1. Field of the Invention
The invention concerns the realization of cycle of filtration for liquids containing solid substances in suspension and of a rotary filter suited to carry out such a cycle of filtration.
2. Description of Related Art
Rotary filters of different types are known, through which the filtration of the liquids containing solids in suspension is carried out. Said rotary filters are widely used, for instance in the production cycle of food companies, in the fur trade, in chemical industries as well as others, or they are employed in each of those cases in which it proves to be necessary at the end of a production process to separate any residually suspended solids from the liquids before the phase of purification of the latter.
The mentioned rotary filters, though with different executive variations which make them suitable for various uses, essentially consist of a tank containing the liquid to be filtered, in which a rotary drum is immersed on which a filtering surface is placed. The liquid, passing through the filtering surface, deposits on it the solids in suspension, which are collected and removed using various types of mechanical systems. The filtered liquid is collected inside the rotary drum and is sent by pumps for use or to the purification plant. However, the rotary filters of the known type present a difficulty for how easily their filtering surfaces become obstructed. It is understood that the amount of solids deposited on the filtering surfaces in the unit of time is directly proportional both to the rate of flow through the filtering surface itself, and to the degree of filtration resulting from it, so that the obstruction of the filtering surfaces takes place when one of the mentioned parameters proves to be higher than the maximum value for the rotary filter in use. The rotary filters presently in use, in fact, present the problem that if the purpose is to generate high flow rates and high filtrations at the same time, their filtering surfaces become very rapidly obstructed and the user is frequently forced to stop the filter in order to clean the filtering surfaces. To avoid this, using the known rotary filters a compromise is usually made, which is to filter quite limited rates of flow and to produce reasonably reduced degrees of filtration to avoid the continual obstruction of the filtering surfaces.