The kiln types of domestic and foreign glass melting furnaces include flat plate tank kilns, horizontal flame liquid cave kilns, horseshoe flame liquid cave kilns, small horizontal flame tank kilns, heat exchange single-chamber kilns, heat exchange double-chamber kilns , Heat exchange unit kiln, heat exchange countercurrent tank kiln, heat exchange double horseshoe flame tank kiln, branch kiln, day tank kiln, double kiln, snake kiln and heat exchange vertical horseshoe flame tank kiln, etc. More than a dozen types, usually according to different product characteristics and considering the output size, quality requirements, melting temperature system, forming system, fuel type, investment cost and other factors to choose different kiln types. For flat glass, a flat tank kiln is usually used.
Flat glass melting furnaces can be divided into different types according to different classification methods, usually according to the following methods.
1. Classification by furnace scale
According to different production processes and scales, flat glass melting furnaces are divided into different sizes.
Float process: daily melting capacity is less than or equal to 300t for small melting furnace, 300~600t (excluding 600t) for medium plastic melting furnace; 600~900t for large melting furnace; greater than or equal to 900t for extra large melting furnace.
Flat drawing method (also known as Graviber method, referred to as grid method) process: daily melting capacity is less than or equal to 60t (one kiln and one line) is a small furnace; 60~120t (-kiln two lines) is a medium-sized furnace; 120t (one kiln and three lines) is a large furnace.
Vertical lead-up (no groove and grooved) process: classified according to the number of lead-in machines, so this kind of process has high labor intensity, poor product quality, and small varieties and specifications. It has been gradually eliminated. Its production process and scale are no longer in the book Introduction.
Calendering process: the melting volume is less than or equal to 150t (one kiln line) is a small furnace; 150~250t (one kiln and two lines) is a middle brewing furnace; 500t (-kiln four lines) or more is a large furnace.
From the perspective of domestic furnace structure design and refractory material configuration, the float process is more advanced and higher-grade than the grid process, so its service life is also longer than that of the grid process (the grid process life is 3 to 5 years) 2~3 times longer.
At present, the scale of the melting furnace is also divided according to the heat consumption of the molten glass. Generally, the larger the scale of the glass melting furnace, the higher the efficiency of cattle production and the lower the unit heat consumption of molten glass.
2. Classified by heating method
According to heating methods, glass melting furnaces can be divided into fuel heating furnaces and electric heating furnaces.
According to different fuel types, fuel heating furnaces can be divided into fuel-fired glass furnaces, gas-fired glass furnaces and natural gas-fired glass furnaces. The common feature of this type of glass melting furnace is the use of a transverse flame regenerator. Since the heating process is performed above the molten glass, it is also called a hot top operation. Electric heating glass melting is performed by the molten glass itself heating during the conduction process. During the production process, the molten glass is covered with glass batches, and the temperature at the top of the furnace is relatively low, so it is called cold top operation. Relatively speaking, hot-top operation has a larger floor space than cold-top operation kilns, with higher heat consumption, more material consumption, huge investment, and greater impact on the environment. However, because people use this kiln for a long time And the scale of this kind of kiln can reach 1000t/d. With the application and promotion of oxygen-enriched and all-oxygen combustion technology, the defects of hot-top operation kilns are gradually improved. Although the electric melting furnace has many advantages, it has not been able to make the scale too large so far.
3. Classification by flame flow direction
Plate glass melting furnaces are currently mostly continuous operation regenerative furnaces heated by fuel. Usually, the furnaces are divided into horseshoe flame tank kilns and horizontal flame tank kilns according to the direction of flame flow in the kiln. With the maturity of oxy-fuel technology, oxy-fuel furnaces that do not require regenerators and reversal are being adopted by many manufacturers.
Continuous operation means that the glass melting process from feeding, melting, cooling to forming is carried out continuously at different parts at the same time, and the temperature in the kiln is stable.
The heat storage type uses the lattice refractory bricks built in the heat storage room as the heat storage body, accumulates and recovers part of the heat exhausted from the kiln, and is used to heat the air or gas entering the heat storage room after reversing. The regenerator has a simple structure and can heat the gas to a higher temperature, but the regenerator operates intermittently, the heating temperature is unstable, the temperature in the kiln fluctuates frequently, and it occupies a large area.
The horseshoe flame tank kiln has only a pair of small furnaces. The flame is sprayed from one small furnace. The flame is fully extended and completely burned. The exhaust gas is discharged through another small furnace, so that the flame forms a horseshoe flow in the furnace, so it is called horseshoe Flame pool kiln. This kind of furnace has a long flame stroke, small footprint, low investment, simple operation and maintenance, but the flame coverage area is small, and the temperature distribution in the width direction of the kiln is uneven. It is difficult to establish the necessary thermal system on the kiln length. It is only suitable for small-scale furnaces. Flat drawing or calendering furnace.
In a horizontal flame kiln, the flame direction in the kiln is perpendicular to the length of the furnace (liquid glass flow), and the flame is sprayed from one side of the kiln to the other through the small furnace, across the width of the furnace. According to the different scale of production, the number of small furnaces is different. The cross-fire kiln has a large flame coverage area, and it is easy to control the temperature distribution, pressure, atmosphere system and bubble boundary in the long direction of the kiln. Therefore, the operation system of the cross-fire kiln is stable, the uniformity of the glass liquid is good, and the quality is easy to control.
Float glass melting furnaces, large and medium-sized lattice glass melting furnaces and calendered glass melting furnaces are all "continuously operating horizontal flame tank furnaces".
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