Energy Savings for the Metals Industry Image

The steel industry is energy intensive with many opportunities to apply advanced controls to save energy. Some of the possible energy saving applications in a steel mill and the potential annual savings are illustrated in the figure below.


Energy saving systems typically use variable frequency drives, mill feedback data, and expert mill operation knowledge to precisely control and reduce the energy flows through the equipment. Some of the actual savings achieved by TMEIC on hot strip mills are shown below.

  • Main Motor Cooling Fan – Energy savings through speed control of the cooling fan based on the load on the motor, winding temperature, and air temperature.
  • Auxiliary Motor Cooling – Energy savings through speed control of the cooling fan based on the load on the motor, winding temperature, and air temperature.
  • Fume Exhaust Fan – Energy savings through fan speed control based on the exhaust air flow.
  • Cooling Water Pump – Energy savings through pump speed control based on the tank level and calculated flow of cooling water to the run out table.
  • Scale Pit Pump – Energy savings through pump speed control based on position of the slab relative to the descaler.

The following table shows the energy saving technology for each facility in a steel plant.



Mechanical equipment and system technology

Manufacture of Pig Iron

Combustion equipment

  • Coke oven combustion equipment
  • Air heating furnace combustion equipment

Collection of waste heat

  • Coke dry quenching (CDQ)
  • Collection of exhaust gas heat in coke oven
  • Collection of coke oven furnace gas heat
  • Collection of heat from sinter cooler
  • Blast Furnace dry-type TRT
  • Heat collection of air heating furnace
  • Material drying preheating equipment

Other Processes

  • Pulverized coal injection (PCI)
  • Coal moisture control equipment
  • Dust collector speed control, or combustion blower

Steel Making

Waste Heat Recovery

  • Arc furnace optimum electrical control system
  • Arc furnace electric pole variable speed drive hoisting equipment
  • Ladle refining optimum operation control system
  • Larger arc furnace transformer capacity

Sintering Plant

  • Main Blower
  • Cooling Fan

Collection of waste heat

Material preheating equipment for electric furnace

Electrical Energy Saving

  • Speed control of dust blower
  • High-speed electric hoisting control, furnace cover control

Rolling/ Surface Treatment

Collection of waste heat

  • Boiler for waste heat utilization
  • Heat accumulation type regenerator

Electrical Energy Saving

  • Speed control of auxiliary motor on main motor
  • Speed control of roll cooling water pump
  • Pressure control of de-scaling pump

Rod/ Shaping/ Fabrication

Heat utilization equipment

Speed control of furnace blower

Collection of waste heat

  • Waste heat utilization
  • Collection of annealing exhaust gas heat

Electrical Energy Saving

  • Speed control of cooling fan motor for main motor
  • Speed control of roll cooling water pump
  • Change motor from DC to variable-speed AC

Other Energy Consumption Plant

Cogeneration equipment

  • Multiple-stage extraction steam turbine
  • Back pressure turbine

Electric power use equipment

  • Speed control of Fan or Pump
  • Power factor improvement equipment
  • High efficiency motor/ electric transformer

Lighting system

  • High efficiency lighting system 
  • High frequency fluorescent lamp lighting

Abstract from "Type 1 specified Business Operator" the guide for mid and long term scenario- (4) Steel Plant publication in Japan by ECCJ, Japan 1999 with TMEIC's amendments from electrical point of view.

TMEIC introduces the following electrical energy saving technologies for metal mills:

Energy Saving System for Rolling Mills and Process Lines


  • Providing optimal energy savings for complete rolling mills and process lines
  • Providing an energy saving system which can be easily added to an existing mill
  • Using a combination of PLC controllers and drives


  • Energy saving using variable speed drive control
  • Optimal cooling of drive motor
  • Energy savings for miscellaneous power, lighting, and heaters (example: Stop while idling)
  • Optimal operation using energy saving control model (example: heating furnace combustion control and mill pacing)
  • Waste heat recovery

Energy Saving Controls for Hot Strip Mills

Furnace combustion control

  • Improved fuel consumption using furnace combustion control model
  • Reduction of material heat emission using mill control model

Improvement of power factor

  • Improving efficiency and power factor by applying GCT/IEGT main drives
  • Monitoring power demand for the entire mill line
  • Reduction of electric power rates by improving power factor

Optimization of Ventilation cooling

  • Optimal control using variable speed control
  • Main motor cooling fan
  • Auxiliary motor cooling fan
  • Electrical room ventilation cooling fan

Applying Variable Voltage, Variable Frequency Control

  • Descaler pump
  • Air compressor
  • Heating furnace blower
  • Conveyor system

Energy saving operation

  • Energy saving control of miscellaneous power, lighting and air conditioning units

Introduction of energy saving equipment

  • Applying high efficiency motors
  • Applying high efficiency transformers
  • Replacing DC motors with AC motors and variable speed drives

Energy Saving Control System for Hot Strip Mill Main Motor Cooling Fan

In order to remove the heat generated in the main motor rotor and stator, cooling air is circulated through the unit cooler. The speed of the cooling fan motor is varied proportionally to the load of the main motor, thereby providing energy conservation.

System Configuration

Typical plot of Fan Frequency and Motor Temperature

This graph shows an example of controlling the main motor cooling fan speed so the temperature rise of the motor remains constant irrespective of the main motor load. By applying this technology, large energy savings have been realized as shown in the following table.

Typical Change of Fan frequency and Motor Temperature

This graph shows the power reduction by applying TMEIC's energy saving control system in a steel company.


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