E - Yanbu Boiler Training - Controls Student Training Presentation CLC.pdf

YANBU – BOILER CONTROLS TRAINING Bill Miller / Jack O’Rourke May, 2024 © 2024 GE Vernova and/or its affiliates. All rights reserved. YANBU SPSC - BOILER CONTROLS TRAINING © 2024 GE Vernova and/or its affiliates. All rights reserved Page 2 Presenters slide Bil...

YANBU – BOILER CONTROLS TRAINING Bill Miller / Jack O’Rourke May, 2024 © 2024 GE Vernova and/or its affiliates. All rights reserved. YANBU SPSC - BOILER CONTROLS TRAINING © 2024 GE Vernova and/or its affiliates. All rights reserved Page 2 Presenters slide Bill Miller Jack O`Rourke Chief Consulting Engineering Manager Engineer – GE Steam - Process Power - Boilers Engineering (Controls) © 2024 GE Vernova and/or its affiliates. All rights reserved Page 3 BOILER CONTROL SYSTEMS YANBU SPSC - BOILER CONTROLS TRAINING CLOSED⇒ LOOP⇒CONTROL⇒ Aȍaɱ ới ⇒ Cớȍʉṩớɱ SYSTEM⇒ ⁌CLC⁍ Rƽi ữɱ aʉjȍi ⇒ Cớȍʉṩớɱ ⇒⁌Cớȍʉṩớɱ ⇒ḕṩjуƽṯ ) Digital Control - Fuel (Start/Stop, BURNER MANAGEMENT Open/Close) SYSTEM (BMS) Boiler PROTECTION OPEN LOOP CONTROL Digital Control - (fans, pumps, air heaters, SYSTEM (OLC) isolation dampers, drain valves & vents) © 2024 GE Vernova and/or its affiliates. All rights reserved Page 4 Definitions (typical) Burner Management System Closed Loop Control (CLC) Open Loop Control System Designed to prevent operator A command to a device that The Open Loop (OLC) logic errors during startup/shutdown modulates to control to a provides remote and normal operation setpoint. i.e. the process manual/automatic control of “closes” the loop and readjusts the boiler auxiliary equipment the demand to the device after digital functions. the process changes.  YANBU SPSC - BOILER CONTROLS TRAINING CLOSED LOOP CONTROL SYSTEM (CLC) Analog Control Regulating Control (Control drives) © 2024 GE Vernova and/or its affiliates. All rights reserved. 6 YANBU SPSC - BOILER CONTROLS TRAINING Closed Loop Control System System Design Control Subsystems Controlled Equipment System Design Analog Control Designed for Remote Manual/Automatic Control DCS Based Control Operator Interface Control Closed Loop Control Definition (typical) A command to a device that modulates to control to a setpoint. i.e. the process “closes” the loop and readjusts the demand to the device after the process changes. © 2024 GE Vernova and/or its affiliates. All rights reserved Page 7  YANBU SPSC - BOILER CONTROLS TRAINING MAJOR BOILER CLC CONTROL LOOPS BOILER LOAD DEMAND FURNACE PRESSURE CONTROL FUEL & AIR FLOW CONTROL FEEDWATER CONTROL SEPARATOR STORAGE TANK LEVEL CONTROL STEAM TEMPERATURE CONTROL GAS RECIRCULATION FLOW CONTROL WINDBOX DAMPER CONTROL WARM-KEEPING CONTROL © 2024 GE Vernova and/or its affiliates. All rights reserved Page 8  YANBU SPSC - BOILER CONTROLS TRAINING CLC CONTROLLED EQUIPMENT - UNIT ID & FD FAN BLADE PITCH CONTROL FUEL CONTROL VALVES BOILER FEEDWATER DEMAND SH & RH SPRAYWATER CONTROL VALVES STARTUP SYSTEM CONTROL VALVES WINDBOX AIR DAMPERS WINDBOX TILTS GAS RECIRCULATION DAMPERS STEAM COIL CONTROL VALVES © 2024 GE Vernova and/or its affiliates. All rights reserved Page 9 FAN CONTROL Redundant pressure transmitters © 2024 GE Vernova and/or its affiliates. All rights reserved. 10  YANBU SPSC - BOILER CONTROLS TRAINING COMBUSTION AIR AND FLUE GAS OVERVIEW © 2024 GE Vernova and/or its affiliates. All rights reserved Page 11 YANBU SPSC - BOILER CONTROLS TRAINING COMBUSTION AIR AND FLUE GAS TRAIN A © 2024 GE Vernova and/or its affiliates. All rights reserved Page 12 YANBU SPSC - BOILER CONTROLS TRAINING FURNACE PRESSURE CONTROL MIMIC (ID FAN CONTROL) © 2024 GE Vernova and/or its affiliates. All rights reserved Page 13 YANBU SPSC - BOILER CONTROLS TRAINING FURNACE PRESSURE / ID FAN CONTROL © 2024 GE Vernova and/or its affiliates. All rights reserved Page 14  YANBU SPSC - BOILER CONTROLS TRAINING NFPA 85 –Furnace Block A shows the requirements for three furnace pressure Pressure Control Functional transmitters arranged in an auctioneered median-select system, each Requirements on a separate pressure sensing tap. Block B shows the requirements for suitable monitoring to minimize the possibility of operating with a faulty furnace pressure measurement Block C shows a feed-forward signal to the furnace pressure control subsystem (D), which is a function of boiler airflow demand and is not based on a measured airflow signal Block D shows the furnace pressure control subsystem, which positions the furnace pressure regulating equipment so as to maintain furnace pressure at the set point Block E is Auto Manual Station Block F shows the requirements for a feed-forward override action initiated by a master fuel trip in anticipation of a furnace pressure excursion due to flame collapse and works in conjunction with logic that minimizes furnace pressure excursions Block G shows the requirements for a furnace pressure control protection subsystem, which is applied after the auto/manual transfer station (Block E) to minimize furnace pressure excursions under both, © 2024 GE Vernova and/or its affiliates. All rights reserved Page 15 auto and manual operation modes YANBU SPSC - BOILER CONTROLS TRAINING FURNACE PRESSURE / ID FAN CONTROL (Reference Drawing No. -1D8679) © 2024 GE Vernova and/or its affiliates. All rights reserved Page 16  YANBU SPSC - BOILER CONTROLS TRAINING Boiler Unit Airflow Control Mimic (FD Fan Control) © 2024 GE Vernova and/or its affiliates. All rights reserved Page 17 FUELS CONTROL Redundant pressure transmitters © 2024 GE Vernova and/or its affiliates. All rights reserved. 