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单选题
Water evaporates or steam condenses at the saturation temperature, which depends upon the pressure, the higher the pressure （） the saturation temperature.
A
the more
B
the higher
C
the lower
D
the highest
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The fuel supply system to an automatic auxiliary boiler, will be automatically shutdown if the boiler()
A.salinity is abnormallyB.high steam demand is tooC.feed-water flow is lowD.water level is abnormally low
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The water level showing in a boiler water gauge glass is usually ( ) duringworking.A.higher than the actual drum water levelB.equal to the actual drum water levelC.increasing due to steam condensation in the glassD.lower than actual drum wafer level
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If the feed pump for an auxiliary boiler fails to deliver the feed water to the boiler, the cause may be ______.A.high steam pressure in the boilerB.abnormally high feed-water temperatureC.abnormally high boiler water temperatureD.steam demand exceeding feed pump capacity
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Steam smoke will occur when ______.A.extremely cold air from shore passes over warmer waterB.warm dry air from shore passes over cooler waterC.cold ocean water evaporates into warm airD.cool rain passes through a warm air mass
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Geothermal(地热)Energy
1 Since heat naturally moves from hotter regions to cooler ones, the heat from the earth's center flows outwards towards the surface. In this way, it transfers to the next layer of rock. If the temperature is high enough, some of this rock melts and forms magma(岩浆). The magma ascends in its turn towards the earth's surface. It often remains well below the earth's surface, creating vast areas of hot rock. In such regions, there are deep cracks, which allow rainwater to descend underground. Some of the heated rainwater travels back up to the earth's surface where it will appear as a hot spring. However, if this ascending hot water reaches a layer of impermeable(不可渗透的)rock, it remains trapped, forming a geothermal reservoir. If geothermal reservoirs are close enough to the surface, they can be reached by drilling wells. Hot water and steam shoot up the wells naturally, and can be used to produce electricity in geothermal power plants.
2.A few geothermal power plants depend on dry-stem reservoirs which produce steam but little or no water. In these cases, the steam is piped up directly to provide the power to spin a turbine generator. The first geothermal power plant, constructed at Lardarello in Italy, was of this type, and is still producing electricity today.
3.Most currently operating geothermal power plants are either "flash" steam plants or binary(双重的)plants. Flash plants produce mainly hot water ranging in temperature from 300° to 700°Fahrenheit. This water is passed through one or two separators where released from the pressure of the underground reservoir, it "flashes" or boils into steam Again, the force of this steam provides the energy to spin the turbine and produce electricity. The geothermal water and steam are then reinjected directly back down into the earth to maintain the volume and pressure of the reservoir. Gradually they will be reheated and can then be used again.
4.A reservoir with temperatures below 300° Fahrenheit is not hot enough to flash steam but it can still be used to generate electricity in binary fluid. The steam from this is used to power the turbines. As in the flash steam plant, the geothermal water is recycled back into the reservoir.
