Waste incineration flue gas deacidification agent and preparation method thereof

Abstract

The invention discloses a waste incineration flue gas deacidification agent and a preparation method thereof, and belongs to the technical field of flue gas deacidification agents. The raw materials of the deacidification agent comprise quicklime, a surfactant, a dispersant, an accelerant, an absorbent, water vapor and a lubricant, the accelerant is selected from one or more of sodium hydroxide, sodium carbonate and sodium silicate, and the absorbent is selected from one or more of calcium chloride and magnesium chloride; the mass ratio of the quick lime to the surfactant to the dispersing agent to the accelerant to the absorbent to the water vapor is 100: (1-3): (1-2): (5-10): (5-10): (105-125). The preparation method disclosed by the invention is simple in preparation process flow, high in deacidification efficiency of the deacidification agent, wide in application range and suitable for deacidification only by a dry process and a wide temperature range of 150-1000 DEG C.

Description

Technical Field

[0001] This invention belongs to the technical field of flue gas deacidification agents, specifically relating to a waste incineration flue gas deacidification agent and its preparation method. Background Technology

[0002] Waste incineration generates large amounts of flue gas containing acidic gases such as sulfur dioxide (SO2) and hydrogen chloride (HCl). These pollutants must be effectively treated to meet emission standards. Currently, waste-to-energy plants commonly use a "semi-dry + dry" process to treat acidic gases, but this suffers from problems such as large fly ash production and low reaction efficiency. Therefore, a simplified acid removal process is urgently needed to reduce operating costs while ensuring that pollutants meet emission standards.

[0003] Calcium-based absorbents are widely used in flue gas purification due to their wide availability and low cost. However, traditional calcium-based absorbents suffer from problems such as low reactivity and low calcium utilization.

[0004] CN116688745A discloses a combined desulfurizing agent comprising calcium-based composite metal oxides (zinc oxide, zirconium oxide, and cerium oxide) that act as catalysts. This combined desulfurizing agent is added to the high-temperature section of a waste incineration system, while a solubilizing agent is added to the lime slurry preparation tank in the desulfurization reaction tower. However, this invention has high preparation costs and requires the addition of agents during lime slurry preparation, failing to solve the problem of high fly ash generation associated with the semi-dry method.

[0005] CN120346776A discloses a modified calcium hydroxide for enhanced desulfurization and its preparation method. The method involves modifying calcium hydroxide with a mixed organic acid, adding an absorbent agent and nanofiller, and then obtaining modified calcium hydroxide powder through stirring, drying, grinding, and sieving. Finally, an organic amine is added to obtain the modified calcium hydroxide powder with enhanced desulfurization effect. However, its preparation process is complex and unsuitable for industrial production. Furthermore, current desulfurization agents in the waste incineration field only target desulfurization, while waste incineration flue gas often has a high HCl content, resulting in low desulfurization efficiency when removing both SO2 and HCl.

[0006] Therefore, it is of great significance to develop a deacidifying agent that can simultaneously and efficiently remove SO2 and HCl, and that has a simple process and low cost. Summary of the Invention

[0007] Technical problem solved: In view of the above-mentioned technical problems, the present invention provides a deacidifying agent for waste incineration flue gas and its preparation method. The preparation process is simple, the deacidifying agent has high deacidification efficiency, and a wide range of applications. It is suitable for dry deacidification processes only and a wide temperature range of 150~1000℃.

[0008] Technical solution: A deacidifying agent for waste incineration flue gas, the raw materials of which include quicklime, surfactant, dispersant, accelerator, absorbent, steam and lubricant, wherein the accelerator is selected from one or more of sodium hydroxide, sodium carbonate and sodium silicate, and the absorbent is selected from one or more of calcium chloride and magnesium chloride; the mass ratio of quicklime, surfactant, dispersant, accelerator, absorbent and steam is 100:(1~3):(1~2):(5~10):(5~10):(105~125).

