ME 2151: Steam Generator Practice Flashcards

Comprehensive flashcards covering the ME 2151 Steam Generator lectures, including definitions, classifications, thermodynamic properties, and specific boiler types like Cochran and Babcock and Wilcox.

What is the formal definition of a boiler according to the lecture notes?

A boiler is an enclosed container that provides a means for heat of combustion to be transferred into the working media (water) until it becomes steam.

Are open vessels that generate steam at atmospheric pressure considered boilers?

No, open vessels generating steam at atmospheric pressure are not considered to be boilers.

In which part of the boiler is heat generated through fuel combustion?

Heat is generated in the furnace part of the boiler.

What defines a 'Closed system' in the context of steam circulation?

A system where $100\%$ of the steam produced is returned to be reused.

What is an 'Open system' regarding steam and condensate?

A system that does not return the condensate.

In an industrial context, what does a steam boiler system include?

A complex system for producing steam for use in a turbine or in an industrial process.

List two heating applications of steam mentioned in the notes.

Space heating and hot water supply.

Which four industrial process industries are specifically listed as using steam?

Sugar mills, Chemical industry, Paper Industry, and Textile mills.

Steam generators are integral components of what prime movers used to produce electricity?

Steam turbines.

What types of power plants utilize steam turbines for electricity generation?

Thermal and nuclear power plants.

What refined form of water is produced using steam for medical and pharmaceutical purposes?

Distilled water.

Name two transportation-related applications of steam generators.

Locomotives and Marine applications.

How early was steam used to obtain mechanical power?

As early as 2000 years ago.

What evidence of steam/hot air use was found in ancient Egyptian civilization?

Records of the use of hot air for opening and closing temple doors.

Who is considered 'the father of the modern steam engine'?

James Watt.

In which century did James Watt live/contribute to the modern steam engine?

The 17th century.

During which century did steam power applications grow into vehicles like tractors and ships?

The 1700s.

Approximately how long did the 'age of steam' last?

Almost 200 years.

In a simple boiler schematic, what is the name of the water that replaces evaporated water?

Feedwater.

What happens to boiler pressure if steam leaves faster than water is added?

The pressure in the boiler falls.

What happens to boiler pressure if water is added faster than it is evaporated?

The pressure rises.

By how much does the volume of water increase when it is boiled into steam?

About 1,600 times.

The explosive force of water expanding into steam is compared to what substance?

Gunpowder.

What is the primary source of power in all steam engines?

The force produced by the expansion of water into steam.

What occurred at Tampaco Foils in Tongi in September 2016?

A boiler accident that killed at least 36 people.

What occurred at Multifabs Garments in Gazipur in July 2017?

A boiler accident that killed at least 11 people.

What triple measure is emphasized for preventing boiler accidents?

Proper maintenance, inspection, and testing.

What is the boiling temperature of water at atmospheric pressure according to the notes?

$100^\circ\text{C}$.

What is the value provided for atmospheric pressure in kPa?

$101.3\,\text{kPa}$.

During the boiling process, what happens to the heat energy instead of increasing the water temperature?

It results in a change of phase from a liquid to a gaseous state.

What does the notes define as 'the gas phase of water'?

Steam.

What specific type of heat energy does steam contain in large amounts?

Latent heat.

How is ‘Enthalpy’ defined in terms of system energy changes?

A widely used expression for energy changes in a system.

What is the mathematical formula for enthalpy ($h$)?

$h = u + pv$.

Define ‘Sensible heat’.

The heat absorbed by water in attaining its boiling point.

Define ‘Latent heat’.

The heat absorbed to convert boiling water into steam.

What is ‘Wet steam’?

Steam that contains moisture or particulates of steam in suspension.

What is ‘Dry steam’?

Steam that does not contain any suspended particulates of water.

What is ‘Superheated steam’?

Dry steam that is further heated at constant pressure, raising its temperature.

What is the definition of ‘Quality of steam’?

The ratio of dry steam per kg of wet steam.

What is the formula for steam quality ($x$)?

$x = \frac{m_s}{m_s + m_w}$.

In the quality of steam formula, what does $m_s$ represent?

The mass of dry steam.

In the quality of steam formula, what does $m_w$ represent?

The mass of water droplets in suspension.

How does higher pressure affect the evaporation temperature of water?

At a higher pressure, water evaporates at a higher temperature.

At what temperature does water evaporate at a pressure of $10\,\text{bar}$?

$184^\circ\text{C}$.

What is the direct result of burning more fuel in a boiler?

More heat is generated and transferred, more steam is generated, and pressure rises.

What happens to the pressure inside a boiler when less fuel is combusted?

The pressure goes down.

Define a ‘Fire tube boiler’.

A boiler where hot gases pass through tubes that are surrounded by water.

Define a ‘Water tube boiler’.

