A flue gas treatment process

Abstract

The present invention discloses a flue gas treatment process, belonging to the technical field of flue gas treatment. The process is as follows: The flue gas is introduced into the SCR reactor, and the flue gas is subjected to denitrification treatment by using ammonia and a denitrification catalyst to obtain denitrified flue gas; The denitrified flue gas enters the dust collector, and the denitrified flue gas is dust-removed by using a dust-removing filter bag to obtain dust-removed flue gas; Among them, a polymer film layer obtained by copolymerizing stearic acid ester, acryloyl ethylenediamine, and an amide compound of acryloyl chloride and γ-aminopropyltrialkoxysilane is attached to the surface of the dust-removing filter bag; And carbon nanotubes are grafted onto acryloyl ethylenediamine; The dust-removed flue gas is introduced into the desulfurization tower for desulfurization treatment and then led out for external discharge. By using the polymer film layer attached to the surface of the dust-removing filter bag, the waterproof, oil-proof and anti-static capabilities of the dust-removing filter bag are improved, and the occurrence of bag sticking phenomenon can be effectively prevented.

Description

Technical Field

[0001] The present invention relates to a flue gas treatment process, belonging to the technical field of flue gas treatment. Background Art

[0002] Selective Catalytic Reduction (SCR) refers to the process in which, under the action of a catalyst, a reducing agent (such as NH 3 ) selectively reacts with NO in the flue gas x and generates non-toxic and pollution-free N 2 and H 2 O. Selectivity means that during the flue gas denitrification process, the flue gas denitrification catalyst selectively reduces NO x to nitrogen, while SO in the flue gas 2 is rarely oxidized to SO 3 .

[0003] The flue gas after denitrification treatment contains a large amount of dust, which needs to be dust-removed, then desulfurized and discharged. However, water vapor is generated during the flue gas denitrification process. The existence of this water vapor will cause the dust to become more viscous. After contacting the dust removal filter bag, due to the strong intermolecular force, it will cover the surface of the dust removal filter bag, resulting in the occurrence of the bagging phenomenon; at the same time, the oily substances contained in the flue gas will also cause the bagging phenomenon after mixing with the dust; moreover, under the action of air flow or electric field, electrostatic interaction will occur between dust particles, making the particles more likely to adsorb on the surface of the dust removal filter bag, resulting in difficulty in being removed. Summary of the Invention

[0004] The purpose of the present invention is to provide a flue gas treatment process, which uses the polymer film layer attached to the surface of the dust removal filter bag to improve the waterproof, oil-proof and anti-static capabilities of the dust removal filter bag, and can effectively prevent the occurrence of the bagging phenomenon.

[0005] In order to achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0006] A flue gas treatment process has the following process:

[0007] S1. The flue gas is introduced into the SCR reactor, and the flue gas is denitrified by using ammonia and a denitrification catalyst to obtain the denitrified flue gas;

[0008] S2. The denitrified flue gas enters the dust collector, and the denitrified flue gas is dust-removed by using the dust removal filter bag to obtain the dust-removed flue gas;

[0009] Among them, a polymer film layer obtained by copolymerizing stearic acid ester, acryloyl ethylenediamine, and an amide compound of acryloyl chloride and γ-aminopropyltrialkoxysilane is attached to the surface of the dust removal filter bag; and carbon nanotubes are grafted on the acryloyl ethylenediamine;

[0010] S3. After dust removal, the flue gas is introduced into a desulfurization tower for desulfurization treatment and then discharged externally.

[0011] Preferably, the preparation method of the polymer in the polymer film layer comprises the following steps:

[0012] Step 1. Under a nitrogen atmosphere, acryloyl chloride and γ-aminopropyltrialkoxysilane are dispersed in a triethylamine solution, and stirred and heated for reaction to obtain an amide compound of acryloyl chloride and γ-aminopropyltrialkoxysilane;

[0013] Step 2. Stearyl acrylate and acryloyl ethylenediamine are continuously added into the reaction system of Step 1, and then an initiator is added dropwise and stirred and heated for reaction to obtain a polymer intermediate;

[0014] Step 3. A carboxyl-modified carbon nanotube solution is added into the reaction system of Step 2, and the reaction is continued to obtain a polymer;

[0015] Among them, the molar ratio of acryloyl chloride, γ-aminopropyltrialkoxysilane, triethylamine, stearyl acrylate, acryloyl ethylenediamine and the initiator is 1:(1-1.2):(0.2-0.5):(1-3):(1.5-2.5):(0.05-0.2);

[0016] The mass ratio of acryloyl ethylenediamine to the carboxyl-modified carbon nanotubes is 1:(1.1-1.3).

