Case study on boiler & boiler's mountings and accessories

MARWADI EDUCATION FOUNDATION GROUP OF INSTITUTIONS

Case Study On

Boilers,Boiler Mountings & Accessories

Prepared By

Yagnesh Virani (131160119614)

Virag Mutha (131160119612)

Yash Saradva (131160119619)

MARWADI EDUCATION FOUNDATION’S GROUP OF INSTITUTIONS

DEPARTMENT OF MECHANICAL ENGINEERING

CERTIFICATE

This is to certify that, students

Shri. Yagnesh Virani Enroll no. 131160119614Shri. Virag Mutha Enroll no. 131160119612Shri. Yash Saradva Enroll no. 131160119619Shri. Enroll no. Shri. Enroll no.

of B.E. second Semester MECHANICAL ENGINEERING branch have satisfactorily

completed the CASE STUDY REPORT On Boiler ,Boiler Mountings & Boiler

accessories for Elements of Mechanical Engineering subject in the academic year

2013/14.

Date of submission ___ / 05/2014.

Guided By: Head of department Introduction

1.What is a Boiler?

“Boiler is a closed vessel in which the heat produced by the combustion of fuel is transferred to water for its conversion into steam at the desired temperature and pressure”

2.What Type of Boilers Are There?1. Fire Tube Boiler

2. Water Tube Boiler

3. Pulverized Fuel Boiler

4. Waste Heat Boiler

2.1 Fire Tube Boiler

Relatively small steam capacities (12,000 kg / hour).

Low to medium steam pressures (18 kg/cm2).

Operates with oil, gas or solid fuels.

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Mainly three types of fire tube boiler:

1. Cochran Boiler

2. Lancashire Boiler

3. Locomotive Boiler

2.1.1 Cochran Boiler

It is a multi-tubular vertical fire tube boiler having a number of horizontal fire

tubes. T is the modification of a simple vertical boiler where the heating surface has been

increased by means of a number of fire tubes.

It Consists Of

1. Shell

2. Crate

3. Fire box

4. Flue pipe

5. Fire tubes

6. Combustion chamber

7. Chimney

8. Man-hole

2.1.2 Lancashire BoilerIt is a stationary, fire tube, internally fired boiler. The size is approximately from

7-9 meters in length and 2-3 meters in diameter.

It consists Of

1. Cylindrical shell

2. Furnace tubes, bottom flue and side flues

3. Grate

4. Fire bridge

5. Dampers

2.1.3 Locomotive Boiler

A locomotive boiler has three main components: a double-walled firebox; a horizontal,

cylindrical "boiler barrel" containing a large number of small flue-tubes; and a smoke

box with chimney, for the exhaust gases. The boiler barrel contains larger flue-tubes to carry

the superheater elements, where present. Forced draught is provided in the locomotive boiler

by injecting exhausted steam back into the exhaust via a blast pipe in the smoke box.

Locomotive-type boilers are also used in traction engines, steam rollers, portable

engines and some other steam road vehicles. The inherent strength of the boiler means it is

used as the basis for the vehicle: all the other components, including the wheels, are mounted

on brackets attached to the boiler. It is rare to find super heaters designed into this type of

boiler, and they are generally much smaller (and simpler) than railway locomotive types.

2.2 Water Tube Boiler

Used for high steam demand and pressure requirements.

Capacity range of 4,500 – 120,000 kg/hour.

Combustion efficiency enhanced by induced draft provisions.

Lower tolerance for water quality and needs water treatment plant.

Mainly one type of water tube boiler:

1. Babcock and Wilcox Boiler

2.2.1 Babcock and Wilcox Boiler

It is a water tube boiler used in steam power plants. In this, water is circulated

inside the tubes and hot gases flow over the tubes.

It consists Of

1. Steam and water drum (boiler shell)

2. Water tubes

3. Uptake-header and down corner

4. Grate

5. Furnace

6. Baffles

7. Super heater

8. Mud box

9. Inspection door

10. Damper

2.3 Pulverized Fuel Boiler

• Pulverized coal powder blown with combustion air into boiler through burner

nozzles.

• Combustion temperature at 1300 -1700 °C.

• Benefits: varying coal quality coal, quick response to load changes and high

pre-heat air temperatures.

Independence Steam Electric Station - Newark, AR

Operation: Unit 1 - January 1983/Unit 2 -December 1984

Fuel: Low-sulfur coal mined near Gillette, Wyoming

Capability: 1,678 megawatts

2.4 Waste Heat Boiler • Used when waste heat available at medium/high temp.

• Auxiliary fuel burners used if steam demand is more than the waste heat can

generate.

• Used in heat recovery from exhaust gases from gas turbines and diesel

engines.

3. Boiler mountingsBoiler mountings are the machine components that are mounted over

the body of the boiler itself for the safety of the boiler and for complete control of the

process of steam generation.

