A flue gas desulfurization and denitrification treatment method

Abstract

The present application discloses a flue gas desulfurization and denitrification treatment method, which belongs to the field of flue gas purification technology. A flue gas desulfurization and denitrification treatment method comprises the following steps: after the coke oven flue gas is heat exchanged in a flue gas heat exchanger, the heat energy is recovered, and the flue gas cooled to below 120-150°C is passed into a filter bag to obtain dust-removed flue gas; the dust-removed flue gas is introduced into a desulfurization and denitrification tower loaded with a desulfurization and denitrification agent, and a mixed gas of ammonia and air is passed into it to obtain desulfurized and denitrified flue gas; the used desulfurization and denitrification agent is transported to a regeneration tower, and the used desulfurization and denitrification agent is regenerated by the recovered heat energy, and the regenerated desulfurization and denitrification agent is transported to the desulfurization and denitrification tower for recycling; the desulfurization and denitrification agent comprises the following components: modified activated carbon, carboxymethyl starch, limestone, sodium humate, protein soil, magnesium chloride and polybutyl acetate; the desulfurization and denitrification agent has good adsorption and catalytic properties before and after regeneration, ensuring the desulfurization and denitrification effect while improving economic benefits.

Description

Technical Field

[0001] The present application relates to a flue gas desulfurization and denitrification treatment method, belonging to the technical field of flue gas purification. Background Art

[0002] Coking is a way to efficiently utilize coal and is an indispensable prerequisite and guarantee for steelmaking and ironmaking. x Flue gas containing atmospheric pollutants such as SO2 and SO2, if discharged directly into the atmosphere without treatment, will have a serious impact on the natural ecological environment and will also threaten human physical and mental health. Due to the complex composition of flue gas, large temperature differences between high and low temperatures, and large flue gas volume, the removal process of sulfur oxides and nitrogen oxides is often very complicated. At present, the commonly used desulfurization and denitrification technologies can be divided into two categories: one is that the flue gas first passes through the desulfurization process equipment to remove sulfur oxides, and then passes through the denitrification process equipment to remove nitrogen oxides, that is, first desulfurization through desulfurization technology, and then denitrification through denitrification technology; the other is to remove SO2 and NO at the same time through the flue gas simultaneous desulfurization and denitrification technology x In order to streamline equipment, optimize operations, save investment costs, operating costs and floor space, simultaneous desulfurization and denitrification in one device to achieve integrated desulfurization and denitrification has become one of the future development directions of flue gas treatment technology.

[0003] Chinese invention patent CN107511064A discloses a desulfurization and denitrification method based on activated carbon and low-temperature catalyst, which includes the following steps: (1) the dust in the flue gas is first removed by gravity sedimentation; (2) the flue gas with dust removed is fully mixed with ammonia water; (3) the flue gas fully mixed with ammonia water enters the activated carbon in a fluidized state, wherein a part of the activated carbon serves as a carrier of the low-temperature catalyst, and NO x The reaction between SO2 and NH3 will be fully carried out under the action of low-temperature catalyst, and SO2 will be adsorbed by activated carbon, removing NO x and NH3 and SO2 removal; (4) removal of NO x Flue gas dehydrated with NH3 and SO2 undergoes centrifugal sedimentation to remove the activated carbon carried in the flue gas, resulting in activated carbon-removed flue gas. This method is simple, reduces equipment investment and operating costs, and is pollution-free, facilitating the large-scale deployment of desulfurization and denitrification technologies. However, as the desulfurization and denitrification reactions proceed, the resulting products clog the activated carbon pores and reduce catalyst activity, leading to a decrease in removal efficiency. Furthermore, some activated carbon exhibits poor catalytic performance after regeneration and cannot be reused, increasing operating costs and energy consumption. Summary of the Invention

[0004] In order to solve the above problems, a flue gas desulfurization and denitrification treatment method is provided to reduce the occurrence of decreased removal efficiency of sulfur dioxide and nitrogen oxides due to blockage of activated carbon pores. After regeneration, the desulfurization and denitrification agent has good adsorption and catalytic performance, ensuring the desulfurization and denitrification effects while improving economic benefits.

[0005] The present invention adopts the following technical solutions:

[0006] A flue gas desulfurization and denitrification treatment method comprises the following steps:

[0007] (1) After the coke oven flue gas is heat exchanged in the flue gas heat exchanger, the heat energy is recovered and the flue gas cooled to below 120-150°C is passed into the filter bag. The dust in the flue gas is removed by the pulse soot blowing method to obtain dust-removed flue gas;

[0008] This process uses a pulsed soot blowing method to clean the soot thoroughly, consumes little gas, and is not affected by the amount of flue gas. The recovered heat energy is supplied to the subsequent regeneration process, further improving economic benefits.

