CN117443176A - Semi-dry desulfurization process for replacing limestone and slaked lime with carbide slag - Google Patents
Semi-dry desulfurization process for replacing limestone and slaked lime with carbide slag Download PDFInfo
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- CN117443176A CN117443176A CN202311679298.9A CN202311679298A CN117443176A CN 117443176 A CN117443176 A CN 117443176A CN 202311679298 A CN202311679298 A CN 202311679298A CN 117443176 A CN117443176 A CN 117443176A
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- carbide slag
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- 239000002893 slag Substances 0.000 title claims abstract description 134
- 238000006477 desulfuration reaction Methods 0.000 title claims abstract description 86
- 230000023556 desulfurization Effects 0.000 title claims abstract description 86
- 238000000034 method Methods 0.000 title claims abstract description 33
- AXCZMVOFGPJBDE-UHFFFAOYSA-L calcium dihydroxide Chemical compound [OH-].[OH-].[Ca+2] AXCZMVOFGPJBDE-UHFFFAOYSA-L 0.000 title claims abstract description 24
- 239000000920 calcium hydroxide Substances 0.000 title claims abstract description 24
- 235000011116 calcium hydroxide Nutrition 0.000 title claims abstract description 24
- 229910001861 calcium hydroxide Inorganic materials 0.000 title claims abstract description 24
- 235000019738 Limestone Nutrition 0.000 title claims abstract description 23
- 239000006028 limestone Substances 0.000 title claims abstract description 23
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 claims abstract description 18
- 239000003546 flue gas Substances 0.000 claims abstract description 18
- 238000001035 drying Methods 0.000 claims abstract description 12
- 239000002002 slurry Substances 0.000 claims abstract description 7
- 239000006228 supernatant Substances 0.000 claims abstract description 5
- 239000002245 particle Substances 0.000 claims description 33
- 239000011575 calcium Substances 0.000 claims description 22
- 239000000428 dust Substances 0.000 claims description 13
- 239000003638 chemical reducing agent Substances 0.000 claims description 7
- 238000005507 spraying Methods 0.000 claims description 7
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 claims description 4
- 229910052791 calcium Inorganic materials 0.000 claims description 4
- 238000007599 discharging Methods 0.000 claims description 4
- 235000008733 Citrus aurantifolia Nutrition 0.000 claims description 3
- 235000011941 Tilia x europaea Nutrition 0.000 claims description 3
- 239000004571 lime Substances 0.000 claims description 3
- 241000208125 Nicotiana Species 0.000 claims description 2
- 235000002637 Nicotiana tabacum Nutrition 0.000 claims description 2
- 230000000903 blocking effect Effects 0.000 claims 1
- 239000000126 substance Substances 0.000 abstract description 5
- 239000002918 waste heat Substances 0.000 abstract description 3
- 239000002894 chemical waste Substances 0.000 abstract description 2
- 239000005997 Calcium carbide Substances 0.000 description 18
- CLZWAWBPWVRRGI-UHFFFAOYSA-N tert-butyl 2-[2-[2-[2-[bis[2-[(2-methylpropan-2-yl)oxy]-2-oxoethyl]amino]-5-bromophenoxy]ethoxy]-4-methyl-n-[2-[(2-methylpropan-2-yl)oxy]-2-oxoethyl]anilino]acetate Chemical compound CC1=CC=C(N(CC(=O)OC(C)(C)C)CC(=O)OC(C)(C)C)C(OCCOC=2C(=CC=C(Br)C=2)N(CC(=O)OC(C)(C)C)CC(=O)OC(C)(C)C)=C1 CLZWAWBPWVRRGI-UHFFFAOYSA-N 0.000 description 18
- ODINCKMPIJJUCX-UHFFFAOYSA-N calcium oxide Inorganic materials [Ca]=O ODINCKMPIJJUCX-UHFFFAOYSA-N 0.000 description 17
- 238000006243 chemical reaction Methods 0.000 description 17
- 239000000292 calcium oxide Substances 0.000 description 10
- 238000000354 decomposition reaction Methods 0.000 description 10
- 239000000463 material Substances 0.000 description 10
- 238000005516 engineering process Methods 0.000 description 8
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 6
