CN113117477A - Integrated process for treating flue gas and preparing cementing material - Google Patents

Integrated process for treating flue gas and preparing cementing material Download PDF

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CN113117477A
CN113117477A CN201911397046.0A CN201911397046A CN113117477A CN 113117477 A CN113117477 A CN 113117477A CN 201911397046 A CN201911397046 A CN 201911397046A CN 113117477 A CN113117477 A CN 113117477A
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flue gas
weight
parts
chlorine dioxide
fluidized bed
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童裳慧
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Environment Sustainable System Engineering Tech Co Ltd
Environment Sustainable System Engineering Technology Co Ltd
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Environment Sustainable System Engineering Tech Co Ltd
Environment Sustainable System Engineering Technology Co Ltd
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
    • B01D53/34—Chemical or biological purification of waste gases
    • B01D53/46—Removing components of defined structure
    • B01D53/60—Simultaneously removing sulfur oxides and nitrogen oxides
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
    • B01D53/34—Chemical or biological purification of waste gases
    • B01D53/74—General processes for purification of waste gases; Apparatus or devices specially adapted therefor
    • B01D53/75—Multi-step processes
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
    • B01D53/34—Chemical or biological purification of waste gases
    • B01D53/74—General processes for purification of waste gases; Apparatus or devices specially adapted therefor
    • B01D53/76—Gas phase processes, e.g. by using aerosols
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
    • B01D53/34—Chemical or biological purification of waste gases
    • B01D53/74—General processes for purification of waste gases; Apparatus or devices specially adapted therefor
    • B01D53/81—Solid phase processes
    • B01D53/83—Solid phase processes with moving reactants
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B7/00—Hydraulic cements
    • C04B7/24—Cements from oil shales, residues or waste other than slag
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B7/00—Hydraulic cements
    • C04B7/24—Cements from oil shales, residues or waste other than slag
    • C04B7/243—Mixtures thereof with activators or composition-correcting additives, e.g. mixtures of fly ash and alkali activators
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B7/00—Hydraulic cements
    • C04B7/36—Manufacture of hydraulic cements in general
    • C04B7/38—Preparing or treating the raw materials individually or as batches, e.g. mixing with fuel
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2258/00—Sources of waste gases
    • B01D2258/02—Other waste gases
    • B01D2258/0283—Flue gases
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P40/00—Technologies relating to the processing of minerals
    • Y02P40/10—Production of cement, e.g. improving or optimising the production methods; Cement grinding

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Environmental & Geological Engineering (AREA)
  • Ceramic Engineering (AREA)
  • Biomedical Technology (AREA)
  • Analytical Chemistry (AREA)
  • General Chemical & Material Sciences (AREA)
  • Oil, Petroleum & Natural Gas (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Health & Medical Sciences (AREA)
  • Materials Engineering (AREA)
  • Structural Engineering (AREA)
  • Organic Chemistry (AREA)
  • Dispersion Chemistry (AREA)
  • Treating Waste Gases (AREA)

Abstract

The invention discloses an integrated process for treating flue gas and preparing a cementing material. The process comprises the following steps: reacting chlorate aqueous solution, hydrogen peroxide and sulfuric acid aqueous solution in a chlorine dioxide generator to obtain chlorine dioxide; mixing chlorine dioxide and air to obtain an oxidant, and contacting the oxidant and the pre-dedusting flue gas in a flue gas pipeline before the oxidant and the pre-dedusting flue gas enter a fluidized bed absorption tower to obtain first treated flue gas; introducing the first treated flue gas into a fluidized bed absorption tower, contacting with absorbent dry powder sprayed into the fluidized bed absorption tower, and spraying water into the fluidized bed absorption tower to obtain second treated flue gas, wherein the second treated flue gas is filtered to obtain ash and purified flue gas; wherein the absorbent dry powder comprises fly ash and an alkali activator; mixing raw materials containing ash, mineral powder, fly ash and an additive to form the cementing material. The process disclosed by the invention can be used for efficiently desulfurizing and denitrating and preparing the cementing material with excellent performance.

Description

Integrated process for treating flue gas and preparing cementing material
Technical Field
The invention relates to an integrated process for treating flue gas and preparing a cementing material.
