CN110563069B - Comprehensive utilization method of nitrobenzene tar and aniline wastewater - Google Patents
Comprehensive utilization method of nitrobenzene tar and aniline wastewater Download PDFInfo
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- B01D3/00—Distillation or related exchange processes in which liquids are contacted with gaseous media, e.g. stripping
- B01D3/001—Processes specially adapted for distillation or rectification of fermented solutions
- B01D3/002—Processes specially adapted for distillation or rectification of fermented solutions by continuous methods
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- B01D3/14—Fractional distillation or use of a fractionation or rectification column
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- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
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- C02F1/26—Treatment of water, waste water, or sewage by extraction
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Abstract
The invention discloses a method for comprehensively utilizing nitrobenzene tar and aniline wastewater. The method takes nitrobenzene tar oil as an extracting agent to extract aniline in aniline wastewater, and simultaneously uses the aniline wastewater to wash the nitrobenzene tar oil to remove phenate in the tar oil; the concentration of aniline in the extracted waste water is less than 100mg/L and is used for nitrobenzene neutralization and water washing, and the concentration of nitrophenol in the tar is less than 2mg/L and is used for refining and recycling nitrobenzene. The invention has simple operation, low investment and operation cost and obvious economic value.
Description
Technical Field
The invention relates to a method for comprehensively utilizing nitrobenzene tar and aniline wastewater, in particular to a method for recycling wastes by utilizing byproducts in the production of nitrobenzene tar and aniline wastewater so as to reduce the production cost.
Background
Aniline is an important organic chemical raw material and chemical product, and is mainly used for producing MDI, rubber auxiliaries, medicines, dyes, pigments, intermediates and the like.
At present, the main production route of aniline is to prepare nitrobenzene by benzene nitration and then prepare aniline by nitrobenzene hydrogenation, and a large amount of three wastes which are difficult to treat are generated in the whole production process.
Firstly, in the production process of nitrobenzene, trace nitrophenol and salts thereof enter a rectification process along with crude nitrobenzene, the nitrophenol is discharged along with tar in a rectification tower, and phenate scales in heater tubes, pipelines and tower walls of the rectification tower, so that the heater tubes and connecting pipelines are blocked to form explosion hidden dangers in serious cases. At the present stage, the nitrobenzene tar is mainly used as solid waste and sent to qualified treatment factories for incineration treatment, and the treatment cost of each ton of nitrobenzene tar is about 4000-5000 yuan. The nitrobenzene content in the nitrobenzene tar accounts for about 90 percent, and the nitrobenzene tar is directly used as solid waste to be treated, so that the resource waste is greatly increased.
Secondly, oil-water separation is carried out on aniline and water generated after nitrobenzene hydrogenation, the separated water contains a certain amount of aniline, the mass percentage of the aniline in the water is about 3%, currently, steam stripping treatment is mainly adopted, the aniline is concentrated after steam stripping, and then the aniline is recovered after purification; the aniline content in the waste water after steam stripping is reduced to below 1000mg/L, and then biochemical treatment is carried out. The method consumes 1 ton of steam per ton of waste water steam stripping, has high energy consumption for waste water treatment, and has large difficulty in biochemical treatment of high-concentration aniline waste water.
Patent CN1600696A discloses a method for treating aniline wastewater by a nitrobenzene extraction method, wherein nitrobenzene used as a raw material for producing aniline is selected as an extracting agent. After the aniline wastewater is subjected to nitrobenzene extraction treatment, the obtained extract phase is nitrobenzene containing aniline, which can be used as a raw material for producing aniline, and the extract phase is wastewater containing a small amount of nitrobenzene, and the obtained raffinate phase can be used as crude nitrobenzene alkaline washing water in nitrobenzene production.
