#page5 — Public Fediverse posts
Live and recent posts from across the Fediverse tagged #page5, aggregated by home.social.
-
#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
-------------------------------------------------- 5 ------------------------------------------------------ -
#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
-------------------------------------------------- 5 ------------------------------------------------------ -
#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
-------------------------------------------------- 5 ------------------------------------------------------ -
#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
-------------------------------------------------- 5 ------------------------------------------------------ -
#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
-------------------------------------------------- 5 ------------------------------------------------------ -
#BoilerManual #OptimizingCombustion #Section9 #Page5
450,000 to 800,000 Btu/cu.ft. per hour and gas temperatures exceeding 3,000 F are developed. These temperatures are sufficiently high to melt the ash into a liquid slag, which form as a layer on the walls of the cyclone. The incoming coal particles (except for a few fines that are burned in suspension) are thrown to the walls by centrifugal force, held in the slag, and scrubbed by the high-velocity tangential secondary air. Thus, the air required to burn the coal is quickly supplied, and the products of combustion are rapidly removed.
The release of heat per cubic foot in the cyclone furnace is very high. However, there is only a small amount of surface in the cyclone and this surface is partially insulated by the covering slag layer. Heat absorption rates range from 40,000 to 80,000 Btu/sq. ft. hour. This combination of high heat release and low heat absorption assures the high temperature necessary to complete combustion and to provide the desired liquid slag coating.
The gaseous products of combustion are discharged through the water-cooled re-entrant throat of the cyclone, Figure 1, into the gas-cooling furnace.Molten slag in excess of the thin layer retained on the walls continually drains away from the burner end and discharges through the slag tap opening, to the boiler furnace, from which it is tapped into a slag tank, solidified, and disintegrated for disposal.
By this method of combustion the fuel is burned quickly and completely in the small cyclone chamber, and the boiler furnace is used mainly for cooling the flue gases. Most of the ash is retained as a liquid slag and tapped into the slag tank under the boiler furnace. Thus the quantity of flyash is low.
-------------------------------------------------- 5 ------------------------------------------------------
-
#BoilerManual #OptimizingCombustion #Section9 #Page5
450,000 to 800,000 Btu/cu.ft. per hour and gas temperatures exceeding 3,000 F are developed. These temperatures are sufficiently high to melt the ash into a liquid slag, which form as a layer on the walls of the cyclone. The incoming coal particles (except for a few fines that are burned in suspension) are thrown to the walls by centrifugal force, held in the slag, and scrubbed by the high-velocity tangential secondary air. Thus, the air required to burn the coal is quickly supplied, and the products of combustion are rapidly removed.
The release of heat per cubic foot in the cyclone furnace is very high. However, there is only a small amount of surface in the cyclone and this surface is partially insulated by the covering slag layer. Heat absorption rates range from 40,000 to 80,000 Btu/sq. ft. hour. This combination of high heat release and low heat absorption assures the high temperature necessary to complete combustion and to provide the desired liquid slag coating.
The gaseous products of combustion are discharged through the water-cooled re-entrant throat of the cyclone, Figure 1, into the gas-cooling furnace.Molten slag in excess of the thin layer retained on the walls continually drains away from the burner end and discharges through the slag tap opening, to the boiler furnace, from which it is tapped into a slag tank, solidified, and disintegrated for disposal.
By this method of combustion the fuel is burned quickly and completely in the small cyclone chamber, and the boiler furnace is used mainly for cooling the flue gases. Most of the ash is retained as a liquid slag and tapped into the slag tank under the boiler furnace. Thus the quantity of flyash is low.
-------------------------------------------------- 5 ------------------------------------------------------
-
#BoilerManual #OptimizingCombustion #Section9 #Page5
450,000 to 800,000 Btu/cu.ft. per hour and gas temperatures exceeding 3,000 F are developed. These temperatures are sufficiently high to melt the ash into a liquid slag, which form as a layer on the walls of the cyclone. The incoming coal particles (except for a few fines that are burned in suspension) are thrown to the walls by centrifugal force, held in the slag, and scrubbed by the high-velocity tangential secondary air. Thus, the air required to burn the coal is quickly supplied, and the products of combustion are rapidly removed.
The release of heat per cubic foot in the cyclone furnace is very high. However, there is only a small amount of surface in the cyclone and this surface is partially insulated by the covering slag layer. Heat absorption rates range from 40,000 to 80,000 Btu/sq. ft. hour. This combination of high heat release and low heat absorption assures the high temperature necessary to complete combustion and to provide the desired liquid slag coating.
The gaseous products of combustion are discharged through the water-cooled re-entrant throat of the cyclone, Figure 1, into the gas-cooling furnace.Molten slag in excess of the thin layer retained on the walls continually drains away from the burner end and discharges through the slag tap opening, to the boiler furnace, from which it is tapped into a slag tank, solidified, and disintegrated for disposal.
By this method of combustion the fuel is burned quickly and completely in the small cyclone chamber, and the boiler furnace is used mainly for cooling the flue gases. Most of the ash is retained as a liquid slag and tapped into the slag tank under the boiler furnace. Thus the quantity of flyash is low.
-------------------------------------------------- 5 ------------------------------------------------------
-
#BoilerManual #OptimizingCombustion #Section9 #Page5
450,000 to 800,000 Btu/cu.ft. per hour and gas temperatures exceeding 3,000 F are developed. These temperatures are sufficiently high to melt the ash into a liquid slag, which form as a layer on the walls of the cyclone. The incoming coal particles (except for a few fines that are burned in suspension) are thrown to the walls by centrifugal force, held in the slag, and scrubbed by the high-velocity tangential secondary air. Thus, the air required to burn the coal is quickly supplied, and the products of combustion are rapidly removed.
The release of heat per cubic foot in the cyclone furnace is very high. However, there is only a small amount of surface in the cyclone and this surface is partially insulated by the covering slag layer. Heat absorption rates range from 40,000 to 80,000 Btu/sq. ft. hour. This combination of high heat release and low heat absorption assures the high temperature necessary to complete combustion and to provide the desired liquid slag coating.
The gaseous products of combustion are discharged through the water-cooled re-entrant throat of the cyclone, Figure 1, into the gas-cooling furnace.Molten slag in excess of the thin layer retained on the walls continually drains away from the burner end and discharges through the slag tap opening, to the boiler furnace, from which it is tapped into a slag tank, solidified, and disintegrated for disposal.
By this method of combustion the fuel is burned quickly and completely in the small cyclone chamber, and the boiler furnace is used mainly for cooling the flue gases. Most of the ash is retained as a liquid slag and tapped into the slag tank under the boiler furnace. Thus the quantity of flyash is low.
-------------------------------------------------- 5 ------------------------------------------------------
-
#BoilerManual #OptimizingCombustion #Section9 #Page5
450,000 to 800,000 Btu/cu.ft. per hour and gas temperatures exceeding 3,000 F are developed. These temperatures are sufficiently high to melt the ash into a liquid slag, which form as a layer on the walls of the cyclone. The incoming coal particles (except for a few fines that are burned in suspension) are thrown to the walls by centrifugal force, held in the slag, and scrubbed by the high-velocity tangential secondary air. Thus, the air required to burn the coal is quickly supplied, and the products of combustion are rapidly removed.
The release of heat per cubic foot in the cyclone furnace is very high. However, there is only a small amount of surface in the cyclone and this surface is partially insulated by the covering slag layer. Heat absorption rates range from 40,000 to 80,000 Btu/sq. ft. hour. This combination of high heat release and low heat absorption assures the high temperature necessary to complete combustion and to provide the desired liquid slag coating.
