BurnerMate Universal Industrial
The BurnerMate Universal Industrial offers a patented metering fuel-air ratio combustion control technique using a unique control strategy referred to as “Predictive Metering”. The ideal combustion control strategy is one that maintains a preset fuel-air ratio over the entire load range of a boiler despite changes in fuel supply, combustion air and draft conditions, and also provides rapid load change response.
Fully Metered combustion control is now available “off the shelf” in an economical, pre-engineered, parameter-driven control package.
The BurnerMate Universal Industrial includes the following features:
- Patented “Predictive Full Metering” fuel-air ratio control
- Cross-limited Actuator “Position Pacing”
- Single PID fuel-air ratio tuning
- Air flow temperature compensation
- Gas flow pressure compensation
- Windbox O2 FGR Trim + Flue O2 Air Flow Trim
The BurnerMate Universal Industrial also includes all of the features in the Basic and Expanded versions of BMU:
- Precise high torque Servo Actuators (3 ft-lb -> 720 ft-lb, 8 sizes)
- FD, ID & FGR Fan and BFW Pump VFD drive control
- NFPA 85 compliant Burner Management System (BMS)
- Individual Interlock Annunciation with advanced Lockout Data storage
- Low Fire Fuel Changeover
- Firing Rate, Feedwater and Draft control
- Oil Atomizing Pressure control with Setpoint Curve
- Large 10” color Touch Screen OIT with pre-programmed graphics (Note: 15” also available on custom applications)
- Modbus communications
Predictive Metering Combustion Control: The BurnerMate Universal Industrial offers a patented metering fuel-air ratio combustion control technique using a unique control strategy referred to as “Predictive Metering”. The ideal combustion control strategy is one that maintains a preset fuel-air ratio over the entire load range of a boiler despite changes in fuel supply, combustion air and draft conditions, and also provides rapid load change response.
Traditional Fully Metered combustion control systems have the following weaknesses:
- Two PID loops are required, making tuning difficult
- Cross Limiting Lead-Lag causes Air Rich operation during Load changes
- Sluggish response to load changes due to PID and Cross Limiting Lead-Lag interactions
- Air Flow meter inaccuracies at low flow rates limit Burner turndown capabilities
- Flow meter malfunctions disable the burner, or require manual operation until repaired
- Until now, Fully Metered control systems were “custom” so their benefits were not available “off the shelf”
Preferred’s patented “Predictive Metering” combustion control strategy combines multiple fuel, air, and FGR ‘as-commissioned’ feedforward curves (which predict Servo/VSD changes during a load change), with measured flow rate based PID fuel-air ratio control that incorporates a robust Cross-Limited Position Pacing algorithm. Predictive metering uses ‘as-commissioned’ measured fuel flow rate and air flow rate curves to ensure that the PID fuel-air ratio remains at the ‘as-commissioned’ fuel-air ratio setpoint for every firing rate.
Predictive Metering, combined with “Position Pacing” logic, assures much more precise Actuator positioning and assures that each servo remains “on curve” during load changes. This allows the controller to increase or decrease firing rate more quickly, without concern for “fuel rich” or “fuel lean” burner operation. These strategies are of particular importance when applied to sensitive low NOx burners with narrow limits of flammability.
Because “Predictive Metering” combustion control uses both the Servo Actuator position feedback and fuel and air flow meter inputs, metering combustion control can be selectively “turned” off at low firing rates where air flow meters may not be as accurate. Most importantly, if a flow meter malfunctions, by simple Parameter selection the BMU Industrial controller can be directed to operate as a Parallel Positioning combustion control system with Oxygen trim until the flow meter is repaired or replaced. Traditional Fully Metered systems can only be run in manual when there is a flow meter malfunction.
Because “Predictive Metering” is pre-programmed and only application-specific Parameter setup is required to make the controller functional, BurnerMate Universal Industrial is much easier to commission and operate than traditional Fully Metered combustion control systems. The single PID block (rather than the two required for traditional systems) requires that only one set of PID values need to be tuned during commissioning.
Inputs for “Predictive Metering” combustion control include:
- Combustion air flow
- Combustion air temperature
- Fuel 1 Oil flow (pulser or 4-20 mA)
- Fuel 2 (natural) gas flow
- Fuel 2 (natural) gas pressure**
- Fuel 3 (digester or other) gas flow**
**Note: The Fuel 3 Flow, Gas Pressure compensation, and Atomizing Pressure control transmitters all share a single BMU Industrial input. Only one of the three can be enabled (field selectable).
Fuel and Steam flows are also Totalized. Each of these flow rates and flow totals has a Modbus address for display on the local OIT Touch Screen or remotely via Modbus on Plant DCS system OITs.
BMU Industrial Fuel-Air-FGR Cross Limited Position Pacing:
“Position Pacing” is a unique feature of the BurnerMate Universal Industrial that assures the positions of all Fuel, Air, and FGR Servos and related VSD speeds remain “on curve” during load swings. Position pacing helps avoid:
- Periods of lean combustion that can cause rumbling, vibration, or flame-outs during firing rate increases
- Fuel rich conditions that can cause smoking, burn-back, and excessive CO or unburned hydrocarbons during firing rate decreases
With traditional Fully Metered control systems, the solution to these problems is to slow down the response to firing rate changes, and to tighten “cross limiting Lead-Lag” to assure that the fuel and air flows remain “on curve.” For such systems, it is not unusual for low to high fire response times to be 4-8 minutes.
BMU Industrial “Position Pacing” assures that all Servo Actuators remain “on curve” in the following manner:
- All fuel, air, FGR Servos and VSDs move together and “on curve” --there is no fuel or air “Lead” or “Lag”.
- Each Servo and VSD has precise position or speed feedback to insure that all devices are Cross Limited.
- The BMU Industrial “knows” how far each Servo Actuator and VSD can move in 0.5 seconds and uses “self-adaptive” Position Pacing to ensure that load changes never cause any Servo or VSD to lag behind the others.
- Εvery 0.5 seconds, the BMU Industrial examines all curves to “find” the Servo or VSD worst case 0.5 second ‘move’ caused by a requested firing rate change.
- Based on the curves, all other Servos or VSDs target positions are “scaled back” to assure ALL devices arrive “On Curve” at the end of the next 0.5 second move.
DOCUMENTS & DOWNLOADS
|BurnerMate Universal Industrial Boiler Controller Cutsheet (Catalog 25)|
|BurnerMate Universal Industrial-SPEC|
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