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#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 #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 #Ramping #Section8 #Page20
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Alt = Simply labeled Fig. 9, but the title at the top reads EXAMPLE: INCORRECT PRE-RAMP CONDITIONS. Like Fig. 6, this is a set of 3 charts with the x axis markings in common.The y axis on the top chart is marked Valve position --%; it's set in increments of 20, and plot lines for, top down order, 202 valve, 201 valve, then to the left bottom the 207 valve and to the right bottom, the 2000 valve.
The middle chart's y axis is marked thrice over, first in terms of Boiler and firing rate master % next to the axis, incremented by 5s up to 20 and then an unmarked line across; to the left is marked corresponding Megawatts, in increments of 20s; further to the left of that is marked Throttle pressure, in corresponding terms from 500 to 2500 in increments. The lines appear intertwined but are distinguished from each other by type of line drawn.
Firing rate is drawn with alternating dashes and dots; Boiler master is short dashes; MW line is solid but appears intertwined with Boiler master. The lowest line is by itself, in a solid line, marked Throttle pressure.
The bottom chart's y axis is marked twice over, first as Convection pass and PSH outlet temperature, from 620 to 800 incremented in 20s; correspondingly marked to the left of that as SSH outlet temperature, from 800 to 1050 in increments of 50. The lines, in top down order, are PSH (drawn as an alternating dash dot line), SSH (drawn as a solid line), and Convection pass (drawn as a line of short dashes). What's going on is explained in detail by the main text.
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#BoilerManual #Ramping #Section8 #Page20
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Alt = Simply labeled Fig. 9, but the title at the top reads EXAMPLE: INCORRECT PRE-RAMP CONDITIONS. Like Fig. 6, this is a set of 3 charts with the x axis markings in common.The y axis on the top chart is marked Valve position --%; it's set in increments of 20, and plot lines for, top down order, 202 valve, 201 valve, then to the left bottom the 207 valve and to the right bottom, the 2000 valve.
The middle chart's y axis is marked thrice over, first in terms of Boiler and firing rate master % next to the axis, incremented by 5s up to 20 and then an unmarked line across; to the left is marked corresponding Megawatts, in increments of 20s; further to the left of that is marked Throttle pressure, in corresponding terms from 500 to 2500 in increments. The lines appear intertwined but are distinguished from each other by type of line drawn.
Firing rate is drawn with alternating dashes and dots; Boiler master is short dashes; MW line is solid but appears intertwined with Boiler master. The lowest line is by itself, in a solid line, marked Throttle pressure.
The bottom chart's y axis is marked twice over, first as Convection pass and PSH outlet temperature, from 620 to 800 incremented in 20s; correspondingly marked to the left of that as SSH outlet temperature, from 800 to 1050 in increments of 50. The lines, in top down order, are PSH (drawn as an alternating dash dot line), SSH (drawn as a solid line), and Convection pass (drawn as a line of short dashes). What's going on is explained in detail by the main text.
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#BoilerManual #BypassSystem #Section7 #Page20
Questions for bypass system
1. Why is a bypass system needed for the universal pressure boiler?
2. Name the four different phases or modes of boiler operation during the bypass
system........... 1. ________________________________
.......... 2. ________________________________
.......... 3. ________________________________
.......... 4. ________________________________
3. What are the main purposes of cold cleanup?4. Briefly describe the cold cleanup mode of the boiler startup.
5. Briefly describe the hot cleanup phase.
6. When can the startup phase begin?
7. Briefly describe the startup phase.
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#BoilerManual #BypassSystem #Section7 #Page20
Questions for bypass system
1. Why is a bypass system needed for the universal pressure boiler?
2. Name the four different phases or modes of boiler operation during the bypass
system........... 1. ________________________________
.......... 2. ________________________________
.......... 3. ________________________________
.......... 4. ________________________________
3. What are the main purposes of cold cleanup?4. Briefly describe the cold cleanup mode of the boiler startup.
5. Briefly describe the hot cleanup phase.
6. When can the startup phase begin?
7. Briefly describe the startup phase.
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#BoilerManual #CycloneOperation #Section6 #Page20
There is a 5 second delay between the time the feeder stops and the feeder outlet valve closes. This allows the coal line to be clear of coal before closing the valve.
