Explaination

1. GANDHINAGAR INSTITUTE OF
TECHNOLOGY
ACTIVE LEARNING ASSIGNMENT
NAME:- DISHANT PAGDAR
ENR. NO.:- 160120107072
BRANCH:- COMPUTER-B
BATCH:- B2
SUB:- ELEMENTS OF MECHANICAL ENGINEERING
TOPIC:- WATER AND FIRE TUBE BOILERS
GUIDED BY:- PROF. NIMESH GAJJAR

2. What is a boiler?
“Boiler” is a closed pressure vessel in which steam is
generated with capacity exceeding 25 liters, gauge
pressure greater than or equal to 1 kg/cm2, and water is
heated at 100c or above.
The steam produced is used for:
(i) Producing mechanical work by expanding it in steam
engine or steam turbine.
(ii) Heating the residential and industrial buildings
(iii) Performing certain processes in the sugar mills,
chemical and textile industries.

3. CLASSIFICATION OF BOILERS
 According to relative position of water and hot
gases.
 1. Fire tube.
 2. Water tube.

4. Fire Tube
Boilers

5.  If the hot gases of combustion from the furnace pass
through the tubes and water is surrounding the tubes
is called fire tube boilers. Ex:- cocharan,Lancashire,
etc.
 In this boiler the furnace is placed inside the boiler
shell therefore these type of boilers are internally fired
boiler.
 Relatively small steam capacities (12,000 kg/hour)
 Low to medium steam pressures (18 kg/cm2)
 Operates with oil, gas or solid fuels.

6. Water
tube
boilers

7.  If the water passes through the tubes and hot gases
surrounding the tubes is called water tube boiler. Ex:-
Babcock and Wilcox boiler.
 In this boiler the furnace is placed outside the boiler shell
therefore these type of boiler are externally fired boilers.
 Used for high steam demand and pressure requirements.
 Capacity range of 4,000 – 120,000 kg/hour.
 Combustion efficiency enhanced by induced draft fans.
 Lower tolerance for water quality and needs water treatment
plant.

8. Comparison between Fire-tube & water-tube boilers
S no. Particulars Fire tube boilers Water tube boilers
1. Mode of firing Internally fired Externally fired
2. Rate of steam production lower Higher
3. construction Difficult Simple
4. transportation Difficult Simple
5. Treatment of water Not so necessary More necessary
6. Operating pressure Limited to 16 bar Under high pressure as
100 bar
7. Floor area More floor area Less floor area
8. Shell diameter Large for same power Small same power
9. explosion Less More
10. Risk of bursting lesser More risk