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#BoilerManual #ProtectingPressureParts #Section10 #Page4

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

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

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

BOILER PROTECTION

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

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

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#BoilerManual #ProtectingPressureParts #Section10 #Page4

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

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

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

BOILER PROTECTION

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

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

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#BoilerManual #OptimizingCombustion #Section9 #Page4

combustion. Excess air would not be required if it were possible to have perfect combustion of air and fuel. It is necessary, however, to keep the excess at a minimum in order to hold down the stack loss. The excess air that is not used in the combustion of the fuel leaves the unit at stack temperature. The heat required to heat this air from room temperature to stack temperature serves no purpose and is lost heat.

In summary, there are certain heat loses over which there is no control, and certain others which are subject to some control. The inherent losses are the result of (1) the discharge of the products of combustion at a temperature higher than ambient, and (2) the moisture content of the fuel plus the combination of some of the hydrogen with the oxygen in the fuel.

The heat losses which are controllable by careful operation, can be minimized by:

1. Careful control of fuel and air ratios on a per cyclone basis.

2. Tolerating virtually no unburned solid combustible matter in ash or refuse.

3. Permitting no unburned gaseous combustibles in the exit gases.

4. A well-insulated settling for the steam generating unit to reduce radiation loss.

The efficiency of combustion in a heat exchanger or boiler is 100 minus the sum of the heat losses expressed in percent.

CYCLONE COMBUSTION

The combustibles are burned from the fuel at heat release rates of

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#BoilerManual #OptimizingCombustion #Section9 #Page4

combustion. Excess air would not be required if it were possible to have perfect combustion of air and fuel. It is necessary, however, to keep the excess at a minimum in order to hold down the stack loss. The excess air that is not used in the combustion of the fuel leaves the unit at stack temperature. The heat required to heat this air from room temperature to stack temperature serves no purpose and is lost heat.

In summary, there are certain heat loses over which there is no control, and certain others which are subject to some control. The inherent losses are the result of (1) the discharge of the products of combustion at a temperature higher than ambient, and (2) the moisture content of the fuel plus the combination of some of the hydrogen with the oxygen in the fuel.

The heat losses which are controllable by careful operation, can be minimized by:

1. Careful control of fuel and air ratios on a per cyclone basis.

2. Tolerating virtually no unburned solid combustible matter in ash or refuse.

3. Permitting no unburned gaseous combustibles in the exit gases.

4. A well-insulated settling for the steam generating unit to reduce radiation loss.

The efficiency of combustion in a heat exchanger or boiler is 100 minus the sum of the heat losses expressed in percent.

CYCLONE COMBUSTION

The combustibles are burned from the fuel at heat release rates of

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#BoilerManual #Ramping #Section8 #Page4

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Alt = Fig. 2 Ramping -- Opening of 201 valves. 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 201 set of valve {there's only one in the drawing.You'd have to go all the way back to the previous section, page 2, to discover that there exists, in series, a 201A valve next to the 201}, following the details laid out in the main text.

#BoilerManual #Ramping #Section8 #Page4

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Alt = Fig. 2 Ramping -- Opening of 201 valves. 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 201 set of valve {there's only one in the drawing.You'd have to go all the way back to the previous section, page 2, to discover that there exists, in series, a 201A valve next to the 201}, following the details laid out in the main text.

#BoilerManual #BypassSystem #Section7 #Page4

less than 33% flow. The bypass system provides a method of maintaining the 33% flow requirement through the boiler, passing some of the fluid to the turbine as superheated steam is required, and returning the difference to the feedwater cycle.

BYPASS SYSTEM

Steam is separated from water in the steam drum of the drum type boiler. As pressure increases, superheated steam is available to warm and roll the turbine due to the separation process.

The once-through UP boiler does not have a drum for separation as it is designed to provide a pure, superheated steam leaving the boiler under normal operating conditions. But during startup, a pure steam does not leave the boiler due to the low heat input to the unit. The flashtank, with its associated valves and piping provide a method of separating the water and steam, ensuring superheated steam to the turbine.

