JP6059905B2 - Method for activating reactant in hydrogen generator - Google Patents

Description

  The present invention relates to a method for activating a reactant in a hydrogen generator for activating a reactant in a hydrogen generator using an alkali metal hydroxide as a reaction agent.

  Alkali metal hydroxide (NaOH, KOH) as a reactant is housed in a stainless steel reaction cell, which is heated to 500 ° C. or more to emit fine particles from the molten salt. The present inventor has already filed an application for a hydrogen generator that reacts with water and decomposes water to generate hydrogen.

International Publication WO2010 / 084790

  However, when the reactants in Patent Documents 1 and 2 are used for a long period of time, the reactants deteriorate and their ability decreases, so activation of the reactants is desired.

  Therefore, in the method of the present invention, an alkali metal hydroxide as a reactant is accommodated in a metal reaction cell, and the reaction cell is heated to a temperature higher than the melting point of the reactant to make the reactant a molten salt. An activation method for activating a reactant in a hydrogen generator in which fine particles are scattered and water is decomposed by reacting the fine particles with water vapor supplied into the reaction cell in a metal element atmosphere. In this case, when deterioration of the reactant is detected, a large amount of high-concentration alkali metal oxide aqueous solution is supplied into the reaction cell through a water supply system for supplying water into the reaction cell, and heating is continued to generate steam. When it disappeared, it returned to normal operation.

  Moreover, it is preferable to carry out the activation method when the peak of activity of the reactant is slightly exceeded. Furthermore, the alkali metal hydroxide is preferably sodium hydroxide (NaOH) or potassium hydroxide (KOH), and the metal is preferably stainless steel or iron.

  Further, in the second method of the present invention, an alkali metal hydroxide as a reactant is housed in a metal reaction cell, the reaction cell is heated to a temperature higher than the melting point of the reactant, and the reactant is converted into a molten salt. For activating the reactants of the hydrogen generator, in which fine particles are scattered from the surface, and the fine particles and water vapor supplied to the reaction cell are reacted in a metal element atmosphere to decompose water. In the activation method, when deterioration of the reactant is detected, water vapor is discharged from the reaction cell through a hydrogen discharge system that discharges hydrogen generated in the reaction cell, and then hydrogen is supplied into the reaction cell. The internal pressure was raised to a positive pressure and maintained for a predetermined time.

  Furthermore, it is preferable that the hydrogen is supplied into the reaction cell so that the reaction cell has a pressure of 4 atmospheres or more, and the state is maintained for one day or more.

  In the first invention, when the activity peak of the reactant is slightly passed (deterioration initial stage), a high concentration (over 50%) sodium hydroxide aqueous solution or potassium hydroxide aqueous solution is passed through the water supply system to the reaction cell. If added to the reactant, sodium ions or potassium ions are added to the reactant, and the function of the oxide having a special function generated after the reaction can be maintained.

  In the second invention, in the early stage of deterioration, if high-pressure hydrogen is fed into the reaction cell, the oxide that does not contribute to the decomposition of water or the oxide after the reaction after excessive oxidation is reduced and reacted. Revive the function of the agent. Further, if the hydrogen as the reducing material is maintained at least once at a high pressure of 4 atm or more, the reducing action can be sufficiently performed.

It is a schematic block diagram of the hydrogen generator for implementing the 1st, 2nd invention which concerns on this invention. It is principal part explanatory drawing of the apparatus for implementing 1st invention of this invention. It is a longitudinal cross-sectional view of the reaction cell which shows the state of the oxide after reaction. It is a figure which shows the processing method which discharges a reactive agent from a reaction cell after a reactive agent complete deterioration. It is a figure which shows the washing | cleaning method in the reaction cell after the process shown in FIG. It is a graph which shows the deterioration state of a reactive agent.

  Embodiments of the present invention will be described below with reference to the drawings.

