FIELD OF INVENTION:
The present invention generally relates to water treatment system for submarine
and more particularly relates to a system of treating sea water to produce
potable water for submarine application.
BACKGROUND:
For deep sea application, generating potable water for the operating personnel is
a tough task. Many methods using various types of membranes are being
adopted to produce the required water. Some of them use thermal types where
heating, evaporation and condensation are involved. These methods require
facilities for heating and also large floor space. The space availability inside a
submarine is at a premium and a compact system, meeting all the naval
standard/sea conditions is the requirement. In a submarine, potable water is
being generated from sea water using Disc and tube membrane as per the prior
art. In order to enhance the salt rejection, energy efficiency, ability to handle
varying temperature and pressure of feed sea water and to facilitate easy
installation and replacement of the membranes, a novel method has been
invented for generating potable water from sea water for submarine application.

The present invention discloses an innovative method to treat the sea water
using spiral wound polyamide RO (Reverse Osmosis) membrane.
The present invention is a highly compact skid mounted Sea Water Reverse
Osmosis (SWRO) system. It consists of a bag filter, pumps, RO membranes,
instruments, electrical system, piping and valves as per the Process and Flow
Diagram enclosed.
OBJECTS OF THE INVENTION:
One object of the invention is to provide an improved system as compared to the
prior art and a method of treatment of sea water to generate potable water, and
also the system requiring minimum space.
Another object of the invention is for the system to deliver a constant quantity of
potable water under constant pressure irrespective of the upstream pressure
condition.
Yet another object of the invention is to reject salts to a high degree (99.6%) and
to provide a system better equipped to withstand corrosion, easy to operate,
requiring very little maintenance.

BRIEF DESCRIPTION OF ACCOMPANYING DRAWING;
Figure 1: - A flow diagram shows the working of the method.
DESCRIPTION;
The invention will now be described in an exemplary embodiment as depicted in
the accompanying drawings. There can however be other embodiments of the
same invention, all of which are deemed covered by this description. The present
invention consists of highly compact, skid mounted SWRO (Sea Water Reverse
Osmosis) system. This novel system of treating sea water to produce potable
water for submarine application have following distinguishing features over prior
art.
1. The present invention is for a smaller foot print for the system as
compared to prior art, and thus saving valuable space in the submarine,
2. The invention uses state of the art technology with proven spiral wound
Polyamide membrane (suitable for Reverse Osmosis application) and has
higher salt rejection capability than the existing membrane in the prior
art.

3. The product water (permeate) quality achieved from this invention is
around 150ppm against the quality of lOOOppm being achieved from the
prior art; thus permeate quality is six times better than the quality of
permeate achieved through prior art.
4. Substantial reduction in noise levels during the operation of the system as
compared to the prior art (because the present invention is using direct
drive for the high pressure pump application as compared to the belt drive
used in the prior art), is a very significant technical achievement for
submarine application. This also reduces maintenance requirements.
5. Aesthetic look, easy layout and facilitating clear identification of various
pipe lines in the present system have resulted in a highly compact system
using SS 316 double compression ferrule fittings and tubes against the
rubber/braided hose in the prior art.
It consists of a bag filter, pumps, RO membrane, instruments electrical system,
piping and valves as per the process and flow diagram given in Figure 1.

Figure 1 depicts the inventive system in accordance with the invention, wherein
a constant quantity of sea water is delivered to the submarine, at a constant
pressure irrespective of upstream pressure condition through a pressure
regulating valve (01).
A bag filter (02) prevents accidental passage of any foreign material to the raw
water feed pump (03) and membrane. This micron guard filter (02) otherwise
known as Bag Filter is made up of polypropylene material and has micron level
pore to have effective filtration. Its housing is made of tough PP (polypropylene)
to withstand corrosive nature of sea water.
This is a stage 1 filter. A feed pump (03) supplies required feed water to the RO
(Reverse Osmosis) membrane (07) through cartridge filter (04). Body of this
pump (03) is made of SS316 material and all the wetted components are of
titanium material which is highly corrosion resistant and suitable for sea water
application.
A micron cartridge filter (04) which is a second stage guard filter to prevent the
accidental passage of any foreign materials to the High pressure feed pump and
membrane. Filter element is melt blown, depth type Polypropylene material and
has a micron level pore to have effective filtration. Its housing is made of tough
PP to withstand the corrosive nature of the sea water.