18 YANBU SPSC - BOILER CONTROLS TRAINING Combustion Control scheme which includes: Typical Combustion Control Diagram Cross limiting of fuel and air Cross limiting ensures that on a load increase, airflow leads Fuel flow. Cross limiting ensures that on a load decrease, fuel flow leads airflow. In the event equipment does not respond in the proper manner, for example, a fuel control valve does not respond to a demand decrease. In this case, the demand for unit Airflow is held based on the measured fuel flow. Minimum Aiflow demand equal to the Purge rate. O2 Correction is shown but is not connected to either the Airflow demand or the Airflow feedback. In the GE design , we choose to apply the O2 correction (or trim) to the Airflow Demand. © 2024 GE Vernova and/or its affiliates. All rights reserved Page 19 YANBU SPSC - BOILER CONTROLS TRAINING The purpose of the Fuel/Air demand logic is to maintain Combustion Control - Fuel/Air Demand (Reference Drawing No. -1D8668) proper, efficient fuel/air ratios in both automatic and manual modes. The Boiler Master demand provides the uncorrected demand for both fuel and air. Combustion optimization is achieved through automatic adjustment of unit air flow demand in response to measured flue gas O2. The setpoint to a PI oxygen controller is established from the greater of an Operator set low limit or a load dependent O2 curve. The O2 correction adjusts unit air flow demand so as to maximize combustion efficiency by maintaining excess air at an optimum value. The greater of the resulting air demand, minimum unit air flow or total corrected fuel flow serves as the setpoint to an air master controller. On the fuel side, the Boiler Master demand, limited by actual measured air flow, (adjusted by O2 control action described above) provides the total unit fuel demand. When firing Main Gas as the primary fuel, actual measured light oil & heavy oil flow are subtracted from this demand and yields the required Gas flow and corresponding setpoint to the Main Gas Flow controller. When firing light oil or heavy oil as the primary fuel, actual measured gas flow is subtracted from this demand and yields the required Oil flow and corresponding setpoint to the Oil Flow controllers. © 2024 GE Vernova and/or its affiliates. All rights reserved. 20 YANBU SPSC - BOILER CONTROLS TRAINING FUEL/AIR RATIO PROTECTION Combustion Control - Fuel/Air Demand (Reference Drawing No. -1D8668) As described under “FUEL/AIR DEMAND”, the demand to the air master can never be less than the total measured fuel flow, however, if the air master is not in remote setpoint, this protection is in effect “disconnected”. A second circuit monitoring the actual operating fuel/air ratio activates a FD fan demand limit/increase ramp function in the event of an excessive fuel/air ratio providing continued protection in manual and local setpoint modes. The ramp function includes automatic rate adjustment based on the number of FD fans in service to provide consistent response with varying equipment (fan) status. This function is not active in the event of a high furnace pressure condition, where furnace pressure FD fan directional blocking takes priority. As Oil and Gas elevations are located in adjacent compartments in each windbox, an alarm is provided to advise the Operator that the localized heat input is excessive. © 2024 GE Vernova and/or its affiliates. All rights reserved. 21 YANBU SPSC - BOILER CONTROLS TRAINING Combustion Control – Manual Fuel/ Air Ratio Protection, Localized Heat Input Exceeded (Reference Drawing No. -1D8668) FUEL/AIR RATIO PROTECTION As described under “FUEL/AIR DEMAND”, the demand to the air master can never be less than the total measured fuel flow, however, if the air master is not in remote setpoint, this protection is in effect “disconnected”. A second circuit monitoring the actual operating fuel/air ratio activates a decrease in fuel demand until the high ratio is cleared. On the Air side, after a one minute time delay and in the event that ratio has not cleared, the FD fan demand is increased slowly. This excessive fuel/air ratio provides continued protection in manual and local setpoint modes. The ramp function includes automatic rate adjustment based on the number of FD fans in service to provide consistent response with varying equipment (fan) status. This function is not active in the event of a high furnace pressure condition, where furnace pressure FD fan directional blocking takes priority. The logic is based on NFPA 85 paragraph 6.6.5.3.2* which states that if an air deficiency develops while flame is maintained at the burners, the fuel shall be reduced until the air/fuel ratio has been restored to within predetermined acceptable limits; if fuel flow cannot be reduced, the airflow shall be increased slowly until the air-fuel ratio has been restored to within those limits. As Oil and Gas elevations are located in adjacent compartments in each windbox, an alarm is provided to advise the Operator that the localized heat input is excessive. © 2024 GE Vernova and/or its affiliates. All rights reserved. 