Method for recycling and comprehensive treatment of semi-coke wastewater resources

Abstract

The present application relates to a method for recycling and comprehensive treatment of semi-coke wastewater, comprising the following steps: S1: after pretreatment, the semi-coke wastewater is subjected to oil removal treatment to separate light oil, water phase, heavy oil and oil residue; S2: the water phase obtained in step S1 is subjected to extraction to extract phenolic substances therefrom to obtain an extraction phase containing phenolic substances and a water phase containing an extraction agent; S3: the extraction phase containing phenolic substances and the water phase containing an extraction agent are subjected to separate treatment to recover their extraction agents and recycle them to the extraction treatment in step S2; phenolic substances and wastewater are separated; S4: the phenolic substances obtained in step S3 are subjected to three separate treatments in sequence to obtain phenol, o-cresol, m / p-cresol and mixed dimethyl phenol, respectively; and S5: the wastewater obtained in step S3 is subjected to biochemical treatment, and the obtained water can be reused.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of semi-coke wastewater treatment, and particularly relates to a method for recycling and comprehensively treating semi-coke wastewater. BACKGROUND

[0002] Semi-coke wastewater is wastewater generated in the process of producing semi-coke from coal blocks through dry distillation. The semi-coke wastewater contains a large amount of coal tar, phenolic substances, light oil, oil residue and other pollutants, and has a high COD and poor biodegradability. Traditional semi-coke wastewater treatment methods mainly focus on the degradation and removal of organic and inorganic pollutants, and generally require the use of advanced chemical oxidation or even incineration, combined with biochemical treatment, to remove refractory organic matter. Such a treatment method consumes a large amount of oxidizing agents and auxiliary reagents, or consumes heat energy and releases waste gas, which not only has high equipment investment and operation and treatment costs, but also produces waste gas containing carbon, sulfur, oxygen and other elements, which needs to be treated separately. If the resource substances in the semi-coke wastewater can be recycled and utilized, the COD of the wastewater can be reduced, the biodegradability can be improved, and the difficulty and cost of wastewater treatment can be reduced. SUMMARY

[0003] To solve the above problems, the present application provides a method for recycling and comprehensively treating semi-coke wastewater, comprising the following steps:

[0004] S1: After the semi-coke wastewater is pretreated, oil removal treatment is performed to separate light oil, water phase, heavy oil and oil residue;

[0005] S2: The water phase obtained in step S1 is extracted to extract phenolic substances therefrom, to obtain an extraction phase containing phenolic substances and a water phase containing an extraction agent;

[0006] S3: The extraction phase containing phenolic substances and the water phase containing an extraction agent are separately treated to recover their extraction agents and reuse them in the extraction treatment of step S2; phenolic substances and wastewater are separated;

[0007] S4: The phenolic substances obtained in step S3 are separated three times in sequence to obtain phenol, o-cresol, m / p-cresol and mixed dimethyl phenol, respectively;

[0008] S5: The wastewater obtained in step S3 is subjected to biochemical treatment to obtain water that can be reused.

[0009] Optionally, the oil removal treatment of step S1 comprises, in sequence, a first standing treatment, a first separation treatment, a second separation treatment and a second standing treatment; in the first standing treatment, the wastewater is input into a first standing tank for standing, preliminary sedimentation, floating of light oil, sinking of heavy oil and oil residue, and water phase in the middle part, and the water phase in the middle part is input into a first separator for first separation treatment;

[0010] The first-stage separator is provided with a first stirrer for stirring the wastewater and capturing oil droplets in the wastewater;

[0011] The water phase obtained from the first-stage separator is input into a second-stage separator for second-stage separation treatment. The second-stage separator is provided with a second stirrer for stirring the wastewater and capturing oil droplets in the wastewater;

[0012] The water phase obtained from the second-stage separator is input into a second-stage static tank for second-stage static treatment.

[0013] The oil removal treatment of step S1 separates the free-state dispersed oil, suspended oil and emulsified oil in the semi-coke wastewater through a hierarchical step-by-step method, and at the same time, cooperates with the gravity sedimentation oil removal process to realize effective treatment of the semi-coke wastewater and facilitate long-period operation of the subsequent treatment equipment. The two-stage separators of step S1 are provided with static tanks before and after the two-stage separators respectively for preliminary and further oil removal of the semi-coke wastewater, so that the entire treatment system has stronger anti-shock load capacity. In the case of large fluctuations in the water inflow and oil content, the petroleum-based indicators in the water produced by the entire treatment system are relatively stable. The conventional oil-water separator is easy to maintain, has strong adaptability to the oil-containing phenol-ammonia wastewater, and has a certain removal effect on suspended solids, so that long-period stable operation can be realized. The wastewater resource treatment is realized to recover oil and other resources, which solves the safety and environmental protection problems and also increases economic benefits.

[0014] Further optionally, the time length of the first-stage static treatment and the second-stage static treatment is 50-70 h; the rotation speed of the stirrers of the first-stage separator and the second-stage separator and the treatment time length are adjusted according to the water quality of the semi-coke wastewater, the temperature is 35-40℃, and the pressure is 0.05-0.08 MPaG.

[0015] Optionally, step S2 includes the following steps:

[0016] (1) The water phase after oil removal obtained from step S1 is divided into two parts, one part is preheated to form hot feed which is input into the middle and upper part of the deacidification tower, and the other part is cold feed which is input into the top of the deacidification tower; steam is input into the bottom of the deacidification tower to remove acidic gases in the water phase, and the acidic gases are discharged from the top of the deacidification tower;

[0017] (2) The bottom liquid of the deacidification tower and the alkali liquor are input into the middle and upper part of the deamination tower, the medium-pressure steam is input into the bottom of the deamination tower as a heat source to perform deamination treatment, and the ammonia-rich gas is collected from the top of the deamination tower;

[0018] (3) The bottom liquid of the deamination tower and the acid liquor are input into the top of the extraction tower, and the extractant is input into the bottom of the extraction tower to extract the phenolic substances in the wastewater, and the extraction phase containing phenolic substances is discharged from the top of the extraction tower, and the tower kettle liquid of the extraction tower is the water phase containing the extractant.

[0019] Optionally, in step (1), the cold feed is cooled to 35-40℃ by cooling water, and the hot feed is preheated to 45-50℃ before being fed into the deacidification tower.

[0020] The bottom of the deacidification tower is fed with medium-pressure steam, and the kettle bottom liquid temperature of the deacidification tower is 150-160℃, which can be used to preheat the hot feed of the deacidification tower.

[0021] Optionally, the top temperature of the deacidification tower is 65-70℃, and the pressure is 0.5-0.6 MPaG; the bottom temperature is 155-160℃, and the pressure is 0.52-0.6 MPaG.

[0022] The cold feed accounts for 25-30wt% of the total feed.

[0023] Optionally, in step (2), the alkali solution is a sodium hydroxide solution with a concentration of 30-35wt%, and the rich ammonia gas is at 140-150℃, which can be used to preheat the hot feed of the deacidification tower.

[0024] Optionally, the bottom temperature of the deamination tower is 150-160℃, and the pressure is 0.37-0.38 MPaG; the top temperature is 140-150℃, and the pressure is 0.35-0.36 MPaG.

[0025] Optionally, between step (2) and step (3), there is also a step of ammonia gas recovery treatment:

[0026] (a) The rich ammonia gas is subjected to primary gas-liquid separation to obtain ammonia gas and condensate, and the condensate is collected after condensation; the ammonia gas is at 130-140℃, subjected to secondary gas-liquid separation after condensation to obtain ammonia gas and condensate, and the condensate is collected after condensation; the ammonia gas is at 90-100℃, subjected to tertiary gas-liquid separation after condensation to obtain ammonia gas and condensate, and the condensate is collected; the ammonia gas is at 30-40℃;

[0027] (b) The ammonia gas obtained by tertiary gas-liquid separation is mixed with desalted water to prepare ammonia water with a concentration of 20wt%;

[0028] (c) A part of the condensate obtained by three times of gas-liquid separation in step (a) is returned to the top of the deamination tower, and the rest is reused in the raw material of coke oven waste water in step S1 to adjust the water quality.

