543 Questions
What is the primary purpose of a fuel-fired device?
To convert chemical energy into thermal energy
What is the primary function of a combustion chamber?
To mix fuel with oxygen and facilitate combustion
What is a critical factor in the design of fuel-burning equipment?
The type of fuel used
What is a key responsibility of an Operator or Power Engineer?
To oversee the conversion of chemical energy into usable energy
What is a necessary step in the combustion process?
Thoroughly mixing the fuel with air
What is a basic requirement for fuel-burning equipment, regardless of the type of fuel used?
To be easily cleaned and maintained
What is the primary purpose of burning solid fuels in a plant?
To convert their internal energy into heat for plant processes
What type of fuels are often used to fire field-erected watertube boilers?
Solid fuels
Which of the following is NOT a type of solid fuel?
Natural gas
What is a common feature of biomass boilers?
They are custom designed to use various waste materials
What is the purpose of mechanical devices in solid fuel handling?
To transport fuel particles from storage to the boiler
What is the purpose of crushing or shredding solid fuels?
To prepare the fuel for combustion
What is the primary difference between mechanical stokers and coal pulverizers?
The size of the fuel particles
What is the purpose of a belt-weighing machine in coal handling?
To measure the amount of coal brought into the plant
What is the purpose of a bunker in a coal handling system?
To store coal in case of supply interruption
What is hog fuel?
A type of biomass fuel from wood waste
What is the purpose of the hog fuel storage bin?
To store hog fuel before it is fed into the power boiler
How does the electromagnet remove ferrous metal contamination from solid wood-based fuel?
By attracting the metal with a magnetic field and then releasing it when the electric current is switched off
What is the main difference between mass burning and Refuse Derived Fuel (RDF) techniques?
The amount of preparation the fuel goes through
What is the purpose of the magnetic head pulley?
To collect and remove ferrous metal contamination from the belt conveyor
What is the difference between the combustion chamber of a solid-fuel boiler and one designed to burn gas or liquid fuel?
The design of the combustion chamber to support the fuel during burning
What is the result of not removing fly ash from boiler convection surfaces?
Decreased boiler efficiency
What is the purpose of the hog boiler conveyor?
To feed fuel to the power boiler as needed
What is Municipal Refuse?
A type of biomass fuel derived from urban sources
What is the result of the increasing use of biomass fuels?
An increase in the variety of biomass sources
What is the purpose of the electromagnet in Figure 3?
To remove ferrous metal contamination from solid wood-based fuel
What is the purpose of removing fly ash from the flue gas stream?
To reduce environmental impact
What is the typical range of heating value of solid fuels as fired?
8140 to 17450 kJ/kg
What are the three main categories of firing technologies used for solid fuels?
Mechanical stokers, Pulverized fuel firing, and Fluidized Beds
What is the purpose of the firing rate control system in a mechanical stoker?
To match the boiler load
What is the difference between overfeed stokers and underfeed stokers?
Overfeed stokers add fuel from above the bed, while underfeed stokers add fuel from below the bed
What is the purpose of the rotating bladed wheel in a spreader stoker?
To throw fuel onto the bed
What is the purpose of the air jet in an air jet overfeed stoker?
To propel the fuel through the furnace to the grate
What is the purpose of the vibrating elements in a vibrating grate stoker?
To transport the fuel through the furnace
How is the fuel bed height controlled in a crossfeed stoker?
With an adjustable fuel gate
What is the purpose of the draft fan in a crossfeed stoker?
To supply underfire combustion air
What is the purpose of the retort in an underfeed stoker?
To feed coal up through the fire bed
What type of coal is particularly suitable for burning in an underfeed stoker?
High volatile, low ash coal
What is the purpose of the primary air fan in a pulverized fuel system?
To blow powdered coal through the coal pipes
How does the cyclone furnace handle ash with a low ash fusion temperature?
It forms a molten slag
What is the effect of the vortex in the cyclone furnace?
It creates ideal conditions for rapid combustion
In what form is the fuel carried in a pulverized fuel system?
Powder
What is the purpose of the Tuyeres in an underfeed stoker?
To supply combustion air to the fuel bed
What is the advantage of pulverizing coal in a pulverized fuel system?
It allows for lower grades of coal to be burned
What is the typical temperature of the combustion products in a cyclone furnace?
Above 1650°C
What is the purpose of the dumping grates in an underfeed stoker?
To collect ashes from the combustion process
What is the primary purpose of the main boiler furnace in cyclonic firing?
To cool the products of combustion
What is the effect of increasing air velocity in a fluidized bed furnace?
The bed material leaves the furnace
What is the purpose of limestone in a fluidized bed boiler?
To react with sulfur compounds and reduce emissions
What is the function of the in-bed tubes in a bubbling fluidized bed boiler?
To receive heat through radiation and conduction
What is the purpose of the cyclone dust collector in a bubbling fluidized bed boiler?
To intercept and return bed materials to the bed
What occurs when the air velocity is increased to a certain level in a fluidized bed furnace?
The bed loses a defined upper limit
What is the primary difference between cyclone furnaces and pulverized coal-fired furnaces?
The manner in which combustion takes place
What is the purpose of the grate in a fluidized bed furnace?
To support a bed of granular solid material
What is the effect of using in-bed tubes in a bubbling fluidized bed boiler?
The formation of thermal NOX is reduced
What is the region above the bed level and the top of the furnace called?
The freeboard zone
What is the primary purpose of the refractory surrounding the furnace in the boiler?
To protect the surrounding watertubes from the abrasive effects of the fuel and bed materials
What is the characteristic of the combustion air pressure in a bubbling fluidized bed boiler?
It is typically 2.5 kPa at the FD fan and 1.6 kPa at the base of the active bed
What happens when the fluidization air velocity is increased in a bubbling fluidized bed boiler?
The air bubbles disappear and the bed materials are carried through the furnace
What is the purpose of the tube for feeding fuel to the bed in the boiler?
To feed fuel to the bed and achieve stable combustion
What is the characteristic of a circulating fluidized bed boiler?
The bed materials are carried through the furnace and the air bubbles disappear
What is the difference between an atmospheric fluidized bed combustion (AFBC) boiler and a pressurized fluidized bed combustion (PFBC) boiler?
The furnace pressure
What is the primary advantage of a PFBC boiler over a conventional pulverized coal-fired plant?
It is more efficient
What is the purpose of the cyclone separator in a circulating fluidized bed boiler?
To collect and reintroduce fuel and bed materials to the base of the bed
What is the primary application of a pressurized fluidized bed combustion (PFBC) boiler?
Combined cycle applications
What is the purpose of the staggered beams located near the furnace outlet in a circulating fluidized bed boiler?
To disengage coarser materials from the combustion gas flow
What is the primary role of the combustion chamber in a boiler?
To mix the fuel with sufficient oxygen for sustained combustion
What is the main purpose of a boiler?
To convert chemical energy into thermal energy
What is a critical factor in the design of fuel-burning equipment?
All of the above
What is the role of the Operator or Power Engineer in a plant?
