單項選擇題The diesel engine exhaust gas bypass, as fitted with some waste heat boilers, is installed to （）

A.prevent engine back pressure at heavy loads
B.increase total engine efficiency at low loads
C.prevent boiler corrosion at low engine loads
D.improve engine fuel consumption at any load


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1.單項選擇題The fuel oil supply system to an automatic auxiliary boiler, will automatically shutdown if the boiler （）

A.steam demand is high
B.salinity is high
C.safety valve simmers
D.burner flame is extinguished

2.單項選擇題Flame failure in an automatically fired auxiliary boiler can from a/an （）

A.incorrect electrode setting
B.incorrect nozzle position
C.clogged fuel nozzle
D.broken high tension lead

3.單項選擇題In the event of a flame failure in an auxiliary water-tube boiler, you must（）

A.relight the boiler immediately to prevent loss of steam pressure
B.relight the fire off the brickwork as the bricks are cherry red
C.purge the furnace of any combustible gases before attempting to relight the fire
D.speed up the feed pump to prevent dry firing when the burner flame is reestablished

4.單項選擇題The purpose of a temperature sensing device installed in the stack of a small automatically fired auxiliary steam boiler is to secure the oil burner（）

A.in the event of a flame failure
B.in the event of a stack fire
C.when the water level reach the crown sheet
D.when the feed pump discharge pressure drops to a preset minimum

5.單項選擇題Burner ignition failure in an automatically fired auxiliary boiler would be caused by（）

A.a burned out solenoid in the oil supply valve
B.high temperature excess air
C.incorrectly setting the hot-well dump valve
D.an incorrectly positioned burner snubber realy