Presses – Methods – With separation from material of liquid expressed
Patent
1995-10-18
1997-03-25
Gerrity, Stephen F.
Presses
Methods
With separation from material of liquid expressed
100 43, 100 50, 100 99, 100104, 426231, 426478, 426489, B30B 902
Patent
active
056134347
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The invention relates to a method for controlling or regulating the pressing pressure for the separation of solids and liquids from the material for pressing by means of a press, which performs at least one pressing cycle during a pressing operation by means of a pressure increase.
DESCRIPTION OF THE PRIOR ART
In presses of this kind, the material for pressing is filled and emptied in the form of individual batches, which are separate from each other. The presses are therefore designated as discontinuous. Currently there are a number of known discontinuous filter presses, which work in batch operation. They are embodied as piston presses, chamber filter presses, tank presses, packing presses, basket presses, etc.; the increase in pressing pressure is carried out via plates, pistons, or diaphragms, with hydraulic, pneumatic, or mechanical pressing means.
Pressing materials that are to be processed in these presses frequently have a widely varied pressability. Furthermore, even successive batches on occasion vary widely in pressability. These circumstances make it very difficult to preset operating parameters for the course over time of the pressure increase on the basis of experiments. EP-B 0 304 444 and EP-A 0 485 901 have also disclosed a plurality of methods which permit an automatic control or regulation of the pressure increase, suited to the material for pressing.
This kind of known method for controlling or regulating the pressing pressure level currently have the following disadvantages: on empirical values. That is why the above mentioned difficulties cannot be avoided when there are widely varying properties of the material to be pressed. sought is not achieved in practice, and that in comparative tests with methods that use preset empirical parameters, even better results are achieved with methods of this kind. economic aims together.
SUMMARY OF THE INVENTION
The object of the invention, therefore, is to disclose a method of the above mentioned kind for controlling or regulating the pressing pressure, which avoids the disadvantages mentioned.
According to the invention, the attainment of this object is achieved by the fact that the discharge of the liquid phase from the press is directly or indirectly measured, and that from the course over time of the discharge behavior of this phase, a time is determined at which the further pressure increase is limited to a constant value for each pressing cycle, this time lies within a time interval which starts at the beginning of the discharge and ends after the ending of a length of time that is equal to twice the time between the start of the discharge and the onset of the maximal average flow capacity of the liquid phase.
Advantageous embodiment forms of the method for determining such a time as well as the use of this method can be inferred from the claims.
BRIEF DESCRIPTION OF THE DRAWINGS
Exemplary embodiments of the invention are explained in the following description and the figures of the drawing.
FIG. 1 shows a partial section through a horizontal filter piston press for carrying out the method according to the invention,
FIG. 2 is a graph showing the course over time of the discharge behavior of the liquid phase of a press according to FIG. 1,
FIG. 3 is a graph showing the course over time of the pressing pressure and of the pressed-out quantity of liquid in an individual piston backstroke and the following piston forward motion of a press according to FIG. 1,
FIG. 4 is a graph showing the course over time of the pressing pressure and of the pressed-out quantity of liquid in a method example according to the invention,
FIG. 5 is a graph showing the course over time of the pressing pressure and of the pressed-out quantity of liquid in a further method example according to the invention,
FIG. 6 is a graph showing the course over time of the pressing pressure and of the pressed-out quantity of liquid in a further method example according to the invention,
FIG. 7 is a graph showing the course over time of the pressing
REFERENCES:
patent: 5167832 (1992-12-01), Carlsson et al.
patent: 5207154 (1993-05-01), Bonnet
patent: 5231922 (1993-08-01), Hartmann
Bucher-Guyer AG Maschinenfabrik
Gerrity Stephen F.
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