Wide-flow accurate natural gas hydrogen doping device and natural gas hydrogen doping method

Abstract

The invention relates to the technical field of natural gas hydrogen doping, and provides a wide-flow accurate natural gas hydrogen doping device and a natural gas hydrogen doping method. The wide-flow accurate natural gas hydrogen doping device comprises a natural gas pipeline, a hydrogen pipeline, a gas mixing pipeline and a PLC (Programmable Logic Controller) control system, the PLC control system sets the hydrogen doping proportion and controls the opening degree of the first flow transmitter of the natural gas pipeline, the opening degree of the flow adjusting valve of the hydrogen pipeline and the opening and closing of the buffer tank, and therefore the purpose of adjusting the hydrogen doping proportion of gas led out of the gas mixing pipeline is achieved. According to the wide-flow accurate natural gas hydrogen doping device, the effects that the hydrogen doping proportion is accurately controlled, hydrogen doping mixing is uniform and the system can be comprehensively and integrally controlled can be achieved according to the characteristics that the gas consumption rule of an urban gas pipe network is large in gas consumption flow, wide in flow and large in gas consumption peak-valley difference.

Description

Technical Field

[0001] The present application relates to the technical field of natural gas hydrogen blending, and in particular to a wide flow and accurate natural gas hydrogen blending device and a natural gas hydrogen blending method. Background Art

[0002] Urban natural gas is used in a wide range, and its usage pattern shows obvious peak-to-valley differences. For example, a medium-pressure regulating station of a gas company has a peak gas usage at around 6 p.m., and the flow rate of the regulating station can reach 18,000 Nm 3 / h, the gas consumption trough occurs around 4 a.m., with a flow rate of less than 1000Nm 3 / h. For existing blending devices, in order to ensure a constant hydrogen blending ratio, a flow-following blending technology is usually used. This technology is measured through a flow meter and a signal is fed back to the regulating valve for flow-following adjustment of a fixed hydrogen blending ratio. However, in actual engineering practice, it is found that this type of technology can only be used for situations where the gas flow is relatively stable and only fluctuates around the design load.

[0003] Therefore, the current natural gas hydrogen blending device can only control the gas pipeline network with a narrow gas usage range and a small peak-to-valley difference, and cannot meet the requirements of urban gas pipeline networks with a wide gas usage range and a large peak-to-valley difference. Summary of the invention

[0004] In view of the above-mentioned deficiencies in the prior art, the purpose of this application is to provide a natural gas hydrogen blending device with a wide flow rate and precision, aiming to solve the problem that the natural gas hydrogen blending device in the prior art can only control the gas pipeline network with a narrow gas usage range and a small peak-to-valley difference.

[0005] The technical solution adopted by the present application to solve the technical problem is as follows: The present application provides a wide flow and accurate natural gas hydrogen blending device, including a natural gas pipeline, a hydrogen pipeline, a mixed gas pipeline and a PLC control system.

[0006] The gas mixing pipeline is provided with a mixer and a buffer tank connected in sequence; one end of the natural gas pipeline is connected to the mixer, and the other end is a natural gas inlet end; a first flow transmitter is provided between the natural gas inlet end and the mixer; one end of the hydrogen pipeline is connected to the mixer, and the other end is a hydrogen inlet end; a second flow transmitter and a flow regulating valve connected in sequence are provided between the hydrogen inlet end and the mixer; one end of the gas mixing pipeline is connected to the mixer, and the other end is a mixed gas outlet end connected to the outside through the buffer tank; the hydrogen analyzer is provided between the mixer and the buffer tank.

[0007] The first flow transmitter, the second flow transmitter, the flow regulating valve, the hydrogen analyzer and the buffer tank are all connected to the PLC control system signal; the PLC control system sets the hydrogen blending ratio, and controls the opening of the first flow transmitter of the natural gas pipeline, the opening of the flow regulating valve of the hydrogen pipeline and the opening and closing of the buffer tank, so as to achieve the purpose of adjusting the hydrogen blending ratio of the gas discharged from the mixing pipeline.

[0008] Optionally, the natural gas pipeline includes a natural gas large flow branch and a natural gas small flow branch, and the natural gas large flow branch and the natural gas small flow branch are connected in parallel; the intersection of the natural gas pipeline with the left end of the natural gas large flow branch is the first intersection, and the intersection with the right end of the natural gas large flow branch is the second intersection; the first flow transmitter is arranged on the natural gas large flow branch and the natural gas small flow branch.

[0009] The hydrogen pipeline includes a large hydrogen flow branch and a small hydrogen flow branch, and the large hydrogen flow branch and the small hydrogen flow branch are connected in parallel; the intersection of the hydrogen pipeline with the left end of the large hydrogen flow branch is the third intersection, and the intersection with the right end of the large hydrogen flow branch is the fourth intersection; the second flow transmitter and the flow regulating valve connected in sequence are both arranged on the large hydrogen flow branch and the small hydrogen flow branch.

[0010] Optionally, the left end of the natural gas large flow branch and the left end of the natural gas small flow branch intersect at the first intersection, and the right end of the natural gas large flow branch and the right end of the natural gas small flow branch intersect at the second intersection; a first nitrogen purge port, a first pressure gauge, a first temperature gauge, a first ball valve, a first filter, a first stabilizing valve and a first vent valve are sequentially arranged between the natural gas inlet end and the first intersection.

[0011] Optionally, the left end of the large hydrogen flow branch and the left end of the small hydrogen flow branch intersect at the third intersection, and the right end of the large hydrogen flow branch and the right end of the small hydrogen flow branch are compared to the fourth intersection; a second nitrogen purge port, a second vent valve, a second pressure gauge, a second thermometer, a second ball valve, a second filter, and a second stabilization valve are sequentially arranged between the hydrogen inlet end and the third intersection.

[0012] Optionally, a first cut-off valve is arranged between the first flow transmitter of the large natural gas flow branch and the first intersection, and a first ball valve is arranged between the first flow transmitter of the large natural gas flow branch and the second intersection; and / or, a first cut-off valve is arranged between the first flow transmitter of the small natural gas flow branch and the first intersection, and a first ball valve is arranged between the first flow transmitter of the small natural gas flow branch and the second intersection.

[0013] Optionally, a second ball valve is arranged between the second flow transmitter of the large hydrogen flow branch and the third intersection, and a second ball valve is arranged between the flow regulating valve of the large hydrogen flow branch and the fourth intersection; and / or, a second ball valve is arranged between the second flow transmitter of the small hydrogen flow branch and the third intersection, and a second ball valve is arranged between the flow regulating valve of the small hydrogen flow branch and the fourth intersection.

