| 4 | 2010 - Schiff & Hafen

SHIPBUILDING & EQUIPMENT | CONTROL & MONITORING
Automation on gas tankers
LPG/NH 3 CARRIERS In addition to the usual nautical registrations, oil and gas tankers transporting
hazardous goods must comply with diverse additional requirements, especifi cally
regarding explosion protection. Marine Technik GmbH in Schwentinental near Kiel has specialized
in ship automation and relies on the modular Wago I/O System. A project with an automation
system for four new LPG/NH ³ tankers, built by Hyundai Mipo SY, with a load capacity of
35,000 m³, has recently been realized.
Renate Klebe-Klingemann
In order to liquefy LPG gas at
20°C, it must be exposed to
very high pressure. The walls
in these tanks reach a thickness
of 8 to 20 cm. The monitoring
of the operating conditions
and the alarm therefore play an
important role in the ship’s automation
system.
Marine Technik planned and
developed the systems for monitoring
the loading and unloading
processes for the four new
LPG/NH ³ tankers, built by Hyundai
Mipo SY. Wago Kontakttechnik
delivered the nodes
with approximately 2,000
I/O modules on the Profi bus
coupler, hereby collecting the
signals from temperature sensors,
pressure gauges and other
sensors in the explosive and
non-explosive area. The system
is certifi ed by the leading
classifi cation societies and all
28 Ship & Offshore | 2010 | N o 4
signals can be connected via
normal and intrinsically safe
I/O modules, even those from
the explosive areas. Additional
equipment, such as Zener barriers,
are hence unnecessary.
Since very many signals must
be processed on a small area
on such a ship, the compact design
of the components is said
to quickly pay off.
The I/O-nodes transfer the
measured values to the PLC
(programmable logic controller)
of the alarm monitoring
system. Some signals are electrically
isolated from the product
group Jumpfl ex® via midget
switching relays in a plug-in
base with a width of 6 mm.
In addition to the cargo inspection,
many different butterfl y
valves must be controlled in the
fl uid circuits and the respective
status must be recorded, for ex-
ample, in bilge, ballast and fresh
water, as well as the lubricating
oil or fuel. Actuators open and
close the valves via double acting
cylinders and with separate
lines for each control direction.
The solenoid valves to bias the
conduits into action and into
cut-off are supplied with voltage
via I/O modules and relays.
In addition, electrical pressure
sensors (4-20 mA) record the
fi lling levels of the tanks and
displays them individually.
Marine Technik also equips
the tanks with a special display
system upon request. They developed
processor-controlled
tank content measuring systems
with an individual display
and control of butterfl y valves
(VRC) via a trackball or touch
panel for this. In new equipment,
such as for the vessels
at Hyundai Mipo SY, Marine
LPG/NH 3 tankers have to
fulfi l special requirements
on control and
monitoring systems
Technik installs approximately
14 P-Profi bus-D couplers and
more than 500 I/O modules
with analog and digital inputs
in the Ex-i version and the non-
Ex-i in a cabinet.
An Integrated Control and
Monitoring System (ICMS)
provides quick information and
response and therefore safety
onboard. The alarm monitoring
system (MAS) warns visually
and acoustically, for example,
when pressure drops or at
excessive temperatures. Mimic
diagrams show the installation
location of the sensors, thus
facilitating the assessment of
the malfunction. If the trend
of the error message continues,
the safety system (MSS) reduces
the speed of the drive system or
stops it altogether.
The fi lling levels in fuel tanks
and the entire power supply