Transactions A.S.M.E.

644 TRANSACTIONS OF THE A.S.M.E. NOVEMBER, 1940
Transportation cost, reliability of the carrier or carrier system,
and the continuity of supply are important factors when coal or
fuel oil are considered.
The increasing availability of natural gas has encouraged the
extension of pipe lines so that now it may be so conveyed thousands
of miles from the source of supply to the ultimate consumer.
Anthracite destined for eastern markets generally moves via
rail, or rail and tidewater, with a small portion moving via truck.
S e l e c t i o n a n d E v a l u a t io n o p F u e l
Purchasers of fuel are anxious to familiarize themselves with
the limitations of their own equipment, the operating man’s viewpoint,
and the characteristics of available fuels. They desire some
readily understood measure of fuel evaluation and performance,
first, to guide them in its selection and, subsequently, to check
actual performance when the fuel is burned in their own plants.
A suitable measure of performance will facilitate comparison
between plants and between competing fuels in the same plant,
also the effect of variations in preparation and physical characteristics
upon the efficiency of utilization.
A vast amount of detailed information and individual plantoperating
experience has been accumulated and made available
by the engineering profession and by producer and consumer
organizations as to available fuels. Nevertheless, the major
problem still remains.
A scientific approach to the purchase of fuel is possible. Frequently,
however, the power or fuel portion of the total manufacturing
cost is not sufficiently large to justify the extensive and
detailed evaluation methods used by those who consume millions
of tons annually. However, the many chemical and physical
characteristics of fuels undoubtedly do have a marked bearing
upon the selection of appropriate fuels and, having once determined
the desired type or types, the field is considerably narrowed.
It then becomes a m atter of evaluating fuels on the basis
T A B L E 7
SU G G E S T E D M E T H O D O F E V A L U A T IN G FU E L S
of actual heat recovery rather than on a casual analysis of a
salesman.
Coal is now available in a greater variety of sizes and grades
than is generally realized. The producers themselves have
learned to better prepare, size, grade, and treat their coals;
fuel oils have increased in specific gravity and heat content;
refinery by-products and residues have become available; and
the extension of natural-gas lines has brought this fuel into
many otherwise inaccessible markets. Combustion equipment
has been designed or modified to permit high rates of heat release
and to burn not only one but several fuels with substantially
equal facility. The fuel-selection problem thus has become increasingly
complex.
The average consumer is manifestly somewhat bewildered by
the kaleidoscopic changes in fuel prices, fuel markets, and factors
affecting fuel production, distribution, and use. His interest in
the evaluation of fuels leans toward a definite, tangible yardstick
or measure of evaluation and a definite departure from the old
rule-of-thumb method of purchase from “Smith” or “Brown,”
because the fireman thought it burned better or merely because
the supplier had convinced the fireman that his coal shoveled
better than that of his competitor.
The suggested method of evaluation is illustrated in Table 7
for coal, gas, and oil, and for stoker- and pulverized-fuel-fired
boilers.
The variable factors, production, transportation, handling,
and utilization, may be divided into two fundamental and
essential groups as follows:
1 The complete cost of the fuel, including transportation and
conversion, per ton, barrel, or million cubic feet.
2 The heat recovery expressed in convenient units, as, for
example, million Btu per fuel unit.
Both of these in the average industrial plant may be readily
and accurately determined. When compared, they provide a
simple and substantially uniform and sufficiently accurate
method of evaluation regardless of the fuel, the conversion equipment,
the method of operation, plant location, or any other of the
many factors which enter into or effect the utilization of fuel.
After the primary determinations, supplemented by a heat
balance if desired, fuel evaluations are completed for repreeentar
tive fuels and the usual boiler ratings. Subsequent modification
may be quickly approximated to determine the effect of changes in
prices, transportation costs, and operating efficiencies. Thereafter,
periodic tests and an analysis of the results over extended
periods may suggest further changes in fuels and conversion
equipment and make possible the widening of the range of fuel
application. Thus, the management and operating staff are
provided with a yardstick or standard of performance which can
be easily and readily applied to a large or a small plant, and
which includes all the essential fundamental factors. To illustrate,
if we add the following items:
A The delivered cost of fuel, including storage and handling
if necessary;
B Cost of handling the fuel into and through the conversion
equipment;
C Ash- and waste-removal cost;
D Supervision, labor, maintenance, and other operating
expense;
then we can readily determine, from these known and easily
secured data, a unit cost for fuel delivered and consumed.
Actual heat recovery may be readily ascertained from the
steam produced or an equivalent-use evaluation in other processes.
The two predominating and major factors may then be