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154 Cards in this Set
- Front
- Back
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Explain ultimate analysis and proximate analysis.
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Ulitimate analysis determines the precentage of various elements present NOCASH
Proximate determines teh amount of moisture, volatile matter, fixed carbon and ash. |
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How is a water column installed on a boiler?
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Located at the NOWL, the lowest visible part of guage glass is 2 to 3" above boilers highest heating surface on a fire tube boiler, and 2" above the lowest permissable water level according to manufactures specifications on a watertube boiler
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What is the purpose of the continous blowdown heat recovery system?
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Prevents heat losses thorugh blowdown of solids from the boiler water. Heat is reclaimed first by dropping pressure on the boiler water so that the flash steam can be reclaimed, then heating makeup water with the blowdown water. Connected to the steam and water drum well below the low water level.
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What is Total dissolved solids?
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Solids that circulate with the water ina boiler. The soids are formed by the combining of chemicals used in the boiler water treatment process and help removeforeign matter from teh boiler.
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What is Dry Pipe?
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It's main function is to improve the quality of outgoing steam. It is found in teh steam and water drum on some boilers.
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What is the purpose of Scrubbrs?
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Remove the moisture and solids from the steam Scrubbers are essential on boilers equipped with superheaters. They are located in the steam and water drum of watertube boilers.
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What are the harmful effects of scale on the heating surface of a boiler?
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leads to overheating of the boiler metal, resulting in blisters, bags, and possible tube rupture or boiler explosion.
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How do you install a steam pressure gauge on a boiler?
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Range must be 1 1/2 to 2 times greater than the safety valve popping pressure. Must be visible and protected from heat and cold. A siphon must be installed to protect the Bourdon tube from live steam. 1/4 inch brass or copper pipe for temps up to 405°F. Steel and wrought iron must be 1/2" thick. Shut off valves should be lever-handle cock or OS&Y gate valves that show their position when open or closed.
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What is the function of the air injector?
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Removes air and noncondensable gases from the surface condenser to help maintain a high vacuum.
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Define centrifugal force in reference to steam turbine.
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Centrifugal force and centripetal force can be seen in a steam turbine. Centrifugal force is the force that pulls the blades or bucets away from the rotating shaft Centripetal force is the force exerted inward toward the rotating hsaft opposite of centrifugal force.
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What is the purpose of a throttling calorimeter in a steam plant?
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Used to measure the amount of moisture in teh steam. Once the quality of steam has been determined , the total heat per pound of steam can be found. This figure, boiler thermal efficiency can be found.
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What happens when to similar centrifugal pumps are connnected in series, what happens to the discharge pressure and flow?
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The pressure doubles. This arrangement is the same as having a two-stage pumping unit. The volume through each pump remains the same.
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What types of boilers are equipped with waterwalls?
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normally watertube boilers
they help in pulverized coal boiler because of the high heat release furnaces. |
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What is the purpose of waterwalls?
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Prolong the life of the furnace refactory and also add to the heating surface of the boiler.
1sqft = 16lb of steam/hr |
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What is boiler heat balance?
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Boiler heat balance involves accounting for all the heat available in a fuel.
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What is a Atmospheric(relief) valve?
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Prevents pressure buildup on the exhaust side of a reciprocating steam engine or steam turbine. Located on themain exhaust line or attached to the top of a surface condenser as close to the exhaust line as possible.
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What is a Nonreturn valve?
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Found on boiler main steam line. Located as close to the boiler shell as practical. Cuts the boiler in on-line automatically, cuts the boiler offline automatically, and protects the system from draining if one boiler fails.
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What is a Slide valve?
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Simple D type slide valve used on reciprocating steam pumps and engines.
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What is a relief valve?
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Spring-loaded valve used to relieve pressure preventing excessive pressure.
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What maintenance is required to keep a boiler in good condition?
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-Keep it tight prevent air leaks
-Maintain proper FDWTR temp to reduce thermal shock -Set controls so burners run for longer periods than it is off protecting refractory from spalling due to cooling -Test boiler feedwater daily and carefully control chemicals. -Use a soot blower to keep tubes clean. -All valve packing should be replaced as necessary to prevent leakage. -Lubricate valve spindles with a mixture of graphite and oil for easy opening and closing. |
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What are the steps to parallel two AC generators?
