Low-energy-consumption liquid flow hydrogen storage system capable of coping with fluctuating hydrogen source

Abstract

The invention belongs to the technical field of hydrogen storage, and particularly relates to a low-energy-consumption liquid flow hydrogen storage system capable of coping with a fluctuating hydrogen source. The system comprises a gas inlet unit, a liquid inlet unit, a high-pressure reactor, a temperature control unit, a gas-liquid separation unit and a heat exchange unit. Through the liquid flow hydrogen storage system, under the conditions of photovoltaic power generation, wind power generation and the like, the flow of output hydrogen is stable (fluctuation is smaller than or equal to 5%), the purity is larger than or equal to 99.999%, and the liquid flow hydrogen storage device can be applied to various scenes with fluctuating gas sources or / and stable hydrogen requirements such as industrial hydrogen and hydrogen energy electric vehicles.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of hydrogen storage, and particularly relates to a low-energy-consumption liquid flow hydrogen storage system capable of dealing with fluctuating hydrogen sources. BACKGROUND

[0002] With the large-scale development of renewable energy (such as wind energy and solar energy), the fluctuation of its output leads to the significant fluctuation of hydrogen produced by the supporting hydrogen production process (mainly water electrolysis). This fluctuating hydrogen is difficult to directly meet the needs of industrial applications for stability, and efficient hydrogen storage technology is urgently needed to achieve energy buffering. The liquid organic hydrogen carrier (LOHC) hydrogen storage system has the advantages of large storage capacity, convenient transportation, high safety, and becomes an important solution to deal with fluctuating hydrogen energy. Patrick Preuster et al. designed a OneReactor reactor, which uses dibenzyltoluene as a hydrogen storage molecule, simulates the fluctuating hydrogen source obtained by photovoltaic power generation and water electrolysis in the hydrogenation process, adjusts the pressure in the LOHC-flow control reactor to keep constant, and outputs stable hydrogen (Journal of Energy Storage, 2023, 72, 108478). Peter Wasserscheid et al. studied the dehydrogenation system of dibenzyltoluene as a hydrogen storage molecule, studied the dynamic change time scale of LOHC flow rate, temperature and pressure on the hydrogen production amount, so as to cope with the fluctuation of power demand (Applied Energy, 2017, 194, 1-8). Although these methods realize the storage and release of hydrogen, they do not pay attention to the difference between the hydrogen output obtained by the hydrogen storage and release process, and mainly study the method of a single hydrogen storage / release process to cope with fluctuation; at the same time, dibenzyltoluene is used as a hydrogen storage molecule, and the dehydrogenation temperature is about 300°C, which is much higher than the hydrogenation temperature of 180°C, and the energy consumption required for the conversion between the hydrogen storage and release processes is high.

[0003] Process industries are usually 7x24 continuous operation, and once the reaction devices (such as synthesis towers and reforming furnaces) are started or stopped, the cost is extremely high and the time is long. Therefore, it is not feasible to directly connect the hydrogen produced by the fluctuating wind power and photovoltaic power to the existing industrial process. It is urgent to develop a low-energy-consumption peak shaving and valley filling system integration technology to establish a large-scale intermediate storage facility between the hydrogen production end and the hydrogen-using factory and to modify the existing industrial reaction devices so that they can accept hydrogen feed within a certain range of fluctuation. SUMMARY

[0004] In view of the above-mentioned disadvantages of the prior art, the purpose of the present application is to provide a liquid flow hydrogen storage system that can cope with fluctuating hydrogen sources. The system of the present application can cope with fluctuating hydrogen sources and achieve stable hydrogen output. At the same time, attention is paid to the stable output of hydrogen during the hydrogen storage / hydrogen release process, the overall energy consumption of the hydrogen storage / hydrogen release process is reduced, and the problem of using fluctuating hydrogen in continuous operation of process industry is solved.

[0005] The technical solution of the present application is: The first aspect of the present application provides a liquid flow hydrogen storage system, which comprises a gas inlet unit, a liquid inlet unit, a high-pressure reactor, a temperature control unit, a gas-liquid separation unit and a heat exchanger; the gas inlet unit comprises a hydrogen tank, a reducing gas tank and two flow control units; the hydrogen tank and the reducing gas tank are respectively communicated with the flow control units, and each flow control unit is respectively communicated with the heat exchanger; the liquid inlet unit comprises a LOHC+ liquid storage tank, a LOHC- liquid storage tank, a liquid flow control unit and a liquid pump; the LOHC+ liquid storage tank and the LOHC- liquid storage tank are respectively communicated with the liquid flow control unit, and the liquid flow control unit and the liquid pump are communicated; the high-pressure reactor comprises a feed inlet, a reaction unit and a discharge outlet communicated in sequence, and is further provided with a pressure gauge and a safety valve; the reaction unit comprises a gas-liquid flow channel and a catalyst arranged in the gas-liquid flow channel, and is connected with the temperature control unit; the gas-liquid separation unit comprises a gas-liquid separation tank, a back pressure valve and a circulating liquid storage tank communicated in sequence; the circulating liquid storage tank is respectively communicated with the LOHC+ liquid storage tank and the LOHC- liquid storage tank; the heat exchanger comprises a feed preheating channel and a discharge cooling channel, and the two flow control units and the liquid pump are respectively communicated with the feed preheating channel and the feed inlet in sequence, and the discharge outlet, the discharge cooling channel and the gas-liquid separation tank are communicated in sequence.

[0006] The second aspect of the present application provides a method for solving the problem of hydrogen fluctuation of the liquid flow hydrogen storage system, which adopts the liquid flow hydrogen storage system as described in the present application, and the method comprises the following steps: 1) In one cycle of the high-pressure reactor, reducing gas is introduced through the gas inlet unit, the temperature control unit is started, the catalyst is reduced in situ, and the activated catalyst is obtained; 2) In the hydrogenation stage, high hydrogen flux is input through the flow control unit, and after pressure rise, the LOHC- liquid in the LOHC- liquid storage tank is input through the liquid flow control unit at a certain flow rate, and heat exchange is carried out through the feed preheating channel and the discharge cooling channel, so that the feed temperature is quickly raised to the reaction temperature; the preheated feed is introduced into the high-pressure reactor to carry out hydrogenation reaction, and LOHC+ liquid is obtained through the gas-liquid separation unit, which is introduced into the LOHC+ liquid storage tank for subsequent circulation, and hydrogen is output; 3) Dehydrogenation stage, input low hydrogen flux using flow control unit, keep temperature unchanged, reduce system pressure, hydrogen as carrier gas carries LOHC+ liquid into high-pressure reactor for dehydrogenation reaction, obtain LOHC- liquid through gas-liquid separation unit, the LOHC- liquid enters the LOHC- liquid storage tank for subsequent circulation, and output hydrogen with purity greater than or equal to 99.999%; Wherein, the order of step 2) and step 3) can be adjusted.

[0007] The above method is real-time monitoring by using flow control unit and temperature control unit, flexible switching of hydrogenation and dehydrogenation stage under different conditions, hydrogenation under high hydrogen flux and dehydrogenation under low hydrogen flux, and adjusting LOHC- liquid flow rate during hydrogenation process and adjusting system pressure during dehydrogenation process, so that the fluctuating hydrogen source is converted into stable hydrogen, meeting the demand of various working conditions.

[0008] The third aspect of the present application provides a method for reducing energy consumption of a liquid flow hydrogen storage system, which adopts the liquid flow hydrogen storage system as described in the present application, and the selected catalyst-organic hydrogen storage liquid system can perform hydrogenation and dehydrogenation reactions under the same temperature, and the hydrogenation and dehydrogenation processes can be converted by changing the pressure, and the reaction enthalpy change is small, so that the liquid flow hydrogen storage process can be realized with low energy consumption.

[0009] By adopting the foregoing technical solutions, the present application has the following beneficial effects: By using the liquid flow hydrogen storage system, the flow control unit and the temperature control unit can be cooperatively adjusted to output hydrogen flow with stability (fluctuation ≤5%) and purity ≥99.999% under the conditions of photovoltaic power generation, wind power generation, etc., which can be applied to various scenes with fluctuating gas source or / and stable hydrogen demand, such as industrial hydrogen and hydrogen energy electric vehicles.

[0010] The present application proposes a catalyst-organic hydrogen storage liquid system suitable for liquid flow hydrogen storage, which can store and release hydrogen with low energy consumption. BRIEF DESCRIPTION OF DRAWINGS

[0011] Figure 1 Fig. 1 is a structural schematic diagram of the liquid flow hydrogen storage system of the present application.

