|
|
 |
 |
| |
|
| |
 |
|
|
| In case that Emergency Situation
should be generated at LNG Carrier or LNG all working(loading
and unloading) must be automatically stopped. At this time,
Stop or Shut- Down the main equipment related operation and
transfer the ESD status signal to meet the emergency. Above
mentioned functions will be done automatically, this is ESDS
for LNG Carrier. There are various emergency case, but first
of all we define the major case like Fire, Unsafe status of
Cargo Tank, Manual Shut-Down etc. |
 |
| In the event of fire, certain off limit condition
or other emergency condition, the entire cargo system, low &
high duty compressors and master fuel gas valve to the main
boiler may be shut down by single initiation. And there are
three emergency shutdown interface connections made to the shore
facility, is electrical, optical and pneumatic. In port, the
optical link and pneumatic systems will inform the shore of
any ship’s emergency shutdown actuation and will stop the loading
or discharge pumps and close the shore liquid valve. |
| |
 |
|
|
The Air control board is one part of the whole ESDS to monitor
and detect the pneumatic air pressure and eventually control
the emergency shutdown system of LNG Carriers.
Air of 7~9 barg is supplied to the Air Control Board and one
transmitter are provided to detect the air pressure and send
out the pressure value to ESD main controller for automatic
control the Pneumatic system pressure using electro-pneumatic
solenoid valve.
If the control air pressure for the Air Control Board is lower
than normally supplied air then pressure switch detect the pressure
value and send the electrical signal to main controller.
3-way test cock are provided to test the functionality of the
pressure gauge and pressure transmitter individually.
This pneumatic air control system onboard ship is linked to
the pneumatic air line of the terminal to initiate the ESD system
by setting the ESD pressure to the required value of each terminal.
The Pneumatic Link transmitter box is used to set the operating
air pressure of the ESDS onboard ship to the required value
of each terminal.
There are only one Pressure transmitter and 3-way test cock
in this box but it can be measured any LNG terminal set point
flexible
| Air Release
Solenoid valve |
Air releasing solenoid valve is open that means de-energized
, when ESD occurs from ESD main controller.
Automatic shutdowns occurs when any of the following conditions
- Cargo vapor main line header pressure falls to within
0.3 kPa of atmospheric pressure.
- Cargo vapor main line header pressure & primary insulation
space pressurization main line equal pressure.
- Pressure difference between each cargo tank pressure
& primary insulation space pressure becomes 0.5 kPa
- Each cargo tank pressure falls to the primary insulation
space pressure.
- Any cargo tank level extremely high (99% volume)
- Automatic shutdown for electric fail.
- Automatic shutdown by hydraulic oil pressure low.
- Shutdown signal from the terminal.
- Automatic shutdown by pneumatic pressure low in ship/shore
connection.
- Automatic shutdown by control air pressure low.
|
| |
 |
|
|
GMB has proposed new concept of pneumatic system
for Emergency Shutdown System, The new concept of air control
board adopts just one pressure transmitter instead of three
pressure switches that enables to control the air pressure as
pre-defined set value through PLC and air control valve.
As a result, the system becomes much simple and the overall
board size can be reduced drastically so that the maintenance
and operation become easier than previous concept.
Moreover, this new concept enables the pneumatic ESD link as
entirely worldwide compatible system. In other words, the three
(3) pressure switches are replace by one pressure transmitter
and the required setting values are selected by just pushing
the +/- buttons on the monitor or other similar device located
in CCR.
Against old concept of ESDS, new concept system can be simplified
by using just one smart pressure transmitter and the logic can
be much simple.
The pneumatic link pressure (downstream of electro-pneumatic
regulator) is automatically controlled to follow given set point
that is pre-determined through CCR by operator.
The air supply solenoid valve is energized to open during normal
operations and get closed when an ESD condition is detected.
If the pressurized air in the pneumatic link is released by
any ESD signal, the pressure transmitter of the pneumatic link
pressure transmitter box detects the ESD condition.
ESD condition happens as in the previous configuration as well.
|
 |
| |
 |
|
|
The system design and manufacturing of all equipment
shall satisfy the requirements of the classification society,
the Rules and Regulations mentioned in General term of Yard
Specification
- Main Panel Size : 1200(W) X 1800(H) X 800(D)
- Cabinet Paint Color : Munsell 7.5 BG 7/2 (depend on yard
specification)
- Main Control System : Siemens SIMATIC NET S7 Series
- Specification of ESD System
- ESD System shall be applied Redundant CPU, Power, Network
- ESD System is a safeguard provided in addition to the
individual safety devices for equipment.
ESD System shall be interfaced with IAS, CTS, VRC System
etc.
- Air Control Board (810(W)X820(H)) would be installed Electric
Equipment Room (Wall Mount type)
- Pneumatic Link Box : EExi-a (Side passage way)
- Air Release Sol. Valve box : EExi-b ( Side passage way)
- Fusible melting plugs and Manual ESD Push buttons shall
be located certain place on the LNG Carrier.
|
|
|
|
|
