4BE3.5 U4 C2 Obj 1 EMH

4BE3.5 U4 C2 Obj 1 EMH

Created by
@WholesomeMaroon

Questions and Answers

EASY What should be done if the burner continues to smoke?

Adjust the air-fuel ratio

Why do colder boilers experience condensation?

When the water vapour in the flue gases contacts the cold heating surfaces

What happens when a cold boiler is first started?

Flue gas condensation takes place

What is the effect of high firing rates on boilers?

<p>It causes uneven expansion</p> Signup and view all the answers

What is uneven expansion?

<p>When the furnace heats up more quickly than the rest of the firetubes</p> Signup and view all the answers

What is the effect of scale buildup on the furnace and firetubes?

<p>It insulates the furnace tube and firetubes from the cooling effect of the boiler water</p> Signup and view all the answers

What is thermal shock?

<p>When metal is subjected to a sudden change in temperature</p> Signup and view all the answers

What is the effect of rapid temperature changes on boilers?

<p>It causes thermal shock</p> Signup and view all the answers

Why is it important to avoid rapid heating of cold boilers?

<p>To avoid thermal shock</p> Signup and view all the answers

What can cause a rapid drop in temperature in boilers?

<p>Introducing cold water to a hot boiler</p> Signup and view all the answers

What should an operator do if abnormal conditions occur during the light-off or warm-up period of a boiler?

<p>Shut down the boiler immediately and close the main and pilot test firing valves</p> Signup and view all the answers

Why may slight smoking occur during the warm-up period of a cold oil-fired boiler?

<p>The furnace temperature is not yet high enough to vaporize the incoming fuel oil immediately and completely</p> Signup and view all the answers

What should be done if slight smoking persists after the boiler is warmed up?

<p>Ensure the atomizing air or atomizing steam is at the correct pressure, and then take the burner out of service if necessary</p> Signup and view all the answers

What is the purpose of paying attention to boiler warm-up rates?

<p>To ensure the safety and long life of boilers</p> Signup and view all the answers

What should be done before restarting a boiler after an abnormal condition has been identified and corrected?

<p>Verify that the problem has been corrected before restarting the boiler</p> Signup and view all the answers

Which of the following conditions is not typically encountered during the warm-up period of a boiler?

<p>Abnormal pressure</p> Signup and view all the answers

What should be done to ensure that combustion is entirely complete during the warm-up period of a cold oil-fired boiler?

<p>Wait for the furnace temperature to rise</p> Signup and view all the answers

What is the primary reason for paying attention to boiler warm-up rates?

<p>To minimize the risk of premature boiler failure</p> Signup and view all the answers

What can be a source of cold water that can cause thermal shock to a steam heating boiler?

<p>Cool return water from a condensate source</p> Signup and view all the answers

What is the purpose of warming up a boiler slowly?

<p>To prevent thermal shock and uneven expansion</p> Signup and view all the answers

What factors affect the rate at which a boiler can be brought up to its normal operating temperature and pressure?

<p>All of the above</p> Signup and view all the answers

What is the recommended rate of temperature increase for larger boilers to prevent thermal shock?

<p>55°C per hour</p> Signup and view all the answers

What should be checked during the boiler warm-up process?

<p>All of the above</p> Signup and view all the answers

Why should the firing rate be kept on manual low-fire control during the boiler warm-up process?

<p>To prevent thermal shock and ensure safe operation</p> Signup and view all the answers

What should be done to the boiler water level control system after the boiler is started?

<p>It should be placed on automatic</p> Signup and view all the answers

Why should the boiler be continually monitored during the warm-up process?

<p>To detect any signs of poor combustion or thermal shock</p> Signup and view all the answers

What should be done when the boiler pressure approaches its normal pressure or temperature set point?

<p>The firing rate control should be switched to automatic</p> Signup and view all the answers

What should be verified after the boiler warm-up process is complete?

<p>The boiler is performing as expected</p> Signup and view all the answers

medium What happens to the combustion process in a cold oil-fired boiler when it is first started?

