felisa FE-390 Instructivo De Operación página 10

EVAPORATOR
Still evaporator are the vertical, cylindrical double wall type with air-insulating space. The evaporator
are built sufficiently high and wide to provide ample vapor disengaging space and operation at low
velocity. The evaporator cabinet is 304 Stainless Steel, the inner boiler is fabricated in copper, brass
and bronze. All surfaces in contact with the water and steam are coated with a nonstick resin for make
easier the scale cleaning.
CONDENSER
Still condensers are the horizontal type, slightly inclined and atmospherically vented, for final
elimination of gaseous impurities, the condenser are fabricated of cooper and brass finished in
polished nickel. All surfaces that contact the vapor and distillate are coated with pure tin to prevent
metallic contamination. A distillate delivery tube (11) is provided.
ELECTRIC HEATERS
Immersion type heaters (15) are used to give complete heat transfer and maximum heating
efficiency. Heater life may be reduced when operated above maximum voltage, operation with a
voltage less than the above stated, will cause a drop in the Still output.
PRETREATMENT
All Stills Felisa for convenience have been designed with a pretreated feed water kit that utilizes
disposable demineralizer cartridges (18) for removal most ionic impurities. The use of pretreated
water increases purity and decreases cleaning.
Note: The cartridge must be replaced in order to the feed water quality and the operation time.
FEATURES
All Stills are equipped with a deconcentrator valve (5) to continuously deconcentrate impurities from
the evaporator and retard scale formation. A constant level device (6) with hot well arrangement is
provided for evaporator water level control and for primary elimination of gaseous impurities. All
Stills are equipped with a drain valve (8), cooling water discharge piping (10) is provided between the
cooling water outlet to the condenser level device.
DECONCENTRATOR
The role of the deconcentator is to mantain a minimum concentration of dissolved impurities in the
evaporator, thus reducing to a minimum scale formation and tendency to foam. You have to adjusted
as follow.
A.- Permanent hard water or softened water: The valve should be left open at all time, to bleed water
from the evaporator at approximately 1.2 times the distilled water flow in (11). Care should be
exercised to see that it is never clogged, the valve should be inspected periodically and if required,
disassembled and cleaned with a brush or scraper.
B.- Temporary hard water: If the feed water to the evaporator is high in temporary hardness (high in
bicarbonates) the valve should be closed. The reason in that the bicarbonates in solution tends to
precipitate at temperatures up to 150 °F. With the deconcentrator valve open, a large quantity of
feed water passes through the evaporator, precipitating bicarbonates, increasing the scale
formation. Keeping the valve close, will result in an increased concentration of solids in the
evaporator, thus create a tendency to foam. This condition is corrected by draining the Still trough the
drain valve at frequent intervals.
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