Page 53 - Boiler Operator’s Handbook

38 Boiler Operator’s Handbook

Speaking of motors, that’s one of the few things I DOCUMENTATION
haven’t destroyed… yet. I can proudly say that I haven’t
burned up a motor. We won’t talk about all the other The importance of a boiler plant log, SOPs and di-
things I’ve managed to destroy. You can, however, burn saster plans has already been stressed. Since I measure
up a motor if you don’t treat it properly. The common the quality of care a plant receives by its documentation
method is starting and stopping one. Motors are rated I thought it important to let you know what I believe
for “continuous duty,” “intermittent duty,” and “severe should be documented in a boiler plant.
duty.” You might think that had something to do with Okay, that’s a fair question, what is documenta-
where they were located or how many hours the run tion? It’s all the paperwork. Frequently I get a comment
a day but it doesn’t. Continuous duty motors are de- from an operator that goes something like “If I wanted
signed to operate continuously but only be started once to do paperwork I would have got a desk job!” It’s not so
or twice an hour. Intermittent duty motors are designed much doing it, if you think about it the only paperwork
to start and stop a little more frequently and severe you do regularly is filling out the logs. Since the logs are
duty motors are designed to be started and stopped your proof of what you did they’re always part of an
all the time. So, if you have a small boiler with a level operator’s job. SOPs, disaster plans, and the rest that I’m
controlled feed pump that starts and stops all the time it about to cover are primarily one time deals with main-
should have an intermittent or severe duty motor. tenance as required. You prepare them once and revise
When a motor is started the electricity has to bring them when necessary.
it from a dead stop up to speed and that takes a lot of Maintaining documentation can make a big dif-
energy. It’s sort of like pushing somebody’s car when ference in plant operation. Occasionally I get a call to
they’re broke down (does anybody do that anymore?) It visit a customer to attempt to determine who made a
takes a lot of push to get it moving. A motor has what we piece of equipment, what size is it, and where they can
call high inrush current, in other words a lot of electric- get another one. Of course those situations are always
ity flows through it when it starts. All that energy heats crisis ones because whatever it is just broke down and
up the motor because it isn’t as efficient as it is when they need it desperately. Frequently I’ll be in a plant
it’s up to speed. If you stop it, then start it up again collecting data for a new project or to troubleshoot a
right away the heat is still there and added to. So don’t problem and discover the nameplate on a piece of equip-
start and stop continuous duty motors a lot. Sometimes ment is either (1) covered with eight layers of paint, (2)
we have some problems getting a boiler started and scratched and hammered until it’s beyond recognition,
repeatedly start and stop the burner blower. If there’s or (3) simply missing… and the plant will not have one
a selector switch on the panel that lets you run the fan piece of paper that describes it. Look around your plant
constantly that’s a better thing to do than let it continu- at every piece of equipment and imagine what’s going
ally start and stop. to happen if it falls apart when you need it!
One operating technique I was taught was start- Just a couple of weeks ago I was in a plant with
ing a centrifugal pump with the discharge valve shut. pumps that were so corroded you couldn’t even read the
It won’t hurt the pump, at least not right away, and manufacturer’s name and markings formed in the cast-
preventing any fluid flow reduces the load of the pump ing, let alone the nameplate. They had no paperwork
while the motor is coming up to speed. Once the motor on those pumps and no spares. If one broke down they
is up to speed you open the discharge valve so fluid can would have no idea where to find a replacement for it.
flow. That only works on centrifugal pumps. They couldn’t even go to their local pump shop and get
You can also overload a motor. One of the things something that would work because they had no idea
I always used to do when designing boiler plants was what the capacity or discharge head of the pump was.
specify a pump or fan be supplied with a motor that was There’s an old saying in the construction industry that
non-overloading. In other words, it was oversized so no applies to everyone, it’s short and sure, “Document or
matter what we did operating it, we couldn’t overload Disaster.”
it. Now I know that oversized motors are very inefficient Not only do you need plant documentation, it has
so I try not to do that (oversize them). Since we’re all to be organized. I insist the design for every project have
working toward more energy efficient installations you an equipment list and a bill of materials and that they be
will have more opportunities to burn up a motor than I correct. When the job is done those documents become
ever did! the index for the operating and maintenance instruction
manuals. I’ve had customers who didn’t seem to care