6 October 2009

Wireless standard already at work in chemical plant

By Nickolas Sheble

“The price of running one more signal into our DCS with a wire was so high we looked at wireless,” said Didier Auber, plant manager, on Monday at his plant 35 miles northeast of ISA EXPO 2009.

Auber’s Arkema chemical facility in Crosby, Tex., and the ISA100 Wireless Compliance Institute showed off a working demonstration of a sensor network using ISA 100.11a standard technologies to the press and analysts.

Working with multiple companies, Arkema recently installed several wireless devices that communicate over an ISA 100.11a wireless mesh network. This showcase site features the multi-vendor interoperability and the reliable, site-wide performance the ISA 100.11a standard technologies promote.

The wireless mesh network was up and running a mere two weeks after the standard passed muster and uses instruments and systems from Gastronics, Honeywell, Nivis, and Yokogawa.

The network is measuring level, flow, and pressure, analyzing gases, and making a discrete measurement. This is the first stage of what Auber expects will be a bigger network that will work in hazardous and explosive areas, and eventually work in intrinsically safe applications.

Those uses of wireless are outside the ISA standard and will need additional certifications.

“This plant grew in stages, over a period of time, so there were different technologies and instruments involved and still here. The ISA 100.11a standard helped us include all those systems,” Auber said.

The plant began operations in 1966 and joined the Arkema team (formerly Atofina Chemicals, Inc.) in 1989. The plant has grown steadily with major expansions completed in 1979, 1994, and 1999. The Crosby plant produces liquid organic peroxides that are part of the production of plastic resins, polystyrene, polyethylene, polypropylene, PVC and polyester reinforced fiberglass, and acrylic resins.

“Another of the primary reasons to use wireless was to expand the radius of our gas detection systems. There’s the aspect of compliance and safety certainly. As well, the more you know the better,” said Auber.

Honeywell ran an analysis of the leak detection and finding fugitive emissions. In a refinery or chemical plant, it is a huge but critical job to ensure regulatory compliance, safety, and to prevent costly fines.

A plant can have over 35,000 valves and as many as 200,000 monitoring points. Refineries and chemical plants have seen the cost of their lead detection and repair programs skyrocket as the number of monitoring points has increased.

Monitoring costs for leak detection and repair programs are escalating. Many companies are not meeting regulatory requirements or are incurring significant violation costs.

More importantly, plant safety relies on managing assets effectively. Most technologies used to identify and detect potential leak paths are either handheld-manual or wired solutions.

With increasing labor costs, an increasing number of points to monitor and the high cost of wiring in hazardous locations, these methods quickly become cost prohibitive and expose the plant to potential violations.

At a minimum of $40/foot for most hazardous areas, the cost of wiring can quickly exceed $30,000 for a 750 foot run per monitored point. Most plants need to monitor multiple points, and these costs become prohibitive.

In addition, in many places, periodic inspection is simply not enough, but it may be cost prohibitive to run the necessary wiring.

Nivis also played a role at Arkema and showed off an attractive and useful HMI package during the Monday tour, working the integration angle. They have an ISA100.11a Integration Kit that is ready and able.

The ISA100.11a standard communicates to any legacy instrument or host system, including HART, Foundation Fieldbus, Modbus, Profibus, and others.

This effectively makes it the 4-20 milliamp standard of the wireless world. It is has the built-in flexibility to address most wireless applications in a single, plant-wide industrial wireless system.

The system will provide wireless monitoring and control over industrial and commercial applications. It supports ISA100.11a.

The standard platforms on “mesh networking.” Briefly, mesh networking is a way to route data, voice, and instructions between nodes. It allows for continuous connections and reconfiguration around broken or blocked paths by “hopping” from node to node until it reaches the intended destination.

At the demonstration, technicians blocked direct signals with trucks and pieces of metal to force the network to figure its way around the obstacles to get to the control center.

“The system prefers to do a single hop to the control room. It’s also faster and uses less power to transmit straight away to the final destination,” said Herman Storey, ISA100 Wireless Compliance Institute founding sponsor. “But we wanted to push the technology here to assure that it is robust.”