While the Latin root for the word “super” simply translates to “above,” for those of us who grew up with comics, movies, and cartoons of Superman, the word raises our adrenaline and we become “super” excited. Thus, it is no surprise when we talk about supercritical fluids that the average turbomachinery engineer starts to hyperventilate. As engineers, we also love critical things—albeit it is not totally clear why. There are critical speeds, critical loads, critical Reynolds numbers, etc., and they all separate the normal from the abyss. They also often describe situations that are difficult to calculate and interesting to investigate, which may make them cool … and super is even better than critical.

is often used in its original sense—above or beyond—supercritical is not in the abyss but on the other side. A supercritical speed for a rotor is a speed that is (usually) higher than the first critical speed—we learned how to operate at supercritical speeds about 150 years ago … ergo, nothing to worry about. Now, a load beyond the critical load may cause something to break or buckle, so sometimes bad things do happen beyond critical.

Any gas or gas mixture has a critical point at a critical pressure and temperature. This can be seen on a phase diagram where the fluid’s gas phase line intersects its liquid phase line at the highest gas temperature. For CO

, the critical point is at about 30° C and 74 bar pressure. Water’s critical point, on the other hand, is at about 374° C and 220 bar; Methane is at -83° C and 46 bar. The critical pressure and temperature for CO

, unlike many other substances, are well within pressures and temperatures often encountered in typical gas compression applications, such as heat pumps, carbon sequestration, and sCO

 Rankine power cycles. For any substance, if temperature and pressure exceed the critical point, distinct liquid and gas phases cease existence. (Note: This is only true as long as the pressure stays below solid-forming pressure, which for CO

 is somewhere in the range of several thousands of bar, and for all practical purposes not relevant for this discussion.) A good example is the atmosphere of Venus, which is 96.5% CO

 and 3.5% nitrogen. There the surface pressure is 93 bar, and the surface temperature is 462° C, which is well above the critical points of both major constituents, thus making the surface atmosphere of Venus a supercritical fluid.

Above the critical point, fluids are in their dense phase, characterized by high density (comparable to a liquid) but maintain the low viscosity of a gas. In the dense phase, the fluid does not form a free surface as a liquid would, but the fluid is still somewhat compressible— although the compressibility, i.e., density change with pressure, is relatively low. This is quite advantageous for transport purposes in pipelines since longer-distance transport is possible with a smaller power demand for compressors or pumps than transport as a gas. Thus, most long-distance transport of CO

 for carbon sequestration will likely be performed under dense-phase conditions but will require pipelines rated for 150 bar (2,200 psi) to reliably keep the fluid in the dense phase. It is important to understand that dense-phase conditions do not imply that the fluid is completely incompressible, so depending on pressure and temperature, either pumps or compressors can be used for pipeline transport or injection.

However, for the turbomachinery designer, the critical point of any fluid itself is considered pure unadulterated evil. It is like the juvenile delinquent that lives on your street who you keep your teenage daughter as far away from as possible. We try to avoid operating near the critical point at all costs. The reason is that most physical properties of a fluid, such as density, speed of sound, viscosity, specific heat, etc., change drastically near the critical point, i.e., physical properties have steep gradients with respect to pressure and temperature changes. This makes it nearly impossible to accurately design a compressor or expander for stable and predictable operation near the critical point. Thus, when designing a turbomachine, we usually select operating points at pressures and temperatures far, far away from a fluid’s critical point.

 is supercritical at pressures and temperatures above the critical point, about 30° C and 74 bar. This is well within the normal experience range for turbomachinery. There are interesting things happening in this region. When CO

 is kept above its critical temperature and pressure, it acts like a gas yet has the density of a liquid. In this supercritical state, small changes in temperature or pressure cause dramatic shifts in density, making sCO

 an attractive working fluid to generate power. The high density allows for machines with an extremely high-power density. Since CO

 is readily available, non-flammable, and non-toxic, it lends itself as a working fluid both for power cycles and high-efficiency heat pumps. Closed-loop Brayton cycles using sCO

 allow for increased efficiency and a substantially smaller footprint (both physically and environmentally) compared to air Brayton and steam Rankine cycles. This also applies to bottoming cycles for gas turbine waste-heat recovery. Additionally, because the heater and cooler do not involve evaporation or condensation, the temperature differences between the process fluid and heating/ cooling fluids are minimized, which decreases losses in the heat exchangers and improves achievable cycle efficiencies.

 very attractive for several applications, and indeed many organizations are building heat pumps, power cycles, bottoming cycles, and pipelines that take advantage of the behavior of sCO

Klaus Brun is the Director of R&D at Elliott Group. He is also the past Chair of the Board of Directors of the ASME International Gas Turbine Institute and the IGTI Oil & Gas applications committee. 

Rainer Kurz is a recent retiree from Manager of Gas Compressor Engineering at Solar Turbines Inc. in San Diego, CA. He is an ASME Fellow and has published over 200 articles and papers in the turbomachinery field. 

Articles

Supercritical CO2 (sCO2) may not have superpowers, but turbomachinery operators try to avoid working near the critical point at all costs.

Myth Busters: What's so Super About Supercritical CO2?

Steam turbines have been widely used as drivers for different machinery and equipment, and are used in many industries, facilities, and plants. Steam turbine governing, a component of the turbine’s control system, controls the flow rate of steam to the turbine to regulate its speed. Speed varies due to changes in the load/operation. Therefore, the control system should constantly adjust to the turbine’s operation.

There is a wide range of control options for steam turbines to meet the varying needs of different services and applications. A suitable control system should be developed for each application.

There are two basic types of steam turbines: condensing and back-pressure. Condensing steam turbines operate with exhaust pressures less than atmospheric pressure; back-pressure steam turbines operate with exhaust pressures greater than atmospheric pressure. Condensing steam turbines tend to be larger in size and power rating while back-pressure steam turbines are smaller in size and usually operate at faster rotational speeds.

Steam turbines can be used in direct-drive trains, but they often operate the driven equipment, i.e., a pump, compressor, generator, etc., through a speed-reduction gear unit. This allows the steam turbine to be configured to the optimum speed and efficiency for relatively low-speed-driven applications.

The modern digital steam turbine control system is designed to control the main steam flow to the turbine under all operational conditions using the turbine throttle, governor, and control valves. A control system should ensure stable operation throughout each phase, including start-up, shutdown, parallel operation, etc. Full-load rejections are critical cases and should be controlled to prevent an over-speed condition and potential damages.

