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#BoilerManual #ProtectingPressureParts #Section10 #Page11

Answers for protecting pressure parts

1. The two ways you can minimize overheating, thermal stress and corrosion in your boiler are:

........ 1. ___Balance the firing rate to the fluid flow.

........ 2. ___Monitor metal temperatures throughout the system. This will help avoid temperature imbalances which cause thermal stresses and corrosion.

2. The water should be a minimum of 70 F and must be within 100 F of boiler metal temperature.

3. It is very important that you DO NOT suddenly increase air flow to a tripped burner. Maintain the same air flow as at the time of the trip for an extended period of time. Prior to re-establishing the burner flame, you may have to post-purge the burner.

4. Dark and smokey flames indicate that fuel is not being completely burned. Once again, DO NOT suddenly increase air flow to the burners. Rather, you should reduce the FUEL FLOW so that it matches the existing air flow.

5. Anytime the boiler is fired, the furnace must have at least 33% of rated full load flow in the tube circuits.

6. You should make sure that the rate of change in the fluid temperature at the convection pass outlet does not exceed 200 F per hour. Any rate higher than this will lead to thermal stress problems.

7. You can detect a tube failure by monitoring the high makeup flow rate or by a discrepancy between feedwater flow and main steam flow.

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#BoilerManual #ProtectingPressureParts #Section10 #Page11

Answers for protecting pressure parts

1. The two ways you can minimize overheating, thermal stress and corrosion in your boiler are:

........ 1. ___Balance the firing rate to the fluid flow.

........ 2. ___Monitor metal temperatures throughout the system. This will help avoid temperature imbalances which cause thermal stresses and corrosion.

2. The water should be a minimum of 70 F and must be within 100 F of boiler metal temperature.

3. It is very important that you DO NOT suddenly increase air flow to a tripped burner. Maintain the same air flow as at the time of the trip for an extended period of time. Prior to re-establishing the burner flame, you may have to post-purge the burner.

4. Dark and smokey flames indicate that fuel is not being completely burned. Once again, DO NOT suddenly increase air flow to the burners. Rather, you should reduce the FUEL FLOW so that it matches the existing air flow.

5. Anytime the boiler is fired, the furnace must have at least 33% of rated full load flow in the tube circuits.

6. You should make sure that the rate of change in the fluid temperature at the convection pass outlet does not exceed 200 F per hour. Any rate higher than this will lead to thermal stress problems.

7. You can detect a tube failure by monitoring the high makeup flow rate or by a discrepancy between feedwater flow and main steam flow.

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#BoilerManual #ProtectingPressureParts #Section10 #Page10

Questions for protecting pressure parts

1. What are the two ways you can minimize overheating, thermal stress, and corrosion in your boiler?

........ 1. __________________________________

........ 2. __________________________________

2. What are the temperature limitations when filling the boiler with water?

3. What should you do to decrease the chances of an explosion when following a burner trip?

4. How can you reduce the chances of an explosion when you have observed dark and smoking flames in the furnace?

5. What is the minimum amount of feedwater flow needed when firing the boiler?

6. What is the maximum rate of temperature change at the convection pass outlet?

7. Name two ways you can detect a tube failure by monitoring indicators in the control room.

........ 1. __________________________________

........ 2. __________________________________

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#BoilerManual #ProtectingPressureParts #Section10 #Page10

Questions for protecting pressure parts

1. What are the two ways you can minimize overheating, thermal stress, and corrosion in your boiler?

........ 1. __________________________________

........ 2. __________________________________

2. What are the temperature limitations when filling the boiler with water?

3. What should you do to decrease the chances of an explosion when following a burner trip?

4. How can you reduce the chances of an explosion when you have observed dark and smoking flames in the furnace?

5. What is the minimum amount of feedwater flow needed when firing the boiler?

6. What is the maximum rate of temperature change at the convection pass outlet?

7. Name two ways you can detect a tube failure by monitoring indicators in the control room.

........ 1. __________________________________

........ 2. __________________________________

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#BoilerManual #ProtectingPressureParts #Section10 #Page9

Air ejectors and heat exchanging equipment containing copper alloys should not be in direct contact with the treated water for any long periods of time.

During the wet storage period, a positive pressure nitrogen cap should be maintained on the system. When the unit is drained following hydrostatic testing and layup, nitrogen should be used to displace the water.

In the foregoing we have stressed the importance of protection of pressure parts as such protection relates to operating reliability. We discussed ways in which you as an operator can contribute to safe and reliable operation of the unit. We hope that this section of the manual has made you aware of the damaging effects of corrosion, overheating, and thermal stresses, and more specifically, what you as an operator can do to protect the boiler pressure parts.

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#BoilerManual #ProtectingPressureParts #Section10 #Page9

Air ejectors and heat exchanging equipment containing copper alloys should not be in direct contact with the treated water for any long periods of time.

During the wet storage period, a positive pressure nitrogen cap should be maintained on the system. When the unit is drained following hydrostatic testing and layup, nitrogen should be used to displace the water.

In the foregoing we have stressed the importance of protection of pressure parts as such protection relates to operating reliability. We discussed ways in which you as an operator can contribute to safe and reliable operation of the unit. We hope that this section of the manual has made you aware of the damaging effects of corrosion, overheating, and thermal stresses, and more specifically, what you as an operator can do to protect the boiler pressure parts.

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#BoilerManual #ProtectingPressureParts #Section10 #Page8

STORAGE PROCEDURES

In the presence of moisture and oxygen, atmospheric corrosion of ferritic materials (tube metals) proceeds rapidly. This not only makes the unit difficult to clean up during initial startup after a layup, but it also results in rough internal tube surfaces, which in turn serve as sites for future operational corrosion and deposition. Since it is impossible to completely dry all circuits, wet layup with treated water normally offers the best method of protection.

Hydrostatic testing and layup should be accomplished with treated demineralized water. Treated demineralized water is defined as water which has been passed through a mixed bed demineralizer system and has ammonia and hydrazine added to give initial concentrations of 10 ppm and 500 ppm respectively. It is not necessary to maintain concentrations at these levels. Protection is still afforded after pH and hydrazine have dropped to lower levels.

In preparation for the storage period, the ammonia and hydrazine should be added in a manner that results in a uniform concentration throughout the system. The hydrazine and ammonia can be added at the condensate header. It is recommended that if the unit is down five days or longer (long term) the unit should be prepared for storage with treated water during downtime.

For contemplated shutdown periods from 1 to 5 days (short term), when circulating to cool down the steam generator, ammonia and hydrazine concentrations should be built up in the system to 100 ppm and 25 ppm respectively. To prevent unnecessary decomposition of hydrazine, the system should be cooled to less than 400 F before adding the hydrazine. These concentrations of chemicals can generally be reached by use of the cycle chemical feed pumps (during the time of adding the ammonia and hydrazine, the demineralizers should be bypassed).

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#BoilerManual #ProtectingPressureParts #Section10 #Page8

STORAGE PROCEDURES

In the presence of moisture and oxygen, atmospheric corrosion of ferritic materials (tube metals) proceeds rapidly. This not only makes the unit difficult to clean up during initial startup after a layup, but it also results in rough internal tube surfaces, which in turn serve as sites for future operational corrosion and deposition. Since it is impossible to completely dry all circuits, wet layup with treated water normally offers the best method of protection.

Hydrostatic testing and layup should be accomplished with treated demineralized water. Treated demineralized water is defined as water which has been passed through a mixed bed demineralizer system and has ammonia and hydrazine added to give initial concentrations of 10 ppm and 500 ppm respectively. It is not necessary to maintain concentrations at these levels. Protection is still afforded after pH and hydrazine have dropped to lower levels.

In preparation for the storage period, the ammonia and hydrazine should be added in a manner that results in a uniform concentration throughout the system. The hydrazine and ammonia can be added at the condensate header. It is recommended that if the unit is down five days or longer (long term) the unit should be prepared for storage with treated water during downtime.

For contemplated shutdown periods from 1 to 5 days (short term), when circulating to cool down the steam generator, ammonia and hydrazine concentrations should be built up in the system to 100 ppm and 25 ppm respectively. To prevent unnecessary decomposition of hydrazine, the system should be cooled to less than 400 F before adding the hydrazine. These concentrations of chemicals can generally be reached by use of the cycle chemical feed pumps (during the time of adding the ammonia and hydrazine, the demineralizers should be bypassed).

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#BoilerManual #ProtectingPressureParts #Section10 #Page7

boiler purged. If the boiler is to be kept hot, circulation should be stopped, fans turned off, and all dampers closed.

