CN111646620B - Semi-coke wastewater treatment method and device - Google Patents

Semi-coke wastewater treatment method and device Download PDF

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CN111646620B
CN111646620B CN201910159407.1A CN201910159407A CN111646620B CN 111646620 B CN111646620 B CN 111646620B CN 201910159407 A CN201910159407 A CN 201910159407A CN 111646620 B CN111646620 B CN 111646620B
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ammonia
wastewater
water
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CN111646620A (en
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杨思宇
陈博坤
曹琦
钱宇
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South China University of Technology SCUT
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    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F9/00—Multistage treatment of water, waste water or sewage
    • 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
    • C02F1/02—Treatment of water, waste water, or sewage by heating
    • C02F1/04—Treatment of water, waste water, or sewage by heating by distillation or evaporation
    • C02F1/10—Treatment of water, waste water, or sewage by heating by distillation or evaporation by direct contact with a particulate solid or with a fluid, as a heat transfer medium
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
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    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/20—Treatment of water, waste water, or sewage by degassing, i.e. liberation of dissolved gases
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    • 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
    • C02F1/26—Treatment of water, waste water, or sewage by extraction
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    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
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    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/40—Devices for separating or removing fatty or oily substances or similar floating material
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    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F2101/00—Nature of the contaminant
    • C02F2101/10—Inorganic compounds
    • C02F2101/16—Nitrogen compounds, e.g. ammonia
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
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    • C02F2101/30—Organic compounds
    • 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
    • C02F2101/34—Organic compounds containing oxygen
    • C02F2101/345—Phenols

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Abstract

The invention belongs to the technical field of sewage treatment, and discloses a semi-coke wastewater treatment method and device. The method comprises the following steps: adjusting the pH value of the semi-coke wastewater by an acid adding device, standing to realize gravity oil removal, and separating and recycling; the two effluent water cold and hot streams enter a stripping tower from the upper part and the middle upper part of the deacidification tower, acid gas in the wastewater is removed, and the wastewater is sent to a tail gas treatment device; carrying out countercurrent extraction on the kettle liquid and an extracting agent, and recovering the extracting agent from an extract phase through rectification separation to obtain a crude phenol product; recovering the solvent from the raffinate phase through a solvent stripping tower, and distilling the effluent through an ammonia distillation tower to remove ammonia nitrogen in the water to prepare concentrated ammonia water; the method can realize the high-efficiency separation and recovery of light oil, heavy oil, acid gas, phenols and ammonia nitrogen in the semi-coke wastewater, realizes the recycling of pollutants, simultaneously recycles the extracting agent in the wastewater treatment process, does not introduce new impurities into the wastewater treatment system, and has good application prospect.

Description

Semi-coke wastewater treatment method and device
Technical Field
The invention belongs to the technical field of sewage treatment, and particularly relates to a semi-coke wastewater treatment method and device.
Background
Coal is in an increasingly high position in the fields of energy and chemical industry, wherein the industries such as coal gas, coal oil, coal semi coke and the like are rapidly developed and widely applied to novel coal chemical engineering projects. The semi-coke wastewater is wastewater generated in the medium-low temperature dry distillation (600-800 ℃) process of coal, is rich in tar, phenol, ammonia nitrogen and other refractory organic pollutants, and has very complex water quality, high treatment difficulty and great environmental hazard. The treatment of the wastewater is a difficult problem in the field of water treatment and is also one of important factors for restricting the development of the coal chemical industry.
The waste water contains a large amount of phenol substances, and the phenol is various and cannot be directly biochemically treated. The conventional treatment method at present generally comprises two parts of chemical separation and biochemical treatment. Acid gas, ammonia nitrogen and phenolic substances in the wastewater are removed by a chemical separation means, phenol and ammonia in the wastewater are recovered to realize the recycling of high-value pollutants, and then the high-value pollutants enter a biochemical treatment system so as to achieve the aim of treating the wastewater. The traditional chemical separation method, namely a phenol ammonia recovery system, the effluent quality of the system directly determines the running stability of a biochemical treatment system, and is the key of the wastewater treatment.
Patent publication CN 107434335A relates to a resource comprehensive treatment method for semi-coke wastewater phenol ammonia recovery. Results of the application examples: the total phenol of the effluent is 1000mg/L, the ammonia nitrogen is 80mg/L, and the total COD is 4000 mg/L.
Patent publication CN 101597124A relates to a method for treating coal gasification wastewater containing phenol and ammonia. The industrial application effect of the method on semi-coke wastewater treatment is as follows: the total phenol content of the effluent is 700mg/L, the ammonia nitrogen content is 250mg/L, and the total COD content is 5500 mg/L.
