Deacidification treatment process for flue gas containing high-concentration fluorine and chlorine
By modifying the deacidifying agent that combines natural zeolite with lime powder, the problem of baking soda's tendency to deliquesce and caking was solved, achieving efficient and stable deacidification of high-fluoride and chlorine flue gas, and improving the service life and economic benefits of the equipment.
Patent Information
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- SHANGHAI BOSHIGAO ENVIRONMENTAL TECH CO LTD
- Filing Date
- 2025-05-12
- Publication Date
- 2026-07-16
AI Technical Summary
Existing deacidifying agents such as baking soda are prone to deliquescence and caking, resulting in low deacidification efficiency, especially for flue gas containing high levels of fluorine and chlorine.
A deacidifying agent is prepared by combining modified natural zeolite with lime powder. The strong adsorption capacity of zeolite and the defluorination performance of lime are utilized, along with the stability of modified sodium bicarbonate. A dry deacidification process is then used to treat the flue gas, employing a temperature-resistant and corrosion-resistant bag filter.
It improved flue gas deacidification efficiency, reduced corrosion from high-fluorinated chlorine flue gas, lowered operating costs, extended equipment life, and achieved efficient and stable deacidification results.
Abstract
Description
A desulfurization process for flue gas containing high levels of fluorine and chlorine. Technical Field
[0001] This invention belongs to the field of flue gas treatment technology and relates to a deacidification treatment process for flue gas containing high levels of fluorine and chlorine. Background Technology
[0002] The flue gas from hazardous waste incineration systems typically contains high concentrations of HCl, SO2, small amounts of HF, and other acidic substances. These acidic substances have a significant impact on atmospheric pollution, making the purification of such flue gas particularly important.
[0003] Currently, wet desulfurization is mostly used for acidic flue gas, which involves spraying alkaline solution (sodium hydroxide solution) into a desulfurization tower or scrubbing tower. This produces a large amount of high-salt wastewater. The soluble salts in this wastewater can only be separated from the liquid through evaporation and crystallization. These salts are then treated and disposed of as hazardous waste. Dry desulfurization technology is a commonly used flue gas purification method. Its advantage is that wastewater is generated during the desulfurization process, and the resulting salts, dust, and excess desulfurizing agent are collected and aggregated into fly ash by a bag filter. In dry desulfurization technology, the preparation of the desulfurizing agent is one of the key steps. Commonly used desulfurizing agents include alkaline substances such as sodium hydroxide, lime, and baking soda. However, commonly used desulfurizing agents have some problems in use. For example, baking soda easily combines with moisture in the air, causing deliquescence and caking, which greatly affects the desulfurization efficiency. At the same time, baking soda has low defluorination efficiency and is ineffective for desulfurizing flue gas containing high levels of fluorine and chlorine. Therefore, it is essential to prepare deacidifying agents with good reactivity and stability in flue gas environments. Summary of the Invention
[0004] The purpose of this invention is to provide a deacidification treatment process for flue gas containing high levels of fluorine and chlorine, which has the characteristic of high deacidification efficiency.
[0005] The objective of this invention can be achieved through the following technical solutions:
[0006] A desulfurization process for flue gas containing high levels of chlorofluorocarbons (CFCs), the process flow of which is as follows:
[0007] S1: The incineration flue gas is introduced into the flue gas quench tower and atomized cooling water is sprayed in to rapidly reduce the flue gas temperature to below 200 ℃ within 1.0 s, and the cooling water is controlled to prevent condensation in the tower.
[0008] S2: The flue gas after rapid cooling enters the dry deacidification reaction tower. The deacidification agent is added to the dry deacidification reaction tower by airflow to react with acidic substances such as HCl, SO2, and HF in the flue gas to remove acid.
[0009] The deacidifying agent is prepared as follows:
[0010] S1-1: Add 10 parts by weight of natural zeolite to 90 parts by weight of sodium hydroxide solution, stir for 24 h, wash 3 times with deionized water of the same mass as the zeolite, and then dry in a vacuum drying oven at 60 ℃ for 12 h to obtain powder A.
[0011] S1-2: Mix powder A and lime powder evenly, place them in a muffle furnace for roasting at a temperature of 400~600 ℃, and cool them to room temperature at a rate of 5 ℃ / min to obtain powder B;
[0012] S1-3: Mix powder B and modified baking soda, grind in a grinder for 30 min at a grinding speed of 800 r / min, and then pass through a 300-mesh sieve to obtain the deacidifying agent;
[0013] S3: The flue gas after deacidification in the dry deacidification reaction tower is further purified by a bag filter to capture dust and excess deacidification agent in the flue gas, and further remove residual acidic substances at the interface of the bag filter. The purified flue gas meets the emission standards and is discharged above the filter bag support plate.
