CN113121133A - Integrated process for preparing cementing material by flue gas desulfurization and denitrification in synergy - Google Patents

Integrated process for preparing cementing material by flue gas desulfurization and denitrification in synergy Download PDF

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Publication number
CN113121133A
CN113121133A CN201911401467.6A CN201911401467A CN113121133A CN 113121133 A CN113121133 A CN 113121133A CN 201911401467 A CN201911401467 A CN 201911401467A CN 113121133 A CN113121133 A CN 113121133A
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flue gas
calcium
chlorine dioxide
denitrification
slurry
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童裳慧
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Coiico Shanghai Environmental Technology Co ltd
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Coiico Shanghai Environmental Technology Co ltd
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    • 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
    • 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
    • B01D53/76—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
    • B01D53/80—Semi-solid phase processes, i.e. by using slurries
    • 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
    • C04B7/14—Cements containing slag
    • C04B7/147—Metallurgical slag
    • C04B7/153—Mixtures thereof with other inorganic cementitious materials or other activators
    • C04B7/1535—Mixtures thereof with other inorganic cementitious materials or other activators with alkali metal containing activators, e.g. sodium hydroxide or waterglass
    • 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
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2257/00—Components to be removed
    • B01D2257/40—Nitrogen compounds
    • B01D2257/404—Nitrogen oxides other than dinitrogen oxide
    • 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

Abstract

The invention discloses an integrated process for preparing a cementing material by the synergy of flue gas desulfurization and denitrification, which comprises the following steps: (1) the method comprises the following steps of (1) contacting flue gas to be treated with gas containing chlorine dioxide to oxidize nitric oxide in the flue gas to obtain oxidized flue gas, and then contacting the oxidized flue gas with absorption slurry containing a calcium-based absorbent and sodium bisulfite to obtain desulfurization and denitrification slurry; wherein the calcium-based absorbent contains calcium oxide and/or calcium hydroxide; (2) dehydrating, drying and grinding the desulfurization and denitrification slurry to obtain a ground solid product; (3) and uniformly mixing the ground solid product, the fly ash, the mineral powder and the alkali activator to obtain the cementing material. The denitration efficiency of the invention is higher, and the performance of the obtained cementing material is excellent.

Description

Integrated process for preparing cementing material by flue gas desulfurization and denitrification in synergy
Technical Field
The invention relates to an integrated process for preparing a cementing material by the synergy of flue gas desulfurization and denitrification.
Background
The coal-fired flue gas contains harmful substances such as sulfur dioxide, nitrogen oxides and the like, so far, most power plants and industrial boilers still adopt the traditional desulfurization method and denitration method, the occupied area is large, the operation cost is high, and the byproducts after desulfurization and denitration cause environmental pollution, so that the development of a method capable of simultaneously desulfurizing and denitrating is the key research point in the field of flue gas desulfurization and denitration in recent years.
Gypsum, lime and cement are three inorganic cementing materials and have a long history of application, but not only a large amount of coal and electric resources but also a large amount of natural resources such as limestone, iron ore, clay and gypsum are consumed in the process of producing the cementing materials. Therefore, the desulfurization and denitrification by-products and industrial solid wastes are cooperated to prepare the cementing material with high performance and high quality to replace a cement material, so that the method becomes a development direction for researching green novel cementing materials and has wide prospects.
CN103191634B discloses a low-cost oxidation denitration process. The process takes lime water and chlorine as raw materials to prepare aqueous solution, the prepared aqueous solution is diluted in an oxidation section and then is sprayed into the oxidation section from the upper part as an oxidant to be in countercurrent contact with flue gas entering from the lower part, so that nitric oxide in the flue gas is subjected to oxidation reaction, alkali liquor is used as an absorbent and is sprayed into an absorption section from the upper part to absorb the nitric oxide in the oxidized flue gas, and corresponding nitrite is generated to be dissolved in water, so that the aims of desulfurization and denitrification are fulfilled. The process injects a large amount of chlorine gas to generate chloride ions which can corrode the metal structure.