Background
Currently, the removal efficiency of sulfur dioxide in flue gas treatmentHigher, but NOxThe removal efficiency of (2) is difficult to be improved all the time, and the main difficulty is the removal of NO. The oxidation method is a method for removing NO in the flue gas by using a common method. In the prior art, researchers have used different oxidants for NO removal, with chlorine dioxide being favored for its strong oxidizing properties. However, chlorine dioxide is generally used as an oxidizing agent in the form of an aqueous solution, so that the using amount is large, water resources are wasted, and the oxidizing effect is difficult to control.
In the flue gas treatment process, a large amount of ash slag is easily generated, the resource utilization of the ash slag is a hot point of the current domestic and foreign research, and the material composition and the performance of the ash slag are changed due to the difference of the desulfurization process and the coal type of the combustion flue gas. The main applications of ash include: recovery of lime, mineral wool, production of cement, silica-calcium bricks, artificial gravel, road construction, soil stabilization and improvement, neutralization of mine sewage, concrete admixtures, concrete blocks, recovery of sulfur, and the like. The preparation of inorganic cementitious materials using ash is an important development trend.
CN104307351B discloses a method for synthesizing alpha-olefin with O3The method for denitration of the oxidant comprises the steps of enabling ozone generated by an ozone generator and cold air generated by a dilution fan to enter a mixing tank to be mixed, spraying the mixture into a flue through an ozone distributor, and oxidizing NO in flue gas into high-valence nitrogen oxide. The process has high cost, if the process is not regulated, the oxidant is greatly wasted, the desulfurization and denitrification efficiency is reduced, and the cost of a denitrification system is increased.
CN104028103A discloses a method for simultaneously desulfurizing and denitrating flue gas after catalytic oxidation by liquid-phase chlorine dioxide. The chlorine dioxide aqueous solution is generated by a chlorine dioxide preparation device, the concentration of the chlorine dioxide aqueous solution is 0.0015-0.015 mol/L, and the chlorine dioxide aqueous solution is sprayed in the absorption tower to oxidize NO in the flue gas, but the concentration of the chlorine dioxide is low, the spraying amount is large, the tower volume and the early-stage equipment investment are increased, and the difficulty in process implementation is increased.
CN101973723A discloses a process and a device for preparing an inorganic cementing material by using desulfurization and denitrification byproducts generated by desulfurization treatment of flue gas of a coal-fired power plant as main materials and slag, gypsum and cement clinker as admixtures, wherein the preparation process does not need high-temperature calcination treatment, can greatly reduce energy consumption and is beneficial to the protection and improvement of ecological environment; however, raw materials such as cement clinker, gypsum and the like in the formula of the method are greatly required in the preparation process, so that the preparation cost is increased; and the performance of the prepared gelled material is poor.
Disclosure of Invention
In view of the above, an object of the present invention is to provide an integrated process for flue gas treatment and cementing material preparation, which can efficiently desulfurize and denitrate and can prepare cementing materials with excellent performance. The invention adopts the following technical scheme to achieve the purpose.
The invention provides an integrated process for treating flue gas and preparing a cementing material, which comprises the following steps:
(1) reacting chlorate aqueous solution, hydrogen peroxide and sulfuric acid aqueous solution in a chlorine dioxide generator to obtain chlorine dioxide;
(2) mixing chlorine dioxide with air to obtain an oxidant; pre-dedusting raw flue gas to obtain pre-dedusted flue gas; contacting an oxidant and the pre-dedusting flue gas in a flue gas pipeline before entering a fluidized bed absorption tower to obtain first treated flue gas; wherein the volume fraction of chlorine dioxide in the oxidant is 4-10 vol%, and the molar ratio of chlorine dioxide in the oxidant introduced in unit time to nitric oxide in the raw flue gas introduced in unit time is 1.1-3;
(3) introducing the first treated flue gas into a fluidized bed absorption tower, contacting with absorbent dry powder sprayed into the fluidized bed absorption tower, and spraying water into the fluidized bed absorption tower to obtain second treated flue gas, wherein the second treated flue gas is filtered to obtain ash and purified flue gas; wherein the absorbent dry powder comprises 30-50 parts by weight of fly ash and 40-60 parts by weight of alkali activator;
(4) mixing raw materials comprising 30-70 parts by weight of ash, 20-50 parts by weight of mineral powder, 0-30 parts by weight of fly ash and 2-10 parts by weight of additive to form the cementing material.
