Boiler Combustion

If the theoretical quantity of dry air required to burn one pound of fuel oil is 13.75 pounds, what is the weight of air per pound of fuel when operating a boiler at 5% excess air? A. 14.44 pounds B. 15.13 pounds C. 15.81 pounds D. 16.50 pounds

A. 14.44 pounds

Which of the following represents the proper color of the flame end farthest from the boiler burner during normal operations? A. Bright yellow or orange B. Dark brown C. Light brown haze D. Dazzling white

A. Bright yellow or orange

Excess air must be provided to an operating boiler to allow for A. complete combustion of fuel B. fluctuations in boiler steam demand C. heat losses up the stack D. all of the above

A. complete combustion of fuel

A higher than normal stack gas temperature could indicate A. dirty firesides or watersides B. inner or outer casing leakage C. eroded water screen tube walls D. defects in burner cone refractory

A. dirty firesides or watersides

White stack smoke from a main propulsion boiler could indicate A. excessive amount of combustion air B. low fuel temperature C. insufficient air for combustion D. excessive furnace combustion temperature

A. excessive amount of combustion air

Underway on watch in the fire room, the bridge reports black smoke coming from the stack. This would indicate A. fuel oil temperature too low B. excessive steam atomization pressure C. excessive air-fuel turbulence D. All of the above

A. fuel oil temperature too low

The greatest single overall loss of efficiency in a marine propulsion steam plant cycle results from A. heat lost in the main condenser B. poor heat transfer in feed water heaters C. mechanical losses in the atomization process D. heat loss required for fuel oil heating

A. heat lost in the main condenser

Insufficient combustion air supply to a boiler furnace can cause A. low superheater temperature B. high stack temperature C. high superheater temperature D. sputtering fires

A. low superheater temperature

Excessive combustion air in a boiler is indicated by the flame ends appearing as a/an A. shower of sparks B. orange colored flame C. dull red or black flame D. light brown flame

A. shower of sparks

If the theoretical quantity of dry air required to burn one pound of fuel oil is 13.75 pounds, what weight of air will be necessary to burn one pound of fuel to operate a boiler at 10% excess air? A. 14.44 pounds B. 15.13 pounds C 15.81 pounds D 16.50 pounds

B. 15.13 pounds

Efficient combustion in a boller is indicated by a A. white haze B. brown haze C. yellow haze D. black haze

B. brown haze

In a boiler furnace, incomplete combustion due to Insufficient air yields an excess amount of A. carbon dioxide B. carbon monoxide C. nitrogen oxide D. sulfur dioxide

B. carbon monoxide

In an oil fired water-tube boiler, Inner casing air leaks can cause A. oxidation of the exposed furnace walls B. chilling of the combustion gases C. excessive feed water consumption D. localized overheating of tube surfaces

B. chilling of the combustion gases

If a boiler is smoking black and increasing the boiler front air box pressure does not reduce the smoke, the cause can be A. forced draft fan failure B. dirty atomizers C. heavy soot on tubes D. high ambient air temperature

B. dirty atomizers

A light brown haze issuing from the boiler smoke stack generally indicates A. dirty fuel atomizers B. good fuel combustion C. too much fuel pressure D. a high firing rate

B. good fuel combustion

When too much excess air is supplied to an operating boiler, the A. heat loss will be reduced B. heat loss will be excessive C. flame will impinge on the burner cone D. flame will be a deep red color

B. heat loss will be excessive

In addition to being hazardous to personnel, gas leaks through the boiler casing can also A. cause overheating of the uptakes B. impair the effectiveness of the air purge cycle C. cause improper atomization of fuel oil D. impair the operation of the high steam pressure limit switch

B. impair the effectiveness of the air purge cycle

Lower boiler efficiency results from carrying too much excess air because A. it varies the degree of deposits on heat absorbing surfaces B. it increases the volume and temperature of the furnace gas leaving the stack C. it decreases the volatility of the fuel D. the flame temperatures are lower

B. it increases the volume and temperature of the furnace gas leaving the stack

Black smoke issuing from the boiler stack can be caused by an improper fuel/air ratio and by A. excessively high fuel pressure B. low fuel temperature C. high fuel temperature D. low fuel pressure

B. low fuel temperature

Insufficient combustion air supply to the furnace would cause A. the fires to sputter B. low superheater outlet temperature C. high stack temperature D. high feed water consumption

B. low superheater outlet temperature

If the stack temperature is higher than normal, this could indicate A. low fuel oil back pressure B. too much excess air C. high feed water pressure D. external boiler casing leakage

B. too much excess air

Regarding main propulsion boilers, what condition would normally be indicated if the bridge reported that white smoke was observed coming from the stack? A. high fuel oil viscosity B. too much excess air C. low fuel oil temperature D. insufficient steam atomization pressure

B. too much excess air

If the theoretical quantity of dry air required to burn one pound of fuel oil is 13.75 pounds, what will be the weight of the air necessary to burn one pound of fuel when operating a boiler at 15% excess air? A. 14.44 pounds B. 15.13 pounds C. 15.81 pounds D. 16.50 pounds

