Surface Machinery and Methods for Oil-Well Pumping

16 SURFACE MACHINERY AND METHODS FOR OIL-WELL PUMPING.
to radiation from the boiler shell. Oil-field boiler efficiency has been
discussed by Bureau of Mines engineers.4
As the temperature of the furnace gases can not be reduced below
the steam temperature of the boiler, much initial heat is unavoidably
lost. Tests of different sizes and types of boilers with different kinds
of fuel indicate a combined (or over-all) furnace and boiler efficiency
ranging from 30 to 80 per cent, but averaging for larger power plants
above 70 per cent. Tests 5 have shown that in oil-field practice the
boiler efficiency of many locomotive and return tubular boilers with
oil or gas fuel does not exceed 50 per cent; but with improved set-
ting, properly regulated burners, and proper care of plant, these
same boilers show an efficiency of 70 per cent.
Losses characteristic of the fuel itself are, with coal, due to un-
burned pieces dropping into the ashpit, and the slacking of coal in
storage bins; with fuel oil, tank leakage; and with gas, leakage in
gas lines.
Suitable burners are important for the efficient use of oil and gas as
a fuel, as are the size and shape of the fire box. When coal is the fuel
most of it burns slowly on the grates, and efficient combustion de-
pends largely upon adequate grate area. When oil or gas is the fuel
it burns quickly as a vapor or as a gas, and efficient combustion de-
pends on adequate combustion space.
In respect to fuel economy, the boiler is the most important part
of the power plant, and is responsible for the largest part of the
operating expenses.
COAL AND WOOD AS FUELS.
Coal is not much used in the oil fields, except at some central
power plants where it is cheaper than fuel oil or natural gas. Wood
has been used for years in some of the older, heavily timbered, Penn-
sylvania oil fields, where the gas supply is depleted and wood can be
obtained near by at the cost of cutting.
The grates for burning wood or coal in locomotive and return
tubular boilers in the oil fields have cast-iron bars side by side in the
fire box or furnace; the thickness of the lugs cast on the bars deter-
mines the width of the air spaces. For larger boiler plants, shaking
grates have been designed to permit cleaning the fire without opening
the door.
For central power stations burning coal, mechanical or automatic
stokers have come into general use. In one of the common types the
grate is a horizontal endless chain of short iron bars that moves over
sprockets at each end. The coal is fed from a hopper in front of the
'Brewer, G. S., Youker, M. P., and Beecher, C. E., The use of low-pressure gas burn-
ers in oil-field boilers: The Mid-Continent Year Book, 1921, pp 77-121.
Tourtellotte, W. B., Tests on oil field boilers. Union Oil Co., 1919, 40 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 September 1, 2014.