To oversee the conversion of chemical energy into thermal energy
What is a necessary step in the combustion process in a boiler?
Thoroughly mixing the fuel with air
What is the purpose of various components inside a boiler?
To promote efficient combustion and heat transfer
What is the primary consideration when selecting the method of fuel transportation in a solid fuel handling system?
Fuel size and properties
What is the primary purpose of crushing or shredding solid fuels before combustion?
To enhance the fuel's combustion efficiency
What is the primary advantage of using a fluidized bed boiler for burning solid fuels?
Greater flexibility in fuel type and size compared to cyclone furnaces
What is the primary purpose of using a belt-weighing machine in a coal handling system?
To monitor the coal's flow rate and quantity
What is the primary characteristic of biomass fuels that distinguishes them from fossil fuels?
Renewable and sustainable source
What is the primary benefit of using mechanical stokers for burning coal?
Easier ash removal and disposal
What is the primary role of the bunker in a coal handling system?
To store coal in case of supply interruptions
What is the primary difference between pulverized coal-fired boilers and cyclone furnaces?
Furnace design and architecture
What is the primary purpose of the hammer mill in a coal handling system?
To remove tramp metal from the coal
What is the primary benefit of using biomass fuels in a solid fuel boiler?
Reduced greenhouse gas emissions and environmental impact
What is the primary purpose of the hog fuel storage bin?
To feed fuel to the power boiler as needed
What is the main difference between mass burning and Refuse Derived Fuel (RDF) techniques?
The amount of preparation the fuel goes through
What is the purpose of the electromagnet in Figure 3?
To attract and remove ferrous metal contamination from the fuel
What is the result of not removing fly ash from boiler convection surfaces?
Decreased boiler efficiency
What is a common characteristic of biomass fuels?
They burn in suspension and produce ash
What is the purpose of the magnetic head pulley?
To attract and remove ferrous metal contamination from the fuel
What is the primary advantage of using biomass fuels?
They can be sourced from a variety of urban and rural sources
What is the primary difference between solid-fuel boilers and boilers designed to burn gas or liquid fuel?
The combustion chamber design
What is the purpose of the hog fuel conveyor?
To feed fuel to the power boiler as needed
What is a common source of biomass fuels?
All of the above
What is the primary function of the mechanical stoker in a boiler?
To transport and support the burning solid fuel bed
What is the typical range of moisture content in waste wood or sludge?
10% to 65%
What is the purpose of the grate in an overfeed stoker?
To support the burning fuel bed
What is the characteristic of the fuel bed in a spreader stoker?
The fuel is fed from above the bed
What is the purpose of the vibrating elements in a vibrating grate stoker?
To transport the fuel through the furnace
How is the fuel bed height controlled in a crossfeed stoker?
By adjusting the fuel gate
What is the primary difference between overfeed and underfeed stokers?
The direction of fuel feeding
What is the purpose of the combustion air in an air jet overfeed stoker?
To propel the fuel through the furnace
What is the typical range of heating value of solid fuels as fired?
6980 to 22100 kJ/kg
What is the purpose of the mechanical drive system in a crossfeed stoker?
To move the fuel bed through the furnace
What is the primary purpose of the tuyeres in an underfeed stoker?
To supply combustion air to the fuel bed
What is the advantage of using pulverized coal in a boiler furnace?
It enables better combustion control and burns rapidly and thoroughly
What occurs when the fluidization air velocity is increased in a bubbling fluidized bed boiler?
The fuel bed becomes more turbulent
What is the primary function of the cyclone furnace?
To burn low quality fuel, containing large amounts of ash, with a low ash fusion temperature
What is the purpose of the dumping grates in an underfeed stoker?
To collect ashes from the fuel bed
How does the cyclone furnace handle ash with a low ash fusion temperature?
It melts the ash and it flows out of the cyclone furnace in liquid form
What is the purpose of the primary air fan in a pulverized coal system?
To blow the pulverized coal through the coal pipes
What is the characteristic of the combustion process in a cyclone furnace?
It occurs at a high temperature, often exceeding 1650°C
What is the purpose of the retort in an underfeed stoker?
To channel the coal into the incandescent layer
What is the significance of the vortex in a cyclone furnace?
It creates ideal conditions for rapid combustion
What is the primary function of the windbox in a fluidized bed furnace?
To deliver combustion air under pressure
What is the primary reason for the use of refractory surrounding the furnace in a bubbling fluidized bed boiler?
To protect the surrounding watertubes from the abrasive effects of the turbulent fuel and bed materials
What is the purpose of the in-bed tubes in a bubbling fluidized bed boiler?
To reduce the formation of SOX and NOX
What is the characteristic of the combustion air pressure in a circulating fluidized bed boiler?
It is typically 6 to 10 m/s at the FD fan and 1.6 kPa at the base of the active bed
What is the purpose of the cyclone separator in a circulating fluidized bed boiler?
To capture and reintroduce the fuel and bed materials to the base of the furnace
What is the result of increasing the airflow in a fluidized bed furnace beyond a certain point?
The bed material is transported out of the furnace
What is the difference between an atmospheric fluidized bed combustion (AFBC) boiler and a pressurized fluidized bed combustion (PFBC) boiler?
The AFBC operates at atmospheric pressure, while the PFBC operates at a higher pressure
What is the primary difference between a bubbling fluidized bed boiler and a circulating fluidized bed boiler?
The way the bed material is fluidized
What is the characteristic of the fuel burned in a bubbling fluidized bed boiler?
It has a low heating value and high moisture content
What is the purpose of the cyclone dust collector in a bubbling fluidized bed boiler?
To intercept and return bed materials to the furnace
What is the purpose of the tube for feeding fuel to the bed in the boiler?
To feed fuel to the bed and enhance the combustion process
What is the region above the bed level and the top of the furnace called?
The freeboard zone
What is the advantage of a circulating fluidized bed boiler over a bubbling fluidized bed boiler?
It has a longer residence time for the fuel and bed materials
What is the purpose of the grate in a fluidized bed furnace?
To permit airflow
What is the effect of using limestone in a fluidized bed boiler?
It reduces the formation of SOX
What is the purpose of the staggered beams located near the furnace outlet in a circulating fluidized bed boiler?
To disengage coarser materials from the combustion gas flow
What is the characteristic of the combustion air pressure in an atmospheric fluidized bed combustion (AFBC) boiler?
It is typically 2.5 kPa at the FD fan and 1.6 kPa at the base of the active bed
What is the primary advantage of a fluidized bed boiler over a conventional pulverized coal-fired plant?
It can burn a wider range of fuels
What is the advantage of a pressurized fluidized bed combustion (PFBC) boiler over a conventional pulverized coal-fired plant?
It has a higher efficiency due to the combined cycle application
What is the purpose of the air nozzles in a bubbling fluidized bed boiler?
To fluidize the bed
What is the primary advantage of a Pressurized Fluidized Bed Combustion (PFBC) plant design?
Higher overall power generation efficiency
What is the purpose of maintaining the correct expanded bed height in a bubbling bed boiler?
