Boiler Warm-Up and Cold Start Conditions

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What is the primary concern when starting a boiler from cold?

Ensuring rapid heating of boiler metal

Preventing boiler failure

Adhering to boiler warm-up rates prescribed by manufacturers (correct)

Minimizing energy consumption

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

Shut down the boiler immediately and close the main and pilot test firing valves (correct)

Consult with a senior engineer before taking action

Monitor the situation closely and adjust as needed

Increase the warm-up rate to compensate

Why do new hazards appear during startup of a boiler plant?

Because of the rapid changes in plant conditions and related hazards (correct)

Because of the complexity of the boiler's design

Because of inadequate training of operators

Because of the boiler's age and wear

What is the purpose of the recommended boiler warm-up rates?

To prevent leaks and premature boiler failure Signup and view all the answers

What is the recommended course of action after identifying the cause of trouble during startup?

Correct the problem before restarting the boiler Signup and view all the answers

What is the primary objective of the recommended procedures for boiler startup?

To ensure the safety and long life of boilers Signup and view all the answers

What is the main cause of thermal shock in metal?

Sudden change in temperature Signup and view all the answers

What is the effect of thermal shock on boiler tubes?

Formation of tiny cracks in the tubes Signup and view all the answers

What is a normal condition during the warm-up period of a cold oil-fired boiler?

Slight smoking Signup and view all the answers

Why is it important to warm up boilers slowly?

To prevent thermal shock Signup and view all the answers

What may occur when a cold boiler is first started, especially in firetube boilers with large water content?

Flue gas condensation Signup and view all the answers

What is the result of rapid heating during a cold start in firetube boilers?

Thermal shock and refractory damage Signup and view all the answers

What is the maximum recommended temperature increase per hour for boiler water?

55°C per hour Signup and view all the answers

What is the purpose of ensuring the atomizing air or steam is at the correct pressure during a cold start?

To ensure complete combustion Signup and view all the answers

What is the purpose of bypassing part of the flow around the boiler in a hot water heating system?

To prevent thermal shock Signup and view all the answers

What is the effect of cold make-up water on steam boilers?

It causes thermal shock Signup and view all the answers

What is the effect of scale buildup on the furnace and firetubes during a cold start?

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

What should be done if a boiler continues to smoke after being warmed up?

Take the burner out of service Signup and view all the answers

What is the recommended firing rate after ignition?

Manual low-fire control Signup and view all the answers

What is the main factor affecting the rate at which a boiler can be brought up to its normal operating temperature and pressure?

All of the above Signup and view all the answers

What is the effect of high firing rates during a cold start in firetube boilers?

Rapid heating and uneven expansion Signup and view all the answers

Why is it important to keep make-up water sources at normal operating temperature?

To prevent thermal shock Signup and view all the answers

What is the consequence of uneven expansion in firetube boilers during a cold start?

Premature boiler failure and costly repairs Signup and view all the answers

What should be checked if a boiler is still smoking after the warm-up period?

All of the above Signup and view all the answers

What is the purpose of the water level control system in steam boilers?

To monitor water level Signup and view all the answers

What is the result of a heavily smoking burner receiving additional combustion air?

An explosive condition Signup and view all the answers

What is the primary purpose of checking the furnace draft pressures during boiler startup?

To verify that combustion gases are passing normally through the furnace and flue gas passages Signup and view all the answers

What is the recommended action if the boiler has a continuous pilot?

Allow at least 5 minutes for the furnace to purge naturally with the pilot and main gas valves shut Signup and view all the answers

What is the purpose of reviewing the manufacturer recommendations for burner and boiler startup?

To follow the specific startup procedures for the boiler Signup and view all the answers

What is the purpose of the boiler control switch?

To turn the boiler on or off Signup and view all the answers

What should the Power Engineer do after boiler pressure approaches its normal pressure or temperature set point?

Switch the firing rate control to automatic Signup and view all the answers

What is the purpose of the furnace purge during boiler startup?

To remove any combustible gases from the furnace Signup and view all the answers

What should the Power Engineer do if the boiler has a gas-fired atmospheric burner and a continuous pilot?

Allow at least 5 minutes for the furnace to purge naturally with the pilot and main gas valves shut Signup and view all the answers

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

To intervene if necessary to prevent accidents or damage Signup and view all the answers

What should the Power Engineer do before starting the boiler?

