Therefore, the furnace volume of the pulverized coal furnace is often compared with the stratified furnace of the same evaporation amount.

In the cooling step of the lithium complex oxide in the furnace, 0.3 to 10 vol % of carbon oxide relative to the volume of the furnace is fed into the furnace.

In this way the whole of the oven space is heated in an even and uniform manner - optionally with vapourized air.

A trapezoidal cross-section also allows the cooling channel depth to be reduced, in turn reducing the stave body thickness and giving scope for further increases in furnace volume.