A method and system for determining the pipe loss of a steam supply heat pipe network

Abstract

The present invention discloses a method and a system for determining the pipe loss of a steam supply heat pipe network. The method includes: determining the pressure of a target node according to the pressure, enthalpy value, mass flow rate and inner diameter of the pipe of the current node, as well as the friction resistance coefficient, the actual pipe length of the current pipe section interval, the pipe length converted from the local pipe resistance, and the altitude of the current node and the target node; determining the enthalpy value of the target node according to the steam temperature of the current node, the ambient temperature, the outer diameter of the pipe wall, the diameters of each layer of thermal insulation and the outermost diameter of the overall pipe, as well as the actual pipe length and the heat dissipation coefficient from the outer surface of the thermal insulation layer to the atmosphere, and determining the steam temperature of the target node according to the pressure and enthalpy value of the target node; determining the condensate water volume of the current pipe section interval according to the pressure, enthalpy value and mass flow rate of the target node, and determining the pipe loss of the steam supply heat pipe network according to the sum of the condensate water volumes of each pipe section interval, which improves the practicability on the basis of accurately determining the pipe loss.

Description

Technical Field

[0001] The present application relates to the field of energy technologies, and more specifically, to a method and system for determining the pipe loss of a steam supply heating pipeline network. Background Art

[0002] With the rapid development of the industrial heating industry, heating pipeline networks are gradually extending over long distances. Currently, industrial heating generally provides heat to user parties in the form of superheated steam. In long-distance pipeline networks (pipeline systems over 30 km), steam condensation is bound to occur. When the pipe diameter and flow rate do not match, this part of the loss can reach about 20%-30%. Therefore, accurately calculating the pipe loss of the pipeline network and quickly adjusting the steam supply parameters according to the change of the pipe loss are the main improvement directions of current industrial heating. Due to the phase change process in the steam supply heating pipeline network, the calculation of the heat dissipation of the pipeline network and the pipeline network state is relatively complex.

[0003] Currently, there are still the following problems in the calculation of pipeline network pipe loss:

[0004] 1. The calculation methods for the pipe loss of civil heating pipeline networks are generally used in current standards. There is only one liquid phase in the civil heating pipeline, without involving the phase change process, and there is no drainage in the pipeline.

[0005] 2. For the calculation method of the pipe loss of long-distance pipeline networks, it is generally calculated by modeling with heating pipeline network software, which is difficult for front-line personnel to master in actual engineering.

[0006] 3. When calculating the pipe loss, due to the involvement of the two-phase region, the physical properties here are often inaccurate.

[0007] Therefore, how to improve the practicality on the basis of accurately determining the pipe loss of the steam supply heating pipeline network is a technical problem to be solved currently. Summary of the Invention

[0008] The embodiments of the present application provide a method and system for determining the pipe loss of a steam supply heating pipeline network, so as to solve the technical problems of poor accuracy and low practicality when determining the pipe loss of a steam supply heating pipeline network in the prior art.

[0009] In a first aspect, a method for determining the pipe loss of a steam supply heating pipeline network is provided, and the method includes:

[0010] Step S1, determining a plurality of nodes according to the heating start point, each branch point, and each heating end point in the steam supply heating pipeline network, and determining a plurality of pipe section intervals and the order of each pipe section interval according to each node and the flow direction of the working medium. Each pipe section interval includes a start node and an end node;

[0011] Step S2: Take the starting node of the current pipe section interval as the current node, take the ending node of the current pipe section interval as the target node, and determine the pressure of the target node based on the pressure, enthalpy value, mass flow rate, and inner diameter of the pipe of the current node, as well as the friction resistance coefficient, the actual pipe length of the current pipe section interval, the pipe length converted from local pipe resistance, and the elevation of the current node and the target node.

[0012] Step S3: Determine the enthalpy value of the target node based on the steam temperature, ambient temperature, outer diameter of the pipe wall, diameters of each layer of insulation, and the outermost diameter of the overall pipe of the current node, as well as the actual pipe length and the heat dissipation coefficient from the outer surface of the insulation layer to the atmosphere, and determine the steam temperature of the target node based on the pressure and enthalpy value of the target node.

[0013] Step S4: Determine the steam dryness of the target node based on the pressure and enthalpy value of the target node, and determine the condensate water volume of the current pipe section interval based on the steam dryness and the mass flow rate of the current node.

[0014] Step S5: If the current pipe section interval is not the last pipe section interval, take the next pipe section interval of the current pipe section interval in the order as the new current pipe section interval, and re-execute Step S2 - Step S4 until the condensate water volume of the last pipe section interval is determined, and determine the pipe loss of the steam supply heating pipe network based on the sum of the condensate water volumes of each pipe section interval.

[0015] Among them, the starting node of the first current pipe section interval is the starting point of heat supply.

[0016] In the second aspect, a system for determining the pipe loss of a steam supply heating pipe network is provided. The system includes:

[0017] A pipe section interval determination module for executing Step S1: Determine multiple nodes based on the starting point of heat supply, each branch point, and each heat supply end point in the steam supply heating pipe network, and determine multiple pipe section intervals and the order of each pipe section interval according to each node and the flow direction of the working medium. Each pipe section interval includes a starting node and an ending node.

[0018] A pressure determination module for executing Step S2: Take the starting node of the current pipe section interval as the current node, take the ending node of the current pipe section interval as the target node, and determine the pressure of the target node based on the pressure, enthalpy value, mass flow rate, and inner diameter of the pipe of the current node, as well as the friction resistance coefficient, the actual pipe length of the current pipe section interval, the pipe length converted from local pipe resistance, and the elevation of the current node and the target node.