[0014] Furthermore, the preparation method of the modified baking soda in S1-2 is as follows:
[0015] Baking soda was placed in a grinder and ground for 10 minutes. Then, 1-3 wt% polyethylene glycol was added and the mixture was ground for another 20 minutes to obtain the modified baking soda.
[0016] Furthermore, the flue gas temperature in S1 is reduced to 130~180 ℃.
[0017] Furthermore, the temperature inside the dry deacidification reaction tower in S2 is 130~160 ℃.
[0018] Furthermore, the sodium hydroxide solution in S1-1 has a mass fraction of 10%.
[0019] Furthermore, in S1-2, the mass ratio of powder A to lime is 3:1.
[0020] Furthermore, the calcination time in S1-2 is 1.5 h.
[0021] Furthermore, in S1-3, powder B and modified sodium bicarbonate are mixed at a mass ratio of 1:(2~4).
[0022] Furthermore, the filter bags in the baghouse dust collector in S3 are made of temperature-resistant and corrosion-resistant PTFE + coated PTFE filter bag material.
[0023] Furthermore, the baking soda is ground in a grinder at a speed of 1000 r / min.
[0024] Natural zeolite is a hydrous aluminosilicate mineral of alkali or alkaline earth metals. Its interior is filled with channels and cavities, resulting in a large specific surface area. The unique crystal structure creates strong attractive forces, giving zeolite excellent adsorption properties. Modifying natural zeolite with sodium hydroxide solution allows the sodium hydroxide to chemically react with the silicate components, etching the zeolite surface, increasing its roughness and the number of pores, thereby significantly increasing the zeolite's surface area. This not only optimizes the zeolite's porous structure but also enhances its adsorption capacity for acidic flue gas.
[0025] Calcining zeolite in a muffle furnace at a suitable temperature effectively removes impurities such as moisture and organic matter from the pores and cavities of the zeolite, thereby improving the permeability of the pores and the specific surface area. Simultaneously, the calcination process causes some ions in the zeolite crystal structure to migrate, increasing its ion exchange capacity and further enhancing its activity. Adding an appropriate amount of lime powder before calcination and mixing thoroughly allows the lime powder to react with the silicate components on the zeolite surface at high temperatures. Some lime can enter the pores or cavities of the zeolite, forming a good bond with it. Zeolite utilizes its strong adsorption capacity to adsorb large amounts of acidic flue gas, while lime, with its excellent defluorination properties, reacts with fluoride ions on the zeolite surface or within the pores to generate calcium fluoride, thus achieving efficient defluorination. As a highly efficient adsorption carrier, zeolite can reduce the corrosion of subsequent treatment equipment by acidic components, extending its service life. Furthermore, zeolite is regenerable; through regeneration, its adsorption performance can be restored, enabling recycling and significantly reducing industrial costs.
[0026] The particle size and specific surface area of baking soda directly affect its contact area and reaction rate with acidic flue gas. Further refining the particle size of baking soda through grinding, specifically grinding commercially available baking soda powder into particles smaller than 300 mesh, is a more effective deacidifying agent. This significantly increases its specific surface area, thereby increasing the contact area and reaction opportunities with acidic flue gas, promoting improved deacidification performance, and facilitating gas flow to the dry deacidification reaction tower. Because baking soda is prone to deliquescence, leading to particle agglomeration and caking, polyethylene glycol (PEG) possesses excellent hygroscopic and film-forming properties, capable of adsorbing and fixing moisture on the surface of baking soda particles, preventing agglomeration and caking. Therefore, adding an appropriate amount of PEG to the baking soda during the grinding process allows PEG to form a protective film on the surface of the baking soda particles, enhancing its stability and dispersibility. The modified baking soda powder of this invention contains 1% to 3% PEG.
[0027] A deacidifying agent is prepared by grinding lime-loaded zeolite with modified baking soda using a grinding mill. The agent is then sieved through a 300-mesh sieve to ensure fine particle size and low moisture content. Combining lime-loaded zeolite with modified baking soda fully leverages their synergistic effect, effectively removing acidic gases and fluorides from flue gas using a dry deacidification process. This invention utilizes modified zeolite and lime. Zeolite's strong adsorption capacity adsorbs large amounts of halogens and fluoride ions from acidic flue gas. Simultaneously, the lime loaded on the zeolite reacts with fluoride ions to form calcium fluoride, achieving highly efficient defluorination. Baking soda, with its alkaline properties, reacts with the acidic flue gas to further remove halogens and fluoride ions. This combination not only improves dehalogenation and defluorination performance but also achieves environmental and social benefits such as energy saving and emission reduction, while simultaneously improving the economic benefits of operating enterprises, demonstrating excellent practicality.
