22 SURFACE MACHINERY AND METHODS FOR OIL-WELL PUMPING.
With enough gas and proper plant design, the failure of natural-
gas burners can usually be traced to leaks, pipes too small and with
too many bends, gas pipes clogged by dirt or corrosion, burner im-
properly installed or operated, burner too small for the work re-
quired, and burner poorly designed or unsuitable for the pressure
used. The most common defect is deficient mixing of the air and
gas; that is, not enough air to complete combustion, or excess air
that passes through the boiler without combustion.
Many engineers claim higher efficiencies with combustion of high
pressure gas than with low pressure gas. The use of high-pressure
gas burners has been discussed by J. S. S. Brame.8
Steam engines and boilers were the only source of mechanical
power in oil fields for many years. The horizontal single-cylinder
slide-valve steam engine is still the chief source of power for drilling
oil wells. For this purpose it is made in sizes from a cylinder with
a 9-inch diameter and a 12-inch stroke and a rating of 15 horsepower
to a. 16 by 16 inch cylinder with a rating of 70 horsepower. It is
noncondensing, of simple design, and strongly built for the severe
service of the oil fields. Formerly the steam engine used in drilling
on the "block " was also used to pump the completed well. Many
such engines are found in the oil fields, frequently at some well
where they are used for " pulling " or cleaning long after another
method of pumping has been adopted.
Vertical slide-valve engines are often seen in the oil fields mounted
as part of a portable steam drilling-machine. Several of the oil-
well supply companies manufacture double-cylinder slide-valve en-
gines for the European oil fields.
Steam engines are also classified as single expansion and multiple
expansion. In the former the steam expands and does all of its
work in one cylinder as in the oil-field drilling engine. The multiple-
cylinder type is classified as a compound engine when there is both
a high-pressure and a low-pressure cylinder, the engine doing part of
its work by a partial expansion of the steam in the smaller high-
pressure cylinder and completing the expansion and work in the
larger low-pressure cylinder.
Steam engines are further classified as slide valve, Corliss valve,
piston valve, and poppet valve. The slide valve is the simplest type
of valve and uses the most steam with the lowest efficiency. It is gen-
erally suited for small or medium size engines for high speeds. The
Corliss valve has long been used in large steam engines, such as those
at central power plants, but it is not well suited to small, high-
8 Bramne, J. S. S., Fuel, solid, liquid, and gaseous. London, 1917, 372 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 30, 2016.