CN108726541B - Method for preparing sodium bisulfate by resource utilization of coal chemical industry waste gas and waste water - Google Patents

Method for preparing sodium bisulfate by resource utilization of coal chemical industry waste gas and waste water Download PDF

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CN108726541B
CN108726541B CN201810523555.2A CN201810523555A CN108726541B CN 108726541 B CN108726541 B CN 108726541B CN 201810523555 A CN201810523555 A CN 201810523555A CN 108726541 B CN108726541 B CN 108726541B
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coal chemical
chemical industry
waste gas
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sodium bisulfate
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CN108726541A (en
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韩洪军
李琨
徐春艳
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Harbin Institute of Technology
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Harbin Institute of Technology
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    • CCHEMISTRY; METALLURGY
    • C01INORGANIC CHEMISTRY
    • C01DCOMPOUNDS OF ALKALI METALS, i.e. LITHIUM, SODIUM, POTASSIUM, RUBIDIUM, CAESIUM, OR FRANCIUM
    • C01D5/00Sulfates or sulfites of sodium, potassium or alkali metals in general
    • C01D5/02Preparation of sulfates from alkali metal salts and sulfuric acid or bisulfates; Preparation of bisulfates

Abstract

A method for preparing sodium bisulfate by resource utilization of coal chemical waste gas and waste water relates to the field of waste water, waste gas and resource utilization. The invention aims to solve the problem that the coal chemical waste gas and the strong brine can be effectively treated and recycled at the same time. The invention improves the resource rate of the water body and the gas in the coal chemical industry when treating the waste gas and the strong brine in the coal chemical industry. The raw materials for preparing the sodium bisulfate, namely sulfur dioxide in the coal chemical industry waste gas and sodium chloride in the concentrated brine are generated in the coal chemical industry production process, so that the economic feasibility is realized; the invention directly utilizes the sulfur dioxide in the waste gas to produce the sulfuric acid, saves the sulfur recovery process when the waste gas is treated in the coal chemical industry, and saves the energy consumption.

Description

Method for preparing sodium bisulfate by resource utilization of coal chemical industry waste gas and waste water
Technical Field
The invention relates to the field of wastewater, waste gas and resource utilization, in particular to a method for preparing sodium bisulfate by utilizing coal chemical industry waste gas and strong brine.
Background
China is a big coal resource country, and the reserve of coal resources accounts for more than 75% of the total amount of energy resources. In recent years, the coal chemical industry in China is developed at a high speed, and meanwhile, the environment protection and supervision of the coal chemical industry are strengthened by the nation. The novel national coal chemical industry takes high energy conversion rate as a direction, has the characteristic of less discharge of waste water, waste gas and waste liquid, and simultaneously enhances the recycling of byproducts and resources in the production process.
The concentrated brine generated in the coal chemical industry is generated in a reclaimed water system for recycling water resources in the coal chemical industry, and contains a large amount of refractory organic matters (COD is 500-5,000mg/L) and salts (up to 100,000mg/L, and Na is used as+、Cl-、SO4 2-、NO3 -Mainly), so the quality of the strong brine in the coal chemical industry is complex and difficult to treat, and is a main factor restricting the development of the coal chemical industry. The 'membrane concentration and evaporative crystallization' is a technology for treating strong brine in coal chemical industry applied to practical engineering, wherein the strong brine in coal chemical industry is concentrated to about one third by a reverse osmosis membrane and then enters an evaporative crystallization process, a mechanical falling film evaporation MVR evaporation process, a two-effect evaporation process or a multi-effect evaporation process is commonly used, and finally, crystallized salt is prepared by a TVR evaporative crystallizer, a drying crystallization crystallizer, a two-effect crystallizer and other crystallizers.
The main pollutants in the coal chemical industry waste gas are hydrogen sulfide and sulfur dioxide, and in addition, the main pollutants comprise oxides, smoke dust and carbon dioxide. Hydrocarbons, and other organic compounds. For different processes such as coal-to-coke, coal-to-oil, coal-to-gas and the like, waste gas has different components and contents. Sulfur dioxide in coal chemical industry waste gas is treated by ammonia absorption, alkali liquor absorption, lime milk gypsum method, limestone washing method, zinc oxide absorption, citrate method, etc. and is prepared into recoverable sulfur by Claus or Scott process.
