CN114950109A - Double-alkali semi-dry desulfurization method for flue gas - Google Patents
Double-alkali semi-dry desulfurization method for flue gas Download PDFInfo
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- flue gas
- desulfurization
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- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 title claims abstract description 151
- 239000003546 flue gas Substances 0.000 title claims abstract description 151
- 238000006477 desulfuration reaction Methods 0.000 title claims abstract description 82
- 230000023556 desulfurization Effects 0.000 title claims abstract description 82
- 238000000034 method Methods 0.000 title claims abstract description 54
- 239000003513 alkali Substances 0.000 title claims abstract description 53
- 230000003009 desulfurizing effect Effects 0.000 claims abstract description 57
- 239000007921 spray Substances 0.000 claims abstract description 35
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 30
- 239000003795 chemical substances by application Substances 0.000 claims abstract description 24
- 238000001816 cooling Methods 0.000 claims abstract description 16
- 239000000428 dust Substances 0.000 claims abstract description 15
- 238000006243 chemical reaction Methods 0.000 claims abstract description 12
- 238000002156 mixing Methods 0.000 claims abstract description 10
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 claims description 29
- 239000000779 smoke Substances 0.000 claims description 20
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 claims description 14
- 239000011593 sulfur Substances 0.000 claims description 13
- 229910052717 sulfur Inorganic materials 0.000 claims description 13
- JGIATAMCQXIDNZ-UHFFFAOYSA-N calcium sulfide Chemical compound [Ca]=S JGIATAMCQXIDNZ-UHFFFAOYSA-N 0.000 claims description 8
- KWYUFKZDYYNOTN-UHFFFAOYSA-M Potassium hydroxide Chemical compound [OH-].[K+] KWYUFKZDYYNOTN-UHFFFAOYSA-M 0.000 claims description 6
- 238000005507 spraying Methods 0.000 claims description 6
- 239000002585 base Substances 0.000 claims description 4
- 238000002347 injection Methods 0.000 claims description 3
- 239000007924 injection Substances 0.000 claims description 3
- 239000005864 Sulphur Substances 0.000 claims 1
- RAHZWNYVWXNFOC-UHFFFAOYSA-N Sulphur dioxide Chemical compound O=S=O RAHZWNYVWXNFOC-UHFFFAOYSA-N 0.000 abstract description 18
- 230000000694 effects Effects 0.000 abstract description 11
- 230000002195 synergetic effect Effects 0.000 abstract description 5
- 239000007788 liquid Substances 0.000 description 10
- 239000011575 calcium Substances 0.000 description 9
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 description 8
- 238000010521 absorption reaction Methods 0.000 description 8
- 229910052791 calcium Inorganic materials 0.000 description 8
- 230000000052 comparative effect Effects 0.000 description 8
- DGAQECJNVWCQMB-PUAWFVPOSA-M Ilexoside XXIX Chemical compound C[C@@H]1CC[C@@]2(CC[C@@]3(C(=CC[C@H]4[C@]3(CC[C@@H]5[C@@]4(CC[C@@H](C5(C)C)OS(=O)(=O)[O-])C)C)[C@@H]2[C@]1(C)O)C)C(=O)O[C@H]6[C@@H]([C@H]([C@@H]([C@H](O6)CO)O)O)O.[Na+] DGAQECJNVWCQMB-PUAWFVPOSA-M 0.000 description 6
- 239000011734 sodium Substances 0.000 description 6
- 229910052708 sodium Inorganic materials 0.000 description 6
- 235000008733 Citrus aurantifolia Nutrition 0.000 description 4
- 235000011941 Tilia x europaea Nutrition 0.000 description 4
- 238000001514 detection method Methods 0.000 description 4
- 239000004571 lime Substances 0.000 description 4
- GEHJYWRUCIMESM-UHFFFAOYSA-L sodium sulfite Chemical compound [Na+].[Na+].[O-]S([O-])=O GEHJYWRUCIMESM-UHFFFAOYSA-L 0.000 description 4
- 239000000843 powder Substances 0.000 description 3
- 239000000243 solution Substances 0.000 description 3
- CSNNHWWHGAXBCP-UHFFFAOYSA-L Magnesium sulfate Chemical compound [Mg+2].[O-][S+2]([O-])([O-])[O-] CSNNHWWHGAXBCP-UHFFFAOYSA-L 0.000 description 2
- AXCZMVOFGPJBDE-UHFFFAOYSA-L calcium dihydroxide Chemical compound [OH-].[OH-].[Ca+2] AXCZMVOFGPJBDE-UHFFFAOYSA-L 0.000 description 2
- 239000000920 calcium hydroxide Substances 0.000 description 2
- 235000011116 calcium hydroxide Nutrition 0.000 description 2
- 229910001861 calcium hydroxide Inorganic materials 0.000 description 2