NOTE: the boiler can be force-cooled if desired, but cooling rates should be limited to 200 F/hr temperature differentials to prevent thermal stress problems. Circulation should continue in the cold cleanup mode. Heat should be rejected through the bypass system to the condenser at a rate determined by the flashtank pressure setpoint. A lower setpoint will result in a higher rejection rate. Air flow can also continue, but care should be taken not to overload the gas recirculation fans (hot gas fans), with cold air.

The combination of air flow and heat rejection from the flashtank should be carefully regulated so that fluid temperature at the convection pass outlet does not change by more than 200 F an hour.

After the boiler has been cooled, it must be properly stored. Wet storage, with all circuits flooded is preferable unless ambient temperatures will drop below freezing. If the boiler needs to be drained, it should be drained and stored under a positive pressure nitrogen cap to keep air out of the tubes to prevent oxygen corrosion.

PROTECTION OF THE REHEATER

Due to the various piping and valving arrangements of the reheater, it is normally impossible to pressurize the reheater with nitrogen. Therefore, the following procedure should be observed. Before shutdown is complete and the reheater is hot enough to produce steam, open the vents or drains on the primary inlet of the reheater. The condenser vacuum will facilitate in the removal of the steam/condensate in the reheater.

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#BoilerManual #ProtectingPressureParts #Section10 #Page7

boiler purged. If the boiler is to be kept hot, circulation should be stopped, fans turned off, and all dampers closed.

NOTE: the boiler can be force-cooled if desired, but cooling rates should be limited to 200 F/hr temperature differentials to prevent thermal stress problems. Circulation should continue in the cold cleanup mode. Heat should be rejected through the bypass system to the condenser at a rate determined by the flashtank pressure setpoint. A lower setpoint will result in a higher rejection rate. Air flow can also continue, but care should be taken not to overload the gas recirculation fans (hot gas fans), with cold air.

The combination of air flow and heat rejection from the flashtank should be carefully regulated so that fluid temperature at the convection pass outlet does not change by more than 200 F an hour.

After the boiler has been cooled, it must be properly stored. Wet storage, with all circuits flooded is preferable unless ambient temperatures will drop below freezing. If the boiler needs to be drained, it should be drained and stored under a positive pressure nitrogen cap to keep air out of the tubes to prevent oxygen corrosion.

PROTECTION OF THE REHEATER

Due to the various piping and valving arrangements of the reheater, it is normally impossible to pressurize the reheater with nitrogen. Therefore, the following procedure should be observed. Before shutdown is complete and the reheater is hot enough to produce steam, open the vents or drains on the primary inlet of the reheater. The condenser vacuum will facilitate in the removal of the steam/condensate in the reheater.

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#BoilerManual #ProtectingPressureParts #Section10 #Page6

these circuits will not exceed 1000 F, provided the leakage rate does not exceed 3%. If a tube leak is detected, the boiler should be shutdown as soon as normal operating conditions permit. Operating with a known leak can be dangerous as well as costly. If the leak is in the burner area, it can cause loss of ignition and possibly an explosion on re-ignition. Operating with a leak can also cause extensive damage and failure of other tubes by eroding adjacent tubes and by altering flow distribution enough to result in wide-spread overheat failures.

Tube failures may be detected in several ways. If the leak is large, a loss of water from the system may be detected, either as high makeup or as a discrepancy in feedwater flow to steam flow. If the leak is in the furnace, it will often be seen as an unusual increase in riser temperatures.

SHUTDOWN AND STORAGE

Proper shutdown and storage procedures can also help protect the pressure parts against thermal stress and corrosion. Soot should be blown whenever possible immediately prior to shutting down. This will help remove corrosive deposits from the tube surfaces. The fuel/air ratio and furnace conditions should be closely monitored at low loads for explosion prevention.

The normal shutdown procedure would be to reduce load to minimum feedwater flow with the turbine valves, and then lower turbine loading with the bypass system. Minimum FW flow must be maintained at all times in the furnace and convection pass enclosure circuits. The bypass system should be in the startup mode for maximum heat recovery in the feedwater heaters. The rate of change of fluid temperature at the convection pass outlet should be limited to 200 F/hr and SSH tube leg temperatures closely monitored. Below 10% of rated steam flow, the gas temperature at the thermoprobes should be limited to 1000 F. The turbine and boiler should be tripped at minimum turbine loading and the

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#BoilerManual #ProtectingPressureParts #Section10 #Page6

these circuits will not exceed 1000 F, provided the leakage rate does not exceed 3%. If a tube leak is detected, the boiler should be shutdown as soon as normal operating conditions permit. Operating with a known leak can be dangerous as well as costly. If the leak is in the burner area, it can cause loss of ignition and possibly an explosion on re-ignition. Operating with a leak can also cause extensive damage and failure of other tubes by eroding adjacent tubes and by altering flow distribution enough to result in wide-spread overheat failures.

Tube failures may be detected in several ways. If the leak is large, a loss of water from the system may be detected, either as high makeup or as a discrepancy in feedwater flow to steam flow. If the leak is in the furnace, it will often be seen as an unusual increase in riser temperatures.

SHUTDOWN AND STORAGE

Proper shutdown and storage procedures can also help protect the pressure parts against thermal stress and corrosion. Soot should be blown whenever possible immediately prior to shutting down. This will help remove corrosive deposits from the tube surfaces. The fuel/air ratio and furnace conditions should be closely monitored at low loads for explosion prevention.

The normal shutdown procedure would be to reduce load to minimum feedwater flow with the turbine valves, and then lower turbine loading with the bypass system. Minimum FW flow must be maintained at all times in the furnace and convection pass enclosure circuits. The bypass system should be in the startup mode for maximum heat recovery in the feedwater heaters. The rate of change of fluid temperature at the convection pass outlet should be limited to 200 F/hr and SSH tube leg temperatures closely monitored. Below 10% of rated steam flow, the gas temperature at the thermoprobes should be limited to 1000 F. The turbine and boiler should be tripped at minimum turbine loading and the

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#BoilerManual #ProtectingPressureParts #Section10 #Page5

matched. However, several other factors can effect steam temperature as well as alter the heat distribution pattern within the boiler.

Spray attemperators are used to balance the relationship between main steam and reheat steam temperature. With over-attemperation it is possible to overfire the boiler and still maintain steam temperature. Increased excess air and gas recirculation after the heat distribution within the boiler causing more convection and less radiant heat transfer. Variations in feedwater temperature requires a different firing rate to maintain steam temperature. A 10 F change in FW temperature results in about a 3 F change in main steam temperature.

The ability to alter steam and heat distribution independently of firing rate and steam flow means that fluid temperature throughout the boiler must be closely monitored to prevent overheating tubes in some circuits. While all temperatures are important, furnace tube temperatures are the most critical. The furnace tubes are exposed to the direct radiant heat of the fires, and along with the SSH tubes, are the most affected by errors in the firing rate/steam flow ratio. All tube temperatures must be kept below their alarm limits.

Tube temperatures also provide good indications of firing imbalance. The fluid temperatures in any circuit should be within 80 F of the average temperature of the fluid in the same pass. This is important to prevent both overheat failures and failures due to thermal stress caused by the temperature differentials. Thermal stress failures as well as a failure of attachments to the tubes can be further minimized if the rate of change of the fluid temperature at the convection pass outlet is limited to 100 F/hr. This limit is particularly important during startups and shutdowns.

All cyclone and furnace enclosure circuits are designed to permit a fluid leakage rate of 3% (126,000 lb/hr) of full load flow, over the load range. This built in safety factor insures that the fluid temperature in

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#BoilerManual #ProtectingPressureParts #Section10 #Page5

matched. However, several other factors can effect steam temperature as well as alter the heat distribution pattern within the boiler.

Spray attemperators are used to balance the relationship between main steam and reheat steam temperature. With over-attemperation it is possible to overfire the boiler and still maintain steam temperature. Increased excess air and gas recirculation after the heat distribution within the boiler causing more convection and less radiant heat transfer. Variations in feedwater temperature requires a different firing rate to maintain steam temperature. A 10 F change in FW temperature results in about a 3 F change in main steam temperature.

The ability to alter steam and heat distribution independently of firing rate and steam flow means that fluid temperature throughout the boiler must be closely monitored to prevent overheating tubes in some circuits. While all temperatures are important, furnace tube temperatures are the most critical. The furnace tubes are exposed to the direct radiant heat of the fires, and along with the SSH tubes, are the most affected by errors in the firing rate/steam flow ratio. All tube temperatures must be kept below their alarm limits.

Tube temperatures also provide good indications of firing imbalance. The fluid temperatures in any circuit should be within 80 F of the average temperature of the fluid in the same pass. This is important to prevent both overheat failures and failures due to thermal stress caused by the temperature differentials. Thermal stress failures as well as a failure of attachments to the tubes can be further minimized if the rate of change of the fluid temperature at the convection pass outlet is limited to 100 F/hr. This limit is particularly important during startups and shutdowns.

