Case Study 9 - Pig Iron plant – Stoves

Waste heat recovery from flue gases of Stoves and its utilization in preheating BFG and combustion air, in Pig Iron manufacturing steel plant.

System Description

Initial situation

• The Pig Iron manufacturing steel plants employs Blast Furnace. Blast furnace requires hot air blast for process, generated in Stoves with the combustion of BFG. Huge amount of flue gases exhausted from Stoves at temperature of 300 to 350° C approx.
• The heat in flue gas was being wasted in the atmosphere

Challenges

• The heat was to be recovered from flue gases and to be used for preheating combustion air & BFG
• The gases were not supposed to come in contact with each other in case of leakage in the equipment

Solution offered

• Heat is recovered from the flue gases coming out of Stoves in the form of Hot
  Thermal Oil.
• This recovered heat is utilized to pre heat BFG and combustion air required for the stoves.
• The heat recovery & heat utilization equipments for BFG and combustion air are separate.
• Thermal Oil acts as intermediate fluid. The flue gas does not come in direct contact with BFG and combustion air in case of leakage in the equipment. This ensures safe operation of the system.

Note : The proposed system is under consideration at one of the steel plant in India.
The installation is yet to come up.

Results

Process Schematic