22  YANBU SPSC - BOILER CONTROLS TRAINING Simplified Unit Airflow Control (typical) 7 Feedforward for ID fan control for 1 Boiler demand large changes comes in 7 Secondary controller 2 Error between for number of fans in boiler demand service and steam flow 3 Feedforward for large changes 8 Operator Setpoint to limit fan 4 O2 Correction 9 Directional Blocking if ID does not respond 5 Greater of O2 and furnace pressure corrected, total hi corrected fuel flow and min air flow 6 Setpoint error created with feedforward 11 Fuel Air protection to prevent fuel rich conditions © 2024 GE Vernova and/or its affiliates. All rights reserved Page 23  YANBU SPSC - BOILER CONTROLS TRAINING Boiler Fuel and Airflow Control Station © 2024 GE Vernova and/or its affiliates. All rights reserved Page 24 YANBU SPSC - BOILER CONTROLS TRAINING Unit Airflow Control (Cont.) The O2 controller controls the appropriate amount of excess air for the combustion process. O2 is measured in the Economizer outlet duct. air. © 2024 GE Vernova and/or its affiliates. All rights reserved Page 25 YANBU SPSC - BOILER CONTROLS TRAINING Simplified Unit Airflow Control – O2 Correction (typical) © 2024 GE Vernova and/or its affiliates. All rights reserved Page 26 YANBU SPSC - BOILER CONTROLS TRAINING FIRING SYSTEM ARRANGEMENT Gas is introduced to each of eight (8) windboxes. Three (3) elevations of gas spuds are provided; each admission point has two (2) pipe ignitors and a dedicated gas flame scanner. Oil is also introduced to each of eight (8) windboxes. Four (4) elevations of oil HEA Ignitor guns are provided; each Fireball Scanner with a dedicated Class 3 Fireball and Special Electric Ignitor and Discriminating Flame a dedicated oil flame Scanner scanner. Twin IFM Pipe Ignitor © 2024 GE Vernova and/or its affiliates. All rights reserved Page 27 YANBU SPSC - BOILER CONTROLS TRAINING Ignitor Gas Header P&ID 1E8532 © 2024 GE Vernova and/or its affiliates. All rights reserved. 28 YANBU SPSC - BOILER CONTROLS TRAINING Simplified Ignitor Gas Pressure Control (typical) (Reference Drawing No. -1D8670)  Two Ignitor Gas header pressure control valves are provided to maintain the desired ignitor gas header pressure.  The valves are positioned by a single PI controller that responds to the error between measured ignitor gas header pressure as compared to a predetermined setpoint.  Redundant pressure transmitters are provided to indicate Ignitor Gas Header Pressure  In addition to the pressure control shown, the ignitor gas control valve demand is subject to a second overriding control action initiated in response to an ignitor gas header leak test. In this case, the valve will be commanded to open by the BMS during a leak test prior to Ignitor gas firing. © 2024 GE Vernova and/or its affiliates. All rights reserved. 29 YANBU SPSC - BOILER CONTROLS TRAINING IGNITOR GAS CONTROL STATIONS © 2024 GE Vernova and/or its affiliates. All rights reserved Page 30 YANBU SPSC - BOILER CONTROLS TRAINING Natural Gas System Ignitor gas P&ID 8352 Refer to high resolution PIDs in file: E - Yanbu Boiler Training - Controls Student Manual Attachment 4 Boiler PIDs 5-16-24 © 2024 GE Vernova and/or its affiliates. All rights reserved. 31 YANBU SPSC - BOILER CONTROLS TRAINING Natural Gas System Main Gas P&ID 8352 Refer to high resolution PIDs in file: E - Yanbu Boiler Training - Controls Student Manual Attachment 4 Boiler PIDs 5-16-24 © 2024 GE Vernova and/or its affiliates. All rights reserved. 32 YANBU SPSC - BOILER CONTROLS TRAINING Simplified Main Gas Flow Control (typical) 6 prevents low pressure trips 3 Actual Flow Calc 7 BMS override for trips 4 HHV set point Controller (delta demand to actual) 8 Cross limit to prevent persistent fuel rich 1 Setpoint demand 2 restricted by comes in (includes number of burners O2 trim) in service 9 Valves start opening sequentially according to demand © 2024 GE Vernova and/or its affiliates. All rights reserved. 33 YANBU SPSC - BOILER CONTROLS TRAINING MAIN GAS CONTROL STATIONS © 2024 GE Vernova and/or its affiliates. All rights reserved Page 34 YANBU SPSC - BOILER CONTROLS TRAINING Heavy Fuel Oil System P&ID Return Oil Flow through eight corner downcomers Returned to oil heaters ring header collection Oil is distributed through a ring header Four elevations of Heavy Fuel Oil via Triple Redundant eight corner risers High and low range pressure transmitters control valves © 2024 GE Vernova and/or its affiliates. All rights reserved. Refer to high resolution PIDs in file: E - Yanbu Boiler Training - Controls Student Manual Attachment 4 Boiler PIDs 5-16-24 35  YANBU SPSC - BOILER CONTROLS TRAINING Simplified Heavy Fuel Oil Flow Control (typical) (Reference Drawing No. -1D8672) flow Return flow deducted Prevents low pressure nuisance trips Zeros flow if no burner in To Pressurize service the circuit Remote demand comes in Delta setpoint 4 HHV set point to actual Prevents persist fuel > air Valve Demand Controller restricted by number of burners in service © 2024 GE Vernova and/or its affiliates. All rights reserved. 