Pressure loss calculation method in slurry hydrogen pipeline conveying process

Abstract

The invention discloses a pressure loss calculation method in a slurry hydrogen pipeline conveying process, and relates to the technical field of hydrogen energy conveying, and the pressure loss calculation method comprises the following steps: S1, slurry hydrogen pipeline basic design parameters are obtained, and the basic design parameters comprise the conveying capacity, the pipe length, the inlet and outlet temperature and the solid hydrogen content; s2, looking up a table to calculate the density of the slurry hydrogen fluid, and testing yield stress and viscosity parameters of the slurry hydrogen fluid through experiments; s3, calculating the Hertz number, the critical flow nuclear radius ratio and the Bingham Reynolds number of the slurry hydrogen pipeline transportation system; s4, calculating the critical Reynolds number of the slurry hydrogen system in transition from laminar flow to turbulent flow, and carrying out flow state discrimination; the method is established on the basis of the relation among the Van Ning friction resistance factor, the critical Reynolds number and the Hirschner number, a simple and effective calculation method is provided for hydraulic design, equipment model selection, operation management and the like of the slurry hydrogen pipeline, and compared with common flow numerical simulation calculation, complex modeling, grid division and particle dynamics numerical theories are avoided, and the method has the advantages that the method is simple and practical. And the calculation efficiency is effectively improved.

Description

Technical Field

[0001] The present invention relates to the technical field of hydrogen energy transportation, and in particular to a method for calculating pressure loss in a slurry hydrogen pipeline transportation process. Background Art

[0002] Slurry hydrogen is a mixture of solid and liquid hydrogen. Compared with liquid hydrogen, slurry hydrogen has higher density and heat capacity. In addition to the advantages of general introduction of slurry, slurry hydrogen has lower evaporation rate and loss, as well as higher storage density compared with liquid and gaseous hydrogen. Slurry hydrogen pipeline is a key link in the hydrogen energy industry chain. Its development is of great significance to the widespread application of hydrogen energy and the transformation of energy structure. With the continuous advancement of technology and the reduction of costs, it is expected that slurry hydrogen pipeline will be more widely used and developed worldwide in the future.

[0003] However, during the flow of slurry hydrogen in the pipe, the friction between the slurry and the inner wall of the pipe, the collision of solid particles inside the slurry, and the sedimentation of particle monomers due to gravity will all cause pipeline pressure loss, reduce pipeline transportation efficiency, increase energy consumption of power equipment, and affect system operating stability. Therefore, it is extremely necessary to analyze and calculate the resistance loss of the slurry hydrogen transportation pipeline for the design of slurry hydrogen pipeline. For this purpose, a method for calculating pressure loss during slurry hydrogen pipeline transportation is proposed. Summary of the invention

[0004] The purpose of the present invention is to solve the problems in the prior art and to propose a method for calculating the pressure loss in the process of slurry hydrogen pipeline transportation.

[0005] A method for calculating pressure loss during slurry hydrogen pipeline transportation comprises the following steps:

[0006] S1. Obtain the basic design parameters of the slurry hydrogen pipeline, which include the flow rate, pipe length, inlet and outlet temperatures, and solid hydrogen content;

[0007] S2. Calculate the density of the slurry hydrogen fluid by looking up the table, and test the yield stress and viscosity parameters of the slurry hydrogen fluid experimentally;

[0008] S3. Calculate the Hershel number, critical flow core radius ratio and Bingham Reynolds number of the slurry hydrogen pipeline system;

[0009] S4. Calculate the critical Reynolds number of the transition from laminar flow to turbulent flow in the slurry hydrogen system and identify the flow state;

[0010] S5. Calculate the Fanning friction factor and slurry hydrogen pipeline pressure drop under the corresponding flow state.

[0011] Preferably, in step S2, the table lookup to calculate the density of the slurry hydrogen fluid includes the following steps:

[0012] (1) Determine the solid hydrogen content and fluid temperature at the inlet and outlet positions;

[0013] (2) Based on the solid hydrogen content-density relationship diagram, infer the density at the inlet and outlet of the slurry hydrogen pipeline;

[0014] (3) Finally, the average value is taken to calculate the density of the slurry hydrogen fluid.