Speed and load controls are usually required. The speed control is the primary control loop for many steam turbines. Without speed control, it cannot reliably and safely start or operate. The steam inlet is controlled by a series of valves, often multi-valve assembly, working in concert. Typically, one steam control device can only control one parameter. The operational flexibility is increased when the controlled parameter’s set point is influenced as a function of secondary parameters. For example, the steam turbine’s inlet steam valve controls the turbine speed, but exhaust pressure can be used to bias the speed set-point to maintain some level of exhaust pressure. This is an example of how parameters other than speed come into play, but the speed control loop ultimately ties back to the inlet steam valve system.

The actual speed (measured speed) should be weighed against the desired speed. Adjustments are then made to achieve speed balance, which is the set point. This balanced system is the heart of the control system. The logic and method of control implementation influence the turbine’s operation. The speed control loop can control the load by raising or lowering the speed reference to open or close the inlet governor valves and influence the flow of steam through the turbine. In this way, the change in steam flow may not change the speed; however, it will change the load (power) depending on the flow change. Load control may be secondary for back-pressure or extraction turbines but is still a controlling parameter. For condensing turbines, load control is usually an important parameter.

In addition to speed and load, inlet pressure and exhaust pressure are also steam turbine-related parameters that are part of the turbine control system. Inlet pressure is controlled by manipulating the inlet governor valve system. A bias related to inlet pressure actual versus set-point values should be applied to the speed control loop. This bias is accomplished by incorporating cascade control into the system.

Exhaust-pressure control is utilized only with back-pressure turbines and comes into play when the exhaust steam is used in a plant that requires close steam pressure control. As with inlet pressure, exhaust pressure is usually controlled by manipulating the inlet governor valve system. A bias should be applied to the speed control loop related to exhaust pressure actual compared to the set point. Like inlet pressure, cascade control is often incorporated into the control system.

Steam turbines are often employed in mechanical-drive applications involving driven equipment such as pumps, compressors, blowers, fans, etc. Parameters directly related to the speed of the turbine are controlled by adjusting the output signal in the control system limited to the driven equipment’s output parameters, such as discharge pressure or flow. In this case, the control resides inside the turbine system alongside the speed-control function.

The second option is to control the turbine speed via the remote speed set-point through a process controller or a remote-control system that calculates and sends a corrective signal to adjust the speed reference. In this arrangement, all control algorithms relative to the process are external to the turbine control—it only receives the corrective speed signal. This arrangement is used when the process is distanced from the steam turbine or the turbine speed is indirectly related to the ultimate process under control.

Amin Almasi is a Chartered Professional Engineer in Australia and the U.K. (M.Sc. and B.Sc. in mechanical engineering). He is a senior consultant specializing in rotating equipment, condition monitoring and reliability.

A steam turbine’s control system should ensure stable operation throughout each phase: start-up, shutdown, and parallel operation.

Turbo Tips: Useful Guidelines & Technical Notes on Steam Turbine Control Systems

Regal Rexnord, an industrial manufacturing company with roots dating back to 1955, specializes in components and systems to transmit and control motion within the power transmission market. Headquartered in Milwaukee, WI, the company is known for its Kop-Flex diaphragm and disc couplings and Powerlign torque monitoring system.

Regal Rexnord doesn’t stop its work at the manufacturing stage—its customers and components are supported through its recertification program that offers maintenance and emergency labor for lifecycle extension.

A coupling in turbomachinery applications connects the driver to driven machinery while accommodating axial and radial misalignment caused by machine movement and thermal growth. Regal Rexnord manufactures a range of flexible couplings designed to accommodate this torque, including the Kop-Flex, Bibby Turboflex, Ameridrive, and Euroflex models.

The Kop-Flex couplings are available in a diaphragm or disc format and are suitable for high-performance turbomachinery, with variations that suit the application requirements. Regal Rexnord implemented a compact, low-weight, high-power density design into its Kop-Flex couplings as gas turbines and compressors evolve toward smaller footprints and higher speeds. It comes in two styles: the RM and RZ.

“The RM is a full-featured disc coupling, providing a reduced windage design and interlocking flanges for additional protection in the event of a disc pack failure. The RZ coupling provides a more cost-effective solution and lowest overhung moment with non-interlocking flanges,” said Oliver Doidge, Global Product & Business Development Manager, Regal Rexnord.

The Ameriflex diaphragm coupling tolerates large misalignments with low stiffness through its soft, multi-convoluted design. Regal Rexnord supplies Ameriflex couplings for mobile power-generation packages that require exceptional amounts of misalignment capabilities during transport and operation.

“In recent years, the development of mobile power-generation packages for grid expansion, power for fracking, and even disaster relief require larger amounts of misalignment than normal industrial applications and have been accommodated by the Ameridrives engineers through detailed analysis and optimization to suit,” said Doidge.

Euroflex disc couplings are designed for numerous applications within oil and gas—such as test benches, compressors, and steam and gas turbine power generation. Bibby Turboflex is a brand wholly owned by Regal Rexnord producing customized couplings for oil and gas industries and other markets, including marine propulsion, aerospace and defense, mining, and more.

Powerlign is a monitoring system that measures the coupling’s torque, power, and speed, offering real-time data on a customer’s critical rotating machinery. This data allows operators to conduct proactive maintenance and cost-effectively diagnose issues before the complete failure of a system. Powerlign tracks performance differentials and over-torque for driving and driven machinery, identifying issues such as blade fouling, coupling shaft failure, or overall equipment failure.

According to Doidge, immediate data feedback gives customers a significant advantage. “Because the system provides real-time monitoring, our customers can tell when to shut down rather than just doing so on a monthly or 90-day schedule. Customers save money by following this process because they are cleaning less or more often, which improves overall efficiency and uptime while reducing the need for the expensive and environmentally harmful cleaning fluids used.”

Powerlign can integrate with distributed control systems, PCs, and laptops for flexible system data analysis. It also works within a closed-loop system, as it can establish thresholds that, once reached, trigger an alert or alarm for end-users. Regal Rexnord implemented a feature so Powerlign acts as a control system, shutting down equipment or directing equipment in the flow of gas or fuel to secure load and efficiency.

Regal Rexnord offers comprehensive customer support through its recertification program, focusing on maintaining couplings that have endured extended operational life and increased misalignment. The program represents a proactive maintenance strategy that restores couplings to a newer condition at a lower cost than outright replacement, reinforcing the reliable operation of rotating equipment.