The literature (research progress of blue carbon wastewater pretreatment technology, coal chemical industry, 2018.8, volume 46, stage 4) proposes that the total COD of effluent water of industrial blue carbon wastewater after phenol ammonia recovery is 6742 mg/L.
The phenol and ammonia removing and recovering processes of the industrially operated phenol and ammonia recovering system are basically similar, and comprise units of stripping, deacidifying, deaminating, extracting, dephenolizing, recovering a solvent and the like. The wastewater enters a phenol ammonia recovery system after oil and suspended matters in the wastewater are removed through gravity settling, and acidic gas and ammonia are separated and a high-purity ammonia product is recovered by utilizing the volatility difference of the acidic gas and the ammonia under high pressure; organic extracting agents such as methyl isobutyl ketone (MIBK), diisopropyl ether (DIPE), n-amyl alcohol (n-PTL), tributyl phosphate (TBP) and the like are adopted to extract and remove phenols in water, the extracting agents can be effectively recycled, and pollutants such as phenols are effectively recycled. However, the national environmental protection department proposes a new standard of 'zero liquid discharge' for wastewater in coal chemical industry: in the process of realizing zero liquid discharge, higher requirements are put forward on the removal efficiency of phenol, oil and ammonia nitrogen; the traditional phenol ammonia recovery process has insufficient removal efficiency on phenol, oil and ammonia nitrogen, and residual phenol and oil have great toxicity on microorganisms in the chemical engineering section, thereby influencing the stable operation of the system.
The defects and the defects of the prior phenol ammonia recovery technology are mainly shown as follows: firstly, the gravity settling tank can not effectively remove oil and suspended matters, and the water quality of the effluent can not reach the water quality index required by the phenol-ammonia recovery system. The waste water containing oil and suspended matters enters the deacidification and deamination device to easily cause the blockage of the tower plate, thereby not only influencing the efficiency of the deacidification and deamination of the waste water, but also influencing the running stability of the phenol ammonia recovery system. Secondly, the pH value of the wastewater is reduced to 7-8 after the acid gas and the ammonia nitrogen are removed, the removal efficiency of phenolic substances and other organic pollutants is low under the alkalescent condition, the total phenol index in the effluent of the same type phenol ammonia recovery process operated industrially is still about 700mg/L, and the COD index is still about 5500 mg/L. This is undesirable for subsequent treatment to degrade phenolic materials and total COD levels in the wastewater. The solubility of the complexing extractant in water is about 1000mg/L generally, the extractant is not recovered by an effective means and is difficult to biodegrade, and the biochemical load is increased by the introduction of the extractant in the wastewater.
Disclosure of Invention
In order to overcome the defects of the prior art, the invention mainly aims to provide a semi-coke wastewater treatment method. The method obviously improves the removal rate of phenol, ammonia, oil and COD and enhances the anti-fouling and anti-blocking capability of the system.
The invention also aims to provide a device for realizing the semi-coke wastewater treatment method.
The purpose of the invention is realized by the following scheme:
a semi-coke wastewater treatment method mainly comprises five units of standing and deoiling after acidifying semi-coke wastewater, stripping to remove acid gas, extracting and dephenolizing by an extracting agent, recycling a recovered solvent, stripping and deaminating alkalized wastewater and the like in sequence.
Preferably, the five units specifically include the following steps:
(1) acidifying and deoiling: adjusting the pH value of the semi-coke wastewater to 2-6 by an acid adding device, standing the semi-coke wastewater in a storage tank, separating heavy oil from light oil, and feeding the treated semi-coke wastewater into an acid removing tower;
(2) stripping and deacidifying: respectively cooling and heating the semi-coke wastewater subjected to acidification and deoiling in the step (1) from the upper part and the middle upper part of a deacidification tower, allowing the acid mixed gas extracted by the steam to be subjected to fractional condensation, then separating ammonia, acid gas, light oil and water through phase splitting, recovering the light oil, refluxing the ammonia and the water, discharging the acid gas, and extracting kettle liquid from the bottom of the deacidification tower;
(3) and (3) extraction dephenolization: feeding the kettle liquid extracted from the bottom of the deacidification tower in the step (2) into the upper part of an extraction tower to perform countercurrent extraction with an extractant, feeding an extraction phase extracted from the top of the extraction tower into a solvent recovery tower, wherein the molar reflux ratio of the solvent recovery tower is 0.1-0.4, rectifying and separating a crude phenol product and the extractant, and recycling the extractant; extracting raffinate phase from the bottom of the extraction tower;
(4) and (3) recovering the solvent: sending the raffinate phase extracted in the step (3) into a solvent stripping tower, extracting an azeotropic mixed gas of a solvent and water from the tower top, sending the condensed azeotropic mixed gas into an oil-water separator to separate the solvent phase and the water phase, refluxing the water phase to the top of the solvent stripping tower, and sending the solvent into a solvent circulating tank for recycling; collecting kettle liquid from the bottom of the solvent stripping tower;
(5) stripping and deamination: mixing the kettle liquid extracted in the step (4) with an alkaline solution, feeding the mixture into the upper part of an ammonia still, feeding direct steam into the bottom of the ammonia still to evaporate ammonia, cooling ammonia steam by a condenser at the top of the ammonia still, taking condensate as reflux of the ammonia still, and directly feeding ammonia gas into an ammonia water absorption device to be condensed into concentrated ammonia water; and the kettle liquid discharged from the bottom of the ammonia still exchanges heat with raffinate phase and then is sent to a biochemical treatment device.