[0014] Optionally, a third pressure gauge, a third temperature gauge, a third nitrogen purge port, a third ball valve, a flame arrester and a third shut-off valve are sequentially arranged between the mixer and the buffer tank, and the hydrogen analyzer is located between the flame arrester and the third shut-off valve.

[0015] The present application also provides a natural gas hydrogen blending method, which uses the above-mentioned wide flow and accurate natural gas hydrogen blending device to blend hydrogen into a natural gas pipeline, comprising the following steps: S1: according to the maximum design demand Q of the hydrogen-blended natural gas m And the target supply demand Q of hydrogen-blended natural gas, the PLC control system sets the hydrogen blending ratio λ.

[0016] S2: According to the target supply demand Q of hydrogen-blended natural gas and the hydrogen blending ratio λ, the opening of the first flow transmitter of the natural gas pipeline, the opening of the flow regulating valve of the hydrogen pipeline and the opening and closing of the buffer tank are controlled to blend hydrogen into the natural gas.

[0017] The method of controlling the opening of the first flow transmitter of the natural gas pipeline, the opening of the flow regulating valve of the hydrogen pipeline, and the opening and closing of the buffer tank according to the target supply demand Q of the hydrogen-blended natural gas and the hydrogen blending ratio λ comprises the following steps: when the target supply demand Q of the hydrogen-blended natural gas is 20%Q m To 100% Q m When the flow rate of the natural gas branch is low, the flow rate transmitter of the natural gas branch with large flow rate and the flow rate regulating valve of the hydrogen branch with large flow rate are opened, and the remaining first flow transmitters and flow rate regulating valves are closed.

[0018] When the target supply demand of hydrogen-blended natural gas is 6%Q m Up to 30%Q m When the flow rate of the natural gas branch is low, the first flow transmitter of the natural gas branch and the flow regulating valve of the hydrogen branch are opened, and the remaining first flow transmitters and flow regulating valves are closed.

[0019] When the target supply demand of hydrogen-blended natural gas Q is less than 6% Q m When the flow rate is high, close all the first flow transmitters and flow control valves, and only open the buffer tank.

[0020] Optionally, the flow range of the natural gas large flow branch is 0.2(1-λ)Q m to (1-λ)Q mThe flow range of the natural gas small flow branch is 0.06(1-λ)Q m To 0.3(1-λ)Q m The flow range of the large hydrogen flow branch is 0.2λQ m To λQ m ; The flow range of the hydrogen small flow branch is 0.06λQ m Up to 0.3λQ m .

[0021] Optionally, when only the buffer tank is opened, the pressure of the buffer tank after being filled is: Among them, P 2 is the pressure after the buffer tank is filled, Pa; Q m is the maximum design demand for hydrogen-blended natural gas, Nm 3 / s;P 0 is the gas supply pressure of the natural gas pipeline, Pa; P m is the atmospheric pressure, Pa; ρ is the density of hydrogen-blended natural gas under standard operating conditions when the blending ratio is λ, kg / m 3 ; A is the cross-sectional area of ​​the buffer tank inlet, m 2 ; ξ is the flow coefficient.

[0022] The water volume of the buffer tank is: Among them, V 缓冲罐 is the water volume of the buffer tank, m 3 ; n is the inflation time, min; Q m is the maximum design demand for hydrogen-blended natural gas, Nm 3 / s;P m is atmospheric pressure, Pa; P 2 is the pressure after the buffer tank is filled, Pa; P 1 is the pressure alarm value of the buffer tank, Pa.

[0023] Compared with the prior art, the present application provides a wide flow rate accurate natural gas hydrogen blending device and a natural gas hydrogen blending method; wherein, the wide flow rate accurate natural gas hydrogen blending device sets the hydrogen blending ratio λ through a PLC control system according to the target supply demand Q of the hydrogen-blended natural gas, connects the natural gas pipeline, the hydrogen pipeline and the buffer tank by signal, transports the natural gas through the natural gas pipeline, transports the hydrogen through the hydrogen pipeline, mixes and blends in a mixer to obtain the required hydrogen-blended natural gas, passes the hydrogen-blended natural gas into the buffer tank for buffering and then passes it out for use, so that the gas passed out of the mixed gas pipeline is mixed uniformly; during the process, the hydrogen blending uniformity and gas volume of the hydrogen-blended natural gas can be analyzed by a hydrogen analyzer, so that the delivery volume of the natural gas and hydrogen can be adjusted by the PLC control system to achieve the effect of accurately controlling the hydrogen blending ratio; and when the hydrogen blending ratio is small, gas can be supplied through the buffer tank, which can prevent the first flow transmitter, the flow control valve and other flow control instruments from oscillating back and forth quickly and causing inaccurate metering, thereby meeting the requirement of accurately controlling the hydrogen blending ratio and also widening the gas flow range passed out of the mixed gas pipeline. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a schematic diagram of a wide flow rate and accurate natural gas hydrogen blending device provided in the present application;

[0025] Figure 2 It is a gas flow diagram of a wide flow and accurate natural gas hydrogen blending device provided in this application.

[0026] Description of reference numerals:

[0027] N1, natural gas pipeline; N11, natural gas high flow branch; N12, natural gas low flow branch; N2, hydrogen pipeline; N21, hydrogen high flow branch; N22, hydrogen low flow branch; N3, mixed gas pipeline; A, first intersection; B, second intersection; C, third intersection; D, fourth intersection; 11, first pressure gauge; 110, first nitrogen purge port; 12, first thermometer; 13, first ball valve; 14, first filter; 15, first stabilizing valve; 16, first vent valve; 17, first shut-off valve; 18, first flow transmitter; 19, first check valve; 21, second pressure gauge ; 211, flow regulating valve; 210, second nitrogen purge port; 22, second thermometer; 23, second ball valve; 24, second filter; 25, second stabilizing valve; 26, second vent valve; 27, second shut-off valve; 28, second flow transmitter; 29, second check valve; 30, mixer; 301, differential pressure gauge; 302, drain port; 31, third pressure gauge; 310, third nitrogen purge port; 32, third thermometer; 33, third ball valve; 34, flame arrester; 35, hydrogen analyzer; 36, stop valve; 37, third shut-off valve; 38, buffer tank; 39, third vent valve. DETAILED DESCRIPTION

[0028] The embodiments of the present application are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present application, and cannot be understood as limiting the present application.

[0029] In the description of the present application, it should be understood that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present application. In addition, the terms "first" and "second" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present application, unless otherwise specified, "multiple" means two or more.

[0030] 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 or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0031] It should also be noted that the illustrations provided in the following embodiments are only schematic illustrations of the basic concept of the present application. The drawings only show components related to the present application rather than being drawn according to the number, shape and size of components in actual implementation. In actual implementation, the type, quantity and proportion of each component may be changed arbitrarily, and the component layout may also be more complicated.

