RU2285859C1 - Tank for storing and accumulating hydrogen - Google Patents

Abstract

FIELD: hydrogen power engineering.

SUBSTANCE: tank comprises pressure-tight housing, branch pipes, heater, and filler-accumulator of hydrogen mounted inside the housing. The tank is separated with the baffle made of proton-conducting material into anode space filled with water and provided with porous anode and cathode space that receives the solid cathode and heater and is filled with the filler-accumulator of hydrogen made of microporous high-strength material. The microporous material is made of hollow microspheres.

EFFECT: enhanced safety and capacity.

6 cl, 3 dwg

Description

The invention relates to the field of hydrogen energy - the accumulation and storage of hydrogen, which is currently used in chemical, transport engineering and other industries.

Known devices for the accumulation and storage of hydrogen, based on the binding of hydrogen in a solid material (for example, metal hydrides or sorption on the surface of dispersed nanomaterials), (RF patents No. 2037737, 2038525, IPC F 17 C 5/04), these devices for accumulation and hydrogen storage are the most explosion-proof of the existing ones, as hydrogen does not have excess pressure, but such systems are inertial and require a certain time (of the order of several minutes) to start operation, the absorption and evolution of hydrogen occurs with significant thermal effects, in addition, the mass content of hydrogen is the ratio of the weight of hydrogen in the battery to the weight of the battery itself - 4.5% - is very low. The mass content depends both on the amount of hydrogen in the storage material and on the specific gravity of the storage material.

Known capacity for storing hydrogen (patent No. 2222749, IPC F 17 C 5/04), which is a sealed casing with an inner vessel for storing liquefied hydrogen, while the gas filling system is designed to reduce hydrogen loss, reduce the time of filling the tank. This tank is designed for a hydrogen automobile (Schwartz A. Automobile of the future. J. Herald, No. 10 (347), pp. 1-5, 05/12/2004), it is made of durable composite relatively light materials. The last modification has a volume of 90 liters, a mass of 40 kg, a hydrogen pressure of 400 atm. Estimates show that in this case 3.2 kg of hydrogen can be stored in the tank, therefore, the mass content of hydrogen is 3.2 / 40 × 100% = 8%. The disadvantages of the tank are explosiveness and low hydrogen content per unit volume, up to 400 liters of hydrogen per liter, gas loss from the tank.

It is known that hydrogen can be stored in hollow microspheres made of glass with a diameter of 5-200 μm with a wall thickness of 0.5-5 μm (Malyshenko S.P., Nazarova O.V. Accumulation of hydrogen. In the collection of articles. "Atomic-hydrogen energy and technology ”, issue 8, pp. 155-205, 1988). At a temperature of 200-400 ° C under pressure, hydrogen, actively diffusing through the walls, fills the microspheres and after cooling remains in them under pressure. So, at a hydrogen pressure of 500 atmospheres and heating the microspheres to the indicated temperatures, a mass content of hydrogen in the microspheres of 5.5-6.0% was obtained. At lower pressures, the mass content of hydrogen in the microspheres will decrease. When heated to 200 ° C, about 55% of the hydrogen stored in the microspheres is released and about 75% when heated to 250 ° C. When storing hydrogen in glass microspheres, the diffusion loss through the walls is about 0.5% per day. In the case of coating microspheres with metal films, the diffusion losses of hydrogen at room temperature are reduced by 10-100 times. A significant drawback is that the charging of the battery with microspheres is carried out at relatively low hydrogen pressures, since the tensile strength of the glass has low values and is in the range up to 20 kg / mm ² . This does not allow to provide a mass content of hydrogen in microspheres significantly exceeding 6 wt.%.

Known capacity for storing and accumulating hydrogen, consisting of a sealed enclosure, process pipes, an internal heat exchange surface and a hydrogen filler-accumulator, which is an intermetallic powder (RF patent No. 2037737, IPC F 17 C 5/04 - prototype). The disadvantage of the invention is that the absorption and evolution of hydrogen occurs with significant thermal effects, in addition, the mass content of hydrogen - the ratio of the weight of hydrogen contained in the tank to the weight of the tank itself - 4.5% - is very low.

The technical result, which the invention is directed to, is the creation of a container for the safe storage and storage of hydrogen, providing an increase in the mass content of hydrogen above 6%.

For this purpose, a container for storing and storing hydrogen is proposed, consisting of a sealed housing, process pipes, a heater and a hydrogen storage filler-battery located in the housing, while the tank is divided by a proton-conducting material partition into an anode cavity filled with water with a porous anode located in it and a cathode cavity with a continuous cathode and heater located in it and filled with a hydrogen storage filler-accumulator made of a material with a tensile strength above 30 kg / m m ² and having a microporous structure.

In this case, the partition is made in the form of a proton conducting membrane.

In this case, the microporous structure is made of hollow microspheres.

