Page 112 - Boiler_Operators_Handbook,_Second_Edition

Boiler Plant Operations 97

around a boiler plant there will be significant deteriora- ravages of weather, etc., simply because the plant had no
tion of the boiler’s interior unless protected. To prevent need of it. Later, when they attempted to sell it, the con-
corrosion the boiler should be free of moisture. After the dition was so bad they couldn’t and their only option for
boiler is drained all drain valves should be closed, the removing it was to pay for its removal. Even if you don’t
drum covers or inspection openings opened and dry need the equipment, preserve it. Someone may need it
air blown through the boiler to remove any remaining and, if it’s in good shape, the owner will get enough for
moisture. Checking the exhaust air with a hygrometer it to pay for its removal. Otherwise you may be looking
until the humidity in the boiler is less than 10% or 5% at that rusting hulk until the day you retire.
above the humidity of the drying air is recommended. When the whole plant is put in lay-up these guide-
Then, insert a package of silica gel with a corrosion lines can be extended to other equipment. Special
proof drain pan under it and close the boiler completely. consideration should be given to a long-term lay-up.
The air will simply compress and expand in the boiler Valves and Pumps with packing should have the pack-
as it heats and cools so there is no reason to install an ing removed and replaced with fresh material heavy
expansion tank. The silica gel must be checked twice in graphite. Packing that was in use and allowed to
a year to ensure it is active. Any moisture found in the dry will harden and be almost impossible to remove
drain pan should be removed. later. Pumps that have mechanical seals can’t be reli-
The fire sides of the boiler have to be considered ably preserved but you could try disassembling the
for long-term lay-up. The connection to the stack and seals, coating the sealing surfaces with a mineral oil
the combustion air inlets should be blocked off. The and reassembling them. Pumps containing oil and such
enclosed spaces should be dried and maintained with a materials that lubricate without freezing can simply be
silica gel dryer as described above. isolated after filling with liquid that is confirmed water
Normally boiler control panels, motor starters, free and not prone to form acids while stagnant. Pumps
etc. can be maintained by simply leaving the power on containing water should be drained completely, close
the panels. The indicating lights in the panels should their supply and discharge valves, then use the vent and
supply sufficient heat to lower the internal humidity drain connections to blow dry air through them and dry
and prevent corrosion from moisture. If the panels are them completely before isolating.
exposed to the weather addition of some light bulbs in-
side to lower the humidity is recommended. Wiring two
100 watt lights in series will produce about 25 watts of TUNE-UPS
heat but the likelihood of one of the bulbs failing is very
low. Add lights to panels that do not have any. Motors While I prefer the title “tune-up” the PhD’s at the
for combustion air fans, boiler water feed or circulating EPA who like to use longer words have chosen to use
pumps can be heated by applying reduced voltage to the the title “Combustion Optimization” for the same thing.
windings or using heaters that are supplied for such a This edition is revised to include a section for Combus-
purpose. tion Optimization in the Chapter on maintenance be-
Always refer to the manufacturer’s instruction cause it’s a normal maintenance function. It’s included
manuals for suggestions or requirements for lay-up. Re- in the startup of a new boiler and operation of the plant
gardless of how the boiler is laid up its condition must during a tune-up is covered here.
be monitored on a regular basis, preferably weekly, to Along the east coast of the US I’ve found that
ensure it is not deteriorating. All you’re normally doing it’s uncommon for a boiler operator to be expected to
is making sure the seals are intact (nobody opened it and perform the tune-up of a boiler. A few plants do their
left it) and there’s no external signs of corrosion or other own tune-ups but use other personnel with labels like
problems. Initially test water during wet lay-up on a Instrument Technician to do the work. Rarely is it done
weekly basis to ensure it has sufficient sulfite to remove by a licensed boiler operator. Tune-ups should be per-
any oxygen. When testing reveals consistent retention of formed on an annual basis and whenever there’s reason
the sulfite extend the testing interval until a period with to believe the controls are out of tune and it is always
a drop of 10 ppm is experienced and incorporate that the boiler operator’s role to identify a problem with the
testing interval in your SOPs. Check silica gel inside the controls that require a tune-up.
furnace on a monthly basis and inside the boiler on a Another factor in tune-ups are the requirements of
semi-annual basis. the local environmental office, whoever is responsible
All too often I’ve seen a boiler abandoned to the for enforcing the Clean Air Act. Many states now require