CN116692981A - Recycling treatment process and treatment system for nitrobenzene wastewater - Google Patents
Recycling treatment process and treatment system for nitrobenzene wastewater Download PDFInfo
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- CN116692981A CN116692981A CN202310704540.7A CN202310704540A CN116692981A CN 116692981 A CN116692981 A CN 116692981A CN 202310704540 A CN202310704540 A CN 202310704540A CN 116692981 A CN116692981 A CN 116692981A
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- LQNUZADURLCDLV-UHFFFAOYSA-N nitrobenzene Chemical compound [O-][N+](=O)C1=CC=CC=C1 LQNUZADURLCDLV-UHFFFAOYSA-N 0.000 title claims abstract description 330
- 239000002351 wastewater Substances 0.000 title claims abstract description 186
- 238000000034 method Methods 0.000 title claims abstract description 76
- 230000008569 process Effects 0.000 title claims abstract description 54
- 238000004064 recycling Methods 0.000 title claims abstract description 40
- 239000000463 material Substances 0.000 claims abstract description 92
- 239000007789 gas Substances 0.000 claims abstract description 21
- 239000012071 phase Substances 0.000 claims abstract description 21
- 239000007791 liquid phase Substances 0.000 claims abstract description 15
- 239000002912 waste gas Substances 0.000 claims abstract description 15
- 230000009467 reduction Effects 0.000 claims abstract description 8
- 238000002347 injection Methods 0.000 claims description 44
- 239000007924 injection Substances 0.000 claims description 44
- 239000003513 alkali Substances 0.000 claims description 31
- IOVCWXUNBOPUCH-UHFFFAOYSA-M Nitrite anion Chemical compound [O-]N=O IOVCWXUNBOPUCH-UHFFFAOYSA-M 0.000 claims description 28
- 239000002253 acid Substances 0.000 claims description 24
- 230000001105 regulatory effect Effects 0.000 claims description 22
- 238000010438 heat treatment Methods 0.000 claims description 20
- 238000000926 separation method Methods 0.000 claims description 14
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 claims description 9
- ODINCKMPIJJUCX-UHFFFAOYSA-N Calcium oxide Chemical compound [Ca]=O ODINCKMPIJJUCX-UHFFFAOYSA-N 0.000 claims description 6
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 claims description 6
- 230000007363 regulatory process Effects 0.000 claims description 5
- 239000000243 solution Substances 0.000 claims description 4
- 235000008733 Citrus aurantifolia Nutrition 0.000 claims description 3
- 235000011941 Tilia x europaea Nutrition 0.000 claims description 3
- 239000000292 calcium oxide Substances 0.000 claims description 3
- 235000012255 calcium oxide Nutrition 0.000 claims description 3
- 150000007529 inorganic bases Chemical class 0.000 claims description 3
- 239000004571 lime Substances 0.000 claims description 3
- 239000008267 milk Substances 0.000 claims description 3
- 210000004080 milk Anatomy 0.000 claims description 3
- 235000013336 milk Nutrition 0.000 claims description 3
- 235000011121 sodium hydroxide Nutrition 0.000 claims description 3
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 abstract description 20
- 239000003245 coal Substances 0.000 abstract description 13
- 238000002309 gasification Methods 0.000 abstract description 5
- 238000012423 maintenance Methods 0.000 abstract description 4
- 230000000052 comparative effect Effects 0.000 description 19
- 230000007797 corrosion Effects 0.000 description 16
- 238000005260 corrosion Methods 0.000 description 16
- 239000003250 coal slurry Substances 0.000 description 11
- LSNNMFCWUKXFEE-UHFFFAOYSA-N Sulfurous acid Chemical compound OS(O)=O LSNNMFCWUKXFEE-UHFFFAOYSA-N 0.000 description 9
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 8
- 230000014759 maintenance of location Effects 0.000 description 8
- 238000005457 optimization Methods 0.000 description 8
- 230000020477 pH reduction Effects 0.000 description 8
- 239000002002 slurry Substances 0.000 description 8
- 239000000126 substance Substances 0.000 description 8
- 238000004519 manufacturing process Methods 0.000 description 7
- 230000000694 effects Effects 0.000 description 6
- 238000005516 engineering process Methods 0.000 description 6
- 230000001276 controlling effect Effects 0.000 description 5
- 238000010025 steaming Methods 0.000 description 5
- 238000004065 wastewater treatment Methods 0.000 description 5
- 229910052742 iron Inorganic materials 0.000 description 4
- 239000005416 organic matter Substances 0.000 description 4
- 239000000654 additive Substances 0.000 description 3
- 239000003463 adsorbent Substances 0.000 description 3
- 238000009835 boiling Methods 0.000 description 3
- 238000006243 chemical reaction Methods 0.000 description 3
- 244000005700 microbiome Species 0.000 description 3
- 238000007254 oxidation reaction Methods 0.000 description 3
- 239000000047 product Substances 0.000 description 3
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 2
- 230000002378 acidificating effect Effects 0.000 description 2
- 239000012043 crude product Substances 0.000 description 2
- 230000006378 damage Effects 0.000 description 2
- 238000009826 distribution Methods 0.000 description 2
- 239000003344 environmental pollutant Substances 0.000 description 2
- 238000000605 extraction Methods 0.000 description 2
- 238000006386 neutralization reaction Methods 0.000 description 2
- 229940005654 nitrite ion Drugs 0.000 description 2
