Sulfuric acid tail gas deep desulfurization, denitrification and demercuration integrated device and treatment method thereof

Abstract

The invention discloses a sulfuric acid tail gas deep desulfurization, denitrification and demercuration integrated device and a treatment method thereof, and relates to the technical field of environmental protection technology and chemical waste gas treatment. The device sequentially comprises a cooling, tempering and pre-oxidation module, a heat exchanger with a built-in dilute acid corrosion resistant material, a circulating spraying unit, an oxidizing agent feeding port and a pre-oxidation unit in the airflow direction, the core of the desulfurization, denitrification and demercuration functional module is expanded polytetrafluoroethylene (e-PTFE) matrix filler embedded with a selective adsorption functional polymer group on the surface; the liquid coalescence and efficient demisting module sequentially comprises a liquid coalescer, a first-stage efficient fiber demister and a second-stage efficient fiber demister, the first-stage efficient fiber demister and the second-stage efficient fiber demister are connected in series, and a porous distribution partition plate with a spiral flow deflector is arranged between the two stages of demisters. According to the invention, an innovative pre-oxidation and cooperative treatment front end is designed, a corrosion-resistant material heat exchanger is combined with high-efficiency oxidant addition, pre-oxidation of NO, Hg and SO2 is completed at a proper temperature, and a foundation is laid for subsequent deep removal.

Description

Technical Field

[0001] This invention belongs to the field of environmental protection technology and chemical waste gas treatment technology, specifically a deep desulfurization, denitrification and mercury removal integrated device for sulfuric acid tail gas and its treatment method. Background Technology

[0002] Sulfuric acid production exhaust gas has a complex composition, containing not only residual sulfur dioxide but also nitrogen oxides, gaseous elemental mercury or mercury compounds, sulfuric acid mist droplets, and small amounts of sulfur trioxide (SO3). With increasingly stringent environmental regulations, exhaust gas emissions must achieve ultra-low or even near-zero emissions of multiple pollutants. Traditional single technologies (such as alkaline absorption desulfurization, selective catalytic reduction denitrification, and activated carbon or organic mercury removal agent adsorption) often suffer from problems such as lengthy processes, high equipment investment, high operating costs, and insufficient efficiency in the synergistic removal of multiple pollutants, particularly in controlling sulfur dioxide emissions and capturing mercury and fine sulfuric acid mist. There is an urgent need to develop an integrated, efficient, stable, and reliable deep purification technology and device.

[0003] The information disclosed above in this background section is only for enhancing the understanding of the background section of this invention, and therefore may include prior art that is not known to those skilled in the art. Summary of the Invention

[0004] The purpose of this invention is to provide an integrated device and method for deep desulfurization, denitrification and mercury removal of sulfuric acid tail gas, which aims to achieve efficient and synergistic removal and emission compliance of multiple pollutants such as SO2, NOx, Hg and sulfuric acid mist.

[0005] To achieve the above objectives, the present invention provides the following technical solution: an integrated device for deep desulfurization, denitrification, and mercury removal of sulfuric acid tail gas, comprising, in sequence along the gas flow direction:

[0006] The cooling and conditioning pre-oxidation module has a built-in heat exchanger made of dilute acid corrosion resistant material, a circulating spray unit, an oxidant dosing port and a pre-oxidation unit;

[0007] The core of the desulfurization, denitrification and mercury removal functional module is an expanded polytetrafluoroethylene (e-PTFE) matrix filler with selective adsorption functional polymer groups embedded on its surface;

[0008] The liquid coalescing and high-efficiency demisting module includes, in sequence, a liquid coalescer, a first-stage high-efficiency fiber demister and a second-stage high-efficiency fiber demister arranged in series, and a porous distribution baffle with spiral guide vanes is provided between the two-stage demisters.

[0009] The functional activated carbon adsorption unit is located at the end of the integrated device and is filled with highly efficient modified activated carbon.

[0010] Preferably, the heat exchanger in the cooling, conditioning, and pre-oxidation module is made of fluoroplastic or silicon carbide; the oxidant is ozone, hydrogen peroxide, or an online-prepared persulfate solution.

[0011] Preferably, the functional polymer groups in the desulfurization, denitrification, and mercury removal functional module include amino and / or sulfonic acid groups for adsorbing sulfur dioxide and nitrogen oxides, and thiol groups for adsorbing mercury.

[0012] Preferably, the desulfurization, denitrification and mercury removal functional module includes, in sequence, a denitrification catalytic unit, a desulfurization catalytic unit, and a mercury removal catalytic unit, with an acid discharge port at the bottom.

