01
The Challenge
A 700 t/d float glass furnace runs its super duty silica crown for years between rebuilds, and energy consumption rises as the furnace ages. CSG needed to know whether a high emissivity coating would affect silica brick expansion or glass quality before trusting it on a production furnace.
02
What Was Applied
In April 2015, Emisshield coating was applied to the crown and walls of CSG's No. 1 float glass furnace in Dongguan, 743 m² of super duty silica brick. It was the first float glass furnace to use Emisshield.
03
Why It Worked
A high emissivity surface radiates more heat back into the melt instead of absorbing it into the refractory. That radiative effect also protects the crown bricks, which is consistent with the intact crown found at the sixth and eighth year inspections.
04
Energy Savings Held Into the Seventh Year
In the first year, CSG detected no effect from the coating on silica brick expansion or glass quality. At the end of 2015, CSG compared the total energy consumption of two 700 t/d float glass furnaces under the same working conditions and estimated savings of about 2%. The design institute set a first-year energy target of 5,233 kJ/kg and projected 5,622 kJ/kg for 2022 as the furnace aged. The coated furnace averaged 5,446 kJ/kg in 2022, its seventh year, 3.1% below that projection. Endoscope inspections in 2021 and 2023 found the inner crown surface intact with no rat holes.
| Measure | Result |
|---|---|
| Energy savings, end of 2015 (CSG calculation) | About 2% |
| 2022 energy consumption, coated furnace | 5,446 kJ/kg |
| 2022 projected target | 5,622 kJ/kg |
| Difference versus 2022 target | 3.1% lower |
| First-year target | 5,233 kJ/kg |
| Crown condition, 2021 and 2023 endoscope inspections | Intact, no rat holes |
| Effect on silica brick expansion and glass quality, year one | None detected |