According to the process of the present invention, preferably, in step (1), chlorine dioxide is obtained by: adding chlorate solution, hydrogen peroxide solution and sulfuric acid solution in dioxygenReacting in a chlorine generator at 50-90 ℃ to obtain chlorine dioxide; wherein the concentration of sodium chlorate in the chlorate aqueous solution is 15-40 wt%, and the concentration of hydrogen peroxide is 25-38 wt%; the concentration of the sulfuric acid aqueous solution is 30-60 wt%; sodium chlorate in aqueous chlorate solution, hydrogen peroxide in hydrogen peroxide and H in aqueous sulfuric acid solution2SO4The molar ratio of (A) to (B) is 1: 0.55-1: 0.5-1.
According to the process provided by the invention, preferably, in the step (2), the sulfur content in the raw flue gas is 600-4000 mg/Nm3(ii) a The nitrogen content is 200-600 mg/Nm3(ii) a Oxygen content is 5-23 wt%; moisture content is 5-12 wt%;
the flow velocity of the pre-dedusting flue gas in the flue gas pipeline is 6-15 m/s; the contact time of the pre-dedusting flue gas and the oxidant in the flue gas pipeline is 1-3 s.
According to the process, preferably, in the step (3), the flow speed of the first treated flue gas in the fluidized bed absorption tower is 2-5 m/s; the contact time of the first treated flue gas and the absorbent dry powder in the fluidized bed absorption tower is 1-6 s.
According to the process of the present invention, preferably, in the step (3), the absorbent dry powder is prepared by the following method: reacting fly ash, an alkali activator and water at 50-80 ℃ for 5-20 h, and drying and grinding the obtained product to obtain absorbent dry powder with the particle size of 150-350 meshes.
According to the process of the invention, in the step (3), the ratio of the total weight of the fly ash and the alkali-activator to the weight of the water is preferably 1: 10-20.
According to the process of the present invention, preferably, in the step (3), the alkali activator is calcium hydroxide and/or calcium oxide.
According to the process of the present invention, preferably, in the step (3), the fly ash comprises 20 to 60 parts by weight of silica, 20 to 40 parts by weight of alumina and 1 to 20 parts by weight of calcium oxide based on 100 parts by weight of fly ash.
According to the process of the present invention, preferably, in the step (4), the additive is potassium hydroxide and/or sodium hydroxide.
According to the process, raw materials comprising 30-70 parts by weight of ash, 20-50 parts by weight of mineral powder, 0-30 parts by weight of fly ash and 2-10 parts by weight of additives are preferably mixed to form the cementing material.
The desulfurization efficiency of the flue gas treated by the process reaches over 99.7 percent, the denitration efficiency reaches over 96 percent, and the obtained cementing material meets the national standard. Furthermore, the invention has low operation cost and is green and environment-friendly.
Detailed Description
The present invention will be further described with reference to the following specific examples, but the scope of the present invention is not limited thereto.
The integrated process of the invention simultaneously comprises a flue gas treatment process and a cementing material preparation process, and the flue gas treatment process and the cementing material preparation process are tightly combined. The integration can be realized only by adjusting the flue gas treatment process parameters and the cementing material preparation process parameters, so that the method is different from the common independent flue gas treatment process and the common independent cementing material preparation process.
The integrated process for treating the smoke and preparing the cementing material comprises the following steps: (1) preparing chlorine dioxide; (2) an oxidation step; (3) a desulfurization and denitrification step; and (4) a step of preparing a cement; as described in detail below.
< preparation of chlorine dioxide step >
The chlorate solution, hydrogen peroxide and sulfuric acid solution react in a chlorine dioxide generator to obtain chlorine dioxide.
The chlorate can be selected from one of sodium chlorate, potassium chlorate and magnesium chlorate; preferably, the chlorate is selected from one of sodium chlorate or potassium chlorate; more preferably, the chlorate salt is sodium chlorate. The chlorate solution may have a sodium chlorate concentration of 15 to 40 wt%, preferably 25 to 40 wt%, more preferably 25 to 35 wt%. The concentration of the aqueous sulfuric acid solution may be 30 to 60 wt%, preferably 45 to 60 wt%, and more preferably 50 to 60 wt%. The concentration of the hydrogen peroxide can be 25-38 wt%, preferably 26-37 wt%, and more preferably 27-36 wt%. Sodium chlorate in aqueous chlorate solution, hydrogen peroxide in hydrogen peroxide and H in aqueous sulfuric acid solution2SO4The molar ratio of (A) to (B) is 1:0.55 to 1:0.5 to 1, preferably 1:0.55 to 1:0.51: 0.6-1, more preferably 1: 0.7-1. The reaction temperature in the chlorine dioxide generator is 50-90 ℃, preferably 60-80 ℃, and more preferably 70-80 ℃. By adopting the molar ratio and the reaction temperature range, the generation rate of the chlorine dioxide can be controlled, and the purity of the generated chlorine dioxide is improved; further, the safety factor of chlorine dioxide generation is improved.