The feeder may be run manually only when the cyclone is in the test mode. Therefore, if the feeder is unloaded for maintenance purposes, the cyclone must be put in test in order to fill the feeder belt, prior to startup of the cyclone.
FLAME MONITOR
The boiler flame monitor logic continually monitors the boiler for a Fuel No Flame condition. An immediate boiler trip will occur if no flame is detected in the boiler and any cyclone is tripped. Effectively, if one cyclone is in service and it trips, an immediate boiler trip will occur. During a furnace purge, a no flame trip delay of 30 seconds will be initiated (no cyclone tripped) so that continuous boiler trips will not occur as a result of no flame detection at startup.
During normal operation if a feeder is running and main flame is not detected on that cyclone for more than 30 seconds, and unit load is less than 60%, the boiler is tripped. If a total flame-out occurs, the boiler is tripped after a 30 second time delay.
This concludes out discussion on cyclone operation. You should now be familiar with the associated equipment for cyclone firing, the controls used in this process and the various operational parameters which must be satisfied to maintain efficient operation of the system.
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#BoilerManual #CycloneOperation #Section6 #Page20
There is a 5 second delay between the time the feeder stops and the feeder outlet valve closes. This allows the coal line to be clear of coal before closing the valve.
The feeder may be run manually only when the cyclone is in the test mode. Therefore, if the feeder is unloaded for maintenance purposes, the cyclone must be put in test in order to fill the feeder belt, prior to startup of the cyclone.
FLAME MONITOR
The boiler flame monitor logic continually monitors the boiler for a Fuel No Flame condition. An immediate boiler trip will occur if no flame is detected in the boiler and any cyclone is tripped. Effectively, if one cyclone is in service and it trips, an immediate boiler trip will occur. During a furnace purge, a no flame trip delay of 30 seconds will be initiated (no cyclone tripped) so that continuous boiler trips will not occur as a result of no flame detection at startup.
During normal operation if a feeder is running and main flame is not detected on that cyclone for more than 30 seconds, and unit load is less than 60%, the boiler is tripped. If a total flame-out occurs, the boiler is tripped after a 30 second time delay.
This concludes out discussion on cyclone operation. You should now be familiar with the associated equipment for cyclone firing, the controls used in this process and the various operational parameters which must be satisfied to maintain efficient operation of the system.
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#BoilerManual #CycloneDescription #Section5 #Page20
Answers for cyclone description
1. Centrifugal force throws the heavier coal particles away from the cyclone's center and onto the slag-covered barrel tubes.
2. Combustion occurs in the main barrel of the cyclone. Primary air and coal are mixed into a whirling motion in the radial burner.
3. Tertiary air cools the burner front, it is then forced through a hole in a baffle plate to enter the burner zone. This action keeps the coal flow in the burner zone moving out into the cyclone.
4. Secondary air is the main source of oxygen in the cyclone. Secondary air comprises about 80% of the total air admitted to the cyclone.
5. The three requirements the cyclone meets which are needed for complete and efficient coal combustion are:
............ 1. ___Time__________
............ 2. ___Temperature____
............ 3. ___Turbulence_____6. The answer is A and D. Both conditions can cause slag tapping problems.
7. A small amount of excess air leads to complete combustion with high flame temperatures. A large amount of excess air leads to complete combustion with high flame temperatures. A large amount of excess air only lowers temperatures in the cyclone.
8. The rapid combustion in the cyclone makes it very responsive to load demands. Boiler output can be controlled very quickly by changing the coal-feeder speed.
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#BoilerManual #CycloneDescription #Section5 #Page20
Answers for cyclone description
1. Centrifugal force throws the heavier coal particles away from the cyclone's center and onto the slag-covered barrel tubes.
2. Combustion occurs in the main barrel of the cyclone. Primary air and coal are mixed into a whirling motion in the radial burner.
3. Tertiary air cools the burner front, it is then forced through a hole in a baffle plate to enter the burner zone. This action keeps the coal flow in the burner zone moving out into the cyclone.
