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We have independently researched and successfully developed a new compressed air convection system according to demands from market.That is Compressed Air Convection with Double Circulatory System (CAC+DCS). It has been used in dozens of furnaces, with which can completely achieve the tempering of Low-E glass, particularly, the Low-E glass made by Saint-Gobain, Xinyi, CSG, and Taiwan Glass, have been approved by their technologists
1. Brief Introduction of Furnaces for Low-E glass
At present, there are three types furnaces to be used to temper Low-E glass.
1.1 With high temperature fan convection system (such as Glassrobot):
1.1.1 Advantages of this system: large volume of flux, Strong capacity of heat exchange, high efficiency of glass heating.
1.1.1 Disadvantages of this system: high cost; serious scouring on inner surface of heating chamber; life of high temperature fan is short, vibration during work, inside parts is easy to be oxidized, drops of residues, deformation of metal material; large amount of high cost for maintenance; continuous running of fan costs dozens of kilowatts; useless function consumption. Production costs are great.
1.2 Compressed air convection system (such as Tamglass )
1.2.1 Advantages of this system: cost less; strong capability of convection; high efficiency of heating; uneasy oxidization, no drops and deformation; free of maintenance during working period.
1.2.2 Disadvantages of this system: periodic injection of compressed air, the same volume of hot air shall overflow to keep balance; high power comsumption.
1.3 Double chambers furnace ( convection furnace +radiation furnace)
Double chambers furnace is the ideal for Low-e glass tempering. The fan convection system work at lower temperature (350℃-400℃ ),.The working environment is change better, safe and reliable. But the manufacture cost is higher and installed capacity is more.
2. Introduction of compressed air convection with double circulatory system – the biggest breakthrough of convection
2.1 Hot air circulation inside heating chamber
There is a hot air circulation inside heating chamber on the basis of compressed air convection system. That is adopting a special static pressure generator, which takes the compressed air as driving source according to Venturi principle; make the hot air circulation inside heating chamber. Have the effect of high temperature fans.
It is a superb combination of high temperature fan circulation with compressed air circulation, which not only overcomes their shortcoming but also achieve low cost, simple structure, easy installation.
2.2 The recovery of heat outside the furnace
At the same time, add a heat exchange system outside the heating chamber, so that heat of part of the hot air discharged from the furnace, through the heat exchange system, exchange to compressed air, to preheat the cool air. So as to realize double circulation convection effect both inside and outside the chamber, further to achieve the use of energy and recycling. The system is higher efficient, stable and reliable.
2.3 The high efficiency and energy saving.
CAC+DCS can save 70% external power comsumption comparing with normal comparessed air convection system. It can save 80% of the energy consumption,Low cost, low energy consumption, convenient installation, stable and reliable comparing with fac convection system. It is a perfect technological revolution which has all the advantages of the former compressed air convection, meanwhile overcome the only drawback of discharging large amount hot air. It is the best choice for Low-E glass tempering furnace.
2.4 Simple and reliable controlling
The control system is completely independent and does not need to change any of the original control systems, which can be improved and used in existing furnaces. With the independent forced convection control system, it can rapidly improve the performance of your glass tempering furnace, to process offline Low-E glass.
Grasp the new business opportunities, relieve your troubles. Improve the utilization of existing equipment such as compressed air system you currently use, no more reinvest requested. Small investments can meet your requirements of tempering Low- E glass.
The installed power of three convection type:(2440X5000mm furnace as example)
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Power of fan or compressed air |
Total Power Kw |
Convection poiwer consumption in 10 hours (Kw/h) 5mm glass |
Performance-price ratio (full set of system) |
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High temperature fan convection (Internal circulation, energy saving) |
Top 6 sets fan * 5.5Kw=33kw |
60Kw Continuous work |
Useful work 380 Kw/h Idle energy consumption 160 Kw/h Cooling power 90 Kw/h |
Aound USD 100’000 |
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Bottom 6 sets fan * 4.5Kw=27kw |
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Compressed air convection (Hot air discharge) |
One air compressor 95Kw |
95Kw intermittent work. 100s/load |
Useful work 375 Kw/h Air discharge consumption 50 Kw/h |
Aound USD 60’000 (air compressor USD36’000,Convection system USD24’000) |
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Compressed Air Convection with Double Circulatory System (CAC+DCS, energy saving). |
One air compressor 37Kw |
37Kw intermittent work. 100s/load |
Useful work 125 Kw/h Air discharge consumption Air discharge consumption 0 Kw/h |
Aound USD 46’000(air compressor USD14’000,Convection system USD32’000) |
Note: No extra invest of air compressor if already have.
3. Composition of Compressed Air Convection with Double Circulatory System (CAC+DCS,)
It is composed of roof heat exchanger, exhausting fan,internal preheating and convection injection pipe furnace, hanging and distribution support of the static pressure injection pipe, external pipe,the pressure differential mixer, gas pressure, distribution and control center, operation panel with independent Siemens TD400 display, control system is Siemens PLC. Stable and reliable.
The heating time can be shorten 5-10%,output increases by 10% and power consumption is 4KW.sqm (4mm clear glass),when the system is used for tempering of clear float glass, meanwhile the problem of white over glass surface is solved and final products rate is improved .
The heating time is 300-350S and energy consumption 4.6 kwh per square meter when the system is used to temper Low-E glass.Guarantee the quality of tempered Low-E glass with E above 0.05.
4 Furnace upgrade and installation:
According to the requirement of the user, it is possible to add the upper and lower convection radiation pipe to heating chamber, or top convection pipe only. It is convenient, fast and reliable. It does not affect the performance and heat insulation properties of the heating chamber, and not destroy its complete state, beautiful, generous and practical. We just take an output signal, do not change the original control system.
The table of the process parameters before and after the upgrade:
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Glass type |
Top/bottom temperature(℃) |
Heating time(S) |
Heating power% |
High pressure time(S) 0.5MPa |
Lowpressure time(S) 0.2MPa |
Load rate% |
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Before upgrade. |
After upgrade |
Before Reno. |
After Reno |
Before Reno. |
After Reno |
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clear 5mm |
top707 |
top715 |
245 |
215 |
100 |
100 |
95 |
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bottom700 |
Bottom 705 |
90 |
95 |
5 |
60 |
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clear 6mm |
Top 700 |
Top 710 |
310 |
245 |
95 |
100 |
0 |
70 |
95 |
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bottom695 |
Bottom 700 |
90 |
95 |
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Low-e 6mm |
Top 710 |
Top 715 |
450 |
320 |
95 |
100 |
60 |
30 |
65 |
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bottom700 |
Bottom 700 |
90 |
95 |
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Low-e 8mm |
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Note:
1. To guarantee the quality, the loadage of Low-E glass shall be 70% or less.
2. The data in the table can be adjusted according to the characteristics of each furnace due to the characters of different furnace,
Dedicated to new and old customers and friends!