Development and application of the rapid opening method of Jinan Iron and Steel Co., Ltd.'s 350m3 blast furnace by introducing compressed air into the taphole
Continuously increasing new achievements Chuqiang, Zhao Xiaoming and Chen Jianbo
(Jinan Iron and Steel Group Co., Ltd. No. 1 Ironmaking Plant)
Abstract: This article focuses on the poor fluidity of slag iron due to insufficient furnace temperature in the past blast furnace opening, which easily made it difficult to open the iron taphole of the first furnace and even caused a large number of tuyeres. In order to solve the problem of major accidents such as burnout or even freezing of the furnace, a new furnace opening method has been developed in which a special conduit is pre-buried in the taphole channel and the conduit is used to pass compressed air into the furnace. This significantly increases the temperature of the furnace and reduces the slag. The fluidity of iron has been significantly improved, the opening speed of the first iron furnace has been greatly accelerated, and the furnace opening process has been greatly accelerated.
Keywords: Compressed air for blast furnace opening taphole
l Introduction
Since the blast furnace opening is a relatively complex system engineering, therefore, the blast furnace opening All aspects and every link of the furnace process need to be clearly understood and implemented by the personnel who preside over and participate in the blast furnace opening. Only in this way can the blast furnace opening be a complete success. In the past, the success of blast furnace opening was evaluated based on the smooth operation of the furnace and the safe and smooth tapping of iron. Generally, rapid production was not pursued. With the improvement of the knowledge and technical level of blast furnace workers, the standards for evaluating whether the blast furnace is a complete success are also improving. In addition to ensuring that the furnace conditions are smooth and the iron can be safely and smoothly tapped, whether the blast furnace can quickly reach production and reduce consumption as much as possible has been It has become an important evaluation index and is also the goal pursued by blast furnace workers. With the improvement of scientific and technological level and the improvement of iron-making professional technical innovation ability, some new technologies and new methods have been applied in the blast furnace opening, so that the blast furnace opening can not only achieve smooth furnace conditions and safe and smooth iron tapping, but also ensure the smooth progress and safety of the blast furnace. The speed of reaching production capacity has also been greatly accelerated. Jinan Iron and Steel Co., Ltd.'s 350m3 blast furnace has further developed and innovated based on the technology of blowing compressed air from the taphole into the furnace when opening the furnace from Xuangang and other units, and successfully applied it to the opening of four blast furnaces, greatly increasing the opening speed. It has been accelerated and achieved obvious economic and social benefits.
2 Analytical understanding of the problems in the opening of blast furnaces in the past
Due to the need to minimize the time to achieve production and efficiency, increase the speed of air addition, and reduce the loss of indicators due to the need for large and medium-sized repairs and opening of blast furnaces . Judging from the changes inside the blast furnace after the shutdown, due to the long shutdown time, the hearth temperature is seriously insufficient. The first furnace slag iron has insufficient heat, the temperature is low and sticky, especially during the mid-repair furnace, due to the bottom of the taphole tunnel and The slag-iron contact interface is mixed with insufficient-temperature slag iron, and the existing taphole opening machine cannot drill. The conventional method is to use an oxygen tube to boil the taphole after the amount of iron in the furnace reaches a certain level. The use of oxygen to burn iron mouth has the following shortcomings: First, there are serious unsafe factors and risk factors of burns and scalds when operated by multiple people and the space on site is small. Once an abnormality occurs, it is difficult for personnel to evacuate in time; second, a large number of oxygen tubes are consumed, causing certain Waste of materials: third, it takes a long time to burn through the taphole, or even fails to burn for a long time, causing serious wind suffocation in the furnace, affecting the recovery speed of the furnace condition, and even causing major malignant accidents; fourth, a large amount of yellow smoke is produced, which seriously pollutes the environment. Affect corporate image. When the No. 6 blast furnace of Jinan Iron and Steel Co., Ltd. No. 1 Ironmaking Plant was opened for maintenance in 2007, the tap hole still failed to burn after nearly 10 hours, so it was forced to use the slag port to tap iron. As a result, local tuyere flooding was caused when the air was blocked. It's scum, which greatly delays the time to achieve production and results. Therefore, the most critical constraint after opening the furnace is whether the taphole of the first furnace can be opened quickly and smoothly. In view of the shortcomings of the conventional method of opening the taphole, in order to successfully open the taphole of the first furnace, after many discussions and discussions, the details were gradually improved. After analyzing various key points, it was believed that using the taphole air duct to pass compressed air into the taphole is a more effective method for opening the taphole. Through specific organization, implementation and continuous optimization, a method for quickly opening the taphole by introducing compressed air into the taphole was formed.