[0029] The non-condensable gas in the ammonia gas in step (b) is discharged from the overall system, and the flow rate of the condensate returned to the deamination tower in step (c) is 4500-5000kg / h.

[0030] Optionally, in step (3), the kettle bottom liquid temperature of the deamination tower is 150-160℃, which can be used to preheat the hot feed of the deacidification tower; and the acid solution is a 98% sulfuric acid solution.

[0031] The temperature in the extraction tower is 40-45°C, and the pressure at the top of the tower is 0.01-0.03 MPaG; the feeding ratio of the water phase to the oil phase is (2.95-3.00):1.

[0032] The phenolic substances in the extraction tower are weakly acidic and will be slightly ionized in water, and the degree of electrolysis is affected by the pH value of the water phase, and almost no ionization occurs under acidic conditions. In order to maintain a good extraction environment, the extraction needs to be carried out in a weak acid environment, and according to the pH value of the bottom liquid of the deamination tower, sulfuric acid is injected when necessary.

[0033] Optionally, step S3 includes the following steps:

[0034] (4) The water phase containing the extractant is cooled and then input into the middle part of the water tower for oil-water separation;

[0035] (5) The extractant at the top of the water tower is extracted and input into the oil-water separator, the obtained water phase is returned to the water tower from the top of the water tower, and the obtained oil phase is the extractant which can be reused in the extraction tower;

[0036] (6) After the bottom liquid at the bottom of the water tower cools the water phase containing the extractant, the biochemical treatment of step S5 is carried out;

[0037] (7) The extraction phase containing phenols is preheated and then input into the upper part of the phenol tower, the recovered extractant is input into the top of the phenol tower, the separation of the phenolic substances and the extractant is carried out, the separated phenolic substances are discharged as the tower bottom liquid, and the separated extractant is discharged as the gas phase from the top of the phenol tower;

[0038] (8) The extracted extractant gas is first heat-exchanged with the extraction phase containing phenols, and then sequentially condensed and cooled to obtain extractant liquid, part of which is reused in the extraction tower, and the other part is returned to the top of the phenol tower.

[0039] Optionally, in step (4), the water phase containing the extractant is cooled to about 40°C;

[0040] The water tower is a tray type, the temperature at the top of the tower is 97-100°C, and the pressure is 0.02-0.03 MPaG; the temperature at the bottom of the tower is 108-110°C, and the pressure is 0.04-0.05 MPaG; a reboiler is arranged at the bottom of the water tower.

[0041] Optionally, in step (5), the flow rate of the water phase returned to the water tower is 550-650 kg / h.

[0042] Optionally, in step (7), a reboiler is arranged at the bottom of the phenol tower;

[0043] The extraction phase containing phenols is preheated to 115-125°C, the extractant refluxed at the top of the phenol tower is 40-50°C, and the reflux amount is 5000-5200 kg / h;

[0044] The top temperature of the phenol column is 118-125°C, and the pressure is 0.02-0.03 MPaG; the bottom temperature is 215-220°C, and the pressure is 0.04-0.05 MPaG.

[0045] Optionally, step S4 comprises the following steps:

[0046] (9) The qualified phenol column bottom liquid obtained in step (7) is input into the middle-upper part of the dehydration column to perform dehydration treatment, and phenol water is collected at the top of the dehydration column and discharged from the system after condensation;

[0047] (10) The column bottom liquid of the dehydration column is input into the middle-upper part of the light component removal column to remove light components, and light components are collected at the top of the light component removal column and discharged from the system after condensation;

[0048] (11) The column bottom liquid of the light component removal column is input into the middle-upper part of the heavy component removal column to remove heavy components, and the column bottom liquid of the heavy component removal column is heavy components and is discharged from the system after condensation;

[0049] (12) The crude phenol after dehydration, light component removal and heavy component removal is collected at the top of the heavy component removal column and input into the middle-upper part of the phenol column after condensation to separate phenol, and the phenol is collected at the top of the phenol column and discharged from the system after condensation;

[0050] (13) The column bottom liquid of the phenol column is input into the middle-upper part of the o-cresol column to separate o-cresol, and the o-cresol is collected at the top of the o-cresol column and discharged from the system after condensation;

[0051] (14) The column bottom liquid of the o-cresol column is input into the middle-upper part of the m,p-cresol column to separate m,p-cresol, and the m,p-cresol is collected at the top of the m,p-cresol column and discharged from the system after condensation, and the column bottom liquid is mixed dimethylphenol.

[0052] Optionally, in step (9), the phenol water comprises water and a small amount of phenolic substances, and after condensation, part of the phenol water is refluxed to the top of the dehydration column, and the other part is mixed into the raw material of the blue water waste in step S1 to adjust the water quality;

[0053] The column bottom liquid of the dehydration column is crude phenol after water removal, part of which is returned to the bottom of the dehydration column after being heated by the reboiler of the dehydration column, and the other part is input into the light component removal column;

[0054] The top temperature of the dehydration column is 60-65°C, the bottom temperature is 145-150°C, and the pressure is -0.08 MPaG.

[0055] Optionally, in step (10), the light components and a small amount of phenolic substances are collected at the top of the light component removal column and discharged from the system or collected after condensation;

[0056] The tower kettle liquid of the light component removal tower is crude phenol from which light components are removed, a part of which is returned to the bottom of the light component removal tower after being heated by the light component removal tower reboiler, and another part of which is input into the heavy component removal tower;

[0057] The tower top temperature of the light component removal tower is 125-130℃, the tower bottom temperature is 150-160℃, and the pressure is -0.08MPaG.

[0058] Optionally, in step (11), phenolic substances from which heavy components are removed are taken out from the top of the heavy component removal tower, and after being condensed, a part of which is returned to the top of the heavy component removal tower, and another part of which is input into the phenol tower;

[0059] The tower kettle liquid of the heavy component removal tower is heavy components, a part of which is returned to the bottom of the heavy component removal tower after being heated by the heavy component removal tower reboiler, and another part of which is cooled and then discharged from the system or collected;

[0060] The tower top temperature of the heavy component removal tower is 125-130℃, the tower bottom temperature is 190-200℃, and the pressure is -0.09MPaG.

[0061] Optionally, in step (12), phenol substances are taken out from the top of the phenol tower, and after being condensed, a part of which is returned to the top of the phenol tower, and another part of which is condensed and then discharged from the system or collected;

[0062] The tower kettle liquid of the phenol tower is crude phenol from which phenol is removed, a part of which is returned to the bottom of the phenol tower after being heated by the phenol tower reboiler, and another part of which is input into the o-cresol tower;

[0063] The tower top temperature of the phenol tower is 110-120℃, the tower bottom temperature is 150-160℃, and the pressure is -0.09MPaG.

[0064] Optionally, in step (13), o-cresol substances are taken out from the top of the o-cresol tower, and after being condensed, a part of which is returned to the top of the o-cresol tower, and another part of which is condensed and then discharged from the system or collected;

[0065] The tower kettle liquid of the o-cresol tower is crude phenol from which o-cresol is removed, a part of which is returned to the bottom of the o-cresol tower after being heated by the o-cresol tower reboiler, and another part of which is input into the m,p-cresol tower;

[0066] The tower top temperature of the o-cresol tower is 120-130℃, the tower bottom temperature is 153-165℃, and the pressure is -0.09MPaG.