Harbin industry university provides a method for preparing industrial salt by separating, evaporating and crystallizing concentrated salt water in coal chemical industry, and the patent number is as follows: CN 105399262A, the invention utilizes the concentrated brine of coal chemical industry to recover industrial-grade crystal salt through coagulating sedimentation, stripping, ultrafiltration, nanofiltration, active carbon, ion resin and evaporation crystallization processes. A process for preparing sulfuric acid from sulfur dioxide is disclosed in CN 102530888A, which is to prepare sulfuric acid from sulfur dioxide gas in the production process of anhydrite cement by two-stage contact oxidation and oxidation of vanadium or lithium sulfate catalyst. However, the first invention relates to the preparation of sodium chloride and sodium nitrate only, and the second invention relates to the preparation of concentrated sulfuric acid in the cement industry only. Therefore, a method for preparing sodium bisulfate by resource utilization of coal chemical waste gas and strong brine needs to be researched.
Disclosure of Invention
The invention aims to solve the problem that the waste gas and the waste water in the coal chemical industry can be treated and recycled at the same time, and provides a method for preparing sodium bisulfate by recycling the waste gas and the waste water in the coal chemical industry.
The invention relates to a method for preparing sodium bisulfate by resource utilization of coal chemical industry waste gas and waste water, which is carried out according to the following steps:
firstly, a regulating reservoir: introducing the coal chemical wastewater into a regulating reservoir, regulating the water outlet amount and stabilizing the water quality;
secondly, passivation technology: adding calcium oxide, a magnesium agent, sodium carbonate, a coagulant and a coagulant aid into the coal chemical industry wastewater, wherein the adding amount of the calcium oxide is 100-150 mg/L; the adding amount of the sodium carbonate is 60-70 mg/L; the addition amount of the coagulant is 50 mg/L-100 mg/L; the adding amount of the coagulant aid is 0.5-1.0 mg/L; the magnesium agent and SiO in the coal chemical industry wastewater3 2-The mass ratio of (A) to (B) is 12: 1; wherein the hardness of effluent is less than 50mg/L, and the silicon is less than 25 mg/L;
thirdly, multi-medium filtration: introducing the effluent obtained in the step two into a multi-media filter to remove particles, colloids and suspended matters in the coal chemical industry wastewater, wherein the turbidity of the effluent obtained in the step three is less than 0.1 NTU;
fourthly, ion exchange resin: introducing the effluent obtained in the step three into an ion exchange resin device to obtain effluent with the hardness of less than 2mg/L after the effluent passes through the ion exchange resin;
and fifthly, nanofiltration separation: introducing the effluent obtained in the step four into a nanofiltration system, and performing nanofiltration treatment to form nanofiltration permeate taking sodium chloride as a main component and nanofiltration concentrated water taking sodium sulfate as a main component;
sixthly, washing waste gas: removing suspended impurities, acid mist, fluorine and moisture in the waste gas of the coal chemical industry through a cyclone separator, a spray tower, an electric demister and a drying tower; thereby obtaining a dry purge gas;
seventhly, sulfur dioxide absorption: introducing the obtained dry purified gas into the middle part of the desulfurizing tower, and making the dry purified gas be in countercurrent contact with a desulfurizing agent entering from the top of the desulfurizing tower so that the desulfurizing agent absorbs sulfur dioxide in the waste gas; discharging the treated coal chemical waste gas from the top of the desulfurizing tower, and discharging the desulfurizing agent adsorbing sulfur dioxide from the bottom of the desulfurizing tower;
eighthly, pyrolyzing and regenerating a desulfurizing agent: the rich solution absorbed in the step seven is sent into a regeneration tower, pure sulfur dioxide gas is discharged from the top of the regeneration tower, and the regenerated barren solution returns to the upper part of the desulfurization tower for cyclic utilization; the pregnant solution is a desulfurizer of sulfur dioxide;
ninthly, preparing sulfur trioxide by catalytic oxidation: sending the sulfur dioxide gas discharged in the step eight into a contact chamber, and preparing sulfur trioxide at the temperature of 450 ℃ under the catalytic action of vanadium pentoxide;
and tenthly, preparing pyrosulfuric acid: reducing the temperature of the sulfur trioxide gas prepared in the ninth step to 150 ℃ through heat exchange, and then absorbing the gas in an absorption tower by using concentrated sulfuric acid with the volume percentage content of 98.3% to prepare pyrosulfuric acid;
eleven, preparing sulfuric acid: adding water into the pyrosulfuric acid obtained in the step ten to prepare industrial concentrated sulfuric acid;
and twelfth, distillation and purification: purifying the industrial concentrated sulfuric acid prepared in the step eleven by a distillation process;
thirteen, introducing nanofiltration permeate which is mainly sodium chloride and is generated in the fifth step into a reaction kettle, simultaneously adding concentrated sulfuric acid with the volume percentage of 95% and prepared in the twelfth step, and preparing sodium bisulfate solution in the reaction kettle;
fourteen, namely: sodium bisulfate evaporation crystallization process: introducing the sodium bisulfate solution prepared in the step thirteen into an evaporation crystallizer with the temperature of 90-120 ℃ to prepare sodium bisulfate, and then preparing industrial sodium bisulfate in a crystallizer with the temperature of 130-195 ℃;
fifteen: an anhydrous sodium sulfate evaporation crystallization process: pumping the nanofiltration concentrated water taking sodium sulfate as a main component into an evaporator, evaporating and concentrating the salt content in the water discharged from the step five to 180,000-200000 mg/L, then conveying the concentrated salt solution into a crystallizer, and controlling the crystallization temperature to be 95-105 ℃ to prepare the industrial anhydrous sodium sulfate.