[0019] A temperature determination module, configured to execute step S3: determine the enthalpy value of a target node according to the steam temperature, ambient temperature, outer diameter of the pipeline, diameters of each layer of thermal insulation, and the outermost diameter of the overall pipeline of the current node, as well as the actual pipeline length and the heat dissipation coefficient from the outer surface of the thermal insulation layer to the atmosphere, and determine the steam temperature of the target node according to the pressure and enthalpy value of the target node;

[0020] A condensate water quantity determination module, configured to execute step S4: determine the steam dryness of the target node according to the pressure and enthalpy value of the target node, and determine the condensate water quantity of the current pipe section interval according to the steam dryness and the mass flow rate of the current node;

[0021] A pipeline loss determination module, configured to execute step S5: if the current pipe section interval is not the last pipe section interval, use the next pipe section interval of the current pipe section interval in the sequence as the new current pipe section interval, and re - execute steps S2 - S4 until the condensate water quantity of the last pipe section interval is determined, and determine the pipeline loss of the steam supply heat network according to the sum of the condensate water quantities of each pipe section interval;

[0022] Wherein, the starting node of the first current pipe section interval is the heat supply starting point.

[0023] In a third aspect, there is provided a terminal device, including a memory, a processor, and a computer program stored on the memory and executable on the processor. When the processor executes the computer program, the steps of the method described in the first aspect are implemented.

[0024] In a fourth aspect, there is provided a computer - readable storage medium, on which a computer program is stored. When the computer program is executed by a processor, the steps of the method described in the first aspect are implemented.

[0025] By applying the above technical solutions, in step S1, multiple nodes are determined according to the heat supply starting point, each branch point, and each heat supply ending point in the steam supply and heat supply pipeline network, and multiple pipe section intervals and the sequence of each pipe section interval are determined according to each node and the working medium flow direction; in step S2, the starting node of the current pipe section interval is used as the current node, the ending node of the current pipe section interval is used as the target node, and according to the pressure, enthalpy value, mass flow rate, and inner diameter of the pipeline of the current node, as well as the friction resistance coefficient, the actual pipeline length of the current pipe section interval, the pipeline length converted from the local pipe resistance, and the altitude of the current node and the target node, the pressure of the target node is determined; in step S3, according to the steam temperature, ambient temperature, outer diameter of the pipeline wall, diameters of each layer of thermal insulation, and the outermost diameter of the overall pipeline of the current node, as well as the actual pipeline length and the heat dissipation coefficient from the outer surface of the thermal insulation layer to the atmosphere, the enthalpy value of the target node is determined, and the steam temperature of the target node is determined according to the pressure and enthalpy value of the target node; in step S4, the steam dryness of the target node is determined according to the pressure and enthalpy value of the target node, and the condensate water volume of the current pipe section interval is determined according to the steam dryness and the mass flow rate of the current node; in step S5, if the current pipe section interval is not the last pipe section interval, the next pipe section interval in the sequence of the current pipe section interval is used as the new current pipe section interval, and steps S2 to S4 are executed again until the condensate water volume of the last pipe section interval is determined, and the pipe loss of the steam supply and heat supply pipeline network is determined according to the sum of the condensate water volumes of each pipe section interval; since the two-dimensional calculation method of increasing the radial thermal parameter change of the pipeline and the three-dimensional calculation method of finite element simulation of the pipeline are not adopted, but the one-dimensional calculation method that only considers the thermal parameter change along the axial direction of the pipeline is adopted, the practicability is improved on the basis of accurately determining the pipe loss of the steam supply and heat supply pipeline network. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the following drawings are only some embodiments of the present application. For those skilled in the art, other drawings can be obtained based on these drawings without creative efforts.

[0027] Figure 1 FIG. shows a schematic flowchart of a method for determining the pipe loss of a steam supply and heat supply pipeline network proposed in an embodiment of the present invention;

[0028] Figure 2 FIG. shows a schematic structural diagram of a typical steam supply and heat supply pipeline network;

[0029] Figure 3 FIG. shows a schematic flowchart of a method for determining the pipe loss of a steam supply and heat supply pipeline network proposed in another embodiment of the present invention;

[0030] Figure 4The figure shows a comparison diagram between the model values calculated by the pipe loss calculation model and the measured pipe loss values.

[0031] Figure 5 The figure shows a structural diagram of a system for determining the pipe loss of a steam supply heating pipe network proposed in an embodiment of the present invention. Detailed implementation manners

[0032] Next, the technical solutions in the embodiments of the present application will be clearly and completely described with reference to the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments of the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present application.

[0033] The embodiment of the present application provides a method for determining the pipe loss of a steam supply heating pipe network, as Figure 1 shown, the method includes the following steps:

[0034] Step S1, determine a plurality of nodes according to the heat supply starting point, each branch point and each heat supply ending point in the steam supply heating pipe network, and determine a plurality of pipe section intervals and the order of each pipe section interval according to each node and the working medium flow direction, and each pipe section interval includes a starting node and an ending node.

[0035] In this embodiment, the steam supply heating pipe network includes a heat supply starting point, a plurality of branch points and a plurality of heat supply ending points. The heat supply starting point can be the heat supply first station or a designated heat supply starting position, and the heat supply ending point is each heat network user or a designated heat supply ending position. Determine a plurality of nodes according to the heat supply starting point, each branch point and each heat supply ending point, and then determine a plurality of pipe section intervals and the order of each pipe section interval according to each node and the working medium flow direction. Each pipe section interval includes a starting node and an ending node.

