Low Pressure Boilers Ch 7

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Non-adhering sludge is best removed when the boiler is ___.

under light load

Priming and carryover can be caused by opening the main steam valve too quickly.

True

Priming and carryover can lead to water hammer and possible pipe rupture.

True

Rusting of the boiler metal is caused by oxygen in the boiler water.

True

Scale acts as an insulator and slows down the transfer of heat to the water.

True

Scale formation can result in an increase in fuel required to generate steam.

True

Sodium sulfide is an oxygen scavenger that is commonly used to treat boiler water.

True

The bypass feeder is located on the main steam header to provide efficient feeding.

True

Automatic valves are used to control the amount of chemicals added by the bypass feeder.

False

Corrosion is the accumulation of sludge on boiler heating surfaces.

False

Oxygen in the boiler water is used to remove non-adhering sludge.

False

Scale and sediment cause pitting of the boiler metal surfaces.

False

Sludge is removed from the boiler using the surface blowdown valve.

False

Sludge rises when the boiler is on light load and is removed using the try cocks on the water column at the NOWL.

False

Slug feeding is used to generate foam to prevent carryover.

False

The chemicals used to treat the boiler water depend on the pressure inside the boiler.

False

Water that contains a small quantity of minerals is hard water.

False

Well water requires chemical treatment but city water does not.

False

___ is a condition caused when steam bubbles are trapped below the boiler water surface.

Foaming

A boil-out procedure is performed when a new boiler is installed.

True

Boiler water treatment is required for makeup water introduced to the boiler.

True

Boiler water treatment required for most low pressure boilers is minimal if the boiler recovers all or most of the condensate returns.

True

Chemicals added to the boiler water change scale-forming salts into non-adhering sludge.

True

Dissolved solids are impurities such as calcium, silica, and iron dissolved in solution.

True

Fuel oil contamination of the boiler water can be prevented by dumping all fuel oil heater returns to waste.

True

Fuel oil contamination of the boiler water most commonly occurs in plants using No. 6 fuel oil.

True

Oxygen in the boiler water can be removed by adding sodium sulfite.

True

___ is the exposure to highly alkaline elements, causing boiler metal corrosion at stress zones.

Caustic embrittlement

___ in the boiler water causes corrosion and pitting of the boiler metal.

Oxygen

___ can lead to water hammer.

Priming, Carryover, & High surface tension

___ is used as an oxygen scavenger to remove oxygen from the boiler water.

Sodium sulfite

Overheating of heating surfaces results in ___.

bags, blisters, & burned-out tubes

Non-adhering sludge is removed from the boiler by using the ___.

bottom blowdown valve

In low pressure boiler operation, chemicals for reducing oxygen and preventing scale can be added using a ___.

bypass feeder

Small particles of water carried into steam lines are called ___.

carryover

Fuel oil is removed from the steam and water side of a boiler by using ___.

caustic soda

High surface tension on the boiler water is shown by ___.

fluctuation in the gauge glass

Increased surface tension of boiler water can be caused by ___.

fuel oil inside the boiler

Water that contains large quantities of minerals is called ___.

hard water

Water is ___ to reduce the amount of oxygen.

heated

Hard water contains ___.

scale-forming salts

Scale is caused by ___.

scale-forming salts, hard water, & mineral deposits


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