The gaseous products of combustion are discharged through the water-cooled re-entrant throat of the cyclone, Figure 1, into the gas-cooling furnace.Molten slag in excess of the thin layer retained on the walls continually drains away from the burner end and discharges through the slag tap opening, to the boiler furnace, from which it is tapped into a slag tank, solidified, and disintegrated for disposal.
By this method of combustion the fuel is burned quickly and completely in the small cyclone chamber, and the boiler furnace is used mainly for cooling the flue gases. Most of the ash is retained as a liquid slag and tapped into the slag tank under the boiler furnace. Thus the quantity of flyash is low.
-------------------------------------------------- 5 ------------------------------------------------------
-
#BoilerManual #Ramping #Section8 #Page5
-------------------------------------------------- 5 ------------------------------------------------------
Alt = Labeled Fig. 3 Ramping -- Pressurizing superheater Image is just like the one before this one, sideways with the bottom long the right edge and the top along the left edge, but with the focus on the relationship between the superheaters and the flashtank. Please refer to the main text for details. -
#BoilerManual #Ramping #Section8 #Page5
-------------------------------------------------- 5 ------------------------------------------------------
Alt = Labeled Fig. 3 Ramping -- Pressurizing superheater Image is just like the one before this one, sideways with the bottom long the right edge and the top along the left edge, but with the focus on the relationship between the superheaters and the flashtank. Please refer to the main text for details. -
#BoilerManual #Ramping #Section8 #Page5
-------------------------------------------------- 5 ------------------------------------------------------
Alt = Labeled Fig. 3 Ramping -- Pressurizing superheater Image is just like the one before this one, sideways with the bottom long the right edge and the top along the left edge, but with the focus on the relationship between the superheaters and the flashtank. Please refer to the main text for details. -
#BoilerManual #Ramping #Section8 #Page5
-------------------------------------------------- 5 ------------------------------------------------------
Alt = Labeled Fig. 3 Ramping -- Pressurizing superheater Image is just like the one before this one, sideways with the bottom long the right edge and the top along the left edge, but with the focus on the relationship between the superheaters and the flashtank. Please refer to the main text for details. -
#BoilerManual #Ramping #Section8 #Page5
-------------------------------------------------- 5 ------------------------------------------------------
Alt = Labeled Fig. 3 Ramping -- Pressurizing superheater Image is just like the one before this one, sideways with the bottom long the right edge and the top along the left edge, but with the focus on the relationship between the superheaters and the flashtank. Please refer to the main text for details. -
#BoilerManual #BypassSystem #Section7 #Page5
water to a level corresponding to a cation conductivity of one micromho at the economizer inlet before firing is started. {Some chemistry basics: this is referencing ion content of water, where cations and anions are polar opposites. Ions in the water provide spare electrons to make water conductive, and that's why conductivity--the opposite of resistivity--is the desired measurement for this in water...therefore whereas the unit of resistance measurement is the ohm, the unit of conductivity is ohm spelled backwards: mho.} During cold cleanup operation the turbine is sealed, the condenser is under vacuum and every effort is made to keep oxygen out of the system. A nitrogen blanket may be provided for the deaerator, a vacuum line may be connected to the condenser, or the vents closed on the deaerator. Auxiliary steam should be used if available to obtain deaeration.
Hot cleanup Mode
Note: We are presently using only hot cleanup mode, without flashtank drains to the DA {Deaerator}, due to turbine manufacturer's steam purity requirements.
The cyclones are fired and the temperature of the water being circulated is slowly increased. During this period, the boiler and economizer slough off some deposits
(primarily iron oxide) as they heat up. If the system is dirty, as it happens with a new system or after acid cleaning, cleanup must be complete before exceeding a fluid temperature of 550 F in the boiler. Flashtank drains are directed to the condenser and then to the condensate polishing system for cleanup until iron content leaving the condensate polisher falls below 100 ppb {parts per billion}. Since early turbine sealing and feedwater deaeration are necessary to protect the unit from oxygen corrosion the deaerator is vented to the condenser until flashtank steam is available for deaeration. After the deaerator s supplied, excess flashtank steam can be used to warm, roll and load the turbine. Before deaeration is obtained every effort should be made to keep oxygen out of the system. DA is vented to condenser during startup and maintained at a slight vacuum.Startup Mode
This mode is used after hot cleanup is accomplished, or when it is not
-------------------------------------------------- 5 ------------------------------------------------------
-
#BoilerManual #BypassSystem #Section7 #Page5
water to a level corresponding to a cation conductivity of one micromho at the economizer inlet before firing is started. {Some chemistry basics: this is referencing ion content of water, where cations and anions are polar opposites. Ions in the water provide spare electrons to make water conductive, and that's why conductivity--the opposite of resistivity--is the desired measurement for this in water...therefore whereas the unit of resistance measurement is the ohm, the unit of conductivity is ohm spelled backwards: mho.} During cold cleanup operation the turbine is sealed, the condenser is under vacuum and every effort is made to keep oxygen out of the system. A nitrogen blanket may be provided for the deaerator, a vacuum line may be connected to the condenser, or the vents closed on the deaerator. Auxiliary steam should be used if available to obtain deaeration.
Hot cleanup Mode
Note: We are presently using only hot cleanup mode, without flashtank drains to the DA {Deaerator}, due to turbine manufacturer's steam purity requirements.
The cyclones are fired and the temperature of the water being circulated is slowly increased. During this period, the boiler and economizer slough off some deposits
(primarily iron oxide) as they heat up. If the system is dirty, as it happens with a new system or after acid cleaning, cleanup must be complete before exceeding a fluid temperature of 550 F in the boiler. Flashtank drains are directed to the condenser and then to the condensate polishing system for cleanup until iron content leaving the condensate polisher falls below 100 ppb {parts per billion}. Since early turbine sealing and feedwater deaeration are necessary to protect the unit from oxygen corrosion the deaerator is vented to the condenser until flashtank steam is available for deaeration. After the deaerator s supplied, excess flashtank steam can be used to warm, roll and load the turbine. Before deaeration is obtained every effort should be made to keep oxygen out of the system. DA is vented to condenser during startup and maintained at a slight vacuum.Startup Mode
This mode is used after hot cleanup is accomplished, or when it is not
-------------------------------------------------- 5 ------------------------------------------------------
-
#BoilerManual #BypassSystem #Section7 #Page5
water to a level corresponding to a cation conductivity of one micromho at the economizer inlet before firing is started. {Some chemistry basics: this is referencing ion content of water, where cations and anions are polar opposites. Ions in the water provide spare electrons to make water conductive, and that's why conductivity--the opposite of resistivity--is the desired measurement for this in water...therefore whereas the unit of resistance measurement is the ohm, the unit of conductivity is ohm spelled backwards: mho.} During cold cleanup operation the turbine is sealed, the condenser is under vacuum and every effort is made to keep oxygen out of the system. A nitrogen blanket may be provided for the deaerator, a vacuum line may be connected to the condenser, or the vents closed on the deaerator. Auxiliary steam should be used if available to obtain deaeration.
Hot cleanup Mode
Note: We are presently using only hot cleanup mode, without flashtank drains to the DA {Deaerator}, due to turbine manufacturer's steam purity requirements.
