A natural gas hydrogen blending device with uniform flow distribution

Abstract

The present invention relates to a natural gas hydrogen blending device for uniformly distributing flow, comprising a square pipe, a partition structure and a flow equalizer; the square pipe is provided with a natural gas inlet and a hydrogen inlet, the natural gas inlet is arranged along the pipe axis, and the hydrogen inlet is arranged radially along the pipe side; a square grid-shaped partition structure is provided in the square pipe, and the partition structure divides the space in the square pipe into area one and area two; area one is divided into a plurality of mutually independent parts, and area two is a connected whole; area two is divided into area three and area four, wherein the square grid at the node of the square grid of the partition structure is area four, and the square at the four sides of area four is area three; a flow equalizer is provided in the hydrogen channel, and the flow equalizer comprises a gradually converging and expanding pipe, a contraction spring and a fluid marble. The beneficial effects of the present invention are as follows: the present invention provides a partition structure in the pipe, disperses the two fluids into small tributaries, and arranges the tributaries of different gas types in sequence, so as to achieve rapid and uniform mixing.

Description

Technical Field

[0001] The invention relates to a natural gas hydrogen blending device, in particular to a natural gas hydrogen blending device with uniform flow distribution. Background Art

[0002] Natural gas blending with hydrogen has always been an important research direction for hydrogen transportation and large-scale utilization at home and abroad, and is of great significance to the development of my country's hydrogen energy industry. Natural gas blending with hydrogen is an important technical issue for the safe transportation of hydrogen-blended natural gas.

[0003] There are three existing methods of blending natural gas with hydrogen: the first is direct mixing, that is, the natural gas pipe and the hydrogen pipe directly intersect to form a natural gas hydrogen blending pipe, and the turbulence effect is used to reach a uniform state after a long distance. The advantage of this solution is that no additional mixing device is required. The disadvantage is that a long distance is required before the mixing state is reached. Therefore, the gas components are in an uneven state for a long distance after the mixing point; the second is a moving part gas mixing device, which achieves hydrogen blending and mixing through mechanical structure stirring, and can quickly achieve uniform mixing, but requires energy consumption; the third is a gas mixing device without moving parts, which has higher reliability than the gas mixing device with moving parts. The existing gas mixing devices without moving parts include SV type, SK type, SX type, SL type, SH type, etc. The principle is to achieve a mixing effect by setting complex flow channels to continuously change the flow direction of the fluid to enhance the turbulence effect.

[0004] At the mixing point of the natural gas pipeline and the hydrogen pipeline, regardless of whether a mixer is used, the two gases have a clear boundary at the initial stage of mixing, and the pressure drop loss in different parts is different, which will inevitably cause the composition of the initial fluid to be different from the composition after reaching equilibrium. In this process, taking the gas at a farther pipe as the object, the gas composition on the same pipe section can be uniform, but the gas composition fluctuates at different time points. Fig.10 As shown in the figure, i is the component after the mixing equilibrium is reached, and j is the time required to reach the equilibrium. In the fluctuation section, the component (referring to the total proportion of gas on a certain pipe section, not the uniformity) fluctuates above and below the equilibrium component value. Due to the conservation of matter, the integral area of ​​"component-time" of this fluctuation curve is equal to i·j. Similarly, after the inlet flow rate of the natural gas pipe or hydrogen pipe at the mixing point changes, a new component balance is established, which also requires a fluctuation section.

[0005] The existence of the fluctuation section in the above-mentioned mixing process causes the flow rate at the mixing point to change, which will inevitably cause component fluctuations at the back end. This fluctuation has an adverse effect on the combustion stability of the end user and needs to be eliminated. Summary of the invention

[0006] The purpose of the present invention is to overcome the deficiencies in the prior art and provide a natural gas hydrogen blending device with uniform flow distribution.

[0007] The natural gas hydrogen blending device for uniformly distributing flow comprises a square pipe, a partition structure and a flow equalizer; the square pipe is provided with a natural gas inlet and a hydrogen inlet, the natural gas inlet is arranged along the pipe axis direction, and the hydrogen inlet is arranged along the radial direction of the pipe side; a square grid-shaped partition structure is provided in the square pipe, and the partition structure divides the space in the square pipe into area one and area two; area one is divided into multiple independent parts, and area two is a connected whole; area two is divided into area three and area four, wherein the square grid at the node of the square grid of the partition structure is area four, and the square at the four sides of area four is area three; area three is a circulation space and area four is a closed space, or area three is a closed space and area four is a circulation space; area one serves as a natural gas channel, and area three or area four of the partition structure serves as a hydrogen channel; a flow equalizer is provided in the hydrogen channel, and the flow equalizer comprises a gradually converging and expanding tube, a contraction spring and a fluid ball, a contraction spring is provided at the front end of the gradually converging and expanding tube, the contraction spring is connected to the fluid ball, and the fluid ball fits the narrowest section of the gradually converging and expanding tube.