To keep in-bed tubes covered
What is a drawback of a PFBC boiler compared to an AFBC system?
Complexity and erosion of gas turbine blades
How is the working bed height controlled in a bubbling bed boiler during operation?
Through changes in limestone feed rate and bed drain rate
What is the purpose of the control systems in an FBC boiler?
To optimize fuel handling and flue gas treatment
What is the result of a lower furnace temperature in a PFBC boiler?
Reduced steam temperature
What is the temperature range required for the bed materials to ignite the solid fuel?
500°C to 700°C
How long does it take to preheat the bed using auxiliary burners?
1 hour
What is the advantage of using fluidized bed combustion for burning low-grade fuels?
Flexibility in fuel characteristics
What is the purpose of adding crushed limestone to the coal in a fluidized bed boiler?
To act as a desulfurizing agent
What is the range of combustion efficiency in a coal-fired circulating fluidized bed boiler?
97.5 to 99.5%
Why are FBC plants smaller in size compared to pulverized coal plants?
Due to higher heat transfer rate in the furnace
What is the disadvantage of fluidized bed combustion in terms of power requirements?
High power requirements for combustion air
What is the result of gradual loss of the fluidized bed in an FBC unit?
Lower efficiency and higher cost dust collectors
Why is the combustion temperature in an FBC unit limited to 800°C to 900°C?
To prevent the oxidation of nitrogen into NO2
What is the advantage of using FBCs in terms of regulatory compliance?
Significant reduction in SOX and NOX emissions
What is the main advantage of using natural gas as a boiler fuel?
No storage space is required if delivered by pipeline
What is the primary component of natural gas supplied to the consumer?
Methane
What is the purpose of adding mercaptan to natural gas?
To aid in leak detection
What is the main disadvantage of using natural gas as a fuel?
It is highly flammable and explosive in certain concentrations with air
Where is natural gas usually processed?
At a processing plant, usually located in a natural gas producing region
What is the purpose of booster stations along the natural gas pipeline?
To increase the pressure of the pipeline
What is the purpose of storing natural gas underground?
To store it in a safe and convenient manner
What is the primary reason for processing natural gas?
To remove impurities
What is the main advantage of using liquefied petroleum gas (LPG) as a fuel?
It requires little storage space because it is stored in a liquid rather than vapour form
What is the primary characteristic of biogas?
It is a renewable energy source
What is the primary characteristic of natural gas that makes leak detection difficult?
It is colourless, odourless, and tasteless
What is the process by which bacteria convert organic matter into methane and carbon dioxide?
Anaerobic digestion
What is the primary advantage of using LPG over other fuels?
It is easier to store and transport
What is the correct sequence of events in a gas burner?
Mix fuel and air, ignite, monitor combustion
What is the primary difference between premix and after mix burners?
The way air and fuel mix
What is the purpose of processing biogas?
To remove carbon dioxide and other impurities
What is a disadvantage of using biogas?
It is not widely available
What is the boiling point of propane at atmospheric pressure?
-42°C
What is the purpose of the venturi in a premix burner?
To mix air and fuel
What is the advantage of using ribbon burners over premix burners?
They are quieter and provide more stable flame conditions
What is the purpose of the adjustable air shutter in an atmospheric premix burner?
To ensure the correct amount of premix air
What happens when the speed of burning exceeds the velocity of the gas issuing from the ports in an atmospheric premix burner?
The flame flashes back into the mixing tube
What is the typical percentage of premix air that produces a satisfactory burner operation in an atmospheric premix burner?
30 to 40%
What is the role of the venturi in an atmospheric premix burner?
To create a low-pressure zone, drawing primary air into the venturi
What is the purpose of the forced draft fan in an after mix gas burner?
To provide combustion air
What is the characteristic of the combustion process in an atmospheric premix burner?
Clean combustion with additional combustion air
Why is the primary air percentage important in an atmospheric premix burner?
It influences the nature of burning
What is the purpose of the diffuser vane in an after mix gas burner?
To create turbulent airflow
What is the characteristic of the flame when the premix is low in an atmospheric premix burner?
Long and pale blue
What is the advantage of an atmospheric premix burner?
No mechanical draft devices are necessary
What is the primary characteristic of an after mix type burner?
The gas and air mix together after leaving the burner
What is the purpose of the vanes cast into the outside of the burner ring in an after mix burner?
To impart a swirling motion on the combustion air
What is the typical range of kW inputs for after mix gas burners?
Relatively small kW inputs to extremely large inputs
What is the purpose of the ring manifold in a multi-spud burner?
To direct gas to the burner throat
What is the advantage of using a multi-spud burner with individual spuds that can be isolated?
Ability to remove, clean, repair, and replace individual spuds without shutting down the boiler
What is the purpose of the air diffuser cone in a ring burner?
To give the air a swirling motion before entering the furnace
What is the characteristic of refractory burners?
They are no longer commonly used
What is the purpose of the small jets in a refractory burner?
To supply gas to the mixing tunnels
What is the purpose of the venturi-shaped tunnels in a refractory burner?
To promote thorough mixing of gas and air
What is the advantage of using a ring burner with numerous gas outlet holes?
Improved mixing of gas and air
What should be done to leaking safety shut-off valves?
They should be replaced, not repaired
Why is it necessary to inspect burner components?
To identify signs of overheating and deterioration
What is the purpose of main fuel gas valves?
To control the flow of gas to the burners
Why is it necessary to clean gas burners?
To remove carbon deposits with a wire brush
What is the purpose of automatic safety shut-off valves?
To quickly extinguish burners upon adverse conditions
What is the correct way to address plugged burner orifices?
Drill out with a proper sized drill by a Class A gas fitter
What is the primary advantage of using refractory burners?
Higher combustion efficiency with a minimum of excess air
What is the main disadvantage of refractory burners?
All of the above
What is the purpose of a continuous pilot burner?
To provide a safety circuit and ensure the main gas valve cannot be opened if the pilot is not burning
What is the characteristic of an interrupted pilot burner?
It ignites and is proven at the beginning of the main burner run sequence, and then extinguished
What is the purpose of lubricating gas shut-off cocks?
To ensure freedom of movement and prevent wear
What should the flame color be during gas burner operation?
Blue with yellow tips
What is the purpose of the combustion air-proving switch?
To verify the function of all combustion safety limit controls
What is the purpose of checking air registers for freedom of movement?
To prevent wear and ensure proper operation
What is the purpose of an annual combustion analysis?
To make adjustments to provide maximum combustion efficiency
What is the purpose of cleaning, testing, and replacing the flame scanner, flame rod, or thermocouple flame detector?
To ensure proper operation and safety
What is the primary advantage of a PFBC boiler over a conventional gas turbine alone?
Larger total electrical power output
What is the purpose of maintaining the correct expanded bed height in a bubbling bed boiler?
To maximize conductive heat transfer
What is a drawback of a PFBC boiler compared to an AFBC system?
Complexity and erosion of gas turbine blades
How is the working bed height controlled in a bubbling bed boiler during operation?
