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AIR LIFT PUMPING AND WATER PURIFICATION 1
By John Oliphant 2
This paper is not written to discuss the principles of air-lift pump-
ing, but it is advisable to call attention at the outset to the necessity,
if success is to be attained, of choosing correctly the diameters of the
water and air pipes for different lifts and submergences, and of
obtaining a complete, intimate mixture of the air and water at the
foot piece. If an air lift plant is properly designed and constructed
it furnishes water continuously without interruption for a long
period. For example, at Maywood, a suburb of Chicago, there is
an air lift plant furnishing 700 gallons per minute from a single well,
with a lift of over 300 feet. The compressor has been running
twenty-four hours daily for four years, without other interruption
than a stop of a few minutes each day for examination and occa-
sionally for some adjustment. There has been no expense whatever
for repairs.
There are occasions where the air lift can be used as an auxiliary
to a high duty suction plant pumping from deep wells, as at Clinton,
111., something over a year ago. There the water is obtained by
suction from deep wells. For ordinary purposes a sufficient amount
is delivered by this method, but for peak loads in the summer and
in case of fire the supply was not sufficient. The water is drawn
from half a dozen wells having a surface flow of limited volume.
These are connected so as to flow into a surface reservoir, or may
be direct-connected to the mains by means of suction pumps.
In order to be able to meet the heavy drafts, three of the wells
were connected with the air lift system arranged to discharge into
the reservoir, using the suction piping as a gravity flow line. One
of the 8-inch wells had a natural artesian flow of about 150 gallons
per minute. When under suction from the pumps, the pull-down
was 20 feet, increasing the flow to 500 gallons per minute. With
1 Condensed from a paper presented at the Buffalo convention, June 10,
1919.
1 With Sullivan Machinery Company, Chicago, 111.
212
AIB LIFT PUMPING AND WATER PURIFICATION 213
the air lift, its production was increased to 1035 gallons per minute,
the pumping head being 50 feet below the surface. The other two
wells, connected up in the same manner, showed a proportionate
increase.
The efficiency of the air lift when operating under heavy lifts is
illustrated by table 1, giving the results of two tests made at Gales-
burg, 111., on plants installed by the author. One plant has been in
operation for a year and the other about six months. Formerly
the public supply was drawn from three deep and six shallow wells,
with a combined yield of about 250 gallons per minute. This plant
was expensive to operate. It was therefore decided to sink a new
well, which furnished 450 gallons per minute, which was so satis-
factory that a second well was sunk in another part of the city,
which furnished 650 gallons per minute.
Well 1 was cased with 40 feet of 24-inch heavy steel casing, 106
feet of 20-inch, 130 feet of 16-inch, and 350 feet of 12-inch, the last
being sealed into the rock. A 12-inch hole was then drilled to a
depth of 1085 feet from the surface, where the diameter was reduced
to 10 inches and the drilling continued, through the St. Peter's
sandstone, to a depth of 1255 feet. It was then shot with two 200-
pound charges of 100 per cent gelatin, covering the entire sandstone
stratum, and cleaned out carefully. Ten-inch wrought iron pipe
was next sealed into the top of the 12-inch pipe about 350 feet below
the ground surface; this extends to within 3 feet of the top of the
sandstone and keeps out of the well all water from strata over-
lying the St. Peter's formation. The air lift delivers the water into
a small surface reservoir from which it is pumped into the mains
under 40 pounds pressure by a centrifugal pump. On account of
the heavy lift, an auxiliary starting device was installed at a depth
of 481 feet, 8 inches.
The main features of the second well are also shown in table 1,
from which it will be seen that this equipment also included an
auxiliary starting device.
There is one feature of pumping water by the air lift which gives
it special advantages where it is desirable to eliminate certain sub-
stances like sulphates or carbonates of iron which are in solution.
When the air is thoroughly mixed with the water, the latter is
aerated and certain of its undesirable constituents are thereby
oxidized into forms which can be removed by filtration.