All cyclone and furnace enclosure circuits are designed to permit a fluid leakage rate of 3% (126,000 lb/hr) of full load flow, over the load range. This built in safety factor insures that the fluid temperature in

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#BoilerManual #ProtectingPressureParts #Section10 #Page5

matched. However, several other factors can effect steam temperature as well as alter the heat distribution pattern within the boiler.

Spray attemperators are used to balance the relationship between main steam and reheat steam temperature. With over-attemperation it is possible to overfire the boiler and still maintain steam temperature. Increased excess air and gas recirculation after the heat distribution within the boiler causing more convection and less radiant heat transfer. Variations in feedwater temperature requires a different firing rate to maintain steam temperature. A 10 F change in FW temperature results in about a 3 F change in main steam temperature.

The ability to alter steam and heat distribution independently of firing rate and steam flow means that fluid temperature throughout the boiler must be closely monitored to prevent overheating tubes in some circuits. While all temperatures are important, furnace tube temperatures are the most critical. The furnace tubes are exposed to the direct radiant heat of the fires, and along with the SSH tubes, are the most affected by errors in the firing rate/steam flow ratio. All tube temperatures must be kept below their alarm limits.

Tube temperatures also provide good indications of firing imbalance. The fluid temperatures in any circuit should be within 80 F of the average temperature of the fluid in the same pass. This is important to prevent both overheat failures and failures due to thermal stress caused by the temperature differentials. Thermal stress failures as well as a failure of attachments to the tubes can be further minimized if the rate of change of the fluid temperature at the convection pass outlet is limited to 100 F/hr. This limit is particularly important during startups and shutdowns.

All cyclone and furnace enclosure circuits are designed to permit a fluid leakage rate of 3% (126,000 lb/hr) of full load flow, over the load range. This built in safety factor insures that the fluid temperature in

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#BoilerManual #ProtectingPressureParts #Section10 #Page5

matched. However, several other factors can effect steam temperature as well as alter the heat distribution pattern within the boiler.

Spray attemperators are used to balance the relationship between main steam and reheat steam temperature. With over-attemperation it is possible to overfire the boiler and still maintain steam temperature. Increased excess air and gas recirculation after the heat distribution within the boiler causing more convection and less radiant heat transfer. Variations in feedwater temperature requires a different firing rate to maintain steam temperature. A 10 F change in FW temperature results in about a 3 F change in main steam temperature.

The ability to alter steam and heat distribution independently of firing rate and steam flow means that fluid temperature throughout the boiler must be closely monitored to prevent overheating tubes in some circuits. While all temperatures are important, furnace tube temperatures are the most critical. The furnace tubes are exposed to the direct radiant heat of the fires, and along with the SSH tubes, are the most affected by errors in the firing rate/steam flow ratio. All tube temperatures must be kept below their alarm limits.

Tube temperatures also provide good indications of firing imbalance. The fluid temperatures in any circuit should be within 80 F of the average temperature of the fluid in the same pass. This is important to prevent both overheat failures and failures due to thermal stress caused by the temperature differentials. Thermal stress failures as well as a failure of attachments to the tubes can be further minimized if the rate of change of the fluid temperature at the convection pass outlet is limited to 100 F/hr. This limit is particularly important during startups and shutdowns.

All cyclone and furnace enclosure circuits are designed to permit a fluid leakage rate of 3% (126,000 lb/hr) of full load flow, over the load range. This built in safety factor insures that the fluid temperature in

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#BoilerManual #ProtectingPressureParts #Section10 #Page5

matched. However, several other factors can effect steam temperature as well as alter the heat distribution pattern within the boiler.

Spray attemperators are used to balance the relationship between main steam and reheat steam temperature. With over-attemperation it is possible to overfire the boiler and still maintain steam temperature. Increased excess air and gas recirculation after the heat distribution within the boiler causing more convection and less radiant heat transfer. Variations in feedwater temperature requires a different firing rate to maintain steam temperature. A 10 F change in FW temperature results in about a 3 F change in main steam temperature.

The ability to alter steam and heat distribution independently of firing rate and steam flow means that fluid temperature throughout the boiler must be closely monitored to prevent overheating tubes in some circuits. While all temperatures are important, furnace tube temperatures are the most critical. The furnace tubes are exposed to the direct radiant heat of the fires, and along with the SSH tubes, are the most affected by errors in the firing rate/steam flow ratio. All tube temperatures must be kept below their alarm limits.

Tube temperatures also provide good indications of firing imbalance. The fluid temperatures in any circuit should be within 80 F of the average temperature of the fluid in the same pass. This is important to prevent both overheat failures and failures due to thermal stress caused by the temperature differentials. Thermal stress failures as well as a failure of attachments to the tubes can be further minimized if the rate of change of the fluid temperature at the convection pass outlet is limited to 100 F/hr. This limit is particularly important during startups and shutdowns.

All cyclone and furnace enclosure circuits are designed to permit a fluid leakage rate of 3% (126,000 lb/hr) of full load flow, over the load range. This built in safety factor insures that the fluid temperature in

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#BoilerManual #ProtectingPressureParts #Section10 #Page4

These same thermocouples are also important for SH protection during normal operation. As mentioned earlier, the primary method of SH protection under normal conditions is to balance steam flow and firing rate. The usual indicator that the two are properly balanced is the main steam temperature. There are, however, other factors such as excess air, gas recirculation, and spray attemperation, which affect main steam temperature. Hence, it is possible to have a proper steam temperature and still overfire the SH. Over attemperation is an excellent example, Main steam temperature would be correct, but SH tube leg temperatures could be dangerously high since firing rate and steam flow would not be properly matched

The outlet leg thermocouples also indicate firing imbalances across the width of the furnace. Tube outlet leg thermocouples can be used to minimize these imbalances and aid in combustion as well as protecting the SH from locally high gas temperature.

The special attention required by the SH's does not lessen the protection required by the rest of the boiler pressure parts and in fact, many of the SH protection measures also protect the furnace enclosure.

BOILER PROTECTION

As with the SH's, the primary method of protecting the boiler pressure parts against overheating is by maintaining the correct firing rate for each flow. This is due to the forced, once-through circulation utilized with the UP boiler. To insure that flow through each tube within each pass is sufficient to protect the tube, minimum flow and pressure requirements must be maintained. MINIMUM FLOW IS 33% OF FULL LOAD FLOW AND MUST BE MAINTAINED AT ANY TIME THE UNIT IS FIRED.

With the proper operating pressure, main steam temperature is usually the primary indication that firing rate and steam flow are

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#BoilerManual #ProtectingPressureParts #Section10 #Page4

These same thermocouples are also important for SH protection during normal operation. As mentioned earlier, the primary method of SH protection under normal conditions is to balance steam flow and firing rate. The usual indicator that the two are properly balanced is the main steam temperature. There are, however, other factors such as excess air, gas recirculation, and spray attemperation, which affect main steam temperature. Hence, it is possible to have a proper steam temperature and still overfire the SH. Over attemperation is an excellent example, Main steam temperature would be correct, but SH tube leg temperatures could be dangerously high since firing rate and steam flow would not be properly matched

The outlet leg thermocouples also indicate firing imbalances across the width of the furnace. Tube outlet leg thermocouples can be used to minimize these imbalances and aid in combustion as well as protecting the SH from locally high gas temperature.

The special attention required by the SH's does not lessen the protection required by the rest of the boiler pressure parts and in fact, many of the SH protection measures also protect the furnace enclosure.

BOILER PROTECTION

As with the SH's, the primary method of protecting the boiler pressure parts against overheating is by maintaining the correct firing rate for each flow. This is due to the forced, once-through circulation utilized with the UP boiler. To insure that flow through each tube within each pass is sufficient to protect the tube, minimum flow and pressure requirements must be maintained. MINIMUM FLOW IS 33% OF FULL LOAD FLOW AND MUST BE MAINTAINED AT ANY TIME THE UNIT IS FIRED.

With the proper operating pressure, main steam temperature is usually the primary indication that firing rate and steam flow are

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#BoilerManual #ProtectingPressureParts #Section10 #Page4

These same thermocouples are also important for SH protection during normal operation. As mentioned earlier, the primary method of SH protection under normal conditions is to balance steam flow and firing rate. The usual indicator that the two are properly balanced is the main steam temperature. There are, however, other factors such as excess air, gas recirculation, and spray attemperation, which affect main steam temperature. Hence, it is possible to have a proper steam temperature and still overfire the SH. Over attemperation is an excellent example, Main steam temperature would be correct, but SH tube leg temperatures could be dangerously high since firing rate and steam flow would not be properly matched

The outlet leg thermocouples also indicate firing imbalances across the width of the furnace. Tube outlet leg thermocouples can be used to minimize these imbalances and aid in combustion as well as protecting the SH from locally high gas temperature.