The pH value in the step (1) is preferably 4.5-5.5, and more preferably 5.0;
the standing time in the step (1) is 2-6 h;
and (2) discharging the separated heavy oil in the step (1) from the bottom of the storage tank, discharging light oil from the upper part, and feeding the treated semi-coke wastewater into an acid removal tower from the middle-lower section.
The cold-hot feeding ratio of the deacidification tower in the step (2) is 1: 1-6; preferably 1: 2-6; more preferably 1: 3.
the tower bottom pressure of the deacidification tower in the step (2) is 0.1-0.2 MPa, the temperature is 100-121 ℃, the tower top pressure is 0.1-0.15 MPa, and the temperature is 35-45 ℃.
Segregating and condensing the acid mixed gas stripped in the step (2) at 30-40 ℃; preferably at 35 ℃.
The extractant described in step (3) includes, but is not limited to, at least one of diisopropyl ether (DIPE), methyl isobutyl ketone (MIBK), and n-amyl alcohol (n-PTL).
The volume ratio of the extracting agent to the kettle liquid in the step (3) is 1: 10-1: 1, preferably 1: 4.
the temperature of the top of the extraction tower in the step (3) is 40-70 ℃, and preferably 50 ℃.
And (3) the top pressure of the extraction tower in the step (3) is 0.1-0.2 MPa, and the bottom pressure of the extraction tower is 0.1-0.2 MPa.
And (4) the molar reflux ratio of the solvent recovery tower in the step (3) is 0.05-0.2.
The tower top pressure of the solvent recovery tower in the step (3) is 0.1-0.2 MPa, the temperature is 65-140 ℃, the tower bottom pressure is 0.1-0.2 MPa, and the temperature is 200-220 ℃;
the tower top pressure of the solvent stripping tower in the step (4) is 0.1-0.2 MPa, the temperature is 65-102 ℃, the tower bottom pressure is 0.1-0.2 MPa, and the temperature is 100-118 ℃.
The alkaline solution in the step (5) is NaOH solution, KOH solution and Ca (OH)2At least one of the solutions, preferably a 20 wt% NaOH solution.
When the alkaline solution in the step (5) is a NaOH solution, the molar ratio of NaOH in the NaOH solution to fixed ammonium in the kettle solution is 1: 0.5-1, preferably 1: 1.
the top pressure of the ammonia distillation tower in the step (5) is 0.1-0.15 MPa, the temperature is 55-80 ℃, the bottom pressure of the tower is 0.1-0.2 MPa, and the temperature is 102-122 ℃.
A device for realizing the semi-coke wastewater treatment method comprises the following steps:
comprises a storage tank, a deacidification tower, an extraction tower, a solvent stripping tower, a solvent recovery tower, an ammonia still, an oil-water separator and a storage tank:
the raw material wastewater is subjected to acid addition and then is kept stand and layered in a storage tank, the cold and hot water streams of the outlet water of the storage tank are connected with the top and the middle upper part feed inlet of the deacidification tower, and the bottom of the deacidification tower is connected with the extraction tower.
The top of the extraction tower is connected with a solvent recovery tower, the top of the solvent recovery tower is connected with a solvent storage tank, and the bottom of the solvent recovery tower is connected with a crude phenol recovery device through a pipeline; the bottom of the extraction tower is connected with a solvent stripping tower, the top of the solvent stripping tower is connected with an oil-water separator, an oil phase outlet of the oil-water separator is connected with a solvent storage tank, a water phase outlet is connected with the top of the solvent stripping tower, and the bottom of the solvent stripping tower is connected with an ammonia still; the solvent storage tank is respectively connected with the top of the solvent recovery tower and the extraction tower through pipelines; the top of the ammonia distillation tower is provided with an ammonia water outlet, and the bottom of the ammonia distillation tower is connected with a biochemical treatment device.