- 238000007599 discharging Methods 0.000 description 2
- VTHJTEIRLNZDEV-UHFFFAOYSA-L magnesium dihydroxide Chemical compound [OH-].[OH-].[Mg+2] VTHJTEIRLNZDEV-UHFFFAOYSA-L 0.000 description 2
- 239000000347 magnesium hydroxide Substances 0.000 description 2
- 229910001862 magnesium hydroxide Inorganic materials 0.000 description 2
- JESHZQPNPCJVNG-UHFFFAOYSA-L magnesium;sulfite Chemical compound [Mg+2].[O-]S([O-])=O JESHZQPNPCJVNG-UHFFFAOYSA-L 0.000 description 2
- 238000004064 recycling Methods 0.000 description 2
- 230000008929 regeneration Effects 0.000 description 2
- 238000011069 regeneration method Methods 0.000 description 2
- 230000001105 regulatory effect Effects 0.000 description 2
- 238000000926 separation method Methods 0.000 description 2
- CDBYLPFSWZWCQE-UHFFFAOYSA-L sodium carbonate Substances [Na+].[Na+].[O-]C([O-])=O CDBYLPFSWZWCQE-UHFFFAOYSA-L 0.000 description 2
- 235000010265 sodium sulphite Nutrition 0.000 description 2
- 235000019738 Limestone Nutrition 0.000 description 1
- DWAQJAXMDSEUJJ-UHFFFAOYSA-M Sodium bisulfite Chemical compound [Na+].OS([O-])=O DWAQJAXMDSEUJJ-UHFFFAOYSA-M 0.000 description 1
- VEUACKUBDLVUAC-UHFFFAOYSA-N [Na].[Ca] Chemical compound [Na].[Ca] VEUACKUBDLVUAC-UHFFFAOYSA-N 0.000 description 1
- 230000002745 absorbent Effects 0.000 description 1
- 239000002250 absorbent Substances 0.000 description 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 239000006028 limestone Substances 0.000 description 1
- 229910003002 lithium salt Inorganic materials 0.000 description 1
- 159000000002 lithium salts Chemical class 0.000 description 1
- 239000000395 magnesium oxide Substances 0.000 description 1
- CPLXHLVBOLITMK-UHFFFAOYSA-N magnesium oxide Inorganic materials [Mg]=O CPLXHLVBOLITMK-UHFFFAOYSA-N 0.000 description 1
- 229910052943 magnesium sulfate Inorganic materials 0.000 description 1
- 235000019341 magnesium sulphate Nutrition 0.000 description 1
- AXZKOIWUVFPNLO-UHFFFAOYSA-N magnesium;oxygen(2-) Chemical compound [O-2].[Mg+2] AXZKOIWUVFPNLO-UHFFFAOYSA-N 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 229910052760 oxygen Inorganic materials 0.000 description 1
- 239000001301 oxygen Substances 0.000 description 1
- 239000002245 particle Substances 0.000 description 1
- 238000001556 precipitation Methods 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 230000001172 regenerating effect Effects 0.000 description 1
- 229910000029 sodium carbonate Inorganic materials 0.000 description 1
- 235000010267 sodium hydrogen sulphite Nutrition 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
- 230000009466 transformation Effects 0.000 description 1
- 238000005406 washing Methods 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
- B01D53/77—Liquid phase processes
- B01D53/78—Liquid phase processes with gas-liquid contact
-
- 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
- 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
- B01D2257/00—Components to be removed
- B01D2257/30—Sulfur compounds
- B01D2257/302—Sulfur oxides
-
- 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
- Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
- Y02A50/00—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE in human health protection, e.g. against extreme weather
- Y02A50/20—Air quality improvement or preservation, e.g. vehicle emission control or emission reduction by using catalytic converters
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 provides a double-alkali semi-dry desulfurization method for flue gas, which comprises the following steps: preheating the flue gas and then feeding the preheated flue gas into a desulfurizing tower, and mixing the flue gas with a desulfurizing agent at an inlet section of the desulfurizing tower to obtain mixed flue gas; after the mixed flue gas is accelerated by a Venturi section at the bottom of the desulfurization tower, cooling treatment is carried out at an outlet of the Venturi section by adopting alkali-containing spray water; the mixed flue gas after the temperature reduction treatment enters a circulating fluidized bed for desulfurization reaction to obtain desulfurized flue gas; and the desulfurized flue gas enters the next treatment working section after being subjected to dust removal treatment. Aiming at the problem that the traditional semi-dry desulfurization method has limited desulfurization effect when facing high-sulfur-content flue gas, the alkali is added in the spray water process and acts with a desulfurizer in a synergistic manner, so that the desulfurization effect of the desulfurization tower is maximized, the utilization efficiency of the device is improved, the complexity of the process is reduced, and the standard emission of sulfur dioxide is realized.
