Method and system for determining roughness and downstream pressure of natural gas long-distance pipeline

Abstract

The invention relates to a method and system for determining the roughness and downstream pressure of a natural gas long-distance pipeline, and the method comprises the steps: obtaining the initial information of N continuous time nodes in a current pipeline roughness measurement time period; for each time node, determining a hydraulic friction resistance coefficient lambda of the target natural gas long-distance pipeline; determining an original pipeline roughness value kKe with a correction coefficient; determining a recommended pipeline roughness value k 'Ke with a correction coefficient; and obtaining a downstream predicted pressure value P2'of the target natural gas long-distance pipeline according to the recommended pipeline roughness value k 'Ke with the correction coefficient. According to the invention, the technical problem of inaccurate downstream operation pressure prediction caused by deviation between the preset fixed roughness value of the existing natural gas long-distance pipeline and the current actual roughness value can be improved.

Description

Technical Field

[0001] The present invention relates to the technical field of natural gas pipelines, and in particular to a method and system for determining the roughness and downstream pressure of a long-distance natural gas pipeline. Background Art

[0002] During the natural gas pipeline transportation process, monitoring pipeline flow, operating pressure, and real-time prediction of downstream operating pressure and abnormal pressure alarm are crucial to pipeline safety and optimized operation. Generally, the accuracy of downstream operating pressure prediction is greatly affected by pipeline roughness.

[0003] At present, the roughness of long-distance pipelines is often calculated by selecting a preset fixed absolute roughness value based on whether or not there is an inner coating. However, due to the different age and maintenance conditions of the pipelines in the natural gas pipeline network, the inner walls of most pipelines are becoming smoother and smoother as the natural gas is flushed for a long time, and the absolute roughness of the pipelines is continuously reduced; some pipelines are poorly maintained, and the absolute roughness of the pipelines increases due to corrosion and other factors. This leads to a large deviation between the actual roughness of the pipeline status and the preset fixed absolute roughness value, resulting in inaccurate pressure prediction values ​​and affecting the pressure warning effect. Summary of the invention

[0004] Aiming at the technical problem that the preset fixed roughness value of the existing natural gas long-distance pipeline deviates from the current actual roughness value, resulting in inaccurate prediction of downstream operating pressure, the present invention provides a method and system for determining the roughness and downstream pressure of a natural gas long-distance pipeline.

[0005] The technical solution of the present invention to solve the above technical problems is as follows:

[0006] In a first aspect, the present invention provides a method for determining the roughness and downstream pressure of a natural gas long-distance pipeline, comprising the following steps:

[0007] Obtain the initial information of N consecutive time nodes within the current pipeline roughness measurement period. The initial information corresponding to each time node includes the flow value q of the target natural gas long-distance pipeline. v , a starting point pressure value P1 of the calculation section of the target natural gas long-distance pipeline and an end point pressure value P2 of the calculation section of the target natural gas long-distance pipeline;

[0008] For each of the time nodes, determining the hydraulic friction coefficient λ of the target natural gas long-distance pipeline according to the initial information corresponding to the time node;

[0009] For each time node, the original pipeline roughness value kK with correction coefficient is determined according to the hydraulic friction coefficient λ corresponding to the time node. e ;

[0010] According to the N original pipeline roughness values ​​kK with correction coefficients corresponding to the current pipeline roughness measurement time period e , determine the recommended pipe roughness value k′K with correction factor e ;

[0011] According to the recommended pipeline roughness value with correction factor k′K e , and obtain the downstream predicted pressure value P2′ of the target natural gas long-distance pipeline.

[0012] The beneficial effect of the present invention is that the flow value q of the target natural gas long-distance pipeline is obtained in real time. v , the pressure value P1 at the start of the long-distance pipeline calculation section, the pressure value P2 at the end of the long-distance pipeline calculation section, and the recommended pipeline roughness value k′K with correction coefficient are calculated e , using the pipeline roughness value k′K e , improve the accuracy of the predicted downstream operating pressure value P2′, and improve the technical problem that the preset fixed roughness value of the existing natural gas long-distance pipeline deviates from the current actual roughness value, resulting in inaccurate prediction of the downstream operating pressure.

