Wcf furnace ignition

TVA WCF Furnace Ignition

Operations Continuing Training Tennessee Valley Authority TVA

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WCF Furnace Ignition

Table of Contents

TABLE OF CONTENTS ................................................................................................................

STUDENT OBJECTIVES ............................................................................................................4

Introduction .....................................................................................................................................................................................................5 Burner Management System Functions ...........................................................................................................................................6 Lamp Test……………………………................................................................................................................................................................7 Boiler Relays……………................................................................................................................................................................................9 Unit 7 Relays...........................................................................................................................................................................10 Unit 8 Relays.................................................... ....................................................................................................................................... 11 Purge Permit ….. .......................................................................................................................................................................................12 Lighting Off Oil System ............................................................................................................................................................................13 Backup Regulator. ....................................................................................................................................................................................14 Prerequisites……........................................................................................................................................................................................15 Igniter Trip Valve……..............................................................................................................................................................................16 Warm-up Trip Valve…. .......................................................................................................................................................17 Ignition Process……………....................................................................................................................................................18 Pair Operation….........................................................................................................................................................................................19 Oil Gun Operation.....................................................................................................................................................................................20 Oil Gun Stop/Purge Sequence............................................................................................................................................................21 Oil Gun Trips/First Out Alarms…………..........................................................................................................................................22 Pulverizer Ignition………………………..................................................................................................................................................23 Pulverizer Feeder Operation…………………....................................................................................................................................24 Hot Restart…………………………...............................................................................................................................................................25 Stable Fire………...…………….....................................................................................................................................................................26 Burner Nozzle Temperatures……………………………………………………………………………………………………………..27 Emergency Trip Buttons Unit 7…………………………………………………………………………………………………………..28 Emergency Trip Buttons Unit 8…………………………………………………………………………………………………………..29

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WCF Furnace Ignition

Christmas Tree

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WCF Furnace Ignition

Student Objectives

To explain the purpose and operation of the boiler purge interlocks……………………..

To explain the purpose and operation of the pulverizer/feeder start interlocks……………….

To explain the importance of the burner nozzle temperature monitoring………………………

To explain the operation of the furnace control system…………………………………….

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WCF Furnace Ignition

Introduction

The Burner Management System is designed to ensure the execution of a safe, orderly operating sequence in the start-up and shutdown of fuel firing equipment and to prevent errors of omission or commission in following such a safe operating procedure.

The system provides protection should there be a malfunction of fuel firing equipment and associated air systems. The safety features of the system are designed for protection in most common emergency situations; however, the system cannot supplant the intelligent and reasonable judgment of the operator in all situations.

In some phases of operation, the Burner Management System provides permissive interlocks only to insure safe start-up sequences of equipment.

Once the equipment is in service, the operator must use normally acceptable safe operating practices.

It is important that the operator is familiar with the overall operation of the unit and the operation of individual equipment.

Gauge Observations

1 = Inlet Pressure 2 = Tower Vacuum Gauge 3 = Outlet Pressure Gauge 4 = Oil Temperature Gauge 5 = Differential Pressure Gauge (Polishing filter) 6 = Vacuum Pump Backpressure Gauge

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WCF Furnace Ignition

Burner Management Functions A. Supervise the purge sequence to ensure that the proper conditions are maintained throughout the purge cycle.

B. Prevent any fuel firing unless a satisfactory furnace purge sequence has first been completed.

C. Prevent start-up of individual fuel firing equipment unless certain permissive interlocks have first been satisfied.

D. Monitor and control the proper component sequence during start-up and shutdown of fuel equipment.

E. Make continued operation of fuel firing equipment subject to certain safety interlocks remaining satisfied.

F. Provide component status feedback to the operator.

G. Provide flame supervision when fuel firing equipment is in service and affect a fuel trip upon certain adverse operating conditions.

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WCF Furnace Ignition

Lamp Test The Burner Management System has a lamp test to ensure that all indicators can be illuminated.