“With this program, our customers can ensure that their power equipment stays in peak operating condition and minimizes the costs of unplanned downtime, replacement parts, and emergency labor,” said Doidge. “We created the program for Kop-Flex couplings, but it has been expanded to include all Regal Rexnord brands. The company continues to develop its service and commitment to its installed base and user community with a larger global footprint and by increasing the number of facilities across five continents.”

LNG continues as a primary market for Regal Rexnord’s portfolio of coupling brands, with market growth demonstrated by large-scale projects across the United States, Asia, the Middle East, and Australia. The company’s engineers continue to develop customized systems and solutions for larger, higher-speed turbomachinery applications.

As an emerging fuel for power generation and other industries, hydrogen requires engineers to take a second look at current equipment to assess how it can be adapted to meet the fuel’s demands and develop newer technology. Regal Rexnord is applying this new perspective to its own portfolio.

“Within the industry there is an increased demand for hydrogen compression, meaning that the speeds of the compressors are getting faster and faster,” said Doidge. “Our research and development teams are working closely with our customer base to ensure that we are aligned with this demand, have products that are suitable for these applications, and support them in prototype testing.”

Regal Rexnord manufactures products for turbomachinery applications, including diaphragm and disc couplings.

Vendor Spotlight: Regal Rexnord

Gas turbine lubrication systems are commonly plagued by varnish formation. Although top-treat solvency enhancers, varnish filtration technology, system cleaners, and flushing are solutions to varnish in a turbine lubricating system, the best and most effective approach is not letting it form in the first place.

Varnish results from oil degradation accumulating beyond the oil’s capacity to keep it solubilized. High temperatures, cavitation, electrostatic discharge, and the presence of catalytic contaminants are all potential contributors to the degradation of lubricant molecules. Regardless of the source, once the oil has become saturated with oxidation and thermal degradation byproducts, it will deposit these components as varnish throughout the system. While steps can be taken to delay degradation through additives and operating conditions, oxidation is not preventable; it is inevitable, as defined by the laws of thermodynamics. However, it is highly predictable and can be managed so that the negative consequences of excessive degradation, i.e., varnish, are preventable.

Creating, utilizing, and executing a proper turbine-oil lifecycle management strategy ensures a varnish-free lubricating system for the entire fluid-drain interval.

Select a lubricant that provides excellent resistance to varnish formation.

Perform the correct oil analysis tests at the right sample intervals.

Proactively manage the varnish tendency of the fluid as it ages.

Schedule an oil change once the data indicates the fluid is nearing the end of its useful life.

The key to maximizing the life and performance of your turbine oil is to give it a clean, contamination-free environment from the start. For new units, that means flushing the system with a sacrificial change of oil before the initial fill. For a system undergoing a service-interval change, that means ensuring there is no residual varnish or degraded oil from the previous fluid that could contaminate the new oil. For systems known to have varnish or suspected varnish, use one or more mitigation technology, such as varnish filtration, varnish solvency enhancers, and/or oil system flushing.

While many commercial lubricant technologies advertise properties that meet the basic fluid requirements for turbine manufacturers, not all these fluids will provide equal, long-term performance in application. Additionally, there are multiple technology approaches to fluid formulation for varnish resistance. Using a technology with robust, inherent varnish resistance and solubility provides an advantage in managing the fluid lifecycle and achieving a long useful oil life.

A critical component of managing the oil’s lifecycle to prevent varnish formation is performing the proper oil analysis tests at the correct intervals. The table below details the tests and intervals that should be utilized for varnish formation prevention. The most important sample in the turbine oil process is the first sample taken in the fluid’s life: It should be pulled in the first 8 to 24 hours. This sample will serve as the baseline for all future sample comparisons. A fresh, uncirculated sample as the baseline is not recommended.

All oil degrades with time and use, and thus it will eventually reach the end of its useful life regardless of prevention and intervention. However, measures can be taken to maximize the oil’s useful life, especially concerning varnish potential. Varnish formation is preventable by ensuring the oil does not exceed its solubility for varnish precursors and degradation byproducts. Using the prescribed analysis protocol provides the necessary information to keep ahead of this occurrence. As data predicts cautionary levels of degradation components in the oil, mitigation technologies, such as varnish filtration units and a varnish solvency enhancer, can control the accumulating degradation components.

Once the oil-testing data indicates the oil is nearing the end of its useful life (6 to 18 months), begin making plans to replace the current fluid. A varnish solvency enhancer and an intermediate flush ensure the system is clean for the new fluid and help maximize its potential.

Varnish can be prevented. Following the prescribed key components to fluid lifecycle management provides the best approach to maximize the life of your lubricant and remain varnish-free.

Christopher Knapp is a Product Application Specialist at Shell Lubricant Solutions.

A proper turbine-oil lifecycle management strategy ensures a varnish-free lubricating system.

Varnish is Preventable

The Niagara Falls region has been a hotbed for harnessing hydropower since the mid-1700s when power was initially obtained by diverting water from the falls to turn waterwheels at a small sawmill—an early form of the hydro turbine. Since then, advancements in hydro turbine technology and the buildout of hydroelectric plants transformed the region into an epicenter of continuous sustainable power.

Today, hydroelectric power plants in the Niagara Falls’ Canadian region generate almost 2 million kW of electricity, while the American plants—Robert Moses Niagara Power Plant and the Lewiston Pump Generating Plant—combine for more than 2.6 million kW. Between these two plants, a combined 25 turbines are being spun. In fact, Niagara Falls is New York State’s biggest electricity producer. According to the U.S. Department of Energy, hydropower accounts for 28.7% of the country’s total renewable electricity generation and approximately 6.2% of total electricity generation.

The Ontario region, via a partnership between Ontario Power Generation (OPG) and GE Vernova, established a 15-year plan to refurbish up to five hydropower plant stations; this includes up to 25 units at the Sir Adam Beck Complex in Niagara Falls—increasing its capacity by up to 50 MW. The hydroelectric refurbishment plans will help secure up to 1,700 MW of clean electricity and extend their life by another 30 years.

Hydropower stations house complex rotating machinery that is exposed to environmental elements, varying elevations, and more, day in and day out. But there is no one-size-fits-all turbomachine used in hydropower plants.

“In a hydropower plant, the rotating machines—turbines and generators—convert the mechanical energy of flowing water through the units into electrical energy delivered to the grid. According to the site characteristics, mainly the differences in elevation between upstream and downstream reservoirs or river levels, different kinds of turbines [can be installed],” explained Jean-Michel Milles, Hydro Power Head of Engineering at GE Vernova’s Hydro Business.

