METI-ASEAN PROMEEC Seminar<Comments for EE&C
in Iron & Steel Factory>

November, 2006

Hideyuki TANAKAECCJECCJ1

Comments for EE&C
1. Regulations for Reheating Furnace in Japan
1) Standard/Target Air Ratios for Industrial Furnaces
by the Law
2) Heat Recovery Rates for Industrial Furnaces
by the Law
3) Furnace Wall Outer Surface Temperatures forIndustrial Furnace4) Calculation of heat dissipation
2. Air compressor
5) Checking Method of Air Leakage
6) Necessary Air Tank Volume21) Standard/Target Air Ratios for IndustrialFurnaces by the Law
Furnace Category

Liquid fuelGas fuel
CoetaneousIntermittent

ContinuousIntermittent

Melting furnace (F.)
for metal Casting

1.25
1.05~1.20

1.35
1.05~1.25

1.30
1.05~1.25

1.40
1.05~1.30

Continuous steel
billet/ bloom heating
F. (CSHF)

1.20
1.05~1.15

−
−

1.25
1.05-1.20−−

Metal Heating F.
other than CSHF

1.25
1.05~1.20

1.35
1.05~1.30

1.25
1.05~1.20

1.35
1.05~1.30

Standard/Target

Note:

ECCJ

The standard/Target values of air ratio mentioned in the table above define
those to be obtained measurements at the exhaust port of kiln or furnace
when fired at a level of load around the related after inspection and repair.

32) Heat Recovery Rates for Industrial Furnaces
by the Law
Waste Heat Recovery Rates, Standard/Target for Furnaces
Exhaust gas
temperature (ºC)
at F’ce ~ Recu.
< 500500 ≤ ~ < 600600 ≤ ~ < 700700 ≤ ~ < 800800 ≤ ~ < 900900 ≤ ~ <1,0001,000 ≤Capacity
category
A&B
A&B
A
BCAB
CAB
CA
B
CABC

Waste heat recovery rates
Standard(%)
2525353025353025403025453530453530

Target(%)
3535403530403530454035554540554540(Reference for target)
Waste gas
Preheat air
temperature (ºC) temperature (ºC)
275
190
235
230
365
305
400
270
435230
420
350
460
310
505
265
435
440
480
395
525
345
385
595
485
490
535
440
-Notes: A: Rating capacity of from 84GJ/h (= 20Gcal/h)
B: Rating capacity of from 21GJ/h (= 5Gcal/h) to under 84GJ/h (= 20Gcal/h)
C: Rating capacity of from 840MJ/h (= 200Mcal/h) to under 21GJ/h (= 5Gcal/h)

ECCJ43) Furnace Wall Outer Surface Temperatures
for Industrial FurnaceStandard / Target for Furnace Outer Wall Surface
Temperature by the Law
Furnace temperature(ºC)

Standard / Target furnace external wall temp. (ºC)
RoofSide wall

Bottom facing air

1,300 ≤

140/120120/110180/160

1,100 ≤ ~ <1,300

125/110110/100

145/135900 ≤ ~ <1,100

110/100

95/90

120/110

< 900

90/80

80/70

100/90Note: The standard/target values of furnace wall outer surface temperaturetemperature mentioned in theable above defined the average temperature of furnace wall outer surface (exceptspecific parts) during its normal, steady operation at an outside air temperature of20ºC.
20ECCJ54) Calculation of heat dissipation
Side area: As1, As2. As3. As4
Top area: At
Calculation formulas:
The heat dissipation is thought of as the radiation and naturalconvection because of the inside of a factory building.
a. Radiation heatCalculation formula of heat radiation:
Qr = 5.67×ε×A×T1(1004) -T2(1004)(W)(For each surface, and total of Qr = QR)
Where,A: Surface area (m2)ε : Emissivity of melting material = 0.3 (Aluminum painted)
T1: Furnace surface temperature (K)6
T2: Ambient temperature (K)ECCJ

b. Convection heatCalculation formula:Side surface (Vertical wall):Qs = 2.56×(T1 – T2)1.25 ×As (W)(For each surface, and total of Qs = QS)
Top surface:
Qt = 3.26×(T1 – T2)1.25 ×At (W)c. Total heat dissipation
Q = QR + Qs + Qt (W)Where,
As: Side Surface area (m2)
At: Top surface area (m2)d. Estimation of insulation effectCalculation:
By using the data of previous temp., after temp. byimprovement, operation time per year, oil calorific value,efficiency and oil price, etc.
ECCJ75) Checking Method of Air Leakage (1/2)
Specified pressure

Pressure (MPa)0.7Working pressure range

0.6

0.05 ~ 0.1MPa

0.5

Depressurization

0.4

Pressurization
0.3

Small quantity of leakage
Large quantity of leakage

0Time (min)Pressure Change
in Compressed Air System
ECCJ8Checking Method of Air Leakage (2/2)
Q=(P1 - P2)×V
t2×P０

Qmax- Q =ε=t1

(P1 - P2)×V
t1×P０
×100

t1 + t2
Le = Wm×H×ε/100 (kWh)Wm =ECCJ

3 ×Voltage (V)×Current (A)×φ/1000

Q: Leak volume (m3/min)
V: Air system volume (m3)P０: Atmospheric pressure(MPa. Abs.)
P1, P2: Working pressure (MPa)t1, t2: (min)ε: Leakage ratio (%)
Qmax: Compressor discharge
volume (m3/min)
Le: Loss power by leakage (kWh)
Wm: Average input motorpower (kW)
Qmax: Compressor discharge
volume (m3/min)
Le: Loss power by leakage (kWh)
H: Operation time (h)9φ: Power factor

6) Necessary Air Tank Volume
The necessary air tank volume is calculated as follows.
This tank can cover the fluctuating air consumption volume, andkeep the air pressure in tank in some range.
V=0.1013×(Q2 - Q1)
P - PL×t(m3)60Where, V: Tank volume (m3)
Q1: Air supply volume from compressor (m3 N/min)
Q2: Air consumption volume (m3 N/min)
P: Maximum pressure in tank (MPa)
PL: Minimum allowable pressure (MPa)t: Time from Pressure P to PL (sec)

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