First, the influence of furnace structure
The furnace type, the structure and size of each part of the furnace body, the materials used in the furnace and the structure of auxiliary equipment all belong to the factors of furnace type structure. The furnace structure design should be reasonable and the masonry quality should be qualified. Furnace structure has a great influence on productivity, and improving productivity can be considered from the following aspects.
1, adopting new furnace type. The general development trend of heating furnace is large-scale, multistage, mechanization and automation.
2, transform the old furnace type. (1) Enlarge the furnace and increase the charging amount. (2) Improve the furnace type and furnace type to make it more reasonable. (3) Reduce the heat loss of the furnace. The heat loss conducted through the furnace body and the heat taken away by the cooling water account for 1/4~ 1/3 of the furnace heat load, which not only wastes heat energy, but also lowers the furnace temperature and affects the heating of steel. Reducing this loss can increase the output of the furnace.
Second, the influence of combustion conditions and heating intensity
With the increase of heat load, the temperature level of the furnace is improved, the ability of heat transfer to metal is strengthened, and the output is bound to increase. The important measures to improve the heating intensity of continuous heating furnace are to increase the heating point, expand the heating section and improve the temperature level of the heating section. An important prerequisite for increasing heat load is to ensure the complete combustion of fuel. If 20% of the fuel cannot be burned in the furnace, the output of the furnace will be reduced by 25% ~ 30%. Therefore, in order to improve the heat load or combustion conditions, we should pay attention to improving the combustion device and effectively improve the productivity of the furnace.
Third, the influence of loading conditions
Under certain heating conditions, the thicker the billet and the longer the heating time, the lower the productivity of the furnace. In addition, the temperature of billet entering the furnace has an important influence on the productivity of the furnace. The higher the charging temperature of steel, the shorter the heating time and the higher the productivity of the furnace. According to statistics, for every 50℃ increase of billet surface temperature, the furnace production capacity can be increased by 7%. Therefore, we should try our best to improve the hot charging rate of heating furnace.
Fourthly, the influence of technological conditions.
The most reasonable heating temperature, heating speed and temperature uniformity should be considered when making the heating process. Because the types and cross-sectional dimensions of metals often change, the heating process should be adjusted accordingly. If the heating temperature is set too high, the heating speed is too fast, and the sectional temperature difference is too strict, it will affect the productivity of the furnace.
The fuel consumption and thermal efficiency of heating furnace are important indexes to evaluate the heating work of heating furnace. From the heat balance table of the furnace, we can see the utilization of heat in the furnace. Of all the heat expenditure items, only the part of the heat for heating the metal is effectively utilized, and the others constitute the heat loss of the furnace. If all kinds of heat losses are reduced, oil consumption will inevitably decrease. There are four main ways to improve furnace thermal efficiency and reduce fuel consumption.
First, reduce the heat taken away from the furnace by the exhaust gas.
On the premise of ensuring the complete combustion of fuel, reduce the air consumption coefficient as much as possible to increase the combustion temperature and reduce the amount of exhaust gas.
Attention should be paid to the sealing problem of the furnace, and the furnace pressure should be controlled at a slightly positive pressure level to prevent cold air from being sucked into the furnace, increase the flue gas volume of the furnace and reduce the combustion temperature.
Reasonable exhaust gas temperature should be controlled. The higher the exhaust gas temperature, the more heat the exhaust gas takes away and the lower the thermal efficiency. However, the exhaust gas temperature is too low, the average furnace temperature level in the furnace decreases, the heat exchange in the furnace deteriorates, the heating is too slow, and the productivity of the furnace decreases. Therefore, the correct approach should be to maintain high productivity and reasonable exhaust temperature. As for the heat contained in waste gas, measures should be taken to recover it in order to improve thermal efficiency and reduce fuel consumption.
Second, reduce the heat carried away by cooling water.
In order to reduce the heat taken away by cooling water, the measures taken are: reducing unnecessary water cooling area, insulating water cooling pipes and adopting waterless slide rails.
Third, reduce the heat dissipation of furnace masonry.
The main measure to reduce heat dissipation of masonry is heat preservation. The use of lightweight refractories and various thermal insulation materials can effectively reduce the heat loss through masonry.
Fourth, strengthen the thermal management and scheduling of the furnace.
The high fuel consumption and low thermal efficiency of the furnace are often not caused by technology, but by poor management and scheduling. For example, the mismatch between steel billet and heating furnace reduces the hot charging ratio and billet temperature of the furnace. Another example is the poor coordination between the heating furnace and the rolling mill, and the billet is waiting to be rolled in the furnace, which also causes the fuel consumption to increase and the thermal efficiency and productivity to decrease. Therefore, the furnace should keep a balanced operation under the rated output to realize the optimal control of various thermal parameters.