Through changes in limestone feed rate and bed drain rate
What is unique about the control systems of an FBC boiler compared to a conventional steam generator?
They are quite different due to specialized fuel handling systems
What is the pressure of the boiler furnace in a PFBC plant design?
1013 kPa
What is the main component of natural gas supplied to the consumer?
Methane
What is the purpose of mercaptan in natural gas?
To aid in leak detection
Where is natural gas usually processed?
At a processing plant
What is the primary factor affecting the availability and cost of natural gas?
End-user location
What is the purpose of booster stations in natural gas transportation?
To maintain pipeline pressures of about 7000 kPa
What is the disadvantage of using natural gas as a fuel?
It is highly flammable and explosive in certain concentrations with air
What is the purpose of processing natural gas?
To separate different hydrocarbons from the base gas
What is the typical storage method for natural gas?
Underground in porous rock zones
What is the purpose of testing piping connections in natural gas systems?
To detect leaks
What is a necessary step in leak detection in natural gas systems?
Using a gas detector to identify the source of the leak
What is the minimum temperature required for the combustion process to begin in a fluidized bed?
500°C
What is the primary benefit of using fluidized bed combustion for burning solid fuels?
All of the above
What is the purpose of heating the fluidizing air before it passes through the bed in a fluidized bed combustion?
To increase the bed temperature
What is the range of combustion efficiency in a coal-fired circulating fluidized bed boiler?
97.5 to 99.5%
What is the purpose of adding crushed limestone to the coal in a fluidized bed boiler?
To act as a desulfurizing agent
What is the disadvantage of fluidized bed combustion in terms of power requirements?
Higher power requirements for combustion air
What is the effect of gradual loss of the fluidized bed on the efficiency of the combustion process?
It decreases the efficiency
What is the advantage of fluidized bed combustion in terms of regulatory compliance?
It meets increasingly stringent emission regulations
What is the typical operating temperature range of a fluidized bed boiler?
800°C to 900°C
What is the benefit of using a circulating fluidized bed boiler over a bubbling fluidized bed boiler?
Higher combustion efficiency
What is a characteristic of liquefied petroleum gases?
They are petroleum gases that can be easily liquefied
What is the primary purpose of processing biogas?
To increase the concentration of methane and remove corrosive components
What is a common use of biogas?
As a fuel for power generation
What is a requirement of a gas burner?
To mix fuel and air, and maintain stable ignition
What is the difference between premix and after mix burners?
The method of air and fuel mixing
What is the purpose of the venturi in a premix burner?
To mix primary air with fuel
What is a characteristic of the combustion process in a premix burner?
It is complete and quiet
What is the boiling point of butane at atmospheric pressure?
0°C
What is a disadvantage of using biogas?
It is not widely available
What is a characteristic of natural gas?
It is colourless, odourless, and tasteless
What is the primary function of the adjustable air shutter in an atmospheric premix burner?
To ensure the correct amount of premix air
What is the effect of excessive primary air on the flame in an atmospheric premix burner?
It creates a noisy operation and reduces combustion efficiency
What is the purpose of the diffuser vane in an after mix gas burner?
To create turbulent airflow
What is the characteristic of the fuel-air mixture in an atmospheric premix burner?
It is a homogeneous mixture of fuel and air
What is the primary benefit of using an atmospheric premix burner?
It is a simple and cost-effective design
What is the effect of increasing the primary air in an atmospheric premix burner?
It shortens the flame and increases combustion efficiency
What is the purpose of the venturi in an atmospheric premix burner?
To create a low-pressure zone to draw in primary air
What is the characteristic of the burner operation with a 30-40% premix?
It produces a non-luminous, blue flame
What is the difference between an atmospheric premix burner and an after mix gas burner?
The atmospheric premix burner mixes the gas and air streams before ignition, while the after mix gas burner mixes them after ignition
What is the purpose of the gas orifice in an atmospheric premix burner?
To control the fuel flow rate
What is a critical requirement for main fuel gas valves in heating and power boilers?
They must open slowly and close instantly when de-energized.
What is the purpose of the vanes cast into the outside of the burner ring in an after mix burner?
To impart a swirling motion on the combustion air
Why is it necessary to inspect burner components such as diffusers and venturi tubes?
To identify signs of overheating and deterioration.
What is the characteristic of the gas flow in a multi-spud burner?
The gas flows out of multiple holes or slots formed into the end of each spud
What is the purpose of leak testing pilot and main burner safety shut-off valves?
To identify any leaks that could lead to safety issues.
What is the recommended method of cleaning carbon deposits from gas burners?
Using a wire brush and solvents to cut grease deposits.
What is the function of the diffuser vanes in a multi-spud burner?
To promote intensive mixing of gas with air
What is the primary purpose of automatic safety shut-off valves in heating and power boilers?
To quickly extinguish burners upon adverse conditions.
What is the advantage of a multi-spud burner with a ring manifold located outside the windbox?
It allows for the isolation of individual spuds in case of damage
What is the purpose of the air diffuser cone in a ring burner?
To give the air a swirling motion before entering the furnace
Who should be employed to replace damaged burner components and address the conditions leading to the component failure?
A licensed Class A gas fitter.
What is the characteristic of refractory burners?
They consist of refractory material containing a number of circular holes
What is the purpose of the small jets in a refractory burner?
To supply gas to the mixing tunnels
What is the advantage of a multi-spud burner over a refractory burner?
It is easier to repair and maintain
What is the purpose of the windbox in a multi-spud burner?
To house the ring manifold and spuds
What is the characteristic of the combustion air in a ring burner?
It is supplied through the centre of the gas ring
What is the primary function of refractory burners in gas-fired heating equipment?
To preheat the gas and air mixture before it enters the furnace
What is the main disadvantage of using refractory burners in gas-fired heating equipment?
Higher cost due to complex design
What is the primary function of a pilot burner in gas-fired heating equipment?
To ignite the main burner and form part of the safety circuit
What is the difference between a continuous pilot and an intermittent pilot in gas-fired heating equipment?
Continuous pilots burn at all times, while intermittent pilots automatically ignite at the start of each burner operating sequence
What is the purpose of checking the flame color during gas burner operation?
To ensure the flame is blue with yellow tips
What is the purpose of lubricating gas shut-off cocks during gas burner operation?
To prevent corrosion and ensure smooth operation
What is the purpose of the combustion air-proving switch in gas-fired heating equipment?
To prove the presence of combustion air before the main burner ignites
What is the purpose of the low fire start interlock in gas-fired heating equipment?
To prevent the main burner from igniting at low fire conditions
What is the purpose of the annual combustion analysis in gas-fired heating equipment?
To adjust the burner to provide maximum combustion efficiency
What is the purpose of the flame scanner, flame rod, or thermocouple flame detector in gas-fired heating equipment?
To detect the presence or absence of the main flame
What is the primary purpose of the diaphragm gas valve in Figure 25?
To provide a safety shut-off for lower capacity gas-fired boilers and furnaces
What happens when the relay coil energizes in the diaphragm gas valve?