[0012] Figure 2 Fig. 4 is a diagram of a fluctuating hydrogen source, a fluctuating hydrogen source obtained by solar power generation, and a fluctuating hydrogen source obtained by wind power generation.

[0013] 1 Inlet gas unit 11 Hydrogen tank 12 Reducing gas tank 13 Flow control unit 14 Needle valve 2 Liquid inlet unit 21 LOHC+ liquid tank 22 LOHC- liquid tank 23 Liquid flow control unit 24 Liquid pump 3 High pressure reactor 31 Inlet port 32 Outlet port 33 Reaction unit 331 Gas-liquid flow channel 332 Catalyst 34 Pressure gauge 35 Safety valve 4 Temperature control unit 5 Gas-liquid separation unit 51 Gas-liquid separation tank 52 Back pressure valve 53 Circulating liquid tank 6 Heat exchanger 61 Feed preheating channel 62 Discharge cooling channel DETAILED DESCRIPTION

[0014] Hereinafter, an embodiment of a low-energy liquid flow hydrogen storage system capable of dealing with fluctuating hydrogen source is described in detail.

[0015] The specific embodiments of the present application will be further described in conjunction with the accompanying drawings. These embodiments are only used to illustrate the present application, and are not limiting to the present application.

[0016] The orientation or positional relationship indicated by the terms "center", "longitudinal", "transverse", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present application and simplifying the description, and does not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation to the present application. In addition, the terms "first", "second" are only for description purposes, and cannot be understood as indicating or implying relative importance.

[0017] In the description of the present application, it should be noted that, unless otherwise explicitly specified and limited, the terms "mounting", "connection", "connection" should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or integrally connected; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium, or it can be the communication inside two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0018] In addition, in the description of the present application, unless otherwise specified, the meaning of "multiple" is two or more.

[0019] The inventors of the present application have designed a liquid flow hydrogen storage system through a large amount of research, which can maintain stable output hydrogen flow under the conditions of photovoltaic power generation, wind power generation, etc. through the coordinated regulation of the flow control unit and the temperature control unit. At the same time, the most suitable catalyst-organic liquid system is selected to reduce the overall energy consumption. On this basis, the present application is completed.

[0020]

Liquid flow hydrogen storage system

[0021] In the liquid flow hydrogen storage system provided by the present application, a needle valve 14 is arranged on the communication pipeline of the air inlet unit 1 and the heat exchanger 6, and the hydrogenation and dehydrogenation processes are switched by the opening and closing of the needle valve 14.

[0022] The hydrogen gas tank 11 and the reducing gas tank 12 are respectively communicated with the flow control unit 13, and specifically, the hydrogen gas tank 11 is communicated with one of the flow control units 13, and the reducing gas tank 12 is communicated with the other flow control unit 13. The flow control units 13 are used for controlling the flow rate of the inlet gas and providing a fluctuating hydrogen source. In some embodiments, the flow control unit 13 can be a seven-star Huachuang flowmeter and a program flow control instrument of Hande Seiko Technology Co., Ltd.

[0023] The liquid inlet unit 2 includes a LOHC+ liquid storage tank 21, a LOHC- liquid storage tank 22, a liquid flow control unit 23, and a liquid pump 24, which are used for inputting the liquid into the reaction tube of the reaction unit 33 at a controllable flow rate. The liquid flow control unit 23 can be a high-pressure constant-flow pump of Shanghai Sanyi. The LOHC+ liquid storage tank 21 and the LOHC- liquid storage tank 22 are respectively communicated with the liquid flow control unit 23, the liquid flow control unit 23 is communicated with the liquid pump 24, and the liquid pump 24 is communicated with the needle valve 14.

[0024] Further, the LOHC+ liquid storage tank 21 in the liquid inlet unit 2 can include a liquid mainly composed of 1,4-butanediol (BDO), and the LOHC- liquid storage tank 22 can include a liquid mainly composed of 1,4-butyrolactone (GBL). It should be noted that the LOHC+ liquid storage tank 21 obtains 1,4-butanediol (BDO) through a hydrogenation reaction, and the LOHC- liquid storage tank 22 obtains 1,4-butyrolactone (GBL) through a dehydrogenation reaction.

[0025] The high-pressure reactor 3 includes a feed inlet 31, a reaction unit 33, and a discharge outlet 32 communicated in sequence, and is provided with a pressure gauge 34 and a safety valve 35. The high-pressure reactor 3 is sealed by a flange on the outside and is provided with the reaction unit 33 in the inside. The reaction unit 33 includes a gas-liquid flow channel 331 and a catalyst 332 arranged in the gas-liquid flow channel 331. The reaction unit 33 is connected with the temperature control unit 4.

[0026] Further, the reaction unit 33 is a double-layer reaction tube, the outer layer is a stainless steel sleeve, and the inner layer is a quartz tube. The gas flow channel 331 is formed in the quartz tube, and the catalyst 332 is filled in the gas flow channel 331.

[0027] The high-pressure reactor 3 is sealed by a flange on the outside, the feed inlet 31 is communicated with the top of the reaction unit 33, Figure 1The outlet 32 is connected with the gas flow channel 331 of the reaction unit 33 at the top. Figure 1 The heat exchanger 6 includes an inlet preheating channel 61 and an outlet cooling channel 62. The inlet gas unit 1, the inlet liquid unit 2, the inlet preheating channel 61 and the inlet 31 are sequentially connected. Specifically, the inlet preheating channel 61 is connected with the inlet gas unit 1 / inlet liquid unit 2 and the inlet 31 of the high-pressure reactor 3 through a pipeline. More specifically, the hydrogen tank 11 is connected with one of the flow control units 13, and the reducing gas tank 12 is connected with the other flow control unit 13. Then, the two flow control units 13 and the liquid pump 24 are sequentially connected with the inlet preheating channel 61 and the inlet 31, respectively. Further explanation is as follows. Figure 1 The two flow control units 13 and the liquid pump 24 are sequentially connected with the inlet preheating channel 61 and the inlet 31, respectively, through a pipeline. The outlet 32, the outlet cooling channel 62 and the gas-liquid separation unit 5 are sequentially connected. Specifically, the outlet cooling channel 62 is connected with the outlet 32 of the high-pressure reactor 3 and the inlet of the gas-liquid separation unit 5 through a pipeline. More specifically, the outlet 32, the outlet cooling channel 62 and the gas-liquid separation tank 51 are sequentially connected.

[0028] Further, the outlet 32 is connected with the heat exchanger 6 through a pipeline. The heat exchanger 6 is used to transfer the heat of the outlet gas-liquid mixture to the reaction gas and liquid provided by the inlet gas unit 1 and the inlet liquid unit 2, so as to realize preheating.

[0029] In the electro-hydraulic flow hydrogen storage system, the gas-liquid separation unit 5 includes a gas-liquid separation tank 51, a back pressure valve 53 and a circulating liquid storage tank 52. The gas-liquid separation unit 5 is used to separate gas and liquid. The gas is used in a use end (not shown), and the liquid is used for further circulation.

[0030] Further, the gas path and the liquid path obtained after the gas-liquid separation tank 51 in the gas-liquid separation unit 5 is separated are connected with the back pressure valve 53 and the circulating liquid storage tank 52, respectively. The circulating liquid storage tank 52 is connected with the LOHC+ liquid storage tank 21 and the LOHC- liquid storage tank 22 through a three-way valve, respectively. Specifically, the circulating liquid storage tank 52 is connected with the LOHC+ liquid storage tank 21 and the LOHC- liquid storage tank 22 through two paths of the three-way valve, respectively. The connection direction is adjusted according to the reaction stage (hydrogenation / dehydrogenation). The back pressure valve 53 is connected with a hydrogen use end (not shown) after the back pressure valve 53. The hydrogen use end is, for example, a hydrogenation plant, a hydrogenation station and the like.