The special attention required by the SH's does not lessen the protection required by the rest of the boiler pressure parts and in fact, many of the SH protection measures also protect the furnace enclosure.

BOILER PROTECTION

As with the SH's, the primary method of protecting the boiler pressure parts against overheating is by maintaining the correct firing rate for each flow. This is due to the forced, once-through circulation utilized with the UP boiler. To insure that flow through each tube within each pass is sufficient to protect the tube, minimum flow and pressure requirements must be maintained. MINIMUM FLOW IS 33% OF FULL LOAD FLOW AND MUST BE MAINTAINED AT ANY TIME THE UNIT IS FIRED.

With the proper operating pressure, main steam temperature is usually the primary indication that firing rate and steam flow are

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#BoilerManual #ProtectingPressureParts #Section10 #Page4

These same thermocouples are also important for SH protection during normal operation. As mentioned earlier, the primary method of SH protection under normal conditions is to balance steam flow and firing rate. The usual indicator that the two are properly balanced is the main steam temperature. There are, however, other factors such as excess air, gas recirculation, and spray attemperation, which affect main steam temperature. Hence, it is possible to have a proper steam temperature and still overfire the SH. Over attemperation is an excellent example, Main steam temperature would be correct, but SH tube leg temperatures could be dangerously high since firing rate and steam flow would not be properly matched

The outlet leg thermocouples also indicate firing imbalances across the width of the furnace. Tube outlet leg thermocouples can be used to minimize these imbalances and aid in combustion as well as protecting the SH from locally high gas temperature.

The special attention required by the SH's does not lessen the protection required by the rest of the boiler pressure parts and in fact, many of the SH protection measures also protect the furnace enclosure.

BOILER PROTECTION

As with the SH's, the primary method of protecting the boiler pressure parts against overheating is by maintaining the correct firing rate for each flow. This is due to the forced, once-through circulation utilized with the UP boiler. To insure that flow through each tube within each pass is sufficient to protect the tube, minimum flow and pressure requirements must be maintained. MINIMUM FLOW IS 33% OF FULL LOAD FLOW AND MUST BE MAINTAINED AT ANY TIME THE UNIT IS FIRED.

With the proper operating pressure, main steam temperature is usually the primary indication that firing rate and steam flow are

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#BoilerManual #ProtectingPressureParts #Section10 #Page4

These same thermocouples are also important for SH protection during normal operation. As mentioned earlier, the primary method of SH protection under normal conditions is to balance steam flow and firing rate. The usual indicator that the two are properly balanced is the main steam temperature. There are, however, other factors such as excess air, gas recirculation, and spray attemperation, which affect main steam temperature. Hence, it is possible to have a proper steam temperature and still overfire the SH. Over attemperation is an excellent example, Main steam temperature would be correct, but SH tube leg temperatures could be dangerously high since firing rate and steam flow would not be properly matched

The outlet leg thermocouples also indicate firing imbalances across the width of the furnace. Tube outlet leg thermocouples can be used to minimize these imbalances and aid in combustion as well as protecting the SH from locally high gas temperature.

The special attention required by the SH's does not lessen the protection required by the rest of the boiler pressure parts and in fact, many of the SH protection measures also protect the furnace enclosure.

BOILER PROTECTION

As with the SH's, the primary method of protecting the boiler pressure parts against overheating is by maintaining the correct firing rate for each flow. This is due to the forced, once-through circulation utilized with the UP boiler. To insure that flow through each tube within each pass is sufficient to protect the tube, minimum flow and pressure requirements must be maintained. MINIMUM FLOW IS 33% OF FULL LOAD FLOW AND MUST BE MAINTAINED AT ANY TIME THE UNIT IS FIRED.

With the proper operating pressure, main steam temperature is usually the primary indication that firing rate and steam flow are

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#BoilerManual #ProtectingPressureParts #Section10 #Page3

SUPERHEATER PROTECTION

Special attention must be given to protecting the superheating surfaces, particularly during startup as they are located in the hottest areas of the convection pass. During operation of the bypass system, fluid flow through the SH's is less than flow through the furnace circuits. The reheater is in effect an additional superheater inserted ahead of the intermediate pressure turbine and is placed in service in tandem with the SH, so it requires the same protection.

The two primary methods of protecting the SH's are to match fluid flow to firing rate during ramping and normal operation, and to limit gas temperature entering the SSH during startup until steam flow through each tube is sufficient for protection.

Gas temperature is limited to 1000 F entering the SSH until all water is removed from each tube and total steam flow is greater than 10% of rated flow. Ten percent flow is required to insure an even distribution of flow to each tube. The 1000 F limit is measured by the thermoprobes.

As previously stated, the superheater loops must be cleared of all condensate. The reason for the water removal requirements is that there can be no steam flow through a partially filled tube. Those portions of the tube not in contact with the water leg will be subject to high temperature and can overheat and fail. Water is removed from drainable SH's and RH's simply by opening all drains and vents. Removal is not as simple with the non-drainable pendant SH's and RH's since the water must be boiled away.

Thermocouples attached to the outlet legs of the SSH tubes will indicate when they have boiled out. The thermocouples will read saturation temperature while water remains in the tube. The reading will rise sharply as the tube is boiled clear and flow is established. SH tubes adjacent to the sidewalls are normally the last to boil out.

-------------------------------------------------- 3 ------------------------------------------------------

#BoilerManual #ProtectingPressureParts #Section10 #Page3

SUPERHEATER PROTECTION

Special attention must be given to protecting the superheating surfaces, particularly during startup as they are located in the hottest areas of the convection pass. During operation of the bypass system, fluid flow through the SH's is less than flow through the furnace circuits. The reheater is in effect an additional superheater inserted ahead of the intermediate pressure turbine and is placed in service in tandem with the SH, so it requires the same protection.

The two primary methods of protecting the SH's are to match fluid flow to firing rate during ramping and normal operation, and to limit gas temperature entering the SSH during startup until steam flow through each tube is sufficient for protection.

Gas temperature is limited to 1000 F entering the SSH until all water is removed from each tube and total steam flow is greater than 10% of rated flow. Ten percent flow is required to insure an even distribution of flow to each tube. The 1000 F limit is measured by the thermoprobes.

As previously stated, the superheater loops must be cleared of all condensate. The reason for the water removal requirements is that there can be no steam flow through a partially filled tube. Those portions of the tube not in contact with the water leg will be subject to high temperature and can overheat and fail. Water is removed from drainable SH's and RH's simply by opening all drains and vents. Removal is not as simple with the non-drainable pendant SH's and RH's since the water must be boiled away.

Thermocouples attached to the outlet legs of the SSH tubes will indicate when they have boiled out. The thermocouples will read saturation temperature while water remains in the tube. The reading will rise sharply as the tube is boiled clear and flow is established. SH tubes adjacent to the sidewalls are normally the last to boil out.

-------------------------------------------------- 3 ------------------------------------------------------

#BoilerManual #ProtectingPressureParts #Section10 #Page3

SUPERHEATER PROTECTION

Special attention must be given to protecting the superheating surfaces, particularly during startup as they are located in the hottest areas of the convection pass. During operation of the bypass system, fluid flow through the SH's is less than flow through the furnace circuits. The reheater is in effect an additional superheater inserted ahead of the intermediate pressure turbine and is placed in service in tandem with the SH, so it requires the same protection.

The two primary methods of protecting the SH's are to match fluid flow to firing rate during ramping and normal operation, and to limit gas temperature entering the SSH during startup until steam flow through each tube is sufficient for protection.

Gas temperature is limited to 1000 F entering the SSH until all water is removed from each tube and total steam flow is greater than 10% of rated flow. Ten percent flow is required to insure an even distribution of flow to each tube. The 1000 F limit is measured by the thermoprobes.

As previously stated, the superheater loops must be cleared of all condensate. The reason for the water removal requirements is that there can be no steam flow through a partially filled tube. Those portions of the tube not in contact with the water leg will be subject to high temperature and can overheat and fail. Water is removed from drainable SH's and RH's simply by opening all drains and vents. Removal is not as simple with the non-drainable pendant SH's and RH's since the water must be boiled away.

Thermocouples attached to the outlet legs of the SSH tubes will indicate when they have boiled out. The thermocouples will read saturation temperature while water remains in the tube. The reading will rise sharply as the tube is boiled clear and flow is established. SH tubes adjacent to the sidewalls are normally the last to boil out.