<p>Combustion is incomplete until the furnace heats up</p> Signup and view all the answers

What is a normal condition encountered during the warm-up period of a boiler?

<p>Slight smoking</p> Signup and view all the answers

Why is it important to pay attention to boiler warm-up rates?

<p>To prevent thermal shock and premature boiler failure</p> Signup and view all the answers

What should be done if an abnormal condition occurs during the light-off or warm-up period of a boiler?

<p>Shut down the boiler immediately and identify the cause</p> Signup and view all the answers

What should be checked before restarting a boiler after an abnormal condition has been identified and corrected?

<p>All valves, including the main and pilot firing valves</p> Signup and view all the answers

What is a common condition that may disappear after the boiler is hot?

<p>Slight smoking and condensation</p> Signup and view all the answers

What should be done if an atomizing air or steam pressure is incorrect?

<p>Check and adjust the atomizing air or steam pressure</p> Signup and view all the answers

What is recommended by the ASME VI Recommended Rules for the Care and Operation of Heating Boilers in case of abnormal conditions?

<p>Shut down the boiler immediately and identify the cause</p> Signup and view all the answers

What is the primary cause of condensation in boilers?

<p>Water vapor in the flue gases contacting the cold heating surfaces</p> Signup and view all the answers

Why is it important to know the damage caused by cold start conditions?

<p>To avoid uneven expansion and thermal shock</p> Signup and view all the answers

What is the effect of scale buildup on the furnace and firetubes?

<p>It insulates the furnace tube and firetubes from the cooling effect of the boiler water</p> Signup and view all the answers

What occurs when metal is subjected to a sudden change in temperature?

<p>Internal stress and thermal shock</p> Signup and view all the answers

Why is it important to avoid rapid heating of cold boilers?

<p>To avoid thermal shock and uneven expansion</p> Signup and view all the answers

What is the effect of high firing rates on firetube boilers?

<p>Rapid warming up and uneven expansion</p> Signup and view all the answers

Why is it essential to ensure combustion is entirely complete during the warm-up period?

<p>To avoid thermal shock and uneven expansion</p> Signup and view all the answers

What is the recommended approach to starting up a cold boiler?

<p>Gradual warming up to prevent thermal shock</p> Signup and view all the answers

What is the typical consequence of uneven expansion in firetube boilers?

<p>Leakage and premature boiler failure</p> Signup and view all the answers

Why is it important to monitor the boiler during the warm-up process?

<p>To prevent thermal shock and uneven expansion</p> Signup and view all the answers

What is a common source of cold water that can cause thermal shock to a steam heating boiler?

<p>All of the above</p> Signup and view all the answers

What is the primary reason for warming up a boiler slowly?

<p>To prevent thermal shock and allow gradual thermal expansion</p> Signup and view all the answers

What factors affect the rate at which a boiler can be brought up to its normal operating temperature and pressure?

<p>All of the above</p> Signup and view all the answers

What is the recommended rate of temperature increase for larger boilers to prevent thermal shock?

<p>55°C per hour</p> Signup and view all the answers

What should be checked during the boiler warm-up process?

<p>All of the above</p> Signup and view all the answers

Why should the firing rate be kept on manual low-fire control during the boiler warm-up process?

<p>To reduce the risk of thermal shock</p> Signup and view all the answers

What should be done to the boiler water level control system after the boiler is started?

<p>It should be placed on automatic</p> Signup and view all the answers

Why should the boiler be continually monitored during the warm-up process?

<p>To prevent thermal shock and uneven expansion</p> Signup and view all the answers

What should be done when the boiler pressure approaches its normal pressure or temperature set point?

<p>Switch the firing rate control to automatic</p> Signup and view all the answers

What should be verified after the boiler warm-up process is complete?

<p>All of the above</p> Signup and view all the answers

HARD What is the primary reason for paying attention to boiler warm-up rates as prescribed by boiler manufacturers?

<p>To ensure the safety and long life of boilers</p> Signup and view all the answers

What should an operator do if an abnormal condition occurs during the light-off or warm-up period of a boiler?

