Steam Generation and Control Systems

Questions and Answers

If the boiler is generating 20,000 lb/hr of steam, it must be supplied with ________ lb/hr of feedwater

20,000

From the deaerator, oxygen and other noncondensable gases are separated from the feedwater and directed to the atmosphere _________

through the vent

A(n) ___________ system is a system of measuring instruments and controllers that work together to control a process.

control

One pound of water is needed to produce ________ of steam.

1lb Signup and view all the answers

In a low-pressure gas system, the ________ valve is an electric valve that cannot be opened until the gas pilot is lit.

manual reset Signup and view all the answers

______ are used for loads that require dry steam, such as turbines.

superheaters Signup and view all the answers

In a feedwater system, the ________ valve is located close to the shell of the boiler on the feedwater line so that the check valve can be repaired without draining the boiler.

stop Signup and view all the answers

A steaming boiler can have the water in the gauge glass go from half full to empty in a matter of ________ if water is not added to the boiler.

minutes Signup and view all the answers

In a fuel oil system, the purpose of duplex strainers is to ________.

permit one strainer to be cleaned while the other is in service Signup and view all the answers

Superheated steam has more _______ than saturated steam at the same pressure.

heat energy Signup and view all the answers

The deaerator is located ________.

above the feedwater pumps Signup and view all the answers

A gas pilot line on a high-pressure gas system supplies gas through a _________ valve to the pilot gas pressure regulator.

shutoff Signup and view all the answers

The purpose of any fuel oil system is to supply fuel oil to the burner at the proper __________.

temperature and pressure Signup and view all the answers

Number ________ fuel oil needs to be heated before it is pumped so that it can flow.

number 6 Signup and view all the answers

Pulverizing coal allows__________.

for closer contact between the coal and oxygen for complete combustion Signup and view all the answers

Draft is ____________ caused by a difference in pressure between two points.

the flow of air or gases of combustion Signup and view all the answers

Natural draft is the result of temperature differences between __________.

air and gases of combustion Signup and view all the answers

In a high-pressure gas system, the air mixes with the gas in the ________.

burner register Signup and view all the answers

A measuring instrument can use a___________to send a signal to a controller.

transmitter Signup and view all the answers

Pulverized coal is ground into a fine powder and blown into the combustion chamber where it is burned in ___________.

suspension Signup and view all the answers

A control system uses a__________to execute a control strategy.

control loop Signup and view all the answers

Water weighs approximately__________ lb/gal.

8.3 lb/gal Signup and view all the answers

Induced draft is produced by pulling air through the boiler furnace with a fan located in the ____________.

breeching Signup and view all the answers

A control loop uses a____________as the control element.

steam pressure controller Signup and view all the answers

Codes may require that a(n) __________be positioned before the firing-rate valve that controls the volume of gas to the burner.

manual shutoff valve Signup and view all the answers

What is the purpose of steam traps?

<ol> <li>To trap steam. 2. Vent air. 3. Remove condensate from steam lines.</li> </ol> Signup and view all the answers

What is the purpose of the steam strainer?

To keep rust and debris from entering the inlet side of a steam trap. Signup and view all the answers

Which valve cannot be used as a main steam valve? (Select one)

Globe Signup and view all the answers

What are the two types of steam traps?

Return and Non-Return. Signup and view all the answers

What are the four kinds of steam traps?

<ol> <li>Thermostatic 2. Float Thermostatic 3. Inverted Bucket 4. Thermodynamic.</li> </ol> Signup and view all the answers

Name two tests for steam trap operation.

<ol> <li>Strap on thermometers 2. Temperature crayons.</li> </ol> Signup and view all the answers

What does it mean when a pump is steam bound?

The water it was pumping has become too hot and flashed into steam. This is usually caused by a 'blowing' steam trap. Signup and view all the answers

What is Water Hammer?

The noise which is a result of high-velocity steam passing over pockets of water collected in the piping. Signup and view all the answers

What is Start up load?

The condensate formed in bringing the piping and radiators up to steam temperature. Signup and view all the answers

What is Priming?

The carrying of small particles of water into the steam piping. Signup and view all the answers

What is Foaming?

Bubbles or froth build-up on the surface of the boiler water. Signup and view all the answers

What is Bullheading a Tee?

The practice of piping the steam supply into the bull of the tee. Signup and view all the answers

A line desuperheater is used in conjunction with a ___.

pressure-reducing station Signup and view all the answers

Some plants are equipped with a ___ instead of a blowdown tank.

blowdown separator Signup and view all the answers

If steam has a quality of ___%, it is 98% vapor and contains 2% water.

98 Signup and view all the answers

In a heat recovery system, the ___ regulates the flow of makeup water to the flash economizer.

proportioning valve Signup and view all the answers

A 10 degree F rise in feedwater temperature produces approximately ___% savings in fuel.

