Original control electronics of the boiler controls fuel
feeding rate, air flow to the combustion chamber and grate
sweeping period. The fuel feeding is realized by changing
duration of running time of the screw feeder that periodically
repeats every 20 seconds. Grate sweeping movement is
repeated once every 10 minutes. Air flow is controlled using
thyristor regulation leaving out every n-th period of 50 Hz
AC source frequency.
The instrumentation and control equipment of the boiler
was not sufficient for the experimental purposes and thus it
was extended. A couple of thermocouples, flue gas analyzer
and frequency inverter for control of combustion air fan
speed were installed.
However, the original control unit was a custom made
electronics that did not allow for any external algorithm
change or acquisition of the measured data. The original
electronics could not be replaced because the boiler is also
used for educational purposes.
Another control unit was therefore built in parallel to the
original electronics. Operator of the boiler can choose
between control units by switching control member plugs
between control unit’s outlets