14 SURFACE MACHINERY AND METHODS FOR OIL-WELL PUMPING.
the feed water has been opened. The water is subjected to the full
boiler pressure and quickly flows into the boiler because of its hydro-
static head. Contact with the live steam will heat the water con-
siderably. When the vessel has been drained, the valves in the steam
and feed-water lines are closed, and that in the water-supply pipe is
reopened. Automatic regulation of gravity feed is often used and
works satisfactorily. Gravity feed is common in oil fields in the
hilly parts of Pennsylvania and West Virginia.
Some small power plants use a boiler feed pump of simple design,
attached to the steam engine and worked directly from the engine
crosshead. This pump circulates water through a coil placed in the
steam-engine exhaust pipe, and heats it before forcing it into the
BOILER FEED WATER AND ITS TREATMENT.
In many of the oil fields of California, Wyoming, Kansas, Okla-
homa, Texas, and Illinois suitable boiler feed water is hard to obtain.
Rain water is often collected in ponds and used instead of well water.
A condensing system helps to conserve the supply of good boiler feed
water. Certain waters should never be used for boiler feed, because
no treatment can make them suitable. All of the scale-forming
salts in the water forced into the boilers will ultimately be deposited,
regardless of the rate at which steam is generated. However, a
badly scaled boiler that would blister if operated at high rates might
be safe at a lower rate, although its efficiency would be low.
Poor feed water may cause scale, foaming, priming, and corrosion.
A Bureau of Mines publication 3 discusses boiler-water treatment and
covers the nature and origin of scale-forming ingredients in boiler
water, the effect of scale and methods of removing scale formers from
water, and gives some examples of economies effected by softening
FUELS AND COMBUSTION.
EFFICIENCY OF DIFFERENT FUELS.
An average bituminous coal yields 13,500 B. t. u. to the pound,
or 27,000,000 B. t. u. to the ton; 27,000,000 divided by 33.479 equals
806.5 b. hp. With a boiler efficiency of 65 per cent this would be
524.2 effective b. hp.
An average petroleum or fuel oil yields 19,500 B. t. u. to the
pound. An oil of 16 B. weighs approximately 8 pounds to the
gallon, or 336 pounds to the barrel of 42 gallons, and 1 barrel of
this oil would produce 336 times 19,500 or 6,552,000 B. t. u.; 6,552,000
3 United States Fuel Administration, Boiler water treatment: Tech. Paper 218, Bureau
of \Mines, 1919, 8 pp.
George, H. C. Surface Machinery and Methods for Oil-Well Pumping. Washington D.C.. UNT Digital Library. http://digital.library.unt.edu/ark:/67531/metadc12407/. Accessed July 4, 2015.