3M MEMBRANA Liqui-Cel, Инструкция по уборке

Страница: 13 / 26

11
Liqui-Cel
®
Membrane Contactors Cleaning Guidelines
A. Biological Soil Removal
Typically, a decrease in contactor gas transfer efficiency or an increase in liquid or gas
pressure drop through contactor indicates that the contactor requires cleaning. If soil has not
penetrated the membrane pore structure, a surface cleaning of the wetted side of the
membrane (normally the shellside) is usually sufficient. If the performance is not restored
after two cleaning cycles, then use the
Severe Biological Soil Cleaning Protocol, section
VI-B.
Table 4: Recommended Cleaning Procedure For Normal Biological Fouling
Step Description Chemical Solution Time
1
Water flush / once
through
10 micron filtered, ambient to cold water 5 min
2
Alkaline wash /
recirculated
2% to 6% w/w caustic (NaOH or KOH) solution, using 10 micron
filtered water.
Suggested temperature ambient to 122 ºF (ambient to 50 ºC)
30 min to 4 hrs.
3
Water flush / once
through
10 micron filtered, ambient to cold, water
5 to 15 minutes.
4
Acid rinse /
recirculated
10% w/w citric, or 3% Nitric or phosphoric, or 3% hydrochloric or a
combination of 3% Nitric and 3% phosphoric acid solution or 3% Nitric
and 3% HCL using filtered (10 micron) water at ambient temp.
30 min to 2 hrs.
5
Water flush / once
through
10 micron filtered, ambient to cold, water
Until acceptable
cleaning solution
pH is achieved
6 Purge lumens
CO
2,
N
2,
air at maximum flow rate. If operating in combo mode, use
maximum sweep gas in combination with the vacuum pump.
Until no water droplets
appear from exit sweep
port
Do not use any commercial cleaner that contains surfactants.
B. Recommended cleaning procedure for severe fouling
Wet-out refers to a condition of the membrane when it has lost its hydrophobic property, thus
allowing liquids to pass through the pore structure. Wet-out can also occur when the
membrane is exposed to protein-containing liquids such as beer, wine or fruit juice. Removing
biological deposits that have penetrated the membrane pore structure will restore the
membrane to a hydrophobic state. To remove the proteins adhering to the polymer surface, a
Severe Biological Soil Cleaning Protocol is recommended.
This uses an alcohol-water solution and then a final drying step. The cleaning frequency
depends on the types and concentrations of proteins. In order to prevent wet-out, a daily
cleaning protocol should be used until an appropriate cleaning frequency is determined.
The drying step is critical for removing any remaining liquid from the pore structure. If liquid
remains in the pore structure, any liquids introduced into the contactor during operation will
pass through the membrane.
Therefore, the contactor must be dried before it is put back
into service .
Contact a 3M representative to learn more about contract cleaning services available in our
facility for your convenience.