[0017] Preferably, the stearyl acrylate is vinyl stearate and / or allyl stearate;

[0018] The γ-aminopropyltrialkoxysilane is γ-aminopropyltrimethoxysilane and / or γ-aminopropyltriethoxysilane;

[0019] The initiator is AIBN.

[0020] Preferably, the solvents used in the triethylamine solution and the carboxyl-modified carbon nanotube solution are both DMF;

[0021] In the triethylamine solution, the content of triethylamine is 0.1-0.5 mol / L;

[0022] In the carboxyl-modified carbon nanotube solution, the content of the carboxyl-modified carbon nanotubes is 80-120 g / L.

[0023] Preferably, in Step 1, the conditions for the stirring and heating reaction are: 50-200 rpm, 40-50 °C, 2-5 h.

[0024] Preferably, in Step 2, the conditions for the stirring and heating reaction are: 100-300 rpm, 60-80 °C, 3-7 h.

[0025] Preferably, in the step 3, the reaction conditions are: 100 - 300 rpm, 60 - 80 °C, 1 - 3 h.

[0026] Preferably, the preparation method of the carboxyl - modified carbon nanotubes is as follows:

[0027] Mix carbon nanotubes, concentrated sulfuric acid, and concentrated nitric acid in a mass ratio of (1 - 5):(8 - 15):(2 - 5), then oscillate and mix at 30 - 70 °C for 3 - 5 h, and then obtain carboxyl - modified carbon nanotubes through filtration, washing, and drying.

[0028] Preferably, the preparation method of the dust - removing filter bag with a polymer film layer attached to the surface is as follows:

[0029] Disperse the polymer in water to form a 15 - 30% emulsion, then soak the fabric in the emulsion, impregnate and roll, with a liquor pick - up rate of 80 - 90%, and then bake at 110 - 125 °C for 3 - 5 min to obtain the treated fabric, and then obtain the dust - removing filter bag through cutting, sewing, and assembling.

[0030] Preferably, the raw material of the fabric is any one of polyester, aramid, PPS, PP, and PTFE.

[0031] The beneficial effects of the present invention are as follows:

[0032] The polymer film layer component contains a polymer copolymerized from stearic acid enol ester, acryloyl ethylenediamine, and an amide compound of acryloyl chloride and γ - aminopropyltrialkoxysilane. Among them, stearic acid enol ester, acryloyl ethylenediamine, and the amide compound of acryloyl chloride and γ - aminopropyltrialkoxysilane are copolymerized through carbon - carbon double bonds, and the free - radical copolymerization is non - selective copolymerization. Therefore, the C - C main long chain of the polymer, the long - chain alkyl branches in stearic acid enol ester, and the siloxane structure in the branches of the amide compound of acryloyl chloride and γ - aminopropyltrialkoxysilane can be fully dispersed in the polymer film layer to form a waterproof network; at the same time, after the polymer is dispersed in water and impregnated onto the dust - removing filter bag fabric, a polysiloxane structure with strong hydrogen - bond interaction with the dust - removing filter bag fabric will be formed, improving the adhesion effect.

[0033] The amide structure in acryloyl ethylenediamine, the amide structure formed between acryloyl ethylenediamine and carboxyl - modified carbon nanotubes, and the amide structure in the amide compound of acryloyl chloride and γ - aminopropyltrialkoxysilane have good oil - repellent effects. Also due to the non - selective copolymerization of free radicals, the amide structure will also be fully dispersed in the polymer film layer to form an oil - repellent network; and the carbon nanotubes grafted with acryloyl ethylenediamine will be fully dispersed in the polymer with acryloyl ethylenediamine to form a conductive network, improving the anti - static effect and being able to improve the thermal stability of the dust - removing filter bag. Detailed implementation manners

[0034] The present invention will be specifically introduced below in conjunction with embodiments.

