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73 Cards in this Set
- Front
- Back
A line desuperheater is used in conjunction with a ____ |
Pressure-reducing station |
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Some plants are equipped with a ____ instead of a blowdown tank |
Blowdown separator |
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If steam has a quality of ____ %, it is 98% vapor and contains 2% water |
98 |
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In a heat recovery system, the ___ regulates the flow of makeup water to the flash economizer |
Proportioning valve |
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A 10 degree Fahrenheit rise in feedwater temperature produces approximately ____ % savings in fuel |
1 |
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A throttling calorimeter is used directly to measure ____ |
Moisture content in steam |
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The flow of steam maintained through a superheater should never be less than ____ % of boiler capacity |
25 |
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When water is boiling, the water in the boiler and steam above it are at ____ |
The same temperature and pressure |
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Water hammer is caused by ____ and can lead to a line rupture |
Mixing steam and water |
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A steam trap usually has a ____ installed on the inlet line |
Steam strainer |
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Steam turbines require ____ steam |
Dry superheated |
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The air ejectors on the condenser of a steam turbine are used to remove air and other noncondensable gases from the ____ |
Condenser |
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Boilers operating at ____ psi or more are required to have two bottom blowdown valves mounted on the blowdown line |
100 |
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When ____ fills an inverted bucket steam trap, the bucket loses buoyancy and sinks to open the discharge valve |
Condensate |
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Failure to maintain steam flow will result in ____ superheater tubes |
Overheating of |
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Watertube boilers can be fitted with ____ to increase the heat content of the steam |
Superheaters |
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The bellows of a thermostatic steam trap is usually filled with a(n) ____ and water solution to increase the sensitivity of the trap |
Alcohol |
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Although the condensate tank is vented, it is possible to have a pressure buildup caused by ____ |
Leaking steam traps |
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According to the ASME code, it the MAWP exceeds ____ psi, the blowdown lines and the fittings must be composed of materials suitable for the temperature and pressures allowed |
125 |
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A steam trap can be tested with a(n) ____ to determine if it is working properly |
Ultrasonic device |
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In large steam boiler plants, a(n) ____ is necessary to provide the extra capacity required to handle changing loads and peak flows of condensate |
Surge tank |
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A ____ steam trap is a steam trap that has a single movable disc that rises to allow the discharge of air and cool condensate |
Thermodynamic |
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The raw makeup water system generally has a float chamber located at the ____ water level in a surge tank |
Minimum |
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Transfer pumps are used to transfer the mixture of ____ from a surge tank to the deaerator or directly to the boiler feedwater pumps |
Condensate and raw makeup water |
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A blowdown valve is located ____ of the water side of a firetube boiler or the mud drum of a watertube boiler. |
At the lowest part |
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A ____ cools down the blowdown water and steam to protect sewer lines from the high pressure and temperature of the blowdown water. |
Blowdown tank |
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A blowdown heat recovery system is equipment that reclaims heat that is normally lost during the ____ blowdown process. |
Continuous |
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Steam ____ is the ratio of dry steam to the total amount of water evaporated |
Quality |
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A superheater is located in the ____ or in the direct part of the gases of combustion |
Radiant zone (furnace area) or in the convection section of the boiler |
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____ steam turbines use steam velocity as a force acting in a forward direction on a blade mounted on a wheel |
Impulse |
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____ steam turbines must use a large amount of the available exhaust steam to maintain maximum efficiency. |
Noncondensing |
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A steam trap removes ____ from steam lines, increasing the overall efficiency of a steam plant |
Air and condensate |
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A steam trap that is stuck open will ____ |
Cause steam to blow through. |
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Do firetube boilers have superheated steam? |
No |
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What is the steam called that leaves the drum? |
Saturated steam |
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What type of steam do turbines require? |
Superheated steam |
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Every 35 degrees of superheated steam adds how much plant efficiency? |
1% per 35 degree increase |
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Why is there a superheater safety valve? |
To prevent damage to the tubes by keeping a flow of steam through the tubes at all times. |