In addition, the microporous structure is made of polymers of the aramid group. Also, the microporous structure can be made of foam metal, for example foam nickel, foam titanium.

In addition, the microporous structure is made of a material with proton-conducting properties.

The hydrogen content in the microporous structure is determined primarily by the strength characteristics of the material of this structure. For microporous structures for hydrogen storage and storage containers, high-strength materials with a tensile strength σ _bp above 30 kg / mm ² are suitable. Depending on the strength characteristics, what maximum hydrogen pressure can be created with a fixed pore size, since the same hydrogen pressure creates large stresses in large pores and, accordingly, lower voltage in small pores. By increasing the pore volume (and therefore their size), we obtain a higher hydrogen content per unit volume of the microporous structure, but the increase in pore size is limited by the magnitude of the ultimate stresses created by the hydrogen pressure in these pores. As a result, for each material, the maximum maximum pore size is determined by the strength characteristics of the microporous material. In addition, the microporous material should have significantly different hydrogen permeability characteristics under various conditions, for example, when the temperature changes, when exposed to ultrasound, high-frequency currents, when applying direct or alternating voltage, etc. The nature of the impact and its magnitude are determined by the requirements of the rate of hydrogen absorption by the microporous structure and / or the rate of hydrogen exit from it.

The simplest and actually created microporous structure is a structure created from hollow microspheres, primarily metals or their alloys, as well as a microporous structure from foam nickel, foam titanium, other foam metals and polymeric materials.

The microporous structure of hollow microspheres, for example of steel, is formed into a single rigid structure. This can be done by diffusion welding. Moreover, all the free space both inside the microspheres and between them will be filled with hydrogen.

Of exceptional interest in creating a porous microstructure are materials having high strength characteristics and low specific gravity, these are, first of all, composite carbon and polymer materials. Thus, polymers based on poly-p-phenylene terephthalamide and other similar aromatic polymers (aramids) have a specific gravity of 5.5 times less than steel, and strength characteristics are 2.5-3.5 times higher. For high strength steels of a tensile strength σ _Bp = 160-220 kg / mm ^2, for aramids tensile strength to 550 kg / mm ² (Table 1).

Table 1 Material grade (country) Density, kg / m ³ Tensile strength, kg / mm ² Armos (Russia) 1450 500-550 SVM (Russia) 1430 380-420 Thurlon (Russia) 1450 310 Kevlar 29 (USA) 1440 292 Kevlar 129 (USA) 1440 320 Twaron (Holland) 1440 280 Technora (Japan) 1390 300-340

Figure 1 shows a schematic diagram of a container for storing and storing hydrogen, where 1 is the container body, 2 is a porous electrode anode made of a first-kind conductor, 3 is a pipe for supplying water to the anode cavity, 4 is a pipe for oxygen removal from anode cavity, 5 - a partition made of proton-conducting material (membrane), 6 - microporous structure - a hydrogen accumulator, 7 - a solid electrode - a cathode made of a conductor of the first kind, 8 - a pipe for removing hydrogen from the tank to the engine (consumer), 9 - heater.

Figure 2 presents the microporous structure of microspheres, where 10 is a microsphere.

Figure 3 presents the microporous structure of a polymeric material - Armos, where 11 are fibers, 12 are pores.

The device operates as follows.

The sealed container body 1 is divided by a partition 5 into two cavities. The anode cavity is filled with water through the nozzle 3. Water enters the porous anode 2. At the boundary of the porous anode made, for example, of porous titanium and proton-conducting membrane 5, which can be made of ceramic, polymer or other material, the water oxidation reaction proceeds:

2H ₂ O + 2e ^- = O ₂ + 4H ⁺ .

Oxygen is released through the pores of the anode into the volume of water and is removed through the oxygen outlet 4. Hydrogen ions (protons) along the proton conducting membrane 5 move to the cathode 7, where they are reduced to hydrogen. Hydrogen does not pass through the solid metal cathode 7 and saturates the microporous structure 6. The cathode and proton conducting membrane form a cathode cavity filled with a porous microstructure 6. From this closed volume, when heated by the heater 9, it is directed through the pipe 8 to the consumer, for example, to the hydrogen supply system to the engine internal combustion or fuel cells. To accelerate hydrogen saturation, the microporous structure can have proton-conducting properties. The amount of hydrogen in the porous structure is determined by the magnitude of the charging current and charging time.

Compare the characteristics of the tank for storing and accumulating hydrogen with a microporous structure of hollow microspheres 10 (see figure 2) made of steel and Armos (see figure 3), where 11 are the fibers of the material. With the formation of pores 12, their shape can be very diverse from capillaries to spheres. Consider the option of spherical pores.