- 238000012360 testing method Methods 0.000 description 5
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 4
- 238000001354 calcination Methods 0.000 description 4
- 239000003245 coal Substances 0.000 description 4
- 238000002485 combustion reaction Methods 0.000 description 4
- 238000002474 experimental method Methods 0.000 description 3
- 239000000203 mixture Substances 0.000 description 3
- 239000000843 powder Substances 0.000 description 3
- 230000035484 reaction time Effects 0.000 description 3
- 239000007787 solid Substances 0.000 description 3
- RAHZWNYVWXNFOC-UHFFFAOYSA-N Sulphur dioxide Chemical compound O=S=O RAHZWNYVWXNFOC-UHFFFAOYSA-N 0.000 description 2
- BRPQOXSCLDDYGP-UHFFFAOYSA-N calcium oxide Chemical compound [O-2].[Ca+2] BRPQOXSCLDDYGP-UHFFFAOYSA-N 0.000 description 2
- 230000003009 desulfurizing effect Effects 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 239000007789 gas Substances 0.000 description 2
- 230000005484 gravity Effects 0.000 description 2
- 239000010440 gypsum Substances 0.000 description 2
- 229910052602 gypsum Inorganic materials 0.000 description 2
- 239000012535 impurity Substances 0.000 description 2
- UQSXHKLRYXJYBZ-UHFFFAOYSA-N iron oxide Inorganic materials [Fe]=O UQSXHKLRYXJYBZ-UHFFFAOYSA-N 0.000 description 2
- 239000000395 magnesium oxide Substances 0.000 description 2
- CPLXHLVBOLITMK-UHFFFAOYSA-N magnesium oxide Inorganic materials [Mg]=O CPLXHLVBOLITMK-UHFFFAOYSA-N 0.000 description 2
- AXZKOIWUVFPNLO-UHFFFAOYSA-N magnesium;oxygen(2-) Chemical compound [O-2].[Mg+2] AXZKOIWUVFPNLO-UHFFFAOYSA-N 0.000 description 2
- TWNQGVIAIRXVLR-UHFFFAOYSA-N oxo(oxoalumanyloxy)alumane Chemical compound O=[Al]O[Al]=O TWNQGVIAIRXVLR-UHFFFAOYSA-N 0.000 description 2
- NDLPOXTZKUMGOV-UHFFFAOYSA-N oxo(oxoferriooxy)iron hydrate Chemical compound O.O=[Fe]O[Fe]=O NDLPOXTZKUMGOV-UHFFFAOYSA-N 0.000 description 2
- 230000000704 physical effect Effects 0.000 description 2
- 239000011347 resin Substances 0.000 description 2
- 229920005989 resin Polymers 0.000 description 2
- 239000000377 silicon dioxide Substances 0.000 description 2
- 235000012239 silicon dioxide Nutrition 0.000 description 2
- 239000011593 sulfur Substances 0.000 description 2
- 229910052717 sulfur Inorganic materials 0.000 description 2
- 239000002699 waste material Substances 0.000 description 2
- 230000004580 weight loss Effects 0.000 description 2
- 229910004261 CaF 2 Inorganic materials 0.000 description 1
- 241000196324 Embryophyta Species 0.000 description 1
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 description 1
- 238000005054 agglomeration Methods 0.000 description 1
- 230000002776 aggregation Effects 0.000 description 1
- HSFWRNGVRCDJHI-UHFFFAOYSA-N alpha-acetylene Natural products C#C HSFWRNGVRCDJHI-UHFFFAOYSA-N 0.000 description 1
- 238000000498 ball milling Methods 0.000 description 1
- 230000015556 catabolic process Effects 0.000 description 1
- 239000003153 chemical reaction reagent Substances 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 230000000052 comparative effect Effects 0.000 description 1
- 230000002950 deficient Effects 0.000 description 1
- 238000001514 detection method Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000004134 energy conservation Methods 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 238000003912 environmental pollution Methods 0.000 description 1
- 125000002534 ethynyl group Chemical group [H]C#C* 0.000 description 1
- 238000001125 extrusion Methods 0.000 description 1
- 238000001914 filtration Methods 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 238000012423 maintenance Methods 0.000 description 1
- 238000001556 precipitation Methods 0.000 description 1
- 238000005070 sampling Methods 0.000 description 1
- 239000000779 smoke Substances 0.000 description 1
- 239000002910 solid waste Substances 0.000 description 1
- 239000004575 stone Substances 0.000 description 1
- 238000002411 thermogravimetry Methods 0.000 description 1