[0015] Preferably, in step S2, when the yield stress and viscosity parameters of the slurry hydrogen fluid are experimentally tested, the yield stress and viscosity of the slurry are obtained by rheological experiments, wherein the shear stress in the yield stress test program is set with reference to the actual pipeline transportation to set the stress loading range and rate, the turning point of the stress-strain curve obtained by the test is the yield stress, and the shear rate set in the viscosity test program should be similar to the pipe wall shear.

[0016] Preferably, in step S3, the specific steps of calculating the Hershel number, critical flow core radius ratio and Bingham Reynolds number parameters of the slurry hydrogen pipeline system include:

[0017] The calculation formula of Hersh number He is as follows:

[0018]

[0019] Where ρ is the density of slurry hydrogen (kg / m 3 ), τ B is the slurry hydrogen yield stress (Pa), D is the pipe diameter (m), and η is the slurry hydrogen viscosity (Pa·s);

[0020] Critical flow core radius ratio a c The calculation formula is as follows:

[0021]

[0022] The Bingham Reynolds number Reb is calculated as follows:

[0023]

[0024] Wherein, V is the flow rate of the slurry hydrogen pipe flow (m / s).

[0025] Preferably, in step S4, the specific steps of calculating the critical Reynolds number for the transition from laminar flow to turbulent flow in the slurry hydrogen pipeline system and distinguishing the flow state include:

[0026] Critical Reynolds number Reb c The calculation formula is as follows:

[0027]

[0028] Flow state identification:

[0029] If Reb <Reb c , then the fluid in the slurry hydrogen tube is in laminar flow state;

[0030] If Reb ≥ Reb c , the fluid in the slurry hydrogen tube is in a turbulent state.

[0031] Preferably, in step S5, the specific steps of calculating the Fanning friction factor and pressure drop of the slurry hydrogen pipeline system include:

[0032] The Fanning friction factor f under laminar flow is calculated by the following formula:

[0033]

[0034] The Fanning friction factor f in turbulent state is calculated by the following formula:

[0035]

[0036] In the formula, Reb t is the corrected Bingham Reynolds number, which is calculated by the following formula:

[0037]

[0038] The final slurry hydrogen pipeline pressure drop △P is calculated by the following formula:

[0039]

[0040] Where L is the tube length.

[0041] Compared with the prior art, the present invention has the following advantages:

[0042] The present invention is based on the relationship between the Fanning friction factor and the critical Reynolds number and Hershel number, and provides a simple and effective calculation method for the hydraulic design, equipment selection and operation management of slurry hydrogen pipelines. Compared with the commonly used flow numerical simulation calculations, it avoids complex modeling, meshing, and particle dynamics numerical theory, and effectively improves the calculation efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 The present invention is a flow chart of a method for calculating pressure loss during slurry hydrogen pipeline transportation. DETAILED DESCRIPTION

[0044] In order to make the technical means, creative features, objectives and effects achieved by the present invention easy to understand, the present invention is further explained below in conjunction with specific implementation methods.

[0045] Reference Figure 1 As shown, a method for calculating pressure loss during slurry hydrogen pipeline transportation includes the following steps:

[0046] S1. Obtain the basic design parameters of the slurry hydrogen pipeline, which include the flow rate, pipe length, inlet and outlet temperatures, and solid hydrogen content;

[0047] S2. Calculate the density of the slurry hydrogen fluid by looking up the table, and test the yield stress and viscosity parameters of the slurry hydrogen fluid experimentally;

[0048] S3. Calculate the Hershel number, critical flow core radius ratio and Bingham Reynolds number of the slurry hydrogen pipeline system;

[0049] S4. Calculate the critical Reynolds number of the transition from laminar flow to turbulent flow in the slurry hydrogen system and identify the flow state;

[0050] S5. Calculate the Fanning friction factor and slurry hydrogen pipeline pressure drop under the corresponding flow state.

[0051] In step S2, the table lookup to calculate the density of the slurry hydrogen fluid includes the following steps:

[0052] (1) Determine the solid hydrogen content and fluid temperature at the inlet and outlet positions;

[0053] (2) Based on the solid hydrogen content-density relationship diagram, infer the density at the inlet and outlet of the slurry hydrogen pipeline;

[0054] (3) Finally, the average value is taken to calculate the density of the slurry hydrogen fluid.