CN101973719A discloses a preparation method of an inorganic cementing material based on a flue gas desulfurization byproduct. The method takes desulfurized ash generated by flue gas desulfurization treatment of a coal-fired power plant as a main material, and slag, gypsum and cement clinker are used as auxiliary materials, and the desulfurized ash is prepared by mixing and grinding. The strength of the cementing material prepared by the process is not high.
Disclosure of Invention
In view of the above, the invention provides an integrated process for preparing a cementing material by the synergy of flue gas desulfurization and denitrification, and the process has higher denitration efficiency and desulfurization efficiency and can obtain the cementing material with excellent performance.
The invention provides an integrated process for preparing a cementing material by flue gas desulfurization and denitrification in a synergistic manner, which comprises the following steps of:
(1) flue gas treatment: the method comprises the following steps of (1) contacting flue gas to be treated with gas containing chlorine dioxide to oxidize nitric oxide in the flue gas to obtain oxidized flue gas, and then contacting the oxidized flue gas with absorption slurry containing a calcium-based absorbent and sodium bisulfite to obtain desulfurization and denitrification slurry; wherein the calcium-based absorbent contains calcium oxide and/or calcium hydroxide;
(2) slurry treatment: dehydrating, drying and grinding the desulfurization and denitrification slurry to obtain a ground solid product;
(3) preparing a cementing material: and uniformly mixing the ground solid product, the fly ash, the mineral powder and the alkali activator to obtain the cementing material.
According to the integrated process for preparing the cementing material by the synergy of the flue gas desulfurization and denitrification, preferably, in the step (1), the molar ratio of chlorine dioxide in the chlorine dioxide-containing gas to nitric oxide in the flue gas to be treated is 0.9-1.6.
According to the integrated process for preparing the cementing material by the synergistic effect of desulfurization and denitrification of the flue gas, preferably, the gas containing chlorine dioxide comprises air and chlorine dioxide, and the volume fraction of the chlorine dioxide is 5-8 vol%.
According to the integrated process for preparing the cementing material by the synergy of the flue gas desulfurization and denitrification, preferably, in the step (1), the molar ratio of chlorine dioxide in the chlorine dioxide-containing gas to nitric oxide in the flue gas to be treated is 1-1.5.
According to the integrated process for preparing the cementing material by the synergistic effect of desulfurization and denitrification of the flue gas, preferably, in the step (1), the molar ratio of the sodium bisulfite to the nitric oxide in the flue gas to be treated is 2.4-3.8.
According to the integrated process for preparing the cementing material by the synergy of flue gas desulfurization and denitrification, preferably, in the step (1), the molar ratio of calcium element in the calcium-based absorbent to sulfur element in flue gas to be treated is 1.1-1.5.
According to the integrated process for preparing the cementing material by the synergistic effect of desulfurization and denitrification of flue gas, preferably, in the step (1), the sodium bisulfite is used in the form of a sodium bisulfite aqueous solution with the mass concentration of 12-24 wt%, and the calcium-based absorbent is used in the form of calcium-based absorbent slurry with the mass concentration of 12-24 wt%.
According to the integrated process for synergistically preparing the cementing material by flue gas desulfurization and denitrification, disclosed by the invention, preferably, based on 100 parts by weight of the cementing material, 30-50 parts by weight of ground solid products, 20-40 parts by weight of fly ash, 30-50 parts by weight of mineral powder and 5-7 parts by weight of alkali activator are used.
According to the integrated process for synergistically preparing the cementing material by flue gas desulfurization and denitrification, preferably, in the step (3), the particle sizes of the ground solid product, the mineral powder, the fly ash and the alkali activator are all 150-500 meshes.
According to the integrated process for preparing the cementing material by the synergistic effect of desulfurization and denitrification of flue gas, in the step (3), preferably, the alkali activator is sodium hydroxide and/or potassium hydroxide.