  In FIG. 1, a hydrogen generator M according to the present invention has a cylindrical reaction cell 1 made of stainless steel (especially, SUS304 of Cr18% -Ni8% -residual Fe is preferable, but iron may be used). Inside, a bowl-shaped reactant receiver 2 (FIG. 2) is accommodated, and a reactant 3 is accommodated therein. As the reactant, sodium hydroxide (NaOH) or potassium hydroxide (KOH) is used. A water pipe 4 for supplying water is provided on the upper surface of one side of the reaction cell 1, and a hydrogen discharge pipe 5 for discharging generated hydrogen is provided on the upper surface of the other side.

The water tube 4 forms part of a water supply system S _1, the water supply system S ₁ is provided with a water tank 6, and a flow control valve 7 for adjusting the amount of water supplied from here, the water supply system the S _1, an aqueous solution supply line S ₂ for supplying a high concentration alkali metal oxides aqueous (aqueous sodium hydroxide solution or potassium hydroxide solution) into the reaction cell 1 are connected. This system path S ₂ has an aqueous solution tank 8 and an on-off valve 9. Furthermore, the hydrogen discharge pipe 5 forms part of the discharge system S _3, the discharge system S ₃ is closed and the vacuum pump 11 to maintain a constant vacuum state reaction cell 1 and switching valve 10, a flow meter 12 A hydrogen supply system S ₄ is connected to the switching valve, and the hydrogen supply system S ₄ includes a hydrogen cylinder 13.

  The reaction cell 1 is heated to a melting temperature of the reactant (300 ° C. or higher) by a heating device (not shown), and is preferably 500 ° C. to 600 ° C., and may be electric heating or gas heating. The reaction cell 1 is preferably provided with height adjustment legs 14 and 14 for making the water supply side slightly higher than the hydrogen discharge side. The reaction cell 1 is supported by a sliding mechanism 15 for sliding the reaction cell 1 to swing back and forth in the axial direction.

  As shown in FIG. 2, the bowl-shaped reactant receiver 2 provided in the reaction cell 1 is closed at its front and rear ends by an end plate 2 a, in which the reactant 3 is accommodated. When heated to ˜600 ° C., it becomes a molten salt, and the fine particles P are scattered from the liquid surface. The fine particles P react with the supplied water vapor to decompose water and generate hydrogen.

  A water receiver 16 is located directly below the water pipe 4, and the alkali metal aqueous solution is guided into the reactant receiver 2 by the water receiver 16. Normally, water hits the water receiver 16 and becomes water vapor. Flows into the reaction space filled with fine particles P.

  Next, the operation of the first invention of the present invention will be described.

  For example, when sodium hydroxide is used as a reactant, the fine particles P of NaOH react with water vapor in a stainless steel atmosphere, but when stainless steel is SUS304, it reacts mainly with iron components and is not actively active with Cr. Ni does not react, and Ni acts as a catalyst during the reaction.

Was it in, mainly _{2Fe + 2NaOH + 2H 2 O →} 2NaFeO 2 + 3H 2
As a result of this reaction, a film of sodium ferrate (NaFeO ₂ ) is formed on the inner wall of the stainless steel (reactant receptacle 2 and inner wall of the reaction cell 1), and this film further reacts with iron (Fe) and water vapor,
_{3NaFeO 2 + 2Fe + 3H 2 O} → Na 3 Fe 5 O 9 + 3H 2
Higher order sodium ferrate (Na ₃ Fe ₅ O ₉ ) is produced. In addition to this main reaction, in this reaction process, oxides such as FeO, Fe ₂ O ₃ , Fe ₃ O _{4 and the} like are generated, and these oxides are converted into the NaFeO ₂ , Na ₃ Fe ₅ O ₉ (functional oxides). If the surface is covered, the reaction agent deteriorates and the ability to decompose water decreases. Also, as the reaction proceeds, the NaOH component decreases, so the surface of the functional oxide is cleaned and at the same time the water supply is stopped to replenish the NaOH component. A large amount is poured into the reactant receiver 2 of the reaction cell 1.
Then, the operation is terminated when the heating is continued and almost no water vapor is generated.

