Production device and production method for large-scale preparation of magnesium hydride

Abstract

The invention discloses a production device and a production method for large-scale preparation of magnesium hydride. The production device comprises a reaction separation bin, a crushing bin, a raw material bin, a heater, a hydrogen compressor, a cooler, a heat exchanger, a steam pocket, a filter, a product bin and a product separator. The fluidization operation using the reaction gas as the carrier gas not only solves the problem of material transfer, but also enables heat transfer and mass transfer between gas and solid to be more sufficient and efficient, and solves the problems of non-uniform material reaction, poor solid heat transfer performance, large temperature gradient and local temperature runaway caused by too fast reaction. And high-speed flowing can increase collision friction among material particles, and a high-speed mill is matched for use, so that magnesium hydride layers on the surfaces of magnesium powder particles are broken in time, hydrogen is easier to contact with the surfaces of fresh magnesium powder particles, and the reaction rate is increased. The steam pocket can effectively recover reaction heat, and energy consumption of the device is reduced.

Description

Technical Field

[0001] The present application relates to a production device and a production method for large-scale preparation of magnesium hydride, belonging to the technical field of chemical industry. Background Art

[0002] my country is currently facing two major challenges: energy security and "carbon emissions". It is necessary to adjust the current energy structure that is overly dependent on fossil energy and develop in the direction of low-carbon and clean energy.

[0003] Incorporating hydrogen energy into my country's entire energy system will help improve my country's high-carbon energy structure and ensure energy security. Its applications include not only hydrogen-powered vehicles, but also energy storage, power generation and other industrial applications.

[0004] In the entire hydrogen energy supply chain, high-density safe storage and transportation of hydrogen is the main bottleneck. The use of solid-state hydrogen storage can not only greatly increase the volumetric hydrogen storage density, but also improve the safety of hydrogen storage and transportation, providing an important solution for the development of the hydrogen energy industry.

[0005] Magnesium hydride (MgH2), also known as magnesium dihydride, is an inorganic compound with an appearance of off-white crystalline powder and a density of 1.45g / cm 3 It has a high volumetric hydrogen storage density (110g / L) and mass hydrogen storage density (7.6%). The released hydrogen is of high purity and has high stability at room temperature and pressure. It is an important solid hydrogen storage material.

[0006] Common preparation methods include using alkyl magnesium to thermally decompose magnesium hydride, magnesium powder catalysis under normal pressure, and magnesium powder heating and pressurization to prepare magnesium hydride. The existing preparation technology has the disadvantages of long hydrogenation time, large size of magnesium hydride, uneven particles, inability to mass-produce continuous production, and high price, which limits the large-scale promotion and use of magnesium hydride as a hydrogen storage material.

[0007] After information retrieval, there are currently public technologies, 1) Publication number: CN109795987A, which discloses an integrated device for preparing magnesium hydride powder and a method for preparing magnesium hydride powder. The device of the invention includes a heating chamber for heating magnesium-based metal materials to produce metal droplets; a powder making chamber, the powder making chamber includes an atomizing device, the atomizing device is used to atomize the metal droplets, and then cool to form metal powder; a collecting chamber for collecting and screening metal powder; and a reaction chamber for subjecting the metal powder to a hydrogenation reaction to form magnesium hydride powder. The device of the invention is an integrated structure with a simple structure and convenient operation; the entire process of preparing magnesium hydride powder can be completed in one device and can be automatically controlled. The method of the invention is simple and easy to implement, and the product obtained has a moderate size, uniform particles, and excellent performance. The integrated structure has no crushing facilities, and the magnesium hydride shell formed on the surface of the magnesium particles cannot be peeled off in time, which affects the contact between hydrogen and the surface of fresh magnesium particles, and the hydrogenation efficiency is low for a long time; there are no cooling facilities, and the heat generated by the hydrogenation of magnesium powder cannot be transferred in time, and local high-temperature points will be generated when the reaction intensity is high; heating relies on external heat sources, the material is heated unevenly, and the temperature gradient is large; continuous production is not possible; the preparation scale is limited, and large-scale production is difficult; raw material input and product transportation are inconvenient, and it is difficult to achieve automated operation, etc.