The invention utilizes the mixing of the gas containing chlorine dioxide and the flue gas, and has high contact degree and good oxidation effect. The invention sprays the absorption serous fluid composed of calcium-based absorbent and sodium bisulfite to the smoke, the nitrogen oxide in the smoke is reduced, SO2Is absorbed, thereby improving the removal efficiency. The solid product is directly used as the raw material for producing the gelled material after being ground, and the gelled material with stable performance is obtained. According to the preferred technical scheme of the invention, the breaking strength and the compressive strength of the cementing material can be further improved by controlling the proportion of the ground solid product and the fly ash in the cementing material.
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 for preparing the cementing material by the synergy of the flue gas desulfurization and the denitrification simultaneously comprises the flue gas desulfurization and denitrification process and the cementing material preparation process, which are closely combined. The integration can be realized only by adjusting the technological parameters of the flue gas desulfurization and denitrification and the technological parameters of the gelled material preparation, so that the method is different from the common independent flue gas desulfurization and denitrification process and the common independent gelled material preparation process. The integrated process comprises the following steps: (1) treating flue gas; (2) treating the slurry; (3) and (3) preparing the cementing material. As described in detail below.
< flue gas treatment >
The method comprises the steps of contacting flue gas to be treated with gas containing chlorine dioxide to oxidize nitric oxide in the flue gas to obtain oxidized flue gas, and contacting the oxidized flue gas with absorption slurry containing a calcium-based absorbent and sodium bisulfite to obtain desulfurization and denitrification slurry. The calcium-based absorbent contains calcium oxide and/or calcium hydroxide. Preferably, the primary treatment flue gas is contacted with the absorption slurry in an absorption tower. The reaction principle is as follows:
(1) oxidation of NO
2ClO2+5NO+H2O→2HCl+5NO2(Main)
2ClO2+4NO→Cl2+4NO2(vice)
2NO2+H2O→HNO2+HNO3(vice)
5HNO2+2ClO2+H2O→5HNO3+2HCl (vice)
(2) Removal of nitrogen oxides
4NaHSO3+2NO2→N2+2Na2SO4+2H2SO4(Main)
2NO2+H2O+HSO3 -→SO4 2-+2NO2 -+3H+(vice)
4ClO2+2Ca(OH)2→Ca(ClO2)2+Ca(ClO3)2+2H2O (vice)
2Cl2+2Ca(OH)2→CaCl2+Ca(ClO)2+2H2O (vice)
(3)SO2Is removed from
SO2+Ca(OH)2→CaSO3+H2O (Main)
2CaSO3+O2→2CaSO4(Main)
SO2+H2O→H2SO3(vice)
H2SO3+Ca(OH)2→CaSO3+2H2O (vice)
According toIn one embodiment of the invention, the gas containing chlorine dioxide generated by the chlorine dioxide generator is input into the flue gas pipeline through an oxidant input device which is arranged on the flue gas pipeline before entering the absorption tower in advance, and is fully mixed with the flue gas to be treated in the flue gas pipeline, so that NO in the flue gas to be treated is oxidized into high-valence nitrogen oxide, and oxidized flue gas is obtained. The oxidized flue gas enters the absorption tower and is fully mixed with the air input by the oxidation fan; adding absorbent slurry (calcium hydroxide slurry) into an absorption tower through absorbent adding equipment, adding sodium bisulfite aqueous solution into the absorption tower through reducing agent adding equipment, mixing the absorbent slurry and the sodium bisulfite aqueous solution to form absorption slurry, pumping the absorption slurry to a spraying layer in the absorption tower through a circulating pump, spraying from top to bottom by using a nozzle, fully contacting with oxidation flue gas in a reverse direction, and reducing high-valence nitrogen oxides in the oxidation flue gas into N by the absorption slurry2And absorbs SO in the oxidized flue gas2And obtaining the treated flue gas at the top of the absorption tower, and obtaining the desulfurization and denitrification slurry at the bottom of the absorption tower.
According to another embodiment of the invention, the flue gas is subjected to a pre-dedusting treatment before being contacted with the chlorine dioxide-containing gas, resulting in a flue gas to be treated. The pre-dedusting treatment can adopt an electrostatic dust collector, and preferably adopts a wet electrostatic dust collector. The pre-dedusting rate is more than 80%, preferably more than 85%, and more preferably more than 90%. The pre-dedusting can remove large particle dust in the flue gas, and prevent the dust from interfering the oxidation of nitric oxide by chlorine dioxide, thereby improving the oxidation efficiency of the flue gas.
