Reference Manual

12−5
Typical Specification:
ES flow-down for on/off sootblowers.
To conserve energy, mills have moved to
throttling sootblower valves. Use an ED.
Tight shutoff not needed as sootblower nozzles
have tight shutoff.
Model:
ES for on/off, flow down, quick opening cage,
Class V
ED for throttling, =% cage, flow down, Class II
These units provide high pressure and
temperature capability along with the tight
shutoff required.
Drilled-hole cage (flow-up)
Body: WCC
Trim: Quick opening cage or Whisper
cage for noise attenuation
Cage: S31600 CoCr-A seat and
guide
Plug: 316 CoCr-A
Seat: R30006 (alloy 6)
Seat Ring Retainer: R30006
(alloy 6)
Stem: Nitronic 50. Optional
oversized stem or oversized
VSC
Bonnet:: PTFE packing
Actuator: 667 spring-and-diaphragm or
585C piston
Positioner: DVC6010 c/w performance
diagnostics
Fisher Engineered Specification:
The Fisher ES and ED cage-guided globe valves
provide maximum stability and ruggedness in high
pressure drop applications. The ES is offered with
an unbalanced plug and the ED with its balanced
plug to minimize actuator thrust requirements.
Both designs have hardened trim for superior
erosion resistance. The plug and stem assembly
is reinforced through the use of high tensile
materials and oversized valve stem connection.
High noise levels are often present in high
pressure drop, high flow steam applications.
Noise attenuation can be achieved with
engineered valve trim combined with an inline
diffuser for additional noise reduction when
required. Typically Whisper Trimt I and a Fisher
6011 downstream diffuser are the most practical
and economical solution; however, there are other
options available that allow for full attenuation at
the valve such as the Fisher Whisper Trim III or
WhisperFlot trim. There are many factors to
consider such as capacity, turndown, line size,
and overall economics when selecting an
appropriate solution.
Chemical Reduction
Chemical reduction occurs via the char bed at the
floor of the recovery furnace. The molten liquid
bed typically operates at temperature of 1600°F -
2500°F. The introduction of air via the primary air
ports provides the oxygen required to burn the
carbon and reduce the sulfate to sulfide. The
molten smelt, consisting primarily of Na
2
CO
3
and
Na
2
S, flows by gravity to the dissolving tank. The
dissolving tank is filled with weak wash to cool the
smelt and produce a solution suitable for pumping.
The solution formed, known as green liquor, is
then transferred to the recausticizing area for
addition of lime and regeneration of white liquor.
The dissolving tank is vented to the atmosphere
via a tall stack. Since the sodium and sulfur
compounds in the smelt present a source of odor
emission, the vented gas is often treated with a
scrubber. Although the scrubbers vary in design
and complexity, a solution of weak wash is often
used as the scrubbing medium.
Control Valve Selection
Although table 12-1 indicates many of the critical
control valves, other general service control valves
are required for the successful operation of a
recovery boiler. Many of the valves are on mill
supply water, instrument air, plant air, or low
pressure steam heating lines.