Liquid purification or separation – Processes – Liquid/liquid solvent or colloidal extraction or diffusing...
Reexamination Certificate
2000-10-31
2002-10-22
Fortuna, Ana (Department: 1723)
Liquid purification or separation
Processes
Liquid/liquid solvent or colloidal extraction or diffusing...
C210S195200, C210S257200, C210S416100
Reexamination Certificate
active
06468431
ABSTRACT:
TECHNICAL FIELD
The present invention relates generally to a reverse osmosis systems for desalinization of water, and more specifically, to an interstage pressure boosting system of a multiple stage reverse osmosis system.
BACKGROUND OF THE INVENTION
Reverse osmosis (RO) is a process widely used for desalinization of water. Reverse osmosis membranes are contained in a process chamber into which pressurized feedwater is admitted. A portion of the pressurized water permeates across the membrane and exits the process chamber as purified water at a low pressure and is referred to as permeate. The remainder of the water, still at high pressure, exits the process chamber and is referred to as a concentrate.
During the life of a membrane the fluid pressure must be adjusted slightly to ensure optimum operation. Without such optimization, the system will needlessly use energy or not produce the desired amount of permeate.
The concentrate from reverse osmosis systems may be used in three ways. The first way is to dispose of the concentrate by throttling the pressure with an orifice plate. The second way in which the high pressure concentrate may be used is to drive an energy recovery turbine (ERT). The output of the turbine is used to drive the feedwater into the system. The use of a turbine reduces the net energy consumption of the system. A third way in which to use the high pressure concentrate is to increase the pressure of the high level concentrate and admit the concentrate to a second reverse osmosis chamber to extract additional permeate. The high pressure concentrate from the second reverse osmosis chamber may then be handled in the above-mentioned three manners.
Referring now to
FIG. 1
, a known reverse osmosis system
10
is illustrated having a feed pump
12
which is driven by a motor
14
to pressurize feed fluid from a feed input
16
. Pressurized fluid leaves pump
12
through an output
18
and enters a first reverse osmosis process chamber
20
. The process chamber
20
has a permeate header
22
through which permeate is removed from the reverse osmosis chamber
20
. Reverse osmosis chamber
20
also has a concentrate output
24
which removes concentrate from the reverse osmosis chamber
20
at a high pressure. The concentrate output
24
is coupled to a booster pump
26
which is driven by a booster pump motor
28
. The booster pump
26
with booster pump motor
28
boosts the pressure of the concentrate before it is admitted into a second reverse osmosis chamber
30
. The reverse osmosis chamber
30
has a permeate output
32
coupled to permeate header
22
. A concentrate output
34
is coupled to an energy recovery turbine
36
which is coupled to a shaft
38
common to both motor
14
and pump
12
. In this manner, some of the load of pump
12
is relieved by energy recovery turbine
36
.
Another known arrangement similar to
FIG. 1
is illustrated having the same components illustrated with the same reference numerals. In this embodiment, second energy recovery turbine
40
is coupled to concentrate output
34
is used to drive booster pump
26
on a common shaft
42
. The energy recovery turbine
36
is thus used to recover any remaining energy in the concentrate.
One problem in known systems is that energy-wasting throttle valves and bypass lines are typically used to control the flow and the pressure of fluids to and from the reverse osmosis chambers. It would therefore be desirable to provide a reverse osmosis system that allows independent control of the flow and pressure of each reverse osmosis chamber without the use of energy wasting throttle valves and bypass lines.
SUMMARY OF THE INVENTION
It is therefore one object of the invention to provide a reverse osmosis system that may easily and energy-efficiently be adjusted to operate at its design capacity despite changes in the membrane characteristics due to fouling or other operating parameters.
In one aspect of the invention, a common shaft is used to rotatably hold a first pump fluidically coupled to the first feed inlet, a pump motor, a first energy recovery turbine fluidically coupled to the first concentrate outlet, and a second energy recovery turbine fluidically coupled to the second concentrate outlet. A second pump may also be coupled to the first concentrate outlet to increase the pressure of the first concentrate prior to entering the second process chamber.
In a further aspect of the invention, the second pump may be rotatably coupled to a booster pump motor. In another aspect of the invention, the second pump may be coupled to a third energy recovery device that is fluidically coupled to the second concentrate outlet.
In a further aspect of the invention, a method for operating a reverse osmosis system comprises the steps of:
providing energy from a first reverse osmosis process chamber to boost the pressure of feed fluid to the first reverse osmosis process chamber;
providing energy from a second process chamber to boost the pressure of feed fluid to a first process chamber; and,
collecting permeate form the first process chamber and the second reverse osmosis process chamber.
One advantage of the present invention is that energy-wasting throttle valves and bypass lines have been eliminated from the reverse osmosis process. Another advantage of the invention is that more energy is recovered from the process lowering the overall cost of operating such a process.
Other objects and features of the present invention will become apparent when viewed in light of the detailed description of the preferred embodiment when taken in conjunction with the attached drawings and appended claims.
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Fortuna Ana
Mierzwa Kevin G.
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