Achieving Unprecedented Efficiency


Technological advances in turbines are underscoring performance improvements, leading to increasingly reliable, efficient, and safe equipment.

“The technology advances we see are mostly on safety and monitoring such as electronic trip systems and electronic speed governors,” notes Christiann Bash, spokesperson for Elliott Group.

Recent design upgrades have added to reliability and safety and meet safety integrity level (SIL) requirements, Bash says, adding that Elliott has created a SIL-rated trip system that is new.

Among the choices on the market are those offered by Siemens, which provides heavy-duty gas turbines, industrial gas turbines, and aeroderivative gas turbines up to 567 MW from a package installation to a full turnkey power plant for end-uses including power production, industrial power generation, and oil and gas applications.

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The company also offers steam turbines from 10 kW to 1,900 MW. The steam turbines work as generator drives or mechanical drives for compressors or pumps and play a significant role in many combined cycle and cogeneration plants, as well as in industrial applications.

Steam turbines are often applied in the renewable energy sector. Applications for steam turbines include power generation plants, district heating, biomass, waste-to-energy, seawater desalination, and solar heat.

Siemens gas and steam turbines played a key role in the creation of the Holland Energy Park in Holland, MI. The park combines the benefits of CHP technology, a snowmelt system, and a visitor center in its new power plant.

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Credit: Siemens
The Holland Energy Park

In 2011, Holland officials developed a Community Energy Plan as a guideline for securing a reliable and independent power supply for future needs. When planning for a new power station, the Holland Board of Public Works (HBPW)—a community-owned power supplier—considered environmental, health, and social implications.

Dave Koster, HBPW general manager, notes that the board initially discussed modernizing the existing coal-powered plant, but there was “no appetite” for more coal power on a state level. Holland officials wanted to maintain its snowmelt system and the intangibles attached to having coal, such as ships coming into Holland.

A HBPW engineer suggested the city approach the issue using a Sustainable Return of Investment (SROI) analysis.

In the process, HBPW officials considered coal, natural gas, renewables, and buying power from the grid. They also considered the mostly intangible impacts on the community, examining each solution’s economic, environmental, financial, and social impact.

With input from community stakeholders, the ultimate SROI decision was the creation of the Holland Energy Park. The priority was to supply the community with reliable, clean, and affordable energy, notes Koster, adding that HBPW also can offer an extended snowmelt system and eventually district heating. The project has led to more reliable and cleaner power with 50% less CO2 emissions.

Holland officials chose Siemens as its industry partner. The Siemens combined heat and power portfolio includes two Siemens SGT-800 gas turbines, which provide a capacity of 50.5 MW to the Holland Energy Park.

It also includes an SST-400, a single-casing steam turbine. A symmetrical casing with horizontal joint flange enables the SST-400 to accept short startup times and rapid load changes.

An SPPA-T3000 digital control system is a distributed power plant control system designed to ensure effective and efficient operation.

GSU transformers take the generator voltage level up to the transmission voltage level—up to 800 kV system voltage, with auxiliary transformers providing reliable auxiliary and control services from the generated 13.8 kV, taking it down to 4.16 kV to feed MV distribution switchgear.

The Siemens Type WL low-voltage metal-enclosed switchgear is designed, tested, and constructed to provide optimal power distribution, power monitoring, and control, while providing extreme modularity and uniform height.

Also part of the system is Siemens tiastar industrial motor control centers (MCCs).

Siemens medium-voltage arc-resistant GM-SG-AR switchgear and SIMOVAC-AR motor controllers provide an added degree of protection to those close to the equipment from an internal arcing fault and can share a factory-installed pressure relief channel reducing installation time.

The Holland Energy Park exemplifies the wave of the future, notes Bill Castor, director of business development, Siemens Energy.

Solutions and integrated concepts of which turbines play one part is where technology is now heading, notes Castor. A product on its own may be very efficient, but its efficiencies are amplified when it is part of an integrated approach, he adds.

In the past, a building owner or operator may have installed a CHP system as an alternative energy supply for an industrial or commercial space and simply run it as much as possible, notes Castor.

“What we’re seeing now with the more complex environment from the grid is the need for more information to consider how you might optimize your energy alternatives,” he adds.

“It sometimes makes sense to turn these things down and use the energy from the outside market at times as opposed to just running a piece of equipment full out like in the old days.”

