How to choose the aluminum melting furnace burning with the correct master methods of operation
Aluminum melting furnaces burning fuel is the gradual transition from coal to fuel, and then a gradual transition to the gas combustion process. The manufacture of the melting furnace is also a gradual transition from homemade to specialized kiln factory. The combustion system from the introduction - digestion and absorption - imitation. The burning of gas or foreign level, the automatic control mode in the 1930s and 1940s the level of technology in the 1970s and 1980s. Combustion of the aluminum melting furnace with intelligent control research and development, how to adapt to the "12" energy saving task is very arduous. Put forth to explore how to choose the way of the combustion of the aluminum melting furnace with the proper understanding of the operating method is as follows:
One, how to choose the aluminum melting furnace gas combustion.
An industrial furnace combustion divided into three types according to broad categories: power combustion and diffusion combustion, combustion transition. Burning power: the gas is mixed with air faster than the speed of chemical reactions, the combustion process mainly depends on the chemical reaction rate. Diffusion combustion: gas mixed with air speed below the speed of chemical reactions, the combustion process depends on the mixing speed. Transition combustion: chemical reaction and mixing speed is very close to the combustion process depends on the chemical reaction and mixing rates.
Of the three combustion chamber structure, volume and heat load, which directly affects gas heat of combustion efficiency levels.
2, the basic principles of gas combustion. The combustible gas fuel composition (hydrogen, carbon monoxide, methane, hydrocarbons and hydrogen sulfide) under certain conditions, the intensity of oxidation with oxygen, and produce a lot of heat and light, physical and chemical reaction process called combustion.
Combustion conditions: you must have the combustible ingredients in the gas and oxygen in the air basis having a certain proportion of the molecular state of mixed participation of reactive molecules in the collision must have the energy required for destroying the old molecule, necessary to complete the reaction time.
3, the classification of the gas combustion atmosphere: oxide flame, neutral flame, reducing flame. Greater than the theoretical air ratio in the combustion process known as the oxidizing flame; close to the theoretical air ratio that the neutral flame; less than the theoretical air ratio, said reducing flame. Different heating requirements should be different flame oxidizing atmosphere.
4, what kind of burning burning the fullest? The maximum flame temperature, and power combustion (premixed), followed by excessive burning (half of the premixed combustion of secondary combustion), again for the diffusion-type combustion. Three kinds of combustion from the current level of technology analysis, intermittent burning premix combustion for lower furnace temperature, such as the life of the boiler. The continuous operation of the high-temperature kiln maximize the use of semi-premixed combustion of secondary combustion. To analyze the situation from the combustion technology development, diffusion combustion gradually replaced as a matter of time.
At present, domestic and industrial furnace combustion is basically a diffusion combustion mode, its energy saving potential, such as the use of semi-premixed secondary help oxygen combustion system, the rate of its solar terms in the molten aluminum and insulation aluminum water heaters on up to 15 - 20%.
The two semi-premixed combustion system application effect.
The semi-premixed combustion system is one of the functional combination of combustion systems, it has obtained the national patent (Patent No. 2008.2.0032136.0) it can be adjusted by an \ air volume adjustment of the secondary air to reduce the furnace temperature difference raising and lowering the flame temperature, oxidation by oxygen combustion, reducing Al burning about 1%, reduce energy consumption 15 - 20%. Currently being promoted.
Third, how to master methods of operation.
Industrial furnace heating method of operation for the manual mode of operation. The operator is in the situation of lack of data, entirely based on the experience of the operator operating combustion conditions. According to site statistics, the energy consumption gap between the operator up to 8 - 12%, resulting in the above energy consumption gap causes the following aspects.
1, changing the heating temperature. Such as aluminum melting furnace temperature rose from 750 ℃ to 830 ℃, gas heat utilization from 0.68 to 0.63. The difference of natural gas energy consumption of up to 6.349%.
2, the proper understanding of the combustion air volume (figure 1).
According to this table the coefficient of the combustion air in the exhaust gas temperature under the same conditions, the air ratio compared to 1 and 1.6, the difference larger. Such as exhaust gas temperature of 600 ° C, for example, the air ratio of 1:00, and its thermal efficiency of 73% air coefficient of 1.6, the thermal efficiency of 62%, energy consumption, the gap between the two was 17.7%.
3, the size of the air ratio of aluminum oxide loss (Figure 2).
Is proportional to the metal burning with excess air, the curve shown in the diagram in order to reduce the loss of raw materials, the furnace is running must be properly control the furnace atmosphere. Has been tested and Italy "Black & Decker" diffusion burner, air coefficient of 1.4 (liquefied petroleum gas) will be black smoke, resulting in inadequate combustion is mixed with the gas velocity below the speed of chemical reactions cause.
4, the furnace pressure, the heat loss (Figure 3)
Furnace pressure is too large, the furnace gas to escape the heat loss; furnace negative pressure is too big, serious air leakage, more cold air, resulting in increased heat losses and deterioration of the furnace atmosphere and increase the oven temperature difference. Industrial furnace pressure and the inhalation of air and escape the smoke momentum loss diagrams for furnace pressure of the air intake speed in the negative.
In order to reduce these heat losses in the operation to keep attention to adjust the flue gate in order to maintain the furnace pressure value, pressure value of the normal furnace: furnace and heat treatment furnace bottom at the general control of the zero pressure value.
Furnace pressure measurement points should be placed near the bottom horizontal or door open at the end of the face, to avoid burning Tsui volume inspiratory flow, but also to avoid into a place of the material escaping gas or the inhalation of cold air.
Proper understanding of the balance of the waste tobacco consumption and smoking.
As the flue gas flow conditions a direct impact on the distribution law of the furnace temperature, the correct organization of the furnace air movement, ventilation and lack of power will cause incomplete combustion, increased loss of fuel, the burning intensity weakened; ventilation excessive force, will increase the excess air, uneven temperature distribution, and increase the loss of the hot flue gas.
Intelligent control of the aluminum melting furnace combustion conditions, to ensure safety in production.
1, control the gas flow and air flow to achieve a neutral flame burning.
2, the flue gas the Feedback oxygen content data, adjust the blower speed.
3, according to the size of the furnace pressure, adjust the exhaust gate smoking fan frequency.
4, the safety interlock protection device (hair, ignition, control, gas pressure, the combustion air pressure protection device in series).
Aluminum melting furnaces, combustion devices, and intelligent control of these parameters is bound to achieve 20% energy saving, reduce oxidation loss of 1% of the target, to create conditions for enterprises to reduce