26 terms

Chapter 7: Boiler Water Treatment

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Water in the boiler must be...
Water used in the boiler must be treated for safety and efficiency.
What can cause boiler parts to overheat? and why?
Minerals present in water can cause a buildup of deposits that restrict water flow and cause overheating of boiler parts.
What can cause high surface tension? and what does it result in?
Impurities floating on the surface of the boiler water cause high surface tension, resulting in priming and carryover.
What can oxygen in feedwater lead to? and what can be implemented/changed for maximum effectiveness and economy?
Oxygen in feedwater can lead to corrosion and pitting of the boiler metal. The correct amount of water treatment chemicals must be used for maximum effectiveness and economy.
What is Feedwater?
Feedwater is water that is treated for use in the boiler.
What is boiler water? and what is it's use?
Boiler water is the water in the boiler used to produce steam.
What is Scale?
Scale is the accumulation of minerals such as calcium and magnesium on boiler heating surfaces.
What is Corrosion?
Corrosion is rusting or pitting that weakens boiler metal by the thinning (removal) of the metal.
What is caustic embrittlement?
Caustic embrittlement is the accumulation of high alkaline elements, which cause boiler metal corrosion at stress zones in the boiler.
When can priming and carryover occur?
Priming and carryover can occur when boiler water is carried into the steam lines.
How is foaming caused?
Foaming is caused by the formation of steam bubbles trapped below a film on the boiler water surface.
What is alkalinity?
Alkalinity is the property of a solution as determined by measuring its pH level.
What should boiler water ph typically be?
Boiler water pH typically should be between 10 and 11.5
What does an electronic hardness tester do?
An electronic hardness tester is commonly used to determine water hardness.
How are TDS measured?
The total dissolved solids (TDS) present in boiler water are measured with a conductivity meter.
What is external boiler water treatment?
External boiler water treatment is treating water before it enters the boiler.
What does a water softener do?
A water softener removes calcium and magnesium to reduce water hardness.
What does a deaerator do?
A deaerator heats feedwater to the temperature of saturated steam at the pressure within a pressure vessel.
What does a surge tank collect?
A surge tank collects condensate before sending it to the deaerator.
What does a bypass feeder do?
A bypass feeder introduces water treatment chemicals in a loop on the discharge side of the feedwater pump.
What does a chemical feed system do?
A chemical feed system introduces feedwater treatment chemicals into a boiler at a predetermined and controlled rate.
What is internal boiler water treatment?
Internal boiler water treatment is treating water after it has entered the boiler.
How is blowdown used? and why?
Blowdown is used as a part of a boiler water treatment program to remove some of the concentrated water and replace it with feedwater to lower the total concentration of dissolved solids.
How is a bottom blowdown performed?
A bottom blowdown is performed in accordance with plant procedures and/or the water treatment program.
What can an inadequate/improper boiler water treatment do?
Lack of adequate boiler water treatment or improper boiler water treatment can drastically shorten the life of a boiler.
What must the boiler operator record?
The boiler operator must record any conditions that may indicate water treatment-related problems.