[0008] 2) Publication No.: CN114436213A, discloses a magnesium hydride preparation device and a magnesium hydride preparation method, wherein the magnesium hydride preparation device comprises: a transition bin, the transition bin comprises a feeding port; a heating chamber, the heating chamber is connected to the transition bin through a first valve; a heater, the upper end of the heater is open and can be moved between the transition bin and the heating chamber through the first valve, and the heater is used to heat the magnesium raw material placed therein in the heating chamber; a collecting chamber, the collecting chamber is connected to the heating chamber through a conduit to collect magnesium powder; and a reaction chamber, the reaction chamber is connected to the collecting chamber through a second valve to receive magnesium powder, and the reaction chamber is connected to an external hydrogen source to receive hydrogen. The magnesium hydride preparation device proposed in the invention combines magnesium powder preparation and hydrogenation reaction into one device, and the magnesium hydride preparation method using the magnesium hydride preparation device has simple steps, and the particle size of the prepared magnesium hydride particles can be controlled within the range of 1μm-60μm by controlling conditions such as temperature and pressure. Although the integrated device for large-scale preparation of magnesium hydride powder solves some of the problems of scale, it still cannot solve the problem of continuous automated production. The raw materials and products cannot be completely fluidized, pneumatic conveying is difficult, the feeding and discharging cannot be continuous, the pneumatic crushing strength is low, and the raw materials cannot be crushed efficiently.

[0009] The existing magnesium hydride preparation technology is difficult to achieve scale, continuity and automation, and the main problems are as follows: 1) The preparation process is a gas-solid reaction. In the existing static high-temperature and high-pressure hydrogenation process, it is difficult for hydrogen to transfer to the surface of fresh magnesium, which affects production efficiency and heat transfer. The uneven heat transfer during the hydrogenation startup heating process will cause local high temperatures. The heat generated during the hydrogenation process cannot be transferred in time, which will also cause local high temperatures and even temperature spikes. High temperatures will cause the magnesium powder to melt, weld, and enlarge the particles, and hydrogenation will be incomplete; 2) There is no effective method for breaking the magnesium hydride shell on the surface of magnesium particles, and the hydrogenation efficiency is low; 3) The feeding, discharging, and internal transportation and transfer in the preparation process cannot be automated and continuous, and can only be batch produced; 4) The large amount of heat energy generated during the hydrogenation of magnesium powder cannot be recovered, resulting in energy waste. Summary of the invention

[0010] In view of the technical problem that the existing magnesium hydride preparation technology is difficult to achieve scale, continuity and automation, the present application provides a magnesium hydride preparation device and preparation method that can simultaneously meet the requirements of scale, fluidization, continuity, automation, efficient hydrogenation, precise temperature control, and energy recovery.

[0011] According to one aspect of the present application, a production device for large-scale preparation of magnesium hydride is provided, the production device comprising: a reaction separation bin, a crushing bin, a raw material bin, a heater, a hydrogen compressor, a cooler, a heat exchanger, a steam drum, a filter, a product bin, a product separator, a heat exchanger cross-line valve, a cooler cross-line valve, a heater cross-line valve, and a main valve;

[0012] The upper end of the reaction separation chamber is connected to the filter, the heat exchanger, the cooler, the hydrogen compressor, the heater and the crushing chamber in sequence through a circulating hydrogen pipeline;

[0013] The raw material bin is arranged between the crushing bin and the heater;

[0014] A product separator is provided on the side where the circulating hydrogen pipeline enters the reaction separation chamber, and the product separator is connected to the product chamber;

[0015] The heat exchanger is connected to the steam drum and the heat exchanger cross-line valve;

[0016] The cooler is connected to the cooler cross-line valve, and the heater is connected to the heater cross-line valve;

[0017] A product separation gas return valve is provided between the product separator and the reaction separation chamber;

[0018] The main valve is arranged on the pipeline where the circulating hydrogen pipeline enters the reaction separation chamber;

[0019] A reaction separation bin bottom valve is provided at the bottom of the reaction separation bin, a crushing bin bottom valve is provided at the bottom of the crushing bin, and a raw material bin bottom valve is provided at the bottom of the raw material bin.

