Cornish Boiler: Parts, Working, Advantages, & Disadvantages

Cornish boiler is a simple horizontal boiler which belong to the shell and tube class of boilers. Cornish boiler is much like the Lancashire boiler. 

Cornish boiler has the ability to produce steam at the rate of 1350 kg/hr and can take the maximum pressure of about 12 bar. 

Dimensions of the Cornish boiler shell is 4 m to 7 m in length and 1.2 m to 1.8 m in diameter. Cornish boiler is a fire tube type of boiler that is hot gases flow in tubes and water surround these tubes in shell.

Parts of Cornish boiler

Tubes

These are present inside the shell and hot gases flow through them.

Shell

A big shell which contain water inside it as well as tubes. Heat transfer between hot gases and water is take place here

Side flue

Flue are the tubes which take hot gases after they passes out from the fire tubes. Flue present at side of the horizontal shell are called side flues.

Bottom flue

Flue present at the bottom of the shell is called bottom flue. Bottom flue take the smoke toward the chimney.

Grate

Grate is the place where fuel is added for burning.

Ash pit

Ash pit the one which contain the ashes of fuel aster they are completely burn.

Chimney

Chimney take smoke from the bottom flue and take it out to the atmosphere.

Stop valve

It is used to regulate the flow of steam from boiler

Safety valve

Purpose of this valve is to stop the steam pressure from exceeding the maximum limit

Blow of cock

Blow of cock is used to clean boiler by discharging the water and sediments from bottom of boiler

You can read our other article to know all about NESTLER BOILERS Parts and Working and Simple vertical boiler : Parts, Working, Advantages and Disadvantages

Working of the Cornish boiler

Fuel is added in the grate area where it burn to produce hot gases. There hot gases move into the fire tube which take it inside the shell where it exchange its heat with surrounding water. Water take heat and after some time it start boiling to produce steam. 

Hot gases upon reaching at the end of the fire tube, divided into two section and each move into the one of two side flue which take them once again at the front section of the boiler where they are move into the bottom flue and bottom flue take them toward the chimney. Chimney throw these gases out of the boiler into the atmosphere. 

In this process hot gases travels complete length of boiler thrice that is once in fire tube then in side flue and at last bottom flue.  Maximum heat transfer is taken place at fire tube and shell section then taken place at side flue and at last at bottom flue.

Application of Cornish boiler

• Cornish boiler are used in many industries like textile, sugar, paper, tyre, chemical etc

• They are also used to produce steam to run steam turbine

• They are also used in many marines

Advantages of Cornish boiler

• Cornish boiler have simple design and easy construction

• One of its main advantages is its Compactness and Portability

• Low construction and maintenance cost

• It has ability to overcome load fluctuation

 Disadvantages of Cornish boiler

• Low steam production rate = 1350 kg/hr

• Low maximum steam pressure range 12 bar

• Need more ground because of horizontal structure

LANCASHIRE BOILER Parts, Working, Application, Advantages and Disadvantages

LANCASHIRE BOILER is a simple horizontal boiler and belong from the shell and tube types of boilers. 

It has a circular shell connected to end plates supported by gusset plates.  It has a circular shell connected to end plates supported by gusset plates. 

Lancashire boiler have two fire tubes whose length is equal to length of the boiler and diameter of the fire tube is less than half of the diameter of the shell. 

LANCASHIRE BOILER DIAGRAM

LANCASHIRE BOILER DIAGRAM

You can read our other article to know all about Locomotive boiler Parts, Working and Applications and Cornish Boiler: Parts, Working, Advantages, & Disadvantages

Parts of LANCASHIRE BOILER

Grate

Grate contain the fuel for combustion

Feed valve

Feed valve is used to enter fuel material inside the grate

Fire hole

Fire hole is used to introduce the initiating fire spark 

Safety valve

Safety valve is used to release the pressure when it crosses the safety limits of the boiler

Bottom flue

Flue present at the bottom of the shell and take the hot gases from the front to back of the boiler

Side flue

Flue present at both sides of the shell and take hot gases from the back to the main outlet of the boiler

Low water alarm

Alarm which inform us when water level is low than safety line

Dampers

Flow of gases from side flues to the chimney is controlled by the sliding doors located at the end of side flue

Blow-off clock

For the removal of mud and sediments and blow off clock is provided at the bottom of front section of boiler.

Fusible plug

Fusible plug is used to prevent the coil tubes of the boiler are overheating, extinguishing the fire when water level is lower than a particular level

Working of LANCASHIRE BOILER

In Lancashire boiler fuel is added into the grate of the boiler and burning of this make gases hot. These hot gases start their motion from grate section and enter the fire tube of the boiler. 