The cyclones are fired and the temperature of the water being circulated is slowly increased. During this period, the boiler and economizer slough off some deposits
(primarily iron oxide) as they heat up. If the system is dirty, as it happens with a new system or after acid cleaning, cleanup must be complete before exceeding a fluid temperature of 550 F in the boiler. Flashtank drains are directed to the condenser and then to the condensate polishing system for cleanup until iron content leaving the condensate polisher falls below 100 ppb {parts per billion}. Since early turbine sealing and feedwater deaeration are necessary to protect the unit from oxygen corrosion the deaerator is vented to the condenser until flashtank steam is available for deaeration. After the deaerator s supplied, excess flashtank steam can be used to warm, roll and load the turbine. Before deaeration is obtained every effort should be made to keep oxygen out of the system. DA is vented to condenser during startup and maintained at a slight vacuum.Startup Mode
This mode is used after hot cleanup is accomplished, or when it is not
-------------------------------------------------- 5 ------------------------------------------------------
-
#BoilerManual #BypassSystem #Section7 #Page5
water to a level corresponding to a cation conductivity of one micromho at the economizer inlet before firing is started. {Some chemistry basics: this is referencing ion content of water, where cations and anions are polar opposites. Ions in the water provide spare electrons to make water conductive, and that's why conductivity--the opposite of resistivity--is the desired measurement for this in water...therefore whereas the unit of resistance measurement is the ohm, the unit of conductivity is ohm spelled backwards: mho.} During cold cleanup operation the turbine is sealed, the condenser is under vacuum and every effort is made to keep oxygen out of the system. A nitrogen blanket may be provided for the deaerator, a vacuum line may be connected to the condenser, or the vents closed on the deaerator. Auxiliary steam should be used if available to obtain deaeration.
Hot cleanup Mode
Note: We are presently using only hot cleanup mode, without flashtank drains to the DA {Deaerator}, due to turbine manufacturer's steam purity requirements.
The cyclones are fired and the temperature of the water being circulated is slowly increased. During this period, the boiler and economizer slough off some deposits
(primarily iron oxide) as they heat up. If the system is dirty, as it happens with a new system or after acid cleaning, cleanup must be complete before exceeding a fluid temperature of 550 F in the boiler. Flashtank drains are directed to the condenser and then to the condensate polishing system for cleanup until iron content leaving the condensate polisher falls below 100 ppb {parts per billion}. Since early turbine sealing and feedwater deaeration are necessary to protect the unit from oxygen corrosion the deaerator is vented to the condenser until flashtank steam is available for deaeration. After the deaerator s supplied, excess flashtank steam can be used to warm, roll and load the turbine. Before deaeration is obtained every effort should be made to keep oxygen out of the system. DA is vented to condenser during startup and maintained at a slight vacuum.Startup Mode
This mode is used after hot cleanup is accomplished, or when it is not
-------------------------------------------------- 5 ------------------------------------------------------
-
#BoilerManual #BypassSystem #Section7 #Page5
water to a level corresponding to a cation conductivity of one micromho at the economizer inlet before firing is started. {Some chemistry basics: this is referencing ion content of water, where cations and anions are polar opposites. Ions in the water provide spare electrons to make water conductive, and that's why conductivity--the opposite of resistivity--is the desired measurement for this in water...therefore whereas the unit of resistance measurement is the ohm, the unit of conductivity is ohm spelled backwards: mho.} During cold cleanup operation the turbine is sealed, the condenser is under vacuum and every effort is made to keep oxygen out of the system. A nitrogen blanket may be provided for the deaerator, a vacuum line may be connected to the condenser, or the vents closed on the deaerator. Auxiliary steam should be used if available to obtain deaeration.
Hot cleanup Mode
Note: We are presently using only hot cleanup mode, without flashtank drains to the DA {Deaerator}, due to turbine manufacturer's steam purity requirements.
The cyclones are fired and the temperature of the water being circulated is slowly increased. During this period, the boiler and economizer slough off some deposits
(primarily iron oxide) as they heat up. If the system is dirty, as it happens with a new system or after acid cleaning, cleanup must be complete before exceeding a fluid temperature of 550 F in the boiler. Flashtank drains are directed to the condenser and then to the condensate polishing system for cleanup until iron content leaving the condensate polisher falls below 100 ppb {parts per billion}. Since early turbine sealing and feedwater deaeration are necessary to protect the unit from oxygen corrosion the deaerator is vented to the condenser until flashtank steam is available for deaeration. After the deaerator s supplied, excess flashtank steam can be used to warm, roll and load the turbine. Before deaeration is obtained every effort should be made to keep oxygen out of the system. DA is vented to condenser during startup and maintained at a slight vacuum.Startup Mode
This mode is used after hot cleanup is accomplished, or when it is not
-------------------------------------------------- 5 ------------------------------------------------------
-
#BoilerManual #CycloneOperation #Section6 #Page5
To ensure that sufficient air flow is provided to completely burn the fuel being fired, the requirement for air flow is increased whenever the measured fuel exceeds its requirement. The cyclone fuel requirement is compared with the measured total cyclone air flow which has been temperature compensated and calibrated for excess air requirements. Any difference will cause the Individual cyclone Air Flow Controls to reposition the velocity damper (secondary air flow control damper) until the measured cyclone air flow satisfies its requirement. A selector station is required for each cyclone to permit selection of automatic or manual operation of the velocity damper when desired.
Total Air Flow ControlAs the cyclone fuel loading increases, more air flow is obtained by opening the individual cyclone velocity dampers. The windbox to furnace differential setpoint may be varied from 30.5 to 32.5" H2O. An adjustable setpoint is provided to permit the operator to change the setpoint when desired. The Air Flow Control modulates the forced draft fan flow control to obtain the desired windbox to furnace delta-P.
The total air flow is then adjusted to obtain the desired flue gas O2 as measured at the economizer outlet.
BURNER OPERATION
The Bailey Control system continuously determines conditions pertinent to control of burner operation, then takes action based on three conditions. Conditions which must be recognized may be classified as follows:
-------------------------------------------------- 5 ------------------------------------------------------
-
#BoilerManual #CycloneOperation #Section6 #Page5
To ensure that sufficient air flow is provided to completely burn the fuel being fired, the requirement for air flow is increased whenever the measured fuel exceeds its requirement. The cyclone fuel requirement is compared with the measured total cyclone air flow which has been temperature compensated and calibrated for excess air requirements. Any difference will cause the Individual cyclone Air Flow Controls to reposition the velocity damper (secondary air flow control damper) until the measured cyclone air flow satisfies its requirement. A selector station is required for each cyclone to permit selection of automatic or manual operation of the velocity damper when desired.
Total Air Flow ControlAs the cyclone fuel loading increases, more air flow is obtained by opening the individual cyclone velocity dampers. The windbox to furnace differential setpoint may be varied from 30.5 to 32.5" H2O. An adjustable setpoint is provided to permit the operator to change the setpoint when desired. The Air Flow Control modulates the forced draft fan flow control to obtain the desired windbox to furnace delta-P.
The total air flow is then adjusted to obtain the desired flue gas O2 as measured at the economizer outlet.
BURNER OPERATION
The Bailey Control system continuously determines conditions pertinent to control of burner operation, then takes action based on three conditions. Conditions which must be recognized may be classified as follows:
-------------------------------------------------- 5 ------------------------------------------------------
-
#BoilerManual #CycloneOperation #Section6 #Page5
To ensure that sufficient air flow is provided to completely burn the fuel being fired, the requirement for air flow is increased whenever the measured fuel exceeds its requirement. The cyclone fuel requirement is compared with the measured total cyclone air flow which has been temperature compensated and calibrated for excess air requirements. Any difference will cause the Individual cyclone Air Flow Controls to reposition the velocity damper (secondary air flow control damper) until the measured cyclone air flow satisfies its requirement. A selector station is required for each cyclone to permit selection of automatic or manual operation of the velocity damper when desired.