Patent CN101759244A discloses a method for treating wastewater from aniline production by nitrobenzene hydrogenation, in which aniline water and aniline in aniline synthesis process are separated, the aniline water is sent to an extraction tower, crude nitrobenzene is used to extract aniline in wastewater in the extraction tower, the obtained extract phase is nitrobenzene containing aniline, and the obtained material is sent to a vaporizer as raw material for aniline synthesis. The raffinate phase is wastewater containing nitrobenzene and aniline, and the wastewater can be used as water for a crude nitrobenzene alkaline washing section.
The prior patents all mention that nitrobenzene is used as an extracting agent to extract aniline in aniline wastewater, and because the aniline wastewater also contains a small amount of light components besides aniline, the extracted nitrobenzene also brings the light components in the wastewater into nitrobenzene, and the direct hydrogenation for preparing aniline can increase reaction byproducts on one hand and increase load of an aniline refining system on the other hand, and even leads low-boiling-point substances in aniline products to exceed the standard, thereby leading the quality of the aniline products to be reduced or unqualified.
On the basis of the defects of the prior art, the invention provides the comprehensive utilization of the nitrobenzene tar and aniline wastewater which are difficult to treat, and realizes the comprehensive utilization of the nitrobenzene tar and aniline wastewater.
Disclosure of Invention
Aiming at the problem of treatment of nitrobenzene tar and aniline wastewater generated in the existing nitrobenzene and aniline production, the invention aims to provide a method for extracting aniline in aniline wastewater by using nitrobenzene in nitrobenzene tar, and simultaneously washing the aniline wastewater to remove inorganic salt in the nitrobenzene tar, so that nitrobenzene in the nitrobenzene tar can be recycled by using the existing refining system, and the comprehensive utilization of the nitrobenzene tar and the aniline wastewater is realized.
The technical scheme adopted by the invention is as follows: the comprehensive utilization method of the nitrobenzene tar and aniline wastewater is characterized by comprising the following steps: mixing nitrobenzene tar as an extracting agent with aniline wastewater for extraction, extracting aniline in the aniline wastewater by using the nitrobenzene tar, and washing the aniline wastewater to remove inorganic salts in the nitrobenzene tar; the aniline wastewater after extraction is used for nitrobenzene neutralization and washing, and nitrobenzene tar after washing is dehydrated through a coalescence separator and then enters a nitrobenzene refining system to recover nitrobenzene.
The main components of the nitrobenzene tar comprise nitrobenzene, dinitrobenzene and inorganic salt, wherein the inorganic salt is phenolate and sodium salt, and the mass content of the nitrobenzene is more than 80%.
The aniline wastewater is obtained by oil-water separation of a nitrobenzene hydrogenation product, and the mass percentage of aniline in the wastewater is 1-3%.
The extraction process is countercurrent extraction, the number of countercurrent extraction stages is 1-4, and the oil-water ratio of extraction is 0.5-3: 1.
In the extraction process, the concentration of aniline in the extracted wastewater is controlled to be less than 100mg/L through the oil-water ratio and the extraction stage number.
The concentration of nitrophenol in the extracted tar is controlled to be less than 10mg/L through the oil-water ratio and the extraction stage number in the extraction process.
The concentration of nitrophenol in the washed nitrobenzene tar is less than 2mg/L after the nitrobenzene tar is further dehydrated by a coalescence separator.
The coalescence separator adopts a fiber filter element separator, a special plate group separator or a combined separator.
The nitrobenzene refining system comprises a nitrobenzene primary distillation tower and a rectifying tower, wherein the operating conditions of the primary distillation tower are as follows: the tower top temperature is 90-110 ℃, the tower kettle temperature is 165 +/-2 ℃, the tower top vacuum degree is 0.068-0.072 MPa, and the rectifying tower operation conditions are as follows: the temperature of the top of the tower is 100-120 ℃, the temperature of the bottom of the tower is less than or equal to 128 ℃, and the vacuum degree of the top of the tower is more than or equal to 0.094 MPa.
