Workingman's Wireless

More Routine Process Control Applications Are Adopting Wireless to Save Cable, Secure Added Signals, and Transfer Data from Spots Where Wire Can't Go. Here's How Veteran Users Do It Every Day

By Jim Montague

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"Refinery assets are typically spread over a large geographical area. Plants are often required to monitor multiple points in applications involving level, flow, pressure and gas detection., and, up to 90% of the installed cost of measurements in these applications can be for cable conduit and related construction," says Felix. "Wireless networks make it possible to easily obtain point measurements in the most remote and hard-to-access locations without interrupting normal operations. Wireless systems can work consistently and reliably in areas previously considered impractical, and lower cost per I/O with wireless may justify projects that wouldn't have been feasible with wired transmitters."

Back on the wired side, Wilmington originally employed a Honeywell TDC 2000 DCS, and subsequent upgrades added TDC 3000 equipment, while legacy US stations were migrated to Experion PKS with new HMIs, Icon stations and Experion servers. The refinery is presently moving to C300 controllers, which will be used for blender control. The plant was commissioned in 1969 and expanded with alkylation and fluid catalytic cracking (FCC) units in 1982. It produces 15% of southern California's asphalt supply. Meanwhile, Wilmington's OneWireless R200 installation includes Honeywell's Wireless Device Manager (WDM), Field Device Access Points (FDAPs) and XYR6000 wireless transmitters.

"Our wireless network provides more reliability and ease of use than earlier systems," adds Felix. "Also, OneWireless supports multiple protocols and is simple to manage and operate. Our wireless system provides a cost-effective, manageable solution for non-critical process monitoring applications, including pipeline movement, flare monitoring, LPG purge gas pressure, heat exchanger temperature and tank high-level alarms."

Because Valero and the Wilmington plant were early wireless adopters, they've learned many valuable lessons. For instance, the plant's initial wireless transmitters and multi-nodes were installed by Honeywell and then handed over to Valero for day-do-day maintenance and expansion. "However, our staff encountered some problems, such as signal strength issues due to antennas that weren't wrapped well enough to handle the weather, and some other cables that corroded," explains Felix. "There were also some challenges in programming the multi-nodes."

So in August of 2012, Wilmington conducted a new wireless site survey, and migrated its OneWireless R120 systems to OneWireless R200. The multi-nodes were replaced with FDAPs, while R200 and WDM provided improved system reliability and connectivity and an intuitive, web-based user interface. They allowed integration of the wireless network with the plant's control system using industry-standard protocols.

So far, Wilmington's active OneWireless network consists of 30 wireless transmitters, 11 FDAPs, two FDAPs wired to the DCS, and the WDM connected via serial Modbus to the Honeywell DCS.

"R200 was a lot faster to deploy, and it lets us troubleshoot our transmitters much quicker," adds Felix. "Work on the R200 system has proven to be much less labor-intensive than with the original R120 system."

Though they need power routed to them, FDAPs do message routing, so users can connect wireless devices to the control network and route data from the field.

They also allow creation of a secure, ISA100-compliant, wireless network of field instruments which communicate with each other and route messages from neighboring field devices to controllers. Likewise, WDM enables gateways and security managers to make sure communications between field instruments and the plant are secure. They support a web-based user interface, allowing process and field engineers with basic IT knowledge to quickly set up wireless systems, and they reduce time required to commission, monitor and troubleshoot the wireless device network.

"OneWireless helps us optimize our plant processes and reliability, improves safety and security, and ensures regulatory compliance," says Felix. "It's been much more than just avoiding the cost of wire because the key benefit of wireless lies in the ability to integrate valuable data into control systems and advanced applications, while also sharing that data with other networked applications. Many other projects are now becoming possible for us, such as short-range site-to-site, using inputs in control, etc."

Water Goes Wireless

One of the best indications that wireless is taking over basic process control is its widespread adoption in municipal applications, especially in water and wastewater processes.

For example, Oslo Municipality's public works department recently replaced costly operator panels with connectBlue's Bluetooth wireless maintenance and operations devices at several hundred pump stations which manage water and wastewater flows throughout Norway's largest city (Figure 2). The Bluetooth units give the utility's ABB ITTM AC 800C control system an Ethernet interface and web-server access to process data on customized web pages, local dynamic data logging and access to the city's wide area network (WAN).

In addition, Oslo's staff can use Bluetooth handhelds to service machinery, adjust and reprogram each pump station on site, and connect with overall control systems. Connecting AC 800C to the WAN also enables personnel at the pump stations to automatically store software changes on the WAN server, so they no longer have to return to the control room to download program adjustments before proceeding to another station.

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  • I agree both wired and wireless have parts to play in automation. Wired and wireless have different characteristics and thus excel in different applications. They complement each other. Most importantly, the communication shall be digital to enable intelligent devices communicating over a wireless or wired network.

    Indeed WirelessHART is ideal for fixing problems around the plant with which plants just had to live with before. Modernizing existing plants is the killer application for WirelessHART. Within plants these applications fall into three major areas: essential asset monitoring to improve reliability, HS&E, and energy conservation measures (ECM) for energy efficiency. Outside plants the main application is integrated operations for improved production and recovery at oil and gas wells.

    Personally I believe the fast uptake of WirelessHART is not due to the low cost, but the low risk of deployment. We hear about savings of tens of thousands of dollars per year, even hundreds of thousands and millions in energy savings and improved production etc. This would be a phenomenal return on investment even on a costlier wired solution. So why was it never done before? I personally believe the reasons are risk and lack of resources. Running wires in an existing plant requires cable trays and junction boxes to be opened; this caries a risk of damaging the existing installation so such mini projects get rejected. And there just aren’t enough people around to manage the logistics of it. WirelessHART is much simpler. You deploy a WirelessHART gateway at the edge of the plant area; then you can deploy wireless transmitters inside that plant area, without running any new wires inside the plant area. No wiring for power. No wiring for signal I/O. That is, electrical installation is non-intrusive. In many cases non-intrusive mechanical installation is also possible: there may be existing thermowells or tapping points for installation of temperature sensors and pressure transmitters. Clamp-on surface temperature transmitters can also be used. Pressure transmitters can be installed where pressure gauges previously were mounted. Valve position feedback bolt onto hand operated valves like bypass valves. Vibration sensors can either be screwed on the outside, glued on, or even use a magnet. Acoustic transmitters for monitoring of valve leaks, relief valve activation, and steam trap health simply strap onto the outside of the pipe using hose clamp. In many cases new process penetrations need not be drilled, cut, or welded. That is, not only low installed cost, but low installed risk.

    Having said that, high cost of 4-20 mA and on/off cabling and DCS I/O count is often the reason why these points were not automated in the first place when the plant was originally built. But most plants are now very old, and the economics of energy cost etc. has changed greatly since the plant was constructed. All the points which were not automated are now “missing measurements”. WirelessHART provides a “second layer” of automation for points “beyond the P&ID” (on top of the wired automation used for control loops on the P&ID). Use wireless for plant modernization, and deploy wireless gateways in all plant areas on new plants because all Greenfield plants become brownfield after startup.

    Learn more here: http://community.emerson.com/process/emerson-exchange/b/weblog/archive/2013/10/03/why-are-there-missing-measurements.aspx

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