlet to the blockage position is calculated according to the blockage pressure rise; dividing the calculated volume by the sectional area of the pipeline to obtain a blockage position, and calculating an error value through a predicted pressure curve. According to the quantitative calculation method, the blockage position is obtained through the pressure change of the pipeline after the pipeline is blocked, the previous method for checking the blockage position in a segmented manner is changed, the judgment of the blockage position of the pipeline is quantified, and blockage removal of the natural gas pipeline is guided by calculating the blockage position, so that the work of testing by using various instruments and equipment and the like is reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of natural gas extraction and transportation, and relates to a calculation method for determining a blockage position of a natural gas pipeline. Background Art

[0002] my country is a major natural gas consumer, importing large quantities of natural gas annually via pipelines, exemplified by the China-Russia natural gas pipeline project. However, during natural gas transportation, pipeline blockages can occur due to condensation of water vapor in low-temperature environments, accumulation of impurities during transportation, and condensation of liquid hydrocarbons and condensate. Pipeline blockages significantly impact the extraction and transportation of natural gas. The resulting pressure surge can cause overpressure damage to pipelines, valves, pressure regulators, and other equipment, and even lead to pipeline rupture. However, current domestic blockage detection methods are still in the preliminary analysis stage, using methods such as pressure monitoring, flow analysis, and acoustic detection. The location of pipeline blockages is significantly affected by factors such as blockage type, pipeline curvature, and pipeline distance, leading to continued improvement in accuracy, cost-effectiveness, and real-time performance.

[0003] Aiming at the current problem of natural gas pipeline blockage, the present invention proposes a calculation method for determining the location of natural gas pipeline blockage. Summary of the Invention

[0004] The present invention addresses the problem of blockage during natural gas transportation. It quantitatively calculates the location of pipeline blockage through pipeline pressure changes, measures and records the pressure change at the pipeline inlet after blockage occurs through a pressure sensor at the pipeline inlet, measures and records the temperature change at the pipeline inlet after blockage occurs through a temperature sensor at the pipeline inlet, and measures and records the amount of natural gas substances leaked from the pipeline after blockage occurs through a flow meter at the pipeline outlet, thereby providing a location basis for clearing pipeline blockage.

[0005] The technical solution of the present invention:

[0006] The calculation method for determining the location of natural gas pipeline blockage is as follows:

[0007] S1. After the natural gas pipeline is blocked, the pressure at the inlet of the natural gas pipeline continues to rise. The actual pressure increase curve of the natural gas pipeline caused by the blockage is obtained. The initial pressure P1 and temperature T1 of the pressure increase curve are obtained. The real-time pressure P t and real-time temperature T t , obtain the pressure P2 and temperature T2 at the end of the force rise curve;

[0008] S2. Obtain the existing methane density in the natural gas pipeline at the initial moment of pressure increase caused by natural gas pipeline blockage. According to the initial pressure P1 and temperature T1 in the pressure rise curve obtained by S1, the methane density at the pipeline inlet to the natural gas pipeline blockage position at the initial moment of natural gas pipeline blockage is obtained. The expression is as follows:

[0009] (1)

[0010] Determine the distance between the natural gas pipeline blockage location and the pipeline inlet The volume of the pipeline between the natural gas pipeline inlet and the location of the natural gas pipeline blockage The relationship is as follows:

[0011] (2)

[0012] Where r is the cross-sectional radius of the natural gas pipeline, is the porosity in the natural gas pipeline;

[0013] Obtain the methane mass between the pipeline inlet and the natural gas pipeline blockage location at the initial moment of natural gas pipeline blockage The expression is as follows:

[0014] (3)

[0015] S3. Obtain the amount of methane injected into the natural gas pipeline and leaked from the natural gas pipeline. Calculate the pore volume from the natural gas pipeline inlet to the location of the natural gas pipeline blockage based on the pressure increase of the natural gas pipeline blockage. Obtain the amount of methane flowing into the natural gas pipeline in real time during the pressure increase phase using the natural gas pipeline inlet flowmeter. The amount of methane leaked from the natural gas pipeline in real time during the pressure increase phase is obtained through the natural gas pipeline outlet flow meter. , and then obtain the real-time methane density from the natural gas pipeline inlet to the natural gas pipeline blockage position during the pressure increase stage The expression is:

[0016] (4)

[0017] Where, is the molar mass of methane; The methane density at all times from the natural gas pipeline inlet to the blockage position during the entire pressure increase stage, including the methane density at the initial moment and the methane density at the end ;

[0018] Substituting the temperature T2 and the pressure P2 at the end of the pressure rise phase into formula (5) yields the methane density at the end of the pressure rise phase: , the formula is:

