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Water Treatment
Homework #7
20
Engineering
Professional
08/13/2009

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Cards

Term
What are the Three Primary Contaminates in Raw Water?
Definition
Dissolved Solids, Suspended Solids, and Dissolved Gases.
Term
What are the Two Sources of Water treatment used in power plant?
Definition
Surface Water and Ground Water.
Term
What are the Two forms of Water treatment used in power plants?
Definition
External Treatment and Internal treatment.
Term
What are the Four reasons we treat Boiler Feed-Water?
Definition
1. Prevent Sludge
2. Prevent Scale
3. Prevent Corrosion
4. Prevent Carryover
Term
What are Cations and what are Anions?
Definition
Cations are Positively charged ions, while Anions are Negatively charged ions.
Term
How are Suspended Solids removed from Raw Water?
Definition
Removed by Filtration
Term
How are Minerals removed from Raw Water?
Definition
De-mineralization which works on the principle that ions can be exchanged.
Term
How are Dissolved Gases gases removed from make-up water/feed-water?
Definition
Clarifiers, Coagulation, Filtration, and De-aeration/Aeration.
Term
Define P.H.
Definition
The logarithm of the reciprocal of the Hydrogen Ion Activity. Simply put: A measure of water's Acidity or Alkalinity.
Term
Is 7.0 on the scale Acidic or Alkaline?
Definition
A 7.0 on the scale is Neutral.
Term
How are chemicals added to the boiler?
Definition
Internally, either by Volatile chemicals or Non-Volatile chemicals.
Term
What is meant by the term "Cycles of Concentration"?
Definition
It indicates the number of times the water in the boiler has Cycled Up.
Term
What P.H. level do we try to maintain in boilers?
Definition
About 11 on the P.H. scale.
Term
What is Foaming and what is Priming?
Definition
Foaming is a layer of foam (bubbles) on the surface of the boiler water due to high alkalinity, high dissolved/suspended solids or the presence of oil or other colloidal solids. Priming is the carry-over of large slugs of water with the steam.
Term
Name some conditions in a boiler that could cause Carry-Over.
Definition
High water level in the boiler and/or Foaming.
Term
What chemicals are used to adjust boiler P.H.?
Definition
Caustic Soda, (Sodium Hydroxide NaOH) and Ammonia (NH3)
Term
Why is sodium Sulfite used in some boilers?
Definition
To remove oxygen from the boiler. It is an Oxygen Scavenger.
Term
How do you Blow-Down a boiler?
Definition
1. Find the true water level.
2. Have 1/2 a gauge glass full or better.
3. Open cooling water to blow-down tank.
4. Open quick opening valve or inside valve
5. Open slow opening or outside valve wide
6. Shut the outside or slow closing valve.
7. Close the inside valve or quick closing valve.
8. Check site glass
9. Secure cooling water to blow-down tank
Term
What causes Condensate Return Line Corrosion?
Definition
Term
Explain the terms Dry Lay-Up and Wet Lay-Up.
Definition
Dry Lay-Up: When taking a Boiler offline for about more than Six months one will usually dry out the boiler completely, close all the valves to prevent moisture, and lay trays of moisture-absorbing chemicals in the boiler drum.
Wet Lay-Up: When taking a boiler off-line for less than six months one will close up the boiler and fill it with warm treated water until it is filled to the vent, then the vent will be closed. Then the pressure in the boiler will be maintained slightly above atmospheric pressure.
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