Page 113 - Boiler_Operators_Handbook,_Second_Edition

98 Boiler Operator’s Handbook

a tune-up be performed each year. That is, however, not period of time so the technician can collect data that are
as frequent as I believe they should be done. I’ve docu- all relative to that firing rate. This can mean anything
mented many cases where performance of a tune-up as from operating the subject boiler in manual, while using
soon as evidence of mis-operation exists will pay for another to handle load, to controlling steam dumped to
itself in as little as a couple of weeks. The larger your atmosphere to produce a constant load.
plant is, basically the more fuel you burn, the sooner a An operator can be so involved in simply maintain-
tune-up will pay for itself. The important thing is that ing the firing condition that there’s not time to collect
the operator monitor operation to determine when it’s the data and that’s another reason for using a contrac-
needed independent of regular intervals. tor. In many cases there are problems creating the load
Sometimes the evidence is rather apparent, smoke conditions for tune-ups because there isn’t enough load.
pouring out the stack or frequent flame failures, but Wasting steam may seem like a logical solution but if the
that’s the extreme and an operator should detect prob- plant normally operates with high condensate returns
lems long before it gets that bad. wasting steam may be impossible because the water pre-
I personally believe a plant should use a contrac- treatment system can’t produce enough water to waste
tor for tune-ups because the contractor’s employees are as steam. That’s why, in some cases, boiler tune-ups are
doing the job at a higher frequency so their equipment restricted to the winter.
is maintained in calibration, their skill level is higher, When a boiler is tuned up in the summer the data
and they aren’t distracted by other things going on in the and adjustments at high fire may be made by temporar-
boiler plant. A contractor can afford to invest in high tech ily running the firing rate up to grab readings which
equipment for tune-ups when doing several a month. isn’t the same as establishing a stable condition so
That same equipment is too expensive for a plant performance at those rates may be a lot different than
that only needs to use it once or twice a year. That the report indicates. A boiler plant log should always
doesn’t mean that a contractor is always the best op- include a note to the effect that a tune-up was achieved
tion. I’ve also encountered many situations where the by grabbing readings so the assumption that it was a
contractor considers the tune-ups as fill-in jobs and pulls normal load tune-up is not made.
the employee regularly to handle emergencies so the I will argue that it isn’t necessarily important to fire
tune-up loses the continuity that’s required to ensure it’s a boiler at or near full load to tune it up with a full me-
done properly. The single biggest problem with opera- tering combustion control system. When properly con-
tors doing tune-ups is they get pulled away to handle figured a full metering system can be set up with a few
other situations and if the contractor’s operation is the readings, preferably at loads to at least 50% of maximum
same that’s a disadvantage to using that contractor. firing rate because the variables associated with load are
Is a tune-up necessary right now? That’s a question corrected for by the system with one single exception
a boiler operator has to ask whenever plant operating assuring that the maximum firing rate according to air
conditions indicate it. Monitoring of evaporation rate flow is.
or heat rate and other conditions can indicate a tune- A final note on tune-ups. They are not a final fix.
up is necessary. Of course the operator has to be aware As the boiler continues to operate the linkage, fan wheel,
of situations that can create a problem that could be and everything else is subjected to friction and wear.
wrongly attributed to controls (like blocking of plant air With jackshaft type parallel positioning controls every-
entrances) and correct them first. thing in the plant can alter the burner’s air to fuel ratio.
Something coming loose and shifting position from I’ve been told that all you have to do is to repeat a
vibration or for other reasons should also be sought out tune-up every year, whether it needs it or not, and you
before committing to a tune-up. An employer will get find your readings are still the same. If you do that, give
very upset if the cost of a tune-up is revealed to be some- me a call, I want to see that boiler! It’s always possible
thing other than a problem with the controls. I remember that something can slip, wear, or change in some man-
one chief that got peeved when he discovered the opera- ner during normal operation and you’ll have to repeat
tor called for a regular tune-up just because he got lonely the tuning process to restore efficient and clean firing
and wanted the company of the contractor’s technician. before the year is up. When that happens it’s best to
A number of things must be considered in asso- treat the time between tune-ups as the required interval
ciation with a boiler tune-up and some of them are best unless a couple of repeat runs prove that one time was a
accomplished by the operator. To tune a boiler it’s neces- fluke and you can go back to annual tune-ups or what-
sary to create stable firing conditions for at least a short ever interval your equipment sets for you.