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DC BOILER EXAM ACTUAL EXAM AND PRACTICE
EXAM LATEST 2024-2025 QUESTIONS AND
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DC BOILER EXAM ACTUAL EXAM
A ___ converts the energy from the expansion of high-pressure steam into the mechanical energy of rotation - ANSWER-turbine A ___ is a device that converts mechanical energy into electrical energy - ANSWER-generator Cogeneration is the process of ___ and then using the waste heat for heating buildings, providing process heat, or further electrical generation - ANSWER-generating electricity Food processing plants use steam for ___, pasteurization, and sterilization - ANSWER-cooking ___ is the production of electricity as a result of a conductor passing through a magnetic field - ANSWER-Electromagnetic induction ___ generators are the most common generators used to produce electrical power - ANSWER- AC
___ is often used as a prime mover that is used to rotate turbines to generate electricity - ANSWER-High-pressure steam Exhaust gases from engines and turbines pass through a heat exchanger to produce hot water or steam for use in plant heating or processes in ___ plants - ANSWER-combined heat and power (CHP) Steam that has lost its heat and has turned back into water is called ___ - ANSWER-condensate ___ are used for steam loads that require dry steam - ANSWER-Superheaters As steam is produced, its pressure is controlled, and ___ valves protect the boiler if the pressure control fails - ANSWER-safety A ___ can be installed at the point of use to reduce the steam pressure to the pressure needed for the load - ANSWER-pressure-reducing station A ___ is used to send condensate back to the condensate return - ANSWER-steam trap Feedwater flows into a boiler to be heated by ___. - ANSWER-gases of combustion
A shutoff valve is used when ___ - ANSWER-making repairs A stop valve and a check valve are located on the ___ line - ANSWER-feedwater On larger watertube boilers, a(n) ___ can heat the feedwater by using gases of combustion before the feedwater enters the boiler. - ANSWER-economizer Once fuel oil reaches the burner, it is the function of the burner to ___ the oil so it can mix with air and burn - ANSWER-atomize In a low-pressure gas system, the zero gas governor reduces the pressure of the gas to ___ psi. - ANSWER- 0 In a low-pressure gas system, the air and gas mixture in the furnace is ignited by the ___. - ANSWER-pilot A fuel oil relief valve protects a fuel system from excessive oil pressure and discharges to the ___. - ANSWER-fuel oil return line Modern coal plants use ___ coal that is blown into the combustion chamber where it burns in suspension. - ANSWER-pulverized
___ valves are typically slow-opening, fast-closing, hydraulic-electric valves and should have an internal proof-of-closure switch. - ANSWER-Safety shutoff A(n) ___ is used to clean fuel oil before it goes to a burner - ANSWER-strainer Stop valves isolate a tank when ___. - ANSWER-it is not in use Most steam plants that use No. ___ fuel oil have two tanks. - ANSWER- 6 In a basic pulverized coal system, the coal ___ stores the coal before it flows onto the coal conveyor - ANSWER-bunker ___ draft results from temperature differences between air and gases of combustion and is produced with a stack only - ANSWER-Natural A draft fan located between a boiler and stack is used in a(n) ___ draft system. - ANSWER- induced
Instrumentation is a group of measuring instruments and related devices that are part of a ___.
- ANSWER-control system A control loop typically uses a(n) ___ as the control element. - ANSWER-steam pressure controller An example of a primary element in a control loop is a(n) ___. - ANSWER-gas flowmeter The ___ are the final elements that control the flow of fuel and air to the burner. - ANSWER-gas valve and damper The setting or adjusting of a safety valve should only be done by a ___. - ANSWER-qualified person who is familiar with the construction and operation of the safety valve Because of the large volume of water, the boiler type most likely to cause a boiler explosion is a ___ boiler. - ANSWER-firetube The part of a boiler with the heat and gases of combustion on one side and water on the other side is known as the ___ surface. - ANSWER-heating
___ is the pressure at which the density of water and steam are the same. - ANSWER-Critical pressure An electric boiler produces heat using electrodes or ___. - ANSWER-resistance coils Boiler horsepower (BHP) is the amount of energy equal to the evaporation of ___ lb/hr of water from and at a feedwater temperature of 212°F. - ANSWER-34. A high pressure steam boiler operates at a steam pressure of more than ___ psi. - ANSWER- 15 A ___ results in a higher boiling point for water in a boiler - ANSWER-higher steam pressure A(n) ___ is a boiler that uses heat recovered from a hot gas stream, such as hot exhaust gases from a kiln or from a gas turbine. - ANSWER-heat recovery steam generator (HRSG) A ___ is the lowest part of the water side of a watertube boiler. - ANSWER-mud drum By increasing the number of passes and the number of fire tubes, water can absorb more heat and ___ increases. - ANSWER-thermal efficiency
The ___ is the operating pressure of a boiler as determined by the design and construction of the boiler in conformance with the ASME Code. - ANSWER-maximum allowable working pressure The safety valve on a boiler must be capable of discharging all the steam the boiler can generate without the pressure increasing more than ___ above the MAWP. - ANSWER-6% A(n) ___ test is a safety valve test performed to determine if a safety valve opens at the correct pressure. - ANSWER-pop A fitting is a ___ and is required for the operation of the boiler. - ANSWER-component directly attached to a boiler Steam boilers having more than ___ sq ft of heating surface require two or more safety valves. - ANSWER- 500 ___ is the predetermined pressure at which a safety valve opens and remains open until the pressure drops - ANSWER-Popping pressure Electric boilers exceeding ___ kW of input require two safety valves. - ANSWER- 500