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What are the three primary categories of steam traps? |
Mechanical, thermostatic, thermodynamic |
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Name 4 popular steam traps: |
1: float steam trap 2: thermostatic steam trap 3: inverted bucket steam trap 4: thermodynamic disc steam trap |
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Explain why a steam trap is installed in a boiler. |
A steam traps prime mission is to remove condensate and air while preventing the escape of live steam from the distribution system. |
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Explain what is a superheater. |
A superheater is a device that is used to convert saturated steam into superheated steam. It is placed in the path of hot flue gases from the furnace. Superheaters are classified as convection, radiant, or combination of these. |
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What does a free blow drain inform you of? |
It lets you know when the non-return valve is open. |
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Saturation temperature is the temperature at which _____ |
water and steam are at the same pressure |
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A superheater is a bank of tubes through which steam passes _____ |
after leaving the boiler where additional heat is added to the steam |
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A consistent steam temperature during fluctuations in load can be maintained using _____ |
both radiant and convection superheaters in the same unit |
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A superheater safety valve must be of sufficient capacity to relieve _____ % of the steam that the boiler can produce |
25 |
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The flow of steam through a superheater should never be less than _____ % of boiler capacity |
25 |
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In an average steam turbine, there is a gain of about _____ % in efficiency for every 35 degree Fahrenheit of superheat. |
1 |
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Noncondensing steam turbines are normally used in steam plants that require large amounts of ______ |
low-pressure process or heating steam |
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Condensing steam turbines are commonly used on medium to large units and operate with an exhaust pressure of _____ vacuum |
26 in. Hg to 29 in. Hg |
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To produce the force in an impulse steam turbine, a _____ is located before each stage |
nozzle |
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Most steam turbines are designed to have a steam velocity that is ____ |
twice as great as the blade velocity |
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_____ is a method in which the energy from steam is extracted using multiple stages in a turbine to reduce the steam velocity and pressure in a short time. |
velocity compounding |
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The temperature drop across a steam trap is called _____ |
subcooling |
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Most thermostatic steam traps operate with _____ subcooling |
20 degrees Fahrenheit to 40 degrees Fahrenheit |
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Float thermostatic steam traps are used generally in plants with pressures up to _____ psi |
125 |
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A(n) ____ steam trap has no condensate backup |
inverted bucket |
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Bimetallic steam traps normally operate with _____ subcooling |
50 degrees Fahrenheit to 100 degrees Fahrenheit |
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If steam is allowed to enter a return line, it can result in a loss of _____ |
plant efficiency |
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With the sound method, a ____ can be used to test steam traps. |
mechanic's stethoscope |
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The latest method of testing steam traps uses a sensor fitted inside a sensing chamber to detect the presence of steam or condensate by measuring its _____ |
conductivity |
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Condensate tanks and pumps are installed at the _____ |
lowest points in each building where steam is being used |
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A pressure buildup in a condensate tank is prevented by a(n) _____ |
atmospheric vent line |
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In a larger steam boiler plant, a surge tank is vented to the atmosphere and is equipped with a(n) ____ for cleaning and repairs. |
manhole |
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_____ are used to transfer the mixture of condensate and raw makeup water to the deaerator or directly to the boiler feedwater pumps. |
transfer pumps |
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In a raw makeup water system, a float operates a makeup water valve to maintain the ____ in the tank. |
minimum water level |
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Some plants are equipped with a _____ instead of just a condensate return tank. |
Condensate surge tank |
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Saturated steam is ______ |
In equilibrium with water at the same temperature and pressure. |
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The two parts of a bimetallic element expand and contract differently when exposed to changes in ______ |
Temperature |
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Superheater tubes are protected from warping or burning out by ______ |
A continuous flow of steam. |
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A desuperheater is an accessory used to _____ to make it suitable for a process. |
Remove heat from superheated steam. |
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Some _____ moisture separators automatically open and close because they use a wax that expands and contracts with temperature changes. |
Variable orifice |