The Furnace A and B console insert panel has a Lamp Test push button. The indicators should be tested before the unit is placed in service or they can be tested at anytime to ensure that the indicators can be illuminated. Depressing the Lamp Test push button will illuminate all indicators on the associated console insert panel. If any indicator is not illuminated, the defective indicator lamp or lamps is replaced, the Lamp Test push button should be depressed to ensure that all indicator lamps can be illuminated.

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WCF Furnace Ignition

Boiler Auxiliary Relays When placing the furnace in service to prevent unwanted and dangerous consequences, boiler interlocks have been installed. This is a safety mechanism that has been engineered into the process. This system serves two purposes: 1) to ensure a means is available to remove the products of combustion. 2) To arm a protection process in the case of equipment malfunction or operator error.

The common relays are located in several places: the Unit 4160v Board in the Auxiliary Compartment, On and behind the Unit Control Board, the Relay Board on the Mezzanine Level. We won’t discuss location just function.

We will use the Boiler trip Scheme to show what mechanism is used to trip the fires or unit with this protection scheme.

All Boiler Trips as labeled on the diagram will be referred to as Furnace Trips for the purpose of this lesson and to give more clarity.

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WCF Furnace Ignition

The furnace is always tripped through the 97 relay. This relay is actually a trip circuit that has multiple levels and designations they are as follows for Unit 7: 97 H&L- this portion of the relay function is to trip the pulverizers on its respective 4160v board.

97 P- this portion of the relay function is to send a MFT (Master Fuel Trip) to the Burner Management System.

97 F- this portion of the relay function is to trip the Forced Draft Fans if all the Induced Draft Fans trip.

97A PT- this portion of the relay operates through 97 H&L to trip on loss of fans in the A Furnace.

97B PT-this portion of the relay operates through 97 H&L to trip on loss of fans in the B Furnace.

97 IFA- this portion of the relay operates the A Furnace Induced Draft Fan and Air Pre-Heater Gas Inlet Dampers. It operates off ID Fan Speed.

97IFB-this portion of the relay operates the B Furnace Induced Draft Fan and Air Pre-Heater Gas Inlet Dampers. It operates off ID Fan Speed.

The 97 Relay has a trip cut-out switch on B Bench Board on 7 and also on 8. This is used to enable you to place a fire in the furnace with the turbine valves closed. This does not bypass a MFT.

Print 45W7683-3

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These are the relay designations for Unit 8: 97 IT-this portion of the relay function is to trip the Forced Draft Fans if all the Induced Draft Fans breakers come open.

97 YA & YB- this portion of the relay function is to trip the pulverizers on its respective 4160v board.

97 Y1- this portion of the relay function is to trip the soot blowing system and to activate the first out Ann. and Sequence of events printer.

97 Y2- this portion of the relay function is to send a MFT (Master Fuel Trip) to the Burner Management System.

97 F- this portion of the relay function is to trip the Forced Draft Fans if all the Induced Draft Fans breakers come open.

97A PT- this portion of the relay operates to trip on loss of fans in the A Furnace.

97B PT-this portion of the relay operates to trip on loss of fans in the B Furnace.

We have discussed the protection schemes we need to protect the furnace from equipment malfunction or operator error. The next phase will be Burner Management.

Print 45W8690-1

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Purge Permit Before any fuel firing can take place in either furnace (Initially or following a Master Fuel Trip) a successful furnace purge cycle must be completed for both furnaces.

The Purge Permit signal must be established for the associated furnace before the furnace purge cycle can be started. The Purge Permit signal must remain established for the duration of the furnace purge cycle. The following are the 10 requirements for a Purge Permit: • The airflow is greater than 30% • The airflow is less than 40% and the burner tilts are horizontal. The OIC puts the airflow between 675 and 900 CFM. • All of the auxiliary dampers are modulating. 75% (33 of 44) auxiliary air dampers open greater than purge position. The OIC 75%>25% open) • FD Fan Crossover Damper Closed • The Igniter Valves on all four (4) elevations 1, 2, 3-4, and 5 are closed. This is indicated when all sixteen (16) IGN VLV CLOSED (green) lights are on at the console insert panel.

