Nitric acid absorption system

Abstract

The utility model relates to the technical field of ammonium nitrate production, in particular to a nitric acid absorption system which comprises a first absorption tower and a second absorption tower, the lower part of the first absorption tower is provided with a first liquid inlet and a first gas inlet, the top end of the first absorption tower is provided with a first gas outlet, and the lower part of the second absorption tower is provided with a second liquid inlet and a second gas inlet. A second gas outlet is formed in the top end of the second absorption tower, the first absorption tower is connected to the second liquid inlet through a first liquid outlet formed in the bottom, the first gas outlet is connected to the second gas inlet, a first reboiler is arranged at the bottom of the first absorption tower, and a second reboiler is arranged at the bottom of the second absorption tower; the second gas outlet is connected to a heat source inlet of the first reboiler, and the heights of the first absorption tower and the second absorption tower are 25m-35m. Through cooperation of the first absorption tower and the second absorption tower, the height of the single absorption tower is reduced, and the energy-saving effect is achieved.

Description

Technical Field

[0001] The utility model relates to the technical field of ammonium nitrate production, in particular to a nitric acid absorption system. Background Art

[0002] In the process of nitric acid production, the absorption tower is one of the key process equipment. Its main function is to absorb nitrogen oxides (such as NO x ) with water or nitric acid and convert them into nitric acid. Its tower body is a stainless steel cylinder, and its internal structure includes packing type, bubble cap type, sieve plate, etc. Process water or nitric acid is added from the top of the tower, and nitrogen oxide gas enters from the bottom of the tower. The two flow countercurrently in the tower for mass transfer and heat transfer processes, and the generated nitric acid is discharged from the bottom of the tower.

[0003] In traditional processes, the height of the nitric acid absorption tower used exceeds 60 meters. For example, the height of the ultra-large nitric acid absorption tower manufactured by China National Chemical Equipment Technology Corporation is 69 meters, and the height of the nitric acid absorption tower adopted in the Wanhua Fujian MDI project is 68.95 meters. Such a high nitric acid absorption tower makes it difficult in the operation processes of equipment processing, installation and positioning, etc. In the prior art, the improvement process of the absorption tower often only focuses on the adjustment of the internal structure of the tower. For example, CN 221580177U discloses a nitric acid absorption tower for improving separation effect. By adjusting the internal structure of the absorption tower, an atomizing disk, a swirl plate and a baffle demister are added to effectively and timely separate gas and liquid, ensuring the absorption effect of the upper atomizing disk. CN216223763U discloses an absorption tower for nitric acid production. By setting a current limiting plate inside the tower to increase the conversion efficiency of gas and liquid, and at the same time, setting a purification component to reduce environmental pollution.

[0004] Therefore, how to control the height of the nitric acid absorption tower to reduce the installation difficulty while ensuring the nitric acid absorption effect is an urgent problem to be solved in this field. Summary of the Utility Model

[0005] The purpose of the utility model is to overcome the above-mentioned deficiencies of the prior art and provide a nitric acid absorption system. Among them, the nitric acid absorption system includes a first absorption tower and a second absorption tower. By using two independently arranged absorption towers, the utility model effectively controls the total height of the absorption tower, reduces the installation operation difficulty of the absorption tower, and at the same time, sets the two absorption towers to negative pressure and slightly positive pressure respectively, improving the absorption effect on nitrogen oxides; meanwhile, reboilers are provided on both absorption towers, and the high-temperature tail gas produced by the second absorption tower provides heat for the first reboiler of the first absorption tower, effectively utilizing the high latent heat carried in the tail gas and reducing the external steam consumption.

[0006] To achieve the above technical effects, the utility model adopts the following technical solutions:

[0007] A nitric acid absorption system, comprising a first absorption tower and a second absorption tower, wherein the heights of the first absorption tower and the second absorption tower are 25m - 35m;

[0008] The lower part of the first absorption tower is provided with a first liquid inlet and a first gas inlet, the top of the first absorption tower is provided with a first gas outlet, the lower part of the second absorption tower is provided with a second liquid inlet and a second gas inlet, and the top of the second absorption tower is provided with a second gas outlet.

