Turbine designers are finding new ways to lower costs, increase efficiency and capacity, minimize maintenance requirements, and reduce the size and weight of the equipment. Recent developments are delivering business benefits, particularly in the renewables space.
|Sheila Kennedy is a professional freelance writer specializing in industrial and technical topics. She established Additive Communications in 2003 to serve software, technology, and service providers in industries such as manufacturing and utilities, and became a contributing editor and Technology Toolbox columnist for Plant Services in 2004. Prior to Additive Communications, she had 11 years of experience implementing industrial information systems. Kennedy earned her B.S. at Purdue University and her MBA at the University of Phoenix. She can be reached at email@example.com.|
Recent developments have occurred in the area of advanced non-water-based waste heat recovery cycles for gas turbine-driven power plants. “Several companies are now offering organic Rankine cycles using pentene as a working fluid, and other manufacturers are working on developing different types of supercritical CO2 cycles,” says Klaus Brun, machinery program director at Southwest Research Institute. “Both of these technologies offer the potential to significantly simplify and reduce the cost of waste heat recovery while increasing the overall plant efficiency. They can also be utilized for industrial waste heat recovery applications at temperatures well below those commercially feasible for steam Rankine cycles,” explains Brun.
Expansion turbine design
In turboexpanders, the use of active magnetic bearings rather than oil-lubricated bearings allows for a smaller support skid footprint, lower overall weight of equipment, and less maintenance due to the non-contact, lubrication-free design. L.A. Turbine is able to incorporate magnetic bearing technology into any turboexpander design. The size of a magnetic bearing turboexpander machine is based on the gas composition, molecular weight, and site conditions. “Today, more companies are considering and purchasing magnetic bearing units rather than oil bearing units due to the advantages they bring in size, performance, and maintenance,” says Houman Shokraneh, director of engineering at L.A. Turbine. “This technology is especially appealing for offshore environments and those with space limitations.”
Renewable energy enablers
Wind and solar power plant output is inconsistent, making it important for gas and coal plants to make up for lost production by quickly responding to signals from the power grid. Equipping gas turbines with the TurboPhase compressed air smarter peaking power system from PowerPhase essentially turbocharges them, increasing output capacity and plant ramp rates regardless of ambient temperature. TurboPhase is differentiated by avoiding the use of water or steam, while providing additional compressed air and emitting less greenhouse gas than coal-fired and natural gas-driven peaker plants. It can be retrofitted to almost any gas turbine in simple cycle, combined cycle, or cogen applications.
"We are able to demonstrate 20% incremental capacity that is available on both frame and aero-derivative gas turbines,” says Bob Kraft, president of PowerPhase. “TurboPhase was designed to respond in 60 seconds to enable the grid to operate more efficiently given the growing penetration of renewables."
ABB’s new ACS880 low voltage wind turbine converter lowers the levelized cost of energy (LCoE) by ensuring high turbine uptime, greater operational efficiency, advanced grid code compliance, simplified maintenance, and lower lifecycle costs. The liquid-cooled full power converter is suited to onshore and offshore utility-scale wind turbines. Self-healing foil capacitors prevent the need for replacements over the life of the converter. Optional parallel-connected subconverters can be activated or deactivated depending on wind conditions in order to increase overall efficiency of the converter, particularly at partial load.
To optimize wind turbine costs and efficiency, Siemens now offers a system controller that can be individually adapted to on-site conditions. The Soft-SPS Simatic WinAC RTX controller from Siemens communicates in real time with the MATLAB/Simulink software from MathWorks, allowing wind turbine manufacturers to improve their wind turbine designs by simulating and addressing actual wind and operating conditions for the installation location. As a result, the turbines operate with maximum efficiency and generate the highest possible energy yield for the conditions. The simulation results and control settings can be transferred to the Simatic system controller.
Marine Current Turbines, a Siemens business, recently worked with Frazer-Nash Consultancy to improve its SeaGen tidal energy turbine technology. The next generation turbine design is expected to minimize fatigue loads. Frazer-Nash built a series of models to understand the hydrodynamic interaction between the rotor blade and the crossbeam, which were validated against measurements from the first-generation turbine.
“We were able to use our modeling expertise to help Marine Current Turbines refine the crossbeam design to minimize the fatigue loads on the machine. This information will also inform the blade design, ultimately helping to minimize risks and reduce costs for the client,” says Paul Mather, business manager for renewables at Frazer-Nash Consultancy.