UFC 3-240-13FN
25 May 2005
Figure 3-8. Failed Boiler Tube
3-1.4.3
Carryover Problems. Carryover problems are caused by misting,
foaming, priming, and silica carryover (see paragraph 3-2.8). Carryover is a process
that results in impure steam quality. Dissolved solids contained in the carryover material
can contribute to corrosion and deposition problems.
3-1.5
Calculations. To understand and produce efficient boiler operations,
boiler calculations are performed and the results applied correctly. Boiler calculations
are the means for providing information used to determine optimal blowdown rates and
to assess condensate return. The greatest efficiency of boiler operations can be
achieved by optimizing the COC by adjusting the amount of blowdown to give the
proper volume of water. Efficient boiler operations recover and return as much
condensate as possible. The material balance or mass balance of an operating boiler
system can be calculated from the results of water tests and the known (measured)
value of a single boiler operational parameter such as steam production, makeup water
usage, feedwater usage, or blowdown. Steam table data can be used with mass
balance information to calculate energy input and energy output for the boiler system.
Chemical feed rates can be used with mass balance information to develop an
estimation tool for the annual consumption of water treatment chemicals. Familiarity
with these calculation procedures and their application to boiler system operations
assessment is required of any base or facility engineer or section supervisor. This
knowledge is also useful for boiler operators. Examples of boiler calculations are
provided in paragraphs 3-1.5.3 through 3-1.6.3.
3-1.5.1
Cycles of Concentration (COC). COC in a steam boiler is a term that
refers to the number of times the minerals in the feedwater have been concentrated in
the boiler by its operation. As boiler water is evaporated and steam is produced,
minerals that were dissolved in the boiler water remain behind, increasing the mineral
41
Previous Page