-------------------------------------------------- 3 ------------------------------------------------------

#BoilerManual #ProtectingPressureParts #Section10 #Page3

SUPERHEATER PROTECTION

Special attention must be given to protecting the superheating surfaces, particularly during startup as they are located in the hottest areas of the convection pass. During operation of the bypass system, fluid flow through the SH's is less than flow through the furnace circuits. The reheater is in effect an additional superheater inserted ahead of the intermediate pressure turbine and is placed in service in tandem with the SH, so it requires the same protection.

The two primary methods of protecting the SH's are to match fluid flow to firing rate during ramping and normal operation, and to limit gas temperature entering the SSH during startup until steam flow through each tube is sufficient for protection.

Gas temperature is limited to 1000 F entering the SSH until all water is removed from each tube and total steam flow is greater than 10% of rated flow. Ten percent flow is required to insure an even distribution of flow to each tube. The 1000 F limit is measured by the thermoprobes.

As previously stated, the superheater loops must be cleared of all condensate. The reason for the water removal requirements is that there can be no steam flow through a partially filled tube. Those portions of the tube not in contact with the water leg will be subject to high temperature and can overheat and fail. Water is removed from drainable SH's and RH's simply by opening all drains and vents. Removal is not as simple with the non-drainable pendant SH's and RH's since the water must be boiled away.

Thermocouples attached to the outlet legs of the SSH tubes will indicate when they have boiled out. The thermocouples will read saturation temperature while water remains in the tube. The reading will rise sharply as the tube is boiled clear and flow is established. SH tubes adjacent to the sidewalls are normally the last to boil out.

-------------------------------------------------- 3 ------------------------------------------------------

#BoilerManual #ProtectingPressureParts #Section10 #Page3

SUPERHEATER PROTECTION

Special attention must be given to protecting the superheating surfaces, particularly during startup as they are located in the hottest areas of the convection pass. During operation of the bypass system, fluid flow through the SH's is less than flow through the furnace circuits. The reheater is in effect an additional superheater inserted ahead of the intermediate pressure turbine and is placed in service in tandem with the SH, so it requires the same protection.

The two primary methods of protecting the SH's are to match fluid flow to firing rate during ramping and normal operation, and to limit gas temperature entering the SSH during startup until steam flow through each tube is sufficient for protection.

Gas temperature is limited to 1000 F entering the SSH until all water is removed from each tube and total steam flow is greater than 10% of rated flow. Ten percent flow is required to insure an even distribution of flow to each tube. The 1000 F limit is measured by the thermoprobes.

As previously stated, the superheater loops must be cleared of all condensate. The reason for the water removal requirements is that there can be no steam flow through a partially filled tube. Those portions of the tube not in contact with the water leg will be subject to high temperature and can overheat and fail. Water is removed from drainable SH's and RH's simply by opening all drains and vents. Removal is not as simple with the non-drainable pendant SH's and RH's since the water must be boiled away.

Thermocouples attached to the outlet legs of the SSH tubes will indicate when they have boiled out. The thermocouples will read saturation temperature while water remains in the tube. The reading will rise sharply as the tube is boiled clear and flow is established. SH tubes adjacent to the sidewalls are normally the last to boil out.

-------------------------------------------------- 3 ------------------------------------------------------

#BoilerManual #ProtectingPressureParts #Section10 #Page2

than 100 ppb. It is also extremely important to keep oxygen out of the system for corrosion prevention, even during the cleanup period. The turbine should be sealed, the condenser under vacuum, and the deaerator pressurized.

The unit must be purged of combustibles before firing is initiated. The purge cycle is extremely important in the prevention of furnace explosions. Most furnace explosions occur during these periods. Large amounts of combustibles may accumulate or pockets of combustible gas may form in almost any part of the boiler. When an ignition source is provided, their rapid ignition can cause an explosion. Purging the unit at a minimum of 25% rated air flow prior to lightoff removes the unburned combustibles and minimizes the possibility of explosions. The purge cycle should extend for at least five minutes with 25-30% of rated air flow.

As an additional precaution, the furnace should be post-purged with 25-30% air flow immediately following the removal of all fires. There is one important exception to this rule. IF ALL FUEL TO THE BURNERS HAS BEEN TRIPPED DUE TO FLAME FAILURE, INCREASING AIR FLOW TO MEET PURGE REQUIREMENTS COULD RESULT IN AN EXPLOSION. IN THIS CASE, THE PURGE PERIOD SHOULD BE EXTENDED BEYOND ITS NORMAL TIME LIMIT WITH EXISTING AIR FLOW. THIS WILL REMOVE THE COMBUSTIBLES WHILE AVOIDING THE DANGEROUS SUDDEN INCREASE IN AIR FLOW.

The frequency of furnace observation should be increased significantly during extended periods of low load operation. Dark and smoky fires indicate that the fuel is not being completely burned and the possibility of an explosion is increased. Burner adjustments may be necessary and excess air levels may have to be increased above normal; CAUTION: sudden changes in air flow should be avoided.

-------------------------------------------------- 2 ------------------------------------------------------

#BoilerManual #ProtectingPressureParts #Section10 #Page2

than 100 ppb. It is also extremely important to keep oxygen out of the system for corrosion prevention, even during the cleanup period. The turbine should be sealed, the condenser under vacuum, and the deaerator pressurized.

The unit must be purged of combustibles before firing is initiated. The purge cycle is extremely important in the prevention of furnace explosions. Most furnace explosions occur during these periods. Large amounts of combustibles may accumulate or pockets of combustible gas may form in almost any part of the boiler. When an ignition source is provided, their rapid ignition can cause an explosion. Purging the unit at a minimum of 25% rated air flow prior to lightoff removes the unburned combustibles and minimizes the possibility of explosions. The purge cycle should extend for at least five minutes with 25-30% of rated air flow.

As an additional precaution, the furnace should be post-purged with 25-30% air flow immediately following the removal of all fires. There is one important exception to this rule. IF ALL FUEL TO THE BURNERS HAS BEEN TRIPPED DUE TO FLAME FAILURE, INCREASING AIR FLOW TO MEET PURGE REQUIREMENTS COULD RESULT IN AN EXPLOSION. IN THIS CASE, THE PURGE PERIOD SHOULD BE EXTENDED BEYOND ITS NORMAL TIME LIMIT WITH EXISTING AIR FLOW. THIS WILL REMOVE THE COMBUSTIBLES WHILE AVOIDING THE DANGEROUS SUDDEN INCREASE IN AIR FLOW.

The frequency of furnace observation should be increased significantly during extended periods of low load operation. Dark and smoky fires indicate that the fuel is not being completely burned and the possibility of an explosion is increased. Burner adjustments may be necessary and excess air levels may have to be increased above normal; CAUTION: sudden changes in air flow should be avoided.

-------------------------------------------------- 2 ------------------------------------------------------

#BoilerManual #ProtectingPressureParts #Section10 #Page2

than 100 ppb. It is also extremely important to keep oxygen out of the system for corrosion prevention, even during the cleanup period. The turbine should be sealed, the condenser under vacuum, and the deaerator pressurized.

The unit must be purged of combustibles before firing is initiated. The purge cycle is extremely important in the prevention of furnace explosions. Most furnace explosions occur during these periods. Large amounts of combustibles may accumulate or pockets of combustible gas may form in almost any part of the boiler. When an ignition source is provided, their rapid ignition can cause an explosion. Purging the unit at a minimum of 25% rated air flow prior to lightoff removes the unburned combustibles and minimizes the possibility of explosions. The purge cycle should extend for at least five minutes with 25-30% of rated air flow.

As an additional precaution, the furnace should be post-purged with 25-30% air flow immediately following the removal of all fires. There is one important exception to this rule. IF ALL FUEL TO THE BURNERS HAS BEEN TRIPPED DUE TO FLAME FAILURE, INCREASING AIR FLOW TO MEET PURGE REQUIREMENTS COULD RESULT IN AN EXPLOSION. IN THIS CASE, THE PURGE PERIOD SHOULD BE EXTENDED BEYOND ITS NORMAL TIME LIMIT WITH EXISTING AIR FLOW. THIS WILL REMOVE THE COMBUSTIBLES WHILE AVOIDING THE DANGEROUS SUDDEN INCREASE IN AIR FLOW.

The frequency of furnace observation should be increased significantly during extended periods of low load operation. Dark and smoky fires indicate that the fuel is not being completely burned and the possibility of an explosion is increased. Burner adjustments may be necessary and excess air levels may have to be increased above normal; CAUTION: sudden changes in air flow should be avoided.

-------------------------------------------------- 2 ------------------------------------------------------

#BoilerManual #ProtectingPressureParts #Section10 #Page2

than 100 ppb. It is also extremely important to keep oxygen out of the system for corrosion prevention, even during the cleanup period. The turbine should be sealed, the condenser under vacuum, and the deaerator pressurized.

