A hydrogen generator based on magnesium borohydride and a fuel cell integrated system

Abstract

The application aims to provide a hydrogen generator based on magnesium borohydride and a fuel cell integrated system, belonging to the field of engines, comprising a nitrogen storage bottle, a hydrogen generator reaction container, a magnesium borohydride solid storage container, a fuel cell stack and other auxiliary devices.The hydrogen generator based on magnesium borohydride can produce hydrogen on line to provide fuel for the fuel cell.The integrated system scheme of the hydrogen generator and the fuel cell is provided, and the product of the hydrogen generator is supplied to the anode of the fuel cell after purification, and water generated by the cathode of the fuel cell is provided to the hydrogen generator after recovery.

Description

TECHNICAL FIELD

[0001] The present application relates to a hydrogen storage and fuel cell device, in particular, a generator and fuel cell based on solid hydrogen storage material. BACKGROUND

[0002] Under the current trend of energy saving and emission reduction, clean and efficient hydrogen energy has become a hot spot for development. However, due to the characteristics of hydrogen, the huge challenge of hydrogen energy utilization is in storage and transportation. Finding an efficient, economical and safe storage and transportation solution is an important part of developing hydrogen energy economy.

[0003] The currently used hydrogen storage technologies include high-pressure gaseous hydrogen storage, cryogenic liquid hydrogen storage, organic liquid hydrogen storage and solid material hydrogen storage. The relatively mature high-pressure gaseous hydrogen storage often requires a pressure as high as 70 MPa, which requires a high-pressure container. Although its cost and energy consumption are low, it has a small mass energy density and potential safety hazards such as leakage and explosion. Cryogenic liquid hydrogen storage has very high mass energy density and volume energy density, but consumes a lot of energy during storage, accounting for about 40% of the energy of the stored hydrogen itself. Liquid organic hydrogen storage has the disadvantages of complex dehydrogenation technology and high dehydrogenation energy consumption, and has not been widely used.

[0004] Mg(BH4)2 is a hydrogen storage material with a mass hydrogen storage density of 14.9wt.% and a volume hydrogen density of 112 g / L. The intermediate borate formed by pyrolysis of Mg(BH4)2 at 200℃ is conducive to rehydrogenation, which provides the possibility for reversible hydrogen storage of Mg(BH4)2. The hydrolysis reaction of magnesium borohydride can be carried out at room temperature, and the reaction equation with water is: and the process is accompanied by heat release. SUMMARY

[0005] The purpose of the present application is to provide a hydrogen generator and fuel cell integrated system based on magnesium borohydride, which can take advantage of solid hydrogen storage material in storage and transportation, and reduce repeated components, save space and weight.

[0006] The purpose of the present application is achieved as follows:

[0007] The hydrogen generator based on magnesium borohydride of the present application comprises a magnesium borohydride storage device and a hydrogen generator shell, and an ultrasonic atomizer is arranged at the bottom of the hydrogen generator shell, and the position of the ultrasonic atomizer is filled with water, and the bottom of the magnesium borohydride storage device is connected to the hydrogen generator shell through an ejector.

[0008] The hydrogen generator based on magnesium borohydride of the present application can further comprise:

[0009] 1. The bottom of the magnesium borohydride storage device is provided with a gear and a small hole, and the small hole is located on the track of the gear teeth.

[0010] The application discloses a magnesium borohydride-based fuel cell integrated system, which is characterized by comprising a fuel cell, a nitrogen cylinder, a water storage tank, an expansion water tank, a hydrogen buffer and a hydrogen generator, the nitrogen cylinder is connected with an ejector through an electromagnetic valve, the bottom of the hydrogen generator shell is connected with the water storage tank, the middle part of the hydrogen generator shell is connected with a purification device through a second filter, the hydrogen buffer comprises two hydrogen cylinders connected in parallel, the purification device is connected with the two hydrogen cylinders through a third three-way valve, the two hydrogen cylinders are connected with a hydrogen booster through a second three-way valve, the hydrogen booster is connected with the anode of the fuel cell through a first humidifier, the cathode of the fuel cell is connected with an intercooler through a second humidifier, air enters the intercooler through a first filter and an air compressor, the anode outlet of the fuel cell is connected with a second discharge valve, the cathode outlet of the fuel cell is connected with a first discharge valve through a gas-liquid separator, and the gas-liquid separator is connected with the water storage tank through a second deionizer.

[0011] The application also discloses a magnesium borohydride-based fuel cell integrated system.