Description
Technical Field
The invention belongs to the field of flue gas treatment, relates to a semi-dry desulfurization method for flue gas, and particularly relates to a double-alkali semi-dry desulfurization method.
Background
The sulfur content of the flue gas is generally 200-1500 mg/m by the traditional semi-dry desulfurization technology 3 The ultra-low emission requirement can be basically met; as the sulfur content of the flue gas increases, the desulfurization efficiency is inevitably reduced if SO 2 The content is more than 2000mg/m 3 And the CFB semi-dry method is adopted for desulfurization alone, so that ultralow emission is difficult to achieve, if the desulfurization efficiency is required to reach more than 90%, on one hand, more lime or slaked lime is consumed, and on the other hand, the operation temperature is required to be reduced.
The circulating fluidized bed semidry method desulfurization device mainly comprises a flue system, a desulfurization tower system, a desulfurization bag-type dust remover transformation system, a desulfurizing agent supply system, a material recycling system, a desulfurization ash discharge system, a process water system, an ash storehouse system, a fluidized air system, an electrical instrument control system and the like.
CN105498503A discloses a novel dual-alkali flue gas desulfurization method and a flue gas desulfurization system, wherein the method adopts sodium hydroxide or sodium carbonate as an absorbent to remove SO in flue gas 2 Absorbing to generate absorption liquid containing sodium sulfite and sodium bisulfite, enabling the absorption liquid to enter a regeneration tank, regenerating the absorption liquid by using magnesium oxide or magnesium hydroxide in the regeneration tank, carrying out precipitation separation by using a solid-liquid separator, returning the regenerated sodium sulfite or sodium hydroxide to a desulfurization tower for flue gas absorption and recycling, enabling the precipitated magnesium sulfite obtained by solid-liquid separation to enter a desulfurization product treatment system, and directly discharging the magnesium sulfite or preparing magnesium sulfate. Although the method and the system refer to a double-alkali method, the flue gas is treated by adopting sodium hydroxide monobasic, and then the absorption liquid is regenerated by magnesium hydroxide, but the flue gas is not treated by using double alkali simultaneously, and the treatment effect of the flue gas with high sulfur dioxide content is still limited.
CN100469419C discloses a sectional sodium-calcium double-alkali desulfurization process, which comprises feeding dust-containing flue gas into an absorption tower, desulfurizing with calcium base, washing the flue gas with calcium base desulfurization circulating liquid prepared from lime or limestone, and removing most of smoke dust and SO in the flue gas 2 And a portion of oxygen; after calcium-based desulfurization, the flue gas is subjected to sodium-based desulfurization and regenerated by sodium alkali or calcium alkaliWashing the sodium alkali clear solution for further desulfurization, and removing trace sulfur dioxide in the flue gas; and demisting the purified flue gas obtained after calcium-based desulfurization and sodium-based desulfurization and then discharging the demisted flue gas. Although the process refers to a double-alkali method, the flue gas is treated by using a calcium-based desulfurizer and a sodium-based desulfurizer in sequence, the calcium-based desulfurizer and the sodium-based desulfurizer are independent from each other, and the treatment effect on the flue gas with high sulfur dioxide content is still limited.
