Apparatus for processing liquids such as water and the like by reverse osmosis

An apparatus for processing liquids such as water or the like by means of a reverse osmosis device has a main pump which provides an entrance pressure to the reverse osmosis device in connection with a throttle. In order to avoid any losses of energy, another pump is connected to the main pump. Via a rigid shaft, a turbine is connected to the other pump which turbine receives the high pressure located in the concentrate and releases it to the other pump.

BACKGROUND OF THE INVENTION 
The present invention relates to an apparatus for processing liquids such 
as water and the like by reverse osmosis. 
In the art of processing liquids, it has been already proposed to use a 
reverse osmosis device for desalinization and decoloration of drinking 
water, industrial water or waste water as well as for upgrading of aqueous 
solutions and of waste waters in order to remove noxious matters. 
Furthermore, the reverse osmosis is employed in the recovering of metals 
during the concentrating of solutions. 
Reverse osmosis is the transmuted natural principle of the osmosis utilized 
for technical applications. 
In the osmosis, the equalization of different concentrations of solution 
occurs through semi-permeable membranes. The solution pressure of 
different concentrations is designated as osmotic pressure by which the 
water molecules try to dilute the concentrated solution. The osmotic 
process is terminated when an equilibrium is obtained. 
In opposition to this, the reverse osmosis tries to counteract the dilution 
of the concentrating phase in order to achieve a further concentration 
wherein a higher pressure must be used than the present osmotic pressure. 
In this case, the semi-permeable membrane acts as a carrier for all 
dissolved substances so that a pure liquid the permeate is obtained at the 
outlet. 
The pressure required for the reverse osmosis is produced by increasing the 
pressure, for example, by interposing a pump ahead of the reverse osmosis 
device. Although this principle seems to be sound, there is the 
disadvantage of a rather remarkable loss of energy since the pressure of 
the concentrate discharge is not utilized any more and therefore gets 
lost. This, however, undesirably increases the expenses of the apparatus. 
The German specification DE-OS No. 2547446 describes method for 
purification of waste water solutions wherein the pressure energy in the 
concentrate is recovered by expanding the concentrate in a turbine which 
is directly connected to a pump. The disadvantage of the specification is, 
however, that the recovered energy is not sufficient to maintain or 
provide the required pressure for the solution to be treated when entering 
the reverse osmosis unit. Thus, the pump must be continuously in 
operation. 
SUMMARY OF THE INVENTION 
Accordingly, it is an object of the present invention to overcome the 
disadvantages of the prior art. 
A more particular object of the invention is to provide an apparatus for 
processing liquid such as water and the like by using reverse osmosis 
wherein the energy located in the concentrate discharge is recovered and 
returned to the apparatus again. 
Another object of the invention is to provide such an apparatus which is 
very simple and inexpensive in its construction. 
A concomitant object of the invention is to provide such an apparatus as 
mentioned hereinbefore, which is highly reliable and requires only minimal 
servicing and upkeep. 
Pursuant to the above objects and others which will become apparent 
hereafter, a feature of the invention resides in an apparatus for 
processing liquids by reverse osmosis which, briefly stated, comprises a 
first pump which is connected to the reverse osmosis device thereby 
achieving that the concentrate is introduced with a certain pressure, a 
turbine which is driven by the concentrate discharged from the reverse 
osmosis device, and a second pump which is connected to the turbine as 
well as to the first pump and being associated to a disconnectable motor. 
Another feature of the present invention is that a rigid shaft connects the 
turbine with the second pump so that the disconnectible motor serves only 
as a starting motor. Therefore, the highly pressurized concentrate 
discharge releases its energy to the second pump via the turbine thereby 
recovering a major part of the energy for producing the pressure of the 
solution to be treated. Thus, the first pump has only to compensate the 
losses of operation and the losses from the reverse osmosis device. 
The novel features which are considered as characteristic for the invention 
are set forth in particular in the appended claims. The invention itself, 
however, both as to its construction and its method of operation, together 
with additional objects and advantages thereof, will be best understood 
from the following description of specific embodiments when read in 
connection with the accompanying drawing.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
The FIGURE illustrates an embodiment of the apparatus for processing 
liquids according to the present invention, wherein the concentrated 
solution is fed to a first pump 2 via an associated duct 1, the pump being 
driven by an electric motor 4 via a centrifugal clutch 3. Motor 4 is only 
used as a starting motor and can be discharged, for example through the 
centrifugal clutch 3. Outgoing from the pump 2 is a duct 5 which leads to 
a main or second pump 6 driven by a motor 8 via a clutch 7. From the main 
pump 6, there is outgoing a duct 9. For the purpose of optimization of the 
entire apparatus, the second pump 6, which is for example a centrifugal 
pump, is controllable in its speed so that the pressure of the solution to 
be treated is adjustable. Thus, a certain amount of concentrated solution 
having a certain pressure P1 is supplied to the duct 9 which is connected 
to a throttle 10 or the like, for example a bypass control, from which a 
duct 9' is leading to a reverse osmosis device 11. Through the throttle, 
the pressure P2 of the concentrated solution in the duct 9' is adjusted in 
such a manner that it corresponds to the required entrance pressure of the 
reverse osmosis device 11. It is to be noted that the arrangement of the 
pumps 2 and 6 is interchangeable. The pure water or the permeate is 
discharged in a depressurized state from the reverse osmosis device via a 
duct 12. Thus, for example 30% are discharged as depressurized permeate 
when considering the concentrated solution supplied to the device 11 as 
100%. The remaining 70% of the solution are discharged from the device 11 
as concentrate of high pressure via a duct 13 and are guided through a 
turbine 15 where a major part of the pressure energy located in the 
concentrate is received and released to the pump 2 via a rigid shaft 16 or 
the like connecting the turbine with the pump 2. The concentrate is 
discharged in a depressurized state through a duct 17. Furthermore, duct 
13 is provided with a bypass duct 13' having a shutoff valve 14. 
In a desalinization apparatus, concentrated solution having a pressure of 
P2=P1-.DELTA.P1 of approximately 60 to 70 bar is supplied to the reverse 
osmosis device 11 through the duct 9'. The concentrated solution leaves 
the reverse osmosis device 11 with a pressure of P3=P2-.DELTA.P2. Thus, 
70% of this pressure energy are fed to the turbine 15 which recovers a 
major part of the energy and returns it to the cycle of the apparatus. 
Thus, the pump 6 has to compensate only losses of flow and losses of 
pressure occurring in the reverse osmosis device 11. 
It will be understood that each of the elements described above, or two or 
more together, may also find a useful application in other types of 
constructions differing from the types described above. 
While the invention has been illustrated and described as embodied in an 
apparatus for processing liquids such as water or the like, it is not 
intended to be limited to the details shown since various modifications 
and structural changes may be made without departing in any way from the 
spirit of the present invention. 
Without further analysis, the foregoing will so fully reveal the gist of 
the present invention that others can by applying current knowledge 
readily adapt it for various applications without omitting features that, 
from the standpoint of prior art, fairly constitute essential 
characteristics of the generic or specific aspects of this invention.