This article was originally published in Engineering Edge Vol. 4 Iss. 2 ©2015 Mentor Graphics Corporation all rights reserved

Experimental Validation of Steam Turbine Control Oil Actuation Systems Transient Behavior[1]

his work presented at the 30th International CAE Conference in Verona, Italy demonstrates dramatically the value of

simulating the multi-physics of the fluid-mechanical interactions of a steam turbine trip valve. The steam trip valves are used as a safety device to prevent a steam turbine from overspinning. Also called overspeed valves, they shut down the flow of steam to the turbine on overspeed if it reaches 10% above the maximum operational speed. These valves use a high spring force, opposed by control oil pressure during normal operation, to close the hydraulically controlled valve rapidly on loss of control oil pressure. This creates a close coupling between the steam flow path and the hydraulic control fluid path via the mechanical interaction of the valve. The authors were able to successfully model this interaction by taking advantage of the Flowmaster mechanical component library. The model had to properly demonstrate the three stages of operation which include:

• Opening stage: loading of the spring;

• Opening stage: valve opening; and

• Closing stage. The model was validated against test data and the team were able to successfully simulate the pressure fluctuations behind the damper plate of the valve and show the decoupling between the damper plate and the piston glass at the end of the opening phase of the valve trip.

Once the valve control was validated it was able to convert to a composite component and then added to a master model that simulated an entire test bench oil systemThis complete piping model was based on

the real components and was validated through a series of tests which showed good correlation. By running through a number of scenarios by the team were able to optimize the control oil system by adjusting several parameters including pipe diameters, orifice sizes, pipe lengths, and external temperature.

From their physical tests and numerous simulations runs the authors were able to successfully model both the hydrodynamic

and mechanical interactions simultaneously in Flowmaster. This provided them with fast consistent simulations in different configurations and run virtual hazardous operational scenarios. It also gives them the opportunity to provide fast solutions for customer problems and eliminates the need for tuning of the system during installation.

Riccardo De Paolis graduated in Mechanical Engineering from University “RomaTre” in fall 2013, carrying out turbomachinery and electric machines path. For his first work experience, he joined a

TAndrea Tradii; Stefano Rossin; and Riccardo De Paolis, GE Oil and Gas

2015 Don Miller Award for Excellence in System Level Thermo-Fluid Design

Figure 1. Steam path components

Process

This article was originally published in Engineering Edge Vol. 4 Iss. 2 ©2015 Mentor Graphics Corporation all rights reserved

six month internship with GE Oil & Gas, increasing software modeling of various Gas Turbines Auxiliary Systems. At the end of the internship, he succeeded in GE Oil & Gas Edison Engineering Development Program selection, being part of this leadership program from wave 2014. The first rotational assignment he carried out was still related to Gas Turbine Auxiliary Systems, giving contribution in one-dimensional fluid dynamics and Finite Elements Modeling, as well as completing requisition activities.

Stefano Rossin currently holds the position of Chief Engineer for Turbomachinery Auxiliary System and Industrial Plant in GE Oil&Gas based in Florence. He graduated from the University of Pisa with a M.S. Degree in Aeronautical Engineering and he began his career in 1989 working in several fields from Chemical Research to Aerospace.

He joined GE O&G in 2005 and since then he has always managed the design of rotating machineries auxiliary systems, improving connections with universities in several engineering areas and successfully introducing fundamental guidelines for blast assessment of turbo-compressor train, in off-shore and Floating Liquefied Natural Gas applications.

He is the author of three patents and 15 international papers, some of them developed in cooperation with important Oil&Gas customers such as Shell and Exxon Mobil. In June 2013 Stefano received the Edison Pioneer Award, such honor is presented to select individuals from across GE every year and it recognizes mid-career technologists who demonstrate technical excellence and customer impact.

Andrea Tradii is Senior Engineer for Turbomachinery Auxiliary System and Industrial Plant in GE Oil&Gas based in Florence. He graduated at the University of Rome and joined GE O&G in 1991. Since then he managed the design of Mechanical Auxiliary Systems for Turbo-compressor trains and Motor-compressor trains. He began his career as a Mechanical Design Engineer and, after four years of experience as Resident Engineer in Mexico, he became Mechanical Team Leader for Turbomachinery Auxiliary System. In 2012 he was appointed Product Innovation and Standard Update Leader.

Reference: [1] Presented as part of the International CAE Conference proceedings, Oct. 2014

Figure 2. Mechanical components of hydraulic actuator

Figure 3. Hydraulic model characterization

Figure 4. Control oil actuation systems validation

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