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-Adjust voltage to line voltage with field rheostat
-Frequency of both turbo-generator should be the same. -Synch using synchroscope. -When hand stops close breaker. -Increase the load on the unit that just came online. |
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How is thermal efficiency affected when steam is bled from various stages to heat feedwater?
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Raises the thermal efficiency of the steam turbine. feedwater regains the latent heat that would be lost in the condenser.
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Why do firetube boilers require stays?
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FT Boilers have extensive flat surfaces. Forces acting on a flat surface tend to act in one direction that does not happen on a curved surface.
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What is prefect combustion?
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Burning all fuel supplied to the boiler usining only a theoretical amount of air.(only possible in a laboratory, never in actual plant operation.
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What is Complete combustion?
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The burning of all the fuel supplied to the boiler using minimum amount of air.
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What is Incomplete Combustion?
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fuel supplied is not burned resulting in soot and smoke.
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Why do staybolts have holes drilled in the ends?
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warnt he operator if the bolts have sheared or corroded. water will come out of the telltale hole of the staybolt indicating it has failed.
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What is the diameter and depth of the drilled holes?
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The hole drilled in the end is 3/16" in diameter and must extend at least 1" itno the water side of the boiler.
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What is the best time to blowdown a waterwall on a watertube boiler?
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They are never blown down until the furnace has cooled down. Furnace temps(2500) waterwall blowdown valves should be kept locked at all times.
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What is a two-element feedwater regulator?
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Used on boilers with load changes(process plant). One is the rise and fall of the waterlevel in the boiler. The other is the steam flow fomr the boiler.
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How are expansions and contractions compensated for in the steam lines?
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Expansion bends. Expansion joints are also used to allow for expansion and contraction of main steam lines in the plant.
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IAW ASME code where must the blowdown line and valve be located on a firetube boiler?
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Lowest part of the water side.
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IAW ASME code where must the blowdown line and valve be located on a watertube boiler?
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lowest part of the mud drum.
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Which boilers require more than two bottom blowdown valves?
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boilers carrying greater than 100psi
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What is the kingsbury thrust bearing?
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Is found on the low pressure end of the turbine shaft.It is used to take up the thrust formed as steam passes through the steam turbine blades to maintain proper axial clearancee between the stationary and moving blades.
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How are boile tubes connected to drums of watertube boilers?
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Boiler tubes are rolled and expanded i nwtertube boilers.
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How are boiler tubes connected to tube sheets in firetube boilers?
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In firetube boilers , boiler tubes are expanded in the tube sheet and then the ends are beaded over to prevent the tube ends from burning.
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What effect does an increase in firing rate have on the superheater outlet steam temperature?
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In convection superheater the temp raises. In a radiant superheater the steam temperature decreases.
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What effect does the ON/OFF operation of a boiler have on boiler maintenance and boiler life?
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Results in increased maintenance.
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Heating value is determined by?
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Ultimate Analysis
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In steam tables, heat in liquid (h) equals?
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boiling point in °F -32
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Scale buildup in a superheater causes?
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Superheater tubes to overheat
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____results in a high 02 reading in gases of combustion?
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incomplete combustion
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Keeping gases of combustion in the air heater at a temperature higher than dew point of gases of combustion, it is possible to____?
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prevent corosion
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An_____is located on the inlet line of a steam turbine condenser?
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atmospheric relief valve
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Sodium sulfite used in boiler drum reduces____?
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oxidation of metal
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Plant efficiency can be increased when____steam is used to heat boiler feedwater?
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exhaust
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An econimizer uses heat from___to heat feedwater?
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gases of combustion
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Safety valves are rated_____
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in pounds of steam per hour at a given pressure
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Flyash and soot are removed fro gases of combustion going up the chimney by____?
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electrostatic precipitators
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Bituminous coal requires large amounts of overfire air because it has a____content.
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high volatile
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A(n)_____is used to reduce pulsation and maintain a constant pressure on the discharge side of a reciprocating pump.
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air chamber
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A chain grate stoker most commonly burns coal with a___content.
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high ash
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The amount of moisture in saturated steam can be detemined by using a(n)___.
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throttling calorimeter
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_____is the comparison of heat energy(entalpy) supplied to the steam turbine to heat energy used by the steam turbine.
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thermal efficiency of the steam turbine
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When burning pulverized coal, a____temperature must be maintained.
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high furnace
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____air is supplied to a furnace controls the rate of combustion.
