Refinery gas upgrading via partial condensation and PSA

• US 8,535,415 B2
• Filed: 08/10/2012
• Issued: 09/17/2013
• Est. Priority Date: 12/05/2006
• Status: Active Grant

• Current Assignee: Praxair Technology Incorporated (Linde Plc)
• Original Assignee: Praxair Technology Incorporated (Linde Plc)
• Inventors: Dragomir, Ramona Manuela, Drnevich, Raymond Francis, Bonaquist, Dante Patrick
• Primary Examiner(s): LAWRENCE JR, FRANK M
• Application Number:
  US13/571,801
• Publication Number:
  US 20120304688A1
• Time in Patent Office: 403 Days
• Field of Search: 95/96, 951/43, 961/21, 626/17, 626/18, 626/36
• US Class Current: 95/96
• CPC Class Codes: B01D 2256/16 Hydrogen
• CPC Class Codes: B01D 2259/416 involving cryogenic temperature treatment
• CPC Class Codes: B01D 53/047 Pressure swing adsorption
• CPC Class Codes: C01B 2203/0465 Composition of the impurity
• CPC Class Codes: C01B 2203/0475 the impurity being carbon dioxide
• CPC Class Codes: C01B 2203/048 the impurity being an organic compound
• CPC Class Codes: C01B 2203/0485 the impurity being a sulfur compound
• CPC Class Codes: C01B 2203/0495 the impurity being water
• CPC Class Codes: C01B 3/506 at low temperatures
• CPC Class Codes: C01B 3/56 by contacting with solids; Regeneration of used solids C01B3/508 takes precedence
• 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 2205/04 in the feed line, i.e. upstream of the fractionation step
• CPC Class Codes: F25J 2205/40 using hybrid system, i.e. combining cryogenic and non-cryogenic separation techniques
• CPC Class Codes: F25J 2205/80 using membrane, i.e. including a permeation step
• CPC Class Codes: F25J 2210/02 Multiple feed streams, e.g. originating from different sources
• CPC Class Codes: F25J 2210/12 Refinery or petrochemical off-gas
• CPC Class Codes: F25J 2245/02 Recycle of a stream in general, e.g. a by-pass stream
• 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 3/0252 : separation of hydrogen production of hydrogen containing gas in general C01B3/00, e.g. separation of hydrogen or hydrogen containing gases form gaseous mixtures at low temperatures C01B3/506
• CPC Class Codes: F25J 3/062 : Refinery gas, cracking gas, coke oven gas, gaseous mixtures containing aliphatic unsaturated CnHm or gaseous mixtures of undefined nature
• CPC Class Codes: F25J 3/0635 : separation of CnHm with 1 carbon atom or more
• CPC Class Codes: F25J 3/0655 : separation of hydrogen production of hydrogen containing gas in general C01B3/00, e.g. separation of hydrogen or hydrogen containing gases form gaseous mixtures at low temperatures C01B3/506

Abstract

A process and system for recovering valuable by-products (e.g., hydrogen) from refinery gas streams. For hydrogen-only recovery, the invention comprises a partial condensation step to upgrade the refinery fuel gas to a minimum of 60% hydrogen, which is further purified in a pressure swing adsorption process. When configured to recover hydrogen, methane-rich gas and raw LPG (methane depleted gas containing C2 hydrocarbons and heavier), the invention comprises two partial condensation steps where the feed is cooled in the first step to allow separation of ethane and heavier hydrocarbons, and the resulting vapor is cooled to a lower temperature in a second step for hydrogen recovery.

Claims

1. A process for recovering high purity hydrogen from a feed gas containing less than 50 mole % hydrogen comprising the steps of:

a) cooling a feed gas in one or more heat exchangers and producing a partially condensed feed gas;

b) separating the partially condensed feed gas to produce a hydrogen-rich stream and a hydrocarbon-rich stream;

c) generating refrigeration by Joule-Thomson expansion of the hydrocarbon-rich stream and producing a colder hydrocarbon-rich stream;

d) recovering refrigeration from the colder hydrocarbon-rich stream to cool the feed gas in step (a);

e) recovering refrigeration from the hydrogen-rich stream to cool the feed gas in step (a);

f) recovering a gas stream containing at least 60 mole % hydrogen from the hydrogen-rich stream; and

g) feeding the gas stream containing at least 60 mole % hydrogen to a pressure swing adsorption (PSA) system and recovering high purity hydrogen product with or without feeding an external hydrogen-containing stream to the PSA system.

2. The process of claim 1, wherein in step (g), a low pressure tailgas comprising methane, residual hydrogen and other non-readily condensable compounds leaves the PSA system.

3. The process of claim 1, wherein the feed gas contains between 30-50 mole % hydrogen.

4. The process of claim 3, wherein the feed gas is at a temperature of about 100°

F. and 50-120 psia.

5. The process of claim 1, wherein the high purity hydrogen product contains at least 99 mole % hydrogen.