Method and compositions for removing acid gases from gaseous mixtures and reducing corrosion of ferrous surface areas in gas purification systems

• US 3,896,212 A
• Filed: 09/17/1973
• Issued: 07/22/1975
• Est. Priority Date: 02/01/1966
• Status: Expired due to Term

• Current Assignee: Eickmeyer & Associates Incorporated
• Original Assignee: Allen G. Eickmeyer
• Inventors: Eickmeyer, Allen G.
• Primary Examiner(s): Thomas, Earl C.
• Application Number:
  US05/398,066
• Time in Patent Office: 673 Days
• Field of Search: 423/220,223,226-229,232,233 252/189,190,192
• US Class Current: 423/223
• CPC Class Codes: B01D 53/1406 Multiple stage absorption
• CPC Class Codes: B01D 53/1412 Controlling the absorption process
• CPC Class Codes: B01D 53/1456 Removing acid components
• CPC Class Codes: B01D 53/1462 Removing mixtures of hydrogen sulfide and carbon dioxide
• CPC Class Codes: B01D 53/1468 Removing hydrogen sulfide
• CPC Class Codes: B01D 53/1493 Selection of liquid materials for use as absorbents
• CPC Class Codes: B01D 53/526 Mixtures of hydrogen sulfide and carbon dioxide
• CPC Class Codes: C10K 1/10 with aqueous liquids alkaline reacting aqueous liquids C10K1/12
• CPC Class Codes: C23F 11/06 in markedly alkaline liquids
• CPC Class Codes: Y02C 20/40 of CO2
• CPC Class Codes: Y02P 20/151 Reduction of greenhouse gas [GHG] emissions, e.g. CO2

Abstract

The invention relates to an absorption desorption composition and process employing said composition for selectively removing acidic gases, particularly carbon dioxide (CO2) and hydrogen sulphide (H2S) from gaseous mixtures, said composition comprising an aqueous solution containing a major proportion of alkali metal salts, potassium carbonate and potassium borate, a minor proportion of a catalytic activator, and a corrosion inhibitor when required, with provision for maintaining the inhibitor in an effective condition and in condition to perform its corrosion reducing function; the process characterized by two stages of absorption and desorption connected in a circulating system for the fluids being processed with suitable temperature and pressure controls, whereby an increased amount of the contaminating gases are removed and corrosive and side reaction difficulties reduced to a minimum.

Claims

1. IN AN ABSORPORTION-DESORPTION PROCESS FOR REMOVING CARBON DIOXIDE FROM A GASOUS MIXTURE CONTAINING SUBSTANTIALLY NO OXYGEN OR HYDROGEN SULFIDE, WHEREIN SAID MIXTURE IS CONTRACTED WITH AN AQUOUS OBSORPTION SOLUTION COMPRISING AT LEAST POTASSIUM SALT SELECTED FROM THE GROUP CONSISTNG OF POTASSIUM CARBONATE, POTASSIUM BORATE AND MIXTURES THEREOF, SAID SOLUTION THEREAFTER BEING REGENERATED BY REMOVING AT LEAST A PORTION OF THE ABSORBED CARBON DIOXIDE AND THENCE RECYCLED FOR FURTHER ABSORPTIVE CONTACT WITH SAID GASEOUS MIXTURE, THE IMPROVEMENT WHICH COMPRISES:

ADDING A SMALL AMOUNT OF A CORROSION INHIBITOR SELECTED FROM THE GROUP CONSISTING OF THE SODIUM, POTASSIUM AND AMMONIUM METAVANDATES AND POXYVANADATES TO SAID AQUEOUS ABSORPTION SOLUTION, AND CONTACTING SAID ABSORPTION SOLUTION WITH A SMALL AMOUNT OF AN OXIDIZING AGENT SELECTED FROM THE GROUP CONSISTING OF AIR, OXYGEN HYDROGEN PEROXIDE AND THE ALKALI METALS DICHROMATES, SAID OXIDIZING AGENT BEING PRESENT IN AN AMOUNT SUFFECIENT TO MAINTAIN MOST OF SAID CORROSION INHIBITOR IN AN OXIDIZED CONDITION.

2. The method of claim 1, wherein said corrosion inhibitor is present in an amount of from about 0.05 to 2 percent by weight.

3. The method of claim 1, wherein said oxidizing agent is air.

4. A method of inhibiting corrosion of ferrous metal surfaces in a carbon dioxide absorption process wherein carbon dioxide is removed from a gaseous mixture containing substantially no oxygen or hydrogen sulfide therein, said method comprising:

contacting said gaseous mixture with an aqueous absorption solution comprising at least one potassium salt selected from the group consisting of potassium carbonate, potassium borate and mixtures thereof, an amine catalyst selected from the group consisting of monoethanolamine, diethanolomine and diethanolomine borate, and a minor amount of a corrosion inhibitor selected from the group consisting of the sodium, potassium and ammonium metavandates and peroxyvanadates, to thereby absorb a fraction of the carbon dioxide from said gaseous mixture;

regenerating the aqueous absorption solution containing the absorbed carbon dioxide by removing at least a portion thereof from the solution;

recycling at least a portion of said regenerated solution for absorptive contact with said gaseous mixtures; and

contacting said absorption solution with an oxidizing agent selected from the group consisting of air, hydrogen peroxide, oxygen and the alkali metal dichromates, said oxidizing agent being present in an amount sufficient to maintain said corrosion inhibitor in an oxidized condition.

5. The method of claim 4, wherein said potassium salt is present in amount of from about 10 to 40 percent by weight.

6. The method of claim 4, wherein said amine catalyst is present in an amount from about 3 to 12 percent.

7. The method of claim 4, wherein said corrosion inhibitor is present in an amount of from about 0.05 to 2 percent by weight.

8. The method of claim 4, wherein said oxidizing agent is air.

9. In a method of separating carbon dioxide from gaseous mixtures containing substantially no oxygen or hydrogen sulfide and for simultaneously inhibiting corrosion of ferrous metal surfaces, wherein said gaseous mixture is contacted with an aqueous absorption solution comprising about 25 percent by weight potassium carbonate and about 0.2 percent by weight potassium vanadate, the improvement which comprises contacting said absorption solution with a small amount of air, thereby maintaining most of said potassium vanadate in an oxidized Condition.