Disclosure of Invention
In order to solve the technical problems, the invention provides a double-alkali semi-dry desulfurization method for flue gas, which aims at the problem that the desulfurization effect of the traditional semi-dry desulfurization method is limited when the flue gas with high sulfur content is faced, and the method is characterized in that alkali is added in a spray water process, the absorption desulfurization is cooperated with cooling, and the synergistic effect with a desulfurizing agent is realized, so that the desulfurization effect of a desulfurization tower is maximized, the utilization efficiency of a device is improved, the complexity of the process is reduced, and the standard emission of sulfur dioxide is realized.
In order to achieve the technical effect, the invention adopts the following technical scheme:
the invention provides a double-alkali semi-dry desulfurization method for flue gas, which is characterized by comprising the following steps:
preheating the flue gas and then feeding the preheated flue gas into a desulfurizing tower, and mixing the flue gas with a desulfurizing agent at an inlet section of the desulfurizing tower to obtain mixed flue gas;
after the mixed flue gas is accelerated by a Venturi section at the bottom of the desulfurization tower, cooling treatment is carried out at an outlet of the Venturi section by adopting alkali-containing spray water;
the mixed flue gas after the temperature reduction treatment enters a circulating fluidized bed for desulfurization reaction to obtain desulfurized flue gas;
and the desulfurized flue gas enters the next treatment working section after being subjected to dust removal treatment.
In the invention, aiming at the problem of poor desulfurization effect of the traditional semi-dry desulfurization method on high-sulfur-content flue gas, alkali is added into spray water to absorb desulfurization and reduce temperature in a synergistic manner, and through the synergistic effect with a desulfurizing agent, the desulfurization efficiency is improved, the reaction depth of desulfurization reaction is increased, and the desulfurization rate is improved.
In a preferred embodiment of the present invention, the temperature of the preheated flue gas is not lower than 140 ℃, such as 145 ℃, 150 ℃, 155 ℃, 160 ℃, 165 ℃, 170 ℃, 175 ℃ or 180 ℃, but is not limited to the values listed, and other values not listed in the range of the values are also applicable.
As a preferable technical scheme of the invention, the smoke amount of the smoke is 220000-240000 Nm 3 H, e.g. 225000Nm 3 /h、230000Nm 3 H or 235000Nm 3 And/h, etc., but are not limited to the recited values, and other values not recited within the numerical range are equally applicable.
As the preferable technical scheme of the invention, the initial sulfur content of the flue gas is 3000-3500 mg/Nm 3 E.g. 3050mg/Nm 3 、3100mg/Nm 3 、3150mg/Nm 3 、3200mg/Nm 3 、3250mg/Nm 3 、3300mg/Nm 3 、3350mg/Nm 3 、3400mg/Nm 3 Or 3450mg/Nm 3 And the like, but are not limited to the recited values, and other values not recited within the numerical range are also applicable.
In a preferred embodiment of the present invention, the ratio of calcium to sulfur in the mixed flue gas is 2 to 20, such as 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, or 19, but not limited to the above-mentioned values, and other values not listed in the above-mentioned range are also applicable.
Preferably, the desulfurizer is added in a spray mode.
Preferably, the desulfurizing agent is injected at a rate of not less than 18m/s, such as 18.5m/s, 19m/s, 19.5m/s, 20m/s, 20.5m/s, 21m/s, 21.5m/s, or 22m/s, but not limited to the recited values, and other values not recited within the range are equally applicable.
In the invention, the desulfurizer is continuously sprayed at the inlet of the desulfurizing tower by using the jet pump, the spraying rate of the desulfurizer can be adjusted according to the concentration of sulfur dioxide in flue gas, and the spraying rate of the desulfurizer is not lower than 18m/s, so that the stability of the desulfurizing efficiency can be maintained.
