Introduction to blast furnace smelting equipment

Blast furnace smelting is an important process in iron and steel production, and its blast furnace smelting equipment consists of blast furnace body, blast furnace dust collector, blast furnace blower, blast furnace hot blast stove, molten iron tanker, etc. The blast furnace dust collector is a device used to collect the dust contained in the blast furnace gas, the blast furnace blower is the most important power equipment of the blast furnace, and the blast furnace hot blast stove is the equipment for heating and blasting the blast furnace.

Blast furnace smelting equipment basics

The main equipment of high-protection ironmaking includes: blast furnace body, blast furnace dust collector, blast furnace blower, blast furnace hot blast stove, molten iron tanker, etc.

Usually, the construction investment of the auxiliary system is 4 to 5 times that of the blast furnace body. In production, each system cooperates and restricts each other to form a continuous, large-scale high-temperature production process. After the blast furnace is opened, the entire system must be continuously produced around the clock. Except for planned maintenance and temporary suspension of air due to special accidents, the furnace is generally not stopped until the end of the life of one generation.

1. Blast furnace body

The blast furnace body is more complex: an ironmaking shaft furnace with a circular cross-section. The steel plate is used as the furnace shell, and the shell is lined with refractory bricks. The blast furnace body is divided into 5 parts from top to bottom: throat, body, waist, belly and hearth. Due to the good technical and economic indicators of blast furnace ironmaking, simple process, large production volume, high labor production efficiency, and low energy consumption, the iron produced by this method accounts for the vast majority of the world's total iron production. During blast furnace production, iron ore, coke, and slag-making flux (limestone) are charged from the top of the furnace, and preheated air is blown from the tuyere located at the lower part of the furnace along the furnace circumference.

At high temperature, the carbon in the coke (some blast furnaces also inject auxiliary fuels such as pulverized coal, heavy oil, natural gas, etc.) and the oxygen in the air are combusted to generate carbon monoxide and hydrogen. Oxygen, thereby reducing to obtain iron. The smelted molten iron is released from the iron mouth. Unreduced impurities in iron ore and fluxes such as limestone combine to form slag, which is discharged from the slag port. The generated gas is discharged from the top of the furnace and used as fuel for hot blast stoves, heating furnaces, coke ovens, boilers, etc. after being dedusted. The main product of blast furnace smelting is pig iron, as well as by-product blast furnace slag and blast furnace gas.

2. Blast furnace dust collector

Equipment used to collect dust contained in blast furnace gas. Dust collectors for blast furnaces include gravity dust collectors, centrifugal dust collectors, cyclone dust collectors, scrubbers, venturi tubes, gas scrubbers, electrostatic precipitators, and bag dust collectors. Coarse-grained dust (>60～90um) can be removed by gravity dust collector, centrifugal dust collector and cyclone dust collector; fine-grained dust requires dust removal equipment such as gas scrubber and electrostatic precipitator.

3. Blast furnace blower

The most important power equipment of blast furnace. It not only directly provides the oxygen required for blast furnace smelting, but also provides the gas power required to overcome the resistance of the blast furnace charge column. The blowers used in modern large and medium blast furnaces are mostly centrifugal blowers and axial flow blowers driven by steam turbines. In recent years, large-capacity synchronous electric blowers have been used. Although this kind of blower consumes a lot of electricity, it is easy to start, easy to maintain, and has less investment. Blast furnace smelting requires the blower to supply a certain amount of air to ensure a certain amount of carbon is burned; the required air volume is not only proportional to the furnace capacity, but also related to the degree of blast furnace strengthening, generally 2.1 to 2.5m3/min per unit furnace capacity Air volume equipment. But in fact, many blast furnaces are equipped with fans with a capacity greater than this ratio considering the development of production.

4. Blast furnace hot blast stove

The hot blast stove is the equipment that heats the blast furnace and is an indispensable and important part of the modern blast furnace. A modern hot blast stove is a regenerative heat exchanger. The current wind temperature level is 1000 ℃~1200 ℃, the highest is 1250 ℃~1350 ℃, and the highest is 1450 ℃~1550 ℃.

Raising the air temperature can be achieved through technical measures such as increasing the calorific value of the gas, optimizing the structure of the hot blast stove and air supply pipeline, preheating the gas and combustion air, and improving the operation of the hot blast stove. Theoretical research and production practice show that it is an effective way to increase the air temperature to adopt the optimized structure of the hot blast stove, improve the thermal efficiency of the hot blast stove, and prolong the life of the hot blast stove.

5. Hot metal tanker

The molten iron tanker is used to transport molten iron, realize the transfer of molten iron between the desulfurization span and the charging span, or place it under the iron mixing furnace for tapping iron such as blast furnace or iron mixing furnace.