Method for determining fireproof spacing of hydrogen pipeline station based on consequence comparison

Abstract

The invention discloses a hydrogen pipeline station fireproof spacing determination method based on consequence comparison, and belongs to the technical field of hydrogen pipeline station safety protection, and the method comprises the steps: collecting design parameters of a pipeline at a hydrogen station and basic parameters of gas flowing through the pipeline, and introducing a pressure correction coefficient to calculate hydrogen station correction pressure, determining a leakage aperture; calculating the maximum leakage flow of the pipeline under the condition of non-cut leakage according to the determined leakage hole diameter and the calculated maximum leakage flow; calculating the flame length when a fire disaster is caused after horizontal leakage, and calculating the thermal radiation influence distance of the flame to the surrounding environment; and calculating the external fireproof distance of the hydrogen pipeline station according to the thermal radiation influence distance. According to physical properties of hydrogen and natural gas, an operation pressure corrected hydrogen / natural gas leakage model is provided, a hydrogen / natural gas leakage consequence (fire) influence model is established, and the hydrogen pipeline station fire-proof spacing is determined by comparing hydrogen and natural gas heat radiation influence ranges.

Description

Technical Field

[0001] This application belongs to the field of hydrogen pipeline station safety protection technology, and in particular relates to a method for determining the fire prevention distance of hydrogen pipeline stations based on consequence comparison. Background Technology

[0002] Hydrogen, as a key development direction for new energy sources, boasts significant advantages over traditional fossil fuels, including high calorific value, environmentally friendly combustion products, wide availability, and renewability. It is hailed as a clean energy source of the future and will become a new pathway for humanity to address increasingly severe energy and environmental challenges. Currently, utilizing hydrogen pipelines for transportation is an efficient and large-scale storage and transportation method for hydrogen energy. This includes the construction of new hydrogen pipelines and hydrogen pipeline stations.

[0003] Compared to natural gas (which mainly contains methane), hydrogen has a wider explosion range, lower ignition energy, and higher thermal energy per unit mass. In terms of the main functional configuration of pipeline stations, hydrogen pipeline stations are basically the same as natural gas pipeline stations, mainly including dust removal, metering, and pellet launching / receiving units (the configuration varies depending on the station's function).

[0004] Hydrogen stations generally operate at higher pressures (hydrogen production and storage pressures can exceed 20 MPa), while hydrogen pipeline stations operate at relatively lower pressures (approximately 5 MPa). Therefore, the impact range of accidents occurring at these two types of stations will inevitably differ significantly. If the fire separation distance for hydrogen pipeline stations is determined according to the relevant regulations for fire separation distances at hydrogen stations, it will cause considerable inconvenience to the site selection of hydrogen pipeline stations and potential demolition of surrounding areas.

[0005] Currently, there is no publicly available literature that fully elaborates on the method for determining the external fire protection distance of hydrogen pipeline stations, nor has a quantitative analytical model been proposed. Furthermore, given that the development level of hydrogen stations is far less than that of natural gas stations, the computational margin of the analytical model should be fully considered. Summary of the Invention

[0006] The purpose of this application is to overcome the deficiencies of the prior art and provide a method for determining the fire protection distance of hydrogen pipeline stations based on consequence comparison. Based on the similarity of the configuration of hydrogen pipeline stations and natural gas pipeline stations, and making full use of the fire protection distance requirements already implemented by natural gas pipeline stations, the method supports the determination of the fire protection distance of hydrogen pipeline stations, thus forming a method for selecting the fire protection distance of hydrogen pipeline stations.

[0007] The objective of this application is achieved through the following technical solution:

[0008] A method for determining fire separation distances at hydrogen pipeline stations based on consequence comparison, the method comprising:

[0009] Collect the design parameters of the pipelines at the hydrogen station site and the basic parameters of the gas flowing through the pipelines, introduce the pressure correction coefficient to calculate the corrected pressure of the hydrogen station site, and determine the leakage orifice diameter;

[0010] Based on the determined leakage orifice diameter and the calculation of the maximum leakage flow rate of the pipeline under uninterrupted discharge;

[0011] Calculate the flame length when a fire is triggered by a horizontal leak, and calculate the distance of the flame's thermal radiation impact on the surrounding environment;

[0012] The external fire prevention distance of the hydrogen pipeline station is calculated based on the distance affected by thermal radiation.