The acid-adding raw material wastewater is connected with an acid-adding device through a pump, and the strong acid is connected with the acid-adding device through a jet pump;
the raw material wastewater is subjected to acid addition and then is kept stand and layered in a storage tank, an upper oil phase is connected with a light oil tank from the upper part of the storage tank, and a lower oil phase is connected with a tar tank from the lower part of the storage tank;
the tower top of the deacidification tower is connected with an acid gas burning device or a sulfur recovery device;
and the ammonia water outlet is connected with an ammonia water absorption device.
The deacidification tower is a stripping tower with 10-25 theoretical stages, bulk fillers are arranged above a hot feed port, and tower plates are arranged below the hot feed port.
The extraction tower is a packed tower with 2-6 theoretical stages, and FG type honeycomb grid packing is filled in the tower.
The solvent recovery tower is a rectifying tower with the theoretical stage number of 17-30.
The solvent stripping tower is a stripping tower with 10-25 theoretical stages.
The ammonia still is a stripping tower with 8-20 theoretical stages, the upper part of a feed inlet of the ammonia still is a partial condenser, and the lower part of the feed inlet is a tower plate.
Compared with the prior art, the invention has the following advantages and beneficial effects:
(1) the invention effectively improves the removal efficiency of oil, acid gas, ammonia nitrogen and phenols, reduces the chroma of sewage, enhances the anti-fouling and anti-blocking performance of equipment, improves the running stability of a system, and provides a better environment for subsequent biochemical treatment; the grade of steam used in the deacidification and deamination process is reduced, so that the treatment cost of the wastewater is greatly reduced.
(2) According to the invention, the pH value of the wastewater is adjusted by adding acid to reduce the Zeta potential, so that oil is gathered into drops, and floating oil, dispersed oil, emulsified oil and oil-solid in water are effectively removed; the deacidification efficiency and the extraction dephenolization efficiency are improved by acidifying free ammonia in fixed water and reducing the pH value; after a proper amount of alkali liquor is added, ammonia nitrogen in water is stripped, a novel compound extracting agent is adopted, the loss amount of a solvent along with a water discharge system is greatly reduced, other components are not introduced into the treatment process, and tar, high-purity crude phenol and ammonia water products can be obtained simultaneously.
(3) The COD of the semi-coke wastewater treated by the process can be reduced to 2000-5000 mg/L from 20000-40000 mg/L; the oil is reduced from 500-1500 mg/L to 30-150 mg/L; reducing the total phenol content from 5000-15000 mg/L to 200-600 mg/L; reducing the ammonia nitrogen from 1500-3000 mg/L to 30-100 mg/L; the pH value of the effluent of the wastewater is changed from 7.5-8.5 to 7.8-8.5; the COD removal rate in the wastewater is more than 90 percent, the total phenol removal rate is more than 93 percent, the acid gas removal rate is more than 98 percent, and NH is added4The N removing rate is more than 95 percent, the oil removing rate is more than 80 percent, the chroma of the waste water is reduced by more than 10 times, and the circulation rate of the extracting agent is more than 99.9 percent.
(4) The invention is suitable for the extracting agent which is commonly used in industry, when different extracting agents are used, the change of the operating conditions of the process equipment is small, and the invention is beneficial to widely replacing the prior process flow.
(5) The invention ensures the effluent index and the stability of the influent water of the subsequent biochemical treatment system under the condition of efficiently removing light oil, phenol and ammonia nitrogen; and effective separation and recycling of crude phenol, heavy oil, light oil and ammonia nitrogen are realized, and the purity of the product is improved.
Drawings
FIG. 1 is a schematic view of a wastewater treatment process of the present invention:
1-semi coke waste water settling tank, 2-deacidification tower, 3-extraction tower, 4-solvent recovery tower, 5-solvent stripping tower, 6-ammonia still tower, 7-oil water separator, 8-solvent circulation tank, 9-strong acid self-acidification device, 10-raw semi coke waste water, 11-cold feed of deacidification tower, 12-hot feed of deacidification tower, 13-acid gas, 14-deacidification waste water, 15-extract phase, 16-extractant, 17-raffinate phase, 18-solvent recovery tower top solvent steam, 19-separated oil phase, 20-solvent stripping tower stripping azeotropic mixed gas, 21-alkaline solution, 22-solvent stripping tower kettle liquid, 23-crude ammonia gas, 24-circulating cooling water, 25-circulating cooling water backwater, 26-treated waste water, 27-crude phenol product removing tank area, 28-supplementary solvent, and 29-solvent recovery tower reflux solvent.
