Foreword

The hot blast stove is the main auxiliary equipment for blast furnace ironmaking, and the burner is the main component of the hot blast stove and the heating device of the hot blast stove. Whether it works normally or not directly affects whether the hot blast stove can provide enough heat for the lattice brick during the combustion period and provide a stable air temperature to the blast furnace. At the same time, whether the burner design is reasonable or not will also affect the service life of the lattice brick. Therefore, the research, design and application of the burner has been placed in an extremely important position by the domestic and foreign ironmakers.

From the history of the development of hot blast stove, it has been 160 years since the application of the hot blast stove in 1857. In this period of more than 100 years of history, with the progress of ironmaking technology, the air temperature provided by the hot blast stove is required to increase continuously. The structure of hot blast stove has also developed from internal combustion type and external combustion type to the current top combustion hot blast stove. Various forms of hot blast stove burners continue to introduce new ones, from the old metal sleeve long flame burner used in internal combustion hot blast stove to the current ceramic short flame burner used in top combustion hot blast stove.

In order to make the burner in industrial applications to meet the hot blast furnace heating to the blast furnace, to provide high air temperature to the blast furnace, to ensure the safe and efficient use of lattice bricks, while ensuring the burner in the combustion and air supply alternate conditions of long-term stable work, is the primary task of hot blast furnace research and design workers.

Characteristics and working principle of various hot blast stove burners

sleeve metal burner

Old internal-combustion hot-blast stoves used metal burners. The air gas enters the fire well through the concentric sleeve arranged horizontally, the mixing effect is poor, and the pulsating combustion is serious.

Fig. 1 Sleeve metal burner

sleeve ceramic burner

Air gas channel and nozzle are made of refractory material. Gas is sprayed upward from the central nozzle, and the combustion-supporting air is divided into small air streams by many nozzles in the outer ring and sprayed to the central gas flow at a certain angle at a high speed, so that the gas and air form a good mixture, and the high temperature zone at the end of the flame is at the vault of the hot blast stove.

Fig. 2 Ceramic Sleeve Burner

grid ceramic burner

Air gas channel and nozzle are made of refractory material. Air gas from the bottom of the burner respectively form a separate interphase channel up to the top through the grid plate into fine strands to achieve better mixing of air gas, this burner flame length is shorter than the sleeve burner, widely used in external combustion hot blast stove use.

Fig. 3 Premixed Ceramic Burner

The premixed ceramic burner is a high-power short-flame burner with few burners and high power. It burns tangentially along the circumference of the vault. The load of the single burner is large, the temperature near the burner is high, the air velocity changes greatly, and the high temperature is concentrated near the burner, which is easy to burn the burner bricks. The characteristics of combustion airflow and temperature distribution can be seen through numerical simulation experiments. The high-temperature flue gas flow swirl from top to bottom along the tangent line of the vault into the lattice brick. The high-temperature flue gas velocity on the surface of the lattice brick is obviously different, the edge velocity is large, the center velocity is small, the temperature distribution on the surface of the lattice brick is uneven, the edge temperature is high, the center temperature is low, and the utilization rate is low.

Fig.4 Schematic diagram of premixed ceramic burner and temperature distribution of simulation

Non-premixed ceramic burner

The non-premixed ceramic burner is a plane swirl burner, with the gas ring on the top and the air ring on the bottom. The air gas is divided into fine strands by the nozzle and ejected at high speed, forming a plane swirl through the throat and mixing in the conical vault space while burning. The central airflow of the burner directly goes down to the lattice brick, and the edge velocity of the high-temperature flue gas distribution on the upper surface of the lattice brick is large and the center velocity is small.

Fig.5 Schematic diagram of non-premixed ceramic burner and temperature distribution of simulation

Three-dimensional hybrid ceramic burner for rotary cutting of cone column

Anneke cone column rotary cutting three-dimensional mixing non-premixed ceramic burner, changing the flow field of the plane swirl burner into three-dimensional cross three-dimensional mixing, better mixing effect, smaller negative pressure area in the center of the burner, and high temperature flue gas on the lattice brick The surface distribution is more uniform, and the lattice brick is more fully utilized. The burner has been successfully applied to 1000 m at home and abroad.³to 3200m³A total of more than 60 blast furnaces nearly 200 hot blast stoves. It has achieved good results in energy saving, environmental protection and high air temperature.

Fig.6 Schematic diagram of cone-column rotary cutting three-dimensional mixed burner and simulation temperature distribution

Research Content and Method of Hot Blast Stove Burner

Main research contents of hot air burner

1) Find the reasonable flame length required by different hot blast stoves by air-gas mixing, and determine the position of the high temperature zone in the center of the combustion chamber (vault). The flame length and the position of the high temperature zone are obtained by the burner structure, the position of the air gas nozzle, the shape and the speed ratio.

