Direct calculation method for flow distribution of natural gas hydrogen doping system

Abstract

The invention discloses a direct flow distribution calculation method for a natural gas hydrogen doping system, which comprises the following steps: S1, directly doping hydrogen in a preset proportion into a natural gas pipeline without any gas mixing equipment on the basis of a distributed hydrogen doping technology to form the natural gas hydrogen doping system; s2, establishing a flow mechanism model of the natural gas hydrogen doping system, and considering the influence of two types of gas parameters, namely gas flow and total heat value, on flow distribution; s3, constructing an air pressure flow equation considering the relative density of the pipeline mixed gas and the heat value of the node mixed gas, and calculating the relative density of the pipeline mixed gas and the heat value of the node mixed gas by iteratively updating the air pressure of each node, the relative density of the node mixed gas, the heat value of the node mixed gas, the relative density of the pipeline mixed gas and the heat value of the pipeline mixed gas in the air pressure flow equation. And solving the flow distribution of the natural gas hydrogen doping system.

Description

Technical Field

[0001] This invention belongs to the field of energy quality analysis technology for natural gas systems, and specifically relates to a direct calculation method for the vortex distribution in a natural gas hydrogen-blended system. Background Technology

[0002] As crucial technologies supporting the high-proportion consumption of new energy sources, emerging technologies such as natural gas blending with hydrogen, electric heating, and green electricity hydrogen production have been widely applied, further enriching the types of energy included in integrated energy systems (IES). The deep coupling of electricity, natural gas, hydrogen, heat, and cold energy further highlights the differences in energy quality within IES.

[0003] In the industrial sector, there are typical scenarios with varying energy quality, such as waste heat utilization and exhaust gas utilization. The scientific energy use philosophy of using energy according to its quality, matching it to temperature, cascading utilization, and maximizing heat utilization has become an industry consensus. With the large-scale development of renewable energy, a series of technologies for absorbing high proportions of new energy, such as green electricity to hydrogen production, electric heating, and natural gas blending with hydrogen, are constantly emerging. On the one hand, this breaks down the barriers to the independent operation of electricity / gas / cooling / heating, increasing the diversity of energy types in energy systems (IES); on the other hand, multi-energy complementarity also makes the differences in energy quality within IES more prominent, enriching the application scenarios.

[0004] The dual attributes of quantity and quality of energy determine the limitations of traditional natural gas system energy flow models in energy quality analysis. Backflow analysis is an important tool for focusing on the essence of energy utilization. The establishment of a backflow mechanism model for natural gas systems has solved the problem that backflow analysis of black-box natural gas systems cannot reveal weak links in their energy-saving capabilities. However, with the advancement of energy transition, the types of energy in natural gas systems are becoming increasingly diversified, energy equipment is constantly being updated, and new technologies are emerging. Existing backflow mechanism models for natural gas systems do not yet consider the key energy transition technology of hydrogen blending in natural gas. Therefore, it is necessary to further improve the backflow mechanism model of natural gas systems and the corresponding solution methods. Summary of the Invention

[0005] The purpose of this invention is to fill the gap in the prior art and solve the problem that existing technologies for calculating the sludge distribution in natural gas hydrogen blending systems have not considered the impact of changes in gas quality conditions such as relative density and total calorific value on sludge distribution. This invention provides a direct calculation method for the sludge distribution of natural gas hydrogen blending systems, specifically for distributed hydrogen blending technology, to achieve the calculation of the sludge distribution in natural gas hydrogen blending systems.

[0006] The objective of this invention is achieved through the following technical solution:

[0007] A direct calculation method for the flow distribution in a natural gas hydrogen blending system includes:

[0008] S1. Based on distributed hydrogen blending technology, without the aid of any gas mixing equipment, hydrogen is directly blended into the natural gas pipeline in a preset proportion to form a natural gas hydrogen blending system;

[0009] S2. Establish a sludge mechanism model for a natural gas hydrogen blending system, taking into account the influence of two gas parameters, relative density and total calorific value, on sludge distribution;

[0010] S3. Construct a pressure-fluidity equation that considers the relative density of the mixed gas in the pipeline and the calorific value of the mixed gas at the nodes. By iteratively updating the pressure, relative density, calorific value, relative density of the mixed gas at each node, and calorific value of the mixed gas in each pipeline in the pressure-fluidity equation, the fluid distribution of the natural gas-hydrogen blending system can be solved.

[0011] Furthermore, the flow mechanism model described in step S2 is obtained through:

[0012] The gas power is determined by multiplying the total calorific value of the gas by the gas flow rate.

[0013] The potential of a natural gas-hydrogen blending system is expressed as the product of gas power and the energy mass coefficient of the gas.

[0014] Pipeline loss is represented by the product of the potential difference at both ends of the pipe and the airflow rate.

[0015] To achieve a quantitative description of the changes in gas and gas parameters before and after hydrogen doping.