3 Design, installation and application of special conduits for compressed air through iron mouth
3.1 Conduit design
By learning from Xuangang’s experience and combining it with our factory In fact, a special conduit for the compressed air to be introduced into the taphole was specifically designed. The conduit mainly consists of three parts, namely the furnace section, the buried section, and the compressed air and peephole interface (see Figure 1). It can be seen from Figure 1 that the furnace section where the taphole is connected to the special compressed air conduit is designed to be relatively thick, and there are many small holes drilled on the circumference; the buried section is relatively thin, mainly to prevent large flows when tapping, and to have Helps to form a more suitable taphole passage; the compressed air and peep hole interfaces are arranged outside the furnace, with the compressed air interface arranged upwards to reduce air inlet resistance; the peep hole interface is installed at the end of the duct concentrically with the duct, here first Install a straight-through valve, and then configure the tuyere sight glass so that you can observe from the tap hole during the furnace opening process to determine whether the furnace hearth is on fire and when.
3.2 Duct installation application
The special duct for compressed air through the iron mouth can be installed after the blast furnace drying is completed or before the drying furnace. The diameter is mainly divided into two sections: 80mm and 60mm. The length is about 4000mm, and about 1000mm is left outside the tappet mud jacket (i.e. outside the furnace): a metal hose is connected to the compressed air interface, and the metal hose is connected to the source of compressed air and equipped with a pressure gauge to facilitate observation of pressure changes; at the end of the conduit Install a ball valve or straight-through valve at the peep hole interface, and install an air outlet peephole behind the valve. After charging the blast furnace, adjust the compressed air pressure in the duct to 0.3~0.4Mpa before supplying air and igniting. After the blast furnace is ignited, observe the changes in compressed air pressure in the taphole duct and observe the furnace hearth through the sight glass. In case of fire, after confirming that the furnace is on fire, you can close the valve at the peep hole interface and remove the peep mirror. When the compressed air pressure of the taphole duct rises to a certain level and after calculation, it is confirmed that the amount of iron in the furnace hearth meets the requirements for tapping, a slag iron pot is installed, full preparations are made in front of the furnace for safe tapping, and then the original installation of the taphole duct is opened Close the valve at the looking glass and close the compressed air valve. The molten iron will automatically flow out along the conduit in an instant, and the steel pipe outside the taphole cover will soon melt. Wait for the gas fire to appear at the taphole, and after confirming that the slag iron has come out clean, follow the normal procedure. Use a hydraulic cannon to block the taphole, and then use an opening machine to open the taphole normally to tap out iron. This creates important conditions for the rapid recovery and smooth opening of the newly opened blast furnace.
Summary of the use effects and advantages of the method of rapid opening of the furnace by introducing compressed air into the taphole
4.1 Use effects
Jinan Iron and Steel No. 1 Ironmaking Plant The method of injecting compressed air into the taphole to open the furnace has been used in the opening of the 350m3 blast furnace No. 3, No. 4, No. 6, and No. 1. Judging from the practice of four on-site uses, the first furnace iron can flow out very smoothly, and The effect is better every time (see Table 1). Table 1 compares the two openings of the four blast furnaces before and after the furnace. Through comparison, it is found that the average opening time of the first furnace iron is reduced by 4.6 hours; a total of 372 oxygen pipes (3.1 tons) are saved: After the blast furnace is ignited, the time to add full wind is reduced by 47.3 hours on average; the average time to reach production is reduced from 8.7 days in the past to 3.1 days; the average coke ratio is reduced by 9.3kg/t when reaching production: spraying starts The coal time has been reduced from 86 hours in the past to 27.8 hours, achieving the goal of quickly starting the furnace and successfully reaching production, and accumulated rich experience for the smooth opening of the first furnace taphole in the future: for the future furnace to be able to timely produce Cleaning slag iron, quickly adding air, quickly lowering the furnace temperature, improving the fluidity of slag iron and accelerating the recovery of furnace conditions, injecting coal in advance, reducing coke ratio, and quickly reaching production and achieving results have laid a solid technical foundation.
4.2 Advantages
Judging from the actual effect of using the taphole to pass compressed air four times to open the taphole, compared with the traditional method of burning the taphole with oxygen, Especially when discharging the first furnace of iron, it has the following advantages: (1) As long as the operator chooses a safe standing position, determines the opening time of the tap hole according to the pressure and time, and opens the valve at the peep hole interface in sequence, and closes the compressed air valve , can achieve safe, fast and smooth iron tapping; (2) It has been proved through 4 uses that the taphole opening time does not exceed 3 minutes each time, so that the taphole can be opened normally in the future, clean slag iron can be discharged on time, and the full airflow in the furnace can be accelerated The process creates conditions; (3) It can significantly reduce the number of operators in front of the furnace and greatly reduce the labor intensity of workers in front of the furnace. Generally, only two people are needed to complete the operation; (4) There is no need to burn oxygen, which can save a lot of oxygen and reduce a lot of Oxygen tube consumption; (5) Since there is no need to burn oxygen, the yellow smoke produced by burning oxygen is eliminated, which effectively protects the environment of the ironmaking plant, reduces environmental pollution, and has significant social benefits.