TYPES OF TURBINES AND ROTATING EQUIPMENT AT HYDROPOWER STATIONS

Milles reviewed the three most common hydro turbines:

Pelton turbines are used for heads between 200 and 1,000 meters. 

Francis turbines are used for heads between 50 and 300 meters.

Kaplan units are for heads lower than 50 meters.

“For pumped storage plants—where water is transferred from upstream reservoirs to downstream reservoirs (in generation mode) and then back to the upstream reservoir (in pump mode)—‘reversible Francis’ turbines are coupled to a motor generator,” he said. “These pumped storage plants are becoming increasingly important to stabilize the grid due to the growth of intermittent renewable energy sources like solar and wind. The rotational speed of the turbine and generator is also driven by site characteristics and targeted unit output, which results in a wide range of speeds—from around 60 rpm for large units under low head to around 1,000 rpm for small units under high head.”

One of the major differences between Kaplan turbines and other hydraulic turbines, such as Francis or Pelton, is they have movable blades assembled on a hub so that the blades are not attached to a shroud.

“These movable blades maintain a high efficiency on a wide operating range, but since the blades only attach to the hub and not to a shroud, they can only sustain low heads of up to 50 meters,” Milles said. “The typical arrangement of a Kaplan is with a vertical rotational axis, but for very low heads, horizontal-axis turbines have adjustable rotor blades with a straight intake, straight diffuser, and generator located in an enclosure inside the flow. This leads to an even higher performance with a unitary output limited to around 90 MW due to the generator arrangement—these are called bulb turbines.”

A hydro turbine’s efficiency may decrease due to energy losses, including friction losses or losses due to the poor incidence of water on the turbine blades. Components within these turbines, such as adjustable rotor blades and inlet guide vanes, are designed to maximize the efficiency of hydropower operations.

“The role of the inlet guide vanes is to improve the flow incidence on the rotor blades over the whole head range of the unit,” Milles added. “Then, when the turbine is equipped with adjustable rotor blades, as is the case for Kaplan units, these adjustable blades deliver a flow that helps to reduce energy losses in the rotor itself and in the components downstream over the whole discharge range of the unit.”

Upkeep of hydro turbines requires periodically checking for seals, clearances, status reports on some components such as bolts and profiles, and replacing worn equipment as needed.

Maintenance considerations differentiate the upkeep of these units from land-based turbomachinery. “Compared to a gas turbine, the components of the hydro turbine are not exposed to very high temperatures; on the other hand, maintenance of a hydro turbine is significantly driven by site characteristics, such as the water quality,” Milles said. “Chemical composition and the quantity of sediments influence water abrasiveness and/or erosion and can impact component lifetime.”

While the hydropower space continues to expand—GE Vernova has more than 6,000 MW of projects under development globally—the technology itself is mature, but Milles said that doesn’t mean hydropower is not constantly innovating. Modified processes, implementing outside technologies, and environmental considerations are driving forces behind trends and innovations.

“In recent years, there has been a focus on increasing the flexibility of the hydropower plant to help increase performance, but more importantly to help stabilize the grid through wider operating ranges, start-and-stops, hydraulic short circuits, and more,” Milles said. “Also, we’ve seen some key innovations such as robotic inspections to improve maintenance activities and fish-friendly turbine designs for environmental purposes.”

Hydropower’s continued use as a renewable energy source requires complex hydro turbines and other rotating machines to electrify many regions worldwide.

A History of Hydropower and Turbomachinery

Steam turbines are widely used in mechanical drive and power generation applications. As they serve as the backbone of many power and chemical plants, these machines are subjected to rigorous operational demands. It is therefore important to maintain their optimal performance and longevity. Unfortunately, traditional inspection methods are increasingly inadequate in meeting the evolving demands of turbine maintenance. The inherent limitations of these methods pose a significant risk, as undetected issues can lead to disruptive failures, resulting in costly repairs and downtimes.

Recognizing the imperative for a more sophisticated and reliable approach, Mitsubishi Heavy Industries Compressor International Corp. (MCO-I) implemented an advanced solution: PAUT. As a relatively new technology in steam turbine rotor diagnostics, PAUT aims to redefine the industry’s approach to protecting the health and longevity of these critical machines, boosting efficiency in steam turbine maintenance. 

PAUT is a non-destructive testing technique that employs multiple ultrasonic elements and advanced signal processing to provide insight into the condition of steam turbine blade attachment areas. MCO-I employed PAUT, which is implemented daily in the medical field, to improve safety and preventative maintenance.

Unlike traditional methods, PAUT’s ability to scan with improved accuracy ensures that anomalies as small as 0.020 - 0.030 inches can be identified. By detecting corrosion pitting or crack-like indications in their early stages, PAUT provides a proactive defense against potential turbine malfunctions that could lead to catastrophic failures. The early identification of rotor damage symptoms allows for timely intervention and targeted maintenance, mitigating the risk of unexpected failures and ensuring the sustained reliability of steam turbines.

PAUT technology provides inputs for a detailed analysis of the structural integrity of turbine components. This assessment not only identifies existing flaws but also offers insight into the remaining life of the components. Armed with this predictive data, turbine users can implement proactive maintenance interventions, improving the reliability of the turbines and mitigating the risk of unexpected failures.

One of PAUT’s key contributions is identifying potential stress corrosion crack indications early, enabling customers to employ strategic upgrades involving improved corrosion-resistant materials. This proactive approach reduces long-term maintenance costs and ensures the entire turboset’s long-term reliability.

By shedding light on potential issues that may compromise the integrity of turbine components, PAUT has proved on many occasions to be an effective tool in maintaining cost-effective, long-term operation.

PAUT is an asset in identifying sub-surface flaws, especially in rotors. Pinpointing vulnerabilities allows clients to make informed decisions about material upgrades. This strategy enhances the resistance of the system against corrosion damage and minimizes the likelihood of unexpected failures and associated operational disruptions.

Through a PAUT inspection and a subsequent remaining life evaluation, a customer discovered that they only had seven years left on their rotor. This discovery prompted them to revise their maintenance strategy, planning, resource allocation, and budgeting for a new rotor well in advance. This proactive approach contrasts with the potential surprise and financial strain that might have ensued without the insights of PAUT.

