FI79401B - METALLHYDRIDREAKTOR. - Google Patents

Description

1 79401

METAL HYDRAULIC REACTOR - METAL HYDRAULIC REACTOR

The invention relates to a metal hydride reactor as defined in the preamble of claim 1.

The metal hydride technique is based on a reversible reaction between hydrogen and metal in which either a metal hydride is formed or the metal hydride decomposes into its starting materials depending on whether heat is removed from the reaction or heat is introduced into it. The formation of the metal hydride is shown in the formula:

Me + Ha <=> Me hydride + heat, where Me is a metal or alloy, This reaction is used in a metal hydride reactor. When a reactor containing a metal powder, which may be pure metal or a mixture of two or more metals or intermetallic compounds, is cooled and hydrogen is introduced, hydrogen is stored in the reactor in the form of a metal hydride. When the reactor is heated, the metal hydride decomposes and the hydrogen gas released can be led from the reactor to the desired application. Hydrogen storage and unloading can be performed in a controlled manner by heating and cooling. In addition, a reactor in which hydrogen is stored in a metal hydride acts as a depressurized hydrogen reservoir, so that using the reactor as a form of hydrogen storage, for example, is considerably safer than e.g. a hydrogen gas cylinder in which hydrogen-30 gas is pressed under pressure.

The roetallohydride reactors currently in use are closed reaction vessels surrounded by a cooling / heating jacket which acts as a heat exchanger element. Attached to the inner wall of the reactors are flanged partition walls, e.g., aluminum plates, which divide the reaction vessel into compartments. Partitions conduct heat. A gas pipe 2 79401 is arranged in the middle of the reactor to penetrate the reactor and out of the reactor through the partitions. The gas pipe is porous in the part inside the reaction vessel. The compartments bounded by the partitions are filled with metal hydride powder.

5 The problem with current metal hydride reactors is the poor distribution of hydrogen in the reactor, as the compartments delimited by the partitions are substantially isolated from each other. The hydrogen introduced into the reactor in each compartment slowly travels from the central part of the reactor to the Takalo part of the compartment, i.e. in the vicinity of the outer walls of the reactor. Hydrogen released from the metal hydride also travels slowly from the rear of the compartments towards the gas pipeline in the center of the reactor. Hydrogen from the gas pipeline can also be unevenly distributed between different compartments.

15 Further, heat transfer in the reactor poses problems. The cooling / heating jacket surrounding the reactor cools and heats the metal powder in the vicinity of the reactor wall faster and more efficiently than the metal powder in the central parts of the reactor. Efforts have been made to improve heat transfer by means of heat-conducting partitions, but these are not sufficient to eliminate the significant temperature differences in the reactor.

Poor hydrogen distribution and insufficient heat transfer affect the metal hydride reaction by slowing down the rate of the reaction, thereby slowing the binding of hydrogen to the reactor and the release of hydrogen from the reactor.-A slow-running reactor limits many applications.

It is an object of the present invention to obviate the above drawbacks. In particular, it is an object of the invention to provide a novel metal hydride reactor in which the distribution of hydrogen in the reactor is even more unobstructed, whereby the metal hydride reaction can take place rapidly throughout the reactor.

It is a further object of the present invention to provide a metal hydride reactor in which the heat transfer of the reactor is more efficient and faster.

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It is a further object of the present invention to provide a metal hydride reactor in which the charging and discharging of the reactor can be performed quickly and economically.

Reference is made to the claims for features which characterize the invention.

The metal hydride reactor according to the invention consists of a closed reaction vessel comprising a gas tube for introducing hydrogen into and out of the reactor, a heat exchanger element for cooling and heating the reactor, According to the idea of the invention, the partitions are provided with hydrogen-permeable pores, through which hydrogen can pass from one compartment to another when hydrogen is introduced into and out of the reactor. In the metal hydride-20 reactor according to the invention, the hydrogen introduced from the gas pipe to the reactor spreads in the reactor from its central part, i. in the vicinity of the gas pipe, to each compartment and in each compartment towards the wall of the reaction vessel. In addition, hydrogen can move through the pores of the partitions from one compartment to another, allowing the hydrogen to be distributed rapidly and evenly in the reactor. Thanks to the good distribution, the hydrogen is able to react quickly with the metal powder throughout the reactor, so that the hydrogen can be stored in the reactor in a shorter time than before.

