Yanbu Boiler Training - Controls Student Training Manual PDF

SALINE WATER CONVERSION CORP STUDENT INFORMATION/TRAINING YANBU POWER STATION, UNIT No.’s 10 - 50 MANUAL BOILER CONTROLS NAME __________________________ : ...

SALINE WATER CONVERSION CORP STUDENT INFORMATION/TRAINING YANBU POWER STATION, UNIT No.’s 10 - 50 MANUAL BOILER CONTROLS NAME __________________________ : Yanbu Power Station, Unit No.’s 10 – 50 ©COPYRIGHT GE Vernova May, 2024 2  Yanbu Power Station, Unit No.’s 10 – 50 Contents Master Fuel Trip......................................................................... 16 Superheat Steam Temperature Control (General)....................... 38 Disclaimer.................................................................................... iii First Out Cause of Trip System.................................................. 19 Platen Superheat Temperature Control....................................... 38 Objectives.................................................................................... iii Scanner/Ignitor Air Fan Control.................................................. 19 Final Superheat Temperature Control......................................... 38 Acronyms..................................................................................... iii Combustion Air Control.............................................................. 19 Reheat Steam Temperature Control (General)............................ 39 Burner Management System Control............................................... 4 Auxiliary Air Dampers................................................................. 20 Reheat Temperature (Spray) Control.......................................... 39 Introduction...................................................................................... 4 Fuel Air Dampers....................................................................... 20 Reheat Temperature (Tilt) Control............................................... 39 Burner Management System Logic.................................................. 5 General...................................................................................... 23 Reheat Temperature (Gas Recirculation Fan) Control................ 40 Unit Start-Up................................................................................. 5 Unit Master Control Interface...................................................... 23 Flash Tank Drain Tank Pump Recirculation Control.................... 41 Furnace Purge.............................................................................. 5 Runback..................................................................................... 23 Flash Tank Drain Tank Pump Recirculation Control.................... 41 Oil Header Trip Valve Operation................................................... 6 Block ULD increase.................................................................... 24 Flash Tank Drain Tank Drain Water Temperature Control.......... 41 Oil Leak Test................................................................................ 6 Block ULD decrease................................................................... 24 SCAPH Drain Tank Level Control............................................... 41 Ignitor Gas Header Trip Valve Operation...................................... 7 ULD Rundown............................................................................ 24 Air Heater Cold End Temperature Control................................... 42 Ignitor Gas Leak Test................................................................... 8 ULD Runup................................................................................ 24 Air Heater Bypass Cold End Temperature Control...................... 42 Main Gas Header Trip Valve Operation........................................ 9 Combustion Control.................................................................... 25 Furnace Sootblower Steam Pressure Control............................. 42 Main Gas Leak Test................................................................... 10 Fuel/Air Demand........................................................................ 25 Scanner Cooling Air/Ignitor Air to Furnace Diff. Pressure Control 43 Oil Elevation Start-Up................................................................. 11 Ignitor Gas Header Pressure Control......................................... 28 General – Open Loop Control.....................................................45 Firing Mode / Manual Operation................................................. 11 Main Gas Control....................................................................... 28 ID Fan Interlock and Drive Logic.................................................45 Oil Automatic Startup Operation................................................. 12 Heavy Oil Control....................................................................... 28 FD Fan Motor Control and Interlock Logic................................... 45 Oil Corner Start Sequence.......................................................... 12 Light Oil Control......................................................................... 28 GR Fan Motor Control and Interlock Logic.................................. 46 Main and Ignitor Gas Elevation Start-Up..................................... 12 Atomizing Steam Header Pressure Control................................ 29 GR Fan Lube Oil System............................................................46 Gas Manual Operation............................................................... 13 Total Unit Air Flow...................................................................... 29 ID Fan Cooling / Seal Air System................................................ 47 Gas Automatic Startup Operation............................................... 13 Air Flow Control.......................................................................... 29 ID Fan Control Oil System...........................................................47 Main Gas Corner Start Sequence............................................... 13 Gas Recirculation Damper Control............................................. 30 ID Fan Lube Oil System..............................................................47 Gas Elevation Shutdown............................................................ 14 Auxiliary Air Damper Control...................................................... 30 FD Fan Control Oil System.........................................................48 Gas Manual Operation............................................................... 14 Fuel Air Damper Control............................................................. 31 FD Fan Lube Oil System.............................................................48 Gas Automatic Shutdown Operation........................................... 14 Close-Coupled Overfire Air (CCOFA) Damper Control............... 33 SCAH Isolation Gate Logic..........................................................48 Gas Corner Shutdown................................................................ 14 Separated Overfire Air (SOFA) Damper Control......................... 33 AH Bypass Gate Drive Logic.......................................................48 Gas Corner Trip.......................................................................... 14 Furnace Pressure Control.......................................................... 