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Summary of scrap preheating methods

[vc_row][vc_column][vc_column_text]Today we are not talking about (iron ore and steel scrap) prices, only the method of (scrap preheating), to increase the converter scrap ratio, not only in one link, it should eat scrap in all links of the entire process, the following is what we are Let me share with you the experiences and methods learned and practiced by steel companies.

  • The roaster preheats the scrap steel.

The scrap steel is preheated by the roaster: Advantages, no investment is required. The original steel-clad roaster can be used. Because of its low flame temperature, poor rigidity, and low scrap preheating temperature, The temperature difference is large (1/5 of the surface layer, not fully baked), and the effect is not ideal.

scrap-preheating-methods1

scrap-preheating-methods

  • Preheat the scrap in the hopper

scrap-preheating-methods

scrap-preheating-methods

Advantages: small investment, large scrap preheating (20-30t), the amount of scrap required for one bucket (furnace) can be preheated at a time and poured into the converter or iron (steel) ladle. The preheating temperature of scrap steel is low (about 200-300℃). The hopper is easily deformed by heat (dangerous).

  • Preheat the scrap steel in the steel (iron) ladle (pure oxygen combustion)

Converter gas is the combustion medium, and its flame temperature can be as high as 2200℃. The flame spraying speed is high (Mach 1.9). Compared with the traditional baking equipment, the flame has good rigidity and strong penetrating ability. It has the function of cutting scrap, and can conduct heat convection to the scrap at the bottom of the iron ladle, and the baking temperature is uniform (The upper and lower temperature difference is less than 30℃), which can make the scrap heating up quickly: 11 tons of scrap steel, heating for 13 minutes, the preheating reaches 1161℃ (test data). The thermal efficiency is increased by more than 5 times, breaking through the traditional scrap preheating method, and providing the most direct and effective method for iron and steel enterprises to increase the converter scrap ratio, save energy and reduce consumption, tap potential and increase efficiency, and increase production. Because the scrap preheating is carried out at a high temperature of 2000 ℃, the problem of dioxins is directly avoided.

The investment intensity is medium, and the operation and maintenance cost is low. The effect is obvious and the income is high.

scrap-preheating-methods

scrap-preheating-methods

  • Oxygen-burning scrap preheating of the silo

The preheated steel scrap is added to the steel 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℃. The investment intensity is small, the floor space is small, the layout is flexible and convenient, and the operation and maintenance cost is low. High requirements for scrap steel quality (rebar head or scrap with good fluidity).

scrap-preheating-methods

scrap-preheating-methods

  • Continuous conveying scrap preheating system

Advantages: continuous feeding, continuous preheating, continuous discharging. It occupies a large area, complex equipment, high investment intensity, and high operation and maintenance costs.

scrap-preheating-methods

scrap-preheating-methods

Through the above practice, in the process of increasing the converter scrap ratio, the main problem to be solved is the converter heat balance problem. The steel (iron) water temperature and the size of the scrap have an important influence on the melting of the scrap. At 1300℃ and 1600℃, the melting rate of the scrap is 0.045mm/s and 0.309mm/s; the equivalent diameter of 50mm is melting. The time is 18.6min and 7.65min respectively. Scrap preheating is conducive to the melting of scrap steel in molten iron. When the scrap steel is 25 ℃, the melting time of the scrap steel is 12.82 min; when the preheating temperature of the scrap steel reaches 800 ℃, the melting time of the scrap steel is 7.65 min. When it reaches 1000 ℃, the scrap steel The melting time is 3.05min. The solution is to achieve a heat balance under a high scrap ratio. The heat compensation method is mainly: adding fuel, and heat compensation through fuel combustion. In terms of the object of thermal compensation, the main solution is to increase heat to preheat the scrap. The iron ladle is covered with heat preservation to reduce temperature drop!

Through the above practice, in the process of increasing the converter scrap ratio, the main problem to be solved is the converter heat balance problem. The steel (iron) water temperature and the size of the scrap have an important influence on the melting of the scrap. At 1300℃ and 1600℃, the melting rate of the scrap is 0.045mm/s and 0.309mm/s; the equivalent diameter of 50mm is melting. The time is 18.6min and 7.65min respectively. Scrap preheating is conducive to the melting of scrap steel in molten iron. When the scrap steel is 25 ℃, the melting time of the scrap steel is 12.82 min; when the preheating temperature of the scrap steel reaches 800 ℃, the melting time of the scrap steel is 7.65 min. When it reaches 1000 ℃, the scrap steel The melting time is 3.05min. The solution is to achieve a heat balance under a high scrap ratio. The heat compensation method is mainly: adding fuel, and heat compensation through fuel combustion. In terms of the object of thermal compensation, the main solution is to increase heat to preheat the scrap. The iron ladle is covered with heat preservation to reduce temperature drop!

This article is from “YuXinGongCheng”[/vc_column_text][/vc_column][/vc_row]

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