[0009] (2) The dust removal flue gas is introduced into a desulfurization and denitrification tower loaded with desulfurization and denitrification agents, and a mixed gas of ammonia and air is introduced, wherein the ammonia content is 3-7%, so as to remove SO2 and NO in the dust removal flue gas. x , the obtained desulfurized and denitrified flue gas is discharged into the atmosphere;

[0010] Specifically, SO2 in the dust removal flue gas is adsorbed on the active sites of the desulfurization and denitrification agent and is oxidized to H2SO4 in the presence of oxygen and water vapor. At the same time, under the catalytic action of the desulfurization and denitrification agent, NO x Reacts with ammonia to generate nitrogen and water, thereby achieving SO2 and NO x removal;

[0011] (3) transporting the desulfurization and denitrification agent used in step (2) to a regeneration tower, regenerating the desulfurization and denitrification agent used by the heat energy recovered in step (1), and transporting the regenerated desulfurization and denitrification agent to the desulfurization and denitrification tower for recycling;

[0012] Specifically, when the used desulfurization and denitrification agent is heated, the H2SO4 on it reacts with C (carbon) to generate SO2, which can be treated by acid production or ammonium sulfate production, thereby realizing its resource utilization, economic and environmental protection;

[0013] The desulfurization and denitrification agent comprises the following components by weight: 18-30 parts of modified activated carbon, 15-25 parts of carboxymethyl starch, 12-25 parts of limestone, 10-20 parts of sodium humate, 8-15 parts of protein soil, 6-12 parts of magnesium chloride and 3-8 parts of polybutyl acetate;

[0014] Specifically, the modified activated carbon has a large pore size and a stable structure, significantly reducing the possibility of clogging and collapse during use, ensuring the activity of the desulfurization and denitrification agent, and is easy to regenerate, with good adsorption and catalytic performance after regeneration. Carboxymethyl starch has hydrophilic carboxyl groups and a porous structure, which allows it to synergize with moisture in flue gas to increase adsorption efficiency and also facilitates bonding between components, improving the stability of the desulfurization and denitrification agent. The good filling and covering effects of sodium humate tightly connect the components together, helping to improve the strength of the modified activated carbon. Magnesium chloride fills and wraps between the components, increasing the density and compressive strength of the components. Limestone can assist the modified activated carbon in removing sulfur dioxide and nitrogen oxides from flue gas, enhancing the adsorption effect and increasing the adsorption capacity and efficiency. Protein clay can release negative ions, which helps reduce the number of fine particles in the flue gas and remove odors, thereby achieving the goal of rapidly improving flue gas quality. Polybutyl acetate can increase the bonding strength between the components, helping to improve the mechanical strength and stability of the desulfurization and denitrification agent, while also expanding the scope of application of the desulfurization and denitrification agent.

[0015] Optionally, the weight ratio of modified activated carbon, protein soil and polybutyl acetate is (5-8): (1-3): 1;

[0016] The weight ratio of sodium humate to magnesium chloride is (1-2):1.

[0017] Optionally, the preparation method of the modified activated carbon comprises the following steps:

[0018] S1. The coke powder is crushed and passed through a 180-200 mesh sieve, immersed in a nitric acid solution for 2-4 days, washed with water, and then immersed in a potassium hydroxide solution for 12-18 days. After drying to a paste, it is calcined and activated under nitrogen protection for 1-5 hours, cooled, washed until neutral, filtered, and dried to obtain activated carbon;

[0019] In this process, the coke powder is first deashed with nitric acid, then impregnated with KOH and activated by high-temperature calcination, which makes the prepared activated carbon loose in structure and forms a large number of pore structures with rich pore structure distribution and increased specific surface area.

[0020] S2. Dispersing titanium dioxide in toluene and heating the mixture to 70-90° C. to obtain a mixed solution, then uniformly mixing 3-(isomethacryloyloxy)propyltrimethoxysilane, triethylamine, and toluene, and adding the mixture dropwise to the mixed solution, continuing the reaction for 20-30 hours, then centrifuging, and washing the precipitate with toluene, ethanol, and diethyl ether in sequence, and drying to obtain modified titanium dioxide;

[0021] During this process, the titanium dioxide surface is rich in active hydroxyl groups, which can react with 3-(isomethylacryloyloxy)propyltrimethoxysilane through silylation to remove methanol molecules and achieve organic-inorganic functionalization. After the silylation reaction, carbonyl groups and double bonds are introduced on the titanium dioxide surface, which is beneficial for subsequent reactions.