34 AH Gas Inlet Damper Drive Logic............................................... 49 Oil Elevation Shutdown.............................................................. 15 Feedwater Control...................................................................... 35 AH Gas Outlet Damper Drive Logic............................................. 49 Oil Manual Operation.................................................................. 15 Feedwater Demand.................................................................... 35 ID Fan Outlet Damper Logic........................................................49 Oil Automatic Shutdown Operation............................................. 15 Start-up, Warm-Keeping & Water Separator Systems................ 37 SOFA Airflow Element Purge Logic............................................. 49 Oil Corner Shutdown.................................................................. 15 Separator Storage Tank Level Control....................................... 37 FD Fan Outlet Shutoff Damper Logic.......................................... 49 Oil Corner Local Scavenge......................................................... 16 Minimum Economizer Flow Control Valve (MEFCV)................... 37 GR Fan Inlet Damper Drive Logic............................................... 50 Oil Corner Trip............................................................................ 16 Warming Line Valve Control....................................................... 37 Seal Air to GR Ring Header Damper Drive Logic........................ 50 ©COPYRIGHT GE Vernova May, 2024 i  Yanbu Power Station, Unit No.’s 10 – 50 Boiler Recirculation Isolation Valve Logic................................... 50 Boiler Water Circulation Pump Drive Logic................................. 50 Boiler Water Circulation Pump Suction and Discharge Valve Logic................................................................................................... 51 CCCW Supply to BWCP Cooler and Thermal Barrier Drain Isolation Valve Logic................................................................... 51 High Water Level Isolation Valves.............................................. 51 Superheat (SH) Spraywater Block Valve Logic........................... 52 Reheat (RH) Spray Block Valve Logic........................................ 52 Condensate Pump Drive Logic................................................... 53 SCAH Condensate Pump Drive Logic........................................ 53 LP Startup Condensate Pump Drive Logic................................. 54 Boiler Drain Valve Logic............................................................. 54 Boiler Vent Valve Logic.............................................................. 54 Air Heater Drive Motor and Air Motor.......................................... 55 Air Heater Guide Bearing Lube Pump Drive Logic...................... 55 Air Heater Support Bearing Lube Pump Drive Logic.................. 55 Boiler Electromatic Relief Valve Logic........................................ 55 Exercises....................................................................................... 56 General...................................................................................... 56 Overview.................................................................................... 56 Burner Management System (BMS)........................................... 57 Open Loop Control (OLC)........................................................... 58 Closed Loop Control (CLC)........................................................ 59 Test Questions for Verification of Learning Progress.................. 59 Questions................................................................................... 59 Questions (continued)........................................................................ 60 Lesson Question Solution Key.................................................... 61 ©COPYRIGHT GE Vernova May, 2024 ii  Yanbu Power Station, Unit No.’s 10 – 50 Disclaimer Objectives Acronyms "This Student Information Manual and any training material, whether Operation Training ACV Volts AC Current written or oral, furnished as part of any seminar or course presented ASME American Society of Mechanical Enqineers by GE Vernova, Inc. is for general, informational purposes and is not At the successful completion of this course, the student will have BCS Burner Control Svstem intended to be used as a comprehensive instruction for operation or sufficient knowledge to operate the upgraded systems and BMS Burner Manaqement System maintenance of equipment. By enrollment and attendance in an GE equipment in accordance with the recommended procedures and Btu/ft³ British Thermal Unit per Cubic Foot, Volume system design specifications. This objective will be accomplished by British Thermal Unit for energy, scf: Standard Cubic Feet of Gas@ Btu/scf Vernova course, the attending company agrees that (i) GE Vernova (Standard conditions of 14.7 psi and 68°F) shall not be liable in contract or negligence or other cause of action enabling the students to: CCOFA Close Coupled Overtire Air for any damages of any kind and, in particular, for any special, Describe the changes made from the original firing C-E Combustion Engineering, Inc. CFM Cubic Foot per Minute incidental or consequential damages, including, but not limited to, equipment to the gas firing equipment. CH4 Methane loss of profits and revenue and loss due to business interruption and Describe the firing characteristics of gas and how it differs Class 1 NFPA Rating lgnitor rated generally in excess of 10% of full load burner input (ii) GE Vernova provides information to the attending company from firing other fuels. Closed Loop Control - Automatic control logic for modulating systems CLC without express or implied warranties or guarantees of any kind, and Locate the gas valves associated with the gas firing system based on feedback that use of any information furnished by GE Vernova is at the sole and describe the function of the valves. CO Carbon Monoxide risk of the attending company." Describe the functions of the major systems and components CO2 Carbon Dioxide DCS Distributive Control System It must be recognized that no amount of written instructions can furnished for the gas conversion. DFI Diagnostic Flame Indicator - lgnitor flame proving replace intelligent thinking and reasoning on the part of properly Describe the normal start up and shut down operating Exp. Expansion (allowance) trained operations and maintenance personnel, especially when sequences associated for each system or piece of FHI Fuel Heat Input coping with unforeseen conditions. The Owner should ensure that equipment. FSA Flame Signal Analyzer - Scanner both operations and maintenance personnel are familiar with the List the critical operating parameters and values associated HHV Higher Heating Value - Gross heating value, taking latent heat of vaporization of the water formed equipment through training and experience. This training manual is with the systems and equipment to be monitored during HMI soft PB Human / Machine Interface, soft Push Button an aid to, and not a substitute for, skilled operations, inspection and operation. I/O Input/Output maintenance