[0016] Furthermore, in step S3, the pressure-flow equations considering the relative density of the pipeline gas mixture and the calorific value of the node gas mixture are adopted. Specifically, the Lacey equation for low-pressure natural gas systems, the Polyflow equation for medium-pressure natural gas systems, and the Panhandle A equation for high-pressure natural gas systems are adopted respectively, and the potential expression is introduced into the above equations to describe the node gas pressure-pipeline gas flow relationship under different operating conditions.

[0017] Furthermore, in step S3, assuming that the gases flowing into the same node are fully mixed, the relative density and calorific value of the mixed gas at the node are calculated by weighted average of the gas flow rate of each branch and the corresponding gas quality parameters.

[0018] Furthermore, the iterative solution of the air pressure flow equation in step S3 employs the Newton-Raphson nodal method, specifically including:

[0019] Construct a node Jacobian matrix based on residuals;

[0020] Update the nodal pressure or its square until the residual converges;

[0021] The relative density and calorific value of the mixed gas at each node and in each pipeline are updated synchronously.

[0022] Repeat the iteration until the residual current of the natural gas hydrogen blending system is lower than the set threshold.

[0023] Furthermore, in step S2,

[0024] The flow mechanism model of the natural gas hydrogen blending system is expressed as follows:

[0025] (1)

[0026] In the formula, and These represent the gas power and gas flow rate transmitted through the pipeline, respectively; G is the total calorific value of the gas, which depends on the gas composition within the natural gas blending system.

[0027] Natural gas energy is measured by thermal power. The fuel consumed by the gas load is equivalent to the heat generated during gas combustion from ambient temperature to the theoretical combustion temperature; the gas flow rate... The energy mass coefficient of a gas can be determined by its energy mass coefficient. The product of gas power is expressed as:

[0028] (2)

[0029] In the formula, The ambient temperature; The theoretical combustion temperature of the gas is given by the energy mass coefficient of natural gas, hydrogen, and the mixture. They are all considered to be the same constant;

[0030] Gas flow Represented as variables With natural gas flow The product of:

[0031] (3)

[0032] variable The potential of a natural gas hydrogen blending system is expressed as the potential carried per unit gas flow rate, with units of (kW∙h) / m³. 3 It is related to the calorific value of the gas, specifically expressed as:

[0033] (4)

[0034] The pipeline loss in a natural gas-hydrogen blending system is expressed as the product of the potential difference between the two ends and the gas flow rate:

[0035] (5)

[0036] In the formula, For pipeline damage; and These represent the forces at both ends of the pipe.

[0037] Furthermore, in step S3,

[0038] If the turbulent flow satisfies the generalized Kirchhoff's first law at the nodes, then the equilibrium equation for the turbulent flow at the nodes can be expressed as:

[0039] (6)

[0040] In the formula, The node's flow vector; The flow vector of the pipeline; The node-branch correlation matrix of the natural gas hydrogen blending system is as follows: 1-th order matrix Let be the order of the matrix;

[0041] The nodal pressure-pipeline gas flow relationships for low, medium, and high-pressure natural gas hydrogen blending systems were constructed using the Lacey equation, Polyflo equation, and Panhandle A equation, respectively. Substituting the above three types of equations, we obtain the pressure-flow equation:

[0042] (7)

[0043] In the formula, and These represent the air pressure at both ends of the pipe; and These are the pipe diameter and length, respectively. The efficiency factor is set to 0.8~1; The relative density of the gas mixture in the pipeline; The calorific value of the mixed gas at the node; The energy mass coefficient of the gas mixture; The flow vector of the pipeline; For the sake of momentum, Natural gas flow rate; index Take values ​​of 2, 1.848, and 1.854 respectively;

[0044] Assuming the gases flowing into the node are completely mixed, the gases flowing out of the node all have the same relative density and calorific value. The relative density and calorific value of the mixed gases at the node are expressed as:

[0045] (8)

[0046] In the formula, and This represents the relative density and calorific value of the mixed gas in the i-th node; and These are the relative density and calorific value of the gas flowing into the i-th node, respectively; and These represent the gas flow rates flowing into and out of the i-th node, respectively.

[0047] Construct equation (8) in matrix form:

[0048] (9)

[0049] In the formula, It is a coefficient matrix composed of pipeline gas flow rates; and These are the node relative density vector and the heat value vector, respectively; It is a column vector containing the sum of the products of relative density and air flow rate; It is a column vector containing the sum of the products of calorific value and gas flow rate;

[0050] The specific process of alternately solving the pressure-flow equation is as follows:

[0051] 1) Obtain the topology, pipeline parameters, and equilibrium node pressure parameters of the natural gas-hydrogen blending system; based on the non-equilibrium nodes, obtain the reduced-order node flow vectors. Dimension is , The number of nodes in a natural gas hydrogen blending system;

[0052] 2) Initialize nodal pressure, relative density, and calorific value;

