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01 July 2003

Broaden your spectrum at ISA EXPO 2003

Technologies evolve to new heights

By Ellen Fussell

Control loops, Bluetooth wireless technology, and multispectral imaging are just a few topics that will help you strengthen your industry knowledge base at this year's EXPO 2003 Emerging Technologies conference in Houston. ISA's main technical conference is in sync as well with more wireless, hazardous location standards updates, human-machine interface applications, and Web-based supervisory control and data acquisition (SCADA). Take a sneak peak at what experts will be talking about this October.

CONTROL LOOPS

How can you provide your client with control loops to eliminate facility shutdowns during a liquid slug period? What about unpredictable shutdowns during start-ups and normal operations associated with a floating production storage and offloading (FPSO) facility? Aker Kvaerner, a global provider of engineering and construction services, was tasked with this challenge; they also needed to predict the time interval between liquid slugging and the related type of instability—high-level or high-pressure anomalies.

"In the past, our client had a lot of shutdowns during start-ups and normal operations initiated by liquids overfilling the primary separator, due to over pressure in the same vessel," said Michael Needham in his abstract of an ISA Expo 2003 submitted paper, "Predicting time intervals of liquid slugging in vertical two-phase flow regimes." The object of Needham's study was to predict a time interval when the client could expect a slug severe enough to cause shutdowns due to either high pressure or high-high levels.

Needham's team developed the origin of these liquid slugs from two flow regimes—accumulation in the crude oil boarding risers while the FPSO was out of service and instability at the gas-liquid interface during normal operation associated with gravitational forces. These accumulated liquids became slugs after putting the subsea wells into production service. Now they would cause intervals of shutdowns to last from several minutes to several hours. The shutdown event would change from high-high level to over pressurization in the separators toward the end of the slugging period.

First, Needham's team determined the potential for slugging as the ratio of gas/liquid hold changed further up the riser due to gravitational forces. They developed a suitable control loop or loops with the appropriate sensors and final control devices to control the slug rather than allow the facility to be shutdown.

BLUETOOTH AND LOCAL POSITIONING

Mobility has been one of the key features behind the success of wireless technology—giving us a choice of plenty of applications once we combine this mobility with location awareness. But accurate assessment of the mobile user's local position is critical for location awareness, said Steven Case of Minnesota State University in a submitted abstract for his paper, "An indoor positioning system using Bluetooth ad hoc networks."

"Local positioning refers to a technology used to determine the position of any device with respect to the other devices whose positions are already known," Case said.

Case's paper discusses the development of a local positioning service based on the Bluetooth ad hoc wireless network standard. Originally conceived as a cable replacement, Bluetooth is a low-power, short-range, wireless radio system that can help create a wide range of wireless services.

In his paper, Case discusses theoretical and practical aspects associated with indoor positioning based on Bluetooth communication. Then he proposes a solution based on the exchange of positioning information between master and slave devices within a Bluetooth piconet. The paper closes with a presentation of preliminary results based on an initial implementation of the proposed service and its application to a hypothetical industrial automation system.

MULTISPECTRAL IMAGING

Integrating remote sensing and geographic information systems (GIS) in environmental applications is growing in popularity. GIS applications rely on remotely sensed images for data sources in environmental applications, while users rely on GIS capabilities to improve image analysis procedures. Carl Steidley of Texas A&M University, Corpus Christi, gives us a thorough explanation in his paper, "A multi-spectral imaging system for geo-spatial applications."

When you combine image processing and GIS facilities in an integrated system, you can use vector data to help classify images. You can also use raster image statistics within vectors as criteria for vector query and analysis, he said.

"Advances in imaging technology and sensors have made airborne remote sensing systems viable for many GIS applications that require reasonably good resolution at low cost," Steidley said.

Steidley will describe in his paper the design, prototype, and initial testing of the aircraft-mounted imaging system at Texas A&M University, Corpus Christi, with the support of a grant from NASA.