Another customer detected damage to their turbine rotor while using PAUT. This early detection allowed for immediate corrective action, averting potential failures that could have resulted from waiting. Traditionally, without the capabilities of PAUT, such damage might have gone unnoticed until a critical stage was reached, leading to severe consequences for the turbine’s reliability, operational safety, and plant production outlook.

In one case, PAUT implementation shared valuable insight into the reliability of current components, prompting a decision to upgrade the rotor’s corrosion resistance with a stainless-steel rotor overlay. It was demonstrated that improvements in rotor reliability could be achieved, even when compared with the performance of a new rotor.

The successful utilization of PAUT hinges on the collaboration between service providers and customers. To ensure the efficacy of PAUT inspections, customers are required to provide vital information about the size, location, and environmental conditions of the rotor under examination. In cases where the rotor is not a Mitsubishi product, customers provide details about the original geometry of the machine, such as spacing between the disks or blade rows.

This information exchange serves as the foundation for tailoring PAUT inspections to the unique specifications of each turbine. By understanding the intricacies of the rotor’s dimensions, inspection areas, and the environmental factors to which it is subjected, PAUT can be customized for optimal accuracy and thoroughness. Moreover, this inspection approach is not merely a one-time event but is recommended as part of a proactive strategy, particularly at the service life milestone of 10 years.

PAUT can play an important role in ensuring the reliability and safety of steam turbines. PAUT’s efficacy in detecting cracks, assessing remaining life, and addressing stress corrosion cracking is thoroughly examined in the context of turbine inspection and maintenance, highlighting its accuracy and ability to shape decisions on optimizing performance through strategic maintenance schedules. PAUT technology paves the way for clients to proactively address challenges, meet production goals, and make strategic investments in the longevity and reliability of steam turbines.

Justin Fleming is the Customer Service Business Director for Mitsubishi Heavy Industries Compressor International Corp. at the Pearland Works facility in Houston, TX.

Implementing phased array ultrasonic testing (PAUT) in turbine inspection and maintenance marks an evolution from traditional maintenance to more advanced solutions that ensure efficiency and reliability.

Improving Steam Turbine Reliability

hosted Joseph Bonafin—Sales and Business Development Manager at Turboden, a part of Mitsubishi Heavy Industries Group—on the TurboTime Podcast to discuss geothermal power generation. Bonafin dives into the history of geothermal power, how it’s grown over the past 20 - 25 years, its place in the decarbonization journey, and more.

Q: What role does turbomachinery play in a geothermal plant?

The turbomachinery is the rotating part that converts pressure in the organic fluid into work and electricity by spinning a generator. Pressure in the organic fluid is created by a heat exchanger transferred from a geothermal source, so no geothermal fluids are used. A closed-and-tight circuit generates emissions-free power.

Turbomachinery is key to having an efficient and reliable baseload generation with low maintenance costs.

Q: What goes into designing, manufacturing, and constructing a geothermal plant?

Turboden is involved in the main steps of a geothermal project—from front-end engineering and design to the procurement and construction of the power plant, and remote monitoring and operation.

A geothermal project requires a multi-discipline approach: geochemistry, reservoir engineering, thermodynamics, turbomachinery design, electrical engineering, and metallurgy. We embrace all these disciplines, starting from our core know-how: power plant and turbomachinery design and control philosophy. Not only is engineering required but also financial skills are needed to implement a project. Being part of a multinational group such as Mitsubishi Heavy Industries, we can leverage many instruments to facilitate the export of our equipment, such as export credit financing or grant mechanisms for CO

Q: How has demand for geothermal power plants grown over the past 25 years?

As of today, there are roughly 16 GWs of geothermal plants installed worldwide. The organic Rankine cycle (ORC) is the fastest-growing technology in the geothermal power generation market. ORC has doubled its share among all types of geothermal generation systems in the last five years, adding about 2 GWs of new plants. Exploiting the full range of resources—from low to high temperatures, liquid to steam, and remote locations such as high-elevation deserts or islands—and installing ORC power plants close to inhabited areas show the benefits of this trending technology.

Turboden has experience with power plants delivering both electricity and heat to the district heating networks, and I see more and more of these projects, especially in Europe. A new trend that is quickly expanding is higher-temperature and larger-capacity ORC plants. There is a natural synergy between ORC and enhanced geothermal systems— new drilling technologies allow the fluid to be fully injected by mining the heat and exploiting the thermal energy from the ground, giving back the fluids at a lower temperature. This synergy between power-plant technology and new drilling technologies is the only way to scale up geothermal applications among other renewables.

Q: How is geothermal power generation a pathway to decarbonization? What are its limitations, and what recent advancements have been made to further geothermal new-builds?

Geothermal generates power year-round and can replace coal- or gas-fired power stations as a baseload power with low production costs. It’s also dispatchable and supports grid stability in combination with intermittent sources. It’s also easily integrated into most locations with a small footprint and CO

 lifecycle compared to other renewables such as solar and wind. Plus, geothermal provides not only electrical power but inexpensive thermal power for a district heating network—not to mention that geothermal projects create temporary and permanent jobs that are important in developing a local supply chain.

It does have limitations, too. Regulatory barriers, such as long licensing and permitting procedures similar to mining and oil and gas, can limit new builds. Financial barriers come into play with the initial exploration and drilling activities. Geothermal also suffers from misconceptions. It is much less known compared to conventional renewables such as photovoltaics or wind. Geothermal is even incorrectly compared to shale gas technology in the case of enhanced systems. Issues can also arise from induced seismicity or underground water pollution, for example.

There is, however, an overall positive acceptance of geothermal among the various energy sources to decarbonize the power generation sector. This is reflected in supporting schemes and international programs to facilitate the implementation of new projects at a large scale. I also believe that the oil and gas industry is more interested in investing in geothermal compared to a few years ago.

Q: What's next for Turboden with geothermal?

Integrating ORC technology with other innovative geothermal technologies, such as enhanced geothermal systems, closed-loop geothermal systems, and lithium extraction from geothermal brine, can improve efficiency, sustainability, and economic viability.

Enhanced geothermal systems generate electricity from hot dry rock locations, enhancing the heat exchange by circulating clean water through artificially engineered fractures. This efficiently converts moderate temperature into electricity, expanding the geographic applicability of ORC projects to previously inaccessible heat sources, especially for large-scale projects.

Closed-loop geothermal systems provide environmentally friendly alternatives by creating a thermosyphon effect by drilling multiple lateral wells underground. Integrating ORC with closed-loop systems minimizes the environmental impact and reduces water consumption.