[0022] S3, dissolving 1-allyl-3-methylimidazolium tetrafluoroborate in a mixed solution of deionized water and N,N-dimethylformamide, then adding S1 activated carbon, heating and stirring at 50-70°C for 20-30h, then adding S2 modified titanium dioxide and initiator, reacting at 60-80°C under nitrogen protection, cooling after completion, washing, filtering, and drying to obtain modified activated carbon;

[0023] In this process, 1-allyl-3-methylimidazolium tetrafluoroborate is evenly loaded onto the activated carbon, and the activated carbon is initially modified, resulting in an increase in the pores of the activated carbon, an increase in the pore size, and a uniform and dense distribution of the pores, which is beneficial to the adsorption of the activated carbon; the carbonyl groups and double bonds introduced on the modified titanium dioxide can be grafted with the 1-allyl-3-methylimidazolium tetrafluoroborate on the activated carbon through the double bonds on the allyl groups, ensuring that the titanium dioxide is stably attached to the activated carbon, which not only reduces the possibility of collapse of the activated carbon pores during the regeneration process, but also the titanium dioxide can cover the micropores of the activated carbon and block its original pore size, so that during the desulfurization process, SO2 can be adsorbed more on the active sites on the surface of the activated carbon, which facilitates the desorption of SO2 during the regeneration process. x There is van der Waals force between SO2, NO and the surface molecules of titanium dioxide particles. x It can be adsorbed on titanium dioxide. When the molecules on the surface of titanium dioxide are heated, the adsorbed SO2 and NO x It can be desorbed from titanium dioxide, thereby improving the desulfurization and denitrification performance and regeneration function of the modified activated carbon.

[0024] Optionally, the concentration of the nitric acid solution in S1 is 5-8 mol / L, and the concentration of the potassium hydroxide solution is 8-12 mol / L.

[0025] Optionally, the grafting rate of 3-(methacryloyloxy)propyltrimethoxysilane grafted onto the titanium dioxide surface in S2 is 15-20%.

[0026] Optionally, the amount of 1-allyl-3-methylimidazolium tetrafluoroborate added in S3 is 2-5 wt% of the activated carbon;

[0027] The mass ratio of modified titanium dioxide to 1-allyl-3-methylimidazolium tetrafluoroborate is 1:(15-20).

[0028] Optionally, the preparation method of the desulfurization and denitrification agent comprises the following steps:

[0029] Step 1: Weigh 18-30 parts of modified activated carbon by weight, add 15-25 parts of carboxymethyl starch, 12-25 parts of limestone, 10-20 parts of sodium humate, 8-15 parts of protein soil, 6-12 parts of magnesium chloride and 3-8 parts of polybutyl acetate, mix thoroughly, then add water and stir evenly to obtain a premix;

[0030] Step 2: The premix is ​​aged for 20-40 minutes, then placed into a molding die for cold pressing at a molding pressure of 20-30 MPa and a holding time of 20-40 seconds, and then demolded to obtain a molding material;

[0031] Step 3: Cover the surface of the molding material with plastic wrap for maintenance. After maintenance at 15-25°C for 20-30 hours, remove the plastic wrap and dry it at 28-35°C for 40-50 hours to obtain the desulfurization and denitrification agent.

[0032] Specifically, the hydration effect between the modified activated carbon particles and the auxiliary agent molecules is strengthened through the aging process, thereby improving the density and bonding strength of the desulfurization and denitrification agent. The maintenance process can promote the uniform distribution of water, so that the components are fully bonded, and further improve the mechanical strength and stability of the desulfurization and denitrification agent.

[0033] Optionally, in step (1), the blowing pressure is 0.3-0.5 MPa.

[0034] Optionally, in step (2), the dust removal flue gas air velocity is 500 to 1000 m 3 / h, the mixed gas space velocity is 10000~20000m 3 / h.

[0035] Optionally, in step (3), the regeneration temperature is 400-500° C. and the regeneration time is 30-60 min.

[0036] The beneficial effects of this application include but are not limited to:

[0037] The flue gas desulfurization and denitrification treatment method of the present application can, on the one hand, utilize the flue gas thermal energy to regenerate the desulfurization and denitrification agent, and on the other hand, ensure the desulfurization and denitrification effect of the flue gas by designing an integrated desulfurization and denitrification process and improving the desulfurization and denitrification agent; wherein, the compounding of modified activated carbon, organic binder and inorganic binder improves the mechanical strength of the desulfurization and denitrification agent, ensuring its quality and stable performance; the raw material of the modified activated carbon is coke powder generated in the dry coking process of raw coal samples and the coke crushing process in the chemical industry, which can not only reduce the cost of flue gas desulfurization and denitrification, but also realize the resource utilization of solid waste, thereby achieving the purpose of energy saving and environmental protection. ; By loading 1-allyl-3-methylimidazolium tetrafluoroborate on activated carbon, on the one hand, the pores of the activated carbon are increased, the pore size is enlarged, and the pores are evenly and densely distributed, which is beneficial to the adsorption of the activated carbon. On the other hand, titanium dioxide is stably attached to the activated carbon. Titanium dioxide can cover the micropores of the activated carbon and block its original pore size. During the desulfurization process, SO2 can be more adsorbed on the active sites on the surface of the activated carbon, which is convenient for the desorption of SO2 during the regeneration process. This physical and chemical combination of desulfurization and denitrification method can reduce the deposition of reaction products on the desulfurization and denitrification agent and extend its service life, so it has broad application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] The drawings described herein are used to provide a further understanding of the present application and constitute a part of the present application. The illustrative embodiments of the present application and their descriptions are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings:

[0039] Figure 1 This is a flow chart of the flue gas desulfurization and denitrification treatment method involved in the embodiment of the present application. DETAILED DESCRIPTION

[0040] The endpoints of the ranges and any values ​​disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoints of each range, the endpoints of each range and individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered to be specifically disclosed herein.

