Materials of Construction

[chaswt]

Does anyone know what the reasons are why LNG Plants use Aluminium heat exchangers instead of other metals/alloys?

I understand the SS's are relatively cheap but not good heat exchanger, however Copper is good.

So, Aluminium is approximately 1/3 the cost of Copper however only has about 1/2 the thermal conductivity of Copper. (Copper - 401 W/m.K, Aluminium - 237 W/m.K).

I know Mercury is a big problem for Aluminium HEX's in relation to corrosion. Would Copper have similar corrosion problems if used as HEX material in a gas processing plant?

I'm just trying to determine why Aluminium is the industry wide accepted material for this application.

Thanks.

 

[SNORGY]

Some Clients / Facilities do not allow yellow metals in any pressure retaining service, even if the process itself is not sour.

My gut reaction is that the propensity towards aluminum over copper or other alloys may have as much to do with market inertia as with anything else.

Regards,

SNORGY.

 

[jte]

I would guess that the conductivity of the metal is insignificant relative to the convection coefficient of the process fluids. So I would not focus on conductivity as an indicator of a "good" metal.

As to why Aluminum? Well, for one thing it melts easier... Just the perspective of a guy who generally works with steel!

jt

 

[chaswt]

Snorgy & jte.

Thanks for your comments. Much appreciated.

chaswt

 

[dcasto]

the process to manufacture aluminum heat exchangers makes the assembled cost so low, nothing else can compete.