Select I/O sweetens sour gas project

By Jim Montague

Mar 06, 2019

Not all natural gas is created equal, and removing unhelpful and toxic elements at Wapiti's sour gas facility in northern Alberta, Canada, requires specialized equipment and controls. Because cleaning H2S, propane, butane and other impurities is mission-critical for the plant and worrisome for its operators and manager, Wapiti recently got a much-needed boost from an upgrade by system integrator Blackrock Automation with ABB's Select I/O and System 800xA automation platform.

The facility processes about 200 million cubic feet of sour gas per day, and was seeking a single I/O solution and standard, remote cabinet approach, which could enable hardware on site sooner and keep pace with its aggressive schedule. Overall, the project included 27 Select I/O remote cabinets for service in the plant's -40°C and Class I, Div. 2 environment; System 800xA control system with 2,300 Select I/O and 300 S800 control-related I/O; and 16 Allen-Bradley PLC packages connected via PLC Connect. The project also featured motor-control-center (MCC) communications with more than 40 Multilin relays and variable-frequency drives (VFDs) via Profinet.

"It was -42°C when we started up, but there were no equipment problems. The whole project's mechanical and electrical systems worked well, and we came in two months early and under budget," said Galen Wilton, senior system integrator at Blackrock. "Startup took just two days to selling gas, and the client was so proud that they announced it on the local radio." Wilton was part of a panel discussion about Blackrock and Wapiti's upgrade at this week’s ABB Customer World in Houston.

Hardware and software design decoupled

Select I/O was developed to meet the needs of users just like Wapiti, reported Robert Norberg, I/O systems global product manager, ABB. "Traditional, controller-centric I/O solutions promote an inflexible, serial, sequential project execution model in which project tasks depend on each other, resist changes and cause change orders and delays," he said. "The result of process automation being on the critical path is large cost overruns and late delivery on large capital projects.

"This is why System 800xA's Select I/O, S800 on Ethernet, and xStream Engineering are so useful to these applications. They can minimize the impact of late changes; decouple project tasks, so they can be done in parallel; and reduce testing efforts needed as well as required footprints," explained Norberg.

"When projects plan to execute, the date everyone usually wants to know is the design-freeze day,” said Brad MacDonald, product marketing manager, ABB. “With Select I/O, they don't have to worry about it anymore. Now, they roughly determine how many I/O are needed, but don't have to care what type because Select I/O's common template can connect to so many different devices.

"In Blackrock's case, the design started with 1,200 I/O, but ended with 2,400 I/O because of added pipes and other devices,” said MacDonald. “In the past, this would mean huge and costly change orders, but now they can simply order extra I/O as needed and expand to accommodate them. What's so cool about splitting design engineering off from cabinet assembly and installation is that it finally takes automation off the critical path."

Architecture and network

Wapiti's remote I/O cabinets were designed in Fall 2017, configured in February 2018, built in April-May 2018 and installed and wired in July-October 2018, which included client factory acceptance testing (FAT) of configuration in August-September 2018. I/O loop checks and commissioning were done in late 2018, and production began in January 2019, said Wilton.

"The customer compared I/O solutions from Emerson, Honeywell, and ABB and was most impressed with ABB—it was an easy selection for them," said Kyle Hyland, senior system integrator, Blackrock.

The control and network architecture at Wapiti includes two virtual servers, two servers working as historians, four operator stations, three engineering stations, links via PLC Connect to EtherNet/IP and two PM891 controllers in two S800 cabinets networked with Modbus and Profibus for remote MCCs.
"We installed 27 remote I/O cabinets each with six module terminal units (MTUs) and 96 I/O per cabinet," explained Wilton. "We also had fully redundant power and heaters to comply with our Class I, Div. 2 design. The virtual servers meant we could set up and test at Blackrock's office in Calgary, and staging there and running the whole project in simulation was a big help. We also liked using System 800xA because its combined software package for functions like PLCs and HMIs meant we didn't have to implement them separately."

Hyland added, "System 800xA can also show trends, and give users all the data they like to see. Plus, we can just drop in new software objects, and they'll quickly show trend data."

Wilton agreed that System 800xA was easy to learn with a little coaching from ABB. "It was especially nice to have software-based controllers that we could test, and they're also allowing us to make adjustments, add features and even use them for training," said Wilton. "As a result, we were also able to field-test all the cabinets in just two or three hours. Select I/O also saved a lot on cable by allowing us to use more flexible switching devices between panels and reassign them as needed. As a result, most changes were no longer about asking for money, but were about new ways to save money."

MacDonald added, "Select I/O and System 800xA can save users 30-40% on the cost of projects by eliminating much of the engineering and cabling that was previously required."

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