CN111437701A - System and method for balancing and treating materials in slurry of limestone wet desulphurization absorption tower - Google Patents
System and method for balancing and treating materials in slurry of limestone wet desulphurization absorption tower Download PDFInfo
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- 239000002002 slurry Substances 0.000 title claims abstract description 46
- 239000006028 limestone Substances 0.000 title claims abstract description 39
- 235000019738 Limestone Nutrition 0.000 title claims abstract description 37
- 239000000463 material Substances 0.000 title claims abstract description 36
- 238000010521 absorption reaction Methods 0.000 title claims abstract description 26
- 238000000034 method Methods 0.000 title claims description 28
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 84
- 238000006477 desulfuration reaction Methods 0.000 claims abstract description 79
- 230000023556 desulfurization Effects 0.000 claims abstract description 79
- 239000003546 flue gas Substances 0.000 claims abstract description 47
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 claims abstract description 45
- 239000002351 wastewater Substances 0.000 claims abstract description 41
- 238000000909 electrodialysis Methods 0.000 claims abstract description 39
- 229910052602 gypsum Inorganic materials 0.000 claims abstract description 28
- 239000010440 gypsum Substances 0.000 claims abstract description 25
- 150000002500 ions Chemical class 0.000 claims abstract description 19
- 229910001424 calcium ion Inorganic materials 0.000 claims abstract description 15
- BHPQYMZQTOCNFJ-UHFFFAOYSA-N Calcium cation Chemical compound [Ca+2] BHPQYMZQTOCNFJ-UHFFFAOYSA-N 0.000 claims abstract description 14
- 230000003647 oxidation Effects 0.000 claims abstract description 8
- 238000007254 oxidation reaction Methods 0.000 claims abstract description 8
- 239000012528 membrane Substances 0.000 claims description 15
- JLVVSXFLKOJNIY-UHFFFAOYSA-N Magnesium ion Chemical compound [Mg+2] JLVVSXFLKOJNIY-UHFFFAOYSA-N 0.000 claims description 14
- 229910001425 magnesium ion Inorganic materials 0.000 claims description 14
- 239000003011 anion exchange membrane Substances 0.000 claims description 8
- VTYYLEPIZMXCLO-UHFFFAOYSA-L calcium carbonate Substances [Ca+2].[O-]C([O-])=O VTYYLEPIZMXCLO-UHFFFAOYSA-L 0.000 claims description 8
- 238000005341 cation exchange Methods 0.000 claims description 8
- BQPIGGFYSBELGY-UHFFFAOYSA-N mercury(2+) Chemical compound [Hg+2] BQPIGGFYSBELGY-UHFFFAOYSA-N 0.000 claims description 8
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N silicon dioxide Inorganic materials O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims description 8
- XLYOFNOQVPJJNP-ZSJDYOACSA-N heavy water Substances [2H]O[2H] XLYOFNOQVPJJNP-ZSJDYOACSA-N 0.000 claims description 7
- 238000002425 crystallisation Methods 0.000 claims description 6
- 238000004064 recycling Methods 0.000 claims description 6
- 229910000019 calcium carbonate Inorganic materials 0.000 claims description 5
- 230000008025 crystallization Effects 0.000 claims description 5
- 238000007599 discharging Methods 0.000 claims description 5
- 229910001385 heavy metal Inorganic materials 0.000 claims description 5
- 239000000377 silicon dioxide Substances 0.000 claims description 4
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims description 3
- 239000007788 liquid Substances 0.000 claims description 3
- 229910052760 oxygen Inorganic materials 0.000 claims description 3
- 239000001301 oxygen Substances 0.000 claims description 3
- 239000000779 smoke Substances 0.000 claims description 3
- 239000004071 soot Substances 0.000 claims description 3
- 230000001502 supplementing effect Effects 0.000 claims description 3
- 239000003570 air Substances 0.000 claims description 2
- -1 fluoride ions Chemical class 0.000 abstract description 12
- VEXZGXHMUGYJMC-UHFFFAOYSA-M Chloride anion Chemical compound [Cl-] VEXZGXHMUGYJMC-UHFFFAOYSA-M 0.000 abstract description 10