[0032] In this application, all pressures are absolute pressures.

[0033] Additionally, in the following description, specific details are provided to provide a thorough understanding of the embodiments. However, one skilled in the art will appreciate that the aspects described may be practiced without these specific details.

[0034] Combined with reference Figure 1 and Figure 2In the first embodiment of the present application, a wide flow and accurate natural gas hydrogen blending device is provided, including a natural gas pipeline N1, a hydrogen pipeline N2, a mixed gas pipeline N3 and a PLC control system (not shown in the figure).

[0035] The gas mixing pipeline N3 is provided with a mixer 30 and a buffer tank 38 connected in sequence; one end of the natural gas pipeline N1 is connected to the mixer 30, and the other end is a natural gas inlet end; a first flow transmitter 18 is provided between the natural gas inlet end and the mixer 30; one end of the hydrogen pipeline N2 is connected to the mixer 30, and the other end is a hydrogen inlet end; a second flow transmitter 28 and a flow regulating valve 211 connected in sequence are provided between the hydrogen inlet end and the mixer 30; one end of the gas mixing pipeline N3 is connected to the mixer 30, and the other end is a mixed gas outlet end connected to the outside through the buffer tank 38; the hydrogen analyzer 35 is provided between the mixer 30 and the buffer tank 38.

[0036] The first flow transmitter 18, the second flow transmitter 28, the flow regulating valve 211, the hydrogen analyzer 35 and the buffer tank 38 are all connected to the PLC control system signal; the PLC control system sets the hydrogen blending ratio, and controls the opening of the first flow transmitter 18 of the natural gas pipeline N1, the opening of the flow regulating valve 211 of the hydrogen pipeline N2 and the opening and closing of the buffer tank 38, so as to achieve the purpose of adjusting the hydrogen blending ratio of the gas discharged from the mixing pipeline N3.

[0037] The hydrogen analyzers 35 can be distributed at different positions of the same cross section of the gas mixing pipeline N3 to detect the uniformity of mixing and the amount of hydrogen mixed, and calculate the hydrogen mixing ratio. That is, there can be several hydrogen analyzers 35, which are arranged at different positions of the same cross section of the gas mixing pipeline N3.

[0038] The wide flow and precise natural gas hydrogen blending device of this embodiment is designed to achieve the effects of precise control of the hydrogen blending ratio, uniform mixing of hydrogen blending, and comprehensive integrated control of the system, based on the gas consumption patterns of urban gas pipeline networks, which are characterized by large gas flow, wide flow, and large peak-to-valley difference in gas consumption. Specifically, through the combination of the natural gas pipeline N1, the hydrogen pipeline N2 and the buffer tank 38, when the target supply demand Q of the hydrogen-blended natural gas is large, the natural gas pipeline N1 and the hydrogen pipeline N2 are combined with the hydrogen blending ratio to provide natural gas and hydrogen for mixing, so as to obtain the gas discharged from the mixed gas pipeline N3; when the target supply demand Q of the hydrogen-blended natural gas is small, the hydrogen-blended natural gas stored in the buffer tank 38 is directly provided to obtain the flow rate of the gas discharged from the mixed gas pipeline N3, thereby widening the flow rate range of the gas discharged from the mixed gas pipeline N3, and having the characteristic of "wide flow rate"; and it can prevent the flow rate from being too low to affect the instrument accuracy of the first flow transmitter 18, the second flow transmitter 28, the flow regulating valve 211, and the hydrogen analyzer 35, and can accurately control the hydrogen blending ratio of the gas discharged from the mixed gas pipeline N3, and has the characteristic of "precision".

[0039] The embodiment of the invention is a natural gas hydrogen blending device with wide flow rate and precision. According to the target supply demand Q of hydrogen-blended natural gas, the hydrogen blending ratio λ is set through the PLC control system, and the signals are connected to the natural gas pipeline N1, the hydrogen pipeline N2 and the buffer tank 38. The natural gas is transported through the natural gas pipeline N1, the hydrogen is transported through the hydrogen pipeline N2, and the required hydrogen-blended natural gas is mixed and doped in the mixer 30. The hydrogen-blended natural gas is passed into the buffer tank 38 for buffering and then passed out for use, so that the gas passed out of the gas mixing pipeline N3 is mixed uniformly. During the process, the hydrogen blending uniformity and gas volume of the hydrogen-blended natural gas can be analyzed by the hydrogen analyzer 35, so that the delivery volume of the natural gas and hydrogen can be adjusted through the PLC control system to achieve the effect of accurately controlling the hydrogen blending ratio. Moreover, when the hydrogen blending ratio is small, gas can be supplied through the buffer tank 38, which can prevent the first flow transmitter 18, the flow regulating valve 211 and other flow regulating instruments from oscillating back and forth quickly and causing inaccurate metering, thereby meeting the requirement of accurately controlling the hydrogen blending ratio and widening the gas flow range passed out of the gas mixing pipeline N3.

[0040] In some embodiments, the natural gas pipeline N1 includes a natural gas large flow branch N11 and a natural gas small flow branch N12, and the natural gas large flow branch N11 and the natural gas small flow branch N12 are connected in parallel; the intersection of the natural gas pipeline N1 and the left end of the natural gas large flow branch N11 is a first intersection A, and the intersection with the right end of the natural gas large flow branch N11 is a second intersection B; the first flow transmitter 18 is arranged at the natural gas large flow branch N11 and the natural gas small flow branch N12 On; the hydrogen pipeline N2 includes a large hydrogen flow branch N21 and a small hydrogen flow branch N22, and the large hydrogen flow branch N21 and the small hydrogen flow branch N22 are connected in parallel; the intersection of the hydrogen pipeline N2 and the left end of the large hydrogen flow branch N21 is the third intersection C, and the intersection with the right end of the large hydrogen flow branch N21 is the fourth intersection D; the second flow transmitter 28 and the flow regulating valve 211 connected in sequence are both arranged on the large hydrogen flow branch N21 and the small hydrogen flow branch N22.

[0041] That is, the natural gas flow of the large natural gas flow branch N11 can be controlled by the first flow transmitter 18 on the large natural gas flow branch N11, and the natural gas flow of the small natural gas flow branch N12 can be controlled by the first flow transmitter 18 on the small natural gas flow branch N12; the hydrogen flow of the large hydrogen flow branch N21 can also be controlled by the second flow transmitter 28 and the flow regulating valve 211 on the large hydrogen flow branch N21, and the hydrogen flow of the small hydrogen flow branch N22 can be controlled by the second flow transmitter 28 and the flow regulating valve 211 on the small hydrogen flow branch N22.

