Dimethylamine water absorption system

Abstract

The utility model belongs to tertiary amine production tail gas absorption technical field, concretely relates to a dimethylamine water absorption system. Dimethylamine water absorption system, including primary absorption tower, secondary absorption tower and gas -liquid separator, primary absorption tower upper portion feed inlet and fresh water pipeline connection, primary absorption tower lower part air inlet and tail gas pipeline connection, primary absorption tower top and secondary absorption tower lower part are connected, and primary absorption tower bottom is connected with secondary absorption tower upper portion feed inlet through circulating pump, and circulating pump export still is provided with the pipeline that is connected with gas -liquid separator, and gas -liquid separator is connected with amine water temporary storage jar, and the top of gas -liquid separator is provided with the pipeline that is connected with amination reactor. Dimethylamine water absorption system of the utility model, through strengthening gas -liquid contact efficiency, optimization absorption liquid circulation path, has realized the efficient, stable absorption of residual dimethylamine, and simultaneously, recycling dimethylamine can be recycled, and the cost of raw materials in tertiary amine production is reduced.

Description

Technical Field

[0001] This utility model belongs to the field of tail gas absorption technology in tertiary amine production, and specifically relates to a dimethylamine water absorption system. Background Technology

[0002] Currently, the mainstream method for producing tertiary amines is the one-step alcohol process. This process involves the dehydration of fatty alcohols and dimethylamine under specific conditions of catalyst, temperature, and hydrogen pressure to produce tertiary amines. During the production process, in order to promote the reaction equilibrium and improve the conversion rate of tertiary amines, an excess of dimethylamine is usually introduced as a reactant. At the same time, water is generated during the reaction, which needs to be removed in time to ensure reaction efficiency.

[0003] To separate water from the system, a three-stage condensation process is commonly used in industrial production: a three-stage condenser gradually lowers the temperature, separating the oil phase (such as tertiary amines) from the water phase (such as water vapor). Simultaneously, the solubility of dimethylamine in water allows for the formation of an aqueous dimethylamine solution, enabling the recovery of some dimethylamine. However, due to limitations in condensation temperature, pressure, and the complexity of the gas phase components, some dimethylamine remains uncaptured after three-stage condensation. Direct discharge of this residual dimethylamine not only wastes raw materials but also causes pollution problems due to its malodorous properties.

[0004] In the existing technology, although absorption processes such as multi-stage water washing and acid washing in series have been developed for the treatment of residual dimethylamine after condensation, traditional water washing devices have obvious defects: on the one hand, the gas-liquid contact in single-stage water washing is insufficient, which easily leads to problems such as uneven liquid distribution and wall flow, resulting in limited dimethylamine absorption efficiency; on the other hand, dimethylamine in the absorption liquid is easy to escape from the water, and the discharge of amine-containing wastewater is large, increasing the pressure of subsequent treatment. Utility Model Content

[0005] To address the problem of insufficient water washing in existing technologies, this invention provides a dimethylamine water absorption system. By enhancing gas-liquid contact efficiency and optimizing the absorption liquid circulation path, it achieves efficient and stable absorption of residual dimethylamine. At the same time, the recovered dimethylamine can be recycled, reducing the cost of raw materials in tertiary amine production.

[0006] A dimethylamine water absorption system includes a primary absorption tower, a secondary absorption tower, and a gas-liquid separator. The upper inlet of the primary absorption tower is connected to a fresh water pipeline, the lower inlet of the primary absorption tower is connected to a tail gas pipeline, the top of the primary absorption tower is connected to the lower part of the secondary absorption tower, and the bottom of the primary absorption tower is connected to the upper inlet of the secondary absorption tower via a circulating pump. The outlet of the circulating pump is also provided with a pipeline connected to the gas-liquid separator, the gas-liquid separator is connected to an amine water temporary storage tank, and the top of the gas-liquid separator is provided with a pipeline connected to an amination reactor.

[0007] Preferably, the feed inlets at the top of both the primary and secondary absorption towers are internal pipe-type distributors. The pipe distributor consists of a main pipe, branch pipes, and nozzles. The branch pipes are vertically welded to the main pipe and arranged in parallel. The length of the branch pipes is evenly distributed according to the tower diameter, and nozzles are evenly installed on the branch pipes. The pipe distributor is fixed to the inner wall of the tower by a bracket. One end of the main pipe is connected to the feed inlet, and the other end is closed.

[0008] Preferably, the upper part of the primary absorption tower and the secondary absorption tower are absorption zones, and the lower part is a temporary storage zone. The upper absorption zone of the primary absorption tower is equipped with double-layer packing, and the upper absorption zone of the secondary absorption tower is equipped with single-layer packing. The lower temporary storage zone of the primary absorption tower is equipped with baffles to disperse the tail gas entering the primary absorption tower and the amine water falling from the absorption zone.