[0028] The baghouse dust collector uses high-temperature and corrosion-resistant PTFE + membrane-coated PTFE filter bags, which have excellent chemical corrosion resistance and can effectively resist the erosion of corrosive components in flue gas under high-temperature environments, extending the service life of the filter bags. The PTFE baghouse dust collector also has good filtration efficiency, effectively filtering out fine particulate matter. Its smooth surface does not easily attract dust, resulting in low filtration resistance, which helps reduce the energy consumption of the dust collection system while maintaining high filtration efficiency. Furthermore, because the PTFE surface does not easily attract dust, the cleaning process is smoother, reducing the frequency of cleaning and simplifying maintenance. Regular cleaning is sufficient to effectively prevent a decrease in dust collection accuracy and extend the service life.
[0029] The beneficial effects of this invention are:
[0030] Modification of natural zeolite with sodium hydroxide solution significantly optimized its pore structure and enhanced its adsorption capacity for acidic flue gas. Calcination of the zeolite in a muffle furnace removed adsorbed moisture, further increasing its specific surface area and adsorption activity. Lime reacted with the silicate components on the zeolite surface at high temperature, allowing some lime to enter the pores or cavities and form a good bond with the zeolite. The zeolite utilizes its strong adsorption capacity to adsorb large amounts of acidic flue gas, while lime, with its excellent defluorination properties, reacts with fluoride ions on the zeolite surface or within its pores to generate calcium fluoride, achieving highly efficient defluorination.
[0031] (2) By refining the particle size of baking soda through grinding, its specific surface area is increased, which significantly improves the contact and reaction efficiency with acidic flue gas and enhances the deacidification capacity. Adding an appropriate amount of polyethylene glycol stabilizes the baking soda and enhances its dispersibility by absorbing moisture and forming a film. Combined with lime-loaded zeolite, the strong adsorption force of zeolite is used to capture halogen and fluoride ions, while baking soda and lime exert alkalinity and reactivity to efficiently remove these harmful ions. Detailed Implementation
[0032] To further illustrate the technical means and effects of the present invention in achieving its intended purpose, the following detailed description of the specific implementation methods, structures, features, and effects of the present invention, in conjunction with embodiments, is provided below.
[0033] Example 1
[0034] A desulfurization process for flue gas containing high levels of chlorofluorocarbons (CFCs), the process flow of which is as follows:
[0035] S1: The incineration flue gas is introduced into the flue gas quench tower and atomized cooling water is sprayed in to rapidly reduce the flue gas temperature to 155 ℃ within 1.0 s, and to control the cooling water condensation in the tower.
[0036] S2: The flue gas after rapid cooling enters the dry deacidification reaction tower. The temperature inside the dry deacidification reaction tower is 145 ℃. The deacidification agent is added to the dry deacidification reaction tower by airflow to react with acidic substances such as HCl, SO2, and HF in the flue gas to remove acid.
[0037] The deacidifying agent is prepared as follows:
[0038] S1-1: Add 10 parts by weight of natural zeolite to 90 parts by weight of sodium hydroxide solution, stir for 24 h, wash 3 times with deionized water of the same mass as the zeolite, and then dry in a vacuum drying oven at 60 ℃ for 12 h to obtain powder A.
[0039] S1-2: Mix powder A and lime powder evenly at a mass ratio of 3:1, and place them together in a muffle furnace for roasting at a roasting temperature of 500 ℃ for 1.5 h. Cool to room temperature at a rate of 5 ℃ / min to obtain powder B.
[0040] S1-3: Mix powder B and modified baking soda at a mass ratio of 1:3, grind in a grinder for 30 min at a grinding speed of 800 r / min, and then pass through a 300-mesh sieve to obtain the deacidifying agent;
[0041] S3: The flue gas after deacidification in the dry deacidification reaction tower is further purified by a bag filter. The filter bags are made of temperature-resistant and corrosion-resistant PTFE + membrane PTFE material, which captures dust and excess deacidifying agent in the flue gas and further removes residual acidic substances at the interface of the bag filter. The purified flue gas meets the emission standards and is discharged through the top of the filter bag support plate.
