Process for removing sulfur from sulfur-containing gases

• US 4,804,521 A
• Filed: 11/07/1986
• Issued: 02/14/1989
• Est. Priority Date: 11/07/1986
• Status: Expired due to Fees

• Current Assignee: Board of Regents of the University of Texas System (University of Texas System)
• Original Assignee: Board of Regents of the University of Texas System (University of Texas System)
• Inventors: Rochelle, Gary T., Jozewicz, Wojciech
• Primary Examiner(s): HELLER, GREGORY
• Application Number:
  US06/928,337
• Time in Patent Office: 830 Days
• Field of Search: 423/242 A, 423/242 R, 423/244 A, 423/244 R
• US Class Current: 423/244.04
• CPC Class Codes: B01D 53/501 by treating the gases with a solution or a suspension of an alkali or earth-alkali or ammonium compound
• CPC Class Codes: C01B 17/60 Isolation of sulfur dioxide from gases

Abstract

The present disclosure relates to improved processes for treating hot sulfur-containing flue gas to remove sulfur therefrom. Processes in accorda

The government may own certain rights in the present invention pursuant to EPA Cooperative Agreement CR 81-1531.

Claims

1. A process for reducing the level of sulfur, the sulfur being generally in the form of sulfur dioxide in a sulfur dioxide-containing gas, comprising the steps of:

(a) preparing an aqueous slurry comprising a calcium alkali together with a calcium-reactive silica or alumina which are present in amounts sufficient to allow for the formation of a sulfur dioxide-absorbing component which includes a calcium silicate or calcium aluminate;

(b) heating the slurry to a temperature between about 40° and

about 200°

C. to facilitate in the formation of the sulfur dioxide-absorbing component;

(c) atomizing the slurry into a stream of the sulfur dioxide-containing gas;

(d) drying the resulting atomized droplets so as to form a gas/solid suspension having a gaseous component and a solid component which includes the sulfur dioxide-absorbing component;

(e) retaining the gaseous and solid components in contact in a manner sufficient to allow for the absorption of sulfur dioxide by the absorbing component; and

(f) separating the absorbing component in the form of spent solids from the gas.

2. The process of claim 1 further comprising directing the gas/solid suspension onto a reaction surface to allow for deposition of the solid component onto the surface;

and passing the suspension over the deposited solid component to further effect the absorption of sulfur dioxide by the absorbing component and to effect a separation of the gas from the solid component.

3. The process of claim 2 wherein the reaction surface comprises a bagfilter.

4. The process of claim 1 further comprising carrying the gas/solid suspension in a stream to allow for substantial contact between the gaseous and solid component and separating the solid component from the gas by means of an electrostatic precipitator or cyclone.

5. The method of claim 1 further comprising recycling a portion of the spent solids to the aqueous slurry.

6. The process of claim 1 wherein the slurry comprises an admixture of sulfur doxide-absorbed solids and a calcium alkali.

7. The process of claim 1 wherein the calcium alkali is introduced into the slurry in the form of lime, slaked lime, hydrated lime, calcidic lime, dolomitic lime, calcium hydroxide or calcium oxide and the reactive silica or alumina is introduced in the form of fly ash, clay, bentonite, montmorillonite, activated alumina, or silicic acid.

8. The process of claim 1 wherein the slurry is heated to between about 40°

and about 100°

C. for between about 0.5 and about 48 hours.

9. The process of claim 1 wherein the slurry is heated to between about 40°

and about 60°

C. for between about 2 and about 36 hours.

10. The process of claim 1 wherein the slurry is heated to between about 40°

and about 60°

C. for between about 4 and about 12 hours.

11. The process of claim 1 wherein the slurry is heated to between about 60°

and about 80°

C. for between about 1 and about 24 hours.

12. The process of claim 1 wherein the slurry is heated to between about 60°

and about 80°

C. for between about 2 and about 12 hours.

13. The process of claim 1 wherein the slurry is heated to between about 80°

and about 100°

C. for between about 0.5 and about 12 hours.

14. The process of claim 1 wherein the slurry is heated to between about 80°

and about 100°

C. for between about 1 and about 8 hours.

15. The process of claim 1 wherein the slurry comprises a mass ratio of calcium-reactive silica or alumina to calcium alkali ranging from about 1:

1 to about 16;

1, respectively.

16. The process of claim 1 wherein the slurry comprises a mass ratio of calcium-reactive silica or alumina to calcium alkali ranging from about 1:

1 to about 5;

1, respectively.

17. The process of claim 1 wherein the slurry comprises about 1 to 3 moles of calcium alkali for every mole of sulfur to be removed from the gas.

18. The process of claim 1 wherein the slurry comprises about 1 to 2 moles of calcium alkali for every mole of sulfur to be removed from the gas.

19. The process of claim 1 wherein the slurry further comprises sodium hydroxide in a concentration ranging from about 0.03M to about 1M.

20. The process of claim 1 wherein the slurry further comprises sodium hydroxide in a concentration ranging from about 0.05M to about 0.5M.

21. The process of claim 1 wherein the slurry further comprises sodium hydroxide in a concentration ranging from about 0.1M to about 0.25M.

22. The process of claim 1 wherein the slurry further comprises from about 0.02 to 0.3 moles of sodium hydroxide for every mole of calcium alkali.

23. The process of claim 1 wherein the slury further comprises from about 0.05 to 0.2 moles of sodium hydroxide for every mole of calcium alkali.

24. A process for reducing the level of sulfur, the sulfur being generally in the form of sulfur dioxide in a sulfur dioxide-containing gas, comprising the steps of:

(a) preparing an aqueous slurry comprising a mass ratio of a calcuim-reactive silica or alumina to calcium alkali ranging from about 1;

1 to about 16;

1, respectively, with about 1 to about 3 moles of caloium alkali for every mole of sulfur to be removed from the gas;

(b) heating the slurry to between about 40° and

200°

C. for between about 0.5 and 48 hours;

(c) atomizing the slurry into a stream of the sulfur dioxide-containing gas;

(d) drying the resulting droplets so as to form a gas/solid suspension having a gaseous component and a solid component which includes a sulfur dioxide-adsorbing component;

(e) retaining the gas/solid suspension in a stream to allow for th absorption of sulfur dioxide by the absorbing component; and

(f) removing the sulfur dioxide from the gas by separating the solid component from the gaseous component.