A production process and system for oxidized pellets using a grate machine-rotary kiln system

Abstract

A chain grate-rotary kiln system oxidation pellet production process, the process includes the following steps: 1) The raw pellets are dried, preheated and oxidized through the chain grate, and then the materials passing through the chain grate are transported to the rotary kiln Roasting, and then transported to the ring cooler for cooling to obtain pellets; 2) The hot air discharged from the first stage of the ring cooling is sent to the rotary kiln, and the hot air discharged from the rotary kiln is sent to the second preheating stage, and the hot air discharged from the second stage of the preheating 3) The hot air discharged from the second stage of the ring cooling is sent to the preheating stage by blasting; 4) The hot air discharged from the third stage of the ring cooling is sent to the blast drying section by blasting. The solution of the present invention blows hot air into the first stage of preheating, so that the air pressure in the first stage of preheating is greater than that in the second stage of preheating, so that there is no need to denitrify the gas in the first stage of preheating; at the same time, a stable hot air zone is formed in the first stage of preheating , to ensure the preheating effect of the upper and lower layers of pellets.

Description

technical field [0001] The invention relates to a preheating process, in particular to a production process for oxidizing pellets using a grate-rotary kiln system, and belongs to the technical field of pellets; the invention relates to a grate-rotary kiln system. Background technique [0002] Pellets are the main iron-containing charge produced by blast furnace ironmaking in my country. In 2015, the output of pellets in my country was 128 million tons. Compared with sinter, due to the low energy consumption and relatively friendly environment of the pellet production process, and the product has the advantages of good strength, high grade, and good metallurgical properties, it can increase production and save coke when applied to blast furnace smelting, and improve ironmaking technology and economy Indicators, reducing the cost of pig iron, and improving economic benefits, so pellets have been vigorously developed in my country in recent years. [0003] my country's pellet p...

AI Technical Summary

Problems solved by technology

[0004] Although pelletizing enterprises have done a lot of work in environmental protection, dust removal and desulfurization have been effectively controlled, and can meet the emission requirements, but at present, due to the high cost of NOx removal and complicated process, in the environment of sluggish steel form, this poses a threat to pelletizing. The industry has brought new challenges. Some enterprises have to reduce production in large quantities due to excessive NOx, and even face shutdown

Judging from the current production situation of most pellets, in order to meet the new emission requirements, the terminal denitrification device is added after desulfurization, resulting in a substantial increase in investment costs and operating costs

In addition, the recycling of hot air in the hot air system of the grate-rotary kiln-ring cooler pelletizing process plays a very important role in the production and quality of pellets, as well as in energy saving and emission reduction. Under the existing hot air system , the two stages of preheating are preheated by exhaust air, which not only causes the flue gas of the second stage of preheating to flow into the first stage of preheating, causing the NOx of the preheating stage to exceed the standard, but also causes large differences in the strength and oxidation degree of the upper and lower layers of pellets due to uneven preheating affect the quality of its products

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