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#BoilerManual #OptimizingCombustion #Section9 #Page13

nature of ash depositing on boiler surfaces. Deposits are frequently divided into three broad types:

1. Fused slag deposits forming on furnace walls and other surfaces exposed to predominantly radiant heat.

2. High-temperature bonded deposits occurring on convection heating surfaces. especially superheaters and reheaters.

3. Low-temperature deposits occuring on air heaters and economizers.

EFFECT OF OPERATING VARIABLES

Although the predominant factors affecting ash deposition are the amount and composition of the ash, boiler operating conditions have also been demonstrated to affect deposition. Some of the factors that have been studied are excess air, firing method, and deposit-time temperature, which is a function of the gas-tube temperature relationship as well as ash properties.

The effect of excess air variation on viscosity is indicated in Figure 3. It was noted earlier that plastic slag is most difficult to remove from furnace walls, and this figure shows that variations in atmosphere from reducing to oxidizing have a major effect on the nature of the ash. In practical terms this means that care must be exercised in maintaining proper fuel/air ratios at all times. If imbalances are allowed to occur, the slagging may be aggravated. Flame impingement on furnace walls, or operating several cyclones with less than theoretical air required for combustion and others at high excess air levels are typical ways in which this can occur. Increased slagging can also raise temperatures entering the convection pass, which leads to higher gas and deposit temperatures, thereby increasing deposit strength, see Figure 4. Thus,

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#BoilerManual #OptimizingCombustion #Section9 #Page13

nature of ash depositing on boiler surfaces. Deposits are frequently divided into three broad types:

1. Fused slag deposits forming on furnace walls and other surfaces exposed to predominantly radiant heat.

2. High-temperature bonded deposits occurring on convection heating surfaces. especially superheaters and reheaters.

3. Low-temperature deposits occuring on air heaters and economizers.

EFFECT OF OPERATING VARIABLES

Although the predominant factors affecting ash deposition are the amount and composition of the ash, boiler operating conditions have also been demonstrated to affect deposition. Some of the factors that have been studied are excess air, firing method, and deposit-time temperature, which is a function of the gas-tube temperature relationship as well as ash properties.

The effect of excess air variation on viscosity is indicated in Figure 3. It was noted earlier that plastic slag is most difficult to remove from furnace walls, and this figure shows that variations in atmosphere from reducing to oxidizing have a major effect on the nature of the ash. In practical terms this means that care must be exercised in maintaining proper fuel/air ratios at all times. If imbalances are allowed to occur, the slagging may be aggravated. Flame impingement on furnace walls, or operating several cyclones with less than theoretical air required for combustion and others at high excess air levels are typical ways in which this can occur. Increased slagging can also raise temperatures entering the convection pass, which leads to higher gas and deposit temperatures, thereby increasing deposit strength, see Figure 4. Thus,

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#BoilerManual #Ramping #Section8 #Page13

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Alt = Labeled Fig. 6 The ramping process. The image incorporates 3 different charts, one above the other, marked in top down order, 6A, 6B and 6C. The x axis on all 3 is labeled Time, but none of them is marked out in terms of the clock; they're marked out in terms of sequence of events marked at points A, B, C, D and E. A, B and C are situated to the left of the midsection, and D & E are marked to the right of the midsection.

The y axis on all 3 are in terms of percent, but the middle chart, 6B, is marked Percent and pressure. The lines on the 6A chart, in top down order, are Boiler master, 201 (left end is marked Closed and the right end is marked 100% open) and 200 - pulsed open (a short diagonal line between a bit before point D on the x axis where it's marked Closed, and the other end intersecting with the 201 line where it's 100% open). The line depicting the 201 is the same on all 3 graphs. So is the 201 line. The Boiler master line has 4% marked on its left end, then steps up to 6.5%, then slants upward where, at point E, it's marked as 33%.

Chart 6B has 2 lines above the lines for the 201 and the 200--in top down order, marked Throttle pressure and Megawatts; the Megawatts line looks identical to the Boiler master line in Chart 6A but doesn't have the 4% place marked as such. The Throttle pressure line is marked 500 psi along its left end, increases a little after point C, then shows that it more-or-less achieves Normal operating pressure just before point D.

