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How to calculate the Furnace Efficiency

FURNACE EFFICIENCY = THEORETICAL TOTAL HEAT REQD FOR MELTING (H T) IN KWH. FOR THE MELTING OF THE METAL IN KWH
—————————————————————————————————————-
ACTUAL CONSUMED ENERGY BY THE FURNACE FOR MELTING OF THE METAL IN KWH (H A)
THEORETICAL HEAT REQD FOR MELTING:
H.1 IN KWH = W X SPECIFIC HEAT OF THE METAL X ( T2- T1) + LATENT HEAT OF
THE METAL XW
——————————————————————————————–
3600 ( 3600 KJ = 1KWH)
H2 IN KWH = HEAT REQD FOR SLAG TO.HEAT AND MELT WILL BE 1.65X WSLG X3.6 ( WHERE 3.6 MJ = 1 KWH)
WHERE

W = WEIGHT OF THE METAL TO MELT
T2- = MELTING FINAL TEMP OFTHE METAL.
T1 = INITIAL OR CHARGING TEMP OFTHE METAL.
WSLG = WEIGHT OF SLAG GENERATED IN OPERATION.

HERE,

H T = H1 + H2

  ACTUAL CONSUMPTION OF THE MELTING CAN BE MEASURED FROM THE INPUT BUSBAR OF THE     FURNACE PANEL IN KWH. (H A IN KWH) WHICH IS HIGHER THAN H.T.

  SO DIFFERENCE BETWEEN HA AND HT (HA – HT) IS LOSS DUE TO CONDUCTION RADIATION AND OTHER     LOSSES,

  AND SO FURNACE EFFICIENCY IS RATIO OF THEORETICAL HEAT REQD FOR MELTING IN KWH TO ACTUAL     CONSUMED HEAT IN KWH.

i.e.,

FURNACE EFFICIENCY = HT
——————————————————————————————–
HA
55% TO 65% (MAX) OVERALL ENERGY EFFICIENT FURNACES ARE AVAILABLE.

FOR M.S. SCRAP

SPECIFIC HEAT = 0.682 KJ / KG DEG CENTI.
LATENT HEAT = 272.0 KJ / KG

SPECIFIC HEAT REQD TO MELT 1000KGS OF M.S SCRAP WILL BE, @ 1650ºC

=   100 × 0.682 × (1650 – 30)
————————————– KWH
3600
= 307 KWH

LATENT HEAT REQD,
272 × 1000 / 3600
76 KWH.

HEAT FOR SLAGE
1.6 × 25 / 3.6
12 KWH.

TOTAL KWH THEORETICALLY REQD FOR MELTING IS 395 KWH.

APPROX 400 KWH REQD TO MELT M.S OF 1000KGS TO 1650DEG CENTIGRADE.
IF THE FURNACE CONSUMES 625 KWHITON THAN THE FURNACE IS OVERALL ENERGY EFFIECIENT 65%.

[ i.e. 400 ÷ 625 = 64 % ]

DISTRIBUTION OF LOSSES IN INDUCTION FURNACE:
LOSSES IN INDUCTION FURNACE

The theoretical energy require to melt one Ton of steel is 385 TO 400 KWH / Ton. However in actual practice, the specific energy consumption is remarkably higher to 550 KWH / ton to 950 KWH / ton.