Two-stage absorption system for urotropine production
By designing a two-stage absorption system, the problems of low formaldehyde absorption efficiency and exhaust gas pollution in the production of urotropine are solved, achieving efficient and environmentally friendly formaldehyde absorption and resource utilization.
Patent Information
- Application Number
- CN202522698383.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-19
- Publication Date
- 2026-01-27
- Estimated Expiration
- 2035-12-19
AI Technical Summary
Traditional single-stage absorption devices have low formaldehyde absorption efficiency in urotropine production, resulting in excessive formaldehyde levels in exhaust gas, low resource utilization, and environmental pollution problems.
A two-stage absorption system is adopted, including a spray absorption tower and an adsorption tower. Through the design of liquid distributors, gas distributors, screens and heat exchange jackets, combined with process parameter control, efficient formaldehyde absorption and deep purification of exhaust gas are achieved.
It increases the formaldehyde absorption rate to 99.99%, reduces the formaldehyde concentration in exhaust gas, improves raw material utilization, reduces energy consumption, and achieves environmentally friendly production.
Smart Images
Figure CN223832335U_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of heterocyclic compound technology, specifically relating to a two-stage absorption system for the production of hexamethylenetetramine. Background Technology
[0002] Urotropine, scientifically known as hexamethylenetetramine, is produced by the reaction of formaldehyde and ammonia under high-temperature alkaline conditions. However, the incompletely reacted formaldehyde gas needs to be recovered through an absorption process. Traditional single-stage absorption suffers from low efficiency, a yield of less than 85%, and excessive formaldehyde content in the exhaust gas.
[0003] Currently, most commonly used single absorption devices absorb ammonia and formaldehyde separately. However, the absorbed ammonia and formaldehyde cannot be effectively utilized, which easily leads to resource waste. Existing ammonia and formaldehyde absorption towers also suffer from low absorption efficiency. Ammonia and formaldehyde are discharged from the exhaust port with the exhaust gas, causing environmental pollution. Therefore, there is an urgent need for a device that can absorb ammonia and formaldehyde and then reuse them. Utility Model Content
[0004] In view of the shortcomings of the prior art, the technical problem to be solved by this utility model is to provide a two-stage absorption system for the production of hexamethylenetetramine, in which the synergistic use of dual towers improves the formaldehyde absorption efficiency, significantly reduces exhaust emissions and improves the utilization rate of raw materials.
[0005] The technical solution adopted by this utility model to solve its technical problem is:
[0006] The two-stage absorption system for urotropine production described in this utility model includes a spray absorption tower, a liquid distributor installed on the upper inner side of the spray absorption tower, a gas distributor installed on the lower inner side of the spray absorption tower, a preheater connected to the lower part of the spray absorption tower, a formaldehyde pipe connected to the top of the preheater, several screens spaced apart inside the spray absorption tower, an adsorption tower connected to the top of the spray absorption tower via a vacuum pump, several redistributors spaced apart inside the adsorption tower, a tail gas tank connected to the top of the adsorption tower, a product tank installed at the bottom of the adsorption tower, and a first heat exchange jacket, a second heat exchange jacket, and a third heat exchange jacket arranged sequentially from top to bottom on the outer side of the adsorption tower.
[0007] The liquid distributor is connected to a mother liquor pipe on its side, and the bottom of the preheater is connected to a gas distributor.
[0008] The liquid distributor is generally disc-shaped, with a spider web-like partition plate surrounding the bottom of the liquid distributor. Through holes are provided at the joints of the spider web-like partition plate, and the mother liquor pipe is connected to the middle of the top surface of the liquid distributor.
[0009] The spray absorption tower is equipped with a jacket on the outside, and the lower part of the jacket is connected to the upper part of the preheater.
[0010] The screen is positioned between the liquid distributor and the gas distributor.
[0011] The top of the spray absorption tower is connected to the bottom of the adsorption tower, and the bottom of the spray absorption tower is connected to the redistributor in sequence.
[0012] A material pump is installed between the bottom of the spray absorption tower and the redistributor, and a material pump is installed between the adsorption tower and the product tank.
[0013] A level gauge is installed on the lower inner side of the spray absorption tower, and the level gauge is located below the gas distributor.
[0014] The bottom of each of the redistributors is provided with an adsorption layer, and the first heat exchange sleeve, the second heat exchange sleeve and the third heat exchange sleeve are arranged from top to bottom on the outside of the adsorption layer at the bottom of the redistributor.
[0015] A diffuser is installed at the bottom of the exhaust gas tank.
[0016] The beneficial effects of this utility model are:
[0017] This invention overcomes technical bottlenecks through a two-stage absorption structure design, combined with optimized packing and controlled process parameters. The use of two towers in series solves the problems of low formaldehyde absorption efficiency and high exhaust pollution in urotropine production, achieving both high efficiency and environmental friendliness.