<p>Shut down the boiler immediately and close the main and pilot test firing valves</p> Signup and view all the answers

What is a common condition that may disappear after the boiler is hot during the warm-up period?

<p>Condensation</p> Signup and view all the answers

What is the recommended approach to starting up a cold boiler?

<p>Slowly warming up the boiler to prevent thermal shock</p> Signup and view all the answers

What is the primary cause of condensation in boilers during the warm-up period?

<p>Cold start conditions</p> Signup and view all the answers

What should be checked before restarting a boiler after an abnormal condition has been identified and corrected?

<p>Boiler water level control system</p> Signup and view all the answers

What is the primary purpose of warming up a boiler slowly?

<p>To prevent thermal shock and allow for gradual thermal expansion</p> Signup and view all the answers

What is the effect of rapid temperature changes on boilers?

<p>Thermal shock and potential boiler failure</p> Signup and view all the answers

What is the purpose of ensuring that combustion is entirely complete during the warm-up period of a cold oil-fired boiler?

<p>To prevent smoking and ensure safe operation</p> Signup and view all the answers

What is the recommended rate of temperature increase for larger boilers to prevent thermal shock?

<p>55°C per hour</p> Signup and view all the answers

What should be checked during the boiler warm-up process?

<p>The flame pattern, furnace draft pressures, and other parameters</p> Signup and view all the answers

What is the primary reason for paying attention to boiler warm-up rates?

<p>To prevent thermal shock and allow for gradual thermal expansion</p> Signup and view all the answers

What should be done when the boiler pressure approaches its normal pressure or temperature set point?

<p>Switch the firing rate control to automatic</p> Signup and view all the answers

What is the effect of rapid temperature changes on boilers?

<p>Increased thermal shock</p> Signup and view all the answers

What should be done before restarting a boiler after an abnormal condition has been identified and corrected?

<p>Verify that the boiler is performing 'as expected' and enter a summary of the startup events in the daily log</p> Signup and view all the answers

What is the primary cause of condensation in boilers?

<p>Cold start conditions</p> Signup and view all the answers

What should be done to prevent thermal shock in steam heating boilers?

<p>Bypass part of the flow around the boiler until the water temperature difference between the supply and return lines has reached its normal operating value</p> Signup and view all the answers

What is the typical consequence of uneven expansion in firetube boilers?

<p>Tube failure or damage</p> Signup and view all the answers

What is the primary reason for the formation of tiny cracks in the metal of a boiler?

<p>Rapid temperature changes</p> Signup and view all the answers

What is the consequence of rapid heating of a cold boiler?

<p>Thermal shock and refractory damage</p> Signup and view all the answers

What is the effect of scale buildup on the furnace and firetubes?

<p>Insulation of the furnace tube and firetubes</p> Signup and view all the answers

What is the primary reason for avoiding rapid heating of cold boilers?

<p>To prevent thermal shock and refractory damage</p> Signup and view all the answers

What is the consequence of uneven expansion in firetube boilers?

<p>Leakage and premature boiler failure</p> Signup and view all the answers

What is the purpose of adjusting the air-fuel ratio in a boiler?

<p>To prevent smoking</p> Signup and view all the answers

What is the primary cause of condensation in boilers?

<p>Cold boiler surfaces</p> Signup and view all the answers

What is the effect of high firing rates on firetube boilers?

<p>Thermal shock and refractory damage</p> Signup and view all the answers

What is the recommended approach to starting up a cold boiler?

<p>Warming up the boiler slowly</p> Signup and view all the answers

What is the consequence of sudden changes in temperature in boilers?

