What are Air Cooled Heat Exchangers? Are they the same as Fin Fan® Coolers?
Air Cooled Heat Exchangers – also known as Fin Fan Coolers, are heat transfer devices for rejecting heat from a hot process fluids such as refinery products or steam directly, to the surrounding atmosphere.
Fin Fan Coolers are basically that — multiple rows of fin tubes with a fan to move lower temperature ambient air over the coils in order to cool the hotter fluid, just like a radiator in an automobile. An industrial example is a unit large enough to reject the heat from a turbine exhaust steam condensation system.
What is the average life one can expect from a Smithco Fin Fan® Cooler?
Engineering Consultants who specify these units often ask what will be the life of an air-cooled heat exchanger running in the particular operating environment.
This is a very good question. Smithco-Eng have had units running for longer then 40 years with regular maintenance such as lubrication, monitoring and adjustment of the drive tension and keeping the unit from imbalance forces.
The tube bundle selection is often the key determinant. This is the eroding or corroding component that will most impact life.
When we select an air cooled heat exchanger for our clients we examine the specifications and working with you we balance a number of issues to deliver a custom tailored product. For instance thinner tube walls convey heat better. This improves thermal efficiency. It also means there is less material available to prevent against corrosion. Higher alloy materials prevent against corrosion but increase first cost as well as can impact heat transfer efficiency.
Some of our customers have calculated that using carbon steel bundles in place of higher alloys delivers a better return when all things are considered – like energy use and first cost – even though the bundles may need to be replaced every 3-5 years.
Other plants that run very lean in maintenance personnel are willing to trade-off some points of efficiency and are willing to invest in higher cost alloys in order to not to lengthen the time between re-bundling.
Both approaches are valid and depend upon the operating strategy of each organization. Ask our engineers to help you in navigating this area for optimizing life-cycle costs.
Is there a difference between an Air Cooled Heat Exchanger and an “aerial cooler”?
No. It is just a different name for an air-cooled heat exchanger.
When would one select an induced draft or a forced draft fan?
Typically Induced Draft fan coolers have better distribution of air across the bundle.
Because of the orientation there is less chance of recirculation of the hot outlet air back into the inlet side. Generally it has better process control characteristics because the outlet shroud covers more than 50% of the bundle face area. This also protects against UV deterioration and hail damage.
On the other hand Induced draft fans will have higher horsepower requirements if the leaving air is very hot. Life of the fan and components is lessened due to operating in higher temperatures.
Also with induced draft fans configurations the fan and drive is less accessible for maintenance.
Note: Fin Fan® is a trade-name of the Hudson Products Corporation. Hudson is a majority owner of Smithco Engineering.
The correct terminology for this product is air cooled heat exchangers. The terms fin fans and fin fan coolers are used here due to its common usage in petrochemical refineries.
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