[0041] If the specific conditions are not specified in the examples, the experiments were carried out under conventional conditions or those recommended by the manufacturer. The raw materials or instruments used, if the manufacturers are not specified, are all conventional products that can be purchased commercially.

[0042] Example 1

[0043] This embodiment provides a method for preparing modified activated carbon, comprising the following steps:

[0044] S1, the coke powder was crushed and passed through a 180-mesh sieve, immersed in a 5 mol / L nitric acid solution for 4 days, washed with water, and then immersed in an 8 mol / L potassium hydroxide solution for 18 days. After drying to a paste, it was calcined and activated under nitrogen protection for 1 hour, cooled, washed to neutrality, filtered, and dried to obtain activated carbon;

[0045] S2. Dispersing titanium dioxide in toluene and heating the mixture to 70° C. to obtain a mixed solution, then uniformly mixing 3-(isomethacryloyloxy)propyltrimethoxysilane, triethylamine, and toluene, and adding the mixture dropwise to the mixed solution, continuing the reaction for 30 hours, and then centrifuging the mixture. The precipitate is washed with toluene, ethanol, and diethyl ether in sequence, and dried to obtain modified titanium dioxide; wherein the grafting rate of 3-(isomethacryloyloxy)propyltrimethoxysilane onto the titanium dioxide surface is 15%;

[0046] S3. Dissolve 1-allyl-3-methylimidazolium tetrafluoroborate in a mixed solution of deionized water and N,N-dimethylformamide, add S1 activated carbon, heat and stir at 50°C for 30 hours, then add S2 modified titanium dioxide and azobisisobutyronitrile, react at 60°C under nitrogen protection, cool after completion, wash, filter, and dry to obtain modified activated carbon; wherein the addition amount of 1-allyl-3-methylimidazolium tetrafluoroborate is 2wt% of the activated carbon, and the mass ratio of modified titanium dioxide to 1-allyl-3-methylimidazolium tetrafluoroborate is 1:15.

[0047] Example 2

[0048] This embodiment provides a method for preparing modified activated carbon, comprising the following steps:

[0049] S1, the coke powder was crushed and passed through a 190 mesh sieve, immersed in an 8 mol / L nitric acid solution for 2 days, washed with water, and then immersed in a 12 mol / L potassium hydroxide solution for 12 days. After drying to a paste, it was calcined and activated under nitrogen protection for 5 hours, cooled, washed until neutral, filtered, and dried to obtain activated carbon;

[0050] S2. Dispersing titanium dioxide in toluene and heating the mixture to 90° C. to obtain a mixed solution, then uniformly mixing 3-(isomethacryloyloxy)propyltrimethoxysilane, triethylamine, and toluene, and adding the mixture dropwise to the mixed solution, continuing the reaction for 20 hours, and then centrifuging the mixture. The precipitate is washed with toluene, ethanol, and diethyl ether in sequence, and dried to obtain modified titanium dioxide; wherein the grafting rate of 3-(isomethacryloyloxy)propyltrimethoxysilane onto the titanium dioxide surface is 20%;

[0051] S3. Dissolve 1-allyl-3-methylimidazolium tetrafluoroborate in a mixed solution of deionized water and N,N-dimethylformamide, add S1 activated carbon, heat and stir at 70°C for 20 hours, then add S2 modified titanium dioxide and azobisisobutyronitrile, react at 80°C under nitrogen protection, cool after completion, wash, filter, and dry to obtain modified activated carbon; wherein the addition amount of 1-allyl-3-methylimidazolium tetrafluoroborate is 5wt% of the activated carbon, and the mass ratio of modified titanium dioxide to 1-allyl-3-methylimidazolium tetrafluoroborate is 1:20.

[0052] Example 3

[0053] This embodiment provides a method for preparing modified activated carbon, comprising the following steps:

[0054] S1, the coke powder was crushed and passed through a 200-mesh sieve, immersed in a 6 mol / L nitric acid solution for 3 days, washed with water, and then immersed in a 10 mol / L potassium hydroxide solution for 15 days. After drying to a paste, it was calcined and activated under nitrogen for 3 hours, cooled, washed until neutral, filtered, and dried to obtain activated carbon;

[0055] S2. Dispersing titanium dioxide in toluene and heating the mixture to 80° C. to obtain a mixed solution, then uniformly mixing 3-(isomethacryloyloxy)propyltrimethoxysilane, triethylamine, and toluene, and adding the mixture dropwise to the mixed solution, continuing the reaction for 24 hours, and then centrifuging the mixture. The precipitate is washed with toluene, ethanol, and diethyl ether in sequence, and dried to obtain modified titanium dioxide; wherein the grafting rate of 3-(isomethacryloyloxy)propyltrimethoxysilane onto the titanium dioxide surface is 18%;

