Patent Number: 053217306
Section: description

Referring now to the figures of the drawing in detail and first, particularly, to FIG. 1 thereof, there is seen a containment 1 made of steel or reinforced concrete, which is part of a nuclear reactor plant having a pressurized water reactor with a primary loop, of which only a reactor pressure vessel 2 is shown. The reactor pressure vessel 2 is mounted below a partition 3, in which an overflow opening 4 connects a lower part 5 with an upper part 6. Three-dimensionally distributed ignition devices 10 are shown in the upper part 6. The ignition devices 10 assure the burn-off of hydrogen in a known manner if the local concentration exceeds the ignition limit of 4%. Such ignition devices 10, which may also be disposed in the lower part 5, are used to eliminate momentarily occurring hydrogen quantities, by tripping thermal or catalytic reactions. A plurality of aerosol producers 11 are disposed in distributed fashion in the lower part 5 and in the upper part 6. Catalyst particles, for instance of platinum and/or palladium, are finally distributed in a liquid, preferably water, with the aerosol producers 11. Additives, such as emulsifiers or means for increasing the viscosity at room temperature, or the like, may optionally be added to the liquid. After the spraying, the suspension or solution, which is in the form of droplets, is dried by heating and made to rise in the containment. The suspension or solution which is intended for the distribution is delivered to the aerosol producers 11 through lines 12 from a common tank 13 that is installed outside the containment 1. The tank 13 includes a volume of suspension 15 and an agitator 16 in its lower part for homogenizing the suspension. A compressed air line 18 is connected above a surface 17 of the suspension, so that a cushion 19 of propellant gas is formed. A filter 21 that is permeable to the catalyst particles and is intended to retain large agglomerates, is mounted on the bottom 20 of the tank 13. The filter 21 is located in front of an outlet line 22. A diagrammatically illustrated thermal insulation layer 23 is provided on the outside of the tank 13. The tank may also be heated. In order to charge the aerosol producers 11, a valve 25 that is disposed in the course of the line 12 outside the containment 1, is opened. A bypass line 26 around the tank 13 remains closed by a valve 27. The excess pressure of the propellant gas cushion therefore forces the volume of suspension 15 into the lines 12. The suspension or solution, which travels through the lines 12, also reaches rows 30 and 31 of nozzles, for instance two rows, which are disposed in the region of the overflow openings 4 and directly act upon a superheated, and optionally hydrogen-containing vapor stream rising from the lower part 5 into the upper part 6 with suspension, as is suggested by arrows 32 and 33. While the suspension is entrained upward from the rows 30, 31 of nozzles by the vapor stream passing through the overflow opening 4, an upwardly oriented distribution flow is generated with the aerosol producers 11 by local heating, as will be described in further detail below. The quantity of the suspension may be adjusted or regulated overall and in its course over time by means of a suitable control of the valve 25. Moreover, by extending a separate compressed air or vapor line up to the rows 30, 31 of nozzles, the aerosol production can advantageously be made finer as will be explained below with regard to FIGS. 4 and 6. FIG. 2 diagrammatically shows that an aerosol producer 11 which, for instance, has a laterally disposed suspension container, aspirates the hydrogen-containing vapor atmosphere in the containment 1 as indicated by arrows 35. Arrows 36 indicate the way in which the heated aerosol atmosphere rises. The result in the containment 1 is a superheating zone 37, in contrast to a mist zone 38 located below it. A boundary 39 represented by dashed lines is in actuality a transition zone. Arrows 40 symbolically show that a rising flow can be created by the superheating zone 37 outside the aerosol producer 11 as well. The ignition devices 10 are therefore simultaneously acted upon by hydrogen-rich vapor. The aerosol producer 11 which is shown in a vertical section in FIG. 3 has a housing in the form of a vertical tube 45 that is stepped back multiple times over its cross section. The vertical tube 45 has an open lower end 46 which forms an inlet opening 47. A prefilter 48 and a superheating or propellant catalyst 49 which are disposed in the inlet opening 47, are inclined obliquely, and conically in the case of a rotationally symmetrical embodiment. With the same embodiment, a heater could also be accommodated there. A constricted tube part 50 located above the lower end 46 is narrowed to approximately half its cross section and includes a heating cartridge 51 with ribs 52. Nozzles 55 are disposed above the cartridge and can be fed through regulating valves 56. Feed lines 57 lead to a switch element 58 which, for instance, is equipped with a temperature-dependent or catalytic melting member or a pressure-dependent bursting member. In order to provide for fast aerosol production, particularly upon startup, a preheater 78 that is filled with a small quantity of suspension, may be disposed directly in a drying zone 61. A widened part 60 of the tube 45 above the constricted tube part 50 is twice as long as it is wide, or even longer. The widened part 60 serves to generate buoyancy of the vapor atmosphere carrying the aerosols and also serves to accommodate the drying zone 61. The widened part 60 has an upper end which is closed with a cap 62, as a protection against downdrafts. Below the cap 62 are lateral outlet openings 63, through which the aerosol atmosphere leaves the tube 45 in the direction of arrows 64. A region 65 below the cap 62 is widened somewhat. There, ambient atmosphere aspirated through inlet openings 66 can be admixed, as is suggested by arrows 67. The size of the openings 66 is advantageously adjustable. Partial recirculation of already produced aerosols, and accumulation or settling down in the region of the entire aerosol producer 11, bring about a continuous regeneration of a propellant effect of the superheating catalyst 49. In the exemplary embodiment of FIG. 3, the aerosol producer 11 disposed in the interior of the containment is coupled directly to a tank 70 