[0009] Preferably, a dispersing disc is provided in the middle of the double-layer packing, and a return pipeline is also provided at the outlet of the circulating pump to connect with the dispersing disc. Liquid distribution holes are evenly distributed on the dispersing disc.

[0010] Preferably, the fresh water pipeline is also equipped with a branch line connected to the upper feed inlet of the secondary absorption tower.

[0011] Preferably, the upper part of the gas-liquid separator is also connected to the amine water pipeline from the three-stage condensation unit, and the top of the amine water temporary storage tank is also provided with a pipeline connected to the lower air inlet of the first-stage absorption tower.

[0012] Preferably, the bottom of the secondary absorption tower is connected to the gas-liquid separator via a transfer pump. A drying device is installed on the pipeline connecting the gas-liquid separator and the amination reactor. The drying device contains parallel dryers filled with molecular sieves, with one dryer in operation and one in standby mode.

[0013] Preferably, the top of the primary and secondary absorption towers is also equipped with wire mesh demisters to capture dimethylamine droplets entrained in the gas phase.

[0014] Preferably, the top of the secondary absorption tower is connected to a gas phase pipeline, and a back pressure valve is installed on the gas phase pipeline.

[0015] Preferably, the amine water storage tank is also equipped with a reflux pipeline connected to the upper feed inlet of the primary absorption tower, and the reflux pipeline is also equipped with an external delivery branch.

[0016] In the dimethylamine water absorption system, both the gas-liquid separator and the amination reactor are jacketed structures.

[0017] Compared with the prior art, the beneficial effects of this utility model are as follows: This invention improves dimethylamine absorption efficiency by connecting a primary absorption tower and a secondary absorption tower in series, combined with a tubular distributor for uniform liquid distribution. The primary tower's double-layer packing and baffles enhance gas-liquid contact, and the combination of circulation reflux and a dispersion plate further enhances the absorption efficiency. Simultaneously, a portion of the absorbent from the primary absorption tower serves as supplementary liquid for the secondary absorption tower, reducing the amount of fresh water used and increasing the concentration of amine solution, which can be used as a byproduct. Finally, a gas-liquid separator integrates the tertiary condensate amine solution and the rich absorbent liquid, achieving centralized recovery. Combined with a molecular sieve drying device, this ensures the purity of the recycled dimethylamine and reduces the impact of water in the recycled dimethylamine on the amination reaction. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the dimethylamine water absorption system of this utility model; Figure 2 This is a schematic diagram of the structure of the tubular distributor in this utility model.

[0019] In the diagram: 1. Primary absorption tower; 101. Tubular distributor; 1011. Main pipe; 1012. Branch pipe; 1013. Nozzle; 1014. Support; 102. Dispersion plate; 103. Baffle plate; 104. Packing; 2. Secondary absorption tower; 3. Gas-liquid separator; 4. Amine water storage tank; 5. Drying device; 6. Amination reactor; 7. Fresh water pipeline; 8. Tail gas pipeline; 9. Circulation pump; 10. Amine water pipeline; 11. Gas phase pipeline; 12. Back pressure valve; 13. Wire mesh demister; 14. Transfer pump. Detailed Implementation

[0020] The technical solution of the utility model will be further described below with reference to the accompanying drawings.

[0021] like Figures 1-2 As shown, the dimethylamine water absorption system of this utility model includes a primary absorption tower 1, a secondary absorption tower 2, and a gas-liquid separator 3. The upper inlet of the primary absorption tower 1 is connected to a fresh water pipeline 7, the lower inlet of the primary absorption tower 1 is connected to a tail gas pipeline 8, the top of the primary absorption tower 1 is connected to the lower part of the secondary absorption tower 2, and the bottom of the primary absorption tower 1 is connected to the upper inlet of the secondary absorption tower 2 via a circulating pump 9. The outlet of the circulating pump 9 is also provided with a pipeline connected to the gas-liquid separator 3. The gas-liquid separator 3 is connected to an amine water temporary storage tank 4, and the top of the gas-liquid separator 3 is provided with a pipeline connected to an amination reactor 6.

[0022] Both the primary absorption tower 1 and the secondary absorption tower 2 have internal pipe-type distributors 101 at their upper feed inlets. The pipe distributor 101 consists of a main pipe 1011, branch pipes 1012, and nozzles 1013. The branch pipes 1012 are vertically welded to the main pipe 1011 and arranged in parallel. The length of the branch pipes 1012 is evenly distributed according to the tower diameter. The nozzles 1013 are evenly installed on the branch pipes 1012. The pipe distributor 101 is fixed to the inner wall of the tower by a bracket 1014. One end of the main pipe 1011 is connected to the feed inlet, and the other end is closed.