BYPASS SYSTEM OPERATION

During the course of a plant startup, the Universal Pressure boiler bypass system is operated in four different modes as follows:

Cold Cleanup Mode

Before firing, water is circulated at the full startup or minimum design flow rate through the boiler, primary superheater, flashtank, condenser and condensate polishing system to reduce impurities. The condensate polishing system is an arrangement of demineralizers designed to purify the condensate to meet the feedwater purity requirements of a once-through boiler. This equipment is used to reduce impurities in the boiler

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#BoilerManual #BypassSystem #Section7 #Page4

less than 33% flow. The bypass system provides a method of maintaining the 33% flow requirement through the boiler, passing some of the fluid to the turbine as superheated steam is required, and returning the difference to the feedwater cycle.

BYPASS SYSTEM

Steam is separated from water in the steam drum of the drum type boiler. As pressure increases, superheated steam is available to warm and roll the turbine due to the separation process.

The once-through UP boiler does not have a drum for separation as it is designed to provide a pure, superheated steam leaving the boiler under normal operating conditions. But during startup, a pure steam does not leave the boiler due to the low heat input to the unit. The flashtank, with its associated valves and piping provide a method of separating the water and steam, ensuring superheated steam to the turbine.

BYPASS SYSTEM OPERATION

During the course of a plant startup, the Universal Pressure boiler bypass system is operated in four different modes as follows:

Cold Cleanup Mode

Before firing, water is circulated at the full startup or minimum design flow rate through the boiler, primary superheater, flashtank, condenser and condensate polishing system to reduce impurities. The condensate polishing system is an arrangement of demineralizers designed to purify the condensate to meet the feedwater purity requirements of a once-through boiler. This equipment is used to reduce impurities in the boiler

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#BoilerManual #CycloneOperation #Section6 #Page4

FUEL FLOW CONTROL

The measured fuel flow from individual cyclones is totaled and compared with the total fuel required. Any difference is corrected by changing the total fuel flow control on the cyclones in-service (on automatic).

The individual cyclone fuel flow must be controlled to maintain sufficient heat input to each cyclone to ensure that the slag remains in a molten condition so it will tap.

Individual Cyclone Fuel Flow Control

A manual bias is provided for each cyclone to permit an individual cyclone to carry more or less load with respect to the other cyclones. To insure that sufficient air is always available for burning the fuel safely, the cyclone fuel requirement is limited whenever the measured air flow fails to meet its requirement. Fuel flow to each cyclone is regulated by a variable speed gravimetric coal feeder. {Both the gravimetric and volumetric coal feeders required re-calibration by the C & I Department. This department had a book of listed routine assignments in addition to repair/replace function.} A selector station for each cyclone permits the operator to select automatic or to manually control the coal feeder speed when desired.

AIR FLOW CONTROL

The cyclone fuel requirement serves as the basis for individual cyclone air flow requirement. The Air Flow Control is designed to produce the correct air flow to satisfy the boiler requirements for total air while simultaneously ensuring that sufficient air flow is available for each cyclone in service. Provision is made to enable the air flow to lag its requirement both when the load is being decreased normally and following a unit trip.

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#BoilerManual #CycloneOperation #Section6 #Page4

FUEL FLOW CONTROL

The measured fuel flow from individual cyclones is totaled and compared with the total fuel required. Any difference is corrected by changing the total fuel flow control on the cyclones in-service (on automatic).

The individual cyclone fuel flow must be controlled to maintain sufficient heat input to each cyclone to ensure that the slag remains in a molten condition so it will tap.

Individual Cyclone Fuel Flow Control

A manual bias is provided for each cyclone to permit an individual cyclone to carry more or less load with respect to the other cyclones. To insure that sufficient air is always available for burning the fuel safely, the cyclone fuel requirement is limited whenever the measured air flow fails to meet its requirement. Fuel flow to each cyclone is regulated by a variable speed gravimetric coal feeder. {Both the gravimetric and volumetric coal feeders required re-calibration by the C & I Department. This department had a book of listed routine assignments in addition to repair/replace function.} A selector station for each cyclone permits the operator to select automatic or to manually control the coal feeder speed when desired.

AIR FLOW CONTROL

The cyclone fuel requirement serves as the basis for individual cyclone air flow requirement. The Air Flow Control is designed to produce the correct air flow to satisfy the boiler requirements for total air while simultaneously ensuring that sufficient air flow is available for each cyclone in service. Provision is made to enable the air flow to lag its requirement both when the load is being decreased normally and following a unit trip.

