U.S. patent application number 09/727676 was filed with the patent office on 2001-06-21 for energy recovery device.
Invention is credited to Elliott-Moore, Peter.
Application Number | 20010004442 09/727676 |
Document ID | / |
Family ID | 10866270 |
Filed Date | 2001-06-21 |
United States Patent
Application |
20010004442 |
Kind Code |
A1 |
Elliott-Moore, Peter |
June 21, 2001 |
Energy recovery device
Abstract
An energy recovery device comprises at least one cylinder, a
piston slidable in the cylinder, first valve means for selectively
connecting one end of the cylinder to waste liquid at a first
relatively high pressure and to drain and second valve means for
allowing feed liquid to enter the other end of the cylinder at a
second lower pressure via a feed liquid entry port and to be
discharged via a feed liquid discharge port from said other end of
the cylinder in response to movement of the piston caused by waste
liquid entering said one end of the cylinder. Also, means, such as
a rod which extends from the other end of the cylinder and into but
not through the piston, ensures that the area of the piston acting
on the feed liquid is less than the area of the piston acted upon
by the waste liquid so that the piston acts as a pressure
intensifier to discharge feed liquid through the feed liquid
discharge port at a higher pressure than the pressure of waste
liquid entering said one end of the cylinder.
Inventors: |
Elliott-Moore, Peter;
(Evesham, GB) |
Correspondence
Address: |
YOUNG & THOMPSON
745 SOUTH 23RD STREET 2ND FLOOR
ARLINGTON
VA
22202
|
Family ID: |
10866270 |
Appl. No.: |
09/727676 |
Filed: |
December 4, 2000 |
Current U.S.
Class: |
417/225 ;
417/399 |
Current CPC
Class: |
F04B 9/1176 20130101;
Y02A 20/131 20180101; B01D 61/06 20130101 |
Class at
Publication: |
417/225 ;
417/399 |
International
Class: |
F04B 017/00; F04B
035/00 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 15, 1999 |
GB |
9929508.1 |
Claims
What is claimed is:
1. An energy recovery device comprising at least one cylinder, a
piston slidable in the cylinder, first valve means for selectively
connecting one end of the cylinder to waste liquid at a first
relatively high pressure and to drain, second valve means for
allowing feed liquid to enter the other end of the cylinder at a
second lower pressure via a feed liquid entry port and to be
discharged via a feed liquid discharge port from said other end of
the cylinder in response to movement of the piston caused by waste
liquid entering said one end of the cylinder, and means ensuring
that the area of the piston acting, in use, on the feed liquid is
less than the area of the piston, in use, acted upon by the waste
liquid so that the piston acts as a pressure intensifier to
discharge feed liquid through the feed liquid discharge port at a
higher pressure than the pressure of waste liquid entering said one
end of the cylinder.
2. An energy recovery device as claimed in claim 1, wherein said
means comprises a rod extending between said other end of the
cylinder and the piston, the rod being slidable relative to said
other end of the cylinder or extending into but not through the
piston so that the piston is slidable on the rod.
3. An energy recovery device as claimed in claim 2, wherein the rod
is fixed and extends from said other end of the cylinder and into
but not through the piston.
4. An energy recovery device as claimed in claim 3, wherein the
piston is hollow and the inside of the piston communicates with the
feed liquid entry port via a passage in the fixed rod.
5. An energy recovery system as claimed in claim 1, wherein the
second valve means is in the form of non-return valves.
6. An energy recovery system as claimed in claim 5, comprising a
first non-return valve for preventing feed liquid flowing from the
cylinder through the feed liquid entry port and a second non-return
valve for preventing liquid entering the cylinder through the feed
liquid discharge port.
7. An energy recovery system as claimed in claim 6, wherein the
first and second non-return valves are in the feed liquid entry
port and the feed liquid discharge port, respectively.
8. An energy recovery system as claimed in claim 1, wherein the
first valve means comprises a spool valve having a valve housing
and a slidable valve element for controlling the flow of waste
liquid to and from the at least one cylinder.