The invention has the following beneficial effects:
when the method is used for treating the waste gas and the waste water (especially the strong brine in the waste water) in the coal chemical industry, the resource rate of the water body and the gas in the coal chemical industry is improved.
The raw materials for preparing the sodium bisulfate, namely sulfur dioxide in the coal chemical industry waste gas and sodium chloride in the concentrated brine are generated in the coal chemical industry production process, so that the economic feasibility is realized;
the invention directly utilizes the sulfur dioxide in the waste gas to produce the sulfuric acid, saves the sulfur recovery process when the waste gas is treated in the coal chemical industry, and saves the energy consumption.
The resource conversion rate of the invention reaches more than 80%.
Drawings
FIG. 1 is a flow chart of preparing sodium bisulfate by resource utilization of coal chemical waste gas and concentrated brine.
Detailed Description
The first embodiment is as follows: the method for preparing sodium bisulfate by resource utilization of coal chemical industry waste gas and wastewater in the embodiment is carried out according to the following steps:
firstly, a regulating reservoir: introducing the coal chemical wastewater into a regulating reservoir, regulating the water outlet amount and stabilizing the water quality;
secondly, passivation technology: adding calcium oxide, a magnesium agent, sodium carbonate, a coagulant and a coagulant aid into the coal chemical industry wastewater, wherein the adding amount of the calcium oxide is 100-150 mg/L; the adding amount of the sodium carbonate is 60-70 mg/L; the addition amount of the coagulant is 50 mg/L-100 mg/L; the adding amount of the coagulant aid is 0.5-1.0 mg/L; the magnesium agent and SiO in the coal chemical industry wastewater3 2-The mass ratio of (A) to (B) is 12: 1; wherein the hardness of effluent is less than 50mg/L, and the silicon is less than 25 mg/L;
thirdly, multi-medium filtration: introducing the effluent obtained in the step two into a multi-media filter to remove particles, colloids and suspended matters in the coal chemical industry wastewater, wherein the turbidity of the effluent obtained in the step three is less than 0.1 NTU;
fourthly, ion exchange resin: introducing the effluent obtained in the step three into an ion exchange resin device to obtain effluent with the hardness of less than 2mg/L after the effluent passes through the ion exchange resin;
and fifthly, nanofiltration separation: introducing the effluent obtained in the step four into a nanofiltration system, and performing nanofiltration treatment to form nanofiltration permeate taking sodium chloride as a main component and nanofiltration concentrated water taking sodium sulfate as a main component;
sixthly, washing waste gas: removing suspended impurities, acid mist, fluorine and moisture in the waste gas of the coal chemical industry through a cyclone separator, a spray tower, an electric demister and a drying tower; thereby obtaining a dry purge gas;
seventhly, sulfur dioxide absorption: introducing the obtained dry purified gas into the middle part of the desulfurizing tower, and making the dry purified gas be in countercurrent contact with a desulfurizing agent entering from the top of the desulfurizing tower so that the desulfurizing agent absorbs sulfur dioxide in the waste gas; discharging the treated coal chemical waste gas from the top of the desulfurizing tower, and discharging the desulfurizing agent adsorbing sulfur dioxide from the bottom of the desulfurizing tower;
eighthly, pyrolyzing and regenerating a desulfurizing agent: the rich solution absorbed in the step seven is sent into a regeneration tower, pure sulfur dioxide gas is discharged from the top of the regeneration tower, and the regenerated barren solution returns to the upper part of the desulfurization tower for cyclic utilization; the pregnant solution is a desulfurizer of sulfur dioxide;
ninthly, preparing sulfur trioxide by catalytic oxidation: sending the sulfur dioxide gas discharged in the step eight into a contact chamber, and preparing sulfur trioxide at the temperature of 450 ℃ under the catalytic action of vanadium pentoxide;
and tenthly, preparing pyrosulfuric acid: reducing the temperature of the sulfur trioxide gas prepared in the ninth step to 150 ℃ through heat exchange, and then absorbing the gas in an absorption tower by using concentrated sulfuric acid with the volume percentage content of 98.3% to prepare pyrosulfuric acid;
eleven, preparing sulfuric acid: adding water into the pyrosulfuric acid obtained in the step ten to prepare industrial concentrated sulfuric acid;