A high pressure pump (05) raises the pressure of the feed sea water to a level
much higher than osmotic pressure mostly of the order of 50 to 70 bar. Such
pumps are provided with pulsation dampener to minimize the pulse and to
ensure continuous supply of water. Additional pressure switch, safety relief valve
etc are provided at the pump discharge for safe operation of the plant. The
discharge from the high pressure pump (05) is fed to a membrane pressure
vessel (06) having a RO membrane element (07) inside. RO (Reverse Osmosis)
membrane element is a spiral wound composite polyamide membrane element of
4 inch diameter and 40 inch long, having high salt rejection capacity (99.6%) to
separate potable water from the sea water.
The membrane pressure vessel is a specially designed FRP (Fibre Reinforced
Plastic) vessel to with stand the high pressure encountered in the system. It has
a glossy inside surface and associated components such as end plates, brine
seal O rings, Adapters etc to form a complete assembly. A brine control valve (08)
is used to regulate the pressure of feed water in the system. Its function and
control is of high importance to get the desired quality and recovery. It is made
of SS 316 material.

A lime stone filter (09) is provided to enhance the pH of the RO permeate water
to desired level. It is filled with gravels of calcium carbonate. As the RO permeate
water passes through this filter, it picks up the calcium and its pH value gets
enhanced. This process gives good taste to the potable water.
There is also a UV disinfection system (10) to protect the RO permeate against
the development of bacteria and other harmful germs. It works on the principle
of UV radiation using a UV lamp. It is simple in construction and operation.
Operation of this RO system is controlled through a local PLC (Programmable
Logic Control) (11) mounted in the system. It is simple in design and
construction and easy to programme to suit the varying requirements. All the
state of the art controls and instrumentation are built in the system to make it
user friendly and easy to handle.
Solenoid valves (not shown) are provided to facilitate effective periodical flushing
of RO membrane in order to reduce the scaling of brine side of RO membrane
and auto dump, if the RO permeate quality is beyond acceptable limits.
Provision is also available to carry out the chemical clearing of RO membrane to
restore its performance, as and when required. The entire pipelines are of
Seamless SS 316 material and fittings are Swagelok double compression type.
WE CLAIM;
1. An improved system of treating sea water to produce potable water for
submarine application comprises of: -
• A pressure regulating valve (01)
• A bag filter (02)
• A feed pump (03)
• A micron cartridge filter (04)
• A high pressure pump (05)
• A membrane pressure vessel (06)
• A lime stone filter (09)
• A brine control valve (08)
• A uv disinfection system (10)
• A PLC system (11)
• Solenoid valves (12) and
• Seamless pipeline (13),
Characterized in that potable water is generated from sea water through
spiral wound, composite polyamide membrane suitable for reverse osmosis
application of suitable diameter and length having high salt rejection
capability.
2. A system as claimed in claim 1, wherein the pressure regulating valve
(01) delivers a constant quantity of sea water at a constant pressure
irrespective of the upstream pressure condition.
3. A system as claimed in claim 1, wherein the bag filter is (02) made of
polypropylene material (PP) and has a micron level pore for effective
filtration and a housing made of tough PP (Polypropylene) material to
withstand corrosive nature of sea water.
4. The bag filter as claimed in claim 3, prevents the accidental passage of
any foreign material to the raw water feed pump (03) and RO membrane
(07).
5. A system as claimed in claim 1, wherein raw feed pump (03) is self
aligned, compact, vertical and centrifugal which supplies required feed
water to the RO membrane (07) through cartridge filter (04).
6. The raw water feed pump (03) as claimed in claim 5, wherein the body of
the pump is made of SS316 material and all the wetted components are
made of titanium material which is highly corrosion resistant against sea
water.
7. A system as claimed in claim 1, wherein the micron cartridge filter (04) is
a second stage guard filter to prevent the accidental passage of any
foreign material to the high pressure field pump (05) and RO membrane
(07).
8. The filter as claimed in claim 7, wherein the filter element is melt blown,
depth type polypropylene (PP) material and has micron level pores.
9. The filter as claimed in claim 8, wherein the body is made of tough PP to
