Patent Number: 046860894
Section: description

DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION FIG. 1 is a section view of a vertically standing sieve-plate column 11 which is known from the state of the art. The sieve-plate column 11 has sieve plates 13 mounted so as to be axially displaced one from the other. The spacing identified by the reference letter x between two sieve plates 13 is usually 50 mm in the nuclear reprocessing area. Instead of a sieve plate 13, a distributor plate 15 which is known from the state of the art is fixedly fitted into the sieve-plate column 11. The distributor plate 15 has angle plates 17 which are bent downwardly out of the distributor plate 15 and are at an angle of about 30.degree.. The angle plates 17 were stamped out of the distributor plate 15 so that corresponding openings 19 are formed behind the angle plates 17. If a pressure pulse is imparted to the liquid content of the sieve-plate column 11, then, during the downward stroke movement of the column of liquid, a vortex 21 is produced when the liquid passes through the openings 19. The vortex 21 imparts a swirl movement to the liquid. In the upward stroke movement of the column of liquid, a vortex 23 is formed, which also imparts a swirl movement to the liquid content. Because of this known arrangement in the state of the art, the liquid flowing through the sieve-plate column 11 is deflected out of the flow path by an amount indicated by the reference letter y. A shower of drops of the one phase is constantly produced after passing through the holes 25 in the sieve plate 13. The sieve-plate column 31 shown in FIG. 2 has sieve plates 33 which are axially distributed at the usual spacing relative to each other and which have through holes 35 therein. In the event of pulsation being imparted to the column of liquid, the holes 35 in the sieve plates 33 cause one phase to undergo drop formation. A static mixing element 36 which takes up the entire distance x is arranged between two sieve plates 33. The static mixing element 36 has open channels 37 which intersect each other and which diverge away from the longitudinal axis of the arrangement; the channels 37 extend at an angle of .alpha.=45.degree., in different directions. This configuration cannot be seen from this simplified view of the sectional surface of the static mixing element 36. However, the important consideration in this respect is only that the upper openings 39 of the channels 37 are displaced radially with respect to the lower openings 41. Respective ones of static mixing elements 36 are also disposed in the next intermediate space between the following two sieve plates 33 and in the intermediate space following the latter, the mixing elements 36 being displaced relative to each other through 90.degree. about the central longitudinal axis. When the liquid passes through the static mixing elements 36, it is deflected radially out of the perpendicular. After each occasion that the liquid has passed through a static mixing element 36, the liquid is guided again through a sieve plate 33 and drop formation of the one phase is initiated again. In FIG. 3 and in FIG. 4, which is rotated through 90.degree. relative to FIG. 3, an explanatory diagrammatic view on a larger scale is provided for the flow paths within the plane of the section of the three static mixing elements shown in FIG. 2. It will be seen therefrom that flow channels which are formed in the sieve-plate column 31 are effectively interrupted and the desired cross-mixing is achieved. FIG. 5 shows a sieve-plate column 51 in which six static mixing elements 53 are disposed in the upper third of the column. The mixing elements 53 are each arranged in the respective spaces between two sieve plates 55 and correspond in respect to their height to the spacing x between two sieve plates 55. The heavy phase is introduced into the sieve-plate column 51 at the top by way of the feed 57. The light phase is supplied to the sieve-plate column 51 through the lower feed 59. The light phase is removed at the upper discharge 61 while the heavy phase is removed at the lower discharge 63. The upper three static mixing elements 53 are arranged in accordance with the configuration shown in FIG. 2. They are now followed, in a downward direction, by three free intermediate spaces 65 between the corresponding ones of sieve plates 55. Then the first of three further static mixing elements 53 is disposed in the next intermediate space. The following two intermediate spaces are provided with the other two static mixing elements 53 and are arranged in a displaced relationship relative to each other. In FIG. 6, the curve-like courses (referred to in language of the art as the flooding curve) of the operating range of a sieve-plate column having a distributor plate which is known from the state of the art (curve A) is plotted against the pulse amplitude at a frequency of 1 Hz. In comparison therewith, curve B shows the operating range of a sieve-plate column equipped with the mixing arrangement according to the invention when using a static mixing element. It will be seen (see the nominal rating--straight line (C) that the sieve-plate column with the mixing arrangement according to the invention has a substantially greater operating range and the intensity of pulsation can be selected in a greater band width. It is understood that the foregoing description is that of the preferred embodiments of the invention and that various changes and modifications may be made thereto without departing from the spirit and scope of the invention as defined in the appended claims.