2Nd Class Fireman, High Pressure Boilers, Chapter 9, Notecards

- An automatic boiler control system that regulates fuel supply, air supply, air-fuel ratio, and draft in a boiler in order to deliver the required amount of steam to a load

- provides control through the burner management system by determining when to fire and how much fuel to burn in order to produce enough steam for the loads while maintaining the pressure at the setpoint

- takes control of a boiler after the burner management system completes a firing cycle.

A modulating control strategy that uses steam pressure as the input signals and outputs one signal to a fuel valve to modulate the fuel flow and another signal to a variable-speed blower motor or to an air damper to modulate the airflow

- A master controller that calculates and distributes steam production requirements across several boilers to maintain the steam pressure at the setpoint.

- it tells the boiler how much steam to produce.

- An ON/OFF Control with an adjustable differential that regulates the operating range of the boiler between the cut-in pressure and the cut-out pressure by opening and closing electrical contacts.

Sighting the main flame through a flame scanner to verify that the main flame is lit

A modulating control strategy that uses steam pressure as the input signal and outputs a signal to a modulating motor that turns a jackshaft to modulate the air and fuel flow

A control strategy in which increases in airflow lead increases in fuel flow, and decreases in air flow lag behind decreases in fuel flow

- A combustion control system that is used to adjust the firing rate to a degree that is proportional to the steam load through the use of PLC or digital control system.

- can be used instead of a modulating pressure control device on newer or larger boilers.

- can also start or stop the burner automatically by using an operating pressure control.

A combustion control system in which the flow of fuel and air are measured and adjusted in correct proportions based on steam pressure

- A safety device that uses a flame sensor to sense whether a flame is present and sends a signal to the burner management system whether it’s safe to operate the boiler.

- proves the pilot to allow the firing cycle to continue when steam demand initiates the combustion cycle.

- it does not allow the fuel valve to open if the scanner does not prove the pilot or main flame. This prevents fuel from entering the furnace of the boiler and building up when the burner is not lit.

- according to the book, tested at least once a week.

A motor controller used to vary the frequency of the electrical signal supplied to an AC motor in order to control its rotational speed

- A combustion control strategy that is used to start and stop a burner without any modulation of the flame.

- can be used in plants where the steam load is steady and allows the burner to be started and stopped.

- A situation where the pilot or main flame fails to light properly or goes out unintentionally during normal operation.

- The burner management system must be manually reset to re-initiate the start cycle.

An ON/OFF control with a manual reset that sends a signal to the combustion control system to shut down the burner in the event of a high pressure condition that exceeds the operating pressure control cut-out setting

A predetermined period of time during which air is blown through the furnace to remove any combustible vapors

- The sensing device in the flame scanner that senses the pilot and main flame in the burner.

- A system programmed for automatic burner sequencing and flame supervision

- responsible for managing the purging operations and firing cycles of a burner

- provides for the direct connection of pressure controls, safety and operating interlocks, the combustion blower motor, the modulating motor, the flame ignition system, valves, and alarms

- checks the boiler for errors.

- controls the operation and sequence of the startup.

- common checks and procedures used by this system include pre-ignition checks, purge cycles, lighting the pilot, lighting the main flame, and postpurge during shutdown.

- Sighting the pilot through a flame scanner to verify that the pilot is lit.

A pressure control device that provides local control of the firing rate proportional to the steam pressure

A control strategy used to adjust the air-fuel ratio of a burner according to the results from a flue gas oxygen analyzer

A purge that occurs after burner shutdown

An audible electronic alarm that alerts the operator of an operating condition that needs immediate attention

A device that controls the flow of liquid, gas, or electrical current. Also known as a control device.

The ratio of the maximum firing rate to the minimum firing rate.

- a diagram of a system telling how it works.

A picture of what’s going on with the boiler. It’s a computerized version (on a computer screen).

A device in a flame scanner that generates a small amount of electrical current when exposed to ultraviolet light.

- a device in a flame scanner that generates a small amount of electric current when exposed to visible light.

- the current indicates to the burner management system that a flame is present.

- A sensing device in a flame scanner that generates a small electric current when one end of the sensor is placed directly in a flame.

- older technology and rarely used today.

After proving the pilot, the main fuel valve is opened to allow fuel to enter the furnace where it is ignited by the pilot.

A purge that occurs before a burner is allowed to fire.

- A device in a flame scanner that generates a small amount of electric current when exposed to infrared light.

- this current indicates to the burner management system whether a flame is present.

A combustion control strategy that senses the steam pressure and sends a control signal to start and stop the burner to maintain the steam pressure.

Air system.