The unit must be purged of combustibles before firing is initiated. The purge cycle is extremely important in the prevention of furnace explosions. Most furnace explosions occur during these periods. Large amounts of combustibles may accumulate or pockets of combustible gas may form in almost any part of the boiler. When an ignition source is provided, their rapid ignition can cause an explosion. Purging the unit at a minimum of 25% rated air flow prior to lightoff removes the unburned combustibles and minimizes the possibility of explosions. The purge cycle should extend for at least five minutes with 25-30% of rated air flow.

As an additional precaution, the furnace should be post-purged with 25-30% air flow immediately following the removal of all fires. There is one important exception to this rule. IF ALL FUEL TO THE BURNERS HAS BEEN TRIPPED DUE TO FLAME FAILURE, INCREASING AIR FLOW TO MEET PURGE REQUIREMENTS COULD RESULT IN AN EXPLOSION. IN THIS CASE, THE PURGE PERIOD SHOULD BE EXTENDED BEYOND ITS NORMAL TIME LIMIT WITH EXISTING AIR FLOW. THIS WILL REMOVE THE COMBUSTIBLES WHILE AVOIDING THE DANGEROUS SUDDEN INCREASE IN AIR FLOW.

The frequency of furnace observation should be increased significantly during extended periods of low load operation. Dark and smoky fires indicate that the fuel is not being completely burned and the possibility of an explosion is increased. Burner adjustments may be necessary and excess air levels may have to be increased above normal; CAUTION: sudden changes in air flow should be avoided.

-------------------------------------------------- 2 ------------------------------------------------------

#BoilerManual #ProtectingPressureParts #Section10 #Page2

than 100 ppb. It is also extremely important to keep oxygen out of the system for corrosion prevention, even during the cleanup period. The turbine should be sealed, the condenser under vacuum, and the deaerator pressurized.

The unit must be purged of combustibles before firing is initiated. The purge cycle is extremely important in the prevention of furnace explosions. Most furnace explosions occur during these periods. Large amounts of combustibles may accumulate or pockets of combustible gas may form in almost any part of the boiler. When an ignition source is provided, their rapid ignition can cause an explosion. Purging the unit at a minimum of 25% rated air flow prior to lightoff removes the unburned combustibles and minimizes the possibility of explosions. The purge cycle should extend for at least five minutes with 25-30% of rated air flow.

As an additional precaution, the furnace should be post-purged with 25-30% air flow immediately following the removal of all fires. There is one important exception to this rule. IF ALL FUEL TO THE BURNERS HAS BEEN TRIPPED DUE TO FLAME FAILURE, INCREASING AIR FLOW TO MEET PURGE REQUIREMENTS COULD RESULT IN AN EXPLOSION. IN THIS CASE, THE PURGE PERIOD SHOULD BE EXTENDED BEYOND ITS NORMAL TIME LIMIT WITH EXISTING AIR FLOW. THIS WILL REMOVE THE COMBUSTIBLES WHILE AVOIDING THE DANGEROUS SUDDEN INCREASE IN AIR FLOW.

The frequency of furnace observation should be increased significantly during extended periods of low load operation. Dark and smoky fires indicate that the fuel is not being completely burned and the possibility of an explosion is increased. Burner adjustments may be necessary and excess air levels may have to be increased above normal; CAUTION: sudden changes in air flow should be avoided.

-------------------------------------------------- 2 ------------------------------------------------------

This is the very last section of the boiler training manual, folks. None of this is light reading, but submitted to the public for mulling over just how intensely complicated these behemoths are, and to recognize the importance of making these things museum pieces so that others may learn from them--rather than demolishing them, for no two boilers are alike, not even the Baldwin Twins Units 1 and 2. Unit 3 was an antique GE drum boiler, which should also be deemed to be a museum piece, as well as its own history of operation.

#BoilerManual #ProtectingPressureParts #Section10 #Page1

Protecting pressure parts

Proper protective care of the boiler is essential to unit reliability. We often think of care of the boiler only in connection with maintenance. However, as an operator there is a great deal that you can do to protect boiler pressure parts and help ensure reliable operation and high availability. The need for these protective procedures is present from the initial filling through startup, during normal operating periods, shutdown and storage. The major concerns which we'll be detailing in this section are those which will protect the boiler against corrosion, overheating and thermal stresses.

GENERAL

High temperature differentials cause thermal stresses which can break studs, lugs and other attachments. Severe stresses limit the life of pressure parts. Therefore, the temperature of the water used to fill the boiler should be regulated to match the temperature of the boiler metals so that these stresses are minimized. Normally, water temperature should be within 100 F of metal temperature, and it should be at least 70 F.

All boiler vents should be open during the filling process so that any air in the boiler tubes is replaced with water. This reduces the possibility of oxygen corrosion while at the same time insuring that all boiler tubes are filled.

High quality water should be used for filling in order to minimize cleanup time and protect the boiler against waterside corrosion and deposition {which is why the facility also had its own complete water treatment plant for processing the lake water, and that even includes chlorination--and they used straight-up chlorine gas for that}. Water quality is no less important during startup than during normal operation, and firing is not permitted until cation conductivity is below one micromho at the economizer inlet. Fluid temperature is limited

to 550 F at the convection pass outlet until iron content is less

-------------------------------------------------- 1 ------------------------------------------------------

This is the very last section of the boiler training manual, folks. None of this is light reading, but submitted to the public for mulling over just how intensely complicated these behemoths are, and to recognize the importance of making these things museum pieces so that others may learn from them--rather than demolishing them, for no two boilers are alike, not even the Baldwin Twins Units 1 and 2. Unit 3 was an antique GE drum boiler, which should also be deemed to be a museum piece, as well as its own history of operation.

#BoilerManual #ProtectingPressureParts #Section10 #Page1

Protecting pressure parts

Proper protective care of the boiler is essential to unit reliability. We often think of care of the boiler only in connection with maintenance. However, as an operator there is a great deal that you can do to protect boiler pressure parts and help ensure reliable operation and high availability. The need for these protective procedures is present from the initial filling through startup, during normal operating periods, shutdown and storage. The major concerns which we'll be detailing in this section are those which will protect the boiler against corrosion, overheating and thermal stresses.

GENERAL

High temperature differentials cause thermal stresses which can break studs, lugs and other attachments. Severe stresses limit the life of pressure parts. Therefore, the temperature of the water used to fill the boiler should be regulated to match the temperature of the boiler metals so that these stresses are minimized. Normally, water temperature should be within 100 F of metal temperature, and it should be at least 70 F.

All boiler vents should be open during the filling process so that any air in the boiler tubes is replaced with water. This reduces the possibility of oxygen corrosion while at the same time insuring that all boiler tubes are filled.

High quality water should be used for filling in order to minimize cleanup time and protect the boiler against waterside corrosion and deposition {which is why the facility also had its own complete water treatment plant for processing the lake water, and that even includes chlorination--and they used straight-up chlorine gas for that}. Water quality is no less important during startup than during normal operation, and firing is not permitted until cation conductivity is below one micromho at the economizer inlet. Fluid temperature is limited

to 550 F at the convection pass outlet until iron content is less

-------------------------------------------------- 1 ------------------------------------------------------

This is the very last section of the boiler training manual, folks. None of this is light reading, but submitted to the public for mulling over just how intensely complicated these behemoths are, and to recognize the importance of making these things museum pieces so that others may learn from them--rather than demolishing them, for no two boilers are alike, not even the Baldwin Twins Units 1 and 2. Unit 3 was an antique GE drum boiler, which should also be deemed to be a museum piece, as well as its own history of operation.

#BoilerManual #ProtectingPressureParts #Section10 #Page1

Protecting pressure parts

Proper protective care of the boiler is essential to unit reliability. We often think of care of the boiler only in connection with maintenance. However, as an operator there is a great deal that you can do to protect boiler pressure parts and help ensure reliable operation and high availability. The need for these protective procedures is present from the initial filling through startup, during normal operating periods, shutdown and storage. The major concerns which we'll be detailing in this section are those which will protect the boiler against corrosion, overheating and thermal stresses.

GENERAL

High temperature differentials cause thermal stresses which can break studs, lugs and other attachments. Severe stresses limit the life of pressure parts. Therefore, the temperature of the water used to fill the boiler should be regulated to match the temperature of the boiler metals so that these stresses are minimized. Normally, water temperature should be within 100 F of metal temperature, and it should be at least 70 F.

All boiler vents should be open during the filling process so that any air in the boiler tubes is replaced with water. This reduces the possibility of oxygen corrosion while at the same time insuring that all boiler tubes are filled.