[0042] The instrument range on the natural gas large flow branch N11 is different from the instrument range of the natural gas small flow branch N12. Specifically, the instrument range on the natural gas large flow branch N11 is larger than the instrument range of the natural gas small flow branch N12. According to the required natural gas ventilation volume, you can choose to use the natural gas large flow branch N11 or the natural gas small flow branch N12 for ventilation, thereby ensuring that during the natural gas ventilation process, the instruments on the branch are within the optimal detection range, and will not cause inaccurate measurement due to rapid back and forth oscillations, thereby ensuring the control accuracy of the natural gas pipeline N1.

[0043] Similarly, the instrument range on the hydrogen large flow branch N21 is different from the instrument range of the hydrogen small flow branch N22. Specifically, the instrument range on the hydrogen large flow branch N21 is larger than the instrument range of the hydrogen small flow branch N22. Depending on the required hydrogen ventilation volume and hydrogen blending ratio, you can choose to use the hydrogen large flow branch N21 or the hydrogen small flow branch N22 for ventilation, thereby ensuring that during the hydrogen ventilation process, the instruments on the branch are within the optimal detection and control range, and will not cause inaccurate measurement due to rapid back and forth oscillations. This can ensure the control accuracy of the hydrogen pipeline N2 and make the hydrogen blending ratio in the mixed gas more accurately controlled.

[0044] In some embodiments, the left end of the natural gas large flow branch N11 and the left end of the natural gas small flow branch N12 intersect at the first intersection A, and the right end of the natural gas large flow branch N11 and the right end of the natural gas small flow branch N12 intersect at the second intersection B; a first nitrogen purge port 110, a first pressure gauge 11, a first thermometer 12, a first ball valve 13, a first filter 14, a first stabilizing valve 15 and a first vent valve 16 are sequentially arranged between the natural gas inlet end and the first intersection A.

[0045] The first nitrogen purge port 110, the first pressure gauge 11, the first thermometer 12, the first ball valve 13, the first filter 14, the first stabilizing valve 15 and the first vent valve 16 can all be connected to the PLC control system to build a system for monitoring and controlling the natural gas pipeline N1. The first nitrogen purge port 110 is installed at the natural gas inlet end to ensure the cleanliness and safety of the pipeline at the natural gas inlet end; the first pressure gauge 11 and the first thermometer 12 are used to detect the pressure and temperature in the pipeline respectively; the first ball valve 13 is used to control the opening and closing of the pipeline; the first filter 14 is used to filter impurities in the pipeline; the first stabilizing valve 15 and the first vent valve 16 are used to control the pressure of the pipeline.

[0046] At the same time, a first thermometer 12 may be provided between the first stabilizing valve 15 and the first venting valve 16 to observe temperature changes during the pressure regulation or venting process, thereby monitoring the internal conditions of the pipeline in real time.

[0047] Similarly, in some embodiments, the left end of the large hydrogen flow branch N21 and the left end of the small hydrogen flow branch N22 intersect at the third intersection C, and the right end of the large hydrogen flow branch N21 and the right end of the small hydrogen flow branch N22 are compared to the fourth intersection D; a second nitrogen purge port 210, a second vent valve 26, a second pressure gauge 21, a second thermometer 22, a second ball valve 23, a second filter 24, and a second stabilization valve 25 are sequentially arranged between the hydrogen inlet end and the third intersection C.

[0048] The second nitrogen purge port 210, the second vent valve 26, the second pressure gauge 21, the second thermometer 22, the second ball valve 23, the second filter 24, and the second stabilizing valve 25 can all be connected to the PLC control system to build a system for monitoring and regulating the hydrogen pipeline N2. The second nitrogen purge port 210 is installed at the hydrogen inlet end to ensure the pipeline cleanliness and pipeline safety at the hydrogen inlet end; the second pressure gauge 21 and the second thermometer 22 are used to detect the pressure and temperature in the pipeline respectively; the second ball valve 23 is used to control the opening and closing of the pipeline; the second filter 24 is used to filter impurities in the pipeline; the second stabilizing valve 25 and the second vent valve 26 are used to control the pressure of the pipeline.

[0049] At the same time, a second shut-off valve 27 may be provided between the second filter 24 and the second stabilizing valve 25. When the temperature and pressure in the hydrogen pipeline N2 are abnormal, the second shut-off valve 27 may be promptly shut off to prevent leakage of hydrogen.

[0050] In some embodiments, a first shut-off valve 17 is provided between the first flow transmitter 18 of the natural gas large flow branch N11 and the first intersection A, and a first ball valve 13 is provided between the first flow transmitter 18 of the natural gas large flow branch N11 and the second intersection B; and / or, a first shut-off valve 17 is provided between the first flow transmitter 18 of the natural gas small flow branch N12 and the first intersection A, and a first ball valve 13 is provided between the first flow transmitter 18 of the natural gas small flow branch N12 and the second intersection B. The first shut-off valve 17 and the first ball valve 13 are both used to control the opening and closing of the natural gas large flow branch N11 and the natural gas small flow branch N12, and to ensure the safety of the branches. Both the first shut-off valve 17 and the first ball valve 13 can be connected to the PLC control system, so as to construct a system for monitoring and regulating the natural gas large flow branch N11 and the natural gas small flow branch N12.

[0051] A first check valve 19 may also be provided between the second intersection point B and the mixer 30 to allow the natural gas to flow in a fixed direction and prevent its reverse flow that would cause inaccurate flow monitoring.

[0052] In some embodiments, a second ball valve 23 is provided between the second flow transmitter 28 of the large hydrogen flow branch N21 and the third intersection C, and a second ball valve 23 is provided between the flow regulating valve 211 of the large hydrogen flow branch N21 and the fourth intersection D; and / or, a second ball valve 23 is provided between the second flow transmitter 28 of the small hydrogen flow branch N22 and the third intersection C, and a second ball valve 23 is provided between the flow regulating valve 211 of the small hydrogen flow branch N22 and the fourth intersection D. The second ball valve 23 is used to control the opening and closing of the large hydrogen flow branch N21 and the small hydrogen flow branch N22, and to ensure the safety of the branch. The second ball valve 23 can be connected to the PLC control system to construct a system for monitoring and regulating the large hydrogen flow branch N21 and the small hydrogen flow branch N22.

[0053] A second vent valve 26 may also be provided between the second stabilizing valve 25 and the third intersection C on the hydrogen pipeline N2. When the hydrogen in the pipeline is found to be abnormal, it is vented in time to prevent danger. A second thermometer 22 may also be provided between the second vent valve 26 and the second stabilizing valve 25 on the hydrogen pipeline N2, and it is possible to simultaneously judge whether the gas in the pipeline is abnormal in combination with the pipeline temperature displayed by the second thermometer 22. A second check valve 29 may also be provided between the fourth intersection D and the mixer 30, so that hydrogen flows in a fixed direction to prevent its reverse flow from causing inaccurate flow monitoring. In addition, since hydrogen has the characteristics of being flammable and explosive when leaked at a low content, a second thermometer 22 and a second pressure gauge 21 may also be provided between the second check valve 29 and the fourth intersection D.