The plunger lifts, sealing off the upstream gas pressure
What causes the diaphragm gas valve to open?
The pressure beneath the diaphragm exceeding the pressure above
What is the purpose of the small 3-way valve in the diaphragm gas valve?
To allow gas to enter the valve and flow around the diaphragm
What happens when the heat demand is satisfied in the diaphragm gas valve?
The contacts of the operating control open, and the relay coil de-energizes
What is the effect of throttling the bleed gas in the diaphragm gas valve?
The valve opens more slowly
What is the minimum distance required between the fuel tank and the furnace?
0.6 m
What is the maximum temperature allowed for the fuel tank?
38°C
Where should the oil fill cap be located?
At least 1 m above ground level
What is the purpose of the vent on the fuel tank?
To prevent overpressure in the tank
Why is the tank equipped with an outside filling pipe?
To provide a means for filling the tank
What is the purpose of the air vent with a gooseneck?
To keep out dirt and rain
Why should the tank be installed with a slight slant?
To allow for easy inspection of the tank and to provide a low spot for water and dirt to accumulate
What is the primary purpose of secondary containment in fuel storage?
To contain the tank contents in case of a leak
What is the requirement for the secondary containment volume in a single above-ground tank?
At least 10% greater than the volume of the tank
What is the purpose of the vent at the top of the vessel in a secondary containment area?
To vent the interstitial space
What is the main purpose of normally closed solenoid valves?
To shut off gas supply in pilot lines
How do solenoid valves open when energized?
The electromagnetic solenoid draws the plunger up into the core
What is the purpose of the adjustable hydraulic brake in solenoid safety shut-off valves?
To slow the rate of valve opening
How does the motorized gas valve (Hydramotor) operate?
The valve is hydraulically opened and spring-loaded to close
What is the primary advantage of using motorized gas valves?
Gradual fuel admission during ignition
What is the main characteristic of fuel oil used in power plants?
High flammability and volatility
What is the purpose of the double wall tank in a fuel oil storage system?
To prevent fuel leakage and contamination
What is the primary function of the filter and trap combination in a fuel oil storage system?
To remove contaminants and impurities from the fuel
What is the minimum temperature required to atomize heavy fuel oils?
90°C
What is the main purpose of the copper supply line in a fuel oil storage system?
To connect the tank to the burner
What is the purpose of the bubbler-style level gauge in the fuel tank?
To monitor the level of the fuel
What is the main advantage of using liquid fuels in power plants?
Flexibility and variety of fuel options
What type of fuel is most suitable for air atomizing burners?
Light fuel oils
What is the purpose of the pressure relief valve in the fuel system?
To divert excess fuel back to the storage tank
What is the function of the swirlers in the air atomizing oil burner?
To force the oil through small holes into the path of the air
What is the purpose of the safety shut-off valves in the fuel system?
To shut off the fuel supply in case of emergency
What is the turndown ratio of a high turndown burner?
20:1
What is the purpose of the concrete barricades around the fuel lines?
To protect the fuel lines from vehicular traffic
What is the function of the fuel pump in the oil fuel train?
To provide the necessary pressure for proper fuel atomization
What is the purpose of the return recirculation line in the fuel system?
To return unused fuel oil from the boiler back to the storage tank
What is the purpose of the tip in an air-atomizing burner?
To force the air-oil mixture into a swirling cone shape
What is the advantage of using steam-atomizing burners over air-atomizing burners for heavier grades of oil?
The steam provides additional heat to the oil, decreasing its viscosity and improving atomization
How do mechanical atomizing burners achieve faster mixing and improved atomization?
By pumping oil under high pressure through slots in a sprayer plate
What is the purpose of the slots in the disc of a mechanical atomizing oil burner?
To provide a swirling action to the oil
What is the result of the oil passing through the orifice in the tip of a mechanical atomizing oil burner?
The oil breaks up into a spray of minute droplets
What is the characteristic of the combustion air pressure in a steam-atomizing burner?
It is maintained at 100 to 200 kPa above the oil pressure
What is the turndown ratio of a steam-atomizing burner?
6:1
What is the purpose of the fuel pump in a mechanical atomizing oil burner?
To pump oil under high pressure to the burner nozzle
What is a common problem with the slots in the disc of a mechanical atomizing oil burner?
They are prone to clogging
What is the difference between a constant capacity mechanical atomizing oil burner and a modulating pressure burner?
The constant capacity burner is designed for on-off operation, while the modulating pressure burner is designed for continuous operation
Why is a fine strainer necessary for the high-pressure atomizing oil burner?
To prevent poor atomization
What is the purpose of the turbulator vanes in a packaged burner?
To impart a swirl to the combustion air
What is the function of the cut-off valve in a packaged burner?
To shut off oil flow to the burner when oil pressure is too low
What is the purpose of the programming relay in a packaged burner?
To start and stop the burner
What is the advantage of using multiple fixed capacity burners in a cluster burner system?
To better match the firing rate to the steam demand
What is the purpose of the primary nozzle in a two-fixed capacity nozzle burner system?
To provide low-fire capacity
What is the function of the pressure relief valve in a two-fixed capacity nozzle burner system?
To return fuel oil to the inlet of the pump if the oil pressure is too high
What is the advantage of direct spark ignition over pilot flame ignition in a packaged burner?
It provides a more reliable ignition source
What is the purpose of the adjustment damper in a packaged burner?
To adjust the combustion air
What is the characteristic of the combustion air in a packaged burner?
It is swirling
What is the primary purpose of the fuel pump in the burner system?
To return unused oil to the fuel storage tank
What is the minimum oil pressure required for proper fuel atomization in the burner nozzles?
1380 kPa
What is the sequence of operations when the air damper motor moves to high fire position?
Low fire valve, then intermediate valve, then high fire valve
What is the purpose of the spark ignition system in the burner?
To light only the primary nozzle
What happens when the heat demand is low?
The burner cycles off and on, igniting only the primary nozzle
What is the purpose of the OSOV (primary oil safety shutoff valve)?
To provide a safety shut-off in case of low oil pressure
What is the primary reason the valve disc remains firmly on its seat when the burner is not in operation?
The force of the gas at inlet pressure above the diaphragm
What is the purpose of the small valve on the gas bleed port line?
To adjust the speed of the valve opening
In what position is the valve shown in Figure 25?
Closed
What occurs when the relay coil is energized?
The plunger is lifted
What is the effect of the weight of the diaphragm on the valve disc?
It holds the valve disc firmly on its seat
What is the result of the pressure beneath the diaphragm exceeding the pressure above the diaphragm?
The valve opens
What is the primary function of the solenoid valve in a gas-fired heating system?
To provide a safety shut-off in case of emergency
What is the purpose of the hydraulic brake in a solenoid safety shut-off valve?
To slow down the opening of the valve
How does the Hydramotor valve operate?
Through the use of a hydraulic cylinder
What is the purpose of the relief valve in a Hydramotor valve?
To maintain the hydraulic fluid pressure on top of the piston
What is the characteristic of normally open solenoid valves?