Drains are placed at the lower section of safety valve discharge piping to ___. - ANSWER- remove any condensation that may form A(n) ___ test is used to establish the relief capacity of boiler safety valves. - ANSWER- accumulation The ___ is the part on a safety valve that increases the area of the safety valve disc to increase the total force. - ANSWER-huddling chamber Safety valve ___ is a drop in pressure between popping pressure and reseating pressure as a safety valve relieves boiler overpressure. - ANSWER-blowdown Boiler safety valves are placed ___ of the boiler. - ANSWER-at the highest part of the steam space The safety valve ___ is the amount of steam that can be relieved by a safety valve. - ANSWER- capacity The boiler vent is located at the ___. - ANSWER-highest part of the steam side of the boiler
A steam pressure gauge must be protected by a(n) ___ to prevent steam from damaging the gauge. - ANSWER-steam siphon Saturated steam is steam that is ___. - ANSWER-in equilibrium with water at the same temperature and pressure When steam is superheated, the temperature ___. - ANSWER-increases with no change in pressure Superheater tubes are protected from warping or burning out by the ___. - ANSWER- continuous flow of steam Steam impinging on boiler tubes would ___. - ANSWER-cause erosion of the lines and fittings Steam quality is the ratio of dry steam to the total amount of ___. - ANSWER-water evaporated A ___ is used to directly measure the moisture content in steam - ANSWER-throttling calorimeter A(n) ___ may be a simple bend or a set of elbows that allow the pipe to move slightly - ANSWER-expansion bend
The flow of steam through a superheater should never be less than ___% of boiler capacity - ANSWER- 25 A(n) ___ injects feedwater into a superheated steam line to reduce the steam temperature. - ANSWER-line desuperheater With a condensing steam turbine, a low exhaust pressure allows the steam to ___ - ANSWER- release more heat A noncondensing steam turbine ___. - ANSWER-is normally used in a plant that requires low pressure steam Impulse steam turbines may contain many sets of revolving blades that ___. - ANSWER-are divided into stages With a reaction steam turbine, the steam expands in the nozzle-shaped passages and ___. - ANSWER-gains additional velocity ___ is steam removed from a turbine at a controlled pressure after it has passed through some of the turbine stages. - ANSWER-Extraction steam
An inverted bucket steam trap is a steam trap that contains an inverted bucket connected to a ___. - ANSWER-discharge valve Steam separators have barriers placed in the path of the wet steam flow that cause the steam to ___. - ANSWER-change direction 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 ___. - ANSWER-conductivity A(n) ___ is a steam system accessory that collects condensate returned from the point where steam is used. - ANSWER-condensate return tank A(n) ___ is used in larger steam boiler plants where there are many sources from which condensate returns to the boiler room. - ANSWER-condensate surge tank Normally, a surge tank is fitted with ___ along with the transfer pumps and controls. - ANSWER- makeup water fittings A pressure buildup in a condensate return tank is prevented by a(n) ___. - ANSWER- atmospheric vent line
Transfer pumps are used to transfer the ___ to the deaerator or directly to the boiler feedwater pumps. - ANSWER-mixture of condensate and raw makeup water A gauge glass may be attached to a condensate tank and used to ___. - ANSWER-indicate the level of condensate The main purpose of a water column is to ___. - ANSWER-reduce turbulence in the gauge glass to get a more accurate reading of the water level in the boiler A low-water fuel cutoff ___ in the event of a low-water condition. - ANSWER-secures the burner The water column and gauge glass should be blown down at least ___ or whenever the water level is in doubt. - ANSWER-once every shift An auxiliary low-water fuel cutoff is installed ___. - ANSWER-slightly below the primary low- water fuel cutoff ___ is a process in which the water level in a boiler momentarily rises with an increase in steam demand. - ANSWER-Swell
A(n) ___ feedwater heater is a feedwater heater in which steam and feedwater mix with each other - ANSWER-open With a(n) ___, heat that would normally be lost up the stack is reclaimed to preheat the feedwater. - ANSWER-economizer A closed feedwater heater is normally equipped with a ___ to protect the shell from excessive pressure - ANSWER-safety valve A high water level in a feedwater heater can allow water to enter the steam or condensate lines and cause ___. - ANSWER-water hammer Soot retards heat transfer because it ___. - ANSWER-insulates the surface of the economizer The theory of operation of a centrifugal pump is that the centrifugal force of a rotating element ___. - ANSWER-is converted into pressure The feedwater stop valve on a feedwater line is located closest to the shell of the boiler so that the ___. - ANSWER-check valve can be repaired without taking the boiler off-line
A variable-speed drive is a motor controller used to vary the ___ supplied to an AC motor in order to control its rotational speed. - ANSWER-electrical frequency The ASME Code states that boilers having over ___ sq ft of boiler heating surface must have at least two means of supplying feedwater to the boiler. - ANSWER- 500 A ___ valve must be installed so that the pressure from the feedwater pump is under the seat of the valve. - ANSWER-globe Each stage of a multiple-stage centrifugal pump has ___. - ANSWER-a single impeller Turbine pumps must be equipped with a relief valve on the discharge line to protect the pump from ___. - ANSWER-excessive pressure Typical applications for ___ in boiler feedwater pumps and deaerator systems include continuously running centrifugal pump applications where the motor horsepower is 15 HP and greater. - ANSWER-variable-speed drives Boiler water with a low pH can cause ___. - ANSWER-acidic corrosion