[0036] For example, as Figure 2 shown is a schematic diagram of a typical steam supply heating pipe network structure. The heat supply starting point in this steam supply heating pipe network is a, each branch point is b, c, c1, d, e and e1, and each heat supply ending point is b1, c2, c3, d1, e2, e3 and f. Each pipe section interval is formed according to each node, and the order of each pipe section interval is determined according to the working medium flow direction. The sequentially arranged pipe section intervals formed thereby can be a-b, b-b1, b-c, c-c1, c1-cz, c1-c3, c-d, d-d1, d-e, e-e1, e1-e2, e1-e3, e-f. Among them, the order of the pipe section intervals with the same starting node can be interchanged. For example, the starting nodes of c1-c2 and c1-c3 are both c1, and their order can be interchanged. Those skilled in the art can set it flexibly.

[0037] It should be noted that there is a possible error in the text you provided. In the description of the pipe section intervals in item , "c1-cz" should probably be "c1-c2". The above translation has been corrected accordingly.Step S2: Take the starting node of the current pipe section interval as the current node, take the ending node of the current pipe section interval as the target node, and determine the pressure of the target node based on the pressure, enthalpy value, mass flow rate, and inner diameter of the pipe at the current node, as well as the friction resistance coefficient, the actual pipe length of the current pipe section interval, the pipe length converted from local pipe resistance, and the altitude of the current node and the target node.

[0038] In this embodiment, the parameters of each pipe section interval are processed in sequence. The pipe section interval including the heat supply starting point is pre-set as the first current pipe section interval, and the heat supply starting point is taken as the current node, and the ending node of the current pipe section interval is taken as the target node. The heat supply parameters of the heat supply starting point are pre-determined, and the heat supply parameters include pressure, steam temperature, enthalpy value, mass flow rate, the actual pipe length of the current pipe section interval, the pipe length converted from local pipe resistance, inner diameter of the pipe, and ambient temperature.

[0039] For example, as Figure 2 shown, if the current pipe section interval is a - b, take a as the current node and b as the target node, and determine the pressure of the target node b based on the pressure, enthalpy value, mass flow rate, and inner diameter of the pipe at the current node a, as well as the friction resistance coefficient, the actual pipe length of the current pipe section interval a - b, the pipe length converted from local pipe resistance, and the altitude of the current node a and the target node b.

[0040] In some embodiments of the present application, in order to accurately determine the pressure of the target node, step S2 is specifically:

[0041] Determine the working fluid density of the current node based on the pressure and enthalpy value of the current node, and determine the working fluid velocity of the current node based on the working fluid density, mass flow rate, and inner diameter of the pipe at the current node;

[0042] Determine the pressure drop of the current pipe section interval based on the working fluid density, working fluid velocity, inner diameter of the pipe, friction resistance coefficient, the actual pipe length, the pipe length converted from local pipe resistance, and the altitude of the current node and the target node:

[0043]

[0044] Determine the pressure of the target node based on the difference between the pressure of the current node and the pressure drop of the current pipe section interval:

[0045] P B = P A - △p A ;

[0046] where, △p A is the pressure drop of the current pipe section interval, ρ A is the working fluid density of the current node, P Ais the pressure of the current node, w A is the working fluid flow velocity of the current node, D A is the inner diameter of the pipeline at the current node, K is the friction resistance coefficient (usually selected according to the pipeline roughness), L A is the actual pipeline length, L dA is the pipeline length converted from the local pipe resistance, H B is the altitude of the target node, H A is the altitude of the current node, P B is the pressure of the target node.

[0047] In order to accurately determine the working fluid density and working fluid flow velocity of the current node, in some embodiments of the present application, the working fluid density of the current node is determined according to the pressure and enthalpy value of the current node, and the working fluid flow velocity of the current node is determined according to the working fluid density, mass flow rate and inner diameter of the pipeline of the current node. Specifically:

[0048] Determine the working fluid density of the current node according to the pressure and enthalpy value of the current node:

[0049] ρ A = ρ(P A , h A );

[0050] Determine the working fluid flow velocity of the current node according to the working fluid density, mass flow rate and inner diameter of the pipeline of the current node:

[0051]

[0052] where h A is the enthalpy value of the current node, ρ(P A , h A ) is the density calculation formula corresponding to P A and h A , m A is the mass flow rate of the current node.

[0053] In this embodiment, the density calculation formula corresponding to P A and h A is the prior art, and those skilled in the art can select a suitable density calculation formula according to needs, and the specific content will not be elaborated.

[0054] In order to improve the accuracy of the pressure drop in the current pipe section interval, in some embodiments of the present application, the method further includes:

[0055] When receiving the user's zeroing instruction for 10 ρA (H B - H A ), set 10 ρA (H B - HA ) set the value to zero.

[0056] Since 10 ρA (H B -H A ) is the pressure loss caused by the height difference between the head and the end of the pipeline, and those skilled in the art can choose to ignore it according to the actual situation.

[0057] Step S3: Determine the enthalpy value of the target node according to the steam temperature, ambient temperature, outer diameter of the pipeline, diameters of each layer of thermal insulation, and the outermost diameter of the overall pipeline of the current node, as well as the actual pipeline length and the heat dissipation coefficient from the outer surface of the thermal insulation layer to the atmosphere, and determine the steam temperature of the target node according to the pressure and enthalpy value of the target node.

[0058] In this embodiment, for example, if the current pipe section interval is a-b, a is the current node, and b is the target node, determine the enthalpy value of the target node b according to the steam temperature, ambient temperature, outer diameter of the pipeline, diameters of each layer of thermal insulation, and the outermost diameter of the overall pipeline of the current node a, as well as the actual pipeline length and the heat dissipation coefficient from the outer surface of the thermal insulation layer to the atmosphere, and determine the steam temperature of the target node b according to the pressure and enthalpy value of the target node b.

