CN113117483A - Integrated method for dry desulfurization and denitrification and cementing material manufacturing - Google Patents
Integrated method for dry desulfurization and denitrification and cementing material manufacturing Download PDFInfo
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Abstract
The invention discloses an integrated method for dry desulfurization and denitrification and cementing material manufacturing. The method comprises the following steps: (1) sequentially performing pre-dedusting, oxidation and desulfurization and denitrification treatment on raw flue gas to form desulfurization and denitrification flue gas; (2) carrying out dust removal treatment on the desulfurization and denitrification flue gas to obtain ash; the ash comprises a first ash and a second ash; (3) uniformly mixing raw materials including first ash, fly ash, mineral powder and an alkali activator to obtain the cementing material; wherein the first ash is 25-55 parts by weight, the fly ash is 15-55 parts by weight, the mineral powder is 15-45 parts by weight, and the alkali activator is 4-8 parts by weight. The method disclosed by the invention is high in denitration efficiency and high in strength of the cementing material.
Description
Technical Field
The invention relates to an integrated method for dry desulfurization and denitrification and cementing material manufacturing.
Background
The sulfur dioxide and the nitrogen oxide mainly come from flue gas discharged in large quantity from coal-fired power plants and the like. In order to effectively control the emission of harmful gases in coal-fired flue gas, extensive research and engineering practice is carried out on desulfurization and denitration at home and abroad. Most of the currently adopted processes are single desulfurization and denitrification devices; large occupied area and high investment and operation cost. Therefore, the integrated desulfurization and denitrification process is more and more emphasized.
The desulfurization and denitrification of the flue gas can generate ash, and the ash comprises desulfurization ash. The ash and slag wastes including the desulfurized ash are recycled, so that the environmental protection problem can be solved, and the economic value can be improved.
The utilization conditions of domestic and foreign desulfurized fly ash are basically based on the utilization approach of fly ash, and are mainly used for backfilling soil, constructing roads, doping other materials to refine building materials and the like.
As the flue gas desulfurization and denitration processes are various, the formed desulfurization and denitration ash residues are different. Accordingly, the method of using the ash formed by desulfurization and denitrification of flue gas is different. Therefore, people pay attention to and research on how to integrally desulfurize and denitrate the flue gas and prepare the desulfurized and denitrated flue gas ash into the cementing material so that the cementing material has the performance which can reach or exceed that of common portland cement.
CN106517991A discloses a self-toughening magnesium cementing material, which comprises the following components in parts by weight: 58-80 parts of magnesium oxide, 10-30 parts of magnesium chloride, 0.2-10 parts of magnesium sulfate and 0.5-10 parts of phosphate. During the use process of the cementing material provided by the invention, magnesium oxide and magnesium sulfate in the components react with mixing water to generate 5Mg (OH)2·MgSO4·7H2O and 5Mg (OH)2·MgSO4·3H2O is a representative of a uniformly dispersed high-strength needle crystal, and the toughness is significantly improved. However, this patent document does not disclose the use of desulfurized and denitrified ash as a raw material for a cement.
CN107441909A discloses a desulfurization and denitrification integrated process. The desulfurization and denitrification process comprises the steps of dust removal, heat exchange, ozone introduction reaction and alkali liquor absorption. The alkali solution in the process can be ammonia water, sodium hydroxide, potassium hydroxide and sodium carbonate. The alkali liquor is used for absorbing SOx and oxidized NOx in the flue gas simultaneously, so that the NOx and SOx in the flue gas are completely removed, and the flue gas reaches the standard and is discharged. However, the process does not mention the reuse of desulfurization and denitrification ash, and the process adopts expensive ozone oxidation, thereby causing higher cost.
CN107572844A discloses a method for producing a gelled material by flue gas desulfurization and denitrification. (1) Treating the flue gas by adopting ozone and a desulfurization and denitrification agent to form an absorption product, and further treating the absorption product to obtain dry desulfurization and denitrification ash; (2) mixing raw materials containing desulfurization and denitrification ash, solid waste and magnesium oxide to form a cementing material; the desulfurization and denitrification agent comprises 30-60 parts by weight of magnesium oxide, 20-50 parts by weight of red mud and 20-50 parts by weight of carbide slag, wherein the magnesium oxide is selected from at least one of magnesite light-burned powder, dolomite light-burned powder and analytically pure magnesium oxide. Although the method can solve the problem of recycling the desulfurization and denitrification ash, the method still adopts expensive ozone oxidation, which results in higher cost.
Disclosure of Invention
The invention aims to provide an integrated method for dry desulfurization and denitrification and manufacturing of a cementing material. Sometimes, the method can also be called an integrated process for manufacturing the cementing material based on dry flue gas desulfurization and denitrification. The integrated method has higher denitration efficiency, and the manufactured cementing material has high strength. Further, the invention can realize the cooperative recycling of waste gas and solid waste. The invention achieves the above purpose through the following technical scheme.
