Danfoss iSave 50, Руководство по эксплуатации

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Operating guide | iSave 50 - 70
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180R9357 | AQ265943679828en-00100
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IOM iSave 50 - 70 | 0
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5.12 High pressure remains after shutdown
The HP line of the RO system equipped with an iSave
can remain pressurised for a long time after
shutdown. Pressure decreases as water slowly leaks
through the iSave. If more rapid system
depressurisation is required, the system should be
bled through a suitable valve on the HP concentrate
line.trado HP.
5.13 Over-pressurisation caused by low
pressure isolation
If the low-pressure side of the iSave is blocked
and the iSave is exposed to high-pressure, there
is a risk that the iSave or the LP piping could be
damaged by over-pressurisation.
5.14 Over-pressurisation caused by the
high-pressure pump.
Discharge pressure on the pump is generated
only by the restriction in the pipelines, valves
and membranes. The pump can build up
pressure that will exceed the mechanical
strength of the membrane vessels, pipes
and other accessories. The pressure rise can be
fast and may exceed the response time for
electrical safety equipment, like pressure
switch and control loop.
5.11 CIP or membrane cleaning
The purpose of membrane cleaning is to reduce
scaling and fouling in the membranes. For optimal
performance specific chemicals are required,
depending on the cause of the pollution. After
chemical treatment the system must be
flushed with permeate.
Also see instruction “Membrane cleaning of
RO system with iSave unit” in appendix 10.3.
The flush water coming out of the membranes may
consist of a large amount of suspended inorganic
particles. It is important to assure that hese particles
must not enter the iSave as the waste product of
flushing exceed the iSave filtration.
Always check the pressure in the high-pressure
lines before making service in the HP lines or
pressurised equipment.
To prevent such over-pressurisation, appropriate
relief valves should be used and procedures should
be implemented to assure that the HP of
the iSave is protected against excess pressure.
Special attention should be given to the
pressure in the HP line (7) as the iSave may
start to cavitate when it runs at high speed
and the pressure in the P line (7) drops below 2
bargs. This can be avoided by reducing the
speed of the iSave and keeping the pressurein
the HP line at the minimum of 2 barg.
At this low pressure the iSave may only
run for a maximum of 10 minutes.
Failing to flush the iSave with fresh water before
extended shutdowns may result in extensive
biological growth and cause corrosion in the
iSave and other equipment in the RO system.
To prevent such over-pressurisation, appropriate
relief valves should be used and procedures should
be implemented to assure that the HP of the iSave is
depressurised prior to the isolation of the LP side..
5.10 Flushing
RO membranes require periodic flushing to
limit biological fouling.
There are two types of flushing: feed water
(Seawater) flush and fresh water (Permeate)
flush.
Regardless of the flush water used, the water
must be pre-filtered to the level described
in chapter 5.8. All parts of the iSave must be
flushed, i.e. LP- and HP flow channels.
Follow the guide line 180R9213 “Start and stop of
the SWRO with iSave in appendix 10.2.
It is required to flush with permeate:
• After chemical treatment
• For stop more than 1 day the iSave must be
rotated during permeate flush
• Before long time shut down
It is required to flush with fresh sea water prior to
every shut down.
To prevent such over-pressurisation, appropri-
ate relief valves should be used and proce-
dures should be implemented to safeguard
the HP and LP sides of the iSave and/or the
RO system.
5.15 Explanation of P&ID set-up
See data sheet in appendix 10.1.