TEG Unit Evaluation

[EmmanuelTop]

G'day everyone

I have got a task to evaluate suitability of an existing TEG Glycol Dehydration Unit for another service/location. The basic design information for the existing unit is as shown below:

TEG purity: 99.75% weight
Max Circulation rate: 4.87 m3/h
Packing type: Sulzer Mellapak 250Y
Packing height: 5,040 mm
Max Capacity of Contactor: 9,360 actual m3/h
Max Reboiler duty: 450 kW

Now, there are two possible locations for this unit and the inlet gas conditions are as follows:

Location 1

Flow: 5,450 actual m3/h
Operating pressure: 13 barg
Inlet gas dew point: 20 degC
Outlet gas dew point spec: -32 degC
Inlet gas water content: 1,350 mg/Sm3
Outlet gas water content: 40 mg/Sm3
Available TEG/H2O rate: > 40 kg TEG / kg water absorbed


Location 2

Flow: 5,570 actual m3/h
Operating pressure: 35 barg
Inlet gas dew point: 35 degC
Outlet gas dew point spec: -18 degC
Inlet gas water content: 1,350 mg/Sm3
Outlet gas water content: 40 mg/Sm3
Available TEG/H2O rate: 20 kg TEG / kg water absorbed

I have been using GPSA Databook and Shell DEP in order to evaluate suitability of this unit for the two locations/services, and it appears that everything is OK.

Do you have any hints, or suggestions what sort of further checks I need to make?
Apart from Contactor/Regenerator, all other equipment items are 100% verified as suitable.

http://antwrp.gsfc.nasa.gov/apod/astropix.html

 

[SJones]

Check whether the materials are suitable for the new gas compositions.

Steve Jones
Materials & Corrosion Engineer

http://www.linkedin.com/pub/8/83b/b04

 

[maddocks]

Build a simulation to see if it verifies design? Shell's DEP's are fairly well done, but a simulation is always a good check.

 

[dcasto]

I don't believe the existing case, there isn't enough heat input, Unless there is something really special with the TEG regeneration syste, I get you need 600 kw.

Next, you have 3 times as many moles/hr in the new case of wet gas with the same water content, therfore you want to remove more water. That means you need even more energy and without detailed packing simulations, I doubt you have enough packing height.

 

[EmmanuelTop]

@ maddocks:

Thank you for your reply. I am not sure how HYSYS can be accurate for these cases that are "on the edge", and how much I can rely on them. The risk of approving the Unit that might not be suitable is quite high when compared to looking for a grassroot solution.

@ dcasto:

Dcasto, the feed gas in the original case is not saturated at given process conditions. Moisture content is 400 mg/Sm3. That is why I believe you've got misleading results.

The second case id 100% saturated gas @ 13 barg and 20 degC. The third case is the same gas (including additional source gas) but compressed to 35 barg and 50 degC. That is why moisture content is the same.

I wonder which standards/software you use for estimating reboiler duty because I see this item as the most critical one in my calculations done so far.

http://antwrp.gsfc.nasa.gov/apod/astropix.html