Essentially, building owners and operators can benefit by thinking holistically, looking at how all aspects of generating or purchasing power work together and how they can optimize their operations based on several factors, many of which are external to a facility, Castor says.

One of the primary drivers for Holland’s project was that coal was going out of environmental favor, notes Castor. The decentralized energy powered by natural gas or renewables “is a much cleaner way to approach generation,”’ he adds.

With respect to advances in gas turbines, “the biggest advances we’re seeing are related to efficiency, operational flexibility, and the integration of digital technology. All of these improvements are focused on providing better situational awareness and improving an end-user’s ability to effectively interact with the outside market,” points out Castor.

Advances in equipment technology are made better by digitalization efforts in such areas as condition-based servicing as opposed to the traditional hours-based approach.

Reliable onsite generation is critical at times when a facility is impacted by severe weather events.

“Those companies that have taken control of their energy generation are more efficient and self-reliant and they clearly have had a much higher level of reliability when it comes to those kinds of events,” points out Castor.

Energy storage is starting to play a bigger role in many energy projects, with the concept of microgrids picking up momentum, notes Jim Crouse, executive vice president for sales and marketing for Capstone Turbine Corporation.

“We’re seeing more combinations of CHP and indoor standby generation combined with renewables and storage to provide a more in-depth overall solution along with the improvement in resiliency or business continuity that comes from having those onsite resources,” he says.

Case in point: in early 2015, managers of Mexican plastics and molds manufacturer Bopisa sought a clean and efficient energy solution to replace its existing generators, supply reliable electrical power, and condition the onsite water supply for its manufacturing operation in Guadalajara, Mexico.

The search was in recognition of the fact that Mexico is one of the largest consumers of plastic, using nearly 143 pounds per capita, the highest per capita consumption rate of plastics in Latin America. Its plastics industry is growing in concert with its automotive, electronics, and medical sectors and their respective demands.

The goal of the search was to increase the plant’s energy efficiency while effectively reducing the company’s rising operational costs. Bopisa chose Capstone Turbine distributor DTC Ecoenergía for a full site assessment from among all options examined.

DTC Econergía’s team of energy experts performed an in-depth evaluation of the plant and reported that Bopisa was consuming energy from the local Comisión Federal de Electricidad network with a billable demand contracted from 202 to 950 kW.

Operating with a plant load average of 761 kW per month and a maximum demand of 1,153 kW, it was determined that a 600-kW Capstone C600 Microturbine for Grid Connect, fueled by high-pressure natural gas, would appropriately meet the site requirement.

Bopisa management also opted to utilize the thermal energy from the microturbine’s clean exhaust by installing an absorption chiller (CCHP) to deliver hot and chilled water to the existing water lines.

Today, the Capstone C600 microturbine generates more than 59% of the manufacturing plant’s electricity with a heat consumption of 80 tons of refrigeration (TR).

The Capstone microturbine generates 484 kWh, helping the manufacturing facility avoid a 27% demand consignee expense. Since adopting Capstone Turbine’s microturbine technology, Bopisa has reduced its energy costs by 58%, saving $350,000 annually, and has provided a three- to four-year return on investment.

Controls and the ability to improve performance and reliability with advanced controls for both the microturbine and the balance of plant equipment are playing a major role, Crouse says.

Capstone Turbine’s PowerSync MultiMaster controller enables end-users to intelligently dispatch multiple microturbines as a single power source. The controller automatically controls up to 30 C200 power modules and is preconfigured for up to six C1000S Microturbines using PowerSync Master or PowerSync Enhanced controllers.

It is designed to integrate with PowerSync Master, Enhanced, and Lite C1000S controllers. The controller communicates with integral C200/C1000S Heat Recovery Module. It also features self-healing Ethernet ring topology for MultiPac control.

The controller is pre-wired for digital and analog I/O connections. It is pre-engineered for seamless transfer control. Its Programmable Logic Controller based system provides dispatch algorithms and digital communications.

An industrial PC provides touchscreen human-machine interface and data file management. It features an integral UPS system with 30-minute battery storage. The controller can be set up for two remote access sessions using optional mGuard secure VPN accessory.

The controller is part of secure digital communications for integration with Building Management Systems, for remote/local monitoring and service.

