Patent Number: 051732513
Section: description

Referring now to the figures of the drawings in detail and first, particularly to FIG. 1 thereof, there is seen a mixing chamber 1 that is closed on the lower end of the drawing and open on the upper end and which has a rectangular cross section and a straight center line 2. Deflector elements 3 which are connected to the right-hand side of the mixing chamber 1, over the entire height of the mixing chamber, deflect fluid flows 5 entering vertically from above through rectangular openings 4. The flows 5 also have intrinsically different temperatures and/or compositions. Deflector walls 6 that in this case are in the shape of a quarter circle deflect the fluid flows 5 into the mixing chamber 1, and in so doing carry a predominant portion of the fluid flows 5 at undiminished speed into the lower part of the mixing chamber 1. In this way, a macroscopic vortex is generated in the mixing chamber 1 without any special baffle devices. Although this vortex is continuously braked in the corners of the rectangular cross section of the mixing chamber 1, it is kept in rotation by an inflow from a plurality of the deflector elements 3 that are disposed in staggered fashion in the longitudinal direction of the mixing chamber. The inflow is at a tangent with respect to the vortex. The openings in the vertical parts of the deflector elements 3 at a location 7 on the mixing chamber 1 carry fluid flows into the mixing chamber 1 at a tangent to the vortex. This can be seen more clearly in FIG. 2. In order to provide good, thorough mixing, the mixing chamber 1 should be substantially longer at the upper end of FIG. 1 than shown. The end of he mixing chamber 1 has a rectangular outlet opening 8 for the exit of a mixed fluid flow 9. In FIG. 2, a mixing chamber 21 has a curved center line 22 and is joined over its entire height to one of a plurality of deflector elements 23. Fluid flows 25 flow through vertical openings 24 in a cover or ceiling 28 and are deflected jointly by walls 26, which are curved into a quarter circle, and carried preferentially into the lower part of the mixing chamber 21. There, as already described with regard to FIG. 1, a macroscopic vortex is created, which in this case, in accordance with the curved center line 22, moves to a non-illustrated outlet opening. FIG. 3 shows a mixing apparatus as in FIG. 2, but by not showing the cover or ceiling and outer wall of a mixing chamber 31, a part of a star-shaped distributor 30 is made visible, which carries fluid flows 35, entering through diagrammatically shown openings 34, into the mixing chamber 31 through radial deflector elements 33. Once again, as already described for FIGS. 1 and 2, a macroscopic vortex in the mixing chamber 31 is created, which is kept in rotation by the inflows, that are predominantly at a tangent, from the deflector elements 33, which in this case are staggered in the circumferential direction of the mixing chamber 31. An outlet for the exit of the mixed fluid flow is also not shown in this case. However, as in FIGS. 4 and 5 which are described below, the outlet may be provided radially toward the outside of the mixing chamber. FIGS. 4 and 5 show an application of the present invention in the form of a mixing apparatus for a gas-cooled nuclear reactor operating on the pebble-bed principle. In both drawing figures, the same numerals are used. A circular mixing chamber 41 with a rectangular cross section surrounds a distributor being formed of twelve sectors 42-45. There are nine identical sectors 42 and three sectors 43, 44 and 45 without deflector elements. These twelve sectors form a pebble discharge conduit 46 in the middle. Toward the outside, the mixing chamber 41 is defined by twenty-two sector-shaped graphite blocks 47, which are insulated on the outside by coal stone blocks 48. Along with the sectors 42, 43, 44 and 45 and an outlet opening 61, the blocks 48 rest on twenty-four likewise sector-shaped graphite blocks 49 and 50 and are joined both to the blocks 49 and 50 and to one another by various smaller graphite blocks 51, 52, 53, 54, 55. Moreover, some of the graphite blocks 47 are pierced by vertical bores 56 and 57, which are used for cooling and/or for receiving absorber rods and absorber pebbles. The bores contain graphite liners 58 and sealing rings 59 and 60, but this is not of any importance to the present invention. As is seen in the right-hand half of each of FIGS. 4 and 5, the mixing chamber 41 discharges in the outlet opening 61 for an exiting mixed fluid flow 62. In this region, the sector-shaped graphite blocks 47 and coal stone blocks 48 are respectively pierced by an outlet connecting piece 63 and a ring 64. There are numerous vertical conduits 65 above the mixing chamber 41 and deflector sectors 42, but not in the vicinity of the outlet opening 61. Farther up, these conduits 65 communicate with two annular chambers 66 and 67, so that gas flows 69 arriving through numerous openings 68 across the reactor cross section can find a way to the mixing chamber 41 through the conduits 65. Pebble-type fuel assemblies 70 are shown at only one point in FIG. 5, but in actuality a great many of them form a core 72, which is substantially contained by the graphite blocks 47. The fuel assemblies 70 also fill the pebble discharge tube 46 and are discharged downward as needed, in a non-illustrated manner. The gas flows 69 flow from top to bottom, first through the numerous small openings 68, into the two concentric annular chambers 66 and 67. From there, the gas flows 69 flow through the numerous vertical conduits 65, but these are disposed only above the deflector sectors 42 where, as already described for the preceding drawing figures, they are deflected into the mixing chamber 41. The rotating vortex created in the mixing chamber flows clockwise in the upper half of FIG. 4 and counter-clockwise in the lower half of FIG. 4 and emerges as the mixed gas flow 62 through the outlet opening 61 and the outlet connecting piece 63, into a line, which will not be described in detail, to a non-illustrated heat exchanger. The intended disposition of sectors 43, 44, 45 without deflection elements in the vicinity of the outlet opening 61 prevents any inadequately mixed gas flows from reaching the outside. Radioactive radiation emerging in particular from the highly radioactive fuel assemblies 70 in the pebble discharge conduit 46, which cannot be shielded with graphite blocks in the vicinity of the discharge conduit 61, is reduced in this region with absorber material with which bores 73 can be filled. As is shown in FIG. 5 only, bores 74 are also disposed in the immediate vicinity of the pebble discharge conduit 46 and can be filled with absorber material in order to already reduce the radioactive radiation at that point. This is of particular significance at the level of the deflector sectors 42, which do allow more radioactive radiation to reach the outside because the graphite material is absent there. Inside the graphite blocks 49, the pebble discharge conduit 46 is extended downward with a pebble discharge tube 75.