equipment One of the biggest problems in the project is
to determine the position of the robot inside the cooling tower.
The environment in the tower is very humid and hot, with the
lot of fog. We have tried almost all standard solutions for
determination of a robot's position, but none of them was possible.
Laser range-finding method (LIDAR) is not possible due to a
fog, satellite GPS is not possible, because the tower is almost
closed at the top, direct measurement of a passed path with
the positioning of an electronic compass is not possible due
to a rough tower floor surface, etc.
The only possible
solution is as we see so called Ultrasonic GPS. This measuring
method defines the position of a robot with the triangulation
of several ultrasonic transponders. On the robot is a special
Ultrasonic transmitter unit which sends ultrasound signals.
Those sound signals are detected with the Transponder units
which are positioned on the known locations inside the tower.
To sinhronise all signals, all of the remote transponders and
the robots Ultrasonic transmitter are linked together with the
radio 433MHz signal.
Because of a harsh environment a special version of a ultrasonic transponder was tested. This is the State of the art unit, sealed and water proof, because of its power it can also be used for bigger distances. It's high resonant frequency (92 kHz) allows to use it even in the environment full of noise. Several test were made with the new transducer in the lab and we plan to put it on the test in real cooling tower environment in the beginning of the year 2000. Up to now some real time distance measurement with the prototype lab units were made to show the use of the method and to evaluate the final version. The prototype Ultrasonic transponder unit and a LCD display type Ultrasonic receiver were made and tested. We can with those measure the distances up to 30 m. With the final version of the Ultrasonic GPS the computer will through it's attached A/D card read the distance to all remote Ultrasonic Transponders and transmit the data of all distances via Radio link to the external host computer. This method didn't work at the final testing.
are basic parameters, measured on-line simultaneously with aid
of computer system, additional parameters, measured in different
time intervals, and system parameters which were taken from
the power plant control room. The measurements are performed
according to the standard DIN 1947.
field of the cooling tower Air velocity field of
the cooling tower is measured with a current-meter mounted on the
vehicle. Measurement error is approximately 2% of the measuring
value. Current-meter made on TURBOINSTITUTE have 100mm diameter and
spiral pitch 125 mm. Propeller is made of polished aluminium alloy
and is able to measure fluid velocities up to 4 m/s. Current-meter
holder is made of stainless-steel with magnetic relay to detect
rotation of the current-meter. Special petroleum lubricated bearings
allow durable operation with invariable characteristics.
Well-balanced and calibrated current-meter has high time-stability
and accuracy. Current-meter is pre-calibrated. With each rotation of
the current-meter four signal changes are generated (from 0 to 1 or
reverse) which are sensed by the measuring system. The measurement
time of one operational point is 1 minute. Software for
current-meters calibration and flow measurement was developed by
temperature field in the cooling tower Air temperature field in
the cooling tower is measured by Pt-100 temperature sensor located
beside current-meter on the tracked vehicle. Time interval of
temperature measurement at respective measurement position is 1
Water flow in
the outlet channel Water flow in the outlet channel is obtained
indirectly with measurement of water level and water velocity. The
water velocity is measured with the ultrasonic type of a flow meter.
RESULTS The Figures 3 to 5 should be given as an example of
final measuring results in the cooling tower measurement plane.
structure of the velocity profile; P = 331 MW.
Topological structure of the temperature profile; P = 331 MW.
EFFICIENCY INCREASE AFTER RECONSTRUCTION OF COOLING TOWER