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Criteria for exhaust gas temperature
(the Law Concerning Rational Use of Energy)
Criteria for boilers, standard / target exhaust gas temperature
Type
Load
factor, %
Solid fuel
Liquid fuel
Gaseous fuel
Blast furnace gas,
etc. Byproduct gas
Fixed bed
Fluidized bed
Electric utility service
 
–
–
145/135
110/110
200/190
Other service (Quantity of evaporation, tons/h)
 
 
 
 
 
30–
10–30
5–10
–5
50–100
50–100
50–100
50–100
200/180
200/180
–
–
200/170
200/170
– /300
– /320
200/160
200/160
220/180
250/200
170/140
170/140
200/160
220/180
200/190
Summary of note After periodical inspection / 20°C at air feeder inlet, load factor at 100%, boiler outlet
(heat recovery, flue gas treatment facility outlet)
Additional notes on pulverized coal combustion on fixed beds, use the fuel of higher mixing ratio in case of mixed fuel combustion, the target temperature for black liquor combustion being 180°C
Exemption:
Small boilers specified by the Labour and Health Law, boilers for which the fuel has been changed after installation, boilers burning an industrial waste with fuel
Boilers burning either black liquor or a poisonous gas for treatment purpose
Boilers for the purpose of using waste heat, using a heating medium, operating unsteadily, or for the purpose of development, research and test manufacturing
Heat Insulation
  • The surface of a steam pipe is equipped with heat insulation, which lowers the surface temperature of the piping, reducing the heat loss. The amount of heat loss is evaluated by mathematical calculation.
  • An increase in the insulation thickness reduces the heat loss. (see the right figure)
  • An excessive insulation thickness, however, is uneconomical.
  • An increase in the insulation thickness leads to an increase in fixed costs.
  • The insulation thickness that minimizes the sum of heat loss expenses and fixed costs is the economical thermal insulating thickness defined in JIS A 9501(2001). (see the figure below)
Remarks:
Steam temperature=183°C
Room temperature=20°C
Heat transfer factor, inside=10,000 kJ/h/m2/°C
Surface emissibity=0.6
Insulation material=Rockwool blanket
Economical thickness
Criteria for factories (The Energy Conservation Law)
The "criterion" should be observed to the extent economically and technically possible.
The "target" is the objective to pursue to achieve a reduction of energy unit consumption of 1 (one) percent per year (average).

Subjects of criteria (matters concerning standards)
  1. Rationalization of fuel combustion.
  2. Rationalization of heating, cooling and heat transfer.
  3. Prevention of heat loss by radiation, conduction, etc.
  4. Recovery of waste heat.
  5. Rationalization of heat conversion into power, etc.
  6. Prevention of electricity loss by resistance, etc.
  7. Rationalization of conversion of electricity into power, heat, etc.

Quantitatively specified item of criteria (standard value, target value)
  1. Air ratio for boilers
  2. Air ratio for industrial furnaces
  3. Outer wall temperature of industrial furnaces
  4. Exhaust gas temperature for boilers
  5. Waste heat recovery rate of industrial furnaces
  6. Facility for which power factor should be improved
  7. Target efficiency of high-efficient totally-enclosed electric motors (02 to 37kw)
Guidelines by The Law
  • Items & Numerical Expression
  • Air Ratio for Boiler
  • Air Ratio for Furnace
  • Heat Recovery for Furnace
  • Waste gas temp./ Boiler, Wall temp./ Furnace
  • Power Factor
  • Motor Efficiency
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