[0059] In order to accurately determine the enthalpy value and steam temperature of the target node, in some embodiments of the present application, step S3 is specifically:

[0060] Determine the sum of the thermal resistances of each thermal insulation layer according to the steam temperature, ambient temperature, outer diameter of the pipeline, diameters of each thermal insulation layer, and the outermost diameter of the overall pipeline of the current node;

[0061] Determine the unit heat dissipation according to the sum of the thermal resistances of each thermal insulation layer, the steam temperature of the current node, the ambient temperature, the outermost diameter of the overall pipeline, and the heat dissipation coefficient from the outer surface of the thermal insulation layer to the atmosphere:

[0062]

[0063] Determine the enthalpy value of the target node according to the enthalpy value of the current node, the unit heat dissipation, and the actual pipeline length:

[0064] h B = h A -q A L A ;

[0065] Determine the steam temperature of the target node according to the pressure and enthalpy value of the target node:

[0066] T B = T(P B , h B );

[0067] Among them, qA is the heat dissipation per unit, T A is the steam temperature of the current node, T a is the ambient temperature of the current node, i = 1, 2…n, n is the number of insulation layers, ΣR i is the sum of the thermal resistances of each insulation layer, D O is the outermost diameter of the overall pipeline, α is the heat dissipation coefficient from the outer surface of the insulation layer to the atmosphere, h B is the enthalpy value of the target node, h A is the enthalpy value of the current node, L A is the actual pipeline length, P B is the pressure of the target node, T(P B ,h B ) is related to P B and h B corresponding temperature calculation formula, T B is the steam temperature of the target node.

[0068] In this embodiment, the convective thermal resistance inside the pipe wall and the conductive thermal resistance of the pipe wall are ignored, only the thermal resistance of the insulation layer and the convective thermal resistance of the outermost insulation surface are considered, and it is assumed that the condensate water is evenly distributed inside each pipe section interval and the condensate water has been drained in this pipe section interval. In addition, the temperature calculation formula corresponding to P B and h B is the prior art, and those skilled in the art can select a suitable temperature calculation formula according to needs, and the specific content will not be elaborated here.

[0069] In order to accurately determine the sum of the thermal resistances of each insulation layer, in some embodiments of the present application, the sum of the thermal resistances of each insulation layer is determined according to the steam temperature, ambient temperature, outer diameter of the pipeline, diameters of each insulation layer and the outermost diameter of the overall pipeline of the current node, specifically:

[0070] Determine the temperature distribution along the radial direction of each insulation layer according to the steam temperature, ambient temperature, outer diameter of the pipeline, diameters of each insulation layer and the outermost diameter of the overall pipeline of the current node:

[0071]

[0072] Substitute the temperature distribution along the radial direction of each insulation layer into the thermal conductivity formula of each insulation layer respectively and determine the thermal conductivity of each insulation layer:

[0073] λ i = λ(T′ i );

[0074] Determine the sum of the thermal resistances of each insulation layer according to the thermal conductivity of each insulation layer and the diameter of each insulation layer:

[0075]

[0076] Among them, T i ' is the temperature distribution along the radial direction of the i-th layer of thermal insulation layer, D I is the outer diameter of the pipeline, D i is the diameter of the i-th layer of thermal insulation layer, λ i is the thermal conductivity of the i-th layer of thermal insulation layer, λ(T i ) is the thermal conductivity formula.

[0077] In this embodiment, first, the temperature distribution T i ' along the radial direction of each thermal insulation layer is calculated according to the temperature distribution of the steady-state single-layer cylindrical wall, and then the corresponding thermal conductivity λ i is calculated according to the thermal conductivity formula of different thermal insulation materials, and then the thermal resistance R i corresponding to each layer of thermal insulation is calculated, and the sum ΣR i of the thermal resistances of each thermal insulation layer is determined.

[0078] The thermal conductivity formula is prior art. Those skilled in the art can select a suitable thermal conductivity formula according to needs, or obtain it by polynomial fitting of the thermal conductivity given by the manufacturer. The specific content will not be elaborated here.

[0079] Step S4: Determine the steam dryness of the target node according to the pressure and enthalpy value of the target node, and determine the condensate water volume in the current pipe section interval according to the steam dryness and the mass flow rate of the current node.

[0080] In this embodiment, first, the steam dryness of the target node is determined according to the pressure and enthalpy value of the target node, and then the condensate water volume in the current pipe section interval can be determined according to the steam dryness and the mass flow rate of the current node.

[0081] In order to accurately determine the condensate water volume in the current pipe section interval, in some embodiments of the present application, the steam dryness of the target node is determined according to the pressure and enthalpy value of the target node:

[0082] x B = x(P B , h B );

[0083] If x B < 1, determine the condensate water volume in the current pipe section interval according to the steam dryness and the mass flow rate of the current node:

[0084] m cA = m A (1 - x B );

[0085] If x B ≥ 1, then m cA = 0;

[0086] Among them, x Bis the steam dryness of the target node, P B is the pressure of the target node, h B is the enthalpy value of the target node, x(P B , h B ) is the dryness calculation formula corresponding to P B and h B , and m cA is the condensate flow rate in the current pipe section interval, m A is the mass flow rate of the current node.

[0087] In this embodiment, if x B < 1, it indicates that there is condensate. Determine the condensate flow rate in the current pipe section interval according to the steam dryness and the mass flow rate of the current node; if x B ≥ 1, it indicates that there is no condensate in the current pipe section interval, and the condensate flow rate in the current pipe section interval is zero.

[0088] The dryness calculation formula corresponding to P B and h B is prior art. Those skilled in the art can select a suitable dryness calculation formula according to needs, or obtain it through property software calculation. The specific content will not be elaborated here.