Hot gases enter at the front section of the boiler and leave the boiler from the back and enter the bottom fuel and start moving toward the front section of the boiler. 

At front section hot gases leave the bottom flue and enter in side flue and move again toward the back of the boiler and enter the main outlet there. 

There is 85% heat transfer when hot gases are in fire tube and 15% when they are in bottom and side flue. Pressure range of the boiler is about 0.7 MPa to 2 MPa and efficiency is 65 to 70%. 

Dimension of the boiler depends on the dimension of the shell which is 2 to 3 m is diameter and 6 to 10 m in length.

Application of Lancashire Boiler

Lancashire Boilers are used to drive

• Steam turbines 

• Marines  

• Locomotives

Lancashire Boilers are used in industries as processing agent 

• textile industry 

• paper industry 

• sugar industry 

• tire industry 

• chemical industry 

• breweries industry

 Advantages of Lancashire Boiler

• Lancashire Boiler is an Economical boiler 

• It can be easily operated 

• Compactness 

• Portability 

• Simple design  

• Easy construction 

• Have low maintenance cost 

• High overall efficiency (80% to 85%) 

• Steam produce have excellent quality 

• Due to the large quantity of water available, it can easily overcome the load fluctuation

Disadvantages Lancashire Boiler

• Corrosion in water legs 

• It is difficult to clean inside 

• Low steam production rate (9000kg/hr) 

• Horizontal structure cover more ground space 

• Maintenance of brick work is tedious. 

• Have limited grate area because the fire tubes have small diameter. 

• It’s a low pressure Boiler maximum limit is only 20 bars

COCHRAN BOILER Parts, Working, Advantages and Disadvantages

COCHRAN BOILER is a fire tube boiler which is just like the simple vertical boiler with some changes to increase the efficiency of the boiler by increase maximum heating area of the boiler. 

Maximum heating are of the Cochran boiler is 10 to 20 times greater than that of the simple vertical boiler. There are two basic changes made in simple vertical boiler in order to make it Cochran boiler.

One is the introduction of cylindrical shell and second is the hemispherical crown. 

Hemispherical crown have more strength and give maximum area for the specific mass of the fuel, it also increase the radiant heat absorption.

Parts of the Cochran boiler

Ash pit

Ash pit contain the ashes of the fuel material after the complete combustion

Grate

Grate contain the fuel for combustion

Feed check valve

Feed check valve is used to check the level of fuel material inside the grate

Fire hole

Fire hole is used to introduce the initiating fire spark

Flue pipe

Flue pipe take the hot gases from the hemispherical crown and move it toward the combustion chamber

Fire brick lining

Fire brick lining make sure that heat remain inside and outer side remain cool

Combustion chamber

Hot unburnt gases are burnt at combustion chamber

Smoke box

Smoke box contain the smoke of burnt gases which come from the fire tubes

Water level indicator

It indicates the water level inside the water tank

External shell

Outer shell which is visible to us

Pressure gauge

It indicates the steam pressure inside the boiler

Safety valve

Use to prevent the establishing of over pressure inside the boiler

Stop valve

Use to stop the outgoing of steam from the boiler

Chimney

Take the smoke from the smoke box and throw it out in the atmosphere

Working of the Cochran boiler

All the fuel is place in grate and combustion get started. Hot gases along with some unburnt gases moves from hemispherical crown into the combustion chamber where all the unburnt gases are burn out to produce the heat. 

Hot gases moves into the tubes there they exchange their heat with the liquid. After moving in the tubes gases in the shape of smoke came out into the smoke chamber from where it moves out through the chimney. 

Steam produce is collected into the upper chamber and after the sufficient pressure steam is released toward the use full purpose.

Advantages of Cochran Boiler

• Required minimum area on the floor

• Low construction cost.

• Easy to move from one place to an other

• Because of self-contained furnace. Brick work setting is not necessary.

• All kind of fuel can be used

Disadvantages of Cochran Boiler

• Less steam rising capacity due to design limitation

• Cleaning and inspection is quite difficult due to design

• Limited capacity.