[0009] Preferably, the surfactant is selected from one or more of sodium dodecyl sulfate, sodium linear alkylbenzene sulfonate, and tea saponin.

[0010] Preferably, the dispersant is selected from one or more of sodium tripolyphosphate, sodium hexametaphosphate, and sodium polyacrylate.

[0011] Preferably, the lubricant is selected from one or more of silica, diatomaceous earth, talc and calcium stearate, and the mass of the lubricant is 0.5 to 3% of the total mass of the deacidifying agent.

[0012] Preferably, the quicklime has a CaO content of ≥95% and a particle size of 1~5mm.

[0013] A method for preparing a deacidifying agent for waste incineration flue gas includes the following steps: S1. Pretreatment: Quicklime is crushed to obtain quicklime granules; S2. Superheated steam activation and digestion: Quicklime granules, surfactants, dispersants, accelerators, and absorbents are sprayed into a fluidized bed, while steam is introduced for digestion treatment. S3. Secondary maturation: The digested material is left to stand and mature. S4. Drying and sorting: Drying and sorting the matured material to obtain semi-finished material; S5. Mixing: Lubricant is added to the semi-finished material and mixed to obtain the finished deacidifying agent.

[0014] Preferably, in step S2, the temperature of the water vapor is 150~250℃, the pressure is 0.5~1.2MPa, and the digestion time is 10~30min.

[0015] Preferably, in step S3, the relative humidity of the ripening reaction is 60-90%, the temperature is 80-110℃, and the time is 0.5-1.5h.

[0016] Preferably, in step S4, airflow drying is used to dry the material to a moisture content of <2%, the drying temperature is 110~130℃, and the particle size is sorted to 3~50μm as a semi-finished product.

[0017] Preferably, in step S5, the lubricant is incorporated for 5-15 minutes, the mixing temperature is 60-80°C, and the mixing time is 30-45 minutes.

[0018] Beneficial effects: The preparation process of this invention is simple and the preparation time is short. It can be directly injected into the flue using pneumatic conveying, making it a supporting process for waste incineration power plants and reducing operating costs. The deacidifying agent of this invention has high deacidification efficiency, can achieve dry process only to ensure that acidic gas emissions meet the standards, shorten the flue gas purification process, and reduce the amount of fly ash in the waste incineration system; The deacidifying agent of this invention has a wide range of applications and can simultaneously and efficiently remove SO2 and HCl. The reaction temperature is 150~1000℃. It can be sprayed into multiple places such as furnace, tail flue, and horizontal flue, and the spraying position can be flexibly selected according to the actual situation. Detailed Implementation

[0019] The present invention will be further described below with reference to specific embodiments.

[0020] Comparison and performance testing methods: Performance testing methods: The performance of the deacidifying agent was tested in a laboratory electrically heated stainless steel reactor. SO2 and HCl were introduced from the bottom of the reactor via gas cylinders, diluted using N2 as an inert atmosphere, and the concentrations of SO2 and HCl were controlled to the required ranges. The deacidifying agent was added from the top of the reactor through a micro-screw, with the temperature controlled at 240℃. The SO2 and HCl concentrations at the outlet were detected using a flue gas analyzer. The simulated flue gas SO2 and HCl concentrations were stabilized at 500 ppm and 300 ppm, respectively. After the deacidifying agent was added and the emissions stabilized, the removal efficiency of SO2 and HCl was recorded.

[0021] Comparative example: Take 5 kg of high-purity quicklime (CaO mass fraction ≥95%) and crush it to 1-3 mm. Treat it with superheated steam at 200℃ and 0.5 MPa for 18 minutes. Simultaneously, spray an aqueous solution containing 100 g of sodium dodecyl sulfate and 75 g of sodium hexametaphosphate into the steam inlet. Subsequently, slake it at 90℃ and 80% humidity for 1 hour, dry it at 120℃, pulverize it, and then add 1.5% of silica by weight of the finished product and mix thoroughly.

