Gas Turbine Temperature Measurement0 pages

Conax Buffalo is a manufacturerof temperaturesensors gas and steamturbines,generators
for
and other rotating equipment.
Shownis the company's
fiber optic gas turbine temperature
sensor,
cable assembly
and signalprocessor high temperature
for
turbine inlet measurement.

T

he surge in orders for aeroderivative and heavy-duty industrial
gas turbines over the past few
yearshas meant busy times for component suppliers, including the manufacturers of sensors and other critical instrumentation. As the technology of
these machines has evolved with higher temperatures, lower emissions and
oftentimes frequent cycling, the necessity for precise temperature measurement has also increased.
Conax Buffalo Technologies (CBT),
Buffalo, New York, U.S.A., has a long
record of supplying the power generation industry with temperature sensors
and associated installation fittings.
Starting in the 1960s with sensorsand
sealing assembliessupplied as original
equipment on steam turbines, present
day CBT offerings include sensorproducts for steam and gas turbines, steam
recovery systems,generatorsand other
rotating machinery.
"CBT has focused on the power generation market for many years and
strives to provide value-addedsolutions
specifically geared to the industry as it
has evolved," explained Richard Lyon,
turbine products manager for the company. "Steam turbine technology gave
way to gas turbine development and a
whole new rangeof temperaturesensing
applications was demanded by manufacturers.Our involvement with gasturbines startedwith the aircraft enginesector and rapidly led to the development

of products for aeroderivatives and
heavy-duty gas turbines as driven by
long-standing major customers.
"The consideration of benefits and
improvements to industrial gasturbines
through the use of Conax Buffalo products is necessarily specific to both the
product and application," Lyon said.
Following the 'dash for gas'and continued deregulation of electricity markets, gas turbine manufacturers have
sought greater efficiencies and lower
cost-of-ownership for end users and
utilities, as well as compliance with
international emission standards. "This
phase of evolution created a requirement for longer life, cost reduction and
increasedreliability for instrumentation
components,"said Lyon.
The development and implementation of Conax Buffalo's optical fiberbased sensor system for high temperature gaspath measurementcame about
from these requirements, according to
Lyon. The company's fiber optic temperature sensor system comprises a
sensing element in a probe housing, a
fiber optic cable and an opto-electronic
signal processor. The sensor technology is basedon thermal radiation, where
an optically emissivematerial is heated
by the gas stream and thus produces
thermal radiation. This optical energy
is transmitted down a sapphire light
guide that is supported in a probe
housing. A flexible optical fiber transmits the thermal radiation to a signal
processor, where it is converted to a

july-August 2002 Diesel& GasTurbineWorldwide

digital value corresponding to the probe
tip temperature.
The fiber optic sensorprobe component is installed at the first stageturbine
inlet and the system is designed to
measure temperature just downstream
of the combustor.
"We are given to understand that the
ability to determine accurate temperatures at the first stageprovides a number of significant advantages as the
requirements to have greater accuracy
of control of temperatures at this point
increases,"said Tony Henton, marketing manager- CBT Europe. "It is also
believed that this measurementpoint is
helpful in emission control. It is envisioned that the system will provide an
input to the engine control system at
some point in the near future - again
to augment accuracy.
"As further advantages, the optical
fiber-basedsystemis immune to calibration drift, has predicablelife characteristics and is unaffectedby thermal shock
and thermal cycling," Henton said.
Conax Buffalo designs,engineersand
manufacturessensorsin sizesstarting at
1 mm diameter with probe configurations available in more than 30 000
combinations of mounting styles suitable for applications from laboratory to
heavy-duty industrial environments.
"In the caseof traditional sensortechnologies, CBT supplies a significant
number of sensorproduct designsmade
exactly to individual gasturbine manufacturers' specifications.This long-term