An integrated method for dry desulfurization and denitrification and cementing material manufacturing comprises the following steps:
(1) pre-dedusting the raw flue gas to obtain dedusting flue gas; contacting the dedusting flue gas with aqueous hydrogen peroxide in a flue gas pipeline for oxidation to obtain oxidized flue gas; introducing the oxidized flue gas into an absorption tower, and then reacting with the desulfurization and denitrification agent dry powder to form desulfurization and denitrification flue gas; the desulfurization and denitrification agent dry powder contains an absorbent and ammonium bisulfite dry powder, and the absorbent is calcium oxide dry powder or calcium hydroxide dry powder;
(2) carrying out dust removal treatment on the desulfurization and denitrification flue gas to obtain ash; the ash comprises a first ash and a second ash; the first ash comprises calcium sulfate and ammonium sulfate, the second ash comprises a desulfurization and denitrification agent which is not completely reacted, the first ash is discharged to an ash bin, and the second ash is recycled to the absorption tower;
(3) uniformly mixing raw materials including first ash, fly ash, mineral powder and an alkali activator to obtain the cementing material; wherein the first ash is 25-55 parts by weight, the fly ash is 15-55 parts by weight, the mineral powder is 15-45 parts by weight, and the alkali activator is 4-8 parts by weight.
According to the integrated method for dry desulfurization and denitrification and cement material production, in step (3), the alkali activator is preferably sodium hydroxide or potassium hydroxide.
According to the integrated method for dry desulfurization and denitrification and cement material manufacturing, the cement material is preferably composed of the following raw materials in parts by weight in step (3): 25-55 parts of first ash, 15-55 parts of fly ash, 15-45 parts of mineral powder and 4-8 parts of alkali activator.
According to the integrated method for dry desulfurization and denitrification and cement material manufacturing, step (3) preferably further comprises the following steps: before the raw materials are mixed, the first ash is ground until the particle size is 150-500 meshes.
According to the integrated method for dry desulfurization and denitrification and cementing material production, preferably, in the step (1), the concentration of the aqueous hydrogen peroxide solution is 15-35 wt%, and H in the aqueous hydrogen peroxide solution added in unit time2O2The molar ratio of the nitrogen oxide to the nitric oxide in the original flue gas introduced in unit time is 1-4: 1.
According to the integrated method for dry desulfurization and denitrification and cementing material manufacturing, in the step (1), the contact time of the aqueous hydrogen peroxide solution and the dedusting flue gas is preferably 1-30 s; the flow velocity of the dedusting flue gas in the flue gas pipeline is 6-15 m/s.
According to the integrated method for dry desulfurization and denitrification and cementing material manufacturing, in the step (1), the molar ratio of the ammonium bisulfite dry powder added in unit time to the nitric oxide contained in the raw flue gas introduced in unit time is preferably 3.2-4.9: 1.
According to the integrated method for dry desulfurization and denitrification and cementing material manufacturing, preferably, in the step (1), the molar ratio of the absorbent dry powder added in unit time to the sulfur dioxide contained in the raw flue gas introduced in unit time is a calcium-sulfur ratio, and the calcium-sulfur ratio is 1-2: 1.
According to the integrated method for dry desulfurization and denitrification and cementing material manufacturing, the contact time of the desulfurization and denitrification agent dry powder in the absorption tower and the oxidized flue gas is preferably 5-30 s.
According to the integrated method for the dry desulfurization and denitrification and the manufacturing of the cementing material, the flow velocity of the oxidized flue gas in the absorption tower is preferably 1-7 m/s.
The invention takes hydrogen peroxide, calcium-based absorbent and ammonium bisulfite as flue gas treating agent to remove sulfur dioxide and nitrogen oxide in the flue gas. The method has high denitration efficiency and desulfurization efficiency. The obtained first ash can be directly used as a production raw material of the cementing material. Compared with an ozone oxidation process, the cost of the obtained cementing material is lower.
Drawings
FIG. 1 is a schematic view of an integrated device of the present invention.
1-absorbent dry powder supply equipment; 2-ammonium bisulfite dry powder supply equipment; 3-an aqueous hydrogen peroxide solution supply device; 4-an atomizer; 5-an electrostatic precipitator; 6-dense phase dry tower; 7-a humidifier; 8-bag dust collector; 9-ash bin; 10-a chimney; 11-a ball mill; 12-fly ash bin; 13-a fine ore bin; 14-alkali activator storehouse; 15-U type asymmetric mixer; 16-packaging machine.
