Vibro-Meter of Switzerland and Piezocryst of Austria have joined forces to further develop and arket piezoelectric sensors for turbo machinery applications. These sensors are particularly designed to measure gas turbine combustion chamber vibrations that originate from the lean burned air/fuel mixture used to minimize NOx formation. The cooperation between the two companies is intended to combine the individual strengths of both partners to provide additional customer benefits, especially: complete production portfolio for turbine sensing and monitoring; new sensor technology with improved properties; and reduced lead time by combining forces in R&D and production.

Shown is a Vibro-Meter/ Piezocryst high-temperature pressure sensor for gas turbine combustion chamber applications.

Within this frame Vibro-Meter will be responsible for sales, customer service and support, while Piezocryst will pursue future developments and production of dynamic pressure sensors. The continuity of existing products and services will, of course, be assured. The new sensor line, based on a Gallium Phosphate technology, introduced in cooperation with iezocryst, improves sensing behavior. Piezocryst, technologically, is probably the leading company for combusabletion analysis sensors in the automotive industry.

Based on its unique hightemperature single crystalline material gallium phosphate (GaPO4), Piezocryst has complemented its core business in automotive combustion analysis by the monitoring and control of large engines and gas turbines. Gallium phosphate is a perfect pressure sensing element because it does not show any signal variation when exposed to temperature changes. Its single crystal industrial growth process ensures a constant material quality with intrinsic material sensitivity.

This crystal has been used in technical applications such as pressure sensors since 1994. Gallium phosphate exhibits excellent thermal stability of piezoelectric constants, its phase transition starts at a temperature of 970°C while longterm testing at 950°C showed no sign of structure changes. The high performance of test bed sensors, which for example enables high quality thermodynamic calculations, is now avail- combusable for long-term monitoring and closed-loop applications in very demanding combustion applications.

These new dynamic pressure sensors for high-temperature R&D and monitoring purposes enable monitoring pulsations from very high frequencies down to extremely low frequencies. As a consequence, it ensures accurate measurements under thermal gradients — especially during machine start-up — and high signal quality at very low frequencies.

Furthermore, their high internal insulation resistance at operating temperatures improves the signalto- noise ratio, and their very small sensitivity deviation over temperature allows for accurate measurements over the entire temperature range. According to the two partners, this new technology will help to reduce fuel consumption and emission levels of gas turbines. The overall idea of the cooperation is to combine knowledge and resources to better serve the customers with improved solutions and services.

Within the cooperation, Vibro-Meter will be responsible for sales and marketing. To guarantee the same high level of customer service, sales and service will be carried out by existing experienced staff. Piezocryst will be responsible for the future development and production of dynamic pressure sensors. Based on the existing combustion expertise, new products will be developed with improved properties.

Shown is a comparison between the piezoelectric constant d11 of the GaPO4 and quartz. The GaPO4 is twice as sensitive as quartz and extremely linear over a wide temperature range.

Leave a Reply