[0053] 3) Based on the node pressure, relative density, and calorific value, the pipeline flow rate of the natural gas-hydrogen blending system is calculated using the pressure flow equation shown in equation (7). Construct the pipeline flow vector Then, the reduced-order node flow vector is solved. The residual between the calculated and actual flow values ​​at the nodes is obtained:

[0054] (10)

[0055] In the formula, Let be the column vector of node flow residuals, with dimension . ; The reduced-order node-branch incidence matrix has an order of [order missing]. ;

[0056] 4) Construct the nodal Jacobian matrix based on Newton's nodal method. for:

[0057] (11)

[0058] In the formula, The order is ; for A diagonal matrix of order 1; for The i-th element; for low-pressure natural gas systems, The pressure difference between the two nodes of the i-th pipeline; for medium and high pressure natural gas systems, The difference in squares of the air pressure at both ends of the i-th pipeline; The order of the matrix; the exponent. Take values ​​of 2, 1.848, and 1.854 respectively;

[0059] 5) From the Jacobian matrix Update node pressure:

[0060] (12)

[0061] In the formula, It is a Jacobian matrix; Let be a column vector consisting of nodal pressure corrections, with dimension . Low-pressure natural gas system for 3D node pressure column vector, medium-pressure and high-pressure natural gas systems Let be a column vector of squared nodal pressures, with dimension . ; Indicates the number of iterations; For the first The column vector of node flow residuals for the next iteration;

[0062] 6) Calculate the gas flow rate in the pipeline:

[0063] (13)

[0064] In the formula, This is the column vector of pipeline gas flow rate; The outflow node branch correlation matrix;

[0065] 7) Update the relative density of the mixed gas at each node according to equations (9) and (14). and calorific value Simultaneously update the relative density of the mixed gas in each pipeline. and calorific value :

[0066] (14)

[0067] In the formula, The inflow node branch correlation matrix;

[0068] 8) Calculate the maximum value of the iterative residual. ,like Not less than the set threshold If the result is positive, return to step 3) and continue iterating; otherwise, proceed to step 9).

[0069] (15)

[0070] In the formula, This indicates taking the modulus of a complex number or the absolute value of a real number.

[0071] 9) Flux distribution of the output natural gas hydrogen blending system.

[0072] Preferably, the present invention also provides a direct calculation device for the flow distribution of a natural gas hydrogen blending system, comprising:

[0073] The natural gas hydrogen blending system construction module is used to directly blend a set proportion of hydrogen into natural gas pipelines based on distributed hydrogen blending technology without the need for any gas mixing equipment, thus forming a natural gas hydrogen blending system.

[0074] The sludge mechanism model building module is used to establish a sludge mechanism model for a natural gas hydrogen blending system, taking into account the influence of two gas parameters, namely relative density and total calorific value, on sludge distribution;

[0075] The solution module is used to construct a pressure-fluidity equation that considers the relative density of the gas mixture in the pipeline and the calorific value of the gas mixture at each node. By iteratively updating the pressure, relative density, calorific value, relative density, and calorific value of the gas mixture at each node, as well as the relative density and calorific value of the gas mixture in each pipeline, the solution for the fluid distribution of the natural gas-hydrogen blending system is achieved.

[0076] Preferably, the present invention also provides an electronic device, including a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that the processor executes the computer program to implement the steps of a direct calculation method for the flow distribution of a natural gas hydrogen blending system.

[0077] Preferably, the present invention also provides a computer-readable storage medium storing a computer program thereon, which, when executed by a processor, implements the steps of the direct calculation method for the flow distribution of the natural gas hydrogen blending system.

[0078] Compared with the prior art, the beneficial effects of the technical solution of the present invention are:

[0079] 1. Improved the sludge mechanism model of integrated energy systems: From the perspective of natural gas hydrogen blending technology, this invention supplements and improves the existing sludge mechanism model of integrated energy systems. The sludge mechanism model of natural gas hydrogen blending system proposed in this invention can make up for the deficiencies of the existing sludge mechanism model of integrated energy systems. When describing the sludge distribution of natural gas with hydrogen, it considers the influence of changes in gas parameters such as relative density and total calorific value on the sludge distribution, effectively reflecting the influence of changes in gas properties after hydrogen blending on the flow distribution, which is more accurate than the traditional model based only on pressure difference.

[0080] 2. Improved the calculation method for backflow in integrated energy systems: From the perspective of natural gas hydrogen blending technology, the existing calculation model of integrated energy systems is supplemented and improved. The present invention adopts an alternating iterative solution method for the proposed gas pressure backflow equation, which can make up for the deficiencies of the existing integrated energy system backflow calculation model and realize the accurate solution of the backflow distribution of natural gas hydrogen blending.

[0081] 3. Supporting the efficient and high-quality development of integrated energy systems: With the development and utilization of a large amount of renewable energy such as green electricity and green hydrogen, the direct calculation method for the flow distribution of natural gas blending systems provided by this invention can, in the modeling stage, demonstrate as precisely as possible the impact of changes in gas quality parameters on the distribution of work capacity, providing a reliable model foundation for the operation scheduling and flow trading of integrated energy systems with a high proportion of new energy access; and providing a reliable decision-making basis for the deep coupling of high proportion of new energy (green hydrogen, green electricity) with natural gas systems.

