3 Mode of operation – Functional description
21
C
OMBUSTION
PROCESS
When there is a need for heat in the accumulator the HDG Compact
20 – 80 automatically starts the “first filling” by loading fuel from the
fuel store into the combustion chamber (8) via the feeding system
(1).
After completion of the “first filling” the electric ignitor produces hot
air which sets fire to the fuel in the combustion chamber (8). After this
“ignition” phase the “heating up” phase begins when the fuel is intro-
duced to the combustion chamber at a gradually increasing prede-
termined rate.
Following the “heating up” phase the HDG Compact 25 – 80 goes
into “automatic control” where the amount of fuel, primary air and
secondary air is provided, based on the combustion requirements.
The ash produced during combustion is removed by tipping the
grate (7) at regular intervals. The automatic cleaning (4) removes the
lighter fly ash from the heat exchanger surfaces (3) periodically by
raising and lowering the turbulators.
The ash falls into either an ash pan in the base of the boiler or onto
ash removal augers (6) which extract the waste material into ash con-
tainers.
The amount of primary and secondary air introduced into the com-
bustion chamber (8) is governed by primary and secondary servos,
and dictated by the control to maintain efficient combustion.
The Lambda sensor (5), boiler temperature, and combustion
chamber sensor (2) feed information back to the control to do the fol-
lowing:
– Continuously monitor firing
– Adapt the boiler to heat requirements
Figure 3/6 - HDG Compact 45/50/65/80 heating system
7
8
2
1
4
5
3
6