High quality water should be used for filling in order to minimize cleanup time and protect the boiler against waterside corrosion and deposition {which is why the facility also had its own complete water treatment plant for processing the lake water, and that even includes chlorination--and they used straight-up chlorine gas for that}. Water quality is no less important during startup than during normal operation, and firing is not permitted until cation conductivity is below one micromho at the economizer inlet. Fluid temperature is limited

to 550 F at the convection pass outlet until iron content is less

-------------------------------------------------- 1 ------------------------------------------------------

This is the very last section of the boiler training manual, folks. None of this is light reading, but submitted to the public for mulling over just how intensely complicated these behemoths are, and to recognize the importance of making these things museum pieces so that others may learn from them--rather than demolishing them, for no two boilers are alike, not even the Baldwin Twins Units 1 and 2. Unit 3 was an antique GE drum boiler, which should also be deemed to be a museum piece, as well as its own history of operation.

#BoilerManual #ProtectingPressureParts #Section10 #Page1

Protecting pressure parts

Proper protective care of the boiler is essential to unit reliability. We often think of care of the boiler only in connection with maintenance. However, as an operator there is a great deal that you can do to protect boiler pressure parts and help ensure reliable operation and high availability. The need for these protective procedures is present from the initial filling through startup, during normal operating periods, shutdown and storage. The major concerns which we'll be detailing in this section are those which will protect the boiler against corrosion, overheating and thermal stresses.

GENERAL

High temperature differentials cause thermal stresses which can break studs, lugs and other attachments. Severe stresses limit the life of pressure parts. Therefore, the temperature of the water used to fill the boiler should be regulated to match the temperature of the boiler metals so that these stresses are minimized. Normally, water temperature should be within 100 F of metal temperature, and it should be at least 70 F.

All boiler vents should be open during the filling process so that any air in the boiler tubes is replaced with water. This reduces the possibility of oxygen corrosion while at the same time insuring that all boiler tubes are filled.

High quality water should be used for filling in order to minimize cleanup time and protect the boiler against waterside corrosion and deposition {which is why the facility also had its own complete water treatment plant for processing the lake water, and that even includes chlorination--and they used straight-up chlorine gas for that}. Water quality is no less important during startup than during normal operation, and firing is not permitted until cation conductivity is below one micromho at the economizer inlet. Fluid temperature is limited

to 550 F at the convection pass outlet until iron content is less

-------------------------------------------------- 1 ------------------------------------------------------

This is the very last section of the boiler training manual, folks. None of this is light reading, but submitted to the public for mulling over just how intensely complicated these behemoths are, and to recognize the importance of making these things museum pieces so that others may learn from them--rather than demolishing them, for no two boilers are alike, not even the Baldwin Twins Units 1 and 2. Unit 3 was an antique GE drum boiler, which should also be deemed to be a museum piece, as well as its own history of operation.

#BoilerManual #ProtectingPressureParts #Section10 #Page1

Protecting pressure parts

Proper protective care of the boiler is essential to unit reliability. We often think of care of the boiler only in connection with maintenance. However, as an operator there is a great deal that you can do to protect boiler pressure parts and help ensure reliable operation and high availability. The need for these protective procedures is present from the initial filling through startup, during normal operating periods, shutdown and storage. The major concerns which we'll be detailing in this section are those which will protect the boiler against corrosion, overheating and thermal stresses.

GENERAL

High temperature differentials cause thermal stresses which can break studs, lugs and other attachments. Severe stresses limit the life of pressure parts. Therefore, the temperature of the water used to fill the boiler should be regulated to match the temperature of the boiler metals so that these stresses are minimized. Normally, water temperature should be within 100 F of metal temperature, and it should be at least 70 F.

All boiler vents should be open during the filling process so that any air in the boiler tubes is replaced with water. This reduces the possibility of oxygen corrosion while at the same time insuring that all boiler tubes are filled.

High quality water should be used for filling in order to minimize cleanup time and protect the boiler against waterside corrosion and deposition {which is why the facility also had its own complete water treatment plant for processing the lake water, and that even includes chlorination--and they used straight-up chlorine gas for that}. Water quality is no less important during startup than during normal operation, and firing is not permitted until cation conductivity is below one micromho at the economizer inlet. Fluid temperature is limited

to 550 F at the convection pass outlet until iron content is less

-------------------------------------------------- 1 ------------------------------------------------------

#BoilerManual #OptimizingCombustion #Section9 #Page22

9. Slag viscosity is a term describing how easily slag will flow at a specific temperature. It is important to cyclone furnaces because the slag must be thick enough to hold coal particles, but it must be fluid enough to run out the furnace when an excess builds up. For the cyclone furnace, we need a coal that has ash which melts and flows at 2600 F maximum.

10. The five conditions which affect coal-ash deposits in your furnace are:

........ 1. ___How much ash is in the coal.

........ 2. ___The make-up of the ash itself.

........ 3. ___Firing method.

........ 4. ___Equipment design.

........ 5. ___Operating conditions of the boiler.

------------------------------------------------- 22 ------------------------------------------------------

#BoilerManual #OptimizingCombustion #Section9 #Page22

9. Slag viscosity is a term describing how easily slag will flow at a specific temperature. It is important to cyclone furnaces because the slag must be thick enough to hold coal particles, but it must be fluid enough to run out the furnace when an excess builds up. For the cyclone furnace, we need a coal that has ash which melts and flows at 2600 F maximum.

10. The five conditions which affect coal-ash deposits in your furnace are:

........ 1. ___How much ash is in the coal.

........ 2. ___The make-up of the ash itself.

........ 3. ___Firing method.

........ 4. ___Equipment design.

........ 5. ___Operating conditions of the boiler.

------------------------------------------------- 22 ------------------------------------------------------

#BoilerManual #OptimizingCombustion #Section9 #Page21

produced runs out the cyclone, down the furnace, and into the lag tank, for final disposal.

6. The five requirements necessary for slag tap furnaces are:

........ 1. The furnace must be able to maintain temperatures above 3000 F and also be able to tolerate these temperatures.

........ 2. The slag tap furnace must be strong enough to support the extremely heavy molten slag, wherever it tends to accumulate.

........ 3. ___The wall of the furnace should be chemically inactive to the hot slag.

........ 4. ___There must be adequate drainage for the slag.

........ 5. ___The slag needs to be cooled for disposal.

7. The three materials in coal are:

........ 1. ___Combustible material, which should be 15% for cyclone furnaces.

........ 2. ___Ash, which should be a minimum

........ 3. ___Moisture.

8. The four steps that can help prevent iron sulfide formation are:

........ 1. ___Make sure the cyclones are getting enough excess air.

........ 2. ___Keep coal sizing as fine as possible.

........ 3. ___Keep iron oxides to a minimum by making sure cyclone firing is balanced at all times.

........ 4. ___Protect tube surfaces from iron sulfides by keeping stud length at least 1/4" or longer, and by using a good refractory coating that will last.

------------------------------------------------- 21 ------------------------------------------------------

#BoilerManual #OptimizingCombustion #Section9 #Page21

produced runs out the cyclone, down the furnace, and into the lag tank, for final disposal.

6. The five requirements necessary for slag tap furnaces are:

........ 1. The furnace must be able to maintain temperatures above 3000 F and also be able to tolerate these temperatures.

........ 2. The slag tap furnace must be strong enough to support the extremely heavy molten slag, wherever it tends to accumulate.

........ 3. ___The wall of the furnace should be chemically inactive to the hot slag.

........ 4. ___There must be adequate drainage for the slag.

........ 5. ___The slag needs to be cooled for disposal.

7. The three materials in coal are:

........ 1. ___Combustible material, which should be 15% for cyclone furnaces.

........ 2. ___Ash, which should be a minimum

........ 3. ___Moisture.

8. The four steps that can help prevent iron sulfide formation are:

........ 1. ___Make sure the cyclones are getting enough excess air.

........ 2. ___Keep coal sizing as fine as possible.

........ 3. ___Keep iron oxides to a minimum by making sure cyclone firing is balanced at all times.

........ 4. ___Protect tube surfaces from iron sulfides by keeping stud length at least 1/4" or longer, and by using a good refractory coating that will last.

------------------------------------------------- 21 ------------------------------------------------------

#BoilerManual #OptimizingCombustion #Section9 #Page20

Answers for optimizing combustion

1. Combustion is the rapid chemical combination of oxygen with the combustible elements in fuel, that produces heat.

2. The Three T's of Combustion are:

........ 1. ____Time__________________________

........ 2. ____Temperature____________________

........ 3. ____Turbulence_____________________

3. Complete combustion occurs when fuel and oxygen are combined and all the fuel is completely burned. However, not all the oxygen supplied was used. Perfect combustion is when all the oxygen supplied is used. No excess oxygen remains. Perfect combustion would be the ideal i the boiler operation, but instead, excess air is supplied to assure complete combustion.

