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COMBUSTION

Fire triangle

Oxygen

Exp lain auto ignition tem p?

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AUTOIG NITION TEMPERATURESAUTOIG NITION TEMPERATURES

Fu el Compo nentFu el Compo nent ooCC

H2H2 Hydr o genHydr o gen 570570

CH4CH4MethaneMethane 580580

C2H6C2H6 EthaneEthane 49 049 0

C3H 8C3H 8 P r op aneP r op ane 480480

C4H1 0C4H1 0 ButaneButane 42 042 0--480480

C3H6C3H6 PropylenePropylene 46 046 0

NH3NH3 AmmoniaAmmonia 650650

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Lower combustion limit

Upp er combustion limit

Ev ery fuel has a particular range for burning.

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Reacti o nsReacti o nsCH 4 + 2 O 2 CO2 + 2H 2 O

C 2H6 + 3. 5O 2 2C O 2 + 3H 2 O

H2 + 0.5O 2 H2O

Characteristics :

Mixt u re of CH4 and O2 is m eta-stable u nder n o r m al c o nditi o ns .

At high te mp erat u res, reacti o n takes p lace .

Ra p id and highly ex o ther m ic reacti o ns .

COMBUSTION

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HEAT ING VALUEHEAT ING VALUE

How mu ch heat ( Kcal o r BTU) is available by b u rning p er KG / NM3/SCFT

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HEAT ING VALUEHEAT ING VALUE

What is LHV :

CH 4 (g ) + 2 O 2 (g ) CO2 (g) + 2H 2O (g )

When w ater fo r m ed is in gas p hase, the heat of reacti o n is less and it is called LHV o r NCV.

What is HHV :

CH 4 (g ) + 2 O2 (g ) CO 2 (g) + 2H 2O (l)

When the latent heat of w ater fo r m ed is rec o vered by c o ndensing it, the heat of reacti o n is mo re and it is called HHV o r GCV.

FURNACES

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HEAT ING VALUESHEAT ING VALUES

Fu el Compo nentFu el Compo nentHHVHHV

BTU/SCFBTU/SCFLHVLHV

BTU/SCFBTU/SCF

H2H2 Hydr o genHydr o gen 325325 275275

CH4CH4 MethaneMethane 10131013 913913C2H6C2H6 EthaneEthane 17921792 16411641

C3H 8C3H 8 P r op aneP r op ane 25902590 23 8523 85

C4H1 0C4H1 0 ButaneButane 33703370 31133113

C3H6C3H6 PropylenePropylene 23362336 21 8621 86

NH3NH3 AmmoniaAmmonia 441441 36 536 5

Exp lain e ff ect of lean gas

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Typ es :

1. C ylindrical : ( f eedst o ck heaters ,s m all fu rnaces )

2. Bo x ( R e fo r m er, large fu rnaces )

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Co n f ig u rati o ns :

Cylindrical : ( f eedst o ck heaters ,s m all fu rnaces )

Sm aller p lo t area

Low er c o sts by 10 to 1 5 %

Mo re p arallel p assesTaller f ireb o x, s o mo re dra f t at b u rner

High f lu e gas vel o city, s o higher heat trans f er c o e ff icient

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Bo x ( R e fo r m er, large fu rnaces )

P r o cess c o il can al w ays be drainedTwo p hase f low p r o ble m s are less severe .

Can acc ommo date side f iring, end f iring als o.

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Recover all the heat you supplied? How muchis recovered is the efficiency?

Heat loss areas:

Excess air

High stack temp - heat recovery is less

Poor insulation more losses to the surroundings,leakage

Poor distribution

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End