Views: 12 Author: Site Editor Publish Time: 2022-11-09 Origin: Site
Scrap steel preheating is a technology that uses the residual heat of the furnace to preheat the scrap steel, thereby reducing the power consumption of the electric arc furnace.Scrap preheating can take place in scrap charging baskets,charging shafts (shaft furnaces) added to the EAF or in a specially designed scrap conveying system that allows continuous charging during the melting process.
About the method of (preheating of scrap steel) to improve the reject rate of the converter,not just in one,but in every of the whole process.
Let us share the experience and methods of learning and practice in iron and steel enterprises:
The roaster preheats the scrap
Scrap preheated by roaster: advantages, no investment required. The original ladle oven can be used.Due to its low flame temperature,poor rigidity, low scrap preheating temperature and large temperature difference (1/5 of the surface layer, not fully baked),the effect is not ideal.
Preheat the waste in the hopper
Advantages small investment, large amount of scrap steel preheating (20-30t),can preheat one barrel (furnace) required amount of scrap steel at a time,and pour it into converter or iron (steel) ladle.The preheating temperature of scrap steel is low (about 200-300℃).Hoppers are susceptible to thermal deformation (dangerous).
The investment intensity is medium, and the operation and maintenance cost is low.The effect is obvious and the income is high.
Oxygen combustion waste preheating in silo
The preheated scrap is added to the ladle or refining furnace.The system is arranged after the converter or LF furnace,the preheating temperature of scrap steel is 5-10t, and the preheating temperature of scrap steel is about 800℃.Low investment intensity, small footprint, flexible and convenient layout,and low operation and maintenance costs.High requirements for scrap quality (rebar head or scrap with good fluidity).
Continuous conveying waste preheating system
Advantages continuous feeding,continuous preheating,continuous discharging.It occupies a large area,the equipment is complex,the investment intensity is high, and the operation and maintenance cost is high.
The total energy required to melt scrap steel in an electric arc furnace (EAF) to produce one ton of molten steel is only one third of the energy required by integrated steel producers to produce one ton of steel from iron ore using the blast furnace/basic oxygen furnace process.Energy Efficiency, High Productivity and Relatively Low Capital Costs of New Modern Electric Arc Furnaces.
Scrap preheaters are lost in slag, flue gas and cooling water.The 20% that typically leaves the furnace in the flue gas represents about 130 kWh of steel production.Using this gas to preheat scrap loaded into the EAF recovers some of the energy and offsets part of the electrical energy required to melt the scrap. Other advantages of scrap preheating include: Increased productivity. Moisture removal from reduction electrodes Reduction of refractories All these advantages contribute to the competitiveness of scrap consume. It has been used for over 30 years in countries with high electricity costs, such as Japan and Europe.Traditional scrap preheating involves the use of hot gas to heat the scrap in drums prior to loading the scrap into the EAF.The source of the hot gas can be the exhaust gas from the EAF or the gas produced by burning natural gas, which will be discussed later. Conventional scrap preheating can be done by conveying the hot furnace gas to the scrap charging barrel by feeding the exhaust gas from the fourth hole of the EAF to a special hood above the charging barrel.
Using modern methods such as the CONSTEELO Process and the Fuchs Shaft System to preheat scrap prior to loading into the EAF has the potential to reduce the overall energy consumption of the furnace.Other potential major benefits include increased productivity,reduced electrode consumption and reduced dust generation.While only a few steelmakers utilize these processes, the adoption of this technology is expected to grow as steelmakers look for ways to reduce costs and increase productivity to remain competitive.