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 raw flue gas can be sulfur-containing and NO-containing flue gas from coal-fired boilers, steel sintering machines, pellets, industrial kilns and the like.
The integrated method for dry desulfurization and denitrification and cementing material manufacturing simultaneously comprises a flue gas dry desulfurization and denitrification process and a cementing material manufacturing process, which are closely combined. The integration can be realized only by adjusting the technological parameters of the dry flue gas desulfurization and denitrification and the manufacturing technological parameters of the cementing material, so that the process is different from the common and independent process for the dry flue gas desulfurization and denitrification and the common and independent manufacturing process of the cementing material. The integration method comprises the following steps: (1) desulfurizing and denitrating the flue gas; (2) a dust removal step; (3) and (3) manufacturing a cementing material. As described in detail below.
< flue gas desulfurization and denitration >
The dust content of the original smoke is 80-200 mg/Nm3Preferably 90 to 180mg/Nm3More preferably 100 to 160mg/Nm3. And carrying out pre-dedusting treatment on the raw flue gas to obtain dedusting flue gas. And introducing the dedusting flue gas into a flue gas pipeline positioned in front of the absorption tower.
The pre-dedusting step is to pre-treat the raw flue gas by pre-dedusting equipment to obtain the dedusting flue gas. The pre-dedusting efficiency can reach more than 90%. The pre-dust removing equipment can adopt a bag type dust remover, a cyclone dust remover or an electric dust remover, and is preferably an electric dust remover. According to one embodiment of the invention, the pre-dedusting treatment uses a wet electrostatic precipitator for dedusting. Through the pre-dedusting step, larger and tiny particles in the flue gas can be removed.
The dust content in the dedusting flue gas is 5-20 mg/Nm3Preferably 6 to 18mg/Nm3More preferably 7 to 16mg/Nm3. When the dust content in the dedusting flue gas is in the range, the hydrogen peroxide can react with NO in the flue gas more fully to form NO2、N2O5And high valence nitrogen oxides.
The oxygen content of the raw flue gas is 5-23 vol%, preferably 8-20 vol%. When the oxygen content in the original flue gas is in the range, the hydrogen peroxide aqueous solution can react with NO in the flue gas more fully to form NO2、N2O5And high valence nitrogen oxides. The oxygen content in the flue gas is too low, so that the desulfurization and denitrification effects cannot be ensured; too high an oxygen content increases energy consumption and costs.
The temperature of the dedusting flue gas obtained by the pre-dedusting treatment can be 90-150 ℃, preferably 100-130 ℃, and more preferably 110-120 ℃. The moisture content of the original flue gas is 5-15%, and preferably 5-12%. Mixing the flue gasThe temperature and the flue gas humidity are controlled within the ranges, so that the hydrogen peroxide aqueous solution is more favorable for forcibly oxidizing NO into NO2、N2O5And high-valence nitrogen oxides are added, so that the denitration efficiency is improved.
The sulfur content of the raw flue gas is 500-4500 mg/Nm3Preferably 600 to 4500mg/Nm3More preferably 600 to 4000mg/Nm3. The sulfur-containing substances in the original flue gas are mainly sulfur dioxide. Nitrogen oxides NO of raw flue gasxThe concentration is 200-600 mg/Nm3Preferably 300 to 550mg/Nm3. The nitrogen oxides in the original flue gas are mainly NO. The concentration of sulfur dioxide and nitrogen oxide in the flue gas is controlled in the range, which is more beneficial to the forced oxidation of NO into NO by hydrogen peroxide2、N2O5The high valence state nitrogen oxide is beneficial to the reaction of the desulfurization and denitrification agent, sulfur dioxide and the high valence state nitrogen oxide, thereby improving the desulfurization efficiency and the denitrification efficiency.
And contacting the dedusting flue gas with aqueous hydrogen peroxide in a flue gas pipeline for oxidation to obtain oxidized flue gas. The invention adopts the hydrogen peroxide as the oxidant, can rapidly carry out chemical reaction with low-valence nitrogen oxides in the flue gas, and has high reaction speed and high efficiency. The hydrogen peroxide is used in the form of an aqueous hydrogen peroxide solution. Hydrogen peroxide oxidizes NO in flue gas to NO2、N2O5Nitrogen oxides of equal valence state, thereby increasing the subsequent conversion to N2。
The oxidation principle of oxidizing NO with hydrogen peroxide is as follows:
NO+H2O2→NO2+H2o (Main)
2NO+3H2O2→N2O5+3H2O (Main)
2NO+3H2O2→2HNO3+2H2O (vice)
2NO+H2O2→2HNO2(vice)
In the present invention, H in the aqueous hydrogen peroxide solution added per unit time2O2With the content of the original smoke gas introduced in unit timeThe molar ratio of nitric oxide is 1-4: 1, preferably 1.1-3: 1, and more preferably 1.2-1.5: 1. Thus, the oxidation effect and the consumption of the aqueous solution of hydrogen peroxide can be both considered, and the strength of the cementing material can be improved.