- 239000007800 oxidant agent Substances 0.000 description 2
- 230000003647 oxidation Effects 0.000 description 2
- 231100000719 pollutant Toxicity 0.000 description 2
- 238000002360 preparation method Methods 0.000 description 2
- 150000003839 salts Chemical class 0.000 description 2
- 238000001179 sorption measurement Methods 0.000 description 2
- 238000005406 washing Methods 0.000 description 2
- 241001465754 Metazoa Species 0.000 description 1
- IOVCWXUNBOPUCH-UHFFFAOYSA-N Nitrous acid Chemical compound ON=O IOVCWXUNBOPUCH-UHFFFAOYSA-N 0.000 description 1
- 230000000996 additive effect Effects 0.000 description 1
- XKMRRTOUMJRJIA-UHFFFAOYSA-N ammonia nh3 Chemical compound N.N XKMRRTOUMJRJIA-UHFFFAOYSA-N 0.000 description 1
- 208000007502 anemia Diseases 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
- 239000000440 bentonite Substances 0.000 description 1
- 229910000278 bentonite Inorganic materials 0.000 description 1
- SVPXDRXYRYOSEX-UHFFFAOYSA-N bentoquatam Chemical compound O.O=[Si]=O.O=[Al]O[Al]=O SVPXDRXYRYOSEX-UHFFFAOYSA-N 0.000 description 1
- 238000002306 biochemical method Methods 0.000 description 1
- 238000010170 biological method Methods 0.000 description 1
- 230000000711 cancerogenic effect Effects 0.000 description 1
- 231100000315 carcinogenic Toxicity 0.000 description 1
- 239000003638 chemical reducing agent Substances 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 239000000356 contaminant Substances 0.000 description 1
- 238000010924 continuous production Methods 0.000 description 1
- 239000000498 cooling water Substances 0.000 description 1
- 238000000354 decomposition reaction Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000004043 dyeing Methods 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 230000002349 favourable effect Effects 0.000 description 1
- 239000000945 filler Substances 0.000 description 1
- 239000012847 fine chemical Substances 0.000 description 1
- 239000010881 fly ash Substances 0.000 description 1
- 238000010528 free radical solution polymerization reaction Methods 0.000 description 1
- 238000000227 grinding Methods 0.000 description 1
- 239000010842 industrial wastewater Substances 0.000 description 1
- 230000005764 inhibitory process Effects 0.000 description 1
- 201000007270 liver cancer Diseases 0.000 description 1
- 208000019423 liver disease Diseases 0.000 description 1
- 208000014018 liver neoplasm Diseases 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 210000005036 nerve Anatomy 0.000 description 1
- -1 nitrite ions Chemical class 0.000 description 1
- 238000000053 physical method Methods 0.000 description 1
- 238000007639 printing Methods 0.000 description 1
- 238000004886 process control Methods 0.000 description 1
- 238000004537 pulping Methods 0.000 description 1
- 239000011347 resin Substances 0.000 description 1
- 229920005989 resin Polymers 0.000 description 1
- 239000002904 solvent Substances 0.000 description 1
- 238000003786 synthesis reaction Methods 0.000 description 1
- 239000004753 textile Substances 0.000 description 1
- 231100000331 toxic Toxicity 0.000 description 1
- 230000002588 toxic effect Effects 0.000 description 1
Classifications
-
- 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
- C02F1/02—Treatment of water, waste water, or sewage by heating
- C02F1/04—Treatment of water, waste water, or sewage by heating by distillation or evaporation
-
- 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
- C02F1/66—Treatment of water, waste water, or sewage by neutralisation; pH adjustment
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2101/00—Nature of the contaminant
- C02F2101/30—Organic compounds
- C02F2101/38—Organic compounds containing nitrogen
Landscapes
- Life Sciences & Earth Sciences (AREA)
- Hydrology & Water Resources (AREA)
- Engineering & Computer Science (AREA)
- Environmental & Geological Engineering (AREA)
- Water Supply & Treatment (AREA)
- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Removal Of Specific Substances (AREA)
Abstract
The invention discloses a recycling treatment process and a treatment system of nitrobenzene wastewater. The nitrobenzene wastewater to be treated exchanges heat with the materials extracted from the bottom of the removal tower through a first heat exchanger, the nitrobenzene wastewater after temperature rise enters the removal tower, and the materials at the bottom after temperature reduction enter the mill through a second heat exchanger. The gas phase material at the top of the removal tower enters a separating tank after being cooled by a cooler, the gas phase material discharged from the separating tank enters a waste gas treatment unit, and the discharged liquid phase material flows back into the removal tower. According to the invention, the nitrobenzene wastewater is efficiently utilized by definitely corroding the cause and removing the process measures, the unplanned shutdown risk is reduced, the cost expenditure of equipment updating and checking maintenance cost is reduced, the safe, stable and long-period operation of the coal gasification device is ensured, and the water resource saving and wastewater resource utilization capacity of enterprises is steadily improved.
Description
Technical Field
The invention relates to the technical field of wastewater treatment, in particular to a recycling treatment process and a treatment system for nitrobenzene wastewater.
