January 29, 2009
Bitumen often poses storage and handling problems. Here, Sean Ottewell reports on two Australian companies who are tackling these by turning to wireless communication solutions.
BP Bitumen operates its Australian bitumen facilities in Queensland, Victoria, Tasmania and Western Australia. Bulwer Island near Brisbane is the largest production facility with sales of 200 000 t/y. Products include paving grade bitumens, multigrade and a wide range of polymer-modified binders (PMBs).
The products are manufactured using purpose built equipment to rigorous quality and control standards and are designed to have better strength and durability than standard bitumens to deliver longer lasting roads.
Now the company has successfully overcome a fuel supply outage at the site by using Smart Wireless technology from Emerson Process Management.
Wireless instruments normally monitor the pipeline integrity of transfer lines from the nearby BP refinery and report exceptional conditions to control room operators via the easy-to-use self-organising wireless network. The wireless solution showed its flexibility recently when two wireless transmitters were quickly deployed to manage fuel delivery from temporary LPG tanks rushed into service during a refinery shutdown of the regular fuel system.
Officials at BP Bitumen seized upon Smart Wireless as a cost-effective and reliable method of monitoring the temporary fuel gas supply system (Fig. 1).
The plant normally fires natural gas in a heater to maintain a hot oil network at 280°C. All plant bitumen lines have hot oil tracing to keep the viscous product flowing. Even a temporary interruption to the supply of fuel to the heater can adversely effect operations because if the heater shuts down, the plant cools very quickly. If the plant goes completely cold, it can take three to four days to restart.
The cost of sourcing replacement product to meet existing contracts could be as much as AS$150 000 for a fuel outage of one week's duration. For this reason, a close visual watch had to be maintained on the temporary LPG supply to monitor it 24 hours per day. The Smart Wireless solution was implemented to monitor the transfer lines in May 2008, and fuel monitoring was put into service shortly thereafter.
The Smart Wireless field network solution included two Rosemount wireless pressure transmitters that were installed to monitor the fuel delivery from the LPG tanks. With relatively little time to prepare for the natural gas outage, it was not possible to size the temporary LPG system for the maximum firing capacity of the hot oil heater. Without careful monitoring, the heater's burner control system could call for more gas than was available, sucking the fuel line dry and tripping the heater.
However, with the wireless pressure transmitters in place, the burner control system could monitor the LPG supply pressure and avoid the trip scenario. The wireless monitoring of the LPG fuel delivery kept the bitumen plant running, saving the company AS$20 000 per day in lost production. The wireless solution also provided safe remote oversight of the fuel supply instead of continuous operator monitoring at the LPG facility. The plant operated successfully in this way for the duration of the week-long outage.
In addition to the fuel monitoring, three Rosemount wireless temperature transmitters are placed along the plant's bitumen transfer lines to monitor flow of the hot (170°C) bitumen. These instruments transmit status continuously, allowing immediate action if needed to maintain the flow of bitumen to the plant.
"This wireless network monitors pipeline integrity, helping to ensure that no issues go unnoticed for any length of time," according to Matthew James, operations manager at the BP Bitumen facility. "If we had not had the wireless installations, we could not have reacted so quickly to the fuel outage and that could have shut us down for over a week. As a tool to help troubleshoot unusual process conditions anywhere on the plant, they're indispensable."
Each field device in Emerson's self-organising wireless technology acts as a router for other nearby devices, retransmitting messages until they reach the network's Smart Wireless Gateway, which channels the incoming data to a control point. If there is an obstruction, transmissions are simply re-routed along the mesh network until a clear path to the gateway is found. As conditions change or new obstacles are encountered in a plant, such as temporary scaffolding, new equipment, or a parked construction trailer, these wireless networks simply reorganise and find a way to deliver their messages.
All of this happens automatically, without any involvement by the user, providing redundant communication paths and better reliability than direct, line-of-sight communications between individual devices and a receiver. This self-organising technology optimises data reliability while minimising power consumption. It also reduces the effort and infrastructure necessary to set up a successful wireless network, because up to 99 wireless devices can be served by one gateway. New instruments can normally be added to a network in just minutes.
"This wireless concept is not a fad or gimmick," James said. "It really works, and the operating range is amazing. It is a long distance from the temporary LPG bullets to the control room. The fact that we could transmit that far and do so reliably without a single loss of signal is quite magical."
Another Australian business that has also adopted a wireless solution to help handle bitumen is Terminals Pty, the country's largest independent bulk liquid terminals company.
The unloading, storage, and shipping facilities near the industrial port city of Geelong include a 900-metre pier and 16 or more tanks. At this location, the company imports and stores bulk vinyl chloride monomer and other hazardous and non-hazardous combustible and corrosive liquids, fats, and oils. Hot bitumen storage facility is part of a recently completed expansion project
Terminals Pty selected Smart Wireless to monitor temperatures in the 900 metre long, eight-inch wide, heat-traced pipeline used for unloading bitumen from ships at Geelong. It is necessary to make certain the electric heaters are operating all along the pipeline to keep the bitumen hot (160°C) and fluid. If a heater fails, a cold spot could form causing the bitumen to solidify and plugging the line with expensive consequences.
"We needed to monitor the bitumen line," according to Bitumen Terminal project manager Joe Siklic, "to make the operators aware of cooling anywhere in the line from the ship to the storage facility, which could result in an emergency shutdown. Any delay in unloading could keep a ship at the pier longer than planned with demurrage costing up to US$30 000/day."
The wireless technology was selected, Siklic said, for its lower initial cost and minimal maintenance as compared with hard wiring. Eight Rosemount wireless temperature transmitters are evenly spaced along the pipeline, sending temperature readings on one-minute intervals to a Smart Wireless Gateway on shore that channels data to the AMS Suite predictive maintenance software used for instrument configuration and performance monitoring.
The collected data are also forwarded to a SCADA system in the terminal control centre via fibre-optic cable.
Due to the self-organising nature of this technology, each wireless device acts as a router for other nearby devices, passing the signals along until they reach their destination. As with BP Bitumen's solution, if there is an obstruction, transmissions are simply re-routed along the mesh network until a clear path to the Smart Wireless Gateway is found. All of this happens automatically, without any involvement by the user, providing redundant communication paths and better reliability than direct, line-of-sight communications between individual devices and their gateway. "This is an ideal application for wireless," Siklic said. "Since numerous paths exist to carry the transmissions, the network would easily compensate for a transmitter failure, and the operators would be warned. This wireless network has proved to be reliable, compatible with existing control equipment, and cost effective. The amount of structure on the wharf is minimal, and that is another benefit."