  For example, NaOH and KOH can make an aqueous solution of 50% or more depending on the temperature. When the initial amount of the reactant is 25 mol, 500 g or more of the aqueous solution is poured. In the case of NaOH aqueous solution, 6 mol or more of NaOH is replenished, and the surface of the functional oxide is washed with sufficient water, and the activity of the functional oxide film is increased.

In addition, the aqueous solution is sent to the entire reactant receiver 2 on average by the operation of the sliding mechanism 15. This state is shown in FIG. 6. When the value of the flow meter 12 fluctuates for a constant water supply, passes through the first peak m ₁ after operation, and the hydrogen generation amount decreases, the aqueous solution cleaning is performed. (Also serves as NaOH replenishment), and when the second peak m ₂ has passed, the same operation is performed and this operation is repeated several times. This operation needs to be performed at least once before the theoretical value in the reaction is reached.

  When several days have elapsed after the operation of the hydrogen generator M is started, a large number of higher-order iron oxide films 1 are generated in the reaction cell 1 as shown in FIG. 3 to narrow the reaction space in the cell. Therefore, at the end of the operation of the apparatus, as shown in FIG. 4, the front and rear ends of the reaction cell 1 are detachably closed with an opening / closing lid, the water receiver 16 is removed, and the pusher 21 is pushed into the reaction cell 1. It is possible to assemble the reaction cell 1 again by removing the high-order iron oxide film 1 together with the reactant receiver 2 and then washing the inner wall of the cell with the superheated steam spray nozzle 22 as shown in FIG. The superheated steam is generated by the high frequency induction superheater 23.

  Next, the operation of the second invention of the present invention will be described.

In the first invention and the same timing, the hydrogen supply system S ₄ is activated. That is, after the water supply is stopped and the water vapor in the reaction cell is discharged, the switching valve 10 is switched, and high-pressure hydrogen from the hydrogen cylinder 13 is sent into the reaction cell 1. During normal operation, the reaction cell 1 is maintained at −0.6 to 0.3 atm. In this state, high-pressure hydrogen is sent into the reaction cell 1 so that the pressure becomes positive (1 atm or higher). To be. Preferably, it is maintained at 4 atmospheres or more for 1 day (24 hours) or more. As a result, oxides such as FeO, Fe ₂ O ₃ , and Fe ₃ O ₄ that do not contribute to the reaction are reduced and removed, and the function as a reactant is restored.

DESCRIPTION OF SYMBOLS 1 ... Reaction cell 2 ... Reactant receiver 3 ... Reactant 12 ... Flow meter 16 ... Water receiver

Claims (4)

An alkali metal hydroxide as a reactant is housed in a reaction cell made of iron or stainless steel, and the reaction cell is heated to a temperature higher than the melting point of the reactant to make the reactant a molten salt, and fine particles are scattered from the surface. In the activation method for activating the reactants of the hydrogen generator in which the fine particles and the water vapor supplied into the reaction cell are reacted in an iron or stainless steel atmosphere to decompose the water. , when detecting the deterioration of the reactants, oxidation with a high concentration alkali metal hydrosulfide oxide solution through the water supply system for supplying water to the reaction cell was supplied into large quantities reaction cell is formed in a reaction cell A method for activating a reactant in a hydrogen generator, wherein heating is continued while purifying the membrane, and when the generation of water vapor ceases, the normal operation is restored. The method for activating a reactant in a hydrogen generator according to claim 1 , wherein the activation method is performed when a peak of the activity of the reactant is slightly exceeded. Wherein the alkali metal hydroxide, a method of activating reagent of the hydrogen generating apparatus 請 Motomeko 1, wherein consisting of sodium hydroxide (NaOH) or potassium hydroxide (KOH). The method for activating a reactant in a hydrogen generator according to claim 1, wherein the concentration of the alkali metal hydroxide aqueous solution is 50% or more.

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