[0013] That is, as the initial information is acquired in real time, the recommended roughness value kK with correction factor can be dynamically calculated. e Compared with the preset fixed value, the calculation result of this method is closer to the actual roughness of the pipeline. The downstream predicted pressure value P2′ calculated using the roughness with correction coefficient recommended by the present invention is also more accurate.

[0014] In a second aspect, the present invention provides a system for determining the roughness of a long-distance natural gas pipeline, which is applied to the method for determining the roughness and downstream pressure of a long-distance natural gas pipeline, and the system comprises:

[0015] The acquisition module is used to acquire initial information, including the flow value q of the target natural gas long-distance pipeline. v , a pressure value P1 at the starting point of the calculation section of the target natural gas long-distance pipeline and a pressure value P2 at the end point of the calculation section of the target natural gas long-distance pipeline;

[0016] A first processing module is used to determine the hydraulic friction coefficient λ of the target natural gas long-distance pipeline according to the initial information;

[0017] The second processing module is used to determine the original pipeline roughness value kK with a correction coefficient according to the hydraulic friction coefficient λ e ;

[0018] The third processing module obtains the initial information of N consecutive time nodes within a preset pipeline roughness measurement time period, and counts the original pipeline roughness values ​​kK with correction coefficients corresponding to the N time nodes. e, and according to the N original pipeline roughness values ​​kK with correction coefficients e , determine the recommended pipe roughness value k′K with correction factor e ;

[0019] The fourth processing module is used to calculate the pipeline roughness value k′K with the correction coefficient according to the recommended e , and obtain the downstream predicted pressure value P2′ of the target natural gas long-distance pipeline. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a flow chart of the method for determining the roughness and downstream pressure of a long-distance natural gas pipeline of the present invention;

[0021] Figure 2 This is a structural diagram of the roughness determination system for a long-distance natural gas pipeline of the present invention. DETAILED DESCRIPTION

[0022] The principles and features of the present invention are described below. The examples given are only used to explain the present invention and are not used to limit the scope of the present invention.

[0023] In a first aspect, the present invention provides a method for determining the roughness and downstream pressure of a long-distance natural gas pipeline, as described in detail below.

[0024] like Figure 1 , a method for determining the roughness and downstream pressure of a natural gas long-distance pipeline, comprising the following steps:

[0025] S100, obtaining initial information of N consecutive time nodes within the current pipeline roughness measurement time period, wherein the initial information corresponding to each time node includes the flow value q of the target natural gas long-distance pipeline v , a starting point pressure value P1 of the calculation section of the target natural gas long-distance pipeline and an end point pressure value P2 of the calculation section of the target natural gas long-distance pipeline;

[0026] S200, for each of the time nodes, determining the hydraulic friction coefficient λ of the target natural gas long-distance pipeline according to the initial information corresponding to the time node;

[0027] S300, for each time node, determining the original pipeline roughness value kK with a correction coefficient according to the hydraulic friction coefficient λ corresponding to the time node e ;

[0028] S400, according to the N original pipeline roughness values ​​kK with correction coefficients corresponding to the current pipeline roughness measurement time period e , determine the recommended pipe roughness value k′K with correction factor e ;

[0029] S500, according to the recommended pipeline roughness value k′K with correction factor e , and obtain the downstream predicted pressure value P2′ of the target natural gas long-distance pipeline.

[0030] The beneficial effect of this embodiment is that the flow value q of the target natural gas long-distance pipeline obtained in real time v , the starting pressure value P1 of the calculation section, the end pressure value P2 of the calculation section, and the recommended pipeline roughness value k′K with correction coefficient are obtained by calculation e , using the pipeline roughness value k′K e , improve the accuracy of the predicted downstream operating pressure value P2′, and improve the technical problem that the preset fixed roughness value of the existing natural gas long-distance pipeline deviates from the current actual roughness value, resulting in inaccurate prediction of the downstream operating pressure.

