Semi-dry desulfurizer for industrial flue gas and preparation method of semi-dry desulfurizer

Abstract

The invention provides an industrial flue gas semi-dry desulfurizer and a preparation method thereof, and belongs to the technical field of flue gas desulfurization, the desulfurizer is prepared from the following raw materials: quicklime, a moisture absorbent, a phase transfer catalyst and a dispersant; the mass of the moisture absorbent is 1-5% of that of the quick lime; the mass of the phase transfer catalyst is 1-5% of that of the quick lime; the mass of the dispersing agent is 1-3% of that of the quick lime. According to the invention, the problems in the prior art that the reaction rate is slow, the desulfurization efficiency is low and the existing emission requirements cannot be met when the traditional desulfurizer is used for absorbing SO2 can be solved.

Description

Technical Field

[0001] The present invention relates to the technical field of flue gas desulfurization, and more specifically, to an industrial flue gas semi-dry desulfurizer and a preparation method thereof. Background Art

[0002] The iron and steel industry and coal-fired power plants are one of the main sources of sulfur dioxide (SO2) emissions. Due to the presence of sulfur in fuels and high-temperature reaction conditions, a large amount of SO2 is discharged into the atmosphere through flue gas. This kind of emission not only causes the formation of acid rain, but also has a negative impact on human health and the environment.

[0003] The semi-dry desulfurization technology has been widely used in the industrial field due to its advantages in reducing energy consumption and by-product generation. However, with the implementation of more stringent ultra-low emission standards, the existing semi-dry desulfurization technology faces challenges in the removal efficiency of SO2.

[0004] The currently used traditional desulfurizer has a slow reaction rate and low desulfurization efficiency when absorbing SO2, and cannot meet the current emission requirements. Summary of the Invention

[0005] In view of the above problems, the purpose of the present invention is to provide an industrial flue gas semi-dry desulfurizer and a preparation method thereof, so as to solve the problems in the prior art that the traditional desulfurizer has a slow reaction rate, low desulfurization efficiency and cannot meet the current emission requirements when absorbing SO2.

[0006] The present invention provides an industrial flue gas semi-dry desulfurizer, which is prepared from the following raw materials: quicklime, hygroscopic agent, phase transfer catalyst, dispersant, water; wherein,

[0007] The mass of the hygroscopic agent is 1-5% of the mass of the quicklime;

[0008] The mass of the phase transfer catalyst is 1-5% of the mass of the quicklime;

[0009] The mass of the dispersant is 1-3% of the mass of the quicklime;

[0010] The mass ratio of water to quicklime is 8:1.

[0011] In addition, preferably, the purity of the quicklime is not less than 93%, the effective calcium content is at least 90%, the activity is above 360, T 60 <1 minute.

[0012] In addition, preferably, the hygroscopic agent is at least one of magnesium sulfate, calcium chloride, magnesium chloride, potassium sulfate, sodium sulfate, sodium chloride, potassium chloride or at least two of them mixed in any proportion.

[0013] In addition, preferably, the phase transfer catalyst is sodium citrate or adipic acid or a mixture of sodium citrate and adipic acid in any ratio.

[0014] In addition, preferably, the dispersant is polyethylene glycol.

[0015] The present invention also provides a preparation method of the semi-dry flue gas desulfurizer as described above, comprising the following steps:

[0016] Weigh quicklime, a moisture absorbent, a phase transfer catalyst, a dispersant and water;

[0017] Divide the moisture absorbent into a premixed section moisture absorbent and a water bath section moisture absorbent; divide the phase transfer catalyst into a premixed section phase transfer catalyst and a water bath section phase transfer catalyst;

[0018] Mix the quicklime, the premixed section moisture absorbent and the premixed section phase transfer catalyst evenly to form a mixed material;

[0019] Add the dispersant to water, and then add the mixed material to obtain a mixed material to be reacted;

[0020] Place the mixed material to be reacted in a water bath heating environment, and under the condition of 65 °C to 85 °C, stir, and add the water bath section moisture absorbent and the water bath section phase transfer catalyst during the stirring process to make the mixed material to be reacted completely react to obtain a slurry;

[0021] Lay the slurry flat and carry out drying treatment to obtain a dried sample;

[0022] Grind and sieve the sample to obtain a desulfurizer.

[0023] In addition, preferably, the ratio of the premixed section moisture absorbent to the water bath section moisture absorbent is 1:1;

[0024] The ratio of the premixed section phase transfer catalyst to the water bath section phase transfer catalyst is 1:1.