[0008] Preferably, the structure of the second region is local in the direction along the tube axis.

[0009] As a preference, area one is used as a natural gas channel, area four is used as a hydrogen channel, and the natural gas channel and the hydrogen channel are in corner contact with each other.

[0010] Preferably, area one is used as a natural gas channel, and area three is used as a hydrogen channel, and each hydrogen channel is in contact with the natural gas channel in both the up-down or left-right directions.

[0011] As a preferred embodiment, a flow equalizer is provided in the natural gas channel.

[0012] The working method of the flow equalizer of the natural gas hydrogen blending device for evenly distributing flow is as follows: a force opposite to the gas flow direction is applied to the fluid ball through a contraction spring; when the gas flow is zero, the fluid ball fits against the inner wall of the gradually converging and expanding tube under the action of the contraction spring; when the gas flow increases, the fluid ball moves in the direction of the gas flow, and the larger the gas flow, the larger the gap between the gradually converging and expanding tube and the fluid ball, the larger the spring length, and the greater the restraining force on the fluid ball.

[0013] The beneficial effects of the present invention are:

[0014] 1. The present invention is provided with an in-tube partition structure to disperse the two fluids into small tributaries, and arrange the tributaries of different gas types in sequence to achieve rapid and uniform mixing.

[0015] 2. The present invention sets the same flow equalizer in each branch of the gas channel, and quickly realizes branch flow uniformity control when the flow changes by balancing the pressure loss of each branch.

[0016] 3. The present invention combines the partition structure with the flow equalizer, which can not only achieve sufficient mixing of natural gas with hydrogen, but also quickly establish component balance when the flow changes, and achieve uniformity and flow control at the same time. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 Schematic diagram of the mixer air intake method;

[0018] Figure 2 It is the cross-section diagram of the square pipe;

[0019] Figure 3 This is a schematic diagram of the division of the space inside the tube;

[0020] Figure 4 It is a schematic diagram of the partition structure in the tube;

[0021] Figure 5 It is a schematic diagram of mixed fluid partitioning;

[0022] Figure 6 Schematic diagram of the mixing process for adjacent jets;

[0023] Figure 7 It is a schematic diagram of pipeline flow with and without flow equalizer;

[0024] Figure 8 is a schematic diagram of the current equalizer structure;

[0025] Fig. 9 The working principle diagram of the current equalizer (where: the upper figure is the state diagram of the current equalizer when the flow rate is zero, the middle figure is the state diagram of the current equalizer when the flow rate is relatively small, and the lower figure is the state diagram of the current equalizer when the flow rate is relatively large);

[0026] Fig.10 Schematic diagram of component fluctuations in the initial stage of mixing.

[0027] Explanation of the reference numerals: region one 1, region two 2, region three 3, region four 4, gradually converging and expanding tube 5, contraction spring 6, fluid ball 7. DETAILED DESCRIPTION

[0028] The present invention is further described below in conjunction with embodiments. The description of the following embodiments is only used to help understand the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principles of the present invention, several improvements and modifications may be made to the present invention, and these improvements and modifications also fall within the scope of protection of the claims of the present invention.

[0029] The natural gas hydrogen blending device with uniform flow distribution of the present invention can quickly establish component balance when the flow changes on the basis of sufficient mixing of natural gas and hydrogen.

[0030] Embodiment 1

[0031] Embodiment 1 of the present application provides a natural gas hydrogen blending device with uniform flow distribution, which can achieve sufficient mixing of natural gas and hydrogen.

[0032] like Figure 2 As shown, this embodiment uses a square pipe instead of a circular pipe, which is easier to understand. The circular pipe can also achieve the same effect using the same principle.

[0033] like Figure 1 As shown, in the natural gas hydrogen blending device with uniform flow distribution of this embodiment, the gas to be mixed is fed in the following manner: two streams are fed in along the axial direction of the tube and in the radial direction of the tube side. The mixed gas is discharged along the axial direction of the tube. Since the natural gas accounts for more than 80% and the hydrogen accounts for only less than 20% in the natural gas hydrogen blending process, the natural gas in this embodiment is fed in along the axial direction of the tube, and the hydrogen is fed in radially on the tube side.

