The catalytic element (options)

 

The invention relates to a catalytic element for recombination of hydrogen and/or carbon monoxide with oxygen for nuclear power plants. Described catalytic element (1) for recombination of hydrogen and/or carbon monoxide with oxygen containing body (2) of the catalyst with the catalytic surface (4), the operation of which is particularly reliably prevented spontaneous ignition of the gas mixture contains according to the invention deposited on a catalytic surface (4) and/or on the body (2) of the throttle catalyst layer (10,10 A-10D) for inhibition of diffusion nakaumi and/or a water gas reaction, in particular for nuclear power plants. Technical result: the catalytic element can be reliably prevent unintentional ignition of the gas mixture in the atmosphere of the containment of nuclear power plants. 2 C. and 15 C.p. f-crystals, 5 Il.

The invention relates to the catalytic element (options) for the recombination of hydrogen and/or carbon monoxide with oxygen, containing a catalyst body with a catalytic surface, in particular, for nuclear power plants (NPPs).

A similar theme is considered in the simultaneously filed application entitled "Recombination accident loss of coolant in nuclear power plants in containment (Containment) may release large quantities of hydrogen and carbon monoxide. Without response, the hydrogen can be rich in the atmosphere of the containment so that may form explosive mixture. In case of accidental ignition, primarily due to the combustion of large amounts of hydrogen may invalidate the integrity of the containment.

To avoid such explosive gas mixtures in the containment are considered different devices. These include, for example, devices such as catalytic recombiners, catalytic or electric igniting device or a combination of both these devices.

For removing hydrogen and carbon monoxide from the atmosphere of a protective casing, it is necessary to first achieve timely and flameless recombination of hydrogen and/or carbon monoxide with oxygen. Thus it is necessary to reliably avoid a noticeable increase in pressure due to the virulent combustion of hydrogen. Suitable for this pre-trigger recombination device that even with a long lifetime in the atmosphere of the containment does not significantly lose its activity and passively triggered by low ambient temperatures, it is known from DE 19636557. Using such recombination the R and therefore protected from spontaneous ignition.

From EP 0527968 B1 is known recombination device, which provided a certain number of catalytic systems in the form of flat plates, coated on both sides with a catalyst material such as platinum and/or palladium. This device is particularly well suited to reduce the amount of hydrogen in the containment atmosphere of a nuclear power plant. Each catalytic system includes while carrying the sheet of stainless steel, having both sides of the thin layer, in particular platinum and/or palladium, the thickness of which lies in the micrometer range. Many such covered individual plates is located in the housing, which may be in the form module. The body is flown from the bottom to the controlled gas flow and the gas flow leaves the body in the upper part through the side outlet.

From EP 0436942 A1 it is known recombination device to protect the body, which spontaneously opens, depending on the external temperature. In this state of readiness recombination system protection device housing, in contrast, is closed, which prevents contamination of the catalytically active surface of recombinator.

Have known from EP 0416140 A1 recombinational atmosphere, for example, aerosols, and, thereby, protect the recombination catalyst device from contamination.

Further, from DE 3725290 known alloys of noble metals, which through a supporting plate or a metal mesh absorb or divert occurs when recombination heat of reaction, which should prevent the ignition of the gas mixture. From EP 0388955 A1 it is known recombination device, which are additionally provided with an igniting device for the controlled combustion of hydrogen.

Each known recombinatory system especially designed for high performance recombination with particularly small dimensions of the components, and high resistance to contamination. To use the device for the recombination of hydrogen in the gas mixture at nuclear power plants should, in addition, to ensure that the occurrence of effects that can adversely affect the safety of nuclear power plants. Note that used for hydrogen recombination catalytic element (catalyst device) due to recombination is usually heated and due to its elevated temperature may be involuntary to facilitate the ignition of the gas mixture in the atmosphere of the containment of nuclear power plants. and/or carbon monoxide with oxygen in the gas mixture, in particular, in the atmosphere of the containment of nuclear power plants, which work particularly reliably prevented spontaneous ignition of the gas mixture.

