CN115006982A - Method for desulfurizing and carbon-fixing coal-fired flue gas by using carbide slag slurry - Google Patents

Method for desulfurizing and carbon-fixing coal-fired flue gas by using carbide slag slurry Download PDF

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CN115006982A
CN115006982A CN202210053548.7A CN202210053548A CN115006982A CN 115006982 A CN115006982 A CN 115006982A CN 202210053548 A CN202210053548 A CN 202210053548A CN 115006982 A CN115006982 A CN 115006982A
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slurry
gas
flue gas
coal
carbide slag
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张冬冬
马海翔
宁平
付阳
杨志杰
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Kunming University of Science and Technology
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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
    • B01D53/74—General processes for purification of waste gases; Apparatus or devices specially adapted therefor
    • B01D53/80—Semi-solid phase processes, i.e. by using slurries
    • 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
    • B01D53/48—Sulfur compounds
    • B01D53/50—Sulfur oxides
    • B01D53/501—Sulfur oxides by treating the gases with a solution or a suspension of an alkali or earth-alkali or ammonium compound
    • B01D53/502—Sulfur oxides by treating the gases with a solution or a suspension of an alkali or earth-alkali or ammonium compound characterised by a specific solution or suspension
    • 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
    • B01D53/62—Carbon 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
    • B01D53/96—Regeneration, reactivation or recycling of reactants
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2251/00—Reactants
    • B01D2251/40—Alkaline earth metal or magnesium compounds
    • B01D2251/404—Alkaline earth metal or magnesium compounds of calcium
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2251/00—Reactants
    • B01D2251/60—Inorganic bases or salts
    • B01D2251/604—Hydroxides
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2257/00—Components to be removed
    • B01D2257/50—Carbon oxides
    • B01D2257/504—Carbon dioxide
    • 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
    • Y02P20/00—Technologies relating to chemical industry
    • Y02P20/151—Reduction of greenhouse gas [GHG] emissions, e.g. CO2

Abstract

The invention discloses a method for desulfurizing and carbon-fixing coal-fired flue gas by using carbide slag slurry, which comprises the following steps: pretreating carbide slag slurry to prepare absorption slurry for later use; mixing the obtained absorption slurry with SO 2 And CO 2 The flue gas is in countercurrent contact to remove SO in the flue gas 2 To obtain a high concentration of CO 2 The desulfurized gypsum slurry is obtained simultaneously with the tail gas; purifying and drying the obtained desulfurization slurry, reducing and calcining to obtain calcium oxide and high-concentration SO 2 A gas; will contain high concentration of CO 2 Reacting the tail gas with the carbide slag slurry to obtain calcium carbonate slurry; purifying and drying the obtained calcium carbonate slurry, and calcining at high temperature to obtain calcium oxide and high-purity CO 2 A gas; the SO obtained 2 The gas can be used as a raw material for producing sulfuric acid; resulting CO 2 The gas can be used as industrial raw material after being purified. The invention simultaneously realizes the recycling of calcium, sulfur and carbon resources in the carbide slag and the coal-fired flue gas, achieves the aim of treating wastes with wastes, and has wide application prospect under the background of 'carbon peak reaching' and 'carbon neutralization'.

Description

Method for desulfurizing and carbon-fixing coal-fired flue gas by using carbide slag slurry
Technical Field
The invention belongs to the fields of industrial waste residue comprehensive utilization, carbon emission reduction, sulfur-containing tail gas purification and the like, and particularly relates to a method for desulfurizing and carbon sequestration of coal-fired flue gas by using carbide slag slurry.
Background
Carbon dioxide is the major product of fossil fuel combustion and is also the most significant gas responsible for the greenhouse effect. The greenhouse effect brings a series of environmental problems such as global temperature rise, climate abnormity and the like. The control of carbon dioxide emissions is therefore of crucial importance for the sustainable development of humans.
