Method for operating a compressor
View Patent ↗A method for operating a compressor including providing suction pressure measurement, final pressure measurement, throughput measurement is provided. Using a first control characteristic map a target value for a pump surge limiter is determined from one or two of the measurements, and the pump surge limiter compares the target value to the throughput measurement, wherein the pump surge limiter opens a bypass valve when the measured value falls below or exceeds the target value, such that the final pressure is lowered or the flow through the compressor is increased. In the event of failure of a measurement, a further measurement of another physical variable of the compression process, together with a measured variable that did not fail or a modification of the measured variable, is an input variable for a substitute control characteristic map, form which a substitute target value is determined.
1. A method for operating a compressor, comprising:
providing measured values including a suction pressure measurement, a final pressure measurement, and a throughput measurement;
in normal operation during which the measured values proceed faultlessly,
determining a target value for a surge limiter from a measured value by means of a first control characteristic map;
comparing the target value with the throughput measurement directly or indirectly by the surge limiter; and
opening a closed bypass valve by the surge limiter when the throughput measurement falls below or exceeds the target value whereby the final pressure is lowered or a flow through the compressor is increased,
wherein in the event of failure of a measured value, the determining step includes determining a substitute target value by a substitute control characteristic map using a further measurement of another physical variable of the compression process and one of the measured values that did not fail or a modification of the measured value that did not fail,
wherein the further measurement is a measurement of a setting angle of an intake guiding apparatus, and
wherein, in the event of a failure of the final pressure measurement or the suction pressure measurement, the following applies:
p
E
p
A
≤
p
E
p
A
|
max
=
f
(
α
)
or
p
E
p
A
≤
p
E
p
A
|
max
=
f
(
n
)
wherein
α=setting angle of the intake guiding apparatus, and
n=rotational speed of the drive.
2. The method as claimed in claim 1 ,
wherein, in normal operation, the target value for the surge limiter, which corresponds to a minimum value for the throughput measurement, is determined from the suction pressure measurement and the final pressure measurement by means of the first control characteristic map, whereby the surge limiter opens the bypass valve when the throughput measurement falls below a minimum value for the throughput measurement.
3. The method as claimed in claim 1 , wherein the suction pressure measurement and/or the final pressure measurement and/or the throughput measurement as an input variable of a characteristic map are normalized to a process variable.
4. The method as claimed in claim 3 , wherein the suction pressure measurement is the input variable of the characteristic map that is normalized to the process value.
5. The method as claimed in claim 1 , wherein, in the event of a failure of the throughput measurement, the pressure ratio is limited by a limiter according to:
p
E
p
A
≤
p
E
p
A
|
min
*
S
with S<1.