Prepare the boiler plant auxiliaries according to site-specific procedures Signup and view all the answers

What is the purpose of the daily log during boiler startup?

To enter a summary of the startup events Signup and view all the answers

What is the purpose of purging the boiler for a given time period?

To remove any air from the combustion chamber Signup and view all the answers

What should be done during the main burner ignition trial?

The main burner safety shut-off valves should open Signup and view all the answers

Why should the boiler be fired at low fire during warm-up?

To limit the differential expansion between the furnace tube and firetubes Signup and view all the answers

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

The boiler for leaks Signup and view all the answers

What should be done when the burner shuts down?

The water pressure on the tridicator gauge should be checked Signup and view all the answers

What is the purpose of the try lever and pop tests?

To check the safety relief valve for evidence of leaking Signup and view all the answers

What should be done when cutting in a hot water boiler in a multiple boiler plant?

The valve in the connecting line between the boiler and the tank should be closed Signup and view all the answers

Why should the boiler be warmed up slowly?

To limit the differential expansion between the furnace tube and firetubes Signup and view all the answers

What should be done with the stop valves in the supply and return lines to the boiler during warm-up?

They should be closed Signup and view all the answers

What should be entered in the log book after startup?

The date and time of startup Signup and view all the answers

What is the main reason to ensure sufficient space in the expansion tank during warmup?

To accommodate the expanded water produced during warmup Signup and view all the answers

What should be done when the stop valve at the boiler outlet is closed?

Close the valve in the return line Signup and view all the answers

How should the stop valve on the boiler outlet be opened when the boiler water reaches the supply main temperature?

Open the valve slowly until it is fully open Signup and view all the answers

What is the purpose of cracking open the outlet valve during the alternative warmup method?

To establish flow through the cold boiler without causing shock Signup and view all the answers

Why is it important to plan ahead for heating loads?

To ensure the on-line boilers have sufficient capacity to heat the extra boiler Signup and view all the answers

What is the purpose of the furnace purge during the safe startup of a steam boiler?

To purge the furnace of combustible gases Signup and view all the answers

What is the recommended approach to warming up steam lines and headers?

Simultaneously with the boiler Signup and view all the answers

What is the purpose of the block valve at the outlet of the boiler?

To isolate the boiler from the steam header Signup and view all the answers

What happens when steam enters the cold steam piping during warmup?

It condenses heavily at first, but decreasingly as the steam piping comes up to temperature Signup and view all the answers

Why is it essential to warm up the steam header with the boiler stop, header stop, and drain valves open?

To ensure the steam piping and boiler warm and pressurize at the same rate Signup and view all the answers

What is the purpose of opening the main steam shutoff valve during the simultaneous warm-up procedure of a steam boiler and its steam piping?

To permit the flow of steam into the steam piping Signup and view all the answers

Why is it important to open the boiler drum vent during the warm-up procedure?

To release corrosive dissolved gases from the boiler water Signup and view all the answers

What is the recommended firing rate during the initial warm-up period of a steam boiler?

Low fire Signup and view all the answers

What is the purpose of inspecting the boiler frequently during the warm-up period?

To check for leakage at washout plugs, valves, handholes, and pipe connections Signup and view all the answers

When should the superheater vent be closed during the warm-up procedure?

When adequate flow of superheated steam is established Signup and view all the answers

What is the purpose of closing the low point drains during the warm-up procedure?

To prevent excessive steam from blowing from the drains Signup and view all the answers

When should the main disconnect switch be closed during the warm-up procedure?

When the pilot flame is established Signup and view all the answers

What is the purpose of reviewing manufacturer recommendations for burner and boiler startup during the warm-up procedure?

To ensure the correct sequence of startup Signup and view all the answers

Why is it important to open the trap bypasses during the warm-up procedure?

To allow the release of condensate from the steam piping Signup and view all the answers

What is the purpose of performing operating control and safety limit checks during the warm-up procedure?

To verify the proper operation of the boiler controls and safety limits Signup and view all the answers

During the startup of a boiler, what is a significant challenge to a Power Engineer’s knowledge and skills?

Identifying and addressing changing hazards Signup and view all the answers

What is the primary reason operators need to pay attention to boiler warm-up rates during startup?

