A gas riser hydrogen storage device for hydrogen-blended natural gas pipeline

Abstract

This utility model relates to the field of urban gas equipment technology, specifically to a hydrogen storage device for a gas riser in a hydrogen-blended natural gas pipeline. The gas riser hydrogen storage device includes a main branch pipe with flange interfaces at both ends for connecting to the hydrogen-blended natural gas pipeline. The main branch pipe consists of an inlet section, a branch section, and an outlet section, arranged sequentially from bottom to top. A guide element is provided on the side of the branch section near the inlet section. The diameter of the branch section is larger than both the inlet and outlet sections. The wall of the outlet section extends into the branch section, with its bottom edge close to the guide element. A valve is located at the top of the branch section. This utility model has a simple structure and, when applied to hydrogen-blended natural gas pipelines, can prevent excessive hydrogen accumulation at the top of the gas riser, thus avoiding localized increases in hydrogen partial pressure and volume fraction, which could lead to pipe failure and leakage.

Description

Technical Field

[0001] The utility model relates to the technical field of urban gas equipment, and in particular to a gas riser hydrogen storage device for a hydrogen-blended natural gas pipeline. Background Art

[0002] Due to the difference in physical properties between natural gas and hydrogen, the two gases may stratify under the condition of low flow field disturbance for a long time, resulting in reduced mixing uniformity. Mixing hydrogen into existing natural gas pipelines is an effective way to achieve large-scale, long-distance, and low-cost storage and transportation of hydrogen. However, with the addition of hydrogen, the hydrogen-blended natural gas will present a non-uniform distribution of volume fraction due to the density difference between hydrogen and natural gas, resulting in an increase in the local hydrogen partial pressure and volume fraction of the pipeline, which in turn leads to pipe failure and leakage.

[0003] Especially during the static process such as pipeline shutdown, hydrogen gradually floats to the top and methane sinks to the bottom, and obvious stratification occurs. As the pressure and hydrogen blending ratio increase, the temperature and pipe diameter decrease, and the hydrogen gas volume fraction gradient in the gravity direction of the pipeline increases; when the hydrogen-blended natural gas pipeline runs at a very low flow rate, hydrogen gradually shifts to the top of the pipeline as it flows, and stratification occurs, and it is more likely to stratify under low temperature and high pressure. The risers of urban gas are usually small-diameter pipes, and the stratification phenomenon is more obvious. At night, the gas flow slows down, and hydrogen is likely to accumulate at the top of the riser, which poses certain safety hazards to users on the top floor. Utility Model Content

[0004] In order to solve the above problems, the utility model provides a gas riser hydrogen storage device for a hydrogen-blended natural gas pipeline, which can avoid excessive accumulation of hydrogen on the top layer of the gas riser.

[0005] The utility model provides a gas riser hydrogen storage device for a hydrogen-blended natural gas pipeline, the gas riser hydrogen storage device comprises a shunt main pipeline, flange interfaces are arranged at the upper and lower ends of the shunt main pipeline, the flange interfaces are used to connect the hydrogen-blended natural gas pipeline, the shunt main pipeline is sequentially provided with an air inlet section pipeline, a shunt section pipeline and an air outlet section pipeline from bottom to top, a flow guide is arranged on a side of the shunt section pipeline close to the air inlet section pipeline, the diameter of the shunt section pipeline is larger than the diameter of the air inlet section pipeline and the diameter of the air outlet section pipeline, the pipe wall of the air outlet section pipeline extends to the inside of the shunt section pipeline, and the bottom of the pipe wall of the air outlet section pipeline is close to the flow guide, and a valve is arranged on the top of the shunt section pipeline.

[0006] Furthermore, the guide member comprises an arc-shaped baffle plate arranged above the air intake section pipeline, and the convex surface of the arc-shaped baffle plate faces downward, which is opposite to the air intake direction of the hydrogen-blended natural gas.

[0007] Furthermore, the outer wall at the bottom of the air outlet section pipe is chamfered.

[0008] Furthermore, the connection between the air intake section pipeline and the diversion section pipeline is connected through a reducing pipe, and the diameter of the reducing pipe increases from bottom to top.

