Untitled

12
Seiberling
(380 L) for the solution wash, plus 200 gal (760 L) for the post-rinse, plus 100 gal
(380 L) for an acidified rinse, plus 200 gal (760 L) (perhaps more) for the final pure
water rinse.
The total water requirement for a spray cleaning program for avessel is related to
( i )the spray delivery rate, ( ii) the volume of the CIPS/CIPR, and ( iii) the volume of
the recirculation tank, plus ( iv) the holdup volume required in the vessel being
cleaned to achieve reliable recirculation. Prerinse and post-rinse times of 40 to 60
seconds are generally adequate. Afinal pure water rinse once through to the drain
may require delivery at the spray design rate for two to three minutes, or more.
Aconservative estimate for the total water requirement for cleaning atank at 80 gpm
(300 lpm) in asystem containing 200 ft (61 m) of 2in. (50 mm) supply/return piping
would include 80 gal (300 L) for the prerinse, 40 gal (150 L) for the solution wash,
80 gal (300 L) for the post-rinse, 40 gal (150 L) for the acidified rinse, and 240 to
360 gal (900–1350 L) for the final pure water rinse, for asingle tank CIP unit which
operates with no solution in the recirculation unit tank. Alternative multi-tank
recirculating units may add an additional 100 to 150 gal (380–570 L) total in the
solution tank and in the vessel being cleaned to achieve stable recirculation with
pumped return. Deadlegs in the CIPS/R piping and excessive holdup in the vessel
will dramatically increase the rinse volume required to achieve set-point resistivity.
Tank and Line CIP in Combination
Whereas vessels and lines are traditionally cleaned in separate circuits because of
the different CIPS flow and pressure requirements, the careful consideration of the
above numbers will reveal that the major amount of water used for the total
program is to fill the CIPS/R piping to and from the circuit. For aCIPS/R length of
100 ft of 2in. tubing, this will be 28 gal minimum. Avery large vessel fitted with a
vortex breaker may need only 3to5gal more for reliable recirculation. A50ft
transfer line of 1.5 in. diameter will contain only 3.5 gal of solution. The addition of
the transfer line to the vessel circuit will increase the volume contained in the circuit
by only 10% to 15% and washing the vessel and line in combination will effectively
reduce total water for both circuits by 40% to 45%, as compared to washing them
individually. There isgenerally no scheduling problem to wash the transfer line
with the vessel as both are soiled and available for CIP at the same time following
the transfer. The two individual tank and line circuits shown in Figure 6can be
combined by installing the 3-Leg U-Bend illustrated in Figure 4onTP1, thus
combining CIPR flow from the vessel (port 3) and the transfer line (port 4) to the
CIPR pump (port 6). Tank T1 would be sprayed and the inlet line “pulsed” as
described above for tank CIP,and CIPS2 would open for perhaps 20 to 30 seconds of
each minute, allowing flush, wash and rinse solutions to pass through the transfer
line in areverse direction, with motivation being the back pressure caused by the
sprays, commonly operated at 25 psi.
Addition of aProcess Component to aTransfer Line
Seldom will asimple length of unobstructed tubing be installed between the two
tanks of atrain. The transfer path may include apump, filter, heat exchanger,
another process component, or acombination of several such devices.
Figure 8 illustrates a relatively simple product filter through which the
transfer could be accomplished via head pressure as previously described.
Following completion of the transfer, the filter housing would be opened to