[0020] Optionally, a multi-stage cyclone separator and a reaction separation chamber gas outlet line are provided in the reaction separation chamber.

[0021] Optionally, the multi-stage cyclone separator is arranged at the upper part of the cavity of the reaction separation bin.

[0022] Optionally, one end of the reaction and separation chamber gas outlet line is arranged in the reaction and separation chamber, and the other end is connected to the exhaust pipeline of the multi-stage cyclone separator.

[0023] Optionally, a grinder is provided in the crushing bin; the crushing bin is set according to the processing scale of magnesium hydride, and one or more crushing bins may be provided.

[0024] Optionally, the power of the mill is 5-11 kW.

[0025] Optionally, a hydrogen feed line is provided between the hydrogen compressor and the cooler, and hydrogen enters the hydrogen compressor through the hydrogen feed line.

[0026] Optionally, a deionized water line and a by-product steam line are provided on the steam drum.

[0027] Optionally, a powder fluidization tube bundle is further provided in the cavity of the reaction and separation bin, and the powder fluidization tube bundle is arranged at the bottom of the cavity of the reaction and separation bin.

[0028] Optionally, the air inlet end of the powder fluidization tube bundle is connected to the heater outlet.

[0029] Optionally, a safety discharge line is provided on the top of the reaction separation chamber, and a safety valve is provided on the safety discharge line.

[0030] According to another aspect of the present application, a production method of the production device for large-scale preparation of magnesium hydride is provided, and the production method comprises the following steps:

[0031] (1) When feeding, close all valves and start the hydrogen compressor to transport the raw materials in the raw material bin to the reaction and separation bin through hydrogen;

[0032] (2) During the reaction, the powder fluidization tube bundle is started, the heater cross-line valve is closed, and the hydrogen compressor and heater are started to react with the hydrogen and the raw materials to obtain magnesium hydride;

[0033] (3) When collecting materials, close the main valve, open the product line valve and the product separation gas return valve, and allow magnesium hydride to enter the product bin;

[0034] The raw material is magnesium-based metal powder material.

[0035] Optionally, in step (2), when the hydrogen reacts with the raw material, the hydrogen is first heated by a heater and then reacts with the raw material.

[0036] Optionally, in step (2), the temperature of the reaction between hydrogen and raw materials is adjusted by a heater, a heat exchanger and a cooler.

[0037] Optionally, in step (2), the reaction heat generated in the process of obtaining magnesium hydride is carried by hydrogen into a heat exchanger to generate steam, which is then transported to the outside through a steam drum.

[0038] Optionally, in step (2), the reaction pressure is 1-5 MPa, and the reaction temperature is 250-400°C.

[0039] Optionally, in step (2), the reaction pressure is selected from any value of 1 MPa, 2 MPa, 3 MPa, 4 MPa, 5 MPa or a range between any two of the above values.

[0040] Optionally, in step (2), the reaction temperature is selected from any value of 250°C, 300°C, 350°C, 380°C, 400°C or a range between any two of the above values.

[0041] Optionally, the particle size of the magnesium hydride is 0.5-10 μm.

[0042] Optionally, the purity of magnesium hydride prepared by hydrogenating pure magnesium is >95%.

[0043] Optionally, the magnesium-based metal powder material is selected from at least one of magnesium, magnesium-nickel alloy, magnesium-aluminum alloy, magnesium-rare earth alloy, magnesium-iron oxide mixture, magnesium-graphite mixture, and magnesium-aluminum oxide mixture; wherein the magnesium content in the alloy or mixture is 60 to 99.99%.

[0044] Optionally, the raw material further contains an auxiliary agent, and the content of the auxiliary agent is 1 to 10 wt%.

[0045] In the present application, (1) the material feeding, discharging, material transportation and reaction process are all fluidized, and the fluidized carrier gas is hydrogen to prevent impurity gases from affecting the preparation of magnesium hydride. The feeding process uses hydrogen carrier gas to transport the magnesium powder in the magnesium powder bin to the reaction separation bin in a fluidized manner, thereby entering the reaction cycle process of magnesium powder hydrogenation; after the hydrogenation is completed, the material is discharged, and the material in the reaction cycle is directly transported to the product separator by adjusting the valve, and then enters the product bin after separation; during the entire reaction cycle, the magnesium powder and the reaction product magnesium hydride powder are carried by the hydrogen carrier gas through each unit, and hydrogenation, crushing and separation, as well as heat transfer are completed during the cycle. In the initial stage of hydrogenation, the material is heated by the carrier gas, and the heat generated in the reaction is taken away by the carrier gas during the reaction process.