Total Air Flow ControlAs the cyclone fuel loading increases, more air flow is obtained by opening the individual cyclone velocity dampers. The windbox to furnace differential setpoint may be varied from 30.5 to 32.5" H2O. An adjustable setpoint is provided to permit the operator to change the setpoint when desired. The Air Flow Control modulates the forced draft fan flow control to obtain the desired windbox to furnace delta-P.
The total air flow is then adjusted to obtain the desired flue gas O2 as measured at the economizer outlet.
BURNER OPERATION
The Bailey Control system continuously determines conditions pertinent to control of burner operation, then takes action based on three conditions. Conditions which must be recognized may be classified as follows:
-------------------------------------------------- 5 ------------------------------------------------------
-
#BoilerManual #CycloneOperation #Section6 #Page5
To ensure that sufficient air flow is provided to completely burn the fuel being fired, the requirement for air flow is increased whenever the measured fuel exceeds its requirement. The cyclone fuel requirement is compared with the measured total cyclone air flow which has been temperature compensated and calibrated for excess air requirements. Any difference will cause the Individual cyclone Air Flow Controls to reposition the velocity damper (secondary air flow control damper) until the measured cyclone air flow satisfies its requirement. A selector station is required for each cyclone to permit selection of automatic or manual operation of the velocity damper when desired.
Total Air Flow ControlAs the cyclone fuel loading increases, more air flow is obtained by opening the individual cyclone velocity dampers. The windbox to furnace differential setpoint may be varied from 30.5 to 32.5" H2O. An adjustable setpoint is provided to permit the operator to change the setpoint when desired. The Air Flow Control modulates the forced draft fan flow control to obtain the desired windbox to furnace delta-P.
The total air flow is then adjusted to obtain the desired flue gas O2 as measured at the economizer outlet.
BURNER OPERATION
The Bailey Control system continuously determines conditions pertinent to control of burner operation, then takes action based on three conditions. Conditions which must be recognized may be classified as follows:
-------------------------------------------------- 5 ------------------------------------------------------
-
#BoilerManual #CycloneOperation #Section6 #Page5
To ensure that sufficient air flow is provided to completely burn the fuel being fired, the requirement for air flow is increased whenever the measured fuel exceeds its requirement. The cyclone fuel requirement is compared with the measured total cyclone air flow which has been temperature compensated and calibrated for excess air requirements. Any difference will cause the Individual cyclone Air Flow Controls to reposition the velocity damper (secondary air flow control damper) until the measured cyclone air flow satisfies its requirement. A selector station is required for each cyclone to permit selection of automatic or manual operation of the velocity damper when desired.
Total Air Flow ControlAs the cyclone fuel loading increases, more air flow is obtained by opening the individual cyclone velocity dampers. The windbox to furnace differential setpoint may be varied from 30.5 to 32.5" H2O. An adjustable setpoint is provided to permit the operator to change the setpoint when desired. The Air Flow Control modulates the forced draft fan flow control to obtain the desired windbox to furnace delta-P.
The total air flow is then adjusted to obtain the desired flue gas O2 as measured at the economizer outlet.
BURNER OPERATION
The Bailey Control system continuously determines conditions pertinent to control of burner operation, then takes action based on three conditions. Conditions which must be recognized may be classified as follows:
-------------------------------------------------- 5 ------------------------------------------------------
-
#BoilerManual #CycloneDescription #Section5 #Page5
baffle plate also serves to keep the coal flow in the burner zone and moving out into the cyclone.
8. Replaceable Wear Blocks (Figure 3) - In the radial burner, the crushed coal is accelerated to the high velocity necessary to throw the heavier particles against the slagged surfaces of the cyclone barrel. This high velocity cases erosion of the burner, which is minimized by the use of tungsten carbide, ceramic, or other erosion-resistant wear liners.
9. Main Barrel (Figure 1) - Closely spaced, water-cooled, studded tubes shaped to form a cylinder. Inlet and outlet headers are connected into the boiler circulation systems by means of supply and riser tubes. The barrel tubes are arranged with the use of an intermediate header so that secondary air can be admitted tangentially along part of the cyclone length.
10. Neck (Figure 1) - Closely spaced, water-cooled, studded tubes shaped to form the front closure of the main barrel. Inlet and outlet headers are connected into the boiler circulation system by means of supply and riser tubes. The neck tubes are arranged such that the radial burner is positioned in the center of this front neck enclosure. These neck tubes are often referred to as cone tubes.
11. Re-entrant Throat* (Figures 1 & 4) - Closely spaced, water-cooled, studded tubes shaped to form a conical diffuser into the furnace. Inlet and outlet headers are connected to the boiler circulation system by means of supply and riser tubes. The gaseous products of combustion are discharged through the re-entrant throat of the cyclone into the boiler furnace.
12. Slag Tap* (Figures 1 & 4) - Offset water-cooled, studded tubes create an opening through the furnace wall. Molten slag in excess of the thin layer retained on the cyclone walls continually drains away
-------------------------------------------------- 5 ------------------------------------------------------
-
#BoilerManual #CycloneDescription #Section5 #Page5
baffle plate also serves to keep the coal flow in the burner zone and moving out into the cyclone.
8. Replaceable Wear Blocks (Figure 3) - In the radial burner, the crushed coal is accelerated to the high velocity necessary to throw the heavier particles against the slagged surfaces of the cyclone barrel. This high velocity cases erosion of the burner, which is minimized by the use of tungsten carbide, ceramic, or other erosion-resistant wear liners.
9. Main Barrel (Figure 1) - Closely spaced, water-cooled, studded tubes shaped to form a cylinder. Inlet and outlet headers are connected into the boiler circulation systems by means of supply and riser tubes. The barrel tubes are arranged with the use of an intermediate header so that secondary air can be admitted tangentially along part of the cyclone length.
10. Neck (Figure 1) - Closely spaced, water-cooled, studded tubes shaped to form the front closure of the main barrel. Inlet and outlet headers are connected into the boiler circulation system by means of supply and riser tubes. The neck tubes are arranged such that the radial burner is positioned in the center of this front neck enclosure. These neck tubes are often referred to as cone tubes.
11. Re-entrant Throat* (Figures 1 & 4) - Closely spaced, water-cooled, studded tubes shaped to form a conical diffuser into the furnace. Inlet and outlet headers are connected to the boiler circulation system by means of supply and riser tubes. The gaseous products of combustion are discharged through the re-entrant throat of the cyclone into the boiler furnace.
12. Slag Tap* (Figures 1 & 4) - Offset water-cooled, studded tubes create an opening through the furnace wall. Molten slag in excess of the thin layer retained on the cyclone walls continually drains away
-------------------------------------------------- 5 ------------------------------------------------------
-
#BoilerManual #CycloneDescription #Section5 #Page5
baffle plate also serves to keep the coal flow in the burner zone and moving out into the cyclone.
8. Replaceable Wear Blocks (Figure 3) - In the radial burner, the crushed coal is accelerated to the high velocity necessary to throw the heavier particles against the slagged surfaces of the cyclone barrel. This high velocity cases erosion of the burner, which is minimized by the use of tungsten carbide, ceramic, or other erosion-resistant wear liners.
9. Main Barrel (Figure 1) - Closely spaced, water-cooled, studded tubes shaped to form a cylinder. Inlet and outlet headers are connected into the boiler circulation systems by means of supply and riser tubes. The barrel tubes are arranged with the use of an intermediate header so that secondary air can be admitted tangentially along part of the cyclone length.