and twelfth, distillation and purification: purifying the industrial concentrated sulfuric acid prepared in the step eleven by a distillation process;
thirteen, introducing nanofiltration permeate which is mainly sodium chloride and is generated in the fifth step into a reaction kettle, simultaneously adding concentrated sulfuric acid with the volume percentage of 95% and prepared in the twelfth step, and preparing sodium bisulfate solution in the reaction kettle;
fourteen, namely: sodium bisulfate evaporation crystallization process: introducing the sodium bisulfate solution prepared in the step thirteen into an evaporation crystallizer with the temperature of 90-120 ℃ to prepare sodium bisulfate, and then preparing industrial sodium bisulfate in a crystallizer with the temperature of 130-195 ℃;
fifteen: an anhydrous sodium sulfate evaporation crystallization process: pumping the nanofiltration concentrated water taking sodium sulfate as a main component into an evaporator, evaporating and concentrating the salt content in the water discharged from the step five to 180,000-200000 mg/L, then conveying the concentrated salt solution into a crystallizer, and controlling the crystallization temperature to be 95-105 ℃ to prepare the industrial anhydrous sodium sulfate.
The purpose of adding the chemical in the second step of the embodiment is to remove heavy metals, silicon and suspended matters in the concentrated brine in the coal chemical industry.
In the third step of the embodiment, particles, colloid and suspended matters in the coal chemical industry concentrated brine are intercepted in the multi-medium filter through the multi-layer filter material of the multi-medium filter, so that the purpose of removing particulate matters, colloid and suspended matters in the coal chemical industry concentrated brine is achieved.
In the fourth step of the embodiment, the chemical bond formed by the calcium and magnesium ions in the concentrated brine in the coal chemical industry and the functional group of the ion exchange resin is stronger, so that the cations in the ion exchange resin are replaced, and the LSI index in the concentrated brine is effectively reduced.
The ion exchange resin in the fourth embodiment has a high degree of crosslinking and has characteristics of handling high-salt water and high-pH water.
The nanofiltration membrane in the fifth step of the embodiment has the characteristics of small aperture and strong electronegativity on the surface of the membrane, the nondegradable organic matters in the concentrated brine are removed through the screening effect, and multivalent ions are intercepted through the charge effect and penetrate through monovalent ions at the same time. The rejection rate of the nanofiltration membrane on organic matters is more than 70%, the rejection rate on multivalent cations is more than 60%, the rejection rate on multivalent anions is more than 90%, and the rejection rate on monovalent ions is 10% or even negative.
The material and configuration of the nanofiltration membrane in the fifth step of the embodiment are related to the anti-pollution capability to the strong brine in the coal chemical industry, and the anti-pollution capability of the nanofiltration process has an influence on the stability and reliability of the process.
In the sixth step of the present embodiment, the concentration of the liquid dilute sulfuric acid in the spray tower is 10%;
in the sixth step of the embodiment, the concentration of concentrated sulfuric acid in the drying tower is 93-95%;
the gas components after the washing of the waste gas in the sixth step of the present embodiment are sulfur dioxide, oxygen, and nitrogen.
The wastewater of this example was concentrated brine.
Chemical reaction basis for generating indoor sulfur trioxide in step nine of the embodiment(reversible reaction) is carried out;
the chemical reaction basis in the tenth absorption tower in the step of the present embodimentCarrying out the following steps;
the step of the present embodiment is based on H for the undecamated sulfuric acid and water2SO7+H2O=2H2SO4Generating sulfuric acid;
the concentration of concentrated sulfuric acid after the twelve-step distillation and purification in the embodiment is 95 to 98 percent;
in the thirteenth embodiment, the reaction equation for preparing sodium bisulfate in the reaction kettle is as follows:
the third concrete implementation mode: the first difference between the present embodiment and the specific embodiment is: the structure of the nanofiltration membrane comprises a roll type nanofiltration membrane, a disc tube type nanofiltration membrane or a vibration membrane and the like. The rest is the same as the first embodiment.