[0046] The fluidization of materials not only realizes the continuous transportation of materials during the preparation process, facilitating automatic control, but also enhances the mass transfer and heat transfer between hydrogen and materials. At the same time, it increases the friction and collision between materials during the flow process, destroys the magnesium hydride shell on the surface of some magnesium particles, and promotes the hydrogenation reaction.

[0047] (2) Setting a high-speed mill. During the hydrogenation reaction, a magnesium hydride shell will be produced on the surface of the magnesium powder. This shell will affect the mass transfer of hydrogen to the surface of the magnesium powder particles and reduce the reaction efficiency. By setting a high-speed mill, the material will be continuously transported to the high-speed grinding head to crush the material during the hydrogenation reaction, peeling off the magnesium hydride shell on the surface of the magnesium particles, exposing the fresh magnesium surface, and accelerating the hydrogenation process of the magnesium powder.

[0048] (3) Increase the steam drum to recover energy. A large amount of heat is released during the hydrogenation of magnesium powder. The formation enthalpy of magnesium hydride is about 76 kJ / mol-H2. This heat is wasted by cooling during the preparation of magnesium hydride. The present invention adds a steam drum to the reaction cycle system, which can not only save the heat generated in the reaction process in the form of high-pressure steam by generating steam, but also stabilize the temperature of the hydrogen carrier gas by adjusting the steam pressure.

[0049] (4) Heating or cooling the hydrogen carrier gas, using the hydrogen carrier gas to heat or cool the material. The conventional heating process for preparing magnesium hydride begins with heating the magnesium powder by means of heat transfer oil or electric heating. Due to the poor thermal conductivity of the magnesium powder, the internal and external thermal gradient of the reactor will be too large, and the heating will be uneven. The local temperature may be too high, causing the magnesium powder to melt and the particles to become larger. The present invention heats the hydrogen carrier gas by electric heating or heat transfer oil, and then heats the magnesium powder by the hydrogen carrier gas. The high-temperature hydrogen achieves efficient heat transfer to the magnesium powder by forced convection, and this process is in a fluidized state, so that the magnesium powder is heated more evenly and efficiently, and the cooling process is the same.

[0050] A) magnesium powder circulation reaction fluidized system disclosed in the present application. The system includes a hydrogen compressor, a heater, a cooler, a magnesium powder silo, a crushing silo, a reaction separation silo, a gas fluidized tube bundle, a product separator and a magnesium hydride product silo. Magnesium powder feeding, discharging, reaction and transportation between various units are all completed under fluidization.

[0051] b) by setting a high-speed mill to destroy the magnesium hydride shell on the surface of the magnesium powder particles, the hydrogen gas is allowed to contact with the fresh magnesium surface to increase the reaction rate;

[0052] c) By arranging a steam drum on the hydrogen circulation pipeline, the heat generated by the hydrogenation of magnesium powder is recovered in the form of high-pressure steam, and the temperature of the hydrogen can be controlled by adjusting the steam pressure;

[0053] d) The temperature of the hydrogen is adjusted by the cooler and heater on the hydrogen circulation system, and the magnesium powder is heated to the reaction temperature by the heated hydrogen. Similarly, the heat generated by the hydrogenation of the magnesium powder can be taken away by the cooled hydrogen.

[0054] In this application, "magnesium powder" is not specific, but refers to magnesium-based metal materials in general, including one or more combinations of pure magnesium, magnesium-nickel alloy, magnesium-aluminum alloy, magnesium-rare earth alloy, magnesium-iron oxide mixture, magnesium-graphite mixture, magnesium-aluminum oxide mixture, etc., wherein the magnesium content in the alloy or mixture is between 60-99.99%, and the content of other substances is between 0.1-40%.

