Distillation column minimum flow arrangement
A distillation system operating below minimum flow. The distillation column is configured for separating a mixed feed into one or more fractional mixtures, producing an overhead product and a bottom product. A bottom return line is provided for returning at least a portion of the bottom product to supplement the mixed feed to the distillation column. A control valve is configured for controlling a flow rate in the bottom return line. A feed surge drum is configured for receiving a feed from the bottom return line and fresh feed, producing the mixed feed.
1 . A distillation system comprising:
a distillation column configured for separating a mixed feed into one or more fractional mixtures, producing an overhead product comprising methane, ethane, carbon dioxide, hydrogen sulfide, or combinations thereof and a bottom product;
a bottom return line configured for returning at least a portion of the bottom product to supplement a fresh feed;
a control valve configured for controlling a flow rate in the bottom return line;
a feed surge drum configured for receiving the fresh feed and the bottom product from the bottom return line, producing the mixed feed;
a vent line connected to the feed surge drum for venting one or more components comprising methane, ethane, carbon dioxide, or hydrogen sulfide from the feed surge drum; and
an overhead vapor line connected to the vent line for collecting and combining the overhead product comprising methane, ethane, carbon dioxide, hydrogen sulfide, or combinations thereof directly produced from a top of the distillation column and the one or more components in the vent line directly from the feed surge drum.
2 . The system of claim 1 further comprising:
a reboiler configured for heating at least a portion of the distillation column bottom product, to generate a hot vapor return;
a hot vapor return line configured for redistributing the hot vapor from the reboiler to the distillation column as a stripping medium and;
a bottom product cooler, and
wherein the bottom return line is configured for transferring at least a portion of the bottom product from the bottom product cooler to the feed surge drum as the bottom product.
3 . The system of claim 1 , further comprising:
a feed surge drum sump configured for removing an aqueous or emulsion phase from the feed surge drum.
4 . The system of claim 1 , wherein;
a bottom product cooler is configured to reduce a temperature of the bottom product before it is mixed with the fresh feed.
5 . The system of claim 1 , wherein;
at least a portion of the overhead product is cooled and returned to the distillation column as reflux.
6 . A distillation system configured as an NGL stripper, comprising:
a distillation column configured for separating a mixed feed of NGL into one or more fractional mixtures, producing an overhead product comprising methane, ethane, carbon dioxide, hydrogen sulfide, or combinations thereof and an NGL bottom product;
a bottom return line configured for returning at least a portion of the NGL bottom product to a feed surge drum;
a control valve configured for controlling a flow rate in the bottom return line;
wherein the feed surge drum is configured for receiving a fresh feed and a portion of the bottom product from the bottom return line, producing the mixed feed of NGL;
a vent line connected to the feed surge drum for venting one or more components comprising methane, ethane, carbon dioxide, or hydrogen sulfide from the feed surge drum; and
an overhead vapor line connected to the vent line for collecting and combining the overhead product comprising methane, ethane, carbon dioxide, hydrogen sulfide, or combinations thereof directly produced from a top of the distillation column and the one or more components directly from the feed surge drum.
7 . The system of claim 6 further comprising:
a reboiler configured for heating a portion of the NGL bottom product;
a hot vapor return line configured for returning a hot vapor from the reboiler to the distillation column as a stripping medium; and
a bottom product cooler, and
wherein the bottom return line is configured for transferring a portion of NGL bottom product from the bottom product cooler to the feed surge drum as the bottom product.
8 . The system of claim 6 , further comprising:
a feed surge drum sump configured for removing an aqueous phase or emulsion phase from the feed surge drum.
9 . The system of claim 7 , wherein the bottom product cooler is configured to reduce a temperature of the NGL bottom product return line.