A tail gas recycling carbonization process system for alkali production

Abstract

This utility model discloses a tail gas recycling carbonization process system for alkali production, including an absorption tower. The tower's internal cavity is divided into two longitudinal absorption chambers by a partition. Each absorption chamber has a solution reaction tank at its lower part, and the bottoms of the two solution reaction tanks are connected. The two absorption chambers are a main absorption chamber and a secondary absorption chamber. The lower part of the main absorption chamber has an ammonia inlet and a carbon dioxide inlet, and the top of the main absorption chamber has a gas collecting port connected to the inlet of a circulation pipe. The outlet of the circulation pipe is connected to the two absorption chambers by two branch pipes, each branch pipe equipped with a regulating valve to adjust the opening according to the gas concentration inside the circulation pipe. The top of the secondary absorption chamber has a tail gas discharge port. This utility model can reduce the concentration of ammonia and carbon dioxide in the tail gas during the ammonia absorption carbonization process.

Description

Technical Field

[0001] This utility model relates to the field of industrial soda ash production technology, and in particular to a tail gas recycling carbonization process system for soda ash production. Background Technology

[0002] In the ammonia-soda process for alkali production, the carbonization process typically begins by introducing ammonia gas into brine to form ammonia brine, thereby increasing the brine's ability to absorb carbon dioxide and thus improving yield. This process is usually completed sequentially by an ammonia absorption tower and a carbonization tower. Since the ammonia gas is recovered from the mother liquor through ammonia stripping, the recovered ammonia gas contains carbon dioxide. Furthermore, the ammonia absorption process involves physical dissolution, which is relatively slow, resulting in incomplete absorption of the added carbon dioxide. Consequently, the tail gas from the ammonia absorption tower contains both ammonia and carbon dioxide. To ensure the absorption efficiency of the carbonization tower, the ammonia concentration in the input ammonia brine must meet certain standards, which may explain the higher concentrations of ammonia and carbon dioxide in the tail gas from the ammonia absorption tower. Summary of the Invention

[0003] Purpose of the invention: In order to overcome the shortcomings of the existing technology, this utility model provides a tail gas recycling carbonization process system for alkali production, which can reduce the concentration of ammonia and carbon dioxide in the tail gas during the carbonization process.

[0004] Technical solution: To achieve the above objectives, the present invention provides a tail gas recycling carbonization process system for alkali production, including an absorption tower, the inner cavity of which is divided by a partition to form two longitudinal absorption chambers, and a solution reaction tank is formed at the bottom of each of the two absorption chambers, and the bottoms of the two solution reaction tanks are connected.

[0005] The two absorption chambers are a main absorption chamber and a secondary absorption chamber. The lower part of the main absorption chamber is provided with an ammonia inlet and a carbon dioxide inlet. The top of the main absorption chamber is provided with a gas collection port, which is connected to the inlet end of the circulation pipe. The outlet end of the circulation pipe is connected to the two absorption chambers by two branch pipes respectively. Both branch pipes are provided with regulating valves, which can adjust the opening degree according to the gas concentration inside the circulation pipe. The top of the secondary absorption chamber is provided with a tail gas discharge port.

[0006] Furthermore, the ammonia inlet is located above the liquid surface in the solution reaction tank, and a spraying mechanism is provided above the ammonia inlet. The spraying mechanism is connected to the brine supply system and can form ammonia brine in the solution reaction tank; the carbon dioxide inlet is located at the bottom of the solution reaction tank.

[0007] Furthermore, the spraying mechanism employs atomizing nozzles, which can form an atomizing spraying zone covering the longitudinal section of the main absorption chamber; several spraying mechanisms are arranged longitudinally above the ammonia inlet.

[0008] Furthermore, an ammonia salt water layer is formed in the lower layer of the solution reaction tank within the secondary absorption chamber, and the outlet end of the circulation pipe is connected to the ammonia salt water layer.

[0009] Furthermore, the spraying mechanism is also provided on the upper part of the secondary absorption chamber.

[0010] Furthermore, the lower structure of the separator is formed with an inclined connecting channel for connecting the upper layer of the solution reaction tank in the main absorption chamber with the lower layer of the solution reaction tank in the secondary absorption chamber.

[0011] Furthermore, the carbon dioxide inlet is located below the high-level port of the connecting channel.

[0012] Furthermore, the outlet end of the circulation pipe is positioned opposite to the lower port of the connecting channel.

[0013] Beneficial effects: The tail gas recycling carbonization process system of this utility model can fully absorb ammonia and carbon dioxide in the tail gas through the recycling absorption of the main absorption chamber and the re-absorption of the secondary absorption chamber, and ensure the stability of the pressure in the absorption tower during the recycling absorption process. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of one embodiment of the exhaust gas recirculation carbonization process system of this utility model. Detailed Implementation

[0015] The present invention will be further described below with reference to the accompanying drawings.