The concentration of the aqueous hydrogen peroxide solution may be 15 to 35 wt%, preferably 20 to 35 wt%, more preferably 27.5 wt% or 35 wt%. Still more preferably 27.5 wt%. The contact time of the aqueous hydrogen peroxide solution and the dedusting flue gas can be 1s to 30s, preferably 1s to 10s, and more preferably 1s to 3 s. The flow speed of the dedusting flue gas in the flue gas pipeline is 6-15 m/s, preferably 9-13 m/s, and more preferably 10-12 m/s. This facilitates the oxidation of NO in the flue gas.
According to one embodiment of the invention, the aqueous hydrogen peroxide solution is supplied to the first spraying device by the aqueous hydrogen peroxide solution supply device, and is sprayed into the flue gas duct by the first spraying device, and then contacts and reacts with the dedusting flue gas in the flue gas duct to form oxidized flue gas. According to one embodiment of the invention, the first spraying device is an atomizer.
In the present invention, the oxidation step is carried out in the flue gas duct before entering the absorption tower. First spraying equipment is used for receiving hydrogen peroxide aqueous solution, and sprays hydrogen peroxide aqueous solution to the flue gas pipeline in to make hydrogen peroxide better and remove dust the flue gas and carry out abundant contact and reaction. With first spraying equipment setting in the flue gas pipeline, can promote the contact of hydrogen peroxide aqueous solution and flue gas like this to promote the quick oxidation reaction of hydrogen peroxide to low valence nitrogen oxide (mainly NO). The first spraying device may be an atomizer, which may be located within the flue gas duct. And spraying the hydrogen peroxide water solution into the flue gas pipeline through a first spraying device positioned in the flue gas pipeline, and contacting and reacting with the dedusting flue gas in the flue gas pipeline to form oxidized flue gas.
Hydrogen peroxide oxidizes Nitric Oxide (NO) in flue gas to nitrogen dioxide (NO)2) Dinitrogen pentoxide (N)2O5) The high valence nitrogen oxides are convenient to react with the ammonium bisulfite dry powder. Using aqueous hydrogen peroxide solution to remove dust from flue gasThe products of NO oxidation include: NO2、N2O5、HNO3、HNO2And H2And O, obtaining oxidized smoke.
And introducing the oxidized flue gas into an absorption tower, and then reacting with the desulfurization and denitrification agent dry powder to form the desulfurization and denitrification flue gas. The desulfurization and denitrification agent contains an absorbent and ammonium bisulfite dry powder, and the absorbent is calcium oxide dry powder or calcium hydroxide dry powder.
The principle of adopting ammonium bisulfite dry powder, absorbent dry powder and oxidized flue gas to carry out desulfurization and denitrification reaction is as follows:
4NH4HSO3+2NO2→N2+2(NH4)2SO4+2H2SO4(Main)
10NH4HSO3+2N2O5→2N2+5(NH4)2SO4+5H2SO4(Main)
10NH4HSO3+4HNO3→2N2+5(NH4)2SO4+5H2SO4+2H2O (vice)
6NH4HSO3+4HNO2→2N2+3(NH4)2SO4+3H2SO4+2H2O (vice)
4NH4HSO3+2NO+O2→N2+2(NH4)2SO4+2H2SO4(vice)
SO2+H2O→H2SO3(Main)
3H2SO3+2Ca(OH)2→Ca(HSO3)2+CaSO3+4H2O (Main)
Ca(HSO3)2+2CaSO3+2O2+Ca(OH)2→4CaSO4+2H2O (Main)
NO+NO2+Ca(OH)2→Ca(NO2)2+H2O (vice)
Ca(NO2)2+O2→Ca(NO3)2(vice)
N2O5+Ca(OH)2→Ca(NO3)2+H2O (vice)
HNO2+HNO3+1/2O2+Ca(OH)2→Ca(NO3)2+2H2O (vice)
H2SO4+Ca(OH)2→CaSO4+2H2O
In the invention, the molar ratio of the ammonium bisulfite added in unit time to the NO contained in the raw flue gas introduced in unit time can be 3.2-4.9: 1, preferably 3.3-3.9: 1, and more preferably 3.5-3.9: 1. This is favorable to improving denitration efficiency. If the using amount of the ammonium bisulfite is too small, the denitration efficiency is low, and the performance of the cementing material is poor; if the dosage of the ammonium bisulfite is too much, the denitration efficiency cannot be obviously improved, the absorption of the absorbent is influenced, and the performance of the cementing material is poor.