[0031] The working process of the liquid flow hydrogen storage system is explained by taking 1,4-butanediol (BDO)-1,4-butyrolactone (GBL) system as an example. In one cycle of the high-pressure reactor 3, the needle valve 14 is opened, the reducing gas is introduced by the flow control unit 13, then the temperature control unit 4 is started to reduce the copper catalyst in situ, and the activated supported copper catalyst is obtained. When the hydrogen flux is high, the high hydrogen flux is input by the flow control unit 13, the pressure is first increased, and the liquid flow control unit 23 is used to control the flow rate of the liquid (mainly GBL) in the LOHC-liquid tank 22 to pass through the feed preheating channel 61 of the heat exchanger 6 and exchange heat with the discharge cooling channel 62, so that the temperature of the feed is quickly raised to the reaction temperature. Subsequently, the preheated feed enters the high-pressure reactor 3, and the hydrogenation reaction is carried out by the action of the catalyst 332. Under the action of the supported copper catalyst, GBL generates BDO after passing through the high-pressure reactor 3, and through the gas-liquid separation unit 5, BDO organic liquid with little by-product can be obtained, and the obtained liquid product enters the LOHC+liquid tank 21 for subsequent circulation, and hydrogen gas is output. By adjusting the flow rate of the LOHC-liquid by the liquid flow control unit 23, the pressure in the system can be kept constant, and the stability of the catalytic system can be ensured. When the hydrogen flux is low, the low hydrogen flux is output and kept constant by the flow control unit 13. The temperature is kept constant, and the system pressure is reduced, and the organic liquid is carried into the high-pressure reactor 3 as a carrier gas, and the dehydrogenation reaction is carried out by the action of the catalyst 332. Under the action of the supported copper catalyst, 1,4-butanediol (BDO) generates 1,4-butyrolactone (GBL) after passing through the high-pressure reactor 3, and through the gas-liquid separation unit 5, GBL organic liquid with little by-product can be obtained, and the obtained liquid product enters the LOHC-liquid tank 22 for subsequent circulation, and high-purity hydrogen gas is output. In response to the fluctuation of the output hydrogen gas, the system pressure is adjusted by the gas inlet unit 1 and the back pressure valve 53 to obtain stable hydrogen gas output. Subsequently, every 24 h, the hydrogen storage cycle is carried out by referring to the above hydrogenation / dehydrogenation two stages.

[0032] The liquid flow hydrogen storage system of the present application, for example, uses 1,4-butyrolactone (GBL) as an organic liquid hydrogen storage molecule, which has a low enthalpy change of hydrogenation / dehydrogenation reaction of only 42.2 kJ / mol H2, and a controllable hydrogenation / dehydrogenation temperature difference, with a minimum temperature difference of 0°C, and a low energy consumption required for hydrogen storage and release. Combined with the design of the liquid flow hydrogen storage system, the temperature, pressure and flow rate of the organic liquid can be quickly controlled (the temperature control range is 170-200°C, the pressure control range is 0.1-5 MPa, and the flow rate of the organic liquid is 0.0006-0.006 Nm 3 / h), to cope with the fluctuating hydrogen source and obtain stable hydrogen gas output with a purity of 99.999%.

[0033] Method for solving hydrogen fluctuation problem by liquid flow hydrogen storage system The application provides a method for solving hydrogen fluctuation problem by using a liquid flow hydrogen storage system. 1) In a cycle process of the high-pressure reactor 3, reduction gas is introduced through the gas inlet unit, the temperature control unit 4 is started, the catalyst is reduced in situ, and the activated catalyst is obtained; 2) Hydrogenation stage, high hydrogen flux is input through the flow control unit 13, after pressure increase, the LOHC-liquid in the LOHC-liquid storage tank 22 is exchanged with the feed preheating channel 61 and the discharge cooling channel 62 at a certain flow rate, so that the feed temperature is quickly increased to the reaction temperature; the preheated feed is introduced into the high-pressure reactor 3 to carry out hydrogenation reaction, and LOHC+liquid is obtained through the gas-liquid separation unit 5, the LOHC+liquid is introduced into the LOHC+liquid storage tank 21 for subsequent circulation, and hydrogen is output; 3) Dehydrogenation stage, low hydrogen flux is input through the flow control unit 13, the temperature is kept unchanged, and the system pressure is reduced, hydrogen is used as carrier gas to carry the LOHC+liquid into the high-pressure reactor 3 to carry out dehydrogenation reaction, and LOHC-liquid is obtained through the gas-liquid separation unit 5, the LOHC-liquid is introduced into the LOHC-liquid storage tank 22 for subsequent circulation, and hydrogen with a purity greater than or equal to 99.999% is output.

[0034] Among them, the order of steps 2) and 3) can be adjusted.

[0035] The method for solving hydrogen fluctuation problem by using the liquid flow hydrogen storage system provided by the application is to use the flow control unit and the temperature control unit to monitor in real time, to flexibly switch the hydrogenation and dehydrogenation stages under different conditions, to carry out hydrogenation when the hydrogen flux is high, to carry out dehydrogenation when the hydrogen flux is low, and to adjust the LOHC-liquid flow rate in the hydrogenation process and the system pressure in the dehydrogenation process, so that the fluctuating hydrogen source is changed into stable hydrogen, and the demand of various working conditions is met.

[0036] In the method provided by the application, step 1) is to introduce reduction gas through the gas inlet unit in a cycle process of the high-pressure reactor 3, start the temperature control unit 4, reduce the catalyst in situ, and obtain the activated catalyst.

[0037] In step 1) of the application, in a cycle process of the high-pressure reactor 3, the needle valve 14 is opened, and the reduction gas is introduced by using the flow control unit 13.

[0038] In step 1) of the application, the reduction gas is pure hydrogen or a mixed gas of hydrogen and nitrogen, wherein the volume ratio of hydrogen in the mixed gas is 5% to 20%.

[0039] In step 1) of the method, the catalyst is a supported copper-based catalyst, and the activated catalyst is an activated supported copper-based catalyst.

[0040] In the method, step 2) is a hydrogenation stage, high hydrogen flux is input through the flow control unit 13, and after pressure boosting, the LOHC-liquid in the LOHC-liquid storage tank 22 is exchanged through the feed preheating channel 61 and the discharge cooling channel 62 at a certain flow rate through the liquid flow control unit 23, so that the feed temperature is rapidly increased to the reaction temperature; the preheated feed is obtained and enters the high-pressure reactor 3 for hydrogenation reaction, and the LOHC+liquid is obtained through the gas-liquid separation unit 5, and the LOHC+liquid enters the LOHC+liquid storage tank 21 for subsequent circulation, and hydrogen is output.

[0041] In step 2) of the method, the high hydrogen flux is in the hydrogenation stage.

[0042] In step 2) of the method, the high hydrogen flux is >1.5 Nm 3 / h, for example, ≥3 Nm 3 / h.

[0043] In step 2) of the method, the pressure is first boosted to 0.2-5 MPa, and the LOHC-liquid in the LOHC-liquid storage tank 22 is exchanged at a flow rate of 0.0006-0.006 Nm 3 / h mL / min through the liquid flow control unit 23, and the flow rate can be selected from 0.0006-0.0012 Nm 3 / h, 0.0012-0.006 Nm 3 / h. The feed preheating channel 61 and the discharge cooling channel 62 are exchanged.

[0044] In step 2) of the method, the feed temperature is rapidly increased to the reaction temperature, and the reaction temperature is 170-200°C, which can be selected from 170-180°C, 180-200°C.

[0045] In step 2) of the method, the LOHC-liquid is 1,4-butyrolactone.

[0046] In step 2) of the method, the LOHC+liquid is 1,4-butanediol.

[0047] In step 2) of the method, the byproduct in the LOHC+liquid is only 0-0.5%, which can be selected from 0-0.2%, 0.2-0.5%.

[0048] In step 2) of the method, 1.4-1.6 Nm 3 / h of hydrogen is output, which can be selected from 1.4-1.5 Nm 3 / h, 1.5-1.6 Nm 3 / h.

[0049] In the method provided by the application, step 3) is a dehydrogenation stage, a low hydrogen flux is input by using the flow control unit 13, the temperature is kept unchanged, the system pressure is reduced, hydrogen is carried into the high-pressure reactor 3 as a carrier gas to carry out a dehydrogenation reaction, and LOHC- liquid is obtained through the gas-liquid separation unit 5, and the LOHC- liquid is input into the LOHC- liquid storage tank 22 for subsequent circulation, and hydrogen with a purity greater than or equal to 99.999% is output.

[0050] In step 3) of the application, the low hydrogen flux is in a dehydrogenation stage.

[0051] In step 3) of the application, the low hydrogen flux is less than 1.5 Nm 3 / h, for example, ≤0.4 Nm 3 / h, for example, ≤0.1 Nm 3 / h.

[0052] In step 3) of the application, the system pressure is reduced to 0.1-5 MPa, which can be 0.1-1 MPa or 1-5 MPa.

[0053] In step 3) of the application, the by-product in the LOHC- liquid is 0-0.5%, which can be 0-0.2% or 0.2-0.5%.

[0054] In step 3) of the application, the output flow rate is 1.4-1.6 Nm 3 / h of hydrogen with a purity greater than or equal to 99.999%, which can be 1.4-1.5 Nm 3 / h, 1.5-1.6 Nm 3 / h.

