Standalone high-pressure heavies removal unit for LNG processing
Implementations described and claimed herein provide systems and methods for processing liquefied natural gas (LNG). In one implementation, a dry feed gas is received. The dry feed gas is chilled with clean vapor from a heavies removal column to form a chilled feed gas. The chilled feed gas is partially condensed into a vapor phase and a liquid phase. The liquid phase retains freezing components. The freezing components are extracted using a reflux stream in the heavies removal column. The freezing components are removed as a condensate. The vapor phase is compressed into a clean feed gas. The clean feed gas is free of the freezing components for downstream liquefaction.
1 . A method for reducing solid deposition during liquefaction in a liquefied natural gas (LNG) facility, the method comprising:
receiving a partially condensed feed gas at a heavies removal column following an expansion of a chilled feed gas, the heavies removal column including an upper section and a lower section, the partially condensed feed gas received at the upper section;
receiving a reflux stream at the upper section of the heavies removal column;
extracting freezing components from the partially condensed feed gas disposed in the heavies removal column using the reflux stream;
removing the freezing components from the heavies removal column as a condensate;
outputting a clean vapor free of the freezing components from the heavies removal column for downstream liquefaction;
forming a first portion of the clean vapor and a second portion of the clean vapor;
chilling one or more feed streams using the first portion of the clean vapor;
separating an overhead vapor from a stabilizer into a liquid stream and a vapor stream using a stabilizer reflux drum;
forming a partially condensed liquid stream from the liquid stream, using a heavies removal column reflux condenser; and
producing, in a reflux cooler, the reflux stream using the second portion of the clean vapor and the partially condensed liquid stream.
2 . The method of claim 1 , wherein:
the second portion of the clean vapor includes a slip stream vapor of the clean vapor.
3 . The method of claim 1 , further comprising:
outputting a bottoms liquid containing the freezing components from the lower section of the heavies removal column.
4 . The method of claim 1 , wherein the reflux stream is an internally generated stream or an external natural gas liquids (NGL) stream.
5 . The method of claim 1 , wherein liquid is removed from the chilled feed gas prior to the expansion of the chilled feed gas, the liquid directed to the lower section of the heavies removal column.
6 . A method for reducing solid deposition during liquefaction in a liquefied natural gas (LNG) facility, the method comprising:
forming a partially condensed feed gas by partially condensing a chilled feed gas into a vapor phase and a liquid phase;
receiving the partially condensed feed gas at a heavies removal column, the heavies removal column including an upper section and a lower section, the partially condensed feed gas received at the upper section;
extracting freezing components from the partially condensed feed gas disposed in the heavies removal column using a reflux stream received by the upper section of the heavies removal column;
removing the freezing components from the heavies removal column as a condensate;
forming a first portion and a second portion of a clean feed gas that is output by the heavies removal column, the clean feed gas being free of the freezing components for downstream liquefaction;
compressing the first portion of the clean feed gas;
separating an overhead vapor from a stabilizer into a liquid stream and a vapor stream in a stabilizer reflux drum;
forming a partially condensed liquid stream from the liquid stream, using a heavies removal column reflux condenser; and
producing the reflux stream using the second portion of the clean feed gas and the partially condensed liquid stream in a reflux cooler.
7 . The method of claim 6 , wherein liquid is removed from the chilled feed gas prior to forming the partially condensed feed gas, the liquid directed to the lower section of the heavies removal column.
8 . The method of claim 6 , wherein the partially condensed feed gas is formed by expanding the chilled feed gas.
9 . The method of claim 6 , wherein the reflux stream is an internally generated stream or an external natural gas liquids (NGL) stream.
10 . The method of claim 6 , wherein the second portion of the clean feed gas is a slip stream vapor that condenses light components distilled during removal of the freezing components to produce the reflux stream.
11 . The method of claim 10 , wherein the light components are C4 and lighter and the freezing components are C5 and higher.
12 . A system for reducing solid deposition during liquefaction in a liquefied natural gas (LNG) facility, the system comprising:
a heavies removal column configured to receive a partially condensed feed gas, the heavies removal column being a standalone heavies removal unit and including an upper section and a lower section, the partially condensed feed gas configured to be received at the upper section;
a top bed of the upper section of the heavies removal column configured to receive a reflux stream, the reflux stream configured to extract freezing components from the partially condensed feed gas for removal as a condensate from the heavies removal column, the heavies removal column configured to output a clean vapor free of freezing components for downstream liquefaction;
a feed gas exchanger configured to receive a dry feed gas and a first portion of the clean vapor from the heavies removal column, the feed gas exchanger chilling the dry feed gas with the clean vapor to form a chilled feed gas;
a stabilizer reflux drum configured to separate an overhead vapor from a stabilizer into a liquid stream and a vapor stream;
a heavies removal column reflux condenser configured to form a partially condensed liquid stream from the liquid stream; and
a reflux cooler configured to receive a second portion of the clean vapor from the heavies removal column and the partially condensed liquid stream, the reflux cooler producing the reflux stream using the second portion of the clean vapor and the partially condensed liquid stream.
13 . The system of claim 12 ,
wherein the lower section of the heavies removal column is configured to output a bottoms liquid containing the freezing components.
14 . The system of claim 12 , wherein the reflux stream is produced using a slip stream vapor of the clean vapor.
15 . The system of claim 12 , wherein the standalone heavies removal unit is deployed upstream of a liquefaction process or integrated with the liquefaction process.
16 . The system of claim 12 , further comprising:
a turboexpander configured to partially condense the chilled feed gas into a vapor phase and a liquid phase, the liquid phase retaining the freezing components.
17 . The system of claim 16 , further comprising:
an expander suction drum, the chilled feed gas configured to flow through the expander suction drum prior to entering the turboexpander, the expander suction drum removing liquid from the chilled feed gas, the liquid fed into the lower section of the heavies removal column.
18 . The system of claim 12 , further comprising:
a compressor configured to provide compression of the first portion of the clean vapor.