Power Engineering 4a - Unit 12 - Elements of a boiler system

Carbon that is not combined with hydrogen is referred to as:

Select one:

a. Mono-carbon

b. Separated carbon

c. Free carbon

d. Fixed carbon

D

As a general rule the size of the condensate receiver should be large enough to hold a volume of condensate equal to the water evaporated by the boiler in a _____ period.

Select one:

a. One and one half hour

b. One hour

c. 45 minute

d. 20 to 30 minute

D

Soot blowers are essential equipment on a boiler fired with:

Select one:

a. Natural gas

b. Solid fuels

c. Propane

d. Butane

B

The power requirements for the FD fan of a fluidized bed boiler are ______ times _______ than other boiler designs?

Select one:

a. 4, more

b. 1.5, less

c. 3, more

d. 1.5, more

C

Inlet damper control on a fan:

Select one:

a. Is far less complicated than outlet damper control.

b. Is only used on forced draft fans.

c. Requires less power to drive the fan at reduced loads.

d. Requires more power to drive the fan when the vanes are closed.

C

Heating plants with multiple boilers may have:

Select one:

a. A common feedwater control valve

b. Separate condensate receivers

c. Individual feedwater systems

d. Independent boiler feedwater controls

D

The _______ fan blows combustion air into the wind box of a boiler.

Select one:

a. Balanced draft

b. Forced draft

c. Induced draft

d. High pressure

B

Combustion of fuel in a boiler furnace:

Select one:

a. Requires a higher air-fuel ratio than a diesel engine

b. Should occur with a minimum of excess air

c. Is perfect when the stack gases are free of moisture

d. Requires mechanical draft

B

A modulating pressure atomizer has its return oil flow regulated by:

Select one:

a. A pressure regulator

b. A solenoid valve in the return line

c. A firing rate control valve in the return line

d. A modulating valve to the burner

C

The advantage of a steel stack over a reinforced concrete stack is that a steel stack:

Select one:

a. Has longer life

b. Has lower cost

c. Requires less maintenance

d. Is more durable

B

Large capacity burners:

Select one:

a. must not have full flow of fuel on startup

b. Are very safe relative to puff-back

c. Require only a small pilot flame

d. Require high flow on ignition

A

A steam boiler must be equipped with two low water fuel cut-off devices when the boiler:

Select one:

a. Has two burners

b. Is not continuously attended

c. Has dual fuels

d. Has over 47 m² of heating surface

B

A device that normally uses air or steam to do its job is the:

Select one:

a. Siphon

b. Operating control

c. Burner

d. Soot blower

D

The amount of air required to supply just enough oxygen for complete combustion is called the:

Select one:

a. Excess air

b. Perfect air

c. Primary air

d. Theoretical air

D

A characteristic of mechanical draft is that the draft:

Select one:

a. Is properly regulated during all firing conditions

b. Varies with chimney temperature

c. Varies with chimney height

d. Varies with atmospheric pressure

A

The major disadvantages of oil over coal is that oil:

Select one:

a. Does not burn as clean

b. Is more difficult to control

c. Is more expensive and less abundant

d. Requires more storage space

C

Which of the following burner designs is NOT used for burning oil?

Select one:

a. Stoker-type burner

b. Steam atomizing burner

c. Air atomizing burner

d. Mechanical atomizing burner

A

he approximate amount of excess oxygen for combustion of a gaseous fuel is:

Select one:

a. 6 - 8%

b. 3 - 5%

c. 10 - 15%

d. 3 - 10%

D

Boiler combustion is regulated by:

Select one:

a. Controlling the air and fuel flow

b. Controlling or regulating the fuel flow

c. Varying the speed of an FD fan

d. Varying the speed of an ID fan

A

Water that is fed into the boiler to replace water that has been converted into steam is called:

Select one:

a. Feedwater

b. Return water

c. Condensate

d. Fresh water

A

The amount of pre-mix air to an atmospheric burner is typically:

Select one:

a. 30% to 40%

b. 20% to 50%

c. 5% to 8%

d. 10% to 12%

A

One way to increase natural draft is to:

Select one:

a. Decrease the amount of excess air

b. Install a higher chimney

c. Increase the primary air flow

d. Incorporate a forced draft fan

B

An induced draft fan:

Select one:

a. Discharges air to the wind box

b. Operates at higher temperatures than an FD fan

c. Has less expensive materials of construction than an FD fan

d. Is physically smaller than a forced draft fan

B

This type of boiler condenser return piping arrangement prevents the boiler pressure from forcing boiler water into the return lines:

Select one:

a. Return line piping

b. Pipe siphon

c. Back-flow preventer

d. Hartford loop

D

The complete combustion of carbon is represented by the balanced equation C + O2 =:

Select one:

a. CO

b. CO + heat

c. CO2 + heat

d. 2CO2

C

According to the CSA B-51 code, a blowoff tank is necessary to:

Select one:

a. Reduce the boiler water velocity

b. Remove sludge from blow-off water

c. Prevent blowing off too quickly

d. Prevent high temperature and pressure in the sewer

D

A blowoff tank:

Select one:

a. Accommodates only one boiler

b. Must have a safety valve, set to the maximum allowable working pressure of the tank

c. Lowers the temperature and pressure of the incoming boiler water

d. Is not classed as a pressure vessel since it is vented

C

When an atmospheric gas fired burner is burning fuel properly:

Select one:

a. It will have perfect combustion.

b. There will be no turbulence

c. It will have a long bright yellow flame

d. It will have a blue, non-luminous flame

D

A boiler blowoff system is equipped with slow and fast opening valves. The quick opening valve is placed:

Select one:

a. Furthest from the boiler and opened last

b. Closest to the boiler and opened last

c. Furthest from the boiler and opened first

d. Closest to the boiler and opened first

D

When a greater than normal amount of combustible mixture is ignited, the result may be:

Select one:

a. A too rapid boiler warm-up

b. A negative furnace pressure

c. A puff-back

d. A boiler explosion

C

To which of the following oil burners is the oil supplied under high pressure?

Select one:

a. Steam atomizing burner

b. Rotary cup burner

c. Air atomizing burner

d. Mechanical atomizing burner

D

In order to get maximum heat transfer in a bubbling bed furnace, it is necessary to:

Select one:

a. Operate the sootblowers more frequently

b. Add fuel gas to the regular fuel being burned

c. Ensure that the boiler tubes are covered by the expanded bed

d. Increase the fuel consumption per hour

C

During combustion in a boiler furnace, black smoke may be caused by:

Select one:

a. Insufficient combustion air

b. Flyash in the flue gas

c. Too much nitrogen in the air

d. Too much combustion air

A

A design disadvantage of a pressurized fluidized bed furnace is:

Select one:

a. Fuel preparation is very complex

b. A great deal of maintenance is required

c. A wide range of fuels cannot be used

d. Erosion and/or corrosion/fouling of turbine blades may occur

D

Water formed from the condensing of steam is called:

Select one:

a. Waste water

b. Condensate

c. Wet steam

d. Water

B

Limestone, when added to a fluidized bed boiler:

Select one:

a. Reduces greenhouse gas emissions

b. Absorbs NOx

c. Acts as a de-sulphuring agent

d. Lowers the combustion bed temperature

C

Regulations require that the minimum distance between an oil-fired furnace and an indoor oil storage tank must be:

Select one:

a. 0.6 m

b. 4.7 m

c. 7 m

d. 5.2 m

A

The balanced equation for the incomplete combustion of carbon is:

Select one:

a. C + O2 = CO2 + heat

b. 2C + O2 = CO + heat

c. C + 2O2 = 2CO + heat

d. 2C + O2 = 2CO + heat

D

The two basic varieties of mechanical atomizing oil burners are the:

Select one:

a. Modulating and cluster burners

b. Rotary and reciprocating cup burners

c. Constant capacity and modulating pressure burners

d. Variable capacity and modulating burners

C

An induced draft fan handles:

Select one:

a. Flue gases from the combustion chamber

b. Flue gases going to the combustion chamber

c. Air going to the combustion chamber

d. Air from the combustion chamber

A

Due to the comparative size of FBC power plants, a significant saving is gained in:

Select one:

a. Fuel storage costs

b. "Clinker" and soot blowing costs

c. Material and construction costs

d. Fuel and waste costs

C

When a modulating mechanical atomization system is used with an oil burner:

Select one:

a. Air pressure at the burner should be 70 kPa

b. Dry saturated steam should be used

c. Very high pump pressure is required for correct atomization

d. The fuel must be preheated to 90 degrees C

C

Which of these is NOT one of the undesirable characteristic of flue-gas carbon monoxide?

Select one:

a. CO pockets in the furnace can be explosive

b. High flue gas CO means the combustion is inefficient

c. Less heat of combustion is being released by the fuel

d. CO causes fireside corrosion

D

Dissolved oxygen in condensate:

Select one:

a. Will cause waterside corrosion

b. Can cause scaling on the return lines

c. Is removed with amines

d. Necessitates the installation of a deaerator

A

Stationary soot blowers are installed in the:

Select one:

a. Convection zones

b. Secondary superheater bank

c. Primary superheater bank

d. Reheater bank

A

In a balanced draft system, the forced draft fan is:

Select one:

a. Designed to handle hot combustion gases

b. Used to maintain a slight negative pressure in the furnace

c. Smaller than the induced draft fan

d. Larger than the induced draft fan

C

Water that leaves a blowoff tank and enters a sewer must not exceed _______ °C:

Select one:

a. 75

b. 65

c. 50

d. 45

B

Before a steam or air atomizing oil burner is removed from a boiler furnace, the burner should be blown out with:

Select one:

a. Steam or air

b. High temperature solvent

c. Coal oil

d. Solvent

A

The purpose of the combustion controls on a boiler is to:

Select one:

a. Maintain the proper ratio of air to fuel

b. Vary the air and fuel ratio with variations in firing rate

c. Maintain a constant fuel flow

d. Maintain the proper ratio of combustion air to flue gas

A

Which of the following is NOT a pilot for a gas burner?

Select one:

a. Interrupted

b. Manual

c. Intermittent

d. Continuous

B

Balanced draft:

Select one:

a. Is used for furnaces with positive pressure

b. Uses a forced draft and an induced draft fan

c. Requires a tall smoke stack

d. Requires weights on the dampers to balance them.

B

The low water fuel cut-off of heating boiler must shut the fuel off if the water level drops:

Select one:

a. The lowest permissible water level

b. To an unsafe level

c. Quickly

d. Below the top row of tubes

B

The stack temperature of a boiler can rise if:<

Select one:

a. The rate of fuel flow decreases

b. The percentage of CO in the flue gas rises

c. The fireside of the boiler becomes dirty

d. Excess air is reduced

C

A diaphragm type pressure gauge:

Select one:

a. Is used to measure very small pressures

b. Cannot be used for pressures greater than atmospheric

c. Operates on a mercury column

d. Is used to measure high pressures

A

The _____ pilot is most often used on small boilers.

Select one:

a. Automatic

b. Continuous

c. Interrupted

d. Intermittent

B

In a fluidized bed boiler, a gradual loss of the fluidized bed, including fuel (carbon) particles, is due to:

Select one:

a. Priming

b. Sootblowing

c. Uplift

d. Carryover

D

The simplest way to measure draft is with:

Select one:

a. A bellows measuring device

b. A flexible diaphragm device

c. A Bourdon tube device

d. A U-tube manometer

D

Shot cleaning pellets are transported to the top of the boiler:

Select one:

a. By a hydraulic hoisting system

b. Manually

c. By a steam injection system

d. Using an air stream

D

Boiler chimneys are commonly lined with:

Select one:

a. Insulation

b. Rubber

c. Fire brick

d. Concrete

C

In a typical bubbling fluidized bed boiler, to what depth is the combustion bed maintained?

Select one:

a. 2 metres

b. 2.5 metres

c. 1.5 metres

d. 1 metre

D

A thermo hydraulic feed water regulator uses _____ as operating media.