They are used as main and pilot bleed valves
What is the advantage of using solenoid safety shut-off valves in main burner applications?
They provide a slower opening of the valve
What is the purpose of the valve stem in a solenoid valve?
To connect the valve to the valve seat
What is the characteristic of liquid fuels used in power plants?
They are highly flammable and volatile
What is the purpose of the filter and trap combination in a fuel oil system?
To remove impurities from the fuel oil
What is the minimum distance required between the storage tank and any electrical panel or apparatus?
0.6 m
What is the maximum temperature allowed for the fuel tank?
38°C
What is the minimum height required for the oil fill cap above ground level?
1 m
What is the purpose of the gooseneck in the air vent?
To keep out dirt and rain
What is the maximum static head pressure allowed at the inlet of the fuel pump?
35 kPa
What is the purpose of installing the storage tank with a slight slant?
To provide a low spot where water and dirt can accumulate
What is the requirement for secondary containment volume when there are multiple above-ground tanks?
The volume of the largest tank plus 10% of the total volume of all the other tanks
What is the purpose of the safety berm in a secondary containment area?
To contain the tank contents if the tank were to leak
What is the purpose of monitoring the vacuum in the interstitial space of a double-wall tank?
To ensure the integrity of the inner container
What is the requirement for the secondary containment volume when there is only one above-ground tank?
The volume of the tank plus 10% of the volume of the tank
What is the primary function of the fuel pump in the boiler system?
To provide the necessary atomizing pressure to the burner nozzles
What is the sequence of operations when the air damper motor moves to high fire position?
The low fire valve, intermediate valve, and then the high fire valve are energized
What is the minimum pressure required for the fuel to properly atomize in the burner nozzles?
1380 kPa
What happens when the oil pressure drops to 1035 kPa?
The safety shut-off valves close
What is the purpose of the primary oil safety shutoff valve?
To shut off the oil supply in case of an emergency
What is the effect of the programming control on the oil flow to the burner nozzles?
It energizes the low fire valve and the primary oil safety shutoff valve simultaneously
What is the primary function of the pressure relief valve in the oil fuel train?
To divert fuel of excess pressure back to the storage tank
What is the purpose of the bubbler-style level gauge in the fuel storage system?
To monitor the level of fuel in the storage tank
What is the primary purpose of the secondary air vanes in an air-atomizing oil burner?
To promote turbulent mixing of the fuel and secondary air
What is the minimum temperature required for atomization of heavy oils?
90°C
What is the main advantage of using steam-atomizing burners over air-atomizing burners?
They provide additional heat to the oil, improving atomization of heavier oils
What is the primary function of the safety shut-off valves in the oil fuel train?
To shut off the fuel flow when a low atomizing air/steam signal is sensed
What is the primary characteristic of the spray pattern produced by a mechanical atomizing oil burner?
A spinning cone shape
What is the purpose of the tangential slots in the sprayer plate of a mechanical atomizing oil burner?
To create a swirling motion in the oil
What is the purpose of the inspection ports at the top of the interstitial space?
To insert a dip rod to check for inner wall leakage
What is the primary function of the atomization process in fuel burners?
To increase the surface area of the oil for easy vaporization
What is the typical range of oil pressure used in a constant capacity mechanical atomizing oil burner?
700 to 1400 kPa
What is the purpose of the modulating air-atomizing burner?
To vary the amount of fuel delivered to meet changing load requirements
What is the main advantage of modulating steam-atomizing burners over constant capacity burners?
They provide a higher turndown ratio
What is the primary function of the secondary air in the air-atomizing burner?
To mix with the atomized oil as it leaves the burner
What is the purpose of maintaining the atomizing steam pressure at 100 to 200 kPa above the oil pressure in a steam-atomizing burner?
To achieve proper atomization at all loads and economy in steam consumption
What is the primary characteristic of the oil spray produced by a steam-atomizing oil burner?
A fine spray of oil
What is the purpose of the centre tube in the air-atomizing burner?
To supply oil under pressure to the burner tip
What is the primary advantage of a high turndown burner?
It does not need to cycle on and off as frequently
What is the primary advantage of using steam-atomizing burners over mechanical atomizing burners?
They provide additional heat to the oil, improving atomization of heavier oils
What is the primary purpose of the orifice in the tip of the sprayer plate in a mechanical atomizing oil burner?
To break up the oil into a spray of minute droplets
What is the primary reason for equipping a high-pressure atomizing oil burner with a fine strainer?
To prevent poor atomization
What is the purpose of the turbulator vanes in a packaged burner?
To impart a swirl to the combustion air
What is the function of the cut-off valve in a packaged burner?
To shut off oil flow when oil pressure is too low
What is the purpose of the pressure relief valve in a packaged burner?
To return fuel oil to the inlet of the pump if the oil pressure is excessive
How does a multiple fixed capacity burner system typically operate?
By turning off one or two of the burners
What is the purpose of the primary nozzle in a multiple fixed capacity burner system?
To provide low-fire capacity
What is the purpose of the secondary nozzle in a multiple fixed capacity burner system?
To provide high-fire capacity
What is the result of too much oil pressure in a packaged burner?
Rich air-to-fuel ratio, incomplete combustion, and soot formation
What is the purpose of the ignition spark in a packaged burner?
To ignite the fuel
What is the purpose of the electric motor in a packaged burner?
To drive both the forced draft fan and the fuel oil pump
What is the primary difference between a modulating mechanical atomizing oil burner and a constant capacity oil burner?
The burner has an adjustable firing rate
What is the purpose of the channel in the disc and barrel of the modulating mechanical atomizing oil burner?
To bleed off part of the oil from the swirling chamber
What is the result of turning down the firing rate of a modulating mechanical atomizing oil burner?
The nozzle pressure is reduced
What is the purpose of the firing rate control valve in the return line of the modulating mechanical atomizing oil burner?
To control the amount of oil bled off
What is the advantage of using a modulating mechanical atomizing oil burner?
It maintains constant steam pressure or hot water temperature at widely varying loads
What is the requirement for the fuel supply pressure in a modulating mechanical atomizing oil burner?
It must be high to ensure efficient combustion
What is the typical range of fuel oil pressure in mechanical atomizing burners?
2050-2750 kPa
What is the primary purpose of preheating heavy oils in mechanical atomizing oil burners?
To reach a specific temperature of around 90°C
What is the function of the modulating valve in the return line of a modulating burner system?
To regulate the flow rate of oil to the main nozzle
What is the characteristic of the rotary cup oil burner?
It uses both mechanical and air-atomized means to atomize the fuel
Why is it necessary to clean fuel lines before putting burners into operation?
To prevent blockages
What is the purpose of the pilot flame in a modulating burner system?
To ignite the main nozzle flame
What is the advantage of using a rotary cup oil burner?
It is suitable for burning both light and heavy fuel oils
What is the purpose of the secondary air in a rotary cup oil burner?
To provide additional air for combustion
What should be used to clean dirty oil burners?
Kerosene or special solvents
What is the purpose of the modulating input control valve in a modulating burner system?