Background
Nitrobenzene is an important chemical synthesis intermediate and is widely used in fine chemical industry, textile industry, printing and dyeing industry and the like. Nitrobenzene is a toxic, suspected carcinogenic compound that can cause nerve confusion, anemia, liver disease, and cancer in humans and animals. As nitrobenzene has the harm, relevant departments in China set corresponding standards, and the supervision of the substance is enhanced.
Conventional treatment techniques for nitrobenzene wastewater include biochemical, electrolytic, redox, reduction, advanced oxidation, extraction, adsorption, and the like. The biochemical method is to degrade organic matters in a bioreactor by means of domesticated microorganisms or special microorganisms. Electrolytic processes are processes that degrade organic matter using electrochemical generation of atomic oxygen. The reduction-oxidation method is to reduce the organic matter with reducing agent and then oxidize and degrade the organic matter with oxidizing agent. The reduction method is a biological or chemical method for reducing an organic substance. Advanced oxidation is a method of decomposing organic matter using a chemical oxidizing agent. The extraction method utilizes the selective distribution of solutes in two immiscible solvents to achieve separation of contaminants. The adsorption method is to adsorb pollutants on the adsorbent by using the adsorbent, so as to remove the pollutants in the wastewater. Commonly used adsorbents are activated carbon, fly ash, organic bentonite, resin, etc.
However, nitrobenzene wastewater generated in the production process has the characteristics of high microorganism inhibition, high ammonia nitrogen, high chromaticity and the like, so that the conventional nitrobenzene wastewater treatment technology is in the unfavorable situation of high cost and low income for a long time. The treatment of nitrobenzene wastewater has become one of the difficulties in industrial wastewater treatment.
In recent years, along with the continuous promotion of the concept of recycling wastewater, the conventional water is replaced by wastewater to prepare the coal water slurry, and the recycling of the wastewater is realized in a gasification mode, so that the method becomes a high-efficiency technical means with strong universality, good economical efficiency and simple and convenient operation flow, and has positive significance in the aspects of greatly reducing the conventional wastewater treatment cost, sites, saving water resources and the like. Regarding the method for cooperatively treating nitrobenzene wastewater by using the coal water slurry technology, reference 1 can be referred to:
reference 1: chinese patent document with patent publication No. CN102417249 a.
Reference 1 discloses a method for treating nitrobenzene wastewater, which is to prepare a water-coal-slurry additive by utilizing solution polymerization in the wastewater phase, thereby avoiding pollution of nitrobenzene wastewater discharge to the environment and realizing reutilization of nitrobenzene wastewater.
However, in the actual production process of cooperatively treating nitrobenzene wastewater by using the water-coal-slurry technology, the corrosion of the coal slurry is increased due to the high salt content and complex components of the nitrobenzene wastewater, so that a series of production problems caused by corrosion occur in equipment such as a mill, for example, the slurry leakage phenomenon at the bolted joint of a cylinder body is increased, the maintenance frequency of the equipment is increased, and the continuous and stable operation of the production of a coal gasification device is severely restricted.
In order to solve the above technical problems, the applicant has proposed a solution, see reference 2 for details:
reference 2: chinese patent document with patent publication No. CN114772794 a.
Reference 2 discloses a method for cooperatively treating nitrobenzene wastewater by using a coal water slurry technology, which is characterized in that the nitrobenzene wastewater is deoxidized, then nitrite in the iron and nitrobenzene wastewater is utilized to react, and then the reacted nitrobenzene wastewater, coal and additives are subjected to preparation of the coal water slurry. According to the technical scheme, a corrosion control method is provided from the technical point of view, corrosion causes are eliminated, unplanned shutdown caused by corrosion problems is reduced, excessive investment cost of enterprise material resources, manpower, financial resources and other costs is avoided, safe, stable and long-period operation of the coal gasification device is ensured, and meanwhile, water resource saving and wastewater resource utilization capacity is steadily improved.
However, in the technical scheme, iron-containing filler is consumed in pretreatment of the nitrobenzene wastewater, so that the cost for cooperatively treating the nitrobenzene wastewater by the coal water slurry technology is increased.
Disclosure of Invention
The invention aims to solve the problem of high treatment operation cost of a nitrobenzene wastewater cooperative treatment process by using a water-coal slurry technology in the prior art, and provides a recycling treatment process and a recycling treatment system for nitrobenzene wastewater.
The invention solves the technical problems, and adopts the following technical scheme: a recycling treatment system for nitrobenzene wastewater comprises a removal tower, a first heat exchanger, a cooler, a separation tank, an exhaust gas treatment unit, a second heat exchanger and a mill;
the removal tower is provided with a supersaturated steam inlet and a wastewater inlet, nitrobenzene wastewater to be treated exchanges heat with materials extracted from the tower bottom of the removal tower through a first heat exchanger, the nitrobenzene wastewater after temperature rise enters the removal tower through the wastewater inlet, and the tower bottom materials after temperature reduction enter a mill through a second heat exchanger;
the nitrobenzene wastewater feeding pipe of the first heat exchanger is connected with an acid injection unit, and the feeding pipe of the mill is connected with an alkali injection unit;
the gas phase material at the top of the removal tower enters a separation tank after being cooled by a cooler, the gas phase material discharged from the separation tank enters a waste gas treatment unit, and the discharged liquid phase material flows back into the removal tower.