[0089] Step S5, if the current pipe section interval is not the last pipe section interval, take the next pipe section interval of the current pipe section interval in the said order as the new current pipe section interval, and re - execute steps S2 - S4 until the condensate flow rate of the last pipe section interval is determined, and determine the pipe loss of the steam supply heat pipe network according to the sum of the condensate flow rates of each pipe section interval.

[0090] In this embodiment, after determining the condensate flow rate of the current pipe section interval, judge whether the current pipe section interval is the last pipe section interval. If so, take the next pipe section interval of the current pipe section interval in the said order as the new current pipe section interval. The starting node of the next pipe section interval is the ending node of the current pipe section interval when the current pipe section interval and the next pipe section interval are in series, and the starting node of the next pipe section interval is the starting node of the current pipe section interval when the current pipe section interval and the next pipe section interval are in parallel.

[0091] For example, if the current pipe section interval is a - b, and the order is a - b, b - b1, b - c, c - c1, c1 - c2, c1 - c3, c - d, d - d1, d - e, e - e1, e1 - e2, e1 - e3, e - f, after determining the condensate flow rate of the current pipe section interval a - b, judge that the current pipe section interval a - b is not the last pipe section interval, and take the next pipe section interval b - b1 as the new current pipe section interval.

[0092] The starting node of the next pipe section interval can be divided into two cases: (1) When the current pipe section interval and the next pipe section interval are in series, it is the ending node of the current pipe section interval. For example, when the current pipe section interval is a-b and the next pipe section interval is b-b1 in series, the starting node of the pipe section interval b-b1 is the ending node b of the current pipe section interval a-b; (2) When the current pipe section interval and the next pipe section interval are in parallel, it is the starting node of the current pipe section interval. For example, when the current pipe section interval is c1-c2 and the next pipe section interval is c1-c3 in parallel, the starting node of the pipe section interval c1-c3 is the starting node c1 of the current pipe section interval c1-c2.

[0093] Take the next pipe section interval as the new current pipe section interval, and re-execute steps S2 - S4 until the condensate water volume of the last pipe section interval is determined. Then, determine the pipe loss of the steam supply and heat distribution network based on the sum of the condensate water volumes of each pipe section interval.

[0094] For example, if the next pipe section interval b-b1 is taken as the new current pipe section interval, take the starting node b as the current node and the ending node b1 as the target node. Since the heating parameters of the starting node b, namely pressure, steam temperature, enthalpy value, mass flow rate, actual pipe length of the current pipe section interval, pipe length converted from local pipe resistance, pipe inner diameter, and ambient temperature, have been determined after step S4, after re-executing steps S2 - S4 based on the heating parameters of the starting node b, the condensate water volume of the pipe section interval b-b1 and the heating parameters of the ending node b1 can be determined. And so on, the condensate water volumes of other pipe section intervals and the heating parameters of the remaining nodes can be obtained in turn. Finally, the pipe loss of the steam supply and heat distribution network can be determined based on the sum of the condensate water volumes of each pipe section interval.

[0095] By applying the above technical solution, in step S1, a plurality of nodes are determined according to the heat supply starting point, each branch point, and each heat supply ending point in the steam supply and heat supply pipe network, and a plurality of pipe section intervals and the sequence of each pipe section interval are determined according to each node and the working medium flow direction. Each pipe section interval includes a starting node and an ending node; in step S2, the starting node of the current pipe section interval is used as the current node, the ending node of the current pipe section interval is used as the target node, and according to the pressure, enthalpy value, mass flow rate, and pipe inner diameter of the current node, as well as the friction resistance coefficient, the actual pipe length of the current pipe section interval, the pipe length converted from the local pipe resistance, and the altitude of the current node and the target node, the pressure of the target node is determined; in step S3, according to the steam temperature of the current node, the ambient temperature, the outer diameter of the pipe wall, the insulation diameters of each layer, and the outermost diameter of the overall pipe, as well as the actual pipe length and the heat dissipation coefficient from the outer surface of the insulation layer to the atmosphere, the enthalpy value of the target node is determined, and the steam temperature of the target node is determined according to the pressure and enthalpy value of the target node; in step S4, the steam dryness of the target node is determined according to the pressure and enthalpy value of the target node, and the condensate water volume of the current pipe section interval is determined according to the steam dryness and the mass flow rate of the current node; in step S5, if the current pipe section interval is not the last pipe section interval, the next pipe section interval in the sequence is used as the new current pipe section interval, and steps S2 to S4 are executed again until the condensate water volume of the last pipe section interval is determined, and the pipe loss of the steam supply and heat supply pipe network is determined according to the sum of the condensate water volumes of each pipe section interval; wherein, the starting node of the first current pipe section interval is the heat supply starting point. Since the two-dimensional calculation method of increasing the radial thermal parameter change of the pipe and the three-dimensional calculation method of finite element simulation of the pipe are not adopted, but the one-dimensional calculation method that only considers the thermal parameter change along the axial direction of the pipe is adopted, the practicability is improved on the basis of accurately determining the pipe loss of the steam supply and heat supply pipe network.

[0096] To further elaborate on the technical idea of the present invention, the technical solution of the present invention will be described below in combination with specific application scenarios.

[0097] An embodiment of the present application provides a method for determining the pipe loss of a steam supply and heat supply pipe network, as Figure 3 shown, including the following steps:

[0098] Step S101, a plurality of nodes are determined according to the heat supply starting point, each branch point, and each heat supply ending point in the steam supply and heat supply pipe network, and a plurality of pipe section intervals and the sequence of each pipe section interval are determined according to each node and the working medium flow direction. Each pipe section interval includes a starting node and an ending node.

[0099] Step S102, the working medium density of the current node is determined according to the pressure and enthalpy value of the current node, and the working medium flow velocity of the current node is determined according to the working medium density, mass flow rate, and pipe inner diameter of the current node.