[0018] Both the spray absorption tower and the adsorption tower have internal structures that can slow down the contact time between formaldehyde and the absorbent liquid, making it easier to increase the formaldehyde absorption rate. At the same time, the spray absorption tower can quickly capture most of the formaldehyde, while the adsorption tower can achieve deep removal of trace amounts of formaldehyde through surface adsorption. The vacuum pump at the top of the spray absorption tower can ensure that the pressure inside the tower remains stable and negative, which is conducive to the reaction and absorption of ammonia and formaldehyde, thus improving the reaction efficiency. The waste heat inside the jacket can be used to preheat the formaldehyde in the preheater, reducing the heating energy consumption of the preheater. Adding alkaline solution to the tail gas tank and introducing the absorbed tail gas from the bottom of the tail gas tank can prevent formaldehyde from overflowing and improve emission efficiency.
[0019] This invention increases the formaldehyde absorption rate to over 99.99%, far exceeding the efficiency of a single absorber, and significantly reduces the formaldehyde concentration in the exhaust gas. Furthermore, by adjusting process parameters during use, production efficiency can be further optimized. Attached Figure Description
[0020] Figure 1 This is a schematic diagram of the structure of this utility model;
[0021] Figure 2 This is a schematic diagram of the liquid distributor structure of this utility model;
[0022] Figure 3 This is a schematic diagram of the screen structure of this utility model;
[0023] In the diagram: 1. Spray absorption tower; 2. Adsorption tower; 3. Tail gas tank; 4. Product tank; 5. Preheater; 6. Liquid distributor; 7. Gas distributor; 8. Screen; 9. Redistributor; 10. Mother liquor pipeline; 11. Formaldehyde pipeline; 12. Disperser; 13. Level gauge; 14. Vacuum pump; 101. Jacket; 901. First heat exchange jacket; 902. Second heat exchange jacket; 903. Third heat exchange jacket. Detailed Implementation
[0024] The embodiments of this utility model will be further described below with reference to the accompanying drawings.
[0025] Example 1
[0026] like Figure 1-3 As shown, the two-stage absorption system for urotropine production of this utility model includes a spray absorption tower 1, a liquid distributor 6 installed on the upper inner side of the spray absorption tower 1, a gas distributor 7 installed on the lower inner side of the spray absorption tower 1, a preheater 5 connected to the lower part of the spray absorption tower 1, a formaldehyde pipe 11 connected to the top of the preheater 5, several screens 8 spaced apart inside the spray absorption tower 1, an adsorption tower 2 connected to the top of the spray absorption tower 1 via a vacuum pump 14, several redistributors 9 spaced apart inside the adsorption tower 2, a tail gas tank 3 connected to the top of the adsorption tower 2, a product tank 4 installed at the bottom of the adsorption tower 2, and a first heat exchange jacket 901, a second heat exchange jacket 902, and a third heat exchange jacket 903 arranged sequentially from top to bottom on the outer side of the adsorption tower 2.
[0027] The liquid distributor 6 is connected to the mother liquor pipe 10 on its side, and the bottom of the preheater 5 is connected to the gas distributor 7.
[0028] The liquid distributor 6 is generally disc-shaped. A spider web-like partition plate is arranged around the bottom of the liquid distributor 6. Through holes are provided at the joints of the spider web-like partition plate. The mother liquor pipe 10 is connected to the middle of the top surface of the liquid distributor 6.
[0029] A jacket 101 is provided on the outside of the spray absorption tower 1, and the lower part of the jacket 101 is connected to the upper part of the preheater 5.
[0030] The screen 8 is positioned between the liquid distributor 6 and the gas distributor 7.
[0031] The top of the spray absorption tower 1 is connected to the bottom of the adsorption tower 2, and the bottom of the spray absorption tower 1 is connected to the redistributor 9 in sequence.
[0032] A material pump is installed between the bottom of the spray absorption tower 1 and the redistributor 9, and a material pump is installed between the adsorption tower 2 and the product tank 4.
[0033] A level gauge 13 is installed on the lower inner side of the spray absorption tower 1, and the level gauge 13 is located below the gas distributor 7.
[0034] An adsorption layer is provided at the bottom of several redistributors 9. The first heat exchange jacket 901, the second heat exchange jacket 902 and the third heat exchange jacket 903 are arranged from top to bottom on the outside of the adsorption layer at the bottom of the redistributor 9.
[0035] A diffuser 12 is installed at the lower part of the exhaust gas tank 3.
