An economiser is a device fitted to a boiler which saves energy by using the exhaust gases from the boiler to pre-heat the cold water used the fill it (the feed water).Flue gases from large boilers are typically 250 - 350°C. Stack Economizers recover some of this heat for pre-heating water. The water is most often used for boiler make-up water or some other need that coincides with boiler operation. Stack Economizers should be considered as an efficiency measure when large amounts of make-up water are used (ie: not all condensate is returned to the boiler or large amounts of live steam are used in the process so there is no condensate to return.)
It consists of an array of vertical cast iron tubes connected to a tank of water above and below, between which the boiler's exhaust gases are passed. This is the reverse arrangement to that of fire tubes in a boiler itself; there the hot gases pass through tubes immersed in water, whereas in an economiser the water passes through tubes surrounded by hot gases. For good efficiencies, the tubes must be free of deposits of soot.
They are often referred to as feedwater heaters and heat the condensate from turbines before it is pumped to the boilers.
The savings potential is based on the existing stack temperature, the volume of make-up water needed, and the hours of operation. Economizers are available in a wide range of sizes, from small coil-like units to very large waste heat recovery boilers.
Stack Economizers should be considered as an efficiency measure when large amounts of make-up water are used (ie: not all condensate is returned to the boiler or large amounts of live steam is used in the process so there is no condensate to return) or there is a simultaneous need for large volumes of hot water.
What is a Boiler Economizer?
A boiler economizer is a heat exchanger device that captures the "lost or waste heat" from the boiler's hot stack gas. The economizer typically transfers this waste heat to the boiler's feed-water or return water circuit, but it can also be used to heat domestic water or other process fluids. Capturing this normally lost heat reduces the overall fuel requirements for the boiler. Less fuel equates to money saved as well as fewer emissions - since the boiler now operates at a higher efficiency. This is possible because the boiler feed-water or return water is pre-heated by the economizer therefore the boilers main heating circuit does not need to provide as much heat to produce a given output quantity of steam or hot water. Again fuel savings are the result. Boiler economizers improve a boiler's efficiency by extracting heat from the flue gases discharged. Systems Equipment Corporation Boiler Economizers are fabricated from uniquely formed tubular elements, similar to a tear drop or diamond shape. Each economizer is specifically designed to match our clients boiler characteristics in order to maximize efficiency and the use of boiler room space. Because Systems Equipment Corporation Boiler Economizers are manufactured from stainless steel the usual corrosion problems encountered by our competitions designs are eliminated.