• Limited pressure range

• High head room is required due to vertical design

Six Interview Question at Oil & Gas Job Sector

Q) How to calculate volume of a pipe in barrel if data is available in following units 

Difference between pump and motor

Hydraulic

Pump pressurizes the water by transferring its mechanical energy to the water and forces it to move while motor uses the mechanical energy and pressure of flowing water to produce its rotation

Energy conversion

Motor convert the electrical energy into mechanical energy whereas pump does not convert any form of energy it only transfer its mechanical energy to fluid mechanical energy

Type of mechanism

Motor is a driver that is a driving mechanism and make the other mechanism moves for example pump whereas pump is driven that is it need a mechanism to rotate itself for example motor

Device type

Motor can be an electrical device or hydraulic device whereas pump is pure hydraulic device

Input

Input of pump is always mechanical energy whereas input of motor can be electrical energy of kinetic energy (in hydraulic motor)

Output

Output of motor is always a mechanical energy whereas output of pump is kinetic and pressure energy of fluid

Types

There are two main types of motor AC motor and DC motor while pump has two main types centrifugal pump and reciprocating pump

Difference between Fire tube boiler and water tube boiler

Water Tube boiler and Fire Tube Boiler

Structure of Fire tube boiler vs water tube boiler

Both are shell and tube type of boiler, fire tube have hot gases inside the tube while water tube have water inside the tube and hot gases surrounding them

Steam pressure of water tube boiler vs Fire tube boiler

Steam pressure limit of the fire tube boiler is lies between 20-30 bar and the pressure limit of the water tube boiler is much more than the fire tube boiler and is unlimited within the design limits

Unit output Fire tube boiler and water tube boiler

unit output of the boilers mainly depends on the design limits. Unit output of the fire tube boiler is 20 MW and that of the water tube boiler is unlimited

Fuel of water tube boiler and Fire tube boiler

On both fire tube and water tube boiler any type of fuel can be used for providing the heat. Fire tube mostly used commercial fuel and treated wast while in water tube you can used any fuel available 

Efficiency of Fire tube boiler vs water tube boiler

Normal efficiency of the fire tube boiler is about 80 to 85 % but this can be increase or decrease by using different a accessories. Efficiency of the water tube boiler is more than that of fire tube and lies within the range of 85 to 90 %. efficiency of water tube boiler can also be increased by using different accessories

Application water tube boiler vs Fire tube boiler

Fire tube boiler are usually used for the heating purposes while water tube boiler is used for power and heat supply

Inspection requirements of Fire tube boiler and water tube boiler

Fire tube boiler need for regular inspection than that needed for the water tube boiler

Erection of water tube boiler and Fire tube boiler

Fire tube boiler is packed and ready for the work at working site while water tube boiler is need to be shop assembled and erected at site

Simple vertical boiler : Parts, Working, Advantages and Disadvantages

simple vertical boiler is one whose axis of orientation is vertical with respect to the ground. it is a fire tube or a water tube boiler.

Parts of simple vertical boiler

• Ash pit
• Grate
• Feed check valve
• Fire hole
• Fire box
• Cross box
• Hand hole
• fire box 
• Fusible plug
• Water gauge
• Cylindrical shell
• Steam space
• Manhole
• Pressure gauge
• Steam stop valve
• Safety valve
• Uptake
• Chimney

Working of simple vertical boiler

In a simple vertical boiler fuel is added through the fire hoke into the grate which burn there to produce the hot gases. fuel when converted into ash is collected into the ash pit. 

Hot gases rises above and pass their heat to the water in the cross box and go out of the boiler through the chimney. 

Water heats up and steam production starts. steam which produce as a result of water heating is collected at the steam space of the boiler. steam is collected until a certain pressure is attain and then steam is passed out for use like running turbine or engine.

You can read our other article to know all about LANCASHIRE BOILER Parts, Working, Application, Advantages and Disadvantages and NESTLER BOILERS Parts and Working

Application of simple vertical boiler

• Simple vertical boiler have may application is railway locomotives for example railway steam engine
• Simple vertical boiler are used in the road vehicles like steam wagon (steam lorry or steam waggon)
• Simple vertical boiler have a very famous application that steam tractor 
• There are number of boats specially smaller one which uses the simple vertical boiler to power the engine
• In some parts of the world simple vertical boiler are used in steam donkeys
• Simple vertical boilers are also used in the steam cranes and steam Steam shovels

Advantages of simple vertical boiler

• low initial cost because of lesser parts
• Low maintenance cost
• Simple working
• Easy to install and replace
• Occupy small space on ground
• Simple vertical boiler have water level tolerance

Disadvantages of simple vertical boiler

• Vertical design limits its working in many places
• Because of the limited grate area steam production is limited
• Impurities settle down at the bottom thus prevent water from heating
• Boiler tubes must be kept short to minimize height. As a result, much of the available heat is lost through the chimney, as it has too little time to heat the tubes.