[0082] 4. This invention eliminates the need for additional gas mixing equipment, achieving hydrogen injection directly within the pipeline through a distributed hydrogen blending method. This avoids the procurement and maintenance of centralized gas mixing devices, saving costs and construction complexity, and reducing on-site implementation difficulty and investment costs.

[0083] 5. This invention introduces three types of empirical equations: Lacey, Polyflow, and Panhandle A, and combines them with a unified potential concept to achieve integrated modeling of systems with different pressure levels. It has strong adaptability to multiple operating conditions and is applicable to low / medium / high pressure pipeline networks, thus enhancing the versatility of the method.

[0084] 6. By using the Newton-Nodal method to construct the Jacobian matrix and simultaneously update the air pressure and gas parameters, the residuals of the entire network can be converged to below the preset threshold within dozens of iterations, significantly improving the solution speed and computational efficiency.

[0085] 7. Detailed energy flow quality analysis can provide a reliable model basis for the operation and scheduling of integrated energy systems, load forecasting, and the design of energy trading mechanisms, thereby promoting the efficient and economical operation of the system.

[0086] In summary, the direct calculation method for the flow distribution of a natural gas hydrogen blending system provided by this invention offers important technical support for the development of future energy systems and has significant economic and social benefits. Attached Figure Description

[0087] Figure 1 A flowchart of the direct calculation method for the flow distribution in a natural gas hydrogen blending system.

[0088] Figure 2 This describes the iterative solution process for the air pressure flow equation.

[0089] Figure 3 This is a topology diagram of a natural gas hydrogen blending system for an example.

[0090] Figure 4 The flow distribution diagram is shown in the example of a natural gas hydrogen blending system. Detailed Implementation

[0091] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only for explaining the present invention and are not intended to limit the present invention.

[0092] Example 1

[0093] This embodiment provides a direct calculation method for the current distribution in a natural gas hydrogen blending system. The calculation process is as follows: Figure 1 As shown, it includes:

[0094] S1. No mixing equipment is required. A certain proportion of hydrogen is directly added into the natural gas pipeline through distributed hydrogen blending technology to form a natural gas hydrogen blending system.

[0095] In natural gas hydrogen blending systems obtained through distributed hydrogen blending technology, the gas parameters at each stage are closely related to the hydrogen mixing ratio. Therefore, this embodiment discusses the impact of the gas mixing process on the flow distribution in relation to distributed hydrogen blending technology.

[0096] S2. Establish a sludge mechanism model for a natural gas hydrogen blending system, taking into account the influence of gas parameters such as relative density and total calorific value on sludge distribution.

[0097] The crossflow mechanism model of a natural gas hydrogen blending system can be represented as follows:

[0098] (1)

[0099] In the formula, and These represent the gas power and gas flow rate transmitted through the pipeline, respectively; G is the total calorific value of the gas, which depends on the gas composition within the natural gas blending system.

[0100] Natural gas energy is measured in terms of thermal power. The fuel consumed by the gas load can be equivalent to the heat generated during gas combustion from ambient temperature to the theoretical combustion temperature. The gas flow rate... It can be determined by the energy mass coefficient of the gas. The product of gas power is expressed as:

[0101] (2)

[0102] In the formula, The ambient temperature; The theoretical combustion temperature of a gas is often limited by the heat resistance of combustion equipment, making it difficult for gas combustion in typical scenarios to reach this temperature. Therefore, the energy mass coefficient of natural gas, hydrogen, and mixed gases can be used as a reference. They are all considered to be the same constant.

[0103] Gas flow Can be represented as a variable With natural gas flow The product of:

[0104] (3)

[0105] variable The potential of a natural gas hydrogen blending system is expressed as the potential carried per unit gas flow rate, with units of (kW∙h) / m³. 3 It is closely related to the calorific value of the gas, specifically expressed as:

[0106] (4)

[0107] The pipeline loss in a natural gas hydrogen blending system can be expressed as the product of the potential difference between the two ends and the gas flow rate:

[0108] (5)

[0109] In the formula, For pipeline damage; and These represent the forces at both ends of the pipe.

[0110] S3. Construct a pressure-fluidity equation that considers the relative density of the gas mixture in the pipeline and the calorific value of the gas mixture at the nodes, in order to solve the flux distribution of the natural gas-hydrogen blending system.

[0111] 301. If the turbulent flow satisfies the generalized Kirchhoff's first law at the nodes, then the equilibrium equation for the turbulent flow at the nodes can be expressed as:

[0112] (6)

[0113] In the formula, The node's flow vector; The flow vector of the pipeline; The node-branch correlation matrix of the natural gas hydrogen blending system is of order . .

