Technique. Without large-scale investment, the internal combustion hot blast furnace was eliminated and transformed into a top-fired hot blast stove; The ball furnace has been transformed into a high-efficiency lattice brick hot blast stove, which has achieved the actual effect of high air temperature. Under the premise of not affecting the safe operation of the air supply system, it is feasible to increase the air temperature by 10-30, and the economic benefits are also very considerable.
The energy-saving technical transformation of blast furnace hot blast stove is mainly divided into: eliminating the internal combustion hot blast furnace and transforming it into a top-fired hot blast furnace; The ball furnace was transformed into a high-efficiency lattice brick hot blast stove.
The traditional internal combustion type is transformed into a high-efficiency top combustion type1.A wide range of high-efficiency burners are available.
The burner is the heart of the hot blast stove. The pre-combustion chamber is divided into two chambers: gas and combustion air. Each chamber has two rows of multiple ventilation channels. Except for a row of holes for the combustion air that enters the combustion chamber in the vertical direction, the other holes enter along the near-tangential direction of the combustion chamber at a certain angle. In the combustion chamber, the air flow forms a spiral shape to achieve the purpose of full mixing and complete combustion of coal gas and combustion air. In the case of full blast furnace gas as fuel, the design hot air temperature can reach 1250°C. In terms of material, mullite iolite and low creep clay bricks are used. In addition, the form of mixed masonry is adopted according to different parts and different uses in masonry.
2.Characteristics of top fired hot blast stove.
1) Low investment. Retain the foundation, shell, wall, platform of the internal combustion hot blast furnace, as well as the outlet elevation of the hot blast stove and the preheating of the combustion air and gas equipment of the flue gas of the hot blast stove. With compact layout and small footprint, under the condition of the same blast furnace volume, the top-fired hot blast furnace saves about 20% or 30% of steel and refractory materials compared with the internal combustion hot blast furnace, thus directly reducing the investment of the hot blast furnace.
2) High wind temperature. The top-fired hot blast stove solves the four major technical problems of "combustion, heat transfer, air flow distribution and structural stability" of the hot blast furnace. The top-fired hot blast furnace has high combustion intensity and high flame temperature, and the heat transfer to the regenerator forms a uniform and stable temperature field distribution in the height direction. The heat exchange process is intensified and the thermal efficiency is improved. The heat storage area is increased by 20% and 30% compared with the internal combustion type, and the hot air temperature can reach 1250. For every 100 increase in hot air temperature, the coke ratio can be reduced by 4% and 7%, and the production can be increased by 3% 5%, and the injection of pulverized coal can also be increased by 40kg t, and the coke ratio can be further reduced by 30kg t.
3) Long life. The diameter of the dome was reduced, and the independent combustion chamber of the internal or external combustion hot blast stove was eliminated, and the vault space was used as the combustion chamber. The temperature in the pre-combustion chamber is generally low, with an average of 900 °C, and there is no direct flame impact and local overheating on the refractory brick lining. This is a hot blast stove with a longevity of more than 25 years.
4) Energy saving and environmental protection. Due to the good mixing of the combustion air of the gas and the complete combustion, the CO content in the flue gas is only 20mg m3. The supply mode of gas and combustion air of the annular burner has been improved, the regulating device has been cancelled, and the vortex supply controlled by the microcomputer has been changed, and the gas and combustion air are well mixed and the combustion is complete.
In addition to the new rotary cutting high-efficiency burner, the supporting technologies include: high-efficiency 19-hole and 37-hole lattice bricks; high-temperature resistant furnace grate; Waste heat**; High-quality refractory materials and optimized design for hot air outlet; Silica bricks or sillimanite bricks are used in the high temperature area to ensure stable work.
The ball furnace was transformed into a high-efficiency lattice brickThe spherical hot blast stove has the characteristics of small size, simple structure, much less material consumption than the internal combustion hot blast stove, and low investment, so it was once popular at home and abroad. It has been well used in many small and medium-sized blast furnaces at home and abroad. At present, the ball furnace has been applied to the blast furnace of 1327m3. However, some ball furnaces do have practical problems such as frequent ball changes, high maintenance costs, low air temperature and long-term stability. In order to pursue higher wind temperatures, there is also a momentum of technological transformation in China.
The ball furnace is changed to lattice bricks, and the burner can be increased by 50-100 at the same time. The hot blast stove fully realizes fast, high-intensity, stable combustion and uniform and high-efficiency enhanced heat transfer, which can increase the hot blast temperature, improve the efficiency of the hot blast stove, enhance the load regulation function, achieve safe and stable operation, and then achieve the goal of saving fuel, saving investment, low-carbon and environmental protection.
Technical measures to slightly increase the air temperatureUnder the premise of not making large-scale investment and not affecting the safe operation of the air supply system, it is feasible to take a small amount of technical measures to increase the air temperature by 10-30, and the economic benefits are also very considerable.