[0055] In step S2, when the yield stress and viscosity parameters of the slurry hydrogen fluid are experimentally tested, the yield stress and viscosity of the slurry are obtained by rheological experiments, wherein the shear stress in the yield stress test program is set with reference to the actual pipeline transportation to set the stress loading range and rate, the turning point of the stress-strain curve obtained by the test is the yield stress, and the shear rate set in the viscosity test program should be similar to the pipe wall shear.

[0056] In step S3, the specific steps of calculating the Hershel number, critical flow core radius ratio and Bingham Reynolds number parameters of the slurry hydrogen pipeline system include:

[0057] The calculation formula of Hersh number He is as follows:

[0058]

[0059] Where ρ is the density of slurry hydrogen (kg / m 3 ), τ B is the slurry hydrogen yield stress (Pa), D is the pipe diameter (m), and η is the slurry hydrogen viscosity (Pa·s);

[0060] Critical flow core radius ratio a c The calculation formula is as follows:

[0061]

[0062] The Bingham Reynolds number Reb is calculated as follows:

[0063]

[0064] Wherein, V is the flow rate of the slurry hydrogen pipe flow (m / s).

[0065] In step S4, the specific steps of calculating the critical Reynolds number for the transition from laminar flow to turbulent flow in the slurry hydrogen pipeline system and distinguishing the flow state include:

[0066] Critical Reynolds number Reb c The calculation formula is as follows:

[0067]

[0068] Flow state identification:

[0069] If Reb <Reb c , then the fluid in the slurry hydrogen tube is in laminar flow state;

[0070] If Reb ≥ Reb c , the fluid in the slurry hydrogen tube is in a turbulent state.

[0071] In step S5, the specific steps of calculating the Fanning friction factor and pressure drop of the slurry hydrogen pipeline system include:

[0072] The Fanning friction factor f under laminar flow is calculated by the following formula:

[0073]

[0074] The Fanning friction factor f in turbulent state is calculated by the following formula:

[0075]

[0076] In the formula, Reb t is the corrected Bingham Reynolds number, which is calculated by the following formula:

[0077]

[0078] The final slurry hydrogen pipeline pressure drop △P is calculated by the following formula:

[0079]

[0080] Where L is the tube length.

[0081] Example

[0082] This embodiment uses the calculation method of the present invention to calculate and analyze the pressure loss of the slurry hydrogen pipeline design between a liquid hydrogen station and a hydrogenation station. The length of the pipeline used in the pipeline transportation process is 60m, the solid hydrogen content varies in the range of 20% to 55%, and the designed transmission volume is 8m 3 / h, the tank inlet pressure is 0.15MPa, and the calculation process is as follows:

[0083] (1) Analysis of shear force and other parameter settings required for rheological test

[0084] It is assumed that the solid hydrogen particles are dispersed in the liquid phase to form a stable slurry, and the slurry exhibits Bingham flow characteristics during pipeline transportation.

[0085] The constitutive equation of the slurry is:

[0086]

[0087] Where:

[0088] γ is the shear rate, s-1;

[0089] τ is shear stress, Pa;

[0090] τ B is the yield stress, Pa;

[0091] η is viscosity, Pa·s.

[0092] For the case of solid-hydrogen flow mixture inside a circular tube, we use the "annular microelement method" to perform mechanical analysis, thereby revealing the shear stress characteristics of the slurry hydrogen fluid at a point with a radial distance r from the central axis of the tube cavity (i.e., the geometric center axis of the tube).

[0093]

[0094] Where: Δp / L——resistance loss per unit pipe length (Pa / m). After integrating the above formula, we can get the velocity distribution V of the pipe flow:

[0095]

[0096] Finally, according to the table and experiment, the yield stress τ of slurry hydrogen with a solid hydrogen content of 20%-55% is B =400Pa, viscosity η=2.6Pa·s.