- 239000002912 waste gas Substances 0.000 description 1
- 239000002351 wastewater Substances 0.000 description 1
Classifications
-
- 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
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
- B01D53/34—Chemical or biological purification of waste gases
- B01D53/74—General processes for purification of waste gases; Apparatus or devices specially adapted therefor
- B01D53/75—Multi-step processes
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
- B01D53/34—Chemical or biological purification of waste gases
- B01D53/74—General processes for purification of waste gases; Apparatus or devices specially adapted therefor
- B01D53/81—Solid phase processes
- B01D53/83—Solid phase processes with moving reactants
Landscapes
- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Environmental & Geological Engineering (AREA)
- Health & Medical Sciences (AREA)
- Biomedical Technology (AREA)
- Analytical Chemistry (AREA)
- General Chemical & Material Sciences (AREA)
- Oil, Petroleum & Natural Gas (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Treating Waste Gases (AREA)
Abstract
The invention discloses a semi-dry desulfurization process for replacing limestone and slaked lime with carbide slag, which relates to the field of desulfurization processes, and comprises the following steps: standing the carbide slag slurry to obtain carbide supernatant and carbide slag; step two: transporting the carbide slag to a temporary storage site through a transport vehicle; step three: the method is characterized in that carbide slag is guided into a roller dryer for drying in a belt conveying mode, high-temperature flue gas discharged by a power plant is introduced into the roller dryer, the carbide slag is used as chemical waste in a semi-dry desulfurization process for replacing limestone and slaked lime, most carbide slag is treated in a landfill mode at present, a large amount of experimental data is used as support, wet carbide slag is dried by waste heat of the power plant and the like, and then the wet carbide slag is applied to a semi-dry desulfurization process to well solve the problem that the chemical plant pollutes the environment, and meanwhile, considerable operating cost is saved for a utilization unit.
Description
Technical Field
The invention relates to the field of desulfurization processes, in particular to a semi-dry desulfurization process for replacing limestone and slaked lime with carbide slag.
Background
At present, the boiler desulfurization technology mainly comprises 3 types: 1. desulfurization before boiler combustion, namely clean coal technology; 2. desulfurization during combustion (in-furnace), such as circulating fluidized bed combustion techniques; 3. the desulfurization technology after combustion, namely flue gas desulfurization, is less in domestic application, the flue gas desulfurization technology of the thermal power generating unit is mainly flue gas desulfurization, namely limestone-gypsum wet process is mainly, the desulfurization efficiency is higher (more than 95 percent), the adaptability to coal quality is strong, but the problems that the engineering quantity is large, the hidden danger of gypsum rain exists in operation, desulfurization wastewater cannot be treated and the like exist, and the semi-dry desulfurization technology is used as one of the desulfurization technology genres, is widely applied to medium-capacity and small-capacity units, low-sulfur coal and water-deficient areas, can realize standard emission of sulfur dioxide by matching with the original in-furnace desulfurization technology, and has wider adaptability to sulfur content of coal due to the high price of a desulfurizing agent-quicklime.
Disclosure of Invention
The invention aims to solve the problems, and designs a semi-dry desulfurization process for replacing limestone and slaked lime with carbide slag.