10. Neck (Figure 1) - Closely spaced, water-cooled, studded tubes shaped to form the front closure of the main barrel. Inlet and outlet headers are connected into the boiler circulation system by means of supply and riser tubes. The neck tubes are arranged such that the radial burner is positioned in the center of this front neck enclosure. These neck tubes are often referred to as cone tubes.
11. Re-entrant Throat* (Figures 1 & 4) - Closely spaced, water-cooled, studded tubes shaped to form a conical diffuser into the furnace. Inlet and outlet headers are connected to the boiler circulation system by means of supply and riser tubes. The gaseous products of combustion are discharged through the re-entrant throat of the cyclone into the boiler furnace.
12. Slag Tap* (Figures 1 & 4) - Offset water-cooled, studded tubes create an opening through the furnace wall. Molten slag in excess of the thin layer retained on the cyclone walls continually drains away
-------------------------------------------------- 5 ------------------------------------------------------
-
#BoilerManual #CycloneDescription #Section5 #Page5
baffle plate also serves to keep the coal flow in the burner zone and moving out into the cyclone.
8. Replaceable Wear Blocks (Figure 3) - In the radial burner, the crushed coal is accelerated to the high velocity necessary to throw the heavier particles against the slagged surfaces of the cyclone barrel. This high velocity cases erosion of the burner, which is minimized by the use of tungsten carbide, ceramic, or other erosion-resistant wear liners.
9. Main Barrel (Figure 1) - Closely spaced, water-cooled, studded tubes shaped to form a cylinder. Inlet and outlet headers are connected into the boiler circulation systems by means of supply and riser tubes. The barrel tubes are arranged with the use of an intermediate header so that secondary air can be admitted tangentially along part of the cyclone length.
10. Neck (Figure 1) - Closely spaced, water-cooled, studded tubes shaped to form the front closure of the main barrel. Inlet and outlet headers are connected into the boiler circulation system by means of supply and riser tubes. The neck tubes are arranged such that the radial burner is positioned in the center of this front neck enclosure. These neck tubes are often referred to as cone tubes.
11. Re-entrant Throat* (Figures 1 & 4) - Closely spaced, water-cooled, studded tubes shaped to form a conical diffuser into the furnace. Inlet and outlet headers are connected to the boiler circulation system by means of supply and riser tubes. The gaseous products of combustion are discharged through the re-entrant throat of the cyclone into the boiler furnace.
12. Slag Tap* (Figures 1 & 4) - Offset water-cooled, studded tubes create an opening through the furnace wall. Molten slag in excess of the thin layer retained on the cyclone walls continually drains away
-------------------------------------------------- 5 ------------------------------------------------------
-
#BoilerManual #CycloneDescription #Section5 #Page5
baffle plate also serves to keep the coal flow in the burner zone and moving out into the cyclone.
8. Replaceable Wear Blocks (Figure 3) - In the radial burner, the crushed coal is accelerated to the high velocity necessary to throw the heavier particles against the slagged surfaces of the cyclone barrel. This high velocity cases erosion of the burner, which is minimized by the use of tungsten carbide, ceramic, or other erosion-resistant wear liners.
9. Main Barrel (Figure 1) - Closely spaced, water-cooled, studded tubes shaped to form a cylinder. Inlet and outlet headers are connected into the boiler circulation systems by means of supply and riser tubes. The barrel tubes are arranged with the use of an intermediate header so that secondary air can be admitted tangentially along part of the cyclone length.
10. Neck (Figure 1) - Closely spaced, water-cooled, studded tubes shaped to form the front closure of the main barrel. Inlet and outlet headers are connected into the boiler circulation system by means of supply and riser tubes. The neck tubes are arranged such that the radial burner is positioned in the center of this front neck enclosure. These neck tubes are often referred to as cone tubes.
11. Re-entrant Throat* (Figures 1 & 4) - Closely spaced, water-cooled, studded tubes shaped to form a conical diffuser into the furnace. Inlet and outlet headers are connected to the boiler circulation system by means of supply and riser tubes. The gaseous products of combustion are discharged through the re-entrant throat of the cyclone into the boiler furnace.
12. Slag Tap* (Figures 1 & 4) - Offset water-cooled, studded tubes create an opening through the furnace wall. Molten slag in excess of the thin layer retained on the cyclone walls continually drains away
-------------------------------------------------- 5 ------------------------------------------------------
-
#BoilerManual #Lighters #Section4 #Page5
prevent furnace radiation from overheating the atomizer sprayer plate and end cap. Lighter fuel oil and purge air are turned off, and the ignition transformer is de-energized. Air pressure is normally maintained on the retracting piston to keep the lighter retracted.
3. OIL PURGE
During a normal shutdown of the ligher, all fuel oil is purged from the piping and atomizer to prevent oil from dripping into the burner or windbox. Purge air at 80-125 psi is admitted to the oil piping after the fuel oil valve is closed, but before the lighter is retracted and before the ignition transformer is de-energized. The purge should be continued until the lighter flame goes out. After the purge, the ignition transformer is de-energized and the lighter is retracted.
4. EMERGENCY STOP
If the lighter does not light within five seconds after its fuel oil valve is opened, if ignition is lost during operation, or if furnace conditions dictate that all fuel by tripped, the lighter fuel oil is turned off, the ignition transformer is de-energized, and the lighter is retracted.
LIGHT-OFF POSITION
Normally the interlocks are arranged so that certain requirements must be satisfied before the lighters can be started. These sequential requirements being:
1. Boiler not tripped.
2. Windbox/furnace delta-P is greater than 10 inches and less than 35 inches.
3. Boiler air flow is greater than 25%.
-------------------------------------------------- 5 ------------------------------------------------------
-
#BoilerManual #Lighters #Section4 #Page5
prevent furnace radiation from overheating the atomizer sprayer plate and end cap. Lighter fuel oil and purge air are turned off, and the ignition transformer is de-energized. Air pressure is normally maintained on the retracting piston to keep the lighter retracted.
3. OIL PURGE
During a normal shutdown of the ligher, all fuel oil is purged from the piping and atomizer to prevent oil from dripping into the burner or windbox. Purge air at 80-125 psi is admitted to the oil piping after the fuel oil valve is closed, but before the lighter is retracted and before the ignition transformer is de-energized. The purge should be continued until the lighter flame goes out. After the purge, the ignition transformer is de-energized and the lighter is retracted.
4. EMERGENCY STOP
If the lighter does not light within five seconds after its fuel oil valve is opened, if ignition is lost during operation, or if furnace conditions dictate that all fuel by tripped, the lighter fuel oil is turned off, the ignition transformer is de-energized, and the lighter is retracted.
LIGHT-OFF POSITION
Normally the interlocks are arranged so that certain requirements must be satisfied before the lighters can be started. These sequential requirements being:
1. Boiler not tripped.
2. Windbox/furnace delta-P is greater than 10 inches and less than 35 inches.
3. Boiler air flow is greater than 25%.
-------------------------------------------------- 5 ------------------------------------------------------
-
#BoilerManual #Lighters #Section4 #Page5
prevent furnace radiation from overheating the atomizer sprayer plate and end cap. Lighter fuel oil and purge air are turned off, and the ignition transformer is de-energized. Air pressure is normally maintained on the retracting piston to keep the lighter retracted.
3. OIL PURGE
During a normal shutdown of the ligher, all fuel oil is purged from the piping and atomizer to prevent oil from dripping into the burner or windbox. Purge air at 80-125 psi is admitted to the oil piping after the fuel oil valve is closed, but before the lighter is retracted and before the ignition transformer is de-energized. The purge should be continued until the lighter flame goes out. After the purge, the ignition transformer is de-energized and the lighter is retracted.
