Page 273 - Boiler_Operators_Handbook,_Second_Edition

258 Boiler Operator’s Handbook

will have some meaning and you can use it to estimate not routed through the pretreatment equipment such as
the effect of chemical additions. Don’t forget about the softeners. Condensate will also contain iron, copper, and
complication with pH being steps of ten. other metals from corrosion of the steam and condensate
There are basically four sources for the chemicals piping. It’s also possible to receive water contaminated
that are in your boiler system’s water, makeup, corro- by some operation in the facility. I’ve seen or heard of
sion, leaks, and treatment. In order to effectively control boilers filled with fuel oil, sand, salt, sugar, and milk to
your water treatment you need to be able to determine name a few. A boiler plant operator has to know a little
where the chemicals came from. The principal source is bit about the facility served to be aware of the potential
the makeup and it’s a function of the quality of the water for such contamination and to watch out for it.
you get from the well, river, city water main or wherever One odd one was a boiler contaminated with soft-
it comes from. You have to test that water to know how ener resin. It formed a hard, baked on coating over all
much it’s capable of adding to the chemical burden of the boiler tubes where the resin hit the tubes and melted
your boiler water and how to treat it. on. The operators found one of the strainers in the soft-
Testing that water for hardness provides an indi- ener had broken off allowing the resin to leave with the
cation of the required frequency of regeneration of the treated water.
water softeners. Tests for bicarbonates or TDS provide Water that’s passed through a piece of pretreat-
indications for other ion exchange equipment and bleed ment equipment has to be tested to ensure the equip-
requirements for reverse osmosis systems. When you’re ment is operating properly. Some of the tests are only
using well or river water you may also need to test the significant at specific stages of the system operation. For
water for suspended solids to determine the loading of example, testing of the output of a water softener near
water filters. the end of the run is critical to make certain the resin has
In the Baltimore metropolitan area we have a con- not deteriorated to the degree that hardness is bleeding
cern for the source of the city water. Most of the time our through. Some tests have to be combined with analysis
water is drawn from reservoirs filled by surface runoff of chemical use; if you find yourself using more sulfite
in the northern part of the state but during periods of than normal it’s an indication of problems with the de-
drought or when work is performed at the reservoirs aerator.
the city switches from that source to the Susquehanna Of course only you are aware of operations that
River. Some of the water in the Susquehanna has trav- affect that chemical use; I remember dismantling a de-
eled from as far away as New York State and most of aerator to find nothing wrong based on a consultant’s
it’s from Pennsylvania so it’s spent a lot of time flow- analysis. The consultant didn’t know about a complete
ing over rocks and dissolving them. The TDS levels of plant shutdown and draining and refilling of the boil-
the Susquehanna River are substantially higher than ers using a tank truck. Since the water was exposed to
those of the reservoir water and adjustments in softener air the sulfite was consumed but all the other chemicals
throughput are essential to make sure all the hardness is were recovered.
removed. Also, blowdown has to be increased to com- Reverse osmosis and blowdown reduces the con-
pensate for the heavier solids loading. Regular daily centration of ions in the boiler water but it doesn’t elimi-
testing of that raw city water is essential because they nate them completely. Softeners and other ion exchange
don’t always tell us when they make the switch. equipment, except hydrogen softeners and demineral-
Your softener’s capacity is based on hardness re- izers, swap ions replacing those that produce difficulties
moved so testing the hardness and recording the meter with ones that are not as damaging.
give you a clue. If the hardness of the makeup is 50 ppm They don’t get every bad ion out. By maintain-
and the softener is set to regenerate after 20,000 gallons ing a certain amount of special chemicals dissolved in
you’ll have to reset the meter for 10,000 gallons when the boiler water we provide for the final demise of the
the hardness increases to 100 ppm. Stick with the ratios nasty ions and any oxygen that may have managed to
to avoid all those kilograin calculations. As the resin sneak past all our pretreatment equipment. We say we
deteriorates, which you detect by noting some hardness have a “residual” of water treatment chemicals in the
increase at the end of the softener run, you should adjust water. They reside there, waiting to pounce on any scale
the meter setting accordingly. forming ions or oxygen that gets through before they
Testing condensate can identify leaks into the sys- can damage our boiler. Another reason we maintain a
tem. A common source is steam heated service water residual is that we can measure it. If it’s there so we can
heaters and that’s always a concern because the water is find it with a chemical water test, we know it’s there to