Detailed Description
The present invention will be described in further detail with reference to examples and drawings, but the embodiments of the present invention are not limited thereto.
The reagents used in the examples are commercially available without specific reference.
The semi-coke wastewater treatment process of the invention is schematically shown in figure 1, semi-coke wastewater 10 containing high content of acidic gas, phenol, ammonia, oil and other pollutants is adjusted to pH value between 2-6 by a strong acid self-acidification device 9, then is kept stand and settled in a settling tank 1, the upper layer is separated into light oil phase, the lower layer is separated into heavy oil phase, water phase is extracted from the middle lower part of the tank, and is divided into cold feed 11 and hot feed 12 which are connected with the top and middle upper feed inlet of a deacidification tower 2 through a pump, the deacidification tower is heated by 0.5MPag steam, acidic gas 13 is connected with an acidic gas burning device through a tower top acidic gas outlet, deacidification wastewater 14 extracted from the tower bottom of the deacidification tower 2 is cooled to 40-70 ℃ and is sent into an extraction tower 3 from the upper part to be subjected to multi-stage counter-current extraction with an extracting agent 16, an extraction phase 15 is sent into a solvent recovery tower 4, the solvent recovery tower is heated by solvent recovery tower top solvent steam 18(2.5MPag), crude phenol 27 and an extracting agent 16 are rectified and separated, the extractant is returned to the solvent circulation tank 8 for recycling; pumping the raffinate phase 17 into a solvent stripping tower 5, heating the tower bottom by adopting 0.5MPag direct steam, extracting azeotropic mixed gas 20 from the tower top, condensing and then sending the azeotropic mixed gas into an oil-water separator 7 for separating solvent and water, refluxing a lower-layer water phase to the top of the solvent stripping tower 5, and sending an upper-layer oil phase 19 to a solvent circulation tank 8 for recycling. Mixing the solvent stripping tower residue 22 and an alkaline solution 21, feeding the mixture into the upper part of an ammonia still 6, feeding 0.5MPag direct steam into the tower bottom to evaporate ammonia, cooling the ammonia steam by circulating cooling water 24 on a condenser at the tower top, returning circulating cooling water 25 as the reflux of the ammonia still 6, and directly feeding crude ammonia gas 23 into an ammonia water absorption device to be condensed into concentrated ammonia water; the treated wastewater 26 discharged from the bottom of the ammonia still is cooled and sent to a biochemical treatment device. The solvent 28 is periodically replenished into the solvent circulation tank 8, and the solvent 29 is refluxed from the solvent circulation tank 8 to the solvent recovery column.
Example 1
The flow rate is 100t/h, the total phenol content is about 12000mg/L, the total ammonia content is about 2500mg/L, and CO2The content is about 3400mg/L, H2S content of about 80mg/L, oil content of about 1200mg/L, CODCrThe semi-coke wastewater to be treated with the value of about 35000mg/L, the pH value of 7.8, the chromaticity of 22000 times and the water temperature of 37 ℃ is treated according to the flow shown in figure 1. MIBK is used as an extracting agent, the molar ratio of NaOH in a 20 wt% NaOH solution to fixed ammonium in the liquid of a solvent stripping tower is 1:0.98, and parameters such as the stage number, the pressure, the temperature and the like of each tower are as follows:
and (3) adjusting the pH value of the semi-coke wastewater to 5.1 by using an acid adding device, uniformly mixing the acid and the concentrated sulfuric acid, and standing for 2.5 hours.
The acid removal tower has 15 theoretical stages, the ratio of cold to hot feeding is 3:17, the temperature at the top of the tower is 38 ℃, the pressure is 0.1MPa, the temperature at the bottom of the tower is 102 ℃, the pressure is 0.11MPa, and the extraction amount at the top of the tower is 360 kg/h.
The theoretical stage number of the extraction tower is 3, the pressure at the top of the extraction tower is 0.1MPa, the temperature is 50 ℃, countercurrent extraction is adopted, the pressure at the bottom of the extraction tower is 0.11MPa, the temperature is 51 ℃, and the volume ratio of an extracting agent to waste water is 1: 3.
the theoretical stage number of the solvent recovery tower is 22, the pressure at the top of the tower is 0.1MPa, and the temperature is 115 ℃; the pressure at the bottom of the tower is 0.12MPa, and the temperature is 201 ℃; the molar reflux ratio was 0.2.