36 YANBU SPSC - BOILER CONTROLS TRAINING HEAVY FUEL OIL CONTROL STATIONS © 2024 GE Vernova and/or its affiliates. All rights reserved Page 37 YANBU SPSC - BOILER CONTROLS TRAINING Heavy Fuel Oil System P&ID 1E8518 Eight corner risers distributed to each oil corner through a ring header Triple redundant Triple redundant Temperature Pressure Transmitters Transmitters Steam Header Pressure Control Valve Refer to high resolution PIDs in file: E - Yanbu Boiler Training - Controls Student Manual Attachment 4 Boiler PIDs 5-16-24 © 2024 GE Vernova and/or its affiliates. All rights reserved. 38  YANBU SPSC - BOILER CONTROLS TRAINING Atomizing Steam Header Pressure Control (Reference Drawing No. -1D8713) © 2024 GE Vernova and/or its affiliates. All rights reserved Page 39 YANBU SPSC - BOILER CONTROLS TRAINING Light Fuel Oil System P&ID 1E8518 Ring Header Distribution Redundant pressure transmitters Single elevation “A” single control valve Refer to high resolution PIDs in file: E - Yanbu Boiler Training - Controls Student Manual Attachment 4 Boiler PIDs 5-16-24 © 2024 GE Vernova and/or its affiliates. All rights reserved. 40 YANBU SPSC - BOILER CONTROLS TRAINING Simplified Light Fuel Oil Flow Control (typical) © 2024 GE Vernova and/or its affiliates. All rights reserved. 41 YANBU SPSC - BOILER CONTROLS TRAINING LIGHT FUEL OIL CONTROL STATIONS © 2024 GE Vernova and/or its affiliates. All rights reserved Page 42 FEEDWATER CONTROL YANBU SPSC - BOILER CONTROLS TRAINING FEEDWATER CONTROL OVERVIEW © 2024 GE Vernova and/or its affiliates. All rights reserved Page 44  Conceptual Response Comparison Between Drum Type and Once Through Supercritical Boiler both Units Operating Above Control Load DRUM UNIT – CHANGE IN FEEDWATER FLOW DOES NOT CHANGE STEAM FLOW DOES NOT CHANGE STEAM TEMPERATURE Response To a Change In Feedwater Flow © 2024 GE Vernova and/or its affiliates. All rights reserved Page 45  Conceptual Response Comparison Between Drum Type and Once Through Supercritical Boiler both Units Operating Above Control Load ONCE THROUGH UNIT – AN INCREASE IN FEEDWATER FLOW INCREASES STEAM FLOW DECREASES STEAM TEMPERATURE ONCE THROUGH UNIT – A DECREASE IN FEEDWATER FLOW DECREASES STEAM FLOW INCREASES STEAM TEMPERATURE Response To a Change In Feedwater Flow © 2024 GE Vernova and/or its affiliates. All rights reserved Page 46  Conceptual Response Comparison Between Drum Type and Once Through Supercritical Boiler both Units Operating Above Control Load DRUM UNIT- AN INCREASE IN FUEL & AIR FLOW -- INCREASES STEAM FLOW -- DECREASES STEAM TEMPERATURE FOR STEAM FLOW NEAR MCR -- INCREASES STEAM TEMPERATURE FOR STEAM FLOW NEAR CONTROL LOAD Response To an Increase In Fuel & Air Flow © 2024 GE Vernova and/or its affiliates. All rights reserved Page 47  Conceptual Response Comparison Between Drum Type and Once Through Supercritical Boiler both Units Operating Above Control Load ONCE THROUGH UNIT– AN INCREASE IN FUEL & AIR FLOW DOES NOT CHANGE STEAM FLOW INCREASES STEAM TEMPERATURE Response To an Increase In Fuel & Air Flow © 2024 GE Vernova and/or its affiliates. All rights reserved Page 48  Conceptual Response Comparison Between Drum Type and Once Through Supercritical Boiler both Units Operating Above Control Load DRUM & SUPERCRITICAL UNITS – AN INCREASE IN SPRAY WATER FLOW INCREASES STEAM FLOW DECREASES STEAM TEMPERATURE Response To an Increase In Spray water Flow © 2024 GE Vernova and/or its affiliates. All rights reserved Page 49 YANBU SPSC - BOILER CONTROLS TRAINING FEEDWATER CONTROL Feedwater Demand (Reference Drawing No. -1D8679) The demand for feedwater satisfies the following objectives:  Develops a total unit feedwater demand as required to support unit load.  Adjust feedwater demand to maintain desired SH Hanger Tube outlet temperature.  Adjust SH Hanger Tube outlet temperature setpoint as required to maintain acceptable platen superheat spray control range.  Incorporate separator storage tank level (wet mode) feedwater demand.  