1% Signup and view all the answers

A throttling calorimeter is used to directly measure the ___

moisture content in steam Signup and view all the answers

The flow of steam maintained through a superheater should never be less than ___% of boiler capacity.

25% Signup and view all the answers

***When water is boiling, the water in the boiler and steam above it are at ___

the same temperature and pressure Signup and view all the answers

Water hammer is caused by ___ and can lead to a line rupture.

mixing steam and water Signup and view all the answers

A steam trap usually has a ___ installed in the inlet line.

steam strainer Signup and view all the answers

Steam turbines require ___ steam.

dry super-heated steam Signup and view all the answers

The air ejectors on the condenser of a steam turbine are used to remove air and other noncondensable gases from the ___

condenser Signup and view all the answers

Boilers operating at ___ p.s.i or more are required to have 2 bottom blowdown valves mounted on the same blowdown line.

100 psi Signup and view all the answers

When ___ fills an inverted bucket trap, the bucket loses buoyancy and sinks to open the discharge valve.

condensate Signup and view all the answers

Failure to maintain steam flow will result in ___ superheater tubes.

overheating of Signup and view all the answers

Water-tube boilers can be fitted with ___ to increase the heat content of the steam.

superheaters Signup and view all the answers

The bellows of a thermostatic steam trap are usually filled with an ___ and water solution to increase the sensitivity of the trap.

alcohol Signup and view all the answers

Although the condensate tank is vented, it is possible to have a pressure buildup caused by ___

leaking steam traps (or a bad trap) Signup and view all the answers

According to the ASME Code, if the MAWP exceeds___ p.s.i, the blowdown lines and the fittings must be composed of materials suitable for the temperature and pressures allowed.

125 p.s.i Signup and view all the answers

A steam trap can be tested with an ___ to determine if it is working properly.

ultrasound device Signup and view all the answers

In large steam boiler plants, a ___ is necessary to provide the extra capacity required to handle changing loads and peak flows of condensate.

surge tank Signup and view all the answers

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 Signup and view all the answers

Some ___ moisture separators automatically open and close because they use a wax that expands and contracts with temperature changes.

variable orifice Signup and view all the answers

The raw makeup water system generally has a float chamber located at the ___ water level in a surge tank.

minimum Signup and view all the answers

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 Signup and view all the answers

A makeup control valve is used to ___

maintain a constant water level in the feedwater heater Signup and view all the answers

The _____ is the water level designated as being the proper water level for safe boiler operation.

N.O.W.L....Normal Operating Water Level Signup and view all the answers

The purpose of a feedwater regulator is to........___

maintain a constant water level in the boiler Signup and view all the answers

Feedwater regulators control the feedwater pump to maintain the water level.......___

at the N.O.W.L Signup and view all the answers

The sequence of 3 numbers found on the nameplate mounted on a reciprocating feed-water pump refers to........___

-diameter of the steam piston..........-diameter of the water piston..............and length of the pump stroke. Signup and view all the answers

___ are usually used to create the draft needed to overcome the resistance caused by economizer tubes.

Induced draft fans Signup and view all the answers

An economizer uses the heat energy from the gases of combustion leaving the boiler to heat the............

feedwater Signup and view all the answers

Turbine feedwater pumps are____.

positive-displacement pumps Signup and view all the answers

A turbine feedwater pump must be equipped with a ___ on the discharge line to protect the pump from excessive pressure.

relief valve Signup and view all the answers

Water that is too hot in the open feedwater heater can cause ___

the feedwater pump to become steambound Signup and view all the answers

Water temperatures that are too low in the open feedwater heater will cause ___

oxygen pitting in the boiler Signup and view all the answers

The ___ of a centrifugal feedwater pump is the rotating element that imparts centrifugal force to the liquid.

impeller Signup and view all the answers

Plant efficiency is increased when a ___ uses steam that is bled or extracted from a steam turbine.

closed feedwater heater Signup and view all the answers

If only one low-water fuel cutoff is used, it must have a ___

manual reset Signup and view all the answers

One way to increase the efficiency of a plant is to ___

recover as much heat as possible from the fuel Signup and view all the answers

A ___ is a boiler fitting that reduces the turbulence of boiler water to make it easier to measure the water level.

water column Signup and view all the answers

The piping that connects a water column to the boiler must be a minimum of ___ and must meet the ASME Code requirements for pressure and temperature.

1 inch Signup and view all the answers

___ is the process where the water level in a boiler momentarily rises with an increase in steam demand.

Swell Signup and view all the answers

___ feedwater regulators are found on package fire-tube or watertube boilers where feedwater pumps run either intermittently or consistently.