In the present invention, the concentration of hydrogen peroxide may be 27.5 wt% or 35 wt%. By adopting the hydrogen peroxide with the concentration range, the reaction rate can be controlled, and the safety of producing chlorine dioxide is improved.
According to one embodiment of the invention, chlorine dioxide is obtained by: adding a chlorate aqueous solution, hydrogen peroxide and a sulfuric acid aqueous solution into a chlorine dioxide generator, and reacting at 70-80 ℃ to obtain chlorine dioxide; wherein the concentration of the sodium chlorate aqueous solution is 25-35 wt%, and the concentration of the hydrogen peroxide is 27-36 wt%; the concentration of the sulfuric acid aqueous solution is 50-60 wt%; sodium chlorate in aqueous chlorate solution, hydrogen peroxide in hydrogen peroxide and H in aqueous sulfuric acid solution2SO4The molar ratio of (A) to (B) is 1: 0.7-1.
The method is adopted to prepare the chlorine dioxide, the air is added into the chlorine dioxide generator and mixed with the generated chlorine dioxide to form the oxidant, and then the oxidant is output through the induced draft fan.
< Oxidation step >
Pre-dedusting the raw flue gas to obtain pre-dedusted flue gas. And (3) contacting the oxidant and the pre-dedusting flue gas in a flue gas pipeline before entering the fluidized bed absorption tower to obtain first treated flue gas.
In the invention, the dust content of the original smoke can be 80-200 mg/Nm3Preferably 100 to 150mg/Nm3More preferably 120 to 150mg/Nm3. According to one embodiment of the invention, the raw flue gas is subjected to pre-dedusting treatment by an electrostatic precipitator before being introduced into the flue gas pipeline, so as to obtain pre-dedusting flue gas, and then the pre-dedusting flue gas is introduced into the flue gas pipeline. The dust removal efficiency is 90-80 wt%. By adopting the pre-dedusting treatment, the dust in the original flue gas can be controlled within a range, the desulfurization and denitrification effects are improved, and the dust is avoidedAffecting the performance of the ash. The molar ratio of chlorine dioxide in the oxidant introduced in unit time to nitric oxide in the raw flue gas introduced in unit time can be 1-3, preferably 1.2-2, and more preferably 1.5-1.8. By adopting the molar ratio, the oxidation rate of nitric oxide can be improved on the basis of saving the using amount of chlorine dioxide, and further the denitration efficiency is improved. The volume fraction of chlorine dioxide in the oxidant may be 4 to 10 vol%, preferably 5 to 8 vol%, and more preferably 7 to 8 vol%. By adopting the proportion of the oxidant, the oxidation rate of nitric oxide can be improved, and the usage amount of the oxidant is reduced.
The sulfur content (sulfur dioxide content) in the raw flue gas can be 600-4000 mg/Nm3Preferably 1000 to 3000mg/Nm3More preferably 1500 to 2500mg/Nm3. The nitrogen content (nitrogen content is nitrogen monoxide content) in the original flue gas can be 200-600 mg/Nm3Preferably 200 to 400mg/Nm3More preferably 220 to 250mg/Nm3. The oxygen content in the original flue gas can be 5-23 wt%, preferably 10-20 wt%, and more preferably 15-20 wt%. The moisture content in the original flue gas can be 5-12 wt%, preferably 8-12 wt%, and more preferably 10-12 wt%. By adopting the sulfur content, nitrogen content, oxygen content and moisture content of the flue gas, the desulfurization and denitrification effects of the flue gas can be improved.
The flow velocity of the pre-dedusting flue gas in the flue gas pipeline can be 6-15 m/s, preferably 8-15 m/s, and more preferably 10-12 m/s. In addition, the contact time of the oxidant and the pre-dedusting flue gas in the flue gas pipeline can be 1-3 s. By controlling the flow rate of the pre-dedusting flue gas within the range, the oxidation rate of nitric oxide in the pre-dedusting flue gas is ensured, and the treatment rate can be ensured.