[0055] The present application solves the problem that the preparation process is a gas-solid reaction by fluidizing operation and using a carrier gas to heat and cool the material. In the existing static high-temperature and high-pressure hydrogenation process, it is difficult for hydrogen to transfer to the surface of fresh magnesium, which affects production efficiency, and it is difficult to transfer heat. The uneven heat transfer during the hydrogenation startup heating process will cause local high temperature. The heat generated during the hydrogenation process cannot be transferred in time, which also causes local high temperature and even temperature runaway. The high temperature will cause the magnesium powder to melt, weld, and enlarge the particles. The hydrogenation is incomplete and the feeding, discharging, and internal transportation and transfer in the preparation process cannot be automated and continuous, and batch production is the only problem. The steam drum is set to solve the problem that a large amount of heat energy generated during the hydrogenation of magnesium powder cannot be recovered, resulting in energy waste. The high-speed mill is set to solve the problem that the magnesium hydride shell on the surface of the magnesium particles cannot be effectively broken and the hydrogenation efficiency is low.

[0056] The beneficial effects of this application include:

[0057] 1) The present application adopts a fluidized material conveying process, which can realize continuous and automated material conveying. At the same time, the carrier gas can be used as a heating and cooling medium for the material, which is more uniform and reliable than traditional heating methods, and can also achieve the effect of partially crushing the material.

[0058] 2) In the large-scale production device for preparing magnesium hydride of the present application, a high-speed mill is provided to effectively break up the surface materials of magnesium powder particles, thereby generating a fresh magnesium surface and accelerating the hydrogenation reaction rate.

[0059] 3) In the large-scale production device for preparing magnesium hydride of the present application, a steam drum can be provided to recover the heat released by hydrogenating magnesium powder. BRIEF DESCRIPTION OF THE DRAWINGS

[0060] Figure 1 This is a schematic diagram of the large-scale magnesium hydride preparation process of this application.

[0061] In the figure:

[0062] 1. Reaction separation bin; 2. Crushing bin; 3. Raw material bin; 4. Heater; 5. Hydrogen compressor; 6. Cooler; 7. Heat exchanger; 8. Steam drum; 9. Filter; 10. Multi-stage cyclone separator; 11. Powder fluidization tube bundle; 12. Product bin; 13. Product separator; 14. Product separation gas return valve; 15. Main valve; 16. Product line valve; 17. Reaction separation bin outlet line; 18. Fluidized material; 19. Hydrogen feed line; 20. Deionized water line; 21. By-product steam line; 22. Safety release line; 23. Circulating hydrogen pipeline; 24. Heat exchanger cross-line valve; 25. Cooler cross-line valve; 26. Heater cross-line valve; 27. Reaction separation bin bottom valve; 28. Crushing bin bottom valve; 29. ​​Raw material bin bottom valve. DETAILED DESCRIPTION

[0063] The present application is described in detail below with reference to embodiments, but the present application is not limited to these embodiments.

[0064] Unless otherwise specified, the raw materials in the examples of this application were purchased through commercial channels.

[0065] Example 1

[0066] like Figure 1 The figure shows a production device for large-scale preparation of magnesium hydride: a reaction separation bin 1, a crushing bin 2, a raw material bin 3, a heater 4, a hydrogen compressor 5, a cooler 6, a heat exchanger 7, a steam drum 8, a filter 9, a product bin 12, and a product separator 13; the upper end of the reaction separation bin 1 is connected to the filter 9, the heat exchanger 7, the cooler 6, the hydrogen compressor 5, the heater 4 and the crushing bin 2 in sequence through a circulating hydrogen pipeline 23; the raw material bin 3 is arranged between the crushing bin 2 and the heater 4; a product separator 13 is provided on the side where the circulating hydrogen pipeline 23 enters the reaction separation bin 1, and the product separator 13 is connected to the product bin 12; the steam drum 8 is arranged above the ventilator 7 and connected to the heat exchanger 7; the reaction separation bin 1 contains a fluidized material 18.

[0067] A product separation gas return valve 14 is provided on the side of the reaction separation chamber 1, and the product separation gas return valve 14 is connected to the product separator 13. Below the product separator 13 is the product chamber 12. The side of the product separator 13 is connected to a product line valve 16, and the product line valve 16 is connected to the circulating hydrogen pipeline 23. A main valve 15 is installed downstream of the connection point.