The semi-dry desulfurization process for replacing limestone and slaked lime with carbide slag is characterized by comprising the following steps:
step one: standing the carbide slag slurry to obtain carbide supernatant and carbide slag;
step two: transporting the carbide slag to a temporary storage site through a transport vehicle;
step three: the carbide slag is guided into a roller dryer for drying in a belt conveying mode, and high-temperature flue gas discharged by a power plant is introduced into the roller dryer;
step four: after the carbide slag and the high-temperature flue gas discharged by the power plant are subjected to full heat exchange until the carbide slag is dried to meet the specified requirement, discharging the carbide slag from the roller dryer, crushing the carbide slag by a ball mill crusher, and entering a storage bin for storage after crushing;
step five: the storage bin is divided into a limestone bin and a lime slaking bin, and carbide slag in the limestone bin is directly blown into the circulating fluidized bed boiler to finish preliminary desulfurization by calcium spraying in the boiler;
step six: and (3) carrying out secondary desulfurization on the flue gas discharged by the circulating fluidized bed boiler through semi-dry desulfurization equipment, and spraying carbide slag of a slaked lime bin into the semi-dry desulfurization equipment in the secondary desulfurization process.
Preferably, the roller dryer comprises a roller, a first base, a second base and a third base, wherein the first base, the second base and the third base are of inclined structures, tugs are respectively arranged on the first base and the third base, wheel belts are arranged on the tugs, the wheel belts are connected with the roller, baffle wheels are arranged on two sides of the tugs on the third base, a motor is arranged on the second base, a speed reducer is connected to a motor driving end, a pinion is connected to the speed reducer, a large gear is fixedly arranged on the roller, and the pinion is meshed with the large gear.
Preferably, the semi-dry desulfurization device comprises a desulfurization reactor, the desulfurization reactor is of a U-shaped structure, one end of the desulfurization reactor is a flue gas input end, the other end of the desulfurization reactor is connected with a dust remover, an ash bucket is arranged at the lower end of the dust remover, the lower ends of the flue pipe and the desulfurization reactor are respectively connected with a bin pump, an NID (NID-type) mixer is connected to the desulfurization reactor and is close to the wall surface of the dust remover, a boiler induced draft fan is connected to the dust remover, and a chimney is connected to the other end of the boiler induced draft fan.
Preferably, the particles of crushed carbide slag in the fourth step are larger than 1mm, and the particles of crushed carbide slag are larger than 1mm and account for 0.5% of the total carbide slag particles.
Preferably, the particles of the crushed carbide slag in the fourth step are 1mm-0.5mm, and the particles of the crushed carbide slag are 1mm-0.5mm accounting for 55% of the total carbide slag particles.
Preferably, the particles of crushed carbide slag in the fourth step are smaller than 0.5mm, and the particles of crushed carbide slag are smaller than 0.5mm and account for 45.5% of the total carbide slag particles.
The semi-dry desulfurization process using carbide slag to replace limestone and slaked lime is characterized in that the carbide slag is used as chemical waste, most of carbide slag is treated in a landfill mode at present, a large amount of experimental data is used as support, wet carbide slag is dried by waste heat of a power plant and the like, and the wet carbide slag is applied to the semi-dry desulfurization process to achieve good environmental pollution of solid waste of the chemical plant, and meanwhile considerable operating cost is saved for a utilization unit.
Drawings
FIG. 1 is a flow chart of the present invention;
FIG. 2 is a diagram of a tumble dryer according to the present invention;
FIG. 3 is a diagram of a semi-dry desulfurization apparatus according to the present invention;
in the figure, 1, a first base; 2. a second base; 3. a third base; 4. towing wheel; 5. a wheel belt; 6. a roller; 7. a catch wheel; 8. a motor; 9. a speed reducer; 10. a pinion gear; 11. a large gear; 12. a desulfurization reactor; 13. a dust remover; 14. an ash bucket; 15. a bin pump; 16. a NID mixer; 17. a boiler induced draft fan; 18. and (5) a chimney.