[0009] The first liquid inlet is connected to an external absorption liquid storage device, the first absorption tower is connected to the second liquid inlet through a first liquid outlet opened at the bottom, the second absorption tower is connected to an external nitric acid storage device through a second liquid outlet opened at the bottom, and the first gas outlet is connected to the second gas inlet.

[0010] Preferably, a first reboiler is provided at the bottom of the first absorption tower, a second reboiler is provided at the bottom of the second absorption tower, the second gas outlet is connected to the heat source inlet of the first reboiler, and the heat source outlet of the first reboiler is connected to a tail gas treatment device.

[0011] More preferably, the second reboiler uses an external heat source.

[0012] The nitric acid absorption system provided by the present utility model creatively uses two independently arranged first absorption tower and second absorption tower, effectively controls the total height of the absorption tower, and reduces the installation operation difficulty of the absorption tower; at the same time, reboilers are provided on both absorption towers, and the high-temperature tail gas produced by the second absorption tower provides heat for the first reboiler of the first absorption tower, so that the high latent heat carried in the tail gas is effectively utilized and the external steam consumption is reduced.

[0013] Preferably, both the first absorption tower and the second absorption tower are packed towers.

[0014] More preferably, the packing type of the packed tower is corrugated perforated plate packing.

[0015] Preferably, the top pressure of the first absorption tower is -0.2MPa to -0.1MPa, the top pressure of the second absorption tower is 0.1MPa to 0.2MPa, and a gas pumping device is provided between the first gas outlet and the second gas inlet.

[0016] By setting the first absorption tower to a slightly negative pressure and the second absorption tower to a slightly positive pressure, compared with the existing single-tower device, the absorption effect of nitrogen oxides is significantly improved.

[0017] Preferably, the empty tower gas velocity of the first absorption tower is 0.6m / s.

[0018] Preferably, the plate pressure of the first absorption tower is 0.2KPa.

[0019] Preferably, the first absorption tower and the second absorption tower are installed on the same horizontal plane.

[0020] Compared with the prior art, the beneficial effects of the present utility model are as follows:

[0021] 1. The nitric acid absorption system provided by the present utility model creatively uses two independently arranged first absorption towers and second absorption towers, effectively controlling the total height of the absorption towers and reducing the installation operation difficulty of the absorption towers; at the same time, reboilers are provided on both absorption towers, and the high-temperature tail gas produced by the second absorption tower provides heat for the first reboiler of the first absorption tower, effectively utilizing the high latent heat carried in the tail gas and reducing the external steam consumption.

[0022] 2. The nitric acid absorption system provided by the present utility model significantly improves the absorption effect of nitrogen oxides compared with the existing single-tower device by setting the first absorption tower to a slightly negative pressure and the second absorption tower to a slightly positive pressure. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a schematic diagram of the nitric acid absorption system provided for Example 1.

[0024] Among them, 1. First absorption tower; 11. First liquid inlet; 12. First gas inlet; 13. First gas outlet; 14. First liquid outlet; 15. First reboiler; 16. Tail gas treatment device; 2. Second absorption tower; 21. Second liquid inlet; 22. Second gas inlet; 23. Second gas outlet; 24. Second liquid outlet; 25. Second reboiler; 26. Gas pumping device. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0025] In order to enable those skilled in the art to more clearly understand the technical solutions of the present application, the technical solutions of the present application will be described in detail below with reference to specific embodiments. It should be noted that the following detailed description is illustrative and is intended to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which the present application belongs.

[0026] The devices used in the present utility model are all commonly used commercially available devices in the art, and the specific sources are not elaborated herein.

[0027] Example 1: A nitric acid absorption system

[0028] As Figure 1 shown, it includes a first absorption tower 1 and a second absorption tower 2, and the heights of the first absorption tower 1 and the second absorption tower 2 are 25m - 35m.

