Economisers

Economisers - Optimising the thermal efficiency of your boiler

Economisers are used to recovering heat from the flue gases of a boiler. The heat recovered is used to pre-heat the boiler feed water, which improves the overall thermal efficiency of the boiler.


What you can expect from us

Customised design

We tailor the finned surfaces to the design temperature profile. We can use more economical materials and extended surfaces as the exhaust gas temperature reduces.

Compact arrangement

Using a range of finned surfaces from welded fins through to plate fins, we ensure the most compact arrangement while minimising the pressure drop required.

Corrosion resistant

We design economisers to lower the gas temperature to a level marginally above the level at which condensation would occur. However, there is still a risk of corrosion under start up and shut down conditions. Therefore, we recommend appropriate materials and advise on the best operational parameters to minimise the potential for corrosion.

 

How it works

An economiser takes waste heat from the exhaust gases in a boiler flue and uses it to preheat the boiler feed water. The characteristics of the flue gas are subject to the fuel that is used and consequently can vary significantly.

Here are some key aspects that we consider in our designs.

  • Exhaust temperature
  • Flue gas properties
  • Solids content
  • Condensing temperature

We determine the on-coil fin configuration based on the calculated fin root and tip temperatures. We then progress to a secondary and tertiary phase of cooling ensuring that we remain within the design envelope of the selected fin form in each case.

Boiler feed water inlet temperature varies depending on ambient conditions and operational requirements. We work with our customers to review a range of operating points and ensure that the heat exchange characteristics permit easy control of the equipment as a whole.

Usually, the water is fed counter flow to the flue gas stream. This is the most efficient arrangement. However, when considering the control of fin and tube temperatures, we have found it advantageous to use co-current flow in a limited number of cases.

Note that, before discharge to the atmosphere, the flue gas may require a small amount of reheat to prevent the formation of a plume. Sterling Thermal Technology can also supply a heat exchanger designed to solve this issue.

 

Photo of a flue gas economiser designed and manufactured by Sterling Thermal Technology

 

If you feel you need another type of heat exchanger, visit our products and services page or contact us.


Customised heat exchangers

Over 100 years of design & manufacturing knowledge

Your partner for the entire lifecycle of your business

Sterling Thermal Technology have worked with us to develop the arrangement of economisers that best suits our equipment. We are pleased with their proactive response to our requirements.



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We customise our heat exchange solution to meet your requirements, so contact us today to discover the right equipment for you.

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