[0009] Furthermore, the width of the arc-shaped baffle is greater than the diameter of the air inlet section pipeline and the diameter of the air outlet section pipeline.

[0010] Furthermore, the horizontal plane where the lowest point of the arc-shaped baffle is located is lower than the horizontal plane where the highest point of the variable-diameter pipe is located.

[0011] Furthermore, the gas riser hydrogen storage device is made of steel plate.

[0012] Furthermore, the number of the gas riser hydrogen storage devices arranged on the hydrogen-blended natural gas pipeline is 1 to 2.

[0013] Furthermore, the variable diameter pipe is connected to the air intake section pipe at an inclined angle of 45° in the vertical direction.

[0014] Furthermore, the width between the outer wall of the diversion section pipe and the inner wall of the outlet section pipe is smaller than the diameter of the outlet section pipe.

[0015] Beneficial effects:

[0016] 1. The utility model releases the accumulated hydrogen in advance by connecting the gas riser hydrogen storage device to the hydrogen-blended natural gas pipeline, thus preventing the hydrogen from gradually shifting to the top of the hydrogen-blended natural gas pipeline as it flows, causing stratification. Especially in low-temperature and high-pressure use environments, hydrogen and natural gas are more likely to stratify. The utility model expands the use range of hydrogen-blended natural gas pipelines in low-temperature areas by designing the gas riser hydrogen storage device for hydrogen-blended natural gas pipelines.

[0017] 2. The utility model arranges a guide piece on one side of the diversion section pipeline close to the air inlet section pipeline. When the hydrogen-blended natural gas slowly flows from bottom to top to the vicinity of the guide piece, the guide piece guides the hydrogen-blended natural gas and divides it into three paths to continue to slowly flow upward. The airflows on both sides of the guide piece flow to the hydrogen storage area formed between the outer wall of the outlet section pipeline and the inner wall of the diversion section pipeline. The hydrogen-blended natural gas continuously flows in at any time, and hydrogen accumulates at the top of the hydrogen storage area. After a certain period of time, the valve is opened to release the hydrogen-blended natural gas with high hydrogen content accumulated in the hydrogen storage area.

[0018] It should be appreciated that all combinations of the foregoing concepts, as well as additional concepts described in greater detail below, may be considered part of the inventive subject matter of the present disclosure, provided such concepts are not mutually inconsistent.

[0019] The foregoing and other aspects, embodiments and features of the present invention can be more fully understood from the following description in conjunction with the accompanying drawings. Other additional aspects of the present invention, such as the features and / or beneficial effects of the exemplary embodiments, will be apparent from the following description or learned from the practice of the specific embodiments according to the teachings of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The accompanying drawings are not drawn to scale according to actual reference objects. In the accompanying drawings, each identical or approximately identical component shown in each figure may be represented by the same reference numeral. For the sake of clarity, not every component is labeled in each figure. Now, embodiments of various aspects of the utility model will be described by way of example and with reference to the accompanying drawings, in which:

[0021] Figure 1 The utility model is a cross-sectional view of the structure of a gas riser hydrogen storage device for a hydrogen-blended natural gas pipeline.

[0022] Description of Figure Numbers:

[0023] 1-inlet section pipeline; 2-diversion section pipeline; 3-arc baffle; 4-hydrogen storage area; 5-valve; 6-flange interface; 7-outlet section pipeline. DETAILED DESCRIPTION

[0024] The technical solutions in the embodiments of the present application will be described clearly and completely below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present application.

[0025] In the description of the present application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like indicating orientations or positional relationships are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0026] In the description of this application, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, an electrical connection, or mutual communication; it can be a direct connection, or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0027] The disclosure below provides many different embodiments or examples to realize the different structures of the present application. In order to simplify the disclosure of the present application, the parts and settings of specific examples are described below. Of course, they are only examples, and the purpose is not to limit the present application. In addition, the present application can repeat reference numbers and / or reference letters in different examples, and this repetition is for the purpose of simplification and clarity, which itself does not indicate the relationship between the various embodiments and / or settings discussed. In addition, the various specific processes and material examples provided by the present application, but those of ordinary skill in the art can appreciate the application of other processes and / or the use of other materials.

