Automated data from the coal face to information in your face.
In Mid July 2008, Bulk Connections, the coal storage and loading facility at Island View in Durban Harbour, contracted eTX (via Instrotech) to investigate the possibility of installing a computerised ship loading and discharging monitoring system. The then current ‘tally’ system of counting the bin loads only provided a rough estimate during loading and the vessel draft survey was the final figure on which all commercial transactions were based. A more accurate system was required in order to manage the loading process more effectively.
The vessels are loaded by two 40 ton cranes. The special container type receptacles are first loaded from the stockpiles on site and then towed to the cranes by trailer vehicles. The cranes lift the containers individually over the vessel’s hatch, hydraulically open the bottom of the container bin, deposit the contents into the vessel, then return the bin to the trailer and repeat the process with the next bin. Anything up to seven holds are loaded in this way.
System description
Loading up to 25 000 tons of cargo can require over 1000 bin drops into a vessel. The proposed system would be required to record the simultaneous loading weights of two vessels in two berths by hatch. A vessel and berth configuration page would be needed to record the vessel name, weight, date, and the wind speed at the time of every bin drop. The vessels hatch number also had to be recorded so that the reports would show the actual weight loaded into each hatch. Shift reporting and management/office-network reporting was also a requirement.
A further requirement was a wind speed monitoring system to trigger a siren at a preset wind speed and inform select personnel via SMS as wind speed increased. This as loading has to be aborted above a certain wind velocity and the cranes have to be secured once the wind reaches a critical speed.
The feasibility proved that a system could be designed and installed to achieve these objectives, but would need to be a joint effort between Bulk Connections and eTX, and would require some R&D and testing to take the project to completion. On this basis the project was awarded to eTX Data Services.
Implementation
eTX replaced the existing load cell transmitters on the cranes with Instrotech units to provide the required levels of accuracy and reliability. A Festo PLC was installed on the crane and the win speed monitoring unit connected to it. A Wavecom GPRS modem was connected to the PLC and the wind speed warning siren and the SMS system commissioned. Work then began on the load monitoring system.
Radio transmitter/receivers were installed on each crane to provide a radio link between the Festo PLCs on the cranes and the scada system in the control room. This was necessary as the cranes are mobile. The scada was developed and commissioned in the operations control room. The reporting system available on the office network uses Excel spreadsheets for historical reports of the vessels loaded and the shift history, plus a live scada type Excel spreadsheet for viewing with graphics. The shift history is also available in the reports, which can be viewed via the specially developed website over the Internet.
Operation
During loading the crane operators select which hatch they are loading. This is done from their cab where they can see the weights loaded into each hatch (and the wind speed) on a digital display. The operator in the control room only has to note the shift changes on the scada during loading.
The PLCs store the hatch weight totals on the crane and the scada manages the logging tasks associated with each drop plus providing live graphical process data. Once the loading is complete, the manager completes the process by printing the final report and resetting the berth ready for the next vessel.
Conclusion
The loading system was completed in early 2009 as a successful installation comprising all the components to monitor and automate data collection from the process through to management report generation and finally integration into a larger supply chain information system.
For more information contact Neil Upfold, eTX Data Services, +27 (0)31 764 2099, neilu@etx.co.za, www.etx.co.za
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