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primary
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Degrees API refers to____of fuel oil.
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density
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New boilers and boilers that have had extensive repair work done on the steam or waterside should have a(n)____test preformed?
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hydrostatic
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A(n)______test is preformed on a boiler to check the operation of the low water fuel cutoff by allowing the water level in the boiler to drop slowly.
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evaporation
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A____governor is used on a steam turbine where close control of RPM is required.
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hydraulic
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_____is/are used to prevent leakage between stages of steam turbine blades.
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labryinth packing
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ASME code dictates that a boiler pressure gauge should have a range of two times tthe safety valve setting, but not less than___the safety valve setting?
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1 1/2 times
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In a jet condenser____.
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water and steam mix
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If the staybolt diameter is doubled, the holding power will____.
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quadruple
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The intensity of heat is measure____.
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with a thermometer
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Two boilers with the same capacities are operating at 300psi and 600psi. respectively. The approximate ratio of the areas of their safety valves is____.
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2:1
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Steam turbines are comonly designed to have steam velocity____times as great as blade velocity.
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2
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Axial thrust in a steam turbine is controlled by a
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any of the above
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A(n)______test is preformed on a boiler to check the operation of the low water fuel cutoff by allowing the water level in the boiler to drop slowly.
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evaporation
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A____governor is used on a steam turbine where close control of RPM is required.
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hydraulic
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_____is/are used to prevent leakage between stages of steam turbine blades.
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labryinth packing
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ASME code dictates that a boiler pressure gauge should have a range of two times tthe safety valve setting, but not less than___the safety valve setting?
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1 1/2 times
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In a jet condenser____.
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water and steam mix
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If the staybolt diameter is doubled, the holding power will____.
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quadruple
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The intensity of heat is measure____.
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with a thermometer
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Two boilers with the same capacities are operating at 300psi and 600psi. respectively. The approximate ratio of the areas of their safety valves is____.
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2:1
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Steam turbines are comonly designed to have steam velocity____times as great as blade velocity.
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2
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Axial thrust in a steam turbine is controlled by a
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any of the above
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A sudden increase in chimney temperature with no increase in firing rate indicates____.
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broken baffles on the fire side
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If the feedwater temperature is increased without a change in the firing rate, the steam____.
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flow will increase
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The output of two similar centrifugal pumps connecte in parallel is___?
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constant pressure, double volume
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The maximum size a bottom blowdown valve on a boiler is___".
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2.5
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A thermo expansion feedwater regulator operates on
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expansion and contraction of a thermostatic element
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A boiler explosion is more likely in a(n)___-boiler.
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HRT
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Failure to properly purge a boiler after ignition failure could lead to___.
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a furnace explosion
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Scale buildup on a boiler heating surfaces is cause by___.
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improper fedwater treatment
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The minimum size connection between the gauge glass and water colum is____"?
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1/2
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A dry pipe in the steam and water drum____.
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improves steam quality
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A sudden increase in chimney temperature with no increase in firing rate indicates____.
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broken baffles on the fire side
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If the feedwater temperature is increased without a change in the firing rate, the steam____.
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flow will increase
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The output of two similar centrifugal pumps connecte in parallel is___?
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constant pressure, double volume
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The maximum size a bottom blowdown valve on a boiler is___".
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2.5
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A thermo expansion feedwater regulator operates on
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expansion and contraction of a thermostatic element
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A boiler explosion is more likely in a(n)___-boiler.
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HRT
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Failure to properly purge a boiler after ignition failure could lead to___.
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a furnace explosion
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Scale buildup on a boiler heating surfaces is cause by___.
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improper fedwater treatment
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The minimum size connection between the gauge glass and water colum is____"?
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1/2
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A dry pipe in the steam and water drum____.
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improves steam quality
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A sudden increase in chimney temperature with no increase in firing rate indicates____.
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broken baffles on the fire side
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If the feedwater temperature is increased without a change in the firing rate, the steam____.
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flow will increase
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The output of two similar centrifugal pumps connecte in parallel is___?
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constant pressure, double volume
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The maximum size a bottom blowdown valve on a boiler is___".
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2.5
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A thermo expansion feedwater regulator operates on
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expansion and contraction of a thermostatic element
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A boiler explosion is more likely in a(n)___-boiler.
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HRT
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Failure to properly purge a boiler after ignition failure could lead to___.
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a furnace explosion
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Scale buildup on a boiler heating surfaces is cause by___.