The fourth concrete implementation mode: the first difference between the present embodiment and the specific embodiment is: the coagulant in the second step is polyferric chloride or ferrous sulfate, and the coagulant aid is polyacrylamide, and the other steps are the same as those in the first embodiment.
The fifth concrete implementation mode: the first difference between the present embodiment and the specific embodiment is: the magnesium agent in the second step is magnesia. The rest is the same as the first embodiment. The magnesium agent comprises magnesite, the magnesium agent is described in the foregoing, and the general perceived range of the magnesium agent is described as having problems in this embodiment.
The sixth specific implementation mode: the first difference between the present embodiment and the specific embodiment is: the filter material of the multi-media filter in the third step is active carbon-quartz sand-magnetite and the like. The rest is the same as the first embodiment.
The specific implementation mode is eight: the first difference between the present embodiment and the specific embodiment is: and seventhly, the desulfurizer is renewable organic solvent tetraethylene glycol dimethyl ether, and the volume percentage content is 98%. The rest is the same as the first embodiment.
The specific implementation method nine: the first difference between the present embodiment and the specific embodiment is: in the thirteenth step, the molar ratio of the concentrated sulfuric acid to the sodium chloride in the reaction kettle is 1-1.2: 1. the rest is the same as the first embodiment.
The detailed implementation mode is ten: the first difference between the present embodiment and the specific embodiment is: and in the thirteenth step, the temperature of the reaction kettle is 120 ℃, and the reaction time is 20 min. The rest is the same as the first embodiment.
The concrete implementation mode eleven: the first difference between the present embodiment and the specific embodiment is: the desulfurizing agent is 24 wt% phosphate solution. The rest is the same as the first embodiment.
The specific implementation mode twelve: the first difference between the present embodiment and the specific embodiment is: the desulfurizing agent is 28 wt% of TMHEED amine, namely N, N, N-trimethyl and N-2-hydroxyethyl ethylenediamine. The rest is the same as the first embodiment.
The specific implementation mode is thirteen: the first difference between the present embodiment and the specific embodiment is: the evaporative crystallizers in the fourteenth and fifteenth steps are a mechanical falling film evaporation MVR evaporator, a forced circulation evaporative crystallizer, a continuous evaporative crystallizer and a multi-effect evaporative crystallizer. The rest is the same as the first embodiment.
The beneficial effects of the present invention are demonstrated by the following examples:
example 1
The method for preparing sodium bisulfate by resource utilization of coal chemical industry waste gas and strong brine is carried out according to the following steps:
firstly, a regulating reservoir: introducing the coal chemical strong brine raw water into a regulating reservoir to regulate the quality and quantity of the effluent;
secondly, passivation technology: introducing the coal chemical industry strong brine obtained in the step one into a passivation process, and adding calcium oxide, a magnesium agent, sodium carbonate, a coagulant and a coagulant aid, wherein the hardness of effluent water in the process is less than 50mg/L, and the silicon content is less than 25 mg/L; the dosage of the calcium oxide is 2000 mg/L; the adding amount of the sodium carbonate is 2500 mg/L; the addition amount of the coagulant is 50 mg/L-100 mg/L; the dosage of the coagulant aid is 0.5 mg/L; the magnesium agent and SiO in the concentrated brine in coal chemical industry3 2-The mass ratio of (A) to (B) is 12: 1;
thirdly, multi-medium filtration: introducing the effluent obtained in the step two into a multi-medium filter to remove particles, suspended matters and colloid, wherein the turbidity of the effluent obtained in the step three is less than 0.1 NTU;
fourthly, ion exchange resin; introducing the effluent obtained in the third step into an ion exchange resin device, and removing the hardness of the concentrated salt water by replacing calcium and magnesium ions in the concentrated salt water in the coal chemical industry with functional groups of the ion exchange resin, wherein the hardness of the effluent obtained in the fourth step is less than 2 mg/L;
and fifthly, nanofiltration separation: introducing the effluent obtained in the step four into a nanofiltration system, intercepting organic matter multivalent salt in the coal chemical industry strong brine through a nanofiltration membrane, and performing nanofiltration treatment to form nanofiltration permeate taking sodium chloride as a main component and nanofiltration concentrated water taking sodium sulfate as a main component;