[0031] In the embodiment of the present invention, the initial information can be acquired through the urgent acquisition of the pipeline information acquisition system. The acquisition method is simple and can be achieved by connecting to the existing pipeline information acquisition system. It is easy to operate, low cost, universal, easy to promote on a large scale, and can adapt to different pipeline scenarios, including long-distance pipelines, gathering pipelines, etc.

[0032] The recommended roughness value k′K with correction factor can be dynamically calculated by the above determination method. e Compared with the preset fixed value, the calculation result of this method is closer to the actual roughness of the pipeline. The roughness value vk′K with correction coefficient recommended by the present invention is adopted. e The calculated downstream predicted pressure value P2' is also more accurate.

[0033] Among them, in step S200, the hydraulic friction coefficient λ corresponding to a time node can be determined according to the gas pipeline flow calculation formula (1), and the gas pipeline flow calculation formula (1) is as follows:

[0034]

[0035] Where: q v It indicates the flow rate of gas at pressure P0 = 0.101325MPa and temperature T = 293K, in m 3 / d;

[0036] P1 represents the starting pressure of the calculation section, and P2 represents the ending pressure of the calculation section, both in MPa.

[0037] b is the coefficient, unit is m -1 , b=0.0683(△ / Zt m );

[0038] △h represents the elevation difference between the end point and the starting point of the gas pipeline, in meters;

[0039] d represents the inner diameter of the gas pipeline, in cm;

[0040] Z represents the compressibility factor of the gas;

[0041] △ represents the relative density of the gas;

[0042] t m It represents the average temperature of the gas in K;

[0043] L represents the length of the calculated section of the gas pipeline, in km;

[0044] n represents the number of calculation sections divided by the height difference along the gas pipeline;

[0045] i represents the i-th pipe section, h i Indicates the elevation of the end point of the i-th pipe segment, in m, h i－1 Indicates the elevation of the starting point of the i-th pipe section, in meters;

[0046] L i It indicates the length of each branch section in km. The sum of the lengths of all branch sections indicates the length of the calculation section.

[0047] λ represents the hydraulic friction coefficient of the natural gas long-distance pipeline.

[0048] In step S300, the original pipeline roughness value kK with correction coefficient corresponding to a time node e It can be determined according to Colebrook calculation formula (2), which is:

[0049]

[0050] Where: k represents the roughness correction coefficient of the gas pipeline;

[0051] K e —Preset the absolute roughness value of the fixed pipeline, in mm;

[0052] d represents the inner diameter of the gas pipeline, in mm;

[0053] Re represents the Reynolds number.

[0054] In step S400, the recommended pipeline roughness value k′K with correction coefficient is e It can be determined by the following formula (3) based on the recursive average filtering method and the median average filtering method. Formula (3) is:

[0055]

[0056] Where: j represents the jth time node, N represents the time node, and N-2 represents removing a maximum value and a minimum value.

[0057] In step S500, the downstream predicted pressure value P2′ can be determined according to the following formula (4):

[0058]

[0059] Where: λ′ represents the corrected friction coefficient of the natural gas long-distance pipeline.

[0060] On the basis of the above embodiment, the initial information further includes a soil temperature value t0 at the buried depth of the target natural gas long-distance pipeline and a gas temperature value t1 at the starting point of the calculated section of the target natural gas long-distance pipeline;

[0061] For each of the time nodes, according to the initial information corresponding to the time node, the hydraulic friction coefficient λ of the target natural gas long-distance pipeline is determined, including:

[0062] For each time node, the average temperature value t of the target natural gas long-distance pipeline is obtained according to the soil temperature value t0 and the gas temperature value t1 corresponding to the time node. m , according to the flow value q v , the starting pressure value P1, the end pressure value P2 and the average temperature value t m , and obtain the hydraulic friction coefficient λ of the target natural gas long-distance pipeline.