The theoretical stage number of the solvent stripping tower is 12, the pressure at the top of the tower is 0.1MPa, and the temperature is 89 ℃; the bottom pressure of the column is 0.11MPa, and the temperature is 102 ℃.
The theoretical stage number of the ammonia still is 12, the pressure at the top of the tower is 0.1MPa, the temperature is 59 ℃, the pressure at the bottom of the tower is 0.11MPa, and the temperature is 102 ℃.
Through the treatment of the process, the effluent indexes of the wastewater dephenolization treatment are as follows: COD is less than or equal to 2500mg/L, oil is less than or equal to 50mg/L, total phenol is less than or equal to 350mg/L, ammonia nitrogen is less than or equal to 60mg/L, acid gas is less than or equal to 30mg/L, chroma is less than or equal to 2000 times, pH value is 7.5, and circulation rate of an extracting agent is more than 99.9%.
Example 2
The flow rate is 20t/h, the total phenol content is about 14000mg/L, the total ammonia content is about 2300mg/L, and CO2Content about 3000mg/L, H2S content of about 100mg/L, oil content of about 1500mg/L, CODCrThe semi-coke wastewater to be treated with the value of 48000mg/L, the chroma of 25000 times, the pH value of 7.5 and the water temperature of 40 ℃ is treated according to the flow shown in figure 1. The extractant used was a mixed extractant (3: 2 volume ratio of MIBK to n-PTL), with a molar ratio of NaOH in 20 wt% NaOH solution to fixed ammonium in the solvent stripper bottoms of 1: 0.95, the parameters of the stage number, pressure, temperature and the like of each tower are as follows:
and (3) adjusting the pH value of the semi-coke wastewater to 4.8 by using an acid adding device, wherein the added acid is concentrated sulfuric acid, and standing for 5 hours after uniform mixing.
Deacidifying tower, theoretical stage 13, cold and hot feeding ratio of 1: 4, the temperature at the top of the tower is 41 ℃, the pressure is 0.1MPa, the temperature at the bottom of the tower is 102 ℃, the pressure is 0.11MPa, and the extraction amount at the top of the tower is 65 kg/h.
The theoretical stage of the extraction tower is 4 stages, the pressure at the top of the extraction tower is 0.1MPa, the temperature is 50 ℃, countercurrent extraction is adopted, the pressure at the bottom of the extraction tower is 0.11MPa, the temperature is 51 ℃, and the volume ratio of the extracting agent to the waste water is 1: 3.
The theoretical stage number of the solvent recovery tower is 26, the pressure at the top of the tower is 0.1MPa, and the temperature is 121 ℃; the pressure at the bottom of the tower is 0.12MPa, and the temperature is 201 ℃; the molar reflux ratio was 0.15.
The theoretical stage number of the solvent stripping tower is 15 grades, the pressure at the top of the tower is 0.1MPa, and the temperature is 96 ℃; the bottom pressure of the column is 0.11MPa, and the temperature is 102 ℃.
The theoretical stage number of the ammonia still is 12, the pressure at the top of the tower is 0.1MPa, the temperature is 59 ℃, the pressure at the bottom of the tower is 0.11MPa, and the temperature is 102 ℃.
Through the treatment of the process, the effluent indexes of the wastewater dephenolization treatment are as follows: COD is less than or equal to 3000mg/L, oil is less than or equal to 50mg/L, total phenol is less than or equal to 380mg/L, ammonia nitrogen is less than or equal to 50mg/L, acid gas is less than or equal to 35mg/L, chroma is less than or equal to 1600 times, pH value is 7.8, and circulation rate of an extracting agent is more than 99.9%.
Example 3
The flow rate is 300 tons/hour, the total phenol content is about 8000mg/L, the total ammonia content is about 3300mg/L, CO2Content about 4000mg/L, H2S content of about 50mg/L, oil content of about 1300mg/L, CODCrThe wastewater to be treated with the value of about 30000mg/L, the chroma of 25000 times, the pH value of 8.4 and the water temperature of 35 ℃ is treated according to the flow shown in figure 1. The extractant uses DIPE, the molar ratio of NaOH in 20 wt% NaOH solution to fixed ammonium in the solvent stripping tower still liquidIs 1:0.98, the parameters of the stage number, pressure, temperature and the like of each tower are as follows:
and (3) adjusting the pH value to 5.0 by using an acid adding device, uniformly mixing the acid and the concentrated sulfuric acid, and standing for 3.5 hours.
The deacidification tower has 14 theoretical stages, the cold-hot feeding ratio is 3:16, the tower top temperature is 36 ℃, the pressure is 0.1MPa, the tower bottom temperature is 102 ℃, the pressure is 0.11MPa, and the tower top extraction amount is 1250 kg/h.