[0055] In summary, in the method provided by the application, the hydrogenation / dehydrogenation reaction process is adjusted in time according to the hydrogen input flow rate, hydrogenation is carried out at a high hydrogen flux, the LOHC- liquid is pumped in, the obtained liquid product is input into the LOHC+ liquid storage tank 21, for example, the high hydrogen flux is greater than 1.5 Nm 3 / h; dehydrogenation is carried out at a low hydrogen flux, the LOHC+ liquid is pumped in, and the obtained liquid product is input into the LOHC- liquid storage tank 22, for example, the low hydrogen flux is less than 1.5 Nm 3 / h. By changing the hydrogenation / dehydrogenation reaction process, hydrogen is stored in the organic liquid at a high hydrogen flux, and hydrogen is released at a low hydrogen flux, so that the front-end fluctuating hydrogen source is converted into a stable hydrogen output.

[0056] In the method provided by the application, the fluctuation includes a simple simulation fluctuating hydrogen source, a fluctuating hydrogen source obtained by solar power generation, and a fluctuating hydrogen source obtained by wind power generation. Figure 2). The simple fluctuating hydrogen source is fixed at a high hydrogen flux for a fixed time and fixed at a low hydrogen flux for a fixed time, wherein the high hydrogen flux time is 12-16 hours and the low hydrogen flux time is 8-12 hours within 24 hours. The fluctuating hydrogen source obtained by solar power generation is greater in hydrogen flux obtained by electrolysis after power generation with stronger sunlight in the environment, and changes with the fluctuation of sunlight, wherein the hydrogen flux is increased at the 4th-6th hour and decreased at the 18th-20th hour within 24 hours. The fluctuating hydrogen source obtained by wind power generation is greater in hydrogen flux obtained by electrolysis after power generation with faster wind speed in the environment, and changes with the fluctuation of wind speed, wherein the hydrogen flux is 0 when there is no wind.

[0057] In the method provided by the application, the flow control unit in the system can monitor the gas concentration and flow rate of the gas outlet section in real time, and feed the detection data to the control program, and the temperature control unit 4 of the reaction tube can monitor the reaction temperature in real time and timely control and adjust in the case of unstable reaction temperature.

[0058] In the method provided by the application, in the case of responding to the fluctuating hydrogen source, the flow rate of the LOHC-liquid is adjusted by using the liquid flow control unit 23, for example, the flow rate is 0.0006-0.006 Nm 3 / h, which is used to ensure that the pressure in the system remains constant and ensures the stability of the catalytic system.

[0059] In the method provided by the application, in the case of responding to the fluctuating hydrogen output, the pressure in the system is adjusted by using the gas inlet unit 1 and the back pressure valve 53, and the pressure can be, for example, 0.1-5 MPa, which is used to obtain stable hydrogen output.

[0060] In the method provided by the application, under the fluctuating hydrogen source, the stable hydrogen flow is output in the hydrogen storage / release process by rapid control of temperature, pressure and organic liquid flow rate (the temperature control range is 170-200°C, the pressure control range is 0.1-5 MPa, and the organic liquid flow rate is 0.0006-0.006 Nm 3 / h), and the coupling process industry is realized.

[0061] Method for reducing energy consumption of liquid flow hydrogen storage system The application provides a method for reducing energy consumption of a liquid flow hydrogen storage system, and the selected catalyst-organic hydrogen storage liquid system can realize hydrogen addition and removal reactions in the same temperature zone, the hydrogen addition and removal process can be changed only by changing the pressure, the reaction enthalpy change is small, and the liquid flow hydrogen storage process can be realized with low energy consumption.

[0062] In the method, the catalyst in the catalyst-organic liquid hydrogen storage system is a supported copper-based catalyst, and the organic liquid hydrogen storage system is 1,4-butanediol and 1,4-butyrolactone.

[0063] In the method, the selection of the organic hydrogen storage liquid mainly refers to the reaction enthalpy change, the impurity content in the dehydrogenated gas and the actual hydrogen storage amount, the reaction enthalpy change is < 50 kJ / mol H2, the impurity content in the gas is < 10 ppm, the hydrogen purity is > 99.999%, and the actual hydrogen storage amount is > 4%.

[0064] In the method, the selection of the catalyst mainly refers to the temperature difference and pressure difference of the hydrogenation and dehydrogenation reactions, so as to ensure that the hydrogenation / dehydrogenation reaction liquid conversion rates are all > 60%, the selectivities are all > 99%, the temperature condition difference used is ≤ 5°C, the pressure condition difference is ≤ 3 MPa, and the dehydrogenation pressure is ≥ 1 MPa.

[0065] In some embodiments, the present application uses 1,4-butyrolactone (GBL) as an organic liquid hydrogen storage molecule, which has a low hydrogenation / dehydrogenation reaction enthalpy change of only 42.2 kJ / mol H2, and a controllable hydrogenation / dehydrogenation temperature difference, with a minimum temperature difference of 0°C, and low energy consumption required for hydrogen storage and release; in combination with the design of a liquid flow hydrogen storage system, rapid control of temperature, pressure and organic liquid flow rate (temperature control range: 170-200°C, pressure control range: 0.1-5 MPa, organic liquid flow rate: 0.0006-0.006 Nm 3 / h) is achieved to cope with fluctuating hydrogen sources and obtain stable hydrogen output with a purity of 99.999%.

[0066] The beneficial effects of the present application are further illustrated by the following examples.

[0067] In order to make the purposes, technical solutions and beneficial technical effects of the present application clearer, the present application is further described in detail in combination with the following examples. However, it should be understood that the examples of the present application are only for the purpose of explaining the present application, and are not intended to limit the present application, and the examples of the present application are not limited to the examples given in the specification. The specific experimental conditions or operation conditions not mentioned in the examples are made according to the conventional conditions or the conditions recommended by the material suppliers.

[0068] Furthermore, it should be understood that the existence of other method steps before or after the combined steps, or the insertion of other method steps between these explicitly mentioned steps, does not preclude the existence of other method steps before or after the combined steps, or the insertion of other method steps between these explicitly mentioned steps, unless otherwise stated. It should also be understood that the combined connection relationship between one or more devices / apparatus mentioned in this invention does not preclude the existence of other devices / apparatus before or after the combined devices / apparatus, or the insertion of other devices / apparatus between these explicitly mentioned devices / apparatus, unless otherwise stated. Moreover, unless otherwise stated, the numbering of each method step is merely a convenient tool for identifying each method step, and not for limiting the order of the method steps or limiting the scope of the invention. Changes or adjustments to their relative relationships, without substantially altering the technical content, should also be considered within the scope of the invention.

[0069] In the following embodiments, unless otherwise specified, all the raw materials of the present invention are commercially available or prepared according to conventional methods in the art.

[0070] Example 1 like Figure 1 The liquid flow hydrogen storage system shown is based on the 1,4-butyrolactone (GBL) dehydrogenation reaction. The active component of the catalyst used is copper, and the fluctuating hydrogen source is a simplified simulated fluctuating hydrogen source. The arrows indicate the direction of gas / liquid flow.

[0071] The high-pressure reactor 3 is a reaction chamber with a cylindrical cavity, the main body of which is made of 316L stainless steel, and a reaction unit 33 is set inside. The reaction unit 33 consists of a double-layered reaction tube, with an outer stainless steel sleeve and an inner quartz tube. The quartz tube is filled with quartz sand, catalyst, and more quartz sand from top to bottom. The thermocouple is located at the center of the catalyst bed. The temperature control unit 4 equipped with the system can automatically adjust the temperature of the reaction tube according to the temperature data fed back by the thermocouple, ensuring precise temperature control inside the reaction tube.

[0072] The heat exchanger 6 is connected to the outlet 32 ​​of the high-pressure reactor 3 using a double-layer corrugated pipe, and the pipe joints are sealed with metal gaskets. The heat exchanger 6 has a dual-channel cross-flow structure, including a feed preheating channel 61 and an outlet cooling channel 62. The outer shell of the heat exchanger 6 is made of high-temperature resistant stainless steel, and the channel baffles are made of high thermal conductivity aluminum alloy and coated with an anti-corrosion coating to enhance durability. The inlet of the feed preheating channel 61 is connected to the outlet of the gas inlet unit 1 / liquid inlet unit 2 via a pipe, and the outlet is connected to the feed inlet 31 of the high-pressure reactor 3; the inlet of the outlet cooling channel 62 is connected to the outlet 32 ​​of the high-pressure reactor 3, and the outlet is connected to the inlet of the gas-liquid separation unit 5.