<p>Thermal shock and internal stress</p> Signup and view all the answers

Match the following conditions encountered during the warm-up period of a boiler with their corresponding description:

<p>Slight smoking = Ensured by correct pressure of atomizing air or steam and correct fuel pressure. Condensation = Common condition that may disappear after the boiler is hot Abnormal condition = Should be shut down immediately and investigated before restarting the boiler Normal cold start condition = Ensured by following ASME VI Recommended Rules</p> Signup and view all the answers

Match the following consequences of boiler operation with their corresponding reasons:

<p>Incomplete combustion = Cold oil-fired boiler not yet at high enough temperature Leaks and premature boiler failure = Rapid heating of cold boilers Correct fuel pressure = Important for avoiding smoking during the warm-up period Atomizing air or steam at correct pressure = Ensures complete combustion during the warm-up period</p> Signup and view all the answers

Match the following actions with their corresponding situations:

<p>Shut down the boiler and close the main and pilot test firing valves = Abnormal condition during the light-off or warm-up period Check the fuel pressure and atomizing air or steam = Smoking persists after the boiler is warmed up Restart the boiler after correcting the problem = Abnormal condition has been identified and corrected Ensure correct assembly of the burner nozzle = Slight smoking during the warm-up period</p> Signup and view all the answers

Match the following guidelines with their corresponding sources:

<p>Recommended rules for the care and operation of heating boilers = ASME VI Correct warm-up rates = Boiler manufacturers' guidelines Immediate shut down in case of abnormal conditions = ASME VI Recommended Rules Normal cold start conditions = Boiler operation guidelines</p> Signup and view all the answers

Match the following terms with their corresponding definitions:

<p>Thermal shock = Damage caused by rapid temperature changes in boilers Scale buildup = Hazardous condition affecting furnace and firetubes Cold start condition = Boiler operation from a cold state Uneven expansion = Common cause of leaks and premature boiler failure</p> Signup and view all the answers

Match the following scenarios with their corresponding consequences:

<p>Cold water entering the boiler = Thermal shock to a steam heating boiler Rapid heating of a cold boiler = Leaks and premature boiler failure Incomplete combustion during the warm-up period = Slight smoking from the stack High firing rates = Uneven expansion in firetube boilers</p> Signup and view all the answers

Match the following actions with their corresponding goals:

<p>Paying attention to boiler warm-up rates = Ensuring safety and long life of boilers Monitoring the boiler during the warm-up process = Early detection of abnormal conditions Following ASME VI Recommended Rules = Ensuring safe and proper boiler operation Warming up a boiler slowly = Preventing thermal shock and leaks</p> Signup and view all the answers

Match the following conditions with their corresponding effects on boilers:

<p>Rapid temperature changes = Thermal shock and leaks Sudden changes in temperature = Damage to boiler metal Inadequate combustion during the warm-up period = Slight smoking from the stack Abnormal conditions during the light-off or warm-up period = Boiler shut down and correction of the problem</p> Signup and view all the answers

Match the following boiler components with their potential problems during startup:

<p>Furnace = Poor combustion Refractory = Hot spots Feedwater pumps = Abnormal operation Water level control system = Improper maintenance</p> Signup and view all the answers

Match the following precautions with their purpose during boiler startup:

<p>Slowing down boiler warm-up = Preventing thermal shock Keeping boilers free from scale buildup = Preventing uneven expansion Bypassing part of the cool return flow = Protecting boiler from cold water Monitoring boiler during warm-up = Identifying abnormal conditions</p> Signup and view all the answers

Match the following boiler conditions with their potential consequences:

<p>Rapid temperature changes = Thermal shock Scale buildup = Uneven expansion Cold water = Thermal shock High firing rates = Uneven expansion</p> Signup and view all the answers

Match the following boiler startup procedures with their purposes:

<p>Warming up boilers slowly = Preventing thermal shock Switching firing rate control to automatic = Maintaining normal operating pressure Monitoring boiler during warm-up = Identifying abnormal conditions Verifying boiler performance after startup = Ensuring normal operation</p> Signup and view all the answers

Match the following boiler components with their potential effects on combustion:

<p>Furnace draft pressures = Combustion gas flow Flame pattern = Combustion efficiency Atomizing air or steam pressure = Fuel atomization Water level control system = Steam pressure</p> Signup and view all the answers

Match the following boiler startup conditions with their potential causes:

<p>Slight smoking = Cold oil-fired boiler Abnormal conditions = Improper combustion Hot spots = Refractory damage Condensation = Cold boiler surface</p> Signup and view all the answers

Match the following boiler components with their normal operating conditions:

<p>Furnace draft pressures = Historical data Water level control system = Automatic operation Feedwater pumps = Normal operation Low water level alarm = Proper operation</p> Signup and view all the answers

Match the following boiler startup procedures with their recommended rates:

<p>Boiler warm-up = 55°C per hour Firing rate control = Manual low-fire control Water temperature increase = 55°C per hour Drum pressure increase = 210 kPa per hour</p> Signup and view all the answers

Match the following boiler components with their potential effects on boiler performance:

<p>Scale buildup = Reduced efficiency Refractory damage = Reduced heat transfer Feedwater pumps = Increased pressure Water level control system = Maintained steam pressure</p> Signup and view all the answers

Match the following boiler startup conditions with their recommended actions:

<p>Abnormal condition = Identify and correct Slight smoking = Verify proper operation Hot spots = Monitor boiler surface Cold water = Bypass part of the flow</p> Signup and view all the answers

Match the following boiler components with their characteristics:

<p>Firetube boilers = Larger water content Packaged boilers with economizers = Colder boilers Colder boilers = More likely to experience condensation</p> Signup and view all the answers

Match the following boiler conditions with their consequences:

<p>Rapid heating = Thermal shock and refractory damage Cold start = Leakage and premature boiler failure High firing rates = Uneven expansion and leakage Scale buildup = Increased metal temperatures</p> Signup and view all the answers

Match the following boiler components with their effects:

<p>Furnace tube = Temperature rises at a faster rate Firetubes = Temperature differential and uneven expansion Tube sheets = Localized stress and cracking Reversing chamber doors = Water runs out when condensation occurs</p> Signup and view all the answers

Match the following boiler conditions with their causes:

<p>Thermal shock = Rapid temperature changes Uneven expansion = Temperature differential between shell and tubes Condensation = Cold boiler surfaces and flue gas Leakage = Cracked welds and loose firetube ends</p> Signup and view all the answers

Match the following boiler operations with their effects:

<p>High firing rates = Rapid heating and thermal shock Cold start = Condensation and uneven expansion Slow warm-up = Reduced thermal shock and stress Scale buildup = Increased metal temperatures and uneven expansion</p> Signup and view all the answers

Match the following boiler components with their characteristics:

<p>Furnace = Higher temperature than firetubes Firetubes = Uneven expansion and thermal shock Tube sheets = Localized stress and cracking Reversing chamber doors = Water leakage during condensation</p> Signup and view all the answers

Match the following boiler conditions with their consequences:

<p>Rapid temperature changes = Thermal shock and stress Cold start = Condensation and uneven expansion High firing rates = Rapid heating and thermal shock Scale buildup = Increased metal temperatures and uneven expansion</p> Signup and view all the answers

Match the following boiler operations with their effects:

<p>Slow warm-up = Reduced thermal shock and stress High firing rates = Rapid heating and thermal shock Cold start = Condensation and uneven expansion Scale buildup = Increased metal temperatures and uneven expansion</p> Signup and view all the answers

Match the following boiler components with their characteristics:

<p>Firetube boilers = Furnace tube temperature rises faster Packaged boilers with economizers = Colder boilers and condensation Colder boilers = More likely to experience condensation</p> Signup and view all the answers

Match the following boiler conditions with their causes:

<p>Thermal shock = Rapid temperature changes and uneven expansion Uneven expansion = Temperature differential between shell and tubes Condensation = Cold boiler surfaces and flue gas Leakage = Cracked welds and loose firetube ends</p> Signup and view all the answers

Study Notes

Boiler Startup and Warm-Up

  • Operators must be aware of the effects of rapid heating on boiler metal and the importance of proper warm-up rates to prevent leaks, premature boiler failure, and ensure safety.

Abnormal Conditions During Startup

  • Abnormal conditions may occur during light-off or warm-up period, requiring immediate shutdown and correction of the problem before restarting the boiler.