[0114] The nodal pressure-pipeline gas flow relationships for low, medium, and high-pressure natural gas hydrogen blending systems were constructed using the Lacey equation, Polyflo equation, and Panhandle A equation, respectively. Substituting equation (3) into the above three types of equations, the pressure-flow equations are obtained:

[0115] (7)

[0116] In the formula, and These represent the air pressure at both ends of the pipe; and These are the pipe diameter and length, respectively. This is the efficiency factor, typically taken as 0.8 to 1; The relative density of the gas mixture in the pipeline; The calorific value of the mixed gas at the node; The energy mass coefficient of the gas mixture; For the sake of momentum; Natural gas flow rate; index We take 2, 1.848 and 1.854 respectively.

[0117] Assuming the gases flowing into the node are completely mixed, the gases flowing out of the node all have the same relative density and calorific value. The relative density and calorific value of the mixed gases at the node can be expressed as:

[0118] (8)

[0119] In the formula, and This represents the relative density and calorific value of the mixed gas in the i-th node; and These are the relative density and calorific value of the gas flowing into the i-th node, respectively; and These represent the gas flow rates flowing into and out of the i-th node, respectively.

[0120] Construct equation (8) in matrix form:

[0121] (9)

[0122] In the formula, It is a coefficient matrix composed of pipeline gas flow rates; and These are the node relative density vector and the heat value vector, respectively; It is a column vector containing the sum of the products of relative density and air flow rate; It is a column vector containing the sum of the products of calorific value and gas flow rate.

[0123] The process of alternately solving the pressure-flow equation is as follows: Figure 2 As shown, the specific steps are as follows:

[0124] 1) Obtain the topology, pipeline parameters, and equilibrium node pressure of the natural gas-hydrogen blending system; based on the non-equilibrium node flow vector, obtain the reduced-order node flow vector. Dimension is , This represents the number of nodes in a natural gas hydrogen blending system.

[0125] 2) Initialize the node pressure, relative density, and calorific value.

[0126] 3) Based on the node pressure, relative density, and calorific value, the pipeline flow rate of the natural gas-hydrogen blending system is calculated using the pressure flow equation shown in equation (7). Construct the pipeline flow vector Then, the reduced-order node flow vector is solved. The residual between the calculated and actual flow values ​​at the nodes is obtained:

[0127] (10)

[0128] In the formula, Let be the column vector of node flow residuals, with dimension . ; The reduced-order node-branch incidence matrix has an order of [order missing]. .

[0129] 4) Construct the nodal Jacobian matrix based on Newton's nodal method. for:

[0130] (11)

[0131] In the formula, The order is ; for A diagonal matrix of order 1; for The i-th element; for low-pressure natural gas systems, The pressure difference between the two nodes of the i-th pipeline; for medium and high pressure natural gas systems, It is the difference in squares of the air pressure at both ends of the i-th pipeline. The order of the matrix; the exponent. We take 2, 1.848 and 1.854 respectively.

[0132] 5) From the Jacobian matrix Update node pressure:

[0133] (12)

[0134] In the formula, It is a Jacobian matrix; Let be a column vector consisting of nodal pressure corrections, with dimension . Low-pressure natural gas system for 3D node pressure column vector, medium-pressure and high-pressure natural gas systems Let be a column vector of squared nodal pressures, with dimension . ; Indicates the number of iterations; For the first The column vector of node flow residuals for the next iteration;

[0135] 6) Calculate the gas flow rate in the pipeline:

[0136] (13)

[0137] In the formula, This is the column vector of pipeline gas flow rate; This is the branch association matrix of the outflow node.

[0138] 7) Update the relative density of the mixed gas at each node according to equations (9) and (14). and calorific value Simultaneously update the relative density of the mixed gas in each pipeline. and calorific value :

[0139] (14)

[0140] In the formula, This is the inflow node branch correlation matrix.

[0141] 8) Calculate the maximum value of the iterative residual. ,like Not less than the set threshold If the result is positive, return to step 3) and continue iterating; otherwise, proceed to step 9).

[0142] (15)

[0143] In the formula, This indicates taking the modulus of a complex number or the absolute value of a real number.

[0144] 9) Flux distribution of the output natural gas hydrogen blending system.

[0145] Example 2

[0146] This embodiment provides a supplementary explanation of the direct calculation method for the current distribution in the natural gas hydrogen blending system, based on specific applications and data, as follows:

[0147] The direct calculation method for the backflow distribution of the natural gas hydrogen blending system proposed in this embodiment is applied to an embodiment of a natural gas hydrogen blending system with 5 natural gas nodes and 1 distributed hydrogen injection node, to perform backflow calculation of the natural gas hydrogen blending system and verify the effectiveness of the invention.

[0148] The natural gas hydrogen blending system topology used in this embodiment is as follows: Figure 3 As shown in Table 1, the pipeline parameters for the natural gas-hydrogen blending system include 5 natural gas nodes and 1 distributed hydrogen injection node. The low-pressure 6-node annular natural gas-hydrogen blending system has a gas source node G1 with a pressure of 75 mbar; distributed hydrogen blending is directly injected into the natural gas pipeline network from node G5. The calorific values ​​of natural gas and hydrogen are 45.574 MJ / m³. 3 and 12.750 MJ / m 3 The relative densities are 0.6048 and 0.0696, respectively.