This problem is solved in a catalytic element comprising a body of catalyst with the catalytic surface, according to the invention due to the fact that caused on the catalytic surface and/or on the body of the throttle catalyst layer is provided for braking diffusion nakaumi and/or a water gas reaction. The invention proceeds from the fact that spontaneous ignition of the gas mixture in the environment of the catalytic element can be made at the expense of increased reaction temperature on the catalytic element, so that the result can be caused by a fire that occurred during recombination and out of the catalytic element in the surrounding space. In order reliably to avoid this, the catalytic element must be designed so that the reaction temperature was below the ignition temperature of the gas mixture. It should be ensured, in particular, for such a gaseous mixture, the content of N2which is more than 8 vol.%. This also provides a braking diffusely, thanks are only dynamic adsorption reaction gases, thereby limiting catalytic reaction a small partial quantity per unit area. This, in turn, leads preferably to the limit of the reaction temperature, thereby the ignition temperature of the gas mixture remains unavailable. In addition, in the event vysokozaraznoy atmosphere occur particularly strong retention and sorption resulting catalytic poisons, such as aerosols, due to which the catalytically active surface of the catalyst body is protected from contamination.

It is advisable throttle layer is made porous with an average pore diameter of at least 5mainly, at least 100and at most 10000. When this throttle or porous layer has predominantly, in particular in the area of the leakage of the gas mixture, the so-called macropores average diameter of up to 10000. This provides a particularly good supply and/or exhaust gases of the reaction. Lower and thus closer to the body of catalyst plane throttle sloo, at least 100. Due to this, created a diffusion barrier for gases of the reaction. In working or non-working condition of the catalytic element may occur in addition, the separation of the particles of the body of catalyst. Due to malabaristas throttle layer is particularly reliably prevented removal of the so-called "stray" hot catalyst particles, which can also contribute to the inflammation surrounding the body of catalyst gas mixture.

The preferred way orifice layer has a pore volume of at least 0.1 cm3/g and at most 1 cm3/, Especially suitable Washcoat (Al2O3with particularly small pore volume. This achieves a particularly effective diffusion barrier with a large surface. It also allows the detention of catalytic poisons.

Mainly orifice layer has a thickness of at least 10 μm and at most 1 mm In a particularly preferred implementation of the throttling layer is in the direction of flow of the gas mixture varying the thickness and/or varying the diameter of pores. In this case, in particular in the area of the flowing gas mixture at normal flow rates of 0.1-2 m/s butterfly layer deposited persons who runoff higher dynamic adsorption with less leakage and runoff of reaction gases, due to which the catalytic reaction is choked. In addition, achieved a particularly strong detention catalytic poisons. Preferably the thickness of the orifice layer varies in the direction of flow of the gas mixture along the body of the catalyst. Alternatively and/or additionally, the throttling layer in the direction of flow of the gas mixture through the throttling layer may have a varying diameter of pores.

Mainly throttle layer is made of ceramic. Ceramic butterfly layer it is reasonable porous and has a thickness of at most 500 μm. Preferably ceramic butterfly layer contains aluminum oxide if the silicon oxide. Alternatively, it may also be another oxide ceramic material such as zirconium oxide, titanium dioxide, or mixtures, such as cordierite, mullite, zeolites, etc.,

According to a preferred variant provides that the throttle layer is made of mineral. Mineral throttle layer is preferably porous and has a thickness of at least 1 mm, Particularly preferably mineral throttle layer is made of mineral filling, in particular from filling basalt crushed, with an average size of zere is and absorption.

In another particularly preferred execution throttle layer is made of metal. Metal butterfly layer has an average pore diameter of preferably at most 50 μm. Mostly metal throttle permeable layer contains a metal foil. Metal butterfly layer may be one layer or multi - layer.

To equalize the temperature and, thereby, avoid local centres with high reaction rate and reaction temperature butterfly layer contains a suitable metal or ceramic fibers. While the fibers are preferably in the form of a grid and have a diameter predominantly at most 1 mm, and the average distance between them at most 2 mm, for Example, the throttling layer may be in the form of a single layer of the sieve sheet or multi-layer sieve or fiber device. In particular, due to the position of a metal or ceramic lattices in porous or poured throttle layer is achieved a particularly high impact strength and abrasion resistance to prevent catalytic abrasion of the catalyst body.

Various throttle layers can be Aligator as varnish, it provides a particularly accurate calculation of the thickness of the orifice layer. Alternatively, the throttling layer can be applied by immersion of the body of catalyst or a brush, or gluing.

Preferably the catalyst body contains supporting plate, in particular made of stainless special steel. This supporting plate has a thickness of less than or equal to 0.2 mm alternatively, the catalyst body has a flat plate, perforated plate or bowl as a mechanical holder. Depending on the function and type of catalytic recombination mechanical holder can be made of metal or ceramic.

For a particularly effective recombination contained in the gas mixture of hydrogen catalytic surface contains a catalytic noble metal, particularly platinum or palladium. Preferably the catalytic surface is formed of a catalytically active material, for example platinum, palladium or copper deposited on a mechanical holder with an adhesive layer and/or the intermediate layer. Platinum is particularly temperature stable and resistant to catalytic poisons. In addition, platinum as katalogen, in particular, because of its catalytic property is already apparent under very low ambient temperatures.