personnel. List abnormal operating conditions and select and describe in. Hg Inches of Mercury, pressure ~0.5 osi or 13.6 inches of water possible causes and steps required to control or remedy kpph Thousands of pounds per hour abnormal conditions. lb/hr Pounds per hour lb/mmBtu Pounds per million (106) Btu Maintenance Training LED Liqht Emitting Diode LIMELIGHT™ Alstom product line of scanners and ignitors At the successful completion of this course, the student will be able LNBFS Low NOx Bulk Firing System to plan for and safely perform preventive maintenance relative to the LNCFS Low NOx Concentric Firing System proposed upgrade. This objective will be accomplished by enabling MCR Maximum Continuous Rating, steady State Full Load the students to: MFT Master Fuel Trio One Million (106) British Thermal Units/hour Determine recommended maintenance schedules, lubricants, mmBtu/hr MW Megawatt and wear parts for key components. National Electrical Manufacturers Association, Code rating, re: NEMA Identify problems associated with normal and abnormal NEMA 4 is watertight, good for outdoor application equipment operation and possible corrective actions with the NFPA National Fire Protection Association systems/equipment. NOx Nitrogen Oxide, Typically NO and NO2 Describe the critical activities and considerations for O2 Oxygen, often expressed as excess air Open Loop Control - Automatic control logic for safely starting, preparing for equipment inspection during a routine boiler OLC stopping and in an emeraency tripping outage. OSHA Occupational Safety & Health Administration For the upgraded systems and equipment, identify areas to P&ID Process & Instrumentation Diagram, note that each P&ID collection has its own legend inspect, possible inspection findings, and general care for PM & PdM PM & PdM Preventative Maintenance & Predictive Maintenance continued reliable service. ppm ppm Parts per million psig Pounds per square inch SOFA Separated Overfire Air Sp. Gr. of 0.6 Specific gravity, note that 1.0 is the Sp. Gr. of water VDC Volts direct current Pressure indication, water gauge or water column, note, 1: w.c. = w.g. or w.c. 0.036 psi WB Windbox ©COPYRIGHT GE Vernova May, 2024 iii  Yanbu Power Station, Unit No.’s 10 – 50 See Drawings in Attachment 1: Burner Management System Control I2B-000120-1D8840 BMS - SYMBOLS/DRAWING LIST/TITLE PAGE Introduction I2B-000120-1D8841 BMS - BOILER PURGE PERMISSIVES I2B-000120-1D8842 BMS - MASTER FUEL TRIP/FIRST OUT The Burner Management System (BMS) logic is designed to ensure a safe, orderly start-up and shut-down sequence of the fuel firing equipment and to prevent errors of omission or I2B-000120-1D8843 BMS - MISCELLANEOUS BOILER TRIP commission during execution of the unit operating sequences. The system provides safety I2B-000120-1D8844 BMS - UNIT FLAME FAILURE interlocks to protect against potential emergency situations in the event of malfunction of fuel firing equipment and associated air systems. The safety features of this system are designed for I2B-000120-1D8844 BMS - UNIT FLAME FAILURE protection in most common emergency situations. The system cannot replace the judgment of I2B-000120-1D8845 BMS - LIGHT OIL TRIP VALVE the Operator in all situations. I2B-000120-1D8846 BMS - HEAVY OIL TRIP VALVE The functions of the system are to: I2B-000120-1D8847 BMS - IGNITOR GAS TRIP VALVE 1. Ensure that a furnace purge cycle has been completed prior to firing any fuel. I2B-000120-1D8848 BMS - GAS TRIP VALVE 2. Prevent start-up of individual fuel firing equipment unless certain permissive interlocks I2B-000120-1D8849 BMS - POST PURGE FAN TRIP have first been satisfied. I2B-000120-1D8850 BMS - WINDBOX DAMPER CONTROL 3. Monitor and control the proper component sequence during start-up and shutdown of fuel firing equipment. I2B-000120-1D8851 BMS – SCANNER/IGNITOR AIR FAN 4. Ensure that certain safety interlocks remain satisfied during operation of fuel firing I2B-000120-1D8852 BMS - ECONOMIZER INLET FEEDWATER FLOW equipment. I2B-000120-1D8853 BMS - SEPARATOR LEVEL CONTROL 5. Provide component status feedback to the Operator and the unit control system. I2B-000120-1D8854 BMS - FD FAN AIR FLOW 6. Initiate a fuel trip when certain abnormal operating conditions exist. I2B-000120-1D8863 BMS - TUBE METAL TEMPERATURES NOTE: It is essential that all parts of the Burner Management System are in operable condition I2B-000120-1D8864 BMS - TUBE METAL TEMPERATURES and in service at all times if the system is to provide the function for which it is designed. I2B-000120-1D8866 BMS - OIL AUTO LOAD CONTROL NOTE: It must be recognized that any number of abnormal operating scenarios may be encountered during unit operation. In such cases, plant specific administrative and/or safety I2B-000120-1D8868 BMS - GAS AUTO LOAD CONTROL policies and procedures should take precedence if in conflict with this document. I2B-000120-1D8869 BMS - MAIN FUEL SEQUENTIAL TRIPPING I2B-000120-1D8870 BMS - LIGHT/HVY OIL START/STOP CONTROL I2B-000120-1D8871 BMS - LIGHT/HEAVY OIL CORNER CONTROL I2B-000120-1D8872 BMS - LIGHT/HVY OIL ELEVATION MONITORING I2B-000120-1D8873 BMS - HEAVY OIL START/STOP CONTROL I2B-000120-1D8874 BMS - HEAVY OIL CORNER CONTROL I2B-000120-1D8875 BMS - HEAVY OIL ELEVATION MONITORING I2B-000120-1D8876 BMS - GAS START/STOP CONTROL I2B-000120-1D8877 BMS - GAS CORNER CONTROL I2B-000120-1D8878 BMS - GAS ELEVATION MONITORING ©COPYRIGHT GE Vernova May, 2024 4 Yanbu Power Station, Unit No.’s 10 – 50 Burner Management System Logic 8. The auxiliary air dampers at all elevations are modulating (not closed). 9. All separated overfire air (SOFA) dampers are closed. Unit Start-Up 10. The inlet and outlet dampers of both GR fans are closed. Furnace Purge (Reference Drawing No. -1D8841) Prior to firing any fuel in the furnace (either initially or after a unit trip), a furnace purge cycle must be completed. The “purge ready” condition is established when all of the following permissives are satisfied: 1. No boiler trip command exists. 2. All BMS “system power” available, as follows: a) Unit interrogation power is available. b) Unit drive power is available. c) Each oil elevation power is available (elevations “A”, “B”, “C” & “D”). d) Each gas elevation power is available (elevations “AB”, “BC” & CD”). 3. Unit air flow is greater than 30%. 4. Nozzle tilts horizontal and air flow less than 40%. 5. The following conditions exist at the oil firing equipment: a) The Light Oil Trip Valve is closed. b) All light oil trip valves are closed on elevation A. c) The Heavy Oil Trip valve is closed. d) All heavy oil trip valves are closed on elevations A, B, C & D. e) The Heavy Oil Return Valve is closed. 