- 230000009286 beneficial effect Effects 0.000 abstract description 3
- RAHZWNYVWXNFOC-UHFFFAOYSA-N Sulphur dioxide Chemical compound O=S=O RAHZWNYVWXNFOC-UHFFFAOYSA-N 0.000 description 15
- 239000012535 impurity Substances 0.000 description 11
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 description 7
- 239000011575 calcium Substances 0.000 description 7
- NHNBFGGVMKEFGY-UHFFFAOYSA-N Nitrate Chemical compound [O-][N+]([O-])=O NHNBFGGVMKEFGY-UHFFFAOYSA-N 0.000 description 6
- 229910052791 calcium Inorganic materials 0.000 description 6
- OSGAYBCDTDRGGQ-UHFFFAOYSA-L calcium sulfate Chemical compound [Ca+2].[O-]S([O-])(=O)=O OSGAYBCDTDRGGQ-UHFFFAOYSA-L 0.000 description 6
- 238000005516 engineering process Methods 0.000 description 6
- 229910002651 NO3 Inorganic materials 0.000 description 5
- QAOWNCQODCNURD-UHFFFAOYSA-L Sulfate Chemical compound [O-]S([O-])(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-L 0.000 description 5
- 229910052782 aluminium Inorganic materials 0.000 description 5
- 239000011777 magnesium Substances 0.000 description 5
- KRHYYFGTRYWZRS-UHFFFAOYSA-M Fluoride anion Chemical compound [F-] KRHYYFGTRYWZRS-UHFFFAOYSA-M 0.000 description 4
- 229910052749 magnesium Inorganic materials 0.000 description 4
- FYYHWMGAXLPEAU-UHFFFAOYSA-N Magnesium Chemical compound [Mg] FYYHWMGAXLPEAU-UHFFFAOYSA-N 0.000 description 3
- 229910052925 anhydrite Inorganic materials 0.000 description 3
- 239000006227 byproduct Substances 0.000 description 3
- 238000006243 chemical reaction Methods 0.000 description 3
- 230000007613 environmental effect Effects 0.000 description 3
- XEEYBQQBJWHFJM-UHFFFAOYSA-N iron Substances [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 3
- 229910052742 iron Inorganic materials 0.000 description 3
- 229910001415 sodium ion Inorganic materials 0.000 description 3
- 239000000126 substance Substances 0.000 description 3
- FKNQFGJONOIPTF-UHFFFAOYSA-N Sodium cation Chemical compound [Na+] FKNQFGJONOIPTF-UHFFFAOYSA-N 0.000 description 2
- LSNNMFCWUKXFEE-UHFFFAOYSA-N Sulfurous acid Chemical compound OS(O)=O LSNNMFCWUKXFEE-UHFFFAOYSA-N 0.000 description 2
- 230000008901 benefit Effects 0.000 description 2
- 239000003054 catalyst Substances 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000000630 rising effect Effects 0.000 description 2
- 150000003839 salts Chemical class 0.000 description 2
- 239000002699 waste material Substances 0.000 description 2
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 description 1
- 239000006096 absorbing agent Substances 0.000 description 1
- 238000003916 acid precipitation Methods 0.000 description 1
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 1
- REDXJYDRNCIFBQ-UHFFFAOYSA-N aluminium(3+) Chemical compound [Al+3] REDXJYDRNCIFBQ-UHFFFAOYSA-N 0.000 description 1
- 239000003245 coal Substances 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 230000018044 dehydration Effects 0.000 description 1
- 238000006297 dehydration reaction Methods 0.000 description 1
- 230000003009 desulfurizing effect Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 239000003814 drug Substances 0.000 description 1
- 239000003344 environmental pollutant Substances 0.000 description 1
- 238000001704 evaporation Methods 0.000 description 1
- 239000011344 liquid material Substances 0.000 description 1
- 229910052753 mercury Inorganic materials 0.000 description 1
- 230000003472 neutralizing effect Effects 0.000 description 1
- 238000005457 optimization Methods 0.000 description 1
- 230000001590 oxidative effect Effects 0.000 description 1
- TWNQGVIAIRXVLR-UHFFFAOYSA-N oxo(oxoalumanyloxy)alumane Chemical compound O=[Al]O[Al]=O TWNQGVIAIRXVLR-UHFFFAOYSA-N 0.000 description 1
- 231100000572 poisoning Toxicity 0.000 description 1
- 230000000607 poisoning effect Effects 0.000 description 1
- 231100000719 pollutant Toxicity 0.000 description 1
- 238000001556 precipitation Methods 0.000 description 1
- 239000002910 solid waste Substances 0.000 description 1