[0025] In addition, preferably, stir the mixed material to be reacted with a magnetic stirrer or a mechanical stirrer for at least 1 hour; the stirring speed is 750 rpm to 1250 rpm;

[0026] The water bath section moisture absorbent and the water bath section phase transfer catalyst are added simultaneously.

[0027] In addition, preferably, during the process of laying the slurry flat and carrying out drying treatment to obtain a dried sample, lay the slurry in a container and dry it in an oven at 200 °C to 250 °C for 3 h.

[0028] In addition, a preferred solution is that, in the process of grinding and sieving the sample to obtain the desulfurizer, after grinding and sieving the sample through a 40-60 mesh sieve, the desulfurizer is obtained.

[0029] As can be seen from the above technical solution, the industrial flue gas semi-dry desulfurizer and preparation method provided by the present invention use quicklime, a hygroscopic agent, a phase transfer catalyst, and a dispersant as raw materials. The main component of the prepared desulfurizer is Ca(OH)2. When SO2 in the flue gas reacts with Ca(OH)2, the hygroscopic agent component in the desulfurizer enhances the hygroscopicity of the desulfurizer, effectively promoting the dissolution of SO2 on the surface of the desulfurizer, thereby providing a more sufficient reaction medium for the chemical reaction between SO2 and Ca(OH)2; the introduction of moisture not only prolongs the contact time between SO2 and the desulfurizer, but also expands the reaction surface area, further improving the desulfurization efficiency. By adding the hygroscopic agent, the desulfurization efficiency of the desulfurizer is increased by more than 10%, and at the same time, the stability of the desulfurization process is improved;

[0030] The component of the phase transfer catalyst in the desulfurizer can reduce the resistance at the gas-liquid interface, making it easier for SO2 to pass through the gas-liquid interface and quickly dissolve in the water film on the surface of the desulfurizer. By reducing the interfacial energy, the phase transfer catalyst accelerates the dissolution and mass transfer process of SO2, enabling it to quickly transfer to the liquid phase and participate in the chemical reaction. This process significantly improves the reaction rate between SO2 and Ca(OH)2. Especially in the semi-dry desulfurization process, when the moisture is limited, the phase transfer catalyst can effectively make up for this deficiency and enhance the reaction efficiency of the desulfurizer; in addition, the phase transfer catalyst can also reduce the reaction time and the usage amount of the desulfurizer, thereby reducing the overall desulfurization cost;

[0031] In summary, the present invention can improve the moisture retention ability of the desulfurizer, extend the effective use time of the desulfurizer, avoid premature failure, improve the reaction stability, and significantly extend the breakthrough time, ensuring that the desulfurization system can maintain a high desulfurization effect for a longer time, thereby improving the overall stability and continuous operation ability of the system.

[0032] To achieve the above and related purposes, one or more aspects of the present invention include the features that will be described in detail later. The following description and the accompanying drawings illustrate certain exemplary aspects of the present invention in detail. However, these aspects only indicate some of the various ways in which the principles of the present invention can be used. In addition, the present invention aims to include all these aspects and their equivalents. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] By referring to the following description in conjunction with the accompanying drawings, and with a more comprehensive understanding of the present invention, other objects and results of the present invention will become more apparent and easier to understand.

[0034] Figure 1Flow chart of the semi-dry desulfurizer method for industrial flue gas according to an embodiment of the present invention;

[0035] Figure 2 Schematic diagram of the action principle of the semi-dry desulfurizer for industrial flue gas according to an embodiment of the present invention;

[0036] Figure 3 Diagram showing the effect of different moisture absorbents on the semi-dry desulfurizer for industrial flue gas according to an embodiment of the present invention;

[0037] Figure 4 SO2 breakthrough curve of the semi-dry desulfurizer for industrial flue gas prepared by using different moisture absorbents as raw materials according to an embodiment of the present invention; wherein, to ensure the reliability of the data, the desulfurization test of each sample was repeated three times, that is, the three curves of different colors in each figure. Detailed implementation manners

[0038] In the following description, for the purpose of illustration, in order to provide a comprehensive understanding of one or more embodiments, many specific details are set forth. However, it is obvious that these embodiments can also be implemented without these specific details.

[0039] Aiming at the problems in the prior art mentioned above, that is, the traditional desulfurizer used has a slow reaction rate, low desulfurization efficiency, and cannot meet the current emission requirements when absorbing SO2, a semi-dry desulfurizer for industrial flue gas and a preparation method thereof are proposed.

[0040] The following will describe in detail the specific embodiments of the present invention with reference to the accompanying drawings.