[0068] The reaction separation chamber 1 is connected to a safety discharge line 22, which includes a safety valve. The exhaust pipeline of the multi-stage cyclone separator 10 is connected to the inlet of the filter 9, and its outlet pipeline is connected to the tube inlet side of the heat exchanger 7, and the tube outlet side is connected to the inlet of the cooler 6. The secondary inlet line is connected to the hydrogen feed line 19, and the outlet of the cooler 6 is connected to the inlet of the hydrogen compressor 5. The outlet of the compressor is connected to the heater 4, and the outlet of the heater 4 is connected to the circulating hydrogen pipeline 23. The circulating hydrogen pipeline 23 is connected to the raw material chamber 3 and the crushing chamber 2, and is finally connected to the reaction separation chamber 1 through the main valve 15. The raw material chamber 3 and the circulating hydrogen pipeline 23 are provided with a raw material chamber bottom valve 29.

[0069] The heat exchanger 7 is connected to the steam drum 8, which is connected to the deionized water line 20 and the byproduct steam line 21. The heat exchanger 7, the cooler 6 and the heater 4 are all provided with crossovers, and the valves on the crossovers are the heat exchanger crossover valve 24, the cooler crossover valve 25 and the heater crossover valve 26.

[0070] The reaction separation chamber 1 is connected to the inlet of the crushing chamber 2 below, and a reaction separation chamber bottom valve 27 is provided on the connecting pipeline. The bottom outlet of the crushing chamber 2 is connected to the cyclic hydrogen pipeline 23, and a crushing chamber bottom valve 28 is provided on the connecting pipeline.

[0071] The powder fluidization tube bundle 11 is installed at the bottom of the reaction separation bin 1, and its air inlet end is connected to the downstream pipeline of the heater 4. The multi-stage cyclone separator 10 is installed in the upper part of the reaction separation bin 1 cavity. The reaction separation bin outlet line 17 is installed at the top of the reaction separation bin cavity 1 and connected to the exhaust pipeline of the multi-stage cyclone separator 10 in front of the filter 9; the crushing bin 2 is composed of an outer shell and an internal high-speed grinder.

[0072] Example 2

[0073] Feeding process: First, ensure that all valves are closed, ensure that the raw material warehouse 3 has sufficient raw material elemental magnesium powder, and ensure that the production device (system) for large-scale preparation of magnesium hydride has been purged clean. The system is in a vacuum state except for the raw material warehouse 3, product separator 13, product warehouse 12, heat exchanger 7, steam drum 8 and its connecting lines. The appropriate amount of deionized water is injected into the shell side of steam drum 8 and heat exchanger 7, and the steam drum exhaust pressure is set to 4MPa (G). Adjust the heat exchanger cross-line valve 24, cooler cross-line valve 25, heater cross-line valve 26 and main valve 15 to ensure that the material bypasses the heat exchanger 7, cooler 6 and heater 4. Then inject 3MPa of hydrogen into the system through the hydrogen feed line 19 and stop. Start the hydrogen compressor 5 to circulate the hydrogen in the system, open the bottom valve 29 of the raw material bin, and transport the magnesium powder to the reaction separation bin 1. In the reaction separation bin, the hydrogen carrier gas and the magnesium powder material are separated by a multi-stage cyclone separator, and the magnesium powder material falls into the reaction separation bin 1. The hydrogen enters the filter 9, and the filtered gas enters the heat exchanger cross-line valve 24, and then passes through the cooler cross-line valve 25 and returns to the compressor inlet. After the magnesium powder material is transported to a predetermined amount, the bottom valve 29 of the raw material bin is closed.