To prevent boiler failure and ensure safety Signup and view all the answers

If abnormal conditions occur during the light-off or warm-up period, what should the operator do?

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

Why is it important to correct the problem before restarting the boiler after an abnormal condition occurs?

To prevent further damage to the boiler Signup and view all the answers

What is the primary concern during the boiler startup process?

Ensuring safety and preventing accidents Signup and view all the answers

Why is it essential to monitor the boiler during its warm-up period?

To prevent boiler failure and ensure safety Signup and view all the answers

What is the primary cause of thermal shock in boilers?

Rapid temperature changes Signup and view all the answers

What should be done to prevent thermal shock when starting a cold boiler?

Gradually warm up the boiler to prevent rapid temperature changes Signup and view all the answers

What is the recommended maximum temperature increase per hour for boiler water?

55°C Signup and view all the answers

What can cause thermal shock in steam heating boilers?

Cold make-up water Signup and view all the answers

Why is it important to keep boilers free from scale buildup?

To prevent thermal shock Signup and view all the answers

What is the result of rapid temperature changes in boilers?

Thermal shock and internal stress Signup and view all the answers

What should be done to protect a boiler from uneven expansion and thermal shock?

W warm up the boiler slowly Signup and view all the answers

What is the effect of thermal shock on boiler tubes?

Formation of tiny cracks in the metal Signup and view all the answers

Why is it important to warm up boilers slowly?

To prevent thermal shock and uneven expansion Signup and view all the answers

What is the primary concern when starting a boiler from cold?

Thermal shock and uneven expansion Signup and view all the answers

Why does condensation occur in firetube boilers during the cold start?

When the water vapour in the flue gases contacts the cold heating surfaces of the boiler Signup and view all the answers

What is the result of uneven expansion in firetube boilers during a cold start?

The tubes and furnace expansion is restricted, causing localized stress on the tube sheets Signup and view all the answers

Why is it important to avoid high firing rates during a cold start in firetube boilers?

To prevent thermal shock and refractory damage Signup and view all the answers

What is the recommended action if the burner continues to smoke after being warmed up?

Take the burner out of service and ensure the burner nozzle is clean and properly assembled Signup and view all the answers

Why is it important to avoid adding additional combustion air to a heavily smoking burner?

To prevent the formation of explosive conditions Signup and view all the answers

What is the effect of scale buildup on the furnace and firetubes during a cold start?

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

What is the purpose of ensuring the atomizing air or steam is at the correct pressure during a cold start?

To ensure complete combustion and reduce smoking Signup and view all the answers

Why is it important to warm up a cold oil-fired boiler slowly?

To prevent thermal shock and refractory damage Signup and view all the answers

What occurs when the water vapour in the flue gases contacts the cold heating surfaces of the boiler during a cold start?

The water vapour condenses, causing condensation Signup and view all the answers

What is a normal condition during the warm-up period of a cold oil-fired boiler?

Slight smoking from the stack Signup and view all the answers

What is the primary purpose of checking the furnace draft pressures during boiler startup?

To ensure the combustion gases are passing normally through the furnace and flue gas passages Signup and view all the answers

What should the Power Engineer do before starting the boiler?

Review the manufacturer's recommendations for burner and boiler startup Signup and view all the answers

What is the purpose of purging the boiler for a given time period during the startup procedure?

To allow for four combustion chamber air changes Signup and view all the answers

What should be done when cutting in a hot water boiler in a multiple boiler plant?

Raise the pressure to at least the minimum required static pressure for the cold system Signup and view all the answers

Why is it essential to monitor the boiler during the warm-up period?

To prevent the boiler from being left unattended during its warm-up period Signup and view all the answers

What is the purpose of the boiler control switch?

To turn the boiler on or off Signup and view all the answers

Why is it important to warm up the boiler slowly?

To prevent thermal shock and stress on the boiler metal Signup and view all the answers

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

Switch the firing rate control to automatic Signup and view all the answers

What should be done during the main burner ignition trial?

The main burner safety shut-off valves should be opened Signup and view all the answers

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

The burner operation and leaks Signup and view all the answers

What is the purpose of the furnace purge during the safe startup of a hot water boiler?

To allow the furnace to purge naturally with the pilot and main gas valves shut Signup and view all the answers

What is the recommended approach to starting a hot water boiler in a single boiler plant?