[0067] Optionally, in step (14), m,p-cresol substances are taken out from the top of the m,p-cresol tower, and after being condensed, a part of which is returned to the top of the m,p-cresol tower, and another part of which is condensed and then discharged from the system or collected;

[0068] The tower kettle liquid of the m,p-cresol tower is mixed dimethylphenol, a part of which is returned to the bottom of the mixed dimethylphenol tower after being heated by the mixed dimethylphenol tower reboiler, and another part of which is cooled and then collected;

[0069] The overhead temperature of the m-p-cresol column is 130-140 DEG C, the bottom temperature is 165-175 DEG C, and the pressure is -0.09 MPaG.

[0070] Optionally, in step S5, the following steps are included:

[0071] (15) The kettle bottom liquid of the water column in step (6) is input into the adjusting pool to adjust the water quality, and then is input into the sedimentation pool to remove the emulsified oil and suspended solid matters in the waste water;

[0072] (16) The water produced by the sedimentation pool is input into the hydrolysis acidification pool to perform the hydrolysis acidification reaction and improve the biodegradability;

[0073] (17) The water produced by the hydrolysis acidification pool is input into the internal circulation biological reaction pool to perform the denitrification, nitrification and sedimentation treatment in sequence, so as to degrade the pollutants, remove the nitrogen and phosphorus, and then the waste water is separated from the sludge and discharged;

[0074] (18) The water produced by the internal circulation biological reaction pool is input into the AO pool to perform the anoxic treatment and aerobic treatment in sequence, and then is input into the secondary sedimentation pool to perform the sludge sedimentation;

[0075] (19) The supernatant of the secondary sedimentation pool is subjected to the coagulation treatment of the coagulation reaction pool, and then is subjected to the filtration, ozone oxidation treatment and rapid filtration to obtain the produced water, which can be used as the recycled water.

[0076] The raw material of the semi-coke waste water treated by the present application contains a large amount of oil substances, and although the multi-stage oil removal treatment of step S1 is performed, a small amount of residual oil phase which is insoluble in water, emulsified oil and / or dissolved oil is inevitably contained in the water phase of the waste water. It is difficult to separate the oil phase, emulsified oil and / or dissolved oil from the water phase by relying on the density difference alone. After the water phase containing the oil phase, emulsified oil and / or dissolved oil is input into the extraction column, the fillers in the extraction column are polluted, and the extraction efficiency is reduced. Therefore, the present application provides an extraction column.

[0077] Optionally, the extraction column is provided with a rotating filler layer and a moving filler layer, the rotating filler layer is below the moving filler layer, the center of the rotating filler layer is provided with a stirring shaft which is driven to rotate by a motor at the bottom of the extraction column, the moving filler layer comprises a center support and a support guide which spirally surrounds the outside of the center support, a plurality of filler cages are connected with each other to form a chain shape and move along the support guide from bottom to top, the side wall of the extraction column corresponding to the moving filler layer is provided with a hollow interlayer, a plurality of rotating wheels are arranged in the interlayer and used to guide the filler cages at the top of the moving filler layer into the interlayer and move downward, and then the filler cages are guided to pass out of the bottom of the interlayer and move upward along the support guide again, and the top of the interlayer is provided with a spraying device which is used to clean the filler cages moving into the interlayer.

[0078] Further, the rotating filler layer comprises a stirring shaft and a filler part, the filler part is spirally wound from top to bottom along the outer side of the stirring shaft, the bottom of the stirring shaft penetrates through the bottom of the extraction tower and is connected with the motor outside the lower part of the extraction tower to drive the rotation of the stirring shaft and the filler part.

[0079] The inner side of the filler part is fixed on the stirring shaft, the outer layer extends to the inner wall of the extraction tower and leaves an interval between the inner wall of the extraction tower.

[0080] Further, the filler part is in the form of a mesh cage, a plurality of partition walls are arranged in the filler part, the plurality of partition walls are uniformly distributed along the length direction of the filler part, the filler part is divided into a plurality of segments, and each segment is filled with filler.

[0081] The present application can use conventional fillers in the field, such as theta ring.

[0082] Further, the support guide rail comprises an inner support bar and an outer support bar spirally wound on the outer side of the central support column, the inner support bar is close to the outer side of the central support column, a plurality of rolling cross bars are connected between the inner support bar and the outer support bar, the rolling cross bars are horizontally arranged to support the filler cage.

[0083] The inner wall of the extraction tower is provided with a cleaning inlet corresponding to the position of the top port of the support guide rail, and the inner wall of the extraction tower is provided with a cleaning outlet corresponding to the position of the bottom port of the support guide rail, the cleaning inlet and the cleaning outlet are on the same vertical line, and the interlayer is communicated with the support guide rail through the cleaning inlet and the cleaning outlet. BRIEF DESCRIPTION OF DRAWINGS

[0084] Figure 1 It is a flow chart of the method for recycling and comprehensive treatment of semicoke wastewater resources of embodiment 1;

[0085] Figure 2 It is a structural schematic diagram of the extraction tower of embodiment 4 (omitting the tower plate);

[0086] Figure 3 It is a partial schematic diagram of the support guide rail;

[0087] Figure 4 It is a partial schematic diagram of the tower plate.

[0088] In the drawings, 1 is an extraction tower, 2 is a rotating filler layer, 3 is a moving filler layer, 4 is an extract outlet, 5 is a wastewater inlet, 6 is an extractant inlet, 7 is a kettle liquid outlet, 8 is a stirring shaft, 9 is a central support column, 10 is a support guide rail, 11 is a filler cage, 12 is an interlayer, 13 is a rotating wheel, 14 is a filler part, 15 is a tail gas outlet, 16 is an overflow weir, 17 is an inner support bar, 18 is an outer support bar, 19 is a rolling cross bar, 20 is a cleaning inlet, 21 is a cleaning outlet, 22 is a tower plate, 23 is a large through hole, and 24 is a small through hole. DETAILED DESCRIPTION

[0089] The treatment amount of the raw material of the semi-coke wastewater treated in the following examples and comparative examples is 45m 3 / h, the pH value is 6-9, and other water quality indexes are as follows:

[0090] Item Design value (mg / L) Item Design value (mg / L) COD cr ]] 61300 Ammonia nitrogen 4500 BOD5 31000 Sulphides 4000 Volatilised phenols 7000 Carbon dioxide 7500 Petroleum oils 5000 Total phenols 12000

[0091] Example 1

[0092] The method for recycling and comprehensively treating semi-coke wastewater provided in the embodiment, as shown in Figure 1 , comprises the following steps:

[0093] S1: After the semi-coke wastewater is pretreated, oil removal treatment is performed to separate light oil, water phase, heavy oil and oil residue;

[0094] S2: The water phase obtained in step S1 is extracted to extract phenolic substances therefrom to obtain an extraction phase containing phenols and a water phase containing an extraction agent;

[0095] S3: The extraction phase containing phenols and the water phase containing an extraction agent are respectively subjected to separation treatment, the extraction agents are recovered, and are reused in the extraction treatment of step S2; phenolic substances and wastewater are separated;

[0096] S4: The phenolic substances obtained in step S3 are sequentially subjected to three times of separation to obtain phenol, o-cresol, m / p-cresol and mixed dimethyl phenol, respectively;

[0097] S5: The wastewater obtained in step S3 is subjected to biochemical treatment to obtain water which can be reused.

[0098] In step S1, the pretreatment refers to cleaning the inorganic waste with a larger volume in the semi-coke wastewater, for example, using a grid to intercept the large solid waste in the semi-coke wastewater.

[0099] The oil removal treatment of step S1 is once static separation, the upper oil layer is light oil, the middle water phase is wastewater, and the lower oil layer is heavy oil, including part of oil residue.

