Multi-stage treatment system for acid gas

Abstract

The utility model relates to the technical field of acid gas treatment, in particular to a multi-stage treatment system for acid gas, which comprises a first-stage alkaline tower, a second-stage alkaline tower, a dehydration facility and an activated carbon adsorption facility which are connected in sequence, the device disclosed by the utility model has the beneficial effects that the two stages of alkaline washing towers are connected in series, so that the total gas-liquid contact area is increased, and the removal efficiency of acid gas is improved; through the dense design of nozzles on the periphery of the tower body, the liquid film coverage rate of the tower wall area is increased, gas escape is avoided, and the alkali washing efficiency is further improved; the Pall ring packing is made of CPVC materials, the corrosion resistance is better than that of traditional PP materials, the service life is prolonged, meanwhile, the packing layer is high in anti-blocking capacity, and the shutdown cleaning frequency is reduced.

Description

Technical Field

[0001] This utility model relates to the field of acid gas treatment technology, specifically to a multi-stage treatment system for acid gases. Background Technology

[0002] In the production process of dicarboxylic acid plants, the treatment of acidic tail gas is a crucial aspect of environmental protection and production cost control. Existing acidic gas treatment systems suffer from the following main drawbacks:

[0003] First, wastewater treatment costs are high;

[0004] Existing technologies generate large amounts of wastewater during exhaust gas treatment, requiring significant investment in wastewater treatment and thus increasing production costs considerably. For example, traditional single-stage alkaline washing processes have low alkali utilization rates, and frequent replacement of expired alkali solutions generates large amounts of high-salinity wastewater, increasing the load on subsequent water treatment and requiring additional sewage discharge fees.

[0005] Second, the consumption of caustic soda remains high;

[0006] The existing process consumes a large amount of alkali, and the reaction efficiency between the alkaline absorbent and acidic gas is insufficient, resulting in significant waste of caustic soda. Especially when dealing with high concentrations of acidic gas, a continuous supply of high-concentration alkali solution is required to ensure neutralization, further increasing raw material costs.

[0007] III. Design flaws in the tower body spray structure;

[0008] Uneven spray density: Existing alkaline scrubbing towers have insufficient spray density around the tower body, and the liquid film overlaps sparsely near the tower wall, resulting in weak acid gas capture capacity near the tower wall. For example, traditional single-nozzle spraying methods cannot cover the entire cross-section of the tower body, and gas "escape channels" are easily formed in the tower wall area, reducing the overall purification efficiency.

[0009] Insufficient gas-liquid contact: The short contact time and small reaction area between acidic gases and alkaline solutions prevent the complete neutralization of high-concentration acidic gases entering the tower. Traditional packing layers, due to insufficient corrosion resistance of materials or unreasonable structural design, are prone to salt crystallization and blockage, further reducing the gas-liquid contact area, resulting in incomplete exhaust gas purification and affecting air quality.

[0010] Therefore, a multi-stage treatment system for acidic gases is needed to avoid the aforementioned problems. Utility Model Content

[0011] To address the aforementioned problems, this utility model provides a multi-stage treatment system for acidic gases, thereby achieving the goal of resolving the issues raised in the background art.

[0012] To achieve the above objectives, this utility model embodiment employs the following technical solution: a multi-stage treatment system for acidic gases, comprising a primary alkaline scrubbing tower, a secondary alkaline scrubbing tower, a dehydration facility, and an activated carbon adsorption facility connected sequentially; both the primary and secondary alkaline scrubbing towers include a tower body, a packing layer, a spray assembly, and a circulating pump; the tower body has a gas inlet and a gas outlet; the packing layer uses CPVC Pall ring packing, filling the middle of the tower body to increase the gas-liquid contact area; the spray assembly includes multiple layers of spray pipes distributed above the packing layer, with nozzles evenly arranged circumferentially in the spray pipes, and the nozzle density near the sidewall of the tower body is greater than that in the central area; the circulating pump connects the alkaline solution outlet and the alkaline solution inlet to drive the alkaline solution circulation spray; the dehydration facility is connected to the gas outlet of the secondary alkaline scrubbing tower to remove moisture from the gas phase; the activated carbon adsorption facility is connected to the gas outlet of the dehydration facility to purify the gas.

