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Svanehj Deepwell Cargo PumpsVariable speed control for product/chemical tankers
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Speed regulated cargo systemNew system for future demands
Variable speed control with frequency converters means energy saving and noisereduction.As a leading pump manufacturer Hamworthy Svanehj A/S
has developed an electrically driven, variable speed
regulated cargo system to meet the growing demands with
regard to environment and to achieve optimum perfor-
mance with various cargo densities and viscosities.
The fact that more and more shipowners select diesel-
electric propulsion for their tanker newbuildings makes the
choice of electrically driven cargo system natural.
Easy installation, low discharging noise level, and low
maintenance costs are important factors in building and
operating the vessel.
The system operates with a standard frequency converter
driving the explosion-proof electric motor at the pump.
The frequency convertersare delivered in a converter
switchboard, fully wired and ready to be placed in the
switchboard room.
Local controlof the cargo system takes place from the
converter switchboard front.
The converter switchboard is made with interface for
remote control panel or interface to the Ships Control
System (SCS).
The cargo system is designed individually to suit any tanker.
Integration of motor starters and speed regulation for
ballast pump, tank wash pumps and bow thruster in
converter switchboard is possible.
The electrically driven, variable speed cargo system is
available with certificate from any classification society, e.g.
DNV - LRS - GL - ABS - BV - KR - RS - NK - CCS andR INA.
Variable speed and energy savings
Several things indicate that a cargo pump should be
variable speed regulated:
- Soft starts and stops give a low pressure influen ce at pipes,
valves, gaskets and coupling in the discharge system.
- At cargoes with different densities it is possibel in each
case to optimize the discharge time. It is always possible
to have full motor load or full allowable pressure on the
manifold.
- Low noise from cargo system while discharging.
- Energy savings; discharge takes place at fully open valves.
The energy conservation can be divided into environmental
and economic aspects.
Environmentally, the energy conservation consists of less
pollution, which today is a factor highly weighted (green
ship/minor degree of CO2 emissions).
By means of the frequency converter it is possible to adjust
the speed for optimum pressure and flow, resulting in
considerable physical and economic energy savings, which
contribute to increasing the owner's return on investment.
The frequency operation system can be divided into two
groups.
The reason for this is that the classification societies divide
the ships into zones.
1.components for non-hazardous area
2.components for hazardous area covering
zone 2 - 1 and 0.
Non-hazardous areas
This area covers normally the accommodation, wheelhouse,
cargo control room, engine room, forepeak etc.
Components mounted in this area are e.g. frequency
converters, control panel and remote panel.
Hazardous area
The other areas are classified in different zones depending
on the classification rules for each type of ship, but usually
the pump room will be zone 0 and the deck will be zone 1.
Zone 2 covers also the deck depending on the rules of the
classification society in question.
Zone 0: Permanent presence of explosive atmosphere.
Motors prohibited (normally pump room).
Zone 1:Incident presence of explosive atmosphere in
normal duty (normally deck area according
to classification rules).
Zone 2: Presence only by accident (not in normal duty).
Electrical apparatus are divided into two main grou ps, mining
and other applications.
Group I: Apparatus for coal mines.
Group II: Apparatus for explosive atmosphere
other than mines.
Group II is subdivided according to the severity of the environ-
ment.
IIA IIC is the highest rating; a motor from one of
the higher categories can also be used in a
IIB lower category environment.
IIC
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Combustible gas vapour and explosion-protected electrical
equipment are divided into six temperature classes
according to the ignition temperature of the gas or vapour
and the maximum surface temperature of the equipment.
The temperature classes are T1 - T2 - T3 - T4 - T5 and T6 as
standard. Svanehj use temperature class T4, which covers
max. permitted equipment temperature 135C.
Svanehj use a standard motor with
explosion class EEXdeIICT4
EEX - means that the equipment complies
with the European EN standard.
d - indicates flameproof enclosure
e - enclosure "Increased safety" for
terminal box.
IIC - indicates that the equipment has been
tested and classified in gas group IIC.
T4 - indicates that the surface temperature
of the equipment does not exceed 135C.
Screened cables
Screened cables are used as control cables and motor cables.
Control cables are screened for electromagnetic
compatibility (EMC) reasons, to keep an electrical noise
impulse away from the control system.
Motor cables are screened for two reasons.
The first reason is with regard to safety, because the cable
is drawn in hazardous area (zone 1).
The second reason is to avoid the EMC interference to
electrical instrument mounted near the cables.
(The electrical noise is always kept inside the motor cable.)
View of installation offrequency converter cabinets
Pump installation
Various sizes of frequency converters
Wiring of e-motor
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Electrically driven cargo system - with frequency converter
Svanehj's cargo system is designed for location in 3
different places:
Hazardous areas:
Deck:
Cargo pumps, electric motors, cabling
and emergency stops.
Non-hazardous areas:
Engine room or converter room:
Converter switchboard.
Cargo control room or wheelhouse:
Cargo control system or remote control panel.