[0035] Embodiment 1: This embodiment provides a flue gas treatment process, the process is as follows:

[0036] S1. Under the action of a induced draft fan, the flue gas is introduced into the SCR reactor, and ammonia is sprayed into the intake pipeline of the SCR reactor by using an ammonia injection system so that ammonia is mixed with the flue gas. Under the catalysis of the denitration catalyst in the SCR reactor, nitrogen oxides in the flue gas generate nitrogen and water, thereby reducing the content of nitrogen oxides in the flue gas, reducing the environmental pollution caused by the flue gas, and thus realizing denitration to obtain denitrified flue gas.

[0037] S2. The denitrified flue gas enters the dust collector under the action of the induced draft fan, and the denitrified flue gas is dust-removed by using a dust-removing filter bag to obtain dust-removed flue gas.

[0038] Since water vapor is generated during the flue gas denitration process, the existence of this water vapor will cause the dust viscosity to increase. After contacting with the dust-removing filter bag, due to the strong intermolecular force, it will cover the surface of the dust-removing filter bag, resulting in the occurrence of the phenomenon of bag blinding; at the same time, the oily substances contained in the flue gas will also cause the occurrence of the bag blinding phenomenon after being mixed with the dust; moreover, under the airflow, electrostatic interaction will occur between the dust particles, making the particles more likely to adsorb on the surface of the dust-removing filter bag, resulting in difficulty in being removed.

[0039] Therefore, in this embodiment, the dust-removing filter bag is subjected to a modification treatment, and a polymer film layer obtained by copolymerization of stearic acid vinyl ester, acryloyl ethylenediamine, and an amide compound of acryloyl chloride and γ-aminopropyltrimethoxysilane is attached to the surface of the dust-removing filter bag; and carbon nanotubes are grafted on the acryloyl ethylenediamine; the raw material of the fabric of the dust-removing filter bag is selected as polytetrafluoroethylene (PTFE).

[0040] Specifically, the preparation method of the dust-removing filter bag with a polymer film layer attached to the surface is as follows:

[0041] Step 1. Under a nitrogen atmosphere, 0.5 mol (68.25 g) of acryloyl chloride and 0.55 mol (136.07 g) of γ-aminopropyltrimethoxysilane are dispersed in a triethylamine solution (1 L of N,N-dimethylformamide (DMF) as the solvent; the addition amount of triethylamine is 10.21 g), and the reaction is carried out at 45 °C for 4 h at a stirring rate of 100 rpm to obtain an amide compound of acryloyl chloride and γ-aminopropyltrimethoxysilane.

[0042] Step 2: Continuously add 0.75 mol (165 g) of vinyl stearate and 0.75 mol (82.61 g) of acryloyl ethylenediamine into the reaction system of Step 1, then dropwise add 0.05 mol (8.2 g) of azobisisobutyronitrile (AIBN), and react at 80 °C with a rotation speed of 200 rpm for 5 h to obtain a polymer intermediate.

[0043] Step 3: Mix carbon nanotubes, concentrated sulfuric acid, and concentrated nitric acid in a mass ratio of 1:8:2, shake and mix at 50 °C for 4 h, then filter, wash (wash with water until neutral), and dry (at 70 °C for 3 h) to obtain carboxyl-modified carbon nanotubes; add the carboxyl-modified carbon nanotube solution (using 1 L of N,N-dimethylformamide (DMF) as the solvent; the addition amount of carboxyl-modified carbon nanotubes is 91 g) into the reaction system of Step 2, and continue to react at 80 °C with a rotation speed of 200 rpm for 2 h to obtain a polymer.

[0044] Step 4: Disperse the polymer obtained in Step 3 in water at 50 °C to prepare a 15% emulsion, then immerse the polytetrafluoroethylene fabric in the emulsion for 1 min, dip and squeeze twice, with a liquor pick-up rate of 85%, and then bake at 110 °C for 3 min to obtain the treated fabric. After cutting, sewing, and assembling, a dust removal filter bag with a polymer film layer attached to the surface is obtained.