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#BoilerManual #CycloneDescription #Section5 #Page4

5. Primary-Tertiary Air Duct (Figure 2 & 6) - Up to 23% of the total air supplied to the cyclone is tapped off the windbox and enters the radial burner.

6. Primary-Tertiary Air Shutoff Damper (Figure 2) - Located in the take-off duct from the windbox to the radial burner. This damper will shut off primary-tertiary air flow to an idle cyclone,or may be set to a minimum position, depending upon plant operations.

7. Baffle Plate (Figure 3) - Separates the primary and tertiary air zones at the burner front. Tertiary air enters the radial burner through a small diameter hole at the center of the baffle plate. The

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Alt = Labeled Fig. 3 Radial burner. This image takes the named part displayed in Fig. 2 and shows its internal detail. The topside pipeline is marked Crushed coal inlet where it enters the radial burner barrel, which is cut open to reveal what is marked Wear blocks lining the barrel, to the left of the inlet. Marked in counter-clockwise order are where the Primary air and Tertiary air enter the burner barrel via the ductwork, and running through the ductwork are two rods marked Damper shaft, and are connected to the dampers inside the ducts. Next, at the front of the illustration is marked Burner door (water cooled); the cutaway of that reveals that there's a Baffle plate behind the door.

#BoilerManual #CycloneDescription #Section5 #Page4

5. Primary-Tertiary Air Duct (Figure 2 & 6) - Up to 23% of the total air supplied to the cyclone is tapped off the windbox and enters the radial burner.

6. Primary-Tertiary Air Shutoff Damper (Figure 2) - Located in the take-off duct from the windbox to the radial burner. This damper will shut off primary-tertiary air flow to an idle cyclone,or may be set to a minimum position, depending upon plant operations.

7. Baffle Plate (Figure 3) - Separates the primary and tertiary air zones at the burner front. Tertiary air enters the radial burner through a small diameter hole at the center of the baffle plate. The

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Alt = Labeled Fig. 3 Radial burner. This image takes the named part displayed in Fig. 2 and shows its internal detail. The topside pipeline is marked Crushed coal inlet where it enters the radial burner barrel, which is cut open to reveal what is marked Wear blocks lining the barrel, to the left of the inlet. Marked in counter-clockwise order are where the Primary air and Tertiary air enter the burner barrel via the ductwork, and running through the ductwork are two rods marked Damper shaft, and are connected to the dampers inside the ducts. Next, at the front of the illustration is marked Burner door (water cooled); the cutaway of that reveals that there's a Baffle plate behind the door.

#BoilerManual #Lighters #Section4 #Page4

after the fuel shutoff valve is closed. This purge air should be passed through a 60 mesh strainer, similar to the fuel oil strainer, to prevent plugging the atomizer with debris and scale from the purge air piping.

For rapid and complete oil purges, the fuel oil shutoff valve, purge air connection, and piping should be above the lighter. The total length of pipe to be purged should not exceed 50 feet. If piping and/or valves are below the lighter, the lowest point in the piping should not be more than 10 feet below the lighter and the total
length of piping to be purged should not exceed 25 feet.

OPERATION

The operator should be thoroughly familiar with the lighter, its controls, interlocks, main burners, and related equipment. Operation of the lighter in relation to furnace purging, air flow, and main fuel flow is described in the burner instructions. Normally, four operating conditions exist for the lighter:

1. LIGHT-OFF POSITION

.......... The lighter is moved to the light-off position by reversing the air pressure to the air piston. When the lighter is in the light-off (firing) position, the ignition transformer is energized and the fuel oil to the lighter is turned on. The ignition transformer is normally energized for as long as the fuel oil is being admitted to the lighter. The fuel oil valve should be opened slowly to prevent header pressure decay and possible loss of ignition on the other lighters supplied by the same header.

1. NORMAL SHUTDOWN

.......... When the lighter is not in use, it is retracted from the furnace to

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#BoilerManual #Lighters #Section4 #Page4

after the fuel shutoff valve is closed. This purge air should be passed through a 60 mesh strainer, similar to the fuel oil strainer, to prevent plugging the atomizer with debris and scale from the purge air piping.

