Simple, Strong and Easy-to-Use

By Jim Montague, Executive Editor

Holding 8 or 10 ounces of boiling coffee in your cupped hands is tricky. Using a thick stoneware mug is easier, but you still have to be careful. Likewise, sturdy tools and finesse are needed to consolidate several control rooms into one, especially if you're going to more than triple production at the same time.

These were just two of the countless jobs facing engineers at BHP Billiton Worsley Alumina (www.bhpbilliton.com) when they and their many colleagues renovated and expanded their huge bauxite mine and alumina refinery a few years ago. Located near Collie in southwestern Australia, the company's operations presently refine about 3.5 million tonnes per year of bauxite ore into metallurgical alumina for later processing into aluminum. When the mine and refinery first started running in 1984, more than 50 operators managed production from five control rooms, and produced about 1 million tonnes annually. The initial control system was Honeywell Process Solutions' (hpsweb.honeywell.com) TDC 2000 analog distributed control system (DCS).

To carry out their overall Advanced Process Management (APM) project, BHP Billiton's managers and engineers agreed it should include the new central control room, advanced controls, alarm management and a partial control system upgrade to Honeywell's newer Experion DCS, operator stations, software and other equipment. The new controls also had to make room for and coordinate close to 4,000 process signals and more than 300 drives that were migrated from the old plant equipment to new systems, and do it without hindering operations.

However, elevating production performance in an alumina refinery is a challenge because it hinges on an operator's ability to be proactive and act on information appropriately. BHP Billiton's engineers realized that one catalyst to improving performance was to use advanced automation and user-centered design to replace some of the operators' current tasks, allowing them to focus more on production goals. "Following an extensive review of our process management, we knew we wanted to implement advanced applications and improve our production control," stated Angelo D'Agostino, BHP Billiton's senior process control engineer, in one of  Honeywell's online success stories. "Our operators were key to this transformation and seen as the biggest lever to improve production and quality, and to decrease costs."

The project also was assisted by Ian Nimmo, then at Honeywell's Abnormal Situation Management (ASM) Consortium (www.asmconsortium.net), as well as system integrator I&E Systems (www.iesystems.com.au) and HMI specialist Acuité (www.acuite.com). However, though construction began in 2004 and the centralized controls have been up and running since September 2006, there were and remain some hurdles on the road to good user-centered design.  

Confusion = Danger 

In fact, most obstacles that hamper operators today are actually very old. And in many ways, process applications and their control systems still don't know how to get along with their data processing and computing counterparts.   

"Instrumentation designs were technology-centered for 50 years. Operators weren't considered when new methods were invented for showing what processes were doing, and so people became the bottleneck. Ever since computers began to be used on the plant floor in 1980s, the mistake was that controls and displays were made to look like P&ID drawings. But the problem with having many detailed P&ID screens with no hierarchy is that the operators can't distinguish what's going on where," says Nimmo, who is now president of User Centered Design Services (UCDS) Inc. (www.mycontrolroom.com). "These are not problems that ergonomics can solve. It's why we need user-centered design, so we can understand each operator's tasks, decide what information they really need to see, and provide the best information for them. We also need to make that information available in a useful hierarchy, instead of bombarding operators with the on-screen and alarm overloads. These come from bad design and can hinder instead of help operators because, if everything is red, then you can't discern what's important."

ngly, many of the most catastrophic accidents of the past several decades have been at least partially attributed to missed or obscured alarms and alerts. For example, in his "Situation Critical" white paper, Nimmo reports that the Texaco Pembroke, Esso Longford and Texas City disaster each had "reports of console operators missing important information." (Figure 1, See also www.controlglobal.com/1003_sitcrit.html.)

Waking Up from History

Fortunately, several other technical fields had operators in high-pressure situations who also were overwhelmed with data to the point of causing accidents, injuries and fatalities. For example, when airplane speeds increased during and after World War II, developers found that traditional control layouts weren't allowing pilots to respond fast enough to avoid crashing. Consequently, aerospace engineers examined what pilots must do to fly effectively, and in the 1970s began developing the field of situation awareness.

"Most of this work was done at Wright Patterson AFB and Wright State University, both in Ohio, and this is also how the field of human factors came about," says Dave Strobhar, PE, chief human factors engineer at the four-year-old Center for Operator Performance (COP, www.operatorperformance.org), which also is located at the university. "As the interest in operator performance issues such as alarms, HMIs, training and teams has grown, voids have been found in the available information. People estimate how many alarms they think operators can handle based on other industries, but most of these numbers are pretty arbitrary."