Chart 6C is all valves, with the standard lines for the 201 and 200 put in. 202 and 207 were added and it simply illustrates what the main text describes.

#BoilerManual #Ramping #Section8 #Page13

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Alt = Labeled Fig. 6 The ramping process. The image incorporates 3 different charts, one above the other, marked in top down order, 6A, 6B and 6C. The x axis on all 3 is labeled Time, but none of them is marked out in terms of the clock; they're marked out in terms of sequence of events marked at points A, B, C, D and E. A, B and C are situated to the left of the midsection, and D & E are marked to the right of the midsection.

The y axis on all 3 are in terms of percent, but the middle chart, 6B, is marked Percent and pressure. The lines on the 6A chart, in top down order, are Boiler master, 201 (left end is marked Closed and the right end is marked 100% open) and 200 - pulsed open (a short diagonal line between a bit before point D on the x axis where it's marked Closed, and the other end intersecting with the 201 line where it's 100% open). The line depicting the 201 is the same on all 3 graphs. So is the 201 line. The Boiler master line has 4% marked on its left end, then steps up to 6.5%, then slants upward where, at point E, it's marked as 33%.

Chart 6B has 2 lines above the lines for the 201 and the 200--in top down order, marked Throttle pressure and Megawatts; the Megawatts line looks identical to the Boiler master line in Chart 6A but doesn't have the 4% place marked as such. The Throttle pressure line is marked 500 psi along its left end, increases a little after point C, then shows that it more-or-less achieves Normal operating pressure just before point D.

Chart 6C is all valves, with the standard lines for the 201 and 200 put in. 202 and 207 were added and it simply illustrates what the main text describes.

#BoilerManual #BypassSystem #Section7 #Page13

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Alt = Labeled Fig. 4B Startup -- Deaerator pressurization. This image is also sideways with the bottom long the right edge and the top along the left edge, and nearly identical to the previous simplified figures but with a focus on the different valving configuration covered in detail in the main text.

#BoilerManual #BypassSystem #Section7 #Page13

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Alt = Labeled Fig. 4B Startup -- Deaerator pressurization. This image is also sideways with the bottom long the right edge and the top along the left edge, and nearly identical to the previous simplified figures but with a focus on the different valving configuration covered in detail in the main text.

#BoilerManual #CycloneOperation #Section6 #Page13

BOILER FIRING AND PURGE PERMISSIVES

The boiler firing permissives are the conditions common to all cyclones that must be

satisfied before firing is permitted in the boiler; they are:

* Boiler NOT in trip mode.
* The windbox to furnace differential is within limits.
* Boiler air flow is equal to or greater than 25%.
* Lighter oil pressure is greater than 150 psi.
* No other cyclone is i the start or stop sequence.

If a boiler trip has occurred, the control system memory will be set to the trip side. The memory may be reset only when purge is complete and boiler trip contact is no longer closed. The boiler purge sequence is as follows:

* Lighter fuel oil shutoff valves closed.
* Lighter fuel oil vent valve open.
* All lighter oil valves closed.

* Feeders off.
* Cyclone valve closed.
* Circulation valve closed.
* 2 out of 3 gas recirculation fans on with shutoff dampers open.
* Gas recirculation control dampers and gas tempering control dampers not closed.
* 1 out of 3 FD fans on.
* 1 out of 3 ID fans on.
* Air flow greater than 25%
* Windbox to furnace differential delta-P greater than 10" H2O.

When all of the above conditions have been satisfied continuously for five minutes, the purge is complete.

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#BoilerManual #CycloneOperation #Section6 #Page13

BOILER FIRING AND PURGE PERMISSIVES

The boiler firing permissives are the conditions common to all cyclones that must be

satisfied before firing is permitted in the boiler; they are:

* Boiler NOT in trip mode.
* The windbox to furnace differential is within limits.
* Boiler air flow is equal to or greater than 25%.
* Lighter oil pressure is greater than 150 psi.
* No other cyclone is i the start or stop sequence.