[0019] (5)

[0020] Then Substitute into formula (4) to calculate the pipeline volume between the natural gas pipeline inlet and the natural gas pipeline blockage location , according to the calculated pipeline volume between the natural gas pipeline inlet and the natural gas pipeline blockage location Substitute into formula (2) to get the distance from the blocked position of the natural gas pipeline to the pipeline inlet: ;

[0021] S4. Obtain the prediction error of the blockage position; calculate the pipeline volume between the natural gas pipeline inlet and the natural gas pipeline blockage position Substituting into formula (4) we can get the real-time methane density between the pipeline inlet and the natural gas pipeline blockage position during the pressure increase stage: ,Will Real-time temperature T during pressure increase t Substitute into formula (6) to calculate the real-time predicted pressure in the pressure increase stage , the formula is:

[0022] (6)

[0023] The pressure rise prediction curve of the natural gas pipeline blockage stage is drawn based on the predicted pressure corresponding to different time points in the pressure rise stage obtained by calculation, and the actual pressure in the pressure rise stage obtained by measurement is The actual pressure rise curve is drawn, and the calculation error of the blockage position is obtained by comparing the pressure rise prediction curve with the actual pressure rise curve. The error calculation formula is:

[0024] (7)

[0025] Where, To record the number of data points;

[0026] Determine the location of natural gas pipeline blockage based on error Calculation errors are eliminated and targeted blockage clearing operations are carried out.

[0027] Beneficial effects of the present invention: The quantitative calculation method of the present invention obtains the blockage position through the change of pipeline pressure after pipeline blockage occurs, which changes the previous method of segmented inspection of the blockage position, makes the judgment of the pipeline blockage position quantitative, and guides the clearing of natural gas pipeline blockage by calculating the blockage position, thereby reducing the use of various instruments and equipment for testing.

[0028] Based on the calculated blockage position L, the pipeline blockage clearing operation is quickly carried out, which avoids the use of complex blockage position determination equipment and prevents multiple damage to the transportation pipeline, and quickly and accurately finds the blockage position. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a schematic diagram of natural gas pipeline blockage of the present invention.

[0030] Figure 2 This is a graph of pressure changes when the pipeline is blocked.

[0031] Figure 3 It is a calculation flow chart of the present invention.

[0032] Figure 4 It is a graph of the amount of methane flowing into the pipeline in real time during the pressure increase stage.

[0033] Figure 5 This is the calculation result diagram of the pressure rise curve.

[0034] In the figure: 1 is the natural gas transportation pipeline; 2 is the inlet flow meter; 3 is the pressure sensor; 4 is the temperature sensor; 5 is the outlet flow meter. DETAILED DESCRIPTION

[0035] The specific implementation of the present invention is further described below in conjunction with the technical solutions and drawings.

[0036] The present invention provides a new calculation method for determining the location of a natural gas pipeline blockage, the specific steps of which are as follows:

[0037] Step 1: Analyze the pressure change trend of the pipeline inlet and determine that the inlet pressure continues to rise. After blockage occurs, intercept the pressure rise curve and obtain the initial pressure P1 of 6.0 MPa and temperature T1 of 274.26 K in the pressure rise curve. Obtain the pressure P2 of 12.1 MPa and temperature T2 of 274.53 K at the end of the pressure rise curve.

[0038] Step 2: Substitute the pressure P1 and temperature T1 at the initial moment of the pressure rise curve into the formula to obtain the methane density from the pipeline inlet to the pipeline blockage position at the initial moment of blockage :

[0039] 49.21 kg / m 3

[0040] Furthermore, the distance between the pipe blockage position and the pipe inlet is used to Expresses the volume of the pipe from the pipe inlet to the blockage location , the pipe cross-section radius r is 2.5 cm:

[0041]

[0042] Furthermore, the methane mass between the pipeline inlet and the pipeline blockage position at the initial moment of blockage is obtained. expression:

[0043]

[0044] Step 3: Obtain the amount of methane flowing into the pipeline in real time during the pressure increase stage through the inlet flow meter The amount of methane material leaked from the pipeline in real time during the pressure increase phase is obtained through the outlet flow meter , due to the blockage, .

[0045] Furthermore, the real-time methane density from the pipeline inlet to the pipeline blockage position during the pressure increase stage is obtained. The expression is:

[0046]

[0047] Furthermore, the pressure P2 and temperature T2 at the end of the pressure increase phase are combined Substitute the expression into the calculation to get the pipe volume from the pipe inlet to the blockage location :

[0048]

[0049] 127 cm 3

[0050] Furthermore, according to the volume of the pipeline between the pipeline inlet and the blockage position Calculate the distance from the pipe blockage location to the pipe inlet In this experiment, the porosity is 0.346:

[0051] L 18.68 cm

[0052] The calculated volume The distance from the pipe blockage position to the pipe inlet is calculated by formula (2): .