[0100] Step S2 comprises the following steps:

[0101] (1) The water phase after oil removal obtained in step S1 is preheated and then enters the upper middle part of a deacidification tower, steam is input at the bottom of the deacidification tower, the acid gas in the water phase is removed, and the acid gas is discharged from the top of the deacidification tower;

[0102] (2) The liquid at the bottom of the deacidification tower and the alkali liquor are input into the upper middle part of a deamination tower, medium-pressure steam is input at the bottom of the deamination tower as a heat source to perform deamination treatment, and ammonia-rich gas is collected at the top of the deamination tower;

[0103] (3) The bottom liquid of the deacidification tower and the acid liquid are input into the top of the extraction tower, the extractant is input into the bottom of the extraction tower, the phenolic substances in the extraction wastewater are extracted, and the phenolic extraction phase is discharged from the top of the extraction tower, and the tower bottom liquid of the extraction tower is the water phase containing the extractant.

[0104] In step (1), the feed of the deacidification tower is preheated to 46°C, and then input into the deacidification tower; the medium-pressure steam is input into the bottom of the deacidification tower, with a temperature of 190°C and a pressure of 1.0 MPaG;

[0105] The upper part of the deacidification tower is filled with packing, and the rest is filled with trays; the feed is input above the uppermost tray, and the steam is input below the lowermost tray; the bottom liquid of the deacidification tower is input below the steam inlet of the deacidification tower;

[0106] A reboiler is arranged at the bottom of the deacidification tower; the temperature of the bottom liquid of the deacidification tower is 158°C, which can be used to preheat the feed of the deacidification tower.

[0107] In step (1), the acidic gas discharged from the deacidification tower is condensed to about 40°C, and then sent to the acid gas condensate tank; part of the acid liquid in the acid gas condensate tank is reused in the raw material of the coke wastewater in step S1 to adjust the water quality, and the other acid liquid is treated separately.

[0108] The temperature at the top of the deacidification tower is 65°C, and the pressure is 0.5 MPaG; the temperature at the bottom of the deacidification tower is 158°C, and the pressure is 0.52 MPaG.

[0109] In step (2), the deamination tower is tray type, and a reboiler is arranged at the bottom, with the same medium-pressure steam as in the deacidification tower; the alkali liquid is sodium hydroxide solution with a concentration of 35wt%; the bottom liquid of the deacidification tower and the alkali liquid are countercurrently contacted with the medium-pressure steam to remove ammonia in the wastewater, and the ammonia gas is discharged from the top of the deamination tower, at this time the rich ammonia gas is 145°C, which can be used to preheat the hot feed of the deacidification tower.

[0110] The temperature at the bottom of the deamination tower is 150°C, and the pressure is 0.37 MPaG; the temperature at the top of the deamination tower is 144°C, and the pressure at the top of the deamination tower is 0.35 MPaG.

[0111] Between step (2) and step (3), there is also a step of ammonia gas recovery treatment:

[0112] (a) The rich ammonia gas is subjected to primary gas-liquid separation to obtain ammonia gas and condensate, and the condensate is collected after condensation; the ammonia gas is 130-140°C, and after condensation, it is subjected to secondary gas-liquid separation to obtain ammonia gas and condensate, and the condensate is collected after condensation; the ammonia gas is 90-100°C, and after condensation, it is subjected to tertiary gas-liquid separation to obtain ammonia gas and condensate, and the condensate is collected; the ammonia gas is 30-40°C;

[0113] (b) The ammonia gas obtained by tertiary gas-liquid separation is mixed with desalted water to prepare ammonia water with a concentration of 20wt%.

[0114] (c) a part of the condensate obtained from the third gas-liquid separation in step (a) is returned to the top of the deaminating tower, and the rest is reused in the raw material of the coke-oven wastewater in step S1 to adjust the water quality.

[0115] The non-condensable gas in the ammonia gas is discharged from the whole system in step (b), and the flow rate of the condensate returned to the deaminating tower in step (c) is 4500 kg / h.

[0116] The quality of the obtained ammonia water is as follows: blackness ≤80, evaporation residue ≤0.2wt%, phenols ≤0.05 mg / L.

[0117] In step (3), the kettle bottom liquid of the deaminating tower is used to preheat the hot feed of the deacidifying tower, and the acid liquid is a 98% sulfuric acid solution.

[0118] The extraction tower is in the form of packing, the kettle bottom liquid (aqueous phase) of the deaminating tower is input into the extraction tower from above the packing, the extractant (oil phase) is input into the extraction tower from below the packing, the kettle bottom liquid of the deaminating tower is countercurrently contacted with the extractant to extract phenolic substances, and the extractant is methyl isobutyl ketone; the non-condensable gas is discharged from the top of the extraction tower.

[0119] The temperature in the extraction tower is 40°C, the pressure at the top of the tower is 0.01 MPaG, and the feed ratio of the aqueous phase to the oil phase is 2.95:1.

[0120] Step S3 comprises the following steps:

[0121] (4) the aqueous phase containing the extractant is cooled to 40°C and input into the middle part of the water tower to perform oil-water separation;

[0122] The water tower is in the form of tray, the temperature at the top of the tower is 97°C, and the pressure is 0.02 MPaG; the temperature at the bottom of the tower is 108°C, and the pressure is 0.04 MPaG; a reboiler is arranged at the bottom of the water tower.

[0123] (5) the extractant is extracted from the top of the water tower and input into the oil-water separator, the aqueous phase obtained by separation of the oil-water separator is returned to the water tower from the top of the water tower at a return flow rate of 550 kg / h, and the obtained oil phase is the extractant which can be reused in the extraction tower;

[0124] (6) after the kettle bottom liquid at the bottom of the water tower cools the aqueous phase containing the extractant, the kettle bottom liquid at the bottom of the water tower reaches 40°C, and then the biological treatment in step S5 is performed;

[0125] (7) the extractant phase containing phenols is preheated to 115°C and then input into the upper part of the phenol tower, the extractant liquid (40°C) recovered in step (8) is returned to the top of the phenol tower at a return flow rate of 5000 kg / h to separate the phenolic substances and the extractant, the separated phenolic substances are discharged as the kettle liquid, and the separated extractant is the gas phase which is discharged from the top of the phenol tower;

[0126] The phenol column is of tray type, and is provided with a reboiler at the bottom. The feed of the extracting agent of the phenol column is above the uppermost tray;

[0127] The temperature at the top of the phenol column is 118°C, and the pressure is 0.02 MPaG. The temperature at the bottom of the phenol column is 220°C, and the pressure is 0.04 MPaG.

[0128] The reboiler of the phenol column uses high-pressure steam as heat source, with a pressure of 3.5 MPaG and a temperature of 250°C. Due to the large viscosity of the phenol oil in the kettle of the phenol column, the phenol oil is pressurized by a phenol column circulating pump and then sent to the reboiler of the phenol column, which uses high-pressure steam as heat source;

[0129] The kettle liquid of the phenol column is crude phenol, which is cooled to about 40°C after passing the detection (the mass content of phenol is greater than 90%) and then is subjected to the separation of step S4. The unqualified crude phenol is cooled to about 80°C and then is returned to the upper part of the phenol column.

[0130] (8) The extracted gas is first exchanged heat with the extracting phase containing phenol, and then is sequentially condensed and cooled to obtain the extracting agent liquid, part of which is returned to the extraction column, and the other part is returned to the top of the phenol column.

[0131] The tail gas generated at the top of the water column and the phenol column is input into a tail gas condenser for condensation treatment, and the obtained liquid is the extracting agent, and the obtained non-condensed gas is discharged from the system.

