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overall operating costs. Following is a general description
of the system setup, the CIP procedure, and the various
cleaning fluids.
Cleaning in Place (CIP) Procedure
Start
1. Shut off relevant pumps
2. Shut off the primary side's valves
3. Shut off the secondary side's valves
4. Empty the BPHE
5. Wash it with water to remove loose contamination
6. Connect the machine via inlet/outlet at front or
backside
7. Mix chemical and water according to instructions such
as for Scale 132 Copper
8. Heat the solution to 120-140˚F, make use of primary
side heat if possible
9. Pump the solution in the BPHE using the lower opening
to ventilate air. A flow rate corresponding to 1.5 times
the normal flow rate is suitable. Reverse the flow
direction every 30 min if possible. Monitor the
pressure differential. A pressure differential equal to
design criteria indicates a clean BPHE. Alternatively,
monitor pH. Constant pH value for 30 minutes
indicates a clean BPHE. For Scale 132 Copper pH of 3
indicates the need to renew the cleaning solution, then
empty the BPHE and restart at point 5. The cleaning
time varies, but is estimated to 4-8 hours.
Stop
10. Flush from the lower opening for 5 minutes before
changing direction. Repeat this operation until no
more dirt is flushed out
11. Empty the BPHE and the machine, handle the used
solution properly
12. Flush the BPHE with water starting from the lower
opening until pH 7
13. To pickle and passivate steel use 2% phosphoric acid at
50°C (120°F) for 4-6 h.
14. Flush the BPHE with water starting from the lower
opening until pH 7
CIP Fluids
Bio Gen Active – Scale 132 Copper
Commercially available Scale 132 Copper removes lime
scale and other carbonates as well as rust and other metal
oxides without the risk of corrosion.
Organic Acids
Organic acids are less hazardous than mineral acids,
which makes them a good choice for BPHE cleaning.
Organic acids include formic, acetic, and citric acids,
CG-SVX044B-EN
among others, and are commonly applied at
concentrations between 1 and 5 volume percent.
Formic Acid
Formic acid alone is unable to remove iron oxide why it's
used as a mixture with citric acid or HCl. Formic acid can
be used on stainless steels, it's relatively inexpensive and
can be disposed by incineration.
Acetic Acid
Dissolves lime scale, but doesn't remove iron oxide
deposits. Since it's weaker than formic acid, it is preferred
where long contact times are necessary.
Citric Acid
Mild iron contamination can be removed by using a
mixture of 1% each of citric acid and HNO3. For more
persistent contaminations, stronger solutions must be
used.
Bases
Bases have the ability of removing oil, grease and
biological deposits from the heat exchanger surface and
may be applied as a complement during cleaning. They
may also be added at the end of the cleaning procedure,
before the last rinse with water, to neutralize any acid
content left in the system. A solution of 1-2% sodium
hydroxide (NaOH) or sodium bicarbonate (NaHCO3)
before the last rinse ensures that all acid is neutralized.
CIP Pumps
Important features:
•
The reservoir should be made in acid- and alkali-
resistant material.
•
The hoses should be made in PVC.
•
A reverse flow device enables attack of lime scale from
both directions.
•
A heating device enables the CIP solution to reach
much better effect.
•
The flow rate capacity depends on the size of the BPHE.
COMMERCIALLY AVAILABLE CIP FLUIDS
Bio Gen Active – Scale 132 Copper
Description: Scale 132 effectively removes lime scale and
metal oxides (e.g. rust) without etching the material. It's
used for reconditioning of waterborne systems. The
product is mild to user, material and the environment.
Maintenance
41
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