In the invention, the molar ratio of the absorbent dry powder (calcium oxide dry powder or calcium hydroxide dry powder) added in unit time to the sulfur dioxide contained in the original flue gas introduced in unit time is calcium-sulfur ratio. The calcium-sulfur ratio can be 1-2: 1, preferably 1.1-1.8: 1, more preferably 1.1-1.5: 1. this facilitates the absorption of sulfur dioxide by the absorbent to improve desulfurization efficiency and improves the strength of the cementitious material.
In the invention, the contact time of the desulfurization and denitrification agent dry powder and the oxidized flue gas in the absorption tower can be 5 s-30 s, preferably 6 s-15 s, and more preferably 9 s-12 s. The flow velocity of the oxidation flue gas in the absorption tower can be 1-7 m/s, preferably 2-5 m/s, more preferably 3-5 m/s, such as 4 m/s. Thus being beneficial to the full reaction of the ammonium bisulfite dry powder and the absorbent dry powder with the oxidation flue gas.
The particle size of the calcium oxide dry powder or the calcium hydroxide dry powder is 100-400 meshes, preferably 150-350 meshes, and more preferably 200-250 meshes. The particle size of the ammonium bisulfite dry powder is 100-400 meshes, preferably 150-350 meshes, and more preferably 200-300 meshes. This is favorable to improving desulfurization efficiency and denitration efficiency.
According to one embodiment of the invention, the oxidized flue gas is introduced into an absorption tower, the absorbent dry powder and the ammonium bisulfite dry powder are respectively sprayed into the absorption tower through an absorbent dry powder supply device and an ammonium bisulfite dry powder supply device, and water is sprayed into the absorption tower through a second spraying device, so that the absorbent dry powder and the ammonium bisulfite dry powder are humidified, and the absorbent dry powder and the ammonium bisulfite dry powder contact and react with the oxidized flue gas in the absorption tower, so that the desulfurized and denitrified flue gas is formed. According to one embodiment of the invention, the absorption tower is a dense phase dry tower; the second spraying equipment is a humidifier. Dense phase dry columns are common in the art.
The absorbent dry powder is supplied by an absorbent dry powder supply apparatus. The ammonium bisulfite dry powder is supplied by an ammonium bisulfite dry powder supply apparatus. The water used to humidify the absorbent and the ammonium bisulfite dry powder is supplied by a second spraying device. Thus, the water consumption is low, and the ash slag is a powdery product, thereby not only reducing the water consumption, but also omitting the process step of ash slag crystallization and purification.
Water is sprayed into the absorption column through a humidifier. On one hand, water can promote ammonium bisulfite dry powder to reduce and oxidize nitrogen oxides in the flue gas, and on the other hand, water can promote absorbent dry powder to absorb sulfur dioxide and sulfuric acid in the flue gas. Therefore, the flue gas desulfurization and denitrification effects can be obviously improved. The proper amount of water is favorable for desulfurization and denitrification of flue gas. However, excessive moisture causes agglomeration of the absorbent dry powder, which affects the desulfurization and denitrification effects of the flue gas.
< step of removing dust >
And carrying out dust removal treatment on the desulfurization and denitrification flue gas to obtain ash and purified flue gas. The cleaned flue gas is discharged from an exhaust device, such as a stack. And (4) performing dust removal treatment by adopting a bag-type dust remover. The ash includes a first ash and a second ash. The first ash contains calcium sulfate and ammonium sulfate, and the second ash contains the desulfurization and denitrification agent which is not completely reacted. The first ash is discharged to an ash bin. The unreacted absorbent dry powder and the ammonium bisulfite dry powder (i.e., the second ash) may be recycled to the absorption tower by a recycling device.
< step of producing Cement >
And uniformly mixing the raw materials comprising the first ash, the fly ash, the mineral powder and the alkali activator to obtain the cementing material.
The first ash may be 25 to 55 parts by weight; preferably, the first ash is 27-52 parts by weight; more preferably, the first ash is 30 to 50 parts by weight. This is advantageous for obtaining a cement with higher compressive and flexural strength.
The fly ash is selected from one or two of primary fly ash and secondary fly ash, and is preferably primary fly ash. The particle size of the fly ash can be 150-500 meshes, preferably 200-400 meshes, and more preferably 300-350 meshes. The fly ash can be 15-55 parts by weight; preferably, the fly ash accounts for 17-50 parts by weight; more preferably, the fly ash is 20-45 parts by weight. This is advantageous for obtaining a cement with higher compressive and flexural strength.