[0013] Furthermore, the design parameters include the design pressure of the hydrogen pipeline station and the outer diameter of the main pipeline, and the basic parameters include the specific heat ratio of the gas, the heat of combustion of the gas, the molar mass of the gas, the compressibility factor of the gas, the gas density under operating conditions, the thermal emissivity of the gas, and the atmospheric thermal radiation transmission efficiency of the gas.

[0014] Furthermore, the calculation method for the maximum leakage flow rate includes:

[0015] Calculate the critical expansion coefficients of hydrogen and natural gas:

[0016]

[0017] In the formula, γ represents the specific heat ratio of the gas, z represents the compressibility factor of the gas, and Y represents the critical expansion coefficient of the gas.

[0018] Calculate the leakage mass flow rates of hydrogen and natural gas:

[0019]

[0020] In the formula, P i T1 represents the initial leakage pressure of the gas, T1 represents the initial leakage temperature of the gas, d represents the leakage orifice diameter, and W represents the leakage mass flow rate of the gas.

[0021] Furthermore, the calculation method for the flame length includes:

[0022]

[0023] In the formula, H represents the heat of combustion of the gas, L1 represents the length of the horizontal jet flame of the gas, and m represents the correction factor for the length of the horizontal jet flame of the gas.

[0024] Furthermore, the calculation method for the distance affected by thermal radiation includes:

[0025]

[0026] In the formula, τ represents the atmospheric thermal radiation transmission efficiency of the gas, F represents the thermal emissivity of the gas, and L2 represents the range of thermal radiation influence of the gas.

[0027] L = L1 + L2;

[0028] In the formula, L is the distance affected by thermal radiation.

[0029] Furthermore, the calculation of the external fire prevention distance of the hydrogen pipeline station based on the thermal radiation influence distance specifically includes:

[0030] When the ratio of the thermal radiation distance of hydrogen to that of natural gas is not greater than 1, the external fire protection distance of hydrogen pipeline stations shall be implemented in accordance with the current specifications for natural gas pipeline stations.

[0031] When the ratio of the thermal radiation distances of hydrogen and natural gas is greater than 1, the external fire protection distance of hydrogen pipeline stations shall be implemented after being corrected according to the current specifications for natural gas pipeline stations, with the correction factor being the ratio of thermal radiation distances.

[0032] The methods for calculating the thermal radiation distance ratio include:

[0033]

[0034] In the formula, f represents the thermal radiation distance ratio, and L H2 L represents the distance affected by the thermal radiation of hydrogen. C1 This indicates the distance affected by the thermal radiation of natural gas.

[0035] Furthermore, when the gas is hydrogen, the horizontal jet flame length correction factor is 0.7, and when the gas is natural gas, the horizontal jet flame length correction factor is 0.8.

[0036] Furthermore, the leakage orifice diameter is 50 mm.

[0037] Furthermore, the pressure correction factor is 1.2.

[0038] The beneficial effects of this application are as follows:

[0039] Based on the physical properties of hydrogen and natural gas, and the approach of determining fire protection distances for hydrogen pipeline stations based on fire consequence comparison, a hydrogen / natural gas leakage model with operating pressure correction is proposed to fully consider the safety margin of hydrogen pipeline stations. Furthermore, based on flame length correction and power radiation model, a comprehensive impact range model of hydrogen / natural gas leakage consequences (fire) coupled with flame length and thermal radiation range is established. By comparing the thermal radiation impact range of hydrogen and natural gas, a method for correcting the fire protection distance of hydrogen pipeline stations based on the fire protection distance of natural gas stations is established, forming a quantitative approach to determining the fire protection distance of hydrogen pipeline stations, providing important support for the design of hydrogen pipeline stations. Attached Figure Description

[0040] Figure 1 This is a flowchart of a method for determining the fire protection distance of a hydrogen pipeline station based on consequence comparison, according to an embodiment of this application. Detailed Implementation

[0041] The following specific examples illustrate the implementation of this application. Those skilled in the art can easily understand other advantages and effects of this application from the content disclosed in this specification. This application can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of this application. It should be noted that, unless otherwise specified, the following embodiments and features in the embodiments can be combined with each other.