For rapid and complete oil purges, the fuel oil shutoff valve, purge air connection, and piping should be above the lighter. The total length of pipe to be purged should not exceed 50 feet. If piping and/or valves are below the lighter, the lowest point in the piping should not be more than 10 feet below the lighter and the total
length of piping to be purged should not exceed 25 feet.

OPERATION

The operator should be thoroughly familiar with the lighter, its controls, interlocks, main burners, and related equipment. Operation of the lighter in relation to furnace purging, air flow, and main fuel flow is described in the burner instructions. Normally, four operating conditions exist for the lighter:

1. LIGHT-OFF POSITION

.......... The lighter is moved to the light-off position by reversing the air pressure to the air piston. When the lighter is in the light-off (firing) position, the ignition transformer is energized and the fuel oil to the lighter is turned on. The ignition transformer is normally energized for as long as the fuel oil is being admitted to the lighter. The fuel oil valve should be opened slowly to prevent header pressure decay and possible loss of ignition on the other lighters supplied by the same header.

1. NORMAL SHUTDOWN

.......... When the lighter is not in use, it is retracted from the furnace to

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#BoilerManual #AirAndGasFlow #Section3 #Page4

COMBUSTION AIR & GAS FLOW PRESSURES AND TEMPERATURES

.......................................................TABLE 1

.............................................................Expected..............................Operating
.............................................................Pressure.............................Temperature
1. Air Heater - air side ........................... +39.1 H2O.............................125 F

2. Duct - A.H. to windbox ...................... +30.0 .................................... 600 F

3. Windbox ............................................. -28.5 ...................................... 600 F

4. Furnace .............................................. -2.0 ........................................ 3000-2150 F

5. Pendant Convecton Pass ................. -2.1 ........................................ 2150-1660 F

6. Horizontal Convection Pass .............. -3.5 ....................................... 1660-1000 F

7. Economizer ........................................ -6.5 ........................................ 900-700 F

8. Flue - economizer to A.H. .................. -8.0 ....................................... 690 F

9. Flue - A.H. to gas recirculation fan ... -8.0 ....................................... 690 F

10. Flue - G.R. fan to dampers .............. +2.0 ...................................... 690 F

11. Recirculation & tempering ............... +1.0 ..................................... 690 F
......control dampers to ports

12. Flue - A.H. to precipitator ................ -15.0 .................................... 300 F

13. Windbox to furnace differential ...... +30.5

14. Penthouse .......................................... 0.0 ....................................... N/A

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#BoilerManual #AirAndGasFlow #Section3 #Page4

COMBUSTION AIR & GAS FLOW PRESSURES AND TEMPERATURES

.......................................................TABLE 1

.............................................................Expected..............................Operating
.............................................................Pressure.............................Temperature
1. Air Heater - air side ........................... +39.1 H2O.............................125 F

2. Duct - A.H. to windbox ...................... +30.0 .................................... 600 F

3. Windbox ............................................. -28.5 ...................................... 600 F

4. Furnace .............................................. -2.0 ........................................ 3000-2150 F

5. Pendant Convecton Pass ................. -2.1 ........................................ 2150-1660 F

6. Horizontal Convection Pass .............. -3.5 ....................................... 1660-1000 F

7. Economizer ........................................ -6.5 ........................................ 900-700 F

8. Flue - economizer to A.H. .................. -8.0 ....................................... 690 F

9. Flue - A.H. to gas recirculation fan ... -8.0 ....................................... 690 F

10. Flue - G.R. fan to dampers .............. +2.0 ...................................... 690 F

11. Recirculation & tempering ............... +1.0 ..................................... 690 F
......control dampers to ports

12. Flue - A.H. to precipitator ................ -15.0 .................................... 300 F

13. Windbox to furnace differential ...... +30.5

14. Penthouse .......................................... 0.0 ....................................... N/A

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#BoilerManual #FluidCirculation #Section2 #Page4

Notice that the 0 and 100% quality lines meet at the top of the curve in Figure 4 to form a dome. The pressure at which they meet (3208 psi) is termed the critical pressure. Pressures below the dome are referred to as subcritical.

At pressures above this value (supercritical pressures), there is no difference in density between steam and water. The term boiling point is meaningless because there is no single temperature (which corresponds to the horizontal constant pressure lines at subcritical pressures) where water is converted to steam. Rather, the conversion occurs gradually over a wide range of temperatures as shown in Figure 5. The constant pressure lines above 3208 psi are never horizontal, indicating that temperature always increases with increased heat input.

