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Design information
(cont.)
Prevention of combustion chamber overfilling
In accordance with TRVB 118, a fill level monitor should be installed
to prevent overfilling of the combustion chamber. The boiler has two
light barriers for incandescence monitoring. A sensor directly on the
insert pipe is used to detect any sign of a burn-back risk and to coun-
teract this early on by means of a short term output increase (increase
in material feed).
Reignition protection (RZS)
In accordance with TRVB 118, reignition protection is prescribed for
all systems over 150 kW. If a spark detection and extinguishing facility
is not used, TRD 414 prescribes a constantly available separating
barrier (TRD 414 relates primarily to wood remnants from the prepa-
ration and distribution of wood and wood materials). There are simpler
ways of achieving this for woodchips from the forestry and sawmill
sector.
Back burning protection, fuel supply (RSE)
Additional "material transportation back burning protection" depends
on the relevant requirements (location, size of the fuel store, material,
pressure, regulations) and is a separate item of the standard delivery
ordered from KÖB Holzfeuerungen GmbH.
Shut-off gate valve
The shut-off gate valve is permissible in all unpressurised fuel stores
and is considered suitable back burning protection in accordance with
TRVB 118 (test certificate BV 2979/89).
Rotary lock valve
If the wood remnants are introduced with fans in fuel storage rooms,
due to the pressure load, at least one rotary lock valve is required to
reduce pressure between the fuel store and the boiler. The rotary lock
valve is suitable for reducing pressure and at the same time is con-
sidered suitable back burning protection in accordance with TRVB 118
(test certificate BV 2979/89).
Low water indicator
EN 12828 specifies that boilers must be equipped with a low water
indicator (water level limiter). Tests have verified that the burner will
be automatically switched off in the event of water shortage due to a
leak in the heating system and oil burner operation, before the boiler
or the flue system reach unacceptably high temperatures.
Maximum pressure limiter
If the rated output of the wood boiler is more than 300 kW, a maximum
pressure limit is required for each boiler in a system.
Minimum pressure limiter
Recommended for flow temperatures in excess of 100 ºC. One
required per multi boiler system.
Safety valve
Equip the boilers to EN 12828 with a type-tested safety valve. For all
other operating conditions, this must be identified in accordance with
TRD 721 with "D/G/H".
Expansion vessel
For boilers above 300 kW, install an expansion vessel with blow-off
and drain line near the safety valve. In order to prevent a risk caused
by escaping steam, the discharge pipe must be routed to the out-
side.
PYROT
As a result, any prescribed protection device does not come into effect
and normal operation is maintained with regard to the greatest possible
heat supply reliability.
The boiler is equipped with a separating barrier and is operated per-
manently with underpressure. The boiler is then equipped with reig-
nition protection (RZS) in accordance with both TRVB 118 and
TRD 414.
For this boiler, we recommend installing a rotary lock valve. In addition
to the back burning protection, the penetration of infiltrating air via the
supply screw conveyor is also prevented.
■ Max. permissible overpressure in the fuel store: + 500 Pa
■ Max. permissible underpressure in the fuel store: + 0 Pa
For installation purposes, the wood boilers have a R½ connector on
top of the boiler.
The pipework between the boiler and the safety valve must not be able
to be shut off. Pumps, fittings or restrictions must not be present in this
pipework.
The discharge pipe on the safety valve should be constructed so as to
prevent the possibility of increases in pressure. Arrange the outlet of
the drain line so that any water expelled by the safety valve can be
safely observed and drained off.
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