Compared with the prior art, the invention has the characteristics that: (1) the phenate in the nitrobenzene tar is reduced by washing, and then is further removed by dewatering through a coalescence separator, so that the influence of the phenate on a refining system is reduced, and the nitrobenzene in the nitrobenzene tar can be recycled; (2) after the aniline wastewater is extracted, the concentration of aniline is less than 100mg/L, so that the stripping energy consumption of the aniline wastewater is reduced; (3) the technology adopts the prior device to realize the comprehensive utilization of the nitrobenzene tar and the aniline wastewater, and does not influence the quality of aniline products. (4) The method has the advantages that 50% of nitrobenzene is recovered from each ton of nitrobenzene tar, the sale price of the nitrobenzene is 7000 yuan/ton, and the treatment cost of the nitrobenzene tar is 5000 yuan/ton.
Detailed Description
The following examples further illustrate the essential features and the significant effects of the present invention, but do not limit the contents of the present invention.
The following example operational procedure: the method comprises the steps of carrying out countercurrent mixed extraction on nitrobenzene tar and aniline wastewater according to a certain proportion, using the aniline concentration in the extracted aniline wastewater to be less than 100mg/L for nitrobenzene neutralization and washing, carrying out oil-water separation on the extracted nitrobenzene tar through a coalescence separator, further removing phenate through removing water in the nitrobenzene tar, then enabling the nitrobenzene tar to enter a nitrobenzene refining system, removing water and light components at the top of a primary distillation tower, and enabling materials at the bottom of the tower to enter a rectifying tower to recover nitrobenzene. Operating conditions of the preliminary distillation tower: the tower top temperature is 90-110 ℃, the tower kettle temperature is 165 +/-2 ℃, the tower top vacuum degree is 0.068-0.072 MPa, and the rectifying tower operation conditions are as follows: the temperature of the top of the tower is 100-120 ℃, the temperature of the bottom of the tower is less than or equal to 128 ℃, and the vacuum degree of the top of the tower is more than or equal to 0.094 MPa.
Example 1
Nitrobenzene tar with the mass content of nitrobenzene of 90 percent is taken as an extracting agent, wherein the concentration of nitrophenol is 255mg/L, and the nitrobenzene tar is mixed with aniline wastewater with the mass percentage content of 2.5 percent, and continuous 2-stage countercurrent extraction is carried out according to the oil-water ratio of 1: 1.
The concentration of aniline in the extracted wastewater is 67mg/L, the concentration of nitrophenol in the tar after washing is 8.2mg/L, and the concentration of nitrophenol in the tar is 1.1mg/L after passing through a coalescence separator with a fiber filter core as a filler. And (3) after extraction, the nitrobenzene tar passes through a primary distillation tower and a rectifying tower and then is hydrogenated to prepare aniline, wherein the operating conditions of the primary distillation tower are as follows: the tower top temperature is 92 ℃, the tower kettle temperature is 165 ℃, the tower top vacuum degree is 0.068MPa, and the rectifying tower operation conditions are as follows: the temperature at the top of the tower is 105 ℃, the temperature at the bottom of the tower is 125 ℃, and the vacuum degree at the top of the tower is 0.094 MPa. The mass fraction of the aniline product is 99.90 percent, the mass fraction of the low-boiling-point substance is 0.002 percent, and the quality of the aniline product reaches the standard of a superior product.
Comparative example 1
Nitrobenzene is used as an extracting agent and is mixed with aniline wastewater with the mass percentage of 2.5 percent, and continuous 2-stage countercurrent extraction is carried out according to the oil-water ratio of 1: 1. And (3) directly hydrogenating the extracted nitrobenzene to prepare aniline, wherein the mass fraction of the aniline product is 99.62%, the mass fraction of low-boiling-point substances is 0.018%, and the quality of the aniline product is unqualified due to the excessive low-boiling-point substances.