- 239000011593 sulfur Substances 0.000 description 1
- 229910052717 sulfur Inorganic materials 0.000 description 1
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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
- B01D53/46—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
- B01D53/504—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 device
-
- 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
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/46—Treatment of water, waste water, or sewage by electrochemical methods
- C02F1/469—Treatment of water, waste water, or sewage by electrochemical methods by electrochemical separation, e.g. by electro-osmosis, electrodialysis, electrophoresis
- C02F1/4693—Treatment of water, waste water, or sewage by electrochemical methods by electrochemical separation, e.g. by electro-osmosis, electrodialysis, electrophoresis electrodialysis
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- 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
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D2251/00—Reactants
- B01D2251/60—Inorganic bases or salts
- B01D2251/606—Carbonates
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- 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
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2103/00—Nature of the water, waste water, sewage or sludge to be treated
- C02F2103/18—Nature of the water, waste water, sewage or sludge to be treated from the purification of gaseous effluents
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Abstract
The invention relates to a system for balancing and treating materials in slurry of a limestone wet desulphurization absorption tower, which comprises a flue gas desulphurization system, a limestone putting module, a flue gas pipeline, an oxidation fan, a gypsum output module and a directional driving electrodialysis device, wherein the limestone putting module is arranged on the flue gas pipeline; the inlet end of the flue gas desulfurization system is respectively connected with a limestone feeding module, a flue gas pipeline, an oxidation fan and a water replenishing system; the output end of the flue gas desulfurization system is connected with a gypsum output module; the waste water outlet end of the flue gas desulfurization system is connected with the inlet end of the directional driving electrodialysis device, the A-type water of the directional driving electrodialysis device is connected to the inlet end of the flue gas desulfurization system, and the B-type water of the directional driving electrodialysis device is discharged. The invention has the beneficial effects that: according to the invention, by utilizing the property of selectively and directionally driving ions by special electrodialysis, harmful ions such as chloride ions and fluoride ions in the desulfurization wastewater are discharged, and partial sulfate radicals, calcium ions and water are recycled, so that the material balance of the whole desulfurization slurry absorption system is effectively maintained.
Description
Technical Field
The invention belongs to the technical field of environment-friendly water treatment, and particularly relates to a system and a method for balancing and treating materials in slurry of a limestone wet desulphurization absorption tower.
Background
A large amount of sulfur dioxide is generated in flue gas in the operation process of a coal-fired power plant, so that great pollution is caused, and acid rain is formed. The mainstream technology for treating sulfur dioxide pollution in China is wet limestone desulfurization, namely, limestone slurry is used for neutralizing sulfur dioxide. In the operation process of the wet limestone desulfurization process, the material balance in the slurry of the absorption tower needs to be kept, the enrichment of harmful pollutants in the desulfurization slurry is avoided, and the continuous desulfurization reaction in the system is ensured.
