Process for removing carbon dioxide from combustion exhaust gas

• US 5,344,627 A
• Filed: 01/15/1993
• Issued: 09/06/1994
• Est. Priority Date: 01/17/1992
• Status: Expired due to Term

• Current Assignee: Kansai Electric Power Company Incorporated, Mitsubishi Jukogyo Kabushiki Kaisha
• Original Assignee: Kansai Electric Power Company Incorporated, Mitsubishi Jukogyo Kabushiki Kaisha
• Inventors: Kobayashi, Kenji, Iijima, Masaki, Yoshida, Kunihiko, Karasaki, Mutsunori, Mitsuoka, Shigeaki, Shimojo, Shigeru, Seto, Touru, Fujii, Masumi, Hotta, Yoshitsugu, Suda, Taiichiro
• Primary Examiner(s): Straub, Gary P.
• Assistant Examiner(s): Vanoy, Timothy C.
• Application Number:
  US08/002,830
• Time in Patent Office: 599 Days
• Field of Search: 423/437, 423/220, 423/226, 423/437 M, 423/437 R, 95/39, 95/40, 55/268, 55/DIG. 30, 62/4, 62/17, 62/116, 62/11
• US Class Current: 423/220
• CPC Class Codes: B01D 53/1418 Recovery of products
• CPC Class Codes: B01D 53/1475 Removing carbon dioxide
• CPC Class Codes: E21B 41/0057 Disposal of a fluid by injection into a subterranean formation
• CPC Class Codes: F25J 1/0027 Oxides of carbon, e.g. CO2
• CPC Class Codes: F25J 1/0052 by vaporising a liquid refrigerant stream
• CPC Class Codes: F25J 1/0095 Oxides of carbon, e.g. CO2
• CPC Class Codes: F25J 1/0204 as a single flow SCR cycle
• CPC Class Codes: F25J 1/0282 Steam turbine as the prime mechanical driver
• CPC Class Codes: F25J 2210/70 Flue or combustion exhaust gas
• CPC Class Codes: F25J 2220/80 Separating impurities from carbon dioxide, e.g. H2O or water-soluble contaminants
• CPC Class Codes: F25J 2230/22 Compressor driver arrangement, e.g. power supply by motor, gas or steam turbine
• CPC Class Codes: F25J 2230/30 Compression of the feed stream
• CPC Class Codes: F25J 2240/70 Steam turbine, e.g. used in a Rankine cycle
• CPC Class Codes: Y02C 20/40 of CO2
• CPC Class Codes: Y10S 55/30 Exhaust treatment

Abstract

A process for removing carbon dioxide (CO₂) from a combustion exhaust gas of a boiler (1) which generates steam for driving high (3), intermediate (7), and low (8) pressure turbines. The process comprises the steps of removing CO₂ in the combustion exhaust gas by absorption with a CO₂ -absorbing liquid (19), liquefying the removed CO₂ (28) by compression (42) and cooling (48), storing (52) the CO₂, and regenerating the CO₂ -absorbing liquid by a CO₂ -absorbing liquid regeneration column (24) equipped with a reboiler (30). In the process, a part (40) of steam discharged from the high pressure turbine (3) is used to drive turbines (41, 43) for compressors (42, 44) that compress the CO₂, and a refrigerant for cooling the CO₂, and steam (45) discharged from the compressor turbines is supplied as a heating source to the reboiler (30) for the regeneration of the CO₂ -absorbing liquid. A decrease in the overall power plant efficiency due to the removal of carbon dioxide from the exhaust gas can be reduced.

Claims

1. A process for removing carbon dioxide (CO₂) from a combustion exhaust gas of a boiler generating steam conducted to a first high pressure turbine, a second intermediate pressure turbine operating at a pressure lower than said first turbine, and a third low pressure turbine operating at a pressure lower than said second turbine for driving said turbines, comprising:

removing CO₂ in said combustion exhaust gas by absorbing said CO₂ in a CO₂ -absorbing liquid;

providing a CO₂ -absorbing liquid regeneration column having a reboiler;

conducting said CO₂ -absorbing liquid through said absorbing liquid regeneration column for regenerating said CO₂ -absorbing liquid;

providing a fourth turbine operatively connected to a first compressor for driving said first compressor thereby;

providing a fifth turbine operatively connected to a second compressor for driving said second compressor thereby;

conducting a part of steam discharged from said first turbine to said fourth and fifth turbines;

driving said fourth and fifth turbines by said part of steam discharged from said first turbine;

driving said first and second compressors by said fourth and fifth turbines, respectively;

conducting said removed CO₂ to said first compressor and compressing said removed CO₂ therein;

conducting said compressed CO₂ from said first compressor to a cooler;

passing a refrigerant through said second compressor and through said cooler for cooling and liquifying said compressed CO₂ ;

storing said liquified CO₂ ; and

conducting steam discharged from said first and second compressor turbines to said reboiler as a heating source for said reboiler for regeneration of said CO₂ -absorbing liquid.

2. The process as claimed in claim 1 and further comprising:

extracting steam from said third turbine; and

conducting said extracted steam from said third turbine to said reboiler together with said steam discharged from said fourth and fifth turbines and conducted to said reboiler.