In a preferred embodiment of the present invention, the flow velocity of the mixed flue gas after being accelerated by the venturi section at the bottom of the desulfurization tower is 4 to 6m/s, such as 4.2m/s, 4.5m/s, 4.8m/s, 5m/s, 5.2m/s, 5.5m/s, or 5.8m/s, but the flow velocity is not limited to the above-mentioned values, and other values not listed in the above-mentioned range of values are also applicable.
In a preferred embodiment of the present invention, the temperature reduction treatment reduces the temperature of the mixed flue gas to 75 to 85 ℃, such as 76 ℃, 77 ℃, 78 ℃, 79 ℃, 80 ℃, 81 ℃, 82 ℃, 83 ℃ or 84 ℃, but not limited to the above-mentioned values, and other values not shown in the above-mentioned value range are also applicable.
Preferably, the alkali concentration in the spray water is 1 to 10 wt%, such as 2 wt%, 3 wt%, 4 wt%, 5 wt%, 6 wt%, 7 wt%, 8 wt%, or 9 wt%, but not limited to the recited values, and other values not recited in the range of values are also applicable.
Preferably, the base comprises sodium hydroxide and/or potassium hydroxide.
In the invention, the spray water device used for cooling treatment is connected with the alkali liquor adding device, namely, the alkali liquor and the spray water are mixed and then enter the desulfurizing tower, and spray liquid is formed by a spray component in the spray device to be mixed with the flue gas. Meanwhile, the spray water device and the alkali liquor adding device are both provided with a flow detection assembly and an automatic regulating valve, and spray water and alkali liquor are mixed and then pass through a concentration reduction detection assembly. Through the detection to spraying liquid concentration reduction to can realize the fluctuation to the temperature and the flow of flue gas through flow detection subassembly and automatically regulated valve's regulation, adjust the addition of alkali lye, reach best desulfurization effect.
In a preferred embodiment of the present invention, the pressure drop of the desulfurizing tower is 700 to 1000Pa, such as 750Pa, 800Pa, 850Pa, 900Pa or 950Pa, but the pressure drop is not limited to the above-mentioned values, and other values not shown in the above-mentioned range are also applicable.
In a preferred embodiment of the present invention, the bed pressure drop of the desulfurization tower is 1500-1800 Pa, such as 1550Pa, 1600Pa, 1650Pa, 1700Pa or 1750Pa, but not limited to the above-mentioned values, and other values not listed in the above-mentioned value range are also applicable.
As a preferred technical solution of the present invention, the method comprises:
preheating the flue gas, enabling the preheated flue gas to be not lower than 140 ℃, enabling the preheated flue gas to enter a desulfurizing tower, and mixing the flue gas and a desulfurizing agent at an inlet section of the desulfurizing tower to obtain mixed flue gas, wherein the calcium-sulfur ratio of the mixed flue gas is 2-20;
the smoke amount of the smoke is 220000-240000 Nm 3 The initial sulfur content is 3000-3500 mg/Nm 3 ；
After the mixed flue gas is accelerated by a Venturi section at the bottom of the desulfurization tower, the flow speed is 4-6 m/s, and alkali-containing spray water is adopted at an outlet of the Venturi section for cooling treatment, so that the temperature of the mixed flue gas is reduced to 75-85 ℃, the spraying amount of the spray water is 10-100L/h, and the alkali concentration is 1-10 wt%;
the mixed flue gas after the temperature reduction treatment enters a circulating fluidized bed for desulfurization reaction to obtain desulfurized flue gas;
the pressure drop of the empty tower of the desulfurizing tower is 700-1000 Pa, and the pressure drop of the bed layer is 1500-1800 Pa;
and the desulfurized flue gas enters the next treatment working section after being subjected to dust removal treatment.
Compared with the prior art, the invention has at least the following beneficial effects:
the invention provides a double-alkali semi-dry desulfurization method for flue gas, which aims at the problem that the desulfurization effect of the traditional semi-dry desulfurization method is limited when the flue gas with high sulfur content is faced, and the method is characterized in that alkali is added in a spray water process, the absorption desulfurization is cooperated with cooling, and the synergistic effect with a desulfurizing agent is realized, so that the desulfurization effect of a desulfurization tower is maximized, the utilization efficiency of a device is improved, the complexity of the process is reduced, the standard emission of sulfur dioxide is realized, and the desulfurization rate of the flue gas reaches more than 90%.