The material balance method of the desulfurization system has been applied for patents (Chinese patent application numbers: 201810990379.3, 201910396837.5, 201510071613.9, 201720717001.7, 201710599504.3, etc.). These patents are primarily concerned with the water balance of the desulfurization system, but are not concerned with the balance of other ions (including calcium, magnesium, sulfate, chloride, etc.) within the desulfurization slurry. The material balance of the existing desulfurization slurry is realized by discharging desulfurization wastewater, and the wastewater has high salt content and high calcium and magnesium hardness, is difficult to directly recycle and cannot be directly discharged outside, and needs to be subjected to advanced treatment. When a desulfurization wastewater advanced treatment system (a bypass flue gas evaporation method or an evaporative crystallization method) is used for treatment, on one hand, more sulfate radicals and calcium and magnesium ions in the desulfurization wastewater are not recycled, and on the other hand, the water resource is seriously wasted due to the excessive amount of the desulfurization wastewater. Directly results in the high treatment cost of the desulfurization waste water (the comprehensive cost reaches 100-.
Therefore, the material balance mode of the desulfurization slurry has the requirement of further optimization.
Disclosure of Invention
The invention aims to overcome the defects in the prior art, and provides a system and a method for balancing and treating materials in slurry of a limestone wet desulphurization absorption tower, which aim to efficiently realize the concentration balance of impurity ions in a desulphurization slurry tower with the most limited cost.
The system for balancing and treating the materials in the slurry of the limestone wet desulphurization absorption tower comprises a flue gas desulphurization system, a limestone putting module, a flue gas pipeline, an oxidation fan, a water supplementing system, a gypsum output module and a directional driving electrodialysis device; the inlet end of the flue gas desulfurization system is respectively connected with a limestone feeding module, a flue gas pipeline, an oxidation fan and a water replenishing system; the output end of the flue gas desulfurization system is connected with a gypsum output module; the waste water outlet end of the flue gas desulfurization system is connected with the inlet end of the directional driving electrodialysis device, the A-type water of the directional driving electrodialysis device is connected with the inlet end of the flue gas desulfurization system, and the B-type water of the directional driving electrodialysis device is discharged; the directional driving electrodialysis device is modularized, namely a plurality of directional driving electrodialysis modules are arranged in series or in parallel, each directional driving electrodialysis module is provided with a positive plate and a negative plate and is provided with a direct current power supply, cation exchange membranes and anion exchange membranes are arranged between the positive plate and the negative plate at intervals, and one cation exchange membrane and one anion exchange membrane form a membrane pair.
Preferably, the method comprises the following steps: the directional driving electrodialysis device is connected with a polar water circulation system.
The treatment method of the material balance treatment system in the slurry of the limestone wet desulphurization absorption tower comprises the following steps:
1) the flue gas, limestone, air and make-up water enter a flue gas desulfurization system, react in the flue gas desulfurization system to generate desulfurized gypsum, and simultaneously discharge desulfurized wastewater;
2) enabling the desulfurization wastewater to enter a directional driving electrodialysis device, and selectively separating ions in the desulfurization wastewater into A-type water and B-type water; recycling the A-class water to a flue gas desulfurization system, and discharging the B-class water;
3) the input amount of the make-up water is reduced, the input amount of the limestone is increased, and the crystallization and the discharge of the desulfurized gypsum are accelerated, so that the new balance of the materials in the desulfurized slurry is realized.
Preferably, the method comprises the following steps: in the step 1), the smoke comprises S02、SO3HCl, HF, NOx, soot and heavy metal ions; limestone comprising CaCO3Silicon dioxide, oxides of Mg and oxides of Al; the air contains oxygen; the main component of the desulfurized gypsum is CaSO4·2H2O and CaSO3·1/2H2O; the desulfurization waste water includes Cl-、SO4 2-、F-、Mg2+、Ca2+、NO3 -、Hg2+、Fe3+、Al3+Suspended matter and water.