[0063] In an exemplary embodiment, for each of the time nodes, the average temperature value t0 of the target natural gas long-distance pipeline is obtained according to the soil temperature value t0 and the gas temperature value t1 corresponding to the time node. m ,include:

[0064] For each of the time nodes, when αL≥A, A is a preset value, and the average temperature value t is obtained according to formula (5) and formula (6): m , formula (5) and formula (6) are:

[0065]

[0066] Where, e represents the base of natural logarithm, e=2.718; x represents the length from the starting point of the calculated section of the target natural gas pipeline to any point along the pipeline, in km; △P x represents the pressure drop of the pipe section of length x, in MPa; K represents the total heat transfer coefficient from gas to soil in the target natural gas long-distance pipeline, in (W / m 2)℃; D represents the outer diameter of the target natural gas long-distance pipeline, in m; Cp represents the constant-pressure specific heat of the gas transported by the target natural gas long-distance pipeline, in (J / kg)℃; L represents the length of the calculated section of the target natural gas long-distance pipeline, in km; β represents the Joule-Thomson efficiency coefficient, in ℃ / MPa.

[0067] In this embodiment, the preset value A may be 10.

[0068] In an exemplary embodiment, for each of the time nodes, the average temperature value t0 of the target natural gas long-distance pipeline is obtained according to the soil temperature value t0 and the gas temperature value t1 corresponding to the time node. m ,include:

[0069] For each of the time nodes, when αL<A, A is a preset value, and the average temperature value t is obtained according to formula (5) and formula (7): m , formula (5) and formula (7) are:

[0070]

[0071] Where, e represents the base of natural logarithm, e=2.718; x represents the length from the starting point of the calculated section of the target natural gas pipeline to any point along the pipeline, in km; △P x represents the pressure drop of the pipe section of length x, in MPa; K represents the total heat transfer coefficient from gas to soil in the target natural gas long-distance pipeline, in (W / m 2 )℃; D represents the outer diameter of the target natural gas long-distance pipeline, in m; Cp represents the constant-pressure specific heat of the gas transported by the target natural gas long-distance pipeline, in (J / kg)℃; L represents the length of the calculated section of the target natural gas long-distance pipeline, in km; β represents the Joule-Thomson efficiency coefficient, in ℃ / MPa.

[0072] In this embodiment, the preset value A may be 10.

[0073] Based on the above embodiment, for each time node, the flow value q v , the starting pressure value P1, the end pressure value P2 and the average temperature value t m , the hydraulic friction coefficient λ of the target natural gas long-distance pipeline is obtained, including:

[0074] Step S220, for each of the time nodes, according to the starting pressure value P1 and the ending pressure value P2 of the target natural gas long-distance pipeline calculation section, determine the starting pressure value P1 and the average temperature value t of the natural gas in the target natural gas long-distance pipeline at the calculation section. mThe compression factor Z under the conditions is obtained, and the hydraulic friction coefficient λ of the target natural gas long-distance pipeline is obtained according to the compression factor Z.

[0075] Among them, for each of the time nodes, the starting pressure value P1 and the average temperature value t of the natural gas in the target natural gas long-distance pipeline at the calculation section are determined according to the starting pressure value P1 and the end pressure value P2 of the target natural gas long-distance pipeline. m The compression factor Z under the conditions includes:

[0076] Step S221, for each of the time nodes, according to the starting pressure value P1 of the calculation section of the target natural gas long-distance pipeline and the terminal pressure value P2 of the target natural gas long-distance pipeline, determine the average pressure value P of the calculation section m , according to the average pressure value P m Determine the starting pressure value P1 and the average temperature value t1 of the natural gas in the target natural gas long-distance pipeline at the calculation section m The compression factor Z under conditions.

[0077] The compression factor Z of natural gas in the target pipeline under this pipeline transportation condition can be obtained by the following formula (8):

[0078]

[0079] Where P m Indicates the average pressure value corresponding to the calculation segment at a time node.