[0022] Test results: Specific surface area: 40.5 m² 2 / g; SO2 removal efficiency: 76%; HCl removal efficiency: 80%. Example 1

[0023] The preparation method in this embodiment is the same as that in the comparative example, except that 250g of sodium hydroxide (5% of the mass of quicklime) is added to the composite additive.

[0024] Test results: Specific surface area: 39.0 m² 2 / g; SO2 removal efficiency: 82%; HCl removal efficiency: 83%. Example 2

[0025] The preparation method in this embodiment is the same as that in the comparative example, except that 375g of sodium hydroxide (7.5% of the mass of quicklime) is added to the composite additive.

[0026] Test results: Specific surface area: 39.8 m² 2 / g; SO2 removal efficiency: 85%; HCl removal efficiency: 95%. Example 3

[0027] The preparation method in this embodiment is the same as that in the comparative example, except that 500g of sodium hydroxide (10% of the mass of quicklime) is added to the composite additive.

[0028] Test results: Specific surface area: 41.2 m² 2 / g; SO2 removal efficiency: 90%; HCl removal efficiency: 97%. Example 4

[0029] The preparation method in this embodiment is the same as that in the comparative example, except that 396g of sodium carbonate (equimolar amount of Na as in Example 2) is added to the composite additive.

[0030] Test results: Specific surface area: 40.0 m² 2 / g; SO2 removal efficiency: 83%; HCl removal efficiency: 93%. Example 5

[0031] The preparation method in this embodiment is the same as in embodiment 2, except that 250g of anhydrous calcium chloride (5% of the mass of quicklime) is added to the composite additive.

[0032] Test results: Specific surface area: 40.1 m² 2 / g; SO2 removal efficiency: 88%; HCl removal efficiency: 98%.

[0033] Compared with Example 2, the removal efficiency of SO2 and HCl was improved, demonstrating the promoting effect of the "quasi-liquid phase" environment created by the absorbent as a hygroscopic component on the reaction. Example 6

[0034] The preparation method in this embodiment is the same as in embodiment 2, except that 250g of anhydrous magnesium chloride (5% of the mass of quicklime) is also added to the composite additive.

[0035] Test results: Specific surface area: 41.0 m² 2 / g; SO2 removal efficiency: 90%; HCl removal efficiency: 97%.

[0036] This embodiment has the same effect as Example 5, indicating that magnesium chloride and calcium chloride have similar hygroscopic effects. Example 7

[0037] The preparation method in this embodiment is the same as that in the comparative example, except that 250g of anhydrous calcium chloride (5% of the mass of quicklime) is added to the composite additive.

[0038] Test results: Specific surface area: 38.9 m² 2 / g; SO2 removal efficiency: 75%; HCl removal efficiency: 82%.

[0039] Compared to the comparative example, the HCl removal efficiency in this embodiment is slightly improved; however, compared to the combined use of an accelerator (sodium-based active component) and absorbent (anhydrous calcium chloride hygroscopic component) in Example 5, the improvement effect is far less, indicating that there is a synergistic effect between the accelerator and the absorbent, and their combined use can effectively improve the deacidification efficiency.

[0040] Engineering Application Test 1: The desulfurization agent obtained in Example 5 was tested in an engineering application. In a 300t / d waste-to-energy incineration plant, the desulfurization agent was sprayed into the horizontal flue using six spray guns, with a flue gas volume of 50,000 Nm³. 3 / h, the initial SO2 concentration was 210 mg / Nm 3 The initial concentration of HCl was 500 mg / Nm³. 3 The reaction temperature was approximately 150℃. After 24 hours of continuous operation, the flue gas pollutants were monitored, and the SO2 concentration was between 15 and 31 mg / Nm³. 3 The concentration of HCl varies from 5 to 10 mg / Nm³. 3 The desulfurization efficiency was greater than 85%, and the dechlorination efficiency was greater than 98%. Simultaneously, a long-term stable operation test was conducted for 30 days, during which the pipeline remained unblocked and the operation was in good condition.