文章(23~30)
Paragraph1_____A.Dry steam plants
B.Binary plants
C.Origin of geothermal energy
D.Generation of electricity
E.Flash steam plants
F.Recyclable water and steam
考题
Paragraph4_____A.Dry steam plants
B.Binary plants
C.Origin of geothermal energy
D.Generation of electricity
E.Flash steam plants
F.Recyclable water and steam
考题
单选题The steam boiler is part of a closed loop steam, whereby, after the energy of the steam is used up and it becomes water again, （） is collected and returned back to the boiler for heating up again to steam.A
the formerB
the firstC
the latterD
the last
考题
单选题The heated feed-water entering any flash chamber of a flash-type evaporator will（）A
vaporize, with the un-flashed water remaining at the temperature at which it entered the flash chamberB
vaporize, with the un-flashed eater equalizing to the saturation conditions existing in the f lash chamberC
vaporize, with the remaining water a t a temperature greater than it entered the flash chamberD
boil, allowing steam bubbles to rise through the brine at the bottom of the flash chamber
考题
单选题What is NOT a function of the steam drum of a marine water-tube boiler（）.A
Receives saturated steam from the generating tubesB
Serves as a reservoir of boiler feed waterC
Holds internal fittings for separation of moisture from steamD
Collects steam exhausted from the turbines
考题
单选题In an auxiliary boiler steam and water system, the highest pressure will be in the （）.A
steam stop valveB
dry pipeC
feedwater systemD
generating tubes
考题
单选题Large pipes or （） are fitted between the steam and water drums to ensure good natural circulation of water.A
fire-tubesB
furnacesC
down-comersD
soot-blowers
考题
单选题When the boiler load returns to normal, the drum pressure will rise and steam bubble formation will reduce, causing a fall in water level This is known as （）.A
swellB
shrinkageC
flash offD
lack of water
考题
单选题The heated feedwater entering any flash chamber of a flash-type evaporator will（）A
vaporize, with the unflashed water remaining at the temperature at which it entered the flash chamberB
vaporize, with the unflashed water equalizing to the saturation conditions existing in the flash chamberC
vaporize, with the remaining water at the temperature greater than it entered the flash chamberD
boil, allowing steam bubbles to rise through the brine at the bottom of the flash chamber
考题
单选题A definite advantage of using water as a fire extinguishing agent is its characteristic of（）.A
alternate expansion and contraction as water in a liquid state becomes a vaporB
absorption of smoke and gases as water is converted from a liquid to a vaporC
rapid contraction as water is converted from a liquid to a vaporD
rapid expansion as water absorbs heat and changes to steam
考题
单选题The boiler feed pump discharge pressure is higher than the steam drum pressure to （）.A
ensure feed water flow into the boilerB
keep the steam drum pressure highC
prevent water hammer in the feed lineD
help the feed water flash to steam
考题
单选题Water level controllers of the boiler must be kept operable to protect external steam-using plant from water “（）” danger.A
carry offB
carry downC
carry onD
carry over
考题
单选题The water level in a steaming auxiliary boiler will always （）A
rise when the steam pressure is increasedB
remain constant as long as the feed pump operatesC
fall when the steam pressure is decreasedD
vary as the steam demand changes
考题
单选题The water level showing in a boiler water gauge glass is usually （） during working.A
higher than the actual drum water levelB
equal to the actual drum water levelC
increasing due to steam condensation in the glassD
lower than actual drum water level
考题
单选题Steam smoke will occur when（）.A
extremely cold air from shore passes over warmer waterB
warm dry air from shore passes over cooler waterC
cold ocean water evaporates into warm airD
cool rain passes through a warm air mass
考题
单选题（）, iea steam cooler, may be filled in the boiler system to control the superheated steam temperature.A
An economizerB
An attemperatorC
A water dramD
A down-comer tube
考题
单选题When steam is being raised on a boiler, the water level will normally （）.A
drop as the boiler warms upB
rise as the boiler warms upC
remain unchanged until the boiler is hot enoughD
rise and fall with the steam demand
考题
单选题In motorships，there are two main circuits, （）.A
one salt water, one fresh waterB
one salt water, one fuelC
one fresh water, one fuelD
one steam, one fuel
考题
单选题As for turbine oil, contact with water in the form of steam will be inevitable so good （） properties will be essential.A
defrostingB
de-oilingC
demulsifyingD
dehumidifying
考题
单选题Which of the listed types steam traps operates on the principle that hot water flashes to steam when its vapor pressure is rapidly reduced?（）A
Ball floatB
ThermostaticC
BimetallicD
Impulse
考题
单选题If the feed pump for an auxiliary boiler fails to deliver the feed water to the boiler, the cause maybe （）.A
high steam pressure in the boilerB
abnormally high feed water temperatureC
abnormally high boiler water temperatureD
steam demand exceeding feed pump capacity
考题
单选题Prior to lighting off a cold automatically fired auxiliary boiler, you should （）.A
check and regulate the water levelB
close the air cock once fires are litC
blowdown the gage glassD
crack the steam stop to assure protective steam flow
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