The theoretical stage of the extraction tower is 4 stages, the pressure at the top of the extraction tower is 0.1MPa, the temperature is 50 ℃, countercurrent extraction is adopted, the pressure at the bottom of the extraction tower is 0.11MPa, the temperature is 51 ℃, and the volume ratio of the extracting agent to the waste water is 1: 5.
The theoretical stage number of the solvent recovery tower is 22, the pressure at the top of the tower is 0.1MPa, and the temperature is 71 ℃; the pressure at the bottom of the tower is 0.12MPa, and the temperature is 201 ℃; the molar reflux ratio was 0.1.
The theoretical stage number of the solvent stripping tower is 12, the pressure at the top of the tower is 0.1MPa, and the temperature is 69 ℃; the bottom pressure of the column is 0.11MPa, and the temperature is 102 ℃.
The theoretical stage number of the ammonia still is 15, the pressure at the top of the tower is 0.1MPa, the temperature is 60 ℃, the pressure at the bottom of the tower is 0.11MPa, and the temperature is 102 ℃.
Through the treatment of the process, the effluent indexes of the wastewater dephenolization treatment are as follows: COD is less than or equal to 4500mg/L, oil is less than or equal to 100mg/L, total phenol is less than or equal to 550mg/L, ammonia nitrogen is less than or equal to 50mg/L, acid gas is less than or equal to 30mg/L, chroma is less than or equal to 2500 times, pH value is 7.5, and extractant circulation rate is more than 99.5%.
The above embodiments are preferred embodiments of the present invention, but the present invention is not limited to the above embodiments, and any other changes, modifications, substitutions, combinations, and simplifications which do not depart from the spirit and principle of the present invention should be construed as equivalents thereof, and all such changes, modifications, substitutions, combinations, and simplifications are intended to be included in the scope of the present invention.

Claims (7)

1. A semi-coke wastewater treatment method is characterized by comprising the following steps: sequentially comprises five units of acidification of semi-coke wastewater, standing deoiling, stripping to remove acid gas, extraction of an extracting agent to remove phenol, recycling of a recovered solvent and stripping to remove ammonia from the alkalized wastewater;
the five units specifically include the following steps:
(1) acidifying and deoiling: adjusting the pH value of the semi-coke wastewater to 4.5-5.5 by an acid adding device, standing the semi-coke wastewater in a storage tank, separating heavy oil from light oil, and feeding the treated semi-coke wastewater into an acid removing tower;
(2) stripping and deacidifying: respectively cooling and heating the semi-coke wastewater subjected to acidification and deoiling in the step (1) from the upper part and the middle upper part of a deacidification tower, allowing the acid mixed gas extracted by the steam to be subjected to fractional condensation, then separating ammonia, acid gas, light oil and water through phase splitting, recovering the light oil, refluxing the ammonia and the water, discharging the acid gas, and extracting kettle liquid from the bottom of the deacidification tower;
(3) and (3) extraction dephenolization: feeding the kettle liquid extracted from the bottom of the deacidification tower in the step (2) into the upper part of an extraction tower to perform countercurrent extraction with an extractant, feeding an extraction phase extracted from the top of the extraction tower into a solvent recovery tower, wherein the molar reflux ratio of the solvent recovery tower is 0.1-0.4, rectifying and separating a crude phenol product and the extractant, and recycling the extractant; extracting raffinate phase from the bottom of the extraction tower;
(4) and (3) recovering the solvent: sending the raffinate phase extracted in the step (3) into a solvent stripping tower, extracting an azeotropic mixed gas of a solvent and water from the tower top, sending the condensed azeotropic mixed gas into an oil-water separator to separate the solvent phase and the water phase, refluxing the water phase to the top of the solvent stripping tower, and sending the solvent into a solvent circulating tank for recycling; collecting kettle liquid from the bottom of the solvent stripping tower;
(5) stripping and deamination: mixing the kettle liquid extracted in the step (4) with an alkaline solution, feeding the mixture into the upper part of an ammonia still, feeding direct steam into the bottom of the ammonia still to evaporate ammonia, cooling ammonia steam by a condenser at the top of the ammonia still, taking condensate as reflux of the ammonia still, and directly feeding ammonia gas into an ammonia water absorption device to be condensed into concentrated ammonia water; the kettle liquid discharged from the bottom of the ammonia still exchanges heat with raffinate phase and then is sent to a biochemical treatment device;
the tower bottom pressure of the deacidification tower in the step (2) is 0.1-0.2 MPa, the temperature is 100-121 ℃, the tower top pressure is 0.1-0.15 MPa, and the temperature is 35-45 ℃;
the top pressure of the ammonia distillation tower in the step (5) is 0.1-0.15 MPa, the temperature is 55-80 ℃, the bottom pressure of the tower is 0.1-0.2 MPa, and the temperature is 102-122 ℃;
the standing time of the step (1) is 2-6 h;
discharging the separated heavy oil in the step (1) from the bottom of a storage tank, discharging light oil from the upper part, and feeding the treated semi-coke wastewater into an acid removal tower from the middle-lower section;
the cold-hot feeding ratio of the deacidification tower in the step (2) is 1: 1-6;
segregating and condensing the acid mixed gas stripped in the step (2) at 30-40 ℃;
the extractant in the step (3) comprises at least one of diisopropyl ether, methyl isobutyl ketone and n-amyl alcohol;
the volume ratio of the extracting agent to the kettle liquid in the step (3) is 1: 10-1: 1;
the alkaline solution in the step (5) is NaOH solution, KOH solution and Ca (OH)2At least one of the solutions.
