Tongling city xuanli special steel co., ltd. 1# blast furnace was built in 2011, with a blast furnace volume of 846m and a blast flow rate of 2900nm/min. it is equipped with three big hat ring burners for top-burning hot blast stove. The hot blast stove has been used for less than 9 years, and the big hat arch (Figure 1) and the hot air outlet (Figure 2) have been seriously damaged, and the technical performance of the hot blast stove has decreased significantly, mainly as follows:

(1) The big hat arch of the hot blast stove, the hot air outlet, the pipe lining and the furnace shell are damaged in many places. After many repairs, the safety hazards cannot be eliminated;

(2) The resistance loss of the hot blast furnace system has increased significantly, of which the pressure difference between cold and hot blast of No. 1 blast furnace is basically normal at 6 kPa, but the pressure of No. 2 and No. 3 has deteriorated seriously, reaching a maximum of 15 kPa, causing frequent fluctuations in the hot blast pressure of the blast furnace between 385 and 395kPa, adversely affecting the stable operation of the blast furnace and increasing the power consumption of the blower;

(3) The hot air temperature is low, which can only be maintained at about 1100 ℃ at present, which is 100~150 ℃ lower than that of similar blast furnace, and the cost per ton of iron remains high.

At present, two of the three hot blast stoves have been seriously damaged, and repeated repairs are still useless. If one hot blast stove is stopped for offline maintenance, it will have a serious impact on blast furnace production. For this reason, the owner plans to build a new (4#) hot blast stove first, and then transform the existing hot blast stove one by one after it is put into production.

Zhengzhou Annike Hot Blast Stove Engineering Technology Co., Ltd. was invited to participate in the bidding for the new hot blast stove. Before the bid, Annike, together with the owner, conducted a comprehensive assessment and analysis of the current situation and damage of the hot blast stove, with the goal of reducing investment, ensuring the construction period and meeting the service of the second generation furnace for more than 30 years, formulated a feasible implementation plan for the new hot blast stove and successfully won the bid for the project.

The new and modified hot blast stove adopts the cone-column rotary cutting top-burning hot blast stove technology jointly developed by Anke and MCC Jingcheng. This technology integrates the advantages of various hot blast stoves at home and abroad, and forms a series of core technologies with completely independent intellectual property rights through independent innovation. It has significant advantages in improving hot air temperature, extending the life of hot blast stove, improving thermal efficiency, energy saving and emission reduction, and reducing investment.

1, single burning blast furnace gas to achieve high air temperature above 1250 ℃

The burner of the cone-column rotary cutting top-fired hot blast stove adopts the key technology of air gas space swirl and radial trickle high-speed injection, which is evenly mixed and realizes stable short-flame combustion in the vault space. The air excess coefficient realizes complete combustion of gas under 1.03 conditions, which increases the combustion temperature of gas by about 20 ℃ compared with other hot blast stoves. Its unique enhanced combustion and enhanced heat exchange technology combined with reasonable heat accumulator design, reduce the difference between vault temperature and air supply temperature to less than 80 ℃. The high air temperature above 1250 ℃ can be realized under the condition of single combustion of blast furnace gas and double preheating of air gas.

2. The service life of hot blast stove body and pipeline is more than 30 years

The cone column rotary cutting top burning hot blast stove adopts 72 patents and proprietary technologies, such as three-stage independent structure, easy purging and non-displacement three-dimensional burner, rectifying and guiding device in return flow area at variable diameter, plate interlocking flat arch roof, multi-ring interlocking anti-channeling hot blast outlet, high-efficiency small hole lattice brick edge brick positioning mosaic, "Z-shaped" self-locking closed pipeline, combined brick pouring three-fork, etc, thoroughly solve the top-burning hot-blast stove burner nozzle dislocation brick, hot-blast outlet and arch collapse, hot-blast stove lattice brick sinking, hot-blast pipe main branch pipe three-way fork collapse and other problems, to achieve a stable hot-blast stove system for more than 30 years.

3. The thermal efficiency of the hot blast stove system is more than 90%

The cone-column rotary-cutting top-burning hot-blast stove adopts a three-dimensional mixed high-efficiency burner, which has a small air excess coefficient, improves fuel utilization, reduces combustion-supporting air consumption, and achieves a higher vault temperature. Its unique three-dimensional mixed combustion technology shortens the flame length, saves the combustion space, the furnace design is more compact, and the heat dissipation area of the furnace shell in the high temperature zone is smaller than that of other top-burning hot stoves. In order to improve the life of the furnace shell and reduce heat loss, the thermal insulation layer of the cone-column rotary-cut top-burning hot blast stove is sprayed with low thermal conductivity materials and the surface of the furnace shell to ensure that the temperature of the upper furnace shell of the combustion chamber and the regenerator is less than or equal to 80 ℃, and the temperature of the furnace shell in other parts is less than or equal to 60 ℃. The hot blast stove flue gas adopts high-efficiency heat exchange system for waste heat recovery, and the overall thermal efficiency of the hot blast stove reaches more than 90%.

4. Blast furnace gas consumption reduced by 5%

The three-dimensional mixing burner of the cone-column rotary cutting top-fired hot blast stove is fully mixed, completely burned, energy-saving and efficient. Gas nozzles are distributed on the cone section of the burner, with multiple rows of nozzles with different mixing radii rotating downward movement, forming three-dimensional mixing with the lower air nozzles, saving more than 5% of gas compared with other forms of hot blast stoves.

5, NOx emissions are lower than the national ultra-low emission standard 65%

The cone column rotary cutting top-burning hot stove technology realizes stable combustion under ultra-low air excess coefficient, the heat transfer area of the heat storage body grid brick and the heat storage volume are both balanced, and the thermal efficiency is higher. When the vault temperature is ≤ 1330 ℃, the air supply temperature is ≥ 1250 ℃, the NOx emission is ≤ 50 mg/m, and the NOx emission is more than 65% lower than the national ultra-low emission standard.

After the completion of the new hot blast stove project, the other three existing hot blast stoves will be repaired in turn under the premise that the blast furnace will not stop production. After the repair, all the hot blast stoves will adopt the technology of cone column rotary cutting top burning hot blast stove, it can completely solve a series of problems that plague steel plant users, such as dislocation of burner (mixing chamber) nozzle, damage of vault (combustion chamber), deformation and collapse of hot air outlet, brick falling of hot air pipeline, slag sinking of lattice brick heat storage body, and running wind at the bottom of furnace. Since 2010, more than 1000 new and renovated hot blast stoves have adopted Annike's technology and products, and none of the above problems have occurred so far.

Fig. 1 Damage to the vault of the top-fired hot blast stove of the original big hat annular burner

Fig. 2 Damage of Hot Air Outlet of Top-fired Hot-blast Stove with Original Big Hat Annular Burner