[0028] When hydrogen-blended natural gas pipelines run at a very low flow rate, hydrogen gradually shifts to the top of the pipeline as it flows, resulting in stratification, which is more likely to occur at low temperatures and high pressures. Urban gas risers are usually small-diameter pipes, and the stratification phenomenon is more obvious. At night, when the gas flow slows down, hydrogen is likely to accumulate at the top of the riser, posing a certain safety hazard to users on the top floor.

[0029] Based on the above problems, an embodiment of the utility model provides a gas riser hydrogen storage device for a hydrogen-blended natural gas pipeline.

[0030] See also Figure 1 As shown, the utility model provides a gas riser hydrogen storage device for a hydrogen-blended natural gas pipeline, the gas riser hydrogen storage device comprises a shunt main pipeline, flange interfaces 6 are arranged at the upper and lower ends of the shunt main pipeline, the flange interfaces are used to connect the gas riser hydrogen storage device to the hydrogen-blended natural gas pipeline, the shunt main pipeline is provided with an air inlet section pipeline 1, a shunt section pipeline 2 and an air outlet section pipeline in sequence from bottom to top, a guide piece is arranged on the side of the shunt section pipeline 2 close to the air inlet section pipeline 1, the diameter of the shunt section pipeline 2 is larger than the diameter of the air inlet section pipeline 1 and the diameter of the air outlet section pipeline, the pipe wall of the air outlet section pipeline extends to the inside of the shunt section pipeline 2, and the bottom of the pipe wall of the air outlet section pipeline is close to the guide piece, and a valve 5 is arranged on the top of the shunt section pipeline 2, and the valve 5 is used to discharge the hydrogen accumulated at the top of the hydrogen storage area 4.

[0031] By connecting a gas riser hydrogen storage device to the hydrogen-blended natural gas pipeline, the accumulated hydrogen is released in advance to prevent the hydrogen from gradually shifting to the top of the hydrogen-blended natural gas pipeline as it flows, causing stratification. In particular, hydrogen and natural gas are more likely to stratify under low-temperature and high-pressure use environments. The utility model expands the use range of hydrogen-blended natural gas pipelines in low-temperature areas by designing a gas riser hydrogen storage device for hydrogen-blended natural gas pipelines.

[0032] The utility model provides a flow guide on one side of the diversion section pipeline 2 close to the air inlet section pipeline 1. When the hydrogen-blended natural gas slowly flows from bottom to top to the vicinity of the flow guide, the flow is guided by the flow guide and the hydrogen-blended natural gas is divided into three paths and continues to flow slowly upward. The airflows on both sides of the flow guide flow to the hydrogen storage area 4 formed between the outer wall of the air outlet section pipeline 7 and the inner wall of the diversion section pipeline 2. The hydrogen-blended natural gas continuously flows in at any time, and hydrogen accumulates at the top of the hydrogen storage area. After a certain period of time, the valve is opened to release the hydrogen-blended natural gas with high hydrogen content accumulated in the hydrogen storage area 4.

[0033] In some embodiments of the utility model, the guide member includes an arc-shaped baffle plate 3 arranged above the air intake pipe 1, and the convex surface of the arc-shaped baffle plate 3 faces downward, which is opposite to the air intake direction of the hydrogen-blended natural gas, plays a role in guiding flow, and facilitates the natural diversion of the hydrogen-blended natural gas.

[0034] In some embodiments of the present invention, the outer wall of the bottom of the outlet pipe 7 is chamfered to further assist in flow diversion.

[0035] In some embodiments of the utility model, the connection between the air intake section pipeline 1 and the diversion section pipeline 2 is connected by a reducing pipe, the diameter of the reducing pipe increases from bottom to top, and cooperates with the arc baffle 3 to guide the hydrogen-blended natural gas to the hydrogen storage area 4 in advance.

[0036] In some embodiments of the present invention, the width of the arc-shaped baffle 3 is greater than the diameter of the air inlet section pipe 1 and the diameter of the air outlet section pipe, so as to facilitate drainage.

