1. Field of the Invention
This invention relates to tanks for storing and processing food stuffs, and more particularly to a novel self-emptying tank for storing and processing grapes and their fermentation products.
2. Related Art
A primary objective in the design of storage and processing tanks, particularly those used in the fermentation of wine, include the complete emptying of the tank. This is easily achieved, of course, with low viscosity fluids. However, should the tank contain solids, such as the residue of grape skins and pulp, the achievement of a fully self-draining tank is far more difficult. In addition, current applications for self-emptying tanks require the tank's drain opening to be as close to vertical as practical. A vertical orientation of the drain opening facilitates the control of the discharge process and concentrates any remaining drainage and drippings over a smaller area.
As will be demonstrated in the following review, the known prior art has failed to effectively and economically achieve these highly desired objectives.
The prior art is replete with myriad forms of tanks proposed to facilitate their emptying or draining. Most of these tanks have a vertically-oriented cylindrical upper section and a conical bottom section, the axes of the two sections being co-linear. Examples of such tanks that also include a substantially horizontal exit opening, vice the desired vertical exit opening, date back to 1875, i.e. Reford (U.S. Pat. No. 159,450). Other examples include Rall (U.S. Pat. No. 291,535), Lapp (U.S. Pat. No. 755,144), Schneible (U.S. Pat. No. 954,889), Cremaschi (U.S. Pat. No. 2,536,994), Potter (U.S. Pat. No. 3,823,655) and Maarleveld (U.S. Pat. No. 4,164,902).
Others have addressed the goal of a vertically-oriented exit opening in combination with a vertical upper cylindrical section and a conical bottom section. For example, Brembeck (U.S. Pat. No. 3,100,052) discloses a bulk feed bin having an angled and adjustable exit opening, but does not provide for a fully-vertical opening. Rieger (U.S. Pat. No. 4,593,612) incorporates a horizontal auger in the bottom of the lower conical section to extract the tank's contents. Reiger's arrangement leaves many crevices and corners for solids to accumulate.
Zepponi (U.S. Pat. No. 3,910,173) teaches a tank having an vertically-oriented right circular cylindrical upper section mated with a conical lower section along a horizontal diameter of the cylinder. The uniqueness in Zepponi is that the axis of the conical section is angled with respect to the axis of the cylindrical section such that a portion of the wall of the conical section is in vertical alignment with the wall of the cylindrical section. In addition, the angle of the cone's axis and the dimensions of the cone provide wall angles that are at least as steep as the angle of repose of the tank's contents. An exit opening is provided by an angled cut across the cone near its vertex. If this cut is made perpendicular to the axis to the cone, the opening will be circular but at an angle substantially deviating from the vertical. If the cut is made at an angle to the cone's axis, the opening will be extremely elliptical, and still substantially non-vertical. Because of the vertical orientation of a portion of the cone's wall, any cutting of the cone by an angled cut across the cone near its vertex will produce a substantially horizontal exit opening and not produce a fully-vertical exit opening.
In addition, the horizontal intersection between Zepponi's cylindrical upper section and his conical lower section reduces the amount of front surface area of the tank available for the installation of ancillary devices such as temperature probes and sample taps.
Therefore, there is a need for an improved process tank for liquids such as wine that contain substantial amounts of solids at times during the process. It is a primary objective of the invention herein disclosed to provide a self-emptying tank that presents a fully-vertical outlet or drain opening. It is another objective to provide a tank that inhibits the retention of solid residues subsequent to drainage of the tank. It is yet another objective to provide a tank that can accommodate any desired drainage opening angle and shape and still offer effective residue elimination results. It is still another objective of this invention to provide a self-emptying tank that continues its cylindrical shape downwardly as close as practical to the outlet opening. It is another objective of this invention to minimize the stress in the intersections between the components forming the tank. It is a final objective to provide a tank that is inexpensively fabricated.