21-09-2013, 02:23 PM
BOILERS
BOILERS.ppt (Size: 1,006.5 KB / Downloads: 70)
INTRODUCTION
Boilers are defined as a closed vessel in which steam is produced from water by combustion of fuel
According to A.S.M.E boilers are defined as “a combination of producing, furnishing or recovering heat together with the apparatus for transferring the heat so made available to the fluid being heated and vapourised”.
These are used for generating power in steam engines and steam turbines
In the textile industries for sizing and bleaching etc., and many other industries like sugar mills, chemical industries .
Classification
depending upon the axis of boilers –classified into-Horizontal, vertical and inclined boilers
Depending upon the matter flows in tubes of boilers :-
Fire tube:- if the hot gases are flowing in side the tubes and water surrounds the tubes then it is called as fire tube boiler
ex: Cochran, Lancashire, and Locomotive boilers
Water tube:-if the water is flowing inside of the tubes and hot gases surrounds the tubes then it is called water tube boilers
Ex:-Babcock and Wilcox, Stirling, Yarrow boilers
Depending upon the firing of boilers:-
Externally fired:-if the fire is outside of the shell
Ex:- babcock and wilcox etc.,
Internally fired:-if the furnance is located inside of the boilers
Ex:-cochran,lancashire etc.,
BOILER MOUNTINGS
Two safety valves
Two water level indicators
A pressure gauge
A steam stop valve
A feed check valve
A blow off cock
An attachment for inspector’s test gauge
A man hole
Mud holes or sight holes
Water level indicator
The function of the water level indicator is to indicate the level of water in boiler constantly
Level of the water in the boiler shell decreases when the water being heated in the boiler transforms into steam
For safe working water is usually kept at safe level