[0074] Reaction process: start the powder fluidization tube bundle 11, close the heater cross-line valve 26, let hydrogen enter the heater 4, start the heater 4, raise the hydrogen temperature to 300°C, start the mill of the crushing bin 2 when the temperature of the magnesium powder material in the reaction separation bin 1 reaches 250°C, open the bottom valve 27 of the reaction separation bin and the bottom valve 28 of the crushing bin in sequence, and close the heat exchanger cross-line valve 24 and the cooler cross-line valve 25. When the temperature rises to 300°C, turn off the heater 4. At this time, the hydrogenation reaction has begun, and the reaction process will consume hydrogen. If the hydrogen pressure in the system is lower than 3MPa (G), it will be automatically replenished. The heat generated by the reaction is carried to the heat exchanger 7 by the hydrogen, heating the water therein and generating steam. The steam is supplied to the outside through the steam drum. After the hydrogen passes through the heat exchanger, the temperature is controlled within 270°C. If the temperature is too high, it is cooled by the cooler 6. The magnesium powder material reacts with hydrogen to produce magnesium hydride. The material enters the crushing bin 2 from the bottom of the reaction separation bin 1. The magnesium powder material is squeezed and collided by the high-speed mill. The magnesium hydride shell generated on the surface of the magnesium powder particles is broken and falls off due to its brittleness and scatters at the bottom of the crushing bin 2. Then, it enters the circulating hydrogen pipeline 23 through the bottom valve 28 of the crushing bin. The particles containing magnesium powder and magnesium hydride are carried by the hydrogen carrier gas into the reaction separation bin 1 and separated by the multi-stage cyclone separator 10, so that the magnesium powder and magnesium hydride particles fall into the reaction separation bin 1 respectively. The carrier gas hydrogen re-enters the filter 9 and enters the next cycle.

[0075] Receiving process: After several hours of circulation (different sizes of magnesium powder particles have different feeding reaction times), all the magnesium powder in the system is converted into magnesium hydride powder, and the temperature of heat exchanger 7 gradually decreases. When the inlet temperature is less than 290°C, the logistics is switched to the heat exchanger 7 cross-line, and the drum steam generation is stopped. The temperature in the reaction separation bin gradually drops to room temperature, the main valve 15 is closed, the product line valve 16 and the product separation gas return valve 14 are opened, and the material enters the product separator 13, in which the magnesium hydride powder product is separated by cyclone and enters the product bin 12 from the bottom, and the hydrogen carrier gas enters the reaction separation bin 1, completing a reaction cycle. Among them, the reaction time of 4 to 12 hours of 0.28 mm size magnesium powder particles is used to obtain magnesium hydride with a particle size of 0.5-10 um.

[0076] The fluidization operation using hydrogen reaction gas as a carrier gas not only solves the problem of material transportation, but also makes the heat and mass transfer between gas and solid more sufficient and efficient, solves the problems of uneven material reaction, poor solid heat transfer performance, and local temperature runaway caused by too fast reaction. In addition, high-speed flow increases the collision and friction between material particles, and timely breaks the magnesium hydride layer on the surface of the magnesium powder particles, allowing hydrogen to more easily contact the surface of fresh magnesium powder particles, thereby accelerating the reaction rate.

[0077] The present invention adopts a steam drum as one of the temperature regulating means of the reaction system, which can not only stabilize the reaction temperature but also recover the heat generated in the reaction in the form of high-temperature and high-pressure steam.

[0078] The invention adopts a high-speed mill as a crushing means, which can timely and efficiently break the magnesium hydride layer generated on the surface of the magnesium powder, and can continuously crush the magnesium hydride particles to obtain a product with a smaller particle size.

[0079] The above are only a few embodiments of the present application and do not constitute any form of limitation to the present application. Although the present application is disclosed as above with preferred embodiments, it is not intended to limit the present application. Any technician familiar with the profession, without departing from the scope of the technical solution of the present application, using the technical content disclosed above to make slight changes or modifications are equivalent to equivalent implementation cases and fall within the scope of the technical solution.