[0013] As a further improvement to the above technical solution:

[0014] The nozzles of the spray assembly are spiral atomizing nozzles with a spray angle ≥120°.

[0015] The height of the packing layer is 1 / 3 to 1 / 2 of the total height of the tower.

[0016] The outlet end of the circulating pump is equipped with a heat exchanger for adjusting the temperature of the alkali solution.

[0017] The beneficial effects of this utility model embodiment are as follows:

[0018] In this application, a two-stage alkaline scrubbing tower is connected in series to increase the total gas-liquid contact area and improve the removal efficiency of acidic gases. The denser nozzle design around the tower body increases the liquid film coverage in the tower wall area, preventing gas escape and further improving the alkaline scrubbing efficiency. The Pall ring packing is made of CPVC material, which has better corrosion resistance than traditional PP material, extending its service life. At the same time, the packing layer has strong anti-clogging ability, reducing the frequency of shutdown for cleaning. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the structure of this utility model.

[0020] In the diagram: 1. Primary alkaline washing tower; 2. Secondary alkaline washing tower; 3. Dehydration equipment; 4. Activated carbon adsorption equipment;

[0021] 21. Tower body; 22. Packing layer; 23. Spray assembly;

[0022] 211. Gas inlet; 212. Gas outlet. Detailed Implementation

[0023] Preferred embodiments of the present invention will now be described with reference to the accompanying drawings. Those skilled in the art should understand that these embodiments are merely illustrative of the technical principles of the present invention and are not intended to limit the scope of protection of the present invention.

[0024] See Figure 1 This utility model discloses a multi-stage treatment system for acidic gases, including a primary alkaline scrubbing tower 1, a secondary alkaline scrubbing tower 2, a dehydration facility 3, and an activated carbon adsorption facility 4 connected in sequence, forming a complete purification system of "absorption-dehydration-adsorption".

[0025] Both the primary alkaline scrubbing tower 1 and the secondary alkaline scrubbing tower 2 include:

[0026] The tower body 21 has a gas inlet 211 at the bottom of the tower body 21 and a gas outlet 212 at the top of the tower body 21 on its side wall.

[0027] Packing layer 22: Filled with Pall ring packing made of CPVC material. The special structure of the Pall ring packing increases the gas-liquid contact area in the packing layer 22. At the same time, the porosity of the packing layer is optimized to reduce salt crystal deposition.

[0028] Spray assembly 23: includes multiple layers of spray pipes, uniformly arranged circumferentially above the packing layer 22. Each layer of pipes is equipped with spiral atomizing nozzles (spray angle ≥120°), wherein the nozzle density near the side wall of the tower body 21 is higher than the nozzle density in the middle area (e.g., nozzle spacing 200mm in the middle area and nozzle spacing 150mm in the side wall area), thereby increasing the spray density around the tower body 21 and enhancing the collection efficiency of acidic gases near the tower wall;

[0029] Circulation pump: A corrosion-resistant centrifugal pump is used, with a heat exchanger connected in series at the outlet end. The temperature of the alkali solution is controlled by circulating cooling water to avoid alkali loss due to evaporation caused by high temperature.

[0030] The dehydration facility 3 can use a wire mesh demister, which is connected to the gas outlet 212 of the secondary alkaline washing tower 2 to remove liquid droplets in the gas phase and reduce the moisture content of the gas entering the activated carbon adsorption facility 4.

[0031] The activated carbon adsorption facility 4 can be a fixed-bed adsorption device, filled with honeycomb activated carbon, to further adsorb residual components of acidic gases, and finally the exhaust gas is discharged after testing and meeting the standards.

[0032] The workflow of this application:

[0033] Tail gas collection and primary alkaline scrubbing: Acidic tail gas enters the gas inlet 211 of the primary alkaline scrubbing tower 1 through the gas collection manifold, and comes into countercurrent contact with the alkaline solution sprayed from the spray assembly 23. The acidic gas in the gas phase is neutralized by the alkaline solution, and the concentration of acidic gas is reduced after primary treatment. The treated gas phase enters the secondary alkaline scrubbing tower 2 from the gas outlet 212.