[0054] In some embodiments, a third pressure gauge 31, a third thermometer 32, a third nitrogen purge port 310, a third ball valve 33, a fire arrester 34 and a third shut-off valve 37 are sequentially arranged between the mixer 30 and the buffer tank 38, and the hydrogen analyzer 35 is located between the fire arrester 34 and the third shut-off valve 37. The third pressure gauge 31, the third thermometer 32, the third nitrogen purge port 310, the third ball valve 33, the fire arrester 34 and the third shut-off valve 37 can be connected to the PLC control system to construct a system for monitoring and regulating the gas mixing pipeline N3. Among them, the third pressure gauge 31 and the third thermometer 32 are respectively used to detect the pressure and temperature in the pipeline; the third nitrogen purge port 310 is installed at the connection between the outlet end of the mixer 30 and the gas mixing pipeline N3 to ensure the cleanliness and safety of the pipeline; the third ball valve 33 and the third shut-off valve 37 are used to control the opening and closing of the pipeline to ensure the safety of the pipeline; the fire arrester 34 is used to prevent the spread of flames to prevent the flames from spreading to the pipeline and causing gas explosion when a fire occurs.

[0055] The mixer 30 may be provided with a differential pressure gauge 301 for measuring the flow rate of the gas introduced from the natural gas pipeline N1 and the hydrogen pipeline N2, so as to achieve the function of accurately controlling the proportion of hydrogen blended in the natural gas. The mixer 30 may also be provided with a sewage outlet 302 for discharging internal impurities.

[0056] The function of the buffer tank 38 is to cache the mixed gas after natural gas and hydrogen are doped. By caching, the gas amount in the pipeline in the device can be prevented from changing suddenly, so as to ensure that all instruments can be within the optimal detection and control range, and prevent rapid back and forth oscillations from causing inaccurate measurement. At the same time, when the required hydrogen-blended natural gas has a low hydrogen blending ratio, the mixed gas cached in the buffer can be directly replenished without being provided through the natural gas pipeline N1 and the hydrogen pipeline N2, which can prevent the instruments in the natural gas pipeline N1 and the hydrogen pipeline N2 from falling to low values, and prevent subsequent instrument measurement inaccuracy.

[0057] The buffer tank 38 is provided with a stop valve 36, a third thermometer 32 and a third vent valve 39; the stop valve 36 is used to cut off the liquid in the buffer tank 38, the third thermometer 32 is used to detect the temperature in the buffer tank 38, and the third vent valve 39 is used to vent the gas in the buffer tank 38 in an emergency.

[0058] Specifically, all equipment and instruments on the wide flow and precise natural gas hydrogen blending device can be connected to the PLC control system to achieve the effect of real-time detection and control of each equipment and instrument, improve the degree of automation, and enable the device to be controlled in an integrated manner.

[0059] Specific embodiment 1, a wide flow and accurate natural gas hydrogen blending device, includes a natural gas pipeline N1, a hydrogen pipeline N2, a mixed gas pipeline N3 and a PLC control system (not shown in the figure).

[0060] The gas mixing pipeline N3 is provided with a mixer 30 and a buffer tank 38 connected in sequence; one end of the natural gas pipeline N1 is connected to the mixer 30, and the other end is a natural gas inlet end; a first flow transmitter 18 is provided between the natural gas inlet end and the mixer 30; one end of the hydrogen pipeline N2 is connected to the mixer 30, and the other end is a hydrogen inlet end; a second flow transmitter 28 and a flow regulating valve 211 connected in sequence are provided between the hydrogen inlet end and the mixer 30; one end of the gas mixing pipeline N3 is connected to the mixer 30, and the other end is a mixed gas outlet end connected to the outside through the buffer tank 38; the hydrogen analyzer 35 is provided between the mixer 30 and the buffer tank 38.

[0061] The first flow transmitter 18, the second flow transmitter 28, the flow regulating valve 211, the hydrogen analyzer 35 and the buffer tank 38 are all connected to the PLC control system signal; the PLC control system sets the hydrogen blending ratio, and controls the opening of the first flow transmitter 18 of the natural gas pipeline N1, the opening of the flow regulating valve 211 of the hydrogen pipeline N2 and the opening and closing of the buffer tank 38, so as to achieve the purpose of adjusting the hydrogen blending ratio of the gas discharged from the mixing pipeline N3.

[0062] The hydrogen analyzers 35 can be distributed at different positions of the same cross section of the gas mixing pipeline N3 to detect the uniformity of mixing and the amount of hydrogen mixed, and calculate the hydrogen mixing ratio. That is, there can be several hydrogen analyzers 35, which are arranged at different positions of the same cross section of the gas mixing pipeline N3.

[0063] The natural gas large flow branch N11 and the natural gas small flow branch N12 are connected in parallel; the first flow transmitter 18 is arranged on the natural gas large flow branch N11 and the natural gas small flow branch N12; the hydrogen pipeline N2 includes a hydrogen large flow branch N21 and a hydrogen small flow branch N22, and the second flow transmitter 28 and the flow regulating valve 211 connected in sequence are both arranged on the hydrogen large flow branch N21 and the hydrogen small flow branch N22.

[0064] The specific comparative example 1 is different from the specific embodiment 1 only in that the natural gas pipeline N1 does not include the natural gas small flow branch N12, and the hydrogen pipeline N2 does not include the hydrogen small flow branch N22.

[0065] The specific comparative example 2 is different from the specific embodiment 1 only in that the buffer tank 38 is not included.

[0066] The second embodiment of the present application also provides a natural gas hydrogen blending method, which uses the wide flow and accurate natural gas hydrogen blending device of the first embodiment or its implementation mode to blend hydrogen into a natural gas pipeline, comprising the following steps:

[0067] S1: Based on the maximum design demand for hydrogen-blended natural gas Q m And the target supply demand Q of hydrogen-blended natural gas, the PLC control system sets the hydrogen blending ratio λ.

[0068] S2: According to the target supply demand Q of hydrogen-blended natural gas and the hydrogen blending ratio λ, the opening of the first flow transmitter of the natural gas pipeline, the opening of the flow regulating valve of the hydrogen pipeline and the opening and closing of the buffer tank are controlled to blend hydrogen into the natural gas.