[0041] Engineering Application Test 2: The deacidifying agent obtained in Example 5 was tested in an engineering application. In a 750t / d waste-to-energy incineration plant, the deacidifying agent was sprayed into a flue in the boiler furnace using spray guns. There were three layers of spray guns: six on the front wall and three on each of the left and right walls of each layer. The flue gas volume was 130,000 Nm³. 3 / h, the initial SO2 concentration was 196 mg / Nm 3 The initial concentration of HCl was 227 mg / Nm³. 3 The reaction temperature is 850-1000℃. After 24 hours of continuous operation, the flue gas pollutants are monitored, with SO2 concentrations ranging from 10 to 28 mg / Nm³. 3The concentration of HCl varies from 3 to 9 mg / Nm³. 3 The desulfurization efficiency was greater than 85%, and the dechlorination efficiency was greater than 96%. Simultaneously, a long-term stable operation test was conducted for 14 days. During the operation, the pipeline remained unblocked, and the operation was in good condition.

Claims

1. A deacidifying agent for waste incineration flue gas, characterized in that, The raw materials of the deacidifying agent include quicklime, surfactant, dispersant, accelerator, absorbent, steam and lubricant. The accelerator is selected from one or more of sodium hydroxide, sodium carbonate and sodium silicate. The absorbent is selected from one or more of calcium chloride and magnesium chloride. The mass ratio of quicklime, surfactant, dispersant, accelerator, absorbent and steam is 100:(1~3):(1~2):(5~10):(5~10):(105~125).

2. The waste incineration flue gas deacidification agent according to claim 1, characterized in that, The surfactant is selected from one or more of sodium dodecyl sulfate, sodium linear alkylbenzene sulfonate, and tea saponin.

3. The waste incineration flue gas deacidification agent according to claim 1, characterized in that, The dispersant is selected from one or more of sodium tripolyphosphate, sodium hexametaphosphate, and sodium polyacrylate.

4. The waste incineration flue gas deacidification agent according to claim 1, characterized in that, The lubricant is selected from one or more of silica, diatomaceous earth, talc and calcium stearate, and the mass of the lubricant is 0.5 to 3% of the total mass of the deacidifying agent.

5. The waste incineration flue gas deacidification agent according to claim 1, characterized in that, The quicklime has a CaO content of ≥95% and a particle size of 1~5mm.

6. The method for preparing a waste incineration flue gas desulfurization agent according to claim 1, characterized in that, The steps include the following: S1. Pretreatment: Quicklime is crushed to obtain quicklime granules; S2. Superheated steam activation and digestion: Quicklime granules, surfactants, dispersants, accelerators, and absorbents are sprayed into a fluidized bed, while steam is introduced for digestion treatment. S3. Secondary maturation: The digested material is left to stand and mature. S4. Drying and sorting: Drying and sorting the matured material to obtain semi-finished material; S5. Mixing: Lubricant is added to the semi-finished material and mixed to obtain the finished deacidifying agent.

7. The method for preparing a waste incineration flue gas desulfurization agent according to claim 6, characterized in that, In step S2, the temperature of the steam is 150~250℃, the pressure is 0.5~1.2MPa, and the digestion time is 10~30min.

8. The method for preparing a waste incineration flue gas desulfurization agent according to claim 6, characterized in that, In step S3, the relative humidity of the ripening reaction is 60-90%, the temperature is 80-110℃, and the time is 0.5-1.5h.

9. The method for preparing a waste incineration flue gas deacidifying agent according to claim 6, characterized in that, In step S4, airflow drying is used to dry the material to a moisture content of <2%, the drying temperature is 110~130℃, and the particle size is sorted to 3~50μm as semi-finished material.

10. The method for preparing a waste incineration flue gas desulfurization agent according to claim 6, characterized in that, In step S5, the lubricant is incorporated in 5-15 minutes, the mixing temperature is 60-80°C, and the mixing time is 30-45 minutes.