4. EMERGENCY STOP
If the lighter does not light within five seconds after its fuel oil valve is opened, if ignition is lost during operation, or if furnace conditions dictate that all fuel by tripped, the lighter fuel oil is turned off, the ignition transformer is de-energized, and the lighter is retracted.
LIGHT-OFF POSITION
Normally the interlocks are arranged so that certain requirements must be satisfied before the lighters can be started. These sequential requirements being:
1. Boiler not tripped.
2. Windbox/furnace delta-P is greater than 10 inches and less than 35 inches.
3. Boiler air flow is greater than 25%.
-------------------------------------------------- 5 ------------------------------------------------------
-
#BoilerManual #Lighters #Section4 #Page5
prevent furnace radiation from overheating the atomizer sprayer plate and end cap. Lighter fuel oil and purge air are turned off, and the ignition transformer is de-energized. Air pressure is normally maintained on the retracting piston to keep the lighter retracted.
3. OIL PURGE
During a normal shutdown of the ligher, all fuel oil is purged from the piping and atomizer to prevent oil from dripping into the burner or windbox. Purge air at 80-125 psi is admitted to the oil piping after the fuel oil valve is closed, but before the lighter is retracted and before the ignition transformer is de-energized. The purge should be continued until the lighter flame goes out. After the purge, the ignition transformer is de-energized and the lighter is retracted.
4. EMERGENCY STOP
If the lighter does not light within five seconds after its fuel oil valve is opened, if ignition is lost during operation, or if furnace conditions dictate that all fuel by tripped, the lighter fuel oil is turned off, the ignition transformer is de-energized, and the lighter is retracted.
LIGHT-OFF POSITION
Normally the interlocks are arranged so that certain requirements must be satisfied before the lighters can be started. These sequential requirements being:
1. Boiler not tripped.
2. Windbox/furnace delta-P is greater than 10 inches and less than 35 inches.
3. Boiler air flow is greater than 25%.
-------------------------------------------------- 5 ------------------------------------------------------
-
#BoilerManual #Lighters #Section4 #Page5
prevent furnace radiation from overheating the atomizer sprayer plate and end cap. Lighter fuel oil and purge air are turned off, and the ignition transformer is de-energized. Air pressure is normally maintained on the retracting piston to keep the lighter retracted.
3. OIL PURGE
During a normal shutdown of the ligher, all fuel oil is purged from the piping and atomizer to prevent oil from dripping into the burner or windbox. Purge air at 80-125 psi is admitted to the oil piping after the fuel oil valve is closed, but before the lighter is retracted and before the ignition transformer is de-energized. The purge should be continued until the lighter flame goes out. After the purge, the ignition transformer is de-energized and the lighter is retracted.
4. EMERGENCY STOP
If the lighter does not light within five seconds after its fuel oil valve is opened, if ignition is lost during operation, or if furnace conditions dictate that all fuel by tripped, the lighter fuel oil is turned off, the ignition transformer is de-energized, and the lighter is retracted.
LIGHT-OFF POSITION
Normally the interlocks are arranged so that certain requirements must be satisfied before the lighters can be started. These sequential requirements being:
1. Boiler not tripped.
2. Windbox/furnace delta-P is greater than 10 inches and less than 35 inches.
3. Boiler air flow is greater than 25%.
-------------------------------------------------- 5 ------------------------------------------------------
-
#BoilerManual #AirAndGasFlow #Section3 #Page5
AIR FLOW
Combustion air, commonly called secondary air, is supplied to the cyclones by three FD fans.
The FD fans are centrifugal fans {a.k.a. "squirrel cage" fan}. A centrifugal fan consists of a bladed rotor mounted on a shaft, and a fan housing. The rotor is driven through the shaft by a constant speed motor. A sketch showing the fan design is presented in Figure 2. Air is drawn into the center of the rotor, turns 90 degrees, and enters the space between the blades. The air is then forced away from the center of the rotor - hence the name centrifugal. Air leaves the fan at a higher velocity and higher pressure than it entered. As this happens, more air is drawn into the center of the fan.
When starting a fan, the inlet vanes must be closed in order to reduce the load while the fan is coming up to speed. Motor amps are high when initially starting a fan and until operating speed is reached. Once
-------------------------------------------------- 5 ------------------------------------------------------
Alt = Labeled Fig 2 Centrifugal fan. Drawing that depicts the outer housing of such a fan that is used on the furnace, resembling a large round hatbox laying on its edge but with attached ductwork. Top left is marked Outlet with an arrow pointing away from the fan; on the left is an oblong hopper-type duct marked Inlet with an arrow pointing into the hopper; near the bottom of the hopper is a box marked Motor. To the left of the Motor marking, on the other side of the housing, is marked Fan housing. -
#BoilerManual #AirAndGasFlow #Section3 #Page5
AIR FLOW
Combustion air, commonly called secondary air, is supplied to the cyclones by three FD fans.
The FD fans are centrifugal fans {a.k.a. "squirrel cage" fan}. A centrifugal fan consists of a bladed rotor mounted on a shaft, and a fan housing. The rotor is driven through the shaft by a constant speed motor. A sketch showing the fan design is presented in Figure 2. Air is drawn into the center of the rotor, turns 90 degrees, and enters the space between the blades. The air is then forced away from the center of the rotor - hence the name centrifugal. Air leaves the fan at a higher velocity and higher pressure than it entered. As this happens, more air is drawn into the center of the fan.
When starting a fan, the inlet vanes must be closed in order to reduce the load while the fan is coming up to speed. Motor amps are high when initially starting a fan and until operating speed is reached. Once
-------------------------------------------------- 5 ------------------------------------------------------
Alt = Labeled Fig 2 Centrifugal fan. Drawing that depicts the outer housing of such a fan that is used on the furnace, resembling a large round hatbox laying on its edge but with attached ductwork. Top left is marked Outlet with an arrow pointing away from the fan; on the left is an oblong hopper-type duct marked Inlet with an arrow pointing into the hopper; near the bottom of the hopper is a box marked Motor. To the left of the Motor marking, on the other side of the housing, is marked Fan housing. -
#BoilerManual #AirAndGasFlow #Section3 #Page5
AIR FLOW
Combustion air, commonly called secondary air, is supplied to the cyclones by three FD fans.
The FD fans are centrifugal fans {a.k.a. "squirrel cage" fan}. A centrifugal fan consists of a bladed rotor mounted on a shaft, and a fan housing. The rotor is driven through the shaft by a constant speed motor. A sketch showing the fan design is presented in Figure 2. Air is drawn into the center of the rotor, turns 90 degrees, and enters the space between the blades. The air is then forced away from the center of the rotor - hence the name centrifugal. Air leaves the fan at a higher velocity and higher pressure than it entered. As this happens, more air is drawn into the center of the fan.
When starting a fan, the inlet vanes must be closed in order to reduce the load while the fan is coming up to speed. Motor amps are high when initially starting a fan and until operating speed is reached. Once
-------------------------------------------------- 5 ------------------------------------------------------
Alt = Labeled Fig 2 Centrifugal fan. Drawing that depicts the outer housing of such a fan that is used on the furnace, resembling a large round hatbox laying on its edge but with attached ductwork. Top left is marked Outlet with an arrow pointing away from the fan; on the left is an oblong hopper-type duct marked Inlet with an arrow pointing into the hopper; near the bottom of the hopper is a box marked Motor. To the left of the Motor marking, on the other side of the housing, is marked Fan housing. -
#BoilerManual #AirAndGasFlow #Section3 #Page5
AIR FLOW
Combustion air, commonly called secondary air, is supplied to the cyclones by three FD fans.