The carbide slag is waste slag which is obtained by hydrolyzing carbide to obtain acetylene gas and takes calcium hydroxide as a main component. More than 300 kg of acetylene gas can be generated by adding water into 1t of calcium carbide, and 10 tons of industrial waste liquid with the solid content of about 12 percent is generated at the same time, and is commonly called as calcium carbide slurry. According to statistics, about 1.5-1.9 million tons of carbide slag are generated in the world every year. How to relieve the environmental pressure brought by the carbide slag is concerned by more and more people. At present, the following approaches are mainly used for the resource utilization of the carbide slag: (1) producing building materials such as cement, building bricks, heat-insulating materials, coatings and the like; (2) preparing chemical products such as calcium carbonate, calcium oxide, calcium chloride and the like. However, these methods have problems of high production cost, low added value of products, lack of environmental friendliness, and the like.
In the patents of publication No. CN201110164225.7 'a method for producing a desulfurizing agent by using carbide slag', CN201610600418.5 'a device and method for removing sulfur dioxide in flue gas by using carbide slag', CN201210241581.9 'a process and device for desulfurizing flue gas by using carbide slag-gypsum method', and the like, carbide slag is used as a desulfurizing agent for industrial tail gas, but the preparation process is complex and high in energy consumption, and the removal or fixation of carbon dioxide in the tail gas and the comprehensive utilization of desulfurization by-product gypsum are not considered.
On the basis of the technology, the invention utilizes the characteristics of small particle size, high reaction activity and low pretreatment cost of the carbide slag to combine the coal-fired flue gas desulfurization process with the absorption stationary phase of carbon dioxide, fully recycles reaction byproducts, realizes the cyclic utilization of calcium, sulfur and carbon resources in the carbide slag and the coal-fired flue gas, and has wide application prospect.
Disclosure of Invention
The invention provides a method for desulfurizing and carbon-fixing coal-fired flue gas by using carbide slag slurry. The method effectively reduces the emission of carbon dioxide and sulfur dioxide in the coal-fired flue gas, recycles reaction byproducts, realizes the cyclic utilization of calcium resources, carbon resources and sulfur resources in carbide slag neutralized flue gas, and achieves the purpose of treating wastes with processes of wastes against one another.
The invention adopts the following technical scheme that a method for desulfurizing and carbon-fixing coal-fired flue gas by using carbide slag slurry comprises the following specific steps:
s1, carrying out gravity settling separation on carbide slag slurry generated in a carbide workshop, and further concentrating the carbide slag slurry until the solid content is 20-40% to obtain slurry of which the main component is calcium hydroxide.
S2, conveying the slurry obtained in the step 1 to a primary gas absorption device (a spray tower or a bubble tower) through a circulating pump, and enabling the slurry to contain a large amount of SO 2 And CO 2 The coal-fired flue gas (such as flue gas of a coal-fired power plant, tail gas of a coal-fired boiler and the like) reacts to remove SO in the flue gas 2 Removing to obtain a solution containing high concentration of CO 2 The tail gas of (2); and circularly absorbing the absorption slurry for a certain time, and discharging the absorption slurry out of the absorption tower when the pH value is reduced to about 4 to obtain the desulfurized gypsum slurry.
S3, purifying, removing impurities, drying and dehydrating the desulfurized gypsum slurry in the step 2, and then reducing and calcining at high temperature to obtain calcium oxide and high-concentration SO 2 A gas.
S4, mixing the high-concentration CO in the step 2 2 Introducing the tail gas into a secondary gas absorption device (a spray tower or a bubble tower), reacting with the carbide slag slurry in the step 1, and absorbing CO by the slurry 2 And discharging the calcium carbonate slurry out of the absorption tower after the calcium carbonate slurry is saturated.
S5, removing impurities from the calcium carbonate slurry obtained in the step 4, purifying, dehydrating and drying to obtain high-purity calcium carbonate solidA body; high-temperature calcination is continued to obtain calcium oxide and high-purity CO 2 A gas. Or adjusting part of the calcium carbonate slurry to a proper solid-to-liquid ratio, and returning the calcium carbonate slurry serving as a desulfurizing agent to the desulfurizing system in the step 2 for recycling.
S6, adding the calcium oxide obtained in the steps 3 and 5 into the step 1 as a raw material, and reacting part of water in the carbide slag slurry to save energy consumption of concentration and dehydration, wherein the calcium oxide is recycled in the subsequent steps after being generated; or calcium oxide is taken as a raw material and returned to a calcium carbide production workshop, and then the calcium carbide is synthesized with coke; or the calcium oxide is used as the raw material for cement production; the above three ways can realize the cyclic utilization of calcium resources.