• All warm-up valves on elevation 3-4 are closed. This is indicated when the four OIL VLV CLOSED (green) lights are on at the console insert.

• On the console insert Furnace B panel, the igniter trip valve is proven closed when the closed light is on.

• The pulverizers on all five (5) coal elevations are off.

• Less than two of the four scanners on all four scanner elevations indicate flame.

• A NO BOILER TRIP signal exists.

When all requirements are satisfied, the Burner Management (blue) Purge Permit light comes on. After this light comes on, the furnace purge cycle can be started and the Burner Management System will continue to monitor the requirements listed. If any of these signals is lost before the furnace purge cycle is completed, the Purge Permit light goes off and the furnace purge cycle is stopped. When the furnace purge cycle has been successfully completed, a Purge Complete signal is received. The following events will now occur: • The seven (7) First Out memories are reset.

• The memory for that furnace is reset removing the Loss of Fuel Trip Signal.

• The memory for that furnace is reset removing the furnace Master Fuel Trip signal and the No Master Fuel Trip signal is established. When the No Master Fuel Trip signal is established, the Igniter trip Valve and the Warm-Up Trip Valve can be opened after satisfied.

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WCF Furnace Ignition

Lighting Off Oil System The purpose of the Lighting Off Oil System is to supply fuel oil for the warm-up guns, igniters, and the auxiliary boiler for building heat. The two above ground storage tanks are located at the upstream landside end of the transformer yard. The tanks are cross connected through piping with isolation valves. Each tank has a capacity of 32,657 gallons (99.64 inches) for a total storage capacity of 65,314 gallons. It usually takes about 8,000 to 16,000 gallons of fuel for the average start-up of either unit.

There are 3 lighting off oil pumps located on M-1 in the oil pump room. Each pump has a capacity of 50 gpm@200 psig discharge pressure. They are positive displacement pumps with a relief valve that recirculates back to the suction side of the pumps.

Usually only one pump is used on a start-up, but 2 pumps can be used and controlled from Panel B in the control room, A&B from U7 and B&C from U8.

There is a strainer on the discharge side of the pumps to prevent particulates from plugging the igniters and warm-up oil guns. Also the pumps should be started at least 2 to 3 hours before the start up if possible to warm the oil for better ignition.

The fuel oil and atomizing air is admitted to the furnace through a piping and valve arrangement referred to as the Christmas tree. This arrangement holds the atomizing air regulators. The Igniter Trip Valve and regulating valve is located here, as well as the Warm-Up Oil Trip valve and regulator. Before these valves are opened in the start-up process there is a back-up regulator that allows the oil to return back to the suction and prevent the dead heading of the pumps. This also allows any oil that’s over and above what’s required during the firing process to return to the suction.

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WCF Furnace Ignition

Back-up Regulator In cases where the oil pressure cannot be properly maintained on the unit during startup, one of the primary causes can be the back pressure regulator. This valve can be isolated to it home unit. In other words U7 backpressure regulator can be isolated if not functioning properly and U8’s regulator lined up to U7 to stabilize the pressure. This is a tremendous help in reducing delays in the start up process.

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WCF Furnace Ignition

Prerequisites There are many prerequisites to be observed during a unit start-up. Since we are focusing on furnace ignition the two of importance to us are the resetting of the BCX-2 Relay and engaging the 97 Relay Trip Cut-Out. If the boiler was drained the BCX-2 relay was energized to close a contact in the trip circuits of the pulverizers to prevent fuel from being admitted to the furnace with no water present.