Example 2
Nitrobenzene tar with the mass content of nitrobenzene of 84 percent is taken as an extracting agent, wherein the concentration of nitrophenol is 185mg/L, and the nitrobenzene tar is mixed with aniline wastewater with the mass percentage content of 2.8 percent, and continuous 4-stage countercurrent extraction is carried out according to the oil-water ratio of 1: 1.
The concentration of aniline in the extracted waste water is 50mg/L, the concentration of nitrophenol in the tar after washing is 7.2mg/L, and the concentration of nitrophenol in the tar is 0.8mg/L after passing through a coalescence separator with a special plate group as a filler. And (3) after extraction, the nitrobenzene tar passes through a primary distillation tower and a rectifying tower and then is hydrogenated to prepare aniline, wherein the operating conditions of the primary distillation tower are as follows: 95 ℃, the temperature of a tower kettle is 163 ℃, the vacuum degree of a tower top is 0.070MPa, and the operating conditions of a rectifying tower are as follows: the temperature at the top of the tower is 110 ℃, the temperature at the bottom of the tower is 128 ℃, and the vacuum degree at the top of the tower is 0.083 MPa. 99.85 percent of aniline product, 0.005 percent of low-boiling-point substance and the quality of aniline product reaching the high-grade standard.
Comparative example 2
Nitrobenzene is used as an extracting agent and is mixed with aniline wastewater with the mass percentage of 2.8 percent, and continuous 4-stage countercurrent extraction is carried out according to the oil-water ratio of 1: 1. The nitrobenzene is directly hydrogenated to prepare the aniline after extraction, the mass fraction of the aniline product is 99.52 percent, the mass fraction of the low-boiling-point substance is 0.012 percent, and the quality of the aniline product only reaches the standard of qualified products.
Example 3
Nitrobenzene tar with the mass content of nitrobenzene of 80 percent is taken as an extracting agent, wherein the concentration of nitrophenol is 150mg/L, and the nitrobenzene tar is mixed with aniline wastewater with the mass percentage content of 2.1 percent, and continuous 2-stage countercurrent extraction is carried out according to the oil-water ratio of 3: 1.
The concentration of aniline in the extracted wastewater is 36mg/L, the concentration of nitrophenol in the tar after washing is 6.5mg/L, and the concentration of nitrophenol in the tar is 0.5mg/L after passing through a coalescence separator of a fiber filter core and a special plate group combined filler. And (3) after extraction, the nitrobenzene tar passes through a primary distillation tower and a rectifying tower and then is hydrogenated to prepare aniline, wherein the operating conditions of the primary distillation tower are as follows: 100 ℃, the temperature of a tower kettle is 167 ℃, the vacuum degree of a tower top is 0.070MPa, and the operating conditions of a rectifying tower are as follows: the temperature at the top of the tower is 120 ℃, the temperature at the bottom of the tower is 128 ℃, and the vacuum degree at the top of the tower is 0.083 MPa. The mass fraction of the aniline product is 99.91 percent, the mass fraction of the low-boiling-point substance is 0.007 percent, and the quality of the aniline product reaches the standard of a high-grade product.
Comparative example 3
Nitrobenzene is used as an extracting agent and is mixed with aniline wastewater with the mass percentage of 2.1 percent, and continuous 2-stage countercurrent extraction is carried out according to the oil-water ratio of 3: 1. The nitrobenzene is directly hydrogenated to prepare the aniline after extraction, the mass fraction of the aniline product is 99.59 percent, the mass fraction of the low-boiling-point substance is 0.012 percent, and the quality of the aniline product only reaches the standard of qualified products.
Example 4
Nitrobenzene tar with the mass content of nitrobenzene of 92 percent is used as an extracting agent, wherein the concentration of nitrophenol is 280mg/L, and the nitrobenzene tar is mixed with aniline wastewater with the mass percentage content of 1.5 percent, and continuous 1-level countercurrent extraction is carried out according to the oil-water ratio of 0.5: 1.