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Alt = Figure 4 labeled Critical pressure. The graph is incremented identically to Figure 2, but where the saturation percentage curves converge is between the 800 and 1000 Btu/lb area on the graph slightly above where the 700 F line is, pointed to by the label "Critical pressure (3208 psi)". A curve is drawn from that convergence area to the upper right side of the graph but that line is unlabeled in this graph.

#BoilerManual #FluidCirculation #Section2 #Page4

Notice that the 0 and 100% quality lines meet at the top of the curve in Figure 4 to form a dome. The pressure at which they meet (3208 psi) is termed the critical pressure. Pressures below the dome are referred to as subcritical.

At pressures above this value (supercritical pressures), there is no difference in density between steam and water. The term boiling point is meaningless because there is no single temperature (which corresponds to the horizontal constant pressure lines at subcritical pressures) where water is converted to steam. Rather, the conversion occurs gradually over a wide range of temperatures as shown in Figure 5. The constant pressure lines above 3208 psi are never horizontal, indicating that temperature always increases with increased heat input.

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Alt = Figure 4 labeled Critical pressure. The graph is incremented identically to Figure 2, but where the saturation percentage curves converge is between the 800 and 1000 Btu/lb area on the graph slightly above where the 700 F line is, pointed to by the label "Critical pressure (3208 psi)". A curve is drawn from that convergence area to the upper right side of the graph but that line is unlabeled in this graph.

@Su_G #BoilerManual #UnitDescription #Section1 #Page4
"
the use of pulverized coal firing was a major improvement over stoker firing, which contributed greatly to capacity.

The result is that today a single boiler can produce 10,000,000 pounds of steam per hour by burning more than 500 tons of coal per hour. Operating pressure in these large units range from 2,500 to almost 4,000 psi and steam temperature is usually 1,000 F or higher. These boilers operate dependably and safely, and remain in service for years {by my count, decades}.

But, for the full potential of the boilers to be realized, they must be opeated and maintained properly, and this job has become more difficult as the boilers have become more sophisticated. The purpose of this section of the training program is to familiarize you with the B&W boilers, and to help you realize all the benefits that 100 years of experience have incorporated into their design.

INTRODUCTION

The Baldwin Power Station, Units 1 and 2 consist of Babcock & Wilcox Universal Pressure (UP) boilers as seen in the attached side views. Practically of identical design, these cyclone-fired {explained later} balanced draft {forced and induced drafts} UP boilers are comprised of a water-cooled slag tap furnace {explained later} superheater, reheater, economizer and air heater. The units are designed to utilize crushed coal as the primary fuel with fuel oil as an ignition medium.
{The units actually utilized pulverized coal; after the coal was crushed, it went through a milling process before being loaded into the boilers}
"
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@Su_G #BoilerManual #UnitDescription #Section1 #Page4
"
the use of pulverized coal firing was a major improvement over stoker firing, which contributed greatly to capacity.

The result is that today a single boiler can produce 10,000,000 pounds of steam per hour by burning more than 500 tons of coal per hour. Operating pressure in these large units range from 2,500 to almost 4,000 psi and steam temperature is usually 1,000 F or higher. These boilers operate dependably and safely, and remain in service for years {by my count, decades}.

But, for the full potential of the boilers to be realized, they must be opeated and maintained properly, and this job has become more difficult as the boilers have become more sophisticated. The purpose of this section of the training program is to familiarize you with the B&W boilers, and to help you realize all the benefits that 100 years of experience have incorporated into their design.

INTRODUCTION

The Baldwin Power Station, Units 1 and 2 consist of Babcock & Wilcox Universal Pressure (UP) boilers as seen in the attached side views. Practically of identical design, these cyclone-fired {explained later} balanced draft {forced and induced drafts} UP boilers are comprised of a water-cooled slag tap furnace {explained later} superheater, reheater, economizer and air heater. The units are designed to utilize crushed coal as the primary fuel with fuel oil as an ignition medium.
{The units actually utilized pulverized coal; after the coal was crushed, it went through a milling process before being loaded into the boilers}
"
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