Lithium extraction from geothermal brine, crucial for electric batteries, is a sustainable source. ORC technology works as a cooler for the lithium extraction process in the shared infrastructure, contributing to a more economically viable and environmentally friendly process. Sale of electricity is added on top of the additional revenue stream coming from lithium extraction, promoting a cleaner and more profitable energy supply chain.

In summary, amalgamating ORC technology with enhanced geothermal systems, closed-loop systems, and lithium extraction from geothermal brine creates a holistic approach to geothermal energy production. This synergy enhances diverse resource utilization, promotes environmental sustainability, and contributes to the production of rare materials required for emerging technologies. This integrated approach underscores geothermal energy’s potential in a sustainable and diversified global energy portfolio.

An inside look at turbomachinery in a geothermal plant, how these plants are designed, recent advancements, and how geothermal can help decarbonize the energy landscape.

Q&A: Geothermal Power Generation Continues to Advance and Offers a Clean-Energy Future

Gas turbines are known for their role in land-based power generation applications, but they are also responsible for powering commercial and military naval and aircraft fleets around the world. The development of these turbines demonstrates the acceleration of technological innovation and adaptation in the power industry.

“Since the turn of the 20th century, steam turbine systems dominated the naval market, providing mechanical power for all types of warship propulsion trains,” said Steve Maynard, former Captain in the U.S. Navy and Director of Military Applications at GE Aerospace. “In the 1970s, however, gas turbine systems began proliferating across the world’s navies. The heart of these turbomachinery systems was the marine gas turbine engine—derived from parent aircraft engines originally designed to produce thrust. From these proven aviation engines, marine aeroderivative turbines were adapted to instead produce torque to power ship propellers, waterjets, and electrical generators.”

Turbomachinery has thrived in the naval domain since the 1970s “because it demonstrates superior power density, reliability, and maintainability. These are critical attributes for volume-sensitive warships and, most importantly, they significantly contribute to combat readiness,” Maynard said.

Marine turbines designed and manufactured by some of the top turbine producers are used among large-surface combatant vessels in navies across the globe. Maynard clarified their possible roles: to power the mechanical propulsion drive train, provide electric power for propulsion drives and motors, or provide electrical power for ship service loads such as high-energy weapons systems, advanced sensor suites, and hotel services.

Within larger combat vessels, all-electric propulsion plants equipped with gas turbines and large-scale turbine generators provide the flexibility to move power back and forth between propulsion and combat systems. The propulsion plant configuration varies on smaller ships, such as corvettes and frigates, as these vessels are often equipped with hybrid electric plants that feature a combination of gas turbines and diesels to provide propulsion and ship service power.

“In these smaller combatants, design authorities are increasingly selecting turbomachinery systems for power-dense drive train solutions that provide high-speed capability; this is an important tactical attribute in modern warfare and perfectly suits their smaller hull forms,” Maynard said.

In addition to propulsion applications in the marine space, gas turbines are often used for offshore applications such as floating production, storage, and offloading (FPSO) units and fixed-leg assets in oil and gas production. According to Siemens Energy’s Global Head of Oil & Gas Patrice Laporte, they are installed on platforms “topside for power and process operations such as power generation, the compression and transmission of export sales gas, and carbon capture and reinjection.” These gas turbines are relied upon for their continuous operation and effective resource utilization.

“Turbomachinery plays a critical role in offshore applications, serving as key components across various facilities and subsea installations,” said Holger Wörner, Head of Sales Upstream, MAN Energy Solutions. “The primary advantages of turbomachinery in these contexts include enhanced reliability and uptime, essential for continuous operation and effective resource utilization. Additionally, it contributes to reducing the carbon footprint during operations by enabling more efficient use of energy.”

He said a major trend in offshore turbomachinery is its use for subsea compression, increasing the total recovery of a gas field, maximizing efficiency, and releasing less CO

 into the atmosphere compared to topside platform exploration.

“There is a noticeable shift toward unmanned or low-manned systems, enhancing safety, and reducing operational costs by requiring minimal human intervention,” Wörner said. “Electrification projects are also gaining momentum, with an increasing number of gas turbine-driven machines being replaced by electric motors. This shift aims to improve efficiency and reduce emissions.”

Although marine gas turbine components are subject to unique operational requirements compared to their land-based alternatives, Jacqui Joas, Global Business Development Manager at Atlas Copco Gas and Process, said compressors serve the same function at sea as on land: reducing operating costs and emissions.

Marine compressors can start the engine, reduce fuel consumption, control LNG tank pressure, and release boil-off gas (BOG) to shore during bunkering operations. These BOG compressors also reduce emissions using LNG instead of marine and heavy-fuel oil. Marine-based models must consider the conditions at sea and within a ship environment, such as the vessel’s roll-and-pitch, a salty atmosphere, or requirements from ship classification groups.

Joas said that the technology is mature, so he doesn’t expect the basics of the compressor to change: “We’ll still see screw compressors (oil-free or oil-flooded), hydrovane compressors, piston compressors, and more. Technological progress will be concentrated on better efficiency, downsizing, smaller footprint, maintenance friendliness, lower OPEX, etc.”

Turbines for marine applications were derived from aviation models that came prior, as Maynard pointed out, and rather than using torque for propulsion, aircraft jet engines produce thrust from the exhaust gases of the turbine.

Gas turbines have a compression stage followed by combustion at near-constant pressure, which differs from piston engines. In a gas-turbine setup, hot gas escapes through a pressure drop at a higher velocity than cold air, providing enough momentum to rotate the shaft, Stanford Clemens, Powerplant & Thermo Mechanical Design at Rolls-Royce, explained. Spare hot gas pressure is then used to accelerate a jet.

Compared to a piston engine—another common model for aviation purposes—gas turbines have a smaller combustion air-fuel ratio to maintain an optimal entry temperature to sustain the turbine. Gas-powered models retain several advantages over the alternative. “Gas turbines are typically much smaller and lighter than piston engines for the same power output because the flow path of air through a gas turbine is much more open and the process is continuous,” Clemens said. “Gas turbines are typically 20 times more powerful than a piston engine of the same size.”

The environmental conditions at sea subject naval turbomachinery to complicating factors. According to Maynard, this list is long: underwater shock excursion, ship vibration, extreme climactic heat, salt spray, icing, and storm-driven dust. These factors necessitate unique maintenance and repair methods, such as robust mounting and dampening to control vibration and anti-corrosion metals and coatings to resist the salty environment.