< desulfurization and denitration step >
And introducing the first treated flue gas into a fluidized bed absorption tower, contacting with absorbent dry powder sprayed into the fluidized bed absorption tower, spraying water into the fluidized bed absorption tower to obtain second treated flue gas, and filtering the second treated flue gas to obtain ash and purified flue gas. In the present invention, the absorbent dry powder includes fly ash and an alkali activator. In certain embodiments, absorptionThe dry powder of the agent is obtained by simply heating the fly ash and the alkali activator in the presence of water vapor. The surface characteristics of the fly ash excited by the alkali activator are changed, the formed absorbent dry powder has enhanced adsorptivity, the specific surface area is increased, the active sites are increased, and the desulfurization and denitrification efficiency is obviously improved; fe contained in fly ash3+And Mg2+And the catalyst also has a catalytic action on desulfurization and denitrification reactions, and further helps to improve desulfurization and denitrification efficiency.
The weight part of the fly ash can be 30-50 parts, preferably 40-50 parts, and more preferably 40-45 parts. The alkali activator may be present in an amount of 40 to 60 parts by weight, preferably 50 to 60 parts by weight, and more preferably 50 to 55 parts by weight. By adopting the absorbent with the proportion, the efficiency of absorbing high-valence nitrogen oxides and sulfur dioxide in the oxidized flue gas by the absorbent can be improved.
The alkali activator is calcium hydroxide and/or calcium oxide, preferably one of calcium hydroxide and calcium oxide, and more preferably calcium hydroxide. When the alkali activator contains calcium hydroxide, the purity of the calcium hydroxide is 70 to 95 wt%, preferably 75 to 90 wt%, and more preferably 80 to 90 wt%. When the alkali activator contains calcium oxide, the purity of the calcium oxide is 70 to 95 wt%, preferably 75 to 90 wt%, and more preferably 80 to 90 wt%.
Mixing the fly ash and an alkali activator, humidifying by water vapor, heating for a period of time, and drying and grinding the obtained product to obtain the absorbent dry powder. The particle size of the absorbent dry powder can be 150-350 meshes, preferably 200-350 meshes, and more preferably 200-300 meshes. By adopting the absorbent dry powder with the particle size range, the desulfurization and denitrification effects can be improved.
Specifically, fly ash, an alkali activator and water are reacted, and the obtained product is dried and ground to obtain absorbent dry powder. The weight ratio of the total weight of the fly ash and the alkali activator to the weight of the water can be 10-20: 1, preferably 12-18: 1, and more preferably 12-15: 1. The reaction temperature may be 50 to 80 ℃, preferably 60 to 80 ℃, and more preferably 65 to 75 ℃. The reaction time can be 5-20 h, preferably 8-18 h, and more preferably 10-15 h. The absorbent prepared by adopting the preparation conditions has stronger adsorption performance.
The fly ash of the present invention comprises 20 to 60 parts by weight of silicon dioxide, 20 to 40 parts by weight of aluminum oxide and 2 to 20 parts by weight of calcium oxide, based on 100 parts by weight of the fly ash. According to an embodiment of the present invention, the fly ash comprises 30 to 60 parts by weight of silicon dioxide, 30 to 40 parts by weight of aluminum oxide and 1 to 20 parts by weight of calcium oxide. According to still another embodiment of the present invention, the fly ash comprises 60 parts by weight of silica, 35 parts by weight of alumina and 1.6 parts by weight of calcium oxide.
The flow velocity of the first treated flue gas in the fluidized bed absorption tower can be 2-5 m/s, preferably 3-5 m/s, and more preferably 3-4 m/s. The contact time of the first treated flue gas and the absorbent dry powder in the fluidized bed absorption tower can be 1-6 s, preferably 2-5 s, and more preferably 3-4 s.
The molar ratio Ca/S of the calcium element contained in the absorbent dry powder introduced in unit time to the sulfur element contained in the raw flue gas introduced in unit time is 1.1-1.5, preferably 1.2-1.5, and more preferably 1.2-1.3. By adopting the Ca/S molar ratio, the desulfurization efficiency is improved on the basis of saving the cost.
The molar ratio of the calcium element contained in the absorbent dry powder introduced in unit time to the nitrogen element contained in the raw flue gas introduced in unit time is Ca/N, and the Ca/N is 0.5-1.2, preferably 0.5-1.0, and more preferably 0.6-0.8. By adopting the Ca/N molar ratio, the denitration efficiency is improved on the basis of saving the cost.