[0056] S3. Dissolve 1-allyl-3-methylimidazolium tetrafluoroborate in a mixed solution of deionized water and N,N-dimethylformamide, add S1 activated carbon, heat and stir at 60°C for 24 hours, then add S2 modified titanium dioxide and azobisisobutyronitrile, react at 70°C under nitrogen protection, cool after completion, wash, filter, and dry to obtain modified activated carbon; wherein, the addition amount of 1-allyl-3-methylimidazolium tetrafluoroborate is 3.5wt% of the activated carbon, and the mass ratio of modified titanium dioxide to 1-allyl-3-methylimidazolium tetrafluoroborate is 1:17.

[0057] Comparative Example 1

[0058] The difference from Example 3 is that S2 and S3 are not included.

[0059] Comparative Example 2

[0060] The difference from Example 3 is that the 3-(isomethacryloyloxy)propyltrimethoxysilane in S2 is replaced by γ-methacryloyloxypropyltrimethoxysilane.

[0061] Comparative Example 3

[0062] The difference from Example 3 is that S2 is not included, and S3 is:

[0063] 1-allyl-3-methylimidazolium tetrafluoroborate was dissolved in a mixed solution of deionized water and N,N-dimethylformamide, and S1 activated carbon was added. The mixture was heated and stirred at 60°C for 24 hours, cooled, filtered, and dried to obtain modified activated carbon. The amount of 1-allyl-3-methylimidazolium tetrafluoroborate added was 3.5 wt% of the activated carbon.

[0064] Comparative Example 4

[0065] The difference from Example 3 is that S2 and S3 are replaced by:

[0066] Titanium dioxide was dispersed in deionized water, and S1 activated carbon was added, heated and stirred at 60°C for 24 hours, and then cooled, filtered, and dried to obtain modified activated carbon; wherein the addition amount of titanium dioxide was 3.5wt% of the activated carbon.

[0067] Comparative Example 5

[0068] The difference from Example 3 is that the 1-allyl-3-methylimidazolium tetrafluoroborate in S3 is replaced by 1-isobutenyl-3-methylimidazolium tetrafluoroborate.

[0069] The specific surface area and volume of the modified activated carbons prepared in Examples 1-3 and Comparative Examples 1-5 were characterized and analyzed using the BET method. The results are shown in Table 1.

[0070] Table 1

[0071] Test number <![CDATA[Specific surface area / m 2 ·g -1 > <![CDATA[Total pore volume / cm 3 ·g -1 > <![CDATA[Medium and large pore volume / cm 3 ·g -1 > Example 1 1048.66 0.85 0.47 Example 2 1055.91 0.87 0.49 Example 3 1067.03 0.89 0.51 Comparative Example 1 684.65 0.38 0.17 Comparative Example 2 975.21 0.70 0.36 Comparative Example 3 867.38 0.57 0.28 Comparative Example 4 816.82 0.49 0.24 Comparative Example 5 943.16 0.65 0.33

[0072] It can be seen from Table 1 that, based on Comparative Example 1, after modification by the methods of Examples 1-3, the pore structure of the activated carbon becomes richer, and a large number of medium and large pores are generated to capture more particles and molecules, thereby reducing the mass transfer resistance and making the adsorption process more efficient. It can be seen from Comparative Examples 2-5 that changing any modification condition affects the pore structure of the activated carbon, resulting in the inability to achieve the expected effect in the desulfurization and denitrification process.

[0073] Example 4

[0074] refer to Figure 1 This embodiment provides a flue gas desulfurization and denitrification treatment method, comprising the following steps:

[0075] (1) After the coke oven flue gas is heat exchanged in the flue gas heat exchanger, the heat energy is recovered and the flue gas cooled to below 120°C is passed into the filter bag. The dust in the flue gas is removed by pulse soot blowing at a pressure of 0.5 MPa to obtain dust-removed flue gas.

[0076] (2) Set the airspeed to 500m 3 / h dust removal flue gas is introduced into the desulfurization and denitrification tower loaded with 1 / 3 desulfurization and denitrification agent, and the air velocity is 10000m 3 / h a mixture of ammonia and air, with an ammonia content of 3%, to remove SO2 and NO in dust removal flue gas x , the obtained desulfurized and denitrified flue gas is discharged into the atmosphere;

[0077] (3) transporting the desulfurization and denitrification agent used in step (2) to a regeneration tower, regenerating the desulfurization and denitrification agent using the heat energy recovered in step (1), with a regeneration temperature of 400° C. and a regeneration time of 60 min. The regenerated desulfurization and denitrification agent is transported to the desulfurization and denitrification tower for recycling;

[0078] The preparation method of the desulfurization and denitrification agent comprises the following steps:

[0079] Step 1: Weigh 18 parts of the modified activated carbon of Example 3 by weight, add 15 parts of carboxymethyl starch, 12 parts of limestone, 10 parts of sodium humate, 9 parts of protein soil, 10 parts of magnesium chloride and 3 parts of polybutyl acetate, mix thoroughly, and then add water and stir evenly to obtain a premix;

[0080] Step 2: The premix is ​​aged for 20 minutes, then placed into a molding die for cold pressing at a molding pressure of 20 MPa and a holding time of 40 seconds, and then demolded to obtain a molding material;

[0081] Step 3: Cover the surface of the molding material with plastic wrap for maintenance. After maintenance at 15°C for 30 hours, remove the plastic wrap and then dry at 28°C for 50 hours to obtain the desulfurization and denitrification agent.

[0082] Example 5

[0083] refer to Figure 1 This embodiment provides a flue gas desulfurization and denitrification treatment method, comprising the following steps:

[0084] (1) After the coke oven flue gas is heat exchanged in the flue gas heat exchanger, the heat energy is recovered and the flue gas cooled to below 150°C is passed into the filter bag. The dust in the flue gas is removed by pulse soot blowing at a pressure of 0.3 MPa to obtain dust-removed flue gas.

[0085] (2) Set the airspeed to 1000m 3 / h dust removal flue gas is introduced into the desulfurization and denitrification tower loaded with 1 / 3 desulfurization and denitrification agent, and the air velocity is 20000m3 / h a mixture of ammonia and air, with an ammonia content of 7%, to remove SO2 and NO in the dust removal flue gas x , the obtained desulfurized and denitrified flue gas is discharged into the atmosphere;

[0086] (3) transporting the desulfurization and denitrification agent used in step (2) to a regeneration tower, regenerating the desulfurization and denitrification agent using the heat energy recovered in step (1), with a regeneration temperature of 500° C. and a regeneration time of 30 min. The regenerated desulfurization and denitrification agent is transported to the desulfurization and denitrification tower for recycling;

[0087] The preparation method of the desulfurization and denitrification agent comprises the following steps:

[0088] Step 1: Weigh 30 parts of the modified activated carbon of Example 3 by weight, add 25 parts of carboxymethyl starch, 25 parts of limestone, 20 parts of sodium humate, 10 parts of protein soil, 10 parts of magnesium chloride and 5 parts of polybutyl acetate, mix thoroughly, and then add water and stir evenly to obtain a premix;

[0089] Step 2: The premix is ​​aged for 40 minutes, then placed into a molding die for cold pressing at a molding pressure of 30 MPa and a holding time of 20 seconds, and then demolded to obtain a molding material;

[0090] Step 3: Cover the surface of the molding material with plastic wrap for maintenance. After maintenance at 25°C for 20 hours, remove the plastic wrap and then dry at 35°C for 40 hours to obtain the desulfurization and denitrification agent.

[0091] Example 6

[0092] refer to Figure 1 This embodiment provides a flue gas desulfurization and denitrification treatment method, comprising the following steps:

[0093] (1) After the coke oven flue gas is heat exchanged in the flue gas heat exchanger, the heat energy is recovered and the flue gas cooled to below 140°C is passed into the filter bag. The dust in the flue gas is removed by pulse soot blowing at a pressure of 0.4 MPa to obtain dust-removed flue gas.

[0094] (2) Set the airspeed to 800m 3 / h dust removal flue gas is introduced into the desulfurization and denitrification tower loaded with 1 / 3 desulfurization and denitrification agent, and the air velocity is 15000m 3 / h a mixture of ammonia and air, with an ammonia content of 5%, to remove SO2 and NO in the dust removal flue gas x , the obtained desulfurized and denitrified flue gas is discharged into the atmosphere;

[0095] (3) transporting the desulfurization and denitrification agent used in step (2) to a regeneration tower, regenerating the desulfurization and denitrification agent using the heat energy recovered in step (1), with a regeneration temperature of 450° C. and a regeneration time of 45 minutes, and transporting the regenerated desulfurization and denitrification agent to the desulfurization and denitrification tower for recycling;

[0096] The preparation method of the desulfurization and denitrification agent comprises the following steps:

[0097] Step 1: Weigh 28 parts of the modified activated carbon of Example 3 by weight, add 20 parts of carboxymethyl starch, 15 parts of limestone, 18 parts of sodium humate, 12 parts of protein soil, 9 parts of magnesium chloride and 4 parts of polybutyl acetate, mix thoroughly, and then add water and stir evenly to obtain a premix;

[0098] Step 2: The premix is ​​aged for 30 minutes, then placed into a molding mold for cold pressing at a molding pressure of 25 MPa and a holding time of 30 seconds, and then demolded to obtain a molding material;

[0099] Step 3: Cover the surface of the molding material with plastic wrap for maintenance. After maintenance at 20°C for 24 hours, remove the plastic wrap and then dry at 30°C for 48 hours to obtain the desulfurization and denitrification agent.