[0149] Table 1 Piping parameters for natural gas hydrogen blending system

[0150]

[0151] Table 2 Natural Gas Node Load

[0152]

[0153] The relative density and total calorific value of each node in the natural gas hydrogen blending system are shown in Table 3 after calculation. It can be seen that directly blending hydrogen into the natural gas pipeline leads to changes in the gas quality conditions such as the relative density and total calorific value of each node.

[0154] Table 3. Relative density and total calorific value of natural gas nodes

[0155]

[0156] The current distribution of the natural gas hydrogen blending system is as follows Figure 4 As shown, the bolded numbers represent node vortex flow, and the non-bolded numbers represent pipeline vortex flow. Each node satisfies vortex flow balance, verifying the accuracy of the vortex flow mechanism model and direct solution method for the natural gas hydrogen blending system proposed in this invention. Meanwhile, changes in gas quality conditions further affect the vortex flow distribution of the natural gas hydrogen blending system. Node G6 (hydrogen station) injects a larger volume of hydrogen into the pipeline, but its vortex flow into the pipeline is lower.

[0157] Example 3

[0158] Preferably, embodiments of this application also provide a direct calculation device for the flow distribution of a natural gas hydrogen blending system, comprising:

[0159] The natural gas hydrogen blending system construction module is used to directly blend a set proportion of hydrogen into natural gas pipelines based on distributed hydrogen blending technology without the need for any gas mixing equipment, thus forming a natural gas hydrogen blending system.

[0160] The swirling flow mechanism model building module is used to establish a swirling flow mechanism model for a natural gas hydrogen blending system, taking into account the influence of two gas parameters, namely gas flow rate and total calorific value, on swirling flow distribution.

[0161] The solution module is used to construct a pressure-fluidity equation that considers the relative density of the gas mixture in the pipeline and the calorific value of the gas mixture at each node. By iteratively updating the pressure, relative density, calorific value, relative density, and calorific value of the gas mixture at each node, as well as the relative density and calorific value of the gas mixture in each pipeline, the solution for the fluid distribution of the natural gas-hydrogen blending system is achieved.

[0162] Example 4

[0163] Preferably, embodiments of this application also provide a specific implementation of an electronic device capable of implementing all steps in the direct calculation method for the flow distribution of the natural gas hydrogen blending system described in the above embodiments. The electronic device specifically includes the following:

[0164] Processor, memory, communications interface, and bus;

[0165] The processor, memory, and communication interface communicate with each other via a bus; the communication interface is used to realize information transmission between server-side devices, metering devices, and user-side devices.

[0166] The processor is used to call the computer program in the memory. When the processor executes the computer program, it implements all the steps in the direct calculation method of the current distribution of the natural gas hydrogen blending system in the above embodiments.

[0167] Example 5

[0168] Embodiments of this application also provide a computer-readable storage medium capable of implementing all steps of the multi-objective extended planning method for integrated energy systems that takes into account differences in local work capacity as described in the above embodiments. The computer-readable storage medium stores a computer program that, when executed by a processor, implements all steps of the direct calculation method for the current distribution of a natural gas-hydrogen blending system as described in the above embodiments.

[0169] The various embodiments in this specification are described in a progressive manner. Similar or identical parts between embodiments can be referred to interchangeably. Each embodiment focuses on its differences from other embodiments. In particular, hardware + program embodiments are relatively simple in description because they are fundamentally similar to method embodiments; relevant parts can be referred to the descriptions in the method embodiments.

[0170] The foregoing has described specific embodiments of this specification. Other embodiments are within the scope of the appended claims. In some cases, the actions or steps recited in the claims may be performed in a different order than that shown in the embodiments and may still achieve the desired result. Furthermore, the processes depicted in the drawings do not necessarily require the specific or sequential order shown to achieve the desired result. In some embodiments, multitasking and parallel processing are possible or may be advantageous.

[0171] While this application provides method operation steps as shown in the embodiments or flowcharts, more or fewer operation steps may be included based on conventional or non-inventive labor. The order of steps listed in the embodiments is merely one possible execution order among many and does not represent the only execution order. In actual device or client product execution, the method can be executed in the order shown in the embodiments or drawings or in parallel (e.g., in a parallel processor or multi-threaded processing environment).

[0172] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0173] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0174] Unless otherwise specified, the model numbers of the various devices in this embodiment of the invention are not limited, and any device that can perform the above functions is acceptable.

[0175] Those skilled in the art will understand that the accompanying drawings are merely schematic diagrams of a preferred embodiment, and the sequence numbers of the above embodiments of the present invention are for descriptive purposes only and do not represent the superiority or inferiority of the embodiments.