Preferably, the partitions are arranged transversely in the reactor so that a gas pipe in the middle of the reactor, substantially the length of the reactor vessel, pierces the partitions. The partitions are connected to a heat exchanger element.

Preferably, the partitions consist of copper sinter with a suitable pore size, but other types of porous partitions can also be used.

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The part of the gas pipe inside the reaction vessel can be porous in a manner known per se.

Preferably, the pore size of the partitions is larger than the pore size of the gas pipe.

5 One pure metal or a mixture of different metals can be used as the metal powder, for example FeTi or LaNis powder or some other metal or similar powder used in hydride reactors. The metal powder is selected on the basis of the desired application and / or the desired operating temperature range.

The heat exchanger element can be a cooling / heating jacket, which is equipped with, for example, a water circuit.

Preferably, the heat exchanger element consists of a heat exchanger-15 tube located inside the reaction vessel. In this case, the partitions can be attached to the heat exchanger tube. The reaction vessel may also have several heat exchanger tubes. In addition, the reaction vessel may be surrounded by a cooling / heating jacket.

A heat-20 exchanger tube placed inside the reaction vessel improves the heat transfer of the reactor, thereby further accelerating the reaction between the metal powder and hydrogen.

Good hydrogen distribution and efficient heat transfer accelerate the reaction in the reactor, allowing large amounts of hydrogen to be stored in the reactor in a short time and hydrogen to be discharged out of the reactor quickly.

The hydrogen gas discharged from the reactor is very pure, e.g. more than 99.99999% pure, because the metal-30 powder reacts selectively with hydrogen.

When the hydrogen stored in the metal hydride reactor according to the invention has been used up, the reactor can be recharged.

Because the pressure in the reactor can be less than 10 bar, the reactor is very safe and can be used for various hydrogen technology applications. The reactor can be operated at a stationary 5,79401 site or a mobile site. The reactor can be used to replace, for example, hydrogen gas cylinders or hydrogen containers used in various laboratory applications, processes, various hydrogen gas-powered drives and / or hydrogen gas purification. The hydrogen gas released in the industrial process can also be recovered in the metal hydride reactor according to the invention, in which the gas can be purified at the same time and from which the hydrogen can be reused in various applications. The invention will now be described in detail with reference to the accompanying drawings, with reference to the accompanying drawings, in which Figure 1 shows a longitudinal section of a metal hydride reactor according to the invention, and Figure 2 shows a cross-section of the reactor of Figure 1.

Figure 1 shows a metal hydride reactor according to the invention, consisting of a closed reaction vessel 1. The reaction vessel comprises a gas pipe 2, a heat exchanger element 3, partitions 4 dividing 20 reaction vessels into compartments 5, and a metal powder 6 placed in the compartments.

Steel, for example, can be used as the material of the reaction vessel 1.

In the embodiment shown, the gas pipe 2 is substantially the length of a cylindrical reaction vessel 1 and is arranged on the longitudinal axis of the reaction vessel. The gas pipe is porous in the part inside the reactor vessel. The material of the gas pipe can be, for example, sintered steel. Other types of gas pipes 30 can also be used.

In the metal hydride reactor according to the invention, the heat exchanger element 3 consists of two heat exchanger tubes 9 placed inside the reaction vessel 1, on either side of the gas tube 2 (only one of the successive heat exchanger tubes is shown in the figure). The heat exchanger tubes are also mainly the length of the reaction vessel and are U-shaped so that the tubes 6 79401 can be connected to e.g. a water circulation system. Copper, for example, can be used as the pipe material. If necessary, the reaction vessel can still be surrounded by a cooling / heating jacket.

5 Other types of heat exchanger elements can also be used in metal hydride reactors. In this case, e.g. Cooling can be provided by various circulation systems in which, for example, cold liquids or liquid mixtures of the desired degree are circulated.