[0013] Preferably, the porous distribution partition between the two-stage high-efficiency fiber demister has an opening rate of 40%-60%, and a spiral guide vane with an inclination angle of 30-60 degrees is fixedly installed on the partition.

[0014] Preferably, the bottom of the porous partition is provided with an acid discharge port 2.

[0015] Preferably, the cooling and conditioning pre-oxidation module, the desulfurization, denitrification and mercury removal functional module, and the liquid coalescence and high-efficiency demisting module are connected in sequence.

[0016] The present invention also provides a method for treating sulfuric acid tail gas using the above-mentioned integrated device, comprising the following steps:

[0017] Step a. The exhaust gas enters the cooling, conditioning and pre-oxidation module, where it is cooled, sprayed and conditioned, and oxidant is introduced for pre-oxidation, oxidizing SO2 to SO3, NO to NO2, and elemental mercury to divalent mercury.

[0018] Step b. The pre-oxidized exhaust gas enters the desulfurization, denitrification, and mercury removal functional module, where SO2, NOx, and Hg are removed. 2+ Adsorbed and removed by functional polymer groups;

[0019] Step c. The gas enters the liquid coalescer, causing the fine sulfuric acid mist and mercury droplets to coalesce and grow;

[0020] Step d. The gas passes sequentially through a primary high-efficiency fiber demister, a porous distribution baffle with spiral guide vanes, and a secondary high-efficiency fiber demister to deeply remove liquid droplets;

[0021] Step e. The gas flows through the functional activated carbon adsorption unit, where residual pollutants are thoroughly removed before being discharged in compliance with emission standards.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] 1. This invention designs an innovative pre-oxidation and synergistic treatment front end, employing a corrosion-resistant heat exchanger combined with high-efficiency oxidant dosing to complete the removal of NO and Hg at a suitable temperature. 0The pre-oxidation of SO2 lays the foundation for subsequent deep removal.

[0024] 2. This invention utilizes the excellent physicochemical properties of e-PTFE expanded polytetrafluoroethylene (e-PTFE) material as a stable substrate. By embedding multifunctional polymer groups, it achieves efficient and synergistic removal of sulfur, nitrates, and mercury within a single module, significantly simplifying the process and improving efficiency.

[0025] 3. This invention designs an innovative four-stage series structure of "coalescing-first-stage demisting-swirl distribution-second-stage demisting". The porous distribution partition in the middle has a spiral guide plate, which greatly enhances the removal efficiency of fine droplets (sulfuric acid mist and mercury droplets) and solves the problem of insufficient collection efficiency of submicron droplets by traditional demisters.

[0026] 4. The present invention sets up an activated carbon unit at the end of the device to ensure the complete interception of residual pollutants, especially mercury, in complex exhaust gases, and to ensure stable and compliant emissions.

[0027] 5. This invention achieves high efficiency through integrated design, with each unit having a clear function and working synergistically to form a high-efficiency, compact, and reliable deep purification system, which is particularly suitable for stringent emission requirements in complex working conditions such as sulfuric acid tail gas. Attached Figure Description

[0028] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in this invention. For those skilled in the art, other drawings can be obtained based on these drawings.

[0029] Figure 1 This is a schematic diagram of the integrated device for deep desulfurization, denitrification, and mercury removal of sulfuric acid tail gas according to the present invention.

[0030] In the picture:

[0031] 1. Cooling, conditioning, and pre-oxidation module; 11. Heat exchanger; 12. Circulating spray unit; 13. Oxidant dosing port; 14. Pre-oxidation unit; 2. Desulfurization, denitrification, and mercury removal functional module; 21. Denitrification catalytic unit; 22. Desulfurization catalytic unit; 23. Mercury removal catalytic unit; 24. Acid discharge port one; 3. Liquid coalescence and high-efficiency demister module; 31. Liquid coalescer; 32. Primary high-efficiency fiber demister; 33. Secondary high-efficiency fiber demister; 34. Porous distribution baffle; 341. Spiral guide vane; 35. Acid discharge port two; 4. Functional activated carbon adsorption unit. Detailed Implementation

[0032] To enable those skilled in the art to better understand the technical solutions of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0033] Example 1:

[0034] An integrated device for deep desulfurization, denitrification, and mercury removal of sulfuric acid tail gas includes, in sequence along the airflow direction, a cooling, conditioning, and pre-oxidation module 1; a desulfurization, denitrification, and mercury removal functional module 2; a liquid coalescence and high-efficiency demisting module 3; and a functional activated carbon adsorption unit 4.