The mineral powder of the invention can be S105, S95 or S75 grade mineral powder, preferably S105 grade mineral powder. The granularity of the mineral powder can be 150-500 meshes, preferably 200-400 meshes, and more preferably 300-350 meshes. 15-45 parts of mineral powder; preferably, the mineral powder is 20-45 parts by weight, and more preferably, the mineral powder is 20-40 parts by weight. This is advantageous for obtaining a cement with higher compressive and flexural strength.
The alkali activator of the present invention is sodium hydroxide (NaOH) or potassium hydroxide (KOH), preferably NaOH. The alkali activator can be 4-8 weight parts; preferably, the alkali activator is 5-8 parts by weight; more preferably, the alkali activator is 5 to 7 parts by weight. This is advantageous for obtaining a cement with higher compressive and flexural strength.
According to one embodiment of the invention, the cement material consists of the following raw materials in parts by weight: 25-55 parts of first ash, 15-55 parts of fly ash, 15-45 parts of mineral powder and 4-8 parts of alkali activator. According to another embodiment of the invention, the cementitious material consists of the following raw materials in parts by weight: 30-50 parts of first ash, 20-50 parts of fly ash, 20-45 parts of mineral powder and 5-7 parts of alkali activator. According to a further embodiment of the invention, the cementitious material consists of the following raw materials in parts by weight: 35-45 parts of first ash, 25-45 parts of fly ash, 20-40 parts of mineral powder and 5-6 parts of alkali activator.
Before mixing the raw materials comprising the first ash, the fly ash, the mineral powder and the alkali activator, the first ash can be ground to have the granularity of 150-500 meshes, preferably 200-400 meshes, and more preferably 300-350 meshes. This is advantageous for improving the properties of the cement.
The apparatus used for the grinding according to the invention is preferably a ball mill. The ball-milling machine has a ball-milling ratio of 1: 8-12 and a milling time of 0.5-2 h. Preferably, the ball-milling machine has a ball-milling ratio of 1: 9-11 and a milling time of 0.5-1.5 h. The material-ball ratio refers to the mass ratio of materials in the ball mill to the grinding body.
These raw materials can be mixed uniformly by a conventional method. The mixing device may be a single-shaft mixing device, a double-shaft mixing device, a horizontal ribbon mixer, or a U-shaped asymmetric mixer, preferably a U-shaped asymmetric mixer. More preferably a U-shaped high efficiency asymmetric mixer.
According to one embodiment of the invention, the first ash is added into a ball mill to be ground for 0.5-1.5 h until the first ash is ground to the granularity of 300-350 meshes; and mixing the ground first ash, fly ash, mineral powder and an alkali activator in a U-shaped asymmetric mixer to obtain the cementing material. The material ball ratio in the ball mill is 1: 9-11.
In the present invention, the first ash is fed to the mixing apparatus through the ash bin. The fly ash is fed to the mixing apparatus through a fly ash silo. The ore powder is fed to the mixing device through the ore powder bin. The alkali activator is supplied to the mixing device through the alkali activator bunker. The prepared cementing material is packaged by an (automatic) packaging machine, so that the product is prevented from being affected with damp and mixed with impurities.
Example 1
The schematic diagram of the device used for the integrated method for dry desulfurization and denitrification and the manufacture of the cementing material is shown in figure 1. The raw flue gas from the sintering machine is subjected to particulate matter removal by an electrostatic precipitator 5 to obtain a dedusted flue gas. And introducing the dedusting flue gas into the flue gas pipeline. An aqueous hydrogen peroxide solution (concentration of 27.5 wt%) was supplied to the atomizer 4 located in the flue gas duct by an aqueous hydrogen peroxide solution supply apparatus 3; then the aqueous hydrogen peroxide solution is sprayed into the flue gas pipeline through the atomizer 4 and contacts and reacts with the dedusting flue gas in the flue gas pipeline, so that oxidized flue gas is formed.
Introducing the oxidized flue gas into a dense-phase drying tower 6, simultaneously spraying the dry calcium hydroxide powder and the dry ammonium bisulfite powder into the dense-phase drying tower 6 through an absorbent dry powder supply device 1 and an ammonium bisulfite dry powder supply device 2 respectively, and simultaneously spraying water into the dense-phase drying tower 6 through a humidifier 7, so as to humidify the dry calcium hydroxide powder and the dry ammonium bisulfite powder, and the dry calcium hydroxide powder and the dry ammonium bisulfite powder are contacted with the oxidized flue gas for 10s and react, so as to form the desulfurized and denitrified flue gas.