sixthly, washing waste gas: and (3) removing suspended impurities, acid mist, fluorine and moisture in the waste gas in the coal chemical industry through a cyclone separator, a spray tower, an electric demister and a drying tower. Suspended impurities in the settled waste gas are separated by utilizing the mechanical force in the cyclone separator; the waste gas passes through a liquid layer of the spray tower or is sprayed by liquid in the spray tower, so that impurities in the waste gas are further removed; the electric demister is used for removing acid mist in the waste gas; introducing the waste gas into a drying tower to be in countercurrent contact with concentrated sulfuric acid, thereby obtaining dry purified gas;
seventhly, sulfur dioxide absorption: and D, introducing the waste gas washed in the step six into the middle of the desulfurizing tower, and enabling the waste gas to be in countercurrent contact with a desulfurizing agent entering from the top of the desulfurizing tower, so that the desulfurizing agent absorbs sulfur dioxide in the waste gas. Discharging the treated coal chemical waste gas from the top of the desulfurizing tower, and discharging the desulfurizing agent adsorbing sulfur dioxide from the bottom of the desulfurizing tower;
eighthly, pyrolyzing and regenerating a desulfurizing agent: and (4) feeding the rich solution (the desulfurizer absorbing the sulfur dioxide) in the step seven into a regeneration tower, and decomposing the sulfur dioxide by heating the rich solution in the regeneration tower while regenerating the rich solution in a form of a barren solution. Wherein the pure sulfur dioxide gas is discharged from the top of the regeneration tower, and the regenerated barren solution returns to the upper part of the desulfurization tower for recycling.
Ninthly, preparing sulfur trioxide by catalytic oxidation: and (5) sending the sulfur dioxide gas discharged in the step eight into a contact chamber, and preparing sulfur trioxide through the catalysis of vanadium pentoxide at the high temperature of 450 ℃. Chemical reaction basis for generating sulfur trioxide in contact chamber(reversible reaction) is carried out;
and tenthly, preparing pyrosulfuric acid: reducing the temperature of the sulfur trioxide gas prepared in the step nine to 150 ℃ through heat exchange, and preparing the pyrosulfuric acid (H) after the sulfur trioxide gas is absorbed by 98.3 percent concentrated sulfuric acid in an absorption tower2S2O7). Chemical reaction basis in absorption towerCarrying out the following steps;
eleven, preparing sulfuric acid: and (4) adding water into the pyrosulfuric acid obtained in the step ten to prepare sulfuric acid. Disulfuric acid and water according to H2SO7+H2O=2H2SO4Generating sulfuric acid;
and twelfth, distillation and purification: purifying the industrial concentrated sulfuric acid prepared in the step eleven by a distillation process;
thirteen, introducing nanofiltration permeate which is mainly sodium chloride and is generated in the fifth step into a reaction kettle, simultaneously adding 95% concentrated sulfuric acid prepared in the twelfth step, and preparing sodium bisulfate solution in the reaction kettle;
fourteen, namely: sodium bisulfate evaporation crystallization process: and C, introducing the sodium bisulfate solution prepared in the step thirteen into an evaporation crystallizer with the temperature of 90-120 ℃ to prepare sodium bisulfate, and then preparing industrial sodium bisulfate in a crystallizer with the temperature of 130-195 ℃.
Fifteen: an anhydrous sodium sulfate evaporation crystallization process: pumping the nanofiltration concentrated water obtained in the step five into an evaporator to evaporate and concentrate the salt content in the water obtained in the step five to 200,000mg/L, then conveying the concentrated salt solution into a crystallizer, and controlling the crystallization temperature to be 95-105 ℃ to prepare the industrial anhydrous sodium sulfate.
The wastewater of this example was concentrated brine.
The purpose of adding the chemical in the second step of this embodiment is to remove heavy metals, silicon and suspended solids in the concentrated brine in the coal chemical industry.
In the third step of this embodiment, particles, colloid and suspended solid in the coal chemical industry strong brine are held back in the multi-media filter through the multilayer filter material of multi-media filter, reach the purpose of getting rid of particulate matter, colloid and suspended solid in the coal chemical industry strong brine.
In the fourth step of this embodiment, the chemical bond formed by the calcium and magnesium ions in the concentrated brine of coal chemical industry and the functional groups of the ion exchange resin is stronger, and replaces the cations in the ion exchange resin, thereby effectively reducing the LSI index in the concentrated brine.
The ion exchange resin in the fourth embodiment has high degree of crosslinking and has characteristics of treating high-salt water and high-pH water.
