Debottlenecking Saturates Gas Plants

Typically part of the crude unit or just downstream is the sats gas plant. As the crude unit is expanded, the sats gas plant capacity may need to be increased. Depending on the unit configuration and bottlenecks, there are many potential bottlenecks and expansion options. One typical limit is flooding in the bottom of the debutanizer. Packing is an option, but may not sufficiently debottleneck the tower since high pressure applications may not show significant capacity increases with packing.

One option that may not be obvious, but can have significant benefits is additional feed preheat. Additional feed preheat reduces the fractionating load on the bottom section of the tower. Also, feed preheat debottlenecks the reboiler. Increasing the feed preheat can increase the tower capacity by over 25% in some cases. This significant increase is much cheaper than building a new tower.

Another Saturates Gas Plant example is in propane production. Propane typically has a vapor pressure specification which limits the allowable ethane content. Plants often run their saturated and unsaturated deethanizers conservatively so that little or no ethane remains in the propane. However, to maximize profitability, the amount of ethane in the propane should be maximized since this allows ethane to be sold at liquid fuel propane price rather than ethane gas price. The effect can be even more dramatic since it unloads the deethanizers. The reduced load upon the deethanizers may allow higher charge rates. At the very least, it reduces energy consumption while maximizing higher valued liquid product sales.