A boiler where the tubes contain water and the hot gases flow outside.

What phrase is used to remember fire tube boilers?

'Fire in the tube'.

What phrase is used to remember water tube boilers?

'Water in the tube'.

List two examples of Water tube boilers.

Babcock and Wilcox, Stirling boiler.

List five examples of Fire tube boilers.

Cochran, Lancashire, Locomotive, Cornish, and Scotch-Marine boiler.

Where is the furnace located in an 'Internally fired boiler'?

Inside the boiler shell.

Where is the furnace located in an 'Externally fired boiler'?

Outside the boiler shell.

What type of boilers are mostly 'Internally fired'?

Most of the fire tube boilers.

What type of boilers are mostly 'Externally fired'?

Most of the water tube boilers.

How does natural circulation of water take place?

Naturally by the temperature difference of the water.

Natural circulation is usually found in what pressure category of boilers?

Low pressure boilers.

How is water circulated in forced circulation boilers?

With the help of a pump driven by an external source of power.

Forced circulation is usually found in what pressure category of boilers?

High pressure boilers.

What are common uses for a 'Vertical boiler'?

Small factories, small water supply plants, and temporary sites like construction work.

What are two advantages of Vertical boilers?

Requires minimum floor space and is portable.

Why are Vertical boilers considered inefficient?

Due to large wastage of fuel and less heating surface.

What is the most widely used boiler type according to the axis of the shaft?

Horizontal boiler.

What is the pressure threshold for a 'High pressure boiler'?

Higher than $80\,\text{bar}$.

What is the pressure threshold for a 'Low pressure boiler'?

Below $80\,\text{bar}$.

What is the primary use of 'Land boilers'?

Stationary plants.

What is the defining characteristic of 'Portable boilers'?

They can be readily dismantled and carried from one location to another.

What is the maximum steam pressure for 'Heating Boilers'?

$15\,\text{PSIG}$.

What are the temperature and pressure limits for 'Hot Water' in heating boilers?

Below $250^\circ\text{F}$ and $160\,\text{psig}$.

What is another name for 'Power Boilers'?

Process Boilers.

What is the operating pressure for 'Steam Boilers' classified as Power Boilers?

Above $15\,\text{psig}$.

What are the limits for 'Hot Water' in power boilers?

Above $250^\circ\text{F}$ or $160\,\text{psig}$.

What is the first property listed for a 'Good Boiler'?

Capability of generating steam at required pressure and quality quickly with minimum fuel consumption.

What three costs should be minimized for a good boiler?

Initial cost, installation cost, and maintenance cost.

How should a good boiler be described in terms of weight and floor area?

Light in weight and occupying a small floor area.

What should a good boiler be able to meet without overheating?

Fluctuating demands or steam supply.

How should parts of a good boiler be designed for maintenance?

They should be easily approachable for inspection and repairs.

What should be avoided on the heated surfaces of a good boiler?

Deposition of mud and other foreign particles.

Which 1923 law must boilers in Bangladesh conform to?

The Boilers Act, 1923.

Which 2006 code must boilers in Bangladesh conform to?

Bangladesh National Building Code, 2006.

What are the two main sections of a simple vertical boiler's cylindrical shell?

A portion full of water and a remaining steam space.

In a simple vertical boiler, where is the fuel burnt?

On the grate at the bottom of the fire box.

Where does ash fall in a simple vertical boiler?

In the ash pit.

What are the five main types of Fire Tube Boilers?

Simple Vertical Boilers, Cochran Boilers, Cornish Boilers, Lancashire Boiler, and Locomotive Boilers.

Define the Cochran Boiler.

A multi-tubular, vertical, fire tube, natural circulation boiler having horizontal fire-tubes.

Why is the heating surface of a Cochran boiler higher than a simple vertical boiler?

Because of the multiple number of fire tubes.

What is the typical efficiency of a Cochran boiler?

Around $70\text{-}75\%$.

In a Cochran boiler, what is the 'CC' component?

Combustion chamber.

In a Cochran boiler, what is the 'SSV' component?

Steam stop valve.

In a Cochran boiler, what is the 'PG' component?

Pressure gauge.

In a Cochran boiler, what is the 'WLG' component?

Water level gauge.

In a Cochran boiler, what is the 'FT' component?

Flue tube.

In a Cochran boiler, what is the 'BOC' component?

Blow off cock.

What is the function of the 'Antipriming pipe' (APP) in a Cochran boiler?

Steam preparation/transport (diagram legend indicates APP).

What is the shape of the furnace in a Cochran boiler?

Dome shaped.

What is the shape of the crown in a Cochran boiler?

Hemispherical.

Why is the crown of a Cochran boiler hemispherical?

To give the boiler good strength to withstand the pressure of steam inside.

Where do waste gases enter before being released through the chimney in a Cochran boiler?

The smoke box.