Table 2 presents a comparison of the characteristics of microporous structures made of steel microspheres and a microporous structure with the same pore size made of Armos. In the tables, σφ is the tangential stress on the shell of the microsphere, kg / mm ² , σ _R is the radial stress on the shell of the microsphere, kg / mm ² . The specific gravity of steel is 8 kg / l. The specific gravity of the armos is 1.45 kg / l.

table 2 Hydrogen saturation pressure, ati The ratio of the weight of N ₂ to the weight of the microstructure, wt.% The hydrogen content in the microstructure, l / l (g N ₂ / l) σφ-σ _R , kg / mm ² one 2 four 5 Microstructure with microspheres with a diameter of 200 microns, shell thickness of 1 micron. Shell weight per liter of microstructure volume: steel - 124.3 g / l, Armos - 22.53 g / l. Pore volume 0.98 L / L 200 14.1 78.1 196.8 (17.6) 100.5 300 21,2 117.2 295.3 (26.4) 150.75 400 28.3 156.2 393.8 (35.2) 201.0 1000 70.7 390.1 984.4 (87.9) 502.5

The microstructure of microspheres with a diameter of 100 μm, a shell thickness of 1 μm. Shell weight per liter of microstructure volume: from steel - 246.2 g / l, from armos - 44.6 g / l. Pore volume - 0.97 L / L 400 14.0 77.6 387.7 (34.6) 101.0 800 28.1 155.2 775.5 (69.2) 202.0 1000 35.1 193.9 969.2 (86.5) 252.5 2000 70.3 388.1 1938.5 (173.1) 505.0 The microstructure of microspheres with a diameter of 10 μm, a shell thickness of 1 μm. Shell weight per liter of microstructure volume: from steel - 1134.9 g / l, from armos - 205.7 g / l. Pore volume - 0.86 l / l 1000 6.7 171.7 858.1 (76.6) 27.5 10,000 67.5 372.5 8581.35 (766.2) 275.0 20000 135.0 744.9 17162.7 (1532.4) 550.0 The microstructure of microspheres with a diameter of 3 μm, a shell thickness of 1 μm. The weight of the shell per liter of the volume of the microstructure: from steel - 3992 g / l, from Armos - 723.6 g / l. Pore volume - 0.50 l / l 10,000 11.2 61.8 5010.0 (447.0) 100.0

As can be seen from table 2, for identical microporous structures with micropores with a diameter of 200 μm, the mass content of hydrogen in the microstructure is achieved for the best steels 28.3 wt.%, And for Armos 390 wt.%.

Example 1. A hydrogen storage tank is divided into two cavities by a high-temperature (up to 300 ° C) proton-conducting ceramic membrane. The cathode cavity with a volume of 0.028 liters is filled with a microporous structure of hollow microspheres made of high strength steel with a microsphere diameter of 200 and 80 μm, and a shell thickness of 1 μm. Microspheres are connected in a rigid nozzle by diffusion welding. The weight of 0.028 l of microporous structure is 3.5 g. An anode of porous titanium is washed with water. The microporous structure was charged at a current density of 1 A / cm ² . In 20 minutes, 7.2 liters of hydrogen passed into the microporous structure through the surface of the proton conducting membrane. When charging, the temperature of the microporous structure was maintained by a special heater at 280 ° C. The mass content of hydrogen was 18.4 wt.%.

Example 2. In the same device was loaded microporous structure based on a polymer - Armos, which is a polymer fiber with pore sizes of ~ 200 μm. Charging the microporous structure with hydrogen was also carried out for 20 minutes. Proton conducting polymer membrane - MF-4SK. The microporous structure absorbed 7.2 liters of hydrogen. The weight of the porous structure was 0.64 g. The mass content of hydrogen in the microstructure is 101%.

Such containers for storing and storing hydrogen have significant advantages over those that are charged with hydrogen at high pressure or using cryogenic technologies. They are not only safe, but have a very high degree of hydrogen saturation while maintaining small dimensions. They can be supplied not only by gas stations or special points of battery supply; these containers can be charged by consumers themselves (motorists), for this it is enough to pour clean water into the cavity with the anode and connect the tank to the network (power source).

Claims (6)

1. A hydrogen storage tank, consisting of a sealed housing, process pipes, a heater and a hydrogen storage filler-battery located in the housing, characterized in that the tank is divided by a proton-conducting material partition into an anode cavity filled with water, with a porous anode located therein, and a cathode cavity with a solid cathode and heater located therein, and filled with a hydrogen filler-accumulator made of a material with a tensile strength above 30 kg / mm ² and having a microporous th structure. 2. The container according to claim 1, characterized in that the filler-battery is made of hollow microspheres. 3. The container according to claim 1, characterized in that the filler-battery is made of polymers of the aramid group. 4. The container according to claim 1, characterized in that the filler-battery is made of foam metal, such as foam nickel, foam titanium. 5. The container according to claim 1, characterized in that the septum is made in the form of a proton conducting membrane. 6. The tank according to claim 1, characterized in that the filler-battery is made of a material with proton-conducting properties.

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