6. The following conditions exist at the gas firing equipment: a) The Ignitor Gas Header Trip Valve is closed. b) All ignitor trip valves are closed on elevations AB, BC & CD. c) The Main Gas Header Trip Valve is closed. d) All Main Gas Header Trip Valves are closed on elevations AB, BC & CD. 7. All flame scanners on all scanner elevations indicate no flame. ©COPYRIGHT GE Vernova May, 2024 5  Yanbu Power Station, Unit No.’s 10 – 50 When all these conditions are satisfied, the 1st Stage purge sequence may be initiated by e) Nozzle tilts horizontal and airflow less than 40% (requirements bypassed the Operator, by pressing the Purge Start pushbutton. after any fuel elevation is in service). f) No flame failure signal exists. If any of the “purge ready” permissives are lost during the 1st Stage purge sequence, the “purge ready” condition is removed and the purge timer is reset. g) No close command for the oil (header) trip valve exists. The oil trip valve is automatically closed if any of the following conditions exist. When the two (2) minute 1st stage purge sequence is completed, the start sequence for each GR fan is initiated. When “Both GR fans are in service” AND “All GR air dampers 1. The oil trip valve is proven “not closed”, any light / heavy oil trip valve is “not are modulating” the 2nd Stage purge sequence is initiated. closed” and either the following conditions exist, for more than 2 seconds. When the three (3) minute 2nd Stage purge sequence is completed, the “master fuel trip” a) The light / heavy oil header pressure is low. memory is reset. A “no master fuel trip” condition now exists. The Operator may now place the firing equipment in service. b) Atomizing air / steam header pressure is low. c) Atomizing steam pressure is high (heavy oil only). Oil Header Trip Valve Operation (Reference Drawing No. -1D8845 for Light Oil & -1D8846 for Heavy Oil) 2. A “master fuel trip” signal is established. After the “No Master Fuel Trip” signal is established, the oil trip valve can be opened after Oil Leak Test the following permits are satisfied: (Reference Drawing No. -1D8845 for Light Oil & -1D8846 for Heavy Oil) 1. All light /heavy oil trip valves remain closed. All of the following conditions must be present before an oil leak test can be started: 2. The light / heavy oil supply pressure is “adequate”. Airflow is greater than 30%. All light / heavy (corner) oil trip valves closed. Light / heavy oil supply pressure satisfactory. 3. Once the oil trip valve is opened, the oil elevation “trip command” is removed. Light / Heavy Oil Header Trip Valve closed. Leak test not in progress. 4. The light / heavy oil elevation “start permit” is established when the following conditions are satisfied: When all of the above conditions are present, the “Ready for Leak Test” indication will come on. The leak test can now be started. This is accomplished by activating the “Test a) The oil trip valve is open. Start” push button. The “Oil Leak Test in Progress” indication and annunciation will come on. The leak test logic is implemented in two separate sixty (60) second phases. The b) The light / heavy oil header pressure is not low. first phase tests the corner trip valves for leakage. The second phase tests the header c) Atomizing air / steam header pressure is not low. trip valve for leakage. d) No master fuel trip signal exists. ©COPYRIGHT GE Vernova May, 2024 6  Yanbu Power Station, Unit No.’s 10 – 50 Once the test start is activated, the leak test proceeds as follows: Upon successful completion of the Corner Valve Leak Test, the leak test or Heavy Oil Return Valve is opened to depressurize the oil piping downstream of the oil header trip valve. When the system is depressurized, the Leak Test Valve / Heavy Oil Return & Short 1. System Pressurization Recirc. Valves are opened. The following events occur in order to pressurize the oil piping downstream of the oil trip A 60 second Header Trip Valve Leak Test starts when the following events occur: valve in preparation for the first phase of the leak test: The light / heavy oil header pressure is low A signal is sent to the CLC system to open the Light / Heavy Oil Control Valve. A fifteen (15) second “open command” is sent to the Light / Heavy Oil Header Trip The Light / Heavy Oil Trip Valve is closed Valve. After the trip valve has been open for fifteen (15) seconds, it is closed. The The Leak Test Valve / Heavy Oil Return & Short Recirc. Valves are closed. system should now be pressurized. The Corner & Leak Test Valve Leak Test Complete indication is activated. If the header pressure is low, the test does not proceed and the “Corner Leak Test Valve Leak Test Failed” Indicator will activate after the 150 second test timer expires. If the When the sixty (60) second timer expires and the oil header pressure is low, the “Oil Leak header pressure is not low the test proceeds to the Corner Valve Leak Test. Test Complete” indication will come on. This will indicate that the Oil Header Trip Valve Leak Test is successful. If the oil header pressure is not low, the “Header Trip Valve Leak Test Failed” indication will be active at the end of the 165 second leak test time. 2. Corner Valve Leak Test Leak test alarm indicators A sixty (60) second corner leak test starts when the following events occur: Either (or both) “corner/leak test valve leak test failed” or “header trip valve leak test failed” The fifteen (15) second pressurization timer has expired. alarm indicators will come on when the test fails to complete within one hundred sixty-five The light / heavy oil header pressure is not low. (165) seconds after the “test start” push button is activated. The Light / Heavy Oil Header Trip Valve is “fully closed”. The Light Oil Leak Test Valve / Heavy Oil Return & Short Recirc. Valves are closed. The “Corner/leak test valve leak test failed” Alarm When the sixty (60) second timer expires, the following occurs: This alarm is caused by any corner trip valve leakage or oil leak test shut off valve leakage. The “Header trip valve leak test failed” Alarm If the oil pressure is low, the leak test stops and the final test failure indication will be activated after the 165 second test timer expires. This alarm is caused by oil header trip valve leakage. If the oil pressure is not low, the “Corner & Leak Test / Recirc. Valves Leak Test Ignitor Gas Header Trip Valve Operation Complete” indication is activated and the leak test continues to the Header Trip (Reference Drawing No. -1D8847) Valve Leak Test. After the “No Master Fuel Trip” signal is established, the Ignitor Gas Header Trip Valve 3. Light / Heavy Oil Header Trip Valve Leak Test can be opened after the following permits are satisfied: ©COPYRIGHT GE Vernova May, 2024 7  Yanbu Power Station, Unit No.’s 10 – 50 1. All ignitor gas trip valves remain closed. Airflow is greater than 30%. 2. The ignitor gas supply pressure is “adequate”. All ignitor gas trip valves are closed. 3. Once the Ignitor Gas Header Trip Valve is opened, the ignitor gas elevation Ignitor gas supply pressure is satisfactory. “trip command” is removed. The Ignitor Gas Header Trip Valve is closed. 4. The “ignitor gas elevation start permit” is established when the following Leak test is not in progress. conditions are satisfied: a) The Ignitor Gas Header Trip Valve is open When all of the above conditions are present, the “Ready for Leak Test” indication will b) The ignitor gas header pressure is not low. come on. The leak test can now be started. This is accomplished by activating the “Test Start” push button. The “Ignitor Gas Leak Test in Progress” indication and annunciation c) The ignitor gas header pressure is not high. will come on. The leak test logic is implemented in two separate sixty (60) second phases. The first phase tests the corner trip valves and riser vent valves for leakage. The second d) No master fuel trip signal exists. phase tests the header trip valve for leakage. e) Nozzle tilts are horizontal and airflow is less than 40% OR any fuel Once the test start is activated, the leak test proceeds as follows: elevation is in service. 