S7, obtaining high-concentration SO in step 3 2 The gas can be used as a raw material for producing sulfuric acid, and the recycling of sulfur resources is realized.
S8 high-purity CO obtained in step 5 2 The gas can be used as industrial raw material after further separation and purification, and the cyclic utilization of carbon resources is realized.
S9 SO in the flue gas 2 And CO 2 The carbide slag slurry is basically removed after being treated, the residual flue gas is continuously subjected to subsequent treatment to remove NO x And the pollutants can be discharged after reaching the standard.
The partial reaction equation involved in the invention is as follows:
step 2, desulfurizing the coal-fired flue gas by using carbide slag slurry:
SO 2 (g)+H 2 O(l)=H 2 SO 3 (l)
Ca(OH) 2 (s)+H 2 SO 3 (l) =CaSO 3 (s)+2H 2 O(l)
2CaSO 3 (s)+O 2 (g)+4H 2 O(l)=2CaSO 4 ·2H 2 O(s)
step 3, after purifying, impurity removing, dehydrating and drying the desulfurized gypsum slurry, reducing and calcining at high temperature to obtain calcium oxide and high-concentration SO 2 Gas:
CaSO 4 (s) = CaO(s)+SO 2 (g)+O 2 (g)
step 4, carbon fixation is carried out on the coal-fired flue gas by using carbide slag slurry:
Ca(OH) 2 (s)+CO 2 (g) = CaCO 3 (s)+H 2 O(l)
step 5, high-purity calcium carbonate solid is continuously calcined at high temperature to obtain calcium oxide and high-purity CO 2 Gas:
CaCO 3 (s) = CaO(s)+CO 2 (g)。
according to the method, the main component of the carbide slag is calcium hydroxide, the carbide slag contains a certain amount of water and has small particle size, so that the carbide slag slurry is directly prepared into slurry with a certain solid content for removing sulfur dioxide and carbon dioxide in the flue gas, and certain advantages are achieved. Compared with the method for capturing carbon dioxide after calcium oxide is roasted from carbide slag reported by other invention patents and documents, the method has the advantage that the energy consumption is obviously reduced. The desulfurized byproduct calcium sulfate can be used for preparing calcium oxide and high-concentration sulfur dioxide, the calcium oxide can be used for preparing the carbide slag slurry or producing calcium carbide or cement, and the high-concentration sulfur dioxide can be used for producing sulfuric acid after being collected and purified. The calcium carbonate after carbon fixation can be used for further producing calcium oxide and high-concentration carbon dioxide for resource utilization.
The invention has the advantages that:
(1) the carbide slag slurry does not need deep dehydration and drying, can be used after simple concentration, and has low energy consumption;
(2) the removal of sulfur dioxide in the coal-fired flue gas and the absorption and fixation process of carbon dioxide are organically combined, SO that the tail gas SO is achieved 2 Discharge after reaching the standard and carbon emission reduction, and obtain high-concentration SO 2 And CO 2 The resource utilization of sulfur and carbon in the tail gas is realized;
(3) the invention has simple process flow, is easy to realize the improvement and the reconstruction of the process on the basis of not changing or slightly changing the existing wet flue gas purification device, and saves the cost;
(4) the industrial waste carbide slag is used for desulfurization and carbon fixation, so that the environmental pressure caused by the carbide slag is relieved, and the environment-friendly concept of treating wastes with wastes is followed; meanwhile, the resource utilization of calcium, carbon and sulfur is realized. Under the background of 'carbon peak reaching' and 'carbon neutralization', the method has profound significance for carbon emission reduction.
Drawings
FIG. 1 is a technical flow chart of the present invention.
Detailed Description
In order to more clearly explain the technical contents of the present invention, the description is given with reference to the specific examples. The scope of the invention is not limited thereto.
