Compared with traditional technology, modern glass production technology has made a qualitative leap, and it is developing in the direction of higher efficiency, lower energy consumption and better product quality. As the core equipment of glass production, the technical level of kiln is constantly improving, and new technologies such as improving combustion intensity, strengthening heat transfer effect, reducing heat loss and reducing pollution to products and environment are widely adopted. Keywords: evaluation technology of new progress of refractories for glass kiln
1. China's glass industry has developed rapidly, and it has already become the largest glass producer in the world. The rapid development of glass industry has naturally promoted the development and technical progress of refractories for glass kilns in China. Compared with traditional technology, modern glass production technology has made a qualitative leap, and it is developing in the direction of higher efficiency, lower energy consumption and better product quality. As the core equipment of glass production, the technical level of kiln is constantly improving, and new technologies such as improving combustion intensity, strengthening heat transfer effect, reducing heat loss and reducing pollution to products and environment are widely adopted. The technical progress of kiln requires a variety of high-quality refractories as the guarantee conditions, and requires refractories to withstand higher temperatures, more drastic temperature changes, more intense chemical erosion, and more severe stress damage. Only by supporting the application of a variety of high-quality refractories can the advantages of new kiln technology such as high efficiency, energy saving and low pollution be realized. High-quality refractories are not only consumable materials for modern high-temperature technology, but also functional materials necessary for realizing new high-temperature technology.
2. Introduction of the new development of refractories for glass kilns abroad 2.1 AZS and high zirconia bricks are mainly used to improve the corrosion resistance and wear resistance of fused AZS bricks, except that the carbon content of the products is reduced to 0.005% by oxidation melting, and the glass phase precipitation temperature is increased to 1450℃. The casting and annealing processes have also been improved, and the fused AZS with small shrinkage cavity volume or even no shrinkage cavity has been produced. High-zirconia bricks with more than 90% ZrO2 have excellent thermal shock resistance, such as > 95% ZrO2 and < 1.4% SiO2. The high zirconia brick with stabilizer < 3.7% has a bulk density of 4.7g/cm3, porosity < 18.4% and thermal shock resistance of 15 ~ 20 times from room temperature to 1400℃(15-minute interval). A kind of fused-cast zirconia brick is produced in Japan. Its zirconia content is more than 90%, which is called ZFC brick. Its corrosion resistance is better than that of AZS brick with 40% ZrO2 content. At 1500-1600℃, there is no glass phase precipitation after 16 hours, and there is little pollution to the glass. After 40 times of thermal shock resistance test at 800-1250℃, there is no crack.
Next, let's explain to you the refractories for making glass furnaces:
Chrome brick and chrome brick
The dense chromic oxide bricks (Cr2O396%, TiO2<4%) formed by isostatic pressing can be used for the side walls, necks or other severely corroded parts of E glass and C glass tank kilns, and their service life can reach 6-7 years. In recent years, new progress has been made in chromium-containing products, such as adding Cr2O3 to A ZS bricks to form Al2O3-ZrO _ 2-SiO _ 2-Cr2O3 refractories. At high temperature, on the one hand, Cr2O3 forms a solid melt with Al2O3, on the other hand, because Cr2O3 is a high melting point substance, it enters the glass phase of bricks to increase the viscosity of the glass phase, thus increasing the exudation temperature of the glass phase and greatly improving the glass corrosion resistance of glass products. An American company has produced a kind of fused cast AZS/Cr2O3 refractory, which is superior in chemical composition and physical properties. Compared with the original Al2O3/Cr2O3 material, the annual power consumption is reduced by 4%, the output is increased by 15%, the cost is reduced by 3.75%, and the glass quality is not affected. The brick can be formed by mechanical pressing, manual ramming or isostatic pressing, and then sintered at high temperature.
High-purity direct-bonded alkaline bricks fired at 1800℃ are widely used in regenerator walls and self-closed. Germany introduced a new material, RUBINAI·EZ, whose chemical composition is 75% MgO, 13.5% ZrO _ 2 and 9.5% SiO _ 2. It is a periclase Shi Zhuan bonded with zircon. At the initial stage of sintering, zirconium silicate in the brick structure reacts with magnesium oxide to form a structure around periclase particles.
Olivine magnesia brick
The combination phase of olivine has particularly strong corrosion resistance, and the corrosion resistance of magnesium brick can be improved by increasing the content of forsterite in the combination phase of magnesium brick. Therefore, 20% forsterite fine powder is added to the ingredients of magnesia brick to form forsterite binding matrix which can protect magnesia particles and reduce erosion. The price of this brick is relatively cheap, and it has been widely used in the middle of the regenerator lattice of glass kiln abroad.
Barium feldspar olivine brick
In view of olivine's good corrosion resistance but insufficient thermal shock resistance, the thermal shock resistance of brick can be obviously improved by introducing barium feldspar into its bonding phase. Barium feldspar is formed in the sintering process and only exists in the matrix phase. When the content of barium feldspar is 15%, the performance of silicon is the best, and the service temperature is about 1250℃. The research shows that barium feldspar can resist the erosion of alkali and sulfate.
The application of unshaped refractories in glass kilns is also a development trend. In Britain, refractory concrete precast blocks are used to build regenerator, checker brick bottom arch, flue, small furnace supporting plate, burner, etc., which greatly reduces the joints of kiln structure, improves the furnace building speed and shortens the cold repair time. ERSOL in Xipu, France is an amorphous refractory series made of ER 1681 fused particles, which is used in the bottom of the pool with fused bricks. It has excellent glass erosion resistance and weak tendency to precipitate bubbles and form stones. ER2SOL series amorphous materials have been used in the bottoms of some glass kilns in Japan. Foreign refractories for glass kilns are developing in the direction of series products containing zirconium and chromium, and theoretical research is also focused on how to further improve the glass corrosion resistance and mechanical properties in order to further prolong the life of the kiln.
Thermal insulation material for glass kiln
High alumina brick, light silica brick and fiber are widely used in glass kiln insulation abroad, mainly based on aluminosilicate fiber. In Germany, in addition to diatomite, aluminosilicate and silicate fiber materials, lightweight products based on calcium silicate are widely used. In addition, Didier company has developed a composite plate which is composed of two materials and named "SSH". The first layer in the composite plate is 50 ~ 75 mm thick, which is made of fairly dense clay refractory, and the second layer is 100 ~ 125 mm thick, which is made of ultra-light refractory (refractory clay or calcium silicate-based material). The total thickness of the composite plate is 150 ~ 200 mm, and its size is consistent with the surface size of the insulated brick. The CIS mostly uses lightweight phosphate concrete, fiber products and fillers. The binder used for lightweight refractory granular filler is Al-Cr-P binder. The acid ratio of the binder is 2.3, and the density is between 1.55 and 1.6g/cm3. The particles are industrial Al2O3 and artificial Al2O3, and the service temperature is 1800℃. Lightweight phosphate concrete is a new type of lightweight heat-resistant concrete made of phosphate as binder and porous clay crumbs. The main performance parameters of the best lightweight phosphate concrete are: density of 800-1100 kg/m3, compressive strength of 7-12 MPa, thermal conductivity of 0.3～ 0.35W /cm·k k, and long-term service temperature of 1270℃.