[0035] The cooling and conditioning pre-oxidation module 1 has a built-in heat exchanger 11 made of dilute acid corrosion resistant material, a circulating spray unit 12, an oxidant dosing port 13, and a pre-oxidation unit 14;

[0036] Specifically, the heat exchanger 11 in the cooling, conditioning, and pre-oxidation module 1 is made of fluoroplastic or silicon carbide; the oxidant is ozone, hydrogen peroxide, or an online-prepared persulfate solution. The exhaust gas is first cooled to a suitable reaction temperature in this module, such as 25℃-65℃. A spray liquid adjusts the gas-liquid interface properties, and an oxidant is added simultaneously to oxidize SO2 in the exhaust gas to SO3, insoluble NO to water-soluble NO2, and elemental mercury (Hg) to... 0 ) is oxidized to easily captured divalent mercury ions (Hg) 2+ ).

[0037] The core of the desulfurization, denitrification and mercury removal functional module 2 is an expanded polytetrafluoroethylene (e-PTFE) matrix filler with selective adsorption functional polymer groups embedded on its surface;

[0038] Specifically, the functional polymer groups in the desulfurization, denitrification, and mercury removal module 2 include amino and / or sulfonic acid groups for adsorbing sulfur dioxide and nitrogen oxides, and thiol groups for adsorbing mercury. The e-PTFE matrix possesses excellent chemical inertness, temperature resistance, and hydrophobicity. The functionalized polymer groups can simultaneously and efficiently adsorb / absorb / catalytically oxidize pre-oxidized SO2, NOx (mainly NO2), and Hg. 2+ Ions are used to achieve synergistic and deep removal of three major pollutants: sulfur, nitrate, and mercury.

[0039] Specifically, the desulfurization, denitrification, and mercury removal functional module 2 includes, in sequence, a denitrification catalytic unit 21, a desulfurization catalytic unit 22, and a mercury removal catalytic unit 23, with an acid discharge port 24 at the bottom. A distributor support is provided at the bottom of the desulfurization, denitrification, and mercury removal functional module 2.

[0040] The liquid coalescence and high-efficiency demisting module 3 includes a liquid coalescer 31, a first-stage high-efficiency fiber demister 32 and a second-stage high-efficiency fiber demister 33 arranged in series, and a porous distribution partition 34 with spiral guide vanes 341 is provided between the two-stage demisters.

[0041] Specifically, the porous distribution partition 34 between the two-stage high-efficiency fiber demisters has an opening rate of 40%-60%, and a spiral guide vane 341 with an inclination angle of 30-60 degrees is fixedly installed on the partition.

[0042] Liquid coalescer 31 utilizes a specially designed internal structure (such as a multi-layered woven fiber mesh or a pyramidal sleeve structure) to facilitate the formation of fine sulfuric acid mist droplets and liquid mercury (from Hg). 2+ After reduction or capture, the droplets collide, coalesce, and grow, increasing their size. Subsequently, the aerosol enters the first-stage high-efficiency fiber demister 32, removing most of the increased-sized droplets. A porous distribution baffle 34 with spiral guide vanes 341 is installed between the two-stage demisters, forcing the airflow to rotate. This utilizes centrifugal force to further enhance the collision and capture efficiency of droplets and fibers, and ensures that the airflow is evenly distributed in the second-stage high-efficiency fiber demister 33, achieving deep removal of residual fine droplets.

[0043] Specifically, the bottom of the porous partition 34 is provided with an acid discharge port 2 35.

[0044] Specifically, the cooling and conditioning pre-oxidation module 1, the desulfurization, denitrification and mercury removal functional module 2, and the liquid coalescence and high-efficiency demisting module 3 are connected in sequence.

[0045] Functional activated carbon adsorption unit 4, located at the end of the integrated device, is filled with highly efficient modified activated carbon (such as sulfur-loaded activated carbon or halide-loaded activated carbon), mainly used to adsorb and capture trace amounts of mercury vapor (Hg) that may escape from the preceding unit. 0 (and trace amounts of organic pollutants, as the final guarantee for achieving emission standards.)

[0046] Example 2:

[0047] The method for treating sulfuric acid tail gas using an integrated device includes the following steps:

[0048] Step a. The exhaust gas enters the cooling, conditioning and pre-oxidation module 1, where it is cooled, sprayed and conditioned, and oxidant is introduced for pre-oxidation, oxidizing SO2 to SO3, NO to NO2, and elemental mercury to divalent mercury.

[0049] Step b. The pre-oxidized exhaust gas enters the desulfurization, denitrification, and mercury removal functional module 2, where SO2, NOx, and Hg are removed. 2+ Adsorbed and removed by functional polymer groups;

[0050] Step c. Gas enters liquid coalescer 31, causing fine sulfuric acid mist and mercury droplets to coalesce and grow;

[0051] Step d. The gas passes sequentially through a primary high-efficiency fiber demister 32, a porous distribution baffle 34 with spiral guide vanes 341, and a secondary high-efficiency fiber demister 33 to deeply remove droplets;

[0052] Step e. The gas flows through the functional activated carbon adsorption unit 4, where residual pollutants are thoroughly removed before being discharged in compliance with emission standards.

