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Reheating Furnaces In Steel Rolling Mills

 

Reheating Furnaces serve the purpose of heating steel blooms, billets or slabs in steel rolling mills. Reheating furnaces takes this steel stock up to approximately 1200 degree Celsius. The steel begins to deform at this temperature, and the steel rolling process can begin. In a reheating furnace, the heat provided to the steel stock is constant. The stock is charged at the entrance, heated up to the assigned temperature in the furnace and discharged at the reheating furnace exit. During the process, the heat gets transferred to the stock in the furnace with the help of radiation and convection. This takes place due to the placement of the burner gasses and furnace walls. 

How Does The Heat Transfer Mechanism Operate In A Reheat Furnace? 

A steel stock charging temperature can vary drastically, ranging from ambient to the high temperature of 1200-degree celsius. Depending on the dimensions of the steel stock, speed of rolling, and overall steel composition, the exit temperature of a steel stock might differ. The factor of steel quality also plays a huge role when it comes to temperature as it puts limitations on the surface and gradient temperature. It is to be noted that both gaseous and liquid fuels are used in these reheating furnaces. 

What Are The Main Characteristics Of A Reheating Furnace?

A Reheating furnace’ size depends on its ability to produce hot steel from the cold steel stock and is calculated in tons per hour. The increased heat content determines a reheating furnace and its energy efficiency. When the steel stock is heated from 10 degrees celsius to approximately 1200-degree celsius and is then divided by fuel energy used, efficiency can then be calculated accurately. The energy efficiency of a furnace also relies upon the design aspects of various reheating furnaces. 

Design Features That Plays A Role In The Energy Efficiency Of A Reheating Furnace

  • Different styles of burners
  • Dimensions of a Reheating Furnace. 
  • The total number of furnace zones 
  • Different kinds of roof and wall insulation
  • Design of skid 
  • Combustion air and preheating fuel in recuperators

An energy-efficient reheating furnace is developed in a particular method to allow the steel stock to heat up at a uniform temperature without consuming too much labour and fuel. 

Here are Some of The Important Parameters That A reheating furnace must include:

  • The amount of heat that must be imparted to the charge
  • Creation of necessary heat inside the reheating furnace required to heat the stock and curb steel losses
  • The transfer of heat created onto the surface of the stock that needs to be heated
  • Temperature equalisation within the stock 
  • A decrease in heat losses from the reheating furnace to a minimum 

Several operational approaches also play a crucial role in the energy efficiency of a reheating furnace. The ideal case of a reheating furnace is when the furnace is operated at the rated capacity with one kind of steel stock, which has the same dimension and composition. But often, this practice is not followed, which hampers the efficiency of the reheating furnace. 

Factors that Affect Efficiency of A Reheating Furnace

  • Differences in the dimension and composition of steel stock 
  • Delays in rolling can delay or halt the movement of steel stock in the furnace 
  • The composition of the fuel and its availability may differ
  • The conditions of the burners and the internal  state of the reheating furnace might deteriorate 

How are Reheating Furnaces Classified?

Several types of reheating furnaces are available in an average steel rolling mill, but how are they classified into different categories? Reheating furnaces are usually placed in four categories based on:

  • Heating Method 
  • Charging the reheating furnace method 
  • Steel stock movement inside the reheating furnace
  • Recovery of the heat method

If the reheating furnace is classified based on the heating method, there will be two types of heating.

  • Electrical Heating 
  • Combustion Heating 

Combustion heating reheating furnaces are able to use solid, gaseous and liquid fuels.

When the classification is based upon the steel stock’s movement in the furnace, a continuous furnace can be categorized further.

  • Pusher Furnace 
  • Walking Beam Furnace 
  • Roller Hearth Furnace 
  • Walking Hearth Furnace 
  • Rotary Hearth Furnace 

When the classification depends on heat recovery, there are only two types of reheating furnaces.

  • Regenerative Type 
  • Recuperative Type

The regenerative type of reheating furnace operates on regenerative burners. On the other hand, the recuperative variety of reheating furnaces functions with recuperators. 

Why Choose Reheating Furnaces From The Best Rolling Mill Manufacturers

When you select reheating furnaces from The Steefo group, you are guaranteed superior quality. Get your hands on the most innovative and futuristic products that will help you change the face of your business.  

Our projects and products also experience strict testing and quality checks to deliver best-in-class products. Our emphasis on technology and innovation also delivers up-to-date products for your rolling mill. 

To learn more about the Steefo Group and our reheating furnace and how they can improve your productivity and profits, contact +91 98240 76873 or drop a mail at marketing@thesteefogroup.com

 

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