[0034] Secondary alkaline scrubbing and deep purification: The gas phase comes into countercurrent contact with the circulating alkaline solution in the secondary alkaline scrubbing tower 2, further reducing the concentration of acidic gas;

[0035] Dehydration and activated carbon adsorption: The gas phase after the secondary alkaline wash carries a small amount of moisture. After being removed by the dehydration facility 3, it enters the activated carbon adsorption facility 4. Acidic gases and organic matter are removed through physical adsorption. Finally, the concentration of acidic gases in the exhaust gas meets the emission standards, and the gas is discharged through the gas outlet of the activated carbon adsorption facility 4 in compliance with the standards.

[0036] Alkali circulation and treatment: The alkali solution in the primary and secondary alkali washing towers is continuously circulated by circulation pumps. When the pH value of the alkali solution drops to the ineffective range, the ineffective alkali solution is transported to the sewage treatment plant through the drain outlet. At the same time, alkali solution is replenished through the water inlet to maintain stable system operation.

[0037] In this application, the total gas-liquid contact area is increased by connecting two-stage alkaline scrubbing towers in series, thereby improving the removal efficiency of acidic gases. The denser design of the nozzles around the 21st circumference of the tower body increases the liquid film coverage in the tower wall area, preventing gas escape and further improving the alkaline scrubbing efficiency. The Pall ring packing is made of CPVC material, which has better corrosion resistance than traditional PP material, extending its service life. At the same time, the packing layer 22 has strong anti-clogging ability, reducing the frequency of shutdown for cleaning.

[0038] It should be noted that in the description of this utility model, terms such as "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," which indicate direction or positional relationships, are based on the direction or positional relationships shown in the accompanying drawings. These are used merely for ease of description and do not indicate or imply that the device or element must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0039] Furthermore, it should be noted that, in the description of this utility model, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model according to the specific circumstances.

[0040] The term "comprising" or any other similar term is intended to cover non-exclusive inclusion, such that a process, article, or apparatus / device that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to those processes, articles, or apparatus / devices.

[0041] The technical solution of this utility model has been described in conjunction with the preferred embodiments shown in the accompanying drawings. However, it will be readily understood by those skilled in the art that the protection scope of this utility model is obviously not limited to these specific embodiments. Without departing from the principle of this utility model, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will all fall within the protection scope of this utility model.

Claims

1. A multi-stage treatment system for acidic gases, characterized in that, It includes a primary alkaline washing tower (1), a secondary alkaline washing tower (2), a dehydration facility (3), and an activated carbon adsorption facility (4) connected in sequence; Both the primary alkaline scrubbing tower (1) and the secondary alkaline scrubbing tower (2) include a tower body (21), a packing layer (22), a spray assembly (23), and a circulating pump; the tower body (21) is provided with a gas inlet (211) and a gas outlet (212); the packing layer (22) is made of CPVC material Pall ring packing, which is filled in the middle of the tower body (21) to increase the gas-liquid contact area; The spray assembly (23) includes a multi-layer spray pipe distributed above the packing layer (22). The spray pipe has nozzles evenly arranged around its circumference, and the nozzle density near the side wall of the tower body (21) is greater than that in the central area. The circulating pump is connected to the alkali outlet and the alkali inlet and is used to drive the alkali circulation spray. The dehydration facility (3) is connected to the gas outlet (212) of the secondary alkaline scrubbing tower (2) to remove moisture from the gas phase; the activated carbon adsorption facility (4) is connected to the gas outlet of the dehydration facility (3) to purify the gas.

2. The multi-stage treatment system for acidic gases according to claim 1, characterized in that, The nozzle of the spray assembly (23) is a spiral atomizing nozzle with a spray angle ≥120°.

3. The multi-stage treatment system for acidic gases according to claim 1, characterized in that, The height of the packing layer (22) is 1 / 3 to 1 / 2 of the total height of the tower body (21).

4. The multi-stage treatment system for acidic gases according to claim 1, characterized in that, The outlet end of the circulating pump is equipped with a heat exchanger for adjusting the temperature of the alkali solution.

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