TM 5-810-15
Example:
Input-MB/hr
Effcy.
Load
Fuel Cost
Fuel Cost
Increase
Factor
Dollars
Savings
x Percent
x Hours/year
x Per MB
= Per Year
Economizer
140
x 0.06
x 7,000
x 2.00
= 7,600
example*
*Example assumes 100,000 lb/hr capacity, 140 MB/hr full load input, 6 percent efficiency increase with economizer, fuel cost
.00/MB, and MB = Million Btu*s.
Refer to figure 3-15 for fuel savings based on
related system. The cost of water treatment for the
reduction of exit or flue gas temperature. Normally
steam consumption by the sootblowers is an evalu-
an economizer is less costly and requires less space
ation factor.
f. Boiler casing or setting. The boiler casing or
than an air heater.
e. Sootblowers. Sootblowers are used on all
setting is the most visible component of the unit
heavy oil and coal fired boilers to clean ash
and if not properly designed may be the source of
deposits from furnace, boiler and superheater sur-
excessive maintenance costs and loss of boiler
faces in addition to economizers and air heaters.
efficiency.
Sootblowers will be spaced as specified by the
(1) The term boiler setting was originally
boiler manufacturer to maintain unit efficiency and
applied to the brick walls enclosing the furnace and
prevent coal ash pluggage. Ash deposits on the
heating surfaces of the boiler. Since the boiler
tubes may bridge the space between tubes unless
settings and casing have been the source of a large
stopped before such pluggage occurs. Soot-
portion of boiler related maintenance and operating
blowers are used to keep the tubes clean in order to
(heat loss) costs, a great deal of attention and
maintain tube cleanliness and hence efficiency.
improvements have taken place. This is particularly
(1) Sootblowers may be either steam or air
true of the recent past during which time boilers
blowing.
became so large that heat losses and maintenance
(2) Unless water scarcity is an overriding
costs would have been totally unacceptable. As the
factor, only steam should be used due to capital
technology of water treatment plus boiler design
and operating costs of an air compressor and its
and manufacturing improved, water cooled furnace
3-23
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