Maintain minimum required economizer inlet flow. © 2024 GE Vernova and/or its affiliates. All rights reserved Page 50 YANBU SPSC - BOILER CONTROLS TRAINING SIMPLIFIED FEEDWATER CONTROL OVERVIEW (TYPICAL)  In this design, all of the boiler fluid sections progress from subcritical-pressures to supercritical pressures as the boiler load ramps from no load to full load. Feedwater demand is greater of four control  The fluid pressure within the signals boiler is not a control variable. The fluid temperatures and flows within the boiler are controlled. Redundant measurements © 2024 GE Vernova and/or its affiliates. All rights reserved Page 51  YANBU SPSC - BOILER CONTROLS TRAINING FW SETPOINT HIGHEST OF FOUR CONTROL SIGNALS The two modes the Supercritical boiler operates in are: a Controlled Circulation Mode and a Once Through Mode. As mentioned previously, Feedwater demand is greater of four control signals. In the Once Through Mode, all the flow into the economizer flows out of the superheater. There is no recirculation. There is no flow into the Flash Tank. The fluid at the water wall outlet is superheated steam or supercritical fluid. The boiler is operated in the Controlled Circulation mode from no load to a load equal to the minimum Economizer inlet flow. The Yanbu units are designed for a minimum Economizer inlet flow of 35%. This minimum flow is necessary to provide satisfactory cooling of the furnace wall tubes, to avoid circuit flow instability and avoid flashing and steaming in the economizer. When the steam generated in the boiler is less than the minimum Economizer inlet flow, water from the water walls outlet is circulated back to the feedwater system. In the Controlled Circulation mode, the quantity of recirculated water is regulated to maintain the minimum Economizer inlet flow through the Economizer and water walls. re-circulating the boiler water. is to use a boiler circulation © 2024 GE Vernova and/or its affiliates. All rights reserved pump with a flow control valve to return the water to the Page 52 Economizer inlet as shown here.  YANBU SPSC - BOILER CONTROLS TRAINING MINIMUM FW FLOW DEMAND WITH CIRCULATION PUMP ON – IMPLEMENTED AFTER A/M/ STATION  Normally, when the boiler is started, the boiler circulation pump is in service, and the 5% Minimum Feedwater Flow Demand will be selected.  This value has been chosen to maintain sub-cooled water at the inlet of the Boiler Circulation Pump.  The Minimum Feedwater Flow Demand will be the Feedwater flow setpoint when the unit is being started and the water in the furnace walls is displaced by the steam being generated. © 2024 GE Vernova and/or its affiliates. All rights reserved Page 53  YANBU SPSC - BOILER CONTROLS TRAINING During startup and at low loads, level in the separator storage tank is maintained by adjustment of the feedwater demand SEPARATOR LEVEL CONTROL setpoint through a PI controller. In this mode, the demand for feedwater is developed in response to the error between average separator storage tank level and an Operator entered separator storage tank level setpoint. The Separator Storage tanks are acting like the steam drum on a subcritical boiler. The differential pressure representing the level in the separator storage tank is compensated by the average separator outlet pressure to calculate the separator storage tank level. The difference between the level setpoint and measured level are the input to level controller. The level set point is typically set by the operator to 50% of the level range. The controller output is limited to minimum Economizer inlet flow minus the characterized total fuel flow. The output of the level controller is summed with the characterized total fuel flow. The total fuel flow is characterized to form a signal that represents the amount of feedwater required to replace the feedwater being converted to steam. The lower of the minimum Economizer inlet flow or the summation of the level controller output and the characterized total fuel flow is the feedwater setpoint. © 2024 GE Vernova and/or its affiliates. All rights reserved Page 54  YANBU SPSC - BOILER CONTROLS TRAINING BOILER MASTER DEMAND Once a substantial amount of steam is being generated, the feedwater setpoint becomes the Boiler Master demand. This input is dominating when the unit is operating in the Once Through Mode. In the Once Through Mode, the steam flow will be greater than the minimum economizer inlet flow (35%). The time function included in this demand is used to slow down feedwater setpoint changes so that the feedwater flow changes can be coordinated with the heat release in the furnace due to changes in the heat input. © 2024 GE Vernova and/or its affiliates. All rights reserved Page 55  YANBU SPSC - BOILER CONTROLS TRAINING MINIMUM FW FLOW DEMAND WITH CIRCULATION PUMP OFF  At low loads, when the boiler circulation pump is not in service and the unit is being fired, the minimum Economizer inlet flow becomes the selected feedwater setpoint.  This ensures the minimum economizer inlet flow is maintained when the boiler circulation pump is off. © 2024 GE Vernova and/or its affiliates. All rights reserved Page 56  YANBU SPSC - BOILER CONTROLS TRAINING The last of the feedwater setpoints is the Fuel Flow. FUEL FLOW DEMAND  This control arrangement forces the feedwater demand to be equal to or greater than the Fuel Flow.  