Detailed Description
For the purpose of facilitating an understanding of the present invention, the present invention will now be described by way of examples. It should be understood by those skilled in the art that the examples are only for the understanding of the present invention and should not be construed as the specific limitations of the present invention.
Example 1
The embodiment provides a double-alkali semi-dry desulfurization method for flue gas, which comprises the following steps:
preheating the flue gas, then feeding the preheated flue gas into a desulfurizing tower, mixing the flue gas and a desulfurizing agent at an inlet section of the desulfurizing tower to obtain mixed flue gas, wherein the calcium-sulfur ratio of the mixed flue gas is 2, the desulfurizing agent is added in a spray-in type mode, and the spray-in rate is 18 m/s;
the smoke amount of the smoke is 220000m 3 H, initial sulfur content 3000mg/Nm 3 ；
After the mixed flue gas is accelerated by a Venturi section at the bottom of the desulfurization tower, the flow velocity is 4m/s, and alkali-containing spray water is adopted at an outlet of the Venturi section for cooling treatment, so that the temperature of the mixed flue gas is reduced to 85 ℃, and the alkali concentration of the spray water is 10 wt%;
the mixed flue gas after the temperature reduction treatment enters a circulating fluidized bed for desulfurization reaction to obtain desulfurized flue gas;
the pressure drop of the empty tower of the desulfurizing tower is 700Pa, and the pressure drop of the bed layer is 1500 Pa;
and the desulfurized flue gas enters the next treatment working section after being subjected to dust removal treatment.
Example 2
The embodiment provides a double-alkali semi-dry desulfurization method for flue gas, which comprises the following steps:
preheating the flue gas, then feeding the preheated flue gas into a desulfurizing tower, mixing the flue gas and a desulfurizing agent at an inlet section of the desulfurizing tower to obtain mixed flue gas, wherein the calcium-sulfur ratio of the mixed flue gas is 20, the desulfurizing agent is added in an injection mode, and the injection rate is 22 m/s;
the smoke amount of the smoke is 240000m 3 H, initial sulfur content 3500mg/Nm 3 ；
After the mixed flue gas is accelerated by a Venturi section at the bottom of the desulfurization tower, the flow speed is 4-6 m/s, and alkali-containing spray water is adopted at an outlet of the Venturi section for cooling treatment, so that the temperature of the mixed flue gas is reduced to 75 ℃ by the cooling treatment, and the alkali concentration of the spray water is 1 wt%;
the mixed flue gas after the temperature reduction treatment enters a circulating fluidized bed for desulfurization reaction to obtain desulfurized flue gas;
the pressure drop of the empty tower of the desulfurizing tower is 1000Pa, and the pressure drop of the bed layer is 1800 Pa;
and the desulfurized flue gas enters the next treatment working section after being subjected to dust removal treatment.
Example 3
The embodiment provides a double-alkali semi-dry desulfurization method for flue gas, which comprises the following steps:
preheating the flue gas, then heating the flue gas to 155 ℃, enabling the preheated flue gas to enter a desulfurizing tower, and mixing the flue gas and a desulfurizing agent at an inlet section of the desulfurizing tower to obtain mixed flue gas, wherein the calcium-sulfur ratio of the mixed flue gas is 8, the desulfurizing agent is added in a spraying-in type mode, and the spraying rate is 20 m/s;
the smoke volume of the smoke is 230000m 3 Initial sulfur content 3200mg/Nm 3 ；
After the mixed flue gas is accelerated by a Venturi section at the bottom of the desulfurization tower, the flow velocity is 4.5m/s, and alkali-containing spray water is adopted at an outlet of the Venturi section for cooling treatment, so that the temperature of the mixed flue gas is reduced to 78 ℃ by the cooling treatment, and the alkali concentration of the spray water is 8 wt%;
the mixed flue gas after the temperature reduction treatment enters a circulating fluidized bed for desulfurization reaction to obtain desulfurized flue gas;
the pressure drop of the empty tower of the desulfurizing tower is 800Pa, and the pressure drop of the bed layer is 1600 Pa;
and the desulfurized flue gas enters the next treatment working section after being subjected to dust removal treatment.
