MIL-HDBK-1003/6
Oxygen in air is equal to 21
5.3.2.2
Air Required per 100 Pounds of Coal.
percent by volume, therefore:
b.mol Air
x
(100 lb.mol Air)
(8.55 lb.mol O2)
=
41.00 l
(21 lb.mol O2)
One lb.mol of air is equivalent to 29 lbs.
The total air required
for 100 lbs coal is:
ir/100 lb Coal
(29 lbs)
(41 lb.mol Air) x
=
1189 lbs A
(lb.mol Air)
Products of Combustion. The weight of the gaseous products leaving
5.3.3
the boiler stack, assuming complete combustion of the coal used in the above
example, is equal to the weight of the fuel less the ash content plus the
weight of total air required.
Net weight of fuel
100 lbs
Less ash content
9 lbs
Total combustibles
91 lbs
Weight of combustibles
91 lbs
Weight of air
1189 lbs
Total gaseous products (flue gas)
1280 lbs
5.4
Fuel and Ash Handling
5.4.1
Coal
5.4.1.1
Coal Delivery. The total cost, reliability of supply, and
uniformity of the properties of coal as received by the consumer are effected
by the distance shipped and the means of transportation used. In the United
States, coal is transported mainly by barge, rail, and truck. This accounts
for up to 75 percent of delivered coal cost. Transportation effects the as-
received condition of the coal. Factors affected by transportation are
freezing in transit, changing moisture content, or size degradation.
a) Barge Delivery. Transportation by barge is the most economical
over long distances. The main drawback of this type of transport is its
inflexibility. Plants must be located on or near waterways large enough to
receive barges which can carry from 1,000 to 1,500 tons (907 000 to
1 360 500 kg) of coal. Coal delivered by barge is often off-loaded by
clamshell bucket to conveyor systems for movement to storage areas.
b) Railroad Car Delivery. Coal is transported by rail in cars
ranging from 50 to 100 tons (45 350 to 90 700 kg) with an effective range from
500 to 800 miles (805 to 1 288 km) along established railways. This method of
delivery is very slow and inflexible. Although rail delivery costs may exceed
the cost of coal at the mine, it is the best available option for many areas
without waterway access. Additional equipment needed for rail delivery may
include thawing equipment, car pullers and scales, and special unloading
hoppers.
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