[0042] Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without inventive effort are within the scope of protection of this application.

[0043] Currently, there is no publicly available literature that fully elaborates on the method for determining the external fire protection distance of hydrogen pipeline stations, nor has a quantitative analytical model been proposed. Furthermore, given that the development level of hydrogen stations is far less than that of natural gas stations, the computational margin of the analytical model should be fully considered.

[0044] To address the aforementioned technical problems, the following embodiments of a method for determining fire separation distances for hydrogen pipeline stations based on consequence comparison are proposed in this application.

[0045] Reference Figure 1 ,like Figure 1 The diagram shown is a flowchart of a method for determining fire separation distances for hydrogen pipeline stations based on consequence comparison, according to an embodiment of this application. The method specifically includes the following steps:

[0046] Step 1: Collect the design parameters of the pipelines at the hydrogen station site and the basic parameters of the gas flowing through the pipelines, introduce the pressure correction factor to calculate the corrected pressure of the hydrogen station site, and determine the leakage orifice diameter.

[0047] Specifically, the parameters collected in this embodiment are as follows:

[0048] (1) Design pressure P1 of hydrogen pipeline station;

[0049] (2) Outer diameter D of the main pipeline (same for hydrogen and natural gas);

[0050] (3) Hydrogen specific heat ratio γH2, methane specific heat ratio γC1;

[0051] (4) Calorific value of hydrogen combustion H H2 Heat of combustion of methane (H) C1 ;

[0052] (5) Molar mass of hydrogen MH2, molar mass of methane MC1;

[0053] (6) Hydrogen compressibility factor ZH2, methane compressibility factor ZC1;

[0054] (7) Leakage orifice diameter d

[0055] (8) Hydrogen density ρH2 and natural gas density ρC1 under operating conditions

[0056] (9) Thermal emissivity of hydrogen FH2, thermal emissivity of methane FC1;

[0057] (10) Atmospheric thermal radiation transmission efficiency τH2 of hydrogen and atmospheric thermal radiation transmission efficiency τC1 of methane.

[0058] In this study, based on the design pressure P1 of the hydrogen pipeline station, and considering that the operation and maintenance experience of hydrogen pipeline stations is still in the accumulation stage and the number of hydrogen pipeline station leakage cases is limited, a pressure correction factor M is introduced as the selected value P2 for the design pressure of the hydrogen pipeline station. This is to appropriately amplify the scale of the consequences of hydrogen pipeline station leakage and to serve as the basis for comparison with natural gas pipeline stations. Meanwhile, the design pressure of the natural gas pipeline station is considered to be P1. Furthermore, a value of 1.2 for M is recommended.

[0059] The purpose of collecting other parameters is to support subsequent calculations of leakage flow rate and the impact range of leakage fire, in order to quantify and differentiate the scale of consequences of hydrogen and natural gas leaks.

[0060] Step 2: Based on the determined leak orifice diameter, calculate the maximum leakage flow rate of the pipeline under uninterrupted leakage.

[0061] Specifically, since neither natural gas pipeline stations nor hydrogen pipeline stations contain gas storage tanks, only pipeline leakage scenarios are considered. Based on experience with the pipe diameter distribution of natural gas pipeline leakage risk, a medium-sized orifice leakage (d = 50 mm) is recommended as the preferred comparison orifice diameter. Large orifices (100 mm) and complete ruptures are not recommended because their probability of occurrence is low. Both hydrogen and natural gas pipeline stations are equipped with comprehensive intrinsic protection and station maintenance functions, and the purpose of this invention is to compare the leakage consequences under the same orifice diameter. Furthermore, to fully characterize the impact of leakage volume, the impact of pipeline closure after leakage on the total release volume is not considered. The specific calculation method is as follows:

[0062] (1) Calculate the critical expansion coefficients of hydrogen and natural gas:

[0063]

[0064] In the formula,

[0065] γ — Specific heat ratio of hydrogen or methane, dimensionless;

[0066] z—compressibility factor for hydrogen or methane, dimensionless;

[0067] Y—critical expansion coefficient of hydrogen or methane, dimensionless;

[0068] In this formula, the specific heat ratio and compressibility factor of hydrogen and methane under leakage conditions are input respectively, and the corresponding critical expansion coefficient is calculated.

[0069] (2) Calculate the leakage mass flow rates of hydrogen and natural gas:

[0070]

[0071] In the formula,

[0072] P i —Initial leakage pressure of hydrogen or methane, kPa; where the initial hydrogen pressure is the corrected pressure P2 and the initial natural gas pressure is the uncorrected pressure P1.

[0073] T1—Initial leakage temperature of hydrogen or methane, °C;

[0074] d—the diameter of the leaking orifice for hydrogen or methane, in mm;

[0075] W – Leakage mass flow rate of hydrogen or methane, kg / h.

[0076] Step 3: Calculate the flame length when a fire is caused by a horizontal leak, and calculate the distance of the flame's thermal radiation impact on the surrounding environment.

[0077] Generally, the direction of the jet fire caused by a leak includes both vertical and horizontal directions. When the jet fire is horizontal, it has a greater impact on people and buildings near the ground; therefore, the horizontal direction is chosen as the direction for analyzing the impact of the jet fire. Furthermore, the flame length of the jet fire is calculated to fully consider its contribution to the thermal radiation influence range. Simultaneously, based on the difference in attitude between hydrogen and natural gas horizontal jet fires, influence range correction parameters are assigned. In addition, the point source thermal radiation method is used to calculate the thermal radiation influence range, with the flame tip as the center of the thermal radiation point source. The specific method is as follows:

[0078] (1) Calculate the flame length:

[0079]

[0080] In the formula,

[0081] H—Heat of combustion of hydrogen or methane, kJ / kg;

[0082] W—Leakage mass flow rate of hydrogen or methane, kg / h;

[0083] L1—Length of the horizontal jet flame of hydrogen or methane, in meters;

[0084] m—a dimensionless correction factor for the length of a horizontally jetted flame of hydrogen or methane; since hydrogen has a small molecular weight, the tail of the horizontally jetted flame has a distinct "upturned" posture, so a flame length correction factor of 0.7 is preferred, which means that 70% of the calculated flame length is considered as the center of the heat radiation source; since natural gas has a relatively large molecular weight, the horizontally jetted flame has a relatively straight posture, so a flame length correction factor of 0.8 is preferred, which means that 80% of the calculated flame length is considered as the center of the heat radiation source.

[0085] (2) Calculate the thermal radiation range

[0086]

[0087] In the formula,

[0088] τ—Atmospheric thermal radiation transfer efficiency of hydrogen or methane, dimensionless; preferably 1 for both hydrogen and methane;

[0089] F – thermal emissivity of hydrogen or methane, dimensionless; preferably 0.17 for hydrogen and 0.23 for methane;

[0090] L2 – Range of thermal radiation influence of hydrogen or methane, in meters.

[0091] (3) Calculate the combined thermal radiation range of the coupled flame length and thermal radiation influence.

[0092] L = L1 + L2

[0093] In the formula,

[0094] L – The combined thermal radiation range of the coupled flame length of hydrogen or methane and the thermal radiation effect, in meters.

[0095] Therefore, the comprehensive thermal radiation range L of hydrogen can be obtained separately. H2 The combined thermal radiation influence range of natural gas L C1 .

[0096] Step 4: Calculate the external fire prevention distance of the hydrogen pipeline station based on the distance affected by thermal radiation.