[0053] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; 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; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0054] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "over," and "on top" of the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0055] The foregoing has only described certain exemplary embodiments of the present invention by way of illustration. Undoubtedly, those skilled in the art can modify the described embodiments in various ways without departing from the spirit and scope of the present invention. Therefore, the foregoing drawings and descriptions are illustrative in nature and should not be construed as limiting the scope of protection of the claims of the present invention.

Claims

1. An integrated device for deep desulfurization, denitrification, and mercury removal of sulfuric acid tail gas, characterized in that, Along the airflow direction, the following are included in sequence: The cooling and conditioning pre-oxidation module (1) is equipped with a heat exchanger (11) made of dilute acid corrosion resistant material, a circulating spray unit (12), an oxidant dosing port (13) and a pre-oxidation unit (14). The desulfurization, denitrification and mercury removal functional module (2) is a core component of expanded polytetrafluoroethylene (e-PTFE) matrix filler with selective adsorption functional polymer groups embedded on its surface. The liquid coalescence and high-efficiency demisting module (3) includes a liquid coalescer (31), a first-stage high-efficiency fiber demister (32) and a second-stage high-efficiency fiber demister (33) arranged in series, and a porous distribution baffle (34) with spiral guide vanes (341) is provided between the two-stage demisters. The functional activated carbon adsorption unit (4) is located at the end of the integrated device and is filled with highly efficient modified activated carbon.

2. The integrated device for deep desulfurization, denitrification, and mercury removal of sulfuric acid tail gas according to claim 1, characterized in that: The heat exchanger (11) in the cooling and conditioning pre-oxidation module (1) is made of fluoroplastic or silicon carbide; the oxidant is ozone, hydrogen peroxide or persulfate solution prepared online.

3. The integrated device for deep desulfurization, denitrification, and mercury removal of sulfuric acid tail gas according to claim 1, characterized in that: The functional polymer groups in the desulfurization, denitrification and mercury removal functional module (2) include amino and / or sulfonic acid groups for adsorbing sulfur dioxide and nitrogen oxides, and mercapto groups for adsorbing mercury.

4. The integrated device for deep desulfurization, denitrification, and mercury removal of sulfuric acid tail gas according to claim 1, characterized in that: The desulfurization, denitrification and mercury removal functional module (2) includes a denitrification catalytic unit (21), a desulfurization catalytic unit (22), and a mercury removal catalytic unit (23) in sequence, and an acid discharge port (24) is provided at the bottom.

5. The integrated device for deep desulfurization, denitrification, and mercury removal of sulfuric acid tail gas according to claim 1, characterized in that: The porous distribution partition (34) between the two-stage high-efficiency fiber demisters has an opening rate of 40%-60%, and a spiral guide vane (341) with an inclination angle of 30-60 degrees is fixedly installed on the partition.

6. The integrated device for deep desulfurization, denitrification, and mercury removal of sulfuric acid tail gas according to claim 1, characterized in that: The bottom of the porous distribution partition (34) is provided with an acid discharge port two (35).

7. The integrated device for deep desulfurization, denitrification, and mercury removal of sulfuric acid tail gas according to claim 1, characterized in that: The cooling and conditioning pre-oxidation module (1), the desulfurization, denitrification and mercury removal functional module (2), and the liquid coalescence and high-efficiency demisting module (3) are connected in sequence.

8. The method for treating sulfuric acid tail gas using the integrated device according to any one of claims 1-7, characterized in that, Includes the following steps: Step a. The exhaust gas enters the cooling and conditioning pre-oxidation module (1), where it is cooled, sprayed and conditioned, and oxidant is introduced for pre-oxidation, oxidizing SO2 to SO3, NO to NO2, and elemental mercury to divalent mercury. Step b. The pre-oxidized tail gas enters the desulfurization, denitrification, and mercury removal functional module (2), where SO2, NOx, and Hg are removed. 2+ Adsorbed and removed by functional polymer groups; Step c. Gas enters the liquid coalescer (31), causing fine sulfuric acid mist and mercury droplets to coalesce and grow; Step d. The gas passes sequentially through a primary high-efficiency fiber demister (32), a porous distribution baffle (34) with spiral guide vanes (341), and a secondary high-efficiency fiber demister (33) to deeply remove droplets; Step e. The gas flows through the functional activated carbon adsorption unit (4) and is discharged in compliance with standards after deep removal of residual pollutants.

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