Example 4
The embodiment provides a double-alkali semi-dry desulfurization method for flue gas, which comprises the following steps:
preheating the flue gas, then feeding the preheated flue gas into a desulfurizing tower, mixing the flue gas and a desulfurizing agent at an inlet section of the desulfurizing tower to obtain mixed flue gas, wherein the calcium-sulfur ratio of the mixed flue gas is 12, the desulfurizing agent is added in a spray-in type, and the spray-in rate is 20 m/s;
the smoke volume of the smoke is 230000m 3 Initial sulfur content 3200mg/Nm 3 ；
After the mixed flue gas is accelerated by a Venturi section at the bottom of the desulfurization tower, the flow rate is 5.5m/s, and the outlet of the Venturi section is cooled by adopting alkali-containing spray water, so that the temperature of the mixed flue gas is reduced to 75 ℃ by the cooling treatment, and the concentration of the spray water and alkali is 2.5 wt%;
the mixed flue gas after the temperature reduction treatment enters a circulating fluidized bed for desulfurization reaction to obtain desulfurized flue gas;
the pressure drop of the empty tower of the desulfurizing tower is 900Pa, and the pressure drop of the bed layer is 1700 Pa;
and the desulfurized flue gas enters the next treatment working section after being subjected to dust removal treatment.
Example 5
The embodiment provides a double-alkali semi-dry desulfurization method for flue gas, which comprises the following steps:
preheating the flue gas, then feeding the preheated flue gas into a desulfurizing tower, mixing the flue gas and a desulfurizing agent at an inlet section of the desulfurizing tower to obtain mixed flue gas, wherein the calcium-sulfur ratio of the mixed flue gas is 15, the desulfurizing agent is added in a spray-in type, and the spray-in rate is 20 m/s;
the smoke volume of the smoke is 230000m 3 Initial sulfur content 3200mg/Nm 3 ；
After the mixed flue gas is accelerated by a Venturi section at the bottom of the desulfurization tower, the flow velocity is 5m/s, and alkali-containing spray water is adopted at an outlet of the Venturi section for cooling treatment, so that the temperature of the mixed flue gas is reduced to 75 ℃ by the cooling treatment, and the alkali concentration of the spray water is 5 wt%;
the mixed flue gas after the temperature reduction treatment enters a circulating fluidized bed for desulfurization reaction to obtain desulfurized flue gas;
the pressure drop of the empty tower of the desulfurizing tower is 850Pa, and the pressure drop of the bed layer is 1650 Pa;
and the desulfurized flue gas enters the next treatment working section after being subjected to dust removal treatment.
Comparative example 1
The comparative example was carried out under the same conditions as in example 5 except that no alkali was added to the spray solution.
Comparative example 2
The desulfurizing agent in the comparative example is a mixture of lime powder and sodium hydroxide, the addition amount of alkali is the same as the total mass of alkali in the spray liquid, and other conditions are the same as those in example 5.
The desulfurizing agent used in examples 1 to 5 and comparative examples 1 to 2 was 80 to 90% of slaked lime powder (Ca (OH) 2 ) The particle size is 200-300 meshes, the alkali is sodium hydroxide, and the dust content of the initial flue gas is 6000mg/Nm 3 The dust content of the smoke entering the next working section is 10mg/Nm 3 The following.
The sulfur dioxide content of the flue gas treated in examples 1-5 and comparative examples 1-2 was measured and the results are shown in table 1.
TABLE 1
The test results in Table 1 show that when the sulfur dioxide content of the flue gas of the lithium salt factory is 3000-3500 mg/Nm 3 In the process, the desulfurization rate of the flue gas treated by the embodiments 1 to 5 of the invention can reach more than 90 percent. Comparative example 1 no alkali was added to the spray water and the elemental bulk desulfurization rate was reduced compared to example 5. In comparative example 2, sodium hydroxide was not added to the spray water, but sodium hydroxide and lime powder were simultaneously added as a desulfurizing agent, and the desulfurizing effect was reduced as compared with example 5.
