System and method for desulfurization and denitrification of alumina calcination flue gas, and use

Patent metadata

Field	Value
Publication number	US-11090608-B2
Application number	US-201816768716-A
Country	US
Kind code	B2
Filing date	Mar 20, 2018
Priority date	Dec 21, 2017
Publication date	Aug 17, 2021
Grant date	Aug 17, 2021

Abstract

Disclosed are a system and a method for desulfurization and denitrification of an alumina calcination flue gas, and a use. The system comprises an ozone generator, a red mud pre-impregnation slurry scrubbing tower, and a red mud pre-impregnation tank and a red mud pre-impregnation clear liquid scrubbing tower. NO x in a flue gas is oxidized into a high valence oxynitride by ozone, and with the red mud as an absorbent, the synergistic absorption of SO 2 and NO x in the flue gas is achieved, while the dealkalization of the red mud is achieved. By means of the synergistic catalytic oxidation of metal ions such as Fe 3+ in a red mud slurry and ozone, the synergistic absorption of sulfur and oxynitride is prompted; and the use of a structure of staged absorption in two towers overcomes the problem of the difficulty in absorbing NO 2 with a low O 3 /NO x molar ratio.

First claim

What is claimed is:

1. A system for desulfurization and denitrification of alumina calcination flue gas, comprising: an ozone generator, a red mud pre-impregnation slurry scrubbing tower, a red mud pre-impregnation tank and a red mud pre-impregnation clear liquid scrubbing tower; wherein the red mud pre-impregnation slurry scrubbing tower is provided with a spray layer at a upper part, and a flue gas inlet disposed on a tower wall below the spray layer and connected to an alumina calcination flue gas pipeline; the red mud pre-impregnation clear liquid scrubbing tower is provided with a spray layer at a upper part, and a flue gas inlet disposed on a tower wall below the spray layer; a gas outlet at the top of the red mud pre-impregnation slurry scrubbing tower is connected to the flue gas inlet of the red mud pre-impregnation clear liquid scrubbing tower through a pipeline; the red mud pre-impregnation tank is provided with a clear liquid outlet at an upper part and a slurry outlet at a lower part, wherein the clear liquid outlet is connected to a spray liquid inlet of the spray layer in the red mud pre-impregnation clear liquid scrubbing tower, and the slurry outlet is connected to a spray liquid inlet of the spray layer in the red mud pre-impregnation slurry scrubbing tower; and a gas outlet of the ozone generator is connected to the alumina calcination flue gas pipeline and to the pipeline between the gas outlet at the top of the red mud pre-impregnation slurry scrubbing tower and the flue gas inlet of the red mud pre-impregnation clear liquid scrubbing tower, separately.

2. The system of claim 1 , comprising: a first ozone homogenizer and a second ozone homogenizer, wherein the first ozone homogenizer is disposed on the alumina calcination flue gas pipeline, the second ozone homogenizer is disposed on the pipeline between the gas outlet at the top of the red mud pre-impregnation slurry scrubbing tower and the flue gas inlet of the red mud pre-impregnation clear liquid scrubbing tower, the gas outlet of the ozone generator is connected to the first ozone homogenizer and the second ozone homogenizer, separately, and ozone is homogenized in pipelines by the first ozone homogenizer and the second ozone homogenizer.

3. The system of claim 1 , comprising: a demister and a chimney, wherein a flue gas outlet at the top of the red mud pre-impregnation clear liquid scrubbing tower is connected to the demister and the chimney in sequence.

4. The system of claim 1 , wherein a red mud pre-impregnation slurry pond is disposed between the slurry outlet of the red mud pre-impregnation tank and the spray liquid inlet of the spray layer in the red mud pre-impregnation slurry scrubbing tower.

5. The system of claim 1 , wherein the red mud pre-impregnation slurry scrubbing tower is provided with a bottom liquid outlet connected to the spray liquid inlet of the spray layer in the red mud pre-impregnation slurry scrubbing tower.

6. The system of claim 1 , wherein a red mud pre-impregnation clear liquid pond is disposed between the clear liquid outlet of the red mud pre-impregnation tank and the spray liquid inlet of the spray layer in the red mud pre-impregnation clear liquid scrubbing tower.

7. The system of claim 1 , wherein the spray liquid inlet of the spray layer in the red mud pre-impregnation slurry scrubbing tower is connected to a process water pipeline.

8. The system of claim 1 , wherein the bottom liquid outlet of the red mud pre-impregnation slurry scrubbing tower is connected to a material inlet of the red mud pre-impregnation tank.

9. The system of claim 1 , wherein a dewatering pond is disposed between the bottom liquid outlet of the red mud pre-impregnation slurry scrubbing tower and the material inlet of the red mud pre-impregnation tank, and a clear liquid outlet at an upper part of the dewatering pond is connected to the material inlet of the red mud pre-impregnation tank.

10. The system of claim 1 , wherein the red mud pre-impregnation clear liquid scrubbing tower is provided with a bottom liquid outlet connected to the spray liquid inlet of the spray layer in the red mud pre-impregnation clear liquid scrubbing tower.

11. The system of claim 1 , wherein preferably, the bottom liquid outlet of the red mud pre-impregnation clear liquid scrubbing tower is connected to a liquid inlet of the red mud pre-impregnation clear liquid pond.

12. A method for desulfurization and denitrification of alumina calcination flue gas, comprising:
(a) transporting the alumina calcination flue gas mixed with ozone to a red mud pre-impregnation slurry scrubbing tower for reverse spraying with a slurry obtained after red mud pre-impregnation, so as to obtain a flue gas after a primary treatment and a red mud slurry after the spraying; and
(b) mixing the flue gas after the first treatment in step (a) with ozone before transporting to a red mud pre-impregnation clear liquid scrubbing tower for reverse spraying with a clear liquid obtained after the red mud pre-impregnation, so as to obtain a treated flue gas and a red mud clear liquid after the spraying.

13. The method of claim 12 , wherein the method is performed by the system for desulfurization and denitrification of alumina calcination flue gas of claim 1 .

14. The method of claim 12 , wherein a molar ratio of the ozone to remaining NO x in the flue gas after the primary treatment in step (b) is (0.1-1.0):1.

15. The method of claim 12 wherein a molar ratio of the ozone to NO x in the alumina calcination flue gas in step (a) is (0.4-1.5):1.

16. The method of claim 12 wherein the red mud pre-impregnation in step (a) comprises: pre-impregnating and layering a red mud generated in an alumina calcination process in a red mud pre-impregnation tank, wherein the slurry is obtained at a lower layer, and the clear liquid is obtained at an upper layer.

17. The method of claim 12 wherein no additives are added during the red mud pre-impregnation.

18. The method of claim 12 wherein a pH of the clear liquid obtained after the red mud pre-impregnation in step (b) is 7-12.

19. The method of claim 12 wherein the red mud clear liquid after the spraying in step (b) is returned to a spray layer in the red mud pre-impregnation clear liquid scrubbing tower as spray water to be recycled.

Assignees

• Inst Process Eng Cas

Inventors

• Zhu Tingyu
• Liu Xiaolong
• Wang Xue
• Ning Ruliang

Classifications

• B01D53/1431

  Pretreatment by other processes · CPC title

• B01D53/8637 Primary

  Simultaneously removing sulfur oxides and nitrogen oxides · CPC title

• Y02A50/20

  Air quality improvement or preservation, e.g. vehicle emission control or emission reduction by using catalytic converters · CPC title

• B01D53/80

  Semi-solid phase processes, i.e. by using slurries · CPC title

• B01D2258/02

  Other waste gases · CPC title