To keep the oil flow at the minimum firing rate during startup
What is the purpose of the electrodes in an electric ignition system?
To generate a high voltage spark
What is the typical voltage range achieved by the ignition transformer?
10 000 to 12 000 volts
What can cause a puff back in a furnace?
Weak ignition
What is the recommended method to clean burner nozzles?
With a wood splinter
What is the purpose of a fuel oil filter?
To remove dirt and impurities from fuel oil
What is the purpose of a duplex oil strainer?
To remove dirt and debris from fuel oil piping systems without interrupting flow
What should be done when shutting off air or steam atomizing burners?
Shut off the oil first, then blow out the burner with steam or air
What is the purpose of adjusting the registers when the burner is in operation?
To give the proper air to fuel ratio
What is the purpose of a cutoff valve in a fuel oil supply system?
To prevent excessive pressure buildup in the burner supply line
What happens if a flame is dark and smoky?
The fuel flow to the burner nozzle should be reduced
What is the typical pressure range of the fuel oil pump in a mechanical pressure atomizing burner?
550 to 700 kPa
What is the purpose of the plug valve in a duplex oil strainer?
To direct flow through either one of the two strainers
Why should burners be removed from the furnace when not in use?
To prevent carbon from forming within them
What is the purpose of fuel oil pumps in oil-fired boilers?
To transfer oil from the storage tank to the burner
What is the purpose of the drain valves in a duplex oil strainer?
To drain the strainer before disassembly and cleaning
What type of pump is commonly used for fuel oil systems?
Rotary pump
What is the consequence of neglecting a puff back in a furnace?
A larger furnace explosion
What is the maximum lift imposed on a fuel oil pump, measured from the bottom of the supply tank?
4.9 m
What is the purpose of the two-stage pump in fuel oil systems?
To pressurize the oil in the reservoir and discharge it to the burner
What is the purpose of the pressure regulator or modulating firing rate control valve in a two-pipe system?
To bypass the extra oil back to the tank
In a combustion process, what happens when combustion air is excessive?
The CO2 concentration in the flue gas decreases
What is the primary component of flue gas that affects efficiency?
Oxygen and carbon
Why is the CO2 concentration in the flue gas at a maximum during ideal combustion?
Because all carbon reacts to form CO2
What is the purpose of flue gas analysis?
To ensure safety, operational efficiency, and environmental impact targets are met
What type of sensors are becoming more popular for flue gas analysis due to their longer lifespan?
Infrared sensors
What is the primary purpose of the relief valve in the discharge line of the pump?
To prevent the fuel pressure at the burner from exceeding the design pressure
What is the primary component of interest in flue gas analysis from an environmental perspective?
Nitrogen oxides and sulfur oxides
What is the function of the closing spring in the cutoff valve?
To close the valve when the oil pressure is below the minimum required for proper atomization
What is the purpose of a continuous emissions monitoring system (CEMS)?
To analyze flue gas samples continuously
What is the purpose of the purging cycle in a larger oil-fired heating boiler?
To prevent the possibility of a furnace explosion during startup
Why is the sampling chamber in an external analyzer unit sometimes heated?
To keep the product to be measured from condensing out
What is the function of the time-delay oil valve in a smaller oil-fired heating boiler?
To delay the flow of oil to the burner until the furnace has been properly purged
What is the purpose of a Peltier cooler in flue gas analysis?
To condense moisture out of the flue gas
What is the purpose of analyzing the CO2 content in the flue gas?
To determine the amount of excess air in the flue gas
How is the amount of excess air supplied calculated?
By analyzing the CO2 concentration in the flue gas
What is the effect of too high a pressure on the fuel supply to the furnace?
Incomplete combustion occurs
What is the excess air percentage when the CO2 content is 12%?
25.5%
What is the purpose of the spring-loaded valve in the discharge line of the pump?
To prevent the fuel pressure at the burner from exceeding the design pressure
What is the boiler efficiency at a 12% CO2 content and a net stack temperature of 527°F?
80.5%
What is the consequence of the oil pressure at the burner nozzle dropping too low?
The atomization quality deteriorates
What is the effect of an increase in excess air on the boiler efficiency?
It decreases the boiler efficiency
What is the effect of a rise in net stack temperature on the boiler efficiency?
It decreases the boiler efficiency
What is the purpose of the programming control in a larger oil-fired heating boiler?
To control the duration of the purging cycle, time of ignition, and fuel supply
What is the function of the adjusting screw in the cutoff and pressure relief valves?
To adjust the pressure at which the valves open
What can cause a rise in net stack temperature?
Either an increase in excess air or waterside scale or fireside soot and ash deposits
What is the relationship between CO2 content and excess air?
A 1% decrease in CO2 content results in a 10% increase in excess air
What is the unit of measurement used for larger numbers, such as oxygen and carbon dioxide?
Percentage (%)
What is the method used to find the amount of excess air when the CO2 or O2 content of the flue gas is known?
By using tables or graphs
What is the purpose of keeping the excess air down to the minimum required for complete combustion?
To reduce the heat loss
What is the information required to determine the efficiency of a boiler using a combustion efficiency chart?
The percentage of CO2 in the flue gases and the net stack temperature
What is the purpose of a clean-burning flame and the correct amount of CO2 in the flue gas?
To ensure good combustion
What is the method used to find the percentage of excess air when the CO2 content of the flue gas is known?
By interpolation
What is the effect of increasing the excess air by 10% on the percentage of CO2 in the flue gas?
The percentage of CO2 decreases by 0.8%
What is the purpose of consulting the boiler manufacturer's service manual for the recommended amount of excess air?
To determine the ideal amount of excess air for the boiler
What is the importance of keeping the heat transfer surfaces clean in a boiler?
To reduce the heat loss
What is the purpose of performing flue gas analysis in a boiler?
To regulate the air supply for complete combustion
How does the modulating mechanical atomizing oil burner maintain constant steam pressure or hot water temperature at varying loads?
By bleeding off part of the oil from the swirling chamber
What is the primary function of the firing rate control valve in the return line of a modulating mechanical atomizing oil burner?
To control the amount of oil bled off to the storage tank
What is the purpose of the channel in the disc and barrel of a modulating mechanical atomizing oil burner?
To bleed off part of the oil from the swirling chamber
Why do modulating mechanical atomizing oil burners require very high fuel supply pressure?
To ensure adequate pressure for atomizing at minimum firing rate
What is the effect of reducing the nozzle pressure in a modulating mechanical atomizing oil burner?
The firing rate decreases
How does the modulating mechanical atomizing oil burner differ from the constant capacity oil burner?
The modulating burner has an adjustable firing rate, while the constant capacity burner has a fixed firing rate
What is the typical range of fuel oil pressures in mechanical atomizing burners?
2050-2750 kPa
What is the purpose of the modulating valve in the return line from the nozzle in a modulating burner system?
To regulate the flow rate of oil to the main nozzle
What is the sequence of operations when starting up a modulating burner system?
Pilot solenoid valve opens, pilot flame ignites, main oil solenoid valve opens, main nozzle flame ignites
What is the characteristic of the rotary cup oil burner?
