BALLAST CONTROL

Ballast Control

System Design

The ballast system is one of the most critical systems on the vessel. Operation of the system must be closely monitored and finely adjusted to cope with the demands of work the vessel is involved in, drilling, pipelaying, crane barge, diving support etc
Jelec has extensive experience in designing, manufacturing and commissioning of ballast control and monitoring systems. These systems range from Tank Gauging Bubbler System using discrete mimic panels through sophisticated PLC data acquisition and control systems incorporating fully automatic ballast control algorithms.
Jelec Ballast Control and Monitoring Systems can provide monitoring of all tank gauging, and draft data, and control of ballast valves, throttle valves, and ballast pumps. The system can also be interfaced with stability software in a real time mode, for constant monitoring of the vessel's stability.
Additionally, the system can provide control and monitoring of fuel oil transfer systems, potable water systems, bilge controls, watertight doors alarms, rig alarms and other vessel management systems.
Jelec Ballast Control and Monitoring systems are designed around Allen Bradley ControlLogix family of PLCs or equivalent according to the customer requirement. These PLC processors are typically arranged in a "Redundant Hot Backup" configuration and located within the ballast control console. Inputs and Outputs are handled by placing Flex I/O Modules located conveniently near each pump room.
The PLC's are interfaced with the remote I/O over a fiber optic network arranged in a ring topology, which provides communication redundancy and removes the single point of failure from the network.
Valve control and Tank Gauging Systems are designed to operate independently of each other such that a failure in one system doesn't jeopardize the operation of any of the other systems.

Valve Control

Valve control is typically achieved remotely by use of an actuator mounted on the valve spindle. Power for the actuator can be hydraulic, pneumatic, or electric and the signaling system (indicating valve position) to the actuator can be a wide combination of all three types of power. Through the use of standard PLC control and feedback modules, almost any type of valve control can be implemented. Most of the regulations require ballast tank valves to fail in close position and upon loss of control power they should close and remain close. Jelec systems are designed to meet the requirements of all major regulatory bodies.

Ballast Control and Monitoring Console

A centralized control and monitoring station is located on the bridge or control room, which is above the worst damage waterline. Typically this is a dual bay system allowing redundant control and monitoring of the ballast system to comply with the Classificaton Society regulations where computer operated systems form part of the control system, they are to have back-up capability for continued operation upon loss of any single major component. This is accomplished by the use of multiple computers arranged in a peer-to-peer network. This simple and cost effective approach where each system operates independently of the other has proven successful. Optional Mimic Panels can be used in addition to computer based MMI screens. The mimic panels can have the option of a touch screen for control and monitoring purposes.

System Functions

The main System functions are, but not limited to:

  • Remote Open/Close of all ballast and bilge valves.
  • Total fail safe design for all valves and pumps.
  • Valve status and position indication on MMI screens.
  • Remote Start/Stop of ballast and bilge pumps.
  • Pump status and running indication on MMI screens.
  • Level indication and alarm of all monitored tanks.
  • Display data in feet, meters, short tons, long tons, etc...
  • Total volumes by the sum of all fuel tanks.
  • Total volumes by the sum of all potable water tanks.
  • Total volumes by the sum of all potable drill water tanks.
  • Draft indication.
  • Heel and Trim indications etc.

Example of a Ballast control Upgrade

Shown above are two pictures taken before and after the revamp of a ballast control system on a pentagon type semi-submersible drilling rig. To avoid any confusion for the ballast control operators, Jelec suggested the customer to install one touch screen per column. The touch screens were designed to operate similar to the old system. This greatly helped to reduce the training period and the time taken by the ballast control operators and electricians to familirize themselves with the improved operational facilities.