What are Boiler Economizers?
Boiler Economizers Can Reduce Energy Use & Save On Costs
The first boiler economizer, patented in 1845, was used to improve the efficiency of boilers used in steam engines for mills and factories. By the 20th century, almost all steam engine boilers included economizers. Modern boiler economizers are used to reduce energy consumption and improve boiler energy efficiency. This article will walk you through the main types of modern economizers and explain why they’re critical features of modern boiler design.
⭐ An Economizer installed on a Miura LX-Series Boiler
The heat recovery device utilizes exhaust heat to preheat incoming feed water. Above and to the right; the Economizer Water Inlet can be seen. This is where the feed water piping enters the economizer.
What is an Economizer?
The concept behind an economizer is simple. Boilers produce heat that is transferred to water, creating steam. During that process, some heat energy is inevitably lost. Economizers capture heat from the exhaust flue and return it to the boiler by heating the incoming feedwater. By heating the feedwater, the boiler does not have to expend as much fuel to turn the water into steam.
Over the long term, fuel costs are the top expense involved in running a boiler. By greatly improving efficiency, economizers significantly decrease the cost of running a boiler over its lifetime.
Economizers recover thermal energy that would normally be lost in stack exhaust. Saving money from going up the chimney.
Types of Economizers
Non-Condensing Economizers
In a boiler, the flue gas is the heated gas that exits the boiler via an exit duct known as the flue. The escaping hot gas is a site of heat loss in the boiler system. Non-condensing economizers work through a basic heat exchange process. They consist of a heat exchange mechanism situated in the flue and are usually finned coils or tubes. As the hot exhaust gases pass across the heat exchange mechanism, heat transfers to the coiled mechanism. The recaptured heat increases the feedwater temperature entering the boiler. As the captured energy heats the feedwater, less fuel is needed to heat the water to the required boiling temperature.
Non-condensing economizers do not lower the flue gas temperature to below its acid dew point (the temperature, at a given pressure, at which gaseous acids such as SO2 in the flue/exhaust gas will start to condense into liquid acid). Depending on the boiler’s fuel, the resulting condensation can contain particles capable of corroding the flue. Keeping the temperature above the condensation point avoids the problem of potentially corrosive compounds.
Condensing Economizers
Condensing economizers take advantage of a straightforward heat exchange process to recapture the heat escaping in the boiler’s exhaust fumes. Condensing economizers lower the temperature of the flue gases to below their dew point—the point to which the gases need to be cooled to condense from gas to liquid. The process takes advantage of a property known as enthalpy. The exhaust gases transfer energy to the heat exchanger, and the resulting temperature drop causes vapor in the exhaust gas to condense and collect on any surface in the economizer. This results in condensation building up in the economizer that must drain. This allows the exhaust gases reclaim a larger proportion of energy.
All Miura boilers use non-condensing economizers. For full schematics and specifications please reach out to our sales team HERE.
The Heat Recovery Steam Generator
Economizers are one of the main components of a heat recovery steam generator (HRSG). An HRSG is a highly efficient heat exchange system that recovers heat from the hot exhaust gas and produces steam. Often, HSRGs reclaim heat from gas turbines, which creates steam to drive steam turbines. The steam produced by the HSRG may also be directly used in industrial applications. The economizer’s role in the HRSG is to preheat the feedwater. That water is then turned to steam by the evaporator and then superheated for use in industrial applications.
Improving In-Service Efficiency
- Economizers can help improve ‘true efficiency’
- Miura has developed the term “In-Service Efficiency” to describe:
- Combustion Efficiency
- Thermal Efficiency
- Fuel-to-Steam Efficiency
At Miura the Economizer Comes Standard
Unlike other boilers in the market, Miura’s package boilers come standard with a load of added benefits, including a heat recovery economizer. The economizer captures otherwise wasted heat from the combustion exhaust to preheat the incoming feed water. With this, the Miura LX-Series boiler produces steam using less fuel while operating at increased efficiency.
For more info about Miura’s boilers reach out today. CONTACT US TODAY
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