[0045] S3: After dust removal, the flue gas is introduced into the desulfurization tower under the action of the induced draft fan for desulfurization treatment. Conventional desulfurization means can be used for the desulfurization treatment. After desulfurization, the flue gas is led out by the induced draft fan and discharged outside the chimney.

[0046] Example 2: It is basically the same as Example 1, except that the raw material of the fabric of the dust removal filter bag is selected as polyester, and the preparation method of the dust removal filter bag with a polymer film layer attached to the surface is also different.

[0047] Specifically, the preparation method of the dust removal filter bag with a polymer film layer attached to the surface in this example is as follows:

[0048] Step 1: Under a nitrogen atmosphere, disperse 0.5 mol (68.25 g) of acryloyl chloride and 0.6 mol (154.32 g) of γ-aminopropyltriethoxysilane in a triethylamine solution (using 1 L of N,N-dimethylformamide (DMF) as the solvent; the addition amount of triethylamine is 10.21 g), and react at 45 °C with a stirring rate of 100 rpm for 4 h to obtain an amide compound of acryloyl chloride and γ-aminopropyltriethoxysilane.

[0049] Step 2: Continuously add 1 mol (172.26 g) of allyl stearate and 0.75 mol (82.61 g) of acryloyl ethylenediamine into the reaction system of Step 1, then dropwise add 0.05 mol (8.2 g) of azobisisobutyronitrile (AIBN) and react at 80 °C with a rotation speed of 200 rpm for 5 h to obtain a polymer intermediate.

[0050] Step 3: Mix carbon nanotubes, concentrated sulfuric acid, and concentrated nitric acid in a mass ratio of 1:8:2, then shake and mix at 50 °C for 4 h, followed by filtration, washing (washed with water until neutral), and drying (70 °C, 3 h) to obtain carboxyl-modified carbon nanotubes; add the carboxyl-modified carbon nanotube solution (using 1 L of N,N-dimethylformamide (DMF) as the solvent; the addition amount of carboxyl-modified carbon nanotubes is 99 g) into the reaction system of Step 2, continue to react at 80 °C with a rotation speed of 200 rpm for 2 h to obtain a polymer.

[0051] Step 4: Disperse the polymer obtained in Step 3 in water at 50 °C to prepare a 20% emulsion, then soak the polyester fabric in the emulsion for 1 min, followed by two dips and two squeezes with a squeezing ratio of 90%, and then bake at 115 °C for 3 min to obtain a treated fabric. After cutting, sewing, and assembling, a dust removal filter bag with a polymer film layer attached to its surface is obtained.

[0052] Performance testing:

[0053] Water repellency: Measured on a Y(B)813 fabric water adhesion tester according to the AATCC-227 standard and method, and the average value of two measurements is taken. 0 points is the worst, and 100 points is the best.

[0054] Oil repellency: Tested according to the FZ / TO1067-1999 standard. Grade 8 is the best, and Grade 1 is the worst.

[0055] Antistatic performance: The fabric is tested by the surface charge density method in GB / T 12703.1-2008 "Evaluation of Electrostatic Properties of Textiles".

[0056] After cutting the dust removal filter bag fabrics used in Example 1 and Example 2 according to the above detection standards and / or methods, place them correspondingly in the emulsions obtained in Example 1 and Example 2 and perform the treatment process of the dust removal filter bag fabrics in Example 1 and Example 2. The obtained products are named 1# fabric and 2# fabric respectively, and the test results are shown in Table 1.

[0057] Table 1 Performance test results

[0058] Waterproof (classification) Oil-proof (grade) <![CDATA[Surface charge density (μC·m -2 )]]> Fabric No. 1 90 7 0.056 Fabric No. 2 100 7 0.068

[0059] As can be seen from the data in Table 1, the polymer provided by the present invention can endow the dust removal filter bag fabric with excellent waterproof, oil-proof and anti-static properties, thereby preventing dust from adhering to the surface of the dust removal filter bag and causing the phenomenon of bag clogging, and can extend the service life of the dust removal filter bag.

