Talking about Several Energy Saving Ways for Glass Furnace
[Summary description] The main energy-consuming part in a glass factory is the glass kiln (whose energy consumption accounts for more than 75% of the total energy consumption). Therefore, it is a top priority to pay close attention to the energy saving of the glass kiln.
The main energy-consuming part in a glass factory is the glass kiln (whose energy consumption accounts for more than 75% of the total energy consumption). Therefore, it is a top priority to pay close attention to the energy saving of the glass kiln. Over the past few years, we have taken many energy-saving measures in terms of glass frit, feeding system, combustion system, kiln structure, kiln body insulation, waste heat utilization, and operation control, and have achieved great results. The fuel consumption indicators of many factories have dropped significantly. Some factories have reached the level of first-class furnaces or special furnaces. But compared with foreign countries, there is still a big gap.. So we have to work hard to further reduce energy consumption. Several ways to save energy are proposed below:
First, increase the temperature of the liquid glass without increasing the flame temperature
When the temperature of the liquid glass increases, the melting speed can be accelerated, the melting time can be shortened, and the output can be increased and the unit consumption can be reduced. The specific methods are:
(1) Increase the radiant heat of the flame space to the glass liquid.
1. Liquid glass selectively absorbs radiant energy. Energy with a wavelength of less than 3 microns is transmitted down through the liquid surface. It is the carbon particles in the flame and the surface of the inner wall of the kiln space that can eject radiant energy with a wavelength of less than 3 microns. Therefore, increasing the blackness of the flame (by means of oxygen-deficient heat medium or carbon addition measures) and maintaining the blackness value of the kiln masonry high (related to the roughness and temperature of the masonry surface. The blackness value of clay bricks and silicon bricks at high temperature is: 0.61-0.62 at 1000 ° C, 0.52-0.53 at 1200 ° C, and 0.47-0.49 at 1400 ° C. At high temperature, the blackness value of fused refractory bricks is 0.4-0.5), which can increase the radiant heat of the flame space to the glass liquid.
2. Eliminate the "cold air" film near the liquid surface. Pay attention to the height of the baseplate of the small furnace from the liquid surface and the angle of flame ejection. Oxygen blowing and melting measures can also be considered (after foreign countries blow in oxygen at a speed of 195-500 m/s, the heat transfer speed is accelerated, and the flame temperature near the liquid surface is increased by about 100 ° C).
(2) Improve the temperature or temperature uniformity of the glass liquid in the kiln tank.
The point of view is to increase the heat transfer of the flame to the liquid glass by reducing the liquid surface temperature. When the liquid surface temperature decreases, the uniformity of the temperature of the liquid glass in the direction of the pool depth is also improved. The measures taken to realize the above point of view are: 1. Bubbling at the bottom of the pool (pay attention to the purification of the bubbling medium and the erosion of the bubbling bricks). 2. Deepen the depth of the pool. It can intensify the convection in the vertical direction, which improves the temperature uniformity of the liquid glass in the pool depth. At the same time, it also adapts to the improvement of the melting rate. 3. Kiln body insulation. 4. Electrically assisted melting.
Second, shallow clarification, deep reclaiming, control liquid flow in the direction of single channel DC
This is from the point of view of increasing the temperature of the glass liquid in the clarification area, reducing the backflow and selecting high-quality glass liquid to enter the liquid cavity. This can improve the output and quality of the glass liquid and reduce the loss of the reflux glass liquid. The measures taken to realize the above point are: set a low and wide kiln to reduce the shallowness of the clarifier to sink the liquid cavity (no sinking when melting dark materials).
Third, strengthen homogenization
Most factories report that homogenization is a key process that affects product quality. At present, the homogenization process is basically in a state of "congenital deficiencies and acquired imbalances". It is difficult to maintain the uniformity of the mixture after entering the kiln, resulting in uneven composition. The heat permeability of the liquid glass and the heat dissipation to the surrounding of the kiln cause uneven temperatures. Relying on natural diffusion alone for homogenization is obviously not satisfactory. For this reason, measures of forced homogenization must be taken. The current effective measures are: low bubbling in the pool (the most obvious for dark materials), stirring in the material channel, discharge of material from the bottom of the working material or material channel (with leakage holes) and electric heating of the material channel. When using stirring measures, pay attention to the position of the stirring point, the insertion depth of the stirrer and the stirring process, otherwise the ideal effect will not be obtained. The material of the domestic stirrer is an urgent problem to be solved. The surface liquid flow can not only strengthen the lateral flow\ improve the temperature uniformity, but also pull away the dirty material and crusts on the liquid surface. The size of the ear should be appropriate, do not cause too much heat loss, and the discharge can be continuous or intermittent. Electric heating can significantly improve the temperature uniformity in the depth direction of the feed channel pool, but the temperature distribution from the material to the horizontal plane may not improve. The shape of the electrode, the determination of the glass resistance between the electric bases, and the methods of electrode adjustment, installation and maintenance are the issues that need to be paid attention to when using heating. While taking forced homogenization measures, the role of natural diffusion should still be fully exerted. Therefore, the size of the working part and the length of the feed channel should be carefully considered in the design.