From the figure above it appears that the converter
switchboard consists of several identical units.
Normally each frequency converter is one unit, and
converters of same sizes are identical units.
In the upper part of the converter switchboard there is a
common busbar, which makes it possible to have only one
common main power supply from the main switchboard.
If supply current for the cargo system exceeds 2-3000
amperes, the busbar is then often divided into two parts
resulting in two main power entries.
In front of each converter unit a maximum current breaker
is installed. When making an emergency stop, all the
current breakers will be deactivated.
To restart the cargo system after an emergency stop, a
reset must be done on each unit and all maximum current
breakers must be switched on again.
The front of each unit includes display panel, all necessary
lamps and buttons for local control and operation.
Usually there will be floating floor in the room where the
converter switchboard is installed, and all cabling will be
done from underneath the floating floor up to the
respective connections.
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Converter switchboard
The standard frequency converters are built into an IP 22
switchboard.
The switchboard is in a modular design to minimize the
physical size.
In the switchboard there is a common copper busbar to
istribute the power to each frequency converter.
Supply to the busbar is taken directly from the mai n
switchboard.
All cable connections are made from the bottom of t he
switchboard.
At delivery the converter cabinet is divided into h andy
transport sections.
Safety for cargo system
The primary safety for avoiding damage to the cargo
system is handled in the converter switchboard.
- e-motor overload protection
- maximum pressure on cargo pipe system
- emergency stop
Interface
Interface for Ships Control System or for remote c ontrol panel
consists of:
- NO/NC-signals (Normally open/normally closed)
- 4-20 mA galvanic isolated signals
- Current transformer signal
(for amperemeter in remote control panel)
Frequency converter switchboard mounted at top deck in engine room.
Remote control panel
Frequency converter control panel
Loadmaster on duty
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Frequency converter
The frequency converter is a power electronic unit, which
transforms alternating current with a fixed frequency into
an alternating current with variable frequency.
The e-motor speed depends on the frequency.
If you have a variable frequency, then you are able to
regulate the motor speed. The frequency converter has a
programmable start ramp, which makes it possible to
change the timer for the soft start.
Frequency converter
- power input
When starting the pump, there
will be no high starting current
demand to the ship generators.
The absorbed supply current will
not exceed the nominal motor
current.
If the technical data for the
generators are given, it is
possible to calculate the
harmonic disturbance from the
converter switchboard.
Frequency converter
- power output
Starting the pump, the converter
will be able to deliver a starting
current of about 2-3 times
nominal motor current.
The starting current will after
some time (normally 10 sec.) fall
to less than nominal current.
When starting up the pump, the
motor voltage will be near zero.
As speed increases, the voltage
rises towards nominal voltage.
Getting beyond nominal speed, the nominal e-motor
power will be available. It will be possible to pump liquids
with very different specific gravity and viscosity, over a
wide range.
The converter creates a nice sinusoidal current waveform in
order not to increase losses in the electric motor.
The electric motor is selected for frequency converter
operation.
Pump installation Buttons/lamps in front of the frequency converterswitchboard
Inside view of the frequency convertercabinets seen from the rear
Inside view of the frequency converter cabinets seen from in front
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Remote control - SCS control
The cargo system is controlled from either the remote
control panel or the Ships Control System (SCS).
There will be the same control possibilities, but without the
information from the frequency converter display panel.
Only the motor speed and load is available here.
If some automatic modes are wanted, they must be
programmed into the SCS.
Reliability of operation
The local facilities ensure that the ship can always be
discharged even if there is a breakdown on SCS or during
commissioning, if SCS is not yet active.
As option it is possible to make a manual cross-link
between two frequency converters so that changing to the
neighbouring converter in case of breakdown on the
converter is possible.
Frequency converter switchboard and remote control panel
In front of each frequency converter switchboard a control
panel and necessary buttons and lamps are mounted.
From here it is possible to start/stop the pump and perform
a manual discharge.
The remote control panel has the same facilities as the
frequency converter switchboard but includes also a pump
load meter as well as a speed meter.
The control consists of:
Buttons: Lamps:
- Remote control - local control - Ready
- Start pump - Pump running
- Stop pump - Thermistor fault
- Speed up - speed down - Pressure fault
- Reset fault - Converter fault
Emergency stop
In the frequency converter switchboard a common
emergency stop function is built in.
Emergency stop from deck and remote control panel will
be connected here, so a reset of the emergency
function can take place from the two locations.
Section of remote control panel Diagram showing necessary instrumentation
Emergency stop and reset button at the frequency converter switchboard.
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Hamworthy Svanehj A/SP.O. Box 30, 6 FabriksparkenDK-9230 Svenstrup J.Denmark
tel: +45 96 37 22 00fax: +45 98 38 31 56e-mail: [email protected]: www.hamworthy.com
A subsidiary of Hamworthy plc.
The manufacturer reserves the right to alter thespecification and data to incorporate improvementsin design. Certified drawings will be issued on request.
All details copyright Hamworthy plc.
HPS
1304
0307
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