Olefin recovery units
Petrochemical plants and refineries use distillation to separate olefins, e.g. ethane/ethylene, propane/propylene, and butane/butene. The columns used for olefin separation are often referred to as splitters, more specifically C2, C3, and C4 splitters respectively. Because these columns contain a large number of separation stages, they are commonly referred to as superfractionators. 

Koch-Glitsch has developed specific thermodynamic packages to accurately represent the subtle nuances of low pressure, medium pressure, and high pressure ethane/ethylene and propane/propylene separations. Koch-Glitsch has created grassroots designs to optimize project economics that include reduced column count and size and minimized energy consumption while providing the maximum throughput capacity. In addition, Koch-Glitsch has participated in numerous revamps to improve the performance of existing assets.

Superfractionators (C2, C3, and C4 splitters)
C2 splitters often have over 90-100 stages, C3 splitters usually have 150 to 200 stages, and C4 splitters have between 60 and 90 stages.  Trays are most frequently used in these towers because of the challenging system properties and the high reflux rates that result in elevated internal liquid traffic. Random packings have been used in some smaller splitter towers, but their only benefit compared to trays is lower pressure drop which is usually of little advantage, even in towers that use vapor recompression.

New towers

FLEXITRAY® valve trays combine high capacity and excellent efficiency with a wide operating range.

New towers are frequently sized based on conventional FLEXITRAY® valve trays. This may result in a larger initial tower diameter, but leaves the option open to later revamp the tower using SUPERFRAC® trays for increased throughput.

In these services, SUPERFRAC® trays provide proven increased capacity and tray efficiency compared to conventional trays. This can be used to reduce the required tray count or reduce energy consumption while allowing operation at the highest throughput capacity for a crossflow tray device. Following the development of new ultra-high- capacity trays, designing new splitter towers using SUPERFRAC® trays is becoming a more frequently accepted practice. The SUPERFRAC® tray is a high performance cross-flow tray that has the highest combined capacity and efficienty of all cross-flow trays tested at FRI.
Revamps
Koch-Glitsch supplies SUPERFRAC® trays not only for new columns, but many columns have also been successfully revamped by Koch-Glitsch from conventional trays to SUPERFRAC® trays. In collaboration with Koch Heat Transfer, the associated heat exchanger bundles can be revamped along with the tower internals in one turnkey package to further improve the revamp potential for your existing operations.
For even higher capacities, ULTRA-FRAC® trays can be installed in these applications. Counterflow and cross-flow trays have a limiting vapor velocity that is set by the fluid properties alone. This maximum vapor velocity is referred to as the “system limit“ because it is independent of the tray design. ULTRA-FRAC® trays use co-current flow to break through this system limit. When ULTRA-FRAC® trays are installed, distillation columns can process much larger fluid volumes than with counter-flow or cross-flow devices installed. A typical capacity gain of more than 30% can be achieved even when revamping a tower that already has high capacity counterflow or crossflow type trays installed. The ULTRA-FRAC® tray is the highest capacity mass transfer device tested at FRI.


 

 

 

 

Products

Trays

FLEXITRAY® valve trays

SUPERFRAC® trays

ULTRA-FRAC® trays


Literature

Revamp & retune; Nieuwoudt, Karpilovskiy, and Lockett; Hydrocarbon Engineering, 2009.