12 min read
14 Mar

Tempered glass belongs to safety glass and is widely used in high-rise building doors and windows, glass curtain walls, indoor partition glass, lighting ceilings, sightseeing elevator passages, furniture, glass guardrails, and other fields. Worldwide, after years of development, the annual statistical output of tempered glass above the designated size has reached more than 2.5 billion square meters, and the product application field has also expanded from a single construction field to multiple applications such as construction, automobiles, photovoltaics, home appliances, decoration, and fire protection. field. With the gradual development of the tempered glass deep processing industry, high-end, energy-saving, intelligent, and green have become the mainstream of the future development of the tempered glass processing industry, which puts forward higher requirements for the performance of the existing tempered glass, especially in the "double carbon" Under the background, the realization of energy saving in the production process and low carbonization of products has become an important factor affecting the competitiveness of products. Under the background that the existing glass tempering equipment is difficult to meet the above requirements, it is necessary to upgrade the existing glass tempering equipment to improve the tempered glass. quality and energy-saving, making it a relatively economical choice for current glass processing manufacturers.

1. The overview of the development of tempered glass

1.1 The development history of tempered glass

Since the 1970s, tempered glass has been popularized and applied in automotive, construction, aviation, electronics, and other fields, especially in construction and automobiles. Since then, the glass industry has continued to conduct research and development of new tempered products and technologies, and flat non-spotted glass, ultra-thin tempered glass, Low-E tempered glass, special-shaped tempered glass, etc. have been born one after another. At the same time, the scale of the glass processing industry is also growing. By 2020, it is estimated that the tempered glass output of enterprises above the designated size worldwide will reach 2.53 billion square meters. Take China, a major producer of glass deep processing, as an example. Since the 1980s, Chinese enterprises have begun to introduce a large number of horizontal roller-type tempered glass production line equipment, which has effectively improved the quality and production efficiency of tempered glass products. As an excellent supplier of glass tempering equipment, Glaston began to introduce the original brand "Tamglass" into China from the late 1980s to the early 1990s. By 2020, more than 200 production lines are operating in China, provides strong support for the production of high-quality tempered glass, and also indirectly promotes the modernization process of the development of tempered glass production equipment worldwide.

1.2 Introduction of glass tempering equipment

Tempered glass is a kind of prestressed glass. To improve the strength of the glass, chemical or physical methods are usually used to form compressive stress on the surface of the glass. When the glass is subjected to external force, the surface stress is first offset, thereby improving the bearing capacity and enhancing the glass's wind pressure resistance, cold and heat resistance, and impact resistance. There are many ways to classify glass physical tempering equipment. Commonly used glass physical tempering equipment mainly includes reciprocating flat tempering equipment, continuous flat tempering equipment, bending tempering equipment, etc.; Heating chamber tempering unit, etc.; according to the heating method, it is divided into radiation heating tempering equipment, convection heating furnace tempering equipment, etc.

The glass flat tempering equipment mainly includes four components: a loading table, heating furnace (preheating furnace, main heating furnace), tempering grille, and unloading table, as well as other components such as a control system and tempering (cooling) fan. A heating furnace and tempering (cooling) air grid are the most important components of glass tempering equipment. Through different combinations, different types of glass tempering equipment such as single-chamber reciprocating tempering furnaces, double-chamber tempering furnaces, continuous tempering furnaces, and bending tempering furnaces can be formed. 

Figure 1 Schematic diagram of the composition of glass tempering equipment

Figure 1 Schematic diagram of the composition of glass tempering equipment

1.3 There are problems

Although the tempering equipment of Glaston has a very long service life, there is even equipment that has still in operation for more than 20 years. However, after using the old glass tempering equipment for some time (such as 8-10 years), problems such as high energy consumption, high maintenance frequency, and product quality decline will occur, and it is difficult to meet the production requirements of high-quality, low-carbon and low-cost products...

1. High energy consumption. The main reasons for the high energy consumption are as follows: First, after the glass tempering equipment is used for some time, the thermal insulation performance of the refractory material decreases, causing heat to be lost to the outside air, thereby increasing the energy consumption of the equipment; second, the main heating The furnace body adopts a compressed air convection system, and the hot air in the furnace needs to be discharged to maintain the normal pressure in the furnace. The discharged air causes a large heat loss and increases the energy consumption of the equipment; thirdly, the preheating furnace body of the old glass tempering equipment adopts 44 The power of each fan is 3.2kW, and the total power is 140.8kW, which also increases the energy consumption of the equipment to a certain extent.