that feeds the suspension and propellant vapor lines feed lines 57. The tank 70 has a bottom 71 on which a coarse filter 73 is disposed, above an outlet 72, and the tank has an insulation 74 on the outside. A circulation which is indicated by an arrow 76 can be generated in a liquid 75, for instance by local heating and optionally cooling. A lower part 77 of the tank 70 is closed off by a bursting disk 80. Catalyst powder 81 rests on the bursting disk 80. This powder 81 is a fine powder, for instance, having a statistical mean diameter of 0.2 to 1.5 .mu.m, which may be mixed with a fluxing agent of a few nanometers. The remainder of an upper part 79 includes a propellant gas 83, such as nitrogen, at a pressure of 5 to 20 bar, which is settled or accumulated in a sorbent 82, such as a molecular sieve. A connection 84 leading to a pressure measuring unit 85 and a fill line 86 for filling purposes, is mounted on the upper end of the tank 70. If need be, or in other words in the event of a malfunction where hydrogen is produced, the switch element 58 opens automatically. As a result, the overpressure of the cushion of the propellant gas 83 acts upon the bursting disk 80 and tears it. The catalyst powder 81 travels into the liquid 75 and is carried out with it through the nozzles 55. In the constricted tube part 50, an aerosol mist is produced, having a diameter of catalyst particles of 0.1 to 2 .mu.m, with liquid droplets that have a diameter of less than 30 .mu.m. By heating the carrier gas to 50.degree. C. above ambient temperature, the suspension droplets dry to form a fine aerosol within less than one second. The catalyst particles contained in it are finely distributed slowly, and rise continuously, over the interior of the containment 1. The charging can be adapted to the hydrogen content and can be continued even over a relatively long period, such as 24 hours. Alternatively, the catalyst powder may also be stored in the liquid as a suspension with additives, as described above, before it is discharged. The aerosol producer 11 in FIG. 4 has a tube 90 formed as a diffusor. The tube 90 has a lower, slightly narrowing region 91 that accommodates not only inlet openings 92, but also an auxiliary blower 93, which is especially advantageous for increasing the output. Above the region 91, in a partition 94, is a thermal recombiner or heater 95, for instance an electric heater, so that the separate provision of such a device can be dispensed with as applicable. A preheater 78 is disposed in the region of a constricted tube part 96, above a reflux protector 97. The preheater may be fed with catalyst solution or catalyst suspension through a line 99 connected to the tank 70. A row of nozzles 98 is distributed over the tube cross section above the preheater 78 and can be charged with catalyst solution or suspension through a branch 99a of the line 99. In order to provide fast aerosol production, the slight quantity of suspension in the preheating container 78 can be heated in a short time by the vapor atmosphere that is aspirated in accordance with the arrows 35, is heated to approximately 300.degree. C. to 500.degree. C. as it passes through the heater 95, and can be carried out through a nozzle 98a. It can be seen in the exemplary embodiment of FIG. 5 that two separate tanks 101 and 102 can be used to furnish catalyst particles 103 or liquid 104. As is indicated by arrows 105, the tank 101 is kept at 20.degree. C. above ambient temperature, for instance, by thermal conduction. The top of a liquid jacket 106 is connected to an overpressure valve 107 as protection against overheating. Thermal insulation of the tank 101 is suggested at reference numeral 108. An outlet 110, which is provided with a preceding coarse filter 109, leads through a membrane switch 111 to a non-illustrated aerosol producer. A line 115 having a switch element 116 leads from the top of the tank 101 to the underside of the tank 102. This tank is again divided by a membrane or foil 117. Above the liquid 104 is a propellant gas space 118, which contains a molecular sieve 119, for instance, as a sorbent. If the need arises, the switch element 116 opens automatically. As a result, the overpressure of the propellant gas in the propellant gas space 118 acts upon the foil or membrane 117 and tears it. The membrane switch 111 opens at the same time. The liquid 104 passes through the line 115 into the tank 101, where it is mixed with the catalyst particles 103 to form the solution or suspension. The solution or suspension passes through the line 110 to the non-illustrated aerosol producer or generator. In the exemplary embodiment of FIG. 6, a device 120 for aerosol production is disposed outside the containment 1. An adequate thermal quantity is continuously prepared in a heat accumulator 121, by means of an electric heater 122. The heat accumulator 121, along with a suspension or solution container 123 and a water prestorage container 124, are disposed in a common heat-insulating casing 125. A horizontally disposed heat-insulated tube 126 is connected to the casing 125 in the region of the heat accumulator 121. The interior of the tube 126 forms a conduit 127, which communicates with the heat accumulator 121 through an opening 128 in the casing 125. A line 129 connected to the tube 126 is carried through a duct 130 into the containment 1. Two valves 131 and 132 that are connected in series are provided in the line 129, and a bursting disk 133 is connected parallel to the valves 131 and 132. If the need arises, the valves 131 and 132 are opened. The production of propellant vapor is effected by spraying water from the water prestorage container 124 into the heat accumulator 121 through a line 134. The response and feeding of the propellant vapor into the containment 1 can also be effected through the bursting disk 133, by means of the pressure arising upon the vapor generation. In the superheated vapor stream, the suspension is introduced into the containment 1 through the line 129 with the aid of a two-substance nozzle 135 that is disposed in the conduit 127 and communicates with the suspension container 123 through two vertical lines 136 and 137. In the containment, the catalytic aerosols that are dried in the conduit 127, are distributed with the aid of a nozzle-like distributor 138. They rise in the containment 1 and form a floating mist that is catalytically effective in the oxidation.