Detailed Description
The invention is specifically described below with reference to the accompanying drawings, as shown in fig. 1-3, a semi-dry desulfurization process for replacing limestone and slaked lime with carbide slag, comprising the following steps:
step one: standing the carbide slag slurry to obtain carbide supernatant and carbide slag;
step two: transporting the carbide slag to a temporary storage site through a transport vehicle;
step three: the carbide slag is guided into a roller dryer for drying in a belt conveying mode, and high-temperature flue gas discharged by a power plant is introduced into the roller dryer;
step four: after the carbide slag and the high-temperature flue gas discharged by the power plant are subjected to full heat exchange until the carbide slag is dried to meet the specified requirement, discharging the carbide slag from the roller dryer, crushing the carbide slag by a ball mill crusher, and entering a storage bin for storage after crushing;
step five: the storage bin is divided into a limestone bin and a lime slaking bin, and carbide slag in the limestone bin is directly blown into the circulating fluidized bed boiler to finish preliminary desulfurization by calcium spraying in the boiler;
step six: and (3) carrying out secondary desulfurization on the flue gas discharged by the circulating fluidized bed boiler through semi-dry desulfurization equipment, and spraying carbide slag of a slaked lime bin into the semi-dry desulfurization equipment in the secondary desulfurization process.
Further, the roller dryer comprises a roller, a first base, a second base and a third base, wherein the first base, the second base and the third base are of inclined structures, tugs are respectively arranged on the first base and the third base, wheel belts are arranged on the tugs, the wheel belts are connected with the roller, catch wheels are arranged on two sides of the tugs on the third base, a motor is arranged on the second base, a speed reducer is connected onto a motor driving end, a pinion is connected onto the speed reducer, a large gear is fixedly arranged on the roller, and the pinion is meshed with the large gear.
Further, semi-dry desulfurization equipment includes the desulfurization reactor, the desulfurization reactor is U type structure, desulfurization reactor one end is flue gas input and the other end connects the dust remover, the ash bucket is installed to the dust remover lower extreme, tobacco pipe and desulfurization reactor lower extreme are connected with the storehouse pump respectively, be connected with the NID blender on the desulfurization reactor and be close to on the wall of dust remover, be connected with the boiler induced draft fan on the dust remover, the boiler induced draft fan other end is connected with the chimney.
Further, in the fourth step, the crushed particles of the carbide slag are larger than 1mm, and the crushed particles of the carbide slag are larger than 1mm and account for 0.5% of the total carbide slag particles.
Further, the particles of the crushed carbide slag in the fourth step are 1mm-0.5mm, and the particles of the crushed carbide slag are 1mm-0.5mm accounting for 55% of the total carbide slag particles.
Further, in the fourth step, the crushed particles of the carbide slag are smaller than 0.5mm, and the crushed particles of the carbide slag are smaller than 0.5mm and account for 45.5% of the total carbide slag particles.
The components in this case are connected in sequence by a person skilled in the art, and specific connection and operation sequence should be referred to the following working principle, and the detailed connection means are known in the art, and the following working principle and process are mainly described.
Examples: the calcium carbide slag is waste slag taking calcium hydroxide as a main component after calcium carbide is hydrolyzed to obtain acetylene gas. The chemical composition of the carbide slag is related to the quality of the carbide, and the basic composition comprises 63.93% of calcium oxide, 1.27% of magnesium oxide, 0.50% of aluminum oxide, 0.96% of ferric oxide, 7.90% of silicon dioxide and 24.30% of loss on ignition. The specific gravity of the carbide slag is 1.82, the dry volume weight is 0.683 g/cc, the wet volume weight is 1.366 g/cc, and the screen allowance of the fineness passing through 4900-hole screen per square centimeter is 14.4%. At present, many chemical enterprises for producing PVC paste resin consume about 1.5 tons of calcium carbide, and about 10 tons of calcium carbide slag slurry can be produced by reacting 1 ton of calcium carbide in a generator, and the solid content is about 10 percent, for example, about 2 tons of calcium carbide slag is produced by press filtration into calcium carbide slag with the solid content of 50 percent, so that 3 tons of calcium carbide slag can be produced by producing one ton of PVC paste resin.
