Effectively Separate Liquid/Liquid Dispersions on Medium, Coarse, or Higher Solids Emulsions

The AquaSep EL system is a multiple-stage system starting with filtration to remove particulate matter, followed by either a one-stage horizontal coalescer or a two-stage integrated vertical coalescer/separator stack to separate the two liquid phases. AquaSep EL coalescers will remove free water to a level as low as 15 ppmv1 and be effective over a wide range of conditions such as inlet liquid contaminant concentration as high as 10% and interfacial tension less than 20 dynes/cm.

 

Table 1: Coalescer Selection Guide

 

Process Condition	Recommended Product
The dispersed phase fluid is aqueous and a horizontal footprint is acceptable	AquaSep EL coalescer in a horizontal housing without separator
The dispersed phase fluid is oil and the continuous phase fluid is aqueous
The dispersed phase fluid is aqueous and minimal footprint is required	AquaSep EL coalescer/separator stack in a vertical housing

 

AquaSep EL Coalescer— Horizontal Housing Configuration

In a horizontal housing, the liquid/liquid mixture enters the coalescing element and flows inside-to-outside, small liquid dispersed phase droplets suspended in the continuous phase come together, or coalesce, as the mixture moves through the AquaSep EL coalescer. The large coalesced droplets of the dispersed phase separated by gravity in the horizontal housing and are removed. The size of the housing is a function of the flow rate, IFT, viscosity, and specific gravity of the liquids.

 

Figure 3: AquaSep EL Liquid/Liquid Separation System with Coalescer in a Horizontal Housing with a Prefilter

AquaSep EL Coalescer/Separator Stack— Vertical Housing Configuration

The liquid/liquid mixture enters the coalescing element and flows inside-to-outside. Small liquid droplets suspended in the continuous phase come together, or coalesce, as the mixture moves through the coalescer medium.
Contaminant-free liquid and large droplets of the dispersed phase flow toward the separator located directly below the coalescer stage. The flow is outside- to- inside. The separator medium is hydrophobic preventing the aqueous phase from entering the separator. Only the non-aqueous continuous phase fluid flows through the separator. The two liquids are removed by separate drain connections.

Figure 4: AquaSep EL Liquid/Liquid Separation System with an Integrated Coalescer/Separator Stack in a Vertical Housing with a Prefilter

Typical Applications

Not all coalescers provide a high quantitative removal of dispersed liquid contaminants and can handle emulsions with low interfacial tensions (IFTs). For example, conventional cartridge and mesh pack coalescers made of glass fiber media begin to lose efficiency when the IFT of the emulsion gets below 20 dynes/cm. In contrast, the new AquaSep EL coalescer from Pall is constructed of a high-efficiency, polymeric medium, making it well suited for numerous liquid/liquid separation applications with very low IFTs including:

• Water removal from hydrocarbon condensates before stabilization, fractionation or pipeline transport
• Removal of oil from sour water to protect sour water stripping (SWS) as well as downstream sulfur plant and water treatment operations
• Water removal from high solids coker fractionates
• Performance upgrades to existing cartridge or mesh pack coalescers, sand beds and ESPs
• General oil/water separation needs across upstream, midstream, and downstream processes

Maximum operating temperature	60 °C/140 °F
Maximum differential pressure	3.4 bard/50 psid at 21 °C/70 °F
Recommended change-out	1.0 bard /15 psid at 21 °C/70 °F

Comparative Performance

 

Pall’s new AquaSep EL liquid/liquid coalescer system is a lower-cost solution to separate higher solids and medium to coarse emulsions versus competitive cartridge coalescers, mesh pack coalescers, sand beds, and electrostatic precipitators (ESPs). Its cost-effectiveness is due to the ability of each coalescer element to process a higher flow in a higher solids environment while still providing superior effluent quality. For existing cartridge coalescer systems, the AquaSep EL element provides superior continuous removal of liquid contaminant thereby making it a more reliable solution than competitive offerings. See Figures 1 and 2 below.

 

 

 

Product Benefits

 

Features	Advantages	Benefits
High Performance, Coarse Grade Polymeric Medium	Up to 60% higher flow per coalescing element	Smaller, lower-cost system
	Reduced incidents of off-spec product	Eliminates reprocessing, product degradation, and transportation costs Reduces costly corrosion problems in downstream equipment Prevents catalyst deactivation in downstream processes
	The longer service life of coalescer and prefilter elements on higher solids applications	Lower operating costs versus less efficient alternative solutions Mesh pack coalescers, salt driers, electrostatic separators, and sand filters Fewer cartridge change-outs reduced maintenance costs, and waste disposal costs
	Tolerant to process upsets, can remove slugs of liquids	Consistent fluid quality
Non-disarming Medium	The medium does not disarm in the presence of surfactants. Disarming occurs when surfactants (either natural or additives) “coat” the surface of the medium	Consistent fluid quality Eliminates ongoing labor costs to change out disarmed glass fiber coalescer elements or mesh packs
	Ability to separate emulsions with IFTs lower than 20 dynes/cm	Reliable use of liquid/liquid coalescers on challenging applications such as hydrocarbon condensate, sour water stripping (SWS), coker fractionates, L/L separation upgrades, and general high-efficiency water/oil separation needs
Availability of a High-Performance Integrated Stack Design— Coalescer and Separator	Higher flow per cartridge because of even flow distribution. In conventional two-stage systems, the separators are located at different distances from the coalescers. This causes poor flow distribution.	Consistent fluid quality Smaller, lower-cost system

 

Coalescers