- Published on Monday, 18 March 2013 12:12
- Written by Kate Kunkel
While technological advances, like those developed for the fracing industry, have made possible many processes previously thought near impossible, there is still much work to be done by valve, actuator and control manufacturers and their suppliers to meet the continually changing needs of the power industry.
Many of these technical challenges and developments were covered during VMA’s March 2013 Technical Seminar, as were comprehensive analyses of the trends, technologies and influences affecting America’s power industry. One repeating theme from the presentations was that, while coal will not disappear as fuel to generate electricity, the potential for new coal plants in the U.S. is virtually non-existent. Additionally, because developed nations have basically reached the pinnacle of power requirements due to efficiency in production and use, developing nations will provide huge opportunities for the valve industry.
Another recurring theme was the impact natural gas has had on the power industry. Despite ongoing concerns about continuing reliability and low cost, many new power generation facilities will operate with natural gas. In his keynote address, Kevin Geraghty, vice president of power generation, NV Energy, said, “Watch what happens with natural gas. If it stays low in price, is really abundant and can be recovered in an environmentally acceptable way, it will take a larger share of power production. If it returns to its historical volatility, watch out. We have to have a mix of power generation sources, including renewable.”
Geraghty also pointed out that, while there has been a lot of speculation that regulation has caused the death of coal, that is simply not the case. “Coal units that did not make the current regulations—the weak units—were the ones shut down. They were also not big producers. What will be left are the biggest, most efficient, lowest fuel price units, and they will run even more than they did before.” That does not mean, however, that the path for coal is an easy one, and all energy will be more expensive in the future. He warned, “Despite the lack of current CO2 tax, most people expect that one will be instituted sooner rather than later, and all energy forms will go up 30 to 40%.”
David Gandy, program manager for Technology Innovation at EPRI, echoed the importance of a diversified power system. “We can’t go with just any one or two of the technologies. It will take the entire portfolio if we want to remain competitive. And remember, the existing infrastructure was built over several decades. It takes a long time to transform that kind of system.” Gandy continued, noting that “the fact that there is a lack of a coherent energy policy in the U.S. creates an issue in planning. The fact that environmental regulations, climate policy and renewable energy standards are far from set means it is difficult to set a course.”
In order to have a fully diversified energy portfolio, advanced materials technologies must be an integral part of it. “We are working on advancing ultra-supercritical coal technologies to improve efficiencies and reduce emissions. When you go from 3300 to 5500 PSI, and increase the temperature to 1400°F, you get an increase in overall efficiency from 41.5% to 46% or 47%, so there are substantial increases in efficiency simply as a result of increasing pressure and the overall operating temperature. That requires new materials, though, to get to that 1400-degree range.”
Gandy summarized the situation. “Existing generation will take time and significant investment to replace and upgrade. Advances in technologies will require new alloys, improved materials processes and re-investment in forging capabilities.”
On the Technical Side
In his presentation on valve and material performance expectations in fossil power plants, Tom Love, senior engineer, Duke Power Oconee Station, pointed out that, as power plants aged they may, or may not, have been upfitted with improvements in valves, valve-related products, distributed control systems and environmental equipment. Referring to pulverized coal (PC) units, he said, “They’re rough, tough, heavy…the F350 of the power generation world, and have held up better than ever thought. But over time, PC units, which were designed for base load, were expected to turn down to lower loads as dispatch order changed.”
Problems arose when those workhorse plants had to be turned down, then back up. They were designed to run continuously. And when the plant is lower down in dispatch order as it ages, budgets get tighter, resulting in more problems. “If forced to run at reduced load, there can be dramatic effects on the unit’s heat rate and cycle life of its valves and actuation. It’s like your old second car. First you won’t wax it any more, and then you use cheaper oil. You just do what you have to in order to get it by.”
Codes and Specifications
Neil Kalsi, senior specialist and project manager, Kalsi Engineering, covered nuclear power-operated valve qualification and life extension. He also itemized nuclear design and construction requirements, noting the challenges for new entrants in the nuclear game. They include the expense of implementing a nuclear program and dealing with the Nuclear Regulatory Commission operating environment and related history. “A fundamental shift in thinking and new learning is required when dealing with this,” he said.
Velan’s Paul Major, manager of nuclear design, discussed codes and specifications from the point of view of a North American valve manufacturer supplying to the North American industry, how codes, standards and specifications influence valve design in the power industry. He stressed that, although there are requirements for valves in various sections of the codes, they do not drive the design of the valves. While the codes refer to other standards for valve design and construction requirements, there have not been any significant changes over the years that have forced large changes to the design of a given valve.
Welding was covered in two separate presentations. Scott Smith and Roy Button of CFM/VR-TESCO, LLC discussed in-line weld repairs of valve defects, while William F. Newell of EUROWELD demonstrated, with graphic illustrations, the perils of welding and PWHT (post-weld heat treatment) of P91 steels. Newell also informed attendees about the new ASME IIA rules where minimum hardness criteria are being discussed for all P91 base metal product forms.
Casting quality was brought into sharp focus during a presentation by Ken Juncewicz, senior principal engineer, GE Energy. Juncewicz shared an experience Progress Energy had with large bore C12A valves that had been ordered for HP and HRH steam lines. During routine correspondence with the design company, the company noticed that numerous base metal repairs had been performed on the valve bodies at the valve manufacturer. When Progress requested weld documentation, including filler metal chemistries, PWHT charts and hardness data, serious problems emerged.
The complex process of casting high-quality C12A valves was covered from a supplier’s point of view by Elaine Thomas, director of metallurgy, Bradken Tacoma (Atlas). Thomas enumerated the various stages involved in the process, from molding through testing of the metal to be used in the product, to inspection of the finished product. She also addressed new ASME requirements.
Producing More with Less
Metso’s Mark Buzzell discussed how modern plants are challenged to produce more, with a smaller and less experienced workforce. Increased safety and environmental compliance is a constant and growing concern, and there are also numerous process measurements related to temperature, pressure and flow that are not always directly linked to the performance, status and condition of the valve assembly. To accomplish maximum efficiency and safety at lowest possible cost and downtime, Smart positioners and online valve diagnostics are being used to support a predictive maintenance strategy. Buzzell gave step-by-step advice to help operators take advantage of the newest generation of diagnostics.
In their presentation on specifying electric actuation for the power industry, Bill Breitmayer and Justin Ledger of AUMA Actuators itemized the valves and electric actuators typically used in power plants. Stressing that specifying the proper actuator features is important, they urged consideration of the application, the valve characteristics, what type of motor controls are required, the environment, and what is the primary and control voltage.
The VMA Technical Seminar & Exhibits is an annual event open to the industry. Information about the 2014 meeting will be posted on VMA.org as soon as it is available.