Claims

1. A production device for large-scale preparation of magnesium hydride, characterized in that: The production device comprises: a reaction separation chamber (1), a crushing chamber (2), a raw material chamber (3), a heater (4), a hydrogen compressor (5), a cooler (6), a heat exchanger (7), a steam drum (8), a filter (9), a product chamber (12), a product separator (13), a heat exchanger cross-line valve (24), a cooler cross-line valve (25), a heater cross-line valve (26), and a main valve (15); The upper end of the reaction and separation chamber (1) is connected to the filter (9), the heat exchanger (7), the cooler (6), the hydrogen compressor (5), the heater (4) and the crushing chamber (2) in sequence through a circulating hydrogen pipeline (23); The raw material bin (3) is arranged between the crushing bin (2) and the heater (4); A product separator (13) is provided on the side where the circulating hydrogen pipeline (23) enters the reaction separation chamber (1), and the product separator (13) is connected to the product chamber (12); The heat exchanger (7) is connected to the steam drum (8) and the heat exchanger cross-line valve (24); The cooler (6) is connected to a cooler cross-line valve (25), and the heater (4) is connected to a heater cross-line valve (26); A product separation gas return valve (14) is provided between the product separator (13) and the reaction separation chamber (1); The main valve (15) is arranged on the pipeline where the circulating hydrogen pipeline (23) enters the reaction separation chamber (1); A reaction separation bin bottom valve (27) is provided at the bottom of the reaction separation bin (1), a crushing bin bottom valve (28) is provided at the bottom of the crushing bin (2), and a raw material bin bottom valve (29) is provided at the bottom of the raw material bin.

2. The production device according to claim 1, characterized in that: The reaction and separation chamber (1) is provided with a multi-stage cyclone separator (10) and a reaction and separation chamber gas outlet line (17); Preferably, the multi-stage cyclone separator (10) is arranged at the upper part of the cavity of the reaction separation bin; Preferably, one end of the reaction and separation chamber gas outlet line (17) is arranged in the reaction and separation chamber (1), and the other end is connected to the exhaust pipeline of the multi-stage cyclone separator (10).

3. The production device according to claim 1, characterized in that: The crushing chamber (2) is provided with a grinding machine; Preferably, the power of the mill is 5-11 kw.

4. The production device according to claim 1, characterized in that: A hydrogen feed line (19) is provided between the hydrogen compressor (5) and the cooler (6), and hydrogen enters the hydrogen compressor (5) through the hydrogen feed line (19); Preferably, the steam drum (8) is provided with a deionized water line (20) and a by-product steam line (21).

5. The production device according to claim 1, characterized in that: A powder fluidization tube bundle (11) is also provided in the cavity of the reaction and separation bin (1), and the powder fluidization tube bundle (11) is arranged at the bottom of the cavity of the reaction and separation bin (1); Preferably, the air inlet end of the powder fluidization tube bundle (11) is connected to the outlet of the heater (4).

6. The method for producing a large-scale production device for preparing magnesium hydride according to any one of claims 1 to 5, characterized in that: The production method comprises the following steps: (1) When feeding, close all valves and start the hydrogen compressor to transport the raw materials in the raw material bin to the reaction and separation bin through hydrogen; (2) During the reaction, the powder fluidization tube bundle is started, the heater cross-line valve is closed, and the hydrogen compressor and heater are started to react with the hydrogen and the raw materials to obtain magnesium hydride; (3) When collecting materials, close the main valve, open the product line valve and the product separation gas return valve, and allow magnesium hydride to enter the product bin; The raw material is magnesium-based metal powder material.

7. The production method according to claim 6, characterized in that: In the step (2), when the hydrogen reacts with the raw material, the hydrogen is first heated by a heater and then reacts with the raw material; Preferably, in step (2), the temperature of the reaction between hydrogen and raw materials is adjusted by a heater, a heat exchanger and a cooler.

8. The production method according to claim 6, characterized in that: In the step (2), the reaction heat generated in the process of obtaining magnesium hydride is carried by hydrogen into the heat exchanger (7) to generate steam, which is then transported to the outside through the steam drum (8).

9. The production method according to claim 6, characterized in that: In the step (2), the reaction pressure is 1-5 MPa, and the reaction temperature is 250-400°C.

10. The production method according to claim 6, characterized in that: The particle size of the magnesium hydride is 0.5 to 10 μm; Preferably, the magnesium-based metal powder material is selected from at least one of magnesium, magnesium-nickel alloy, magnesium-aluminum alloy, magnesium-rare earth alloy, magnesium-iron oxide mixture, magnesium-graphite mixture, and magnesium-aluminum oxide mixture; wherein the magnesium content in the alloy or mixture is 60 to 99.99%; Preferably, the raw material further contains an auxiliary agent, and the content of the auxiliary agent is 1 to 10 wt %.

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