Device for catalytic element with the body of the catalyst with the catalytic surface and deposited throttle layer preferably carried out in separate layers in the form of so-called design "sandwich". When individual layers are held together by clamps or u-shaped sheet. Clamp or sheet covers while the corresponding end of the catalytic element, which accounts for the catalytic layers of the element are held particularly securely. The retention of the catalytic element can occur, for example, in the sieve basket or Dignam block. It provided a particularly simple installation in the recombination device containing a large number of catalytic elements.

According to another preferred implementation, at least in the zone of penetration provided by Teflon throttle layer. The ability of early operation, in particular in humid environmental conditions, may result due to such a locally limited Teflon coating to create the temporary hydrophobic properties of the body, catalepsia water inside the porous or butterfly layer and, thus, to improve the ability of early activation (passive initiation of the reaction).

Achieved thanks to the advantages of the invention consist, in particular, that for the expense incurred on the catalytic surface of the orifice layer with appropriate thickness or diameter of the pores provided catalytic recombination of hydrogen with oxygen in it the atmosphere, i.e., when the content of H2in the gas mixture of about 15 vol.%, without initiation of ignition. This is achieved, in particular, due to the diffusion properties throttle layer as a diffusion barrier for gases of the reaction causes the throttling catalytic reaction. Catalytic abrasion or split reliably prevented due to deposited on the catalytic surface layer throttle, as the throttle layer as a protective layer covers the catalytically active material. This is due, in particular, good thermal conductivity and high hardness throttle the layer that forms the outer layer of the catalytic element. In addition to inhibition of diffusion through the diffusion layer is securely prevented the spread of flame, perhaps worrying about 0.3 mm is achieved in a particularly reliable effect flaming barrier.

Examples of carrying out the invention are explained in more detail using the drawings, which depict:

- Fig.1 - catalytic element for recombination of hydrogen in the gas mixture with the throttle layer;

- Fig.2-4 - fragment I of Fig.1 with four alternative executions throttle layer.

The same parts are marked in all figures the same reference position.

The catalytic element 1 in Fig.1 is designed for recombination of hydrogen and/or carbon monoxide with oxygen in the gas mixture, namely in the atmosphere of the containment not shown in detail recombination device NPP in case of an accident. The catalytic element 1 contains for this purpose, the body 2 of the catalyst with the catalytic surface 4. As the body 2 of the catalyst is, for example, a supporting plate, in particular a sheet of stainless special steel. Alternatively, the body 2 of the catalyst may include mechanical holder flat plate, perforated plate, a bowl or a filling in the plate of the supporting structure, and a mechanical holder is made of metal or ceramic.

The catalytic surface 4 formed in this catalytic material 8, nanseni body 2 of the catalyst. The intermediate layer 6 made, for example, mineral, in particular, the intermediate layer 6 contains Washcoat (Al2About3), in which the catalytic material 8 is located directly on the surface 4. The catalytic surface 4 comprises a catalytically active material 8 catalytic noble metal or mixture of noble metals, or device from the foil a noble metal. As the noble metal is provided, in particular, platinum or palladium.

In addition, the catalytic surface 4 throttle applied layer 10 for braking nakaumi and/or a water gas reactions, such as H2O2, CO, CO2N2O. throttle layer 10 is made porous. The diameter of pores is in the area And the leakage orifice layer 10 and, thereby, directly in the external zone of the catalytic element 1 at most 10000. These are located in the outer area of the pores so called macropores. Underlying the plane of the orifice layer 10 located in the immediate vicinity of the body 2 of the catalyst, in particular in the area of the catalytic surface 4 have a smaller pore diameter of at least 5pre the pores and cause especially inhibiting the diffusion property throttle layer 10.

Depending on the achieved properties braking diffusion orifice layer 10 may be changing in the direction of flow of the gas mixture along the body 2 of the catalyst thickness and/or changing the direction of flow of the gas mixture through the throttling layer 10, the diameter of pores. The pore volume of the throttle layer 10 is at least 0.1 cm3/g and at most 1 cm3/,

For a reliable hold partially in the form of a layer of catalytic components item 1 - supporting sheet 2, the catalytic surface 4, the intermediate layer 6, the throttling layer 10 respectively on the upper and lower ends of the catalytic element 1 is set in the latch 11. As the latch 11 is, for example, a clamp or u-shaped sheet.