Calcium carbide (CaC) 2 ) The main chemical reaction formula of the added water is as follows:
CaC 2 +H 2 O＝C 2 H 2 +Ca(OH) 2 +127.3 KJ/g
At the same time of the reaction of calcium carbide and water, impurities in the calcium carbide also participate in the reaction to generate calcium hydroxide and other gases:
CaO+H 2 O＝Ca(OH) 2
CaS+2H 2 O＝Ca(OH) 2 +H 2 S↑
Ca 3 N 2 +6H 2 O＝3Ca(OH) 2 +2NH 3 ↑
Ca 3 P 2 +6H 2 O＝3Ca(OH) 2 +2PH 3 ↑
Ca 2 Si+4H 2 O＝2Ca(OH) 2 +SiH 4 ↑
Ca 3 As 2 +6H 2 O＝3Ca(OH) 2 +2AsH 3 ↑
the dry calcium carbide waste residue mainly contains Ca (OH) 2 Can be used as a substitute for slaked lime.
Physical properties of carbide slag
The main component of carbide slag is Ca (OH) 2 Due to Ca(OH) 2 Has small solubility in water, and solid Ca (OH) 2 Particles are separated out from the solution, and calcium carbide slag slurry is formed through the processes of inter-particle collision, extrusion, agglomeration, precipitation and the like, and calcium carbide supernatant and calcium carbide slag are obtained after the calcium carbide slag slurry is stood.
TABLE 1 composition of typical carbide slag
TABLE 2 particle size distribution of exemplary carbide slag
As can be seen from tables 1 and 2, ca (OH) in carbide slag 2 The content is 58.69%, and if the water is not considered, the content can reach 85.94%, and the content is very high. Particles with a particle size of less than 80 μm are also up to 63.87%. From the physical property point of view, carbide slag is more suitable as a desulfurizing agent.
2. Carbide slag drying and crushing process
The moisture content of carbide slag reaches about 40% after leaving the factory, which severely restricts the application of the dry desulfurization process. Through the market
The method selects the waste gas and waste heat drying technology of the power plant to carry out carbide slag drying work. The rotary single-drum dryer is equipment which drives materials to perform full heat exchange with high-temperature smoke through a lifting plate which rotates and is arranged on a cylinder body, so that the materials are dried, and has the characteristics of good drying effect, large capacity, high operation rate, energy conservation, environmental protection, simplicity and convenience in operation and maintenance, long service life of the whole dryer and the like. According to the drying process, the circumferential lifting plate combination device with various angles is arranged in the cylinder body, so that the heat exchange rate can be greatly improved, the drying time is shortened, and the drying cost is reduced.
Principle of drying
The material enters the dryer through the feeding device, and the cylinder body slowly rotates in an inclined state, so that the material moves from a high end to a low end in the axial direction, and the material is continuously lifted, thrown away and moved downwards in the circumferential direction by the lifting plate in the moving process, so that the material and high-temperature flue gas discharged by a power plant are subjected to full heat exchange until the material is dried to a specified requirement, and the dried material is discharged from the discharging device.
The dried carbide slag is crushed directly by a conventional ball milling system to reach qualified granularity and then enters a storage bin for temporary storage for standby.
Carbide slag dry powder detection
The dried carbide slag presents gray powder in appearance, and enters a dry desulfurization system material storage system, and the sampling and testing components are as follows;
table 3 carbide slag dry powder test meter
Thermogravimetric analysis of chemical characteristics and desulfurization performance of carbide slag
Calcium oxide in carbide slag accounts for 63.93%, magnesium oxide accounts for 1.27%, aluminum oxide accounts for 0.50%, ferric oxide accounts for 0.96%, silicon dioxide accounts for 7.90%, and loss on ignition accounts for 24.30%. The specific gravity of the carbide slag is 1.82, the dry volume weight is 0.683 g/cc, the wet volume weight is 1.366 g/cc, and the screen allowance of the fineness passing through 4900-hole screen per square centimeter is 14.4%.