The flue gas of the invention can be flue gas from a sintering machine, pellets or a coal-fired boiler. The dust content in the flue gas can be 80-200 mg/Nm3(ii) a Preferably 90 to 180mg/m3(ii) a More preferably 100 to 140mg/m3. Sulfur content (SO) in flue gas2) 600 to 4000mg/m3Preferably 1200 to 3000mg/m3(ii) a More preferably 1800-2600 mg/m3. The content of Nitrogen Oxide (NO) in the flue gas can be 200-600 mg/Nm3Preferably 200 to 400mg/m3More preferably 200 to 260mg/m3. The oxygen content in the flue gas can be 5-23 vol%; preferably, it is10-23 vol%; more preferably 15 to 20 vol%. The moisture content in the flue gas can be 5-12 wt%, preferably 7-12 wt%, and more preferably 9-11 wt%. The temperature of the flue gas is 110-200 ℃ when the flue gas is contacted with the gas containing chlorine dioxide, and preferably 110-170 ℃; more preferably 110 to 150 ℃. The flue gas parameters are controlled within the range, so that the denitration efficiency and the desulfurization efficiency are improved.
The chlorine dioxide gas of the present invention is generated by a chlorine dioxide generator, which may contain some air. The chlorine dioxide generator may employ products or techniques known in the art. The molar ratio of chlorine dioxide in the chlorine dioxide-containing gas to nitric oxide in the flue gas is 0.9-1.6, preferably 0.95-1.5, and more preferably 1.0-1.5. The volume fraction of chlorine dioxide in the chlorine dioxide-containing gas is 4 to 10 vol%, preferably 5 to 8 vol%, and more preferably 6 to 7 vol%. The contact time of the chlorine dioxide-containing gas and the flue gas to be treated in the flue gas pipeline is 1-3 s, preferably 2-3 s, and more preferably 2.5-3 s. The flow velocity of the flue gas in the flue gas pipeline can be 8-15 m/s, preferably 9-13 m/s, and more preferably 10-12 m/s. Therefore, the chlorine dioxide can be ensured to fully react with the nitric oxide in the flue gas to be treated, and the denitration efficiency is improved.
The sodium bisulfite of the present invention may be used in the form of an aqueous sodium bisulfite solution. The mass concentration of the sodium bisulfite aqueous solution of the invention can be 10-25 wt%, preferably 18-23 wt%, and more preferably 20-22 wt%. The molar ratio of the sodium bisulfite in the sodium bisulfite aqueous solution to the nitric oxide in the flue gas to be treated can be 2.4-3.8, preferably 2.7-3.5, and more preferably 3-3.3. Therefore, the nitrogen oxides can be fully reduced by the sodium bisulfite, and the denitration efficiency is improved.
The calcium-based absorbent of the present invention is used in the form of a calcium-based absorbent slurry. The purity of calcium oxide or calcium hydroxide in the calcium-based absorbent is 80-95%, preferably 80-90%, and more preferably 85-90%. The granularity of calcium oxide or calcium hydroxide in the calcium-based absorbent is 150-350 meshes, preferably 200-250 meshes, and more preferably 220-250 meshes. Therefore, the cost of the calcium-based absorbent is low, and the desulfurization and denitrification efficiency is good. In the calcium-based absorbent slurry, the mass concentration of the calcium hydroxide is 10 to 25 wt%, preferably 15 to 20 wt%, and more preferably 18 to 20 wt%. The calcium oxide reacts with water to form calcium hydroxide, which may result in a calcium-based absorbent slurry.
The molar ratio of the calcium element in the calcium-based absorbent to the sulfur element in the flue gas to be treated is 1.1-1.5, preferably 1.1-1.4, and more preferably 1.2-1.3. Thus, the sulfur dioxide in the flue gas is fully absorbed, and the desulfurization effect is improved.