[0042] The preparation method of the modified baking soda in S1-2 is as follows:
[0043] Baking soda was placed in a grinder and ground for 10 minutes. Then, 2 wt% polyethylene glycol was added and the grinding continued for 20 minutes at a speed of 1000 r / min to obtain the modified baking soda.
[0044] Example 2
[0045] A desulfurization process for flue gas containing high levels of chlorofluorocarbons (CFCs), the process flow of which is as follows:
[0046] S1: The incineration flue gas is introduced into the flue gas quench tower and atomized cooling water is sprayed in to rapidly reduce the flue gas temperature to 130 ℃ within 1.0 s, and to control the cooling water condensation in the tower.
[0047] S2: The flue gas after rapid cooling enters the dry deacidification reaction tower. The temperature inside the dry deacidification reaction tower is 130 ℃. The deacidification agent is added to the dry deacidification reaction tower by airflow to react with acidic substances such as HCl, SO2, and HF in the flue gas to remove acid.
[0048] The deacidifying agent is prepared as follows:
[0049] S1-1: Add 10 parts by weight of natural zeolite to 90 parts by weight of sodium hydroxide solution, stir for 24 h, wash 3 times with deionized water of the same mass as the zeolite, and then dry in a vacuum drying oven at 60 ℃ for 12 h to obtain powder A.
[0050] S1-2: Mix powder A and lime at a mass ratio of 3:1, place them together in a muffle furnace for roasting at a temperature of 400 ℃ for 1.5 h, and cool to room temperature at a rate of 5 ℃ / min to obtain powder B;
[0051] S1-3: Mix powder B and modified baking soda at a mass ratio of 1:2, grind in a grinder for 30 min at a grinding speed of 800 r / min, and then pass through a 300-mesh sieve to obtain the deacidifying agent;
[0052] S3: The flue gas after deacidification in the dry deacidification reaction tower is further purified by a bag filter. The filter bags are made of temperature-resistant and corrosion-resistant PTFE + membrane PTFE material, which captures dust and excess deacidifying agent in the flue gas and further removes residual acidic substances at the interface of the bag filter. The purified flue gas meets the emission standards and is discharged through the top of the filter bag support plate.
[0053] The preparation method of the modified baking soda in S1-2 is as follows:
[0054] Baking soda was placed in a grinder and ground for 10 minutes. Then, 1 wt% polyethylene glycol was added and the grinding continued for 20 minutes at a speed of 1000 r / min to obtain the modified baking soda.
[0055] Example 3
[0056] A desulfurization process for flue gas containing high levels of chlorofluorocarbons (CFCs), the process flow of which is as follows:
[0057] S1: The incineration flue gas is introduced into the flue gas quench tower, and atomized cooling water is sprayed in to rapidly reduce the flue gas temperature to 180 ℃ within 1.0 s, and to control the cooling water condensation in the tower.
[0058] S2: The flue gas after rapid cooling enters the dry deacidification reaction tower. The temperature inside the dry deacidification reaction tower is 160 ℃. The deacidification agent is added to the dry deacidification reaction tower by airflow to react with acidic substances such as HCl, SO2, and HF in the flue gas to remove acid.
[0059] The deacidifying agent is prepared as follows:
[0060] S1-1: Add 10 parts by weight of natural zeolite to 90 parts by weight of sodium hydroxide solution, stir for 24 h, wash 3 times with deionized water of the same mass as the zeolite, and then dry in a vacuum drying oven at 60 ℃ for 12 h to obtain powder A.
[0061] S1-2: Mix powder A and lime powder evenly at a mass ratio of 3:1, place them in a muffle furnace for roasting at a temperature of 600 ℃ for 1.5 h, and cool them to room temperature at a rate of 5 ℃ / min to obtain powder B.
[0062] S1-3: Mix powder B and modified baking soda at a mass ratio of 1:4, grind in a grinder for 30 min at a grinding speed of 800 r / min, and then pass through a 300-mesh sieve to obtain the deacidifying agent;
[0063] S3: The flue gas after deacidification in the dry deacidification reaction tower is further purified by a bag filter. The filter bags are made of temperature-resistant and corrosion-resistant PTFE + membrane PTFE material, which captures dust and excess deacidifying agent in the flue gas and further removes residual acidic substances at the interface of the bag filter. The purified flue gas meets the emission standards and is discharged through the top of the filter bag support plate.
[0064] The preparation method of the modified baking soda in S1-2 is as follows:
[0065] Baking soda was placed in a grinder and ground for 10 minutes. Then, 3 wt% polyethylene glycol was added and the grinding continued for 20 minutes at a speed of 1000 r / min to obtain the modified baking soda.