[0060] The above are only the preferred embodiments of the present invention patent. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention patent, several improvements and retouches can be made, and these improvements and retouches should also be regarded as the protection scope of the present invention patent.

Claims

1. A flue gas treatment process, characterized in that: The process is as follows: S1. Flue gas is introduced into the SCR reactor, and ammonia and a denitration catalyst are used to denitrate the flue gas to obtain denitrated flue gas; S2, the flue gas after denitration enters the dust collector, and the dust removal filter bag is used to remove dust from the flue gas after denitration to obtain dust-removed flue gas; The surface of the dust filter bag is attached with a polymer film layer obtained by copolymerization of stearic acid ethylenediamine, acryloyl chloride and γ-aminopropyltrialkoxysilane amidate; and carbon nanotubes are grafted on the acryloylethylenediamine; S3. The flue gas after dust removal is introduced into the desulfurization tower for desulfurization treatment and then discharged to the outside.

2. A flue gas treatment process according to claim 1, characterized in that: The method for preparing the polymer in the polymer film layer comprises the following steps: Step 1, under a nitrogen atmosphere, dispersing acryloyl chloride and γ-aminopropyltrialkoxysilane in a triethylamine solution, stirring and heating to react, to obtain an amidate of acryloyl chloride and γ-aminopropyltrialkoxysilane; Step 2, continue to add stearic acid ethylenediamine and acryloylethylenediamine into the reaction system of step 1, then dropwise add initiator and stir and heat to react to obtain a polymer intermediate; Step 3, adding the carboxyl-modified carbon nanotube solution into the reaction system of step 2, and continuing the reaction to obtain a polymer; Wherein, the molar ratio of acryloyl chloride, γ-aminopropyltrialkoxysilane, triethylamine, stearic acid ethyl ester, acryloylethylenediamine and initiator is 1:(1-1.2):(0.2-0.5):(1-3):(1.5-2.5):(0.05-0.2); The mass ratio of acrylamide to carboxyl-modified carbon nanotubes is 1:(1.1-1.3).

3. A flue gas treatment process according to claim 2, characterized in that: The stearic acid olefin ester is vinyl stearate and / or allyl stearate; The γ-aminopropyltrialkoxysilane is γ-aminopropyltrimethoxysilane and / or γ-aminopropyltriethoxysilane; The initiator is AIBN.

4. A flue gas treatment process according to claim 2, characterized in that: The solvents used in the triethylamine solution and the carboxyl-modified carbon nanotube solution are both DMF; and In the triethylamine solution, the content of triethylamine is 0.1~0.5mol / L; In the carboxyl-modified carbon nanotube solution, the content of the carboxyl-modified carbon nanotube is 80-120 g / L.

5. A flue gas treatment process according to claim 2, characterized in that: In the step 1, the stirring and heating reaction conditions are: 50-200 rpm, 40-50° C., 2-5 h.

6. A flue gas treatment process according to claim 2, characterized in that: In step 2, the stirring and heating reaction conditions are: 100-300 rpm, 60-80° C., 3-7 h.

7. A flue gas treatment process according to claim 2, characterized in that: In the step 3, the reaction conditions are: 100-300 rpm, 60-80° C., 1-3 h.

8. A flue gas treatment process according to claim 4, characterized in that: The preparation method of carboxyl-modified carbon nanotubes is as follows: Carbon nanotubes, concentrated sulfuric acid and concentrated nitric acid are mixed in a mass ratio of (1-5):(8-15):(2-5), and then shaken and mixed at 30-70°C for 3-5 hours, filtered, washed and dried to obtain carboxyl-modified carbon nanotubes.

9. A flue gas treatment process according to claim 2, characterized in that: The preparation method of the dust removal filter bag with a polymer film layer attached to the surface is as follows: The polymer is dispersed in water to prepare a 15-30% emulsion, and then the cloth is immersed in the emulsion, dipped and rolled, the rolling rate is 80-90%, and then baked at 110-125℃ for 3-5min to obtain the treated cloth, and then cut, sewed and assembled to obtain the dust filter bag.

10. A flue gas treatment process according to claim 9, characterized in that: The raw material of the cloth is any one of polyester, aramid, PPS, PP and PTFE.