Flue gas desulfurization and carbon sequestration device

Abstract

The utility model discloses a flue gas desulfurization and carbon sequestration device which comprises a desulfurization tower, a decarbonization tower, a heat exchanger and a red mud stirring tank, an absorption tank I is arranged at the bottom of the desulfurization tower; an absorption tank II is arranged at the bottom of the decarbonization tower; a flue gas inlet I is formed in the lower part of the desulfurization tower, and a flue gas outlet I is formed in the upper end; a flue gas inlet II is formed in the lower part of the decarbonization tower, and a flue gas outlet II is formed in the upper end; the first smoke outlet communicates with an inlet of the heat exchanger, and an outlet of the heat exchanger communicates with the second smoke inlet. A liquid inlet and a feeding hole are formed in the upper end of the red mud stirring tank; a clear liquid overflow hole I is formed in the upper part of the red mud stirring tank; the liquid outlet is communicated with the absorption tank II through a pipeline III; a red mud pump I is arranged on the pipeline III; the absorption tank II is communicated with the absorption tank I through a pipeline IV. According to the utility model, the flue gas is subjected to desulfurization, mineralization and carbon sequestration treatment by using the red mud, and aluminum hydroxide in the red mud slurry is recovered, so that desulfurization and decarbonization integrated treatment and resource utilization of the red mud and the flue gas are realized.

Description

Technical Field

[0001] The utility model relates to the technical field of flue gas treatment, in particular to a flue gas desulfurization and carbon fixation device. Background Art

[0002] Red mud is an industrial solid waste discharged when alumina is extracted in the aluminum industry. In the development of the electrolytic aluminum industry, the treatment and comprehensive utilization of red mud is a global problem. According to statistics, in 2023, the national alumina production was 81.86 million tons, the red mud production was 105 million tons, and the utilization was 8 million tons. The comprehensive utilization rate of resources was only 7.6%, which was far lower than other bulk industrial solid wastes. It has gradually become a bottleneck restricting the sustainable development of the aluminum industry. Strong alkalinity is the most significant feature of red mud, and it is also a difficult problem restricting its comprehensive utilization.

[0003] There is a good synergistic effect between "pollution reduction" and "carbon reduction", which is determined by my country's high-carbon energy structure and high-energy consumption industries. In addition, atmospheric pollutants and greenhouse gases often come from similar sources, so reducing greenhouse gas emissions while reducing atmospheric pollutant emissions has certain synergistic benefits. At present, the use of limestone / lime-gypsum wet SO2 removal process in industry has become a common desulfurization method, but this process has the problems of high cost and relatively difficult maintenance. The by-product gypsum output is very large, causing secondary pollution to the environment. At the same time, the process will increase CO2 emissions. For every kg of SO2 absorbed, 0.69 kg of CO2 will be emitted. At present, the most common technology in industrial CO2 capture technology is liquid absorption. The essence of liquid absorption method to capture CO2 is to use alkaline solution to contact and react chemically with CO2 in flue gas to form unstable salts. Under certain conditions, the salts will reversely decompose to release CO2 and regenerate the absorbent at the same time, thereby achieving the separation and capture of CO2 from flue gas. Organic amine solutions such as ethanolamine (MEA), diethanolamine (DEA) and other commonly used liquid absorbents have relatively mature application processes and high absorption efficiency, but there are problems such as high energy consumption for operation and absorbent regeneration, and organic amines are prone to corrosion of equipment. Therefore, how to reduce energy consumption and improve the comprehensive utilization rate of red mud is a technical problem that needs to be solved urgently.

[0004] Once the strong alkalinity of red mud is used to neutralize and absorb sulfur dioxide and carbon dioxide, it can not only reduce the alkalinity of red mud, but also reduce the emission of sulfur dioxide and carbon dioxide in industry. The presence of soluble alkali in red mud can neutralize and remove acidic substances (such as sulfides, nitrides and fluorides) in flue gas. In addition, red mud is rich in metal oxides such as Fe and Ca. This component is the most common active component in H2S desulfurizers in industrial oxygen-free or low-oxygen gases, so it is extremely advantageous in absorbing carbon dioxide and sulfur dioxide. If red mud can be used for desulfurization and decarbonization in industrial gas, it can alleviate the problem of large-scale storage of red mud in my country, and it can also greatly reduce the cost of desulfurization and decarbonization. Utility Model Content

[0005] The technical problem to be solved by the utility model is to provide a device for desulfurizing and fixing carbon in flue gas.