The temperature of the first treated flue gas at the inlet of the fluidized bed absorption tower can be 110-200 ℃, preferably 110-180 ℃, and more preferably 120-150 ℃.
According to a specific embodiment of the invention, the filter device is a bag-type dust remover arranged at the top of the fluidized bed absorption tower, the second treatment flue gas is dedusted by the bag-type dust remover, the obtained purified flue gas is discharged from a chimney, and the obtained ash residue is conveyed to a byproduct storage tank or sprayed into the fluidized bed absorption tower for recycling.
< preparation of cementitious Material >
Mixing the raw materials of ash, mineral powder, fly ash and an additive to form the cementing material. In certain embodiments, the raw materials consist only of ash, mineral fines, fly ash, and additives. Specifically, the ash may be 30 to 70 parts by weight, preferably 40 to 60 parts by weight, and more preferably 45 to 55 parts by weight. The amount of the ore powder is 20 to 50 parts by weight, preferably 25 to 40 parts by weight, and more preferably 25 to 35 parts by weight. The fly ash may be 0 to 30 parts by weight, preferably 10 to 25 parts by weight, and more preferably 15 to 20 parts by weight. The additive can be 2 to 10 parts by weight, preferably 3 to 8 parts by weight, and more preferably 4 to 6 parts by weight.
In the invention, the fly ash is selected from one or two of primary fly ash and secondary fly ash, and is preferably primary fly ash. The admixture may be potassium hydroxide and/or sodium hydroxide, preferably potassium hydroxide or sodium hydroxide, more preferably sodium hydroxide. The ore powder can be one or more of S105, S95 and S75 grade ore powder, preferably one or two of S105 and S95 grade ore powder, and more preferably S105 grade ore powder.
The ash slag is ground powder; the particle size is 150 to 500 mesh, preferably 200 to 400 mesh, and more preferably 300 to 350 mesh. In the invention, the mineral powder, the fly ash and the additive are all ground powder; the particle size is 150 to 500 mesh, preferably 200 to 400 mesh, and more preferably 300 to 350 mesh.
According to an embodiment of the invention, the particle sizes of the ash, the mineral powder, the fly ash and the additive are all 150-500 meshes, preferably 200-400 meshes, and more preferably 300-350 meshes.
In the invention, firstly, grinding the ash on a double-roller grinding machine to obtain ash powder with the particle size of 300-350 meshes; grinding the mixture of S105-grade mineral powder, the first-grade fly ash and sodium hydroxide on a double-roller grinder to obtain a mixed ground substance with the particle size of 300-350 meshes; then adding the ash powder into a horizontal ribbon mixer, adding the mixed and ground product, and mixing to obtain a gel material; and finally, packaging the gel material through a full-automatic packaging machine.
The test method is described below:
the properties of the cementitious materials were determined according to GB175-2007 Universal Portland Cement.
Example 1
And conveying the aqueous solution of sodium chlorate, hydrogen peroxide and the aqueous solution of sulfuric acid to a chlorine dioxide generator for reaction to obtain chlorine dioxide, and mixing the chlorine dioxide with air introduced into the chlorine dioxide generator to obtain an oxidant. Inputting an oxidant into a flue gas pipeline through an induced draft fan; and (3) dedusting the original flue gas by an electrostatic precipitator to obtain pre-dedusted flue gas, introducing the pre-dedusted flue gas into a flue gas pipeline, and contacting the pre-dedusted flue gas with an oxidant in the flue gas pipeline to obtain first treated flue gas.
And introducing the first treated flue gas into a fluidized bed absorption tower, contacting the first treated flue gas with the sprayed absorbent dry powder, and spraying water into the fluidized bed absorption tower to obtain second treated flue gas.
The above method was applied to 90m2In the flue gas treatment project of the sintering machine, the operation parameters are shown in table 1. The obtained second treated flue gas is dedusted by a bag-type dust remover at the top of the fluidized bed absorption tower to obtain ash and purified flue gas; wherein the parameters of the purified flue gas obtained are shown in table 2.