[0069] Specifically, the first flow transmitter measures the natural gas flow, the second flow transmitter and the flow regulating valve measure the hydrogen flow, and after calculation, the PLC control system gives a signal, and the first flow transmitter, the second flow transmitter and the flow regulating valve adjust the opening according to the hydrogen blending ratio for rough adjustment; the hydrogen analyzer has high accuracy, and the hydrogen analyzer in the gas mixing pipeline performs secondary calibration, and after comparison with the set value of the hydrogen blending ratio, the signal is fed back to the first flow transmitter, the second flow transmitter and the flow regulating valve for fine adjustment, so as to improve the accuracy control of the hydrogen blending ratio of the hydrogen-blended natural gas finally obtained.

[0070] Wherein, the step S2 of controlling the opening of the first flow transmitter of the natural gas pipeline, the opening of the flow regulating valve of the hydrogen pipeline, and the opening and closing of the buffer tank according to the target supply demand Q of the hydrogen-blended natural gas and the hydrogen blending ratio λ comprises the following steps:

[0071] When the target supply demand of hydrogen-blended natural gas is 20%Q m To 100% Q m When the flow rate of the natural gas branch is low, the flow rate transmitter of the natural gas branch with large flow rate and the flow rate regulating valve of the hydrogen branch with large flow rate are opened, and the remaining first flow transmitters and flow rate regulating valves are closed.

[0072] When the target supply demand of hydrogen-blended natural gas is 6%Q m Up to 30%Q m When the flow rate of the natural gas branch is low, the first flow transmitter of the natural gas branch and the flow regulating valve of the hydrogen branch are opened, and the remaining first flow transmitters and flow regulating valves are closed.

[0073] When the target supply demand of hydrogen-blended natural gas Q is less than 6% Q m When the flow rate is high, close all the first flow transmitters and flow control valves, and only open the buffer tank.

[0074] Specifically, when the target supply demand of hydrogen-blended natural gas is 20%-100%Q m When the target supply demand Q of hydrogen-blended natural gas is 6%-30%, Q m When the target supply demand Q of hydrogen-blended natural gas is lower than 6%, Q m When the fuel is heated, the buffer tank provides hydrogen-blended natural gas.

[0075] The valve provided on the buffer tank can be controlled according to the target supply demand Q of the hydrogen-blended natural gas and the hydrogen blending ratio λ, thereby controlling the opening and closing degree of the buffer tank.

[0076] The target supply demand for hydrogen-blended natural gas is 20%-30%Q mPreferably, when the target supply demand Q of hydrogen-blended natural gas is 0.2Q m When the target supply demand Q of hydrogen-blended natural gas is around 0.3Q, the natural gas small flow branch and hydrogen small flow branch will provide natural gas and hydrogen respectively. m When the temperature fluctuates, the natural gas high flow branch and hydrogen high flow branch provide natural gas and hydrogen respectively. m <Q≤30%Q m , natural gas and hydrogen can be provided respectively by a large natural gas flow branch and a large hydrogen flow branch.

[0077] The hydrogen blending ratio λ (%) is based on the provisions of GB55009 on the calorific value and Wobbe number of 12T natural gas, and is generally within 5-20% (volume ratio); during the process of hydrogen blending of natural gas, the gas supply of the natural gas pipeline is (1-λ)Q m , the gas supply of the hydrogen pipeline is λQ m .

[0078] In some embodiments, the flow range of the natural gas high flow branch is 0.2(1-λ)Q m to (1-λ)Q m The flow range of the natural gas small flow branch is 0.06(1-λ)Q m To 0.3(1-λ)Q m The flow range of the large hydrogen flow branch is 0.2λQ m To λQ m ; The flow range of the hydrogen small flow branch is 0.06λQ m Up to 0.3λQ m Preferably, the flow rate of the natural gas pipeline is in the range of 9.6-160.0Nm 3 / h, the flow range of the large flow branch of natural gas is 32.0-160.0Nm 3 / h; the flow range of the small flow branch of natural gas is 9.6-48.0Nm 3 / h; the flow range of hydrogen pipeline is 0.1-40.0Nm 3 / h, the flow range of the large hydrogen flow branch is 8.0-40.0Nm 3 / h; the flow range of the small hydrogen flow branch is 2.4-12.0Nm 3 / h; the flow range of the mixed gas pipeline is 9.0-

[0079] 210.0Nm 3 / h. Specifically, the optimal operating ranges of the instruments and valves on the natural gas pipeline, hydrogen pipeline, and mixed gas pipeline correspond to the above flow ranges one by one, so as to improve the control accuracy of the instruments and valves on the pipeline.

[0080] In some embodiments, when only the buffer tank is opened, the pressure of the buffer tank after being filled is: Among them, P 2 is the pressure after the buffer tank is filled, Pa; Q m is the maximum design demand for hydrogen-blended natural gas, Nm 3 / s;P 0 is the gas supply pressure of the natural gas pipeline, Pa; P m is the atmospheric pressure, Pa; ρ is the density of hydrogen-blended natural gas under standard operating conditions when the blending ratio is λ, kg / m 3 ; A is the cross-sectional area of ​​the buffer tank inlet, m 2 ξ is the flow coefficient. In this formula, the pressure is absolute pressure.

[0081] The water volume of the buffer tank is: Among them, V 缓冲罐 is the water volume of the buffer tank, m 3 ; n is the inflation time, min; Q m is the maximum design demand for hydrogen-blended natural gas, Nm 3 / s;P m is atmospheric pressure, Pa; P 2 is the pressure after the buffer tank is filled, Pa; P 1 is the pressure alarm value of the buffer tank, Pa. In this formula, the pressure is absolute pressure.

[0082] The buffer tank is set with a pressure alarm value P 1 , that is, the pressure in the buffer tank drops to P 1 or P 1 When the pressure is below 200°C, the buffer tank cannot stably provide hydrogen-blended natural gas. During the process of providing hydrogen-blended natural gas, the actual pressure P in the buffer tank will change from P 2 Keep decreasing, when P≤P 1 When the flow rate of the natural gas branch is less than 0.06 Q, the first flow transmitter of the natural gas branch and the flow regulating valve of the hydrogen branch are opened again, and the natural gas branch and the hydrogen branch provide natural gas and hydrogen, and the first flow transmitter and the flow regulating valve are controlled so that the amount of hydrogen-blended natural gas measured in the hydrogen analyzer is within 0.06 Q. m When the actual pressure P in the buffer tank reaches P2, close the first flow transmitter of the natural gas small flow branch and the flow regulating valve of the hydrogen small flow branch, and stop replenishing gas.

