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Boiler Heat Recovery - Economizers
The major efficiency loss of a boiler is caused by the hot stack gases
discharging to the atmosphere. One of the most cost-effective ways of
improving the efficiency of a high pressure steam boiler is to install
an economizer on the boiler. An economizer is a heat exchanger, which
transfers heat from the stack gases to the incoming feedwater.
Typically, on a high pressure water tube boiler, the efficiency
improvement with an economizer is 2 to 4%, depending on firing rate.
On a high pressure fire tube boiler, the improvement is 2 to 3.5%,
depending on boiler size and firing rate.
The economizers are located in the boiler stack close to the stack
gas outlet of the boiler. They may be supported from overhead or
from the floor. A feedwater line, which serves the boiler, is piped
to the unit. No additional feedwater control valves or stack gas
dampers are required.
Generally, economizers are manufactured by companies specializing
in this type of equipment. They are often cataloged by boiler
manufacturers as accessory equipment.
Technical assistance on the application of boiler economizers is
available from the Consulting Support Service (183A), Office of
Facilities Management. Please call Jim Shoemaker at 202-565-5176.
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