[0006] In order to solve the above technical problems, the technical solution of the utility model is:

[0007] A device for desulfurization and carbon fixation of flue gas, comprising a desulfurization tower, a decarbonization tower, a heat exchanger and a red mud slurry stirring tank; the bottom of the desulfurization tower is an absorption tank 1 for accommodating red mud slurry; the bottom of the decarbonization tower is an absorption tank 2 for accommodating red mud slurry; a flue gas inlet 1 is arranged at the lower part of the desulfurization tower, and a flue gas outlet 1 is arranged at the upper end; multiple layers of desulfurization absorption spray layers and desulfurization demisters are arranged in sequence upward above the flue gas inlet 1 in the desulfurization tower; the inlet of the desulfurization absorption spray layer is connected with the absorption tank 1 through a pipeline 1; a desulfurization tower absorption liquid spray pump is arranged on the pipeline 1; a flue gas inlet 2 is arranged at the lower part of the decarbonization tower, and a flue gas outlet 2 is arranged at the upper end; the decarbonization tower, located above the flue gas inlet 2, In the direction, multiple layers of decarbonization spray layers and combined demisters are arranged in sequence; the inlet of the decarbonization spray layer is connected with the absorption tank two through pipe two; the decarbonization tower absorption liquid spray pump is arranged on the pipe two; the lower part of the desulfurization tower is provided with an air inlet for introducing air into the red mud slurry therein; the flue gas outlet one is connected with the inlet of the heat exchanger, and the outlet of the heat exchanger is connected with the flue gas inlet two; the lower end of the red mud slurry stirring tank is provided with a liquid outlet, the upper end is provided with a liquid inlet and a feed inlet, and the upper part is provided with a clear liquid overflow port one; the liquid outlet is connected with the absorption tank two through pipe three, and a red mud slurry pump one is arranged on the pipe three; the absorption tank two is connected with the absorption tank one through pipe four; the absorption tank one is provided with a slurry discharge port at the bottom.

[0008] Preferably, it also includes a red mud residue sedimentation tank, a neutralization tank, and a filter press; the slurry discharge port is connected to the feed port of the red mud residue sedimentation tank through a pipeline five, the lower discharge port of the red mud residue sedimentation tank is connected to the inlet of the filter press one through a pipeline six, a clear liquid overflow port two is provided on the upper part of the red mud residue sedimentation tank, the clear liquid overflow port two is connected to the inlet of the neutralization tank, and the clear liquid overflow port two is connected to the inlet of the neutralization tank through a pipeline seven; the discharge port of the filter press one is connected to the inlet of the neutralization tank; a desulfurization slurry pump is provided on the pipeline five, and a red mud slurry pump two is provided on the pipeline six.

[0009] Preferably, it also includes a filter press 2 and an aluminum hydroxide precipitation tank; the liquid outlet of the neutralization tank is connected to the inlet of the aluminum hydroxide precipitation tank, the lower discharge port of the aluminum hydroxide precipitation tank is connected to the inlet of the filter press 2 through a pipe 8, and an aluminum hydroxide precipitation slurry pump is provided on the pipe 8; a clear liquid overflow port 3 is provided on the upper part of the aluminum hydroxide precipitation tank, and is connected to the liquid inlet of the red mud slurry stirring tank through a pipe 9; the discharge port of the filter press 2 is connected to the liquid inlet through a pipe 10.

[0010] Preferably, it also includes an aluminum hydroxide calciner and an aluminum oxide storage reservoir; the solid material discharge port of the second filter press is connected to the feed port of the aluminum hydroxide calciner, and the discharge port of the aluminum hydroxide calciner is connected to the entrance of the aluminum oxide storage reservoir.

[0011] The above technical solution has the following advantages:

[0012] The utility model uses red mud for desulfurization and decarbonization in industrial gas, realizes desulfurization and carbon fixation of industrial flue gas, can not only reduce the alkalinity of red mud, but also absorb the SO2 and CO2 content in flue gas to achieve desulfurization and carbon emission reduction, and then effectively resolve the problem of large-scale storage of red mud in my country. After red mud is used for desulfurization and decarbonization, it can effectively purify the alumina therein, thereby achieving resource utilization of solid waste red mud. At the same time, it can also significantly reduce the cost of desulfurization and decarbonization, solving the technical problem of high cost of flue gas desulfurization and decarbonization. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is a schematic diagram of the device in the utility model;

[0014] In the figure:

[0015] 1-desulfurization tower, 2-decarbonization tower, 3-heat exchanger, 4-red mud slurry stirring tank, 5-absorption tank 1, 6-absorption tank 2, 7-flue gas inlet 1, 8-flue gas outlet 1, 9-desulfurization absorption spray layer, 10-desulfurization demister, 11-pipeline 1, 12-desulfurization tower absorption liquid spray pump, 13-flue gas inlet 2, 14-flue gas outlet 2, 15-decarbonization spray layer, 16-combined demister, 17-pipeline 2, 18-decarbonization tower absorption liquid spray pump, 19-oxidation air inlet, 20-liquid outlet, 21-liquid inlet, 22-feeding port, 23-clear liquid overflow Flow outlet one, 24-pipeline three, 25-red mud pump one, 26-pipeline four, 27-slurry discharge outlet, 28-red mud residue sedimentation tank, 29-neutralization tank, 30-filter press one, 31-pipeline five, 32-pipeline six, 33-clear liquid overflow outlet two, 34-pipeline seven, 35-desulfurization slurry pump, 36-red mud pump two, 37-alumina storage tank, 38-filter press two, 39-aluminum hydroxide sedimentation tank, 40-pipeline eight, 41-aluminum hydroxide sedimentation slurry pump, 42-clear liquid overflow outlet three, 43-pipeline nine, 44-pipeline ten, 45-aluminum hydroxide calciner. DETAILED DESCRIPTION

[0016] The specific implementation methods of the present invention are further described below in conjunction with the accompanying drawings. It should be noted that the description of these implementation methods is used to help understand the present invention, but does not constitute a limitation of the present invention. In addition, the technical features involved in each implementation method of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0017] As attached Figure 1As shown, a device for desulfurization and carbon fixation of flue gas comprises a desulfurization tower 1, a decarbonization tower 2, a heat exchanger 3 and a red mud slurry stirring tank 4; the bottom of the desulfurization tower 1 is an absorption tank 5 for accommodating red mud slurry; the bottom of the decarbonization tower 2 is an absorption tank 6 for accommodating red mud slurry; the lower part of the desulfurization tower 1 is provided with a flue gas inlet 7, and the upper end is provided with a flue gas outlet 8; in the desulfurization tower 1, multiple layers of desulfurization absorption spray layers 9 and desulfurization demisters 10 are sequentially arranged above the flue gas inlet 7; the inlet of the desulfurization absorption spray layer 9 is connected with the absorption tank 5 through a pipeline 11; a desulfurization tower absorption liquid spray pump 12 is arranged on the pipeline 11; the lower part of the decarbonization tower 2 is provided with a flue gas inlet 13, and the upper end is provided with a flue gas outlet 14; in the decarbonization tower 2, multiple layers of desulfurization absorption spray layers 9 and desulfurization demisters 10 are sequentially arranged above the flue gas inlet 13 A multi-layer decarbonization spray layer 15 and a combined demister 16 are provided; the inlet of the decarbonization spray layer 15 is connected to the absorption tank 2 6 through a pipe 2 17; a decarbonization tower absorption liquid spray pump 18 is provided on the pipe 2 17; an oxidizing air inlet 19 is provided at the lower part of the desulfurization tower 1 for introducing air into the red mud slurry therein; the flue gas outlet 18 is connected to the inlet of the heat exchanger 3, and the outlet of the heat exchanger 3 is connected to the flue gas inlet 2 13; a liquid outlet 20 is provided at the lower end of the red mud slurry stirring tank 4, a liquid inlet 21 and a feed inlet 22 are provided at the upper end, and a clear liquid overflow port 23 is provided at the upper part; the liquid outlet 20 is connected to the absorption tank 2 6 through a pipe 3 24, and a red mud slurry pump 25 is provided on the pipe 3 24; the absorption tank 2 6 is connected to the absorption tank 1 5 through a pipe 4 26; a slurry discharge port 27 is provided at the bottom of the absorption tank 1 5.

[0018] As a further improved technical solution of this embodiment, it also includes a red mud slag sedimentation tank 28, a neutralization tank 29, and a filter press 30; the slurry discharge port 27 is connected with the feed port of the red mud slag sedimentation tank 28 through a pipeline 5 31, and the lower discharge port of the red mud slag sedimentation tank 28 is connected with the inlet of the filter press 30 through a pipeline 6 32. A clear liquid overflow port 2 33 is provided on the upper part of the red mud slag sedimentation tank 28, and the clear liquid overflow port 2 33 is connected with the inlet of the neutralization tank 29, and the clear liquid overflow port 2 33 is connected with the inlet of the neutralization tank 29 through a pipeline 7 34; the discharge port of the filter press 30 is connected with the inlet of the neutralization tank 29; a desulfurization slurry pump 35 is provided on the pipeline 5 31, and a red mud slurry pump 2 36 is provided on the pipeline 6 32.