Preferably, the method comprises the following steps: in the step 2), the A-type water accounts for three-fourths of the total wastewater, and the A-type water contains SO4 2-Part of Ca2+Small amount of Mg2+And a small amount of Cl-(ii) a The B water accounts for one fourth of the total wastewater amount, and the B water contains SO4 2-High concentration of Cl-、F-、NO3 -、Mg2+、Ca2+、Hg2+、Fe3+And Al3+。
The invention has the beneficial effects that:
(1) according to the invention, by utilizing the property of selectively and directionally driving ions by special electrodialysis, harmful ions such as chloride ions and fluoride ions in the desulfurization wastewater are discharged, and partial sulfate radicals, calcium ions and water are recycled, so that the material balance of the whole desulfurization slurry absorption system is effectively maintained.
(2) In the process of balancing desulfurization and absorbing slurry materials, the directional driving electrodialysis device is arranged, so that the water quantity of the discharged wastewater is reduced, the water resource is saved, and the difficulty in subsequent deep treatment of the discharged wastewater is reduced.
(3) In the process of balancing desulfurization and absorbing slurry materials, the directional driving electrodialysis device is arranged, so that the total amount of discharged dissolved salt is reduced, and the total amount of solid waste after subsequent external waste discharge water deep treatment is also reduced.
(4) In the process of balancing desulfurization and absorption of slurry materials, the invention only consumes the electric energy generated by the coal-fired power plant without using a large amount of chemicals, and has the characteristics of environmental protection.
Drawings
FIG. 1 is a schematic diagram of a method for balancing materials in slurry in a limestone wet desulfurization absorption tower;
fig. 2 is a schematic view of a directionally driven electrodialysis module.
Detailed Description
The present invention will be further described with reference to the following examples. The following examples are set forth merely to aid in the understanding of the invention. It should be noted that, for those skilled in the art, it is possible to make various improvements and modifications to the present invention without departing from the principle of the present invention, and those improvements and modifications also fall within the scope of the claims of the present invention.
The limestone wet desulphurization absorption tower slurry in material balance treatment system, under the premise of keeping the concentration of harmful impurity ions in the slurry not continuously rising, recycles water, sulfate radicals and calcium ions in the desulphurization wastewater to the flue gas desulphurization system, not only can realize the recycling of resources, but also can reduce the difficulty of the subsequent advanced treatment of the desulphurization wastewater. The structure of the device comprises a flue gas desulfurization system, a limestone feeding module, a flue gas pipeline, an oxidation fan, a water supplementing system, a gypsum output module and a directional driving electrodialysis device. The inlet end of the flue gas desulfurization system is respectively connected with a limestone feeding module, a flue gas pipeline, an oxidation fan and a water replenishing system; the output end of the flue gas desulfurization system is connected with a gypsum output module; the waste water outlet end of the flue gas desulfurization system is connected with the inlet end of the directional driving electrodialysis device, the A-type water of the directional driving electrodialysis device is connected with the inlet end of the flue gas desulfurization system, and the B-type water of the directional driving electrodialysis device is discharged; the directional driving electrodialysis device is modularized, namely a plurality of directional driving electrodialysis modules are arranged in series or in parallel, each directional driving electrodialysis module is provided with a positive plate and a negative plate and is provided with a direct current power supply, cation exchange membranes and anion exchange membranes are arranged between the positive plate and the negative plate at intervals, and one cation exchange membrane and one anion exchange membrane form a membrane pair.
The directional driving electrodialysis device is connected with a polar water circulation system.
In the process of flue gas desulfurization, the flue gas desulfurization absorption tower mainly has the function of reducing SO in the flue gas2Using calcium carbonate and SO in limestone2And (4) reacting to produce the byproduct desulfurized gypsum.