And (3) performing carbide slag calcination and decomposition experiments:
the calcination and decomposition curve of the carbide slag in the thermobalance heating furnace represents the calcination process of the carbide slag in the air. The calcination and decomposition of carbide slag are divided into three stages:
in the first stage, the weight loss of water and part of impurities is 15 minutes, the initial decomposition temperature is 35 ℃, the decomposition end temperature is 356 ℃, the highest reaction rate is 0.50mg/min, and the corresponding temperature of the highest reaction rate is 164 ℃;
the second stage is Ca (OH) 2 The decomposition weight loss time is 10 minutes, the initial decomposition temperature is 356 ℃, the decomposition end temperature is 566 ℃, the highest reaction rate is 5.65mg/min, and the temperature corresponding to the highest reaction rate is 482 ℃;
the third stage is CaCO 3 Breakdown loss ofThe weight, time was 10 minutes, the initial decomposition temperature was 566 ℃, the decomposition end temperature was 755 ℃, the highest reaction rate was 1.75mg/min, and the temperature corresponding to the highest reaction rate was 699 ℃.
And (3) performing carbide slag desulfurization experiments:
reaction capacity coefficient K:
and (5) representing the final reachable degree of the carbide slag desulfurization reaction. The larger the K value is, the higher the final reachable degree of the carbide slag desulfurization reaction is. The discrimination criteria are as follows:
| grade of reaction ability | Coefficient of reaction ability K | Reactive capability attributes |
| Ⅰ | >53 | High height |
| Ⅱ | 41-53 | Higher height |
| Ⅲ | 23-41 | Medium and medium |
| Ⅳ | 14-23 | Lower level |
| Ⅴ | <14 | Low and low |
The K value of the carbide slag is 60.00, and the desulfurization reaction of the carbide slag can reach high degree finally.
The utilization rate is as follows:
and (3) characterizing the utilization degree of CaO in the carbide slag when the reaction time is 60 minutes. The discrimination criteria are as follows:
| discrimination of | CaO utilization rate |
| High height | >21 |
| Higher height | 19-21 |
| Medium and medium | 16-19 |
| Lower level | 13-16 |
| Low and low | <13 |
When the reaction time of the carbide slag is 60 minutes, the CaO utilization rate is 43.61, and the CaO utilization rate is high. The above indexes are combined to obtain:
the desulfurization performance of the carbide slag is good, the final reachable degree of the desulfurization reaction is high, when the reaction time is 60 minutes,
the CaO utilization rate is also high.
Particle size: the granularity of the carbide slag is 0.5% of that of the carbide slag with the granularity of more than 1mm, 55% of that of the carbide slag with the granularity of 1mm-0.5mm and 44.5% of that of the carbide slag with the granularity of less than 0.5 mm.
Dry desulfurization principle in carbide slag furnace: the principle of the dry desulfurization process in the carbide slag furnace is that stone is utilized;
dry reagents for ash or dry slaked lime with SO in flue gas 2 The reaction is as follows:
CaO+H 2 0＝Ca(OH) 2
Ca(OH) 2 +S0 2 ＝CaSO 3 +1/2H 2 0+1/2H 2 0
CaSO 3 ·1/2H 2 O+3/2H 2 0+1/20 2 ＝CaS0 4
principle of carbide slag semi-dry desulfurization:
Ca(OH) 2 +SO 2 ＝CaSO 3 +H 2 O
Ca(OH) 2 +2HF＝CaF 2 +2H 2 O
Ca(OH) 2 +SO 3 ＝CaSO 4 +H 2 O
Ca(OH) 2 +2HCl＝CaCl 2 +2H 2 O
CaSO 3 +1/2O 2 ＝CaSO 4
field test:
through the desulfurization mechanism, desulfurization characteristics and experiments of carbide slag, the desulfurization performance of the carbide slag is obviously superior to that of limestone. The test work was performed in 2022 in a unit No. 2 desulfurization system for 168 hours, and the results were as follows:
table four test comparative data
According to the data, the calcium spraying efficiency in the furnace is greatly improved after the carbide slag is added, and a large amount of slaked lime is saved. The investment of carbide slag has no influence on the operation parameters of the semi-dry desulfurization system. According to 1 unit, the utilization of the unit is 5000 hours, the generated energy is 7.5 hundred million kilowatt hours, and compared with the utilization of limestone and slaked lime, the addition of carbide slag can save 469.7 ten thousand yuan per year of desulfurization material cost, and the economic benefit is obvious.