RELIABLE WIRELESS

R. Duckworth of Adaptive Instruments LLC will present a system architecture that provides a robust, reliable wireless network for industrial sensors and control that employ frequency hopping spread spectrum (FHSS) in the industrial, scientific, and medical band in his paper, "Reliable wireless in an unreliable world."

Although FHSS provides some measure of protection if a frequency is noisy, it is important to carefully design and implement network systems if we want to achieve periodic sensor measurement or control over the lifetime of the installation, he said.

Duckworth's paper will consider elements responsible for ensuring a reliable network—sensors and control actuators, base radios, network topology, radio frequency monitoring tools, and control computers. "It is critical the sensors and actuators have a wireless transceiver (not just a transmitter or receiver) to provide a bi-directional wireless communication path," he said.

Duckworth explains how you can maintain sensor and actuator communication with redundant but inexpensive base radios—even if electrical interference or a mechanical object in the wireless path blocks one path or frequency. Using continuous frequency and signal strength monitoring with data link tests and simple spectrum analysis tools built into the sensors, actuators and base radios allow dynamic modification of the radio network as external conditions require, he said.

TECHNICAL CONFERENCE

The Expo 2003 Technical Conference also offers its share of enlightenment: hazardous locations, HMI, SCADA, and the Web are some key issues.

IECEX SCHEME

"Markets for trade in explosion-protected apparatus are growing as a result of global market integration and industry mergers across national and regional boundaries," said Paul Kelly of Underwriters Laboratories Inc., in his paper, "The impact of the IECEx scheme on the global availability of explosion-protected apparatus." Abolishing differences in relevant national standards is especially important for product manufacturers' use in hazardous locations. Conformity assessment bodies or testing agencies can help accelerate the merging of markets through a global scheme of accredited certification bodies and testing labs—harmonizing all national standards with the International Electrotechnical Commission (IEC) standards. That's where the IECEx scheme becomes crucial.

Kelly's paper will address the advantages and possible concerns regarding the scheme from the perspective of multiple international certification organizations providing an over-view of the scheme.

The goal is to develop and maintain uniform product evaluations to protect users against products that are not compliant with the required level of safety, Kelly said.

WEB-BASED HMI

Brad Carlberg of BSC Engineering will explain circumstances for using active server pages, intelligent serial devices, HTML, SOAP, WML, XSL, FTP, WML, OPC and ActiveX, and Internet/intranet technologies to create web-based human-machine interfaces (HMIs) during a panel discussion, "Web-based HMIs." "Web technologies provide new opportunities to implement human-machine interface applications using new technologies," he said. Those technologies help gain influence from high-speed communication to industrial hardware—helping users view real-time plant/production data over a plant intranet.

"This future communication architecture will provide a bridge between current proprietary systems to an open environment based on Ethernet and Web technology," Carlberg said. Web-based HMI's evolution has allowed access to real-time information from automation systems to anyone in the corporation. Five or six representatives from the major vendors and providers will sit on the panel and give 5–7 minute PowerPoint presentations followed by an audience question-and-answer period.

SCADA SYSTEMS

"SCADA systems, which manage the production, transmission, and distribution of energy resources including oil, natural gas, and electricity, are becoming increasingly connected to the Internet, and as a result, are much more vulnerable to attack," said Bob Walters of Stratum8 Networks, in his abstract for his presentation, "Protecting SCADA systems from Web exposure."

"Traditionally, these sensitive systems were based on proprietary or homegrown technologies and isolated from mainstream computer networks," he said. But while isolation brings safety, two recent trends are exposing SCADA systems to attacks from the outside. One is commercial hardware and software—Windows, UNIX, and third-party applications in SCADA systems. Utilities are connecting SCADA systems to their corporate networks, intranets, and even wireless networks. The result? SCADA systems are exposed to the same vulnerabilities and threats as corporate networks and Internet-facing applications.

Walters' session will cover the security implications associated with making SCADA systems accessible via corporate networks and intranets that are connected to the Internet. IT