The reaction equation is as follows:
SO2+H2O→H2SO3
CaCO3+H2SO3→CaSO3+CO2
CaSO3+1/2O2→CaSO4
CaSO3+1/2H2O→CaSO3·1/2H2O
CaSO4+2H2O→CaSO4·2H2O
the material entering the absorption tower system comprises: SO brought in by flue gas2、SO3HCl, HF, NOx, soot (containing impurities such as silica and aluminum oxide), heavy metal ions, and CaCO introduced from limestone3Small amount of silica, oxides of Mg and Al, etc., oxidizing windAir (containing oxygen) blown by the machine, make up water. The substances discharged from the absorption tower system mainly comprise: desulfurized gypsum (CaSO as main component)4·2H2O、CaSO3·1/2H2O), small amount of smoke entrained by the flue gas, S02、SO3HCl, HF, NOx, etc.
In order to keep the desulfurization reaction continuously, the input of sulfur dioxide and calcium carbonate in the absorption tower and the output of the desulfurized gypsum are always kept in balance. But chloride, fluoride, magnesium, aluminum and heavy metal ions will be enriched in the absorber slurry. Wherein chloride ion's enrichment can cause the corruption of desulfurization system equipment and influence gypsum crystallization and dehydration, and the rising of magnesium ion, aluminium ion, fluorine ion concentration can cause the thick liquid poisoning, makes the unable normal clear of sulfur dioxide absorption reaction, and heavy metal can influence the quality of desulfurization gypsum, therefore above impurity all must constantly be removed from the desulfurization thick liquid to guarantee the balance of desulfurization thick liquid material concentration.
In the normal operation of a 600MW unit burning coal with medium sulfur concentration (Sar0.6-0.8%), the discharge amount of desulfurization waste water in a desulfurization system per hour is about 3-5t, so that the concentration of chloride ions in desulfurization slurry can be kept within the range of 10000 plus 15000 mg/L.
A new method for balancing materials in slurry of a limestone wet desulphurization absorption tower utilizes a selective ion directional driving water treatment technology to selectively separate ions in desulphurization wastewater. And the material balance of the desulfurization slurry absorption tower is realized by discharging impurities such as chloride ions and recycling sulfate ions.
As shown in fig. 1:
the method comprises the following steps of (1) discharging materials in the original desulfurization wastewater: cl-、SO4 2-、F-、Mg2+、Ca2+、NO3 -、Hg2+、Fe3+、Al3+The suspended matter and water are separated by selective ion directional driving technology and are divided into two types of water A and water B.
The class A water accounts for three-fourth of the total waste water (can be adjusted according to the operation condition), and the SO of the class A water accounts for three-fourth of the total waste water4 2-The concentration of the calcium-containing calcium-based calcium sulfate is basically consistent with that of desulfurized wastewater, and in addition, the calcium-based calcium2+And a small amount of Mg2+、Cl-. Because the main component is CaSO4Other harmful impurities are less and can be recycled to the desulfurization slurry;
class B water accounts for one fourth of the total waste water (can be adjusted according to the operation condition), and SO thereof4 2-The concentration of the catalyst is basically consistent with that of the desulfurized wastewater, and in addition, the catalyst also contains extremely high concentration of Cl-、F-、NO3 -、Mg2+、Ca2+、Hg2+、Fe3+、Al3+. It is discharged from the desulfurization system because it contains a large amount of harmful impurities.
Due to the recycling of the A-type water, the balance of the water and other materials in the desulfurizing tower system is changed. The operation process of the desulfurization system needs to be changed, the addition amount of make-up water is reduced, the input amount of limestone is increased, and the crystallization and discharge of the desulfurized gypsum are accelerated, so that the new balance of materials in the desulfurized slurry is realized. The new balance reduces the loss of water resources and calcium sulfate while preventing harmful impurities from being enriched in the slurry, increases the yield of economic byproduct desulfurized gypsum, and has the advantage of environmental protection.