[0036] Working principle and process:
[0037] During the reaction, a mother liquor containing excess ammonia is used as the spray liquid, transported from the mother liquor pipeline 10 to the liquid distributor 6 and distributed into uniform droplets before entering the spray absorption tower 1. Formaldehyde is sent through the formaldehyde pipeline 11 to the preheater 5 for preheating and then to the gas distributor 7. The gas diffuses into the spray absorption tower 1 and contacts the spray liquid from bottom to top, with a liquid-to-gas ratio of 3:1. Simultaneously, hot water is added to the jacket 101 to adjust the temperature inside the spray absorption tower 1 to 70°C. Due to the several screens 8 spaced apart inside the spray absorption tower 1, the falling speed of the spray liquid is slowed down, increasing the contact area and contact time between formaldehyde and the spray liquid. Finally, a hexamethylenetetramine precursor is obtained at the bottom of the spray absorption tower 1. The hot water in the jacket 101 is transported to the preheater 5 to preheat the formaldehyde gas, and the hexamethylenetetramine precursor is transported to the adsorption tower 2 for further processing. Formaldehyde gas is absorbed and reacted. The adsorption tower 2 has three adsorption layers, and the hexamethylenetetramine precursor is fed in stages through three redistributors 9. The temperature of each adsorption layer is controlled separately, from bottom to top: 60℃, 65℃, and 75℃. The adsorption layers and redistributors 9 work together to improve the formaldehyde absorption rate. The remaining exhaust gas is sent to the exhaust gas tank 3, where an alkaline solution is added. The exhaust gas and alkaline solution are mixed through a disperser 12 to improve the exhaust gas purification efficiency. The total formaldehyde absorption rate is detected to be greater than 99.9%. The prepared hexamethylenetetramine is sent to the product tank 4 for storage, and the purity of the hexamethylenetetramine product is greater than 99.5%. When using this invention, the formaldehyde consumption per unit of raw material is reduced by 12% compared to traditional single-stage absorbers, significantly reducing raw material utilization, lowering energy consumption, and improving production efficiency.
[0038]
Claims
1. A two-stage absorption system for the production of urotropine, comprising a spray absorption tower (1), characterized in that, A liquid distributor (6) is installed on the upper inner side of the spray absorption tower (1), a gas distributor (7) is installed on the lower inner side of the spray absorption tower (1), a preheater (5) is connected to the lower part of the spray absorption tower (1), a formaldehyde pipe (11) is connected to the top of the preheater (5), a number of screens (8) are arranged at intervals inside the spray absorption tower (1), an adsorption tower (2) is connected to the top of the spray absorption tower (1) through a vacuum pump (14), a number of redistributors (9) are arranged at intervals inside the adsorption tower (2), a tail gas tank (3) is connected to the top of the adsorption tower (2), a product tank (4) is installed at the bottom of the adsorption tower (2), and a first heat exchange jacket (901), a second heat exchange jacket (902) and a third heat exchange jacket (903) are arranged sequentially from top to bottom on the outside of the adsorption tower (2).
2. The two-stage absorption system for hexamethylenetetramine production according to claim 1, characterized in that, The liquid distributor (6) is connected to the mother liquid pipe (10) on the side, and the bottom of the preheater (5) is connected to the gas distributor (7).
3. The two-stage absorption system for hexamethylenetetramine production according to claim 2, characterized in that, The liquid distributor (6) is generally disc-shaped. A spider web-like partition plate is arranged around the bottom of the liquid distributor (6). Through holes are provided at the connection points of the spider web-like partition plate. The mother liquor pipe (10) is connected to the middle of the top surface of the liquid distributor (6).
4. The two-stage absorption system for hexamethylenetetramine production according to claim 1, characterized in that, A jacket (101) is provided on the outside of the spray absorption tower (1), and the lower part of the jacket (101) is connected to the upper part of the preheater (5).
5. The two-stage absorption system for hexamethylenetetramine production according to claim 1, characterized in that, The screen (8) is positioned between the liquid distributor (6) and the gas distributor (7).
6. The two-stage absorption system for hexamethylenetetramine production according to claim 1, characterized in that, The top of the spray absorption tower (1) is connected to the bottom of the adsorption tower (2), and the bottom of the spray absorption tower (1) is connected to the redistributor (9) in sequence.
7. The two-stage absorption system for hexamethylenetetramine production according to claim 6, characterized in that, A material pump is installed between the bottom of the spray absorption tower (1) and the redistributor (9), and a material pump is installed between the adsorption tower (2) and the product tank (4).
8. The two-stage absorption system for hexamethylenetetramine production according to claim 1, characterized in that, A level gauge (13) is installed on the lower inner side of the spray absorption tower (1), and the level gauge (13) is located below the gas distributor (7).
9. The two-stage absorption system for hexamethylenetetramine production according to claim 1, characterized in that, Several redistributors (9) are provided with an adsorption layer at the bottom. The first heat exchange jacket (901), the second heat exchange jacket (902) and the third heat exchange jacket (903) are arranged from top to bottom on the outside of the adsorption layer at the bottom of the redistributor (9).
10. The two-stage absorption system for hexamethylenetetramine production according to claim 1, characterized in that, A diffuser (12) is installed at the bottom of the exhaust gas tank (3).