TABLE 1
Parameter(s) Numerical value Unit of
Flue gas flow at inlet of flue gas pipeline (Standard condition) 400000 Nm3/h
Temperature of first treated flue gas at inlet of fluidized bed absorption tower 120 ℃
SO in raw flue gas2In an amount of 2100 mg/Nm3
Content of NO in raw flue gas 250 mg/Nm3
Moisture content of raw flue gas 10 ％
Oxygen content of original smoke 18 ％
Dust content of raw flue gas 120 mg/Nm3
Flue gas velocity in flue gas duct 12 m/s
Flue gas velocity in fluidized bed absorption tower 3.8 m/s
Aqueous sodium chlorate solution 30 wt％
Hydrogen peroxide solution 27.5 wt％
Aqueous sulfuric acid solution 60 wt％
Sodium chlorate, hydrogen peroxide, H2SO4In a molar ratio of 1:0.7:0.7 -
Chlorine dioxide generator reaction temperature 45 ℃
Chlorine dioxide in volume fraction of oxidant 8 vol％
ClO in flue gas pipeline2Molar ratio of NO 1.2 -
Ca/S molar ratio 1.3 -
Ca/N molar ratio 0.6 -
The ratio of the total weight of the fly ash and the alkali activator to the weight of the water 15:1 -
Reaction time in preparation of absorbent dry powder 15 h
Reaction temperature in preparation of absorbent dry powder 75 ℃
Silicon dioxide in fly ash: aluminum oxide: mass ratio of calcium oxide 60:35:1.6 -
Purity of calcium hydroxide 90 wt％
Particle size of absorbent dry powder 200～300 Eyes of a user
TABLE 2
Item Number of Unit of
Exhaust gas temperature 65 ℃
Efficiency of desulfurization 99.7 ％
Denitration efficiency 96.1 ％
The obtained ash and other raw material components were added to a horizontal ribbon mixer in the parts by weight shown in table 3 below and mixed to obtain a cement. The obtained cementing material is poured and molded in a template with the thickness of 40mm multiplied by 160mm, and the performance of the cementing material is tested according to GB175-2007 general Portland Cement, and the performance is shown in Table 4.
TABLE 3
Raw materials Parts by weight
Ash and slag 30
First grade fly ash 30
Mineral powder 30
Sodium hydroxide 5
TABLE 4
Age of age Compressive strength Flexural strength Unit of
3d 28 4.2 MPa
7d 35 6 MPa
28d 62 9.8 MPa
Example 2
The clinker obtained in example 1 was mixed with other raw materials in the following weight proportions as shown in Table 5, and the remaining parameters were the same as those of example 1, to obtain a cement having the properties as shown in Table 6.
TABLE 5
Raw materials Parts by weight
Ash and slag 50
First grade fly ash 20
Mineral powder 30
Sodium hydroxide 5
TABLE 6
Age of age Compressive strength Flexural strength Unit of
3d 34 5.3 MPa
7d 47 7.1 MPa
28d 77 11.4 MPa
Comparative example 1
The clinker obtained in example 1 was mixed with other raw materials in the following weight proportions as shown in Table 7, and the remaining parameters were the same as those of example 1, to obtain a cement having the properties as shown in Table 8.
TABLE 7
Raw materials Parts by weight
Ash and slag 80
First grade fly ash 20
Mineral powder 30
Sodium hydroxide 5
TABLE 8
Age of age Compressive strength Flexural strength Unit of
3d 24 4.6 MPa
7d 34 5.9 MPa
28d 61 8.9 MPa
Comparative example 2
The operating parameters were the same as in example 1 except for the operating parameters shown in Table 9 below, and the purified flue gas parameters obtained in this comparative example are shown in Table 10.
TABLE 9
Parameter(s) Numerical value
ClO2Molar ratio of NO 3.2
Watch 10
Item Number of Unit of
Exhaust gas temperature 65 ℃
Efficiency of desulfurization 99.2 ％
Denitration efficiency 94.7 ％
Continued increase of ClO2The molar ratio of NO, the desulfurization efficiency and the denitration efficiency are not obviously increased, but the operation cost and the system load are increased.
Comparative example 3
The operating parameters were the same as in example 1 except for the operating parameters in Table 11 below, and the purified flue gas parameters obtained are shown in Table 12.
TABLE 11
Parameter(s) Numerical value
ClO2Molar ratio of NO 0.6
TABLE 12
Item Number of Unit of
Exhaust gas temperature 65 ℃
Efficiency of desulfurization 99.3 ％
Denitration efficiency 88.6 ％
The present invention is not limited to the above-described embodiments, and any variations, modifications, and substitutions which may occur to those skilled in the art may be made without departing from the spirit of the invention.

