Method for the treatment of waste gas from a cellulose plant

• US 7,014,684 B2
• Filed: 11/30/2001
• Issued: 03/21/2006
• Est. Priority Date: 12/01/2000
• Status: Expired due to Fees

• Current Assignee: Linde AG (Linde Plc)
• Original Assignee: Linde AG (Linde Plc)
• Inventors: Hiller, Hans, Dietrich, Wolfgang
• Primary Examiner(s): LAWRENCE JR, FRANK M
• Application Number:
  US10/433,088
• Publication Number:
  US 20050098037A1
• Time in Patent Office: 1,572 Days
• Field of Search: 951/49, 951/87, 951/99, 952/16, 952/23, 952/24, 952/37, 962/75, 261/116, 261/DIG.54, 162/29, 162/65, 162/67
• US Class Current: 95/199
• CPC Class Codes: B01D 47/10 Venturi scrubbers
• CPC Class Codes: B01D 53/78 with gas-liquid contact
• CPC Class Codes: B01D 53/8675 Ozone
• CPC Class Codes: D21C 11/06 Treatment of pulp gases; Recovery of the heat content of the gases; Treatment of gases arising from various sources in pulp and paper mills; Regeneration of gaseous SO2, e.g. arising from liquors containing sulfur compounds
• CPC Class Codes: D21C 9/10 Bleaching ; Apparatus therefor

Abstract

A process and a device for cleaning waste gas from pulp production, especially for cleaning waste gases from a bleaching reactor. Aerosols contained in the waste gas are removed and the gaseous impurities are scrubbed out of the waste gas by a scrubbing liquid.

Claims

1. A process comprising:

bleaching pulp with a bleaching gas comprising ozone;

withdrawing a waste gas containing aerosols from said bleaching step;

passing said waste gas through a Venturi scrubber operated with scrubbing water so as to scrub out the aerosols contained in the waste gas; and

passing the waste gas to a different scrubbing step so as to scrub out gaseous impurities from the waste gas by means of a scrubbing liquid (5).

2. A process according to claim 1, wherein the nozzle cross section of the Venturi scrubber (4) is adjustable, and further comprising adjusting the nozzle cross section so as to match the amount of waste gas to be cleaned to the desired degree of cleaning.

3. A process according to claim 1, wherein in said different scrubbing step, the gaseous impurities are scrubbed out in a scrubbing column (5).

4. A process according to claim 1, wherein in said different scrubbing step, the gaseous impurities are scrubbed out in a packed column (5).

5. A process according to claim 1, further comprising withdrawing some of the scrubbing liquid (10) from said further scrubbing step and passing said scrubbing liquid as scrubbing water to the Venturi scrubber (4).

9. A process according to claim 1, wherein pulp fibers in the waste gas are removed from the waste gas before the aerosols are removed.

10. A process according to claim 1, wherein first the aerosols in the waste gas are removed, and then the gaseous impurities are scrubbed out of the waste gas by means of a scrubbing liquid.

11. A process according to claim 2, further comprising withdrawing some of the scrubbing liquid (10) from said different scrubbing step and passing said scrubbing liquid as scrubbing water to the Venturi scrubber (4).

12. A process according to claim 3, further comprising withdrawing some of the scrubbing liquid (10) from said different scrubbing step and passing said scrubbing liquid as scrubbing water to the Venturi scrubber (4).

13. A process according to claim 4, further comprising withdrawing some of the scrubbing liquid (10) from said different scrubbing step and passing said scrubbing liquid as scrubbing water to the Venturi scrubber (4).

14. A process according to claim 10, further comprising withdrawing some of the scrubbing liquid (10) from said different scrubbing step and passing said scrubbing liquid as scrubbing water to the Venturi scrubber (4).

15. A process according to claim 10, wherein said further scrubbing step comprises scrubbing the gaseous impurities out in a scrubbing column (5).

16. A process according to claim 10, wherein in said different scrubbing step, the gaseous impurities are scrubbed out in a packed column (5).

17. A process according to claim 15, further comprising withdrawing some of the scrubbing liquid (10) from said different scrubbing step and passing said scrubbing liquid as scrubbing water to the Venturi scrubber (4).

18. A process according to claim 16, further comprising withdrawing some of the scrubbing liquid (10) from said different scrubbing step and passing said scrubbing liquid as scrubbing water to the Venturi scrubber (4).

19. A process according to claim 18, wherein the nozzle cross section of the Venturi scrubber (4) is adjustable and further comprising adjusting the nozzle cross section so as to match the amount of waste gas to be cleaned to the desired degree of cleaning.

20. A process according to claim 1, wherein the gaseous impurities scrubbed out from the waste gas include chlorine and/or chlorine dioxide.

21. A process according to claim 1, wherein the waste gas containing aerosols withdrawn from said bleaching step includes HCl, H₂SO₄ and/or HNO₃ acids bonded to the aerosols.

6. A process comprising:

bleaching pulp with a bleaching gas comprising ozone and chlorine dioxide;

withdrawing a waste gas containing aerosols from said bleaching step;

passing said waste gas through a Venturi scrubber operated with scrubbing water so as to scrub out the aerosols contained in the waste gas; and

passing the waste gas to a different scrubbing step so as to scrub out gaseous impurities from the waste gas by means of a scrubbing liquid (5).

7. A process according to claim 6, further comprising destroying the ozone in the resultant scrubbed waste gas.

8. A process according to claim 7, wherein the ozone is catalytically (6) destroyed.