High propane recovery process and configurations

• US 7,073,350 B2
• Filed: 04/15/2004
• Issued: 07/11/2006
• Est. Priority Date: 08/11/2000
• Status: Expired due to Term

• Current Assignee: Fluor Enterprises Incorporated (Fluor Corporation)
• Original Assignee: Fluor Technologies Corporation (Fluor Corporation)
• Inventors: Mak, John
• Primary Examiner(s): DOERRLER, WILLIAM CHARLES
• Application Number:
  US10/826,438
• Publication Number:
  US 20040250569A1
• Time in Patent Office: 817 Days
• Field of Search: 626/25, 626/32, 626/35, 626/36
• US Class Current: 62/625
• CPC Class Codes: F25J 2200/02 in a single pressure main column system
• CPC Class Codes: F25J 2200/04 in a dual pressure main column system
• CPC Class Codes: F25J 2200/70 Refluxing the column with a condensed part of the feed stream, i.e. fractionator top is stripped or self-rectified
• CPC Class Codes: F25J 2200/74 Refluxing the column with at least a part of the partially condensed overhead gas
• CPC Class Codes: F25J 2200/78 Refluxing the column with a liquid stream originating from an upstream or downstream fractionator column
• CPC Class Codes: F25J 2205/04 in the feed line, i.e. upstream of the fractionation step
• CPC Class Codes: F25J 2220/66 Separating acid gases, e.g. CO2, SO2, H2S or RSH
• CPC Class Codes: F25J 2230/60 the fluid being hydrocarbons or a mixture of hydrocarbons
• CPC Class Codes: F25J 2240/02 Expansion of a process fluid in a work-extracting turbine (i.e. isentropic expansion), e.g. of the feed stream
• CPC Class Codes: F25J 2270/90 External refrigeration, e.g. conventional closed-loop mechanical refrigeration unit using Freon or NH3, unspecified external refrigeration
• CPC Class Codes: F25J 2290/10 Mathematical formulae, modeling, plot or curves; Design methods
• CPC Class Codes: F25J 2290/12 Particular process parameters like pressure, temperature, ratios
• CPC Class Codes: F25J 2290/40 Vertical layout or arrangement of cold equipments within in the cold box, e.g. columns, condensers, heat exchangers etc.
• CPC Class Codes: F25J 3/0209 Natural gas or substitute natural gas
• CPC Class Codes: F25J 3/0233 separation of CnHm with 1 carbon atom or more
• CPC Class Codes: F25J 3/0238 separation of CnHm with 2 carbon atoms or more
• CPC Class Codes: F25J 3/0242 separation of CnHm with 3 carbon atoms or more
• CPC Class Codes: Y02C 20/40 of CO2

Abstract

A gas processing plant has a de-ethanizer and a refluxed absorber, wherein the absorber operates at higher pressure than the de-ethanizer, and wherein at least a portion of the absorber bottoms product is expanded to provide cooling for the absorber reflux stream and/or the distillation column feed stream. Especially contemplated gas processing plants include propane and ethane recovery plants, and where the gas processing plant is an ethane recovery plant, it is contemplated that the ethane product comprises no more than 500 ppm carbon dioxide.

Claims

1. A gas processing plant comprising:

a refluxed absorber operating at a first pressure, producing a bottoms product stream and receiving a feedstock and an absorber reflux stream;

a distillation column fluidly coupled to the absorber, receiving a distillation column feed stream, producing a distillation column overhead stream, and operating at a second pressure that is at least 100 psi lower than the first pressure;

wherein at least a portion of the bottoms product stream is expanded and provides cooling for at least one of the absorber reflux stream and the distillation column feed stream;

wherein the distillation column overhead stream is separated into a fluid portion that provides reflux for the distillation column and a gaseous portion that is liquefied and provides the absorber reflux stream;

wherein the distillation column comprises a de-ethanizer column, and wherein the feedstock is at a pressure of between 1000 psig and 2000 psig;

wherein the bottoms product stream has a pressure and wherein expanding the bottoms product stream reduces the bottoms product stream pressure in a range of 100–

250 psi;

wherein the expanded bottoms product stream further provides cooling for a distillation column overhead stream; and

wherein at least a portion of the feedstock is expanded in a turboexpander.

2. The gas processing plant of claim 1 wherein the expanded bottoms product stream has a temperature between −

95°

F. to −

125°

F.

3. The gas processing plant of the claim 1 wherein the expanded absorber bottoms product stream is fed as the distillation column feed stream into the distillation column at a position that is at least three trays below an upmost tray of the distillation column.

4. The gas processing plant of claim 1 wherein the distillation column produces a distillation column overhead stream that is compressed, cooled, and fed into the absorber as the absorber reflux stream.

5. The gas processing plant of claim 1 wherein the feedstock comprises propane, and wherein the distillation column produces a distillation column product stream that comprises at least 95% of the propane in the feedstock.