[0176] This invention is not limited to the embodiments described above. The above description of specific embodiments is intended to illustrate and explain the technical solutions of this invention. The specific embodiments described above are merely illustrative and not restrictive. Without departing from the spirit and scope of the claims, those skilled in the art can make many specific modifications based on the teachings of this invention, and these modifications all fall within the scope of protection of this invention.

Claims

1. A method for directly calculating the current distribution in a natural gas hydrogen blending system, characterized in that, include: S1. Based on distributed hydrogen blending technology, without the aid of any gas mixing equipment, hydrogen is directly blended into the natural gas pipeline in a preset proportion to form a natural gas hydrogen blending system; S2. Establish a sludge mechanism model for a natural gas hydrogen blending system, taking into account the influence of two gas parameters, relative density and total calorific value, on sludge distribution; S3. Construct a pressure-fluidity equation that considers the relative density of the mixed gas in the pipeline and the calorific value of the mixed gas at the nodes. By iteratively updating the pressure, relative density, calorific value, relative density of the mixed gas at each node, and calorific value of the mixed gas in each pipeline in the pressure-fluidity equation, the fluid distribution of the natural gas-hydrogen blending system can be solved.

2. The direct calculation method for the flow distribution of a natural gas hydrogen blending system according to claim 1, characterized in that, The flow mechanism model described in step S2 is obtained through: The gas power is determined by multiplying the total calorific value of the gas by the gas flow rate. The potential of a natural gas-hydrogen blending system is expressed as the product of gas power and the energy mass coefficient of the gas. Pipeline loss is represented by the product of the potential difference at both ends of the pipe and the airflow rate. To achieve a quantitative description of the changes in gas and gas parameters before and after hydrogen doping.

3. The direct calculation method for the current distribution in a natural gas hydrogen blending system according to claim 1, characterized in that, In step S3, the pressure-flow equations considering the relative density of the pipeline gas mixture and the calorific value of the node gas mixture are adopted. Specifically, the Lacey equation for low-pressure natural gas systems, the Polyflow equation for medium-pressure natural gas systems, and the Panhandle A equation for high-pressure natural gas systems are adopted respectively. The potential expression is introduced into the above equations to describe the node gas pressure-pipeline gas flow relationship under different operating conditions.

4. The direct calculation method for the flow distribution of a natural gas hydrogen blending system according to claim 1, characterized in that, In step S3, assuming that the gases flowing into the same node are fully mixed, the relative density and calorific value of the mixed gas at the node are calculated by weighted average of the gas flow rate of each branch and the corresponding gas quality parameters.

5. The direct calculation method for the flow distribution of a natural gas hydrogen blending system according to claim 1, characterized in that, The iterative solution of the pressure-flow equation in step S3 uses Newton's nodal method, specifically including: Construct a node Jacobian matrix based on residuals; Update the nodal pressure or its square until the residual converges; The relative density and calorific value of the mixed gas at each node and in each pipeline are updated synchronously. Repeat the iteration until the residual current of the natural gas hydrogen blending system is lower than the set threshold.

6. The direct calculation method for the flow distribution of a natural gas hydrogen blending system according to claim 1 or 2, characterized in that, In step S2, The flow mechanism model of the natural gas hydrogen blending system is expressed as follows: (1) In the formula, and These represent the gas power and gas flow rate transmitted through the pipeline, respectively; G is the total calorific value of the gas, which depends on the gas composition within the natural gas blending system. Natural gas energy is measured by thermal power. The fuel consumed by the gas load is equivalent to the heat generated during gas combustion from ambient temperature to the theoretical combustion temperature; the gas flow rate... The energy mass coefficient of a gas can be determined by its energy mass coefficient. The product of gas power is expressed as: ； (2) In the formula, The ambient temperature; The theoretical combustion temperature of the gas is given by the energy mass coefficient of natural gas, hydrogen, and the mixture. They are all considered to be the same constant; Gas flow Represented as variables With natural gas flow The product of: ； (3) variable The potential of a natural gas hydrogen blending system is expressed as the potential carried per unit gas flow rate, with units of (kW∙h) / m³. 3 It is related to the calorific value of the gas, specifically expressed as: ； (4) The pipeline loss in a natural gas-hydrogen blending system is expressed as the product of the potential difference between the two ends and the gas flow rate: ； (5) In the formula, For pipeline damage; and These represent the forces at both ends of the pipe.