1. System Pressurization f) No close command for the Ignitor Gas Header Trip Valve exists. The following events occur in order to pressurize the ignitor gas piping downstream of the The ignitor gas trip valve is automatically closed if any of the following conditions exist. header trip valve in preparation for the first phase of the leak test: 3. The Ignitor Gas Header Trip Valve is proven “not closed”, any ignitor gas trip valve is “not closed” and either the following conditions exist, for more than 2 All of the ignitor gas riser vent valves are closed. seconds. A signal is sent to the CLC system to open the Ignitor Gas Control Valve. A fifteen (15) second “open command” is sent to the Ignitor Gas Header Trip Valve. a) The ignitor gas header pressure is low. After the header trip valve has been open for fifteen (15) seconds, it is closed. The b) The ignitor gas header pressure is high system should now be pressurized. 4. A “master fuel trip” signal is established. If the header pressure is low, the test does not proceed and the “Corner Trip / Riser Vent Valve Leak Test Failed” Indicator will activate after the 165 second test timer expires. If Ignitor Gas Leak Test the header pressure is not low the test proceeds to the Corner Trip / Riser Vent Valve (Reference Drawing No. -1D8847) Leak Test. All of the following conditions must be present before the ignitor gas leak test can be 2. Corner Trip / Riser Vent Valve Leak Test started: A sixty (60) second leak test starts when the following events occur: ©COPYRIGHT GE Vernova May, 2024 8  Yanbu Power Station, Unit No.’s 10 – 50 The fifteen (15) second pressurization timer has expired, Leak test alarm indicators The ignitor gas header pressure is not low. The Ignitor Gas Header Trip Valve is “fully closed”. Either (or both) “corner trip / riser vent valve leak test failed” or “header trip valve leak test failed” alarm indicators will come on when the test fails to complete within one hundred All riser vent valves are closed. sixty-five (165) seconds after the “test start” push button is activated. When the sixty (60) second timer expires, the following occurs: The “corner trip / riser vent valve leak test failed” alarm If the ignitor gas header pressure is low, the leak test stops and the test failure This alarm is caused by any corner trip valve leakage or any ignitor gas riser vent indication will be activated after the 165 second test timer expires. valve leakage. The “header trip valve leak test failed” alarm If the ignitor gas pressure is not low, the “Corner Trip & Riser Vent Valve Leak Test This alarm is caused by Ignitor Gas Header Trip Valve leakage. Complete” indication is activated and the leak test continues to the “Header Trip Valve Leak Test”. Main Gas Header Trip Valve Operation (Reference Drawing No. -1D8848) 3. Ignitor Gas Header Trip Valve Leak Test After the “No Master Fuel Trip” signal is established, the Main Gas Header Trip Valve can Upon successful completion of the Corner Trip / Riser Vent Valve Leak Test, the riser be opened after the following permits are satisfied: vent valves are opened to depressurize the ignitor gas piping downstream of the Ignitor Gas Header Trip Valve. The riser vent valves close again when the header pressure is low. 1. All main gas corner trip valves remain closed. A 60 second Ignitor Gas Header Trip Valve Leak Test starts when the following events 2. The main gas supply pressure is “adequate”. occur: 3. Once the Main Gas Header Trip Valve is opened, the main gas elevation “trip Ignitor gas header pressure is low command” is removed. Ignitor Gas Header Trip Valve is closed All ignitor gas riser vent valves are closed. 4. The “Main Gas Elevation Start Permit” is established when the following conditions are satisfied: Corner & Riser Vent Valve Leak Test Complete a) Main Gas Header Trip Valve is open When the leak test expires and the ignitor gas header pressure is low, the “Ignitor Gas Leak Test Complete” indication will come on. This will indicate that the “Ignitor Gas b) Main gas header pressure not low. Header Trip Valve Leak Test” is successful. If the ignitor gas header pressure is not low, the “Header Trip Valve Leak Test Failed” will be active at the end of the 165 second leak c) No master fuel trip signal exists. test time. ©COPYRIGHT GE Vernova May, 2024 9  Yanbu Power Station, Unit No.’s 10 – 50 d) Nozzle tilts horizontal and airflow less than 40% OR any fuel elevation is in The first phase tests the corner trip valves and riser vent valves for leakage. The second service. phase tests the header trip valve for leakage. e) No close command for the Main Gas Header Trip Valve exists. Once the test start is activated, the leak test proceeds as follows: The Main Gas Header Trip Valve is automatically closed if any of the following conditions 1. System Pressurization exist. The following events occur in order to pressurize the main gas piping downstream of the 5. The Main Gas Header Trip Valve is proven “not closed”, any main gas corner Main Gas Header Trip Valve in preparation for the first phase of the leak test: trip valve is “not closed” and either the following conditions exist, for more than 2 seconds. A signal is sent to the CLC system to open the Main Gas Control Valve. a) The main gas header pressure is “low”. A fifteen (15) second “open command” is sent to the Main Gas Header Trip Valve. After the trip valve has been open for fifteen (15) seconds, it is closed. The system b) The main gas header pressure is high should now be pressurized. 6. A “master fuel trip” signal is established. If the header pressure is low, the test does not proceed and the “Corner Trip / Riser Vent Valve Leak Test Failed” Indicator will activate after the 165 second test timer expires. If the header pressure is not low the test proceeds to the Corner Trip / Riser Vent Valve Main Gas Leak Test Leak Test. (Reference Drawing No. -1D8848) 2. Corner Trip / Riser Vent Valve Leak Test All of the following conditions must be present before the main gas leak test can be started: A sixty (60) second leak test starts when the following events occur: Airflow is greater than 30%. the fifteen (15) second pressurization timer has expired, All main gas corner trip valves closed. the main gas header pressure is not low Main gas supply pressure satisfactory. The Main Gas Header Trip Valve is “fully closed” Main Gas Header Trip Valve closed. All main gas riser vent valves are closed. Leak test not in progress. When the sixty (60) second timer expires, the following occurs When all of the above conditions are present, the “Ready for Leak Test” indication will come on. The leak test can now be started. This is accomplished by activating the “Test Start” push button. The “Main Gas Leak Test in Progress” indication and annunciation If the main gas pressure is low, the leak test stops and the test failure indication will come on. The leak test logic is implemented in two separate sixty (60) second phases. will be activated after the 165 second test timer expires. ©COPYRIGHT GE Vernova May, 2024 10  Yanbu Power Station, Unit No.’s 10 – 50 This alarm is caused by Main Gas Header Trip Valve leakage. If the main gas pressure is not low, the “Corner Trip & Riser Vent Valve Leak Test Complete” indication is activated and the leak test continues