Normal Cold Start Conditions

  • Slight smoking may occur during startup due to incomplete combustion, but should disappear after the boiler is hot.
  • Condensation may occur in cold boilers, especially firetube boilers, causing water to run out of the reversing chamber doors, but will stop when the boiler is hot.

Harmful Cold Start Conditions

  • Rapid heating can cause thermal shock, uneven expansion, and refractory damage, leading to leakage, premature boiler failure, and costly repairs.
  • High firing rates can cause uneven expansion, resulting in localized stress on the tube sheets and potentially cracking the welds or loosening the firetube ends.

Preventing Damage

  • Always warm up boilers slowly to prevent thermal shock and uneven expansion.
  • Keep boilers free from scale buildup to prevent insulation and increased metal temperatures.
  • Avoid sudden changes in temperature to prevent thermal shock.
  • Take precautions to prevent cold water from entering a hot boiler, especially in steam heating systems.

Boiler Warm-Up

  • The rate of warm-up depends on the physical size of the boiler, boiler water content, boiler design, and how long the boiler has been shut down.
  • A general rule of thumb is to not increase the boiler water temperature at a rate greater than 55°C per hour to prevent thermal shock and allow for gradual thermal expansion.
  • Consult manufacturer specifications for specific warm-up rates.

Monitoring Boiler Warm-Up

  • Continually monitor the boiler during warm-up and pressurizing, checking for:
    • Symmetrical and turbulent flame pattern
    • Signs of poor combustion (flame too rich or too lean)
    • "Hot spots" on the metal surface
    • Furnace draft pressures
    • Fan and feedwater pump operation
    • Water level in the boiler
    • Low water level alarm and cut-off operation
    • Proper operation of the boiler as expected.

Boiler Startup and Warm-Up

  • Operators must be aware of the effects of rapid heating on boiler metal and the importance of proper warm-up rates to prevent leaks, premature boiler failure, and ensure safety.

Abnormal Conditions During Startup

  • Abnormal conditions may occur during light-off or warm-up period, requiring immediate shutdown and correction of the problem before restarting the boiler.

Normal Cold Start Conditions

  • Slight smoking may occur during startup due to incomplete combustion, but should disappear after the boiler is hot.
  • Condensation may occur in cold boilers, especially firetube boilers, causing water to run out of the reversing chamber doors, but will stop when the boiler is hot.

Harmful Cold Start Conditions

  • Rapid heating can cause thermal shock, uneven expansion, and refractory damage, leading to leakage, premature boiler failure, and costly repairs.
  • High firing rates can cause uneven expansion, resulting in localized stress on the tube sheets and potentially cracking the welds or loosening the firetube ends.

Preventing Damage

  • Always warm up boilers slowly to prevent thermal shock and uneven expansion.
  • Keep boilers free from scale buildup to prevent insulation and increased metal temperatures.
  • Avoid sudden changes in temperature to prevent thermal shock.
  • Take precautions to prevent cold water from entering a hot boiler, especially in steam heating systems.

Boiler Warm-Up

  • The rate of warm-up depends on the physical size of the boiler, boiler water content, boiler design, and how long the boiler has been shut down.
  • A general rule of thumb is to not increase the boiler water temperature at a rate greater than 55°C per hour to prevent thermal shock and allow for gradual thermal expansion.
  • Consult manufacturer specifications for specific warm-up rates.

Monitoring Boiler Warm-Up

  • Continually monitor the boiler during warm-up and pressurizing, checking for:
    • Symmetrical and turbulent flame pattern
    • Signs of poor combustion (flame too rich or too lean)
    • "Hot spots" on the metal surface
    • Furnace draft pressures
    • Fan and feedwater pump operation
    • Water level in the boiler
    • Low water level alarm and cut-off operation
    • Proper operation of the boiler as expected.

Boiler Startup and Warm-Up

  • Operators must be aware of the effects of rapid heating on boiler metal and the importance of proper warm-up rates to prevent leaks, premature boiler failure, and ensure safety.

