Method and an apparatus for accelerating air or gas exchange

In a method of, and an apparatus for accelerating air or gas exchange during cyclical operation of a pressure chamber with the aid of a pumping device connected to the pressure chamber, and with the aid of a compressor for at least partially compressing the air or gas, the steps include filling the pressure chamber with compressed air or gas through the compressor, thereafter discharging the air or gas from the pressure chamber, and operating the pumping device during at least one of the filling or discharging steps.

BACKGROUND OF THE INVENTION 
The invention relates to a method for accelerating air- or gas-exchange, 
and reducing operating energy during filling and/or discharge of pressure 
chamber. 
In a method of the aforedescribed type there arise, on one hand, uneconomic 
energy costs in an initial phase of the filling of the pressure chamber, 
until a pressure slightly above atmospheric pressure has been reached, as 
air or gas compressed in a compressor to a higher pressure than 
atmospheric pressure expands again during passage into the empty pressure 
chamber through a conduit. On the other hand, the use of a blower for the 
same purpose, although requiring less energy, requires additional time in 
order to reach a minimal filling degree at a considerably lower filling 
capability, which, in turn, has a disadvantageous effect on the efficiency 
of filling the pressure chamber. 
Similar circumstances prevail during discharge of a pressure chamber with a 
subsequent build-up of a vacuum. Here during opening of a valve a 
falling-off of the pressure peak is obtained relatively quickly, while 
falling-off of the pressure beyond that of the atmosphere, and a 
subsequent build-up of a vacuum can only be accomplished at a relatively 
high expenditure of energy, or, in the event a blower is used, by the 
process time being considerably extended. 
A pressure chamber of this type can serve both for the storage of 
compressed air and compressed gases, as well as for the separation of 
liquid materials from solid materials. 
Thus there are known, for example, devices for separating solid materials 
from liquid materials, which include a rotatably supported press 
container, which is partitioned by a flexible membrane into a pressure 
chamber and a pressing space, and wherein an inlet is associated with the 
pressure chamber for passing a pressure medium thereinto, and an outlet is 
associated with the pressing space for a liquid to be squeezed out 
therefrom, and wherein the pressure chamber is filled with compressed air 
obtained from a compressor until attainment of the compression pressure. 
Experience has shown that in an arrangement of this type a third of the air 
volume to be introduced into the pressure chamber for the purpose of 
squeezing out a compressible agricultural product such as a mash is 
required just to shift the membrane normally abutting the container wall 
under vacuum from that wall to the mash, so that the membrane makes 
contact with the mash. 
Compression of air by means of a compressor, for the purpose of causing the 
membrane to abut an agricultural product such as a mash, is not 
sufficiently efficient, and it is equally unsatisfactory to draw or suck 
off any remaining air from the pressure chamber by means of a blower 
following normal discharge of air therefrom. 
This also applies for filling or discharge of a pressure chamber for 
storage therein of gases or of air. 
If desired, such devices can be provided with an additional blower, which 
takes over the task of causing the membrane to abut the mash; devices 
using such features are known in practice. Hence it is possible to obtain 
an inlet pressure, and suctioning off of the air from the pressure 
chamber, while expending less energy than hitherto. A disadvantage here, 
however, is the longer operating time, which is increased based on several 
operating cycles. 
SUMMARY OF THE INVENTION 
It is consequently an object of the invention to devise a method and an 
apparatus for the filling and discharge of pressure chambers for the dual 
purposes of accelerating air or gas exchange, and for saving operating 
costs, so as to improve their economic performance. 
This object is attained, according to the invention, by either filling the 
pressure chamber by means of a compressor, and/or discharging the pressure 
chamber with the additional aid of a pump, such as a stream pump, which in 
turn communicates with the pressure chamber.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
Referring now to the drawing, in FIG. 1, there is shown a rotatably 
supported press container 1 mounted on a frame; the press container 1 is 
subdivided by a flexible membrane 2 into a pressure chamber 3, and a 
pressing space or squeezing compartment 4. The pressure chamber 3 is 
provided with an inlet 5 for a pressure medium, and the pressing space 4 
is provided with an outlet or discharge conduit 6 for the liquid to be 
squeezed out therefrom. 