As a further optimization of the recycling treatment system of nitrobenzene wastewater, the invention: the mill is a wet overflow mill, preferably a rod mill.
A recycling treatment process of nitrobenzene wastewater comprises the following steps: the method comprises the steps that nitrobenzene wastewater to be treated enters a first heat exchanger to exchange heat with materials extracted from the bottom of a removal tower after pH value adjustment through acid injection, the nitrobenzene wastewater after heat exchange enters the removal tower, nitrite in the nitrobenzene wastewater is removed by utilizing superheated steam heating in the removal tower, the materials at the top of the removal tower sequentially enter a cooler and a separating tank, gas-phase materials separated by the separating tank enter a waste gas treatment unit, liquid-phase materials separated by the separating tank flow back to the upper part of the removal tower, the materials at the bottom of the removal tower sequentially exchange heat through the first heat exchanger and a second heat exchanger, and the materials after heat exchange enter a mill after pH value adjustment through an alkali injection unit.
As a further optimization of the recycling treatment process of nitrobenzene wastewater, the invention: and the nitrobenzene wastewater to be treated enters a first heat exchanger after pH value is regulated to be less than or equal to 3 by acid injection.
As a further optimization of the recycling treatment process of nitrobenzene wastewater, the invention: the acid used in the process of regulating the acid injection contains H + Preferably sulfuric acid.
As a further optimization of the recycling treatment process of nitrobenzene wastewater, the invention: the temperature of nitrobenzene wastewater in the removal tower is not lower than 90 ℃.
As a further optimization of the recycling treatment process of nitrobenzene wastewater, the invention: the residence time of the nitrobenzene wastewater in the removal tower is more than or equal to 15min, preferably more than or equal to 10min.
As a further optimization of the recycling treatment process of nitrobenzene wastewater, the invention: and (3) regulating the pH value of the tower bottom material of the removal tower to 7-10 by alkali injection, and then entering the mill.
As a further optimization of the recycling treatment process of nitrobenzene wastewater, the invention: the alkali used in the alkali injection regulating process contains OH - Is an inorganic base of (a).
As a further optimization of the recycling treatment process of nitrobenzene wastewater, the invention: the alkali used in the alkali injection regulating process is one or more of caustic soda flakes, quicklime or lime milk and a solution thereof.
The invention has the following beneficial effects: according to the invention, the nitrobenzene wastewater is efficiently utilized by definitely corroding the cause and removing the process measures, the unplanned shutdown risk is reduced, the cost expenditure of equipment updating and checking maintenance cost is reduced, the safe, stable and long-period operation of the coal gasification device is ensured, and the water resource saving and wastewater resource utilization capacity of enterprises is steadily improved.
Drawings
FIG. 1 is a schematic flow diagram of a system for recycling nitrobenzene wastewater;
the marks in the figure:
1. a removal tower;
2. a first heat exchanger;
3. a cooler;
4. a separation tank;
5. an exhaust gas treatment unit;
6. a second heat exchanger;
7. and (5) grinding.
Detailed Description
For a better understanding of the present invention, the following examples are set forth to illustrate, but are not to be construed as limiting the invention.
Coal water slurries are typically composed of 60-70% coal, 30-40% water, and small amounts of additives. Because a large amount of water is needed for preparing the water-coal-slurry, nitrobenzene wastewater is adopted to replace conventional water to prepare the water-coal-slurry at present based on the resource utilization of wastewater, but the corrosion of the water-coal-slurry is increased in the actual production process due to the high salt content and complex components of the nitrobenzene wastewater, so that production equipment is corroded.
The nitrobenzene wastewater mainly refers to wastewater generated in the processes of alkali liquor neutralization, water washing and rectification of nitrobenzene crude products. The applicant finds that nitrite ions in nitrobenzene wastewater are the main cause of corrosion, and when the nitrite ion content in nitrobenzene wastewater is reduced, the corrosiveness of the water coal slurry technology on equipment is greatly reduced when the nitrobenzene wastewater is cooperatively treated. In the prior technical scheme, the applicant utilizes nitrite in iron and nitrobenzene wastewater to react, so that the nitrite ion content in the nitrobenzene wastewater can be reduced, and particularly when the nitrite content in the wastewater is reduced to less than or equal to 50 mug/g, the corrosion damage to equipment such as a mill and the like in the preparation process of the coal water slurry is greatly reduced.
As shown in fig. 1: a recycling treatment system for nitrobenzene wastewater comprises a removal tower 1, a first heat exchanger 2, a cooler 3, a separation tank 4, an exhaust gas treatment unit 5, a second heat exchanger 6 and a mill 7.
The removal tower 1 is provided with a supersaturated steam inlet and a wastewater inlet, nitrobenzene wastewater to be treated exchanges heat with materials extracted from the bottom of the removal tower 1 through the first heat exchanger 2, the nitrobenzene wastewater after temperature rise enters the removal tower 1 through the wastewater inlet, and the materials at the bottom after temperature reduction enter the mill 7 through the second heat exchanger 6.