[0073] The gas inlet unit 1 / liquid inlet unit 2 is connected to the feed inlet 31 of the high-pressure reactor 3 through a corrosion-resistant steel pipe, and a needle valve 14 is arranged in the pipe. The pipe of the gas inlet unit 1 is integrated with a flow meter and a pressure sensor to monitor the hydrogen supply in real time. The gas in the gas inlet unit 1 is preheated by the heat exchanger 6 and then enters the high-pressure reactor 3.

[0074] The gas-liquid separation unit 5 includes a gas-liquid separation tank 51, a back pressure valve 53, and a circulating liquid storage tank 52, which are used to separate gas and liquid. The gas is used in the use end, and the liquid is used for further circulation. The gas and liquid paths obtained after the separation of the gas-liquid separation tank 51 are connected to the back pressure valve 53 and the circulating liquid storage tank 52, respectively; the circulating liquid storage tank 52 is connected to the LOHC+ liquid storage tank 21 and the LOHC- liquid storage tank 22 through two paths of a three-way valve, and the connection direction is adjusted according to the reaction stage (hydrogenation is connected to the LOHC+ liquid storage tank 21, and dehydrogenation is connected to the LOHC- liquid storage tank 22); the back pressure valve 53 is connected to the hydrogen use end.

[0075] In one cycle of the high-pressure reactor 3, first, the needle valve 14 is opened, and the reducing gas is introduced by the flow control unit 13, then the temperature control unit 4 is started to reduce the copper catalyst (see patent ZL 2022 1 0865626.3 for catalyst selection) in situ, while ensuring that the temperature is uniformly distributed in the catalyst to avoid local overheating, and an activated copper-loaded catalyst is obtained.

[0076] In the first 0-14 hours of the reaction, the hydrogenation stage is used, and the high hydrogen flux is input by the flow control unit 13, which is about 3 Nm 3 / h. At 0h, the pressure is first increased to 3.5 MPa, and the liquid (mainly GBL) in the LOHC- liquid storage tank 22 is preheated by the heat exchanger 6 at a flow rate of 0.0012 Nm 3 / h, and the preheated feed is introduced into the high-pressure reactor 3, and the hydrogenation reaction is carried out by the action of the catalyst 332. Under the action of the copper-loaded catalyst, the GBL generates BDO after passing through the high-pressure reactor 3, and after the gas-liquid separation unit 5, a BDO organic liquid with only 0.5% byproduct is obtained, and the obtained liquid product enters the LOHC+ liquid storage tank 21 for subsequent circulation, and about 1.6 Nm 3 / h of hydrogen is output. By adjusting the flow rate of the LOHC- liquid by the liquid flow control unit 23, the pressure in the system can be kept constant, and the stability of the catalyst system can be ensured.

[0077] In the first 0-14 hours of the reaction, the hydrogenation stage is used, and the high hydrogen flux is input by the flow control unit 13, which is about 3 Nm 3The flow rate is kept constant at 1.6 Nm3 / h. The temperature is kept constant (about 180°C), and the system pressure is directly reduced to 1.1 MPa, and the organic liquid is carried into the high-pressure reactor 3 as the carrier gas, and the dehydrogenation reaction is carried out by the action of the catalyst 332. Under the action of the copper-loaded catalyst, 1,4-butanediol (BDO) is converted to 1,4-butyrolactone (GBL) in the high-pressure reactor 3, and the byproduct content of the obtained GBL organic liquid is only 0.5% after gas-liquid separation in the gas-liquid separation unit 5. The obtained liquid product enters the LOHC-liquid tank 22 for subsequent circulation, and the output flow rate is about 1.6 Nm 3 The hydrogen gas has a purity of up to 99.999%. In response to the fluctuation of the output hydrogen gas, the system pressure is adjusted by the gas inlet unit 1 and the back pressure valve 53 to obtain stable hydrogen gas output.

[0078] Every 24 hours, the hydrogen storage cycle is carried out by referring to the above hydrogenation / dehydrogenation two stages, and the output flow rate is always kept at about 1.6 Nm 3 The BDO content in the LOHC+liquid tank 21 is still >50% and the GBL content in the LOHC-liquid tank is still >50% after 365 cycles in a year.

[0079] The flow control unit in the system monitors the gas concentration and flow rate of the gas outlet section in real time, and feeds the detection data to the control program. The temperature control unit of the reaction tube monitors the reaction temperature in real time and adjusts it in time when the reaction temperature is unstable. By hydrogenation at high hydrogen flux and dehydrogenation at low hydrogen flux, and by adjusting the LOHC-liquid flow rate during hydrogenation and the system pressure during dehydrogenation, the fluctuating hydrogen source can be converted into stable hydrogen output, meeting the needs of various working conditions.

[0080] In the embodiments of the present application, there is a difference in the reaction temperature required for the hydrogenation and dehydrogenation of common organic liquids, and the energy consumption caused by the condition change is large. The liquid flow hydrogen storage system provided by the present application selects GBL as the hydrogen storage molecule, the reaction enthalpy change is 42.2 kJ / mol H2, and the actual hydrogen storage amount is 4.4%. The dehydrogenation process does not require additional energy to raise the reaction temperature, and the selected copper catalyst has the same dehydrogenation temperature zone, and the pressure condition difference is 2.4 MPa, which reduces the energy consumption in the hydrogen storage process. At the same time, the system can adjust the LOHC-liquid flow rate, system pressure and other parameters, convert the fluctuating hydrogen source into stable hydrogen output, and realize precise matching of energy consumption and fluctuating hydrogen storage demand.

[0081] Example 2 Example 2 is basically the same as Example 1, except that in Example 2, the fluctuating hydrogen source is the fluctuating hydrogen source obtained by solar power generation.

[0082] According to the hydrogen flux obtained from the solar power plant, the fluctuating hydrogen source is divided into a high hydrogen flux stage and a low hydrogen flux stage.

[0083] The hydrogenation reaction is carried out in the high hydrogen flux stage within 0-14 h after the reaction starts. The flow rate control unit 13 is used to slowly increase the hydrogen flow rate from 1.6 Nm 3 / h to 3 Nm 3 / h within 5 h, maintain for 4 h, and then slowly decrease the hydrogen flow rate from 3 Nm 3 / h to 1.6 Nm 3 / h within 5 h. At 0 h, the pressure is first increased to 3.5 MPa, and the liquid flow rate control unit 23 is used to preheat the liquid (mainly GBL) in the LOHC-liquid tank 22 through the feed preheating channel 61 of the heat exchanger 6 to exchange heat with the discharge cooling channel 62, so that the feed temperature is quickly increased to the reaction temperature (about 180°C). The liquid flow rate is gradually adjusted according to the hydrogen flow rate, and the liquid flow rate is 0.0006-0.0012 Nm 3 / h. The faster the hydrogen flow rate, the faster the liquid flow rate, for example, when the hydrogen flow rate is 1.6 Nm 3 / h, the liquid flow rate is 0.0006 Nm 3 / h; when the hydrogen flow rate is 3 Nm 3 / h, the liquid flow rate is 0.0012 Nm 3 / h. Subsequently, the preheated feed enters the high-pressure reactor 3, and the hydrogenation reaction is carried out through the action of the catalyst 332. Under the action of the copper-loaded catalyst, the GBL generates BDO after passing through the high-pressure reactor 3, and the BDO organic liquid with only 0.5% of by-products can be obtained through the gas-liquid separation unit 5. The obtained liquid product enters the LOHC+liquid tank 21 for subsequent circulation, and about 1.6 Nm 3 / h of hydrogen is output. By adjusting the flow rate of the LOHC-liquid using the liquid flow rate control unit 23, the pressure in the system can be kept constant, and the stability of the catalytic system can be ensured.

[0084] The dehydrogenation reaction is carried out in the low hydrogen flux stage within 14-24 h after the reaction starts. The flow rate control unit 13 is used to quickly decrease the hydrogen flow rate from 1.6 Nm 3 / h to 0.1 Nm 3 / h within 0.5 h, maintain for 8 h, and then quickly increase the hydrogen flow rate from 0.1 Nm 3 / h to 1.6 Nm 3h. Keeping the temperature constant (about 180°C), directly reduce the system pressure to 1 MPa, as the carrier gas carrying organic liquid into the high-pressure reactor 3 inside, through the action of catalyst 332 dehydrogenation. Under the action of copper catalyst loaded, through the high-pressure reactor 3 after 1,4-butanediol (BDO) to 1,4-butyrolactone (GBL), through the gas-liquid separation unit 5, can obtain by-product only 0.5% GBL organic liquid, the resulting liquid product into LOHC-liquid tank for subsequent circulation, output flow rate of about 1.6 Nm 3 / h purity up to 99.999% hydrogen. In response to the fluctuation of hydrogen output, the pressure in the system is adjusted by the gas inlet unit 1 and the back pressure valve 53 to obtain stable hydrogen output.