C. 15.81 pounds

Which of the following boiler stack (smoke color) conditions indicates efficient combustion? A. Black haze B. White haze C. Brown haze D. Yellow haze

C. Brown haze

Economy and efficiency in the operation of a marine boiler have traditionally been characterized by A. a clear stack (Invisible stack gases) B. maintaining the fuel oil temperature as high as possible C. a light brown haze from the stack D. a slight wisp of white smoke from the stack

C. a light brown haze from the stack

Insufficient air for combustion in a boiler furnace could result in a A. white incandescent flame B. high flame temperature C. black stack smoke emission D. 0% carbon monoxide level

C. black stack smoke emission

Corrosion of the flue gas side of the economizer can be a result of the I. stack gas temperature being lower than the dew point II. feed water temperature being excessively cool A. I only B. I| only C. both I and Il D. neither I or II

C. both I and Il

Insufficient combustion air supply will cause an atomizer flame to appear as a A. ragged flame B. pointed flame C. dull red flame with black streaks D. light yellow flame with white streaks

C. dull red flame with black streaks

The major heat loss in an oil fired boiler is the heat A. used in the economizer and air heater B. passing through the boiler casing C. going up the stack D. required to change water into steam

C. going up the stack

If a boiler is smoking black and increasing the boiler front air box pressure does not reduce the smoke, the cause can be A. forced draft fan failure B. heavy soot on tubes C. low fuel oil temperature D. high air heater temperature

C. low fuel oil temperature

Boiler stack gas temperatures will be higher than normal when A. fuel temperature at the burners is excessively high B. not enough excess air is being supplied for combustion C. secondary combustion is occurring in the gas passages D. internal water wall refractory baffles have failed

C. secondary combustion is occurring in the gas passages

In a steaming boiler, higher than normal stack gas temperature can be caused by A. low steam demand B. excessively high fuel oil temperature C. too much excess air D. delayed burning due to inadequate excess air

C. too much excess air

If the theoretical quantity of dry air required to burn one pound of fuel oil is 13.75 pounds, what will be the weight of the air necessary to burn one pound of fuel to operate a boiler at 20% excess air? A. 14.44 pounds B. 15.13 pounds C. 15.81 pounds D. 16.50 pounds

D. 16.50 pounds

Prior to relieving the watch at sea, you notice black smoke coming from the stack. What would this indicate? A. Insufficient excess air B. Dirty burner C. Soot blowers need to be operated D. All of the above

D. All of the above

Which color burner flame would indicate too much excess air? A. Orange red B. Yellowish orange C. Bright red D. Incandescent white

D. Incandescent white

Under normal operating conditions of constant load and combustion rates, which of the following will occur when the amount of excess air to the furnace is increased? A. The superheater inlet temperature will decrease, B. The rate of heat transfer will decrease. C. The superheater inlet temperature will increase. D. The superheater outlet temperature will increase.

D. The superheater outlet temperature will increase.

Which of the terms listed represents the ratio between the highest and lowest fuel oil pressure at which the burners will remain ignited? A. Air/fuel ratio B. Modulating band ratio C. Firing range ratio D. Turndown ratio

D. Turndown ratio

Air leaks through the inner or outer casing of a boiler could result in A. high superheater outlet temperature B. low superheater outlet temperature C. higher fuel consumption for normal steaming conditions D. all of the above

D. all of the above

Too much excess air in a steaming boiler may be indicated by A. a white burner flame B. a clear stack C. white smoke D. all of the above

D. all of the above

White smoke coming from the stack of a main propulsion boiler indicates A. too much excess air B. partially burned fuel particles are leaving the stack C. excessive air velocity through the air registers D. all of the above

D. all of the above

A lower than normal boiler stack gas temperature usually indicates A. dirty firesides B. dirty watersides C. fuel high sulfur content D. incomplete combustion

D. incomplete combustion

The chemical substance initially responsible for heat loss in the combustion process is A. sulfur B. carbon C. hydrogen D. nitrogen

D. nitrogen

Air leaks 1hrough the inner or outer casings of a boiler will A. improve fuel combustion B. decrease stack temperatures C. cause boiler panting D. reduce boiler efficiency

D. reduce boiler efficiency

Boiler stack gas temperature could be higher than normal if A. leakage exists in the inner and outer casing B. defects exist in the burner cone refractory C. fuel oil temperature is excessively high D. secondary combustion occurs in the gas passages

D. secondary combustion occurs in the gas passages

Before an explosion can occur In a boiler furnace, there must be an accumulation of unburned fuel, sufficient air to form an explosive mixture, and a A. space large enough for the explosion to occur B. ground in the burner ignition electrode C. high steam demand on the boiler D. source of ignition for the explosive mixture

D. source of ignition for the explosive mixture

An incandescent white flame in a boiler firebox would indicate A. efficient combustion B. low fuel oil temperature C. excessive fuel oil pressure D. too much excess air

D. too much excess air