[0053] Step 4: The calculated volume of the natural gas pipeline between the inlet and the location of the natural gas pipeline blockage is Substituting into formula (4) we can get the real-time methane density between the pipeline inlet and the natural gas pipeline blockage position during the pressure increase stage: ,Will Real-time temperature T during pressure increase t Substitute into formula (6) to calculate the real-time predicted pressure in the pressure increase stage , and calculate the real-time predicted pressure The actual pressure increase The error AARE:

[0054]

[0055] In the formula The number of recorded data points.

[0056] The blockage error of the obtained blockage position is 1.1%.

[0057] The above embodiment is one specific implementation of the present invention. Common changes and substitutions made by those skilled in the art within the scope of this technology should be included in the protection scope of the present invention.

Claims

1. A calculation method for determining the location of a natural gas pipeline blockage, characterized in that: Here are the steps: S1. After the natural gas pipeline is blocked, the pressure at the inlet of the natural gas pipeline continues to rise. The actual pressure increase curve of the natural gas pipeline caused by the blockage is obtained. The initial pressure P1 and temperature T1 of the pressure increase curve are obtained. The real-time pressure P t and real-time temperature T t , obtain the pressure P2 and temperature T2 at the end of the force rise curve; S2. Obtain the existing methane density in the natural gas pipeline at the initial moment of pressure increase caused by natural gas pipeline blockage. According to the initial pressure P1 and temperature T1 in the pressure rise curve obtained by S1, the methane density at the pipeline inlet to the natural gas pipeline blockage position at the initial moment of natural gas pipeline blockage is obtained. The expression is as follows: (1) Determine the distance between the natural gas pipeline blockage location and the pipeline inlet The volume of the pipeline between the natural gas pipeline inlet and the location of the natural gas pipeline blockage The relationship is as follows: (2) Where r is the cross-sectional radius of the natural gas pipeline, is the porosity in the natural gas pipeline; Obtain the methane mass between the pipeline inlet and the natural gas pipeline blockage location at the initial moment of natural gas pipeline blockage The expression is as follows: (3) S3. Obtain the amount of methane injected into the natural gas pipeline and leaked from the natural gas pipeline. Calculate the pore volume from the natural gas pipeline inlet to the location of the natural gas pipeline blockage based on the pressure increase of the natural gas pipeline blockage. Obtain the amount of methane flowing into the natural gas pipeline in real time during the pressure increase phase using the natural gas pipeline inlet flowmeter. The amount of methane leaked from the natural gas pipeline in real time during the pressure increase phase is obtained through the natural gas pipeline outlet flow meter. , and then obtain the real-time methane density from the natural gas pipeline inlet to the natural gas pipeline blockage position during the pressure increase stage The expression of is: (4) Where, is the molar mass of methane; The methane density at all times from the natural gas pipeline inlet to the blockage position during the entire pressure increase stage, including the methane density at the initial moment and the methane density at the end ; Substituting the temperature T2 and the pressure P2 at the end of the pressure rise phase into formula (5) yields the methane density at the end of the pressure rise phase: , the formula is: (5) Then Substitute into formula (4) to calculate the pipeline volume between the natural gas pipeline inlet and the natural gas pipeline blockage location , according to the calculated pipeline volume between the natural gas pipeline inlet and the natural gas pipeline blockage location Substitute into formula (2) to get the distance from the blocked position of the natural gas pipeline to the pipeline inlet: ; S4. Obtain the prediction error of the blockage position; calculate the pipeline volume between the natural gas pipeline inlet and the natural gas pipeline blockage position Substituting into formula (4) we can get the real-time methane density between the pipeline inlet and the natural gas pipeline blockage position during the pressure increase stage: ,Will Real-time temperature T during pressure increase t Substitute into formula (6) to calculate the real-time predicted pressure in the pressure increase stage , the formula is: (6) The pressure rise prediction curve of the natural gas pipeline blockage stage is drawn based on the predicted pressure corresponding to different time points in the pressure rise stage obtained by calculation, and the actual pressure in the pressure rise stage obtained by measurement is The actual pressure rise curve is drawn, and the calculation error of the blockage position is obtained by comparing the pressure rise prediction curve with the actual pressure rise curve. The error calculation formula is: (7) Where, To record the number of data points; Determine the location of natural gas pipeline blockage based on error Calculation errors are eliminated and targeted blockage clearing operations are carried out.

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