Heat Recovery from the flues of Industrial Boilers has for many years been effected by placing Economisers in the flue stack.
Economisers first made an appearance onto boilers in 1845 to improve heat transfer from the products of combustion of large steam plant. They were used extensively on Lancashire boilers during the industrial heyday of the cotton and woollen industries.
The mid 1950's saw the gradual replacement of coal fired Lancashire boilers with multi-tubular shell boilers initially fired by oil, but more recently by natural gas. These boilers were considerably more efficient, 82%, than the old Lancashire 65% or 75% with economisers and for some time there was little interest in economisers. The oil crisis of the 1970's and subsequent enormous increase in fuel costs coupled with the change in many cases to natural gas rekindled interest into use of economisers even on steam plant operating at 80 plus % efficiency.