The flow velocity of the flue gas in the absorption tower is 2-7 m/s, preferably 3-5 m/s, and more preferably 3-4 m/s. The contact time of the oxidized flue gas and the absorption slurry in the absorption tower is 3-10 s; preferably 4-8 s; more preferably 5 to 7 seconds. Therefore, the treatment efficiency can be ensured, and the sulfur dioxide and the nitrogen oxide in the oxidized flue gas can be fully absorbed.
According to a specific embodiment of the invention, the temperature of the purified flue gas obtained from the top of the absorption tower can be 50-90 ℃; preferably 35-50 ℃; more preferably 40 to 45 ℃.
< slurry treatment >
And (3) dehydrating, drying and grinding the desulfurization and denitrification slurry to obtain a ground solid product. Specifically, the desulfurization and denitrification slurry is pumped out to a cyclone for primary dehydration, then enters a vacuum filter for secondary dehydration, and the obtained solid product is conveyed to a byproduct storage bin. And conveying the solid product in the byproduct storage bin to a drying device for drying so as to reduce the water content, and then pouring the dried solid product into a ball mill for grinding so as to reduce the particle size, so as to obtain a ground solid product.
In the present invention, the drying device may be a vacuum drying device or a vibrated fluidized bed equipped with a hot air device. When drying, the temperature in the drying device is 90-150 ℃, preferably 100-130 ℃, and more preferably 110-120 ℃. When the drying is performed, the pressure in the drying apparatus is 0.01 to 0.5MPa, preferably 0.05 to 0.2MPa, and more preferably 0.1 to 0.15 MPa. The water content of the dried solid product can be 3-0.02 wt%, preferably 0.5-0.02 wt%, and more preferably 0.01-0.02 wt%. The ball-milling machine has a material-ball ratio of 1: 9 to 11, and the grinding time is 0.5 to 1 hour.
< preparation of Binder >
And uniformly mixing the ground solid product, the fly ash, the mineral powder and the alkali activator to obtain the cementing material. According to one embodiment of the invention, the ground solid product, the fly ash, the mineral powder and the alkali activator are added into a mixing device and uniformly mixed according to the set weight parts to form the cementing material. The mixing device may be a single-shaft mixing device, a double-shaft mixing device or a horizontal ribbon mixer. Preferably, the mixing device is a horizontal ribbon mixer.
In the invention, the ground solid product can be 30-50 parts by weight, preferably 40-60 parts by weight, based on 100 parts by weight of the cementing material; more preferably 50 to 60 parts by weight. The particle size of the ground solid product is 150-500 meshes, preferably 200-400 meshes, and more preferably 300-350 meshes.
In the invention, the fly ash is one or two of primary fly ash and secondary fly ash, and most preferably the primary fly ash. The granularity of the fly ash is 150-500 meshes, preferably 200-400 meshes, and more preferably 300-350 meshes. This facilitates the preparation of the cement. 20-40 parts of fly ash by weight, preferably 23-35 parts of fly ash by weight; more preferably 28 to 32 parts by weight.
In the invention, the ore powder can be S105, S95 and S75 grade ore powder, and the most preferable ore powder is S95 grade ore powder. 30-50 parts of mineral powder, preferably 32-45 parts; more preferably 35 to 40 parts by weight. The granularity of the mineral powder is 150-500 meshes, preferably 200-400 meshes, and more preferably 300-350 meshes. This facilitates the preparation of the cement.
In the present invention, the alkali activator is an alkaline compound, and the alkali activator is NaOH or KOH as a raw material, and NaOH is most preferable. The particle size of the alkali activator is 150-500 meshes, preferably 200-400 meshes, and more preferably 300-350 meshes. 5-7 parts by weight of alkali activator, preferably 5-6 parts by weight; more preferably 6 parts by weight. The raw material proportion is beneficial to improving the mechanical strength of the cementing material.
The test method is described below:
the properties of the gel material were determined according to GB175-2007 Universal Portland Cement.
