Chapter 11 Boiler Water Pre-Treatment Flashcards
Subsidence is defined as:
A) Dissolve or breaking down of water hardness minerals
B) Coagulation
C) Softening of boiler feedwater using water specialized chemicals
D) Sink or fall to the bottom; settle; precipitate
D
Chemicals such as coagulants and flocculants are primarily used as:
A) An agent that causes solids to stay suspended in solution
B) An agent that causes solids to change its pH to alkaline
C) An agent that causes solids to change its pH to acidic
D) An agent that causes solids to combine forming larger heavier particles
D
Coagulation is most effective at moderate temperatures and with a pH of:
A) 5.0 to 9.5
B) 5.5 to 8.0
C) 5.0 to 8.0
D) 5.5 to 8.5
B
Subsidence chemicals like flocculants are added into the:
A) Boiler feedwater pump
B) Clarifier
C) Demineralizer
D) Pressure filters
B
Flocculation describes:
A) Clustering of individual dispersed and suspended solids forming a spongy like substance
B) Removal of scale forming salts, without forming sodium bicarbonate
C) Heating the incoming water to promote chemical reactions
D) Ion exchange to covert scale-forming salts into non-scaling forming salts
A
For boiler feedwater, both the Gravity and Pressure filters use a bed of porous material consisting of:
A) Anthracite only
B) Sand only
C) Sand and anthracite
D) Gravel, sand and anthracite
A
In cold lime softeners, hydrated lime is used to chemically precipitate the carbonate hardness from the boiler feedwater. Which chemical formula is termed hydrated lime?
A) CaCO3
B) CaO
C) Ca(OH)2
D) Ca(HCO3)2
C
The chemicals used in the cold lime softener are:
A) Calcium Sulphate and Sodium Carbonate and a coagulant
B) Calcium Hydroxide and Sodium Carbonate and a coagulant
C) Calcium Hydroxide and Calcium Carbonate and a coagulant
D) Magnesium Carbonate and Calcium Bicarbonate and a coagulant
b
Complete the following Chemical reaction for the cold lime softener.
Mg(HCO3)2 + 2Ca(OH)2 →
A) → Mg(OH)2 + 2CaCO3
B) → Mg(OH)2 + 2CaCO3 + H2O
C) → 2Mg(OH)2 + CaCO3 + H2O
D) → 2Mg(OH)2 + CaCO3
b
In a hot lime soda softener,
A) cold water enters the top of the softening unit
B) hot water enters the bottom of the softening unit
C) cold water enters the bottom of the softening unit
D) hot water enters the top of the softening unit
d
Particular advantages of the hot lime soda softener:
a) Shorter retention time thus higher throughput
b) Chemical feed to the bottom of the unit insures sludge conditioning before backwashing
c) Sludge carryover is reduced with the inverted cone treated water outlet
d) It combines, in one unit, softening, silica removal, deration and filtration
e) Do to the dynamic of the softener tower, chemical feed pumps require minimum attention
A) c, d, e
B) a, b
C) c, d
D) a, b, c
E) a, c, e
c
In hot lime-soda softeners, some of the sludge is continuously sent:
A) To the bottom of the softener
B) To the top of the softener
C) To waste
D) To the pressure filters
b
Anions contribute to the formation of:
A) Scale and Sludge
B) Sodium and Hydrogen Zeolites
C) Acidity & Alkalinity (pH)
D) Sodium and magnesium Bicarbonates
a
Cations contribute to the formation of:
A) sodium and Hydrogen Zeolites
B) Acidity & Alkalinity (pH)
C) Scale and Sludge
D) Sodium and magnesium Bicarbonates
b
Sodium Zeolite softening uses the principle of ________ exchange to convert scale-forming salts into non-scale formation salts.
A) Lime soda
B) Selective
C) Chloride
D) Ion
d