The concentration of aniline in the extracted wastewater is 86mg/L, the concentration of nitrophenol in the tar after water washing is 8.9mg/L, and the concentration of nitrophenol in the tar is 1.6mg/L after passing through a coalescence separator with a fiber filter core as a filler. And (3) after extraction, the nitrobenzene tar passes through a primary distillation tower and a rectifying tower and then is hydrogenated to prepare aniline, wherein the operating conditions of the primary distillation tower are as follows: the tower top temperature is 105 ℃, the tower kettle temperature is 165 ℃, the tower top vacuum degree is 0.07 MPa, and the operating conditions of the rectifying tower are as follows: the temperature at the top of the tower is 120 ℃, the temperature at the bottom of the tower is 128 ℃, and the vacuum degree at the top of the tower is 0.094 MPa. The mass fraction of the aniline product is 99.90 percent, the mass fraction of the low-boiling-point substance is 0.004 percent, and the quality of the aniline product reaches the standard of a superior product.
Comparative example 4
Nitrobenzene is used as an extracting agent and is mixed with aniline wastewater with the mass percentage of 1.5 percent, and continuous 1-level countercurrent extraction is carried out according to the oil-water ratio of 0.5: 1. The nitrobenzene is directly hydrogenated to prepare the aniline after extraction, the mass fraction of the aniline product is 99.65 percent, the mass fraction of the low-boiling-point substance is 0.015 percent, and the quality of the aniline product only reaches the standard of qualified products.
Example 5
Nitrobenzene tar with the mass content of nitrobenzene of 85 percent is taken as an extracting agent, wherein the concentration of nitrophenol is 204mg/L, and the nitrobenzene tar is mixed with aniline wastewater with the mass percentage content of 2.2 percent, and continuous 3-level countercurrent extraction is carried out according to the oil-water ratio of 2: 1.
The concentration of aniline in the extracted waste water is 63mg/L, the concentration of nitrophenol in the tar after washing is 8.4mg/L, and the concentration of nitrophenol in the tar is 1.2mg/L after passing through a coalescence separator with a special plate group as a filler. And (3) after extraction, the nitrobenzene tar passes through a primary distillation tower and a rectifying tower and then is hydrogenated to prepare aniline, wherein the operating conditions of the primary distillation tower are as follows: the tower top temperature is 105 ℃, the tower kettle temperature is 164 ℃, the tower top vacuum degree is 0.072 MPa, and the rectifying tower operation conditions are as follows: the temperature at the top of the tower is 112 ℃, the temperature at the bottom of the tower is 100 ℃, and the vacuum degree at the top of the tower is more than or equal to 0.01 MPa. 99.89 percent of aniline product, 0.005 percent of low-boiling-point substance and the quality of aniline product reaching the high-grade standard.
Comparative example 5
Nitrobenzene is used as an extracting agent and is mixed with aniline wastewater with the mass percentage of 2.2 percent, and continuous 3-stage countercurrent extraction is carried out according to the oil-water ratio of 2: 1. And (3) directly hydrogenating the extracted nitrobenzene to prepare the aniline, wherein the mass fraction of the aniline product is 99.69%, the mass fraction of low-boiling-point substances is 0.016%, and the quality of the aniline product is unqualified due to the excessive low-boiling-point substances.
Example 6
Nitrobenzene tar with the mass content of nitrobenzene of 80 percent is taken as an extracting agent, wherein the concentration of nitrophenol is 198mg/L, and the nitrobenzene tar is mixed with aniline wastewater with the mass percentage content of 3.0 percent, and continuous 3-level countercurrent extraction is carried out according to the oil-water ratio of 3: 1.
