Distillation process to separate mixtures containing three or more components

• US 6,116,051 A
• Filed: 05/25/1999
• Issued: 09/12/2000
• Est. Priority Date: 10/28/1997
• Status: Expired due to Fees

• Current Assignee: Air Products and Chemicals Incorporated (Linde Plc)
• Original Assignee: Air Products and Chemicals Incorporated (Linde Plc)
• Inventors: Agrawal, Rakesh, Fidkowski, Zbigniew Tadeusz
• Primary Examiner(s): CAPOSSELA, RONALD C
• Application Number:
  US09/318,150
• Time in Patent Office: 476 Days
• Field of Search: 62/630, 62/643, 62/924, 62/927, 62/635
• US Class Current: 62/630
• CPC Class Codes: B01D 3/146 Multiple effect distillation
• CPC Class Codes: F25J 2200/02 in a single pressure main column system
• CPC Class Codes: F25J 2200/30 using a side column in a single pressure column system
• CPC Class Codes: F25J 2200/38 using pre-separation or distributed distillation before a main column system, e.g. in a at least a double column system
• CPC Class Codes: F25J 2200/50 using multiple (re-)boiler-condensers at different heights of the column
• CPC Class Codes: F25J 2200/72 Refluxing the column with at least a part of the totally condensed overhead gas
• CPC Class Codes: F25J 2210/12 Refinery or petrochemical off-gas
• CPC Class Codes: F25J 2215/62 Ethane or ethylene
• CPC Class Codes: F25J 2215/64 Propane or propylene
• CPC Class Codes: F25J 2215/66 Butane or mixed butanes
• 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 3/0219 Refinery gas, cracking gas, coke oven gas, gaseous mixtures containing aliphatic unsaturated CnHm or gaseous mixtures of undefined nature
• 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: F25J 3/0247 separation of CnHm with 4 carbon atoms or more
• CPC Class Codes: F25J 3/0257 separation of nitrogen from air F25J3/04, production of nitrogen in general C01B21/00
• CPC Class Codes: F25J 3/0261 separation of carbon monoxide production of carbon monoxide containing gas in general C01B32/40, C10J, C10K
• CPC Class Codes: F25J 3/0295 Start-up or control of the process; Details of the apparatus used, e.g. sieve plates, packings
• CPC Class Codes: F25J 3/044 : using a single pressure main column system only F25J3/0446, F25J3/04624, F25J3/04636 take precedence
• CPC Class Codes: F25J 3/0466 : as a parallel working rectification column or auxiliary column system in a single pressure main column system
• CPC Class Codes: F25J 3/04709 : as an auxiliary column system in at least a dual pressure main column system
• CPC Class Codes: F25J 3/04793 : Rectification, e.g. columns; Reboiler-condenser F25J3/0486 takes precedence
• CPC Class Codes: Y10S 62/924 : Argon
• CPC Class Codes: Y10S 62/927 : Natural gas from nitrogen

Abstract

A technique is set forth to reduce the heat requirement of conventional distillation processes which separate feed mixtures containing three or more components. The technique provides a great deal of flexibility in adjusting the temperatures of the required utilities including a scenario where the heat requirement is reduced without a need for additional higher temperature (and more costly) heat utility. In this technique, when a liquid bottoms stream (or gaseous overhead stream) containing two or more components is sent from an earlier column to a subsequent column, then a return vapor (or liquid) stream is implemented between the same locations in the two columns.

Claims

1. A process for the distillation of a feed stream containing three or more components into product streams enriched in the respective components, said process comprising:

(a) feeding the feed stream to a first distillation column;

(b) removing a gaseous stream enriched in the lighter components of the feed stream from the first column at a location above the feed location of the feed stream and either;

(i) feeding a first portion of the gaseous stream to a second column, partially condensing a second portion of the gaseous stream and subsequently feeding the at least partially condensed second portion to the second column at least one separation stage above the feed location of the first portion;

or

(ii) feeding the entire gaseous stream to the second column without any intervening condensation step and removing heat from the second column between the feed location of the gaseous stream and the top of the second column;

(c) removing a liquid stream from the second column at the feed location of the first portion of the gaseous stream with respect to step (b)(i) or the feed location of the entire gaseous stream with respect to step (b)(ii), and feeding the liquid stream to the first column at the removal location of the gaseous stream.

2. The process of claim 1 wherein said heat is removed in step (b) (ii) via removing a gaseous stream from the second column at a location between the feed location of the entire gaseous stream and the top the second column and at least partially condensing said gaseous stream prior to returning it to the second column.

3. The process of claim 1 wherein the feed gas is a mixture selected from the group consisting of a mixture comprising nitrogen, oxygen and argon and a mixture comprising benzene, toluene and xylene.