To prepare the boiler plant auxiliaries according to site-specific procedures Signup and view all the answers

What is the purpose of the try lever and pop tests?

To check the safety relief valve Signup and view all the answers

What should be done if the flame at low fire provides insufficient heat to reach normal operating temperature after 30 minutes?

Gradually increase the firing rate using the manual firing rate control Signup and view all the answers

What is the purpose of reviewing the manufacturer's recommendations for burner and boiler startup?

To follow the recommended procedures for startup to ensure safe and proper operation Signup and view all the answers

What is the purpose of raising the water temperature slowly during the warm-up process?

To ensure the entire water content of the system and boiler is warmed prior to increasing fuel input Signup and view all the answers

What should the Power Engineer do after the boiler has been started?

Enter a summary of the startup events in the daily log Signup and view all the answers

Why is it important to ensure the boiler is properly maintained during the warm-up period?

To prevent thermal shock and uneven expansion in the boiler Signup and view all the answers

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

Enter the required information in the log book Signup and view all the answers

What should be done when the burner shuts down?

Check the water pressure on the tridicator gauge Signup and view all the answers

What is the primary concern when warming up a steam boiler and its steam piping?

Preventing water hammer Signup and view all the answers

Why is it essential to warm up the steam header with the boiler stop, header stop, and drain valves open?

To warm the steam header and boiler simultaneously Signup and view all the answers

What should be done when the temperature of the boiler water reaches the temperature of the water in the supply main?

Open the stop valve on the boiler outlet slightly Signup and view all the answers

What is the purpose of having an ample air cushion in the expansion tank during warmup?

To provide a buffer for the expanded water Signup and view all the answers

What should be done when the cold boiler is at or near the system temperature?

Fully open the outlet valve Signup and view all the answers

What happens when steam enters the cold steam piping during warmup?

The steam condenses heavily Signup and view all the answers

What is the main benefit of warming up the boiler and steam lines simultaneously?

Preventing water hammer Signup and view all the answers

What should be done when the stop valve at the boiler outlet is closed?

Close the stop valve in the return line Signup and view all the answers

Why is it important to plan ahead for heating loads?

To have standby boilers warmed up prior to being required Signup and view all the answers

What is the purpose of ASME VI and VII guidelines for steam boilers?

To provide general guidelines for boiler startup Signup and view all the answers

What is the primary purpose of opening the boiler drum vent during the simultaneous warm-up procedure?

To release corrosive dissolved gases from the boiler water Signup and view all the answers

Why is it important to maintain low fire during the initial warm-up period of a steam boiler?

To prevent thermal shock and uneven expansion Signup and view all the answers

What should be done when the boiler pressure reaches 15 to 20 kPa during the warm-up procedure?

Close the drum vent valve Signup and view all the answers

What is the purpose of inspecting the boiler frequently during the warm-up period?

To check for leakage and observe burner operation Signup and view all the answers

When should the trap bypasses be closed during the warm-up procedure?

When the steam lines are warmed up and little condensate is blowing from the drains Signup and view all the answers

What is the purpose of preparing the steam plant auxiliaries during the simultaneous warm-up procedure?

To prepare the boiler feed pump, condensate return system, and other auxiliaries Signup and view all the answers

What should be done with the main disconnect switch during the simultaneous warm-up procedure?

Open it to supply power to the boiler Signup and view all the answers

Why is it important to ensure the boiler control switch is in the off position during the initial stages of the warm-up procedure?

To prevent the boiler from starting accidentally Signup and view all the answers

What should be done with the low point drains during the warm-up procedure?

Open them to release condensate as it forms Signup and view all the answers

What is the purpose of reviewing manufacturer recommendations for burner and boiler startup during the warm-up procedure?

To follow site-specific procedures and manufacturer guidelines Signup and view all the answers

Boiler Warm-Up and Cold Start Conditions

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Questions and Answers

What is the primary concern when starting a boiler from cold?

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

Why do new hazards appear during startup of a boiler plant?

What is the purpose of the recommended boiler warm-up rates?

What is the recommended course of action after identifying the cause of trouble during startup?

What is the primary objective of the recommended procedures for boiler startup?

What is the main cause of thermal shock in metal?