The concentration of aniline in the extracted wastewater is 72mg/L, the concentration of nitrophenol in the tar after water washing is 7.3mg/L, and the concentration of nitrophenol in the tar is 0.9mg/L after passing through a coalescence separator with a fiber filter core as a filler. And (3) after extraction, the nitrobenzene tar passes through a primary distillation tower and a rectifying tower and then is hydrogenated to prepare aniline, wherein the operating conditions of the primary distillation tower are as follows: the tower top temperature is 98 ℃, the tower kettle temperature is 165 ℃, the tower top vacuum degree is 0.068MPa, and the rectifying tower operation conditions are as follows: the temperature at the top of the tower is 115 ℃, the temperature at the bottom of the tower is 118 ℃, and the vacuum degree at the top of the tower is 0.098 MPa. The mass fraction of the aniline product is 99.91 percent, the mass fraction of the low-boiling-point substance is 0.003 percent, and the quality of the aniline product reaches the standard of a high-grade product.
Comparative example 6
Nitrobenzene is used as an extracting agent and is mixed with aniline wastewater with the mass percentage of 3.0 percent, and continuous 3-stage countercurrent extraction is carried out according to the oil-water ratio of 3: 1. The nitrobenzene is directly hydrogenated to prepare the aniline after extraction, the mass fraction of the aniline product is 99.75 percent, the mass fraction of the low-boiling-point substance is 0.013 percent, and the quality of the aniline product only reaches the standard of qualified products.
Example 7
Nitrobenzene tar with the mass content of nitrobenzene of 87 percent is taken as an extracting agent, wherein the concentration of nitrophenol is 266mg/L, and the nitrobenzene tar is mixed with aniline wastewater with the mass percentage content of 1.4 percent, and continuous 2-stage countercurrent extraction is carried out according to the oil-water ratio of 1.5: 1.
The concentration of aniline in the extracted waste water is 66mg/L, the concentration of nitrophenol in the tar after washing is 8.0mg/L, and the concentration of nitrophenol in the tar is 1.2mg/L after passing through a coalescence separator with a special plate group as a filler. And (3) after extraction, the nitrobenzene tar passes through a primary distillation tower and a rectifying tower and then is hydrogenated to prepare aniline, wherein the operating conditions of the primary distillation tower are as follows: the tower top temperature is 110 ℃, the tower kettle temperature is 165 ℃, the tower top vacuum degree is 0.068MPa, and the rectifying tower operation conditions are as follows: the temperature at the top of the tower is 100 ℃, the temperature at the bottom of the tower is 128 ℃, and the vacuum degree at the top of the tower is 0.094 MPa. 99.88 percent of aniline product and 0.005 percent of low-boiling-point substance, and the quality of the aniline product reaches the high-grade standard.
Comparative example 7
Nitrobenzene is used as an extracting agent and is mixed with aniline wastewater with the mass percentage of 1.4 percent, and continuous 2-stage countercurrent extraction is carried out according to the oil-water ratio of 1.5: 1. The nitrobenzene is directly hydrogenated to prepare the aniline after extraction, the mass fraction of the aniline product is 99.55 percent, the mass fraction of the low-boiling-point substance is 0.016 percent, and the quality of the aniline product with the low-boiling-point substance exceeding the standard is unqualified.
Example 8
Nitrobenzene tar with the mass content of nitrobenzene of 90 percent is taken as an extracting agent, wherein the concentration of nitrophenol is 179mg/L, and the nitrobenzene tar is mixed with aniline wastewater with the mass percentage content of 2.3 percent, and continuous 2-stage countercurrent extraction is carried out according to the oil-water ratio of 2: 1.
The concentration of aniline in the extracted wastewater is 58mg/L, the concentration of nitrophenol in the tar after water washing is 6.0mg/L, and the concentration of nitrophenol in the tar is 0.6mg/L after passing through a coalescence separator with a fiber filter core as a filler. And (3) after extraction, the nitrobenzene tar passes through a primary distillation tower and a rectifying tower and then is hydrogenated to prepare aniline, wherein the operating conditions of the primary distillation tower are as follows: the tower top temperature is 110 ℃, the tower kettle temperature is 165 ℃, the tower top vacuum degree is 0.068MPa, and the rectifying tower operation conditions are as follows: the temperature at the top of the tower is 100 ℃, the temperature at the bottom of the tower is 128 ℃, and the vacuum degree at the top of the tower is 0.094 MPa. The mass fraction of aniline product is 99.92%, the mass fraction of low-boiling-point substance is 0.002%, and the quality of aniline product with low-boiling-point substance exceeding standard can reach the standard of superior grade.
