Helixchangers
Why is our shop currently full of baffles that look like pieces of pie, and what are we going to do with them?
Helixchangers are a special heat exchanger design with helical baffle design that we license from Lummus Technology. Altex was the first licensee in Canada back in 2004, and since then we have built almost 100 of them.
Why helical baffles? They increase the exchanger performance and reduce fouling when compared to conventional baffle designs – This results in heat exchangers that require less cleaning and maintenance.
In May we were awarded a very important project at a time when nobody was buying anything – 11 Helixchangers for Gibson Energy at Hardisty. These exchangers are just entering production now and will be shipping in the coming months.
Okay, so why don’t we use helical baffles for everything? Well, because they are expensive to make and only become competitively priced when used for the right process condition – which is high viscosity processes on the shell-side.
“The viscosity of a fluid is a measure of its resistance to deformation at a given rate. For liquids, it corresponds to the informal concept of “thickness”: for example, syrup has a higher viscosity than water.”
-Wikipedia
Viscosity examples:
(Measured in cP, centipoise)
1 Water
15 Anti-freeze
50 Corn oil
175 Maple syrup
2500 Honey
60,000 Ketchup
200,000 Peanut butter
In a conventional `transverse’ shell & tube exchanger, the shell-side fluid flows on the outside of the tubes and is guided along the length of the exchanger by baffles.
These baffles serve two functions:
- To support the tubes and keep them from vibrating and getting damaged
- To maximize thermal performance by having a higher velocity and directing the shell-side flow to `cut across’ the tubes instead of flowing along them.
Unfortunately, the flow with transverse baffles is not ideal – there are `dead zones’ where flow is stagnant, and velocities are minimal – these areas are not transferring heat effectively and tend to be where fouling is highest. This effect is magnified when viscosities are increased – sometimes the dead zones can end up having the process solidify completely.
In comparison, a Helixchanger shell & tube exchanger has shell-side flow that follows a spiral pattern throughout the entire shell length – there are no dead-zones where fluid is stagnant.
The result is heat exchangers with higher average shell-side process velocities, increased performance, reduced fouling, and reduced cleaning frequency.
In summary – With the right (high viscosity) process, a Helixchanger design will result in smaller exchanger sizes and/or the reduced number of total exchangers required, giving Altex a competitive advantage.