The removal column 1 may be a general column with distribution pipes. The second heat exchanger exchanges heat between the material and the cooling water.
The nitrobenzene wastewater feeding pipe of the first heat exchanger 2 is connected with an acid injection unit, and the feeding pipe of the mill 7 is connected with an alkali injection unit.
The gas phase material at the top of the removal tower 1 enters a separation tank 4 after being cooled by a cooler 3, the gas phase material discharged from the separation tank 4 enters a waste gas treatment unit 5, and the discharged liquid phase material flows back into the removal tower 1.
The mill 7 is of the wet overflow type, it being foreseen that at least a rod mill may be chosen.
The nitrobenzene wastewater recycling treatment process is based on the treatment system, nitrobenzene wastewater to be treated enters a first heat exchanger to exchange heat with materials extracted from the bottom of a removal tower after pH value adjustment by acid injection, the nitrobenzene wastewater after heat exchange enters the removal tower, nitrite in the nitrobenzene wastewater is removed by heating of superheated steam in the removal tower, materials at the top of the removal tower sequentially enter a cooler and a separation tank, gas-phase materials separated by the separation tank enter a waste gas treatment unit, liquid-phase materials separated by the separation tank flow back to the upper part of the removal tower, materials at the bottom of the removal tower sequentially exchange heat by a first heat exchanger and a second heat exchanger, and the materials after heat exchange enter a mill after pH value adjustment by an alkali injection unit.
The nitrobenzene wastewater mainly refers to wastewater generated in the processes of alkali liquor neutralization, water washing and rectification of nitrobenzene crude products.
The materials at the bottom of the removal tower enter a mill after heat exchange and alkali injection, and the temperature is 50 ℃ after heat exchange.
The superheated steam of the removal tower has the first heating function and the second function of accelerating the gas phase carry-out.
The corrosion factor, i.e., nitrite, has a process control index of 50 μg/g or less, more preferably 40 μg/g or less.
The residence time of nitrobenzene wastewater in the removal tower is more than or equal to 15min, more preferably more than or equal to 10min.
And the nitrobenzene wastewater to be treated enters a first heat exchanger after pH value is regulated to be less than or equal to 3 by acid injection.
The acid used in the process of regulating the acid injection contains H + Preferably sulfuric acid.
The temperature of the nitrobenzene wastewater in the removal tower is not lower than 90 ℃.
And (3) regulating the pH value of the tower bottom material of the removal tower to 7-10 by alkali injection, and then entering the mill.
The alkali used in the alkali injection regulating process contains OH - Is an inorganic base of (a).
Further, the alkali is one or more of caustic soda flakes, quicklime or lime milk and a solution thereof.
When nitrobenzene wastewater is not used as coal slurry water, the core of nitrobenzene wastewater treatment technology (physical method, chemical method and biological method) is to remove nitrobenzene, so that the discharge of wastewater meets the environmental index requirement, and therefore, the nitrite content and whether corrosion influence exists are not considered. When nitrobenzene wastewater becomes coal slurry water, the problem of corrosion of mill equipment occurs, and the corrosion cause is nitrite which is first proposed after research, and then an iron reduction method (comparison document 2) is proposed to remove by a chemical method, but the chemical method has higher cost, so an acidification boiling method is proposed.
The acidification boiling method only aims at nitrous acid, and the method is the resource utilization of the wastewater, so that the corrosiveness of the wastewater is reduced, and other substances in the wastewater are not needed to be considered. The method is not applicable to all systems because of different starting angles, for example, whether decomposition, reaction and the like of the target product exist under the acidification condition is required to be considered, so that not only nitrite removal is required to be considered, but also reduction of the target product is required to be considered, and the situation that the target product is not lost is avoided. In addition, nitrite is a corrosion cause in the pulping process of the mill, the changing environment is not necessarily specific to a certain extent, in other words, the nitrite is a similar environment for determining the corrosion cause, and the nitrite has certain universality.
Nitrite is unstable and easily decomposed under acidic conditions, but requires time, and cannot be given enough time to slowly decompose in a practical continuous production process. Thus, it is known to those skilled in the art that nitrite is unstable and readily breaks down under acidic conditions, but is not readily achieved in production, and that acidification is not feasible in light of the considerations, in combination with other processes, such as boiling as set forth in this patent.
3HNO 2 ＝HNO 3 +2NO+H 2 O (acidification primary reaction), partial removal can be seen.
2HNO 2 ＝NO+NO 2 +H 2 O (acidification heating main reaction), all removal can be seen.
The heating and steaming out function is an enhancement of efficiency and practicality.
Example 1 ]
A nitrobenzene wastewater recycling treatment process comprises the following steps: regulating the pH value of nitrobenzene wastewater to be treated by acid injection to enable the pH value of the nitrobenzene wastewater to be 2, then enabling the nitrobenzene wastewater to enter a first heat exchanger to exchange heat with materials extracted from the bottom of a removal tower, enabling the nitrobenzene wastewater after heat exchange to enter the removal tower, removing nitrite in the nitrobenzene wastewater by utilizing superheated steam heating in the removal tower, and controlling the temperature of the bottom of the removal tower to be 100 ℃ and the removal time to be 30min (the retention time of the nitrobenzene wastewater in the removal tower);
the tower top material of the removal tower sequentially enters a cooler and a separating tank, the gas phase material separated by the separating tank enters a waste gas treatment unit, the liquid phase material separated by the separating tank flows back to the upper part of the removal tower, the tower bottom material of the removal tower sequentially exchanges heat through a first heat exchanger and a second heat exchanger, and the material after heat exchange enters a mill after the pH value is regulated (pH control index is 7-10) through an alkali injection unit.
