25 May 2005
How does one balance chemical treatment levels and COC?
COC is controlled through blowdown. Blowdown is often measured by
maintaining conductivity or TDS within a specific control range. Chemical
treatment levels are controlled by the chemical feed rate into the boiler and by
blowdown. It is best to maintain consistent control of COC first, followed by
proper adjustment of chemical feed rates. If there is a sudden change in
chemical treatment levels without any changes in blowdown or chemical feed
rates, then there is likely to be a change in feedwater quality (e.g., change in
condensate return rate, hardness excursion, poor deaerator operation).
Are boiler water treatment chemicals safe to work with?
Yes, provided the directions on the MSDS sheets are followed. The highest
hazard is due to chemical burns from highly caustic substances.
Why is it impossible to get all the parameters (e.g., alkalinity, TDS) in the control
It is not impossible as long as the control ranges are proper for a given boiler
operation. The first parameter to control is COC. Maximum cycles are limited by
some parameter (i.e., alkalinity, TDS, silica, carryover). Any one of these can be
the limiting factor for COC. Once proper cycles are established, chemical
treatment feed rates should be adjusted to keep levels within control ranges.
Q10. The softeners need to be regenerated more often than before. What could be the
A10. The problem could be one of many things. It usually is due to higher demands for
makeup water. It could, however, be due to an increase in makeup water
hardness levels or a deficiency in regeneration. Deficiencies in regeneration can
be due to insufficient brine strength, insufficient brine time, inadequate backwash
resulting in channeling, lost or cracked resin, and heavily fouled resin due to iron.