Presentationon

Cochran and Lancashire Boiler

In partial fulfillment of the subjectElements of Mechanical Engineering

(2110006)Submitted by:Agarwal Ritika (130120116001) /IT / C-1Akabari Nirali (130120116002) /IT/ C-1Akanksha Sharma (130120116003) /IT/C-1GANDHINAGAR INSTITUTE OF

TECHNOLOGY

What is Boiler?

It is a closed vessel in which steam is produced from water by supplying heat from combustion of fuels.

The steam produced is used for: For generating power in steam engines

or steam turbines. Heating the residential and

industrial buildings. Performing certain processes in the

sugar mills, chemical and textile industries.

Classification of Boiler According to geometric orientation: Horizontal, Vertical, Inclined According to position of water and

gases: Fire tube, Water tube According to location of furnace: Externally fired, Internally fired According to method of water

circulation: Natural circulation, Forced circulation

According to working pressure: High pressure, Medium pressure,

Low pressureAccording to mobility: Stationary, MobileAccording to numbers of tube: Single tube, Multi tube

Cochran Boiler

Characteristics:

This boiler is a vertical, multi tube, fire tube,

internally fired, natural circulated ,stationary

and a low pressure boiler.

This kind of boilers are used for a variety

of steam powered vehicles and other mobile

machines, including early steam

locomotives.

It is modification of simple vertical boiler where heating surface has been increased by increasing number of fire tubes.

Improvement over the simple vertical boiler as it provides greater heating surface.

It is used for steam generation at low rate.

Ranges from 1m dia.*2m high, evaporation 20kg/hr to 3m dia *6m high, evaporation 3000kg/hr.

It is one of the best types of vertical multi-tubular

boiler, and has a number of horizontal fire tubes.

Cochran boiler consist of a cylindrical shell with a

dome shaped top where the space is provided for

steam.

The furnace is one piece construction

Its crown has a hemispherical shape and thus provides

maximum volume of space

Construction

The water is supplied to the boiler

through feed check valve. The coal is introduced to the great through the fire door. The hot gases produced from furnace enters combustion chamber through fuel pipe. This hot gases enters into horizontal fire tubes. Convection heat transfer take place from fuel gases passing inside the tubes to water surrounded the tubes.

Working

The fuel gases coming from of fire tubes enter into smoke box. Finally they discharge to atmosphere through a chimney. The ash formed is collected in ash pit. The steam is collected through antipriming pipe on top of the shell.

A man-hole is provided near the top of the crown of shell for cleaning.

Pressure gauge used to indicate pressure of steam inside the boiler

Water gauge indicates water level inside the boiler to the observer

Feed check valve controls the water from pump to the boiler

Steam stop valve used to control the passage of steam from boiler to the steam pipe.

Mounting and accessories used:

Blow off cock used to discharge sediments

Dead weight safety valve used to maintain safe pressure inside the boiler.

Feed water heater, economizer, super heater, air preheated ,steam separator are some of essential accessories of boiler

Advantages :

Initial cost of boiler is less.

Quick and easy installation.

Any type of fuel can be used.

It can be moved and set up readily in different

locations.

Disadvantages:

Steam raising capacity is less due to vertical design.

Efficiency is poor in smaller sizes.

Water along with steam may enter the steam pipe

under heavy loads due to small steam spaces.

Lancashire BoilerCharacteristics: It is horizontal ,fire tube, internally fired,

naturally circulated, low pressure ,stationary ,multi tube boiler.

It is simple in design, easy to operate and

less operating and maintenance cost.

It is one of the most commonly used

stationary boilers.

It is normally used in sugar mills, textile

industries where power generation as well

as process heating is required.

Lancashire Boiler

Working:The coal is introduced to the grate

through fire holes. The combustion of coal takes place in presence of air which is regulated by damper. The combustion will produce hot gases.

Mounting and accessories used:The mountings used in this boiler is

same as the previous boiler like man-hole, safety valve, pressure gauge, and water level indicator and blow off cock

The fusible plugs are mounted on the top of main flues.

Accessories are added to the boiler as per the requirement of steam generation.

Large rate of steam generation per square metre of heating surface. To some extent this is due to the vibration caused by the motion.

It is free from brickwork, special foundation and chimney. This reduces the cost of installation.

Easy operation, low maintenance costs, easy to clean and inspect.

Advantages:

Disadvantages:Maximum working pressure is limited to 16

bars.Due to brick work, more floor area is

required.Response of pressure build up is less.The furnace is inside the tubes therefore the

grate area is restricted.

References:

Elements of mechanical engineering by NM Bhatt.

www.wikipedia.comwww.mosi.org.uk/media/33871781/

lancashireboiler.pdfwww.cochran.co.uk

Thank you...