Example 1
(1) Flue gas treatment: removing partial particles in the raw flue gas by an electrostatic dust collector to obtain flue gas to be treated, then conveying the flue gas to a flue gas pipeline in front of an absorption tower, inputting gas containing chlorine dioxide generated by a chlorine dioxide generator into the flue gas pipeline through an oxidant input device which is arranged on the flue gas pipeline in front of the absorption tower in advance, fully mixing the gas with the flue gas to be treated in the flue gas pipeline, and oxidizing NO in the flue gas to be treated into high-valence nitrogen oxide to obtain oxidized flue gas. The oxidized flue gas enters the absorption tower and is fully mixed with the air input by the oxidation fan; adding absorbent slurry (calcium hydroxide slurry) into an absorption tower through absorbent adding equipment, adding sodium bisulfite aqueous solution into the absorption tower through reducing agent adding equipment, mixing the absorbent slurry and the sodium bisulfite aqueous solution to form absorption slurry, pumping the absorption slurry to a spraying layer in the absorption tower through a circulating pump, spraying from top to bottom by using a nozzle, fully contacting with oxidation flue gas in a reverse direction, and reducing high-valence nitrogen oxides in the oxidation flue gas into N by the absorption slurry2And absorbs SO in the oxidized flue gas2And obtaining the treated flue gas at the top of the absorption tower, and obtaining the desulfurization and denitrification slurry at the bottom of the absorption tower.
And (4) performing liquid-gas separation on the treated flue gas through a demister positioned at the top of the absorption tower, and discharging the separated clean flue gas through a chimney. The absorption tower is connected with a process water tower, and the process water tower provides process water to intermittently wash the demister and the spraying layer so as to ensure the normal operation of the equipment.
(2) Slurry treatment: and pumping the desulfurization and denitrification slurry out of the cyclone by a pump to perform primary dehydration, then feeding the slurry into a vacuum filter to perform secondary dehydration, and conveying the obtained solid product to a byproduct storage bin. And conveying the solid product in the byproduct storage bin to a drying device for drying so as to reduce the water content, and then pouring the dried solid product into a ball mill for grinding so as to reduce the particle size, so as to obtain a ground solid product. Specific parameters are shown in tables 1-2.
TABLE 1
Figure BDA0002347562910000101
TABLE 2
Item Number of Unit of
Exhaust gas temperature 40 ℃
Efficiency of desulfurization 99.7 ％
Denitration efficiency 94.4 ％
(3) Preparing a cementing material: and adding the ball-milled solid product, the fly ash, the mineral powder and an alkali activator (NaOH) into a horizontal ribbon mixer, and uniformly mixing to obtain the cementing material. Specific process parameters are shown in table 3.
The cement was cast in a 40mm x 160mm form and then tested. The results obtained are shown in Table 4.
TABLE 3
Components Numerical value Unit of
Ground solid product 40 Parts by weight
Fly ash 40 Parts by weight
Mineral powder 20 Parts by weight
Alkali activator (NaOH) 5 Parts by weight
TABLE 4
Age of age Compressive strength Flexural strength Unit of
3d 27 4.2 MPa
7d 39 6.4 MPa
28d 59 9.4 MPa
As can be seen from tables 1-4, the desulfurization efficiency and the denitration efficiency of the integrated process of the invention respectively reach more than 99.7 percent and 94 percent; the flexural strength and the compressive strength of the cementing material can reach the national relevant standards of 52.5-grade cement.
Example 2
The procedure of example 1 was repeated except for the parameters shown in Table 5.
The cement was cast in a 40mm x 160mm form and then tested. The results obtained are shown in Table 6.
TABLE 5
Components Numerical value Unit of
Ground solid product 50 Parts by weight
Fly ash 30 Parts by weight
Mineral powder 20 Parts by weight
Alkali activator (NaOH) 5 Parts by weight
TABLE 6
Age of age Compressive strength Flexural strength Unit of
3d 29 4.9 MPa
7d 42 5.3 MPa
28d 70 11.2 MPa
Comparing the results of example 1 and example 2, it can be seen that the compressive strength and the flexural strength of the cement are improved by properly increasing the amount of the ground solid product and properly decreasing the amount of the fly ash.
