Innovative furnace opening scheme

Hebei Xinda Iron and Steel Group Co., LTD. Ironmaking plant

The opening operation is the necessary link of the blast furnace to achieve normal production in ironmaking production, there are some problems such as high consumption, affecting the production of pig iron, so shortening the opening process and quickly achieving normal production has great practical significance for reducing the opening cost of the blast furnace process and improving the quality of pig iron.

scaling

Hebei Xinda Iron and Steel Group Co., LTD. Ironmaking factory happy innovation studio for the problem of blast furnace opening operation time, combined with the practical experience of the ironmaking plant to carry out research, the blast furnace opening time compression and compression, the proposed target opening time of 48 hours.

Search for the cause

After determining the target, Xing Xing et al. found through the cause-and-effect diagram analysis that the main reasons for obstructing the furnace opening process were slow air addition after ignition opening, non-movement of the material column or even suspension of the material, and difficulty in discharging the first iron slag. The slow process of air loading is due to the poor permeability of the material column, which is also the cause of the slow movement of the material column or even the suspension, resulting in the low temperature of the furnace top and the delay of the gas extraction operation. The difficulty of discharging the first iron is mainly due to the low temperature of the furnace cylinder after the furnace is opened, and the slag iron entering the furnace cylinder is absorbed by the heat of the furnace cylinder, resulting in insufficient physical heat and poor fluidity of the slag iron.

After using tools such as logic tree and cause-and-effect diagram to confirm the main causes, the discussion was carried out to find the countermeasures, which were applied in the furnace opening practice, and the scheme was constantly modified by observing the effect. Then the PDCA cycle method was verified in the next furnace opening practice, and the project scheme was modified and improved according to the feedback of the results, and a relatively perfect scheme was finally formed for curing.

Give a policy

The speed of the furnace depends on the speed of air and the discharge of the first slag iron, and the speed of air depends on the action of the material column. If you want the material column to operate smoothly, there must be space for cutting, the material column must be permeable, and the reaction in the furnace must be rapid; In order to successfully discharge the first iron, the furnace cylinder should have enough heat and the chemical composition of the slag iron should be reasonable. According to the main factors affecting the furnace opening speed, Happy et al. determined the operation plan one by one.

The furnace cylinder is directly filled with coke. When it comes to the tuyere area, throw some firewood from the manhole along the tuyere ring of the blast furnace, and then continue to fill the coke, and the wood filling volume is about 50m³;

 When loading to empty coke, the charging system is changed from CC+NN cycle (C represents coke and N represents auxiliary materials) to CC+NNC cycle, NNC cycle uses double ring cloth, so that auxiliary materials form an outer ring, coke cloth to the center area;

 When distributing load material, from CC+OO (O stands for load material) cycle to CC+OOC cycle, according to the material line using multi-ring fabric, so that the load material forms an outer ring, coke cloth to the center area, forming a central coke material column;

 The load material changes the original pursuit of high clinker ratio of the batching method, with high-quality ore instead of pellets;

 Before or at the same time of opening the furnace, the furnace cylinder uses online oxygen gun technology to ignite the coke in the furnace cylinder for oxygen combustion.

gist

Fill the tuyere area with a small amount of wood: The fire point of the wood is low, and it will burn the coke in the tuyere area quickly after ignition, and provide a small amount of space for the descent of the unfueled column.

The use of on-line oxygen gun in the furnace cylinder can effectively store heat for the furnace cylinder, accelerate the heating rate of the furnace cylinder, and help the slag iron formed during the furnace opening process to maintain a high physical heat and better fluidity, laying the foundation for the smooth discharge of the first furnace slag iron; It can also make the furnace cylinder quickly form a certain space, which is conducive to the movement of the blast-charge column.

The change of load material ratio: the reduction property of PB block is 20% higher than that of pellets, the thermal explosion property is 8%, and the expansion rate of pellets is about 20%. PB block has high softening temperature and short melting interval. Using PB block instead of pellet can improve the reaction speed in furnace.

The purpose is to form a central coke material column, improve the permeability of the furnace after opening, prevent the suspension of the blast furnace, which is conducive to speeding up the process of adding air, but also conducive to the rapid increase of the temperature of the furnace top, and lay the foundation for the rapid gas work.

achievement

After the implementation of this project, Hebei Xinda Iron and Steel smelting plant completed the furnace operation in only 48 hours, and it is estimated that the fuel cost will be saved by about 12 million yuan in 2022, the cast iron damage cost will be reduced by about 12 million yuan, the normal production time will be extended, and the quality qualification rate of hot metal will be improved.

At the same time, through the implementation of this process technology, an invention patent and two utility model patents were also developed and declared for "A blast furnace opening charge column structure", "a blast furnace opening charge column structure and charging method", and "a furnace cylinder ring oxygen gun for blast furnace opening".

"Solve professional problems with professional thinking, and tap the potential of efficiency reduction with fine management." Each of the independent improvement and innovation results shows the infinite independent innovation talent and potential of the staff, which has a positive promotion and promotion significance for optimizing the process and improving the production index. Independent improvement is a long-term and complex systematic project, which requires the joint participation of every employee and the continuous deepening and scientific promotion of the improvement work. Companies should take active actions and participate deeply, further build a good platform for employees to improve themselves, guide employees to find problems, analyze problems, and solve problems based on their positions, and form a good environment of "everyone thinking, everyone doing things, and working together to accomplish things", and make positive contributions to the green and high-quality development of enterprises.