Page 124 - Boiler_Operators_Handbook,_Second_Edition

What the Wise Operator Knows 109

tion. I like to treat those requirements like heating loads “I don’t know” to what I thought was a simple ques-
with a higher base temperature. tion. I would be very embarrassed if someone asked me
An asphalt plant, for example, may operate at 500°F what steam pressure I normally operated at and I had to
to keep the asphalt a liquid and that temperature is so respond that I didn’t know. More than half of the opera-
high that swings in outdoor temperature between 0°F tors asked that question immediately wander over to the
and 100°F, an extreme winter to extreme summer outside nearest pressure gage to look at it before responding.
air temperature would produce a variation between 100% More than eighty percent of the operators of hot water
and 80% [(500–100) ÷ (500–0) = 80%] If they’re significant plants can’t tell me what the normal boiler water tem-
you can treat them the same as heating loads by using the perature is. I always say “it wasn’t meant to be a trick
product temperature instead of 65°F. question, I just wanted to know.”
That’s a way to determine production heating re- You shouldn’t be asking yourself the same ques-
quirements which will exist as a load independent of the tion now. You should know certain things about your
amount of product made. Actual production loads can be plant and be able to respond to one of us dumb en-
related to production output. It’s one reason that boiler gineers without hesitation. We really don’t ask trick
operators should know how many widgets or pounds of questions. When I look at a pressure gage and it reads
product the plant makes and be informed of how many somewhere between 120 and 125 psig I have to ask the
are planned for production during the next shift. question because it could be either one of those values.
Some production facilities produce a negative Here’s a quick list of common questions, see how many
load. These include plants with waste heat boilers that you can answer without looking them up:
can generate steam or hot water from exothermic reac-
tions (chemical reactions of the product that generate 1. What’s your normal operating pressure/tem-
heat). A boiler operator can be called upon to control perature?
those boilers. For the most part they conform to all 2. What pressure/temperature are the safety/relief
the rules described for regular boilers in this book but valves set at?
each one can have unique characteristics or operating 3. What’s the capacity of each boiler?
features and the operator should make sure he fully un- 4. What’s your normal feedwater/return tempera-
derstands all the manufacturer’s and process designer’s ture?
instructions for their operation. 5. What fuels do you fire?
Except for simple heating plants the operator has to 6. What’s the capacity of your fuel storage?
learn the contribution of each type of load and monitor 7. Where does your fuel come from? Are there alter-
loads to determine how much each one contributes to nate suppliers?
the total load. The simple mathematical relationships de- 8. What is the turndown for each boiler?
scribed here should help to explain some of the variations 9. What’s your electrical power (208/230/460, 3
in loads you experience to provide a way to determine phase)?
what the load will be when plant operations change. 10. How reliable is your electric power? (How many
You should be able to tell how much change in interruptions and their length in an average year)
load will be associated with a change in outdoor air tem- 11. What’s your normal compressed air supply pres-
perature, a change in production rates, shutdown of any sure?
particular part of the plant, and short-term swings as- 12. What’s your peak load? Peak day? Peak Hour?
sociated with personnel activities. At the bare minimum 13. What’s your normal winter load?
you should know what your maximum, minimum, 14. What’s your normal summer load?
weekday, weekend, holiday, and total plant shutdown 15. What’s your minimum load?
loads are. Once you know your load and know your 16. What’s your water supply pressure?
plant you can begin operating wisely. 17. What’s the normal hardness of your water supply?
Of alternate water supplies?
18. Where does your water come from? Do you have
KNOW YOUR PLANT an alternate supply for water?
19. How many boilers do you run in the summer?
I’m always amazed at the boiler operators that 20. How many boilers do you run in the winter?
don’t know their plants. I’ve been in plants with an op- 21. How frequently do you switch boilers?
erator that had been there 15 years and had him reply 22. What’s your condensate return system leakage/