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Chapter 9
Combustion and Boiler Controls
| Question | Answer |
|---|---|
| The primary function of a combustion control system is to regulate the ? in a boiler a. fuel supply b. air supply c. draft d. all of the above | d. all of the above |
| On/Off control is used to start and stop a burner a. and modulate the flame to match steam load b. without modulating the flame to match steam load c. based on the measured fuel flow d. based on the measured draft | b. without modulating the flame to match steam load |
| A siphon is used to protect an operating pressure control from a. live steam b. water c. air d. gas | a. live steam |
| An operating pressure control must be connected to the ? a. main steam line b. main feedwater line c. highest part of the steam side of the boiler d. water side of the boiler below the NOWL | c. highest part of the steam side of the boiler |
| The two settings found on the boiler operating pressure control are used to ? a. set the operating steam pressure range of the boiler b. eliminate low water c. maintain high and low fire d. warn the operator of flame failure | a. set the operating steam pressure range of the boiler |
| The combustion blow continues to run after fuel is shut off to the boiler during ? a. postpurging b. prepurging c. synchronization d. ignition | a. postpurging |
| The programmer is an On/Off control system used to ? a. control the burner firing cycle b. control the boiler operating range c. sure the burner in the event of low water d. regulate the flow of steam | a. control the burner firing cycle |
| To eliminate the danger of a furnace explosion during startup, the programmer must allow ? a. main flame ignition b. proving of the main flame c. a prepurge period d. a varying steam load | c. a prepurge period |
| The purpose of the flame sensor in a flame scanner is to prove ? a. only the pilot b. only the main flame c. both the pilot and the main flame d. the proper boiler water level | c. both the pilot and the main flame |
| A flame sensor is sensitive to ? a. heat b. temperature c. pressure d. infrared, or ultraviolet light | d. infrared, or ultraviolet light |
| In the event of a a flame failure, the programmer ? a. automatically goes through a new firing cycle b. shuts the burner down c. vents the fire tubes d. starts the induced draft fan | b. shuts the burner down |
| A modulating control system is sensitive to changes in the ? a. boiler water b. firing rate c. steam flow d. steam pressure | d. steam pressure |
| An ? is a controller that distributes steam production requirements across several boilers to maintain steam pressure at the setpoint a. plant master b. operating pressure control c. on/off control d. programmer | a. plant master |
| A preignition check includes ? a. verifying that the fuel pressure proving switch is closed b. lighting the pilot c. proving the pilot d. proving the main flame | a. verifying that the fuel pressure proving switch is closed |
| After a programmer proves the main flame it ? a. verifies the fuel pressure b. verifies airflow through the furnace c. releases to automatic control d. postpurges the furnace | c. releases to automatic control |
| If steam is being used faster than it is being generated the ? a. steam pressure increases b.steam pressure decreases c. combustion control closes the fuel valve d. combustion control closes the inlet damper | b. steam pressure decreases |
| A high-limit pressure control ? a. has a modulating controller b. uses a high/low/ off controller c. uses a differential pressure settings d. has a manual reset | d. has a manual reset |
| The flow of fuel though valves and air through dampers is usually? a. nonlinear b. linear c. not adjustable d. set at maximum | a. nonlinear |
| Single point positioning uses the ? as the controller input and has only one output a. fuel flow b. airflow c. steam pressure d. steam temperature | c. steam pressure |
| A low firing rate needs ? than at a high firing rate a. more excess air b. less excess air c. more single point positioning d. less single point positioning | a. more excess air |
| Parallel positioning uses steam pressure as the controller input and ? a. has on/off fuel flow b. bypasses the postpurge c. uses one output signal d. uses two output signals | d. uses two output signals |
| A modulating control system adjusts the firing rate proportional to the ? a. steam load b. amount of excess air available c. flue gas analysis d. water level | a. steam load |
| Nonlinear flow means that the percent a valve or damper is opens does not correspond to ? a. percent of flow b. controller output c. steam pressure d. water level | a. percent of flow |
| ? control increases safety by adding a linking system that prevents the airflow from going to low for the amount of fuel flow during load changes a. cross limited b. modulating c. single point postioning d. on/off with modulating | a. cross limited |
| ? is used to adjust the air fuel ratio based on the results of a flue gas analysis a. metering control b. burner management c. purging d. oxygen trim | d. oxygen trim |
Created by:
zmos89