[0132] Step S4 includes the following steps:

[0133] (9) The qualified kettle liquid of the phenol column obtained in step (7) is input into the middle-upper part of the dehydration column for dehydration treatment, and the phenol water is collected at the top of the dehydration column and is discharged from the system after condensation;

[0134] (10) The kettle liquid of the dehydration column is input into the middle-upper part of the light component removal column to remove the light components, and the light components are collected at the top of the light component removal column and are discharged from the system after condensation;

[0135] (11) The kettle liquid of the light component removal column is input into the middle-upper part of the heavy component removal column to remove the heavy components, and the kettle liquid of the heavy component removal column is the heavy components, which are discharged from the system after condensation;

[0136] (12) The crude phenol after dehydration, light component removal and heavy component removal is collected at the top of the heavy component removal column, is input into the middle-upper part of the phenol column after condensation, and the phenol is separated, and the phenol is collected at the top of the phenol column and is discharged from the system after condensation;

[0137] (13) The kettle liquid of the phenol column is input into the middle-upper part of the o-cresol column to separate the o-cresol, and the o-cresol is collected at the top of the o-cresol column and is discharged from the system after condensation;

[0138] (14) The middle and upper part of the meta-cresol column is inputted by the liquid in the kettle of the meta-cresol column, and meta-cresol is separated out, the meta-cresol column is taken out at the top, condensed and discharged from the system, and the liquid in the kettle is mixed dimethyl phenol.

[0139] The dehydration column, the light component removal column, the heavy component removal column, the phenol column, the ortho-cresol column and the meta-cresol column are all plate columns, and each column is equipped with a reboiler at the bottom, and each reboiler uses high-pressure steam as a heat source;

[0140] The non-condensable gas remaining after the condensation of the top product of each column is sent to a vacuum unit after passing through a pressure control valve.

[0141] In step (9), sulfuric acid prepared for inputting into the extraction column in step (3) can be supplemented in the feed of the dehydration column, so that the pH value of the feed of the dehydration column is neutral;

[0142] The phenol water includes water and a small amount of phenolic substances, and is condensed to about 45℃, a part (80%) of which is refluxed to the top of the dehydration column, and the other part is mixed into the semicoke wastewater raw material in step S1 to adjust the water quality;

[0143] The liquid in the kettle of the dehydration column is water-removed crude phenol, a part of which is returned to the bottom of the dehydration column after being heated by the reboiler of the dehydration column, and the other part is inputted into the light component removal column;

[0144] The top temperature of the dehydration column is 65℃, the bottom temperature is 150℃, and the pressure is -0.08MPaG.

[0145] In step (10), the light components and a small amount of phenolic substances are taken out at the top of the light component removal column, and the top product is condensed to about 60℃, a part (98%) of which is refluxed to the top of the light component removal column, and the other part is collected;

[0146] The liquid in the kettle of the light component removal column is light component-removed crude phenol, a part of which is returned to the bottom of the light component removal column after being heated by the reboiler of the light component removal column, and the other part is inputted into the heavy component removal column;

[0147] The top temperature of the light component removal column is 127℃, the bottom temperature is 150℃, and the pressure is -0.08MPaG.

[0148] In step (11), the phenolic substances removed of heavy components are taken out at the top of the heavy component removal column, and are condensed to about 80℃, a part (60%) of which is refluxed to the top of the heavy component removal column, and the other part is inputted into the phenol column;

[0149] The liquid in the kettle of the heavy component removal column is heavy components, a part of which is returned to the bottom of the heavy component removal column after being heated by the reboiler of the heavy component removal column, and the other part is cooled to about 80℃ and then collected;

[0150] The top temperature of the heavy component removal column is 126℃, the bottom temperature is 196℃, and the pressure is -0.09MPaG.

[0151] In step (12), the phenol substance is taken out from the top of the phenol column, condensed to about 80°C, a part (94%) of which is refluxed to the top of the phenol column, and the other part is condensed to about 55°C and then collected;

[0152] The liquid at the bottom of the phenol column is crude phenol from which phenol is removed, a part of which is heated by the phenol column reboiler and then returned to the bottom of the phenol column, and the other part is input into the o-cresol column;

[0153] The temperature at the top of the phenol column is 114°C, the temperature at the bottom is 156°C, and the pressure is -0.09 MPaG.

[0154] In step (13), the o-cresol substance is taken out from the top of the o-cresol column, condensed to about 80°C, a part (91%) of which is refluxed to the top of the o-cresol column, and the other part is condensed to about 55°C and then collected;

[0155] The liquid at the bottom of the o-cresol column is crude phenol from which o-cresol is removed, a part of which is heated by the o-cresol column reboiler and then returned to the bottom of the o-cresol column, and the other part is input into the m,p-cresol column;

[0156] The temperature at the top of the o-cresol column is 120°C, the temperature at the bottom is 159°C, and the pressure is -0.09 MPaG.

[0157] In step (14), the m,p-cresol substance is taken out from the top of the m,p-cresol column, condensed to about 80°C, a part (84%) of which is refluxed to the top of the m,p-cresol column, and the other part is condensed to about 55°C and then collected;

[0158] The liquid at the bottom of the m,p-cresol column is mixed dimethylphenol, a part of which is heated by the mixed dimethylphenol column reboiler and then returned to the bottom of the mixed dimethylphenol column, and the other part is cooled to about 80°C and then collected;

[0159] The temperature at the top of the m,p-cresol column is 132°C, the temperature at the bottom is 165°C, and the pressure is -0.09 MPaG.

[0160] The phenol product collected above meets the requirements of the first-grade product of Coking Phenol (GB / T 6705-2008), the o-cresol and m,p-cresol products meet the requirements of the first-grade product of Coking Cresol (GB / T 2279-2008), and the content of dimethylphenol in the mixed dimethylphenol is not less than 80wt%.

[0161] In step S5, the following steps are included:

[0162] In step (15), the liquid at the bottom of the water column in step (6) is input into the conditioning pool to adjust the water quality, and then input into the sedimentation pool, flocculants or coagulants are added to the upstream side of the sedimentation pool to remove the emulsified oil and suspended solids in the wastewater;

[0163] (16) The effluent of the sedimentation tank is input into the hydrolysis acidification tank to perform hydrolysis acidification reaction, so as to improve the biodegradability;

[0164] (17) The effluent of the hydrolysis acidification tank is input into the internal circulation biological reaction tank to perform denitrification, nitrification and sedimentation treatment in sequence, so as to degrade pollutants and simultaneously remove nitrogen and phosphorus, and the wastewater is discharged after mud-water separation;

[0165] (18) The effluent of the internal circulation biological reaction tank is input into the AO tank to perform anoxic treatment and aerobic treatment in sequence, and then is input into the secondary sedimentation tank to perform sludge sedimentation;

[0166] (19) The supernatant of the secondary sedimentation tank is subjected to coagulation treatment in the coagulation reaction tank, and then is subjected to filtration, ozone oxidation treatment and rapid filtration to obtain effluent, which can be used as circulating water.

[0167] In step (17), in the internal circulation biological reaction tank, microorganisms can rapidly adsorb most of the soluble organic matter in the wastewater through the rapid transfer mechanism of enzymes during the water inlet and denitrification stages, and experience a high-load substrate rapid accumulation process, which can play a good buffering role on the water quality, water quantity, pH and toxic and harmful substances of the influent, and can inhibit the growth of filamentous bacteria, thereby effectively preventing sludge bulking.

[0168] In the main reaction zone stage, a lower-load substrate degradation process is experienced to complete the degradation of organic matter in the wastewater. The internal circulation biological reaction tank integrates the functions of biochemical reaction, sedimentation and drainage, and the degradation of pollutants is a plug-flow process in time. Microorganisms are in a periodic change of aerobic, anoxic and anaerobic states, so as to achieve the removal of pollutants, and also have good nitrogen and phosphorus removal functions. The decanter operates according to the set program, and the clear water flows into the secondary sedimentation tank, and the residual sludge at the bottom is discharged by the sludge discharge pump.

[0169] In step (18), the DO in the anoxic section of the front section of the AO tank is not more than 0.2 mg / L, and the DO in the aerobic section of the rear section is 2-4 mg / L.

[0170] In step (19), caustic soda is added for coagulation treatment to adjust the pH value, and water treatment agents PFS, PAM, ferrous sulfate and oxidizing agents (hydrogen peroxide and sodium hypochlorite) are added to further reduce the COD and SS of the wastewater.