The nanofiltration membrane in the fifth step of the embodiment has the characteristics of small pore diameter and strong electronegativity of the membrane surface, the nondegradable organic matters in the concentrated brine are removed through the screening effect, and multivalent ions are intercepted through the charge effect and penetrate through monovalent ions at the same time. The rejection rate of the nanofiltration membrane on organic matters is more than 70%, the rejection rate on multivalent cations is more than 60%, the rejection rate on multivalent anions is more than 90%, and the rejection rate on monovalent ions is 10% or even negative.
The nanofiltration membrane in the fifth step of this embodiment is made of a composite membrane material of semi-aromatic piperazine polyamide.
The nanofiltration membrane configuration in the fifth step of the embodiment comprises a rolled nanofiltration membrane.
The material and configuration of the nanofiltration membrane in the fifth step of the embodiment are related to the anti-pollution capability to the strong brine in the coal chemical industry, and the anti-pollution capability of the nanofiltration process has an influence on the stability and reliability of the process.
In the sixth step of this embodiment, the concentration of the liquid dilute sulfuric acid in the spray tower is 10%;
in the sixth step of this embodiment, the concentrated sulfuric acid concentration in the drying tower is 93% to 95%;
in this embodiment, the gas components after the washing of the waste gas in step six are sulfur dioxide, oxygen, and nitrogen.
The desulfurizing agent in the seventh step of the present embodiment is a renewable organic solvent, namely tetraethylene glycol dimethyl ether, and the concentration of the desulfurizing agent is 98%;
the concentration of concentrated sulfuric acid after twelve-step distillation purification in the embodiment is 95-98%;
in the thirteenth embodiment, the molar ratio of the concentrated sulfuric acid to the sodium chloride in the reaction kettle is 1: 1.
in the thirteenth embodiment, the temperature in the reaction kettle is 120 ℃ and the reaction time is 20 minutes.
The reaction equation for preparing sodium bisulfate in the reaction kettle in the thirteen embodiment is as follows:
the results of the present example are shown in tables 1 to 4.
TABLE 1 Water quality meter
TABLE 2 quality of inlet and outlet water for strong brine treatment in coal chemical industry
As can be seen from Table 2, the coal chemical industry strong brine can effectively obtain the strong brine mainly containing sodium chloride after being treated by the technology.
TABLE 3 exhaust gas treatment experiment
As can be seen from Table 3, 90% pyrosulfuric acid was obtained by the above technical treatment, and then 90% concentrated sulfuric acid was obtained by reaction with water to give 98% concentrated sulfuric acid.
Table 4 sodium bisulfate liquid preparation
Remarking: the NaCl concentration of the solution was 64071mg/L.
As is clear from table 4, sodium chloride and sodium sulfate obtained by the above techniques can efficiently produce sodium bisulfate. As the concentration of sulfuric acid increases from 90% to 98%, the conversion of sodium chloride solution to sodium bisulfate by reaction with sulfuric acid increases from 91.34 to 93.94%.

Claims (7)

1. A method for preparing sodium bisulfate by resource utilization of coal chemical industry waste gas and wastewater is characterized by comprising the following steps:
firstly, a regulating reservoir: introducing the coal chemical wastewater into a regulating reservoir, regulating the water outlet amount and stabilizing the water quality;
secondly, passivation technology: adding calcium oxide, a magnesium agent, sodium carbonate, a coagulant and a coagulant aid into the coal chemical industry wastewater, wherein the adding amount of the calcium oxide is 100-150 mg/L; the adding amount of the sodium carbonate is 60-70 mg/L; the addition amount of the coagulant is 50 mg/L-100 mg/L; the adding amount of the coagulant aid is 0.5-1.0 mg/L; the magnesium agent and SiO in the coal chemical industry wastewater3 2-The mass ratio of (A) to (B) is 12: 1; wherein the hardness of effluent is less than 50mg/L, and the silicon is less than 25 mg/L;
thirdly, multi-medium filtration: introducing the effluent obtained in the step two into a multi-media filter to remove particles, colloids and suspended matters in the coal chemical industry wastewater, wherein the turbidity of the effluent obtained in the step three is less than 0.1 NTU;
fourthly, ion exchange resin: introducing the effluent obtained in the step three into an ion exchange resin device to obtain effluent with the hardness of less than 2mg/L after the effluent passes through the ion exchange resin;