The thermally conductive partitions 4 are provided with 15 pores permeable to hydrogen. The partitions are arranged transversely in the elongate reactor vessel 1 so that the partitions are pierced by the gas pipe 2 and the heat exchanger pipes 9. The partitions are attached to the heat exchanger tubes, whereby they, as highly heat conducting, improve the heat transfer in the reactor. Copper sinter, for example, can be used as the material for the partitions. Preferably, the pore size of the partitions is larger than the pore size of the gas pipe. The pore size of the partitions is e.g. of the order of 1 x 10 ~ e - 10 x 10_e m.

The partitions 4 divide the reaction vessel 1 into several compartments 5 filled with metal powder 6. As the metal powder, a suitable metal or alloy, e.g. FeTi or LaNie flour, can be used. The metal powder is selected according to the application and the available cooling / heating temperature range. The particle size of the metal powder is preferably larger than the pore size of the gas pipe and the partitions.

The reaction vessel 1 is further surrounded by a jacket 10. In the application shown, a vacuum is sucked into the space 35 delimited by the jacket and the outer wall 11 of the reaction vessel. The vacuum isolates the reaction vessel from the environment.

Figure 2 shows a cross-section of the metal 797011 hydride reactor according to Figure 1.

The reaction vessel 1 is surrounded by a jacket 10. The heat exchanger tubes 9 and 9 'are arranged around the gas tube 2.

When the metal hydride reactor 5 according to Figures 1 and 2 is charged, hydrogen is introduced from the gas pipe 2 to the reactor while cooling the reactor. Cooling is carried out, for example, with water exchange heat exchanger pipes, which can be connected to a normal water supply network, for example. From the pores of the gas pipe, hydrogen travels to the compartments 5 delimited by the partitions 10. As it travels, hydrogen at the same time reacts with the metal powder placed in the compartments to form metal hydride 7. The charging pressure of hydrogen 15 can be kept low, even below 1 bar. Approximately 10 l (50 kg) of metal hydride can be stored in approx. 10 m3 of hydrogen gas. (Correspondingly, when pressing the same amount of hydrogen at a pressure of 200 bar into a conventional gas cylinder, the volume of the gas cylinder must be 50 1 (70 - 80 kg)).

20 When stored hydrogen is introduced, the metal hydride reactor is heated, whereby, thanks to the heat exchanger tubes inside the reactor and the heat transfer partitions connected to the heat exchanger tubes, the metal hydride heats up rapidly and hydrogen 25 discharges from the metal hydride and passes through the compartments.

The metal hydride reactor according to the invention can be charged and discharged several thousand times.

The application examples are intended only to illustrate the invention without limiting it in any way.

Claims (3)

8 79401 A metal hydride reactor consisting of a closed reaction vessel (1) comprising a gas pipe 5 (2) for introducing hydrogen into and out of the reactor, which gas pipe (2) is porous in the part inside the reaction vessel (1) and substantially the length of the reaction vessel (1); a heat exchanger element (3) for cooling and heating the reactor, which heat exchanger element (3) is formed by heat exchanger tubes (9) arranged inside the reaction vessel (1), which are substantially the length of the reaction vessel; thermally conductive partitions (4), which partitions (4) are arranged in the reaction vessel (1) so as to be pierced by the gas pipe (2) 15 and the heat exchange pipes (9) and divide the reaction vessel into compartments (5); and a metal powder (6) placed in the compartments and, on cooling the reactor, together with the hydrogen introduced into the reactor, forms a metal hydride (7), which decomposes again when heated to 20 reactants, characterized in that the partitions (4) is provided with hydrogen-permeable and metal powder-retaining pores through which hydrogen can pass from the gas pipe (2) to the compartments (5) and from the compartment (5) to another when hydrogen is introduced into and out of the reactor. Metal hydride reactor according to Claim 1, characterized in that the partitions consist of copper sinter (8). Metal hydride reactor according to Claim 1 or 2, characterized in that the partitions (4) are provided with pores larger than those of the gas pipe (2).