[0012] 1. The system further comprises an expansion water tank, cooling water of the fuel cell is collected with cooling water of the intercooler and the hydrogen generator through a circulating water pump, and then flows into a radiator, and the expansion water tank is connected with the fuel cell, the intercooler and the hydrogen generator through a first deionizer respectively.

[0013] 2. A first three-way valve is arranged between the expansion water tank and the first deionizer, the first three-way valve is further connected with a PTC heater, and the PTC heater is connected with the radiator.

[0014] The application has the following advantages.

[0015] 1. The exhaust gas of the cathode of the fuel cell enters the gas-liquid separator to obtain water, the water enters a deionizer and then enters the water storage tank of the hydrogen generator, so that the water is reused.

[0016] 2. The cooling system of the hydrogen generator and the cooling system of the fuel cell are integrated in the system, so that repeated components are reduced, space and weight are saved, a large amount of heat is released in the hydrolysis process of magnesium borohydride, and therefore the reaction chamber needs to be cooled; the reaction chamber adopts a water cooling scheme, cooling water at the outlet of the reaction chamber is collected with cooling water at the outlet of the fuel cell, and then flows into the radiator, and after being cooled and deionized, the cooling water flows into the reaction chamber, so that the temperature of the reaction chamber is controlled; in addition, the integrated thermal management system is beneficial to cold start of the fuel cell; since heat is released in the hydrolysis process of magnesium borohydride, in the cold start process, the hydrogen generator is started first to generate hydrogen, at this time, the heat released in the hydrolysis of magnesium borohydride is used to assist in preheating the fuel cell through the cooling system, so that the power of the PTC heater can be reduced, and energy consumption is reduced.

[0017] 3、The application can adjust the hydrogen production rate according to the power requirement during the operation of the fuel cell. The bottom of the magnesium borohydride storage tank has a gear, and the magnesium borohydride powder is supplied through the gap of the gear and the small hole at the bottom of the storage tank. During the operation of the fuel cell, the amount of magnesium borohydride supplied can be controlled by changing the speed of the gear, thereby changing the hydrogen production rate. In addition, the hydrogen produced is filtered and purified and then enters the buffer tank composed of two hydrogen cylinders connected in parallel. By controlling the supply of hydrogen in the buffer tank, the power change of the fuel cell is adapted. This design helps to decouple the preparation and supply of hydrogen to the fuel cell, thereby realizing rapid response of hydrogen supply and avoiding the problem of fuel starvation when the power of the fuel cell changes.

[0018] 4、The application has the advantages of high energy density and compact structure. The boron and magnesium raw materials required for the synthesis of magnesium borohydride are abundant in China and have low price. The mass hydrogen storage density of magnesium borohydride is 14.9wt.%, and magnesium borohydride has great advantages in storage and transportation compared with high-pressure hydrogen and liquid hydrogen. The borate obtained by decomposition of magnesium borohydride can be hydrogenated again under certain conditions, providing the possibility of reversible hydrogen storage.

[0019] 5、The bottom of the hydrogen generator is provided with an ultrasonic atomizer. The magnesium borohydride powder encounters the water mist generated by the ultrasonic atomizer after being sprayed into the reaction chamber, and a hydrolysis reaction occurs. Such a scheme is beneficial to the full contact of magnesium borohydride powder with water mist, and improves the rate of reaction. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 is a structural schematic diagram of the application;

[0021] Figure 2 is a magnesium borohydride storage device. DETAILED DESCRIPTION

[0022] The application will be described in more detail below with examples combined with the drawings:

[0023] Combined Figures 1-2The hydrogen generator based on magnesium borohydride and fuel cell integrated system includes fuel cell 1, hydrogen generator 18, radiator 12, first deionizer 9a, second deionizer 9b, circulating water pump 8, gas-liquid separator 6, first humidifier 2a, second humidifier 2b, hydrogen booster 15, intercooler 3, air compressor 4, first filter 5a, second filter 5b, purification device 16, storage water tank 14, hydrogen buffer 23, nitrogen cylinder 19, ejector 24, ultrasonic atomizer 17, expansion water tank 13, PTC heater 11, magnesium borohydride storage 22, first three-way valve 10a, second three-way valve 10b, third three-way valve 10c, first discharge valve 7a, second discharge valve 7b, third discharge valve 7c, electromagnetic valve 20, pressure relief valve 21. Nitrogen cylinder 19 enters the ejector 24 through the electromagnetic valve 20 and the pressure relief valve 21, and the magnesium borohydride powder provided in the magnesium borohydride storage 22 is sprayed into the hydrogen generator 18. The bottom of the hydrogen generator 18 is connected to the storage water tank 14, and the water is atomized by the ultrasonic atomizer 17 to form water mist, which is mixed with the sprayed magnesium borohydride powder to produce hydrogen by hydrolysis reaction and release a large amount of heat. The generated hydrogen is filtered by the second filter 5b to remove solid impurities, and then enters the purification device 16 for further purification. The obtained pure hydrogen enters the hydrogen buffer 23 through the third three-way valve 10c, which is composed of two hydrogen cylinders connected in parallel. The hydrogen in the hydrogen buffer 23 is supplied to the anode of the fuel cell 1 through the second three-way valve 10b, the hydrogen booster 15 and the first humidifier 2a. At the cathode of the fuel cell 1, the air enters the intercooler 3 after passing through the first filter 5a and the air compressor 4, and then enters the second humidifier 2b to supply the fuel cell 1. The anode outlet of the fuel cell 1 is connected to the second discharge valve 7b, and the cathode outlet is connected to the gas-liquid separator 6 and the first discharge valve 7a. The water discharged from the gas-liquid separator 6 enters the storage water tank 14 after passing through the second deionizer 9b, realizing the reuse of the product water. The cooling water of the fuel cell 1 flows into the radiator 12 after being collected with the cooling water of the intercooler 3 and the hydrogen generator 18 by the circulating water pump 8, and the expansion water tank 13 supplements the cooling water, which is then returned to the fuel cell 1, the intercooler 3 and the hydrogen generator 18 after passing through the first deionizer 9a.

[0024] As shown in Figure 2 The bottom of the magnesium borohydride storage 22 is provided with a gear 22a and a small hole 22b, and the magnesium borohydride powder is supplied outward through the gap of the gear 22a and the small hole 22b. By controlling the rotating speed of the gear 22a, the hydrogen generation rate can be controlled to meet the fuel demand when the power of the fuel cell changes.

[0025] The fuel cell 1 is a water-cooled proton exchange membrane fuel cell; the purification device 16 is a PSA purification device or a membrane separation purification device.

[0026] The temperature of the hydrogen generator 18 is controlled by the cooling water in the fuel cell thermal management system.

[0027] The thermal management system of the fuel cell includes a radiator 12, a PTC heater 11, a first deionizer 9a, and an expansion water tank 13. The cooling water of the hydrogen generator 18 is merged into the fuel cell thermal management system, and the hydrogen generator cooling water is used for auxiliary heating during the start-up stage of the fuel cell due to the heat released by the hydrolysis reaction occurring in the hydrogen generator 18.

Claims

1. A hydrogen generator based on magnesium borohydride, characterized in that: The hydrogen generator comprises a magnesium borohydride storage, a hydrogen generator shell, an ultrasonic atomizer arranged at the bottom of the hydrogen generator shell, and water filled at the position of the ultrasonic atomizer; the bottom of the magnesium borohydride storage is connected to the hydrogen generator shell through an ejector. The bottom of the magnesium borohydride storage is provided with a gear and a small hole, and the small hole is located on the track of the gear teeth.

2. A magnesium borohydride fuel cell integrated system, characterized by: The hydrogen generator comprises a fuel cell, a nitrogen cylinder, a water storage tank, an expansion water tank, a hydrogen buffer, and the hydrogen generator of claim 1; the nitrogen cylinder is connected to the ejector through an electromagnetic valve; the bottom of the hydrogen generator shell is connected to the water storage tank; the middle of the hydrogen generator shell is connected to a purification device through a second filter; the hydrogen buffer comprises two hydrogen cylinders connected in parallel; the purification device is connected to the two hydrogen cylinders through a third three-way valve; the two hydrogen cylinders are connected to a hydrogen booster through a second three-way valve; the hydrogen booster is connected to the anode of the fuel cell through a first humidifier; the cathode of the fuel cell is connected to an intercooler through a second humidifier; air enters the intercooler through a first filter and an air compressor; the outlet of the anode of the fuel cell is connected to a second exhaust valve; the outlet of the cathode of the fuel cell is connected to a first exhaust valve through a gas-liquid separator; the gas-liquid separator is connected to the water storage tank through a second deionizer.

3. The magnesium borohydride fuel cell integrated system according to claim 2, characterized in that: The hydrogen generator further comprises an expansion water tank; the cooling water of the fuel cell, the intercooler, and the hydrogen generator is collected through a circulating water pump, and then flows into a radiator; the expansion water tank is connected to the fuel cell, the intercooler, and the hydrogen generator through a first deionizer.

4. A fuel cell integrated system based on magnesium borohydride according to claim 3, characterized in that: A first three-way valve is arranged between the expansion water tank and the first deionizer; the first three-way valve is further connected to a PTC heater; and the PTC heater is connected to the radiator.

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