If a boiler trip has occurred, the control system memory will be set to the trip side. The memory may be reset only when purge is complete and boiler trip contact is no longer closed. The boiler purge sequence is as follows:

* Lighter fuel oil shutoff valves closed.
* Lighter fuel oil vent valve open.
* All lighter oil valves closed.

* Feeders off.
* Cyclone valve closed.
* Circulation valve closed.
* 2 out of 3 gas recirculation fans on with shutoff dampers open.
* Gas recirculation control dampers and gas tempering control dampers not closed.
* 1 out of 3 FD fans on.
* 1 out of 3 ID fans on.
* Air flow greater than 25%
* Windbox to furnace differential delta-P greater than 10" H2O.

When all of the above conditions have been satisfied continuously for five minutes, the purge is complete.

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#BoilerManual #CycloneDescription #Section5 #Page13

cyclone furnace are shown by the rosin rammler plot in Figure 7. {Rosin-Rammler Distribution in this case is in reference to the math regarding particle comminution--powder--distribution.}Adhering to the recommended coal sizing will minimize erosion of various components of the cyclone. Wear block erosion in the radial burner can be slowed and coal flow remain uniform if wear block integrity is maintained.

Coal particle size is also an influencing factor in combustion. Large coal particles will be retained in the cyclone for a longer period of time while it is being scrubbed by the secondary air to complete combustion. This retention time, besides delaying complete combustion, delays liquefying of the coal ash into slag. This may lead to slag tapping problems.

Slag condition should be observed periodically through inspection doors to make sure that the slag is flowing from the cyclone and primary furnace tap holes. Slag which does not flow freely can indicate the following conditions: high excess air, low cyclone coal input, coal with a high ash fusion temperature, coarse coal, or low boiler load. Simply stated, the heat being generated in the cyclone and furnace is not always sufficient to cause the coal ash to liquify into slag form.

The satisfactory combustion of coal depends on the formation of a liquid slag layer in the cyclone. Ash is removed from the cyclone and primary furnace in fluid form. The viscosity of the slag must permit a slag flow at temperatures experienced in the cyclone and primary furnace. For fuels with high moisture contents and/or low heating values, it is desirable that the coal ash slag be less viscuous (will flow at a lower temperature).

Adjustments are made to the primary and tertiary air dampers only when wide variations in coal quality occurs. Normally, these dampers are set during the startup period and left in the same position for all loads. Lmiting guides for primary and tertiary air dampers are cyclone tapping, coal carrying over to main furnace and burner wear block temperature.

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#BoilerManual #CycloneDescription #Section5 #Page13

cyclone furnace are shown by the rosin rammler plot in Figure 7. {Rosin-Rammler Distribution in this case is in reference to the math regarding particle comminution--powder--distribution.}Adhering to the recommended coal sizing will minimize erosion of various components of the cyclone. Wear block erosion in the radial burner can be slowed and coal flow remain uniform if wear block integrity is maintained.

Coal particle size is also an influencing factor in combustion. Large coal particles will be retained in the cyclone for a longer period of time while it is being scrubbed by the secondary air to complete combustion. This retention time, besides delaying complete combustion, delays liquefying of the coal ash into slag. This may lead to slag tapping problems.

Slag condition should be observed periodically through inspection doors to make sure that the slag is flowing from the cyclone and primary furnace tap holes. Slag which does not flow freely can indicate the following conditions: high excess air, low cyclone coal input, coal with a high ash fusion temperature, coarse coal, or low boiler load. Simply stated, the heat being generated in the cyclone and furnace is not always sufficient to cause the coal ash to liquify into slag form.

The satisfactory combustion of coal depends on the formation of a liquid slag layer in the cyclone. Ash is removed from the cyclone and primary furnace in fluid form. The viscosity of the slag must permit a slag flow at temperatures experienced in the cyclone and primary furnace. For fuels with high moisture contents and/or low heating values, it is desirable that the coal ash slag be less viscuous (will flow at a lower temperature).

Adjustments are made to the primary and tertiary air dampers only when wide variations in coal quality occurs. Normally, these dampers are set during the startup period and left in the same position for all loads. Lmiting guides for primary and tertiary air dampers are cyclone tapping, coal carrying over to main furnace and burner wear block temperature.