9. An energy recovery device as claimed in claim 8, comprising at
least one pair of cylinders and a spool valve for controlling the
flow of liquid to and from both cylinders.
10. An energy recovery device as claimed in claim 9, wherein the
spool valve is arranged to connect one cylinder to waste liquid
while connecting the other cylinder to drain and vice versa.
11. An energy recovery device as claimed in claim 10, wherein one
of the of cylinders extends from the spool valve in a first
direction transverse to the axis of movement of the valve element
and the other cylinder extends from the valve housing in a second
direction transverse to the axis of movement of the valve
element.
12. An energy recovery device as claimed in claim 11, wherein the
first and second directions are opposite to one another.
13. An energy recovery device as claimed in claim 8, wherein the
slidable valve element has two axially spaced annular grooves and a
land therebetween, the two grooves being in fluid communication
with one another by passage means in the land and the land having
two axially spaced apart annular seals for cutting off the supply
of waste liquid to the grooves while the slidable valve element
moves from a position in which the grooves are in full fluid
communication with said one end of the cylinder and a position in
which the grooves are out of fluid communication with said one end
of the cylinder and vice versa.
14. An energy recovery device comprising a valve housing, a
slidable valve element in the valve housing and two cylinders
extending from the valve housing in a direction transverse to the
axis of movement of the valve element, the slidable valve element
controlling the flow of liquid to and from both cylinders.
15. An energy recovery device as claimed in claim 14, wherein the
slidable valve element is arranged to connect one cylinder to a
supply of waste liquid while connecting the other cylinder to
drain.
16. An energy recovery device in combination with reverse osmosis
equipment, the energy recovery device comprising at least one
cylinder, a piston slidable in the cylinder, first valve means for
selectively connecting one end of the cylinder to waste liquid at a
first relatively high pressure and to drain, second valve means for
allowing feed liquid to enter the other end of the cylinder at a
second lower pressure via a feed liquid entry port and to be
discharged via a feed liquid discharge port from said other end of
the cylinder in response to movement of the piston caused by waste
liquid entering said one end of the cylinder, and means ensuring
that the area of the piston acting, in use, on the feed liquid is
less than the area of the piston, in use, acted upon by the waste
liquid so that the piston acts as a pressure intensifier to
discharge feed liquid through the feed liquid discharge port at a
higher pressure than the pressure of waste liquid entering said one
end of the cylinder.
Description
[0001] This invention relates to an energy recovery device
particularly but not exclusively for use in combination with
reverse osmosis equipment such as is used, for example, in the
desalination of water.
[0002] Desalination plants are required to operate at the highest
possible efficiency in order to keep the cost of water to a
minimum. It is well known to employ energy recovery devices to
recover energy from the waste liquor of reverse osmosis equipment.
There are various known devices for recovering energy by changing
the pressure energy of the waste liquor to shaft work, such as
turbines, Pelton wheels and reverse running pumps. However, the
conversion of fluid pressure to shaft work and then back again to
fluid pressure is inherently less efficient than using fluid
pressure directly.
[0003] It is also known, such as from U.S. Pat. No. 5,306,428, to
use work exchangers to transfer the fluid pressure of the waste
liquor across a piston. However, there is a pressure drop across
the reverse osmosis equipment and known recovery systems employing
a piston to transfer the pressure of the waste liquor to feed
liquid require the use of a booster pump to raise the pressure of
the liquid exiting from the work exchanger to the inlet pressure of
the reverse osmosis equipment.
SUMMARY OF THE INVENTION
[0004] According to a first aspect of the present invention there
is provided an energy recovery device comprising at least one
cylinder, a piston slidable in the cylinder, first valve means for
selectively connecting one end of the cylinder to waste liquid at a
first relatively high pressure and to drain, second valve means for
allowing feed liquid to enter the other end of the cylinder at a
second lower pressure via a feed liquid entry port and to be
discharged via a feed liquid discharge port from the other end of
the cylinder in response to movement of the piston caused by waste
liquid entering said one end of the cylinder, and means ensuring
that the area of the piston acting, in use, on the feed liquid is
less than the area of the piston, in use, acted upon by the waste
liquid so that the piston acts as a pressure intensifier to
discharge feed liquid through the feed liquid discharge port at a
higher pressure than the pressure of waste liquid entering said one
end of the cylinder.