Float Signup and view all the answers

A 3-element feedwater regulator measures the steam flow from the boiler.....the ___ into the boiler, and the water level.

feedwater flow Signup and view all the answers

After blowing down a thermohydraulic feedwater regulator, approximately 60 minutes should be allowed for the regulator to ___ before being returned to service.

stabilize Signup and view all the answers

A ___ is used in applications where there are varying flows of condensate and additional condensate storage capacity is required.

surge tank Signup and view all the answers

The ___ pump uses the shape of its casing to direct the discharge.

centrifugal Signup and view all the answers

Some boiler rooms use ___ pumps for reserve or back-up units in the event of an electrical power failure.

reciprocating Signup and view all the answers

An ___ feedwater heater allows steam and feedwater to mix with each other at atmospheric pressure to raise the temperature of the water.

open Signup and view all the answers

Boiler water is treated to prevent ___

-scale.......-pitting.....and -caustic embrittlement Signup and view all the answers

Hardness is a measure of scale-forming ___ dissolved in water.

minerals Signup and view all the answers

Boiler water having high alkalinity could develop ___

caustic embrittlement Signup and view all the answers

Deposits of calcium and magnesium carbonates on the boiler surface cause ___

scale Signup and view all the answers

Pitting and channeling of boiler metal in the water are caused by ___

oxygen and carbon dioxide Signup and view all the answers

Chemicals added to the boiler water change the scale-forming salts into a ___

non-adhering sludge Signup and view all the answers

___ is small water particles and impurities carried out of the boiler into the steam lines.

Carryover Signup and view all the answers

Surface tension on the water in a steam drum is increased by ___

impurities that float on the water surface Signup and view all the answers

A direct cause of overheating of the boiler tubes is ___

scale formation on the tubes Signup and view all the answers

Priming is dangerous and can lead to ___

water hammer Signup and view all the answers

Scale buildup on the water side of a steam boiler is caused by ___

improper boiler water treatment Signup and view all the answers

Trace amounts of dissolved oxygen in the boiler water are removed by ___

adding sodium sulfate to the water Signup and view all the answers

The required frequency for blowing down a steam boiler is best determined by ___

boiler water analysis Signup and view all the answers

Study Notes

Steam Generation and Feedwater

A boiler generating 20,000 lb/hr of steam requires an equal amount of feedwater, 20,000 lb/hr.
One pound of water produces 1 lb of steam; this efficiency is critical for operation.

Deaeration and Draft

Oxygen and noncondensable gases from feedwater exit through the vent of the deaerator.
Natural draft results from temperature differences between air and combustion gases, promoting efficient operation.

Control Systems and Instrumentation

Control systems integrate instruments and controllers to maintain process accuracy.
A control loop acts as the strategic framework that includes a steam pressure controller to execute control strategies.

Fuel and Combustion Management

Superheaters enhance steam quality by increasing heat energy, essential for turbine operations.
Duplex strainers in fuel oil systems allow one strainer to be serviced while the other remains operational.

Steam and Condensate Management

Steam traps serve multiple functions: trapping steam, venting air, and removing condensate to maintain efficient heating.
Water hammer, caused by high-velocity steam interacting with pockets of water, is detrimental to piping systems.

Boiler Components and Functionality

Superheated steam, crucial for turbines, contains more heat energy than saturated steam at equal pressure.
Water columns in boilers must be connected with 1-inch piping adhering to ASME code.

Maintaining Water Quality

Boiler water treatment prevents scale formation, pitting, and caustic embrittlement, all detrimental to boiler longevity.
Priming refers to water particles being carried into steam lines, leading to water hammer.

Regulation and Safety

Feedwater regulators maintain boiler water levels at the Normal Operating Water Level (N.O.W.L) for safety.
In high-stress environments (>100 psi), boiler systems must feature multiple blowdown valves to manage pressure effectively.

Efficiency Enhancement

Introducing a 10°F rise in feedwater temperature can yield approximately 1% fuel savings, highlighting the importance of temperature management.
Heat recovery systems increase overall plant efficiency by utilizing steam extracted from turbines.

Maintenance and Operation

Regular boiler water analysis guides the frequency of blowdowns necessary to maintain water quality.
A surge tank is vital in large steam systems to handle variable condensate flows and additional storage needs.

Understanding Boiler Dynamics

The behavior of steam and water within a boiler affects overall performance, with the quality of steam directly impacting system effectiveness.
Boiler water treated properly can prevent scaling and impurities, ensuring a long-lasting and efficient operating system.

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Description

This quiz covers key concepts of steam generation, feedwater management, and control systems used in boiler operations. It emphasizes the importance of efficiency in steam production and the role of instrumentation in maintaining process accuracy. Test your knowledge on topics like deaeration, combustion management, and steam quality enhancement.