[0100] Comparative Example 6

[0101] The difference from Example 6 is that the desulfurization and denitrification agent does not include protein soil and polybutyl acetate.

[0102] Comparative Example 7

[0103] The difference from Example 6 is that the preparation method of the desulfurization and denitrification agent includes the following steps:

[0104] Step 1: Weigh 28 parts of modified activated carbon by weight, add 20 parts of carboxymethyl starch, 15 parts of limestone, 18 parts of sodium humate, 12 parts of protein soil, 9 parts of magnesium chloride and 4 parts of polybutyl acetate, mix thoroughly, then add water and stir evenly to obtain a premix;

[0105] Step 2: Place the premix into a molding die for cold pressing. The molding pressure is 25 MPa, the pressure holding time is 30 seconds, and the mold is demolded to obtain the desulfurization and denitrification agent.

[0106] Comparative Example 8

[0107] The desulfurization and denitrification method based on activated carbon and low-temperature catalyst in Chinese invention patent CN107511064A is adopted, which includes the following steps:

[0108] (1) The boiler flue gas is first subjected to gravity sedimentation to remove dust from the flue gas;

[0109] (2) The dust-removed flue gas is fully mixed with ammonia water;

[0110] (3) The flue gas fully mixed with ammonia water enters the desulfurization and denitrification agent of Example 6 in a fluidized state, and NO X The desulfurization and denitrification agent of Example 6 will fully react with NH3, and SO2 will be adsorbed by the desulfurization and denitrification agent of Example 6, and NO in the flue gas will be reduced. X and NH3 and SO2 removal;

[0111] (4) NO removal X The flue gas containing NH3 and SO2 is subjected to centrifugal sedimentation to remove the desulfurization and denitrification agents carried in the flue gas, thereby obtaining flue gas free of desulfurization and denitrification agents.

[0112] The flue gas desulfurization and denitrification treatment methods in Examples 4-6 and Comparative Examples 6-8 were evaluated for their effects. The desulfurization and denitrification agent was used at a temperature of 200°C and flue gas conditions of SO2 concentration of 400 mg / Nm 3 , NO x The concentration is 800mg / Nm 3 , particulate matter is 50mg / Nm 3 , the results are shown in Table 2.

[0113] Table 2

[0114] Test number Desulfurization rate / % Denitrification rate / % Dust removal rate / % Example 4 93.9 85.7 96.5 Example 5 93.6 86.4 97.2 Example 6 95.2 88.5 98.6 Comparative Example 6 81.4 69.6 84.8 Comparative Example 7 84.6 75.2 87.5 Comparative Example 8 70.5 66.7 74.3

[0115] It can be seen from Table 2 that the desulfurization and denitrification effects of coke oven flue gas are closely related to the desulfurization and denitrification agents and the desulfurization and denitrification treatment methods. Among them, the desulfurization rate of Examples 4-6 reaches more than 93.6%, the denitrification rate reaches more than 85.7%, and the dust removal rate reaches more than 96.5%, and the odor in the flue gas can also be purified at the same time.

[0116] The modified activated carbons prepared in Examples 1-3 and Comparative Examples 1-5 were applied to the desulfurization and denitrification agent of Example 6, and the performance of the desulfurization and denitrification agent containing the modified activated carbons of Examples 1-3 and Comparative Examples 1-5 was evaluated by the flue gas desulfurization and denitrification treatment method of Example 6. The treatment conditions were: the action temperature of the desulfurization and denitrification agent was 200°C, the flue gas conditions were: the SO2 concentration was 400 mg / Nm 3 , NO x The concentration is 800mg / Nm 3 , particulate matter is 50mg / Nm 3 , the number of regeneration cycles is 5 times, and the results are shown in Table 3.

[0117] Table 3

[0118]

[0119]

[0120] It can be seen from Table 3 that after regeneration, the desulfurization and denitrification rates of the desulfurization and denitrification agents of Examples 1-3 can still reach more than 85% of the rates before regeneration, achieving effective regeneration. Compared with Examples 1-3, the desulfurization and denitrification rates of the desulfurization and denitrification agents of Comparative Examples 2-5 decreased after regeneration. However, unlike Comparative Example 1, the desulfurization and denitrification rates of the desulfurization and denitrification agents of Comparative Example 1 were greatly reduced after regeneration, which has little significance for the regeneration and recycling application of the desulfurization and denitrification agents in the actual process.

[0121] The foregoing is merely an embodiment of the present application, and the scope of protection of the present application is not limited by these specific embodiments, but is determined by the claims of the present application. For those skilled in the art, the present application may have various modifications and variations. Any modifications, equivalent substitutions, improvements, etc. made within the technical ideas and principles of the present application should be included in the scope of protection of the present application.