[0029] The lower part of the first absorption tower 1 is provided with a first liquid inlet 11 and a first gas inlet 12, the top of the first absorption tower 1 is provided with a first gas outlet 13, the lower part of the second absorption tower 2 is provided with a second liquid inlet 21 and a second gas inlet 22, the top of the second absorption tower 2 is provided with a second gas outlet 23. The first liquid inlet 11 is connected to an external absorption liquid storage device. The first absorption tower 1 is connected to the second liquid inlet 21 through a first liquid outlet 14 opened at the bottom. The second absorption tower 2 is connected to an external nitric acid storage device through a second liquid outlet 24 opened at the bottom. The first gas outlet 13 is connected to the second gas inlet 22.

[0030] A first reboiler 15 is provided at the bottom of the first absorption tower 1, and a second reboiler 25 is provided at the bottom of the second absorption tower 2. The second gas outlet 23 is connected to the heat source inlet of the first reboiler 15, and the heat source outlet of the first reboiler 15 is connected to a tail gas treatment device 16. A second reboiler 25 is provided at the bottom of the second absorption tower 2, and the second reboiler 25 uses an external heat source.

[0031] Both the first absorption tower 1 and the second absorption tower 2 are packed towers, and the packing type of the packed tower is corrugated perforated plate packing.

[0032] The top pressure of the first absorption tower 1 is -0.2 MPa to -0.1 MPa, and the top pressure of the second absorption tower 2 is 0.1 MPa to 0.2 MPa. A gas pumping device 26 is provided between the first gas outlet 13 and the second gas inlet 22. The first absorption tower 1 and the second absorption tower 2 are installed on the same horizontal plane.

[0033] The nitric acid absorption system provided by the present utility model creatively uses two independently arranged first absorption tower 1 and second absorption tower 2, effectively controls the total height of the absorption tower, and reduces the installation operation difficulty of the absorption tower. At the same time, reboilers are provided on both absorption towers. The high-temperature tail gas produced by the second absorption tower 2 provides heat for the first reboiler 15 of the first absorption tower 1, effectively utilizes the high latent heat carried in the tail gas, and reduces the external steam consumption.

[0034] The above are only the preferred embodiments of the present application and are not intended to limit the present application. For those skilled in the art, the present application can have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A nitric acid absorption system, characterized in that, It includes a first absorption tower (1) and a second absorption tower (2), and the heights of the first absorption tower (1) and the second absorption tower (2) are 25m - 35m; The lower part of the first absorption tower (1) is provided with a first liquid inlet (11) and a first gas inlet (12), the top of the first absorption tower (1) is provided with a first gas outlet (13), the lower part of the second absorption tower (2) is provided with a second liquid inlet (21) and a second gas inlet (22), and the top of the second absorption tower (2) is provided with a second gas outlet (23). The first liquid inlet (11) is connected to an external absorption liquid storage device. The first absorption tower (1) is connected to the second liquid inlet (21) through a first liquid outlet (14) opened at the bottom. The second absorption tower (2) is connected to an external nitric acid storage device through a second liquid outlet (24) opened at the bottom. The first gas outlet (13) is connected to the second gas inlet (22).

2. The nitric acid absorption system according to claim 1, wherein, A first reboiler (15) is provided at the bottom of the first absorption tower (1), a second reboiler (25) is provided at the bottom of the second absorption tower (2), the second gas outlet (23) is connected to the heat source inlet of the first reboiler (15), and the heat source outlet of the first reboiler (15) is connected to a tail gas treatment device (16).

3. The nitric acid absorption system according to claim 2, characterized in that, The second reboiler (25) uses an external heat source.

4. The nitric acid absorption system according to claim 1, characterized in that, Both the first absorption tower (1) and the second absorption tower (2) are packed towers.

5. The nitric acid absorption system according to claim 4, characterized in that, The packing type of the packed tower is corrugated perforated plate packing.

6. The nitric acid absorption system according to claim 1, characterized in that, A gas pumping device (26) is provided between the first gas outlet (13) and the second gas inlet (22).

7. The nitric acid absorption system according to claim 1, wherein The first absorption tower (1) and the second absorption tower (2) are installed on the same horizontal plane.

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