and fifthly, nanofiltration separation: introducing the effluent obtained in the step four into a nanofiltration system, and performing nanofiltration treatment to form nanofiltration permeate taking sodium chloride as a main component and nanofiltration concentrated water taking sodium sulfate as a main component;
sixthly, washing waste gas: removing suspended impurities, acid mist, fluorine and moisture in the waste gas of the coal chemical industry through a cyclone separator, a spray tower, an electric demister and a drying tower; thereby obtaining a dry purge gas;
seventhly, sulfur dioxide absorption: introducing the obtained dry purified gas into the middle part of the desulfurizing tower, and making the dry purified gas be in countercurrent contact with a desulfurizing agent entering from the top of the desulfurizing tower so that the desulfurizing agent absorbs sulfur dioxide in the waste gas; discharging the treated coal chemical waste gas from the top of the desulfurizing tower, and discharging the desulfurizing agent adsorbing sulfur dioxide from the bottom of the desulfurizing tower;
eighthly, pyrolyzing and regenerating a desulfurizing agent: the rich solution absorbed in the step seven is sent into a regeneration tower, pure sulfur dioxide gas is discharged from the top of the regeneration tower, and the regenerated barren solution returns to the upper part of the desulfurization tower for cyclic utilization; the pregnant solution is a desulfurizer of sulfur dioxide;
ninthly, preparing sulfur trioxide by catalytic oxidation: sending the sulfur dioxide gas discharged in the step eight into a contact chamber, and preparing sulfur trioxide at the temperature of 450 ℃ under the catalytic action of vanadium pentoxide;
and tenthly, preparing pyrosulfuric acid: reducing the temperature of the sulfur trioxide gas prepared in the ninth step to 150 ℃ through heat exchange, and then absorbing the gas in an absorption tower by using concentrated sulfuric acid with the volume percentage content of 98.3% to prepare pyrosulfuric acid;
eleven, preparing sulfuric acid: adding water into the pyrosulfuric acid obtained in the step ten to prepare industrial concentrated sulfuric acid;
and twelfth, distillation and purification: purifying the industrial concentrated sulfuric acid prepared in the step eleven by a distillation process;
thirteen, introducing nanofiltration permeate which is mainly sodium chloride and is generated in the fifth step into a reaction kettle, simultaneously adding concentrated sulfuric acid with the volume percentage of 95% and prepared in the twelfth step, and preparing sodium bisulfate solution in the reaction kettle;
fourteen, namely: sodium bisulfate evaporation crystallization process: introducing the sodium bisulfate solution prepared in the step thirteen into an evaporation crystallizer with the temperature of 90-120 ℃ to prepare sodium bisulfate, and then preparing industrial sodium bisulfate in a crystallizer with the temperature of 130-195 ℃;
fifteen: an anhydrous sodium sulfate evaporation crystallization process: pumping the nanofiltration concentrated water taking sodium sulfate as a main component into an evaporator, evaporating and concentrating the salt content in the water discharged from the step five to 180,000-200000 mg/L, then conveying the concentrated salt solution into a crystallizer, and controlling the crystallization temperature to be 95-105 ℃ to prepare industrial anhydrous sodium sulfate; in the thirteenth step, the molar ratio of the concentrated sulfuric acid to the sodium chloride in the reaction kettle is 1-1.2: 1; and in the thirteenth step, the temperature of the reaction kettle is 120 ℃, and the reaction time is 20 min.
2. The method for preparing sodium bisulfate by resource utilization of coal chemical industry waste gas and wastewater as claimed in claim 1, wherein the coagulant in step two is polyferric chloride or ferrous sulfate.
3. The method for preparing sodium bisulfate by resource utilization of coal chemical industry waste gas and wastewater as claimed in claim 1, wherein the coagulant aid in step two is polyacrylamide.
4. The method for preparing sodium bisulfate by resource utilization of coal chemical industry waste gas and wastewater as claimed in claim 1, wherein the magnesium agent in step two is magnesite.
5. The method for preparing sodium bisulfate by resource utilization of coal chemical industry waste gas and wastewater as claimed in claim 1, wherein the filter material of the multi-media filter in step three is activated carbon-quartz sand-magnetite.
6. The method for preparing sodium bisulfate by resource utilization of coal chemical industry waste gas and wastewater as claimed in claim 1, wherein the desulfurizing agent in step seven is tetraethylene glycol dimethyl ether which is a renewable organic solvent, and the volume percentage content is 98%.
7. The method for preparing sodium bisulfate by resource utilization of coal chemical industry waste gas and wastewater as claimed in claim 1, wherein the wastewater is concentrated brine.
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