[0034] like Figure 3 The figure shows the division of the space inside a section of the pipe at the gas inlet. The square grid structure is used to divide the space inside the square pipe into two parts, one is area 1, and the other is area 2 (which can be defined as a partition structure). Area 1 is divided into multiple independent parts, while area 2 is a connected whole. Furthermore, the axial structure of the pipe is as follows: Figure 3 As shown in the AA section, in the direction along the pipe axis, the structure of the second region is local, that is, the second region divides the space inside the pipe locally, and the BB section further illustrates that the second region is a whole. In this embodiment, the inlet of natural gas does not need to be further described. Figure 3 The middle area 1 was originally connected to the pipelines at the front end and the back end, and further description of area 2 is required.

[0035] like Figure 4 As shown, Figure 3 The partition structure is further described in terms of area 2 (partition structure). Although the partition structure is a whole, it is also divided into area 3 and area 4 by partitions. Area 3 and area 4 are not connected to each other. The square grid at the node of the square grid of the partition structure is area 4, and the square grid at the four sides of area 4 is area 3. There are two ways to design the partition structure: ① Figure 4 In the middle, area three is circulation space and area four is closed space;② Figure 4 In the example, area 3 is a closed space and area 4 is a circulation space. Figure 4As shown in the AA section, the partition structure can use a pipeline to take in air from outside the pipe. The upstream side of the partition structure is not connected to the outside world, and the downstream side of the partition structure is partially connected. Area 4 is a plurality of independent closed spaces without ventilation, that is, area 4 is solid, or the inside can also be hollow, and all the surfaces are closed and the inside is not ventilated. The role of area 4 is to make areas 3 independent of each other, and each channel of area 3 is independently ventilated. Further explanation: Figure 4 The overall partition structure in the middle, viewed from the AA section (the direction from left to right here is Figure 1 In the direction from left to right), at the beginning, all the areas are connected, that is, the area three on the left in AA is connected, and then starting from a certain position, there is area four. The existence of area four divides the entire flow into multiple branches.

[0036] The single stream of natural gas and hydrogen is divided into multiple sub-streams by dividing the space inside the pipe, and these sub-streams are arranged in a matrix in sequence according to different media, which helps to evenly mix the natural gas and hydrogen.

[0037] like Figure 5 As shown in the figure, A is the natural gas channel, B is the hydrogen channel, and there are two possible partitions for the mixed fluid. Figure 5 There are two partitioning methods: in the left figure, natural gas is connected to area 1 and hydrogen is connected to area 4, that is, the partition structure adopts design method ②. As can be seen from the figure, the distribution of A and B is more uniform, and each A (B) is in contact with 4 B (A) corners; while in the right figure, natural gas is connected to area 1 and hydrogen is connected to area 3, that is, the partition structure adopts design method ①. As can be seen from the figure, although the B around A is evenly distributed, for each B, only the up and down or left and right directions are in contact with A, and the distribution is uneven. Therefore, the partitioning method in the left figure can better achieve uniform mixing.

[0038] like Figure 6 As shown, since the gas jet undergoes a radial expansion process after being ejected, the area in the separation structure where no fluid flows will not affect the overall mixing process.

[0039] Embodiment 2

[0040] Embodiment 2 of the present application provides a flow equalizer disposed in a gas channel, which can quickly establish component balance when the flow rate changes and avoid the fluctuation section of the mixing process.

[0041] Resistance along the way:

[0042]

[0043] Where: λ represents the resistance coefficient along the way; l represents the pipe length; d represents the pipe diameter; v represents the flow velocity; and g represents the acceleration due to gravity.

[0044] Local resistance:

[0045]

[0046] Where: ζ is the local resistance coefficient; v is the flow velocity; g is the acceleration due to gravity.