[0100] Specifically, determine the working fluid density of the current node based on the pressure and enthalpy value of the current node:

[0101] ρ A = ρ(P A , h A );

[0102] Determine the working fluid velocity of the current node based on the working fluid density, mass flow rate, and pipe inner diameter of the current node:

[0103]

[0104] where ρ A is the working fluid density of the current node, P A is the pressure of the current node, w A is the working fluid velocity of the current node, D A is the pipe inner diameter of the current node, h A is the enthalpy value of the current node, ρ(P A , h A ) is the density calculation formula corresponding to P A and h A , and m A is the mass flow rate of the current node.

[0105] Step S103: Determine the pressure drop of the current pipe section interval based on the working fluid density, working fluid velocity, pipe inner diameter, friction resistance coefficient, the actual pipe length, the pipe length converted from local pipe resistance, and the altitude of the current node and the target node.

[0106] Specifically,

[0107] where △p A is the pressure drop of the current pipe section interval, K is the friction resistance coefficient, L A is the actual pipe length, L dA is the pipe length converted from local pipe resistance, H B is the altitude of the target node, and H A is the altitude of the current node.

[0108] Step S104: Determine the pressure of the target node based on the difference between the pressure of the current node and the pressure drop of the current pipe section interval.

[0109] P B = P A - △p A ;

[0110] where P B is the pressure of the target node.

[0111] Step S105: Determine the sum of the thermal resistances of each insulation layer based on the steam temperature, ambient temperature, outer diameter of the pipeline, diameters of each insulation layer, and the outermost diameter of the overall pipeline at the current node.

[0112] Specifically, determine the temperature distribution along the radial direction of each insulation layer based on the steam temperature, ambient temperature, outer diameter of the pipeline, diameters of each insulation layer, and the outermost diameter of the overall pipeline at the current node:

[0113]

[0114] Substitute the temperature distribution along the radial direction of each insulation layer into the thermal conductivity formula of each insulation layer respectively and determine the thermal conductivity of each insulation layer:

[0115] λ i =λ(T′ i );

[0116] Determine the sum of the thermal resistances of each insulation layer based on the thermal conductivity of each insulation layer and the diameter of each insulation layer:

[0117]

[0118] where, T i ' is the temperature distribution along the radial direction of the i-th insulation layer, D I is the outer diameter of the pipeline, D i is the diameter of the i-th insulation layer, λ i is the thermal conductivity of the i-th insulation layer, λ(T i ) is the thermal conductivity formula, T A is the steam temperature at the current node, T a is the ambient temperature at the current node, i = 1, 2…n, n is the number of insulation layers, ∑R i is the sum of the thermal resistances of each insulation layer, D O is the outermost diameter of the overall pipeline.

[0119] Step S106: Determine the unit heat dissipation based on the sum of the thermal resistances of each insulation layer, the steam temperature, ambient temperature, outermost diameter of the overall pipeline at the current node, and the heat dissipation coefficient from the outer surface of the insulation layer to the atmosphere.

[0120] Specifically,

[0121] where, q A is the unit heat dissipation, and α is the heat dissipation coefficient from the outer surface of the insulation layer to the atmosphere.

[0122] Step S107: Determine the enthalpy value of the target node based on the enthalpy value, unit heat dissipation, and the actual pipeline length at the current node, and determine the steam temperature of the target node based on the pressure and enthalpy value of the target node.

[0123] Specifically, determine the enthalpy value of the target node based on the enthalpy value of the current node, the unit heat dissipation, and the actual pipeline length:

[0124] h B = h A - q A L A ;

[0125] Determine the steam temperature of the target node based on the pressure and enthalpy value of the target node:

[0126] T B = T(P B , h B );

[0127] Wherein, h B is the enthalpy value of the target node, h A is the enthalpy value of the current node, P B is the pressure of the target node, T(P B , h B ) is the temperature calculation formula corresponding to P B and h B , and T B is the steam temperature of the target node.

[0128] Step S108, determine the steam dryness of the target node based on the pressure and enthalpy value of the target node, and determine the condensate water volume of the current pipe section interval according to the steam dryness and the mass flow rate of the current node.

[0129] Specifically, determine the steam dryness of the target node based on the pressure and enthalpy value of the target node:

[0130] x B = x(P B , h B );

[0131] If x B < 1, determine the condensate water volume of the current pipe section interval according to the steam dryness and the mass flow rate of the current node:

[0132] m cA = m A (1 - x B );

[0133] If x B ≥ 1, then m cA = 0;

[0134] Wherein, x B is the steam dryness of the target node, x(P B , h B ) is the dryness calculation formula corresponding to P B and h B , and mcA is the condensate flow rate of the current pipe section interval, m A is the mass flow rate of the current node.

[0135] Step S109: Determine whether the current pipe section interval is the last pipe section interval. If so, execute Step S111; otherwise, execute Step S110.

[0136] Step S110: Take the next pipe section interval of the current pipe section interval in the said order as the new current pipe section interval, and re-execute Step S102.

[0137] Step S111: Determine the pipe loss of the steam supply and heat distribution network according to the sum of the condensate flow rates of each pipe section interval.

[0138] By applying the above technical solution, the steam dryness is calculated through the enthalpy value and pressure at the end of the pipe section interval, so as to calculate the condensate flow rate, and the pipe loss of the network under different working conditions can be calculated. For the temperature drop calculation, it is obtained by accurately calculating the heat dissipation process of the pipeline, which improves the accuracy of the hydraulic calculation. In addition, the overall method is simple and very practical in the operation of the network.