[0080] Among them, the average pressure P corresponding to the calculation segment at a time node m It can be obtained by the following formula (9):

[0081]

[0082] On the basis of the above embodiment, for each time node, the original pipeline roughness value kK with correction coefficient is determined according to the hydraulic friction coefficient λ corresponding to the time node. e ,include:

[0083] Step S310: for each time node, obtain the natural gas Reynolds number Re in the target natural gas long-distance pipeline, and obtain the original pipeline roughness value kK with a correction coefficient according to the natural gas Reynolds number Re and the hydraulic friction coefficient λ corresponding to the time node. e .

[0084] The natural gas Reynolds number Re can be obtained by the following formula (10):

[0085]

[0086] In the formula, q v It indicates the flow rate of gas at pressure P0 = 0.101325MPa and temperature T = 293K, in m 3 / d;

[0087] d represents the inner diameter of the gas pipeline, in cm;

[0088] △ represents the relative density of the gas;

[0089] μ represents the dynamic viscosity of natural gas, with the unit of N (s / m 2 ).

[0090] Based on the above embodiment, the N original pipeline roughness values ​​kK with correction coefficients corresponding to the current pipeline roughness measurement time period are e , determine the recommended pipe roughness value k′K with correction factor e ,include:

[0091] Step S410, replacing the original pipeline roughness value kKe with the correction coefficient corresponding to the first time node in the current pipeline roughness measurement time period according to the original pipeline roughness value kKe with the correction coefficient corresponding to the first time node in the next time period of the current pipeline roughness measurement time period, and obtaining the original pipeline roughness value kKe with the correction coefficient corresponding to the new N time nodes in the current pipeline roughness measurement time period;

[0092] According to the new N original pipeline roughness values ​​kK with correction coefficients e , determine the recommended pipe roughness value k′K with correction factor e .

[0093] For example, if the preset pipeline roughness measurement period is 180 days, then a new original pipeline roughness value kK with correction factor is calculated each time. e , if the original pipeline roughness value kK with correction coefficient at a certain time node among N time nodes is counted e If the time period exceeds 180 days, the original pipeline roughness value kK with correction factor at a certain time node beyond the time period is used. e Replace the roughness value kK at the head of the original data queue 180 days ago (first-in-first-out principle) e .

[0094] If the data is less than 180 days old, only the new data will be saved and the old data will not be deleted.

[0095] Based on the above embodiment, the pipeline roughness value k′K with the recommended correction coefficient e, obtaining the downstream predicted pressure value P2′ of the target natural gas long-distance pipeline, including:

[0096] Step S510, in an exemplary solution, determining the hydraulic friction coefficient of the target natural gas long-distance pipeline corresponding to the current pipeline roughness measurement time period according to the hydraulic friction coefficients λ corresponding to the N time nodes corresponding to the current pipeline roughness measurement time period;

[0097] According to the recommended pipe roughness value with correction factor k′K e , correcting the hydraulic friction coefficient corresponding to the current pipeline roughness measurement time period to obtain a corrected hydraulic friction coefficient;

[0098] According to the corrected hydraulic friction coefficient, the downstream predicted pressure value P2' is obtained.

[0099] In another exemplary embodiment, according to the recommended pipeline roughness value k′K with correction factor e , the hydraulic friction coefficient of the target natural gas long-distance pipeline determined according to the initial information corresponding to the time node is corrected to obtain a corrected hydraulic friction coefficient λ′, and the downstream predicted pressure value P2′ is obtained according to the corrected friction coefficient λ′.

[0100] In this embodiment, the corrected friction coefficient λ′ can be obtained according to the following formula (11):

[0101]

[0102] In a second aspect, the present invention provides a system for determining the roughness of a long-distance natural gas pipeline, as described in detail below.