2. Maintenance is difficult. First, because the preheating furnace body of the old glass tempering equipment uses 44 small fans, the large number of fans leads to a higher probability of equipment failure, increased maintenance frequency, and delayed production time; second, the control system of the old glass tempering equipment It is a board system. With the increase in service years, the system response is slow, the operation is sluggish, and even the system crashes. Among them, the board system is produced by the company itself, and the control accessories can only be provided by the original company, and the company has stopped the manufacture of the control system accessories, resulting in maintenance difficulties and increased maintenance costs.

3. Quality decline. After the old glass tempering equipment is used for some time, there will be problems such as serious stress spots on thick plate glass, large deformation of glass edges, and large fluctuations in wind pressure when the temperature difference is large. New glass varieties appear, and old glass tempering equipment can no longer meet production requirements.

2. The technical transformation plan

Given the various problems existing in the old tempering equipment, Glaston now proposes an upgrade and transformation plan for the old glass tempering equipment, which mainly includes the transformation of the preheating furnace, the main heating furnace, system control, and tempering parts, and can be modified according to actual needs. Partially upgrade the device. For example, only the preheating furnace and control system are upgraded to improve production efficiency and product quality, and new types of glass such as thin glass and high-stress fire-resistant glass can also be produced by upgrading the tempered part.

2.1 Preheating furnace upgrade plan

2.1.1 Heating method upgrade

First, the convection part is changed from the original side convection heating method through 44 pairs of small fans to the circulating convection heating method through the top 3 high-power fans. In this way, through the high-power and high-efficiency convection, the hot air in the closed furnace can quickly form an internal circulation, and the hot air can quickly reach the glass surface and heat it; second, the fan and heating wire control system is replaced by an intelligent adjustment system, which is heated by reasonable distribution. curve, to achieve precise control and precise heating of the required parts, and improve the product quality of tempered glass; third, the fan is placed on the top of the furnace body, which can be disassembled and installed directly from the top of the furnace to facilitate maintenance.

Figure 2 Heating schematic diagram of the old furnace and heating schematic diagram of the new furnace

Figure 2 Heating schematic diagram of the old furnace and heating schematic diagram of the new furnace

2.1.2 Heating wire upgrade

First, the original single longer heating wire with fixed power is replaced with a shorter heating wire with an adjustable rate, and the heating wire is equipped with a special temperature measurement and control system. The system can not only measure the temperature in real-time, but also automatically control the heating of the corresponding heating wire, which can ensure the multi-station heating in the tempering furnace on demand, which makes the equipment not only energy-saving and heating efficient, but also ensures high product quality; secondly, The heating temperature of the heating wire is increased from the highest 400-500C to 700-800C, which can quickly increase the heating efficiency and improve the overall tempering efficiency of the tempering equipment; Third, the heating wire at the bottom of the fan is installed on the side of the furnace body and can be pulled out directly from the side Maintenance is more convenient.

2.1.3 Upgrade of refractory materials

Replace the refractory material in the furnace body with high-quality mineral wool and fireproof material. The new refractory material has better thermal insulation performance, smaller thermal conductivity, and better sealing performance, which can improve the service life of the tempering equipment and strengthen the heat sealing performance of the tempering furnace, thereby making the furnace body more energy-saving.

2.2 Main furnace upgrade plan

In addition to changing the heating wire and replacing the refractory material with better thermal insulation performance, the main heating furnace body has the same transformation as the preheating furnace. Another important transformation is to change the compressed air convection system to the internal circulation convection system, which can avoid The outflow of hot air in the furnace leads to a large amount of heat loss, which greatly reduces the energy consumption of the product and makes the tempering equipment more energy-efficient. In addition, the circulating convection system adopts a specially designed structure to make the wind pressure of each air nozzle consistent, and the staggering air nozzle arrangement makes the glass more uniform in temperature during heating, reducing the stress spot caused by uneven temperature.