With at least two BCWP’s in service and more than 6 pounds differential pressure across the pumps this relay may be reset. This also allows the establishment of an oil fire; this is a common omission when there is no response to the start input. The Trip Cut-out for the 97 Relay is there to allow you to establish a fire with the turbine steam valves closed. If there is no path for steam flow there is a contact closed in the trip circuit of the pulverizers for furnace over pressurization protection. By pulling up on the handle this takes this portion of the relay out of service.

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WCF Furnace Ignition

Igniter Trip Valve Operation There are two trip valves (igniter and main) that serve the unit. After the “no master fuel trip” signal is established for both furnaces, the trip valves can be placed in service after other conditions are satisfied.

Igniter Trip Valve: The oil igniter trip valve can be opened after all of the following conditions are satisfied: 1. No Master Fuel Trip.

2. All igniter valves are closed.

3. Lighting Off Oil Pump start commanded.

4. Lighting off oil pressure satisfactory.

5. Igniter Trip Valve Tag-Out indication removed.

Depressing the Igniter Trip Valve Open pushbutton will energize the trip to open causing the following to occur: The trip valve is moved from the closed position and the red open pushbutton is illuminated.

The trip valve is proven fully open when the associated green Closed Light goes off.

If the igniter oil header pressure is low, a light-off air/oil fail signal is established. This is an alarm output signal The igniter elevation trip signal is now removed The igniter elevation start permit signal is now established for coal igniter elevations 1, 2 and 5.

The igniter trip valve open signal is now established. This signal starts the number 1 scanner fan in each furnace if the associated back-up scanner fan is not running.

The igniter trip valve is automatically closed if any of the following conditions exist: The igniter loss of power trip signal is established.

When any igniter valve is not closed in both furnaces and the igniter trip valve remains not closed and the igniter oil header pressure is low for more than two seconds, the igniter trip valve will be automatically closed.

This will be shown in area 7.

A Master Fuel Trip exists • Loss of 24 VDC relay power • Igniter oil pressure low for greater than 4 seconds when any igniter valve is open.

• Igniter trip valve fails to open within 5 seconds of open command.

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WCF Furnace Ignition

Warm-Up Trip Valve Operation After the furnace purge is complete the warm-up trip valve can be opened providing the following permissives are satisfied: 1. Lighting off oil pump start commanded.

2. All warm-up oil valves closed.

3. No Master Fuel Trip.

4. Lighting off oil pressure satisfactory.

5. Atomizing air pressure adequate.

Atomizing Air Regulator

6. Warm-up Trip Valve Tag-out indication removed.

Depressing the MAIN OIL TRIP VALVE '“OPEN” push button will energize the trip valve to ”open”, causing the following events to occur: A. When the trip valve is moved from the closed' position, the MAIN OIL TRIP VALVE (red) “OPEN” push button is illuminated.

B. The trip valve is proven "fully open" when the associated (green) closed light goes off.

The following conditions will override the open command and automatically close the warm-up trip valve.

Warm-Up Trip Valve

1. The Close push button from the BMS insert panel is depressed or from the OIC. 2. A warm-up oil Trip valve closed condition exist (described below).

The warm-up trip valve is automatically closed (tripped) if any of the following conditions exist: 1. Warm-up trip valve fails to open within 5 seconds of OPEN command.

2. Any Warm-up valves fail to close 3. Master Fuel Trip .

4. Air/Oil Differential out of limits for greater than 10 seconds while the warm-up trip valve is open.

5. Atomizing air pressure out of limits for greater than 10 seconds with any warm-up oil gun proven.

6. Atomizing air or oil pressure signals in bad quality while the warmup trip valve is open.

Warm-Up Regulator

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WCF Furnace Ignition

Ignition Process The warm-up oil elevation can be placed in service in the following manners, "pair" basis, and “elevation" basis or on a “corner” basis (local only for corner basis) provided the respective oil gun start permit(s) are established for the respective furnace(s). The individual oil gun permissive must also be satisfied before the respective oil gun can be started.