Select one:

a. Water and steam

b. Air and water

c. CO2 and water

d. Oil and nitrogen

A

A mechanical atomizing burner has oil pumped under high pressure through a:

Select one:

a. Sprayer plate

b. Multi-spud burner

c. Ring burner

d. Rotary cup

A

Gas burners for heating boilers can be divided into two general classes:

Select one:

a. Pre and after mix

b. In-shot and up-shot

c. Refractory and ribbon-type

d. Mixing and non-mixing

A

In an atmospheric fluidized bed boiler, the combustion air pressure is typically 2.5 kPa at the FD fan, 1.6 kPa of water at the base of the active bed and _____ at the top of the combustion mass:

Select one:

a. Atmospheric pressure

b. Negative pressure

c. Boiler pressure

d. Negative 16 cm of water

A

The pressure range for pressure-atomizing burners fired with light fuel oil is approximately:

Select one:

a. 550 to 700 kPa

b. 300 to 550 kPa

c. 50 to 100 kPa

d. 150 to 250 kPa

A

The Hartford Loop prevents the water in the boiler from:

Select one:

a. Flowing out through the steam main

b. Dropping below a safe level

c. Exceeding the highest safe level

d. Exceeding the maximum temperature

B

In a mechanical atomizing burner with three fixed capacity burners, the Intermediate and high fire burner nozzles may have higher capacities than the primary burner nozzle:

Select one:

a. To allow slower boiler warm-ups

b. Because of the pump being of the positive displacement type

c. To prevent pressure surges

d. To give greater firing variations

A

Low fuel pressure in an constant capacity mechanical atomizing oil burner produces:

Select one:

a. Poor atomization

b. Gummy deposits in the burner nozzle

c. A short blue flame

d. Low excess air requirements

A

A time delay oil valve:

Select one:

a. Is located on the return line

b. Opens 5 to 15 seconds after ignition begins.

c. Opens on flame failure

d. Opens when the oil pump starts

B

High pressure boiler blowdown and blowoff guidelines can be found in:

Select one:

a. Applicable provincial acts and regulations

b. CSA B51

c. ASME Section VIII

d. ASME Section VI and VII

D

Maximum static pressure in a fuel oil line before the oil pump is limited by code to approximately:

Select one:

a. 35 kPa

b. 70 kPa

c. 10 kPa

d. 15 kPa

A

The amount of excess air required for combustion in a boiler furnace is determined by the:

Select one:

a. Ambient temperature of the outside air

b. Air supply pressure

c. Size of the boiler

d. The type of fuel being burned

D

The Hartford loop will:

Select one:

a. Replace the feedwater check valve

b. Prevent boiler water level from going below the lowest safe water level

c. Ensure continuous circulation of a hot water system

d. Only be installed on multiple-boiler systems

B

The approximate amount of excess air for combustion of fuel oil should be:

Select one:

a. 25 - 30%

b. 10 - 15%

c. 2 - 3%

d. 3 - 10%

B

A boiler with only an induced draft fan:

Select one:

a. Will have a positive furnace pressure

b. Needs a very tall stack

c. Is extremely inefficient

d. Will have a furnace pressure that is below atmospheric pressure

D

In a forced draft system, the furnace pressure is:

Select one:

a. Measured in psi

b. At atmospheric pressure

c. Below atmospheric pressure

d. under a positive pressure

D

Which of the following substances is commonly found in fuel, but is non-combustible?

Select one:

a. CO

b. H2

c. C

d. H2O

D

The efficiency of a combined cycle plant, using a pressurized fluidized bed boiler, is about _____ higher than that of a conventional pulverized coal plant.