to the “Header Trip Valve Leak Test”. Oil Elevation Start-Up (Reference Drawing Nos. -1D8870, -1D8871, -1D8872, -1D8873, -1D8874 & -1D8875) 3. Main Gas Header Trip Valve Leak Test There is one light/heavy oil elevation (A) and three heavy oil elevations (B, C & D) that Upon successful completion of the Corner Trip / Riser Vent Valve Leak Test, the riser serve the unit. For Elevation “A”, THE OPERATOR MUST SELECT LIGHT OR HEAVY vent valves are opened to depressurize the gas piping downstream of the Main Gas OIL. Each oil elevation can be placed in service manually or automatically. Changeover Header Trip Valve. The riser vent valves close again when the header pressure is low. from LO to HO or back requires that all Elevation A light/heavy oil trip valves and atomizing air/steam valves be closed prior to changeover. The manner in which the oil elevation is placed in service is described in the following sections. A 60 second Main Gas Header Trip Valve Leak Test starts when the following events occur: Firing Mode / Manual Operation There are 2 modes of firing, Pair Mode and Elevation Mode. The Operator may select Main gas header pressure is low. the desired mode by activating either the Pair or Elevation pushbuttons. Main Gas Header Trip Valve is closed. All main gas riser vent valves closed. When a Pair Start pushbutton is activated, the pair or elevation will start according to the Corner Trip & Riser Vent Valve Leak Test Complete selected operating mode. An oil elevation will only be started in elevation mode when started from Auto Load Control. In either mode of operation the individual corner start sequence is the same and is detailed in the “Corner Start Sequence” section below. When the leak test expires and the main gas header pressure is low, the “Main Gas Leak Test Complete” indication will come on. This will indicate that the “Main Gas Header Trip In Elevation Mode, the eight (8) oil corners are placed in service sequentially at 15 Valve Leak Test” is successful. If the main gas header pressure is not low, the “Header second intervals. Each corner in Furnace “A” is started simultaneously with the Trip Valve Leak Test Failed” indication will be active at the end of the 165 second leak associated corner in Furnace “B”. The elevation is started according to the test time. following sequence: a. Corner 1 (Starts immediately when elevation start is issued) b. Corner 5 (Starts 15 seconds after 1) Leak test alarm indicators c. Corner 7 (Starts 15 seconds after 5) d. Corner 3 (Starts 15 seconds after 7) e. Corner 2 (Starts 15 seconds after 3) Either (or both) “corner trip / riser vent valve leak test failed” or “header trip valve leak test f. Corner 6 (Starts 15 seconds after 1) failed” alarm indicators will come on when the test fails to complete within one hundred g. Corner 8 (Starts 15 seconds after 5) sixty-five (165) seconds after the “test start” push button is activated. h. Corner 4 (Starts 15 seconds after 7) i. The “corner trip / riser vent valve leak test failed” alarm In Pair Mode, the eight (8) oil guns are placed in service as “pairs” (Pairs 1–3 & 2- 4 in Furnace “A” and Pairs 5-7 & 6-8 in Furnace “B”). This alarm is caused by any corner trip valve leakage or any main gas riser vent valve leakage. Activating the PAIR START push button for Corners 1,3,5,7 generates a start The “header trip valve leak test failed” alarm command and starts the oil corners according to the following sequence: ©COPYRIGHT GE Vernova May, 2024 11  Yanbu Power Station, Unit No.’s 10 – 50 a. Corner 1 (Starts immediately when pair start is issued) b. Corner 5 (Starts 15 seconds after 1) 3. The manual atomizing isolation valve and manual oil isolation valve are open. c. Corner 7 (Starts 15 seconds after 5) d. Corner 3 (Starts 15 seconds after 7) 4. The associated corner discriminating flame scanner indicates “NO FLAME”. Activating the PAIR START push button for Corners 2,4,6,8 generates a start command and starts the oil corners according to the following sequence: 5. The scavenge valve is closed. a. Corner 2 (Starts immediately when pair start is issued) b. Corner 6 (Starts 15 seconds after 2) c. Corner 8 (Starts 15 seconds after 6) When the “start corner” signal exists and the start permits listed above are satisfied, the d. Corner 4 (Starts 15 seconds after 8) corner oil gun is placed in service in a sequential manner as follows: Oil Automatic Startup Operation 1. The high energy arc (HEA) ignitor receives an “advance” signal. An oil elevation will be placed in service automatically when oil is the selected fuel for 2. When the HEA ignitor is “advanced”, the atomizing valve is opened. Auto Load Control and Auto Load Control is activated. With Oil Auto Load Active and a Start First Oil Elevation signal from the OLC system, an Auto Load Start Elev. “A” command is generated (provided that Elev. “A” was not previously placed into service 3. When the HEA ignitor is “advanced” and the atomizing valve is open, the oil manually). If Elev. “A” was already in service and Elev. “B” is not in service, an Auto Load valve’s “open” command is established. Start Elev. “B” command is generated. If both Elev. “A” and “B” are in service, an Auto Load Start Elev. “C” command is generated. 4. When the oil valve is “not closed”, a 30-second ignition trial period is started One hundred fifty seconds after the first oil elevation is started, a second oil elevation will and the HEA ignitor “spark” signal is established. be started automatically when a Start Oil Elevation signal from the CLC system is generated for more than 20 seconds. 5. Upon successful light-off of the oil gun (oil flame scanner shows flame and the oil corner valve is open for more than two seconds), the HEA ignitor “spark” Oil Corner Start Sequence signal is removed and the HEA ignitor spark rod is retracted. When a “start corner” signal exists, each corner is placed in service in the same manner 6. If the oil gun fails to light-off at the end of the 30-second trial time, the oil valve regardless of the defined operating mode. The logic is structured to ensure that a failure is closed, the HEA ignitor “spark” signal is removed and the HEA ignitor spark in the starting sequence of equipment will result in the closing of the oil and atomizing rod is retracted. valves. A local control switch is provided to allow local maintenance of each oil gun. 7. Alarms are provided to indicate that the oil elevation equipment has failed to The following conditions must be satisfied before the associated corner oil gun can be operate in the proper manner. placed in service. 