In order to avoid important for the reaction of adsorption of water inside the throttle layer 10 of the latter, at least in the zone of penetration, i.e. at the lower end of the catalytic element 1, is surrounded by predominantly permeable layer 12 hydrophobic. As layer 12 hydrophobic serves, in particular, Teflon coating or other substance is hydrophobic.

In Fig.2 depicts a fragment I of Fig.1 catalytic element 1 with an alternative throttle , throttle layer 10A especially porous and has a thickness of at most 500 μm.

In Fig.3 shows another alternative form of the orifice layer 10V catalytic element 1. Butterfly layer 10B is also a ceramic layer, which is located in the grid 13. The grid 13 is made of metal or ceramic fibers, for example of fabric made of special steel or fiberglass cloth. Fibers are mainly a diameter of at most 1 mm, and the average distance between them at most 2 mm, alternatively, may be provided with perforated sheet or wire grid. Due to the location of the grid 13 in the orifice layer 10B is made particularly temperature stable and resistant to abrasion.

In the example implementation of Fig.4 catalytic element 1 is shown with an alternative throttle layer 10C made of metal. Metal butterfly layer 10C contains this porous metal foil 14 made of double-layer. As the porous metal foil 14 is, for example, a fabric of metal fibers or perforated metal foil. The individual layers of the metal foil 14 are preferably offset relative to each other, which achieves the alternative throttle layer 10D is shown in Fig.5. When this butterfly layer 10D is formed mineral filling. Mineral throttle layer 10D is made porous with an average grain size of at least 0.3 mm and at most 5 mm, and a thickness of at least 1 mm as mineral backfill is used, for example, filling basalt aggregate.

Different, made especially low-volume, small - and/or macroporous throttle layers 10,10 A-10D provide blast the dissolution of the internal space of the catalytic element 1 also in the it environment, in particular in the environment of hydrogen in particularly high concentrations of more than 10 vol.%. The gap width of the porous layer throttle 10,10 A-10D in the case of the calculation when the hydrogen concentration is more than 10 vol.% should be chosen very narrow, mostly less than 0.5 mm, Similar to the narrow width of the gap also provides particularly reliable flame barrier.

Claims

1. A catalytic element for recombination of hydrogen with oxygen in the atmosphere of the containment of a nuclear power station, containing the body of the catalyst with the catalytic surface on which is deposited catalytically virtually inactive for the named recombination on rednam pore size, at least 5 - 10000has a pore volume of 0.1 - 1 cm3/g and a thickness of 10 μm - 1 mm

2. Item under item 1, wherein the orifice layer has a direction of flow of the gas mixture varying the thickness and/or varying the diameter of pores.

3. Item one by one from PP.1 and 2, characterized in that the throttling layer is made of ceramic.

4. Item under item 3, characterized in that the ceramic orifice layer is made porous and has a thickness of at most 500 μm.

5. Item under item 3 or 4, characterized in that the ceramic orifice layer contains aluminum oxide or silicon oxide.

6. Item one by one from PP.1 and 2, characterized in that the throttling layer is made of mineral.

7. Item under item 6, characterized in that the mineral throttle layer is made porous and has a thickness of at least 1 mm

8. Item under item 6 or 7, characterized in that the mineral throttle layer formed mineral filling, in particular, filling basalt aggregate, with an average grain size of at least 0.3 mm and at most 5 mm

9. Item under item 6 or 7, characterized in that the throttling layer is made of metal.

10. Item under item 9, wherein the metal other metal butterfly layer contains a metal foil.

12. Item one by one from PP.1-11, characterized in that the throttling layer contains a metal or ceramic fibers, which are arranged in a grid and have a diameter predominantly at most 1 mm, and the average distance between them at most 2 mm

13. Item one by one from PP.1-12, characterized in that the catalyst contains supporting plate, in particular made of stainless special steel.

14. Item one by one from PP.1-13, characterized in that the catalyst contains a flat plate, perforated plate or bowl as a mechanical holder.

15. Item one by one from PP.1-14, characterized in that the catalytic surface contains a catalytic noble metal, particularly platinum or palladium.

16. Item one by one from PP.1-15, characterized in that the catalytic surface is formed of a catalytic material deposited on a mechanical holder with an adhesive layer and/or the intermediate layer.

17. A catalytic element for recombination of carbon monoxide with oxygen in the atmosphere of the containment of a nuclear power station, containing the body of the catalyst with the catalytic surface on which is deposited catalytically almost what I am, what throttle layer is made with an average diameter of 5 - 10000has a pore volume of 0.1 - 1 cm3/g and a thickness of 10 μm - 1 mm

 

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