Increase the amount of heat storage unit loadedIn the case that the size and structure of the existing furnace type are not changed, the method of increasing the amount of refractory material can be considered to increase the heating area and increase the air temperature. Preliminary**: Increase the refractory ball or other heat storage to the allowable range, which can increase the wind temperature by more than 10.
Heat storage cladding material with enhanced radiative heat transfer is usedThe high-emissivity coating is applied to the blast furnace hot blast furnace lattice brick, which improves the mechanical properties of the lattice brick. The coating coating changes the thermal properties of the lattice bricks, which can increase the heat absorption of the lattice bricks in the combustion period and the heat release during the air supply period, and can improve the heat storage capacity of the lattice bricks of the hot blast furnace. In the case of overhaul or ball exchange, consider using heat storage cladding materials that enhance radiative heat transfer, including new masonry vaults, large walls and upper refractory balls or lattice bricks, which can be increased by 10-20.
Since 2004, the industrial application of heat storage cladding materials to strengthen radiation heat transfer has been implemented in 338 blast furnace hot blast furnaces of 350mmmmmmm3 in Jinan Iron and Steel, Handan Iron and Steel, Tonggang, Laigang, Qinggang, Weigang, Shiheng Special Steel, Changgang, Xuangang, Anshan Iron and Steel and other enterprises, and achieved good energy-saving effects, and the average air temperature has increased by more than 20, or saving 7% of gas, or extending the air supply time by 10%.
Application case: Comparative test of two hot blast furnaces in the same blast furnace, Jinan Iron and Steel 2 blast furnace (1750m3)1 hot blast furnace is not coated, 2 30 layers of lattice bricks on the hot blast furnace are coated with high-radiation coating. After the lattice bricks in the transition zone are coated with high-radiation cladding, the heating rate in the combustion zone is significantly accelerated, and the decreasing rate is significantly accelerated in the air supply period. This result is consistent with laboratory tests.
Comparison of similar blast furnaces: Jinan Iron and Steel 1 blast furnace (1750m3) as an example to illustrate the application effect of coating on hot blast furnace. 1 The three blast furnaces of the blast furnace were not coated, 3 The upper 30 layers of siliceous lattice bricks and the surface of the vault of the three blast furnaces of the blast furnace were coated with this coating. During the periodic air supply, the temperature of the hot blast furnace is higher than that of the uncoated, with an average of 28 °C. In addition, the fluctuation of the temperature before the supply air is mixed is also less than that of the uncoated one.
Retrofit combustion fanAt present, the air volume of most blast furnace hot blast furnace combustion fans is insufficient, which is mainly due to the different altitudes in different regions, the different relative humidity of the atmosphere in different seasons, and the different pipe resistance and leakage of the combustion air system, and the actual air volume of the combustion fan is 20%-30% smaller than the nameplate air volume under normal circumstances, resulting in the general lack of air volume of the fan. If you want to increase the combustion intensity, you need to modify the combustion fan to increase the air volume or oxygen-rich combustion of the combustion fan. Under the condition of stable gas pressure, ensure that the air temperature can be increased by 10-30.
Intelligent combustion control system is adoptedThe blast furnace hot blast furnace intelligent control combustion system technology is to transform the existing blast furnace hot blast furnace furnace
1.Technical characteristics of intelligent control combustion system.
1) Realize the automatic adjustment of the air-fuel ratio of the hot blast furnace combustion in stages, so that the gas flow and air flow of the hot blast furnace are in the best ratio state as far as possible, and the whole combustion process is automatically completed.
2) It can automatically switch the control scheme according to the fluctuation of the gas pressure in the external network.
3) It can ensure that the hot blast stove is in the best proportioning state most of the time, stabilize the vault temperature, and prolong the service life of the hot blast stove no matter in the rapid heating period or in the holding period.
4) It can save the consumption of blast furnace gas, reduce the energy consumption of the ironmaking process, and improve the economic and social benefits of the enterprise.
5) It can greatly reduce the technical requirements for hot blast furnace operators to burn the furnace and reduce its labor intensity.
6) It can be switched with the original control system without disturbance, and it can be used as a backup for each other, which can avoid the impact on normal production when switching.
2.Expected technical indicators.
1) Increase the wind temperature by about 10 15.
2) The temperature of the vault is controlled smoothly, which can inhibit the fluctuation of the vault temperature during the furnace process.
3) The time to overcome gas pressure fluctuations is 25s.
4) Under the same conditions, the gas saving is about 2% 10%.
5) The heating time can quickly increase the temperature of the vault by 10min.
Efficient double preheating methodIf the hot blast stove has a waste heat system, if the temperature of the preheated air and gas is not too high, a plate heat exchanger with a combustion furnace can be used. Can preheat the temperature to double 250--300. Increase the air temperature by 50-80.
Without large-scale investment, the internal combustion hot blast furnace was eliminated and transformed into a top-fired hot blast stove; The ball furnace is transformed into a high-efficiency lattice brick hot blast stove, which can achieve the effect of high air temperature. Under the premise of not affecting the safe operation of the air supply system, it is feasible to take a small technical measure to increase the air temperature by 10-30, and the economic benefits are also very considerable.