[0016] As attached Figure 1 The tail gas recirculation carbonization process system for alkali production includes an absorption tower 1, the inner cavity of which is divided into two longitudinal absorption chambers by a partition 2. A solution reaction tank is formed at the bottom of each of the two absorption chambers, and the bottoms of the two solution reaction tanks are connected. The bottom connection of the two solution reaction tanks forms a bucket-shaped structure, the bottom of which is a liquid outlet for connecting to a precipitation and filtration device. A suction pump is provided at the liquid outlet to control the liquid level in the two solution reaction tanks.

[0017] The two absorption chambers are a main absorption chamber 21 and a secondary absorption chamber 22. The lower part of the main absorption chamber 21 has an ammonia inlet 5 and a carbon dioxide inlet 6, and the top of the main absorption chamber 21 has a gas collecting port 7, which is connected to the inlet end of the circulation pipe 8. Preferably, the carbon dioxide inlet 6 is positioned lower than the ammonia inlet 5, so that the ammonia first contacts and dissolves in the brine to form ammonia-salt water, and then the carbon dioxide contacts the ammonia-salt water, improving the carbon dioxide absorption efficiency. The main ammonia absorption and carbonization process is completed in the main absorption chamber 21, and the exhaust gas containing unabsorbed ammonia and carbon dioxide is collected by the gas collecting port 7 and input into the circulation pipe 8.

[0018] The outlet of the circulation pipe 8 is connected to the two absorption chambers by two branch pipes, each equipped with a regulating valve to adjust its opening according to the gas concentration inside the circulation pipe 8. A tail gas discharge port 9 is located at the top of the secondary absorption chamber 22. The main pipe of the circulation pipe 8 is equipped with a concentration detection device to control the gas flow by detecting the concentrations of ammonia and carbon dioxide. When the concentrations of ammonia and carbon dioxide in the tail gas are high, the flow rate into the main absorption chamber 21 is increased, while a small portion of the tail gas is allowed to flow into the secondary absorption chamber 22. The secondary absorption chamber 22 has a certain capacity for absorbing ammonia and carbon dioxide. However, when the concentrations of ammonia and carbon dioxide in the tail gas exceed this capacity, the excess is returned to the main absorption chamber 21 for recirculation, while the manageable portion is absorbed by the secondary absorption chamber 22 before being discharged. This effectively reduces the concentrations of ammonia and carbon dioxide in the tail gas. Considering that when the amount of exhaust gas circulating back to the main absorption chamber 21 increases, the pressure in the upper gas zone of the main absorption chamber will rise. The two absorption chambers are connected at the bottom to form a U-shaped cavity structure, and the connecting port is submerged in the solution reaction tank. Since the upper gas zone in the secondary absorption chamber 22 is emptied, its pressure is close to atmospheric pressure. When the gas pressure in the main absorption chamber rises, the instantaneous pressure change can be alleviated by raising the liquid level on the side of the secondary absorption chamber 22 to ensure the safety of the reaction process. The processing pressure of the main absorption chamber 21 can be temporarily relieved by reducing the flow rate of ammonia inlet 5 and carbon dioxide inlet 6. When the concentration of ammonia and carbon dioxide in the circulation pipe 8 drops to the preset range, the amount of exhaust gas flowing into the secondary absorption chamber 22 is increased, and the flow rates of ammonia inlet 5 and carbon dioxide inlet 6 are restored to the preset flow rates. This can effectively cope with the fluctuations in the absorption efficiency of ammonia and carbon dioxide by brine, ensuring that there is almost no ammonia and carbon dioxide in the final exhaust gas.

[0019] The ammonia inlet 5 is located above the liquid surface in the solution reaction tank. A spray mechanism 3 is provided above the ammonia inlet 5. The spray mechanism 3 is connected to the brine supply system 4 and can form ammonia brine in the solution reaction tank. The carbon dioxide inlet 6 is located at the bottom of the solution reaction tank. The spray mechanism forms a longitudinal brine spray zone above the liquid surface in the solution reaction tank. As ammonia gas rises and passes through the spray zone, it cools down and comes into full contact with the brine droplets, increasing the contact time between the ammonia gas and the brine. This allows the ammonia gas to fully dissolve in the brine and eventually fall into the solution tank to form ammonia brine. Due to the suction effect at the bottom of the tank, the ammonia brine tends to move downwards. Carbon dioxide is directly introduced into the ammonia brine and, as it rises along the water body, it forms convection with the ammonia brine and is thus fully absorbed. When the residual gas breaks through the liquid surface, it forms a splash zone above the liquid surface, carrying the ammonia brine with a lower ammonia concentration upwards to form droplets. These droplets come into contact with the introduced ammonia gas, further dissolving some of the ammonia gas before falling back down. This ensures that the ammonia brine in contact with carbon dioxide has a higher concentration, thereby improving the absorption capacity of carbon dioxide.

[0020] Preferably, the spraying mechanism 3 employs an atomizing nozzle, capable of forming an atomized spraying zone covering the longitudinal section of the main absorption chamber 21; several spraying mechanisms 3 are arranged longitudinally above the ammonia inlet 5. This further increases the contact area between ammonia and brine, enhancing the dissolution rate.

