Electric Furnaces for Glass/Ceramics
Operating Temps:
Glass melting: ~1,300–1,550°C (bath). Ceramics firing: ~1,260–1,480 °C for stoneware and porcelain.
Glass melting: ~1,300–1,550°C (bath). Ceramics firing: ~1,260–1,480 °C for stoneware and porcelain.
Electric and hybrid furnaces in glass and ceramics use direct joule heating or resistive elements to bypass fossil combustion. They operate at very high temperatures, similar to steel EAFs but use different heating principles. Deliver large CO2 savings, high efficiency, and cleaner process control.
- All-Electric Glass Furnaces: Vendors produce furnaces using bottom/top electrodes (molybdenum/graphite) to melt glass electrically, delivering 5–200 t/day output.
- Electric Kilns for Ceramics: Widely used for stoneware and porcelain, electric kilns reach up to ~1,480 °C; gas kilns remain necessary for reduction atmospheres.
- Hybrid Electric Furnaces: Combine electrodes with oxy-fuel burners to balance flexibility and electric efficiency—e.g., Libbey’s hybrid melting furnace replacing regenerative units with 80% renewable electricity.
Glass Furnaces vs Steel EAFs
- Glass furnaces use submerged or vertical electrode heating, where current flows through the molten glass, contrasting with open-arc EAFs used in steel.
- Electric kilns employ resistive elements embedded in insulated chambers to fire ceramics—not suited to melting, unlike glass furnaces.
Industrial Impact
- Electric arc melting: Graphite electrodes generate arcs reaching ~1,800 °C to melt steel feedstock.
- Feedstock flexibility: Runs on 100% scrap or hybrid input (scrap + DRI), including green hydrogen-derived DRI.
- Refining stages: Equipped with emission control, alloying, and continuous casting systems for end-product quality.
Emissions & Efficiency Impact
- All-electric glass furnaces reduce CO2 by ~60% and achieve ~95% thermal efficiency due to direct joule heating.
- Electric kilns avoid combustion emissions, offering precise atmospheres and long-lasting heating cycles.
- Hybrid systems can replace up to 80% of fossil inputs, cutting ~60% of emissions .
Supply Chain & Deployment Challenges
- Power infrastructure: Glass furnaces need robust electrodes, transformers, and grid capacity; hybrid variants need oxy-fuel backup systems.
- Material compatibility: Glass chemistries must adapt to electric or hydrogen heating to prevent optical defects .
- Scale-up: Industrial-scale electric glass melting is pioneering but still rare.
- Cost vs flexibility: Full-electric furnaces struggle with dynamic output demands; hybrid models offer a compromise.
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