The directional driving technology in the slurry material balance method is realized by combining directional driving electrodialysis modules, and a plurality of modules can be arranged for series or parallel treatment according to the water quantity of the desulfurization wastewater and the final effluent water quality requirement. Each directional driving electrodialysis module is provided with a positive plate and a negative plate which are provided with a direct current power supply, and cation exchange membranes and anion exchange membranes are arranged between the positive plate and the negative plate at intervals. A cation exchange membrane and an anion exchange membrane form a membrane pair, and the membrane pair is arranged in a mode of positive electrode-positive membrane-negative membrane-positive membrane-negative membrane, and can be increased or decreased according to the size of the treated water quantity.
The desulfurization slurry material balance method adopting the directional driving technology only consumes electric energy in normal operation and does not add a large amount of chemicals, thereby being an environment-friendly balance method.
An embodiment of a method for balancing materials in slurry of a limestone wet desulphurization absorption tower is based on the following steps:
600MW unit of a coal-fired power plant adopts limestone wet desulphurization, and a flue gas inlet SO2The concentration is about 1300mg/Nm3The discharge capacity of the desulfurization wastewater is about 4t/h, and the content of each ion in the wastewater is as follows:
the conductivity is about 35mS/cm, the pH is 5.8, the chloride ion is 12350 mg/L, the sulfate ion is 4200 mg/L, the fluoride ion is 12 mg/L, the nitrate ion is 34 mg/L, the calcium ion is 8765 mg/L, the magnesium ion is 2100 mg/L, the sodium ion is 430 mg/L, the iron ion is 20 mg/L, the aluminum ion is 135 concentrated mg/L, and the mercury ion is 0.04 mg/L.
After directional driving electrodialysis treatment, 4t/h of wastewater is separated into A-type water and B-type water, and the water quantity and the water quality are as follows:
the water quantity of the A-type water is 3t/h, the water quality has the conductivity of about 8.8mS/cm, the pH value is 4.2, the chloride ions are 1482 mg/L, the sulfate ions are 4120 mg/L, the fluoride ions are 1.4 mg/L, the nitrate ions are 4.1 mg/L, the calcium ions are 964 mg/L, the magnesium ions are 273 mg/L, the sodium ions are 58 mg/L, the iron ions are 2.4 mg/L, the aluminum ions are 15 mg/L, and the mercury ions are 0.05 mg/L.
The water amount of the B-type water is 1t/h, the water quality is that the conductivity is about 115mS/cm, the pH is 9.0, the chloride ion is 44954 mg/L, the sulfate ion is 4250 mg/L, the fluoride ion is 43.7 mg/L, the nitrate ion is 123.8 mg/L, the calcium ion is 32167.6 mg/L, the magnesium ion is 7581 mg/L, the sodium ion is 1546 mg/L, the iron ion is 72.8 mg/L, the aluminum ion is 455 mg/L, and the mercury ion is 1.5 mg/L.
The A-type water is recycled to the slurry circulating tank of the desulfurization system, SO that SO in the desulfurization slurry is increased4 2-The concentration of the desulfurized gypsum is beneficial to the crystallization and precipitation of the byproduct desulfurized gypsum, thereby improving the yield of the desulfurized gypsum. Moreover, the water quantity of the A-type water accounts for about three quarters of the water quantity of the desulfurization wastewater, the recycling of the A-type water also reduces the using amount of make-up water, and the water resource is saved.
The discharge of the B-type water ensures that the concentration of impurity ions in the desulfurization slurry is balanced, and the harmful enrichment of the impurity ions in the desulfurization slurry is avoided.
After the class A water is recycled, the operation condition of the power plant desulfurization system is correspondingly adjusted, and a new desulfurization slurry material balance is established. Wherein, the total amount of the slurry in the system is kept unchanged, the adding amount of the make-up water is reduced by 3 tons/hour, the adding total amount of the limestone slurry is increased to 1.05 times of the original adding amount, and the separating amount of the desulfurized gypsum is increased to 1.2 times of the original adding amount.
