Hydrogen generator based on magnesium borohydride and fuel cell integrated system

Abstract

The invention aims to provide a hydrogen generator based on magnesium borohydride and a fuel cell integrated system, which belong to the field of engines and comprise a nitrogen storage bottle, a hydrogen generator reaction container, a magnesium borohydride solid storage container, a fuel cell stack and other auxiliary devices. The magnesium borohydride hydrogen generator provided by the invention can produce hydrogen on line and provide fuel for a fuel cell. An integrated system scheme of a hydrogen generator and a fuel cell is provided, a product of the hydrogen generator is supplied to an anode of the fuel cell after being purified, and water generated by a cathode of the fuel cell is recycled and supplied to the hydrogen generator.

Description

Technical Field

[0001] The present invention relates to a hydrogen storage and fuel cell device, in particular to a generator and a fuel cell based on solid hydrogen storage materials. Background Art

[0002] Under the current trend of energy conservation 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 lies in storage and transportation. Finding an efficient, economical and safe storage and transportation solution is an important part of developing the hydrogen energy economy.

[0003] The main hydrogen storage technologies currently used are: high-pressure gaseous hydrogen storage, low-temperature liquefied hydrogen storage, organic liquid hydrogen storage and solid material hydrogen storage. The more mature high-pressure gaseous hydrogen storage often requires a pressure of up to 70MPa and requires a high-pressure resistant container. Although its cost and energy consumption are low, its mass density is low and there are safety hazards of leakage and explosion. Low-temperature liquid hydrogen storage has a high mass energy density and volume energy density, but consumes a lot of energy during the storage process, which accounts 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 112g / L. The intermediate borate formed by pyrolysis of Mg(BH4)2 at 200℃ is conducive to rehydride, which makes reversible hydrogen storage of Mg(BH4)2 possible. The hydrolysis reaction of magnesium borohydride can be carried out at room temperature, and the reaction equation for its reaction with water is:

[0005] Mg(BH4)2+4H2O→Mg(BO2)+8H2

[0006] And the process is accompanied by heat release. Summary of the invention

[0007] The object of the present invention is to provide a hydrogen generator and fuel cell integrated system based on magnesium borohydride, which can give full play to the advantages of solid hydrogen storage materials in storage and transportation, reduce repeated parts, and save space and weight.

[0008] The object of the present invention is achieved in that:

[0009] The invention discloses a hydrogen generator based on magnesium borohydride, which is characterized by comprising a magnesium borohydride storage and a hydrogen generator shell, wherein an ultrasonic atomizer is arranged at the bottom of the hydrogen generator shell, the position where the ultrasonic atomizer is located is filled with water, and the bottom of the magnesium borohydride storage is connected to the hydrogen generator shell through an ejector.

[0010] The hydrogen generator based on magnesium borohydride of the present invention may also include:

[0011] 1. A gear and a small hole are provided at the bottom of the magnesium borohydride storage tank, and the small hole is located on the rotation track of the gear teeth.

[0012] The invention discloses an integrated system of fuel cells based on magnesium borohydride, which is characterized by comprising a fuel cell, a nitrogen cylinder, a storage water tank, an expansion water tank, a hydrogen buffer and a hydrogen generator, wherein the nitrogen cylinder is connected to an ejector through an electromagnetic valve, the bottom of a hydrogen generator shell is connected to the storage water 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 supercharger through a second three-way valve, the hydrogen supercharger is connected to an 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 anode outlet of the fuel cell is connected to a second discharge valve, the cathode outlet of the fuel cell is connected to the first discharge valve through a gas-liquid separator, and the gas-liquid separator is connected to the storage water tank through a second deionizer.

[0013] The magnesium borohydride fuel cell integrated system of the present invention may also include:

[0014] 1. It also includes an expansion water tank. The cooling water of the fuel cell is collected by the circulating water pump and the cooling water of the intercooler and the hydrogen generator, and then flows into the radiator. The expansion water tank is connected to the fuel cell, the intercooler and the hydrogen generator respectively through the first deionizer.