1. The oil gun is engaged. Main and Ignitor Gas Elevation Start-Up (Reference Drawing Nos. -1D8876 & -1D8877) 2. The local control switch is in the “REMOTE” position. ©COPYRIGHT GE Vernova May, 2024 12  Yanbu Power Station, Unit No.’s 10 – 50 There are three gas elevations (AB, BC & CD) that serve the unit. Each gas elevation When 3 out of 4 corners are in operation and following a 95 second holding period, can be placed in service manually or automatically. The manner in which the gas the remaining corners are started according to the following sequence: elevation is placed in service is described in the following sections. e. Corner 2 ((Starts immediately) f. Corner 6 (Starts 15 seconds after 2) Gas Manual Operation g. Corner 4 (Starts 15 seconds after 6) h. Corner 8 (Starts 15 seconds after 4) The ignitor gas elevation may be started separately or as the first part of the main gas For elevations “BC” and “CD”, the eight (8) gas corners are placed in service sequentially elevation start-up. The elevation of ignitors is placed into service by the Operator at 15 second intervals. The elevation is started according to the following sequence: activating the Start pushbutton provided both of the following conditions exist: a. Corner 1 (Starts immediately when elevation start is issued) The Ignitor Gas Elevation Start Permit is present b. Corner 5 (Starts 15 seconds after 1) c. Corner 3 (Starts 15 seconds after 5) All of the ignitor gas trip valves on the elevation are closed OR any ignitor is proven d. Corner 7 (Starts 15 seconds after 3) e. Corner 2 (Starts 15 seconds after 7) f. Corner 6 (Starts 15 seconds after 2) The ignitors in each furnace are placed in service at 10 second intervals. Each ignitor is g. Corner 4 (Starts 15 seconds after 6) provided with double block and vent valves. When the ignitor cabinet receives a start h. Corner 8 (Starts 15 seconds after 4) signal, the ignitor cabinet spark transformer is energized and the associated ignitor trip valves are opened and the vent valve is closed. Following a ten second trial time, the spark transformer is de-energized. At the completion of this trial time, if the ignitor flame detector indicates “flame” and the ignitor flow is adequate, the ignitor will remain in Gas Automatic Startup Operation service. If the ten second time trial expires and if either the ignitor flame detector indicates “no flame” or if the ignitor flow is not adequate, the ignitor is tripped and the ignitor trip A gas elevation will be placed in service automatically if gas is the selected fuel for Auto valves are closed and the vent valve is opened. Load Control and Auto Load Control is activated. With Gas Auto Load Active and a Start First Gas Elevation signal from the OLC system, an Auto Load Start Elev. “AB” command is generated (provided that Elev. “AB” was not previously placed into service manually). The main gas elevation is placed into service by the Operator activating the Start If Elev. “AB” was already in service and Elev. “BC” is not in service, an Auto Load Start pushbutton provided the following condition exists: Elev. “BC” command is generated. If both Elev. “AB” and “BC” are in service, an Auto Load Start Elev. “CD” command is generated. The Main Gas Elevation Start Permit is present One hundred fifty seconds after the first gas elevations is started, a second gas elevation will be started automatically when a Start Gas Elevation signal from the CLC system is The Ignitor Start Time has expired and 3 out of 4 ignitors are proven in Furnace generated for more than 20 seconds. “A” and Furnace “B” For elevation “AB”, two corners are placed into service in each furnace at 15 second intervals. The elevation is started according to the following sequence: Main Gas Corner Start Sequence a. Corner 1 (Starts immediately when elevation start is issued) When a “start corner” signal exists, each corner is placed in service in the same manner. b. Corner 5 (Starts 15 seconds after 1) The logic is structured to ensure that a failure in the starting sequence of equipment will c. Corner 3 (Starts 15 seconds after 5) result in the closing of the main gas corner trip valves and opening of the associated vent d. Corner 7 (Starts 15 seconds after 3) valves. ©COPYRIGHT GE Vernova May, 2024 13  Yanbu Power Station, Unit No.’s 10 – 50 The following conditions must be satisfied before the main gas corner trip valves can be The elevation of ignitors is taken out of service by the Operator activating the Stop opened. pushbutton. The eight (8) ignitor gas corners are stopped simultaneously. 1. The ignitor is proven. Gas Automatic Shutdown Operation 2. The manual gas isolation valve is open. A gas elevation is taken out of service automatically when gas is the selected fuel for Auto Load Control and Auto Load Control is activated. With Gas Auto Load Active and a Stop 3. No stop corner signal exists. Gas Elevation signal from the CLC system present for more than 20 seconds, an Auto 4. No main gas elevations trip exists. Load Stop Elev. “CD” command is generated (if any gas burner is in service on Elev. “CD”). If all burners on Elev. “CD” are not in service and any burner on Elev. “BC” is in 5. No main gas sequential trip exists. service, an Auto Load Stop Elev. “BC” command is generated. If both Elev. “AB” and “BC” are not in service, an Auto Load Stop Elev. “AB” command is generated. One hundred fifty seconds after the first gas elevations is stopped, a second gas elevation When the “start corner” signal exists and the start permits listed above are satisfied, the will be stopped automatically when another Stop Gas Elevation signal from the CLC main gas corner trip valves are opened and the main gas corner vent valve is closed. system is generated for more than 20 seconds. Gas Elevation Shutdown Gas Corner Shutdown (Reference Drawing Nos. -1D8876, 8877) When a “stop corner” signal exists, each main gas corner trip valve’s open command Gas Manual Operation signal is removed, allowing the valves to close. The main gas corner vent valve’s close command is also removed, allowing the valve to open. The gas loading should be reduced before an elevation is shut down. After the gas loading is reduced, the gas elevation is shut down by the operator. Gas Corner Trip When the Main Gas Elevation Stop pushbutton is activated, the following takes place: When a gas burner is “in service”, the gas corner is automatically shut down if a Main Gas Elevation Trip or Sequential Trip signal is established. The eight (8) main gas corners are stopped sequentially. Each corner stop occurs in 15 second intervals using the following sequence: Any of the following conditions will trip the gas corner: a. Corner 1 (Stops immediately when elevation start is issued) 1. The associated ignitor is not “proven” (when the main gas elevation is not in b. Corner 5 (Stops 15 seconds after 1) service at fireball loading and the gas flame scanner shows “no flame”). c. Corner 3 (Stops 15 seconds after 5) d. Corner 7 (Stops 15 seconds after 3) e. Corner 2 (Stops 15 seconds after 7) 2. The Main Gas Elevation Trip signal exists when any of the following conditions f. Corner 6 (Stops 15 seconds after 2) are established. g. Corner 4 (Stops 15 seconds after 6) h. Corner 8 (Stops 15 seconds after 4) a. The Main Gas Header Trip Valve is “not open”. b. The open command on the Main Gas Header Trip Valve is removed. ©COPYRIGHT GE Vernova May, 2024 14  Yanbu Power Station, Unit No.’s 10 – 50 removed from service in a similar manner using the Corner 2,4,6,8 PAIR STOP push button. 