Reference Manual

10B −9
D Typical process conditions:
— Fluid: White liquor
— T = 190_F
— P = 260 psig – 280 psig
— dP = 35 psi – 60 psi
— Q = 200 – 900 gpm
D Typical valve selection:
— NPS 2 to NPS 4 valves with alloy 6
scraper seats due to concerns over white
liquor scaling. A SST V300 valve with an
alloy 6 HD seal and alloy 6 bearings should
be used in this application.
Valve: LV-7 Digester level control valve
This valve controls liquor flow to the top of the
impregnation vessel. This is a critical and difficult
application on the Kamyr digester. This valve
needs to be operable with up to 300 psi of
differential pressure on some digesters. This
requires a valve capable of tight shut-off and high
pressure throttling. Cavitation is a common
problem with this valve.
D Typical process conditions:
— Fluid: Black liquor
— T = 235_F
— P = 300 psig
— dP = 45 psi – 90 psi
— Q = 1000-3000 gpm
D Typical valve selection:
— The V500 valve or CV500 in stainless
steel has proven to be a successful valve in
this application. The design of the Fisher
valves provides higher flow velocities which
tends to reduce the problems with scaling
that are seen at this location. Both the V500
valve and the CV500 should be supplied with
alloy 6 seats and installed in reverse flow
orientation.
— NPS 6 valve. This may be the most
critical valve in the system other than blow
line control. Capacity issues are a concern.
Valve: FV-61A Impregnation vessel
upper slouse flow
This valve is found only on dual vessel digesters
where it is used to add liquor to the upper dilution
zone to assist in the discharge of chips and liquor
from the impregnation vessel.
D Typical process conditions:
— Fluid: Black liquor
— T = 325_F
— P = 250 psig – 290 psig
— dP = 15 psi – 82 psi
D Typical valve selection:
— NPS 6 to NPS 8 valve with an alloy 6
scraping seat due to concerns over the
precipitation of calcium carbonate causing
plating or scaling buildup. A SST V300 valve
with an alloy 6 HD seal and alloy 6 bearings
should be used in this application.
Valve: FV-61 Impregnation vessel
lower slouse flow
This valve is found only on dual vessel digesters
where it is used to add liquor to the dilution zone
to assist in the discharge of chips and liquor from
the impregnation vessel.
D Typical process conditions:
— Fluid: Black liquor
— T = 345_F
— P = 235 psig – 260 psig
— dP = 25 psi – 52 psi
D Typical valve selection:
— NPS 4 to NPS 6 valve with an alloy 6
scraping seat due to concerns over the
precipitation of calcium carbonate causing
plating or scaling buildup. A SST V300 valve
with an alloy 6 HD seal and alloy 6 bearings
should be used in this application.
Valve: PV-30 Impregnation vessel
pressure relief
This valve is used to relieve excess pressure in
the impregnation vessel by releasing excess liquor
to the No. 2 flash tank.
D Typical process conditions:
— Fluid: Black liquor
— T = 235_F
— P = 180 psig
— dP = 155 psi
— Q = 2800gpm
D Typical valve selection:
— A CV500 (NPS 3) in stainless steel with
alloy 6 trim is a good valve for this
application.
Valve: FV-60 Black liquor to
impregnation vessel (bottom
circulation flow)
This valve is found only on dual vessel digesters
and is used to add black liquor to the outlet of the