[0005] Preferred and/or optional features of the first aspect of
the invention are set forth in claims 2 to 13, inclusive.
[0006] According to a second aspect of the invention, there is
provided an energy recovery device comprising a valve housing, a
slidable valve element in the valve housing and two cylinders
extending from the valve housing in a direction transverse to the
axis of movement of the valve element, the slidable valve element
controlling the flow of liquid to and from both cylinders.
[0007] Preferred and/or optional features of the second aspect of
the invention are set forth in claims 15 to 17, inclusive.
[0008] According to a third aspect of the invention there is
provided an energy recovery device according to the first or the
second aspect of the invention in combination with reverse osmosis
equipment.
[0009] The invention will now be more particularly described, by
way of example, with reference to the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] FIG. 1 is a plan view of one embodiment of an energy
recovery device according to the present invention,
[0011] FIG. 2 is a section taking along line II-II of FIG. 1,
[0012] FIG. 3 is a fragmentary enlarged section of part of the
energy recovery device shown in FIG. 2, and
[0013] FIG. 4 is an enlarged fragmentary view in the direction of
arrow A in FIG. 1.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0014] Referring to the drawings, there is shown therein an energy
recovery device comprising three spool valves 10 each having a
housing 11 provided with an inlet port 12 which is connected, in
use, to a supply of waste liquid discharged from reverse osmosis
equipment used, for example, in the desalination of water and an
outlet port 13 connected to drain. Each spool valve 10 also
comprises a linear drive unit 14 for driving a slidable valve
element 9 to be described hereinafter. The three spool valves 10
are fixed together in side by side relationship by threaded rods 16
extending through the housings 11.
[0015] The energy recovery device also comprises two banks of
cylinders 15. Each bank comprises three cylinders 15, the cylinders
of one bank extending from one side of a respective housing 11 in a
direction perpendicular to the axis of movement of the linear drive
units 14 and the cylinders of the other bank extending from the
other side of a respective housing 11 in an opposite direction.
[0016] Each cylinder 15 has a port block 17 at its end remote from
its respective spool valve 10. Each port block 17 has a feed liquid
entry port 18 and a feed liquid discharge port 19.
[0017] As best shown in FIG. 2 of the drawings, each cylinder 15
comprises a tubular shell 20 mounted in a recess 21 of a respective
housing 11. An O-ring seal 22 is provided in a groove in the shell
20 and forms a seal between the housing 11 and the shell 20. The
other end of each shell 20 is mounted in a recess 23 in a
respective port block 17. A further O-ring seal 24 is provided in a
groove in the shell 20 and provides a seal between the port block
17 and the shell 20. Tie rods 25 (see FIG. 1) extend between each
valve housing 11 and each port block 17 in order to clamp each
shell 20 between a respective housing 11 and a respective port
block 17.
[0018] Each cylinder 15 contains a hollow piston 26. The end of the
piston 26 adjacent to the valve housing 11 is closed, but the other
end has an opening which receives a fixed rod 27 extending from the
centre of the port block 17. The piston 26 is slidable on the rod
27 and a seal 28 is provided between the piston 26 and the rod 27
to prevent flow of liquid between the interior of the hollow piston
26 and the annular space between the rod 27 and the shell 20.
[0019] Each housing 11 has a waste liquid inlet/outlet port 30.
[0020] Each port block 17 has a first non-return valve 31 for
preventing feed liquid flowing from the cylinder through the feed
liquid entry port 18 and a second non-return valve 32 for
preventing liquid entering the cylinder through the feed liquid
discharge port 19. The interior of the piston 26 communicates with
the feed liquid entry port 18 via a through bore 33 in the rod
27.