withstand corrosive nature of sea water.
10. A system as claimed in claim 1, wherein the high pressure pump (05) is a
Triplex Plunger type Reciprocating pump of SS316 material with a direct
driven motor fixed on a common base frame.
11. The high pressure pump as claimed in claim 10, wherein the pump
raises the pressure of feed sea water to a level much higher than osmotic
pressure.
12. The high pressure pump as claimed in claim 10, wherein the pump is
provided with pulsation dampener to minimize the pulse and ensure
continuous supply of water.
13. The high pressure pump as claimed in claim 10, wherein a pressure
switch and a safety relief valve are provided at the pump discharge for
the safe operation of the plant.
14. A system as claimed in claim 1, wherein the membrane pressure vessel
(06) made with FRP (Fibre Reinforced Plastic) to withstand the high
pressure encountered in the system.
15. A system as claimed in claim 14, wherein the vessel has a glossy inside
surface and Brine Seal, O rings, Adapter to form complete assembly.
16. A system as claimed in claim 1, wherein the Brine control valve (08) is a
needle valve to regulate the pressure of feed water in the system.
17. The brine control valve as claimed in claim 1, which is made of SS316
material.
18. A system as claimed in claim 1, wherein a lime stone filter (09) is
provided to enhance the pH of the RO permeates water.
19. A system as claimed in claim 18, wherein the lime stone filter is filled
with gravels of calcium carbonate and the RO permeate water passing
through this filter picks up the calcium whereby its pH is enhanced
which adds to the taste of water.
20. A system as claimed in claim 1, wherein the UV disinfection system (10)
protects RO permeate against the development of bacteria and other
harmful germs.
21. A system as claimed in claim 1, wherein the PLC (Programmable Logic
Controller) (11) controls the operation of the RO system through a local
PLC mounted on the system.
22. A system as claimed in claim 1, wherein solenoid valves (12) are provided
to facilitate effective periodical flushing of RO membrane and auto dump
features are provided for discarding the permeate.
23. A system as claimed in claim 1, wherein pipelines are of seamless SS316
having double compression ferrule fittings and tubes.
24. A method for treatment of sea water for producing potable water
comprising steps of:-
• delivering a constant quantity of sea water at a constant pressure,
irrespective of upstream pressure conditions,
• preventing accidental passage of any foreign material to the raw
water feed pump and membrane through filter (02),
• pumping raw feed water to the RO membrane (07) by raw feed water
pump (03) through micron cartridge filter (04),
• raising the pressure of feed sea water to a level much higher than
osmotic pressure, by high pressure pump,
• passing the high pressure feed water through RO membrane
element for salt rejection (07),
• regulating the pressure of feed sea water through brine control valve
for desired quality and recovery (08),
• enhancing the pH of the RO permeate water to the desired level by
passing through lime stone filter (09),
• disinfecting the RO permeate against development of bacteria and
other harmful germ through uv radiation using uv lamp (10),
• controlling the RO system through a PLC (Programmable Logic
Controller) (11) to suit the varying requirement of the system and
• providing instrumentation facilities for quantitative measurement of
various parameters during operation of the system.

An improved system of treating sea water to produce potable water comprising:
a pressure regulating valve (01); a bag filter (02); a feed pump (03); a micron
cartridge filter (04); a high pressure pump (05); a membrane pressure vessel (06);
a lime stone filter (09); a brine control valve (08); a uv disinfection system (10); a
PLC system (11); solenoid valves (12) and seamless pipeline (13).
The present system is for a smaller foot print as compared to prior art and saves
valuable space in the submarine. This system uses state of the art technology
with proven spiral wound polyamide membrane which is suitable for reverse
Osmosis application and has high salt rejection capability than the existing
membranes. The product quality (permeate) as achieved from the system is
around 150 ppm to 1000 ppm which is six times better than the achieved quality
in prior art. Substantial reduction in noise levels by using direct drive for the
high pressure pump application against the belt drive, used in prior art which
also reduces maintenance requirements. The system is highly compact and uses
SS 316 with double compression ferrule fittings against rubber and braided
hose.