[0103] like Figure 2 , a system for determining the roughness of a long-distance natural gas pipeline, applied to the method for determining the roughness and downstream pressure of a long-distance natural gas pipeline described in the above embodiment, the system comprising:

[0104] The acquisition module is used to acquire initial information, including the flow value q of the target natural gas long-distance pipeline. v , a pressure value P1 at the starting point of the calculation section of the target natural gas long-distance pipeline and a pressure value P2 at the end point of the calculation section of the target natural gas long-distance pipeline;

[0105] A first processing module is used to determine the hydraulic friction coefficient λ of the target natural gas long-distance pipeline according to the initial information;

[0106] The second processing module is used to determine the original pipeline roughness value kK with a correction coefficient according to the hydraulic friction coefficient λ e ;

[0107] The third processing module obtains the initial information of N consecutive time nodes within a preset pipeline roughness measurement time period, and counts the original pipeline roughness values ​​kK with correction coefficients corresponding to the N time nodes. e , and according to the N original pipeline roughness values ​​kK with correction coefficients e , determine the recommended pipe roughness value k′K with correction factor e ;

[0108] The fourth processing module is used to calculate the pipeline roughness value k′K with the correction coefficient according to the recommended e , and obtain the downstream predicted pressure value P2′ of the target natural gas long-distance pipeline.

[0109] In the embodiment of the present invention, the initial information also includes a soil temperature value t0 at the buried depth of the gas pipeline and a gas temperature value t1 at the starting point of the calculated section of the gas pipeline.

[0110] The acquisition module is connected to the pipeline information acquisition system in communication, so that the initial information is collected in real time through the information acquisition system, so that the processing module can dynamically obtain the accurate recommended pipeline roughness value k′K with correction coefficient in real time. e , and obtain the accurate downstream predicted pressure value P2′.

[0111] In a third aspect, the present invention provides an electronic device, as described in detail below.

[0112] An electronic device comprises a memory, a processor and a computer program stored in the memory and executable on the processor, wherein when the processor executes the computer program, the method for determining the roughness and downstream pressure of a long-distance natural gas pipeline described in the above embodiment is implemented.

[0113] In a fourth aspect, the present invention provides a non-transitory computer-readable storage medium, as described in detail below.

[0114] A non-transitory computer-readable storage medium stores a computer program, which, when executed by a processor, implements the method for determining the roughness and downstream pressure of a long-distance natural gas pipeline as described in the above embodiment.

[0115] In the description of the present invention, it is to be understood that the terms “center”, “longitudinal”, “lateral”, “length”, “width”, “thickness”, “up”, “down”, “front”, “back”, “left”, “right”, “vertical”, “horizontal”, “top”, “bottom”, “inside”, “outside”, “clockwise”, “counterclockwise”, “axial”, “radial”, “circumferential”, etc., indicating orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0116] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of the present invention, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0117] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0118] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, a first feature being "above", "above" or "above" a second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being "below", "below" or "below" a second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0119] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0120] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations of the present invention. A person skilled in the art may change, modify, replace and vary the above embodiments within the scope of the present invention.

Claims

1. A method for determining the roughness and downstream pressure of a long-distance natural gas pipeline, characterized in that: The following steps are involved: Obtain the initial information of N consecutive time nodes within the current pipeline roughness measurement period. The initial information corresponding to each time node includes the flow value q of the target natural gas long-distance pipeline. v , a starting point pressure value P1 of the calculation section of the target natural gas long-distance pipeline and an end point pressure value P2 of the calculation section of the target natural gas long-distance pipeline; For each of the time nodes, determining the hydraulic friction coefficient λ of the target natural gas long-distance pipeline at the time node according to the initial information corresponding to the time node; For each time node, the original pipeline roughness value kK with correction coefficient corresponding to the time node is determined according to the hydraulic friction coefficient λ corresponding to the time node. e ; According to the N original pipeline roughness values ​​kK with correction coefficients corresponding to the current pipeline roughness measurement time period e , determine the recommended pipe roughness value k′K with correction factor e ; According to the recommended pipeline roughness value with correction factor k′K e , and obtain the downstream predicted pressure value P2′ of the target natural gas long-distance pipeline.

