US 11,686,528 B2
Single column nitrogen rejection unit with side draw heat pump reflux system and method
Peter J. Turner, The Woodlands, TX (US); Douglas A. Ducote, Jr., The Woodlands, TX (US); and Timothy P. Gushanas, Pearland, TX (US)
Assigned to Chart Energy & Chemicals, Inc., Ball Ground, GA (US)
Filed by Chart Energy & Chemicals, Inc., Ball Ground, GA (US)
Filed on Apr. 1, 2020, as Appl. No. 16/837,039.
Claims priority of provisional application 62/837,439, filed on Apr. 23, 2019.
Prior Publication US 2020/0340740 A1, Oct. 29, 2020
Int. Cl. F25J 3/02 (2006.01)
CPC F25J 3/0257 (2013.01) [F25J 3/0209 (2013.01); F25J 2200/02 (2013.01); F25J 2200/50 (2013.01); F25J 2200/72 (2013.01); F25J 2205/04 (2013.01); F25J 2270/12 (2013.01)] 15 Claims
OG exemplary drawing
 
1. A system for removing nitrogen from a natural gas fluid feed stream comprising:
a. a main heat exchanger including a main feed cooling passage, a withdrawn vapor warming passage, a main reflux stream cooling passage, a reflux vapor cooling passage, a vapor portion cooling passage, and a nitrogen vapor return passage, said main feed cooling passage including an inlet and an outlet, where the inlet of the main feed cooling passage is configured to receive the natural gas fluid feed stream;
b. a distillation column including a first feed inlet and a second feed inlet, a return vapor outlet, a side vapor outlet port, first and second reflux inlet ports and a bottoms liquid outlet, wherein said side vapor outlet port and said first and second reflux inlet ports are positioned between the feed inlet and the return vapor outlet;
c. said side vapor outlet port of the distillation column configured to provide vapor to the withdrawn vapor warming passage of the main heat exchanger, said return vapor outlet of the distillation column configured to provide nitrogen vapor to said nitrogen vapor return passage of the main heat exchanger and said first reflux inlet port of the distillation column is in fluid communication with the reflux vapor cooling passage of the main heat exchanger;
d. a reflux compressor configured to receive and compress fluid from the withdrawn vapor warming passage of the main heat exchanger;
e. a reflux aftercooler configured to receive and cool fluid from the reflux compressor and direct cooled fluid to the main reflux stream cooling passage of the main heat exchanger;
f. a reflux separation device configured to receive fluid from the main reflux stream cooling passage of the main heat exchanger, said reflux separation device having a vapor outlet and a liquid outlet, wherein the vapor outlet of the reflux separation device is configured to direct fluid to the reflux vapor cooling passage of the main heat exchanger and the liquid outlet of the reflux separation device is configured to direct fluid to the second reflux inlet port of the distillation column;
g. an expansion device configured to receive and partially condense a cooled natural gas fluid feed stream from the main feed cooling passage of the main heat exchanger;
h. a main feed separation device configured to receive a mixed phase stream from the expansion device, said main feed separation device including a vapor outlet and a liquid outlet, wherein the liquid outlet is configured to direct a liquid stream to the first feed inlet of the distillation column;
i. said vapor portion cooling passage configured to receive and cool a vapor stream from the vapor outlet of the main feed separation device and direct a resulting cooled stream to the second feed inlet of the distillation column.