2) Through the aerodynamic characteristics of the burner in the combustion chamber (vault) space to find the reasonable parameters of the uniform distribution of high-temperature flue gas generated by combustion in the brick plane, to provide a basis for the rational design of the burner.

3) Refractory materials for burners are studied. Through research to find a match with the burner working environment of the material, both high temperature resistance and good thermal shock resistance, to ensure that the burner combustion and air supply under different conditions can work stably and long life.

Research Method of Hot Blast Stove Burner

Research on the burner of hot blast stove General research is divided into four stages.

1) Digital simulation study: After the preliminary design of the burner is completed, the computer digital simulation study is first carried out to determine its high-temperature aerodynamic characteristics under working conditions and analyze the characteristics of the flow field. It is the prelude of the cold state simulation experiment. After the completion of the digital model simulation, the cold state simulation experiment can be carried out in a targeted manner. Digital simulation research can save manpower, material resources and time, and greatly improve research efficiency.

Fig.7 Temperature distribution of three-dimensional mixing burner for cone-column rotary cutting

2) Cold state simulation experiment: Cold state simulation experiment is an intuitive application of fluid mechanics similar principles (geometric similarity, physical similarity, momentum similarity) to test the aerodynamic characteristics of the burner under working conditions. Through experiments, the motion law of air-gas mixed flow in the combustion chamber (vault) space is found, and the results of numerical simulation are further verified, and the theoretical basis and experimental data are provided for the design optimization of the burner. Such as the shape, number, angle, speed ratio of air gas nozzle, resistance coefficient of air gas channel and nozzle, flame length, airflow distribution and motion trajectory of combustion chamber, etc.

Fig.8 Cold simulation experiment of cone-column rotary cutting three-dimensional hybrid burner

3) Thermal simulation experiment: The thermal simulation experiment device provides an experimental platform for the industrial design of hot blast stove. The experimental device adopts a working system of one burning and one sending. Each test furnace is equipped with 290 thermocouples, several pressure detection points and flue gas composition detection points. The temperature field change, pressure field change and flue gas composition change in different parts and working conditions are verified, and the temperature and airflow distribution law in the furnace are analyzed. Reliable design parameters are provided for improving the combustion efficiency of the burner and the heat storage and release efficiency of the lattice brick.

Fig.9 Thermal simulation experiment of cone-column rotary cutting three-dimensional hybrid burner

4) Hot industrial test: Hot working test is a field test method, a research test method for the actual working condition of the burner in industrial application, and the final identification of the designed burner. The test is carried out during the burning process of the hot blast stove. Special equipment such as high-pressure water-cooled test gun, high-temperature platinum-rhodium thermocouple and matching instruments, U-shaped pressure gauge, bladder for flue gas analysis and the like must be designed and manufactured for the test, and the test must be carried out through the test holes reserved in the manhole of the combustion chamber (vault). The main test contents are the temperature field distribution, pressure field distribution and chemical incomplete combustion rate of air and gas on the section of the combustion chamber (vault) space regenerator under the normal working condition of the burner, so as to judge and identify the quality of the burner. This is a necessary research work for the new burner to be put into industrial application. It is different from the computer digital model simulation research and cold state simulation research. It improves the burner again and makes the design of the burner more perfect and provides direct design reference opinions.

Fig. 10 Industrial application test of cone column rotary cutting three-dimensional hybrid burner

Conclusion

Anneke cone column rotary cutting three-dimensional hybrid ceramic burner has been 1000 m at home and abroad.³to 3200m³A total of more than 60 blast furnaces and nearly 200 hot blast stove projects have been successfully applied.

The hot blast stove with cone column rotary cutting three-dimensional mixed burner has a more compact structure and higher burner power. Under the same design conditions, the use of engineering materials can be significantly reduced, and the engineering investment can be reduced by about 10%-18%. When the energy medium conditions of hot blast stove such as air and gas preheating temperature and gas calorific value are the same, the air supply temperature will be increased by 20 ℃ ~ 30 ℃. Through the collaborative optimization of the aperture, hole type, structure and material of the heat storage brick, the heat exchange efficiency is improved by more than 20%. Three-dimensional hybrid vortex burner NOx emission ≤ 50 mg/m on reasonable air-fuel ratio technology³.

In the future, the development of hot blast stove is bound to be in the direction of high air temperature, long life and low emission. The application of Anke cone column rotary cutting three-dimensional mixed burner has achieved remarkable economic and social benefits, especially suitable for the new construction or transformation of blast furnace in China. Anke will continue to devote itself to the continuous research and optimization of the top-burning hot blast stove burner, and provide the top-burning hot blast stove burner technology with high temperature and long life, energy saving and consumption reduction, and intensive capital reduction for the users of China's iron and steel enterprises.