Hot air baking method of blast furnace and comparison

For projects with coking gas, blast furnace gas or converter gas supply conditions, the above-mentioned gas is generally used to burn the hot blast furnace, and then the blower is used to send air to the blast furnace, and the blast furnace is baked with hot air. This kind of blast furnace baking method is dry gas baking, with large air supply, stable temperature and good effect.
However, for new blast furnace projects and large restoration projects without coking gas, blast furnace gas or converter gas supply, blast furnace drying has been a headache for technicians. The traditional baking method is to use diesel fuel for the hot air furnace and blast furnace baking by open fire. The baking effect of the blast furnace is very poor, which directly affects the service life of the blast furnace. Since hot air furnace firing is not possible, the supply of hot air for blast furnace opening is not guaranteed, and the reliability of blast furnace opening is very poor. In recent years, LPG and LNG have been gradually used for hot blast furnace baking, and LPG has made a technological breakthrough in hot blast furnace firing, which is now very mature and reliable. The use of LNG for hot blast furnace firing is still in the exploratory stage, and the combustion effect is poor, the heat load is too small, and the top temperature of the hot blast furnace cannot be guaranteed, etc. is frequently seen. The first one is to use the blast furnace blower to send air to the blast furnace, and implement the real sense of hot air drying blast furnace. The second is to use the combustion fan of the hot blast furnace to send air to the blast furnace, to implement the symbolic hot air baking blast furnace. Now the above two blast furnace baking way of analysis of the situation is as follows: a blast furnace blower baking way of air supply 1, blast furnace internal airflow field situation analysis blast furnace blower power is larger, air pressure is higher, blast furnace internal bottom-up are in positive pressure conditions, can fully offset the height of the blast furnace and hot air temperature joint cooperation resulting in a strong chimney effect (on the pumping force), into the blast furnace hot air can The hot air entering the blast furnace can achieve the ideal working condition of slow rise, so that the hot air can exchange heat with the furnace cylinder and furnace wall stably and fully to achieve the best baking effect. Especially the cylinder part must maintain a high positive pressure, otherwise the baking effect of the blast furnace will be greatly reduced. Based on the requirement of protecting the top sealing device of the blast furnace, the temperature at the top of the blast furnace should not be too high when baking, usually not higher than 330℃. When the blower is used for baking, the air pressure is high, and the blast furnace top dispersion can keep a small opening degree and still maintain a large air flow. Under the positive pressure, the hot air inside the blast furnace rises slowly, and the temperature at the top of the blast furnace will not exceed the standard after the full contact with the furnace cylinder and the furnace wall. 3、Baking effect of furnace cylinder Baking is the core of blast furnace baking, poor baking effect of furnace cylinder is a common problem. The cylinder is located in the lower part of the blast furnace, the hot air flow naturally floats up due to the chimney effect of the blast furnace, so it is difficult to achieve full heat exchange with the bottom and side of the cylinder, and it is even difficult for the heat to reach the bottom of the cylinder when the burner is set up at the air outlet and the open fire is used to bake the furnace. The temperature measurement point during baking is usually chosen near the air outlet, so that the baking curve is completely inconsistent with the actual situation. By increasing the supply air pressure, the density field inside the blast furnace can be changed and thus the temperature field can be changed in the direction of improving the baking effect. The use of a blower for air supply and the installation of a hot air guide pipe will greatly improve the baking effect of the furnace. In the appropriate range, the higher the air supply pressure, the better the baking effect.