2. A method for determining the roughness and downstream pressure of a natural gas long-distance pipeline according to claim 1, characterized in that: The initial information also includes a soil temperature value t0 at the buried depth of the target natural gas long-distance pipeline and a gas temperature value t1 at the starting point of the calculated section of the target natural gas long-distance pipeline; For each of the time nodes, determining the hydraulic friction coefficient λ of the target natural gas long-distance pipeline at the time node according to the initial information corresponding to the time node includes: For each time node, the average temperature value t of the target natural gas long-distance pipeline at the time node is obtained according to the soil temperature value t0 and the gas temperature value t1 corresponding to the time node. m , according to the flow value q v , the starting pressure value P1, the end pressure value P2 and the average temperature value t m , and obtain the hydraulic friction coefficient λ of the target natural gas long-distance pipeline at the time node.

3. The method for determining the roughness and downstream pressure of a natural gas long-distance pipeline according to claim 2, characterized in that: For each time node, the average temperature value t of the target natural gas long-distance pipeline at the time node is obtained according to the soil temperature value t0 and the gas temperature value t1 corresponding to the time node. m ,include: For each of the time nodes, when αL≥A, A is a preset value, and the average temperature value t of the target natural gas long-distance pipeline at the time node is obtained according to formula (5) and formula (6): m , formula (5) and formula (6) are: Where, e represents the base of natural logarithm, e=2.718; x represents the length from the starting point of the calculated section of the target natural gas pipeline to any point along the pipeline, in km; △P x represents the pressure drop of the pipe section of length x, in MPa; K represents the total heat transfer coefficient from gas to soil in the target natural gas long-distance pipeline, in (W / m 2 )℃; D represents the outer diameter of the target natural gas long-distance pipeline, in m; Cp represents the constant-pressure specific heat of the gas transported by the target natural gas long-distance pipeline, in (J / kg)℃; L represents the length of the calculated section of the target natural gas long-distance pipeline, in km; β represents the Joule-Thomson efficiency coefficient, in ℃ / MPa.

4. The method for determining the roughness and downstream pressure of a long-distance natural gas pipeline according to claim 2, characterized in that: For each time node, the average temperature value t of the target natural gas long-distance pipeline at the time node is obtained according to the soil temperature value t0 and the gas temperature value t1 corresponding to the time node. m ,include: For each time node, when αL<A, A is a preset value, and the average temperature value t of the target natural gas long-distance pipeline at the time node is obtained according to formula (5) and formula (7): m , formula (5) and formula (7) are: Where, e represents the base of natural logarithm, e=2.718; x represents the length from the starting point of the calculated section of the target natural gas pipeline to any point along the pipeline, in km; △P x represents the pressure drop of the pipe section of length x, in MPa; K represents the total heat transfer coefficient from gas to soil in the target natural gas long-distance pipeline, in (W / m 2 )℃; D represents the outer diameter of the target natural gas long-distance pipeline, in m; Cp represents the constant-pressure specific heat of the gas transported by the target natural gas long-distance pipeline, in (J / kg)℃; L represents the length of the calculated section of the target natural gas long-distance pipeline, in km; β represents the Joule-Thomson efficiency coefficient, in ℃ / MPa.

5. The method for determining the roughness and downstream pressure of a long-distance natural gas pipeline according to claim 2, characterized in that: For each of the time nodes, the flow value q v , the starting pressure value P1, the end pressure value P2 and the average temperature value t m , the hydraulic friction coefficient λ of the target natural gas long-distance pipeline at the time node is obtained, including: For each time node, the starting pressure value P1 and the average temperature value t of the natural gas in the target natural gas long-distance pipeline at the calculation section are determined according to the starting pressure value P1 and the end pressure value P2 of the calculation section of the target natural gas long-distance pipeline. m The compression factor Z under the condition is obtained, and the hydraulic friction coefficient λ of the target natural gas long-distance pipeline at the time node is obtained according to the compression factor Z.