[0021] The linear drive unit 14 of each spool valve 10 comprises a
piston 34 and a cylinder 35. The piston 34 is connected to the
slidable valve element 9 by a rod 36 and the cylinder has two air
ports 37 and 38. The slidable valve element 9 is slidable in a
sleeve 39 contained within the housing 11. The sleeve 39 has a
first annular array of openings 40 which communicate with an
annular groove 41 in the housing 11 and this annular groove
communicates with the liquid inlet/outlet port 30 of the right hand
cylinder, as shown in FIG. 2. The sleeve has a second annular array
of openings 42. These openings 42 communicate with an annular
groove 43 of the housing 11. The annular groove 43 communicates
with the inlet port 12. The sleeve also has a third annular array
of openings 44. The openings 44 communicate with an annular groove
45 of the housing 11. This annular groove 45 communicates with the
waste liquid inlet/outlet port 30 of the left hand cylinder, as
shown in FIG. 2.
[0022] The valve element 9 has a through bore 46 which is connected
to the outlet port 13 of the spool valve 10. It also has three
lands 47, 48 and 49. The lands 46 and 48 are at opposite ends of
the valve element 9 and each have a single annular seal 50 and 51
respectively. The central land 47 has two axially spaced seals 52
and 53.
[0023] A first annular groove 54 is defined between the lands 47
and 48 and a second annular groove 55 is defined between the lands
48 and 49. These grooves are in fluid communication with one
another via passages 56 in the land 48. As shown, the annular
groove 54 communicates with the second annular array of openings 42
in the sleeve 39 and the second annular groove 55 communicates with
the third annular array of grooves 44 in the sleeve 39. This places
the left hand cylinder 15 in communication with the inlet port 12
and waste liquid discharged from the reverse osmosis equipment
flows into the left hand cylinder 15 and moves the piston 26
towards its respective port block 17 to discharge feed liquid from
the cylinder through the feed liquid discharge port 19. The rod 27
ensures that the area of the piston 26 acting on the feed liquid is
less than the area of the piston acted upon by the waste liquid so
that the piston acts as a pressure intensifier to discharge feed
liquid through the feed liquid discharge port 19 at a higher
pressure than the pressure of waste liquid entering the other end
of the cylinder. The feed liquid can therefore be fed to the
reverse osmosis equipment without the need for a booster pump.
Also, as shown, the first annular array of openings 40 communicates
with the through bore of the valve element 9 and thus with the
outlet port 13. This enables feed liquid to enter the feed liquid
entry port 18 of the right hand cylinder 15 and discharge waste
liquid from the right hand cylinder 15 to drain via the outlet port
13.
[0024] Air is then admitted to the cylinder 35 through the port 38
while port 37 is vented to atmosphere. This moves the piston 34
upwards and moves the valve element 9 to a position in which the
right hand cylinder 15 is connected to a supply of waste liquid
discharged from the reverse osmosis equipment and in which the left
hand cylinder 15 is connected to drain.
[0025] The seals 52 and 53 on the central land 48 of the valve
element 9 cut off the supply of waste liquid to the annular grooves
54 and 55 while seals 50 and 51 move across respective annular
arrays of apertures 40 and 44. This protects the seals 49 and 50
from damage.
[0026] The timing of the operation of the energy recovery device
can be varied by controlling the supply of air to the pistons
34.
[0027] The length of each cylinder 15 is, preferably, no greater
than 1.5 metres and is, typically, one metre in length. This is
much shorter than the cylinders of conventional work exchanges used
to transfer fluid pressure of the waste liquid across a piston.
[0028] The embodiment described above is given by way of example
only and various modifications will be apparent skilled in the art
without departing from the scope of the invention as defined in the
appended claims. For example, the rod 27 may be fixed relative to
the piston and may be slidable relative to the end of the cylinder
remote from the spool valve housing 11. Alternatively, instead of
the rod, the cylinder could have a stepped diameter bore receiving
a stepped diameter piston.
* * * * *