Repair specialists such as Sulzer continue to develop new coatings and new application methods that can keep pace with the advances in the turbomachinery sector in such a way that plant operators will have the confidence to invest in repairs that have the ability to provide many years of continued service, notes R. Douglas Sewell, vice president for engineering at Sulzer.

“For gas turbines, the internal components are subjected to extreme temperatures, and these can only be endured through the use of specialized coatings,” notes Sewell.

“At the same time, regular, detailed inspections must be carried out to ensure continued reliability, checking for damage and signs of corrosion,” adds Sewell. “The latter issue is of particular interest in units that operate infrequently and are likely to be inspected on a calendar-based schedule rather than on accumulated operating hours.”

Another area that has seen considerable improvement is root cause analysis, says Sewell.

“The technology and equipment that is available today has given us much greater insight into failure modes and enabled us to develop better engineered solutions,” adds Sewell. “Greater computing power has improved computation fluid dynamics, allowing designs to be improved before they leave the drawing board.”

Along with new alloys and improved reverse engineering techniques using 3D laser scanners and rapid prototyping techniques, it is now possible to create greatly improved components using just the original, and sometimes damaged, parts for reference, notes Sewell.

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Credit: Elliott
Elliott Group turbines feature enhanced
safety and monitoring systems.

“Coupled with developing materials technology, maintenance providers such as Sulzer are in an excellent position to deliver more reliable equipment,” says Sewell.

Modern machine tools such as multi-axis CNC robot milling equipment and machining techniques such as electrical discharge machining have further refined the precision that can be achieved today, Sewell points out.

Additive manufacturing, which enables precision molds and cores to be created in a fraction of the time more traditional methods would take, also has had a significant effect on project delivery times, Sewell adds.

Design upgrades are usually aimed at increasing reliability, performance, and service life, says Sewell, adding that achieving these aims often reduces maintenance and operating costs as well “so implementing some of the latest technology in design and materials can have a significant impact.”

In developing and installing design upgrades for both gas and steam turbines, the aim is to improve reliability and service life, resulting in reduced maintenance costs, says Sewell.

For gas turbine operators, increasingly stringent emissions regulations continue to have an impact on the daily operations and maintenance strategies, says Sewell.

To that end, Sulzer has developed a solution that solves a primary fuel nozzle leak issue for two turbine models on the market that can be implemented during routine scheduled maintenance, which “effectively reduces previously tolerable minor leaks at the primary fuel nozzle tips to zero,” says Sewell. “This enables the turbine to run at optimum parameters for power, efficiency, and component lifespan while assisting to meet stricter emissions regulations.”

Meeting more restrictive emissions limitations may require operators to adjust the fuel/air ratio, change the firing temperature, or alternatively, to make an attempt at reducing fuel nozzle leakage, Sewell adds.

“Excessive leakage at the primary fuel nozzles comes at greater cost to the operators, who may have to implement costly emissions scrubbing at the exhaust stack,” says Sewell.

The collaboration between engineers at Sulzer and some of its clients has resulted in the development of new seal designs that are “field-proven to deliver zero leakage, offering operators the ability to achieve emissions limits while maintaining targeted turbine outputs, without increased expense,” says Sewell.

The challenges of protecting components—especially those that are within the hot section of a gas turbine—are considerable, especially when the temperature of the combustion gas is higher than the melting point of the base materials, explains Sewell.

“The combination of internal cooling ducts and a thermal barrier coating work together to maintain the desired component temperature,” adds Sewell. “The latest turbine blades are designed with a large number of tiny cooling holes, often in excess of 500 in a single part, which must remain unaffected by the coating process.”

Sulzer’s specialist coatings are designed to resist corrosion and fouling and to improve performance in turbines. Its HICoat A24 Coating is a metallic-ceramic polymer that has been specifically formulated to provide extended service and prevent loss of efficiency.

Mechanical efficiency looks at reducing losses in the power train, including the clearance between the rotor blades and the stator casing, Sewell points out.

“This is crucial in determining the efficiency of the turbine and therefore a large part of its costs and productivity,” says Sewell, adding that zirconia-ceramic materials can be used to minimize this clearance in high-temperature applications.

“Clearance-control coatings or abradable coatings function by allowing a rotating part such as a blade to cut a path in a sealing abradable layer with minimum clearance,” says Sewell. “Many advanced gas turbines use a thick ceramic coating to impart both thermal-barrier and abradability properties.” De Bug Web

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