Example 2 ]
A nitrobenzene wastewater recycling treatment process comprises the following steps: regulating the pH value of nitrobenzene wastewater to be treated by acid injection to enable the pH value of the nitrobenzene wastewater to be 3, then enabling the nitrobenzene wastewater to enter a first heat exchanger to exchange heat with materials extracted from the bottom of a removal tower, enabling the nitrobenzene wastewater after heat exchange to enter the removal tower, removing nitrite in the nitrobenzene wastewater by utilizing superheated steam heating in the removal tower, and controlling the temperature of the bottom of the removal tower to be 100 ℃ and the removal time to be 30min (the retention time of the nitrobenzene wastewater in the removal tower);
the tower top material of the removal tower sequentially enters a cooler and a separating tank, the gas phase material separated by the separating tank enters a waste gas treatment unit, the liquid phase material separated by the separating tank flows back to the upper part of the removal tower, the tower bottom material of the removal tower sequentially exchanges heat through a first heat exchanger and a second heat exchanger, and the material after heat exchange enters a mill after the pH value is regulated (pH control index is 7-10) through an alkali injection unit.
Example 3 ]
A nitrobenzene wastewater recycling treatment process comprises the following steps: the pH value of nitrobenzene wastewater to be treated is adjusted by acid injection, so that the pH value of the nitrobenzene wastewater is 3, the nitrobenzene wastewater enters a first heat exchanger to exchange heat with materials extracted from the bottom of a removal tower, the nitrobenzene wastewater after heat exchange enters the removal tower, nitrite in the nitrobenzene wastewater is removed by heating with superheated steam in the removal tower, the temperature of the bottom of the removal tower is required to be controlled at 90 ℃ for 30min (the retention time of the nitrobenzene wastewater in the removal tower);
the tower top material of the removal tower sequentially enters a cooler and a separating tank, the gas phase material separated by the separating tank enters a waste gas treatment unit, the liquid phase material separated by the separating tank flows back to the upper part of the removal tower, the tower bottom material of the removal tower sequentially exchanges heat through a first heat exchanger and a second heat exchanger, and the material after heat exchange enters a mill after the pH value is regulated (pH control index is 7-10) through an alkali injection unit.
Example 4 ]
A nitrobenzene wastewater recycling treatment process comprises the following steps: regulating the pH value of nitrobenzene wastewater to be treated by acid injection to enable the pH value of the nitrobenzene wastewater to be 3, then enabling the nitrobenzene wastewater to enter a first heat exchanger to exchange heat with materials extracted from the bottom of a removal tower, enabling the nitrobenzene wastewater after heat exchange to enter the removal tower, removing nitrite in the nitrobenzene wastewater by utilizing superheated steam heating in the removal tower, and controlling the temperature of the bottom of the removal tower to be 100 ℃ and the removal time to be 30min (the retention time of the nitrobenzene wastewater in the removal tower);
the tower top material of the removal tower sequentially enters a cooler and a separating tank, the gas phase material separated by the separating tank enters a waste gas treatment unit, the liquid phase material separated by the separating tank flows back to the upper part of the removal tower, the tower bottom material of the removal tower sequentially exchanges heat through a first heat exchanger and a second heat exchanger, and the material after heat exchange enters a mill after the pH value is regulated (pH control index is 7-10) through an alkali injection unit.
Example 5 ]
A nitrobenzene wastewater recycling treatment process comprises the following steps: the pH value of nitrobenzene wastewater to be treated is adjusted by acid injection, so that the pH value of the nitrobenzene wastewater is 3, the nitrobenzene wastewater enters a first heat exchanger to exchange heat with materials extracted from the bottom of a removal tower, the nitrobenzene wastewater after heat exchange enters the removal tower, nitrite in the nitrobenzene wastewater is removed by heating with superheated steam in the removal tower, the temperature of the bottom of the removal tower is required to be controlled at 100 ℃ and the removal time is required to be 10min (the retention time of the nitrobenzene wastewater in the removal tower);
the tower top material of the removal tower sequentially enters a cooler and a separating tank, the gas phase material separated by the separating tank enters a waste gas treatment unit, the liquid phase material separated by the separating tank flows back to the upper part of the removal tower, the tower bottom material of the removal tower sequentially exchanges heat through a first heat exchanger and a second heat exchanger, and the material after heat exchange enters a mill after the pH value is regulated (pH control index is 7-10) through an alkali injection unit.