The FD fans are centrifugal fans {a.k.a. "squirrel cage" fan}. A centrifugal fan consists of a bladed rotor mounted on a shaft, and a fan housing. The rotor is driven through the shaft by a constant speed motor. A sketch showing the fan design is presented in Figure 2. Air is drawn into the center of the rotor, turns 90 degrees, and enters the space between the blades. The air is then forced away from the center of the rotor - hence the name centrifugal. Air leaves the fan at a higher velocity and higher pressure than it entered. As this happens, more air is drawn into the center of the fan.
When starting a fan, the inlet vanes must be closed in order to reduce the load while the fan is coming up to speed. Motor amps are high when initially starting a fan and until operating speed is reached. Once
-------------------------------------------------- 5 ------------------------------------------------------
Alt = Labeled Fig 2 Centrifugal fan. Drawing that depicts the outer housing of such a fan that is used on the furnace, resembling a large round hatbox laying on its edge but with attached ductwork. Top left is marked Outlet with an arrow pointing away from the fan; on the left is an oblong hopper-type duct marked Inlet with an arrow pointing into the hopper; near the bottom of the hopper is a box marked Motor. To the left of the Motor marking, on the other side of the housing, is marked Fan housing. -
#BoilerManual #AirAndGasFlow #Section3 #Page5
AIR FLOW
Combustion air, commonly called secondary air, is supplied to the cyclones by three FD fans.
The FD fans are centrifugal fans {a.k.a. "squirrel cage" fan}. A centrifugal fan consists of a bladed rotor mounted on a shaft, and a fan housing. The rotor is driven through the shaft by a constant speed motor. A sketch showing the fan design is presented in Figure 2. Air is drawn into the center of the rotor, turns 90 degrees, and enters the space between the blades. The air is then forced away from the center of the rotor - hence the name centrifugal. Air leaves the fan at a higher velocity and higher pressure than it entered. As this happens, more air is drawn into the center of the fan.
When starting a fan, the inlet vanes must be closed in order to reduce the load while the fan is coming up to speed. Motor amps are high when initially starting a fan and until operating speed is reached. Once
-------------------------------------------------- 5 ------------------------------------------------------
Alt = Labeled Fig 2 Centrifugal fan. Drawing that depicts the outer housing of such a fan that is used on the furnace, resembling a large round hatbox laying on its edge but with attached ductwork. Top left is marked Outlet with an arrow pointing away from the fan; on the left is an oblong hopper-type duct marked Inlet with an arrow pointing into the hopper; near the bottom of the hopper is a box marked Motor. To the left of the Motor marking, on the other side of the housing, is marked Fan housing. -
#BoilerManual #FluidCirculation #Section2 #Page5
FUNDAMENTALS OF CIRCULATION
There are two basic types of utility boilers, drum and once-through. Circulation is significantly different in the two types.Drum boilers always operate at subcritical pressures. A steam/water mixture is generated in the furnace. Steam is separated from the water in the drum, and the steam temperature is increased in the superheaters. The water is recirculated to the furnace circuits by natural convection.
This natural circulation effect is caused by the difference between the density of water in the downcomers (non-heated tubes which are external to the furnace proper) and the lower mean density {now is a good time to bring to mind what you've learned of the difference between "mean" and "average"} of the steam/water mixture in the furnace tubes. This density differential provides the pumping head to assure adequate circulation (Figure 6). {...where I made unfortunate doodles around the word "mean", ha.}
-------------------------------------------------- 5 ------------------------------------------------------
Alt = Figure 4 labeled Critical pressure. The graph is incremented identically to Figures 2 thru 4, duplicating all but one of the curves mapped out in Figure 4. That one curve is the one from the peak area of the saturation curves to the upper right corner of the graph. This curve is now curving above the "dome" of saturation curves previously referenced before it shoots up to the upper right corner, labeled "3500 psi". -
#BoilerManual #FluidCirculation #Section2 #Page5
FUNDAMENTALS OF CIRCULATION
There are two basic types of utility boilers, drum and once-through. Circulation is significantly different in the two types.Drum boilers always operate at subcritical pressures. A steam/water mixture is generated in the furnace. Steam is separated from the water in the drum, and the steam temperature is increased in the superheaters. The water is recirculated to the furnace circuits by natural convection.
This natural circulation effect is caused by the difference between the density of water in the downcomers (non-heated tubes which are external to the furnace proper) and the lower mean density {now is a good time to bring to mind what you've learned of the difference between "mean" and "average"} of the steam/water mixture in the furnace tubes. This density differential provides the pumping head to assure adequate circulation (Figure 6). {...where I made unfortunate doodles around the word "mean", ha.}
-------------------------------------------------- 5 ------------------------------------------------------
Alt = Figure 4 labeled Critical pressure. The graph is incremented identically to Figures 2 thru 4, duplicating all but one of the curves mapped out in Figure 4. That one curve is the one from the peak area of the saturation curves to the upper right corner of the graph. This curve is now curving above the "dome" of saturation curves previously referenced before it shoots up to the upper right corner, labeled "3500 psi". -
#BoilerManual #FluidCirculation #Section2 #Page5
FUNDAMENTALS OF CIRCULATION
There are two basic types of utility boilers, drum and once-through. Circulation is significantly different in the two types.Drum boilers always operate at subcritical pressures. A steam/water mixture is generated in the furnace. Steam is separated from the water in the drum, and the steam temperature is increased in the superheaters. The water is recirculated to the furnace circuits by natural convection.
This natural circulation effect is caused by the difference between the density of water in the downcomers (non-heated tubes which are external to the furnace proper) and the lower mean density {now is a good time to bring to mind what you've learned of the difference between "mean" and "average"} of the steam/water mixture in the furnace tubes. This density differential provides the pumping head to assure adequate circulation (Figure 6). {...where I made unfortunate doodles around the word "mean", ha.}
-------------------------------------------------- 5 ------------------------------------------------------
Alt = Figure 4 labeled Critical pressure. The graph is incremented identically to Figures 2 thru 4, duplicating all but one of the curves mapped out in Figure 4. That one curve is the one from the peak area of the saturation curves to the upper right corner of the graph. This curve is now curving above the "dome" of saturation curves previously referenced before it shoots up to the upper right corner, labeled "3500 psi". -
#BoilerManual #FluidCirculation #Section2 #Page5
FUNDAMENTALS OF CIRCULATION
There are two basic types of utility boilers, drum and once-through. Circulation is significantly different in the two types.Drum boilers always operate at subcritical pressures. A steam/water mixture is generated in the furnace. Steam is separated from the water in the drum, and the steam temperature is increased in the superheaters. The water is recirculated to the furnace circuits by natural convection.
This natural circulation effect is caused by the difference between the density of water in the downcomers (non-heated tubes which are external to the furnace proper) and the lower mean density {now is a good time to bring to mind what you've learned of the difference between "mean" and "average"} of the steam/water mixture in the furnace tubes. This density differential provides the pumping head to assure adequate circulation (Figure 6). {...where I made unfortunate doodles around the word "mean", ha.}
-------------------------------------------------- 5 ------------------------------------------------------
Alt = Figure 4 labeled Critical pressure. The graph is incremented identically to Figures 2 thru 4, duplicating all but one of the curves mapped out in Figure 4. That one curve is the one from the peak area of the saturation curves to the upper right corner of the graph. This curve is now curving above the "dome" of saturation curves previously referenced before it shoots up to the upper right corner, labeled "3500 psi". -
#BoilerManual #FluidCirculation #Section2 #Page5
FUNDAMENTALS OF CIRCULATION
There are two basic types of utility boilers, drum and once-through. Circulation is significantly different in the two types.Drum boilers always operate at subcritical pressures. A steam/water mixture is generated in the furnace. Steam is separated from the water in the drum, and the steam temperature is increased in the superheaters. The water is recirculated to the furnace circuits by natural convection.