[0037] In some embodiments of the present invention, the horizontal plane where the lowest point of the arc-shaped baffle 3 is located is lower than the horizontal plane where the highest point of the variable-diameter pipe is located, which further facilitates drainage.

[0038] In some embodiments of the utility model, the material of the gas riser hydrogen storage device is steel plate, which will not leak and has a firm structure.

[0039] In some embodiments of the utility model, the number of the gas riser hydrogen storage devices arranged on the hydrogen-blended natural gas pipeline is 1 to 2. By setting 1 to 2 gas riser hydrogen storage devices on a hydrogen-blended natural gas pipeline with a height of 33 ordinary residential buildings, the phenomenon of hydrogen accumulation and stratification at the top of the hydrogen-blended natural gas pipeline can be effectively alleviated.

[0040] In some embodiments of the present invention, the variable diameter pipe is connected to the air intake section pipe 1 at an inclined angle of 45° in the vertical direction. A reasonably designed inclination angle can not only play a guiding role but also smoothly connect the air intake section pipe 1 and the diversion section pipe 2.

[0041] In some embodiments of the present invention, the width between the outer wall of the diversion section pipe 2 and the inner wall of the outlet section pipe is smaller than the diameter of the outlet section pipe.

[0042] Since the density of hydrogen and methane is very different, the density of methane is about 8 times that of hydrogen at normal temperature and pressure, and hydrogen is easier to diffuse than natural gas. With the addition of hydrogen, the volume fraction of hydrogen-blended natural gas will be unevenly distributed under the action of gravity during storage and pipeline shutdown. At the same time, during the operation of the hydrogen-blended natural gas pipeline, when the pipeline flow rate is low, the phenomenon of hydrogen shifting to the top of the pipeline may occur.

[0043] Therefore, the device of the utility model arranges the hydrogen storage area on both radial sides of the outlet section pipeline, which conforms to the characteristic that hydrogen is easier to diffuse, facilitates the effective accumulation of hydrogen in advance, and releases the hydrogen-blended natural gas with a high hydrogen content through the valve in advance.

[0044] In order to calculate the change of component concentration in the mixed gas system with h, it is necessary to solve the gas state equations simultaneously. RK equation, PR equation, BWRS equation, etc. are all real gas state equations commonly used in natural gas pipeline transportation calculations. Considering the calculation difficulty and calculation accuracy when solving the coupled equation, the utility model uses the PR gas state equation, as follows:

[0045]

[0046] Where p is pressure, unit is Pa; T is temperature, unit is K; v is the molar volume of the mixed gas, unit is m 3 / mol; R is the ideal gas constant, J / (mol·K); a and b are material-related parameters, which respectively reflect the attraction and repulsion between gas molecules; a(T) is a temperature function.

[0047] The transportation of natural gas must satisfy the mass conservation equation, momentum conservation equation, and energy conservation equation. The length of the transportation pipeline is much larger than its diameter, so the flow process of natural gas in the pipeline can be simplified to a one-dimensional flow process. The turbulence model uses the standard k-ε model, and its flow control equation is as follows:

[0048]

[0049] Where w is the gas velocity in the pipeline, in m / s; d is the inner diameter of the pipeline, in mm; θ is the pipeline inclination angle; λ is the friction resistance coefficient; k is the total heat transfer coefficient, W / (m 2 ·℃); T0 is the ambient temperature, in K. The friction coefficient λ is calculated by the Colebrook formula; the total heat transfer coefficient takes into account the effects of convection inside and outside the tube and radial heat conduction of the pipeline;

[0050] The velocity is used as the basic solution variable. The unsteady-state terms of the mass and momentum conservation equations are discretized using the forward difference format, and the convection terms are discretized using the central difference method; the unsteady-state terms of the energy equation are discretized using the forward difference format, and the convection terms are discretized using the first-order upwind format to avoid the stability problem of the energy equation caused by the flow direction.