Claims (10)

1. An integrated process for treating flue gas and preparing a cementing material is characterized by comprising the following steps:
(1) reacting chlorate aqueous solution, hydrogen peroxide and sulfuric acid aqueous solution in a chlorine dioxide generator to obtain chlorine dioxide;
(2) mixing chlorine dioxide with air to obtain an oxidant; pre-dedusting raw flue gas to obtain pre-dedusted flue gas; contacting an oxidant and the pre-dedusting flue gas in a flue gas pipeline before entering a fluidized bed absorption tower to obtain first treated flue gas; wherein the volume fraction of chlorine dioxide in the oxidant is 4-10 vol%, and the molar ratio of chlorine dioxide in the oxidant introduced in unit time to nitric oxide in the raw flue gas introduced in unit time is 1-3;
(3) introducing the first treated flue gas into a fluidized bed absorption tower, contacting with absorbent dry powder sprayed into the fluidized bed absorption tower, and spraying water into the fluidized bed absorption tower to obtain second treated flue gas, wherein the second treated flue gas is filtered to obtain ash and purified flue gas; wherein the absorbent dry powder comprises 30-50 parts by weight of fly ash and 40-60 parts by weight of alkali activator;
(4) mixing raw materials comprising 30-70 parts by weight of ash, 20-50 parts by weight of mineral powder, 0-30 parts by weight of fly ash and 2-10 parts by weight of additive to form the cementing material.
2. The process according to claim 1, wherein in step (1), chlorine dioxide is obtained by: reacting a chlorate aqueous solution, hydrogen peroxide and a sulfuric acid aqueous solution in a chlorine dioxide generator at 50-90 ℃ to obtain chlorine dioxide; wherein the concentration of sodium chlorate in the chlorate aqueous solution is 15-40 wt%, and the concentration of hydrogen peroxide is 25-38 wt%; the concentration of the sulfuric acid aqueous solution is 30-60 wt%; sodium chlorate in aqueous chlorate solution, hydrogen peroxide in hydrogen peroxide and H in aqueous sulfuric acid solution2SO4The molar ratio of (A) to (B) is 1: 0.55-1: 0.5-1.
3. The process as claimed in claim 1, wherein in the step (2), the sulfur content in the raw flue gas is 600-4000 mg/Nm3(ii) a The nitrogen content is 200-600 mg/Nm3(ii) a Oxygen content is 5-23 wt%; moisture content is 5-12 wt%;
the flow velocity of the pre-dedusting flue gas in the flue gas pipeline is 6-15 m/s; the contact time of the pre-dedusting flue gas and the oxidant in the flue gas pipeline is 1-3 s.
4. The process according to claim 1, wherein in the step (3), the flow velocity of the first treated flue gas in the fluidized bed absorption tower is 2-5 m/s; the contact time of the first treated flue gas and the absorbent dry powder in the fluidized bed absorption tower is 1-6 s.
5. The process according to claim 1, wherein in step (3), the dry absorbent powder is prepared by the following method: reacting fly ash, an alkali activator and water at 50-80 ℃ for 5-20 h, and drying and grinding the obtained product to obtain absorbent dry powder with the particle size of 150-350 meshes.
6. The process according to claim 5, wherein in the step (3), the ratio of the total weight of the fly ash and the alkali-activator to the weight of the water is 1:10 to 20.
7. The process according to claim 5, wherein in the step (3), the alkali-activating agent is calcium hydroxide and/or calcium oxide.
8. The process according to claim 5, wherein in the step (3), the fly ash comprises 20 to 60 parts by weight of silica, 20 to 40 parts by weight of alumina and 1 to 20 parts by weight of calcium oxide, based on 100 parts by weight of fly ash.
9. The process of claim 1, wherein in the step (4), the additive is potassium hydroxide and/or sodium hydroxide.
10. The process according to any one of claims 1 to 9, wherein the raw materials consisting of 30 to 70 parts by weight of ash, 20 to 50 parts by weight of mineral powder, 0 to 30 parts by weight of fly ash and 2 to 10 parts by weight of an additive are mixed to form the cementitious material.
CN201911397046.0A 2019-12-30 2019-12-30 Integrated process for treating flue gas and preparing cementing material Pending CN113117477A (en)

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Application publication date: 20210716