Optimization and application points of energy-saving technol

1. Melting tank design and selection of refractory materials

During the melting process of the electric melting furnace, the glass is vertically distributed from top to bottom. The top of the cold furnace, which is covered by the batch, is mainly heated by the electrode in the liquid glass. The temperature gradient of each layer changes, and it can be controlled in layers. Therefore, it is required that the depth of the melting pool of the electric melting furnace must reach the standard, and the depth of the melting pool of the high borosilicate glass production furnace must be> 2m. The melting tank is composed of an upper melting section and a lower clarifying section. The melting section mainly includes a batch covering layer, a silicate layer, and a glass layer. The clarifying section is mainly a homogenizing zone, a cooling zone, and a clarifying zone. The production process of the electric melting furnace is a series of fast, short-term and intense physical and chemical reaction processes, so the space required in the melting section is small, and the glass must be passed through the raw material layer after the bubbles are released. This requires time and space, so The clarification section is relatively large.

 

Different from fuel oil and gas flame furnaces, the selection of refractory materials in electric melting furnaces pays more attention to the material's high temperature resistance, corrosion resistance and electrical conductivity. Refractory materials with higher electrical conductivity have greater potential safety hazards due to possible ignition, melting, and leakage during operation. Therefore, the selection of refractory materials is also one of the important topics for the optimization of energy-saving technologies for electric melting furnaces.

 

2. Fluid flow hole design

The liquid flow hole is an inevitable channel for rising after cooling of the liquid glass and it is also a weak link in the electric melting furnace. It is easy to be eroded. Therefore, attention must be paid to the design of the electric melting furnace. Hole cover brick erosion and other problems.

 

The glass liquid flows out of the melting pool and passes through the flowing liquid hole to reach the ascending channel. If the outflow exceeds the discharge amount, the surplus part will flow back to the melting pool. The subsequent secondary heating will increase the energy consumption of the kiln. However, this process can perform secondary homogenization of the reflux glass liquid to avoid quality defects, so in practice, it is necessary to find a balance between energy consumption and glass liquid quality. Specifically, during the design process, the reasonable size of the cross section of the flow hole should be ensured. For an electric melting furnace with a discharge capacity of 30t, the cross section should be maintained at 900 cm2; the height of the flow hole should be controlled to reduce the erosion of the cover tile. The height of the flow hole should be controlled at 20 ~ 30cm; the length of the flow hole should be increased, and the current flow hole length of the electric melting furnace should be maintained at 2 ~ 3m.

 

In order to control and mitigate the erosion of the cover brick of the flow hole, in practice, AZS41 fused zirconium corundum brick can be considered, and the design of the settlement flow hole is used to ensure that the position of the flow hole is far below the bottom of the pool. , The temperature of the glass liquid will reduce the erosion of the cover tile. In order to ensure the performance of the cover tile and extend its service life, effective measures should be taken to cool the cover tile in the middle and late stages of use of the electric melting furnace.

3. Electrode and power distribution

At present, molybdenum electrodes are commonly used in electric melting furnaces. There are three types of electrode insertion methods: bottom insertion, horizontal insertion and top insertion. Manufacturers generally improve the bottom insertion method and use the side insertion method. This technology can effectively ensure the electric field distribution and glass. Although the uniformity of the liquid needs to be opened in the bottom of the cell, as long as the current density is properly selected and the electrode is pushed in time when the electrode is worn, the possibility of material leakage in this side insertion method is very small, and due to the high viscosity of the bottom of the cell The protective layer can effectively protect the bottom material and electrode hole from erosion, and the safety is still guaranteed.

 

The electrodes and power should be evenly distributed, and multiple pairs of electrodes and multiple transformers should be evenly arranged. The diameter of the electrodes and the capacity of a single transformer should not be too large. The uniform distribution of the electrodes can prevent the occurrence of bias currents and ensure the uniformity of power lines and thermal energy. Distribution and stability of the melting process.

 

In addition, at the beginning of the operation of the electric melting furnace, it is often encountered that the voltage is low, the current is too large but the power is not high. In order to increase the power, the current should be increased first, but it should be noted that too high current may break through the molten electrode brick and Burning electrical control machinery and equipment will affect the melting quality of the material. In order to prevent the above phenomenon, it is necessary to keep the glass solution in the glass furnace to melt uniformly and to have equal resistance at different points. Especially in areas with low resistance, the possibility of bias current is greater. The bias current will inevitably cause phase deviation, which will cause the entire electric melting furnace Unbalanced electrical power and uneven melting.