4. Secondary air is the main source of oxygen in the cyclone. Secondary air comprises about 80% of the total air admitted to the cyclone.
5. The three requirements the cyclone meets which are needed for complete and efficient coal combustion are:
............ 1. ___Time__________
............ 2. ___Temperature____
............ 3. ___Turbulence_____6. The answer is A and D. Both conditions can cause slag tapping problems.
7. A small amount of excess air leads to complete combustion with high flame temperatures. A large amount of excess air leads to complete combustion with high flame temperatures. A large amount of excess air only lowers temperatures in the cyclone.
8. The rapid combustion in the cyclone makes it very responsive to load demands. Boiler output can be controlled very quickly by changing the coal-feeder speed.
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#BoilerManual #Lighters #Section4 #Page20
8. Fill-In.
When the atomizer is removed for cleaning, it should always be cleaned with a ______________ and never ______________ .
......................................... (Turn to the next page for the answers)
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#BoilerManual #Lighters #Section4 #Page20
8. Fill-In.
When the atomizer is removed for cleaning, it should always be cleaned with a ______________ and never ______________ .
......................................... (Turn to the next page for the answers)
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#BoilerManual #AirAndGasFlow #Section3 #Page20
The amount of O2 in the flue gases is significant in defining the status of the combustion process. Its presence means that more oxygen (excess air) is being introduced than is being used. O2 is related to excess air, as shown in Figure 15. Assuming complete combustion, low values of O2 in the flue gas indicates a moderate amount of excess air and reduced heat losses up the stack. Higher values of O2 indicate that excessive heat losses may be present. The flue gas analysis which normally is done at the economizer outlet flue represents only the results of the average state of combustion in the furnace. It does not indicate that there is a correct or desirable fuel/air ratio on all of the cyclones. It is up to the operator, with the help of the fuel/air flow meters for each cyclone, to keep the fuel/air ratio the same on all the cyclones. This is often called balanced firing. If and only if the cyclones are balanced will the flue gas analysis indicate the state of combustion at the cyclones. It is quite possible to have a normal O2 reading and yet still be carrying over large amounts of unburned fuel to the precipitator. This seemingly contradictory situation is generally the result of unbalanced firing. That is, some cyclones have a lot more air going to them than is needed to burn the fuel,
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Alt = A graph labeled Fig. 14 Effect of boiler load on excess air requirements. Both x and y axes are in terms of percentage, marked only with 0 and 100. X axis is is marked Boiler load (percent). Y axis is marked Boiler load (percent). The curve starts on the left at a high but unmarked percentage level and diminishes as it approaches a higher boiler load percentage. -
#BoilerManual #AirAndGasFlow #Section3 #Page20
The amount of O2 in the flue gases is significant in defining the status of the combustion process. Its presence means that more oxygen (excess air) is being introduced than is being used. O2 is related to excess air, as shown in Figure 15. Assuming complete combustion, low values of O2 in the flue gas indicates a moderate amount of excess air and reduced heat losses up the stack. Higher values of O2 indicate that excessive heat losses may be present. The flue gas analysis which normally is done at the economizer outlet flue represents only the results of the average state of combustion in the furnace. It does not indicate that there is a correct or desirable fuel/air ratio on all of the cyclones. It is up to the operator, with the help of the fuel/air flow meters for each cyclone, to keep the fuel/air ratio the same on all the cyclones. This is often called balanced firing. If and only if the cyclones are balanced will the flue gas analysis indicate the state of combustion at the cyclones. It is quite possible to have a normal O2 reading and yet still be carrying over large amounts of unburned fuel to the precipitator. This seemingly contradictory situation is generally the result of unbalanced firing. That is, some cyclones have a lot more air going to them than is needed to burn the fuel,
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Alt = A graph labeled Fig. 14 Effect of boiler load on excess air requirements. Both x and y axes are in terms of percentage, marked only with 0 and 100. X axis is is marked Boiler load (percent). Y axis is marked Boiler load (percent). The curve starts on the left at a high but unmarked percentage level and diminishes as it approaches a higher boiler load percentage. -
#BoilerManual #FluidCirculation #Section2 #Page20
Let's continue on with the example; flow continues from the second circuit of the cyclone B5 to the third circuit of cyclone B3, then the fourth circuit of cyclone B1 and the fifth circuit of cyclone A2 to the sixth circuit of cyclone A4 to the last circuit, seven, in cyclone A6. Refer to Chart II for a tabulation of cyclone interconnections.