[0041] In order to illustrate the semi-dry desulfurizer for industrial flue gas and the preparation method provided by the present invention, Figure 1 shows the flow of the semi-dry desulfurizer method for industrial flue gas according to an embodiment of the present invention; Figure 2 shows the action principle of the semi-dry desulfurizer for industrial flue gas according to an embodiment of the present invention; Figure 3 shows the effect of different moisture absorbents on the semi-dry desulfurizer for industrial flue gas according to an embodiment of the present invention; Figure 4 shows the SO2 breakthrough curve of the semi-dry desulfurizer for industrial flue gas prepared by using different moisture absorbents as raw materials according to an embodiment of the present invention.

[0042] As Figures 1 to 4 collectively shown, the semi-dry desulfurizer for industrial flue gas provided by the present invention is prepared from the following raw materials: quicklime, moisture absorbent, phase transfer catalyst, dispersant, water; wherein,

[0043] The mass of the moisture absorbent is 1-5% of the mass of the quicklime;

[0044] The mass of the phase transfer catalyst is 1-5% of the mass of the quicklime;

[0045] The mass of the dispersant is 1-3% of the mass of quicklime;

[0046] The mass ratio of water to quicklime is 8:1.

[0047] As a preferred embodiment of the present invention, the purity of quicklime is not less than 93%, the effective calcium content is at least 90%, the activity is above 360, and T 60 <1 minute.

[0048] Among them, T 60 refers to the time required for the temperature of quicklime to rise to 60°C after adding water.

[0049] As a preferred embodiment of the present invention, the moisture absorbent is at least one of magnesium sulfate, calcium chloride, magnesium chloride, potassium sulfate, sodium sulfate, sodium chloride, potassium chloride or at least two of them mixed in any proportion.

[0050] As a preferred embodiment of the present invention, the phase transfer catalyst is sodium citrate or adipic acid or a mixture of sodium citrate and adipic acid in any proportion.

[0051] As a preferred embodiment of the present invention, the dispersant is polyethylene glycol.

[0052] A preparation method of the industrial flue gas semi-dry desulfurizer as described above provided by the present invention includes the following steps:

[0053] Step S1, weigh quicklime, moisture absorbent, phase transfer catalyst, dispersant and water;

[0054] Step S2, divide the moisture absorbent into a pre-mixing section moisture absorbent and a water bath section moisture absorbent; divide the phase transfer catalyst into a pre-mixing section phase transfer catalyst and a water bath section phase transfer catalyst;

[0055] Step S3, mix quicklime, the pre-mixing section moisture absorbent, and the pre-mixing section phase transfer catalyst evenly to form a mixed material;

[0056] Step S4, add the dispersant to water and add the mixed material to obtain a mixed material to be reacted;

[0057] Step S5, place the mixed material to be reacted in a water bath heating environment, and under the condition of 65°C - 85°C, stir, and add the water bath section moisture absorbent and the water bath section phase transfer catalyst during the stirring process to make the mixed material to be reacted completely react to obtain a slurry;

[0058] Step S6, spread the slurry flat and perform a drying treatment to obtain a dried sample;

[0059] Step S7, perform a grinding and sieving treatment on the sample to obtain a desulfurizer.

[0060] In the above preparation method adopted by the present invention, a segmented addition process is used for the synergistic additive of the moisture absorbent and the phase transfer catalyst, which is added in different ways at different stages. It is premixed with the quicklime raw material in the early stage and added through water bath stirring in the later stage to ensure the synergistic effect of the moisture absorbent and the phase transfer catalyst, optimize the moisture absorption performance and reaction rate of the desulfurizer, and thus improve the overall desulfurization efficiency.

[0061] As a preferred embodiment of the present invention, the ratio of the moisture absorbent in the premixing stage to the moisture absorbent in the water bath stage is 1:1;

[0062] The ratio of the phase transfer catalyst in the premixing stage to the phase transfer catalyst in the water bath stage is 1:1.

[0063] As a preferred embodiment of the present invention, the reaction mixture to be reacted is stirred by a magnetic stirrer or a mechanical stirrer for at least 1 hour; the stirring speed is 750 rpm to 1250 rpm;

[0064] The moisture absorbent in the water bath stage and the phase transfer catalyst in the water bath stage are added simultaneously.

[0065] Adding the moisture absorbent in the water bath stage and the phase transfer catalyst in the water bath stage simultaneously can avoid the mutual influence of the two on the reaction effect and maintain the best performance of each component.

[0066] As a preferred embodiment of the present invention, in the process of spreading the slurry and drying it to obtain a dried sample,

[0067] The slurry is spread in a container and dried in an oven at 200°C to 250°C for 3 hours.

[0068] As a preferred embodiment of the present invention, in the process of grinding and sieving the sample to obtain the desulfurizer,

[0069] After grinding and sieving the sample through 40 to 60 meshes, the desulfurizer is obtained.