Because there is a tight coupling between ratio of the Fuel to Feedwater Flows and the steam temperature, a reduction in feedwater flow without a corresponding reduction in fuel flow would result in high steam temperatures. The fuel flow input is used to minimize the possibility of elevated steam temperatures. © 2024 GE Vernova and/or its affiliates. All rights reserved Page 57  YANBU SPSC - BOILER CONTROLS TRAINING FUEL FLOW DEMAND Next slide FUEL/FEEDWATER RATIO PROTECTION  The Boiler Master demand provides the demand to the firing system (fuel and air) and is the primary component of the feedwater master demand.  In automatic mode, the ratio between fuel and feedwater will only vary to the extent necessary to satisfy the temperature correction action applied to the feedwater demand.  The fuel/feedwater ratio protection logic provides overriding control of individual feedwater pump demands in the event of an excessively low fuel to feedwater ratio when not operating in automatic.  If activated, the circuit should limit/decrease feedwater demand at a predetermined ramp rate until the condition clears.  The ramp function should include automatic rate adjustment based on the number of feedwater pumps in service to provide consistent response with varying equipment (pump) status. © 2024 GE Vernova and/or its affiliates. All rights reserved Page 58  YANBU SPSC - BOILER CONTROLS TRAINING The Feedwater Demand Trim ONCE THROUGH FW FLOW TRIMS OVERVIEW Logic is shown in red. This logic becomes active in the once through mode only. The purpose is to bring the average SH Hanger Tube outlet temperature to a preset load dependent value and keep the total spray flow at 4% of the total superheater steam flow. It does this by modifying the Boiler Master Demand. It also modifies the Total Corrected Fuel Flow input signal to keep the Fuel Flow input signal from replacing the trimmed Boiler Master Demand as the selected feedwater demand. © 2024 GE Vernova and/or its affiliates. All rights reserved Page 59  YANBU SPSC - BOILER CONTROLS TRAINING ONCE THROUGH FW FLOW TRIM FOR SPRAY FLOW © 2024 GE Vernova and/or its affiliates. All rights reserved Page 60  YANBU SPSC - BOILER CONTROLS TRAINING A second controller acts on a load ONCE THROUGH FW FLOW dependent (indexed from Boiler Master TRIM FOR SH HANGER Demand) SH Hanger tubes outlet OUTLET TEMP temperature setpoint trimmed by the SH spray differential temperature controller output. This controller acts to adjust feedwater in response to firing system disturbances and the relatively fast effect they have on SH Hanger tubes outlet steam temperatures. The overall combined feedwater feedback control action is such that feedwater demand is responsive to changes in the overall unit heat transfer profile. © 2024 GE Vernova and/or its affiliates. All rights reserved Page 61  YANBU SPSC - BOILER CONTROLS TRAINING MINIMUM ECONOMIZER FLOW CONTROL MINIMUM ECONOMIZER FLOW CONTROL The Minimum Economizer Flow Control Valve is located at the discharge of the Boiler Circulating Pump (BCP) the combined action of the pump and control valve circulates water from the evaporator outlet back to the economizer inlet to maintain adequate Evaporator flow during boiler start-up and at low loads. MINIMUM ECONOMIZER FLOW CONTROL VALVE © 2024 GE Vernova and/or its affiliates. All rights reserved Page 62  YANBU SPSC - BOILER CONTROLS TRAINING MINIMUM ECONOMIZER FLOW The purpose of the MEFCV is to: CONTROL Maintain minimum economizer inlet and evaporator flow during the start-up phase of operation. Maintain minimum boiler circulating pump differential pressure which ensures that minimum pump flow is maintained as feedwater flow increases above the minimum economizer flow setpoint. The control logic establishes a demand for this recirculation control valve based on measured economizer inlet flow as compared to a minimum boiler flow setpoint. When the boiler is operating in the Controlled Circulation Mode and the Boiler Circulation pump is in service, the minimum economizer flow control valve (MEFCV) is controlled to maintain the minimum Economizer inlet flow. All the feedwater flows into the mixing piece along with the water flowing out of the water walls. The check valve noted is closed in this operating mode. The difference between the measured economizer inlet flow and minimum economizer inlet flow setpoint is the input to the MEFCV position controller. The minimum position demand to the MEFCV position is limited to a fixed value to protect the pump from operating at a low flow condition. The pump differential pressure and pump inlet temperature are used to calculate the operating pump head. For pump protection, the difference between the operating pump head in feet of water and the maximum pump head setpoint is input to a controller that sets the minimum output of the MEFCV position controller. © 2024 GE Vernova and/or its affiliates. All rights reserved Page 63  YANBU SPSC - BOILER CONTROLS TRAINING SEPARATOR/STORAGE TANK - P&ID 1E8507 © 2024 GE Vernova and/or its affiliates. All rights reserved Page 64  YANBU SPSC - BOILER CONTROLS TRAINING SEPARATOR/STORAGE TANK - P&ID © 2024 GE Vernova and/or its affiliates. All rights reserved Page 65  YANBU SPSC - BOILER CONTROLS TRAINING SEPARATOR STORAGE TANK - In addition to the Separator/Storage Tank level control mentioned HIGH LEVEL CONTROL