[0139] According to the monthly average heat network data provided by a certain thermal power plant in one year, a one-dimensional calculation is carried out on the mathematical model corresponding to the method for determining the pipe loss of the steam supply and heat distribution network in this embodiment, and the data with large daily changes in heating parameters (February, June, December) are excluded, and the result is obtained as Figure 4 shown. As Figure 4 shown, the measured value of the actual pipe loss is very close to the model value of the model calculation of the pipe loss, and the maximum relative error is -6.2%, indicating that the method for determining the pipe loss of the steam supply and heat distribution network in this embodiment has practical value in engineering.

[0140] The embodiment of the present application also proposes a system for determining the pipe loss of a steam supply and heat distribution network, as Figure 5 shown, the system includes:

[0141] The pipe section interval determination module 10 is used to execute Step S1: Determine multiple nodes according to the heat supply starting point, each branch point and each heat supply end point in the steam supply and heat distribution network, and determine multiple pipe section intervals and the order of each pipe section interval according to each node and the working fluid flow direction. Each pipe section interval includes a starting node and an ending node;

[0142] The pressure determination module 20 is used to execute Step S2: Take the starting node of the current pipe section interval as the current node, take the ending node of the current pipe section interval as the target node, and determine the pressure of the target node according to the pressure, enthalpy value, mass flow rate and pipe inner diameter of the current node, as well as the friction resistance coefficient, the actual pipe length of the current pipe section interval, the pipe length converted from the local pipe resistance, and the altitude of the current node and the target node.

[0143] A temperature determination module 30, configured to execute step S3: determine the enthalpy value of a target node according to the steam temperature, ambient temperature, outer diameter of the pipeline, diameters of each layer of thermal insulation, and the outermost diameter of the overall pipeline of the current node, and the actual pipeline length and the heat dissipation coefficient from the outer surface of the thermal insulation layer to the atmosphere, and determine the steam temperature of the target node according to the pressure and enthalpy value of the target node;

[0144] A condensate water quantity determination module 40, configured to execute step S4: determine the steam dryness of the target node according to the pressure and enthalpy value of the target node, and determine the condensate water quantity of the current pipe section interval according to the steam dryness and the mass flow rate of the current node;

[0145] A pipeline loss determination module 50, configured to execute step S5: if the current pipe section interval is not the last pipe section interval, use the next pipe section interval of the current pipe section interval in the sequence as the new current pipe section interval, and re - execute steps S2 - S4 until the condensate water quantity of the last pipe section interval is determined, and determine the pipeline loss of the steam supply heat network according to the sum of the condensate water quantities of each pipe section interval;

[0146] Wherein, the starting node of the first current pipe section interval is the heat supply starting point.

[0147] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present application, and are not intended to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A method for determining the pipe loss of a steam supply thermal pipeline network, characterized in that The method includes: Step S1: Determine multiple nodes based on the heat supply starting point, each branch point, and each heat supply ending point in the steam supply heat pipe network, and determine multiple pipe section intervals and the order of each pipe section interval according to each node and the working medium flow direction. Each pipe section interval includes a starting node and an ending node; Step S2: Take the starting node of the current pipe section interval as the current node, take the ending node of the current pipe section interval as the target node, and determine the pressure of the target node according to the pressure, enthalpy value, mass flow rate, and pipe inner diameter of the current node, as well as the friction resistance coefficient, the actual pipe length of the current pipe section interval, the pipe length converted from local pipe resistance, and the altitude of the current node and the target node; Step S3: Determine the enthalpy value of the target node according to the steam temperature of the current node, the ambient temperature, the outer diameter of the pipe wall, the diameters of each insulation layer, and the outermost diameter of the overall pipe, as well as the actual pipe length and the heat dissipation coefficient from the outer surface of the insulation layer to the atmosphere, and determine the steam temperature of the target node according to the pressure and enthalpy value of the target node; Step S4: Determine the steam dryness of the target node according to the pressure and enthalpy value of the target node, and determine the condensate water volume of the current pipe section interval according to the steam dryness and the mass flow rate of the current node; Step S5: If the current pipe section interval is not the last pipe section interval, take the next pipe section interval after the current pipe section interval in the order as the new current pipe section interval, and re - execute Step S2 - Step S4 until the condensate water volume of the last pipe section interval is determined, and determine the pipe loss of the steam supply heat pipe network according to the sum of the condensate water volumes of each pipe section interval; Among them, the starting node of the first current pipe section interval is the heat supply starting point; Step S2 is specifically: Determine the working medium density of the current node according to the pressure and enthalpy value of the current node, and determine the working medium flow velocity of the current node according to the working medium density, mass flow rate, and pipe inner diameter of the current node; Determine the pressure drop of the current pipe section interval according to the working medium density, working medium flow velocity, pipe inner diameter, friction resistance coefficient, the actual pipe length, the pipe length converted from local pipe resistance, and the altitude of the current node and the target node; ； Determine the pressure of the target node according to the difference between the pressure of the current node and the pressure drop of the current pipe section interval; P B = P A -△ p A ； where, △ p A is the pressure drop of the current pipe section interval, ρ A is the working fluid density of the current node, P A is the pressure of the current node, w A is the working fluid flow velocity of the current node, D A is the inner diameter of the pipe at the current node, K is the friction resistance coefficient, L A is the actual pipe length of the said pipe, L dA is the pipe length converted from the local pipe resistance, H B is the altitude of the target node, H A is the altitude of the current node, P B is the pressure of the target node.

