This invention relates to a cell-less vacuum rotary filter for the separation of solids-liquid mixtures.
Cell-less vacuum rotary filters known in the art utilize a suction pump disposed outside of the vacuum-rotary filter to suck filtrate out of the rotating filter drum. In such configurations it is unavoidable that air will be sucked out of the filter drum with the filtrate and mixed therewith. Furthermore, because the suction force of the suction pump must be substantially greater than the vacuum existing in the filter drum, economical operation can only be obtained utilizing a relatively low vacuum pressure, which limits the volume of material which can be handled in a given time.
Certain liquids requiring filtration, such as fruit juices and wine, can not be stored directly upon discharge from conventional vacuum rotary filters because the air mixed therewith by such filters is harmful to the liquids. Storage of such liquids for extended periods without removal of the air mixed therewith results in oxidation, which appreciably diminshes not only the quality of the recovered liquid, but also impairs the stability of the liquid. Accordingly, liquids discharged from conventional rotary vacuum filters must be additionally processed to remove the air.
In accordance with the principles of the present invention, a rotary vacuum filter is provided with a suction pump disposed in the interior of a rotating filter drum so that no air is mixed with the discharged filtered liquid, making additional processing unnecessary.
The invention consists of a hollow rotating filter drum rotatably supported in a tank containing a liquid to be filtered. The drum has a hollow conduit coaxially extending through it, said conduit having a port connecting the interior of the drum to a vacuum pump. A vacuum thus created inside the drum draws liquid from the tank through a filter disposed on the surface of the drum into the interior of the drum.
A suction pump is also mounted to the hollow conduit in the interior of the drum and has a suction head which extends into the filtered liquid for removal thereof without mixing the liquid with air. The removed filtered liquid is discharged through a pipe also extending through the hollow conduit.
A liquid-level measuring device is provided in the interior of the drum to ensure that a liquid-level is maintained inside the drum so that the suction head of the suction pump will always be beneath the liquid-level.
It is accordingly an object of the present invention to provide a cell-less rotary vacuum filter which separates solids-liquid mixtures without mixing the filtered liquid with air. Another object of the present invention is to provide a cell-less rotary vacuum filter which is operable at high vacuum pressures so that a large quantity of liquid may be filtered in a given period of time.
A further object of the present invention is to provide a means for maintaining a constant liquid-level inside a filtered drum in a rotary vacuum filter to ensure that a suction pump in the filter drum is constantly maintained below a liquid-level.
Further details, features and advantages of the present invention will be apparent from the following explanation of the invention and the accompanying drawings.