APV’s Leading Edge Solution for Rich/Lean Amine Interchange

Amines including Sulfinols are employed to carry high concentrations of hydrogen sulfide and carbon dioxide in the rich stream, which recovers heat from the hotter lean stream. The upper operating temperatures are typically between 100 and 140 Celsius.

The Challenge

Our customers naturally employ high efficiency plate heat exchangers because of their natural advantages over shell and tubes –

• Ability to achieve a high heat recovery thus minimizing the running costs of these very large plants
• A far lower capital cost,
• A much smaller space requirement,
• Flexibility not available with alternatives, etc.

However, some of these customers have had frustrations with their plate heat exchangers – unavoidable until now.

The Final Solution

Between APV, a customer and gasket manufacturer, it was agreed that BL welded pairs with complete TFE-P gaskets will provide the 5-year plus life required for these exchangers. 8 very large heat exchangers were refitted with this new APV Paramine system that involved a complete overhaul of the detailed gasket design. The alterations made to the design are proprietary and made specifically to suit this service. At the time of writing, July 2000, the first installation has completed 22 months of service without incident. 4 units run on MDEA and 4 on Sulfinol.

Qualitative Comparisons with Alternatives

Here are some pros and cons with alternative technologies:

	Conventional PHE	APV Paramine	Fully Welded
Seal life	Can be very short, e.g. ½ year at 135°C	Expect 5 years at 140°C	Not an issue except corrosion or fatigue cracking of welds which can cause total replacement needs
Flexibility to re-arrange/expand	Fully flexible	Fully flexible	None
Ability to inspect for sulfide fouling, lean stream, and clean manually or in chemicals	Open & inspect	Open & inspect	Usually no ability to inspect
Ability to inspect for rich fouling	Open & inspect	Not available	Usually no ability to inspect
Resistance to thermal stresses	Excellent	Excellent	Inherent weakness
Repairable?	Individual plates & gaskets can be replaced	Individual pairs and gaskets can be replaced	Usually impossible
	Conventional PHE	APV Paramine	Fully Welded
Compact	Yes	Yes	Usually not
Liquid hold up	Low	Low	Usually high
Fouling	Usually good experience although fouling must be allowed for and controlled via high shear	Excellent experience so far with 3mm gap. Infrequent in-place cleaning employed	Non-compact-higher fouling. Compact – plugging risks
Capital cost guide for large applications with high recovery	Lowest	Higher	Very high
Medium term ownership costs for high temperature sour applications	High	Low	Higher

 

 

Conclusion

Bearing in mind its flexibility, heat transfer performance, ability to achieve close temperature approaches, resistance to thermal gradient stresses and long term field testing in amine service, the APV Paramine System is the system of choice for large sour gas amine interchanges. It also follows that other amine service devoid of sour gas will also benefit greatly if the APV Paramine System is employed.