[0023] The upper part of the primary absorption tower 1 and the secondary absorption tower 2 are absorption zones, and the lower part is a temporary storage zone. The upper absorption zone of the primary absorption tower 1 is equipped with double-layer packing 104, and the upper absorption zone of the secondary absorption tower 2 is equipped with single-layer packing 104. The lower temporary storage zone of the primary absorption tower 1 is equipped with baffles 103. A dispersion plate 102 is provided in the middle of the double-layer packing 104. The outlet of the circulating pump 9 is also equipped with a return pipeline connected to the dispersion plate 102. Liquid distribution holes are evenly distributed on the dispersion plate 102.

[0024] The fresh water pipeline 7 is also equipped with a branch line that connects to the upper feed inlet of the secondary absorption tower 2.

[0025] The upper part of the gas-liquid separator 3 is also connected to the amine water pipeline 10 from the three-stage condensation unit, and the top of the amine water temporary storage tank 4 is also provided with a pipeline connected to the lower air inlet of the first-stage absorption tower 1.

[0026] The top of the primary absorption tower 1 and the secondary absorption tower 2 are also equipped with wire mesh demisters 13; the top of the secondary absorption tower 2 is connected to the gas phase pipeline 11, and the gas phase pipeline 11 is equipped with a back pressure valve 12; the bottom of the secondary absorption tower 2 is connected to the gas-liquid separator 3 through a transfer pump 14, and a drying device 5 is installed on the pipeline connecting the gas-liquid separator 3 and the amination reactor 6. The drying device 5 is equipped with parallel dryers, which are filled with molecular sieves, one in operation and one on standby.

[0027] The amine water storage tank 4 is also equipped with a reflux pipeline connected to the upper feed inlet of the primary absorption tower 1, and the reflux pipeline is also equipped with an external delivery branch.

[0028] The above-mentioned dimethylamine water absorption system operates as follows: The tail gas containing dimethylamine enters the lower part of the primary absorption tower 1 through the tail gas pipeline 8. Simultaneously, the fresh water pipeline 7 delivers the absorbent liquid to the upper feed inlet of the primary absorption tower 1. After being evenly distributed by the tubular distributor 101, it is sprayed down from the nozzle 1013. The tail gas and water are in full contact within the double-layer packing 104 in the upper absorption zone of the primary absorption tower 1, resulting in the absorption of a large amount of dimethylamine. The dispersion plate 102 in the middle of the double-layer packing 104 further optimizes the liquid distribution through the liquid distribution holes, improving absorption efficiency. The baffle plate 10 in the lower temporary storage zone of the primary absorption tower 1... 3. To mitigate liquid disturbance, during the tail gas absorption process in the primary absorption tower 1, the bottom circulation pump 9 circulates the absorbent liquid. Part of the absorbent liquid is transported by the circulation pump 9 to the upper part of the secondary absorption tower 2 to replace fresh water as the absorbent, while part is returned to the dispersion plate 102 for further circulation and absorption. At the same time, the concentration of the bottom amine solution is periodically detected. After reaching the process concentration, it is circulated by the circulation pump 9 to the gas-liquid separator 3 for temporary storage to prevent excessive amine solution from accumulating in the bottom temporary storage area of ​​the primary absorption tower 1, which could lead to the escape of dimethylamine.

[0029] The unabsorbed tail gas at the top of the primary absorption tower 1 is removed by the wire mesh demister 13 to remove entrained liquid droplets. Then, it enters the lower part of the secondary absorption tower 2. At the same time, a branch of the fresh water pipeline 7 supplies liquid to the upper feed inlet of the secondary absorption tower 2. After being distributed by the tubular distributor 101, the absorbent comes into contact with the tail gas again in the single-layer packing 104 in the upper absorption zone of the secondary absorption tower 2, completing the deep absorption. The gas treated by the wire mesh demister 13 is discharged from the gas phase pipeline 11. The back pressure valve 12 can stabilize the pressure inside the tower. The absorbent at the bottom of the secondary absorption tower 2 is sent to the gas-liquid separator 3 by the transfer pump 14. At the same time, the outlet pipeline of the circulating pump 9 and the amine water pipeline 10 from the tertiary condensation unit also introduce the material into the gas-liquid separator 3.