As shown in the attached figure 1, the method for desulfurizing and carbon-fixing coal-fired flue gas by using carbide slag slurry comprises the following steps:
s1, pretreating carbide slag slurry generated in a carbide workshop to prepare absorption slurry for later use;
s2, mixing the absorption slurry part obtained in the step (1) with SO in a primary gas absorption device 2 And CO 2 The coal-fired flue gas is in countercurrent contact to remove SO in the flue gas 2 Removing to obtain a product containing high concentration CO 2 The tail gas of (2); circularly absorbing the absorption slurry until the pH value is reduced to 3.5-4.5, and discharging the absorption slurry out of the absorption device to obtain desulfurized gypsum slurry;
s3, purifying and removing impurities from the desulfurized gypsum slurry obtained in the step (2), drying and dehydrating, and then carrying out reduction calcination to obtain calcium oxide and high-concentration SO 2 A gas;
s4, mixing the high-concentration CO obtained in the step (2) 2 Introducing the tail gas into a secondary gas absorption device, reacting with the other part of absorption slurry obtained in the step (1), and absorbing CO by the slurry 2 Discharging the calcium carbonate slurry out of the absorption device after the calcium carbonate slurry is saturated to obtain calcium carbonate slurry;
s5, removing impurities from the calcium carbonate slurry obtained in the step (4), purifying, dehydrating and drying to obtain high-purity calcium carbonate solid; continuously calcining to obtain calcium oxide and high-purity CO 2 A gas; or adjusting part of the calcium carbonate slurry to a proper solid-to-liquid ratio, and returning the calcium carbonate slurry as a desulfurizing agent to the step 2 for absorbing the slurry for recycling;
s6, adding the calcium oxide obtained in the steps (3) and (5) into the step 1 as a raw material for preparing absorption slurry; or the raw material is returned to a calcium carbide production workshop as a raw material, and then the raw material and coke are synthesized into calcium carbide; or as a byproduct for cement production;
s7 high-concentration SO obtained in step (3) 2 The gas can be used as a raw material for producing sulfuric acid, so that the recycling of sulfur resources is realized; high purity CO obtained in step (5) 2 The gas can be used as an industrial raw material after further separation and purification, so that the cyclic utilization of carbon resources is realized;
s8, treating the coal-fired flue gas and SO in the flue gas by using a secondary gas absorption device 2 And CO 2 Is removed and subsequently treated to remove NO x The pollutants can be discharged after reaching the standard.
Preferably, the pretreatment in the step (1) is to perform gravity settling separation, then further concentrate and dewater to obtain absorption slurry with the solid content of 20-40%, wherein the absorption slurry mainly contains calcium hydroxide.
Preferably, the coal-fired flue gas in the step (2) is any one or more of flue gas of a coal-fired power plant, tail gas of a coal-fired boiler and flue gas of cement industry.
Preferably, the coal-fired flue gas in the step (2) is flue gas subjected to dust removal treatment, and the main component of the coal-fired flue gas comprises SO 2 、CO 2 、NO x 、N 2 、O 2 Water vapor and heavy metals, in which SO 2 The content is 2000-5000 mg/Nm 3 ，CO 2 The volume fraction is 10% -15%.
Preferably, the temperature of the reduction calcination in the step (3) is 700-900 ℃.
Preferably, the primary gas absorption device and the secondary gas absorption device are spray towers or bubble towers; the first-stage gas absorption device is used for desulfurization, the second-stage gas absorption device is used for carbon fixation, and the absorption slurry is pretreated carbide slag slurry.
Preferably, the high concentration of SO 2 The gas volume fraction is 40% -50%; the high purity CO 2 The gas volume fraction is not less than 95%.
Example 1
A method for desulfurizing and carbon-fixing coal-fired flue gas by using carbide slag slurry is implemented specifically as follows:
after the carbide slag slurry produced in the carbide workshop is settled and separated by gravity, the calcium carbide slag slurry is further concentrated to calcium hydroxide slurry with the solid content of about 30 percentAnd uniformly stirring in a slurry preparation tank, and conveying to a primary spray tower and a secondary spray tower through circulating pump pipelines. The treated flue gas is flue gas of a coal-fired power plant, SO 2 The concentration is 4000mg/m 3 ~5500mg/m 3 ，CO 2 Volume fraction of 15 percent and smoke amount of 3000m 3 H, the empty tower gas speed is 0.5m/s, the liquid-gas ratio is 0.01, and the measured SO 2 The removal rate was 98.1%. After the carbide slag slurry circulates for about 1 hour, the pH value is reduced to be below 4, and the carbide slag slurry is discharged out of the absorption tower. The desulfurized flue gas is continuously sent to a secondary spray tower to react with carbide slag slurry, the air speed of the air tower is 0.5m/s, the liquid-gas ratio is 0.05, and CO is actually measured 2 The removal rate was 97.6%. Absorption of CO by carbide slag slurry 2 And discharging the product from the absorption tower after the product is saturated. After impurity removal, purification, dehydration and drying, a solid with the calcium carbonate content of 94.6 percent is obtained. The desulfurized gypsum, calcium carbonate and the like can be continuously recycled as required.