[0097] (2) Friction loss calculation

[0098] Flow state determination Reb>Reb c , which is laminar flow;

[0099] The corrected Bingham Reynolds number Reb = 58.3, the friction factor f = 0.5, so the pipeline pressure drop can be calculated by the following formula:

[0100]

[0101] Pipeline pressure drop ΔP = 0.067MPa.

[0102] It is known from common technical knowledge that the present invention can be implemented by other embodiments that do not deviate from its spirit or essential features. Therefore, the above disclosed embodiments are only illustrative in all respects and are not exclusive. All changes within the scope of the present invention or within the scope equivalent to the present invention are included in the present invention.

Claims

1. A method for calculating pressure loss during slurry hydrogen pipeline transportation, characterized in that: The following steps are involved: S1. Obtain the basic design parameters of the slurry hydrogen pipeline, which include the flow rate, pipe length, inlet and outlet temperatures, and solid hydrogen content; S2. Calculate the density of the slurry hydrogen fluid by looking up the table, and test the yield stress and viscosity parameters of the slurry hydrogen fluid experimentally; S3. Calculate the Hershel number, critical flow core radius ratio and Bingham Reynolds number of the slurry hydrogen pipeline system; S4. Calculate the critical Reynolds number of the transition from laminar flow to turbulent flow in the slurry hydrogen system and identify the flow state; S5. Calculate the Fanning friction factor and slurry hydrogen pipeline pressure drop under the corresponding flow state.

2. The method for calculating pressure loss during slurry hydrogen pipeline transportation according to claim 1, characterized in that: In step S2, the table lookup to calculate the density of the slurry hydrogen fluid includes the following steps: (1) Determine the solid hydrogen content and fluid temperature at the inlet and outlet positions; (2) Based on the solid hydrogen content-density relationship diagram, infer the density at the inlet and outlet of the slurry hydrogen pipeline; (3) Finally, the average value is taken to calculate the density of the slurry hydrogen fluid.

3. The method for calculating pressure loss during slurry hydrogen pipeline transportation according to claim 1, characterized in that: In step S2, when the yield stress and viscosity parameters of the slurry hydrogen fluid are experimentally tested, the yield stress and viscosity of the slurry are obtained by rheological experiments, wherein the shear stress in the yield stress test program is set with reference to the actual pipeline transportation to set the stress loading range and rate, the turning point of the stress-strain curve obtained by the test is the yield stress, and the shear rate set in the viscosity test program should be similar to the pipe wall shear.

4. The method for calculating pressure loss during slurry hydrogen pipeline transportation according to claim 1, characterized in that: In step S3, the specific steps of calculating the Hershel number, critical flow core radius ratio and Bingham Reynolds number parameters of the slurry hydrogen pipeline system include: The calculation formula of Hersh number He is as follows: Where ρ is the density of slurry hydrogen (kg / m 3 ), τ B is the slurry hydrogen yield stress (Pa), D is the pipe diameter (m), and η is the slurry hydrogen viscosity (Pa·s); Critical flow core radius ratio a c The calculation formula is as follows: The Bingham Reynolds number Reb is calculated as follows: Wherein, V is the flow rate of the slurry hydrogen pipe flow (m / s).

5. The method for calculating pressure loss during slurry hydrogen pipeline transportation according to claim 4, characterized in that: In step S4, the specific steps of calculating the critical Reynolds number for the transition from laminar flow to turbulent flow in the slurry hydrogen pipeline system and distinguishing the flow state include: Critical Reynolds number Reb c The calculation formula is as follows: Flow state identification: If Reb <Reb c , then the fluid in the slurry hydrogen tube is in laminar flow state; If Reb ≥ Reb c , the fluid in the slurry hydrogen tube is in a turbulent state.

6. The method for calculating pressure loss during slurry hydrogen pipeline transportation according to claim 5, characterized in that: In step S5, the specific steps of calculating the Fanning friction factor and pressure drop of the slurry hydrogen pipeline system include: The Fanning friction factor f under laminar flow is calculated by the following formula: The Fanning friction factor f in turbulent state is calculated by the following formula: In the formula, Reb t is the corrected Bingham Reynolds number, which is calculated by the following formula: The final slurry hydrogen pipeline pressure drop △P is calculated by the following formula: Where L is the tube length.

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