Example 6 ]
A nitrobenzene wastewater recycling treatment process comprises the following steps: the pH value of nitrobenzene wastewater to be treated is adjusted by acid injection, so that the pH value of the nitrobenzene wastewater is 3, the nitrobenzene wastewater enters a first heat exchanger to exchange heat with materials extracted from the bottom of a removal tower, the nitrobenzene wastewater after heat exchange enters the removal tower, nitrite in the nitrobenzene wastewater is removed by heating with superheated steam in the removal tower, the temperature of the bottom of the removal tower is required to be controlled at 100 ℃ and the removal time is required to be 15min (the retention time of the nitrobenzene wastewater in the removal tower);
the tower top material of the removal tower sequentially enters a cooler and a separating tank, the gas phase material separated by the separating tank enters a waste gas treatment unit, the liquid phase material separated by the separating tank flows back to the upper part of the removal tower, the tower bottom material of the removal tower sequentially exchanges heat through a first heat exchanger and a second heat exchanger, and the material after heat exchange enters a mill after the pH value is regulated (pH control index is 7-10) through an alkali injection unit.
Example 7 ]
A nitrobenzene wastewater recycling treatment process comprises the following steps: regulating the pH value of nitrobenzene wastewater to be treated by acid injection to enable the pH value of the nitrobenzene wastewater to be 3, then enabling the nitrobenzene wastewater to enter a first heat exchanger to exchange heat with materials extracted from the bottom of a removal tower, enabling the nitrobenzene wastewater after heat exchange to enter the removal tower, removing nitrite in the nitrobenzene wastewater by utilizing superheated steam heating in the removal tower, and controlling the temperature of the bottom of the removal tower to be 100 ℃ and the removal time to be 20min (the retention time of the nitrobenzene wastewater in the removal tower);
the tower top material of the removal tower sequentially enters a cooler and a separating tank, the gas phase material separated by the separating tank enters a waste gas treatment unit, the liquid phase material separated by the separating tank flows back to the upper part of the removal tower, the tower bottom material of the removal tower sequentially exchanges heat through a first heat exchanger and a second heat exchanger, and the material after heat exchange enters a mill after the pH value is regulated (pH control index is 7-10) through an alkali injection unit.
Example 8 ]
A nitrobenzene wastewater recycling treatment process comprises the following steps: regulating the pH value of nitrobenzene wastewater to be treated by acid injection to enable the pH value of the nitrobenzene wastewater to be 3, then enabling the nitrobenzene wastewater to enter a first heat exchanger to exchange heat with materials extracted from the bottom of a removal tower, enabling the nitrobenzene wastewater after heat exchange to enter the removal tower, removing nitrite in the nitrobenzene wastewater by utilizing superheated steam heating in the removal tower, and controlling the temperature of the bottom of the removal tower to be 100 ℃ and the removal time to be 30min (the retention time of the nitrobenzene wastewater in the removal tower);
the tower top material of the removal tower sequentially enters a cooler and a separating tank, the gas phase material separated by the separating tank enters a waste gas treatment unit, the liquid phase material separated by the separating tank flows back to the upper part of the removal tower, the tower bottom material of the removal tower sequentially exchanges heat through a first heat exchanger and a second heat exchanger, and the material after heat exchange enters a mill after the pH value is regulated (pH control index is 7-10) through an alkali injection unit.
Comparative examples 1 to 3
The treatment process of comparative examples 1 to 3 was substantially the same as that of < example 1> except that: the pH values of the nitrobenzene wastewater in comparative examples 1-3 were 4, 5 and 6, respectively, after acid injection adjustment.
Comparative examples 4 to 6 ]
The treatment process of comparative examples 4 to 6 was substantially the same as that of < example 3> except that: the bottom temperatures of the removal columns in comparative examples 4 to 6 were controlled at 60℃at 70℃and 80 ℃.
Comparative example 7 ]
The treatment process of comparative example 7 was substantially the same as that of < example 5> except that: the treatment time of the removal column in comparative example 7 was 5min.
The pretreatment wastewater of < examples 1, 2> and < comparative examples 1-3> was tested, and the sulfite content data obtained are shown in the following table:
| group of | Nitrite concentration (μg/g) |
| Untreated waste water | 400 |
| Example 1 (ph=2) | 35 |
| Example 2 (ph=3) | 48 |
| Comparative example 1 (ph=4) | 303 |
| Comparative example 2 (ph=5) | 323 |
| Comparative example 3 (ph=6) | 327 |
As can be seen from the table above: when the pH value of the nitrobenzene wastewater is less than or equal to 3 through acidification treatment, the removal effect of the sulfite is better. When the pH value of the nitrobenzene wastewater after acidification is more than 3, the removal effect of the sulfite is obviously poor, so that the pH value needs to be limited to be within 3 when the nitrobenzene wastewater is acidified.
The pretreatment wastewater of < examples 3, 4> and < comparative examples 4-6> was tested, and the sulfite content data obtained are shown in the following table:
| group of | Nitrite concentration (μg/g)) |
| Untreated waste water | 400 |
| Example 3 (90 ℃ C.) | 50 |
| Example 4 (100 ℃ C.) | 40 |
| Comparative example 4 (60 ℃ C.) | 174.9 |
| Comparative example 5 (70 ℃ C.) | 172.6 |
| Comparative example 6 (80 ℃ C.) | 150.6 |
As can be seen from the table above: when the temperature of the nitrobenzene wastewater is more than or equal to 90 ℃ in the heating and steaming-out process, the removal effect of the sulfite is better. When the temperature of the nitrobenzene waste water is lower than 90 ℃ in the heating and steaming process, the removal effect of the sulfite is obviously deteriorated, so that the temperature of the nitrobenzene waste water needs to be controlled to be higher than 90 ℃ in the heating and steaming process of the nitrobenzene waste water.