[0015] 2. A first three-way valve is arranged between the expansion water tank and the first deionizer. The first three-way valve is also connected to a PTC heater, and the PTC heater is connected to a radiator.

[0016] The advantages of the present invention are:

[0017] 1. The cathode exhaust of the fuel cell of the present invention enters the gas-liquid separator to obtain water, and the water enters the deionizer and enters the storage water tank of the hydrogen generator, thereby realizing the reuse of water.

[0018] 2. The cooling system of the hydrogen generator in the system proposed by the present invention is integrated with the cooling system of the fuel cell, which reduces duplicate components and saves space and weight. Magnesium borohydride releases a large amount of heat during the hydrolysis process, so it is necessary to dissipate heat from the reaction chamber. The reaction chamber adopts a water-cooling scheme, and the cooling water at the outlet of the reaction chamber and the cooling water at the outlet of the fuel cell are collected and enter the radiator, and then enter the reaction chamber after cooling and deionization, so as to control the temperature of the reaction chamber. In addition, the integrated thermal management system is conducive to the cold start of the fuel cell. Since the hydrolysis process of magnesium borohydride releases heat, in the cold start process, the hydrogen generator is first started to produce hydrogen. At this time, the heat released by the hydrolysis of magnesium borohydride is used to assist in preheating the fuel cell through the cooling system, which can reduce the power of the PTC heater and reduce energy consumption.

[0019] 3. The present invention can adjust the hydrogen production rate according to the power demand during the operation of the fuel cell. There is a gear at the bottom of the magnesium borohydride storage tank, and the magnesium borohydride powder is supplied through the gap between the gears and the small holes at the bottom of the storage tank. During the operation of the fuel cell, the supply of magnesium borohydride can be controlled by changing the gear speed, thereby changing the hydrogen production rate. In addition, after filtering and purification, the produced hydrogen enters a buffer tank composed of two hydrogen bottles in parallel. By controlling the supply of hydrogen in the buffer tank, adaptation to changes in fuel cell power is achieved. This design is conducive to decoupling the preparation of hydrogen and the supply to the fuel cell, thereby achieving a rapid response to the hydrogen supply and avoiding the problem of fuel starvation when the fuel cell power changes.

[0020] 4. The present invention 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 cheap. The mass hydrogen storage density of magnesium borohydride is 14.9wt.%, and magnesium borohydride has great advantages over high-pressure hydrogen and liquid hydrogen in storage and transportation. The borate obtained after the decomposition of magnesium borohydride can be hydrogenated again under certain conditions, which provides the possibility of reversible hydrogen storage.

[0021] 5. An ultrasonic atomizer is set at the bottom of the hydrogen generator. After the magnesium borohydride powder is sprayed into the reaction chamber, it meets the water mist generated by the ultrasonic atomizer and undergoes a hydrolysis reaction. This solution is conducive to the full contact between the magnesium borohydride powder and the water mist, thereby increasing the reaction rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a structural schematic diagram of the present invention;

[0023] Figure 2 It is a magnesium borohydride storage device. DETAILED DESCRIPTION

[0024] The present invention is described in more detail below with reference to the accompanying drawings:

[0025] Combination Figure 1-2 The hydrogen generator and fuel cell integrated system based on magnesium borohydride proposed in the present invention comprises a fuel cell 1, a hydrogen generator 18, a cooler and a fan 12, a deionizer 9a, 9b, a circulating water pump 8, a gas-liquid separator 6, a humidifier 2a, 2b, a hydrogen supercharger 15, an intercooler 3, an air compressor 4, filters 5a, 5b, a purification device 16, a storage water tank 14, a hydrogen buffer 23, a nitrogen bottle 19, an ejector 24, an ultrasonic atomizer 17, an expansion water tank 13, a PTC heater 11, a magnesium borohydride storage 22, a three-way valve 10a, 10b, 10c, a pressure relief valve 7a, 7b, 7c, a solenoid valve 20, and a pressure relief valve 21. The nitrogen tank 19 enters the ejector 24 through the solenoid 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. The water forms water mist through the ultrasonic atomizer 17, and is mixed with the injected magnesium borohydride powder to undergo a hydrolysis reaction to produce hydrogen and release a large amount of heat. The generated hydrogen is filtered through the 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 three-way valve 10c, which is composed of two hydrogen bottles in parallel. The hydrogen in the hydrogen buffer 23 supplies fuel to the anode of the fuel cell 1 through the three-way valve 10b, the hydrogen supercharger 15 and the humidifier 2a. At the cathode of the fuel cell 1, the air enters the intercooler 3 after passing through the filter 5a and the air compressor 4, and the cooled air is supplied to the fuel cell 1 after passing through the humidifier 2b. The anode outlet of the fuel cell 1 is connected to the discharge valve 7b, and the cathode outlet is connected to the gas-liquid separator 6 and the discharge valve 7a. The water discharged from the gas-liquid separator 6 enters the storage water tank 14 after passing through the deionizer 9b, so as to realize the reuse of the product water. The cooling water of the fuel cell 1 passes through the circulating water pump 8, and is collected by the cooling water of the intercooler 3 and the hydrogen generator 18 before flowing into the radiator 12. The expansion water tank 13 replenishes the cooling water, and the cooling water flows back to the fuel cell 1, the intercooler 3 and the hydrogen generator 18 after passing through the deionizer 9a.

[0026] like Figure 2 As shown, a gear 22a and a small hole 22b are provided at the bottom of the magnesium borohydride storage 22, and magnesium borohydride powder is supplied to the outside through the gap of the gear 22a and the small hole 22b. By controlling the rotation speed of the gear 22a, the hydrogen generation rate can be controlled to meet the fuel demand when the fuel cell power changes.

[0027] 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.

[0028] The temperature of the hydrogen generator 18 is controlled by cooling water in the fuel cell thermal management system.

[0029] The thermal management system of the fuel cell includes a radiator 12, a PTC heater 11, a deionizer 9a, and an expansion tank 13. The cooling water of the hydrogen generator 18 flows into the fuel cell thermal management system. Since the hydrolysis reaction in the hydrogen generator 18 releases heat, the cooling water of the hydrogen generator is used for auxiliary heating during the startup phase of the fuel cell.

Claims

1. A hydrogen generator based on magnesium borohydride, characterized in that: The invention comprises a magnesium borohydride storage and a hydrogen generator shell. An ultrasonic atomizer is arranged at the bottom of the hydrogen generator shell. The position of the ultrasonic atomizer is filled with water. The bottom of the magnesium borohydride storage is connected with the hydrogen generator shell through an ejector.

2. A hydrogen generator based on magnesium borohydride according to claim 1, characterized in that: A gear and a small hole are arranged at the bottom of the magnesium borohydride storage, and the small hole is located on the track where the teeth of the gear rotate.

3. A magnesium borohydride fuel cell integrated system, characterized by: It comprises a fuel cell, a nitrogen cylinder, a storage water tank, an expansion water tank, a hydrogen buffer and the hydrogen generator as claimed in claim 1, the nitrogen cylinder is connected to an ejector through a solenoid valve, the bottom of the hydrogen generator shell is connected to the storage water 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 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 supercharger through a second three-way valve, the hydrogen supercharger is connected to the anode of the fuel cell through a first humidifier, the cathode of the fuel cell is connected to the 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 to the second exhaust valve, the cathode outlet of the fuel cell is connected to the first exhaust valve through a gas-liquid separator, and the gas-liquid separator is connected to the storage water tank through a second deionizer.

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

5. The magnesium borohydride fuel cell integrated system according to claim 4 is 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 also connected to the PTC heater, and the PTC heater is connected to the radiator.

Images