APPLICATION SYSTEMS ENGINEERING
Boiler Feedwater, Condensate Return & Make-up Water
A Boiler System is comprised of two main sub-systems:
The furnace, which provides heat to create steam from
the boiler water & the boiler vessels,
tubing & transfer devices, which control & deliver the steam to process
users. Water quality control is
of primary importance to minimize expensive equipment damage & loss of
efficiency. Critical attributes
of boiler feedwater, condensate return & make-up water are summarized
below & in reference documentation.
Actual operating pressure of the steam has a major influence on
the water quality required to minimize damage.
Detailed system analysis is needed on each application, in order
to determine an optimum analytical system.
Boiler feedwater is normally
obtained from treated natural waters, which contain TOC, carbon dioxide,
dissolved oxygen, oily matter, suspended solids, dissolved solids, iron,
silica, sodium, salts & a variety of other impurities.
Organics, Hydrogen Sulfide & Dissolved Oxygen are major
contributors to corrosion.
Organics form organic acids, cause foaming & clogging.
Sulfates, Chlorides, Bicarbonates & Nitrates are formed &
result in unacceptable scaling if feedwater hardness is not strictly
controlled. Make-up water
is obtained from condensate return & treated natural waters.
Liquid water on the boiler bottom collects all the impurities
“flashed out” of the steam in droplets formed in the process, & must be
periodically “Blown-Down” (released to drain).