[0070] The reaction mechanism of the desulfurizer with SO2 in the flue gas is as Figure 2 shown: First, SO2 diffuses from the flue gas to the surface of the liquid droplet, then dissolves on the surface of the liquid droplet. The dissolved SO2 reacts with water to form sulfurous acid (H2SO3), which dissociates into bisulfite ions (HSO3 - ) and hydrogen ions (H + ). At the same time, Ca(OH)2 particles also dissolve in water, releasing hydroxide ions (OH - ) and calcium ions (Ca 2+ ), where OH - reacts with H + to form water, and Ca 2+ reacts with HSO3 -Calcium bisulfite (Ca(HSO3)2) is formed by combination, and Ca(HSO3)2 further reacts to form calcium sulfate (CaSO4).

[0071] To better illustrate the detailed effects of the semi-dry flue gas desulfurizer and its preparation method provided by the present invention, examples are given below:

[0072] Comparative Example 1

[0073] The desulfurizer blank sample was prepared by the following steps:

[0074] 10 g of CaO was added to 80 mL of deionized water at 85 °C, and stirred with a magnetic stirrer at a speed of 750 rpm for 1 h;

[0075] The completely stirred slurry was spread out in a corundum boat and dried in an oven at 200 °C for 3 h;

[0076] The dried sample was ground and sieved through 40 - 60 mesh to obtain the desulfurizer blank sample.

[0077] Example 1

[0078] Weigh 10 g of quicklime, 0.3 g of moisture absorbent, 0.3 g of phase transfer catalyst, 0.1 g of dispersant, and 80 mL of water;

[0079] Mix 10 g of quicklime, 0.15 g of moisture absorbent, and 0.15 g of phase transfer catalyst evenly to form a mixed material;

[0080] Add 0.1 g of dispersant to 80 mL of water, and then add the mixed material to obtain the mixed material to be reacted;

[0081] Place the mixed material to be reacted in a water bath heating environment, stir at 85 °C, and add 0.15 g of moisture absorbent and 0.15 g of phase transfer catalyst during stirring to make the mixed material to be reacted completely react to obtain a slurry;

[0082] Spread the slurry in a corundum boat and dry it in an oven at 200 °C for 3 h to obtain a dried sample;

[0083] Grind and sieve the sample through 40 - 60 mesh to obtain the desulfurizer prepared by the present invention.

[0084] Among them, the phase transfer catalyst is selected as sodium citrate, and the dispersant is selected as polyethylene glycol.

[0085] The moisture absorbents were respectively selected as MgSO4, CaCl2, MgCl2, K2SO4, Na2SO4, KCl, and NaCl, and seven desulfurizers were obtained accordingly.

[0086] Contact angle tests were respectively carried out on the seven desulfurizers obtained in Example 1 and the desulfurizer blank sample prepared in Comparative Example 1, and the results are shown in Table 1.

[0087] Additives used Left contact angle / ° Right contact angle / ° Blank sample of desulfurizer 53.13 50.55 <![CDATA[MgSO4]]> 34.72 36.70 <![CDATA[Calcium chloride]]> 27.89 27.64 <![CDATA[MgCl2]]> 29.71 29.46 <![CDATA[K2SO4]]> 35.96 36.48 <![CDATA[Na2SO4]]> 38.37 35.70 KCl 42.36 44.98 NaCl 43.61 41.67

[0088] Table 1

[0089] As can be seen from Table 1, the hygroscopic agent has a significant effect on the wettability of the Ca(OH)2 surface. Without adding any synergist, the desulfurizer blank sample shows relatively high contact angles (about 50.55° and 59.13°), indicating relatively weak surface hydrophilicity. However, the contact angles of the surfaces of the desulfurizers prepared in the present invention are significantly reduced, indicating that the surface hydrophilicity of the desulfurizers provided by the present invention is significantly enhanced, making the surface easier to be wetted. In addition, the desulfurizers prepared by adding MgSO4 and Na2SO4 have relatively low contact angles (34.72° and 36.70°, 35.70° and 38.37° respectively), indicating that the sulfate additives have a positive effect on enhancing the surface hydrophilicity. In contrast, the changes in the contact angles of the desulfurizers added with KCl and NaCl are relatively small, 42.36° and 44.98°, 43.61° and 41.67° respectively, and the hygroscopicity is relatively weak. It can be inferred from this that highly hygroscopic chlorides such as CaCl2 and MgCl2 can significantly enhance the hydrophilicity of the desulfurizer.