Figure 3 Schematic diagram of compressed air convection in the old furnace and schematic diagram of circulating convection in the new furnace

Figure 3 Schematic diagram of compressed air convection in the old furnace and schematic diagram of circulating convection in the new furnace

2.3 Control system upgrade plan

The control system upgrade is mainly to upgrade the original embedded board control system to an intelligent system (iCont⑹ system). After the system is upgraded, first, it has a high degree of intelligence. When the glass enters the furnace, the system will measure the size and shape of the glass and automatically set the heating power curve and convection curve according to the shape results. The heating wire can follow the position of the glass swinging in the furnace. Adjust the heating state. The heating time is automatically set according to the size, and the system will also automatically adjust the fan power according to the change of the ambient temperature to keep the wind pressure at the set parameter value; second, the real-time recording and analysis function is strong. Output, equipment status, energy consumption, equipment maintenance, and other production process functions, and can generate analysis report files at any time, which is conducive to quality tracking and improves production efficiency; third, the operation is simple, and the system requires low skills for operators, only It is necessary to input the parameters of glass thickness and glass types, and the system can automatically complete all other functions, which is easy to learn. Fourth, the new system has strong compatibility. In addition to the above advantages, the new system also has the advantage of strong compatibility. The control system If there is a problem with the components, replacement components can be obtained from the market, which can save a lot of maintenance time and maintenance costs.

Figure 4 Comparison of the old control system (left) and the new control system (right)

Embedded Board Control System                       Glaston iControl Control System

Figure 4 Comparison of the old control system (left) and the new control system (right)

2.4 Tempering part upgrade plan

The upgrade plan for the tempering part is mainly to change the ordinary centrifugal fan air cooling mode to the compressed air cooling mode, which can meet the tempering requirements of thin glass (S3mm) and high-stress fireproof glass (N180MPa).

For thin glass and high-stress glass, if the temperature of the glass surface is increased blindly, it will lead to more defects and optical distortion on the glass surface. At the same time, if the tempering wind pressure is only increased, it is not economical from the perspective of industrialization. The study found that by moderately increasing the surface heating temperature of the glass and moderately increasing the tempering wind pressure, it can not only meet the requirements of the surface stress of the glass but also ensure the surface quality and optical effect of the glass. The use of compressed air as the tempering medium is more economical than the ordinary centrifugal fan and is not limited by the ambient temperature and altitude. The independently adjustable function of the upper and lower air grilles makes the tempering process more flexible and controllable, making the thin glass fireproof the flatness of the glass is at its best. At the same time, the compressed air is intelligently controlled by the system. After the wind pressure is intelligently and accurately calculated by the system, the power output of the fan can be automatically adjusted, the wind pressure and flow of the fan can be adjusted, and the surface stress of the glass can be precisely controlled to ensure uniform stress on the tempered glass. When producing ordinary tempered products, the supercharging function can be turned off to save energy.

When the tempered part is upgraded, 30 sets of the latest high-precision blowing section spokes will be replaced. The spokes are made of high-precision alloy spokes, which can reduce the optical deformation caused by the beating. The short ropes are all new products, and some of the spokes are densely wound with ropes to reduce the influence of the ropes on the stress spots during glass tempering and achieve the goal of improving product quality.

3. Advantages of equipment upgrades

Through the above analysis, it can be concluded that the old glass tempering equipment has many advantages such as energy-saving, green, high efficiency and high quality, new tempered varieties, more intelligence, and convenient maintenance, which greatly saves production costs and improves production efficiency. comprehensive competitiveness of products.

1. Energy saving and green. Through the use of hot air internal circulation, multi-station intelligent heating, intelligent adjustment of fan power, and upgrading of thermal insulation and refractory materials, the average energy consumption of the upgraded tempered glass products is reduced by more than 12% year-on-year, which makes the products in the power supply shortage and More competitive advantages under the situation of rising electricity prices. At the same time, the energy consumption of 6mm thick float glass and Low-E coated glass is slightly higher and lower than the green tempered glass evaluation index requirements in the "Green Product Evaluation Architectural Glass" standard. This is because the data is based on the glass loading rate of 65%, the actual production data is lower, which can fully meet the standard requirements, which helps enterprises to apply for the title of green tempered glass product and increase product competitiveness, which is more significant in the context of "double carbon".