[0051] Calculations have confirmed that after the hydrogen-blended natural gas pipeline is shut down, as it stands still, hydrogen gradually floats to the top and methane sinks to the bottom of the pipeline, showing an obvious stratification phenomenon. When the standing time reaches a certain value, the hydrogen-methane volume fraction distribution tends to be stable, but there is still a volume fraction gradient; and as the pressure and hydrogen blending ratio increase, and the temperature and pipe diameter decrease, the hydrogen gas volume fraction gradient in the gravity direction increases.

[0052] In summary, the diameters of the various pipes of the utility model are reasonably designed to maximize the convenience of hydrogen being diverted to the hydrogen storage area 4 for accumulation, and the hydrogen accumulated on the top layer is diverted out in advance. According to the actual application scenario, the device of the utility model is dispersed at several key positions of the hydrogen-blended natural gas pipeline to avoid excessive concentration of hydrogen.

[0053] Although the present invention has been disclosed as above with preferred embodiments, it is not intended to limit the present invention. A person with ordinary knowledge in the technical field to which the present invention belongs may make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention shall be determined by the definition of the claims.

Claims

1. A gas riser hydrogen storage device for a hydrogen-blended natural gas pipeline, characterized in that: The gas riser hydrogen storage device includes a shunt main pipeline, and flange interfaces are arranged at the upper and lower ends of the shunt main pipeline, and the flange interfaces are used to connect the hydrogen-blended natural gas pipeline. The shunt main pipeline is sequentially provided with an air inlet section pipeline, a shunt section pipeline and an air outlet section pipeline from bottom to top, and a guide piece is arranged on the side of the shunt section pipeline close to the air inlet section pipeline, and the diameter of the shunt section pipeline is larger than the diameter of the air inlet section pipeline and the diameter of the air outlet section pipeline, and the pipe wall of the air outlet section pipeline extends to the inside of the shunt section pipeline, and the bottom of the pipe wall of the air outlet section pipeline is close to the guide piece, and a valve is arranged on the top of the shunt section pipeline.

2. The gas riser hydrogen storage device for a hydrogen-blended natural gas pipeline according to claim 1, characterized in that: The flow guide comprises an arc-shaped baffle plate arranged above the air intake section pipeline, wherein the convex surface of the arc-shaped baffle plate faces downward, which is opposite to the air intake direction of the hydrogen-blended natural gas.

3. The gas riser hydrogen storage device for a hydrogen-blended natural gas pipeline according to claim 2, characterized in that: The outer wall at the bottom of the air outlet section pipe is chamfered.

4. The gas riser hydrogen storage device for a hydrogen-blended natural gas pipeline according to claim 2, characterized in that: The connection between the air intake section pipeline and the diversion section pipeline is connected through a reducing pipe, and the diameter of the reducing pipe increases from bottom to top.

5. The gas riser hydrogen storage device for a hydrogen-blended natural gas pipeline according to claim 2, characterized in that: The width of the arc-shaped baffle is greater than the diameter of the air inlet section pipeline and the diameter of the air outlet section pipeline.

6. The gas riser hydrogen storage device for a hydrogen-blended natural gas pipeline according to claim 4, characterized in that: The horizontal plane where the lowest point of the arc-shaped baffle is located is lower than the horizontal plane where the highest point of the variable-diameter pipe is located.

7. The gas riser hydrogen storage device for a hydrogen-blended natural gas pipeline according to claim 2, characterized in that: The material of the gas riser hydrogen storage device is steel plate.

8. The gas riser hydrogen storage device for a hydrogen-blended natural gas pipeline according to claim 1, characterized in that: The number of the gas riser hydrogen storage devices arranged on the hydrogen-blended natural gas pipeline is 1 to 2.

9. The gas riser hydrogen storage device for a hydrogen-blended natural gas pipeline according to claim 4, characterized in that: The variable diameter pipeline is connected to the air intake section pipeline at an inclined angle of 45° in the vertical direction.

10. The gas riser hydrogen storage device for a hydrogen-blended natural gas pipeline according to claim 1, characterized in that: The width between the outer wall of the diversion section pipeline and the inner wall of the outlet section pipeline is smaller than the diameter of the outlet section pipeline.

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