[0066] Comparative Example 1
[0067] In the preparation of the deacidifying agent, the sodium bicarbonate is not modified, and the remaining steps are the same as in Example 1.
[0068] Comparative Example 2
[0069] The preparation of the deacidifying agent does not include step S1-1; the remaining steps are the same as in Example 1.
[0070] Comparative Example 3
[0071] The deacidifying agent is prepared without a muffle furnace roasting step; the remaining steps are the same as in Example 1.
[0072] Deacidification performance test:
[0073] The dehalogenation efficiency and defluorination efficiency in the examples and comparative examples were determined by ion chromatography, and the experimental data are recorded in the table below.
[0074] Dehalogenation efficiency (%) Defluorination efficiency (%) Example 1 94.6% 92.5% Example 2 93.1% 91.2% Example 3 93.5% 91.8% Comparative Example 1 85.1% 89.5% Comparative Example 2 91.4% 90.1% Comparative Example 3 89.6% 88.4%
[0075] As can be seen from the examples and comparative data, the deacidifying agent prepared by the present invention has excellent flue gas deacidification efficiency.
[0076] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.
Claims
1. A desulfurization treatment process for flue gas containing high levels of fluorine and chlorine, characterized in that, The deacidification process flow is as follows. S1: The incineration flue gas is introduced into the flue gas quench tower and atomized cooling water is sprayed in to rapidly reduce the flue gas temperature to below 200 ℃ within 1.0 s, and the cooling water is controlled to prevent condensation in the tower. S2: The flue gas after rapid cooling enters the dry deacidification reaction tower. The deacidification agent is added to the dry deacidification reaction tower by airflow, and reacts with acidic substances such as HCl, HF, and SO2 in the flue gas to remove acid. The deacidifying agent is prepared as follows: S1-1: Add 10 parts by weight of natural zeolite to 90 parts by weight of sodium hydroxide solution, stir for 24 h, wash 3 times with deionized water of the same mass as the zeolite, and then dry in a vacuum drying oven at 60 ℃ for 12 h to obtain powder A. S1-2: Mix powder A and lime powder evenly, place them in a muffle furnace for roasting at a temperature of 400~600 ℃, and cool them to room temperature at a rate of 5 ℃ / min to obtain powder B; S1-3: Mix powder B and modified baking soda, grind in a grinder for 30 min at a grinding speed of 800 r / min, and then pass through a 300-mesh sieve to obtain the deacidifying agent; S3: The flue gas after deacidification in the dry deacidification reaction tower is further purified by a bag filter to capture dust and excess deacidification agent in the flue gas, and further remove residual acidic substances at the interface of the bag filter. The purified flue gas meets the emission standards and is discharged above the filter bag support plate.
2. The desulfurization process for flue gas containing high levels of fluorine and chlorine according to claim 1, characterized in that, The preparation method of the modified baking soda in S1-2 is as follows: Baking soda was placed in a grinder and ground for 10 minutes. Then, 1-3 wt% polyethylene glycol was added and the mixture was ground for another 20 minutes to obtain the modified baking soda.
3. The desulfurization process for flue gas containing high levels of fluorine and chlorine according to claim 1, characterized in that, In S1, the flue gas temperature is reduced to 130~180 ℃.
4. The desulfurization process for flue gas containing high levels of fluorine and chlorine according to claim 1, characterized in that, The temperature inside the dry deacidification reaction tower in S2 is 130~160 ℃.
5. The desulfurization process for flue gas containing high levels of fluorine and chlorine according to claim 1, characterized in that, The sodium hydroxide solution in S1-1 has a mass fraction of 10%.
6. The desulfurization process for flue gas containing high levels of fluorine and chlorine according to claim 1, characterized in that, In S1-2, the mass ratio of powder A to lime is 3:
1.
7. The desulfurization process for flue gas containing high levels of fluorine and chlorine according to claim 1, characterized in that, The roasting time in S1-2 is 1.5 h.
8. The desulfurization process for flue gas containing high levels of fluorine and chlorine according to claim 1, characterized in that, In S1-3, powder B and modified baking soda are mixed at a mass ratio of 1:(2~4).
9. The desulfurization process for flue gas containing high levels of fluorine and chlorine according to claim 1, characterized in that, The filter bags in the baghouse dust collector in S3 are made of temperature-resistant and corrosion-resistant PTFE + coated PTFE filter bag material.
10. The desulfurization process for flue gas containing high levels of fluorine and chlorine according to claim 2, characterized in that, The baking soda was ground in a grinder at a speed of 1000 r / min.