What is the effect of thermal shock on boiler tubes?

What is a normal condition during the warm-up period of a cold oil-fired boiler?

Why is it important to warm up boilers slowly?

What may occur when a cold boiler is first started, especially in firetube boilers with large water content?

What is the result of rapid heating during a cold start in firetube boilers?

What is the maximum recommended temperature increase per hour for boiler water?

What is the purpose of ensuring the atomizing air or steam is at the correct pressure during a cold start?

What is the purpose of bypassing part of the flow around the boiler in a hot water heating system?

What is the effect of cold make-up water on steam boilers?

What is the effect of scale buildup on the furnace and firetubes during a cold start?

What should be done if a boiler continues to smoke after being warmed up?

What is the recommended firing rate after ignition?

What is the main factor affecting the rate at which a boiler can be brought up to its normal operating temperature and pressure?

What is the effect of high firing rates during a cold start in firetube boilers?

Why is it important to keep make-up water sources at normal operating temperature?

What is the consequence of uneven expansion in firetube boilers during a cold start?

What should be checked if a boiler is still smoking after the warm-up period?

What is the purpose of the water level control system in steam boilers?

What is the result of a heavily smoking burner receiving additional combustion air?

What is the primary purpose of checking the furnace draft pressures during boiler startup?

What is the recommended action if the boiler has a continuous pilot?

What is the purpose of reviewing the manufacturer recommendations for burner and boiler startup?

What is the purpose of the boiler control switch?

What should the Power Engineer do after boiler pressure approaches its normal pressure or temperature set point?

What is the purpose of the furnace purge during boiler startup?

What should the Power Engineer do if the boiler has a gas-fired atmospheric burner and a continuous pilot?

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

What should the Power Engineer do before starting the boiler?

What is the purpose of the daily log during boiler startup?

What is the purpose of purging the boiler for a given time period?

What should be done during the main burner ignition trial?

Why should the boiler be fired at low fire during warm-up?

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

What should be done when the burner shuts down?

What is the purpose of the try lever and pop tests?

What should be done when cutting in a hot water boiler in a multiple boiler plant?

Why should the boiler be warmed up slowly?

What should be done with the stop valves in the supply and return lines to the boiler during warm-up?

What should be entered in the log book after startup?

What is the main reason to ensure sufficient space in the expansion tank during warmup?

What should be done when the stop valve at the boiler outlet is closed?

How should the stop valve on the boiler outlet be opened when the boiler water reaches the supply main temperature?

What is the purpose of cracking open the outlet valve during the alternative warmup method?

Why is it important to plan ahead for heating loads?

What is the purpose of the furnace purge during the safe startup of a steam boiler?

What is the recommended approach to warming up steam lines and headers?

What is the purpose of the block valve at the outlet of the boiler?

What happens when steam enters the cold steam piping during warmup?

Why is it essential to warm up the steam header with the boiler stop, header stop, and drain valves open?

What is the purpose of opening the main steam shutoff valve during the simultaneous warm-up procedure of a steam boiler and its steam piping?

Why is it important to open the boiler drum vent during the warm-up procedure?

What is the recommended firing rate during the initial warm-up period of a steam boiler?

What is the purpose of inspecting the boiler frequently during the warm-up period?

When should the superheater vent be closed during the warm-up procedure?

What is the purpose of closing the low point drains during the warm-up procedure?

When should the main disconnect switch be closed during the warm-up procedure?

What is the purpose of reviewing manufacturer recommendations for burner and boiler startup during the warm-up procedure?

Why is it important to open the trap bypasses during the warm-up procedure?

What is the purpose of performing operating control and safety limit checks during the warm-up procedure?

During the startup of a boiler, what is a significant challenge to a Power Engineer’s knowledge and skills?

What is the primary reason operators need to pay attention to boiler warm-up rates during startup?

If abnormal conditions occur during the light-off or warm-up period, what should the operator do?

Why is it important to correct the problem before restarting the boiler after an abnormal condition occurs?

What is the primary concern during the boiler startup process?

Why is it essential to monitor the boiler during its warm-up period?

What is the primary cause of thermal shock in boilers?

What should be done to prevent thermal shock when starting a cold boiler?

What is the recommended maximum temperature increase per hour for boiler water?

What can cause thermal shock in steam heating boilers?