The applicant states that the present invention is illustrated by the above examples to show the detailed process equipment and process flow of the present invention, but the present invention is not limited to the above detailed process equipment and process flow, i.e. it does not mean that the present invention must rely on the above detailed process equipment and process flow to be implemented. It should be understood by those skilled in the art that any modification of the present invention, equivalent substitutions of the raw materials of the product of the present invention, addition of auxiliary components, selection of specific modes, etc., are within the scope and disclosure of the present invention.
Claims (10)
1. A double-alkali semi-dry desulfurization method for flue gas, which is characterized by comprising the following steps:
preheating the flue gas and then feeding the preheated flue gas into a desulfurizing tower, and mixing the flue gas with a desulfurizing agent at an inlet section of the desulfurizing tower to obtain mixed flue gas;
after the mixed flue gas is accelerated by a Venturi section at the bottom of the desulfurization tower, cooling treatment is carried out at an outlet of the Venturi section by adopting alkali-containing spray water;
the mixed flue gas after the temperature reduction treatment enters a circulating fluidized bed for desulfurization reaction to obtain desulfurized flue gas;
and the desulfurized flue gas enters the next treatment working section after being subjected to dust removal treatment.
2. The method according to claim 1, wherein the temperature of the preheated flue gas is not less than 140 ℃.
3. The method according to claim 1 or 2, wherein the smoke amount of the smoke is 220000-240000 Nm 3 /h。
4. A method according to any one of claims 1 to 3, wherein the initial sulphur content of the flue gas is from 3000 to 3500mg/Nm 3 。
5. The method according to any one of claims 1 to 4, wherein the calcium-sulfur ratio in the mixed flue gas is 2 to 20;
preferably, the desulfurizer is added in a spray-in mode;
preferably, the injection rate of the desulfurizing agent is not lower than 18 m/s.
6. The method according to any one of claims 1 to 5, wherein the flow velocity of the mixed flue gas after being accelerated by the Venturi section at the bottom of the desulfurization tower is 4-6 m/s.
7. The method according to any one of claims 1 to 6, wherein the temperature reduction treatment reduces the temperature of the mixed flue gas to 75-85 ℃;
preferably, the concentration of alkali in the spray water is 1-10 wt%;
preferably, the base comprises sodium hydroxide and/or potassium hydroxide.
8. The method according to any one of claims 1 to 7, wherein the superficial pressure drop of the desulfurization tower is 700 to 1000 Pa.
9. The method according to any one of claims 1 to 8, wherein the pressure drop of the bed layer of the desulfurization tower is 1500-1800 Pa.
10. The method according to any one of claims 1-9, characterized in that the method comprises:
preheating the flue gas, enabling the preheated flue gas to be not lower than 140 ℃, enabling the preheated flue gas to enter a desulfurizing tower, and mixing the flue gas and a desulfurizing agent at an inlet section of the desulfurizing tower to obtain mixed flue gas, wherein the calcium-sulfur ratio of the mixed flue gas is 2-20;
the smoke amount of the smoke is 220000-240000 Nm 3 The initial sulfur content is 3000-3500 mg/Nm 3 ；
After the mixed flue gas is accelerated by a Venturi section at the bottom of the desulfurization tower, the flow speed is 4-6 m/s, and alkali-containing spray water is adopted at an outlet of the Venturi section for cooling treatment, so that the temperature of the mixed flue gas is reduced to 75-85 ℃, the spraying amount of the spray water is 10-100L/h, and the alkali concentration is 1-10 wt%;
the mixed flue gas after the temperature reduction treatment enters a circulating fluidized bed for desulfurization reaction to obtain desulfurized flue gas;
the pressure drop of the empty tower of the desulfurizing tower is 700-1000 Pa, and the pressure drop of the bed layer is 1500-1800 Pa;
and the desulfurized flue gas enters the next treatment working section after being subjected to dust removal treatment.
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| Title |
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| 朱廷钰等: "《烧结烟气排放控制技术及工程应用》", 北京：冶金工业出版社, pages: 126 - 129 * |
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