Example 2
A method for desulfurizing and carbon-fixing coal-fired flue gas by using carbide slag slurry is implemented specifically as follows:
after the carbide slag slurry generated in a carbide workshop is subjected to gravity settling separation, the carbide slag slurry is further concentrated to calcium hydroxide slurry with the solid content of about 25 percent, the calcium hydroxide slurry is uniformly stirred in a slurry preparation tank, and the calcium hydroxide slurry is conveyed to a first-stage spray tower and a second-stage spray tower through circulating pump pipelines. The treated flue gas is flue gas of a coal-fired power plant, SO 2 The concentration is 2800mg/m 3 ~3500mg/m 3 ，CO 2 The volume fraction is 12 percent, and the smoke gas amount is 2000m 3 H, the empty tower gas speed is 0.5m/s, the liquid-gas ratio is 0.01, and the actual measurement shows that SO 2 The removal rate was 97.3%. And after the carbide slag slurry circulates for about 2 hours, the pH value is reduced to be below 4, and the carbide slag slurry is discharged out of the absorption tower. The desulfurized flue gas is continuously sent to a secondary spray tower to react with carbide slag slurry, the air speed of the air tower is 0.5m/s, the liquid-gas ratio is 0.05, and CO is actually measured 2 The removal rate was 96.8%. Absorption of CO by carbide slag slurry 2 And discharging the product from the absorption tower after the product is saturated. After impurity removal, purification, dehydration and drying, a solid with the calcium carbonate content of 95.4 percent is obtained. The desulfurized gypsum, calcium carbonate and the like can be continuously recycled as required.
Example 3
A method for desulfurizing and carbon-fixing coal-fired flue gas by using carbide slag slurry is implemented specifically as follows:
after the carbide slag slurry generated in a carbide workshop is subjected to gravity settling separation, the carbide slag slurry is further concentrated to calcium hydroxide slurry with the solid content of about 25%, the calcium hydroxide slurry is uniformly stirred in a slurry preparation tank, and the calcium hydroxide slurry is conveyed to a first-stage spray tower and a second-stage spray tower through circulating pump pipelines. The treated flue gas is flue gas of a coal-fired boiler, SO 2 The concentration is 1800mg/m 3 ~2300mg/m 3 ，CO 2 The volume fraction is 12 percent, and the smoke gas amount is 1000m 3 H, the empty tower gas speed is 0.8m/s, the liquid-gas ratio is 0.01, and the actual measurement shows that SO 2 The removal rate was 96.6%. And after the carbide slag slurry circulates for about 2 hours, the pH value is reduced to be below 4, and the carbide slag slurry is discharged out of the absorption tower. The desulfurized flue gas is continuously sent to a secondary spray tower to react with carbide slag slurry, the air speed of the air tower is 0.5m/s, the liquid-gas ratio is 0.05, and CO is actually measured 2 The removal rate was 96.5%. Absorption of CO by carbide slag slurry 2 And discharging the product from the absorption tower after the product is saturated. After impurity removal, purification, dehydration and drying, solid with calcium carbonate content of 96.1 percent is obtained. The desulfurized gypsum, the calcium carbonate and the like can be continuously recycled as required.
The above description is only exemplary of the present invention and should not be taken as limiting the invention, as any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the scope of the present invention.

