- Boiler Economizer Definition: A boiler economizer is a device that preheats fluid to reduce energy consumption and improve boiler efficiency.
- Function: It captures residual heat from flue gases to warm the inlet water before it enters the boiler.
- Construction: The economizer consists of horizontal inlet and outlet pipes connected by vertical pipes where heat transfer occurs.
- Heat Recovery Process: As water moves through vertical pipes, it absorbs heat from flue gases, making the boiler more efficient.
- Soot Management: A scraper mechanism removes soot from the vertical pipes to maintain effective heat transfer.
What Does an Economizer Do in a Boiler
A boiler economizer (also known as an economizer) are mechanical devices intended to reduce energy consumption or perform a useful function such as preheating a fluid. A boiler economizer is essentially a heat exchanger that makes a system more energy efficient by taking enthalpy in fluid streams that are hot, but not hot enough to be used in a boiler – hence recovering more useful enthalpy and improving the steam boiler’s efficiency.
After producing steam, flue gas exits the system. This flue gas still contains some heat energy. If we don’t use this heat, it gets wasted. A boiler economizer captures this remaining heat to warm the inlet (feed) water for the boiler. This process reduces the fuel needed to produce steam, hence the name economizer.
Construction and Working Principle of Boiler Economizer
The construction and working principle of the boiler economizer are simple. At the bottom, there is a horizontal inlet pipe for feeding water at normal temperature. Another horizontal pipe is at the top of the economizer.
These horizontal pipes, at the bottom and top, are connected by a group of vertical pipes. An outlet valve on the top pipe supplies hot water to the boiler. Flue gases from the boiler furnace flow through the vertical pipes.
The flue gases transfer heat to the water as it moves up through the vertical pipes to the top horizontal pipe. This process uses the flue gases’ heat to warm the water before it enters the boiler to produce steam.
The flue gas will have ash particles mixed with it which will get deposited on vertical pipe surfaces. If special care is not taken there will be a thick layer of soot on the surfaces which insulate the heat to enter the water.
To remove this soot, the scraper is attached to each vertical pipe which continuously moves up and down by means of a chain pulley system. By scraping the soot fall down to the soot chamber placed at the bottom of the economizer. Then we collect the soot from the soot chamber. This is how a boiler economizer works. This is a very simple form of boiler economizer.
