The Coolidge examiner., 1941-06-20

III 10 IlOW ulSCIldI I SlIlS CllOuS II
cause undue wear to cylinders.
An idea of the minutely fine ad-
justment of the cylinders can only
be obtained by comparison. A
strand of human hair is approx
mately three one-thousandths of an
inch thick; certain parts used in
connection with the fuel system of
the big engines are fitted, by
measurement, to one hundred
thousandths of an inch, too small
for the eye to perceive without
aid of strong magnifying glass.
Tools for adjusting these engines
range from feeler gauges of
infinitesimal thickness, to enorm-
our hammers and wrenches requir-
ing from five to seven men to use,
some holding, some stricking.
When the plant is in full opera
tiOn approximately two carloads of
fuel oil and the same amount in
power relation of natural gas is
used weekly.
New emergency parts have been
ordered for the egines as required
and it is estimated that at least
two more months will be needed
to finish the work.
Engine number is a Nordberg,
S-cyl. 21x29-in., 2 cycle, cross head
unit, direct connected to 225-rpm,
24O0-volt,. 3-phase, 60 cycle, $500
kva generator. Fiat valves COLI
troll scavenging, and Roots-Con
nersville positivedisplacement
blower, gear driven from the en-
gine shaft, furnishes scavenging
air. Intake air enters through an
automatic filter.
Separate soft and raw water
systems cool the engine. The soft
water circuit includes the engine
Jackets, circulating pumps, and
heat exchangers; a surge tank, in
the building roof structure, takes
care of changes in volume, but
there is no circulation through the
surge tank. Elimination of an
open sump in the soft-water sys
tenn avoids constant head loss due
to differences in elevation of
sump and engine; the entire soft
water circulating-pump load con-
sists of hydraulic friction. All
makeup for the soft-water system
comes from a water softener.
The raw water circuit includes
heat exchangers, circulating pumps
and a cooling tower. Relative
hardness of raw water necessi-
tates frequent cleaning of the heat
exchangers. Presence of fine
wind-borne dust, almost colloidal
in nature, which is deposited in
the cooling-tower sump, further
complicates cleaning. Operators
now successfully clean the sump,
without interfering with tower op-
GRAFTON, by using a small pump
fitted with a suction hose and
nozzle like that of vacuum clean
er.
A shaft driven pump continu-
Ously circulates lubricating oil
through a cooler; an. auxiliary
mOtor-driven pump stands for
starting-up and emergencies. A
centrifuge continuously conditions
a portion of the lube oil by means
of partial bypass.
The fuel system for operating
On oil is conventional solid-injec-
tion. Nozzles are water-cooled.
Since a high degree of reliability
and long runs without shutdown
are required by the nature of the
operation, it has been found de-
slrable to use a completely distill-
ed fuel.
In this engine it is necessary to
add pilot oil = that is, inject
spray of oil with each charge of
gas. This oil apparently controls
the flame propagation and insures
burning instead of detonation.
On June l, 1889, the engine
started initially, On oil, a shake
down run and a 60-hour full-load
run followed, with formal accept
ance tests on June "a. The en-
gine was then changed to gas and
first run On June 26th. After a
shake-down run on gas, formal ac-
ceptance tests were made on July
and and regular operation was
started July 8th.
From August to November in
elusive, the engine ran 96.4% of
the time at 1920 rated load. While
all recognized such operation was
not desirable project funds were
low, water storage in the reservoir
was inadequate, and it was neces-
sary during this period to purchase
| 2,353,000 kwhr from outside sourc-
es. 1t was, therefore, imperative
to secure maximum production.