By Lindsay Morris, Associate Editor
Establishing efficient and effective operations and maintenance at a gas-fired power facility is more important now than ever, especially in light of expanding gas-fired generation in the U.S.
At the same time, the Environmental Protection Agency is enforcing rules that will cause power generators to retire some coal-fired plants. What’s more, natural gas prices are at record lows. Natural gas is expected to replace coal as the leading fuel for generating electricity in the U.S. by 2025, according to the latest long-term outlook from Exxon Mobil Corp.
Mike Johnson, director of O&M and service operations for Siemens Energy, Inc, said that gas-fired, combined cycle generation has been the “primary plant configuration of preference” for over 15 years. However, plenty of changes are in the works for gas-fired plants, Johnson said, such as power and efficiency improvements, improved operation flexibility, service interval and life extensions, and even integration with renewable resources.
“Siemens has spent a lot of effort and R&D funding developing services to allow owners to adapt the mode of the operating plant to meet their changing business models,” Johnson said.
The services that Siemens O&M offer includes staffing and technical support to achieve performance and reliability targets, high environmental compliance, operational flexibility, and advanced diagnostics. Another key aspect to Siemens O&M is safety. Advancements continue to be developed to enable O&M services to be executed at world class safety standards.
“O&M makes us look at the holistic plant – not only the gas turbine that sits in the middle, but everything that goes around it,” Johnson said.
One example of the rapidly expanding gas-generation fleet is Chouteau 2, a 540-MW combined cycle gas plant owned by Associated Electric Cooperative Inc (AECI). The plant began commercial operation on June 8, 2011, in Pryor, Okla.
|Chouteau 2 began commercial operation on June 8, 2011, in Pryor, Okla. O&M at the plant is provided by Siemens O&M. Photo courtesy AECI|
O&M services at Chouteau 2 and its mirroring plant, Chouteau 1, are provided by Siemens O&M. Siemens employees have more than a decade of experience at the plant, as Chouteau 1 began commercial operations in 2000. Combined, the two plants can generate up to 1,062 MW.
|Though more than a decade apart in operation age, Chouteau 1 and 2 are operated by gas turbines that were built in the same era. Photo courtesy AECI|
From the start, Chouteau 2 was a unique project. The actual unit was stored in Kingman, Ariz. for 10 years before being purchased, said Bob Pasley, manager of gas plant operations for AECI. It was originally built for use on a project in Arizona, but when some aspects of the project were abandoned, it met a temporary fate of sitting in storage for 10 years.
|The gas turbine for Chouteau 2 has been referred to as a “power plant in a box” by Siemens and AECI after having been in storage for 10 years due to an abandoned combined cycle project. Photo by Lindsay Morris|
“We call it a power plant in a box,” Pasley said.
After a decade of dormancy, AECI was offered a price on the unit and accepted it.
“The reason the technologies are so close but almost 10 years apart from when they were placed into service is that both gas turbines, the steam turbine and all associated equipment were manufactured in the 2000, 2001 era,” Pasley said.
|Brian Heard, senior combustion turbine specialist, AECI, and Bob Pasley, manager of gas plant operations, AECI, at Chouteau 2. Photo by Lindsay Morris|
During the engineering and design phase of Chouteau 2, AECI and other stakeholders visited a sister Siemens V84.3A2 unit in Georgia. Reviewing operating experience at this plant led to the replacement of some now obsolete equipment, such as the de-aerating pump on Chouteau 2. Access issues were reviewed from the beginning with the plant operations at the engineering and design stage rather than waiting until the completion of the project. Johnson said that visits like these among Siemens O&M plants lead to a “knowledge sharing across plants” that proves valuable.
Shortly after Chouteau 2 began operation, its employees and O&M capabilities were put to the test. On June 26, just two weeks after operations commenced, the plant was called upon for power. Since that time, Chouteau 2 has achieved greater than 99 percent reliability. During the summer, 394,269 MW-hours were produced during record high summer temperatures in the Midwest.
Chouteau 1 and 2 have subtle differences between them. The basic technology is the same, Pasley said.
“The differences,” he said, “are that we added more enhancements like burner light and pre-heated gas, and ceramic tile modifications to the V machine combustion chamber.”
Chouteau 2 has also been upgraded to the Siemens T3000 – “the newest, latest and greatest controls,” said Brian Heard, senior combustion turbine specialist.
While some power plant owners choose to perform their own O&M, AECI has found Siemens O&M to be a good fit.
“Hiring an O&M allows us to have a larger pool of resources,” Pasley said. “They keep us aware of the latest fleet issues which keeps our plant reliability rate up to speed.”
Johnson said that Siemens O&M typically meets with plant owners on a quarterly to annual basis to talk about how the business environment is transforming. Discussions could range from transitions in power contracts to load capability in the region. “If their mode of operation is changing, we can quickly make the changes to maximize the asset.”
One benefit of gas or combined cycle operations is that they typically require a smaller staff than coal-fired plants, Pasley said. “Typically a 1000 MW coal plant could staff more than 150 people.” The Chouteau plant, however, employs just 34 people.
With a relatively small staff, Pasley said the concept of “crosspollination” is important – multiple duties are often spread out to each individual. The plant engineer may also be the environmental compliance manager; a senior operator may also be a safety commander. “We label our staff as highly effective individuals, highly trained, multi-skilled.”
Johnson said Siemens prefers this method of “crosspollinating” its employees for several reasons. First, a larger skill set integrating technical, operational and maintenance aspects often leads to deeper career development satisfaction, he said. Crosstraining also leads to elevated performance. “Staff knowledge of how all the equipment is integrated and how to respond to changing conditions is critical,” Johnson said.
Additionally, the cross-training method provides a training ground that allows Siemens to exchange between plants without difficulty. “We can move associates from site to site quickly,” Johnson said. “This hastens the learning period for a new plant.”
When it comes to operations, the Chouteau plant experiences about 200 starts and stops each year, Heard said. Even if the plant is down 24 to 48 hours, the staff is able to get the plant up and running in about an hour and a half.
“That requires a different type of work force, a different way to plan, a different attitude within your employees,” Pasley said.
Johnson said that advanced combined cycle plant O&M also takes a different type of employee. Individuals who enjoy multi-tasking typically find more ownership and fulfillment at a combined cycle plant due to the smaller plant staff sizes.
Although Siemens is involved in every aspect of power generation, Johnson said that gas-fired, combined cycle O&M is the “sweet spot of Siemens power generation right now.” Siemens continues to be an innovator in O&M with a strong commitment to R&D along with an extensive portfolio of service products and solutions which are customized to provide greater long-term value to our customers.
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