Under certain conditions, and with care and judgment, the use of
refined petroleum has been found to be of great advantage in removing
and preventing scaling in steam boilers.
There is no well authenticated case where a systematic, regular and
uniform feed of pure kerosene oil to a steam boiler has failed to
operate beneficially upon the scale formation.
The best results are obtained by the use of the oil _under the same
arrangement that cylinder oil is fed to an engine_. The kerosene is
sometimes introduced through a one-fourth inch branch to the suction
pipe of the feed pump, leading to the vessel containing the oil,
so that any quantity, large or small, can be put into the boiler
simultaneously with the usual feed. The drawback to this arrangement
is that when the feed water heater has to be cleaned, a gallon or more
of the oil is often lost, which together with a very unpleasant odor,
when used in this manner, tends to condemn its use. _But when piped
between the boiler and heater_, these objections cease. We present an
arrangement which is illustrated by cut on page 157.
This is nothing more than a storage system with sight feed, by use of
which the oil can be fed drop by drop as desired—for each drop of water
entering the reservoir a drop of oil is forced down the small 1/4-in.
pipe, up the glass tube and on into the boiler.
In piping it is necessary to have the water or larger pipe (1/2 in.)
attached through the lower plug as shown in cut, and the oil as shown,
going through the smaller or 1/4-in. pipe—_i.e._, the oil pipe must,
under all circumstances, be the smaller of the two.
In the figure is shown a piece of 6-in. gaspipe, about a foot in
length, plugged at each end; the top plug has one opening, for an
inch nipple “a” with top. This opening is to be used in filling the
reservoir with oil. The bottom plug has two holes, one for the 1/2-inch
water pipe, and the second for a small pet cock “B,” to let the water
out, whenever it is necessary to refill the tank with kerosene. The
water gauge connection is the ordinary, cheap brass fixture, with
boxes, nipples, etc., used in boilers, with gasket of rubber bottom
and top of the glass. The glass plainly exhibits the depth of water
and oil in the reservoir as well as the feed of minute drops of oil as
they speed on their beneficent mission softening the injurious scale.
There are the usual 2 valves on the water glass; by opening the lower
one more or less, the amount of oil used can be regulated to a nicety.
The valves can be used to entirely cut off the apparatus at any time
desired.
[Illustration: METHOD OF FEEDING KEROSENE OIL TO BOILER.—Fig. 69.]
NOTE.—Should the end of the screw connection inside the holder which
each one of these valves control, not be 1/4 inch, a reduced elbow
should be used, as 1/4-in. pipe will give the best satisfaction when
used as a stand pipe inside the reservoir.
The quantity of oil to be fed to a boiler is very largely to be
determined by experiment commencing with a minimum and increasing the
amount as found necessary to keep down the scale formation. The use
of 2 qts. of the oil per week has been found to be sufficient for a
boiler 4 feet in diameter and 12 feet long, and three quarts per week
on boilers 5 feet in diameter. This quantity may be regarded as the
smallest advisable to use and from that up to 1 to 2 gallons per diem
in boilers, say of 125 horse power, when pushed to their capacity in
evaporating water.
The result of careful experiments justifies the use of kerosene, the
scale being less than in four years’ previous experience, and a large
portion of the boiler showing the clean black steel, in as apparently
good condition as when new.
Despite the small quantity of kerosene used in the boilers in this
case, the odor was perceptible by opening an air valve to any steam
radiator in any of the buildings. When as much as a gallon per week was
used, the odor was very strong, but with one half that amount it was
hardly perceptible, and only to be noticed when an air valve had been
open a long time. And since commencing to use the oil a much greater
deposit of rust scales than usual has been found in the various steam
traps in the buildings, indicating that the oil is also exerting a
cleansing influence on the pipes of the whole system.
NOTE.—Provision must be made for the removal of the scale as it drops
from the internal surfaces of the boiler, as at times many bushels of
it have been deposited directly over the furnace; hence, if a boiler
is known to be badly incrusted, the kerosene should not be put in the
first time more than three days before it is intended to wash the
boiler.
NOTE 2.—The safety valve should be opened to allow the escape of the
gas arising from the kerosene before cleaning out the boiler; where a
lighted lamp or candle is used, as it must necessarily be—indeed this
is a precaution which ought always to be observed in all cases, viz.,
properly to ventilate boilers, heaters, and tanks of all descriptions
before entering them with lighted lamps and torches. While these gases
are not likely to cause an explosion, they burn quite rapidly and
should be promptly removed without giving opportunity for an accident.
The accumulation of gas is not confined to the use of kerosene oil for
the prevention of scale in steam boilers, but is also found in flour
mills, confectioners’, conduits for electric wires, brewers’ vats,
etc. So, with common sense precautions, no extra risk is run in using
kerosene oil in steam boilers.