The above technical solution only represents the preferred technical solution of the present invention, and some changes that may be made by those skilled in the art to some parts of the technical solution represent the principles of the present invention, and the technical solution falls within the scope of the present invention.
Claims (6)
1. The semi-dry desulfurization process for replacing limestone and slaked lime with carbide slag is characterized by comprising the following steps of:
step one: standing the carbide slag slurry to obtain carbide supernatant and carbide slag;
step two: transporting the carbide slag to a temporary storage site through a transport vehicle;
step three: the carbide slag is guided into a roller dryer for drying in a belt conveying mode, and high-temperature flue gas discharged by a power plant is introduced into the roller dryer;
step four: after the carbide slag and the high-temperature flue gas discharged by the power plant are subjected to full heat exchange until the carbide slag is dried to meet the specified requirement, discharging the carbide slag from the roller dryer, crushing the carbide slag by a ball mill crusher, and entering a storage bin for storage after crushing;
step five: the storage bin is divided into a limestone bin and a lime slaking bin, and carbide slag in the limestone bin is directly blown into the circulating fluidized bed boiler to finish preliminary desulfurization by calcium spraying in the boiler;
step six: and (3) carrying out secondary desulfurization on the flue gas discharged by the circulating fluidized bed boiler through semi-dry desulfurization equipment, and spraying carbide slag of a slaked lime bin into the semi-dry desulfurization equipment in the secondary desulfurization process.
2. The semi-dry desulfurization process for replacing limestone and slaked lime by using carbide slag according to claim 1, wherein the roller dryer comprises a roller, a first base, a second base and a third base, wherein the first base, the second base and the third base are of inclined structures, tugs are respectively arranged on the first base and the third base, a wheel belt is arranged on the tugs, the wheel belt is connected with the roller, blocking wheels are arranged on two sides of the tugs on the third base, a motor is arranged on the second base, a speed reducer is connected to a driving end of the motor, a pinion is connected to the speed reducer, a large gear is fixedly arranged on the roller, and the pinion is meshed with the large gear.
3. The semi-dry desulfurization process for replacing limestone and slaked lime with carbide slag according to claim 1, wherein the semi-dry desulfurization device comprises a desulfurization reactor, the desulfurization reactor is of a U-shaped structure, one end of the desulfurization reactor is a flue gas input end, the other end of the desulfurization reactor is connected with a dust remover, an ash bucket is arranged at the lower end of the dust remover, the tobacco pipe and the lower end of the desulfurization reactor are respectively connected with a bin pump, an NID (NID-mixer) is connected to the desulfurization reactor and is close to the wall surface of the dust remover, a boiler induced draft fan is connected to the dust remover, and a chimney is connected to the other end of the boiler induced draft fan.
4. The semi-dry desulfurization process using carbide slag to replace limestone and slaked lime according to claim 1, wherein the particles of carbide slag crushed in the fourth step are larger than 1mm, and the particles of carbide slag crushed are larger than 1mm and account for 0.5% of the total carbide slag particles.
5. The semi-dry desulfurization process for replacing limestone and slaked lime with carbide slag according to claim 1, wherein the carbide slag crushed particles in the fourth step are 1mm-0.5mm, and the carbide slag crushed particles are 1mm-0.5mm accounting for 55% of the total carbide slag particles.
6. The semi-dry desulfurization process using carbide slag to replace limestone and slaked lime according to claim 4, wherein the particles of carbide slag crushed in the fourth step are less than 0.5mm, and the particles of carbide slag crushed are less than 0.5mm and account for 45.5% of the total carbide slag particles.
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