214
JOHN OLIPHANT
Carbonates of iron are more susceptible to treatment in this
manner than are sulphates of iron. With the latter the water will
probably need preliminary sedimentation before it goes to the niters
and a small dose of lime may be needed to accelerate the sedimentation.
There are various methods of arranging the parts of one of these
combined lifting and purification plants. The air lift may merely
TABLE 1
Results of tests of air lift installations in two wells at Galesburg, III.
Depth of well
Diameter of well
Diameter of well
Diameter of well
Diameter of well
Diameter of well
Water pipe in well
Water pipe in well
Water pipe in well
Main air line
Auxiliary air line
Static head from ground
Drop during pumping
Elevation above surface of outlet....
Total lift
Operating submergence
Percentage of submergence
Depth of pump in well
Operating pressure
Starting pressure with auxiliary
Discharge per minute
Free air used per minute
Revolutions of compressor per minute
Water horse power
Operating air horse power
Estimated efficiency
WELL 1
WELL 2
1252 ft.
1245 ft.
40 ft. of 24-in.
360 ft. of 15 in.
106 ft. of 20-in.
230 ft. of 14i in.
130 ft. of 16-in.
635 ft. of 13$ in.
809 ft. of 12-in.
170 ft. of 10-in.
235 ft. of 5-in.
204 ft. of 8-in.
331 ft. of 6-in.
213 ft. of 7-in.
190 ft. of 6-in.
331 ft. of 2|-in.
600 ft. of 3-in.
490 ft. of li-in.
500 ft. of lj-in.
186 ft.
190 ft.
118 ft.
157 ft.
7 ft.
7 ft.
311 ft.
354 ft.
262 ft.
253 ft.
45.8 per cent
41.75 per cent
566 ft.
600 ft.
121 pounds
115 pounds
149 pounds
135 pounds
450 gallons
650 gallons
450 cubic ft.
719 cubic ft.
179
214
35.5
58.2
94
148
37§ per cent
39.3
discharge water from a well into the sedimentation basin of a purifi-
cation plant from which it is pumped in the usual way. If the well
is deep enough to give the necessary submergence and other con-
ditions are right, the air lift can be arranged to lift the water into
an elevated tank, which will also serve as a sedimentation basin,
from which the water will pass by gravity through a pressure filter
AIR LIFT PUMPING AND WATER PURIFICATION 215
into the water distribution mains. A third arrangement that is
practicable under some conditions is to place the pressure filter in
the line between the well and the elevated tank.
The practicability of using the air lift for installations like the
last two is sometimes overlooked. They are not always possible,
for the operating conditions must be right to enable them to be
used satisfactorily. In the boosters generally used in these instal-
lations, the water discharged from the well is brought to a complete
stop by striking what is called an umbrella separator in the booster.
This throws the water to the bottom of the booster and allows the
air to escape from the top. Nevertheless, owing to the intimate
mixture of the air and water, which resembles an emulsion in appear-
ance, considerable air is carried by the water discharged from the
booster. While this air is beneficial, on account of its aerating
properties, in the purification of the water, it is detrimental if the
booster delivers water to long horizontal pipe lines, because the air
will form pockets at high points. It is also detrimental where the
water goes directly to pumps or condensers. Where such operating
conditions exist the air must be removed by a separator.
THE CYCLONE SEPARATOR
In order to overcome the difficulties of carrying air over into
long pipes because of complete emulsion and to insure perfect sep-
aration of the air and water, a special separator has been designed,
consisting of a simple shell or cylinder with top and bottom. The
combined air and water is discharged into the top and at one side
at a tangent to the periphery, under high velocity from the well,
causing it to swirl, effecting in this way a perfect separation of the
air and water, the water leaving the separator from an outlet at
the bottom tangent to the periphery and the air passing off at the
top. The downward centrifugal action completely separates the air
from the water, leaving the air quite dry and freeing the water
entirely from air bubbles.