Select one:

a. 5%

b. 10%

c. 15%

d. 20%

A

A condensate receiver low level cutoff switch will:

Select one:

a. Shut off the boiler

b. Cause the make-up valve to close

c. Open a make-up solenoid

d. Stop the feed pump thereby preventing damage to it

D

A multi-burner cluster has secondary and tertiary nozzles ignited by:

Select one:

a. The primary burner

b. An interrupted pilot

c. An igniter spark

d. An intermittent pilot flame

A

A two element feed water control system compensates for or offsets:

Select one:

a. Feed water temperature variation

b. Shrink and swell

c. Differential steam flow rate

d. Level variation

B

The result of a condensate receiver that is too small could be:

Select one:

a. High boiler water level

b. Overflowing of the condensate receiver

c. Loss of make-up water

d. Low make-up water flow rates

B

Single element feed water control systems are very efficient in maintaining the boiler water level when:

Select one:

a. Load demands are low

b. Steady or slowly fluctuating steam demand

c. The boiler is a fire tube boiler

d. The boiler has a large water capacity

B

An intermittent pilot:

Select one:

a. Remains on after the main flame extinguishes

b. Lights the main flame and remains on until the main flame is extinguished

c. Must be manually ignited

d. Lights the main flame then extinguishes

B

The area of a boiler in which air and fuel combine in a chain reaction to cause sustained burning is the:

Select one:

a. Drum

b. Breeching

c. Baffle

d. Combustion chamber

D

Which of the following is NOT a type of oil burner?

Select one:

a. Centrifugal or rotary cup burners

b. Mechanical or pressure atomizing burners

c. Steam atomizing burners

d. Atmospheric burners

D

A solenoid type fuel valve;

Select one:

a. Closes slowly

b. Always opens rapidly

c. Is held closed by electrical current

d. Is held closed by gas action

D

The inert bed material of a fluidized bed boiler must be heated to about __________ °C if burning coal.

Select one:

a. 800 - 900

b. 450 - 500

c. 500 - 700

d. 300 - 350

C

The blowoff connection on a boiler is located at the:

Select one:

a. Bottom of the steam drum of a watertube boiler

b. Top of the mud drum in a watertube boiler

c. Bottom, or base, of the shell in the firetube boiler

d. Water line in both firetube and watertube boilers

C

If the power is cut off to an automatic gas valve, the valve will:

Select one:

a. Open widely

b. De-pressurize the gas train

c. Close immediately

d. Close slowly

C

Boiler water having the highest dissolved solids concentration is found:

Select one:

a. At the bottom of the mud drum

b. At the bottom of the steam drum

c. At the top of the steam drum

d. Just below the waterline of the steam drum

D

The compressed air used as atomizing air in the air atomizing oil burner is also called:

Select one:

a. Pre-mixed air

b. Combustion air

c. Primary air

d. Secondary air

C

A diaphragm draft gauge on a furnace indicates the draft in:

Select one:

a. mm of water column

b. kPa

c. MPa

d. psi

A

Blowoff valves are used to:

Select one:

a. Reduce the steam pressure on the boiler

b. Drain or remove sediment from the continuous blowdown

c. Drain or remove sediment from the bottom of the boiler

d. Drain or remove sediment from the bottom of the steam drum

C

One of the advantages of using natural gas as a fuel in a boiler is:

Select one:

a. No standby fuel is necessary

b. Abundance in supplies

c. Low cost

d. No storage space is required

D

Using lower combustion temperatures with fluidized bed combustion reduces the:

Select one:

a. Turbulence of the furnace interior

b. Production of NOX

c. Boiler efficiency

d. Production of hot flue gases

B

On a boiler blowoff system, a valve that requires at least five 360° turns of the operating mechanism to change from fully open to fully closed is known as:

Select one:

a. an isolating valve

b. a slow opening valve

c. a non-return valve

d. a quick opening valve

B

On a steam boiler with single element feed water control, the measure variable is

B

The Hydramotor® valve or Fluid Power Gas Valve® consists of:

A) the valve operator.

B) the valve operator and the valve body.

C) the valve handle and the valve body.

D) the valve stem and the valve handle.

E) the valve body.

B

The ASME B31.1 Power Piping Code 122.1.7 states that (with few exceptions) the feedwater piping for all power boilers shall be provided with a check valve and a stop valve or cock between the check valve and the hotwell.

A) True

B) False

B