“Maintenance activities are performed on condition-based criteria instead of at fixed operational hours,” Maynard said. “Marine turbomachinery is designed on the fundamental requirement to be supported in place within the ship through the crew and by intermediate maintenance personnel ashore. Marine gas turbines are designed to permit rapid change out of externally mounted controls, accessories, associated piping, and wiring onboard the ship. As such, most maintenance activities, even the most complicated ones, can be performed in place or dockside to the same standard as in a depot.”

Given the isolated nature of operations at sea, maintenance crews may not always be available for in-person diagnosis of sudden malfunctions. Companies that offer remote monitoring, such as MAN Energy Solutions, enable equipment viewing from afar. “Upon the customer’s request, our company’s after-sales division, MAN PrimeServ, can directly access the Programmable Logic Controller and Human Machine Interface for data analysis and, if necessary, parameter tuning,” Wörner said. “This remote support approach ensures timely and efficient troubleshooting, reducing potential downtime and associated costs.”

Similar to gas turbines in a marine environment, aerospace turbines are impacted by external conditions that mandate a different approach to maintenance and repair. Environmental factors present some issues, but the primary differentiator is how aero-gas turbines operate.

“One of the primary limiters of gas turbine durability is hot-section life,” Clemens said. “Aerospace engines have more hot-section cycles per flight, which impacts the durability of the hot section as a result of the thermal-mechanical cyclic strains imposed on the components. Land-based turbines typically run for tens to hundreds of hours at power, which limits thermal-mechanical cycles and allows for much longer lives before a hot-section overhaul is needed.”

Once maintenance is required, he said aero turbines are transported to OEM-approved engine overhaul facilities and, in military cases, work is conducted by customers of the U.S. Department of Defense. Turbines are cleaned and inspected, disassembled, repaired, and then reassembled for testing prior to re-installation on an aircraft.

Many of the turbine systems installed on commercial and military vessels and aircrafts have surpassed their technological adolescence, with engineers fine-tuning the science and execution of combustion cycles to optimize performance. Further innovation, and perhaps the future of these turbines in this context, will involve integrating outside technologies and processes in the monitoring and maintenance spaces.

According to Maynard, the monitoring and control of naval turbomachinery will become primarily automated as fleets cut back crew size: “Digital twin technology, commonly referred to as machine learning, is an emerging concept in which a digital model can be used to analyze performance problems and create diagnostic enhancements. These efforts usually focus on vital areas of functionality using the existing turbomachinery sensors to improve reliability and availability. These automation and remote maintenance technologies will become increasingly vital to developing unmanned surface vessels as well.”

In defense applications, gas turbines are “approaching a point where performance is reaching the limits imposed by hot section materials technology,” Clemens said. Plus, the cost of developing and certifying new centerline gas turbine technology is more than $1 billion. Considering these limitations, the industry is focusing on commercial off-the-shelf (COTS) and modified off-the-shelf (MOTS) turbines and more on the complex system design and integrating gas turbines into new platform opportunities or upgrading existing air-vehicle platforms.

“A challenge with new defense applications is the need for more electrical power for surveillance and countermeasures. This additional electrical power comes at the expense of more heat generation, and thus the need for more novel thermal management solutions,” Clemens said. “So, the approach is to take COTS and MOTS gas turbines with a focus on supplying more electrical and thermal management capabilities. In addition, there is increased emphasis on low signature observables. This has placed increased emphasis on embedded inlets and exhaust infrared suppression systems to satisfy the modern warfighters.”

He said that most of the growing interest in new gas turbine centerline opportunities is focused on attritable engines—lower cyclic life—for lower-cost autonomous air vehicles because it reduces the cost of the engine by using less expensive materials and requiring fewer qualifications, reducing certification costs.

Although engineers have an in-depth understanding of gas turbine combustion cycles, the science, in most cases, can always be improved upon. Maynard concluded that incremental thermal efficiency improvements in the Brayton thermodynamic cycle will enhance the operation of these turbines, reducing annual fuel consumption and providing an advantage by increasing the cruising range of naval vessels and aircraft.

Gas turbine systems are the heart and soul of many defense—including naval and aero—and commercial offshore operations, providing reliable, efficient power.

From Sea to Sky: Turbomachinery in Military and Commercial Applications

After a rebound year in 2022, overall gas turbine MW capacity orders were down 12.6% in 2023. This slight downturn was anticipated due to the cyclic nature of the market for large turbines. OEMs spend years taking major orders from start to commissioning; hence, it is rarely the case that a good year for sales of large machines is followed by an even stronger year. Yet two consecutive years with capacity orders above 30 GW hasn’t happened in a long time. This indicates that the downward trajectory of gas turbine sales during 2010-2019 has been arrested, if not reverted.

Meanwhile, total units sold rose by 3%, according to Tony Brough, President of Dora Partners and Company. Unit orders have been slowly rising since 2019.

One of the reasons for this uptick is innovation from Solar Turbines. The Solar Titan 250 sold 32 units to the oil and gas sector over the last few years—a 48% share of oil and gas sales in the 20 - 30 MW range in the past six years. The relatively new Solar Titan 350 has also started well since its release less than two years ago. It is likely to compete well against GE Vernova’s LM2500+, which is the best-selling aeroderivative model.

With so much attention on renewables, emissions reduction, hydrogen, and net zero, some wonder what the future holds for gas turbines. Brough strongly believes the market will remain healthy for many years to come.

“Gas turbines are not going away; the renewable offset/peaking market continues to have long-term potential,” he said. “Ten years from now, the gas turbine market will still be going strong.”

He backed this up with numbers. He expects $137 billion to be spent on new turbines and turbine packages—not including auxiliary systems, heat recovery steam generators, and other related equipment—over the next 10 years. In addition, aftermarket spending on gas turbines will amount to $261 billion over the next decade.

In the aeroderivative space, GE/Baker Hughes continues to dominate market share with the LM2500+ being the star performer. A total of 83 units were ordered in 2023 compared to 81 in 2022 with a total of 230 over the past six years.

“The LM2500+ has been one of the most popular models in the world for the last 25 years,” said Brough. “Almost 50% of all aeroderivative sales over the past six years have been LM2500+s, and 74% of sales in the 30 - 40 MW segment.”

Other GE aeroderivatives fared less. The LM6000 managed about five orders in 2023, though Brough noted that 2024 looks like a better year for that machine. The LM9000 holds good potential in oil and gas and electric power but is still in the early stages of market acceptance. Overall, aeroderivative unit orders were down 5% in 2023 and MW orders were down 16%, following a huge year for LM6000 sales in 2022.