When all pulverizers are off, the warm-up oil elevation can only be placed in service on a “pair” basis. This is indicated when the WARM-UP OIL FIRING MODE (amber) “pair” light is on at the corresponding console insert panels.

When any pulverizer is ON the warm-up oil elevation can only be placed in service on an “elevation” basis. This is indicated when the WARM-UP OIL FIRING MODE (white) “ELEV” light is on at the corresponding console insert panels.

The following conditions must be established to satisfy the oil gun start permit: 1. Atomizing air and lighting-off oil pressure adequate.

2. 120 VAC control power available.

3. Warm-up trip valve OPEN. 4. No oil gun trip conditions exist.

5. Furnace firing permit established Oil Gun Common Trip A oil gun common trip is initiated when any of the following conditions are present: 1. Master Fuel Trip.

2. Furnace purge required, initiated upon furnace loss of fuel or furnace air flow drops below 25%.

3. Warm-up oil trip valve not open.

4. Complete flame scanner failure on elevation 3-4.

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WCF Furnace Ignition

Pair Operation Considering the fact this lesson is specifically concerned with the initial firing of the furnace, we will only cover Pair and Corner Operation at this time.

The oil guns can be started or stopped from either the Burner Management System screen (BMS) insert panel or the OIC (Operator Interface Console). With the permissives met the Start A/C command can be selected, initiating the sequencing for PAIR operation. This results in a command to start corner A first, which is indicated by the (red) Start A/C push button being illuminated and the associated (green) Stop A/C light being off. After a short time delay with the permissives met corner C is started.

A oil gun is proven when the respective flame scanner proves flame when the oil valve is open, the oil gun extended, and oil gun start is memorized. Indication of the oil gun proven is displayed on the OIC. In addition the flame proven signal for the oil gun is indicated by the BMS insert panels FLAME PROVEN (red) light being on for the respective oil gun.

The oil gun pair mode start sequence is reset by any of the following: 1. An oil gun pair cycle timer elapsed. (46 second start cycle timer expired).

2. A loss of the oil gun start permit.

3. An oil gun common trip.

4. The operator selection of the STOP A/C command.

If an oil gun trips while in pair mode the start sequence will hold and the oil gun start permissive is lost for a (1) minute waiting period during which the furnace air flow of 30% to 40% must be maintained to be credited with the one minute hold. The oil guns that were established will remain in service. When the gun start permit is reestablished you may initiate another start sequence.

Any oil gun trip will be indicated by the annunciator window “Warm-up Pair start/stop fail� along with the individual oil gun controls on the OIC. Whether in Pair or Elevation mode when a oil gun start is memorized a signal is sent to the respective furnaces secondary air control to maintain the elevation 3-4 auxiliary air dampers to at least 20% open.

When 3 out of 4 warm-up oil guns are proven, a signal is established this serves as part of the pulverizer ignition permissives for pulverizers 2, 3, and 4.

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WCF Furnace Ignition

Oil Gun operation Each oil gun is checked for the following oil gun ready permissives: 1. An oil gun start permit.

2. The oil gun atomizing air pressure is adequate.

3. The manual oil valve is open.

4. The oil valve is closed or in the scavenge position.

5. The oil tag out indication is removed.

6. The oil gun local stop is not selected.

When a start command is given an oil gun start is memorized. This results in an oil gun advance command, the HESI (High Energy Spark Igniter) probe is commanded to insert and spark for ten (10) seconds. The oil gun start memorization also arms the oil gun flame trip logic. Once the HESI probe is inserted, the oil valve is commanded to the open position.

The oil gun is proven when the following conditions exist: 1. The oil gun start is memorized.

2. The oil gun is advanced.

3. The oil valve is open.

4. The oil gun flame is proven.

If the oil gun fails to extend within five (5) seconds a oil gun trip will result.