[0085] Every 24 h, the hydrogen storage cycle is carried out by referring to the above hydrogenation / dehydrogenation two stages, and the output flow rate is always about 1.6 Nm 3 / h purity up to 99.999% hydrogen. After 365 cycles in a year, the BDO content in the LOHC+ liquid tank 21 is still >50%, and the GBL content in the LOHC- liquid tank 22 is still >50%.

[0086] The flow control unit in the system monitors the gas concentration and flow rate of the gas outlet section in real time, and feeds the detection data to the control program. The temperature control unit of the reaction tube monitors the reaction temperature in real time and adjusts it in time when the reaction temperature is unstable. By hydrogenation at high hydrogen flux and dehydrogenation at low hydrogen flux, and adjusting the LOHC-liquid flow rate during hydrogenation and the system pressure during dehydrogenation, the fluctuating hydrogen source can be converted into stable hydrogen output, meeting the needs of various working conditions.

[0087] In the embodiments of the present application, there is a difference in the reaction temperature required for the hydrogenation and dehydrogenation of common organic liquids, and the energy consumption caused by the condition change is large. The liquid flow hydrogen storage system provided by the present application selects GBL as the hydrogen storage molecule, the reaction enthalpy change is 42.2 kJ / mol H2, and the actual hydrogen storage capacity is 4.4%. The dehydrogenation process does not require additional energy to raise the reaction temperature, and the selected copper catalyst has the same dehydrogenation temperature zone, and the pressure difference is 2.5 MPa, reducing the energy consumption in the hydrogen storage process. At the same time, the system can adjust the LOHC-liquid flow rate, system pressure and other parameters, convert the fluctuating hydrogen source into stable hydrogen output, and realize precise matching of energy consumption and fluctuating hydrogen storage demand.

[0088] Example 3 Example 3 is basically the same as Example 1, except that in Example 3, the fluctuating hydrogen source is the fluctuating hydrogen source obtained by wind power generation.

[0089] According to the hydrogen flux obtained by wind power generation, the fluctuating hydrogen source is divided into high hydrogen flux and low hydrogen flux stages, and the hydrogen flux range is 0~3 Nm 3 / h.

[0090] The high hydrogen flux (initially 2 Nm 3 / h, and then fluctuates between 1.6~3 Nm 3 / h) stage carries out hydrogenation reaction. First, the pressure is increased to 4 MPa, and the liquid (mainly GBL) in the LOHC-liquid tank 22 is preheated by the liquid flow control unit 23 at a rate of 0.0009 Nm 3 / h via the feed preheating channel 61 of the heat exchanger 6, and exchanges heat with the discharge cooling channel 62, so that the feed temperature is quickly raised to the reaction temperature (about 180°C). According to the hydrogen flow, the liquid flow is gradually adjusted, and the liquid flow is 0.0006~0.0012 Nm 3 / h, the faster the hydrogen flow, the faster the liquid flow, for example, when the hydrogen flow is 1.6 Nm 3 / h, the liquid flow is 0.0006 Nm 3 / h; when the hydrogen flow is 3 Nm 3 / h, the liquid flow is 0.0012 Nm 3 / h. Subsequently, the preheated feed enters the high-pressure reactor 3, and hydrogenation reaction is carried out by the action of the catalyst 332. Under the action of the copper-loaded catalyst, GBL generates BDO after passing through the high-pressure reactor 3, and after passing through the gas-liquid separation unit 5, BDO organic liquid with only 0.5% byproduct can be obtained, and the obtained liquid product enters the LOHC+liquid tank 21 for subsequent circulation, and about 1.6 Nm 3 / h of hydrogen is output. By adjusting the flow rate of the LOHC-liquid using the liquid flow control unit 23, the pressure in the system can be kept constant, and the stability of the catalytic system can be ensured.

[0091] The low hydrogen flux (initially 0.4 Nm 3 / h, and then fluctuates between 0.1~1.6 Nm 3 / h) stage carries out dehydrogenation reaction. The temperature is kept constant (about 180°C), and the system pressure is directly reduced to 1 MPa, and the organic liquid is carried into the high-pressure reactor 3 as a carrier gas, and dehydrogenation reaction is carried out by the action of the catalyst 332. Under the action of the copper-loaded catalyst, 1,4-butanediol (BDO) generates 1,4-butyrolactone (GBL) after passing through the high-pressure reactor 3, and after passing through the gas-liquid separation unit 5, GBL organic liquid with only 0.5% byproduct can be obtained, and the obtained liquid product enters the LOHC-liquid tank 22 for subsequent circulation, and the output flow rate is about 1.6 Nm 3hydrogen gas with purity up to 99.999%. In the case of responding to fluctuation of hydrogen gas output, the pressure in the system is adjusted by the gas inlet unit 1 and the back pressure valve 53 to obtain stable hydrogen gas output.

[0092] Referring to the above hydrogenation / dehydrogenation two stages for hydrogen storage cycle, the output flow rate is always maintained at about 1.6 Nm 3 / h. After one year, the BDO content in the LOHC+ liquid storage tank 21 is still >50%, and the GBL content in the LOHC- liquid storage tank 22 is still >50%.

[0093] The flow control unit in the system monitors the gas concentration and flow rate of the gas outlet section in real time, and feeds the detection data to the control program. The temperature control unit of the reaction tube monitors the reaction temperature in real time, and adjusts in time in the case of unstable reaction temperature. By hydrogenation at high hydrogen flux and dehydrogenation at low hydrogen flux, and adjusting the LOHC- liquid flow rate during hydrogenation and the system pressure during dehydrogenation, the fluctuating hydrogen source can be converted into stable hydrogen output, meeting the needs of various working conditions.

[0094] In the embodiments of the present application, there is a difference in the reaction temperature required for hydrogenation and dehydrogenation of common organic liquids, and the energy consumption brought by condition conversion is large. The liquid flow hydrogen storage system provided by the present application selects GBL as the hydrogen storage molecule, the reaction enthalpy change is 42.2 kJ / mol H2, and the actual hydrogen storage capacity is 4.4%. The dehydrogenation process does not require additional energy to raise the reaction temperature, and the selected copper catalyst has consistent dehydrogenation temperature zone, and the pressure difference is 3 MPa, reducing the energy consumption in the hydrogen storage process. At the same time, the system can adjust the LOHC- liquid flow rate, system pressure and other parameters, convert the fluctuating hydrogen source into stable hydrogen output, and realize precise matching of energy consumption and fluctuating hydrogen storage demand.

[0095] Comparative Example 1 Comparative Example 1 is basically the same as Example 1, except that in Comparative Example 1, a cobalt-based catalyst is selected as the catalyst.

[0096] In one cycle process of the high-pressure reactor 3, first, the needle valve is opened, and the reducing gas is introduced by the flow control unit 13, then the temperature control unit 4 is started, so that the cobalt catalyst is reduced in situ, and at the same time, the temperature is uniformly distributed in the catalyst, avoiding the phenomenon of local overheating, and obtaining the activated cobalt catalyst.

[0097] The hydrogenation stage is in the first 0~14h of the reaction, and the high hydrogen flux is input by the flow control unit 13, which is about 3 Nm 3 / h. At 0h, the pressure is first increased to 4 MPa, and the liquid (mainly GBL) in the LOHC- liquid storage tank 22 is introduced by the liquid flow control unit 23 at a flow rate of 0.0012 Nm 3The feed preheating passage 61 of the heat exchanger 6 exchanges heat with the discharge cooling passage 62, so that the temperature of the feed is rapidly increased to the reaction temperature (about 180°C). Subsequently, the preheated feed enters the high-pressure reactor 3, and is subjected to hydrogenation reaction by the action of the catalyst 332. Under the action of the cobalt-loaded catalyst, GBL is converted into BDO in the high-pressure reactor 3, and the by-product BDO organic liquid with a purity of 90% is obtained through the gas-liquid separation unit 5. The obtained liquid product enters the LOHC+ liquid tank 21 for subsequent circulation, and the output flow rate is about 2.8 Nm 3 / h of hydrogen. By adjusting the flow rate of the LOHC- liquid by using the liquid flow control unit 23, the pressure in the system can be kept constant, and the stability of the catalytic system can be ensured.