above, additional control valves are provided to remove excess water from the tanks which discharge the water to the flash tank. These valves are identified as High Water Level Valve-1 (HWL1) High Water Level Valve-2 (HWL2). HWL1 and HWL2 OPERATION The HWL1 and HWL2 valves are controlled in a split range manner to maintain the liquid level once the level reaches a high limit. High water level will occur during a cold start as the water is being displaced by the low density steam. The displaced water is drained from the boiler through the HWL valves to the flash tank and on to the condenser. High water level will also occur when the boiler recirculation pump is off during wet mode operation. In this case all the feedwater that is not evaporated into steam must be drained through the HWL valves. Tank geometry is such that fluctuations in tank level are very dynamic, for this reason, only proportional control action established through the HWL1/HWL2 function curves is used to position these valves in response to high tank levels. To protect the flash tank from over-pressurization, override action is provided to close the HWL1 valve in the event that the level in the separator storage tank is low and close the HWL2 valve if the level is low or the pressure in the separator is >170 barg. © 2024 GE Vernova and/or its affiliates. All rights reserved Page 66  YANBU SPSC - BOILER CONTROLS TRAINING Operation without Boiler Recirculation Pump Recirculation Mode without BRP Recirculation flow of 35% provided by BFPM All drain flow goes to condenser If condenser not available, alternate destination for drain flow required Operating Envelope without BRP Heat and water losses are higher Recirculation flow supplied by BFPM Evaporator flow = Feedwater flow in recirculation mode Higher water and fuel consumption Feedwater Evaporator flow = Steam flow in once-through Flow (FE1) Steam Flowmode Feedwater Flow (FE2) Drain Flow to Flash Tank Longer startup time 110 100 90 Recirculation Mode Once-through Mode Flow - % of Steam Generation 80 70 60 50 40 30 20 10 0 -30 -20 -10 0 10 20 30 40 50 60 70 80 90 100 110 Steam Generation - % © 2024 GE Vernova and/or its affiliates. All rights reserved Page 67  YANBU SPSC - BOILER CONTROLS TRAINING Operation without BRP - Firing Commences Operating Envelope with BRP Evaporator flow = BRP flow in recirculation mode Feedwater flow = Steam flow in recirc and once-through modes Evaporator Flow (FE1) Steam Flow Feedwater Flow (FE2) Drain Flow to Flash Tank 0% 110 100 90 35% Flow - % of Steam Generation Recirculation Mode Once-through Mode 80 70 0% 35% 60 35% 0% 50 40 30 20 0% 35% 10 0 -20 -10 0 10 20 30 40 50 60 70 80 90 100 110 35% Steam Generation - % © 2024 GE Vernova and/or its affiliates. All rights reserved Page 68  YANBU SPSC - BOILER CONTROLS TRAINING Operation without BRP - 20% Steam Flow 20% Operating Envelope with BRP Evaporator flow = BRP flow in recirculation mode Feedwater flow = Steam flow in recirc and once-through modes Evaporator Flow (FE1) Steam Flow Feedwater Flow (FE2) Drain Flow to Flash Tank 110 35% 100 90 Flow - % of Steam Generation Recirculation Mode Once-through Mode 0% 80 15% 70 35% 0% 60 50 40 30 0% 20 35% 10 0 -20 -10 0 10 20 30 40 50 60 70 80 90 100 110 15% Steam Generation - % © 2024 GE Vernova and/or its affiliates. All rights reserved Page 69 Operation without BRP - 35% Steam Flow 35% Operating Envelope with BRP Evaporator flow = BRP flow in recirculation mode Feedwater flow = Steam flow in recirc and once-through modes Evaporator Flow (FE1) Steam Flow Feedwater Flow (FE2) Drain Flow to Flash Tank 110 35% 100 90 Flow - % of Steam Generation Recirculation Mode Once-through Mode 0% 80 0%. 70 35% 0% 60 50 40 30 0% 20 35% 10 0 -20 -10 0 10 20 30 40 50 60 70 80 90 100 110 0% Steam Generation - % © 2024 GE Vernova and/or its affiliates. All rights reserved Page 70  YANBU SPSC - BOILER CONTROLS TRAINING Warmkeeping System Line Valve Control Warmkeeping System Control 1. During the Once Through Operating mode, the circulation line from the mixing piece to a take off near the separator storage tanks outlet, the HWL valves and piping from the HWL valves inlet to the take off are kept warm using water from the economizer outlet. 2. When wet-to-dry transfer is complete, the Water Storage Downcomer Isolation valve will be closed and all recirculation flow is stopped. Piping from the warming line take-off on the upper section of the Water Storage Downcomer to this valve, and the piping from the warming line take-off to both HWL1/HWL2 valves, is maintained in a warm condition by feedwater flowing from the economizer outlet through the warm-keeping system piping. 3. With this warm-keeping system operating, the differential pressure from high point tap on the separator storage tank to the low tap on the recirculation downcomer is controlled by the warm keeping control valve. This valve is controlled in response to measured differential pressure as compared to an Operator entered setpoint. 