[0021] An ammonia-salt water layer is formed in the lower layer of the solution reaction tank within the secondary absorption chamber 22, and the outlet of the circulation pipe 8 is connected to this ammonia-salt water layer. A spray mechanism 3 is also installed at the upper part of the secondary absorption chamber 22. This mechanism forms a liquid layer with a low ammonia concentration on the surface of the ammonia-salt water layer. The exhaust gas entering the secondary absorption chamber 22 is first introduced into the ammonia-salt water layer to fully absorb residual carbon dioxide. Due to the high ammonia concentration, the absorption of residual ammonia is limited, so the exhaust gas continues to rise, passing sequentially through the liquid layer with a low ammonia concentration and the upper brine spray zone, further absorbing residual ammonia and ensuring that the final exhaust gas contains almost no ammonia or carbon dioxide. Only one set of spray mechanisms is needed within the secondary absorption chamber.

[0022] The lower part of the separator 2 is formed with an inclined connecting channel 20, which connects the upper layer of the solution reaction tank in the main absorption chamber 21 with the lower layer of the solution reaction tank in the secondary absorption chamber 22. This allows a portion of the ammonia brine with a certain ammonia concentration in the upper layer of the main absorption chamber 21 to flow into the lower layer of the secondary absorption chamber, forming an ammonia brine layer. This ensures sufficient absorption of carbon dioxide in the exhaust gas while avoiding waste of the ammonia brine.

[0023] The carbon dioxide inlet 6 is located below the high-level port of the connecting channel 20. This ensures that the introduced carbon dioxide rises along the main absorption chamber, preventing carbon dioxide from directly entering the secondary absorption chamber and being emitted.

[0024] The outlet of the circulation pipe 8 is positioned opposite to the lower port of the connecting channel 20. This ensures that the exhaust gas entering the secondary absorption chamber mixes directly with the newly flowing ammonia brine to achieve the best absorption effect.

[0025] The above are merely preferred embodiments of this utility model. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of this utility model, and these improvements and modifications should also be considered within the protection scope of this utility model.

Claims

1. A tail gas recycling carbonization process system for alkali production, characterized in that: The absorption tower (1) is divided into two longitudinal absorption chambers by a partition (2). A solution reaction pool is formed at the bottom of each absorption chamber, and the bottoms of the two solution reaction pools are connected. The two absorption chambers are a main absorption chamber (21) and a secondary absorption chamber (22). The lower part of the main absorption chamber (21) is provided with an ammonia inlet (5) and a carbon dioxide inlet (6). The top of the main absorption chamber (21) is provided with a gas collection port (7). The gas collection port (7) is connected to the inlet end of the circulation pipe (8). The outlet end of the circulation pipe (8) is connected to the two absorption chambers by two branch pipes respectively. Both branch pipes are provided with regulating valves, which can adjust the opening degree according to the gas concentration inside the circulation pipe (8). The top of the secondary absorption chamber (22) is provided with a tail gas discharge port (9).

2. The tail gas recycling carbonization process system for alkali production according to claim 1, characterized in that: The ammonia inlet (5) is located above the liquid surface of the solution reaction tank. A spraying mechanism (3) is provided above the ammonia inlet (5). The spraying mechanism (3) is connected to the brine supply system (4) and can form ammonia brine in the solution reaction tank. The carbon dioxide inlet (6) is located at the bottom of the solution reaction tank.

3. The tail gas recirculation carbonization process system for alkali production according to claim 2, characterized in that: The spraying mechanism (3) uses an atomizing nozzle, which can form an atomizing spraying zone covering the longitudinal section of the main absorption chamber (21); several spraying mechanisms (3) are arranged longitudinally above the ammonia inlet (5).

4. The tail gas recirculation carbonization process system for alkali production according to claim 3, characterized in that: An ammonia salt water layer is formed in the lower layer of the solution reaction tank in the secondary absorption chamber (22), and the outlet end of the circulation pipe (8) is connected to the ammonia salt water layer.

5. The tail gas recirculation carbonization process system for alkali production according to claim 4, characterized in that: The spraying mechanism (3) is also provided on the upper part of the secondary absorption chamber (22).

6. The tail gas recirculation carbonization process system for alkali production according to claim 5, characterized in that: The lower part of the separator (2) is formed with an inclined connecting channel (20) for connecting the upper layer of the solution reaction pool in the main absorption chamber (21) with the lower layer of the solution reaction pool in the secondary absorption chamber (22).

7. The tail gas recirculation carbonization process system for alkali production according to claim 6, characterized in that: The carbon dioxide inlet (6) is located below the high port of the connecting channel (20).

8. The tail gas recirculation carbonization process system for alkali production according to claim 7, characterized in that: The outlet end of the circulation pipe (8) is positioned opposite to the low-position port of the connecting channel (20).

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