Removal and recovery of sulphur dioxide from gas streams
First Claim
1. A cyclic process for the removal of sulphur dioxide from a sulphur dioxide containing gas stream using an absorbent medium and for the regeneration of the absorbent medium, which comprises:
- (a) contacting said gas stream at substantially atmospheric pressure with an aqueous absorbing medium containing a water-soluble half salt of a diamine at a temperature of from about 10°
to about 60°
C. to absorb sulphur dioxide from said gas stream in amounts of at least about 100 g of sulphur dioxide per kg of absorbing medium, said diamine in free base form having a molecular weight of less than about 300 and said diamine in half salt form having a pKa value for the free nitrogen atom of about 5 to about 7.3, said aqueous absorbing medium containing at least 1 mole of water for each mole of sulphur dioxide to be absorbed and comprising less than about 80 wt. % of water;
(b) stripping gaseous sulphur dioxide from said spent absorbing medium at a temperature of about 50°
to about 110°
C. and at least about 30°
C. greater than said contact temperature to form a regenerated aqueous absorbing medium;
(c) recovering the gaseous sulphur dioxide; and
(d) recycling said regenerated aqueous absorbing medium to said contacting step.
2 Assignments
0 Petitions
Accused Products
Abstract
Sulphur dioxide is removed from gas streams by contacting the gas stream with an absorbing medium containing less than about 80 wt. % of water and the spent absorbing medium subsequently is regenerated by removing absorbed SO2. The absorbing medium comprises amine salt absorbent having at least two amine groups, at least one of which is a salt and at least one of which has a pKa of about 4.5 to 7.3. The absorption is at a temperature of less than about 60° C. The spent absorbing medium is regenerated under conditions such that at least one amine group remains in salt form.
81 Citations
30 Claims
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1. A cyclic process for the removal of sulphur dioxide from a sulphur dioxide containing gas stream using an absorbent medium and for the regeneration of the absorbent medium, which comprises:
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(a) contacting said gas stream at substantially atmospheric pressure with an aqueous absorbing medium containing a water-soluble half salt of a diamine at a temperature of from about 10°
to about 60°
C. to absorb sulphur dioxide from said gas stream in amounts of at least about 100 g of sulphur dioxide per kg of absorbing medium, said diamine in free base form having a molecular weight of less than about 300 and said diamine in half salt form having a pKa value for the free nitrogen atom of about 5 to about 7.3, said aqueous absorbing medium containing at least 1 mole of water for each mole of sulphur dioxide to be absorbed and comprising less than about 80 wt. % of water;(b) stripping gaseous sulphur dioxide from said spent absorbing medium at a temperature of about 50°
to about 110°
C. and at least about 30°
C. greater than said contact temperature to form a regenerated aqueous absorbing medium;(c) recovering the gaseous sulphur dioxide; and (d) recycling said regenerated aqueous absorbing medium to said contacting step. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20)
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21. A cyclic process for the removal of sulphur dioxide from a sulphur dioxide-containing gas stream using an absorbing medium and for the regeneration of the absorbing medium, which comprises;
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(a) contacting said gas stream with an absorbing medium containing (i) water in an amount of at least about 1 mole for each mole of sulphur dioxide to be absorbed up to about 80 weight percent of the medium and (ii) amine salt absorbent having at least two amine groups, at least one of which is a salt and at least one of which is, when in its free form, a group having a pKa in an aqueous medium at 25°
C. of about 4.5 to 7.3 at a temperature up to about 60°
C. sufficient to enable under reference conditions of a partial pressure of 2 mm Hg of sulphur dioxide, at least about 0.5 mole of sulphur dioxide to be reversibly absorbed per mole equivalent of sorbing nitrogen, said absorbent being in an amount sufficient to provide a spent absorbing medium containing at least about 100 grams of sulphur dioxide per kilogram of absorbing medium;(b) removing gaseous sulphur dioxide from the spent absorbing medium at a temperature and pressure sufficient to remove at least about 70 mole percent of the sulphur dioxide absorbed in the contacting step, in the spent absorbing medium to provide a regenerated medium containing absorbent having at least one nitrogen as an amine salt and at least one free sorbing nitrogen; and (c) recovering the gaseous sulphur dioxide; and (d) recycling the regenerated absorbing medium to the contacting step. - View Dependent Claims (22, 23, 24, 25, 26, 27, 28, 29, 30)
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Specification