4. The three areas of controllable heat loss in the boiler are:
........ 1. The first area of heat loss is excess air out the stack. The operator should keep a close eye on the fuel/air ratio to help minimize this problem.

........ 2. The second way to prevent heat loss is to make sure there isn't any unburned combustibles, ash or refuse. This includes combustible gases which shouldn't be allowed out the stack.

........ 3. The third area is radiated heat loss through the unit. If the boiler is kept well insulated, you can help reduce this heat loss as well.

5. Fuel is burned in the cyclone and temperatures reach around 3000 F. This temperature melts the ash into a sticky slag which forms a layer on the walls of the cyclone. This sticky slag layer catches the larger coal particles, while rapidly swirling air scrubs the coal particles with oxygen, causing combustion. Excess slag

------------------------------------------------- 20 ------------------------------------------------------

#BoilerManual #OptimizingCombustion #Section9 #Page20

Answers for optimizing combustion

1. Combustion is the rapid chemical combination of oxygen with the combustible elements in fuel, that produces heat.

2. The Three T's of Combustion are:

........ 1. ____Time__________________________

........ 2. ____Temperature____________________

........ 3. ____Turbulence_____________________

3. Complete combustion occurs when fuel and oxygen are combined and all the fuel is completely burned. However, not all the oxygen supplied was used. Perfect combustion is when all the oxygen supplied is used. No excess oxygen remains. Perfect combustion would be the ideal i the boiler operation, but instead, excess air is supplied to assure complete combustion.

4. The three areas of controllable heat loss in the boiler are:
........ 1. The first area of heat loss is excess air out the stack. The operator should keep a close eye on the fuel/air ratio to help minimize this problem.

........ 2. The second way to prevent heat loss is to make sure there isn't any unburned combustibles, ash or refuse. This includes combustible gases which shouldn't be allowed out the stack.

........ 3. The third area is radiated heat loss through the unit. If the boiler is kept well insulated, you can help reduce this heat loss as well.

5. Fuel is burned in the cyclone and temperatures reach around 3000 F. This temperature melts the ash into a sticky slag which forms a layer on the walls of the cyclone. This sticky slag layer catches the larger coal particles, while rapidly swirling air scrubs the coal particles with oxygen, causing combustion. Excess slag

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#BoilerManual #OptimizingCombustion #Section9 #Page19

7. What three materials in coal are important to its suitability as fuel?

........ 1. __________________________________

........ 2. __________________________________

........ 3. __________________________________

8. What are the four steps that can help prevent iron sulfide formation?

........ 1. __________________________________

........ 2. __________________________________

........ 3. __________________________________

........ 4. __________________________________

9. What is slag viscosity and why is it critical to the cyclone furnace?

10. Name five conditions which affect coal-ash deposits in your furnace.

........ 1. __________________________________

........ 2. __________________________________

........ 3. __________________________________

........ 4. __________________________________

........ 5. __________________________________

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#BoilerManual #OptimizingCombustion #Section9 #Page19

7. What three materials in coal are important to its suitability as fuel?

........ 1. __________________________________

........ 2. __________________________________

........ 3. __________________________________

8. What are the four steps that can help prevent iron sulfide formation?

........ 1. __________________________________

........ 2. __________________________________

........ 3. __________________________________

........ 4. __________________________________

9. What is slag viscosity and why is it critical to the cyclone furnace?

10. Name five conditions which affect coal-ash deposits in your furnace.

........ 1. __________________________________

........ 2. __________________________________

........ 3. __________________________________

........ 4. __________________________________

........ 5. __________________________________

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#BoilerManual #OptimizingCombustion #Section9 #Page18

Questions for optimizing combustion

1. What is the definition of combustion?

2. What are the Three T's of Combustion?

........ 1. __________________________________

........ 2. __________________________________

........ 3. __________________________________

3. What is the difference between complete combustion and perfect combustion?

4. Name three areas of controllable heat loss in the boiler.

........ 1. __________________________________

........ 2. __________________________________

........ 3. __________________________________

5. Explain how the cyclone furnace works?

6. Name five requirements necessary for slag tap furnaces.

........ 1. __________________________________

........ 2. __________________________________

........ 3. __________________________________

........ 4. __________________________________

........ 5. __________________________________

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#BoilerManual #OptimizingCombustion #Section9 #Page18

Questions for optimizing combustion

1. What is the definition of combustion?

2. What are the Three T's of Combustion?

........ 1. __________________________________

........ 2. __________________________________

........ 3. __________________________________

3. What is the difference between complete combustion and perfect combustion?

4. Name three areas of controllable heat loss in the boiler.

........ 1. __________________________________

........ 2. __________________________________

........ 3. __________________________________

5. Explain how the cyclone furnace works?

6. Name five requirements necessary for slag tap furnaces.

........ 1. __________________________________

........ 2. __________________________________

........ 3. __________________________________

........ 4. __________________________________

........ 5. __________________________________

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#BoilerManual #OptimizingCombustion #Section9 #Page17

decreased boiler efficiency as well as the formation of combustible products that can present a hazardous condition in the convection pass and air heaters, as well as in the furnace.

In view of he great number of factors involved in the combustion of any fuel, it is obvious that the specific requirements for the proper combustion of the fuel must be considered a distinct problem. It is possible, however, from the foregoing to draw certain general requirements of proper combustion.

1. The admission of an air supply that will assure sufficient oxygen for complete combustion, (fuel/air ratio).

2. Since complete combustion is not necessarily efficient combustion, it must be secured without permitting the dilution of the products of combustion with excess air, (fuel/air ratio).

3. The air supply should be admitted at the proper time in such a manner tht the oxygen of the air comes into free and thorough contact with the combustible substances of the fuel, (time and turbulence).

4. The gases must be maintained at a temperature equal to or above their ignition point until combustion is complete, (temperature).

In this section of the operator training manual we have reviewed the principles of the combustion process and have examined the inefficiencies which result in combustion losses. Suitability of fuels in relation to cyclone operation as well as the by-products of combustion such as slag and coal ash, were examined along with the effect of operating variables on these deposits.

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#BoilerManual #OptimizingCombustion #Section9 #Page17

decreased boiler efficiency as well as the formation of combustible products that can present a hazardous condition in the convection pass and air heaters, as well as in the furnace.

In view of he great number of factors involved in the combustion of any fuel, it is obvious that the specific requirements for the proper combustion of the fuel must be considered a distinct problem. It is possible, however, from the foregoing to draw certain general requirements of proper combustion.

1. The admission of an air supply that will assure sufficient oxygen for complete combustion, (fuel/air ratio).

2. Since complete combustion is not necessarily efficient combustion, it must be secured without permitting the dilution of the products of combustion with excess air, (fuel/air ratio).

3. The air supply should be admitted at the proper time in such a manner tht the oxygen of the air comes into free and thorough contact with the combustible substances of the fuel, (time and turbulence).

4. The gases must be maintained at a temperature equal to or above their ignition point until combustion is complete, (temperature).

In this section of the operator training manual we have reviewed the principles of the combustion process and have examined the inefficiencies which result in combustion losses. Suitability of fuels in relation to cyclone operation as well as the by-products of combustion such as slag and coal ash, were examined along with the effect of operating variables on these deposits.

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#BoilerManual #OptimizingCombustion #Section9 #Page16

COMBUSTION GUIDES

It is necessary to provide the operating personnel with a device to allow manual or automatic proportioning of the amount of air to the amount of fuel.

The level of excess air is one index that is commonly used to determine the performance of the unit and to guide its everyday operation. Excess air is the amount of air supplied over and above that required for theoretically perfect combustion. It is always necessary to supply some excess air to assure complete combustion of the fuel. Any excess air not actually required constitutes a substantial loss in the form of decreased boiler efficiency and thus, a higher fuel bill. On the other hand, operating boiler efficiency and thus, a higher fuel bull. On the other hand, operating with a deficiency of air flow for the fuel being burned can also result in

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Alt = Labeled Fig. 5 Effect of sintering time. The graph is laid out exactly like Fig. 4 except for how the y axis is incremented (0 to 50, in 10s), and has 3 curves like Fig. 4 but the coal type labels aren't here--each curve is marked in respective order: 168 hours, 15 hours, and 4 hours, and the curves all have steeper curves upward, and are marked with small circles at the points where they cross vertical lines from the x axis. The 168 hours curve terminates slightly beyond where the 1500 F and the 40 mark of psi intersect; the 15 hours curve terminates exactly at the intersection of 1600 F and the 50 mark of psi; the 4 hour curve originates just to the left side of the 1500 F mark just above 0 mark of psi, and terminates just beyond where 1700 F intersects with the 30 mark of psi.