5
Scope of supply
LRR 1-40
1 Control unit LRR 1-40 (plug-in unit in plastic case)
1 Terminating resistor 120 Ω
1 Installation manual
Description
Continuous boilder blowdown (top blowdown)
As the boiler water evaporates, the concentration of non-volatile dissolved solids (TDS) left behind in
the boiler increases over time as a function of steam consumption. If the TDS (= total dissolved solids)
concentration exceeds the limit defined by the boiler manufacturer, foaming and priming occurs as the
density of the boiler water increases, resulting in a carry-over of solids with vapor into steam lines and
superheaters. As a result the operational safety is impaired and the steam boiler and/or pipelines can
be damaged. To keep the TDS concentration within admissible limits, a certain portion of boiler water
must be removed continuously or periodically (by means of a blowdown valve) and fresh make-up
water must be added to the boiler feed to compensate for the water lost through blowdown.
Intermittent boiler blowdown (bottom blowdown)
During the evaporation process fine sludge deposits settle on heating surfaces and in the lowest part of
the steam boiler. The accumulated sludge sediments form a thermally insulating layer and can damage
the boiler walls due to excessive heat.
The resulting suction effect occurs only at the moment when the valve is being opened, the opening
time should therefore not exceed 2 seconds.
The timed pulse/interval control of the intermittent blowdown valve optimises sludge removal while
minimising loss of boiler water.
The interval between the intermittent blowdown pulses can be set between 1 and 120 h
(intermittent
blowdown interval).
The
duration of the intermittent blowdown
can be set between 1 and 60 s.
For larger boilers it may be necessary to repeat the intermittent blowdown pulses. The
inter mittent
blowdown pulses
can be repeated up to 5 times within 5 - 30 seconds
(pulse interval)
.
The
continuous
and
intermittent boiler blowdown
is controlled by the control unit LRR 1-40 in
conjunction with the conductivity electrode LRG 16-40, LRG 16-41, LRG 17-40, the operating unit URB
or SPECTOR
control
and the continuous blowdown valve BAE 46, BAE 47.
In conjunction with the conductivity electrode and the operating unit you can also use the control unit
LRR 1-40 as conductivity limiter in steam boilers or for conducitivity monitoring in condensate and
feedwater systems.
The data exchange between the control unit LRR1-40, the conductivity electrode, the operating unit
and further equipment is effected via CAN bus according to ISO 11898, using the CANopen protocol.
Explanatory Notes
Note
The control unit LRR 1-40 can control the continuous blowdown valve BAE 46, BAE 47
with the actuator ARIS EF 1-1 either directly via the output relays or the continuous
blowdown valve BAE 46, BAE 47 with the actuator EF 1-40 via the CAN bus.