And (3) carrying out dust removal treatment on the desulfurization and denitrification flue gas by adopting a bag-type dust remover 8 to obtain ash and purified flue gas. The ash includes a first ash and a second ash. The first ash is discharged into an ash bin 9. The cleaned flue gas is discharged through a stack 10. And (3) sending the calcium hydroxide dry powder and the ammonium bisulfite dry powder (second ash slag) which are not completely reacted into a dense-phase drying tower 6 for recycling. The relevant parameters of the desulfurization and denitrification treatment are shown in tables 1-2. The method has the advantages that the desulfurization efficiency is 99.9%, and the denitration efficiency can reach 95.2%.
TABLE 1 Inlet flue gas parameters and Process parameters
| Parameter(s) | Numerical value | Unit of |
| Device inlet smoke amount (working condition) | 575824 | m3/h |
| Device inlet smoke volume (Standard condition wet) | 400000 | Nm3/h |
| Flue gas temperature at inlet of desulfurization and denitrification device | 120 | ℃ |
| SO2Inlet concentration | 2000 | mg/Nm3 |
| Inlet concentration of NO | 250 | mg/Nm3 |
| Moisture content of |
10 | ％ |
| Oxygen content of flue gas | 18 | ％ |
| Dust content of flue gas | 120 | mg/Nm3 |
| Flue gas velocity in flue | 12 | m/s |
| Empty towerFlow rate of flue gas | 3.8 | m/s |
| H2O2Molar ratio of NO | 1.5 | — |
| NH4HSO3Molar ratio of NO | 3.2 | — |
| Calcium to sulfur ratio | 1.3 | — |
| H2O2Mass fraction | 27.5 | ％ |
| Amount of hydrogen peroxide aqueous solution injected | 618 | kg/h |
| Purity of ammonium bisulfite | 99 | ％ |
| Ammonium bisulfite particle size | 200～300 | Eyes of a user |
| The amount of ammonium bisulfite to be used | 1057 | kg/h |
| Purity of absorbent (slaked lime) | 90 | ％ |
| Particle size of absorbent (slaked lime) | 200～300 | Eyes of a user |
| The amount of slaked lime (calcium hydroxide) | 1336 | kg/h |
TABLE 2 parameters of the outlet flue gas and desulfurization and denitrification rates
| Item | Number of | Unit of |
| Exhaust gas temperature | 40 | ℃ |
| Efficiency of desulfurization | 99.9 | ％ |
| Denitration efficiency | 95.2 | ％ |
And conveying the first ash from the ash bin 9 to a ball mill 11, and then ball-milling until the granularity is 300-350 meshes. Conveying the ball-milled first ash to a U-shaped asymmetric mixer 15; meanwhile, the fly ash, the mineral powder and the sodium hydroxide are respectively conveyed into a U-shaped asymmetric mixer 15 from a fly ash bin 12, a mineral powder bin 13 and an alkali activator bin 14, and are fully mixed to obtain the cementing material. The amounts of first ash, fly ash, mineral fines and sodium hydroxide are referenced in table 3.
The obtained cement was cast in a 40mm × 40mm × 160mm form and measured according to GB175-2007 "general Portland Cement". The results are shown in Table 4.
TABLE 3 dosage of raw materials for cementitious Material
| Parameter(s) | Numerical value | Unit of |
| First ash | 35 | Parts by weight |
| Fly ash | 45 | Parts by weight |
| Mineral powder | 20 | Parts by weight |
| Alkali activator (NaOH) | 5 | Parts by weight |
TABLE 4 Properties of the cements
| Age of age | Compressive strength | Flexural strength | Unit of |
| 3d | 25 | 4.5 | MPa |
| 7d | 35 | 6.7 | MPa |
| 28d | 65 | 9.3 | MPa |
As can be seen from the table, 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 difference from example 1 is only in the composition ratio of the raw materials of the cement. The quantities of the raw materials of the cement of this example are shown in Table 5. The properties of the resulting cement are shown in Table 6.
TABLE 5 dosage of raw materials of cementitious Material
| Parameter(s) | Numerical value | Unit of |
| First ash | 45 | Parts by weight |
| Fly ash | 35 | Parts by weight |
| Mineral powder | 20 | Parts by weight |
| Alkali activator (NaOH) | 5 | Parts by weight |
TABLE 6 Properties of the cements
| Age of age | Compressive strength | Flexural strength | Unit of |
| 3d | 33 | 4.7 | MPa |
| 7d | 39 | 6.9 | MPa |
| 28d | 73 | 11.1 | MPa |
As can be seen from the table, the flexural strength and the compressive strength of the obtained cementing material can reach the national relevant standards of 52.5-grade cement.
Comparative example 1
The procedure was as in example 1 except for the following conditions:
the oxidant is gas containing ozone, the concentration of the ozone in the gas containing ozone is 10 wt%, the gas containing ozone is sprayed into the flue gas pipeline through the high-pressure atomizing nozzle to be mixed with the flue gas, and ammonium bisulfite dry powder is not used. The desulfurization efficiency was 98.6%, and the denitration efficiency was 85.1%.