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improper fedwater treatment
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The minimum size connection between the gauge glass and water colum is____"?
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1/2
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A dry pipe in the steam and water drum____.
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improves steam quality
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To blow down a boiler equipped with a quick-opening and slow-opening valve on the bottom blow line, the____.
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quick-opening valve is open firt and closed last
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The main purpose of the water column on a boiler is to
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reduce the turbulence of water in the gauge glass
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A___is a device used to remove soot deposits from around tubes and to premit better heat transfer in the boiler.
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soot blower
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Two or more safety valves are required on a boiler____.
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with over 500sq ft of heating surface
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A steam trap blowing steam into the condesate line can cause____.
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lower plant efficiency
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_____ is carryover of water from a boiler to the main steam line
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Priming
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The main function of a condenser is to____.
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decrease the steam turbine water rate
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A____ is a larege auxiliary device where air moves upward to mix with falling water, resuliting in coooing of water.
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cooling tower
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A____ is commonly used to measure furnace pressure.
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manometer
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Furnace refractory life will be extended if the furnace is equipped with____.
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waterwalls
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Boilers in battery must have two main steam stop valves and a fre-blowing drain between them if the boilers are equipped iwth____.
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manhole openings
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When the temperature of condenser cooling water increases with no increase in volume, the vacumm___.
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decreases
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The maximum velocity of water in feedwater lines is limited to____.
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550 ft/min
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___ is the process where the water level in a boiler momentarily drops with a decrease in steam demand.
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Shrink
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The continuous blowdown line is located____.
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in the steam water drum well below the NOWL
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Water in deaerator feedwater heater is prevented from entering the steam line by a(n)____.
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loop seal or internal overflow
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An overspeed trip on a steam turbine that operates at 3600 RPM would activate at____RPM.
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3960
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The btu content of natural gas is 100,000 btu/therm
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100,000 btu/therm
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The ASME code recommends that the low water fuel cutoff be tested by an evaporation test____.
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monthly
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A lead sulfite cell detects___.
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a burner pilot and main flame.
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When warming up a boiler, the air cock should be closed when____.
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boiler pressure gauge reads about 15 to 25psi
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Waterwall tubes_____.
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increase boiler heating surface
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Extra-heavy pipe must be used on blowdown lines when the steam pressure is over____.
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125psi
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The only type of safety valve allowed by the ASME code on a boiler is a___ safety valve
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spring-loaded pop-type
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As the steam pressure in a boiler increases, tehre is a coreesponding increase in the____.
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temperature of steam and water
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The maxiumum velocity of water i feedwater lines is limited to____.
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500 ft/min
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To determine the total dissolved solids in suspension ni boiler water, a(n)___-meter is used.
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conductivity
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Most furnace explosions are caused by___.
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failure to purge the furnace at startup
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The overseped tripping device on a steam turbine must be tripped when____.
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shutting down the steam turbine
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An accumulation test is used to determine____
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safety valve relieving capacity
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Fuel oil with high viscosity____than fuel oil with low viscosity
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is harder to pump
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As much as ____lb of water are required to condesne 1 lb of steam, depending on ambient air temperature and cooling water temperature.
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50
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When heating feedwater with exhaust steam or gases of combustion, there is a 1% increase in plant efficiency for every____°f increase in feedwater temperature.
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10
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If valves are installed between the boiler and water column, they must be___.
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os&y or lever-type, locked or chained open.
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The volatile content of coal is the portion composed of____
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gaseous or liquid combutible elements
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The pressure at the bottom of the tank___.
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Increase as teh heigh of the water level increases.
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Operating with an economizer tube leak can lead to:
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large amounts of make-up flow, plugging of the economizer hoppers, reduced
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___law states that when pressure of a gas is constant, the volume of the fas has a direct relationship with its absolute temperature.
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charles
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The negative plate in an electrochemical cell is called the___
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cathode
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it is the___that causes the fluid to flow
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difference in pressure.
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Axial thrust isa force that
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results fro the effects of rotation.
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A lantern ring is used on pumps to distribute____.
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sealing water around the pump shaft
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Unbalanced, misalignment, and bad bearings in rotating equpiment are common causes of____.
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vibration
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The amount of steam used by a steam turbine, in pounds per horsepower hour, is called teh
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water rate
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The use of one fluid to transport another uses the principal of
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entrainment
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