[0098] In the dehydrogenation stage within 14-24 hours after the reaction starts, the hydrogen flow rate is reduced to 0.4 Nm 3 / h by using the flow control unit 13 and kept constant. The temperature is kept unchanged (about 180°C), and the system pressure is directly reduced to 1 MPa. The organic liquid is carried into the high-pressure reactor 3 as a carrier gas, and is subjected to dehydrogenation reaction by the action of the catalyst 332. Under the action of the cobalt-loaded catalyst, 1,4-butanediol (BDO) is converted into 1,4-butyrolactone (GBL) in the high-pressure reactor 3, and the by-product GBL organic liquid with a purity of 90% is obtained through the gas-liquid separation unit 5. The obtained liquid product enters the LOHC- liquid tank 22 for subsequent circulation, and the output flow rate is about 0.45 Nm 3 / h of hydrogen with a purity of 99.999%.

[0099] The liquid product obtained in the comparative example has too little GBL-BDO content, the by-product reaches 90%, and the actual hydrogen storage amount is only 0.4%. The hydrogenation-dehydrogenation cycle cannot be carried out, and the function of converting the fluctuating hydrogen source into stable hydrogen cannot be realized.

[0100] Comparative Example 2 Comparative Example 2 is basically the same as Example 1, except that the organic liquid system in Comparative Example 2 is formate-carbonate, and the catalyst is a Pd-based catalyst.

[0101] In one cycle of the high-pressure reactor 3, the needle valve is first opened, and the reducing gas is introduced by using the flow control unit 13. Then, the temperature control unit 4 is started, so that the catalyst is in-situ reduced, and the temperature is uniformly distributed in the catalyst, so as to avoid local overheating. The activated catalyst is obtained.

[0102] In the hydrogenation stage within 0-14 hours after the reaction starts, the hydrogen flow rate is about 3 Nm 3 / h. At 0 h, the pressure is first increased to 4 MPa, and the liquid (mainly carbonate solution) in the LOHC-liquid tank 22 is preheated to the reaction temperature (about 100°C) by heat exchange with the outlet cooling channel 62 of the heat exchanger 6 at a flow rate of 0.006 Nm 3 / h. The preheated feedstock enters the high-pressure reactor 3, and the hydrogenation reaction is carried out by the action of the catalyst 332. Under the action of the supported catalyst, the carbonate is converted into formate after passing through the high-pressure reactor 3. The liquid product with only 0.5% byproduct is obtained by the gas-liquid separation unit 5, and the obtained liquid product enters the LOHC+liquid tank 21 for subsequent circulation, with an output flow rate of about 1.6 Nm 3 / h of hydrogen. By adjusting the flow rate of the LOHC-liquid using the liquid flow control unit 23, the pressure in the system can be kept constant, ensuring the stability of the catalytic system.

[0103] In the dehydrogenation stage within 14-24 h after the start of the reaction, the flow rate of hydrogen is reduced to 0.4 Nm 3 / h by the flow control unit 13 and kept constant. The temperature is increased (about 150°C), and the system pressure is directly reduced to 0.1 MPa. The organic liquid is carried into the high-pressure reactor 3 as a carrier gas, and the dehydrogenation reaction is carried out by the action of the catalyst 332. Under the action of the supported catalyst, the formate is converted into carbonate after passing through the high-pressure reactor 3. The liquid product with only 0.5% byproduct is obtained by the gas-liquid separation unit 5, and the obtained liquid product enters the LOHC-liquid tank 22 for subsequent circulation, with an output flow rate of about 1.6 Nm 3 / h of hydrogen with a purity of only 25%. In response to the fluctuation of the output hydrogen, the pressure in the system is adjusted by the gas inlet unit 1 and the back pressure valve 53 to obtain stable hydrogen output.

[0104] Every 24 h, the hydrogen storage cycle is carried out by referring to the above-mentioned hydrogenation / dehydrogenation two stages, and the output flow rate of hydrogen is always about 1.6 Nm 3 / h. After 365 cycles in a year, the formate content in the LOHC+liquid tank 21 is still >50%, and the carbonate content in the LOHC-liquid tank 22 is still >50%.

[0105] The hydrogen content in the gas product obtained in the comparative example is only 25%, and a separation process needs to be added for subsequent use. The temperature difference of hydrogenation / dehydrogenation is 50°C, the pressure difference is 3.9 MPa, and the energy consumption is high. The dehydrogenation pressure is 0.1 MPa, and the energy consumption required for further compression is high. At the same time, the catalyst is a noble metal catalyst, which is expensive, so the system cannot complete the function of converting fluctuating hydrogen sources into stable pure hydrogen with low energy consumption.

[0106] Comparative Example 3 Comparative Example 3 is substantially the same as Example 1, except that in Comparative Example 3, the organic liquid system is selected to be dibenzyltoluene-perhydrodibenzyltoluene, and the catalyst is selected to be a Pt-based catalyst.

[0107] In one cycle of the high-pressure reactor 3, first, the needle valve is opened, and the reducing gas is introduced by the flow control unit 13, then the temperature control unit 4 is started to reduce the catalyst in situ, while ensuring that the temperature is uniformly distributed in the catalyst, avoiding the phenomenon of local overheating, and obtaining the activated supported catalyst.

[0108] In the first 0-14 hours of the reaction, it is in the hydrogenation stage, and a high hydrogen flux is input by the flow control unit 13, about 3 Nm 3 / h. At 0h, the pressure is first increased to 4 MPa, and the liquid (mainly dibenzyltoluene) in the LOHC-liquid tank 22 is preheated by the liquid flow control unit 23 at a flow rate of 0.0006 Nm 3 / h, and the preheated feedstock is introduced into the high-pressure reactor 3, and the hydrogenation reaction is carried out by the action of the catalyst 332. Under the action of the supported catalyst, the dibenzyltoluene is converted to perhydrodibenzyltoluene after passing through the high-pressure reactor 3, and the byproduct is only 0.5% liquid after gas-liquid separation by the gas-liquid separation unit 5, and the obtained liquid product is introduced into the LOHC+liquid tank 21 for subsequent circulation, and about 1.6 Nm 3 / h of hydrogen is output. By adjusting the flow rate of the LOHC-liquid by the liquid flow control unit 23, the pressure in the system can be kept constant, ensuring the stability of the catalytic system.

[0109] In the 14-24 hours after the start of the reaction, it is in the dehydrogenation stage, and the hydrogen flow is reduced to 0.4 Nm 3 / h by the flow control unit 13 and kept constant. The temperature is increased (about 290°C), and the system pressure is directly reduced to 0.1 MPa, and the organic liquid is carried into the high-pressure reactor 3 as a carrier gas, and the dehydrogenation reaction is carried out by the action of the catalyst 332. Under the action of the supported catalyst, the perhydrodibenzyltoluene is converted to dibenzyltoluene after passing through the high-pressure reactor 3, and the byproduct is only 0.5% liquid after gas-liquid separation by the gas-liquid separation unit 5, and the obtained liquid product is introduced into the LOHC-liquid tank 22 for subsequent circulation, and about 1.6 Nm 3 / h of hydrogen with a purity of 99.99% is output. In response to the fluctuation of the output hydrogen, the pressure in the system is adjusted by the gas inlet unit 1 and the back pressure valve 53 to obtain stable hydrogen output.

[0110] The subsequent every 24 h, i.e. the hydrogen storage cycle is carried out by referring to the above two stages of hydrogenation / dehydrogenation, and the output flow rate is always maintained at about 1.6 Nm 3 After 365 cycles in a year, the content of the full hydrogen dibenzyl toluene in the LOHC+ liquid storage tank 21 is still >50%, and the content of the carbonate dibenzyl toluene in the LOHC- liquid storage tank 22 is still >50%.

[0111] The organic liquid reaction enthalpy change in the comparative example is 65.4 kJ / mol H2, the dehydrogenation temperature is high (>200°C), the dehydrogenation temperature difference is 60°C, the pressure difference is 3.9 MPa, and the energy consumption is high; the dehydrogenation pressure is 0.1 MPa, and the energy consumption required for subsequent further compression is high; at the same time, the catalyst is a noble metal catalyst, which is expensive, so it cannot complete the function of converting fluctuating hydrogen source into stable pure hydrogen with low energy consumption.

[0112] In summary, the present application effectively overcomes the shortcomings of the prior art and has high industrial utilization value.

[0113] The above is only a preferred embodiment of the present application, and is not a limitation on the form and substance of the present application. It should be noted that for ordinary skilled persons in the art, some improvements and supplements can be made without departing from the method of the present application, and these improvements and supplements should also be considered as the protection scope of the present application. For those skilled in the art, some minor changes, modifications and equivalent changes made by utilizing the disclosed technical content without departing from the spirit and scope of the present application are equivalent embodiments of the present application; at the same time, any equivalent changes, modifications and evolution of the above-mentioned embodiments according to the essential technology of the present application are still within the scope of the technical solutions of the present application.

