System and method for producing sponge iron by gas-based shaft furnace

Abstract

The invention relates to a system and method for producing sponge iron by a gas-based shaft furnace. The system for producing the sponge iron by the gas-based shaft furnace comprises a raw material pre-treatment system and the gas-based shaft furnace which are sequentially arranged, wherein the raw material pre-treatment system comprises a forming device; the gas-based shaft furnace comprises a furnace body, a combustion chamber and a top gas utilizing system; the furnace body sequentially comprises a charging section, a reduction section and a cooling section from top to bottom; and the combustion chamber is arranged outside the reduction section, a top gas outlet is formed in one side of the charging section, the top gas outlet is connected with a gas inlet of a washing tower of the topgas utilizing system, an outlet of the washing tower is connected with a top gas inlet of the combustion chamber, and a gas inlet is formed in the cooling section. The system and method for producingthe sponge iron by the gas-based shaft furnace shorten a technology process that iron is prepared and reduced directly through a shaft furnace method, lower the technology control difficulty, shortenthe reaction time, reduce energy losses, and improve the adaptation of the raw materials.

Description

technical field [0001] The invention relates to the technical field of gas-based shaft furnaces, in particular to a system and method for producing sponge iron in a gas-based shaft furnace. Background technique [0002] Sponge iron, also known as direct reduced iron, is a low-carbon porous substance formed by fine iron powder or iron oxide in a furnace through low-temperature reduction. It is mainly used as a raw material for electric furnace steelmaking, and can also be used as a coolant for converter steelmaking. An essential high-grade raw material for steel. [0003] At present, the main production method of direct reduced iron in the world is the shaft furnace method with natural gas as the energy source, which uses CO and H 2 The main high-temperature reducing gas is used as the reducing agent, and the direct reduced iron is produced in the shaft furnace by external or internal heating. The method mainly includes forming iron concentrate powder, oxidizing and roastin...

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Problems solved by technology

This method mainly has the following problems: 1) CO reduction of iron oxide is an exothermic reaction, while H 2 The reduction of iron oxide is an endothermic reaction, increasing the temperature is not conducive to the utilization of CO gas, but it is beneficial to increase the H 2 The utilization rate of the gas, so the reaction requires strict control of temperature and reducing gas components in order to obtain the best reduction effect

2) This method needs to independently set up a reducing gas preparation device to obtain reducing gas, and the process is relatively long

3) The reducing gas required by the method is derived from natural gas, which reacts with water to obtain H 2 And CO, the reaction is an endothermic reaction, although the generated CO will release a certain amount of heat when it reacts with iron oxides, but the heat release is much lower than that of the corresponding CH 4 The heat released by full combustion will cause a certain amount of energy loss, and the utilization rate of natural gas is low

4) with CO and H 2 When it is reducing gas, in order to reduce the difficulty of reduction and increase the reduction rate, it uses oxidized pellets as raw material, which has high requirements on raw material conditions, and it is difficult to use iron concentrate powder green pellets or natural iron ore, which increases the energy consumption of oxidation roasting

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