Comparative example 8
Nitrobenzene is used as an extracting agent and is mixed with aniline wastewater with the mass percentage of 2.3 percent, and continuous 2-stage countercurrent extraction is carried out according to the oil-water ratio of 2: 1. The nitrobenzene is directly hydrogenated to prepare the aniline after extraction, the mass fraction of the aniline product is 99.58 percent, the mass fraction of the low-boiling-point substance is 0.017 percent, and the quality of the aniline product is unqualified.
Claims (9)
1. A method for comprehensively utilizing nitrobenzene tar and aniline wastewater is characterized by comprising the following steps: mixing nitrobenzene tar as an extracting agent with aniline wastewater for extraction, extracting aniline in the aniline wastewater by using the nitrobenzene tar, and washing the aniline wastewater to remove inorganic salts in the nitrobenzene tar; the aniline wastewater after extraction is used for nitrobenzene neutralization and washing, and nitrobenzene tar after washing is dehydrated through a coalescence separator and then enters a nitrobenzene refining system to recover nitrobenzene.
2. The method for comprehensively utilizing the nitrobenzene tar and the aniline wastewater according to claim 1, wherein the nitrobenzene tar mainly comprises nitrobenzene, dinitrobenzene and inorganic salts, wherein the inorganic salts are phenolate and sodium salts, and the mass content of nitrobenzene is more than 80%.
3. The method for comprehensively utilizing the nitrobenzene tar and the aniline wastewater according to claim 1, wherein the aniline wastewater is obtained by oil-water separation of a nitrobenzene hydrogenation product, and the mass percentage of aniline in the wastewater is 1-3%.
4. The method for comprehensively utilizing the nitrobenzene tar and the aniline wastewater according to claim 1, wherein the extraction process is countercurrent extraction, the number of countercurrent extraction stages is 1-4, and the oil-water ratio of extraction is 0.5-3: 1.
5. The method for comprehensively utilizing the nitrobenzene tar and the aniline wastewater according to claim 1 or 4, characterized in that the concentration of the aniline in the extracted wastewater is controlled to be less than 100mg/L by the oil-water ratio and the extraction stages in the extraction process.
6. The method for comprehensively utilizing the nitrobenzene tar and the aniline wastewater according to claim 1 or 4, characterized in that the concentration of nitrophenol in the extracted tar is controlled to be less than 10mg/L by the oil-water ratio and the number of extraction stages in the extraction process.
7. The method for comprehensive utilization of nitrobenzene tar and aniline waste water according to claim 1, wherein the concentration of nitrophenol in the washed nitrobenzene tar is less than 2mg/L after further dehydration by a coalescer.
8. The method for comprehensive utilization of nitrobenzene tar and aniline waste water according to claim 1, wherein the coalescing separator is a fiber filter element separator, a special plate group separator or a combined separator.
9. The method for comprehensively utilizing the nitrobenzene tar and the aniline wastewater according to claim 1, wherein the nitrobenzene refining system comprises a nitrobenzene primary distillation tower and a rectification tower, and the operating conditions of the primary distillation tower are as follows: the tower top temperature is 90-110 ℃, the tower kettle temperature is 163-167 ℃, the tower top vacuum degree is 0.068-0.072 MPa, and the rectifying tower operation conditions are as follows: the temperature of the top of the tower is 100-120 ℃, the temperature of the bottom of the tower is less than or equal to 128 ℃, and the vacuum degree of the top of the tower is more than or equal to 0.094 MPa.
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