The pretreatment wastewater of < examples 5-8> and < comparative example 7> was tested, and the sulfite content data obtained are shown in the following table:
| group of | Nitrite concentration (μg/g) |
| Untreated waste water | 415 |
| Example 5 (10 min) | 48.1 |
| Example 6 (15 min) | 35.4 |
| Example 7 (20 min) | 32.1 |
| Example 8 (30 min) | 31.8 |
| Comparative example 7 (5 min) | 128 |
As can be seen from the table above: when the heating and steaming-out duration of nitrobenzene wastewater exceeds 10min, the removal effect of the sulfite is better. When the heating and steaming duration of nitrobenzene wastewater is less than 5min, the removal effect of sulfite is obviously deteriorated, so that the removal time is not less than 10min in the heating and steaming process of nitrobenzene wastewater.
The nitrobenzene wastewater recycling treatment process has the advantages that:
1) The process further widens the utilization path of the nitrobenzene wastewater by eliminating the corrosiveness of the nitrobenzene wastewater;
2) The corrosion problem of coal slurry equipment can be effectively solved or slowed down, the risk of unplanned shutdown is reduced, and the maintenance cost is reduced;
3) The process ensures the continuous use of nitrobenzene wastewater, and is favorable for steadily improving the water-saving efficiency of enterprises.
4) The process has the advantages of high efficiency, easy implementation and low cost, and is suitable for the problem of limited use of the wastewater caused by other same corrosion reasons.
The foregoing describes specific embodiments of the present invention. It is to be understood that the invention is not limited to the particular embodiments described above, and that various changes and modifications may be made by one skilled in the art within the scope of the claims without affecting the spirit of the invention.
Claims (10)
1. A nitrobenzene wastewater recycling treatment system is characterized in that: comprises a removal tower (1), a first heat exchanger (2), a cooler (3), a separation tank (4), an exhaust gas treatment unit (5), a second heat exchanger (6) and a mill (7);
the removing tower (1) is provided with a supersaturated steam inlet and a wastewater inlet, nitrobenzene wastewater to be treated exchanges heat with materials extracted from the tower bottom of the removing tower (1) through the first heat exchanger (2), the nitrobenzene wastewater after temperature rise enters the removing tower (1) through the wastewater inlet, and the tower bottom materials after temperature reduction enter the mill (7) through the second heat exchanger (6);
an acid injection unit is connected to a nitrobenzene wastewater feed pipe of the first heat exchanger (2), and an alkali injection unit is connected to a feed pipe of the mill (7);
the gas phase material at the top of the removal tower (1) enters a separation tank (4) after being cooled by a cooler (3), the gas phase material discharged from the separation tank (4) enters a waste gas treatment unit (5), and the discharged liquid phase material flows back into the removal tower (1).
2. The recycling treatment system of nitrobenzene wastewater according to claim 1, which is characterized in that: the mill (7) is a wet overflow mill (7), preferably a rod mill.
3. A recycling treatment process of nitrobenzene wastewater is characterized in that: the method is based on the processing system of claim 1 or 2, in particular: the method comprises the steps that nitrobenzene wastewater to be treated enters a first heat exchanger to exchange heat with materials extracted from the bottom of a removal tower after pH value adjustment through acid injection, the nitrobenzene wastewater after heat exchange enters the removal tower, nitrite in the nitrobenzene wastewater is removed by utilizing superheated steam heating in the removal tower, the materials at the top of the removal tower sequentially enter a cooler and a separating tank, gas-phase materials separated by the separating tank enter a waste gas treatment unit, liquid-phase materials separated by the separating tank flow back to the upper part of the removal tower, the materials at the bottom of the removal tower sequentially exchange heat through the first heat exchanger and a second heat exchanger, and the materials after heat exchange enter a mill after pH value adjustment through an alkali injection unit.
4. The recycling process of nitrobenzene wastewater, which is characterized in that: and the nitrobenzene wastewater to be treated enters a first heat exchanger after pH value is regulated to be less than or equal to 3 by acid injection.
5. The recycling process of nitrobenzene wastewater, which is characterized in that: the acid used in the process of regulating the acid injection contains H + Preferably sulfuric acid.
6. The recycling process of nitrobenzene wastewater, which is characterized in that: the temperature of nitrobenzene wastewater in the removal tower is not lower than 90 ℃.
7. The recycling process of nitrobenzene wastewater, which is characterized in that: the residence time of the nitrobenzene wastewater in the removal tower is more than or equal to 10min, preferably more than or equal to 15min.
8. The recycling process of nitrobenzene wastewater, which is characterized in that: and (3) regulating the pH value of the tower bottom material of the removal tower to 7-10 by alkali injection, and then entering the mill.
9. The recycling process of nitrobenzene wastewater, which is characterized in that: the alkali used in the alkali injection regulating process contains OH - Is an inorganic base of (a).
10. The recycling process of nitrobenzene wastewater, which is characterized in that: the alkali used in the alkali injection regulating process is one or more of caustic soda flakes, quicklime or lime milk and a solution thereof.
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