Tyco Flow Control Develops Custom- Designed Bled Steam Check Valves

Tyco Flow Control has developed an advanced Fasani bled steam check valve specifically for supercritical coal-fired power stations. The valve was customengineered for a major turbine manufacturer, in a contract for several power stations in different locations around the globe. The check valve portion of the contract is worth €2.5 million, with future projects in the pipeline.

The valve was designed to meet two key requirements; it must close up to ten times faster than current valves and close 100 times without deformation. Tyco’s Fasani engineers met these stipulations through modifications to the hinge design, without changing the body, actuation system or seat. The typical closing time of the new Fasani bled steam check valves is 0.1 seconds, compared with 0.6 – 1 second in previous check valve designs.

As technology advances, supercritical power plants are becoming more common, with higher levels of temperature, pressure and flow velocity calling for valves that can handle the challenge. Plants with an output of 800 MW or higher now occupy a much smaller space than would have been required a decade ago. These space limitations and improved efficiencies demand re-designs and a more complex layout, such as around the boiler. With all elements closer together in a smaller space, there is a greater risk of damage in the event of failure. The Fasani bled steam check valve is designed to be situated closer to the turbine, and to handle a harsher operating environment. Its proximity to the turbine demands an increased closing speed to protect the turbine blades from damage from reverse steam flow.

In designing the bespoke valve, Tyco Flow Control worked in cooperation with Politecnico di Milano to conduct materials testing. As part of an ongoing collaboration, Tyco and the university used CAD to re-create the operating environment, since testing in the actual physical environment would not be possible. Using COMSOL finite element analysis software, it was found that carbon steel, the traditional check valve hinge and disk material, would not endure the increased temperatures of a supercritical plant. As a result, C12A was selected for the hinge and disk due to its strength under pressure and temperature stresses.

QA procedures have led to the certification of two foundries within the Tyco global supply chain that meet high standards in quality and service. These foundries will produce the material for the valve body, disc and hinge. The contract also includes certification of Fasani to conduct much of the valve testing directly. Fasani will conduct critical and non-critical tests on each new valve to ensure quality and reliability, including ultrasonic, radiographic and impact resilience testing.

Bruno Manzetti, director of engineering, Fasani, commented: “With further advances in technology, we expect to see more and more supercritical power stations that occupy less space. This means that valves that can handle more challenging environments will be in greater demand.” He added: “Our engineers are available to discuss custom valve solutions for harsher environments. The new Fasani bled steam check valve is an example of our commitment to excellent service, and to working with our customers to meet their requirements.”

The valve was in design and development for more than a year and is available for situations where resilience to the environment and speed in closing are essential. Collaboration with the Politecnico di Milano formed a key stage in this design process. This partnership was part of an ongoing contract with the university that allows students to learn about industry issues and gain real-life experience, while Tyco Flow Control can access the university’s cutting-edge resources and knowledge.

With other projects to follow in Europe and further advances in plant technology, highly sophisticated valves such as the new Fasani valve are expected to be more in demand. Tyco Flow Control draws on a wealth of experience from many years in the power industry and a trusted portfolio of leading brands. In coal, gas, nuclear, solar, geothermal applications, Tyco engineers can provide service and product solutions to meet any requirements.

Tyco Valves & Controls
Tel: 01858 467281
Website: www.tycovalves-eu.com

Published: 1st September 2011