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#BoilerManual #Lighters #Section4 #Page13

Oil Purge

Solenoid 8B is energized (purge indicator light on) and solenoid valves *C and 8D are de-energized. Air from valve 8B shifts valve 7C (purge valve) to the open position. With solenoid valves 8C and 8D open to vent control air from valves 7A (oil on) and 7B (oil fill), both valves shift to the purge position. Oil flow is cut-off.

Purge air is admitted to the oil lines and lighters to purge them of oil. The purge timer must be set to allow sufficient time for this purge. Up to three minutes may be required to complete the purge. This time is factory set at one minute.

Pressure switch 9A close at 70 psi and the contacts on pressure switch 9D close indicating purge air is being admitted to the oil lines. Following the purge period, solenoid valves 8A, 8B and the ignition transformers are de-energized.

Retract

Valve 41 (air cylinder control valve) will shift to the retract position. Air passes from valve 41 to the air cylinders and retracts the lighters. The cylinders rate of travel can be controlled by adjusting the speed control valve on the exhaust side of the air cylinder. The exhaust air vents back through valve 41. Pressure switch 9C opens hen the lighters begin to retract.

When the lighters reach their retracted position, mechanical stops on the lighters open the retracted interlock valve. Pilot air from the interlock valve closes pressure switch 9B to indicate that the lighter is in the retracted position.

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#BoilerManual #Lighters #Section4 #Page13

Oil Purge

Solenoid 8B is energized (purge indicator light on) and solenoid valves *C and 8D are de-energized. Air from valve 8B shifts valve 7C (purge valve) to the open position. With solenoid valves 8C and 8D open to vent control air from valves 7A (oil on) and 7B (oil fill), both valves shift to the purge position. Oil flow is cut-off.

Purge air is admitted to the oil lines and lighters to purge them of oil. The purge timer must be set to allow sufficient time for this purge. Up to three minutes may be required to complete the purge. This time is factory set at one minute.

Pressure switch 9A close at 70 psi and the contacts on pressure switch 9D close indicating purge air is being admitted to the oil lines. Following the purge period, solenoid valves 8A, 8B and the ignition transformers are de-energized.

Retract

Valve 41 (air cylinder control valve) will shift to the retract position. Air passes from valve 41 to the air cylinders and retracts the lighters. The cylinders rate of travel can be controlled by adjusting the speed control valve on the exhaust side of the air cylinder. The exhaust air vents back through valve 41. Pressure switch 9C opens hen the lighters begin to retract.

When the lighters reach their retracted position, mechanical stops on the lighters open the retracted interlock valve. Pilot air from the interlock valve closes pressure switch 9B to indicate that the lighter is in the retracted position.

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#BoilerManual #AirAndGasFlow #Section3 #Page13

device is installed in the air duct and the differential pressure is measured across this device. Along with the differential pressure, the temperature of the air must also be measured so the density of the air can be calculated. From experiments with air flow devices, it is known that air flow is proportional to the square root of the sum of the density of the air times the differential across the device. This relationship can be expressed by the following equation:
{deleted image due to formatting bugs}
To find the exact relationship, the device must be calibrated. Once calibration has been done, the proportionality constant can be found. For general purposes, this constant is usually called K.
{Image deleted due to formatting bugs, please refer to the Alt description below the page number. Thanks}

Once this "K" factor is known, the absolute air flow can be found by measuring the pressure differential and the temperature of the air. This "K" factor is independent of the temperature of the air. Periodically, the air flow device's calibration should be checked for accuracy. {As well as functionality, which was the job of the Control & Instruments Dept., fondly called "Seein' Eye" for obvious reasons. Most of those measurement devices were made by Leeds & Northrup, all analog.}

Differential Pressure

The measurement of fluid flow is necessary to permit intelligent, safe, and efficient operation of steam generating equipment. This includes the measurement of water and steam as well as air and gas flow. While there are many means of measuring flow, the common denominator is that allflow measuring devices produce a pressure drop or differential pressure. Differential pressure is created by restrictions in the cross-sectional area of a fluid flow path. Differential pressures created by restrictions can be converted into a flow rate.