The obtained cement was cast in a 40mm × 40mm × 160mm form and measured according to GB175-2007 "general Portland Cement". The results are shown in Table 7.
TABLE 7
| Age of age | Compressive strength | Flexural strength | Unit of |
| 3d | 20 | 3.5 | MPa |
| 7d | 25 | 5.2 | MPa |
| 28d | 51 | 8.5 | MPa |
As can be seen from comparison between comparative example 1 and examples 1-2, the use of the oxidant solution of the present invention can not only improve the denitration efficiency, but also improve the flexural strength and compressive strength of the cementitious material.
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 method for dry desulfurization and denitrification and manufacturing of cementing materials is characterized by comprising the following steps:
(1) pre-dedusting the raw flue gas to obtain dedusting flue gas; contacting the dedusting flue gas with aqueous hydrogen peroxide in a flue gas pipeline for oxidation to obtain oxidized flue gas; introducing the oxidized flue gas into an absorption tower, and then reacting with the desulfurization and denitrification agent dry powder to form desulfurization and denitrification flue gas; the desulfurization and denitrification agent dry powder contains an absorbent and ammonium bisulfite dry powder, and the absorbent is calcium oxide dry powder or calcium hydroxide dry powder;
(2) carrying out dust removal treatment on the desulfurization and denitrification flue gas to obtain ash; the ash comprises a first ash and a second ash; the first ash comprises calcium sulfate and ammonium sulfate, the second ash comprises a desulfurization and denitrification agent which is not completely reacted, the first ash is discharged to an ash bin, and the second ash is recycled to the absorption tower;
(3) uniformly mixing raw materials including first ash, fly ash, mineral powder and an alkali activator to obtain a cementing material; wherein the first ash is 25-55 parts by weight, the fly ash is 15-55 parts by weight, the mineral powder is 15-45 parts by weight, and the alkali activator is 4-8 parts by weight.
2. The integrated process of claim 1, wherein in step (3), the alkali-activator is sodium hydroxide or potassium hydroxide.
3. The integrated process according to claim 1, wherein in step (3), the cement material consists of the following raw materials in parts by weight: 25-55 parts of first ash, 15-55 parts of fly ash, 15-45 parts of mineral powder and 4-8 parts of alkali activator.
4. The integrated method according to claim 1, wherein the step (3) further comprises the steps of: before the raw materials are mixed, the first ash is ground until the particle size is 150-500 meshes.
5. The integrated process according to claim 1, wherein in step (1), the aqueous hydrogen peroxide solution has a concentration of 15 to 35 wt.% and H in the aqueous hydrogen peroxide solution is added per unit time2O2The molar ratio of the nitrogen oxide to the nitric oxide in the original flue gas introduced in unit time is 1-4: 1.
6. The integrated process according to claim 1, wherein in step (1), the aqueous hydrogen peroxide solution is in contact with the dedusting fumes for a time ranging from 1s to 30 s; the flow velocity of the dedusting flue gas in the flue gas pipeline is 6-15 m/s.
7. The integrated method according to claim 1, wherein in the step (1), the molar ratio of the ammonium bisulfite dry powder added in unit time to the nitric oxide contained in the raw flue gas introduced in unit time is 3.2-4.9: 1.
8. The integrated method according to claim 1, wherein in the step (1), the molar ratio of the absorbent dry powder added in unit time to the sulfur dioxide contained in the raw flue gas introduced in unit time is a calcium-sulfur ratio, and the calcium-sulfur ratio is 1-2: 1.
9. The integrated method according to claim 1, wherein the contact time of the desulfurization and denitrification agent dry powder in the absorption tower and the oxidized flue gas is 5-30 s.
10. The integrated process according to any one of claims 1 to 9, wherein the flow velocity of the oxidation flue gas in the absorption tower is 1 to 7 m/s.
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Cited By (2)
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| WO2023024392A1 (en) * | 2021-08-27 | 2023-03-02 | 中晶环境科技股份有限公司 | Method for producing building material using desulfurization and denitrification by-product |
| CN116986829A (en) * | 2023-06-13 | 2023-11-03 | 中国地质大学（武汉） | Semi-dry desulfurization ash-fly ash-slag composite cementing material and preparation method thereof |
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| CN116986829A (en) * | 2023-06-13 | 2023-11-03 | 中国地质大学（武汉） | Semi-dry desulfurization ash-fly ash-slag composite cementing material and preparation method thereof |
| CN116986829B (en) * | 2023-06-13 | 2024-10-29 | 中国地质大学（武汉） | Semi-dry desulfurization ash-fly ash-slag composite cementing material and preparation method thereof |
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