[0019] As a further improved technical solution of this embodiment, it also includes a filter press 2 38 and an aluminum hydroxide precipitation tank 39; the liquid outlet of the neutralization tank 29 is connected to the inlet of the aluminum hydroxide precipitation tank 39, and the lower discharge port of the aluminum hydroxide precipitation tank 39 is connected to the inlet of the filter press 2 38 through a pipe 8 40, and an aluminum hydroxide precipitation slurry pump 41 is provided on the pipe 8 40; a clear liquid overflow port 3 42 is provided on the upper part of the aluminum hydroxide precipitation tank 39, and is connected to the liquid inlet 21 of the red mud slurry stirring tank 4 through a pipe 9 43; the discharge port of the filter press 2 38 is connected to the liquid inlet 21 through a pipe 10 44.

[0020] As a further improved technical solution of this embodiment, it also includes an aluminum hydroxide calciner 45 and an aluminum oxide storage tank 37; the solid material discharge port of the filter press 38 is connected to the feed port of the aluminum hydroxide calciner 45, and the discharge port of the aluminum hydroxide calciner 45 is connected to the entrance of the aluminum oxide storage tank 37.

[0021] The specific usage of the device is as follows:

[0022] 1. Preparation of red mud slurry: the red mud in the red mud slurry stirring tank 4 is configured according to a set solid-liquid ratio, and calcium hydroxide is added to adjust the pH. The red mud slurry obtained after stirring is pumped to the absorption tank 2 6, and the red mud slurry in the absorption tank 2 6 overflows into the absorption tank 1 5;

[0023] 2. Flue gas desulfurization and cooling. The flue gas to be treated first enters the absorption tank 5 from the flue gas inlet 1. The red mud slurry in the absorption tank 5 effectively absorbs SO2 in the flue gas in the desulfurization tower 1 to generate calcium sulfate and aluminum sulfate. The desulfurized flue gas is defogged by the desulfurization demister 10 and then enters the heat exchanger 3 for cooling to 20-25°C.

[0024] 3. Flue gas decarbonization: the flue gas after desulfurization is cooled and then enters the absorption tank 2 6 for red mud flue gas mineralization and carbon fixation. The flue gas is sprayed by the multi-layer decarbonization spray layer 15 to absorb CO2, and then passes through the combined demister 16 for demisting before being discharged;

[0025] 4. Post-treatment of red mud slurry. The red mud residue in the absorption tank 5 is pumped to the red mud residue sedimentation tank 28 for precipitation by the desulfurization slurry pump 35. The precipitate enters the filter press 30 for filtration. The filtrate containing aluminum sulfate enters the neutralization tank 29 for neutralization to form aluminum hydroxide precipitate. The aluminum hydroxide precipitate is filtered by the filter press 38 and then enters the aluminum hydroxide calciner 45 for calcination into alumina and then packaged for sale. The filtrate returns to the red mud slurry stirring tank 4 as slurry adjustment water.

[0026] The utility model utilizes the strong alkalinity of red mud to neutralize and absorb sulfur dioxide and carbon dioxide, which can not only reduce the alkalinity of red mud, but also reduce the emission of sulfur dioxide and carbon dioxide in industry. The soluble alkali present in red mud can neutralize and remove acidic substances (such as sulfide, nitride and fluoride) in flue gas. In addition, red mud is rich in metal oxides such as Fe and Ca, which are the most common active components in H2S desulfurizers in industrial anaerobic or low-oxygen gases. Therefore, it is extremely advantageous to use red mud to absorb carbon dioxide and sulfur dioxide.

[0027] According to tests, the utility model uses red mud produced in the electrolytic aluminum industry to remove SO2 and CO2 from flue gas, and the SO2 absorption efficiency in the flue gas can reach more than 99%, and the CO2 absorption efficiency can reach more than 85%.

[0028] The embodiments of the present invention are described in detail above with reference to the accompanying drawings, but the present invention is not limited to the described embodiments. For those skilled in the art, various changes, modifications, substitutions and variations of these embodiments are made without departing from the principles and spirit of the present invention, and still fall within the scope of protection of the present invention.