[0097] Based on a comparison of the thermal radiation impact distances of hydrogen and natural gas leaks under different operating conditions, a correction factor is applied to the hydrogen thermal radiation distance to improve safety and obtain the thermal radiation distance ratio. When the thermal radiation distance ratio is less than 1, the external fire protection distance of the hydrogen pipeline station shall comply with the relevant current specifications for natural gas pipeline stations. When the thermal radiation distance ratio is greater than 1, the external fire protection distance of the hydrogen pipeline station shall be adjusted according to the relevant current specifications for pipeline stations, with the correction factor being the thermal radiation distance ratio. Specifically, the calculation method for the thermal radiation distance ratio is as follows:

[0098]

[0099] In the formula,

[0100] f is the ratio of the thermal radiation distance of hydrogen to that of natural gas, and is dimensionless.

[0101] This led to the development of a method for determining fire separation distances at hydrogen pipeline stations based on consequence comparison.

[0102] Compared with existing technologies, the positive effects of the embodiments of this application are as follows: Based on the physical properties of hydrogen and natural gas, and the approach of determining the fire protection distance of hydrogen stations based on the comparison of fire consequences, a hydrogen / natural gas leakage model with operating pressure correction is proposed to fully consider the safety margin of hydrogen pipeline stations; furthermore, based on flame length correction and power radiation model, a comprehensive impact range model of hydrogen / natural gas leakage consequences (fire) coupled with flame length and thermal radiation range is established; by comparing the thermal radiation impact range of hydrogen and natural gas, a method for correcting the fire protection distance of hydrogen stations based on the fire protection distance of natural gas stations is established, forming a quantitative approach to determine the fire protection distance of hydrogen pipeline stations, which provides important support for the design of hydrogen pipeline stations.

[0103] The principle of the embodiments in this application is as follows:

[0104] (1) Compared to natural gas, hydrogen has a significantly lower minimum ignition energy, a lower explosive limit, and a lower density. Therefore, hydrogen is more easily ignited after a leak, and the impact of the jet fire after a leak has always been a research hotspot. In the engineering field, both hydrogen pipelines and natural gas pipelines require the construction of a certain number of stations to provide functions such as pipeline cleaning, metering, and distribution. The main functions and facility configurations of hydrogen pipeline stations are quite similar to those of natural gas pipeline stations, and the distance between the station and the surrounding environment is generally determined based on fire prevention distances.

[0105] (2) Fire separation distances are proposed based on the station size and transmission pressure, taking into full account the consequences of fire and the frequency of accidents. Natural gas pipeline stations and hydrogen pipeline stations have similar accident consequences. It is possible to compare the accident consequences of natural gas pipeline stations and hydrogen pipeline stations with the same pipe diameter and functional configuration, and obtain the external fire separation distance of hydrogen pipeline stations based on the external fire separation distance of natural gas pipeline stations after modification.

[0106] (3) In specific implementation, in order to fully consider the safety of hydrogen pipeline stations, reduce the impact of hydrogen pipeline station consequences on the external environment, and overcome the current lack of experience in construction and operation, the comparison pressure of hydrogen pipeline stations was corrected (increased) in the design pressure. In order to consider the impact of the length of natural gas and hydrogen jet fire on the comprehensive thermal radiation range, a comprehensive thermal radiation influence range calculation model coupled with jet fire length and point source thermal radiation range was proposed, and the point source position in the jet fire length direction was corrected. Furthermore, the calculated thermal radiation influence range of hydrogen pipeline stations was corrected a second time to further improve its safety margin. The ratio of thermal radiation influence range (the ratio of hydrogen thermal radiation distance to natural gas thermal radiation distance) was used as the correction coefficient. When the thermal radiation distance ratio is less than 1, the external fire protection distance of hydrogen pipeline stations shall be implemented in accordance with the relevant specifications of current natural gas pipeline stations. When the thermal radiation distance ratio is greater than 1, the external fire protection distance of hydrogen pipeline stations shall be corrected in accordance with the relevant specifications of current pipeline stations. Thus, a method for determining the fire protection distance of hydrogen pipeline stations based on consequence comparison was established.