[0171] Comparative Example 1

[0172] The method for recycling and comprehensively treating semi-coke wastewater provided in the comparative example is the same as that in Example 1, except that after the oil removal in step S1, steps S2, S3, S4 and S5 are not performed, and the water phase obtained in step S1 is directly subjected to chemical oxidation treatment by using the method described in CN202111507258.7.

[0173] (1) Adding iron powder to the deoiled semi-coke wastewater, the dosage of iron powder is 10000 mg / L, then air aeration oxidation, the treatment temperature is 40℃, the treatment time is 24h, to obtain the treated water A;

[0174] (2) Using 30% sulfuric acid solution, the pH of the treated water A is adjusted to 2.5-5, after precipitation, the supernatant is obtained as the treated water B;

[0175] (3) Adding iron powder and hydrogen peroxide to the treated water B to carry out electro-Fenton reaction, the reaction time is 2h, to obtain the treated water C;

[0176] The electrode of electro-Fenton reaction is graphite cathode and graphite anode, the current density is 30mA / cm 2 , the dosage of iron powder is 15000 mg / L; the mass fraction of hydrogen peroxide is 30%, the dosage is 3% by volume;

[0177] (4) Using calcium oxide, the pH of the treated water C is adjusted to 8-11, adding flocculant PAC for flocculation and precipitation, the treatment time is 24h, then the treated water is obtained.

[0178] The phenolic substances in the semi-coke wastewater cannot be recovered after the treatment of the comparative example, the additional value of this part cannot be created, and the consumption of chemical reagents is large, the overall operation cost is 15% higher than that of example 1.

[0179] Example 2

[0180] The method for recycling and comprehensively treating semi-coke wastewater provided in the example is the same as that in example 1, the difference lies in that the oil removal treatment in step S1 comprises in turn first standing treatment, first separation treatment, second separation treatment and second standing treatment; in the first standing treatment, the wastewater is input into a first standing tank for standing, preliminary sedimentation, light oil floating, heavy oil and oil residue sinking, and water phase in the middle part; the water phase in the middle part is input into a first separator for first separation treatment;

[0181] A first agitator is arranged in the first separator for agitating the wastewater and capturing oil droplets in the water;

[0182] The water phase obtained from the first separator is input into a second separator for second separation treatment, and a second agitator is arranged in the second separator for agitating the wastewater and capturing oil droplets in the water;

[0183] The water phase obtained from the second separator is input into a second standing tank for second standing treatment.

[0184] The top of the first standing tank, the first separator, the second separator and the second standing tank is provided with a light oil outlet and connected with a light oil pipeline, to discharge the light oil separated from each container and collected in a light oil tank;

[0185] The bottom of the first static tank, the first separator, the second separator and the second static tank are provided with heavy oil outlets and connected with heavy oil pipelines to discharge the heavy oil and oil residue separated from each container and collected in a heavy oil tank.

[0186] The middle part of the first static tank, the first separator, the second separator and the second static tank are provided with water phase outlets and connected in sequence according to the order of the containers to process the waste water in stages and facilitate subsequent extraction treatment.

[0187] The time length of the first static treatment and the second static treatment is 70h; the rotating speed of the agitator of the first separator and the second separator is 80r / min, the treatment time length is 20h, the temperature is 40℃ and the pressure is 0.05MPaG;

[0188] The bottom of the first static tank, the first separator, the second separator and the second static tank are provided with hot coil pipes for inputting low-pressure steam (60℃, 0.5MPaG) to promote oil-water separation. The static tank, the separator and the agitator are conventional devices.

[0189] The light oil and heavy oil obtained in this example have the following indexes:

[0190] Density kg / m 3 ]] Viscosity mPa.s Flash point °C Toluene insolubles % H / C ratio Light oils 900～980 2 (15 max) 155 0.18 1.45 Heavy oils 1020～1060 4.5 (18.5 max) 147 0.46 1.16

[0191] Compared with example 1, the oil substances contained in the raw material of the semi-coke wastewater are greatly reduced by the multi-stage oil-water separation treatment of this example, the influence on the subsequent equipment is greatly reduced, the efficiency of the subsequent deacidification, deamination, extraction and extractant recovery is improved, and the influence of the oil in the wastewater on the above-mentioned operations is reduced.

[0192] Example 3

[0193] The method for recycling and comprehensively treating semi-coke wastewater provided in this example is the same as that in example 1, and the difference lies in that the water phase obtained after oil removal in step (1) is divided into two parts, one part is preheated to form a hot feed and enters the middle and upper part of the deacidification tower, and the other part is a cold feed and enters the top of the deacidification tower; steam is input at the bottom of the deacidification tower to remove the acidic gas in the water phase, and is discharged from the top of the deacidification tower.

[0194] The cold feed is cooled to 40℃ by cooling water and then input into the deacidification tower, and the cold feed accounts for 25wt% of the total feed.

[0195] The deacidification tower of the embodiment has two feeds, hot feed and cold feed, the cold feed is fed above the packing, the acid gas discharged from the top of the deacidification tower includes non-condensable gas composed of H2S, CO2 and a small amount of water vapor, ammonia and the like, the cold feed is used to absorb ammonia in the ascending gas stream in the deacidification tower, so that the high-concentration H2S and CO2 acid mixed gas is obtained at the top of the deacidification tower, the ammonia in the waste water is retained in the waste water as much as possible, and is reserved for removal by the deamination tower, and meanwhile the quality of the gas collected at the top of the deacidification tower is improved, and the ammonia in the collected gas is prevented from reacting with a small amount of water in the acid gas to crystallize; meanwhile, the cold feed also reduces the moisture in the collected gas.

[0196] Embodiment 4

[0197] The method for recycling and comprehensively treating semicoke waste water provided by the embodiment is the same as that of embodiment 1, and the difference lies in that the following extraction tower is used in the embodiment, as shown in Figures 2-4 The rotating packing layer 2 is below the moving packing layer 3 in the extraction tower 1.

[0198] The center of the rotating packing layer 2 is provided with a stirring shaft 8, which is driven to rotate by a motor at the bottom of the extraction tower 1; the moving packing layer 3 includes a center support 9 and a support rail 10 spirally arranged outside the center support 9, a plurality of packing cages 11 are connected with each other to form a chain shape, and move along the support rail 10 from bottom to top, the side wall of the extraction tower 1 corresponding to the moving packing layer 3 is provided with a hollow interlayer 12, a plurality of rotating wheels 13 are arranged in the interlayer 12, which are used to guide the packing cages 11 at the top of the moving packing layer 3 into the interlayer 12 and make them move downward, and then pass through the bottom of the interlayer 12 and move upward along the support rail 10 again; the top of the interlayer 12 is provided with a spraying device for cleaning the packing cages 11 moving into the interlayer 12.

[0199] The top of the extraction tower 1 is provided with an extract outlet 4, the upper part is provided with a waste water inlet 5, the bottom is provided with an extractant inlet 6 and a still liquid outlet 7, which are respectively used for discharging the extractant containing phenols, inputting the semicoke waste water, inputting the extractant and discharging the still bottom liquid.

[0200] The rotating packing layer 2 includes the stirring shaft 8 and a packing part 14, the packing part 14 is spirally wound along the outer side of the stirring shaft 8 from top to bottom, the bottom of the stirring shaft 8 passes through the bottom of the extraction tower 1 and is connected with a motor below the extraction tower 1 outside, which is used to drive the rotating of the stirring shaft 8 and the packing part 14;

[0201] The inner side of the packing part 14 is fixed on the stirring shaft 8, the outer layer extends to the inner wall of the extraction tower 1, and there is an interval between the outer layer and the inner wall of the extraction tower 1.

[0202] The filler part 14 is in the form of a mesh cage, filled with filler inside, and is provided with a plurality of partition walls uniformly distributed along the length direction of the filler part 14, which divide the filler part 14 into a plurality of sections, each of which is filled with filler.