Claims

1. A flue gas desulfurization and carbon fixation device, comprising a desulfurization tower (1), a decarbonization tower (2), a heat exchanger (3) and a red mud slurry stirring tank (4); the bottom of the desulfurization tower (1) is an absorption tank (5) for containing red mud slurry; the bottom of the decarbonization tower (2) is an absorption tank (6) for containing red mud slurry; the lower part of the desulfurization tower (1) is provided with a flue gas inlet (7), and the upper end is provided with a flue gas outlet (8); the desulfurization tower (1) is provided with multiple layers of desulfurization absorption spray layers (9) and desulfurization demisters (10) in sequence above the flue gas inlet (7); the inlet of the desulfurization absorption spray layer (9) is The decarbonization tower (2) is connected to the first absorption tank (5) through a pipe (11); the first absorption tank (5) is provided with a desulfurization tower absorption liquid spray pump (12); the lower part of the decarbonization tower (2) is provided with a second flue gas inlet (13), and the upper end is provided with a second flue gas outlet (14); in the decarbonization tower (2), multiple layers of decarbonization spray layers (15) and a combined demister (16) are sequentially arranged upward above the second flue gas inlet (13); the inlet of the decarbonization spray layer (15) is connected to the second absorption tank (6) through a pipe (17); the second absorption tank (6) is provided with a decarbonization tower absorption liquid spray pump (18); the characteristics are: The lower part of the desulfurization tower (1) is provided with an oxidizing air inlet (19) for introducing air into the red mud slurry therein; the flue gas outlet 1 (8) is communicated with the inlet of the heat exchanger (3), and the outlet of the heat exchanger (3) is communicated with the flue gas inlet 2 (13); the red mud slurry stirring tank (4) is provided with a liquid outlet (20) at the lower end, a liquid inlet (21) and a feed inlet (22) at the upper end, and a clear liquid overflow outlet 1 (23) at the upper part; the liquid outlet (20) is communicated with the absorption tank 2 (6) through a pipeline 3 (24), and a red mud slurry pump 1 (25) is provided on the pipeline 3 (24); the absorption tank 2 (6) is communicated with the absorption tank 1 (5) through a pipeline 4 (26); and a slurry discharge outlet (27) is provided at the bottom of the absorption tank 1 (5).

2. The device for flue gas desulfurization and carbon fixation according to claim 1, characterized in that: It also includes a red mud sedimentation tank (28), a neutralization tank (29), and a filter press (30); the slurry discharge port (27) is connected to the feed port of the red mud sedimentation tank (28) through a pipeline (31); the lower discharge port of the red mud sedimentation tank (28) is connected to the inlet of the filter press (30) through a pipeline (32); a clear liquid overflow port (33) is provided at the top of the red mud sedimentation tank (28); the clear liquid overflow port (33) is connected to the inlet of the neutralization tank (29) through a pipeline (34); the discharge port of the filter press (30) is connected to the inlet of the neutralization tank (29); a desulfurization slurry pump (35) is provided on the pipeline (31), and a red mud slurry pump (36) is provided on the pipeline (32).

3. The device for flue gas desulfurization and carbon fixation according to claim 2, characterized in that: It also includes a filter press 2 (38) and an aluminum hydroxide precipitation tank (39); the liquid outlet of the neutralization tank (29) is connected to the inlet of the aluminum hydroxide precipitation tank (39), the lower discharge port of the aluminum hydroxide precipitation tank (39) is connected to the inlet of the filter press 2 (38) through a pipeline 8 (40), and an aluminum hydroxide precipitation slurry pump (41) is arranged on the pipeline 8 (40); a clear liquid overflow port 3 (42) is arranged on the upper part of the aluminum hydroxide precipitation tank (39), and is connected to the liquid inlet (21) of the red mud slurry stirring tank (4) through a pipeline 9 (43); the discharge port of the filter press 2 (38) is connected to the liquid inlet (21) through a pipeline 10 (44).

4. The device for flue gas desulfurization and carbon fixation according to claim 3 is characterized in that: It also includes an aluminum hydroxide calciner (45) and an aluminum oxide storage tank (37); the solid material discharge port of the second filter press (38) is connected to the feed port of the aluminum hydroxide calciner (45), and the discharge port of the aluminum hydroxide calciner (45) is connected to the inlet of the aluminum oxide storage tank (37).

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