4. The flow between the three warming paths is equalized by a manual throttle valve in each path. 5. The warming water flows from the take off through the Warmkeeping Control valve (WKCV) and into the primary desuperheater. 6. The warming water flow is very small in comparison to the spray water flow so it has very little effect on the performance of the desuperheater. © 2024 GE Vernova and/or its affiliates. All rights reserved Page 71  YANBU SPSC - BOILER CONTROLS TRAINING Warming Line Valve Control Separator/Storage Tank (2) Flow to Platen DSH Warmkeeping Control Valve Bypass around Valve Orifices (3-4 Locations) Flash Tank Economizer Outlet Flow Feedwater Flow Dp © 2024 GE Vernova and/or its affiliates. All rights reserved Page 72 SUPERHEATER STEAM TEMPERATURE CONTROL  YANBU SPSC - BOILER CONTROLS TRAINING SUPERHEAT STEAM TEMPERATURE CONTROL SUPERHEAT STEAM TEMPERATURE CONTROL - GENERAL (Reference Drawing Nos. -1D8704, 8705, 8706, 8707) Overall superheat steam temperature control is accomplished with adjustment of spray water control and manipulation of feedwater flow. Two sets of final spray water control valves act to maintain final superheater outlet steam temperature. Two sets of platen spray water control valves respond to maintain the final spray station differential temperature and feedwater flow is adjusted in response to platen spray station differential temperature. In the short term, final superheat temperature fluctuations are minimized by the fast acting final spray water control valves. In the long term, control action automatically re-adjusts steam temperature at each control point (evaporator/SH Hanger Tubes, platen & final) in response to changes in corresponding heat transfer rates. This approach provides a high level of disturbance rejection and ensures the superheat spray water control valves remain in control range by ultimately adjusting evaporator outlet steam conditions/heat transfer and consequently “fire side” heat passed to the superheat sections. © 2024 GE Vernova and/or its affiliates. All rights reserved Page 74  YANBU SPSC - BOILER CONTROLS TRAINING SUPERHEAT STEAM SYSTEM OVERVIEW For Superheat Spray control, two stages of SH spray are provided. 2nd stage The first stage of DSH spray stations are located at the inlet 1st 2nd of the Platen Superheater stage stage section. 1st stage The second stage of DSH spray stations are located at the Platen SH outlet and inlet to the Final SH section. Each stage of spray provides independently controlled parallel Desuperheater spray stations. Each Desuperheater spray station is provided with redundant spray control valves with redundant DSH inlet and outlet thermocouples. © 2024 GE Vernova and/or its affiliates. All rights reserved Page 75  YANBU SPSC - BOILER CONTROLS TRAINING FINAL SUPERHEAT STEAM OVERVIEW SV ERV ERV SV ERV ERV Final SH Heat Transfer Surface © 2024 GE Vernova and/or its affiliates. All rights reserved Page 76  YANBU SPSC - BOILER CONTROLS TRAINING PRIMARY SPRAYWATER CONTROL page 1/2 The section in red shows the Platen Desuperheater control logic and the purpose of the Platen superheat WITH TWO STAGES OF DESUPERHEAT spray water control valves is to keep the final superheat spray water control valves in their desired operating range. Master Controller The control structure is a cascade arrangement where the master controller acts on the differential temperature Fuel Feedforward measured across the corresponding final superheat spray station as compared to a load dependent differential temperature setpoint. The output of this controller represents the required temperature entering the platen superheat section to achieve the desired temperature at platen outlet (i.e. corresponding final spray station inlet). An “over/under firing” feedforward is added to the master controller’s output for improved response. This signal is developed by comparing the rate of change in steam flow to the rate of change in fuel flow. Over firing (rate of change in fuel flow in excess of rate of change in steam flow) decreases the master Differential Temp CV Platen SH across final Desup controller output. This is an anticipatory action to offset the tendency for increased steam temperatures resulting from a temporary imbalance between cooling (steam flow) and available heat (firing rate) when over © 2024 GE Vernova and/or its affiliates. All rights reserved Page 77 firing.  YANBU SPSC - BOILER CONTROLS TRAINING PRIMARY SPRAYWATER CONTROL page 2/2 When under firing (increases master controller’s output) WITH TWO STAGES OF DESUPERHEAT since in this case the temporary cooling/heat imbalance tends to decrease steam temperatures. The resulting modified master output provides the setpoint to a slave Master controller. The slave controller acts on this setpoint as Controller compared to steam temperature measured at the spray stations outlet (i.e. inlet to platen superheat section). Fuel Feedforward Saturation protection is provided by limiting the spray control valve demand. The saturated steam temperature value, derived from measured separator outlet pressure plus 50C, establishes the minimum permissible temperature at t