Annery Kiln - Limekilns - Function

Function

Annery had three burning chambers constructed of brick, each with an air inlet (the "eye") at the base. Crushed limestone and coal unloaded from a boat on the nearby tidal River Torridge or possibly the Rolle Canal, were hauled up the single ramp and emptied into the kiln chamber. Successive dome-shaped layers of culm coal and limestone would have been built up in the kiln on grate bars across the eye at the base. When loading or 'charging' was completed, the kiln would have been kindled at the bottom, and the fire gradually allowed to spread upwards through the charge. When burnt through, the lime was cooled and raked out through the base.

The size of kilns was limited by the need to allow air to permeate freely and to prevent a collapse from too much weight; this explains why individual kilns were all much the same size and therefore multiple kilns— three at Annery— were necessary to increase production. Each kiln usually made between 25 and 30 tonnes of lime in a batch; at Annery they may have been fired in rotation to ensure a continuous supply.

Typically each kiln took around a day to load, three days to fire, two days to cool and a day to unload. The degree of burning was controlled by trial and error from batch to batch by varying the amount of fuel used. There were large temperature differences between the center of a charge and the material close to the wall, so a mixture of under-burned, well-burned and dead-burned lime was normally produced. Typical fuel efficiency was low and the job was labour intensive, with a loading gang and an unloading gang who would work the kilns in rotation through the week. The heat was intense and the smoke considerable, making this a very dangerous occupation.