steam and boiler

What is the most common steam trap used?

A. Thermostatic

How often should safety valves on low pressure boilers be tested by hand according to ASME code?

A. Once a month

Where does excess fuel oil in the fuel oil system return to?

B. Fuel oil tank

What is a pressure gauge that reads more pressure than is actually in the boiler called?

D. Fast

Which of the following actions will make a boiler work more efficiently: I. more fuel is added; II. fire tubes are decreased in size; III. the heating surface is increased?

C. II & III only

What causes false water level readings in the gauge glass?

B. Foaming

What is the purpose of the safety valve?

A. Prevent the pressure in the boiler from exceeding its MAWP.

What device shuts off the burner in the event of low water?

B. Low water fuel cut-off

Which type of boiler does not use tubes?

A. Cast iron sectional

What is the range of pressure on the vacuum switch?

B. 2 to 8 in.

What must be opened to prevent a vacuum when taking the boiler off-line?

B. Boiler vent

What is the range of the pressure gauge relative to the MAWP of the boiler?

C. 1½ to 2

How does the thermostatic steam trap operate?

D. Flexible bellows

What type of safety valve is only allowed on a boiler according to ASME code?

B. Spring-loaded pop-type

What maintains a constant water level in the boiler?

D. Feedwater regulator

How often should the low water fuel cut-off be tested?

A. Daily

Before entering the boiler’s furnace, fuel oil must be what?

C. Atomized

The safety valve is designed to pop open and remain open until there is a pressure drop of how many psi?

C. 2 to 4

What is the MAWP on a low pressure steam boiler?

C. 15

What controls the operating range of the boiler?

B. Pressure control

In the float thermostatic trap, the float rises to discharge what?

A. Condensate

Where is the water column located in relation to the NOWL?

A. 2 to 3 in. above the highest surface.

What type of pump supplies water to the condensate return tank?

A. Vacuum

What is the blowback of a safety valve intended to prevent?

C. Chattering

When steam loses its heat in a heat exchanger, it turns into what?

C. Condensate

Where should the feedwater stop valve be located?

C. As close to the shell of the boiler as practical.

What is termed when a safety valve opens and closes rapidly?

B. Chattering

What prevents live steam from entering the Bourdon tube of the pressure gauge?

D. Siphon

What causes blade erosion in a steam turbine?

B. Due to droplets in steam

Water tube boilers are preferred for what?

A. High pressure and high output

What causes the maximum energy loss in the boiler?

B. Flue gases

What is added to a boiler to turn water-forming salts into non-adhering sludge?

D. Chemicals

Which valve opens and closes automatically in a feedwater system?

B. Check

What is the pressure range of a supercritical boiler?

D. 225 to 250 bar

What type of boiler is the Benson boiler?

D. No drum

What occurs after the steam has lifted the safety valve off its seat?

A. Huddling chamber

What is the differential pressure setting required if the desired cut-in pressure is 6 psi and cut-out pressure is 10 psi?

C. 4

When does the safety valve on a low pressure boiler open?

B. 15 psi

In what order does flue gas flow in the steam power plant layout?

A. Superheater, economizer, air preheater

What position should the operator switch be in to test the vacuum pump?”,

D. Continuous

Where should the boiler bottom blowdown line discharge?

C. Blowdown tank

What pressure gauge can read vacuum pressure?

A. Compound

Which valve must be used as the boiler main steam stop valve?

D. OS&Y gate (outside screw and yoke)

What is the purpose of compounding steam turbines?

B. Reduce turbine speed

What happens to steam temperature as pressure increases?

C. Increases

What does the ASME code state regarding safety valves on boilers with over 500 square feet of heating surface?

D. Must have two or more safety valves.

What issue can occur with condensate in steam lines?

D. Water hammer

What does a liquid boil when its vapor pressure equals?

B. The ambient pressure.

What process is used when turbines experience excessive moisture?

A. Reheating

Which cycle has the highest efficiency at a given set of operating pressure limits?

D. Regenerative cycle.

In a condensing steam engine, what is condensed?

D. Exhaust steam.

What is the primary reason regeneration results in higher efficiency in a Rankine cycle?

C. Average temperature of heat addition increases.

What happens when employing superheated steam in turbines?

B. Decrease in erosion of blading.

What happens to exhaust temperature as the load decreases in a gas turbine plant?

D. Decreases.

Why is the superheat Rankine cycle more efficient than the simple Rankine cycle?

B. The mean temperature of heat addition is higher.

What is the lower limit on condenser pressure based on?

D. Temperature of cooling water.

What is a common term for upgrading an existing plant by adding equipment?

B. Repowering.

What is the reason for compounding steam turbines?

B. To reduce the speed of rotor.

How does regeneration in a Rankine cycle improve efficiency?

C. Higher average temperature of heat addition.

What improvement does single reheat provide in a modern power plant?

A. 4 to 5% increase in efficiency.

In a two-phase system, what does 30% moisture signify?

B. 70% vapor and 30% liquid.

Which line shows the steam consumption relationship with load in a turbine-generator?

C. Willan’s line.

What aspect of a condenser ascertains its effectiveness?

D. Heat transfer.

What defines properties of a superheated vapor?

B. A superheated table.

What is flow through the nozzle considered?

A. Isentropic.

What is the nozzle inlet velocity if the reservoir is sufficiently large?

D. Zero.

What is defined as simultaneous production of electricity and steam?

D. Cogeneration.

What type of liquid is above saturation temperature at its pressure?

A. Compressed liquid.

Which device lowers air temperature as it passes through?

A. Air cooler.

At what rpm do steam turbines generally operate in power stations?

A. 3000 rpm.

What refers to critical properties in thermodynamics?

C. Property values where liquid and gas phases are indistinguishable.

If a substance’s temperature is less than its saturation temperature, it is a what?

A. Subcooled liquid.

What causes an increase in fluid velocity through nozzles with respect to enthalpy?

A. Decrease in static enthalpy of fluid.

What describes the Rankine efficiency in a steam power plant?

C. Rankine efficiency.

What temperature occurs when water and vapor coexist at atmospheric pressure?

B. Steam point.

What is typically done to the system when excessive moisture is present in a turbine?

C. Reheating.

What does the cut-off ratio in a steam engine describe?

D. Fraction of piston stroke traveled when cut off occurs.

What defines the isentropic efficiency of a turbine?

A. The ratio of actual to ideal energy extracted.

What happens to mass flux through a converging-diverging nozzle with increased stagnation pressure?

C. Increases.

At steam point, how are the temperatures of water and vapor related?

C. In equilibrium.

What is the primary advantage of a reheat Rankine cycle?

A. Reduced moisture content in L.P. side of turbine.

How can the average temperature of heat rejection be decreased in a Rankine cycle?

D. Reduce turbine exit pressure.

What modification approaches the efficiency of the Carnot cycle in a Rankine cycle?

C. Regenerative feed heating by steam.

In what order does the flue gas flow travel?

A. Super-heater, economizer, air pre-heater, precipitator.

In a combined gas-vapor cycle, what is the thermal efficiency compared to a steam or gas turbine cycle?

A. Greater than.

When the boiler pressure increases, what happens to moisture levels?

A. Increases.

What is the process of removing non-condensable gases in steam cycles called?

B. Deaeration process.

Which steam turbine has both fixed and moving blades identical?

C. Parson’s reaction turbine.

In an impulse turbine, where does steam expand fully?

A. Nozzle.

In reaction turbines, what defines a stage?

A. Each row of blades.