Abnormal Conditions During Startup

  • Abnormal conditions may occur during light-off or warm-up period, requiring immediate shutdown and correction of the problem before restarting the boiler.

Normal Cold Start Conditions

  • Slight smoking may occur during startup due to incomplete combustion, but should disappear after the boiler is hot.
  • Condensation may occur in cold boilers, especially firetube boilers, causing water to run out of the reversing chamber doors, but will stop when the boiler is hot.

Harmful Cold Start Conditions

  • Rapid heating can cause thermal shock, uneven expansion, and refractory damage, leading to leakage, premature boiler failure, and costly repairs.
  • High firing rates can cause uneven expansion, resulting in localized stress on the tube sheets and potentially cracking the welds or loosening the firetube ends.

Preventing Damage

  • Always warm up boilers slowly to prevent thermal shock and uneven expansion.
  • Keep boilers free from scale buildup to prevent insulation and increased metal temperatures.
  • Avoid sudden changes in temperature to prevent thermal shock.
  • Take precautions to prevent cold water from entering a hot boiler, especially in steam heating systems.

Boiler Warm-Up

  • The rate of warm-up depends on the physical size of the boiler, boiler water content, boiler design, and how long the boiler has been shut down.
  • A general rule of thumb is to not increase the boiler water temperature at a rate greater than 55°C per hour to prevent thermal shock and allow for gradual thermal expansion.
  • Consult manufacturer specifications for specific warm-up rates.

Monitoring Boiler Warm-Up

  • Continually monitor the boiler during warm-up and pressurizing, checking for:
    • Symmetrical and turbulent flame pattern
    • Signs of poor combustion (flame too rich or too lean)
    • "Hot spots" on the metal surface
    • Furnace draft pressures
    • Fan and feedwater pump operation
    • Water level in the boiler
    • Low water level alarm and cut-off operation
    • Proper operation of the boiler as expected.

Boiler Startup and Warm-Up

  • Operators must be aware of the effects of rapid heating on boiler metal and the importance of proper warm-up rates to prevent leaks, premature boiler failure, and ensure safety.

Abnormal Conditions During Startup

  • Abnormal conditions may occur during light-off or warm-up period, requiring immediate shutdown and correction of the problem before restarting the boiler.

Normal Cold Start Conditions

  • Slight smoking may occur during startup due to incomplete combustion, but should disappear after the boiler is hot.
  • Condensation may occur in cold boilers, especially firetube boilers, causing water to run out of the reversing chamber doors, but will stop when the boiler is hot.

Harmful Cold Start Conditions

  • Rapid heating can cause thermal shock, uneven expansion, and refractory damage, leading to leakage, premature boiler failure, and costly repairs.
  • High firing rates can cause uneven expansion, resulting in localized stress on the tube sheets and potentially cracking the welds or loosening the firetube ends.

Preventing Damage

  • Always warm up boilers slowly to prevent thermal shock and uneven expansion.
  • Keep boilers free from scale buildup to prevent insulation and increased metal temperatures.
  • Avoid sudden changes in temperature to prevent thermal shock.
  • Take precautions to prevent cold water from entering a hot boiler, especially in steam heating systems.

Boiler Warm-Up

  • The rate of warm-up depends on the physical size of the boiler, boiler water content, boiler design, and how long the boiler has been shut down.
  • A general rule of thumb is to not increase the boiler water temperature at a rate greater than 55°C per hour to prevent thermal shock and allow for gradual thermal expansion.
  • Consult manufacturer specifications for specific warm-up rates.

Monitoring Boiler Warm-Up

  • Continually monitor the boiler during warm-up and pressurizing, checking for:
    • Symmetrical and turbulent flame pattern
    • Signs of poor combustion (flame too rich or too lean)
    • "Hot spots" on the metal surface
    • Furnace draft pressures
    • Fan and feedwater pump operation
    • Water level in the boiler
    • Low water level alarm and cut-off operation
    • Proper operation of the boiler as expected.

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