The pressure chamber 3 communicates with a compressor 8 through a main or 
inlet conduit 7, through which the compressed air passes. A control 
conduit 9 for the compressed air is coupled to the main conduit 7 at a 
junction of the main or inlet conduit 7 with the compressor 8. Downstream 
of the compressor 8 there are disposed shut-off means, such as a shut-off 
member 10. Passage of the pressure medium into the pressure chamber 3 is 
accomplished through a (non-illustrated) rotatable inlet. 
Air or gas pumping means, such as two stream pumps 11 and 12 are disposed 
in the circuit of the control conduit 9, which, in turn, communicates with 
the pressure chamber 3. The pressure stream pump 11 serves to fill the 
pressure chamber 3, while the vacuum stream pump 12 serves to discharge 
the pressure chamber. For alternating operation of the stream pumps 11 and 
12, the control conduit 9 for compressed air is subdivided, or branches 
out into two parallel segments 15 and 16, associated with the stream pumps 
11 and 12, respectively; the segments 15 and 16 are in turn provided with 
alternately operating shut-off valves 13 and 14, which cooperate with one 
another. The stream pumps 11 and 12 are so constructed that their outlets, 
or downstream openings, communicate with one another. So as to attain an 
optimal efficiency, the stream pump 11 required to fill the pressure 
chamber 3 is located nearer to the compressor 8 in the control conduit 9 
than pressure the stream pump 12. The stream pump 11, based on its 
construction, which will be explained in further detail in connection with 
FIG. 2, draws in air from the atmosphere and consequently generates 
thereby relatively large volumes of air, which are destined to fill the 
pressure chamber 3. 
The vacuum stream pump 12 is provided to discharge a certain amount of 
remaining air from the pressure chamber 3, and is located closer to the 
pressure chamber 3 than filling stream pump 11, which is required to fill 
that pressure chamber. 
A pump conduit 17 for filling the pressure chamber 3 with compressed air or 
gas, or discharging air or gas from the pressure chamber 3 includes 
shut-off means, such as a shut-off element or valve 18, which is 
maintained open when the stream pumps 11 and 12 are operating. Operation 
of the shut-off element or valve 18 can be accomplished by means of a 
switching valve 19 operable through the control conduit 9. 
In order to connect the pump conduit 17 to the pressure chamber 3, the 
rotatable inlet represented by the main inlet conduit 7 is made use of. 
In order to further lower the operating costs a blower 20 communicates with 
the main inlet conduit 7 during the pressure-chamber filling phase, or 
during the mash-loosening phase, when generating a vacuum in the pressure 
chamber 3. A connecting conduit 26 connected between the main inlet 
conduit 7 and the blower 20 can be closed by valve 25, if needed, namely 
during filling of the pressure chamber 3 with air or gas from any suitable 
source such as the atmosphere. 
In FIG. 2 there is shown a an embodiment of the stream pumps 11 and 12 as 
used, for all intents and purposes, in practice; FIG. 2 also shows how the 
stream pumps are disposed, together with the shut-off valve or element 18, 
on the press container 1. The stream pump 11 used to fill the pressure 
chamber 3 communicates with a segment 15 of the control conduit 9 for the 
compressed air. The compressed air enters a ring-shaped distributor 21, 
and passes therefrom through an annular nozzle 22, in which it is 
rerouted, through an outlet 23 into the pressure chamber 3. During this 
process a low or under-pressure zone arises in the annular nozzle 22, 
through which the surrounding air is drawn in, and wherefrom it is passed 
through the outlet 23 into the pressure chamber 3. 
During discharge of the pressure chamber 3 the stream pump 12 communicating 
with the segment 16 of the control conduit 9 is operated by compressed air 
from the compressor 8, while the stream pump 11 remains motionless without 
any compressed air being supplied thereto. A volume of air still remaining 
in the pressure chamber 3 following discharge thereof is suctioned off 
from the pressure chamber 3 by means of the stream pump 12. 
