Page 226 - Handbook of Energy Engineering Calculations

(28,577 L/day). In 7 days the engines will use (7 days)(7550 gal/day) =
52,900, say 53,000 gal (200,605 L).

2. Select the tank capacity
The actual fuel consumption is 53,000 gal (200,605 L) in 7 days. If fuel is
delivered exactly on time every 7 days, a fuel-tank capacity of 53,000 gal

(200,605 L) would be adequate. However, bad weather, transit failures,
strikes, or other unpredictable incidents may delay delivery. Therefore, added
capacity must be provided to prevent engine stoppage because of an
inadequate fuel supply.

Where sufficient space is available, and local regulations do not restrict the
storage capacity installed, use double the required capacity. The reason is that
the additional storage capacity is relatively cheap compared with the
advantages gained. Where space or storage capacity is restricted, use 1½

times the required capacity.
Assuming double capacity is used in this plant, the total storage capacity
will be (2)(53,000) = 106,000 gal (401,210 L). At least two tanks should be
used, to permit cleaning of one without interrupting engine operation.

Consult the National Board of Fire Underwriters bulletin Storage Tanks for
Flammable Liquids for rules governing tank materials, location, spacing, and
fire-protection devices. Refer to a tank capacity table to determine the
required tank diameter and length or height depending on whether the tank is

horizontal or vertical. Thus, the Buffalo Tank Corporation Handbook shows
that a 16.5-ft (5.0-m) diameter 33.5-ft (10.2-m) long horizontal tank will hold
53,600 gal (202,876 L) when full. Two tanks of this size would provide the
desired capacity. Alternatively, a 35-ft (10.7-m) diameter 7.5-ft (2.3-m) high

vertical tank will hold 54,000 gal (204,390 L) when full. Two tanks of this
size would provide the desired capacity.
Where a tank capacity table is not available, compute the capacity of a
2
cylindrical tank from capacity = 5.87D L, where D = tank diameter, ft; L =
tank length or height, ft. Consult the NBFU or the tank manufacturer for the
required tank wall thickness and vent size.

3. Select the day-tank capacity
Day tanks supply filtered fuel to an engine. The day tank is usually located in

the engine room and holds enough fuel for a 4- to 8-hour operation of an