The results show that the material balance of the slurry of the desulfurization system is realized by using the special electrodialysis technology, no additional medicament is needed, the waste of recyclable resources can be reduced while harmful impurities are discharged, and the method has good economic, environmental and social benefits.
Claims (5)
1. The utility model provides a material balance processing system in limestone wet flue gas desulfurization absorption tower thick liquid which characterized in that: the system comprises a flue gas desulfurization system, a limestone feeding module, a flue gas pipeline, an oxidation fan, a water supplementing system, a gypsum output module and a directional driving electrodialysis device; the inlet end of the flue gas desulfurization system is respectively connected with a limestone feeding module, a flue gas pipeline, an oxidation fan and a water replenishing system; the output end of the flue gas desulfurization system is connected with a gypsum output module; the waste water outlet end of the flue gas desulfurization system is connected with the inlet end of the directional driving electrodialysis device, the A-type water of the directional driving electrodialysis device is connected with the inlet end of the flue gas desulfurization system, and the B-type water of the directional driving electrodialysis device is discharged; the directional driving electrodialysis device is modularized, namely a plurality of directional driving electrodialysis modules are arranged in series or in parallel, each directional driving electrodialysis module is provided with a positive plate and a negative plate and is provided with a direct current power supply, cation exchange membranes and anion exchange membranes are arranged between the positive plate and the negative plate at intervals, and one cation exchange membrane and one anion exchange membrane form a membrane pair.
2. The system for processing the balance of materials in the slurry of the limestone wet desulphurization absorption tower of claim 1, wherein: the directional driving electrodialysis device is connected with a polar water circulation system.
3. A method for processing a system for the equilibrium processing of materials in a slurry in a limestone wet desulphurization absorption tower according to claim 1, comprising the following steps:
1) the flue gas, limestone, air and make-up water enter a flue gas desulfurization system, react in the flue gas desulfurization system to generate desulfurized gypsum, and simultaneously discharge desulfurized wastewater;
2) enabling the desulfurization wastewater to enter a directional driving electrodialysis device, and selectively separating ions in the desulfurization wastewater into A-type water and B-type water; recycling the A-class water to a flue gas desulfurization system, and discharging the B-class water;
3) the input amount of the make-up water is reduced, the input amount of the limestone is increased, and the crystallization and the discharge of the desulfurized gypsum are accelerated, so that the new balance of the materials in the desulfurized slurry is realized.
4. The method for processing the system for processing the material balance in the slurry of the limestone wet desulphurization absorption tower according to the claim 3, characterized in that: in the step 1), the smoke comprises S02、SO3HCl, HF, NOx, soot and heavy metal ions; limestone comprising CaCO3Silicon dioxide, oxides of Mg and oxides of Al; the air contains oxygen; the main component of the desulfurized gypsum is CaSO4·2H2O and CaSO3·1/2H2O; the desulfurization waste water includes Cl-、SO4 2-、F-、Mg2+、Ca2+、NO3 -、Hg2+、Fe3+、Al3+Suspended matter and water.
5. The method for processing the system for processing the material balance in the slurry of the limestone wet desulphurization absorption tower according to the claim 3, characterized in that: in the step 2), the A-type water accounts for three-fourths of the total wastewater, and the A-type water contains SO4 2-Part of Ca2+Small amount of Mg2+And a small amount of Cl-(ii) a The B water accounts for one fourth of the total wastewater amount, and the B water contains SO4 2-High concentration of Cl-、F-、NO3 -、Mg2+、Ca2+、Hg2+、Fe3+And Al3+。
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| CN114887469A (en) * | 2022-03-27 | 2022-08-12 | 山西太钢万邦炉料有限公司 | Stably adjusting SO in flue gas 2 Method of concentration |
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