Looking ahead, Brough predicts that $22.3 billion will be spent on aeroderivatives between now and 2033. GE/Baker Hughes will gain almost $20 billion of that share. The aeroderivative aftermarket will generate $31.5 billion over the next decade; $23 billion of that will be spent on GE/Baker Hughes machines.

The strength of the LM2500+ is attracting competition from small industrial gas turbines like Solar Titan machines and the Siemens Energy SGT-800 as well as reciprocating engines from Wartsila and others. The SGT-800 is performing especially well in the 40 - 60 MW power generation segment with 178 units sold in the last six years—54% of all sales in that segment. In oil and gas, it accounted for 13% of sales in that period (21 units).

While posing a strong technical challenge, Siemens Energy aeroderivatives have suffered competitively due to the company moving the packaging of these units to Sweden.

“Frame 5 heavy-duty gas turbines are also putting pressure on the LM2500+ space,” said Brough.

He compared the LM2500 with the Solar Titan 350. The Titan 350’s power output is 34 - 38 MW, and its efficiency ranges from 39.4% to 40.1%. The output of the LM2500+ is 34 - 37 MW with its efficiency ranging between 38.9% and 39.1%. The Titan 350 wins out when it comes to dry-low NOx by offering 9, 15, and 25 ppm options. The LM2500+ offers 15 and 25 ppm options. However, the footprint and weight of the Solar Titan 350 are much higher: 936 square feet and 406,000 lbs. compared to 585 square feet and 297,624 lbs. for the LM2500+. Further, the GE Vernova model provides far more repair options courtesy of GE Vernova, Baker Hughes, and its three authorized service providers.

Mark Axford, President of Axford Turbine Consultants, expects the gas turbine market to improve in 2024. He predicts a 7 - 10% uptick in orders this year. That said, he warned of the many disruptive factors that can quickly change things. He listed the Israel-Hamas war, the Russia-Ukraine war, and severe shipping constraints in the Red Sea and the Suez Canal that add two weeks and 40% to the price, as goods now have to go around the Cape of Good Hope in Southern Africa.

He gave the example of an earlier market disruption that completely changed the worldwide energy picture.

“The Nord Stream pipeline blowing up in 2022 was the single-most important occurrence in energy markets in decades,” said Axford. “Since then, the United States has gone from third in LNG production to no. 1, with 24% share.”

DATA CENTERS CREATE NEED FOR GAS-POWERED PLANTS

Despite the steady rise in restrictions and anti-fossil-fuel policies—such as the recent pause on new LNG permits in the United States—there is another factor acting as a catalyst for new natural gas facilities development: AI-based data centers. Loudon County, VA near Washington DC, for example, has the highest concentration of data centers in North America. Gas turbines will likely meet the need for far more power in places like this, as there is either no room for large wind and solar farms or their output would be insufficient.

“It is very likely that there will be a lot more for gas turbines due to AI,” said Axford.

Another knock-on effect of rising power demands is delays placed on planned coal plant closures. States such as Kansas, Nebraska, and Oklahoma have all postponed coal closures recently.

Axford noted that Mitsubishi Power and Siemens Energy seem so focused on the sales of industrial gas turbines that they are paying little attention to their own aeroderivative machines. Hence, the dominance of GE in the aeroderivative market. But GE doesn’t win all awards for genset packages. Competition has arisen from companies like ProEnergy and its WattBridge affiliate, Relevant Power Solutions, and Dynamis.

ProEnergy, for example, has built and installed 41 LM6000 genset packages since 2009. WattBridge owns and operates 50 LM6000 peakers in Texas.

“ProEnergy offers a low-cost turnkey alternative 48 MW genset to the OEM and traditional engineering, procurement, and construction firms,” said Axford. “The company also provides Level IV-like shop overhaul services, completing 13 of them on LM2500s and LM6000s in 2023.”

Dynamis, too, has found some success in doing the same thing over and over and doing it well. It has developed a trailer-mounted LM2500+ that can be bought or leased. Oil and gas companies like these units because they can move them from one month to the next to the latest well site. Axford said Dynamis will have 28 of these units running by the end of 2024.

In addition, Relevant Power has developed a trailer-mounted LM2500+. Five have been sold to date and one is in production. The company does full-load string testing and offers an economical installation.

Despite the obvious problems facing the natural gas industry, Axford believes it is holding its own. It remains the leading source of U.S. electricity production, scoring 37 - 39% for six years straight. At the same time, more wind and solar resources are coming onto the grid. Combined with hydroelectric generation, renewables now account for 26% of U.S. electricity generation.

“The optimum amount of renewables for a large grid is probably 30% and perhaps might be stretched closer to 40%,” said Axford. “But gas turbines are an essential part of creating a reliable, affordable, and sustainable grid.”

Drew Robb is a freelance writer specializing in engineering and technology. Email Drew at drew@robbeditorial.com.

Unit orders and aeroderivative sales rose but total MW orders fell slightly.

Gas Turbine Sales Report: 2023 Holds Its Own

’s July/August 2024 tackles turbines from sea and sky to offshore, land, and hydropower-based applications, including industrial and aeroderivative gas turbines, steam, and hydro turbines. 

Along with our bi-monthly industry news, which includes a tribute to a gas turbine legend Ivan Rice, this issue kicks off with 

, a look at gas turbines and compressors in the military, including aero and naval, and commercial and offshore applications as well as upkeep and repair considerations.

Our annual gas turbine sales report segments industrial and aeroderivative turbine sales and looks at the impact of disruptive factors, such as international conflicts, and AI data centers.

The summer issue also dives into hydro and steam turbines. In 

A History of Turbomachinery and Hydropower

, readers get a fact-filled introduction to hydropower generation in the Ontario area and insights GE Vernova’s Head of Hydro Power Engineering on how hydropower plants use complex hydro turbines and other rotating machines to electrify regions worldwide. Mitsubishi Heavy Industries lays out several case studies on how implementing phased array ultrasonic testing in steam turbine inspection and maintenance is an evolution from traditional maintenance that can ensure efficiency and reliability.

In May, Joseph Bonafin, Sales and Business Development Manager at Turboden, came on the 

The July/August 2024 issue offers comprehensive coverage on industrial and aeroderivative gas turbines, steam, and hydro turbines. 

July/August 2024