[0047] like Figure 7 As shown in the figure on the left, the conventional parallel connection of the branch flow is shown. Due to the different lengths l and local resistance coefficients ζ of each branch flow, even if F is reached after a period of time, OA =F OB =F OC =F OD =F OE (After reaching equilibrium, the resistance loss of the parallel pipelines is equal; where F OA 、F OB 、F OC 、F OD 、F OE Indicates the resistance of each parallel pipeline, which is the sum of the resistance along the way and the local resistance). It is also impossible to ensure that the flow rates of ports A, B, C, D, and E are uniform. The middle and right figures show the situation where the same flow equalizer is set in each branch. When there is a flow equalizer, corresponding to a certain flow rate, if the flow equalizer resistance F 均流器 >>max(F OA ,F OB ,F OC ,F OD ,F OE )-min(F OA ,F OB ,F OC ,F OD ,F OE ), when considering the total loss, the original resistance along the way and the local resistance without flow equalizer can be ignored. According to F 均流器 The monotonicity of the corresponding relationship with the flow Q, through the flow equalizer, makes the F' of different branches OA =F' OB =F' OC =F' OD =F' OE (F' OA 、F' OB 、F' OC 、F' OD 、F' OE Indicates that after adding the flow equalizer, the resistance of each parallel pipeline is approximately established, and the flow of branches A, B, C, D, and E is uniform. In addition, since the fluid will preferentially choose the path with low pressure loss to pass through, when F' OA =F' OB =F' OC =F' OD =F' OEWhen it is not established, the flow of branches A, B, C, D, and E is also inconsistent. A flow balance will be established quickly to make F' OA =F' OB =F' OC =F' OD =F' OE The flow rate in the right figure is greater than that in the middle figure.

[0048] like Figure 8 As shown, the hydrogen channel must be equipped with a flow equalizer, that is, Figure 5 Area B. It is best to set a flow equalizer in the natural gas channel (area A). Because natural gas flows along the main pipe direction, while hydrogen enters from the side, it is difficult to distribute the pressure. The flow equalizer includes a gradually converging and expanding tube 5, a contraction spring 6, and a fluid ball 7. A contraction spring 6 is provided at the front end of the gradually converging and expanding tube 5. The contraction spring 6 is connected to the fluid ball 7. The fluid ball 7 fits the narrowest section of the gradually converging and expanding tube 5. Fig. 9 As shown, by contracting the spring, a force opposite to the flow direction is applied to the fluid ball. The larger the fluid flow rate, the larger the gap between the corresponding gradually converging and expanding tube and the fluid ball, the larger the spring length, and the greater the restraining force on the fluid ball.

[0049] By setting the same flow equalizer in different shunt branches (the shunt branches have the same size), uniform control of branch flow can be quickly achieved.

Claims

1. A natural gas hydrogen blending device with uniform flow distribution, characterized in that: It comprises a partition structure and a flow equalizer; the square pipe is provided with a natural gas inlet and a hydrogen inlet, the natural gas inlet is arranged along the pipe axis, and the hydrogen inlet is arranged along the radial direction of the pipe side; a square grid-shaped partition structure is provided inside the square pipe, and the partition structure divides the space inside the square pipe into area one (1) and area two (2); area one is divided into a plurality of mutually independent parts, and area two is a connected whole; area two is divided into area three (3) and area four (4), wherein the square grid at the node of the square grid-shaped partition structure is area four, and the square grid at the four sides of area four is area three; area three is the circulation space Area 4 is a closed space, or area 3 is a closed space and area 4 is a circulation space; area 1 is used as a natural gas channel, and area 3 or area 4 of the partition structure is used as a hydrogen channel; a flow equalizer is arranged in the hydrogen channel, and the flow equalizer comprises a gradually converging and expanding tube (5), a contraction spring (6) and a fluid ball (7); a contraction spring (6) is arranged at the front end of the gradually converging and expanding tube (5), the contraction spring (6) is connected to the fluid ball (7), and the fluid ball (7) fits the narrowest section of the gradually converging and expanding tube (5); in the direction along the tube axis, the structure of area 2 is local; a flow equalizer is arranged in the natural gas channel.

2. The natural gas hydrogen blending device with uniform flow distribution according to claim 1 is characterized in that: Area one serves as a natural gas channel, and area four serves as a hydrogen channel, and the natural gas channel and the hydrogen channel are in corner contact with each other.

3. The natural gas hydrogen blending device with uniform flow distribution according to claim 1, characterized in that: Area one serves as a natural gas channel, and area three serves as a hydrogen channel. Each hydrogen channel contacts the natural gas channel in two directions, up and down or left and right.

4. A method for operating a natural gas hydrogen blending device with uniform flow distribution as claimed in claim 1, characterized in that: Through the contraction spring, a force opposite to the gas flow direction is applied to the fluid ball; when the gas flow is zero, the fluid ball fits against the inner wall of the gradually converging and expanding tube under the action of the contraction spring; when the gas flow increases, the fluid ball moves in the direction of the gas flow. The larger the gas flow, the larger the gap between the gradually converging and expanding tube and the fluid ball, the larger the spring length, and the greater the restraining force on the fluid ball.

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