02.Boiler Fundamentals

04/07/23 S.VISWANATHAN 1


STEAM GENRATION

• CONVERSION WATER INTO STEAM


BOILING PROCESS


BOILING PROCESS OF WATER


HEAT TRANSFER IN BOILER

• RADIATION

• CONVECTION

• CONDUCTION


PressureKg/cm2

Sat.Temp.0C

Sp.EnthalpyKcal/Kg

Sp.Volumem3/Kg

At sattemp.

At S.H.Temp.5400C

At sattemp.

At S.H.Temp.5400C

1 99 638 854 1.725 3.824

10 179 663 852 0.198 0.3802

50 263 667 842 0.04 0.074

100 310 652 828 0.0184 0.032

150 341 626 817 0.0106 0.023

224 374 520 797 0.0037 0.015


INCREASING STEAM PARAMETERS

STEAM GENERATION AT

ATMOSPHERC PRESSURE

INCREASING PRESSURE

INCREASING TEMPERATURE


BOILER-CIRCULATION

• SUFFICIENT FLOW / CIRCULATION OF FLUID IS REQUIRED THROUGH THE BOILER TUBES TO KEEP THE INNER SURFACE CONTINUOUSLY WETTED / COOLED


CIRCULATION NUMBER


EFFECTS OF CIRCULATION NUMBER

• HIGH– CHANCES OF SCALE FORMATION

LESS– LESS POSSIBLITY OF DNB– NEEDS LARGER EVAPORATOR

• LOW– EVAPORATOR COMPACT– CHANCES OF SCALE FORMATION

MORE– OCCURANCE OF DNB


CIRCULATION NUMBER FOR DIFFERENT BOILERS• NATURAL CIRCULATION – INDUSTRIAL BOILERS 12 TO 15– UTILITY BOILERS 7 TO 9

• ASSISTED CIRCULATION 2 TO 3

• FORCED CIRCULATION/

ONCE THROUGH 1


CONTROLLED CIRCULATION

• ORIFICES ARE INSTALLED BETWEEN BOTTOM HEADER AND WATER WALL TUBES TO REGULATE FLOW OF WATER INTO A TUBE BASED ON THE HEAT RECEIVED BY IT / ITS RELATIVE POSITION IN THE FURNACE.

• MINIMISE OCCURANCE OF DNB

02.Boiler Fundamentals

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