Flowserve BA46 - Manual (Page 7)

7
System description
Due to the continuous evaporation process in the steam boiler the density and hence the TDS
(= Total Dissolved Solids) concentration of the boiler water is increased. The TDS level must remain
within the limits specified by the boiler manufacturer and applicable guidelines. For this purpose a
certain amount of boiler water (= boiler blowdown) is discharged continuously or periodically. The
continuous blowdown valves BA... and BAE... feature specially designed and wear resistant nozzle stems
that enter concentrically into a system of expansion chambers which are arranged one after the other,
making the valve well suited for the continuous discharge of boiler blowdown at very high differential
pressures. The continuous blowdown valves BA... and BAE ... are suitable for operation in steam boiler
plants according to TRD 604, EN 95 and EN 953
.
n
BA 46 PN 40, manually operated
n
BA 47 PN 63, manually operated
n
BAE 46 PN 40, operated by the electric actuator EF...*)
n
BAE 47 PN 63, operated by the electric actuator EF...*)
*) Explosion-proof actuators or actuators powered by d. c. or three-phase current are available
on request.
The continuous blowdown valve BA 46/BA 47 is moved to its control position by means of the control
lever. Use the scale on the control lever to adjust the required amount of boiler blowdown.The required
amount of boiler blowdown is calculated with the aid of a formula or read off on a nomogram. The
continuous blowdown valve BAE 46/BAE 47 is motored to its control position by means of the actua-
tor EF... The actuator is activated by the GESTRA conductivity controller KS 90 working in conjunction
with the GESTRA conductivity electrode LRGT ...- or the conductivity controller LRR -5, LRR -6 in
combination with the GESTRA conductivity electrode LRG 6... or the conductivity controller LRR -40 in
conjunction with the conductivity electrode LRG ..-40.
The actuator opens or closes the continuous blowdown valve as a function of the required amount of
boiler blowdown and the desired operating position, at which – independent of the actual electrical
conductivity of the boiler water – a freely selectable fundamental amount can be discharged by the BAE
46/BAE 47. The valve positions “OPEN” and “CLOSED” are limited by the cam-operated switch located in
the actuator, the “OPERATING POSITION” is variably adjustable by means of an operating cam. The power
flow towards the closing direction is transmitted via a rigid coupling with integrated torsion spring. The
coupling permits the actuator to travel a little bit further when the nozzle stem is pressed into the valve
seat.
The conductivity of the boiler water is monitored by the equipment combination consisting of a
conductivity electrode and a conductivity controller. The continuous evaporation process in the steam
boiler increases the boiler water density and, consequently, the TDS level, causing the conductivity of
the boiler water to rise. Once the set limit value is reached, the actuator receives an opening pulse from
the conductivity controller according to the deviation from the conductivity setpoint. When the adjusted
conductivity setpoint is attained, the actuator closes the continuous blowdown valve or returns to the
adjusted operating position. The valve positions “CLOSED” and “OPEN” are limited by the cam-operated
switch in the actuator, the “OPERATING POSITION” is variably adjustable by means of an operating cam
or a feedback potentiometer.
Function
Explanatory Notes
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