2 Tiers 9x9 furnaces.
Smelts fast in bulk recipes.
Energy consumption and crafting speed are adjustable on both tiers, SO ADJUST HOW YOU SEE FIT.
Was meant to be UPS friendly, instead of hundreds of furnaces you need 1.

Base code from https://mods.factorio.com/mod/TheBigFurnace
Graphics from https://mods.factorio.com/mod/Early-3x3-Electric-Furnaces