[0090] A fixed-bed reactor was used to respectively carry out desulfurization effect tests on the seven desulfurizers obtained in Example 1 and the desulfurizer blank sample prepared in Comparative Example 1. The effect test results are shown in Table 2.

[0091]

[0092]

[0093] Table 2

[0094] From Table 2 and Figure 3 and Figure 4 it can be seen that compared with the desulfurizer blank sample, the unit sulfur capacity and the initial breakthrough time of the desulfurizer prepared in the present invention are greatly improved. Among them, the unit sulfur capacity of the desulfurizer after adding MgSO4 is increased the most, from 110.06 mg / g to 161.80 mg / g, and the effect is significant. Such additives absorb the moisture in the flue gas, form a water film on the surface of the desulfurizer, and increase the contact area between SO2 and Ca(OH)2, thereby promoting the reaction.

[0095] The industrial flue gas semi-dry desulfurizer and preparation method thereof according to the present invention have been described above by way of example with reference to the accompanying drawings. However, those skilled in the art should understand that various improvements can be made to the above-mentioned industrial flue gas semi-dry desulfurizer and preparation method thereof without departing from the content of the present invention. Therefore, the protection scope of the present invention should be determined by the content of the appended claims.

Claims

1. A semi-dry desulfurization agent for industrial flue gas, characterized in that: The desulfurizer is prepared from the following raw materials: quicklime, moisture absorbent, phase transfer catalyst, dispersant, and water; wherein: The mass of the desiccant is 1 to 5% of the mass of the quicklime; The mass of the phase transfer catalyst is 1 to 5% of the mass of the quicklime; The mass of the dispersant is 1 to 3% of the mass of the quicklime; The mass ratio of water to quicklime is 8:

1.

2. The industrial flue gas semi-dry desulfurization agent according to claim 1, characterized in that: The purity of the quicklime is not less than 93%, the effective calcium content is at least 90%, the activity is above 360, T 60 <1 minute.

3. The industrial flue gas semi-dry desulfurization agent according to claim 1, characterized in that: The desiccant is at least one of magnesium sulfate, calcium chloride, magnesium chloride, potassium sulfate, sodium sulfate, sodium chloride, and potassium chloride, or at least two of them mixed in any proportion.

4. The industrial flue gas semi-dry desulfurization agent according to claim 1, characterized in that: The phase transfer catalyst is sodium citrate or adipic acid or a mixture of sodium citrate and adipic acid in any proportion.

5. The industrial flue gas semi-dry desulfurization agent according to claim 1, characterized in that: The dispersant is polyethylene glycol.

6. A method for preparing a semi-dry desulfurization agent for industrial flue gas according to any one of claims 1 to 5, characterized in that: The steps include: Weigh quicklime, hygroscopic agent, phase transfer catalyst, dispersant and water; The desiccant is divided into a premixing section desiccant and a water bath section desiccant; the phase transfer catalyst is divided into a premixing section phase transfer catalyst and a water bath section phase transfer catalyst; The quicklime, the premixing stage moisture absorbent, and the premixing stage phase transfer catalyst are uniformly mixed to form a mixed material; Adding the dispersant into water and the mixed material to obtain a reaction mixture; The reaction mixture is placed in a water bath heating environment and stirred at 65°C to 85°C, and the water bath section moisture absorbent and the water bath section phase transfer catalyst are added during the stirring process to allow the reaction mixture to react completely to obtain a slurry; The slurry is spread out and dried to obtain a dried sample; The sample is ground and sieved to obtain a desulfurizing agent.

7. The method for preparing the semi-dry desulfurization agent for industrial flue gas according to claim 6, characterized in that: The ratio of the premixing section desiccant to the water bath section desiccant is 1:1; The ratio of the premixing stage phase transfer catalyst to the water bath stage phase transfer catalyst is 1:

1.

8. The method for preparing the semi-dry desulfurization agent for industrial flue gas according to claim 6, characterized in that: Stirring the reaction mixture for at least 1 hour by means of a magnetic stirrer or a mechanical stirrer; the stirring speed is 750 rpm to 1250 rpm; The water bath section moisture absorbent and the water bath section phase transfer catalyst are added simultaneously.

9. The method for preparing a semi-dry desulfurization agent for industrial flue gas according to claim 6, characterized in that: In the process of spreading the slurry and drying it to obtain a dried sample, The slurry was spread evenly in a container and dried in an oven at 200° C. to 250° C. for 3 h.

10. The method for preparing the semi-dry desulfurization agent for industrial flue gas according to claim 6, characterized in that: In the process of grinding and sieving the sample to obtain the desulfurizer, The sample is ground and sieved through 40-60 meshes to obtain a desulfurizing agent.

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