Table 1 Comparison of energy consumption before and after upgrading of tempering equipment

Thickness (mm)Energy consumption before upgrading (kWh/m2)Energy consumption after upgrading (kWTi/m2)Energy saving rate
4 (Low-E)3.43.36%
 64.13.4 17%
6 (Low-E)4.43.814%
10 (Low-E)6.75.9 12%


Remarks: The energy consumption value is measured under the condition of a 65% loading rate and ambient temperature of 25 °C

Table 2 Energy consumption requirements for evaluation indicators of green tempered glass

ClassificationPlane ordinary tempered glass (thickness 6mm)Plane low-emissivity coated tempered glass (thickness 6mm)
Energy consumption (kWh/m2)<3.22<3.99 

2. High efficiency and high quality. Through comprehensive measures such as increasing the tempering temperature of the preheating furnace, intelligent control of multi-station heating, intelligent adjustment of wind pressure, reasonable wind pressure, heating curve design, etc., the hot air and the glass can conduct more efficient and sufficient heat exchange, and the glass can be in the same time. It absorbs the most heat energy, accelerates the healing rate of the glass surface, accelerates the production efficiency of tempered glass, and increases the production capacity by more than 40% after the tempering equipment is upgraded. At the same time, through the integration of two-stage furnace bodies, the use of imported V-belts for smooth transmission, the selection of high-precision alloy rollers, and reasonable heating and air pressure control, the process of tempering glass being transferred from the reheating furnace to the main furnace is avoided. The appearance of the glass temperature change reduces the optical deformation during the glass softening process, especially the edge deformation, reduces the stress spot caused by uneven temperature, and greatly improves the optical quality of the tempered glass.

3. New varieties of tempering. By adopting compressed air tempering in the tempering section, properly increasing the heating temperature in the heating furnace, and adopting a special tuyere design system, etc., after the tempering equipment is upgraded, new products such as tempered thin glass (<3mm) and high-stress fireproof glass (2180MPa) can be tempered. Glass varieties, and the upgraded equipment is more suitable for tempering Low-E glass varieties. The equipment uses a bottom temperature measurement device to better measure the production efficiency of the tempering equipment.

4. The future development trends of tempered glass. 

At present, construction, transportation, and other industries around the world have entered a period of high-quality development, which has put forward higher requirements for the quality of tempered glass. The future demand for tempered glass is gradually showing development trends such as thinness, functionality, and low carbonization.

1. Thin profile. The thinning of tempered glass is of great significance to building a conservation-oriented society and achieving the "double carbon" goal. The use of thin tempered glass has the advantages of reducing resource consumption for glass production, reducing glass tempering heating energy consumption, and reducing transportation costs. Taking flat glass as an example, based on the output of 946 million weight boxes in 2020, if the thickness is reduced from 6mm to 4mm, the material consumption of the entire system is reduced by 1/3o, which can reduce the annual consumption of glass by about 9.46 million tons and reduce energy consumption by about 2.18 million tons. standard coal, reducing carbon dioxide emissions by approximately 6.5 million tons, which can effectively reduce the use of natural resources and carbon dioxide emissions.

2. Functionalization. With the continuous improvement of the economy and residents' income in various countries, people have entered the stage of quality consumption from meeting the most basic living needs, and have put forward higher requirements for the functions of glass products. Multifunctional glass such as safer, low-carbon, and smart will become the main trend in future development. Such as tempered hollow Low-E glass, photovoltaic glass, vacuum tempered glass, electrochromic glass, photochromic glass, etc., the demand will continue to increase in the future.

3. Low carbonization. Since some developed countries released dual-carbon targets, the national government and various industries have actively carried out relevant work and introduced a series of policies and standards. Carbon reduction has been integrated into all aspects of life. Low-carbonization in the production process should become the basis of the industry. requirements and development trends. As tempered glass is a relatively energy-consuming product, low-carbon production will be an inevitable requirement, and low-carbon products will also enhance corporate competitiveness.

Generally speaking, the upgrading and transformation of tempered glass equipment is a relatively economical solution for improving quality and efficiency. It can not only meet the current needs of enterprises for thinning, multi-functional, and high-quality tempered glass but also conforms to the development trend of green and low-carbon production processes. , in the current "double carbon" context, its significance is even more prominent.

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