The discharge from circuit 7 of all cyclones is directed toward one of two cyclone discharge bottles. Seven cyclones of one wall discharge into a common mix bottle. The two bottles join and form a mix bottle which supplies the furnace front, rear, and side walls.
........................................................CHART I
...........................Cyclone Circuit Interconnections (Example)............................................................Flow Path..........................Cyclone
.................Circuit................Cyclone No................Location..........1. Neck.......................................B7........................................Lower
..........2. Barrel......................................B5........................................Lower
..........3. Barrel......................................B3........................................Lower
..........4. Barrel......................................B1........................................Lower
..........5. Barrel......................................A2........................................Upper
..........6. Barrel......................................A4........................................Upper
..........7. Re-entrant Throat...................A6........................................Upper........................................................CHART II
.................Circuit................Path A...............Path B
..........1. Neck.......................................A7.............................A6
..........2. Barrel......................................B6.............................B7
..........3. Barrel......................................B4.............................B5
..........4. Barrel......................................B2.............................B3
..........5. Barrel......................................A1.............................B1
..........6. Barrel......................................A3.............................A2
..........7. Re-entrant Throat..................A5............................A4------------------------------------------------- 20 ------------------------------------------------------
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#BoilerManual #FluidCirculation #Section2 #Page20
Let's continue on with the example; flow continues from the second circuit of the cyclone B5 to the third circuit of cyclone B3, then the fourth circuit of cyclone B1 and the fifth circuit of cyclone A2 to the sixth circuit of cyclone A4 to the last circuit, seven, in cyclone A6. Refer to Chart II for a tabulation of cyclone interconnections.
The discharge from circuit 7 of all cyclones is directed toward one of two cyclone discharge bottles. Seven cyclones of one wall discharge into a common mix bottle. The two bottles join and form a mix bottle which supplies the furnace front, rear, and side walls.
........................................................CHART I
...........................Cyclone Circuit Interconnections (Example)............................................................Flow Path..........................Cyclone
.................Circuit................Cyclone No................Location..........1. Neck.......................................B7........................................Lower
..........2. Barrel......................................B5........................................Lower
..........3. Barrel......................................B3........................................Lower
..........4. Barrel......................................B1........................................Lower
..........5. Barrel......................................A2........................................Upper
..........6. Barrel......................................A4........................................Upper
..........7. Re-entrant Throat...................A6........................................Upper........................................................CHART II
.................Circuit................Path A...............Path B
..........1. Neck.......................................A7.............................A6
..........2. Barrel......................................B6.............................B7
..........3. Barrel......................................B4.............................B5
..........4. Barrel......................................B2.............................B3
..........5. Barrel......................................A1.............................B1
..........6. Barrel......................................A3.............................A2
..........7. Re-entrant Throat..................A5............................A4------------------------------------------------- 20 ------------------------------------------------------
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@Su_G #BoilerManual #UnitDescription #Section1 #Page20
You have now been provided with a brief component description of the Babcock & Wilcox steam enerators at the Baldwin Power Station. The major steam generator auxiliaries, along with their functions and locations, have been described and a brief description of the combustion and heat transfer process has been presented. This information will provide you with the necessary foundation which will facilitate your understanding of the following detailed descriptions of the operating parameters and characteristics of your steam generating unit.
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@Su_G #BoilerManual #UnitDescription #Section1 #Page20
You have now been provided with a brief component description of the Babcock & Wilcox steam enerators at the Baldwin Power Station. The major steam generator auxiliaries, along with their functions and locations, have been described and a brief description of the combustion and heat transfer process has been presented. This information will provide you with the necessary foundation which will facilitate your understanding of the following detailed descriptions of the operating parameters and characteristics of your steam generating unit.
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