Htw Steam Generators - Honeywell AUTOMATIC CONTROL SI Edition Engineering Manual

HTW STEAM GENERATORS

Using the central HTW boilers for steam production is not
recommended. The HTW system is best used to produce steam
by locating steam generators at the point of need.
The steam generator (Fig. 125) is designed so that the
minimum water level covering the tubes takes up 60 percent or
less of the volume of the shell. The remaining 40 percent for
steam is sufficient to avoid water carry over. A water eliminator
at the steam exit removes most water from the steam.
RELAY CLOSES
VALVE WHEN PUMP STOPS
(NOT REQUIRED TO
PREVENT FLASHING)
HIGH TEMPERATURE
WATER VALVE
HTWR HTWS
ENGINEERING MANUAL OF AUTOMATIC CONTROL
CHILLER, BOILER, AND DISTRIBUTION SYSTEM CONTROL APPLICATIONS
TO PUMP INTERLOCK
AND/OR OUTDOOR
CONTROLLER
HOT WATER
TEMPERATURE
CONTROL
STORAGE
CONVERTER
Fig. 124. HTW to HW Multizone Storage Converter.
OPTIONAL
RELAY
ALARM
CLOSES
VALVE IF
SAFETY
LIMITS
EXCEEDED
PRESSURE
PRESSURE HIGH LIMIT
CONTROL
HIGH
TEMPERATURE
WATER VALVE
CONVERTER
HTWR HTWS
FEED BLOWDOWN
INLET AND DRAIN
Fig. 125. Steam Generator Using HTW.
Flash converters convert HTW to steam by reducing the
pressure. They are not satisfactory steam generators because
water is carried with the steam and control is less stable.
Control of a steam generator is simpler because pressure
changes are sensed immediately and corrections in valve position
are made quickly to maintain the desired steam pressure.
RESET SIGNAL
FROM OUTDOOR
CONTROLLER
HOT WATER
3-WAY ZONE
VALVE
TO HOT WATER
CONVERTER
PUMP
MANUAL
BALANCING
VALVE
TYPICAL ZONE
RELIEF
VALVE
STEAM
STORAGE
STEAM
GENERATOR
CONDENSATE
RETURN
379
ZONE WATER
TEMPERATURE
CONTROLLER
HWS
45-95˚C
HWR
C4627
MAKE UP
WATER
LEVEL
CONTROL
LOW
WATER
CUT OFF
MAKE UP
WATER
C2588