If the HESI fails to extend within the five second allotment the oil gun will trip.

The oil gun will retract when a stop command is given, the oil valve is closed, and the oil gun purge is complete. Failure of the oil gun to retract within five (5) seconds will result in an oil gun stop fail condition, which will be indicated on the individual oil guns control via the OIC. This does not result in an oil gun trip; however you should investigate the cause. The oil gun HESI probe is advanced/energized for forty five (45) seconds when the oil gun stop is depressed, the oil valve is open, and no purge blocked with the oil gun extended for scavenging the oil during a stop sequence.

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WCF Furnace Ignition

Oil Gun Stop/Purge Sequence An oil gun stop command is initiated by the following: 1. An operator stop command on the OIC or insert.

2. An oil gun stop sequence.

3. An oil gun trip.

Once initiated the oil valve will go to the scavenge position. If the following conditions are met the HESI probe will insert and spark for forty five seconds for an oil purge: 1. The oil valve is open.

2. There is no oil gun purge blocked in.

3. The oil gun stop is memorized.

4. The HESI probe is extended.

After the oil gun purge is complete, the oil valve is commanded closed, the HESI probe is retracted, and the oil gun is retracted.

An oil gun purge block: The purge block prevents fuel from being admitted into the furnace under unsafe conditions. The following conditions will initiate an oil gun purge block: 1. The oil gun atomizing air pressure is inadequate.

2. The oil gun is not extended.

3. The 120vac control power is not available.

4. An oil gun trip.

5. A Master Fuel Trip.

6. A furnace purge is required.

If an oil gun purge block is initiated, the condition causing the block must clear and a operator initiated oil gun stop commanded to release the oil gun purge block.

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WCF Furnace Ignition

Oil Gun Trips/First Out Alarms An oil gun first out trip indication is provided on the OIC. The oil gun will trip if any of the following conditions are present: 1. The oil gun HESI probe failed to extend after five seconds.

2. The oil gun failed to extend after five seconds.

3. The oil gun manual oil valve not open and a start memorized.

4. An oil gun atomizing air pressure is inadequate and a start memorized.

5. The oil gun flame not proven ten seconds after the oil valve is open and a start memorized.

6. The oil valve failed to open after five seconds.

7. The oil valve failed to close after five seconds.

8. The oil valve failed to purge after five seconds.

9. An oil gun common trip.

Oil gun trips 1 through 8 are captured into the first out trip logic for the respective oil gun. An oil gun trip can be reset from the OIC with the acknowledge/reset command.

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WCF Furnace Ignition

Pulverizer 3&4 Ignition Prior to starting any pulverizer, the pulverizer’ s ignition energy must be adequate to light off coal.

The ignition energy is adequate when the “Pulverizer Ignition Permit” signal is established. This signal is proven established when the (White) “PULV IGN PERMIT” light is on steady or blinking for the pulverizer on the associated coal elevation.

For pulverizers A3 and B3 the requirements are: • At least three (3) of the four (4) warm-up oil guns on elevation 3-4 are proven. That is the rule, but effort should be given to achieve four (4) guns since the loss of one of the guns at this point would have you lose the purge permit and force you to purge the furnace again.

• This step is only supported if the unit is already on line or in the very later stages of a start-up. If there is adequate ignition energy on coal elevation 2 or 4. Adequate ignition energy must initially be established by the feeder on elevation 2 or 4 being proven. The feeder would have to be at greater than 50% speed and have been in service for more than 50 seconds. Once pulverizer 3 is ON, the adequate ignition energy signal will remain established by the feeder on elevation 2 or 4 being proven or by pulverizers 2 or 4 amps indicating that the pulverizers are sufficiently charged to support ignition energy for pulverizers.

