Page 125 - Boiler_Operators_Handbook,_Second_Edition

110 Boiler Operator’s Handbook

percentage? MATCHING EQUIPMENT TO THE LOAD
23. What’s your normal condensate temperature?
24. Is your condensate return pumped? When we discussed priorities in the first chapter of
25. What does your blowdown drain to? this book the last was listed as the one you would spend
most of your time on, operating the plant economically.
In addition to those questions I frequently aim my Without a doubt, matching the equipment to the load is
laser pointer to produce a red dot on a vertical pipe, the easiest way to do that. I find so many boiler plants
one that comes up through the floor then continues to operating with two boilers on line and not enough load
penetrate the ceiling, and ask the operator what the line to keep one running constantly. I’ve also been in plants
is for and where it goes. While that is usually a question with four boilers on line looking at a load less than the
I want the answer to it’s occasionally used when an op- capacity of one of them. When I make those statements
erator gives the impression he knows it all. After forty I get a “so what” look from the boiler operators or the
3
years of learning boiler plants I know which of those standard WADITW response. Based on what I have
piping systems are obscure. You should test yourself seen, we should be able to conserve about 20% of the en-
in this regard. Can you look at each pipe in your plant ergy used in institutional heating plants in this country
and name its contents, source and destination? No, you by simply matching loads.
don’t have to be able to do that to answer the questions Let’s look at the example of two low pressure heat-
of some dumb engineer like me, you need to know so ing boilers operating when one could carry the load
you can react quickly and responsibly if that piping easily. My observations indicate the load is typically less
fails. than half the capacity of the one boiler. Radiation losses,
Since most of my operating was aboard ship we normally 2% of input (or less) at full load, account for
had another criteria for knowing the plant. The engine 11.5% of the input at the lower load; off cycle losses of
room aboard a ship is always at the bottom and there the boiler that isn’t firing account for another 1/2 to 2%
aren’t any windows. If there’s a skylight it’s so small depending on effective stack height; purging losses are
and far away it doesn’t provide any light at operating doubled; demand charges for electricity when the two
levels. In the event the electric generator tripped we had boilers just happen to be running at the same time; and
to know how to get around in pitch dark. Most of us car- the additional time an operator spends attending to an
ried a working flashlight at all times but I don’t see that operating boiler all add up to a considerable additional
in the typical land based boiler plant. cost for operating two boilers where one would do and
How about it? Especially you guys that work the that’s ignoring the fact that cycling losses are doubled
night shift. Can you get around the plant safely in the when the load is less than low fire capacity of one boiler.
dark? Trying it with your eyes shut is one way to test Demand charges are calculated by the electric
that skill. Be careful, however, that you don’t put your- power company for medium and large installations.
self in the position of falling down a stair or tripping Maximum demand is determined by a separate meter
over something. It’s better to do something as goofy that constantly measures the electrical load and keeps
as walking around the plant with your eyes shut when track of the maximum average electric load during a 15
someone is there that can call the ambulance if you land minute period in each month. The utility bill includes a
on your face. It may be goofy, but it might also save your charge for that demand and it’s not small change, $12
life one day. per kW which is equal to about $9 per horsepower. Any
There are a lot more questions about your plant activity that produces a higher demand simply boosts
that you don’t have to have immediate answers for that charge and any temporary operating condition that
because they’re not asked frequently and, to be honest, produces that demand creates the charge for the entire
you don’t have to know the answer to operate. You do month. In some areas the utilities charge for the highest
need to know a lot that you can’t memorize and there’s demand in the prior six months.
no need to commit it to memory; all you need to know Running two feedpumps when one will do is not
is where to find the information. You should know the only boosting the demand charge, it’s using electricity
location of historical documents, logs, maintenance re- as well. Although it’s not advisable to stop one feed
cords… basically where all the paper and spare parts are pump before starting another to avoid a bump in the de-
stored and how to find something in that maze of paper mand charge you can wait until the air compressor stops
or shelves of boxes. The next best thing to knowing an (so you know it won’t run for a few minutes) to switch
answer is knowing where to find it. over pumps. A drop in demand of ten horsepower while