[0030] The gas-liquid separator 3 separates the introduced gas-liquid mixture. Simultaneously, by introducing insulated water through the jacket, dimethylamine gas in the amine solution is separated, and the liquid enters the amine solution storage tank 4 (equipped with a pressure detection device to monitor the pressure inside the tank). The top pipeline of the amine solution storage tank 4 sends the dimethylamine that escapes during the temporary storage stage back to the lower part of the primary absorption tower 1 for reprocessing. The separated dimethylamine gas enters the drying device 5, and after being dehydrated by the molecular sieve inside the dryer, it enters the amination reactor 6 through the pipeline to participate in the subsequent reaction. The amine solution in the amine solution storage tank 4 can be connected to the primary absorption tower 1 through the return pipeline to replace part of the fresh water and realize the recycling within the system. In addition, the amine solution in the amine solution storage tank 4 can also be transported to downstream devices as a by-product through the external pipeline.

Claims

1. A dimethylamine water absorption system, characterized in that, It includes a primary absorption tower (1), a secondary absorption tower (2) and a gas-liquid separator (3). The upper feed inlet of the primary absorption tower (1) is connected to a fresh water pipeline (7), the lower air inlet of the primary absorption tower (1) is connected to a tail gas pipeline (8), the top of the primary absorption tower (1) is connected to the lower part of the secondary absorption tower (2), and the bottom of the primary absorption tower (1) is connected to the upper feed inlet of the secondary absorption tower (2) through a circulating pump (9). The outlet of the circulating pump (9) is also provided with a pipeline connected to the gas-liquid separator (3). The gas-liquid separator (3) is connected to an amine water temporary storage tank (4), and the top of the gas-liquid separator (3) is provided with a pipeline connected to an amination reactor (6).

2. The dimethylamine water absorption system according to claim 1, characterized in that, Both the primary absorption tower (1) and the secondary absorption tower (2) have internal pipe-type distributors (101) at their upper feed inlets. The pipe-type distributor (101) consists of a main pipe (1011), branch pipes (1012) and nozzles (1013). The branch pipes (1012) are vertically welded to the main pipe (1011) and arranged in parallel. The length of the branch pipes (1012) is evenly distributed according to the tower diameter. The nozzles (1013) are evenly installed on the branch pipes (1012). The pipe-type distributor (101) is fixed to the inner wall of the tower by a bracket (1014). One end of the main pipe (1011) is connected to the feed inlet, and the other end is closed.

3. The dimethylamine water absorption system according to claim 1, characterized in that, The upper part of the primary absorption tower (1) and the secondary absorption tower (2) is the absorption zone and the lower part is the temporary storage zone. The upper absorption zone of the primary absorption tower (1) is equipped with double-layer packing (104), and the upper absorption zone of the secondary absorption tower (2) is equipped with single-layer packing (104).

4. The dimethylamine water absorption system according to claim 3, characterized in that, The lower temporary storage area of ​​the primary absorption tower (1) is equipped with baffles (103).

5. The dimethylamine water absorption system according to claim 3, characterized in that, The first-stage absorption tower (1) has a dispersion plate (102) in the middle of the double-layer packing (104). The outlet of the circulating pump (9) is also equipped with a return pipeline connected to the dispersion plate (102). The dispersion plate (102) has liquid distribution holes evenly distributed on it.

6. The dimethylamine water absorption system according to claim 1, characterized in that, The fresh water pipeline (7) is also equipped with a branch line that connects to the upper feed inlet of the secondary absorption tower (2).

7. The dimethylamine water absorption system according to claim 1, characterized in that, The upper part of the gas-liquid separator (3) is also connected to the amine water pipeline (10) from the third-stage condensation unit, and the top of the amine water storage tank (4) is also provided with a pipeline connected to the lower air inlet of the first-stage absorption tower (1).

8. The dimethylamine water absorption system according to claim 1, characterized in that, The bottom of the secondary absorption tower (2) is connected to the gas-liquid separator (3) via a transfer pump (14). A drying device (5) is installed on the pipeline connecting the gas-liquid separator (3) and the amination reactor (6). The drying device (5) contains parallel dryers filled with molecular sieves, one in operation and one on standby.

9. The dimethylamine water absorption system according to claim 1, characterized in that, The top of the primary absorption tower (1) and the secondary absorption tower (2) are also equipped with wire mesh demisters (13). The top of the secondary absorption tower (2) is connected to the gas phase pipeline (11), and a back pressure valve (12) is installed on the gas phase pipeline (11).

10. The dimethylamine water absorption system according to claim 1, characterized in that, The amine water storage tank (4) is also equipped with a reflux pipeline connected to the upper feed inlet of the primary absorption tower (1), and the reflux pipeline is also equipped with an external feed branch.

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