Method and device for heat supply of rotary hearth furnace

Abstract

The invention discloses a method and a device for the heat supply a rotary hearth furnace. Smoke afterheat generated by the rotary hearth furnace is firstly heated up through a rear combustion chamber to 1300 DEG C and then respectively introduced into a ball-type hot blast furnace and a fire tube-type rotary dryer which are interconnected in parallel, double preheating and staged heat exchange of the fuel for gas generator and the combustion-supporting air are realized by means of the coordinative operation of combined afterheat utilization devices which are mutually connected, such as ball-type hot blast furnace, heat pipe exchanger, fire tube-type rotary dryer and the like, thus the temperature of combustion flame at a combustion nozzle of the rotary hearth furnace is guaranteed to be not less than 2200 DEG C and drying iron ore powder is performed while high temperature reduction is implemented. The novel high-temperature smoke afterheat recycling technology of the rotary hearth furnace is especially suitable for plants in the area without natural gas and coke-oven gas which require coal-based direct reduction rotary hearth furnace to generate high reduction temperature ranging from 1300 to 1400 DEG C, the technology is advanced, the economical benefit is considerable, the top-quality fuel is saved, the expenditure for cooling high temperature smoke is avoided, and the CO2emission and the production cost are lowered.

Description

technical field [0001] The invention relates to a rotary hearth furnace heat supply method and device, which can be used in a rotary hearth furnace for direct reduction in the iron and steel metallurgy industry, including the use of vanadium-titanium magnetite or common iron ore or other metal elements such as vanadium, chromium, nickel , molybdenum, cobalt and other iron ore, non-ferrous metals, ilmenite, factory iron-containing dust, etc. as raw materials for the rotary hearth furnace in the direct reduction project. Background technique [0002] The rotary hearth furnace direct reduction iron process is a new ironmaking process that has emerged and developed rapidly in the past 30 years. The rotary hearth furnace process used in the American inmetco and IDI factories uses briquettes mixed with iron dust from iron and steel plants and coal for direct reduction. , the gas fuel is natural gas, and its calorific value is 9000 kcal / m 3 , the combustion air is preheated to 280...

AI Technical Summary

Problems solved by technology

The characteristics of the existing rotary hearth furnace heating methods in foreign countries are that the waste heat of the flue gas is not fully utilized, and more energy is needed to cool and process the high-temperature flue gas, which consumes a lot of energy and is not economically cost-effective.

The second is that when the mineral powder is dried, another fuel is burned and more CO is generated. 2 It is not only economically uneconomical, but also harmful to the environment

The third is that foreign reducing agents are mostly gas-based, and a large number of regions in my country that do not have the objective conditions of high calorific value gas fuels cannot adopt this process method

Since many factories only have coal resources or natural gas is too expensive, the gas fuel for rotary hearth furnace burners can only use coal to produce producer gas. card / m 3 , far lower than the calorific value up to 9000 kcal / m 3 Natural gas or calorific value is 4000 kcal / m 3 The reduction temperature of the rotary hearth furnace can only reach 1100°C at most, and the direct reduction of the rotary hearth furnace that cannot be burned to 1300-1400°C requires temperature and atmosphere conditions, which hinders the reduction process and cannot be carried out

If the above-mentioned method of oxygen-enriched air is used to support combustion, the preheating can only be limited to below 600°C, which cannot meet the production requirements of vanadium-titanium magnetite smelting. At present, it is urgent to find a way to fully and effectively utilize the high-temperature flue gas generated in the process, and New Safe and Reliable Heating Technology for Rotary Hearth Furnace

Images