3. The Sequential Trip signal exists. Oil Automatic Shutdown Operation On a Master Fuel Trip, the main gas elevations in service will be tripped sequentially (starting with the lowest elevation) in two second intervals. The main gas control valves An oil elevation is taken out of service automatically when oil is the selected fuel for Auto will be ramped closed at the start of this trip. Any non-firing elevation is automatically Load Control and Auto Load Control is activated. With Oil Auto Load Active and a Stop by-passed. The Main Gas Header Trip Valve and the Ignitor Gas Header Trip Valve are Oil Elevation signal from the CLC system present for more than 20 seconds, an Auto closed at the same time that the last main gas elevation is tripped. Load Stop Elev. “D” command is generated (if any oil burner is in service on Elev. “D”). If all burners on Elev. “D” are not in service and any burner on Elev. “C” is in service, an Auto Load Stop Elev. “C” command is generated. If both Elev. “D” and “C” are not in service, an Auto Load Stop Elev. “B” command is generated. Oil Elevation Shutdown One hundred fifty seconds after the first oil elevations is stopped, a second oil elevation (Reference Drawing Nos. -1D8870, -1D8871, -1D8872, -1D8873, -1D8874 & -1D8875) will be stopped automatically when another Stop Oil Elevation signal from the CLC system is generated for more than 20 seconds. Oil Manual Operation Oil Corner Shutdown The oil loading should be reduced before an elevation is shut down. After the oil loading is reduced, the oil elevation is shut down by the operator. The oil corner shuts down in the following manner: Oil shutdown can be accomplished in 2 modes, Pair Mode and Elevation Mode. When the operator Elevation Stop pushbutton is pressed the elevation will stop according to the 1. The oil corner trip valve is closed when the “scavenge” oil gun signal is currently selected operating mode. established. The oil trip valve “closed” indication comes on and the “open” indication goes off. In Elevation Mode, the eight (8) oil corners are stopped sequentially. Each corner stop occurs in 90 second intervals using the following sequence. 2. The HEA ignitor receives an “advance” command and when proven advanced, the “spark” signal is established for thirty (30) seconds. Simultaneously, the scavenge valve is opened. After sparking for 30 seconds, the HEA ignitor is a. Corner 1 (Stops immediately when elevation start is issued) retracted. b. Corner 5 (Stops 90 seconds after 1) c. Corner 7 (Stops 90 seconds after 5) d. Corner 3 (Stops 90 seconds after 7) 3. When the scavenge valve is open, a 300-second “scavenge” timer is started. e. Corner 2 (Stops 90 seconds after 3) f. Corner 6 (Stops 90 seconds after 2) g. Corner 4 (Stops 90 seconds after 6) 4. When the 300 seconds expires, the oil gun “scavenge complete” signal is h. Corner 8 (Stops 90 seconds after 4) established. The scavenge valve and the atomizing air valve are both closed. In Pair Mode, the eight (8) oil guns are removed from service as “pairs” (Pairs 1, 3 & 2, 4 in Furnace “A” and Pairs 5, 7 & 6, 8 in Furnace “B”). Activating the PAIR When both “pair stop” 360-second stop times expire, the following events occur: STOP push button for Corners 1,3,5,7 generates a stop command for Corner 1, followed by corners 3,5,7, in ninety (90) second intervals. Corners 2,4,6,8 are 5. The “corner stop” signals are removed. ©COPYRIGHT GE Vernova May, 2024 15  Yanbu Power Station, Unit No.’s 10 – 50 2. The local control station's selector switch is moved from the “REMOTE” 6. The associated oil elevation’s “position air dampers for oil firing” signal is position to the “OFF” position. removed. 3. The manual atomizing medium isolation valve is “not open”. 4. The Back-Up Trip signal exists 7. The “elevation back-up trip” signal is established for each oil gun corner on the associated oil elevation to not allow a new open command signal to each oil corner trip valve. The “elevation back-up trip” signal exists when any of the following conditions are established: 8. If any of the HEA ignitor spark rods are “not retracted”, the “unsuccessful spark rod shut down” alarm is activated. a) Light / Heavy Oil Trip Valve not open. b) Unit flame failure. 9. If any oil valve remains “not closed,” the elevation “unsuccessful shutdown” c) Sequential Trip. alarm is activated: Master Fuel Trip Oil Corner Local Scavenge (Reference Drawing Nos. –1D8842, -1D8843 & -1D8844) Each corner oil gun can be scavenged and shut down individually from the associated An abnormal unit shutdown occurs when a “master fuel trip” signal is established. A corner's local control station. “master fuel trip” signal is established when there is a boiler trip condition present after the furnace purge cycle has been completed. This is accomplished by placing the local control station's selector switch in the “SCAVENGE” position. The oil gun is scavenged and shut down in the same manner as The “master fuel trip” is accomplished by closing all header trip valves and all corner trip previously described. valves. When a “master fuel trip” signal is established, the following events will occur: When the oil gun is scavenged and successfully shut down, the local control station's 1. The Light Oil Header Trip Valve is closed. selected switch is removed from the “SCAVENGE” position and returned to the “REMOTE” position. 2. The Heavy Oil Header Trip Valve is closed 3. The Main Gas Header Trip Valve is closed Oil Corner Trip 4. The Ignitor Gas Header Trip Valve is closed 5. Oil or Gas Auto Load Control is de-activated When an oil gun is “in service”, it is automatically shut down without scavenging if a 6. Main fuel sequential tripping is started "corner trip" signal is established. The associated oil corner trip valve is closed. 7. All light oil corner trip valves are closed. 8. All heavy oil corner trip valves are closed. Any of the following conditions will establish a “corner trip” signal for the oil gun: 9. All ignitor gas corner trip valves are closed. 10. All main gas corner trip valves are closed. 1. The oil gun becomes “not engaged”. 11. The fuel and auxiliary air dampers are opened and the auxiliary air damper control is transferred to “manual”. ©COPYRIGHT GE Vernova May, 2024 16  Yanbu Power Station, Unit No.’s 10 – 50 d) The Ignitor Gas Header Trip Valve is “not open” or all ignitor gas trip valves are closed. Any of the following conditions will establish a “boiler trip” command signal which will then generate a “master fuel trip” memory signal. 17. Unit flame failure trip. 1. Loss of any (unit) critical power. 2. Loss of DCS control capability for more than ten seconds. The “Unit Flame Failure” trip is “armed” (ready to monitor for “Unit Flame Failure”) when any gas elevation or oil elevation is in service at a header pressure greater than 3. Both ID (Induced Draft) fans are off. fireball (30% of elevation loading). After becoming “armed”, a “Unit Flame Failure” trip 4. Both FD (Forced Draft) fans are off. exists when all seven fireball flame scanner elevations indicate a “No Flame Vote” in either furnace as listed below: 5. Unit airflow is less than 25%. 6. All feedwater pumps are off for more than 20 seconds and loss of fuel trip Note: References to oil guns, gas ignitors and flame scanners are based on applicable arming. corners in each furnace 7. Furnace pressure is at the “high trip” setpoint. 8. Furnace pressure is at the “low trip” setpoint. a) Elevation “A” indicates “No Flame Vote” when any of the following 9. Loss of reheat protection. conditions are present: 10. Both “EMERGENCY TRIP” (hard) push buttons are depressed simultaneously or the “MFT” (soft) push button is activated. 1) Less than two out of four oil scanners show flame on Elevation “A. 2) Two out of four light/heavy oil guns are “not proven” on Elevation “A” 11. Economizer inlet feed water flow low for more than ten seconds and loss of 3) Heavy oil header pressure is