[0083] The natural gas hydrogen blending method of the present embodiment controls the opening of the first flow transmitter of the natural gas pipeline, the opening of the flow regulating valve of the hydrogen pipeline, and the opening and closing of the buffer tank according to the target supply demand Q of the hydrogen-blended natural gas and the hydrogen blending ratio λ, thereby blending the natural gas with hydrogen, ensuring that under the conditions of different target supply demand Q of the hydrogen-blended natural gas, the equipment and instruments of the natural gas pipeline, the hydrogen pipeline, and the mixed gas pipeline can all be within the optimal working range, preventing the equipment or instruments from being damaged due to inaccurate metering due to rapid back-and-forth oscillations, thereby further ensuring the precise control of the hydrogen blending ratio of the mixed gas (i.e., hydrogen-blended natural gas) passed.

[0084] The natural gas hydrogen blending method of this embodiment is adopted, and the following three natural gas hydrogen blending operations are performed in sequence using specific embodiment 1 and specific comparative example 1 and specific comparative example 2 respectively, which is regarded as one round. The above operations are repeated ten times to check the deviation percentage of the hydrogen blending ratio between the obtained hydrogen-blended natural gas and the target hydrogen-blended natural gas.

[0085] The equipment and instruments in the specific embodiment 1, the specific comparative example 1 and the specific comparative example 2 correspond to each other and are of the same specifications. Specifically, the flow range of the natural gas pipeline is 9.6-160.0Nm 3 / h, the flow range of the large flow branch of natural gas is 32.0-160.0Nm 3 / h; the flow range of the small flow branch of natural gas is 9.6-48.0Nm 3 / h; the flow range of hydrogen pipeline is 2.4-40.0Nm 3 / h, the flow range of the large hydrogen flow branch is 8.0-40.0Nm 3 / h; the flow range of the small hydrogen flow branch is 2.4-12.0Nm 3 / h; the flow range of the mixed gas pipeline is 12-200Nm 3 / h.

[0086] First: The target supply demand for hydrogen-blended natural gas is 200 Nm 3 / h, and the hydrogen blending ratio λ is 20%. Specific Example 1 and specific Comparative Example 1 and specific Comparative Example 2 all provide natural gas and hydrogen through a natural gas large flow branch and a hydrogen large flow branch respectively.

[0087] Second: The target supply demand for hydrogen-blended natural gas is 30Nm 3 / h, and the hydrogen blending ratio λ is 20%. Specific Example 1 and Specific Comparative Example 2 both provide natural gas and hydrogen through a natural gas small flow branch and a hydrogen small flow branch respectively; Specific Comparative Example 1 provides natural gas and hydrogen through a natural gas large flow branch and a hydrogen large flow branch respectively.

[0088] The third time: The target supply demand of hydrogen-blended natural gas is 10Nm 3 / h, and the hydrogen blending ratio λ is 20%. Specific Example 1 uses a buffer tank to provide hydrogen-blended natural gas; Specific Comparative Example 2 provides natural gas and hydrogen respectively through a natural gas small flow branch and a hydrogen small flow branch; Specific Comparative Example 1 provides natural gas and hydrogen respectively through a natural gas large flow branch and a hydrogen large flow branch.

[0089] By repeating the above operation ten times using the device of specific embodiment 1, the deviation percentage of the hydrogen blending ratio of the obtained hydrogen-blended natural gas and the target hydrogen-blended natural gas did not exceed 1.5%; by repeating the above operation ten times using the device of specific comparative example 1, the deviation percentage of the hydrogen blending ratio of the obtained hydrogen-blended natural gas and the target hydrogen-blended natural gas was about 6%; by repeating the above operation ten times using the device of specific comparative example 2, the deviation percentage of the hydrogen blending ratio of the obtained hydrogen-blended natural gas and the target hydrogen-blended natural gas was about 6%; wherein, due to the large vibration of the instrument and valve under small flow rate (the third natural gas hydrogen blending operation), the wide flow rate and accurate natural gas hydrogen blending device is difficult to operate normally, and the deviation value cannot be calculated. Therefore, the deviation percentages of specific comparative examples 1 and 2 are mainly calculated as the average values ​​obtained by the first and second natural gas hydrogen blending operations.

[0090] In summary, the present application provides a wide flow and precise natural gas hydrogen blending device and a natural gas hydrogen blending method; wherein the wide flow and precise natural gas hydrogen blending device sets the hydrogen blending ratio λ through a PLC control system according to the target supply demand Q of the hydrogen-blended natural gas, connects the natural gas pipeline, the hydrogen pipeline and the buffer tank by signal, transports the natural gas through the natural gas pipeline, transports the hydrogen through the hydrogen pipeline, mixes and blends in the mixer to obtain the required hydrogen-blended natural gas, passes the hydrogen-blended natural gas into the buffer tank for buffering and then passes it out for use, so that the gas passed out of the mixed gas pipeline is mixed evenly; during the process, the hydrogen blending uniformity and gas volume of the hydrogen-blended natural gas can be analyzed by a hydrogen analyzer, so that the delivery volume of the natural gas and hydrogen can be adjusted by the PLC control system to achieve the effect of accurately controlling the hydrogen blending ratio; and when the hydrogen blending ratio is small, gas can be supplied through the buffer tank, which can prevent the first flow transmitter, the flow control valve and other flow regulating instruments from oscillating back and forth quickly and causing inaccurate metering, thereby meeting the requirement of accurately controlling the hydrogen blending ratio and also widening the gas flow range passed out of the mixed gas pipeline.

[0091] Finally, it should be noted that the above examples are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the above examples, a person of ordinary skill in the art should understand that he or she can still modify the technical solutions described in the above examples, or make equivalent replacements for some of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the examples of the present application.

Claims

1. A wide flow and accurate natural gas hydrogen blending device, characterized in that: Including natural gas pipelines, hydrogen pipelines, mixed gas pipelines and PLC control systems; The gas mixing pipeline is provided with a mixer and a buffer tank connected in sequence; one end of the natural gas pipeline is connected to the mixer, and the other end is a natural gas inlet end; a first flow transmitter is provided between the natural gas inlet end and the mixer; one end of the hydrogen pipeline is connected to the mixer, and the other end is a hydrogen inlet end; a second flow transmitter and a flow regulating valve connected in sequence are provided between the hydrogen inlet end and the mixer; one end of the gas mixing pipeline is connected to the mixer, and the other end is a mixed gas outlet end connected to the outside through the buffer tank; a hydrogen analyzer is provided between the mixer and the buffer tank; The first flow transmitter, the second flow transmitter, the flow regulating valve, the hydrogen analyzer and the buffer tank are all connected to the PLC control system signal; the PLC control system sets the hydrogen blending ratio, and controls the opening of the first flow transmitter of the natural gas pipeline, the opening of the flow regulating valve of the hydrogen pipeline and the opening and closing of the buffer tank, so as to achieve the purpose of adjusting the hydrogen blending ratio of the gas discharged from the mixing pipeline.