[0107] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A method for determining fire separation distances for hydrogen pipeline stations based on consequence comparison, characterized in that, The method includes: Collect the design parameters of the pipelines at the hydrogen station site and the basic parameters of the gas flowing through the pipelines, introduce the pressure correction coefficient to calculate the corrected pressure of the hydrogen station site, and determine the leakage orifice diameter; Based on the determined leakage orifice diameter and the calculation of the maximum leakage flow rate of the pipeline under uninterrupted discharge; Calculate the flame length when a fire is triggered by a horizontal leak, and calculate the distance of the flame's thermal radiation impact on the surrounding environment; The external fire prevention distance of the hydrogen pipeline station is calculated based on the distance affected by thermal radiation.

2. The method for determining the fire separation distance of hydrogen pipeline stations based on consequence comparison as described in claim 1, characterized in that, The design parameters include the design pressure of the hydrogen pipeline station and the outer diameter of the main pipeline. The basic parameters include the specific heat ratio of the gas, the heat of combustion of the gas, the molar mass of the gas, the compressibility factor of the gas, the gas density under operating conditions, the thermal emissivity of the gas, and the atmospheric thermal radiation transmission efficiency of the gas.

3. The method for determining the fire separation distance of hydrogen pipeline stations based on consequence comparison as described in claim 2, characterized in that, The calculation method for the maximum leakage flow includes: Calculate the critical expansion coefficients of hydrogen and natural gas: In the formula, γ represents the specific heat ratio of the gas, z represents the compressibility factor of the gas, and Y represents the critical expansion coefficient of the gas. Calculate the leakage mass flow rates of hydrogen and natural gas: In the formula, P i T1 represents the initial leakage pressure of the gas, T1 represents the initial leakage temperature of the gas, d represents the leakage orifice diameter, and W represents the leakage mass flow rate of the gas.

4. The method for determining the fire separation distance of hydrogen pipeline stations based on consequence comparison as described in claim 3, characterized in that, The method for calculating the flame length includes: In the formula, H represents the heat of combustion of the gas, L1 represents the length of the horizontal jet flame of the gas, and m represents the correction factor for the length of the horizontal jet flame of the gas.

5. The method for determining the fire separation distance of hydrogen pipeline stations based on consequence comparison as described in claim 4, characterized in that, The calculation method for the distance affected by thermal radiation includes: In the formula, τ represents the atmospheric thermal radiation transmission efficiency of the gas, F represents the thermal emissivity of the gas, and L2 represents the range of thermal radiation influence of the gas. L = L1 + L2; In the formula, L is the distance affected by thermal radiation.

6. The method for determining the fire separation distance of hydrogen pipeline stations based on consequence comparison as described in claim 5, characterized in that, The calculation of the external fire prevention distance of the hydrogen pipeline station based on the thermal radiation influence distance specifically includes: When the ratio of the thermal radiation distance of hydrogen to that of natural gas is not greater than 1, the external fire protection distance of hydrogen pipeline stations shall be implemented in accordance with the current specifications for natural gas pipeline stations. When the ratio of the thermal radiation distances of hydrogen and natural gas is greater than 1, the external fire protection distance of hydrogen pipeline stations shall be implemented after being corrected according to the current specifications for natural gas pipeline stations, with the correction factor being the ratio of thermal radiation distances. The methods for calculating the thermal radiation distance ratio include: In the formula, f represents the thermal radiation distance ratio, and L H2 L represents the distance affected by the thermal radiation of hydrogen. C1 This indicates the distance affected by the thermal radiation of natural gas.

7. The method for determining the fire separation distance of hydrogen pipeline stations based on consequence comparison as described in claim 4, characterized in that, When the gas is hydrogen, the horizontal jet flame length correction factor is 0.7; when the gas is natural gas, the horizontal jet flame length correction factor is 0.

8.

8. The method for determining the fire separation distance of hydrogen pipeline stations based on consequence comparison as described in claim 3, characterized in that, The leakage orifice diameter is 50 mm.

9. The method for determining the fire separation distance of hydrogen pipeline stations based on consequence comparison as described in claim 1, characterized in that, The pressure correction factor is 1.2.

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