Fourth, stable supply
The stability of the shape, size and temperature of the material is the premise to ensure the quality and output of the molding. The degree of separation between the feed channel and the working part, as well as the section, size, heat preservation, heating system and cooling system of the feed channel are the main factors affecting the stable feeding. The full separation between the feed channel and the working parts can keep the material channel in an independent operation system without interference. Some factories do not need full separation, and the practice of heating the material channel by the heat of the melting part is debatable. The saddle-shaped cross-section at the bottom of the material channel can reduce the transverse temperature difference. Appropriate deepening of the material basin can increase the static pressure head and stabilize the temperature of the material droplet. The length and width of the material passage should be determined according to the amount of material flowing and the size of the output. A longer material passage is beneficial to adjust the temperature, and can adapt to changes in the amount of material flowing in a larger range. The heat dissipation of the material passage is very large, especially at the material basin. So it is necessary to strengthen heat preservation. The heating and cooling system should be able to adjust the temperature of the liquid glass flexibly and reliably, and maintain the uniformity of the temperature. The cooling system plays a coarse role, and the heating system plays a fine role. Most people think that a combination of multi-nozzle gas heating and electric heating is ideal.
Fifth, reduce useless heat
(1) Reduce the heat that cannot be used, such as the heat dissipation on the surface of the kiln body, the radiant heat of the orifice, and the heat carried away by the gas escaping from the orifice and the brick joint. The measures taken are: 1. The heat preservation of the kiln body. The use of kiln body heat preservation in my country has achieved remarkable results for several years. But it is only in the initial stage, and the heat preservation effect can be further improved. The direction is to engage in multi-layer combined thermal insulation layers, adopt composite (such as sandwich type, filling type) thermal insulation materials, develop bulk concrete thermal insulation materials, and develop sealing materials matched with various refractories. 2. Sealing of orifices and brick joints. Pay attention to the feeding port, temperature measuring hole, fire hole, etc. If conditions permit, a fully enclosed charging machine (such as spiral type, wrapping type) should be used, corundum embedded pipe should be used to measure temperature, and industrial TV should be used to observe flame and chemical material conditions. 3. Large-scale kiln. The larger the kiln scale, the lower the heat dissipation per unit output.
(2) Reduce the heat of repeated heating. The main thing is to reduce the heat consumed by repeated heating of the reflux liquid glass (usually, this heat accounts for about one-tenth of the heat consumed by the melting of the glass). The measures taken are: setting a kiln, sinking the flow hole, appropriately reducing the height of the flow hole and appropriately reducing the temperature of the glass liquid entering the flow hole.
Sixth, the use of available heat
(1) The fuel should be fully burned to release all the heat. To this end, when burning oil, choose an oil nozzle with good atomization effect, adopt measures to strengthen atomization, and design a small furnace structure and parapet height that are matched with the nozzle. When burning gas, determine the appropriate air-gas dynamic ratio, and surround the gas with air.
(2) Improve the heat exchange efficiency and increase the air preheating temperature as much as possible. For this reason, it is necessary to increase the heating surface area of the lattice brick, use a higher lattice body, and use novel lattice bricks and their arrangement methods (such as cross-shaped and cylindrical bricks). Arranged in basket type or chimney type). Also study the material of the lattice brick and the uniformity of the airflow distribution in the lattice (the uniformity of airflow distribution is directly related to the utilization rate of the lattice brick. Factors affecting the uniformity of distribution include the construction coefficient of the lattice body, the ratio of the channel volume of the upper and lower parts of the lattice body to the volume of the lattice body, etc.).
(3) Waste heat utilization of flue gas. The heat carried by the flue gas discharged from the regenerator should be recovered as much as possible under permissible conditions. Many factories have set up waste heat boilers in the flue system. Some factories have also installed heat pipes to recover heat. In addition, how to use the waste heat of flue gas to heat and even sinter the mix should be studied.
Seventh, changing the material side and spheroidizing the mixed material
(1) Adding a small amount of fluxing components to the material side, such as lithium mica, can reduce the melting temperature of the glass and accelerate the melting of the glass. The discharge amount increases significantly.
(2) Spheroidization of the compounding material. The setting treatment of the compounding material is a topic of concern to everyone. We advocate dry spheroidization. The compounding material is pressed into small pellets without binder. It can eliminate dust inside and outside the kiln, accelerate the solid phase reaction, and increase the contact area between the compounding material and the glass liquid. In this way, the melting time and the furnace age can be shortened, and the unit heat consumption will also be reduced.
Eighth, the use of high-quality refractory materials and reasonable matching
At present, it is recognized that various high-quality and durable refractories must be used (such as capacitive refractories, zirconium, chromium, corundum, spinel and alkaline refractories, high-density, high-strength refractories, etc.) and given reasonable matching, so that the overall service life of the kiln increases simultaneously. As we all know, the quality of furnace building materials is very important to the influence of kiln output, glass quality, fuel consumption and furnace age. Compared with foreign countries, there is still a considerable gap in the variety, specification and quality of refractories used in glass kilns in my country. It is urgent to change this situation. We should also expand the use of high-quality refractories. From a long-term point of view, it is worthwhile to spend more money on refractory materials. The energy saving of glass kilns involves a wide range and requires the cooperation and joint efforts of many parties to be effective.
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