Which of the following is caused from scale buildup on boiler tubes:
1. Increased boiler efficiency
2. Weakening of tube metal
3. Decreased boiler efficiency
4. Increased flue gas temperature
5. Cracks in boiler tubes
a. 1, 2, 3, 4
b. 1, 3, 4, 5
c. 2, 3, 4, 5
d. 1, 2, 4, 5
e. 1, 2, 3, 5
2,3,4,5
Contributors to corrosion within a steam boiler are:
1. Oxygen
2. Carbon dioxide
3. A low pH
4. High chelate concentrations
a. 1,2,3
b. 2,3,4
c. 1,3,4
d. 1,2,4
e. 1,2,3,4
1,2,3,4
An, which is fed to the boiler for protection of the condensate return lines against corrosion may:
1. Raise the pH of the condensate
2. Coat the surfaces of the return piping
3. Neutralize the acid in the condensate
4. Cause the condensate to become acidic
a. 1,2,3
b. 1,2,4
c. 1,3,4
d. 2,3,4
e. 1,2,3,4
1,2,3
Hydrazine is used in some high-pressure boilers:
a. To control the dissolved solids
b. To prevent foaming
c. To eliminate erosion
d. To reduce oxygen pitting
e. To condition the sludge
To reduce oxygen pitting
Factors required to produce caustic embrittlement are:
1. A high pH in the boiler water
2. Stress of the boiler pressure parts
3. A riveted joint in the boiler
4. A leak of boiler water
a. 1,2,3
b. 2,3,4
c. 1,3,4
d. 1,2,4
e. 1,2,3,4
1,2,4
Failure to filter surface water before using it in a boiler may result in:
1. A hard, tight scale forming on the water surfaces of the boiler metal
2. Foaming within the boiler
3. A sludge collecting in the drums
4. Boiler water carryover with the steam
a. 1,2,3
b. 1,3,4
c. 1,2,4
d. 2,3,4
e. 1,2,3,4
2,3,4
Boiler blow-off is an important factor in feed water control because it:
1. Should be completed before the boiler water is tested
2. Allows removal of sludge thus assists in the prevention of scale
3. Increases scale formation
4. Should be completed after the boiler water is tested
5. Will help control dissolved solids within the boiler
a. 2,4,5
b. 3,4,5
c. 2,3,5
d. 1,2,3
e. 2,3,4,5
2,4,5
The prime purpose of a continuous blow-off line from the steam drum of a water tube boiler is to:
a. Heat the make-up water supplying a deaerator
b. Reduce the solids level of the boiler water by intermittent operation of the blow-off valves
c. Control the dissolved oxygen in the boiler water
d. Control the quantity of scale forming salts within the boiler water
e. reduce the water level in the boiler
Control the quantity of scale forming salts within the boiler water
_________ is any solid, liquid or vaporous contaminants that leaves the boiler with the steam.
a. Carryover
b. Blowdown
c. Feedwater
d. Mist
Carryover
______ is particularly harmful as it forms a very hard deposit on turbine blades.
a. Carryover
b. Mist
c. Silica
d. Phosphate
Silica
The causes of carryover can be divided into two broad categories, namely mechanical and _______.
a. virtual
b. carryover
c. upset
d. chemical
chemical
Chemical carryover is primarily caused by _________.
a. foaming
b. misting
c. water
d. load
foaming
Mechanical carryover can be prevented by careful boiler design and by operating the boiler within the design parameters for _______ level and firing rates.
a. chemical
b. water
c. blowdown
d. impurities
water
Chemical carryover can be prevented by chemical injection, mud drum blowdown, and _____ ____.
a. pure water
b. boiler load
c. continuous blowdown
d. more chemicals
continuous blowdown
Efficient control of boiler blowdown is an important objective in the operation of most boilers.
a. True
b. False
true
A simple blowdown system involves control that is totally reliant on the _______ .
a. effluent
b. chemicals
c. conductivity
d. operator
operator
Control of the continuous blowdown flow, is ________ adjusted by the operator.
a. manually
b. automatically
c. quickly
d. slowly
manually
Erratic solids levels in the boiler result in erratic residuals of phosphate, sulphite, and so on, which leads to confusion over the amounts of chemicals that are added.
a. True
b. False
true
A significant improvement in _________ can be accomplished by recovering heat from the blowdown water and from its flash steam.
a. control
b. efficiency
c. recovery
d. chemical
efficiency
When testing boiler water for dissolved solids:
a. We measure the amount of electrical current the sample will conduct
b. We must neutralize the oxide ion first
c. Phenolphthalein is added to the sample to cause a blue colour to appear, neutralizing the water
d. Filter the sample, then add sulphuric acid to neutralize the water
e. Measure the "m" and "P" alkalinities
We measure the amount of electrical current the sample will conduct
Shot feeding involves the injection of chemicals over a relatively ______ period of time.
a. long
b. intemittent
c. short
d. measured
short
A _________ feed system. This involves feeding the chemicals to the boiler system at the most efficient injection points and at a steady and continuous rate.
a. closed bypass
b. shot
c. slug
d. continuous
continuous
With the _________, it is common practice to mix one batch of chemicals per day.
a. closed bypass
b. shot
c. slug
d. continuous
continuous
One method of controlling chemical concentrations, is to prepare chemical batches using a table of tank level vs. ________ _________.
a. chemical addition
b. pump stroke
c. steam flow
d. feedwater addition
chemical addition
The two most common designs of are the___________, plunger-type and the electronic impulse-type.
a. electric
b. electronic
c. reciprocating
d. vibrating