Claims (7)

1. A method for desulfurizing and carbon-fixing coal-fired flue gas by using carbide slag slurry is characterized by comprising the following steps:
s1, pretreating carbide slag slurry generated in a carbide workshop to prepare absorption slurry for later use;
s2, mixing the absorption slurry part obtained in the step (1) with SO in a primary gas absorption device 2 And CO 2 The coal-fired flue gas is in countercurrent contact to remove SO in the flue gas 2 Removing to obtain a product containing high concentration CO 2 The tail gas of (2); circularly absorbing the absorption slurry until the pH value is reduced to 3.5-4.5, and discharging the absorption slurry out of the absorption device to obtain desulfurized gypsum slurry;
s3, purifying and removing impurities from the desulfurized gypsum slurry obtained in the step (2), drying and dehydrating, and then carrying out reduction calcination to obtain calcium oxide and high-concentration SO 2 A gas;
s4, step(2) The obtained high concentration CO 2 Introducing the tail gas into a secondary gas absorption device, reacting with the other part of absorption slurry obtained in the step (1), and absorbing CO by the slurry 2 Discharging the calcium carbonate slurry out of the absorption device after the calcium carbonate slurry is saturated to obtain calcium carbonate slurry;
s5, removing impurities from the calcium carbonate slurry obtained in the step (4), purifying, dehydrating and drying to obtain calcium carbonate solid; continuously calcining to obtain calcium oxide and high-purity CO 2 A gas; or adjusting part of the calcium carbonate slurry to a proper solid-to-liquid ratio, and returning the calcium carbonate slurry serving as a desulfurizing agent to the step (2) for absorbing the slurry for recycling;
s6, adding the calcium oxide obtained in the steps (3) and (5) into the step 1 as a raw material for preparing absorption slurry; or the raw material is returned to a calcium carbide production workshop and then is synthesized into calcium carbide with coke; or as a byproduct for cement production;
s7, obtaining high-concentration SO in the step (3) 2 The gas can be used as a raw material for producing sulfuric acid, so that the recycling of sulfur resources is realized; high purity CO obtained in step (5) 2 The gas can be used as an industrial raw material after further separation and purification, so that the cyclic utilization of carbon resources is realized;
s8, treating the coal-fired flue gas by a secondary gas absorption device, and SO in the flue gas 2 And CO 2 Is removed and subsequently treated to remove NO x The pollutants can be discharged after reaching the standard.
2. The method for desulfurizing and carbon sequestration of coal-fired flue gas by using carbide slag slurry as claimed in claim 1, wherein the pretreatment in step (1) is gravity settling separation, and then further concentration and dehydration are carried out to obtain absorption slurry with a solid content of 20-40%.
3. The method for desulfurizing and carbon sequestration of coal-fired flue gas by using carbide slag slurry according to claim 1, wherein the coal-fired flue gas in the step (2) is any one or more of coal-fired power plant flue gas, coal-fired boiler tail gas and cement industry flue gas.
4. Use according to claim 1The method for desulfurizing and carbon-fixing the coal-fired flue gas by the carbide slag slurry is characterized in that the coal-fired flue gas in the step (2) is flue gas subjected to dust removal treatment, and the main component of the coal-fired flue gas comprises SO 2 、CO 2 、NO x 、N 2 、O 2 Water vapor and heavy metals, in which SO 2 The content is 2000-5000 mg/Nm 3 ，CO 2 The volume fraction is 10% -15%.
5. The method for desulfurizing and carbon sequestration of coal-fired flue gas by using carbide slag slurry as claimed in claim 1, wherein the temperature of the reduction calcination in the step (3) is 700-900 ℃.
6. The method for desulfurizing and carbon sequestration of coal-fired flue gas by using carbide slag slurry according to claim 1, wherein the primary gas absorption device and the secondary gas absorption device are spray towers or bubble towers; the first-stage gas absorption device is used for desulfurization, the second-stage gas absorption device is used for carbon fixation, and the absorption slurry is pretreated carbide slag slurry.
7. The method for desulfurizing and carbon sequestration of coal-fired flue gas using carbide slag slurry as claimed in claim 1, wherein said high concentration of SO is 2 The gas volume fraction is 40% -50%; the high purity CO 2 The gas volume fraction is not less than 95%.
CN202210053548.7A 2022-01-18 2022-01-18 Method for desulfurizing and carbon-fixing coal-fired flue gas by using carbide slag slurry Pending CN115006982A (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN116255638A (en) * 2023-04-19 2023-06-13 山东大学 Boiler tail gas purification system and electrochemical waste wet method carbon fixing method thereof

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