Comparative example 1
The same as in preparation example 1 was used except for the following conditions:
the oxidant is gas containing ozone, and is prepared by an ozone generator, the concentration of the ozone in the gas containing ozone is 10 wt%, and the gas containing ozone is sprayed into a flue through a high-pressure atomizing nozzle to be mixed with flue gas; the absorption slurry in the absorption tower is slurry containing a calcium-based absorbent, and does not contain sodium bisulfite. The desulfurization efficiency of the method is 98.8%, and the denitration efficiency is 82%.
The solid product obtained in comparative example 1 was used to prepare a cement by the procedure (3) of example 2. The cement was cast in a 40mm x 160mm form and then tested. The formulations are shown in Table 7, and the results are shown in Table 8.
TABLE 7
Components Numerical value Unit of
Ground solid product 50 Parts by weight
Fly ash 30 Parts by weight
Mineral powder 20 Parts by weight
Alkali activator (NaOH) 5 Parts by weight
TABLE 8
Age of age Compressive strength Flexural strength Unit of
3d 28 4.3 MPa
7d 39 6.0 MPa
28d 60 8.7 MPa
Comparing comparative example 1 with example 2, it can be seen that the denitration efficiency and the breaking strength of the cementing material can be improved by adopting the integrated process of the invention. In addition, the process of the invention has lower cost.

Claims (10)

1. An integrated process for preparing a cementing material by the synergy of flue gas desulfurization and denitrification is characterized by comprising the following steps:
(1) flue gas treatment: the method comprises the following steps of (1) contacting flue gas to be treated with gas containing chlorine dioxide to oxidize nitric oxide in the flue gas to obtain oxidized flue gas, and then contacting the oxidized flue gas with absorption slurry containing a calcium-based absorbent and sodium bisulfite to obtain desulfurization and denitrification slurry; wherein the calcium-based absorbent contains calcium oxide and/or calcium hydroxide;
(2) slurry treatment: dehydrating, drying and grinding the desulfurization and denitrification slurry to obtain a ground solid product;
(3) preparing a cementing material: and uniformly mixing the ground solid product, the fly ash, the mineral powder and the alkali activator to obtain the cementing material.
2. The process according to claim 1, wherein in the step (1), the molar ratio of chlorine dioxide in the chlorine dioxide-containing gas to nitric oxide in the flue gas to be treated is 0.9-1.6.
3. The process of claim 1, wherein the chlorine dioxide-containing gas comprises air and chlorine dioxide, and the volume fraction of chlorine dioxide is 5 to 8 vol%.
4. The process according to claim 1, wherein in the step (1), the molar ratio of chlorine dioxide in the chlorine dioxide-containing gas to nitric oxide in the flue gas to be treated is 1 to 1.5.
5. The process according to claim 1, wherein in the step (1), the molar ratio of the sodium bisulfite to the nitric oxide in the flue gas to be treated is 2.4-3.8.
6. The process according to claim 1, wherein in the step (1), the molar ratio of the calcium element in the calcium-based absorbent to the sulfur element in the flue gas to be treated is 1.1-1.5.
7. The process according to claim 1, wherein in the step (1), the sodium bisulfite is used in the form of a sodium bisulfite aqueous solution with a mass concentration of 12 to 24 wt%, and the calcium-based absorbent is used in the form of a calcium-based absorbent slurry with a mass concentration of 12 to 24 wt%.
8. The process according to any one of claims 1 to 7, wherein the ground solid product is 30 to 50 parts by weight, the fly ash is 20 to 40 parts by weight, the mineral powder is 30 to 50 parts by weight, and the alkali activator is 5 to 7 parts by weight, based on 100 parts by weight of the cementitious material.
9. The process as claimed in claim 8, wherein in the step (3), the particle sizes of the ground solid product, the mineral powder, the fly ash and the alkali-activating agent are all 150-500 meshes.
10. The process according to claim 8, wherein in the step (3), the alkali activator is sodium hydroxide and/or potassium hydroxide.
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