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WCF Furnace Ignition

Pulverizer/Feeder Operation After the associated coal elevation’s “pulverizer ignition permit” signal is established, the associated pulverizer can be started. This is shown on the control panel inserts by the “PULV IGN PERMIT” light being on steady. When the pulverizer is on the following will occur: • The “PULV IGN PERMIT” light will start “blinking” because the pulverizer ignition permit required signal exists. This is to signal the Operator that support flame is required or the pulverizer will trip. The signal exists when the feeder is not on for sufficient time to maintain a steady coal fire without support flame. When the feeder is proven which we will explain later for more than 180 seconds or 3 minutes, the signal is no longer required and support flame can be removed.

• • • • • •

The “start feeder” permit signal is established. When the feeder is placed in service the following events occur: A fifty (50) second counting period is started If the feeder remains on for the fifty (50) seconds, a feeder proven memory signal is established.

The unit flame failure signal is now armed.

The burner tilts horizontal and the furnace air flow between 30-40% is no longer required.

The 180 second (3 minutes) counting period is started. When this counting period expires the following will happen.

The pulverizer ignition permit required signal is removed.

The associated PULV IGN PERMIT light that was blinking returns to a steady on as long as the corresponding start up pulverizer permit signal is established.

If the associated coal elevation’s pulverizer ignition permit signal is now removed, the pulverizer and associated feeder will remain in service because a stabilized flame is now established, but the PUL IGN PERMIT light will go off.

After the feeder is proven and the associated feeder’s speed is greater than 50%, a feeder proven greater than 50% signal is established which may be part of an ignition permit for an adjacent pulverizer.

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WCF Furnace Ignition

Hot Restart Our Burner Management System has a feature that will enable you to recover the fire and minimize thermal stresses on both the boiler tubes and the turbine metal in the event of a loss of flame. The system has a function referred to as Hot Restart. There are conditions that have to be met simultaneously to achieve a Hot Restart Permit they are as follows: •

The Air Preheaters A and B out let air temperature is greater than 350oF.

•

The boiler drum pressure is greater than 500 psi.

•

The furnace steam flow is greater than 30% in both A and B furnaces.

What this allows you to do is after the purging process, you still have to purge for 300 seconds to ensure a safe ignition environment. Upon purge complete and the establishment of an oil fire you will get the pulverizer permits for the 2, 3, and 4 coal elevations. This will enable you to place the #2 elevation pulverizer in service to allow you to counteract the significant loss in temperature due to the cooling effect of the steam flow.

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WCF Furnace Ignition

Stable Fire Understanding the Burner Management System is designed to ensure the execution of a safe, orderly operating sequence of the fuel firing equipment. It will monitor and control the proper component sequence during start-up and shutdown of this equipment. Therefore there are certain conditions that must be met before the system will allow you to transition from one phase to the next. One of the most important requirements to remember is adequate ignition energy for the pulverizer to sustain a flame. We’ve covered what the prerequisites for placing a pulverizer in service are, but we still need to discuss the removal of the oil fire. The Burner Management System not only monitors and allows the creation of energy it also measures the use of that energy.

If we don’t have sufficient steam flow to indicate the requirement of more heat energy then the possibility of having to drop our ignition energy below the point of adequacy in other words drop our feeder loading to below 50% due to a reduction in load, then the BMS will cause a flame failure condition. Therefore steam flow is our reference point for the removal of the oil fire. On start up the 3 and 4 elevation pulverizers provide enough energy to achieve 30% steam flow. If we follow all the requirements and have these mills in service and at least 50% feeder speed on the #3 elevation we will get the PULV IGN PERMIT for the #2 elevation. Once this elevation is in service and stable other unit conditions permit the oil fire can be removed. Keeping in mind that the system cannot supplant the intelligent and reasonable judgment of the operator in all situations.