6. A method for determining the roughness and downstream pressure of a natural gas long-distance pipeline according to claim 5, characterized in that: For each of the time nodes, the starting pressure value P1 and the end pressure value P2 of the calculation section of the target natural gas long-distance pipeline are determined to determine the starting pressure value P1 and the average temperature value t of the natural gas in the target natural gas long-distance pipeline at the calculation section. m The compression factor Z under the conditions includes: For each of the time nodes, the average pressure value P of the calculation section is determined according to the starting pressure value P1 of the calculation section of the target natural gas long-distance pipeline and the end pressure value P2 of the target natural gas long-distance pipeline. m , according to the average pressure value P m Determine the starting pressure value P1 and the average temperature value t1 of the natural gas in the target natural gas long-distance pipeline at the calculation section m The compression factor Z under conditions.

7. The method for determining the roughness and downstream pressure of a natural gas long-distance pipeline according to claim 1, characterized in that: For each time node, the original pipeline roughness value kK with correction coefficient corresponding to the time node is determined according to the hydraulic friction coefficient λ corresponding to the time node. e ,include: For each time node, the natural gas Reynolds number Re in the target natural gas long-distance pipeline is obtained, and the original pipeline roughness value kK with correction coefficient corresponding to the time node is obtained according to the natural gas Reynolds number Re and the hydraulic friction coefficient λ corresponding to the time node. e .

8. A method for determining the roughness and downstream pressure of a long-distance natural gas pipeline according to any one of claims 1 to 7, characterized in that: The N original pipeline roughness values ​​kK with correction coefficients corresponding to the current pipeline roughness measurement time period e , determine the recommended pipe roughness value k′K with correction factor e ,include: The original pipeline roughness value kK with correction coefficient corresponding to the first time node in the next time period of the current pipeline roughness measurement time period e , replace the original pipeline roughness value kK with the correction coefficient corresponding to the first time node in the current pipeline roughness measurement time period e , obtain the original pipeline roughness value kK with correction coefficient corresponding to the new N time nodes in the current pipeline roughness measurement time period e ; According to the new N original pipeline roughness values ​​kK with correction coefficients e , determine the recommended pipe roughness value k′K with correction factor e .

9. A method for determining the roughness and downstream pressure of a long-distance natural gas pipeline according to any one of claims 1 to 7, characterized in that: The recommended pipeline roughness value with correction factor k′K e , obtaining the downstream predicted pressure value P2′ of the target natural gas long-distance pipeline, including: Determine the hydraulic friction coefficient of the target natural gas long-distance pipeline corresponding to the current pipeline roughness measurement time period according to the hydraulic friction coefficient λ corresponding to the N time nodes corresponding to the current pipeline roughness measurement time period; According to the recommended pipe roughness value with correction factor k′K e , correcting the hydraulic friction coefficient corresponding to the current pipeline roughness measurement time period to obtain a corrected hydraulic friction coefficient; According to the corrected hydraulic friction coefficient, the downstream predicted pressure value P2' is obtained.

10. A system for determining the roughness of a long-distance natural gas pipeline, characterized in that: The method for determining the roughness and downstream pressure of a long-distance natural gas pipeline according to any one of claims 1 to 9, the system comprising: The acquisition module is used to collect initial information, including the flow value q of the target natural gas long-distance pipeline. v , a pressure value P1 at the starting point of the calculation section of the target natural gas long-distance pipeline and a pressure value P2 at the end point of the calculation section of the target natural gas long-distance pipeline; A first processing module is used to determine the hydraulic friction coefficient λ of the target natural gas long-distance pipeline according to the initial information; The second processing module is used to determine the original pipeline roughness value kK with a correction coefficient according to the hydraulic friction coefficient λ e ; The third processing module obtains the initial information of N consecutive time nodes within a preset pipeline roughness measurement time period, and counts the original pipeline roughness values ​​kK with correction coefficients corresponding to the N time nodes. e , and according to the N original pipeline roughness values ​​kK with correction coefficients e , determine the recommended pipe roughness value k′K with correction factor e ; The fourth processing module is used to calculate the pipeline roughness value k′K with the correction coefficient according to the recommended e , and obtain the downstream predicted pressure value P2′ of the target natural gas long-distance pipeline.

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