According to the Indian Boiler Regulations (I.B.R.) a boiler is a closed

pressure vessel with capacity exceeding 22.75 liters used for generating steam under

pressure. It includes all the mountings fitted to such vessels which remain wholly or

partly under pressure when steam is shut-off.

According to I.B.R the following mountings should be fitted to the boilers:-

Water level indicator

Safety Valve

1. Dead weight safety valve

2. Lever loaded safety valve

3. Spring loaded safety valve

4. High steam & low water safety valve

Pressure gauge

Fusible plug

Feed check valve

Steam stop valve

Blow off cock

Mud hole & Man hole

3.1 Water Level Indicator

Function:-

Indicates the water level in the drum. The maximum and minimum level is

indicated on that.

Location:-

Placed on the boiler shell. One end is placed in the steam space and other end is

placed on water space.

3.2 Safety Valve

Function:-

The valve is opened when the steam pressure in the boiler exceeds the

set pressure, The excess steam goes out from the boiler till the pressure is reached to set

pressure.

Location:-

Placed on the upper part of the boiler shell. Its end is placed in the steam

space.

There are four types of safety valves:-

1. Dead-Weight safety valve

2. Lever Loaded Safety Valve

3. Spring Loaded Safety Valve

4. High Steam & Low Water Safety Valve

DEAD WEIGHT SAFETY VALVE

LEVER LOADED SAFETY VALVE

SPRING LOADED SAFETY VALVE

HIGH STEAM & LOW WATER SAFETY VALVE

3.3 Pressure Guage

Function:-

It indicates the steam pressure in boiler.

Location:-

Mostly placed on the top of the boiler. It is fitted in such a way that it can be

read from the ground. One end is in the steam space.

3.4 Fusible Plug

Function:-

It is use to protect the boil against damage due to overheating caused by low

water level in the boiler.

Location:-

It is fitted in the crown plate in the case of fire tube boiler or on the furnace from

where, steam is in direct contact.

3.5 Feed Check Valve

Function:-

To control the feed water. The feed water entering back to pump is prevented by

this valve.

Location:-

Opposite side of the boiler or at the bottom it is fitted. It is fitted at the end of

the line from where feed water is entering to the boiler.

3.6 Steam Stop Valve

Function:-

It regulate the flow of steam from boiler to the steam pipe or from one steam

pipe to the other.

Location:-

Fitted on the top of the boiler shell.

3.7 Blow Off Cock

Function:-

To improve salt, mud and other impurities from the boiler. It is also used to

empty the boiler at the time of inspection.

Location:-

It is placed at the bottom pipe or is fitted on elbow pipe.

3.8 Mud Hole & Man Hole

For cleaning of the boiler and for its repair, it is necessary to enter the boiler. An

elliptical cover is provided on the boiler shell. This cover is fitted from inside. It is known as Man

hole By opening this cover, person enters inside the boiler and can do cleaning and repairing

job in the boiler. It is necessary to enter the boiler at the time of annual inspection of the tubes

and checking other surfaces.

In order to remove the impurities, salt and mud it used. Impurities are to be removed

periodically. This is being done with the help of Mud hole.

4. Boiler Accessories Feed pump

Injector

Economiser

Air pre-heater

Superheater

Steam separator

4.1 Feed Pump

It is a pump which is used to deliver feed water to the boiler.

The appliances in common use for delivering the feed-water into the steam boilers

are:

a) Reciprocating pump

b) Rotary pump

4.2 Injector

The function of an injector is to feed water into the boiler. It is also used where the

space is not available for the installation of a feed pump.

4.3 Economiser

An economiser is a device in which the waste heat of the flue gases is utilized for

heating the feed water.

Economiser are of two types :

a) Independent type, and

b) Integral type

4.4 Air preheater

The function of the air pre-heater is to increase the temperature of air before it

enters the furnace. It is generally placed after the economiser.

4.5 Super heater

A superheater is a device used to convert saturated steam or wet steam into dry

steam used in steam engines or in processes, such as steam reforming. There are three

types of superheaters namely: radiant, convection, and separately fired. A superheater

can vary in size from a few tens of feet to several hundred feet (a few metres to some

hundred metres).

4.6 Steam separator

A Steam separator, sometimes referred to as a moisture separator, is a

device for separating water droplets from steam. The simplest type of steam

separator is the steam dome on a steam locomotive. Stationary boilers and nuclear

reactors may have more complex devices which impart a "spin" to the steam so that

water droplets are thrown outwards by centrifugal force and collected.

It is important to remove water droplets from steam because:

In all engines, wet steam reduces the thermal efficiency

In piston engines, water can accumulate in the cylinders and cause a hydraulic

lock which will damage the engine

In thermal power stations, water droplets in high velocity steam coming from nozzles (or

vanes) in a steam turbine can impinge on and erode turbine internals such as turbine

blades.