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WCF Furnace Ignition

Burner Nozzle Temperature An important aspect of placing pulverizers in service is having a clear path for coal flow to the furnace. If there is pluggage in the transport pipe a very undesirable and dangerous condition will result. In order to monitor the transport pipes we have a Burner Nozzle Temperature indication in the OIC. This allows us to check the flow of coal to each corner relative to the other three. This gives information on the performance of the pulverizer. If the coal flow is too low it can allow the coal to begin to coke over the coal nozzle blocking flow, this can get to the point of completely plugging the nozzle. This will allow the coal to settle in the transport pipe and ignite allowing the fire to travel back to the pulverizer and cause an explosion. Therefore there is an alarm to alert the operator to the issue. If any of burner nozzle on a given elevation becomes 50 degrees different from the other three a burner high temperature alarm will come in. If the temperature is climbing at a steady state that pulverizer should be taken out of service per procedure and the pipe cap for that pipe removed and the nozzle inspected for pluggage. The burner nozzle temperature will also come in alarm at 575 degrees although they are within the 50 degree limit as this would indicate insufficient flow through the nozzle.

Upon the starting of any pulverizer there is a 10 minute wait before placing the feeder in service this serves two functions. One is to allow the pulverizer to come to operating temperature and grindability. Second is to allow the burner nozzle temperatures to come below 525 degrees to help prevent coking of the nozzles. Another remedy for this is upon removing a pulverizer from service we remove the pipe caps to allow ambient to allow ambient air to flow over the nozzles therefore keeping them cool.

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Emergency Trip Buttons Unit 7 At the beginning of this lesson we identified the relays and interlocks used to ensure the furnace environment was conducive to a safe combustion process. There are times when conditions are such that we no longer have control of this environment. In the event the operator has this happen, there are emergency trip buttons for the immediate tripping of the issue. This gives the operator the ability to regain control and return to normal operations.

BFP emergency Trip Pushbutton on Panel C 98 relay 98X-H Trips A booster Pump and A BFP Turbine 98X-L Trips B booster Pump and B BFP Turbine Gives an annunciation at the ECB, the Control Room, and Sequence of events recorder.

Must be reset with the BFP Emergency Trip Reset Pushbutton

Boiler Auxiliary Emergency Trip Pushbutton on Panel C 98 Relay 2 98Y-H Relays Trip A1, A3, A5, B2 and B4 Pulverizers 2 98Y-L Relays Trip A2, A4, B1, B3, and B5 Pulverizers Sends a Master Fuel Trip to the Burner Management System and the Scrubber Gives an annunciation at the ECB, the Control Room, and Sequence of events recorder.

Unit emergency Trip Pushbutton on Control Room Wall 98 Relay Trips BFP through BFP Emergency trip Circuit Trips the Pulverizers through the Boiler Auxiliary Emergency Trip Circuit Trips Turbine through 65S Trips the Forced Draft and Induced Draft Fans through 98FH & 98FL BFP & Boiler Auxiliary Emergency Trips must be reset by their Reset Pushbuttons.

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Emergency Trips Unit 8 BFP emergency Trip Pushbutton on Panel C 98 relay 98X- Trips A&B Boiler Feed Pump Turbines Trips all three Boiler Feed Pump Booster Pumps Annunciates in the ECB Manual Emergency Shutdown

Boiler Auxiliary Emergency Trip Pushbutton on Panel C 98 Relay 98 YA- Trips all pulverizers in A Furnace 98YB- Trips all pulverizers in B Furnace 98YI- Boiler Miscellaneous Emergency Trip Soot Blower Trip Common Soot Blower Trip A Furnace Soot Blower Trip B Furnace

Unit emergency Trip Pushbutton on Control Room Wall 98 Relay 65S1 & 65S2- Trips Turbine Trips BFP’s & Booster Pumps through BFP Emergency Circuit 98 ID- Trips ID Fans A-D 98 F - Trips FD Fans A-D; Trips Boiler Trip Relays 97YA, 97YB, 97YI 98YI- Boiler Miscellaneous Trip 98YA- “A” Furnace Pulverizers 98YB- B Furnace Pulverizers Also Energizes 97F