Low Pressure Co2 Cooling Heat Exchanger Selection

[Said92441322]

Hi All,

We intend to cool CO2 compressor suction stream of around 95000 KG/H from around 55 DegC to 44 DegC using chilled water of a temperature ranges between 5 DegC to 12 DegC. However, our CO2 suction stream pressure is as low as 0.985 Barg and by introducing the cooling unit this pressure will be reduced further.

My enquiry is what is the most suitable exchanger type for our application i.e. maintaining minimum pressure drop across the exchanger.And can this exchanger be modeled in either Aspen EDR or HTRI?

 

[georgeverghese]

Perry 7th end says use a TEMA J shell for low pressure drop on shellside - see page 11-42. J shell configuration option should be available in HTRI.

 

[EdStainless]

This will be a very large unit since the flow will be at low velocity.

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P.E. Metallurgy, consulting work welcomed

 

[sarahrad]

Placing the CO compression stream on the shellside and the chilled water on the tubeside TEMA type AXU, AJU, or AHU exchangers are all good for minimal pressure drop. A TEMA type X-shell with multiple shellside inlet/outlet nozzles would be the most conservative design for min pressure drop. Another feature that will minimize pressure drop is a larger tube pitch, spacing the tubes further apart in the bundle. May want to also consider finned tubes, if this exchanger starts to get too large. The gas side will have a low heat transfer coefficient and low finned tubes can help add more surface area.

Both HTRI and Aspen EDR can be used to thermally design this exchanger. I'd recommend HTRI.

 

[Said92441322]

I think the cost of exchanger will go high in case I put the humid CO2 stream in shell side since I will need to use SS material for both shell & tube side.

 

[georgeverghese]

So you can run 2 cases and cost them out to see which is cheaper for a given permissible CO2 side pressure drop:
a) Wet CO2 on shellside, with full SS316 contruction
b) Wet CO2 on tubeside, with "x" units wired in parallel on tubeside and on shellside to meet low CO2 side pressure drop

It may be likely that multiple units wired in parallel on both CO2 side and wired in parallel on chilled water side also are necessary for case (a) also.