Claims

1. A liquid flow hydrogen storage system, characterized in that, The system includes an air intake unit (1), a liquid intake unit (2), a high-pressure reactor (3), a temperature control unit (4), a gas-liquid separation unit (5), and a heat exchange unit (6). The air intake unit (1) includes a hydrogen tank (11), a reducing gas tank (12), and two flow control units (13); the hydrogen tank (11) and the reducing gas tank (12) are respectively connected to the flow control units (13), and the flow control units (13) are respectively connected to the heat exchange unit (6); The liquid inlet unit (2) includes a LOHC+ liquid storage tank (21), a LOHC- liquid storage tank (22), a liquid flow control unit (23), and a liquid pump (24); the LOHC+ liquid storage tank (21) and the LOHC- liquid storage tank (22) are respectively connected to the liquid flow control unit (23), and the liquid flow control unit (23) and the liquid pump (24) are connected. The high-pressure reactor (3) includes a feed inlet (31), a reaction unit (33) and a discharge outlet (32) connected in sequence. The high-pressure reactor (3) is also equipped with a pressure gauge (34) and a safety valve (35). The reaction unit (33) includes a gas-liquid flow channel (331) and a catalyst (332) disposed in the gas-liquid flow channel (331). The reaction unit (33) is connected to the temperature control unit (4). The gas-liquid separation unit (5) includes a gas-liquid separation tank (51), a back pressure valve (53), and a circulating liquid storage tank (52) connected in sequence; the circulating liquid storage tank (52) is connected to the LOHC+ liquid storage tank (21) and the LOHC- liquid storage tank (22) respectively; The heat exchanger (6) includes a feed preheating channel (61) and a discharge cooling channel (62). The two flow control units (13) and the liquid pump (24) are connected in sequence to the feed preheating channel (61) and the feed inlet (31), respectively. The discharge outlet (32), the discharge cooling channel (62), and the gas-liquid separator (51) are connected in sequence.

2. The liquid flow hydrogen storage system as described in claim 1, characterized in that, A needle valve (14) is provided on the connecting pipe between the air intake unit (1) and the heat exchanger (6).

3. The liquid flow hydrogen storage system as described in claim 1, characterized in that, It also includes one or more of the following conditions: A1) The high-pressure reactor (3) is sealed with a flange on the outside. The feed port (31) is connected to the top of the reaction unit (33). The discharge port (32) is connected to the bottom of the reaction unit (33). The reaction unit (33) is connected to the temperature control unit (4). The catalyst (332) is a supported copper-based catalyst. A2) The LOHC+ liquid storage tank (21) in the liquid inlet unit (2) contains a liquid mainly composed of 1,4-butanediol, and the LOHC- liquid storage tank (22) contains a liquid mainly composed of 1,4-butyrolactone. A3) The circulating liquid storage tank (52) is connected to the LOHC+ liquid storage tank (21) and the LOHC- liquid storage tank (22) respectively through a three-way valve, and the back pressure valve (53) is connected to the hydrogen usage end.

4. A method for solving the problem of hydrogen fluctuation in a liquid flow hydrogen storage system, characterized in that, The method using the liquid hydrogen storage system as described in any one of claims 1 to 3 includes the following steps: 1) During one cycle of the high-pressure reactor (3), reducing gas is introduced through the gas inlet unit and the temperature control unit (4) is activated to reduce the catalyst in situ and obtain the activated catalyst; 2) In the hydrogenation stage, a high hydrogen flow rate is input through the flow control unit (13). After pressurization, the LOHC-liquid in the LOHC-liquid storage tank (22) is heat-exchanged at a certain flow rate through the feed preheating channel (61) and the discharge cooling channel (62) through the liquid flow control unit (23), so that the feed temperature is rapidly raised to the reaction temperature. The preheated feed enters the high-pressure reactor (3) for hydrogenation reaction. After passing through the gas-liquid separation unit (5), LOHC+ liquid is obtained. The LOHC+ liquid enters the LOHC+ liquid storage tank (21) for subsequent circulation and outputs hydrogen. 3) In the dehydrogenation stage, a low hydrogen flow rate is input using the flow control unit (13) to keep the temperature constant and reduce the system pressure. Hydrogen is used as a carrier gas to carry LOHC+ liquid into the high-pressure reactor (3) for dehydrogenation reaction. After passing through the gas-liquid separation unit (5), LOHC- liquid is obtained. The LOHC- liquid enters the LOHC-liquid storage tank (22) for subsequent circulation and outputs hydrogen with a purity greater than or equal to 99.999%. The order of steps 2) and 3) is adjustable.

5. The method for solving the hydrogen fluctuation problem in the liquid flow hydrogen storage system as described in claim 4, characterized in that, It also includes one or more of the following conditions; In step 1) of B1), during one cycle of the high-pressure reactor (3), the needle valve (14) is opened and reducing gas is introduced using the flow control unit (13); B2) In step 1), the reducing gas is pure hydrogen or a mixture of hydrogen and nitrogen, wherein the volume percentage of hydrogen in the mixture is 5% to 20%. In step 1) of B3), the catalyst is a supported copper-based catalyst.

6. The method for solving the hydrogen fluctuation problem in the liquid flow hydrogen storage system as described in claim 4, characterized in that, It also includes one or more of the following conditions: In step 2) of C1), the hydrogen addition stage is underway when the hydrogen flow rate is high. In step 2) of C2), the high hydrogen flux is >1.5 Nm. 3 / h; In step 2) of C3), the pressure is first increased to 0.2~5MPa, and the LOHC liquid in the LOHC liquid storage tank (22) is circulated at a flow rate of 0.0006~0.006 Nm using the liquid flow control unit (23). 3 The flow rate is / h, and heat exchange occurs between the feed preheating channel (61) and the discharge cooling channel (62); In step 2) of C4), the feed temperature is rapidly increased to the reaction temperature, which is 170~200°C. In step 2) of C5, the LOHC-liquid is 1,4-butyrolactone; In step 2) of C6), the LOHC+ liquid is 1,4-butanediol; In step 2) of C7), the byproducts in the LOHC+ liquid are only 0~0.5%; In step 2) of C8, the output is 1.4~1.6 Nm. 3 Stable hydrogen per hour.

7. The method for solving the hydrogen fluctuation problem in the liquid flow hydrogen storage system as described in claim 4, characterized in that, It also includes one or more of the following conditions: In step 3) of D1), the dehydrogenation stage occurs when the hydrogen flux is low. In step 3) of D2, the low hydrogen flux is <1.5 Nm. 3 / h; In step 3), the system pressure is reduced by 0.1~5 MPa; In step 3) of D4, the byproduct in the LOHC- liquid is 0~0.5%; In step 3) of D5, the output flow rate is 1.4~1.6 Nm. 3 / h Hydrogen gas with a purity of ≥99.999%.

8. The method for solving the hydrogen fluctuation problem in the liquid flow hydrogen storage system as described in claim 4, characterized in that, Includes one or more of the following conditions: E1) A simplified simulation of a fluctuating hydrogen source, with a fixed high hydrogen flux for a fixed time and a fixed low hydrogen flux for a fixed time. E2) Fluctuating hydrogen source obtained from solar power generation. The stronger the sunlight in the environment, the greater the hydrogen flux obtained by electrolysis after power generation, which fluctuates with the sunlight. E3) Fluctuating hydrogen source from wind power generation. The faster the wind speed in the environment, the greater the hydrogen flux obtained by electrolysis after power generation. When there is no wind, the hydrogen flux is 0, and it fluctuates with the wind speed.

9. A method for reducing energy consumption in a liquid hydrogen storage system, characterized in that, The method of using the liquid flow hydrogen storage system as described in any one of claims 1 to 3 includes the addition and dehydrogenation reaction of the selected catalyst-organic liquid hydrogen storage system in the same temperature range. The addition and dehydrogenation process can be switched by changing the pressure and the enthalpy change of the reaction is small, which can realize a low-energy liquid flow hydrogen storage process.

10. The method for reducing energy consumption in a liquid hydrogen storage system as described in claim 9, characterized in that, It also includes any one or more of the following conditions: In the catalyst-organic liquid hydrogen storage system described in F1), the catalyst is a supported copper-based catalyst, and the organic liquid hydrogen storage system is 1,4-butanediol and 1,4-butyrolactone; F2) Enthalpy change of reaction <50kJ / mol H2, impurity content in gas <10ppm, hydrogen purity >99.999%, actual hydrogen storage capacity >4%; F3) When the liquid conversion rate of hydrogenation / dehydrogenation reaction is both >60% and the selectivity is both >99%, the temperature difference is ≤5°C, the pressure difference is ≤3MPa, and the dehydrogenation pressure is ≥1MPa.

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