Patent Publication Number: US-4367202-A

Title: Centrifugal counter-flow liquid contactor

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a centrifugal counter-flow liquid contactor for use in a centrifugal extractor in which a heavy liquid and a light liquid insoluble to each other are made to contact with and then separated from each other. 
     2. Description of the Prior Art 
     FIGS. 1 and 2 in combination show a conventional centrifugal counter-flow liquid contactor. Referring to these Figures, the centrifugal counter-flow liquid contactor has a rotary body 2 adapted to rotate as a unit with a rotary shaft 1. A multiplicity of porous cylinders 3 are mounted within the rotary member 2 concentrically with the rotary shaft 1 in a plurality of stages. A reference numeral 4 denotes a heavy liquid introduction pipe adapted to introduce the heavy liquid into the rotary body 2 through a passage 12, while a reference numeral 5 denotes a heavy liquid discharge pipe through which the heavy liquid is discharged from the space inside the rotary body, via a passage 13. The light liquid is introduced into the rotary body 2 through a light liquid introduction pipe 6 via a passage 14. These pipes 4, 5 and 6 are arranged radially. A reference numeral 7 designates a light liquid discharge pipe. Reference numerals 8 and 9 designate directions of flow of the light liquid and heavy liquid caused by the rotation of the rotary body 2. A reference numeral 10 designates a plurality of rinsing pipes arranged radially and adapted to close the rinsing ports in the rotary body 2. In the case where the liquid contactor has a substantial axial width, the rinsing pipes are arranged in a plurality of stages spaced in the axial direction to facilitate the rinsing. 
     From a macroscopic point of view, the light liquid flows, as designated at a reference numeral 8, in the same direction as the rotation of the rotary body 2 and toward the inside of the latter. In contrast, as designated at a reference numeral 9, the heavy liquid flows in the direction opposite to the direction of rotation of the rotary body 2 toward the outside of the latter. In this liquid contactor, the radially extending pipes such as the heavy liquid discharge pipe 5, light liquid introduction pipe 6, rinsing pipes 10 and so forth obstructs the circumferential flow of the heavy and light liquids to cause non-uniform flow of these liquids resulting in a deteriorated mixing effect of the heavy and light liquids and, hence, in a deteriorated extraction performance. 
     SUMMARY OF THE INVENTION 
     It is, therefore, an object of the invention to provide a centrifugal counter-flow liquid contactor in which the flow of liquids in the rotary body is smoothed and uniformalized to enhance the mixing effect to improve the extraction efficiency. 
     To this end, according to the invention, there is provided a centrifugal counter-flow liquid contactor in which radial insertions are placed in the region where the heavy and light liquids are mixed with each other and disc-shaped partition plates are placed at both sides of the radial insertions to separate the latter from the region of mixing of the heavy and light liquids. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a vertical sectional view of a conventional centrifugal counter-flow liquid contactor with a part thereof being removed; 
     FIG. 2 is a sectional view taken along the line II--II of FIG. 1; and 
     FIG. 3 is a vertical sectional view of a centrifugal counter-flow liquid contactor constructed in accordance with an embodiment of the invention. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     A preferred embodiment of the invention will be described hereinunder with specific reference to FIG. 3. 
     The centrifugal counter-flow liquid contactor of the invention has a rotary body 2 fixed to a rotary shaft 1 and accomodating porous cylinders (separation discs) 3. The light liquid is introduced into the rotary body 2 from the outer peripheral portion of the latter through a light liquid introduction pipe 6 and via a passage 14 formed in the rotary shaft 1, while the heavy liquid is introduced into the rotary body 2 from the inner peripheral portion of the latter through a heavy liquid introduction pipe 4 and via a passage 12. The heavy liquid which have reached the outer peripheral portion of the rotary body 2 is discharged through a heavy liquid discharge pipe 5. Also, means are provided to discharge the light liquid which has reached the inner peripheral portion of the rotary body 2. As the rotary body 2 rotates, the heavy liquid flows circumferentially and radially outwardly while the light liquid flows circumferentially and radially inwardly so that the heavy and light liquids make a counter-flow contact with each other. More specifically, the light liquid flowing radially inwardly flows circumferentially in the same direction as the rotation of the rotary body, while the heavy liquid flowing radially outwardly flows circumferentially in the direction opposite to the direction of rotation of the rotary body. Thus, the light liquid and heavy liquid flows spirally in the circumferentially opposite directions to reach the inner side and outer side of the rotary body 2. 
     According to the invention, in order to separate or isolate the insertions radially inserted into the counter-flow contact region of two liquids to smooth the flow of these liquids, disc-shaped partition plates 11 are disposed at both sides of the radially extending pipes such as the heavy liquid discharge pipe 5, light liquid introduction pipe 6 and so forth, so as to separate or isolate the radial insertions from the region where the two liquids are mixed with each other. 
     The presence of the radially extending pipes hinders seriously the circumferential flows of the light and heavy liquids caused by the rotation of the rotary body 2 to make these flows non-uniform, resulting in an insufficient contact and mixing of the heavy and light liquids, resulting in a deteriorated extraction performance. According to the invention, however, this problem is overcome because the radially extending pipes are isolated from the mixing region. 
     The extraction performance of the centrifugal counter-flow liquid contactor of the invention having the partition plates 11 for isolating the radially extending pipes was compared with that of the conventional centrifugal counter-flow liquid contactor having no partition plate. 
     It was confirmed that, while the theoretical number of stages in the conventional contactor is 3.4,  the theoretical number of stages in the contactor of the invention is 5.3. Thus, the extraction performance of the contactor of the invention is much superior to that of the conventional one. 
     A test was conducted to compared the extraction performances of the conventional liquid contactor shown in FIG. 1 and the liquid contactor of the invention having the construction shown in FIG. 3, with the same structure in the rotary body 2 and with the same liquids. As stated below, the liquid contactor of the present invention showed an extraction performance much superior to that of the conventional one. 
     Theoretical number of stages in conventional liquid contactor shown in FIG. 1: 
     3.3 (in case of large-sized apparatus) 
     1.5 (in case of small-sized apparatus) 
     Theoretical number of stages in liquid contactor of the invention shown in FIG. 3: 
     5.2 (in case of large-sized apparatus) 
     2.3 (in case of small-sized apparatus) 
     Thus, the present invention offers an about 50% improvement of the extraction performance.