2. The method according to claim 1, characterized in that, Determine the working medium density of the current node according to the pressure and enthalpy value of the current node, and determine the working medium flow velocity of the current node according to the working medium density, mass flow rate, and pipe inner diameter of the current node. Specifically: Determine the working medium density of the current node according to the pressure and enthalpy value of the current node: ； Determine the working medium flow velocity of the current node according to the working medium density, mass flow rate, and pipe inner diameter of the current node: ； Among them, h A is the enthalpy value of the current node, ρ(P A ，h A ） is the density calculation formula corresponding to P A and h A The corresponding density calculation formula, m A is the mass flow rate of the current node.

3. The method according to claim 1, wherein The method further includes: When receiving the user's zeroing instruction for , zero out the value of .

4. The method according to claim 1, wherein Step S3 is specifically: Determine the sum of the thermal resistances of each insulation layer according to the steam temperature of the current node, the ambient temperature, the outer diameter of the pipe wall, the diameters of each insulation layer, and the outermost diameter of the overall pipe; Determine the unit heat dissipation according to the sum of the thermal resistances of each insulation layer, the steam temperature of the current node, the ambient temperature, the outermost diameter of the overall pipe, and the heat dissipation coefficient from the outer surface of the insulation layer to the atmosphere; ； Determine the enthalpy value of the target node according to the enthalpy value of the current node, the unit heat dissipation, and the actual pipe length; ； Determine the steam temperature of the target node based on the pressure and enthalpy value of the target node: ； Among them, q A is the unit heat dissipation, T A is the steam temperature of the current node, T a is the ambient temperature of the current node, i = 1, 2…n, where n is the number of insulation layers, is the sum of the thermal resistances of each insulation layer, D O is the outermost diameter of the overall pipeline, α is the heat dissipation coefficient from the outer surface of the insulation layer to the atmosphere, h B is the enthalpy value of the target node, h A is the enthalpy value of the current node, L A is the actual pipeline length, P B is the pressure of the target node, T( P B , h B ) is related to P B and h B corresponding temperature calculation formula, T B is the steam temperature of the target node.

5. The method according to claim 4, wherein Determine the sum of the thermal resistances of each insulation layer based on the steam temperature of the current node, the ambient temperature, the outer diameter of the pipeline, the diameters of each insulation layer, and the outermost diameter of the overall pipeline, specifically as follows: Determine the temperature distribution along the radial direction of each insulation layer based on the steam temperature of the current node, the ambient temperature, the outer diameter of the pipeline, the diameters of each insulation layer, and the outermost diameter of the overall pipeline: ； Substitute the temperature distribution along the radial direction of each insulation layer into the thermal conductivity formula of each insulation layer respectively and determine the thermal conductivity of each insulation layer: ； Determine the sum of the thermal resistances of each insulation layer based on the thermal conductivity of each insulation layer and the diameter of each insulation layer: ； Among them, T i ' is the temperature distribution along the radial direction of the i -th layer of thermal insulation layer, D I is the outer diameter of the pipeline, D i is the diameter of the i -th layer of thermal insulation layer, λ i is the thermal conductivity of the i -th layer of thermal insulation layer, λ(T i ') is the thermal conductivity formula.

6. The method according to claim 1, wherein Step S4 is specifically as follows: Determine the steam quality of the target node based on the pressure and enthalpy value of the target node: ； If x B < 1, determine the condensate water volume of the current pipe section interval according to the steam dryness and the mass flow rate of the current node: ； If x B ≥ 1, then m cA = 0; Among them, x B is the steam dryness of the target node, P B is the pressure of the target node, h B is the enthalpy value of the target node, x ( P B , h B ) is related to P B and h B corresponding dryness calculation formula, m cA is the condensate water volume of the current pipe section interval, m A is the mass flow rate of the current node.

7. A system for determining the pipe loss of a steam supply thermal pipeline network, characterized in that, Steps for implementing the method according to any one of claims 1 to 6, the system comprising: A pipe section interval determination module for performing step S1: determining a plurality of nodes according to the heat supply starting point, each branch point, and each heat supply end point in the steam supply heat network, and determining a plurality of pipe section intervals and the order of each pipe section interval according to each node and the working fluid flow direction, each pipe section interval including a starting node and an ending node; A pressure determination module for performing step S2: taking the starting node of the current pipe section interval as the current node, taking the ending node of the current pipe section interval as the target node, and determining the pressure of the target node according to the pressure, enthalpy value, mass flow rate, and inner diameter of the pipeline of the current node, as well as the friction resistance coefficient, the actual pipeline length of the current pipe section interval, the pipeline length converted from the local pipe resistance, and the altitude of the current node and the target node; A temperature determination module for performing step S3: determining the enthalpy value of the target node according to the steam temperature of the current node, the ambient temperature, the outer diameter of the pipeline, the diameters of each insulation layer, and the outermost diameter of the overall pipeline, as well as the actual pipeline length and the heat dissipation coefficient from the outer surface of the insulation layer to the atmosphere, and determining the steam temperature of the target node according to the pressure and enthalpy value of the target node; A condensate water quantity determination module for performing step S4: determining the steam quality of the target node according to the pressure and enthalpy value of the target node, and determining the condensate water quantity of the current pipe section interval according to the steam quality and the mass flow rate of the current node; A pipeline loss determination module for performing step S5: if the current pipe section interval is not the last pipe section interval, taking the next pipe section interval of the current pipe section interval in the order as the new current pipe section interval, and re-executing steps S2 - S4 until the condensate water quantity of the last pipe section interval is determined, and determining the pipeline loss of the steam supply heat network according to the sum of the condensate water quantities of each pipe section interval; Wherein, the starting node of the first current pipe section interval is the heat supply starting point.

8. A terminal device, comprising a memory, a processor, and a computer program stored on the memory and executable on the processor, characterized in that, When the processor executes the computer program, it implements the steps of the method according to any one of claims 1 to 6.

9. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by the processor, it implements the steps of the method according to any one of claims 1 to 6.

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