This natural circulation effect is caused by the difference between the density of water in the downcomers (non-heated tubes which are external to the furnace proper) and the lower mean density {now is a good time to bring to mind what you've learned of the difference between "mean" and "average"} of the steam/water mixture in the furnace tubes. This density differential provides the pumping head to assure adequate circulation (Figure 6). {...where I made unfortunate doodles around the word "mean", ha.}
-------------------------------------------------- 5 ------------------------------------------------------
Alt = Figure 4 labeled Critical pressure. The graph is incremented identically to Figures 2 thru 4, duplicating all but one of the curves mapped out in Figure 4. That one curve is the one from the peak area of the saturation curves to the upper right corner of the graph. This curve is now curving above the "dome" of saturation curves previously referenced before it shoots up to the upper right corner, labeled "3500 psi". -
@Su_G #BoilerManual #UnitDescription #Section1 #Page5
"
Each boiler delivers a maximum continuous main steam flow of 4,200,000 pounds per hour (lb/hr) to a Westinghouse steam turbine generator at 2620 pounds per square inch (PSI) and 1005 F in order to produce a nominal electrical generating capacity of 600 megawatts (MW). At full load the boiler reheater cycle provides 3,788,000 lb/hr of steam to the turbine generator at a pressure of 521 PSI and a temperature of 1005 F. The maximum continuous steam flow is based upon a feedwater temperature of 481 F. Each unit is capable of maintaining normal full load with one cyclone out of service. {A cyclone is where the fire happens}It is necessary to control steam temperature to correct for fluctuations caused by operating variables. Above 33% load, main steam temperature is controlled by firing rate and two (2) spray attemperators {spray nozzles}. Reheat steam temperature is controlled over 80% load by gas recirculation and one (1) attemperator.
B&W Scope of Supply
*Boiler
*Bypass System
*Economizer
*Primary Superheater
*Secondary Superheater
*Reheat Superheater
*Cyclones
*Air Heater
*Flues and Ducts
*Platform Steel
*Refractories and Insulation {still asbestos, folks}
*Accessories
"
-------------------------------------------------- 5 ------------------------------------------------------ -
@Su_G #BoilerManual #UnitDescription #Section1 #Page5
"
Each boiler delivers a maximum continuous main steam flow of 4,200,000 pounds per hour (lb/hr) to a Westinghouse steam turbine generator at 2620 pounds per square inch (PSI) and 1005 F in order to produce a nominal electrical generating capacity of 600 megawatts (MW). At full load the boiler reheater cycle provides 3,788,000 lb/hr of steam to the turbine generator at a pressure of 521 PSI and a temperature of 1005 F. The maximum continuous steam flow is based upon a feedwater temperature of 481 F. Each unit is capable of maintaining normal full load with one cyclone out of service. {A cyclone is where the fire happens}It is necessary to control steam temperature to correct for fluctuations caused by operating variables. Above 33% load, main steam temperature is controlled by firing rate and two (2) spray attemperators {spray nozzles}. Reheat steam temperature is controlled over 80% load by gas recirculation and one (1) attemperator.
B&W Scope of Supply
*Boiler
*Bypass System
*Economizer
*Primary Superheater
*Secondary Superheater
*Reheat Superheater
*Cyclones
*Air Heater
*Flues and Ducts
*Platform Steel
*Refractories and Insulation {still asbestos, folks}
*Accessories
"
-------------------------------------------------- 5 ------------------------------------------------------ -
@Su_G #BoilerManual #UnitDescription #Section1 #Page5
"
Each boiler delivers a maximum continuous main steam flow of 4,200,000 pounds per hour (lb/hr) to a Westinghouse steam turbine generator at 2620 pounds per square inch (PSI) and 1005 F in order to produce a nominal electrical generating capacity of 600 megawatts (MW). At full load the boiler reheater cycle provides 3,788,000 lb/hr of steam to the turbine generator at a pressure of 521 PSI and a temperature of 1005 F. The maximum continuous steam flow is based upon a feedwater temperature of 481 F. Each unit is capable of maintaining normal full load with one cyclone out of service. {A cyclone is where the fire happens}It is necessary to control steam temperature to correct for fluctuations caused by operating variables. Above 33% load, main steam temperature is controlled by firing rate and two (2) spray attemperators {spray nozzles}. Reheat steam temperature is controlled over 80% load by gas recirculation and one (1) attemperator.
B&W Scope of Supply
*Boiler
*Bypass System
*Economizer
*Primary Superheater
*Secondary Superheater
*Reheat Superheater
*Cyclones
*Air Heater
*Flues and Ducts
*Platform Steel
*Refractories and Insulation {still asbestos, folks}
*Accessories
"
-------------------------------------------------- 5 ------------------------------------------------------ -
@Su_G #BoilerManual #UnitDescription #Section1 #Page5
"
Each boiler delivers a maximum continuous main steam flow of 4,200,000 pounds per hour (lb/hr) to a Westinghouse steam turbine generator at 2620 pounds per square inch (PSI) and 1005 F in order to produce a nominal electrical generating capacity of 600 megawatts (MW). At full load the boiler reheater cycle provides 3,788,000 lb/hr of steam to the turbine generator at a pressure of 521 PSI and a temperature of 1005 F. The maximum continuous steam flow is based upon a feedwater temperature of 481 F. Each unit is capable of maintaining normal full load with one cyclone out of service. {A cyclone is where the fire happens}It is necessary to control steam temperature to correct for fluctuations caused by operating variables. Above 33% load, main steam temperature is controlled by firing rate and two (2) spray attemperators {spray nozzles}. Reheat steam temperature is controlled over 80% load by gas recirculation and one (1) attemperator.
B&W Scope of Supply
*Boiler
*Bypass System
*Economizer
*Primary Superheater
*Secondary Superheater
*Reheat Superheater
*Cyclones
*Air Heater
*Flues and Ducts
*Platform Steel
*Refractories and Insulation {still asbestos, folks}
*Accessories
"
-------------------------------------------------- 5 ------------------------------------------------------ -
@Su_G #BoilerManual #UnitDescription #Section1 #Page5
"
Each boiler delivers a maximum continuous main steam flow of 4,200,000 pounds per hour (lb/hr) to a Westinghouse steam turbine generator at 2620 pounds per square inch (PSI) and 1005 F in order to produce a nominal electrical generating capacity of 600 megawatts (MW). At full load the boiler reheater cycle provides 3,788,000 lb/hr of steam to the turbine generator at a pressure of 521 PSI and a temperature of 1005 F. The maximum continuous steam flow is based upon a feedwater temperature of 481 F. Each unit is capable of maintaining normal full load with one cyclone out of service. {A cyclone is where the fire happens}It is necessary to control steam temperature to correct for fluctuations caused by operating variables. Above 33% load, main steam temperature is controlled by firing rate and two (2) spray attemperators {spray nozzles}. Reheat steam temperature is controlled over 80% load by gas recirculation and one (1) attemperator.
B&W Scope of Supply
*Boiler
*Bypass System
*Economizer
*Primary Superheater
*Secondary Superheater
*Reheat Superheater
*Cyclones
*Air Heater
*Flues and Ducts
*Platform Steel
*Refractories and Insulation {still asbestos, folks}
*Accessories
"
-------------------------------------------------- 5 ------------------------------------------------------