Claims

1. A flue gas desulfurization and denitrification treatment method, characterized in that: The following steps are involved: (1) After the coke oven flue gas is heat exchanged in the flue gas heat exchanger, the heat energy is recovered and the flue gas cooled to below 120-150°C is passed into the filter bag. The dust in the flue gas is removed by the pulse soot blowing method to obtain dust-removed flue gas; (2) The dust removal flue gas is introduced into a desulfurization and denitrification tower loaded with desulfurization and denitrification agents, and a mixed gas of ammonia and air is introduced, wherein the ammonia content is 3-7%, so as to remove SO2 and NO in the dust removal flue gas. x , the obtained desulfurized and denitrified flue gas is discharged into the atmosphere; (3) transporting the desulfurization and denitrification agent used in step (2) to a regeneration tower, regenerating the desulfurization and denitrification agent used by the heat energy recovered in step (1), and transporting the regenerated desulfurization and denitrification agent to the desulfurization and denitrification tower for recycling; The desulfurization and denitrification agent comprises the following components by weight: 18-30 parts of modified activated carbon, 15-25 parts of carboxymethyl starch, 12-25 parts of limestone, 10-20 parts of sodium humate, 8-15 parts of protein soil, 6-12 parts of magnesium chloride and 3-8 parts of polybutyl acetate; The preparation method of the modified activated carbon comprises the following steps: S1. The coke powder is crushed and passed through a 180-200 mesh sieve, immersed in a nitric acid solution for 2-4 days, washed with water, and then immersed in a potassium hydroxide solution for 12-18 days. After drying to a paste, it is calcined and activated under nitrogen protection for 1-5 hours, cooled, washed until neutral, filtered, and dried to obtain activated carbon; S2. Dispersing titanium dioxide in toluene and heating the mixture to 70-90° C. to obtain a mixed solution, then uniformly mixing 3-(isomethacryloyloxy)propyltrimethoxysilane, triethylamine, and toluene, and adding the mixture dropwise to the mixed solution, continuing the reaction for 20-30 hours, then centrifuging, and washing the precipitate with toluene, ethanol, and diethyl ether in sequence, and drying to obtain modified titanium dioxide; S3. Dissolve 1-allyl-3-methylimidazolium tetrafluoroborate in a mixed solution of deionized water and N,N-dimethylformamide, then add S1 activated carbon, heat and stir at 50-70°C for 20-30h, then add S2 modified titanium dioxide and initiator, react at 60-80°C under nitrogen protection, cool after completion, wash, filter, and dry to obtain modified activated carbon.

2. The flue gas desulfurization and denitrification treatment method according to claim 1, characterized in that: The weight ratio of modified activated carbon, protein soil and polybutyl acetate is (5-8): (1-3): 1; The weight ratio of sodium humate to magnesium chloride is (1-2):

1.

3. The flue gas desulfurization and denitrification treatment method according to claim 1, characterized in that: The concentration of the nitric acid solution in S1 is 5-8 mol / L, and the concentration of the potassium hydroxide solution is 8-12 mol / L.

4. The flue gas desulfurization and denitrification treatment method according to claim 1, characterized in that: The grafting rate of 3-(isomethacryloyloxy)propyltrimethoxysilane grafted onto the titanium dioxide surface in S2 is 15-20%.

5. The flue gas desulfurization and denitrification treatment method according to claim 1, characterized in that: The addition amount of 1-allyl-3-methylimidazolium tetrafluoroborate in S3 is 2-5 wt% of the activated carbon; The mass ratio of modified titanium dioxide to 1-allyl-3-methylimidazolium tetrafluoroborate is 1:(15-20).

6. The flue gas desulfurization and denitrification treatment method according to claim 1, characterized in that: The preparation method of the desulfurization and denitrification agent comprises the following steps: Step 1: Weigh 18-30 parts of modified activated carbon by weight, add 15-25 parts of carboxymethyl starch, 12-25 parts of limestone, 10-20 parts of sodium humate, 8-15 parts of protein soil, 6-12 parts of magnesium chloride and 3-8 parts of polybutyl acetate, mix thoroughly, then add water and stir evenly to obtain a premix; Step 2: The premix is ​​aged for 20-40 minutes, then placed into a molding die for cold pressing at a molding pressure of 20-30 MPa and a holding time of 20-40 seconds, and then demolded to obtain a molding material; Step 3: Cover the surface of the molding material with plastic wrap for maintenance. After maintenance at 15-25°C for 20-30 hours, remove the plastic wrap and dry it at 28-35°C for 40-50 hours to obtain the desulfurization and denitrification agent.

7. The flue gas desulfurization and denitrification treatment method according to claim 1, characterized in that: In step (1), the blowing pressure is 0.3-0.5 MPa.

8. The flue gas desulfurization and denitrification treatment method according to claim 1, characterized in that: In step (2), the dust removal flue gas air velocity is 500-1000m 3 / h, the mixed gas space velocity is 10000~20000m 3 / h.

9. The flue gas desulfurization and denitrification treatment method according to claim 1, characterized in that: In step (3), the regeneration temperature is 400-500°C and the time is 30-60 minutes.

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