2. The semi-coke wastewater treatment method according to claim 1, characterized in that:
when the alkaline solution is NaOH solution, the molar ratio of NaOH in the NaOH solution to fixed ammonium in the kettle liquid is 1: 0.5 to 1.
3. The semi-coke wastewater treatment method according to claim 2, characterized in that:
the tower top pressure of the extraction tower in the step (3) is 0.1-0.2 MPa, the temperature is 40-70 ℃, and the tower bottom pressure is 0.1-0.2 MPa;
the tower top pressure of the solvent recovery tower in the step (4) is 0.1-0.2 MPa, the temperature is 65-140 ℃, the tower bottom pressure is 0.1-0.2 MPa, and the temperature is 200-220 ℃;
the tower top pressure of the solvent stripping tower in the step (4) is 0.1-0.2 MPa, the temperature is 65-102 ℃, the tower bottom pressure is 0.1-0.2 MPa, and the temperature is 100-118 ℃.
4. An apparatus for carrying out the method of any one of claims 1 to 3, wherein:
including storage tank, deacidification tower, extraction column, solvent stripping tower, solvent recovery tower, ammonia still, oil water separator, storage tank:
the raw material wastewater is subjected to acid addition and then is kept stand and layered in a storage tank, and the cold and hot water discharged from the storage tank are connected with the top and the middle upper feed inlet of the deacidification tower; the bottom of the deacidification tower is connected with an extraction tower;
the top of the extraction tower is connected with a solvent recovery tower, the top of the solvent recovery tower is connected with a solvent storage tank, and the bottom of the solvent recovery tower is connected with a crude phenol recovery device through a pipeline; the bottom of the extraction tower is connected with a solvent stripping tower, the top of the solvent stripping tower is connected with an oil-water separator, an oil phase outlet of the oil-water separator is connected with a solvent storage tank, a water phase outlet is connected with the top of the solvent stripping tower, and the bottom of the solvent stripping tower is connected with an ammonia still; the solvent storage tank is respectively connected with the top of the solvent recovery tower and the extraction tower through pipelines; the top of the ammonia distillation tower is provided with an ammonia water outlet, and the bottom of the ammonia distillation tower is connected with a biochemical treatment device.
5. The apparatus of claim 4, wherein:
the acid-adding raw material wastewater is connected with an acid-adding device through a pump, and the strong acid is connected with the acid-adding device through a jet pump;
the raw material wastewater is subjected to acid addition and then is kept stand and layered in a storage tank, an upper oil phase is connected with a light oil tank from the upper part of the storage tank, and a lower oil phase is connected with a tar tank from the lower part of the storage tank;
the tower top of the deacidification tower is connected with an acid gas burning device or a sulfur recovery device;
and the ammonia water outlet is connected with an ammonia water absorption device.
6. The apparatus of claim 4, wherein:
the extraction tower is a packed tower with 2-6 theoretical stages, and the packing in the tower is FG type honeycomb grid packing;
the ammonia still is a stripping tower with the theoretical stage number of 8-20, the upper part of a feed inlet of the ammonia still is a partial condenser, and the lower part of the feed inlet is a tower plate;
the solvent recovery tower is a rectifying tower with the theoretical stage number of 17-30;
the solvent stripping tower is a stripping tower with 10-25 theoretical stages.
7. The apparatus of claim 4, wherein:
the deacidification tower is a stripping tower with 10-25 theoretical stages, bulk fillers are arranged above a hot feed port, and tower plates are arranged below the hot feed port.
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