[0203] The upper surface, lower surface and outer side surface of the filler part 14 are in the form of alternately arranged corrugated strips and flat strips, and the flat strips are at a height between the crests and troughs of the corrugated strips. This special surface form can stabilize the filler particles inside each section of the filler part 14, and can also increase the contact area between the filler part 14 and the material flow in the extraction tower 1, thereby improving the extraction effect.

[0204] The extractant inlet 6 is arranged below the lowermost filler of the rotating filler layer 2, and the tank liquid outlet 7 is arranged below the extractant inlet 6.

[0205] The moving filler layer 3 and the rotating filler layer 2 are concentrically arranged with the extraction tower 1, that is, the central support column 9 and the stirring shaft 8 are on the same vertical line as the axis of the extraction tower 1; the top of the central support column 9 is fixedly connected to the top surface of the extraction tower 1;

[0206] The support guide rail 10 includes an inner support strip 17 and an outer support strip 18 spirally wound on the outer side surface of the central support column 9, the inner support strip 17 closely abuts the outer side surface of the central support column 9, and a plurality of rolling cross bars 19 are connected between the inner support strip 17 and the outer support strip 18, which are horizontally arranged to support the filler cage 11;

[0207] The inner wall of the extraction tower 1 is provided with a cleaning inlet 20 corresponding to the position of the top port of the support guide rail 10, and is provided with a cleaning outlet 21 corresponding to the position of the bottom port of the support guide rail 10, the cleaning inlet 20 and the cleaning outlet 21 are on the same vertical line, and the interlayer 12 communicates with the support guide rail 10 through the cleaning inlet 20 and the cleaning outlet 21.

[0208] The outer support strip 18 is arranged on the inner wall of the extraction tower 1, and the two ends of the rolling cross bar 19 are rotatably connected to the inner support strip 17 and the outer support strip 18, respectively, when the filler cage 11 moves on the support guide rail 10, it can drive the rolling cross bar 19 to rotate, thereby reducing the friction resistance, and the rotation of the rolling cross bar 19 does not require electric power driving, thereby saving energy consumption.

[0209] The first rotating wheel 13 is arranged in the interlayer 12 corresponding to the position of the cleaning inlet 20, and the first rotating wheel 13 has the same height as the cleaning inlet 20; the second rotating wheel 13 is arranged in the interlayer 12 corresponding to the position of the cleaning outlet 21, and the second rotating wheel 13 has the same height as the cleaning outlet 21;

[0210] A plurality of third rotating wheels 13 are arranged between the first rotating wheel 13 and the second rotating wheel 13, and the rotating shafts of all the rotating wheels 13 pass through the side wall of the interlayer 12 and are respectively connected to corresponding rotating motors outside the extraction tower 1.

[0211] The outer side surface of each rotating wheel 13 is uniformly provided with a plurality of protruding teeth along the circumferential direction of the rotating wheel 13, and the protruding teeth are used for being inserted into the packing cage 11 and driving the packing cage 11 to move.

[0212] The spraying device inside the interlayer 12 is arranged above the first rotating wheel 13, and is used for spraying the extraction agent to the packing cage 11 moving into the interlayer 12, so as to clean the packing cage 11.

[0213] The wastewater inlet 5 is located above the moving packing layer 3.

[0214] Each surface of the packing cage 11 is a plane, and the connection between adjacent packing cages 11 is a flexible connection, so that when the rotating wheel 13 drives the packing cage 11 to move, the chain-shaped packing cage 11 combination can spiral up along the spiral-shaped supporting guide rail 10. The width of the packing cage 11 is slightly smaller than the length of the rolling cross rod 19. The semi-coke wastewater enters from the wastewater inlet 5 and is preferentially dropped on the packing cage 11 of the moving packing layer 3, so that the packing cage 11 receives more oil substances in the wastewater and is more easily contaminated to affect the extraction effect. The packing cage 11 of the present application can continuously move upward along the supporting guide rail 10, is introduced into the interlayer 12 by the rotating wheel 13 in the interlayer 12, and is cleaned. The cleaned packing cage 11 is moved out from the cleaning outlet 21. The top port and the bottom port of the supporting guide rail 10 are located on the same vertical line, and the packing cage 11 returns to the bottom port of the supporting guide rail 10 again. The cleaned extraction agent in the interlayer 12 flows out from the cleaning outlet 21 and flows down along the inner wall of the extraction tower 1, and basically does not pollute the rotating packing layer 2 below. Alternatively, an outlet is arranged on the outer wall of the interlayer 12 to lead the cleaned extraction agent out of the extraction tower 1.

[0215] The outer side surface of the central support column 9 is further provided with a tray 22, the tray 22 is located below the supporting guide rail 10 and spirally surrounds the central support column 9, that is, the tray 22 is arranged between the adjacent supporting guide rails 10 in the upper and lower layers.

[0216] The upper surface of the tray 22 is smooth and uniformly densely provided with large through holes 23 and small through holes 24, the hole diameter of the large through hole 23 is larger than that of the small through hole 24, the large through hole 23 is used for the wastewater on the tray 22 to flow down to the next layer of packing cage 11, and the small through hole 24 is used for allowing the rising gas flow to pass through.

[0217] The outer side of the tray 22 is provided with an overflow weir 16, and has a gap with the inner wall of the extraction tower 1.

[0218] The upper part of the extraction tower 1 is provided with a packing cage 11 matched with the tray 22 to improve the extraction effect. The wastewater flowing from the packing cage 11 flows onto the lower tray 22, and a part of the wastewater flows to the next layer of the packing cage 11 through the large through hole 23. The gas velocity of the small through hole 24 is large, allowing the upward gas flow to pass through and contact the wastewater on the tray 22 for extraction. Since the tray 22 has a smooth surface spiraling downward, the wastewater forms a liquid film on the upper surface of the tray 22 and flows downward, which is beneficial to improve the extraction efficiency of the tray 22.

[0219] The top of the extraction tower 1 is provided with a tail gas outlet 15 above the extract outlet 4 for discharging the exhaust gas inside the extraction tower 1.

[0220] The packing used in the embodiment is θ ring.

[0221] The pH value of the produced water after treatment in the embodiment is 6-8, and the benz(a)pyrene is 0.03 μg / L. The other indicators are as follows:

[0222] Pollutant item Limit (mg / L) Pollutant item Limit (mg / L) Suspended solids 70 Petroleum oils 2.5 Chemical oxygen demand COD cr ]] 150 Volatilised phenols 0.30 Ammonia nitrogen 25 Sulphides 0.50 five-day biochemical oxygen demand BOD5 30 Benzene 0.10 Total nitrogen 50 Cyanides 0.20 Total phosphorus 3.0 Polycyclic aromatic hydrocarbons (PAHs) 0.20

[0223] The content of the crude phenol (mass fraction) in the tower kettle liquid of the extraction tower of the embodiment is as follows: phenol 0.000006, o-dihydroxybenzene not detected, m-dihydroxybenzene 0.000003, p-dihydroxybenzene 0.000004, and methyl isobutyl ketone 0.020801. The extraction effect is good.

[0224] The content of the crude phenol (mass fraction) in the tower kettle liquid of the extraction tower of the embodiment 1 is as follows: phenol 0.000035, o-dihydroxybenzene 0.000016, m-dihydroxybenzene 0.000028, p-dihydroxybenzene 0.000031, and methyl isobutyl ketone 0.053067.