For a dependable determination of air flow, the primary element used

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Alt = Equation 1 depicts Air flow is proportional to the square root of (differential)(density).
Equation 2 depicts Air flow = K is the square root of (differential)(density).

#BoilerManual #AirAndGasFlow #Section3 #Page13

device is installed in the air duct and the differential pressure is measured across this device. Along with the differential pressure, the temperature of the air must also be measured so the density of the air can be calculated. From experiments with air flow devices, it is known that air flow is proportional to the square root of the sum of the density of the air times the differential across the device. This relationship can be expressed by the following equation:
{deleted image due to formatting bugs}
To find the exact relationship, the device must be calibrated. Once calibration has been done, the proportionality constant can be found. For general purposes, this constant is usually called K.
{Image deleted due to formatting bugs, please refer to the Alt description below the page number. Thanks}

Once this "K" factor is known, the absolute air flow can be found by measuring the pressure differential and the temperature of the air. This "K" factor is independent of the temperature of the air. Periodically, the air flow device's calibration should be checked for accuracy. {As well as functionality, which was the job of the Control & Instruments Dept., fondly called "Seein' Eye" for obvious reasons. Most of those measurement devices were made by Leeds & Northrup, all analog.}

Differential Pressure

The measurement of fluid flow is necessary to permit intelligent, safe, and efficient operation of steam generating equipment. This includes the measurement of water and steam as well as air and gas flow. While there are many means of measuring flow, the common denominator is that allflow measuring devices produce a pressure drop or differential pressure. Differential pressure is created by restrictions in the cross-sectional area of a fluid flow path. Differential pressures created by restrictions can be converted into a flow rate.

For a dependable determination of air flow, the primary element used

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Alt = Equation 1 depicts Air flow is proportional to the square root of (differential)(density).
Equation 2 depicts Air flow = K is the square root of (differential)(density).

#BoilerManual #FluidCirculation #Section2 #Page13

A starting permissive of the boiler feed pump requires that the valve stem be in the closed position before the pump can be started. It stays in the closed position until the feed pump trips. If a false feed pump trip signal should occur, the stem will attempt to move to the open position, but the pressure differential keeps the valve closed. The valve is always mounted in the vertical position so that the weight of the valve plug opens the valve.

The economizer outlet header feeds two cyclone supply downcomers (one on each side of the unit) which travel a substantial length of the unit and terminate in downcomer bottles. Each downcomer supplies seven separate cyclones.

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Alt = Figure 12 labeled Natural circulation valve; image of a mechanical drawing of the valve. Labeled are the Power driven stem at the bottom; Plug in normal operating position with higher pressure on the economizer side, which is labeled on the right side of the drawing. At the top is labeled the Natural circulation flow direction with a down-pointing arrow.

#BoilerManual #FluidCirculation #Section2 #Page13

A starting permissive of the boiler feed pump requires that the valve stem be in the closed position before the pump can be started. It stays in the closed position until the feed pump trips. If a false feed pump trip signal should occur, the stem will attempt to move to the open position, but the pressure differential keeps the valve closed. The valve is always mounted in the vertical position so that the weight of the valve plug opens the valve.

The economizer outlet header feeds two cyclone supply downcomers (one on each side of the unit) which travel a substantial length of the unit and terminate in downcomer bottles. Each downcomer supplies seven separate cyclones.

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Alt = Figure 12 labeled Natural circulation valve; image of a mechanical drawing of the valve. Labeled are the Power driven stem at the bottom; Plug in normal operating position with higher pressure on the economizer side, which is labeled on the right side of the drawing. At the top is labeled the Natural circulation flow direction with a down-pointing arrow.

@Su_G #BoilerManual #UnitDescription #Section1 #Page13

{image of the sectional side view of Unit One looking south, in detail, but doesn't actually have a page number. Image is too large and print too small to be accommodated on this instance. I'll try posting it in piecemeal fashion later.}

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@Su_G #BoilerManual #UnitDescription #Section1 #Page13

{image of the sectional side view of Unit One looking south, in detail, but doesn't actually have a page number. Image is too large and print too small to be accommodated on this instance. I'll try posting it in piecemeal fashion later.}

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