As has already been mentioned before, after a certain pressure has been 
reached in the pressure chamber 3, the stream pump 11 is shut off, and the 
shut-off element 18 is closed. Closure of the shut-off element 18 is 
accomplished in a self-actuating manner by means of force-storage means, 
such as a spring, while the shut-off element 18 is opened by means of the 
switching valve 19 connected to the control conduit 9. 
The stream pumps 11 and 12 are connected tightly, on one hand, to the 
shut-off element 18, such as a stopcock, which, in turn is secured to the 
flanges of the press container 1, and are connected tightly, on the other 
hand, to the control conduit 9. No special provisions for mounting are 
made. Element 24 is a connector serving to connect a conduit passing 
compressed air to the stopcock 18 for the actuation thereof. 
Operation 
In a device for separating liquid materials from solid materials by means 
of a press of the aforedescribed kind, the device, following preliminary 
dejuicing of the press filled with mash, operates as follows: 
Starting from a state of the press being filled with mash, the press cycle 
commences after dejuicing, namely the shut-off member 10 is closed, the 
compressed air from the compressor 8 streams through the control conduit 
9, and through the open shut-off valve 13 into the stream pump 11, while 
the shut-off valve 14 is closed. The stream pump 11 draws in air from the 
atmosphere, which passes into the pump conduit 17, while being mixed with 
the compressed air from the compressor 8, and passes therefrom through the 
open shut-off element 18 into the pressure chamber 3 of the 
press-container 1, the switching valve 19 having been actuated to open the 
shut-off element 18. The membrane 2 is thereby detached from the wall of 
the press-container 1, and is caused to abut the mash. 
For this process designated as a first phase or stage in the press cycle, 
about 33% of the total air volume, needed for the pressing operation at a 
pressure of about 2 bars, is required. 
Referred to the compressed air volume generated by the compressor, about 
20% of the required pre-filling volume is supplied by means of the stream 
pump for the preliminary filling of the pressure chamber. 
So as to aid this filling process, the blower 20 can be used to operate in 
a direction opposite to the direction indicated, be it through a change in 
the direction of rotation, or through a change of the arrangement of the 
conduit. 
When, following a signal from the pressure chamber,a certain pressure in 
the pressure chamber 3 has been attained, the shut-off element 18, and 
optionally a pushing valve 25, as well as the shut-off valve 13, are 
closed, the shut-off valve 14 being already closed. The air compressed by 
the compressor 8 now passes through the shut-off member 10, which has in 
the meantime been opened, to the pressure chamber 3, and initiates 
pressing of the mash contents by building up the pressure in the pressure 
chamber 3. 
Following a predetermined dwelling time of the membrane 2 under pressure, 
the pressure chamber 3 is again relieved from pressure or stress by 
discharge of the compressed air therefrom. By opening of the pushing valve 
25, the air or gas streams off to the atmosphere through line 20 and the 
blower 20. 
In order to shorten the air or gas discharge time, the shut-off element or 
valve 18 could also be opened, so that the air can then stream off from 
the pressure chamber 3 through the stream pump 11 to the atmosphere. 
Prior to the passage of atmospheric pressure into the pressure chamber 3, 
or at an overpressure of about 0.2 bars, the shut-off member 10, and the 
shut-off valve 13 are closed, while the shut-off valve 14 and the shut-off 
element or valve 18 are opened, the shut-off valve 18 being opened with 
the aid of the switching valve 19. The compressed air from the compressor 
8 now reaches the stream pump 12, which draws off any remaining air volume 
from the pressure chamber 3, and passes it to the atmosphere. For this 
purpose the blower 20 is also made operative, and after a given reduced 
pressure has been reached in the pressure chamber 3, the stream pump 12 is 
switched off, and the shut-off valve 14, as well as the shut-off element 
are closed. 
Subsequently a pre-set, reduced pressure triggers the loosening phase of 
the membrane, during which loosening phase the press-container 1 is 
rotated. 
These operating cycles are repeated several times according to a programmed 
process control. 
It would, of course, also be possible to carry out the principles of the 
process without any particular additional measures by means of a liquid 
pressure medium. 
It is to be understood that it is not desired that the present invention be 
limited to the exact details of construction shown and described, for 
obvious modifications will occur to a person skilled in the art.