7. The method for directly calculating the flow distribution of a natural gas hydrogen blending system according to claim 1, 3, 4, or 5, characterized in that, In step S3, If the turbulent flow satisfies the generalized Kirchhoff's first law at the nodes, then the equilibrium equation for the turbulent flow at the nodes can be expressed as: ； (6) In the formula, The node's flow vector; The flow vector of the pipeline; The node-branch correlation matrix of the natural gas hydrogen blending system is as follows: 1-th order matrix, Let be the order of the matrix; The nodal pressure-pipeline gas flow relationships for low, medium, and high-pressure natural gas hydrogen blending systems were constructed using the Lacey equation, Polyflo equation, and Panhandle A equation, respectively. Substituting the above three types of equations, we obtain the pressure-flow equation: ； (7) In the formula, and These represent the air pressure at both ends of the pipe; and These are the pipe diameter and length, respectively. The efficiency factor is set to 0.8~1; The relative density of the gas mixture in the pipeline; The calorific value of the mixed gas at the node; The energy mass coefficient of the gas mixture; The flow vector of the pipeline; For the sake of momentum, Natural gas flow rate; index Take values ​​of 2, 1.848, and 1.854 respectively; Assuming the gases flowing into the node are completely mixed, the gases flowing out of the node all have the same relative density and calorific value. The relative density and calorific value of the mixed gases at the node are expressed as: ； (8) In the formula, and This represents the relative density and calorific value of the mixed gas in the i-th node; and These are the relative density and calorific value of the gas flowing into the i-th node, respectively; and These represent the gas flow rates flowing into and out of the i-th node, respectively. Construct equation (8) in matrix form: ； (9) In the formula, It is a coefficient matrix composed of pipeline gas flow rates; and These are the node relative density vector and the heat value vector, respectively; It is a column vector containing the sum of the products of relative density and air flow rate; It is a column vector containing the sum of the products of calorific value and gas flow rate; The specific process of alternately solving the pressure-flow equation is as follows: 1) Obtain the topology, pipeline parameters, and equilibrium node pressure parameters of the natural gas-hydrogen blending system; based on the non-equilibrium nodes, obtain the reduced-order node flow vectors. Dimension is , The number of nodes in a natural gas hydrogen blending system; 2) Initialize nodal pressure, relative density, and calorific value; 3) Based on the node pressure, relative density, and calorific value, the pipeline flow rate of the natural gas-hydrogen blending system is calculated using the pressure flow equation shown in equation (7). Construct the pipeline flow vector Then, the reduced-order node flow vector is solved. The residual between the calculated and actual flow values ​​at the nodes is obtained: ； (10) In the formula, Let be the column vector of node flow residuals, with dimension . ; The reduced-order node-branch incidence matrix has an order of [order missing]. ; 4) Construct the nodal Jacobian matrix based on Newton's nodal method. for: ； (11) In the formula, The order is ; for A diagonal matrix of order 1; for The i-th element; For low-pressure natural gas systems The pressure difference between the two nodes of the i-th pipeline; for medium and high pressure natural gas systems, The difference in squares of the air pressure at both ends of the i-th pipeline; The order of the matrix; the exponent. Take values ​​of 2, 1.848, and 1.854 respectively; 5) From the Jacobian matrix Update node pressure: ； (12) In the formula, It is a Jacobian matrix; Let be a column vector consisting of nodal pressure corrections, with dimension . Low-pressure natural gas system for 3D node pressure column vector, medium-pressure and high-pressure natural gas systems Let be a column vector of squared nodal pressures, with dimension . ; Indicates the number of iterations; For the first The column vector of node flow residuals for the next iteration; 6) Calculate the gas flow rate in the pipeline: ； (13) In the formula, This is the column vector of pipeline gas flow rate; The outflow node branch correlation matrix; 7) Update the relative density of the mixed gas at each node according to equations (9) and (14). and calorific value Simultaneously update the relative density of the mixed gas in each pipeline. and calorific value : ； (14) In the formula, The inflow node branch correlation matrix; 8) Calculate the maximum value of the iterative residual. ,like Not less than the set threshold If the iteration fails, return to step 3) and continue the iteration. Otherwise, proceed to step 9); ； (15) In the formula, This indicates taking the modulus of a complex number or the absolute value of a real number. 9) Flux distribution of the output natural gas hydrogen blending system.

8. A device for directly calculating the current distribution in a natural gas hydrogen blending system, characterized in that, include: The natural gas hydrogen blending system construction module is used to directly blend a set proportion of hydrogen into natural gas pipelines based on distributed hydrogen blending technology without the need for any gas mixing equipment, thus forming a natural gas hydrogen blending system. The sludge mechanism model building module is used to establish a sludge mechanism model for a natural gas hydrogen blending system, taking into account the influence of two gas parameters, namely relative density and total calorific value, on sludge distribution; The solution module is used to construct a pressure-fluidity equation that considers the relative density of the gas mixture in the pipeline and the calorific value of the gas mixture at each node. By iteratively updating the pressure, relative density, calorific value, relative density, and calorific value of the gas mixture at each node, as well as the relative density and calorific value of the gas mixture in each pipeline, the solution for the fluid distribution of the natural gas-hydrogen blending system is achieved.

9. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, When the processor executes the computer program, it implements the steps of the direct calculation method for the flow distribution of the natural gas hydrogen blending system according to any one of claims 1 to 7.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that, When executed by a processor, the computer program implements the steps of the direct calculation method for the flow distribution of the natural gas hydrogen blending system according to any one of claims 1 to 7.

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