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4A Comparing Kilns

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Comparing the Draw Kiln and the Hoffmann Kiln

This table shows the advantages and disadvantages of each of the two main types of kiln used at Llanymynech in the 19th Century.

Factors

Draw Kiln

Hoffmann Kiln

Limestone that could be burnt in the kiln

 

Large, hard pieces

Large pieces, hard or crumbly

Fuel type

 

Coal or coke

Coal or coke

Cost of building the kiln

 

Cheap to build

Expensive to build

Cost of repairing the kiln

 

Low

Low

Cost of employing men to work the kiln

 

Low – medium labour costs

High labour costs

Draught of air needed to reach the high temperature

Low

Low

Amount of quicklime produced (output)

 

High output

High output

Quality of quicklime produced

 

Good quality

Good quality

Ease of loading the kiln (charging)

 

Easy to load

Laborious to load

Ease of emptying out the quicklime (discharging)

This varied from kiln to kiln

Laborious to empty

Quicklime produced from 1 ton of coal

 

Between 2.5 and 6 tons

Between 5 and 6.5 tons

1) Which kiln was more expensive to build?  

2) Which kiln had the higher labour costs?  

3) Which kiln was easier to fill and to load?  

4) Which kiln needed the most draught?  

5) What was the main advantage of the Draw kiln? 

6) What was the main advantage of the Hoffmann Kiln? 

7) Why do you think the Hoffmann kiln was used for only 15 years, then closed?

 

[EDUCATION PACK] [SECTION 0NE] [SECTION TWO] [SECTION THREE] [SECTION FOUR] [4A Comparing Kilns] [4B Thomas Savin] [4C Explosion at Cooper's Rock] [4D Inspector's Report] [4E Maps 1887-1901] [4F Tally House - tons] [4G Tally House-kg] [4H Find Height Chimney] [4I General study sheets] [4J Artefact Quiz] [4K Answer Sheet] [SECTION FIVE] [Follow Up Activities] [Using the LLANY ED PACK SITE]