2. The wide flow and accurate natural gas hydrogen blending device according to claim 1 is characterized in that: The natural gas pipeline includes a natural gas large flow branch and a natural gas small flow branch, and the natural gas large flow branch and the natural gas small flow branch are connected in parallel; the intersection of the natural gas pipeline and the left end of the natural gas large flow branch is a first intersection, and the intersection of the natural gas pipeline and the right end of the natural gas large flow branch is a second intersection; the first flow transmitter is arranged on the natural gas large flow branch and the natural gas small flow branch; The hydrogen pipeline includes a large hydrogen flow branch and a small hydrogen flow branch, and the large hydrogen flow branch and the small hydrogen flow branch are connected in parallel; the intersection of the hydrogen pipeline with the left end of the large hydrogen flow branch is the third intersection, and the intersection with the right end of the large hydrogen flow branch is the fourth intersection; the second flow transmitter and the flow regulating valve connected in sequence are both arranged on the large hydrogen flow branch and the small hydrogen flow branch.

3. The wide flow and accurate natural gas hydrogen blending device according to claim 2 is characterized in that: The left end of the natural gas large flow branch and the left end of the natural gas small flow branch intersect at the first intersection, and the right end of the natural gas large flow branch and the right end of the natural gas small flow branch intersect at the second intersection; a first nitrogen purge port, a first pressure gauge, a first temperature gauge, a first ball valve, a first filter, a first stabilizing valve and a first vent valve are sequentially arranged between the natural gas inlet end and the first intersection.

4. The wide flow and accurate natural gas hydrogen blending device according to claim 2 is characterized in that: The left end of the large hydrogen flow branch and the left end of the small hydrogen flow branch intersect at the third intersection, and the right end of the large hydrogen flow branch and the right end of the small hydrogen flow branch are compared to the fourth intersection; a second nitrogen purge port, a second vent valve, a second pressure gauge, a second temperature gauge, a second ball valve, a second filter, and a second stabilization valve are sequentially arranged between the hydrogen inlet end and the third intersection.

5. The wide flow and accurate natural gas hydrogen blending device according to claim 3 is characterized in that: A first cut-off valve is provided between the first flow transmitter of the natural gas large flow branch and the first intersection, and a first ball valve is provided between the first flow transmitter of the natural gas large flow branch and the second intersection; And / or, a first cut-off valve is provided between the first flow transmitter of the natural gas small flow branch and the first intersection, and a first ball valve is provided between the first flow transmitter of the natural gas small flow branch and the second intersection.

6. The wide flow and accurate natural gas hydrogen blending device according to claim 2 is characterized in that: A second ball valve is provided between the second flow transmitter of the large hydrogen flow branch and the third intersection, and a second ball valve is provided between the flow regulating valve of the large hydrogen flow branch and the fourth intersection; And / or, a second ball valve is provided between the second flow transmitter of the small hydrogen flow branch and the third intersection, and a second ball valve is provided between the flow regulating valve of the small hydrogen flow branch and the fourth intersection.

7. The wide flow and accurate natural gas hydrogen blending device according to claim 2 is characterized in that: A third pressure gauge, a third temperature gauge, a third nitrogen purge port, a third ball valve, a flame arrester and a third shut-off valve are sequentially arranged between the mixer and the buffer tank, and the hydrogen analyzer is located between the flame arrester and the third shut-off valve.

8. A method for blending hydrogen into natural gas, characterized in that: The wide flow and accurate natural gas hydrogen blending device according to any one of claims 2 to 7 is used to blend hydrogen into a natural gas pipeline, comprising the following steps: S1: Based on the maximum design demand for hydrogen-blended natural gas Q m The target supply demand of hydrogen-blended natural gas is Q, and the PLC control system sets the hydrogen blending ratio λ; S2: According to the target supply demand Q of hydrogen-blended natural gas and the hydrogen blending ratio λ, the opening of the first flow transmitter of the natural gas pipeline, the opening of the flow regulating valve of the hydrogen pipeline and the opening and closing of the buffer tank are controlled to blend hydrogen into the natural gas; According to the target supply demand Q of hydrogen-blended natural gas and the hydrogen blending ratio λ, controlling the opening of the first flow transmitter of the natural gas pipeline, the opening of the flow regulating valve of the hydrogen pipeline, and the opening and closing of the buffer tank comprises the following steps: When the target supply demand of hydrogen-blended natural gas is 20%Q m To 100% Q m When the flow rate of the natural gas branch is 1, the flow rate transmitter of the natural gas branch with large flow rate and the flow rate regulating valve of the hydrogen branch with large flow rate are opened, and the remaining first flow transmitters and flow rate regulating valves are closed; When the target supply demand of hydrogen-blended natural gas is 6%Q m Up to 30%Q m When the flow rate of the natural gas branch is less than 100%, the flow rate of the hydrogen branch is less than 100%, and the flow rate of the natural gas branch is less than 100%, and the flow rate of the hydrogen ... When the target supply demand of hydrogen-blended natural gas Q is less than 6% Q m When the flow rate is high, close all the first flow transmitters and flow control valves, and only open the buffer tank.

9. The method for blending hydrogen into natural gas according to claim 8, characterized in that: The flow range of the natural gas large flow branch is 0.2(1-λ)Q m to (1-λ)Q m The flow range of the natural gas small flow branch is 0.06(1-λ)Q m To 0.3(1-λ)Q m ; The flow range of the large hydrogen flow branch is 0.2λQ m To λQ m ; The flow range of the hydrogen small flow branch is 0.06λQ m Up to 0.3λQ m .

10. The method for blending hydrogen into natural gas according to claim 8, characterized in that: When only the buffer tank is opened, the pressure after the buffer tank is filled is: Where P2 is the pressure after the buffer tank is filled, Pa; Q m is the maximum design demand for hydrogen-blended natural gas, Nm 3 / s; P0 is the gas supply pressure of the natural gas pipeline, Pa; P m is the atmospheric pressure, Pa; ρ is the density of hydrogen-blended natural gas under standard operating conditions when the blending ratio is λ, kg / m 3 ; A is the cross-sectional area of ​​the buffer tank inlet, m 2 ;ξ is the flow coefficient; The water volume of the buffer tank is: Among them, V 缓冲罐 is the water volume of the buffer tank, m 3 ; n is the inflation time, min; Q m is the maximum design demand for hydrogen-blended natural gas, Nm 3 / s;P m is the atmospheric pressure, Pa; P2 is the pressure after the buffer tank is filled, Pa; P1 is the pressure alarm value of the buffer tank, Pa.

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