Uses a combination of mechanical and air-atomizing means to atomize the fuel
Why is it important to clean the fuel lines before putting the burners into operation?
To prevent dirt and other foreign materials from plugging the small holes and passageways in the burner
What is the purpose of the primary air fan in a rotary cup oil burner?
To supply primary air for atomizing the fuel
What is the advantage of using a modulating mechanical atomizing oil burner?
It provides a variable firing rate
What is the purpose of the secondary air in a rotary cup oil burner?
To supply secondary air for combustion
What is the consequence of the oil pressure at the burner nozzle dropping too low?
The fuel oil will not atomize properly
What is the purpose of using a clean work area when cleaning burners?
To prevent damage to the delicate parts of the burner
What is the primary purpose of the relief valve in a fuel system?
To prevent the fuel pressure at the burner from exceeding the design pressure
What is the purpose of the cutoff valve in a fuel system?
To prevent the fuel pressure at the burner from dropping too low
What is the function of the spring-loaded valve in a fuel system?
To release excess fuel when the set pressure is reached
What is the purpose of the time-delay oil valve in a fuel system?
To delay the fuel supply to the burner until the furnace has been properly purged
What is the effect of too much excess air on boiler efficiency?
It decreases boiler efficiency
What is the purpose of analyzing the CO2 content in the flue gas?
To check the amount of excess air in the flue gas
What is the primary function of the bellows in a cutoff valve?
To open the valve when the oil pressure is above the minimum needed for proper atomization
What is the effect of poor atomization on boiler efficiency?
It decreases boiler efficiency
What is the purpose of the purging cycle in a fuel system?
To purge the furnace and flue gas passages of any combustible vapours
When cleaning burner nozzles, what should be used to avoid damaging the nozzle holes or the oil grooves?
A wood splinter
What is the correct procedure when shutting off air or steam atomizing burners?
Shut off the oil first, and then blow out the burner with steam or air
What is the purpose of the adjusting screw in a relief valve?
To adjust the pressure at which the valve opens
What is the consequence of too little air in a burner?
A dark, heavy smoke
What is the purpose of adjusting the registers in a burner?
To give the proper air to fuel ratio
Why should burners not be left in the furnace when not in use?
To prevent carbon from forming within the burners
What is the maximum lift imposed on a fuel oil pump, measured from the bottom of the supply tank, according to the CSA B139 Installation Code?
4.9 m
What is the purpose of a two-stage pump in a fuel oil system?
To lift oil from the supply tank when the lift is greater than 2.4 m
Why is it important to ensure that the lines are air tight in a fuel oil system?
To eliminate air leaks into the oil lines
What is the purpose of a pressure regulator or modulating firing rate control valve in a two-pipe fuel oil system?
To bypass the extra oil back to the tank
What is the purpose of electric ignitors in oil burners on packaged firetube boilers?
To provide ignition for the oil burner
What is the purpose of the electrodes in an electric ignition system?
To ignite the fuel-air mixture at startup
What is the typical pressure range of fuel oil in mechanical pressure atomizing burners?
550-700 kPa
What is the purpose of the duplex oil strainer in fuel oil systems?
To filter out impurities from the fuel oil and allow continuous flow
What is the result of weak ignition, improper adjustment of the electrodes, and poor insulation in electric ignition systems?
A puff back, a small furnace explosion
What is the purpose of the filter cartridge in the cartridge filter?
To absorb moisture and filter out fine particles from the fuel oil
What is the function of the plug valve in the duplex oil strainer?
To direct flow through either one of the two strainers without interrupting the flow
What is the purpose of the cutoff and pressure relief valves in fuel oil supply systems?
To prevent excessive pressure buildup in the fuel system
What is the typical voltage range achieved by the ignition transformer in electric ignition systems?
10 000-12 000 volts
What is the purpose of the drain valves in the duplex oil strainer?
To drain the strainer before disassembly and cleaning
What is the purpose of the electrodes in relation to the burner tip in electric ignition systems?
To position the electrodes slightly above and in front of the burner tip
What is the effect of a 5.5% increase in excess air on the CO2 content if the original CO2 content is 12%?
CO2 content will decrease by 0.6%
What is the approximate boiler efficiency at a 12% CO2 content and a 527°F net stack temperature?
80.5%
What is the effect of a decrease in excess air on the boiler efficiency?
Boiler efficiency will increase
What is the effect of a rise in net stack temperature on the boiler efficiency at a constant CO2 content?
Boiler efficiency will decrease
What is the primary reason for the decrease in CO2 concentration in the flue gas when combustion air is excessive?
Extra nitrogen and unreacted O2 dilute the CO2 concentration
What is the cause of a rise in net stack temperature in a boiler?
Both increase in excess air and fouling of heating surfaces
Which of the following compounds is NOT a primary component of flue gas from a boiler that uses biomass or coal as fuel?
Hydrogen
What is the primary purpose of a continuous emissions monitoring system (CEMS)?
To meet environmental impact targets
What is the relationship between CO2 content and excess air in a boiler?
CO2 content decreases with increase in excess air
What is the primary advantage of using infrared (IR) sensors over electrochemical sensors in flue gas analysis?
IR sensors are not consumed by the measurement process
What is the primary reason for heating the sampling chamber in an external analyzer unit?
To keep the product from condensing out
What is the primary purpose of analyzing the percentage of CO2 in the flue gas?
To determine the amount of excess air supplied
What is the primary limitation of using IR sensors in flue gas analysis?
They are affected by dirt and fogged lenses
What is the primary purpose of pumping a flue gas sample to a sampling chamber within an external analyzer?
To analyze large systems where probe insertion is not feasible
What is the primary reason for the decrease in CO2 concentration in the flue gas when combustion is incomplete?
CO production increases, reducing CO2 concentration
What is the primary purpose of using a Peltier cooler in an external analyzer unit?
To condense moisture out of the flue gas
What is the unit of measurement used for larger numbers, such as oxygen and carbon dioxide?
Percentages (%)
According to Table 2, what is the relationship between the CO2 or O2 content of the flue gas and the amount of excess air supplied?
A direct proportionality
What is the purpose of interpolating the approximate value of excess air for a CO2 percentage of 9.6% in Example 1?
To find the exact percentage of excess air
What is the ideal amount of excess air for complete combustion?
A variable value depending on the type of boiler and firing equipment
What is the purpose of keeping the heat transfer surfaces clean in a boiler?
To minimize heat loss
What are the two things required to determine the combustion efficiency of a boiler using a combustion efficiency chart?
The percentage of CO2 in the flue gases and the net stack temperature
In Example 2, what is the purpose of finding the percentage of excess air supplied to the boiler?
To regulate the air supply for complete combustion
What is the effect of excessive heat loss on the combustion efficiency of a boiler?
It decreases the combustion efficiency
What is the purpose of performing flue gas analysis in a boiler?
To calculate the combustion efficiency
What is the relationship between the percentage of CO2 in the flue gases and the amount of heat loss?
An inverse proportionality
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