HART-Enabled Plug-In Control System Migration | Automation.com

HART-Enabled Plug-In Control System Migration

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Control System Migration – HART I/O

HART-Enabled Plug-In Control System Migration

Invensys Process Systems (IPS) has helped two clients – Dakota Gasification and Teck Cominco -- take advantage of the benefits of HART communications through a fast, economical control system upgrade.

At its Beulah, North Dakota plant, Dakota Gasification Company (DGC) converts North Dakota (ND) lignite into synthetic natural gas, which it delivers by pipeline throughout the region. Its gasification process brings ND lignite coal, steam, oxygen and a gasifier together in a reaction that forms a gas stream. They then cool the gas and recover various byproducts. The final product is synthetic natural gas.

The gasification plant was designed in the 70s, using what was then state-of-the-art automation technology. Some 25 years later, the company wanted to take greater advantage of automation advances that have occurred.

In the early 90s, for example, DGC installed new HART-based field instrumentation. The new instrumentation stabilized plant operations considerably, but its older control system prevented them from taking full advantage of diagnostic and other capabilities that the digital HART instruments offered. Plant engineering set out on a mission to upgrade their legacy control system at the lowest cost, with minimal interruption of operations.

The legacy system involved four or five different unconnected control systems, which multiple operators accessed from different control rooms. The desire was to combine them into a single control system with a common interface and a global database. And to keep cost and business disruption to a minimum, they needed to complete the migration within a pending 7- to 10-day plant outage. Replacing the field wiring and terminations for a new control system would have required much more time than that, so they also needed a solution that did not require replacing existing field wiring.

After evaluating the migration options offered by a number of controls vendors, DGC chose to migrate to a I/A Series automation system from IPS, largely because they were the only vendor that had manufactured control I/O boards in the same form factors as each of the legacy control systems. These I/O boards were the exact physical replacements for the existing input/output modules, and could plug right into the existing system enclosures with no mapping issues. This migration approach is more cost-effective than a complete system replacement because all field wiring and terminations remain intact.

The migration went as smoothly as anticipated. Over the course of a few days, IPS removed the cards from control boxes and discrete I/O and replaced them with comparable I/A Series cards. They then connected them to the appropriate terminations and Ethernet network via ribbon cables, downloaded the software from the central control system and put the new cards online.

“Now we can pull the HART information from our field devices,” said Rod Wetsch, project manager at the Dakota Gasification Great Plains Synfuels plant. “It doesn’t matter what vendor’s field device it is. We can bring the information into our control room and remotely monitor multiple variables from that device. We can, for example, calibrate remotely, which in itself has great efficiency benefits”

In this way, operators can control multiple parts of the process without having to switch from one interface to another, as they had to do previously. Without leaving their seats, for example, the operator can control PID loops, start pumps or open and close valves.

To Wetsch, the ability to have move to the benefits of digital control as swiftly and as economically as they did is largely a result of the fact that the I/A Series electronics were available in form factors that match each of the legacy control systems.

“This enabled us to capitalize on the legacy backplanes and card cages that were in our system, to move the existing electronics from the cage and to populate it with new I/A Series electronics,” he said.

“Being able to use the existing rack saved us an enormous number of man hours in actually completing that migration, and that saved us money because it enabled us to complete the project within the planned outage period.”

DGS officials see the value of the migration spreading across department lines. In addition to the diagnostic, performance and maintenance benefits derived from being able to access the HART data, they now have a platform that will make it easier to implement new regulatory and advanced control strategies that will contribute to increased production and lower operating costs.

Teck Cominco takes to HART

Another IPS client is already gearing up to obtain similar benefits from the HART protocol. About two years ago, Teck Cominco, a mining, metals, and chemical producer from Vancouver, British Columbia, began to consolidate its four legacy distributed control systems into a common Foxboro DCS platform using the same plug-in migration approach Dakota Gasification had leveraged.

Because IPS did not offer a HART-enabled I/A Series plug-in migration card for the Honeywell TDC 2000 at the time, Teck Cominco migrated three of its four control systems using electronics designed for Windows NT workstations and Unix-based Sun Solaris operator stations.

Like Dakota Gasification, Teck Cominco benefited from the ability to migrate without having to rip and replace field wiring and marshalling cabinets, but they still wanted to take advantage of diagnostic, maintenance and scalability benefits the HART protocol might offer. This became possible in 2007, when IPS announced the availability of Hart-enabled migration cards for the Honeywell TDC 2000 DCS.

“We intend to have all of our controls running the HART cards, and now that we have all control room and operator stations running Windows XP, eliminating any obsolescence issues with NT or UNIX, we don’t have to spend our time hunting for spares with after-market suppliers,” said Rob Zwick, Teck Cominco’s Superintendent for Process Control.

IPS recently expanded its migration offerings with plug-in I/O modules for migrating ABB Taylor Mod 300 distributed control system (DCS) technology to Foxboro® DCS technology without replacing field wiring or terminations. As with the entire line of plug-in modules, this significantly reduces the cost and downtime associated with migrating aging control systems to the latest generation of IPS’ I/A Series® distributed control and InFusion™ enterprise control systems, while achieving the diagnostic and maintenance benefits of the HART communications protocol.

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