Claims

1. A method for resource recovery and comprehensive treatment of blue- carbon wastewater, characterized in that, The method comprises the following steps: S1: treating the semi-coke wastewater after pretreatment by oil removal treatment to separate light oil, water phase, heavy oil and oil residue; S2: extracting the phenolic substances in the water phase obtained in step S1 to obtain an extract phase containing phenolic substances and a water phase containing extractant; S3: separately treating the extract phase containing phenolic substances and the water phase containing extractant to recover their extractants and recycle them to the extraction treatment in step S2; and separating to obtain phenolic substances and wastewater; S4: separately obtaining phenol, o-cresol, m / p-cresol and mixed dimethyl phenol by three times of separation of the phenolic substances obtained in step S3; S5: performing biochemical treatment on the wastewater obtained in step S3 to obtain product water; The extraction column used in step S2 is provided with a rotating packing layer and a moving packing layer, and the rotating packing layer is below the moving packing layer; The center of the rotating packing layer is provided with a stirring shaft, which is driven to rotate by a motor at the bottom of the extraction column; the moving packing layer comprises a center support and a support rail spirally arranged outside the center support, a plurality of packing cages are connected with each other to form a chain shape, and move along the support rail from bottom to top; the side wall of the extraction column corresponding to the moving packing layer is provided with a hollow interlayer, a plurality of rotating wheels are arranged in the interlayer, and the rotating wheels are used to guide the packing cages at the top of the moving packing layer into the interlayer and move downward, and then pass out from the bottom of the interlayer and move upward along the support rail again; a spraying device is arranged at the top of the interlayer, and is used to clean the packing cages moving into the interlayer; The top of the extraction column is provided with an extract outlet, the upper portion is provided with a wastewater inlet, and the bottom is provided with an extractant inlet and a kettle liquid outlet, which are respectively used for discharging the extractant containing phenolic substances, inputting the semi-coke wastewater, inputting the extractant and discharging the kettle bottom liquid; The rotating packing layer comprises a stirring shaft and a packing part, the packing part is spirally wound along the outer side of the stirring shaft from top to bottom, the inner side of the packing part is fixed on the stirring shaft, the outer layer extends to the inner wall of the extraction column and leaves an interval between the inner wall of the extraction column, the packing part is in the form of a mesh cage, and the inside is filled with packing.

2. The method for resource recovery and comprehensive treatment of semicoke wastewater according to claim 1, characterized in that, The oil removal treatment in step S1 comprises first-level standing treatment, first-level separation treatment, second-level separation treatment and second-level standing treatment in sequence; in the first-level standing treatment, the wastewater is input into a first standing tank to stand and preliminarily settle, the light oil floats up, the heavy oil and oil residue sink down, and the water phase is in the middle part; the water phase in the middle part is input into a first separator for first-level separation treatment; A first stirrer is arranged in the first separator, which is used to stir the wastewater and capture oil droplets in the water; The water phase obtained by the first separator is input into a second separator for second-level separation treatment, and a second stirrer is arranged in the second separator, which is used to stir the wastewater and capture oil droplets in the water; The water phase obtained by the second separator is input into a second standing tank for second-level standing treatment.

3. The method for resource recovery and comprehensive treatment of semicoke wastewater according to claim 1, characterized in that, Step S2 comprises the following steps: (1) the water phase after oil removal obtained in step S1 is divided into two parts, one part is preheated to form hot feed and is input into the upper middle part of the deacidification tower, and the other part is cold feed and is input into the top of the deacidification tower; steam is input into the bottom of the deacidification tower to remove acidic gases in the water phase, and the acidic gases are discharged from the top of the deacidification tower; (2) The kettle bottom liquid of the deacidification tower and the alkali solution are input into the middle and upper part of the deamination tower, the bottom of the deamination tower is input with medium pressure steam as heat source, deamination treatment is carried out, and rich ammonia gas is collected from the top of the deamination tower; (3) The kettle bottom liquid of the deamination tower and the acid solution are input into the top of the extraction tower, the extractant is input into the bottom of the extraction tower, the phenolic substances in the extraction wastewater are extracted, the extraction phase containing phenolic substances is discharged from the top of the extraction tower, and the kettle liquid of the extraction tower is the water phase containing the extractant.

4. The method for resource recovery and comprehensive treatment of semicoke wastewater according to claim 3, characterized in that, In step (1), the cold feed is cooled to 35-40℃ by cooling water, the hot feed is preheated to 45-50℃, and then input into the deacidification tower; the cold feed accounts for 25-30wt% of the total feed; the medium pressure steam is input into the bottom of the deacidification tower; the kettle bottom liquid temperature of the deacidification tower is 150-160℃, which can be used to preheat the hot feed of the deacidification tower; In step (2), the alkali solution is sodium hydroxide solution with a concentration of 30-35wt%; the rich ammonia gas is 140-150℃, which can be used to preheat the hot feed of the deacidification tower; In step (3), the acid solution is 98% sulfuric acid solution, the extractant is selected from methyl isobutyl ketone or diisopropyl ether, and the feed ratio of the kettle bottom liquid of the deamination tower and the acid solution to the extractant is (2.95-3.00):

1.

5. The method for resource recovery and comprehensive treatment of semicoke wastewater according to claim 3, characterized in that, Between step (2) and step (3), there is also a step of ammonia gas recovery treatment: (a) The rich ammonia gas is subjected to primary gas-liquid separation to obtain ammonia gas and condensate, the condensate is collected after condensation; the ammonia gas is 130-140℃, subjected to secondary gas-liquid separation after condensation, and ammonia gas and condensate are obtained, the condensate is collected after condensation; the ammonia gas is 90-100℃, subjected to tertiary gas-liquid separation after condensation, and ammonia gas and condensate are obtained, the condensate is collected, and the ammonia gas is reduced to 30-40℃; (b) The ammonia gas obtained by the tertiary gas-liquid separation is mixed with desalted water to prepare ammonia water; (c) A part of the condensate obtained by the three times of gas-liquid separation in step (a) is returned to the top of the deamination tower, and the rest is reused in the raw coke-oven wastewater of step S1 to adjust the water quality.

6. The method for resource recovery and comprehensive treatment of semicoke wastewater according to claim 1, characterized in that, Step S3 includes the following steps: (4) The water phase containing the extractant is cooled and then input into the middle of the water tower for oil-water separation; (5) The extractant is collected from the top of the water tower and input into an oil-water separator, the water phase returned from the top of the water tower is obtained by separation, and the oil phase obtained is the extractant which can be reused in the extraction tower; (6) The kettle bottom liquid at the bottom of the water tower is cooled after cooling the water phase containing the extractant, and then subjected to the biochemical treatment of step S5; (7) The extraction phase containing phenolic substances is preheated and then input into the upper part of the phenol tower, the recovered extractant is input into the top of the phenol tower, the separation of phenolic substances and the extractant is carried out, the separated phenolic substances are discharged as kettle liquid, and the separated extractant is discharged as gas phase from the top of the phenol tower; (8) The extracted gas is first heat exchanged with the extraction phase containing phenolic substances, and then subjected to condensation and cooling in sequence to obtain extractant liquid, a part of which is reused in the extraction tower, and the other part is returned to the top of the phenol tower.

7. The method for resource recovery and comprehensive treatment of semicoke wastewater according to claim 6, characterized in that, In step (5), the flow rate of the water phase returned to the water tower is 550-650kg / h, and a reboiler is arranged at the bottom of the water tower; In step (7), a reboiler is arranged at the bottom of the phenol tower; The phenol-containing extraction phase is preheated to 115-125 DEG C, the extraction agent of the phenol column overhead reflux is 40-50 DEG C, and the reflux amount is 5000-5200 kg / h.

8. The method for resource recovery and comprehensive treatment of semicoke wastewater according to claim 6, characterized in that, Step S4 comprises the following steps: (9) The phenol column qualified kettle liquid obtained in step (7) is input into the middle upper part of the dehydration column to perform dehydration treatment, phenol water is taken out from the top of the dehydration column, and is discharged from the system after being condensed; (10) The kettle liquid of the dehydration column is input into the middle upper part of the light component removal column to remove light components, light components are taken out from the top of the light component removal column, and are discharged from the system after being condensed; (11) The kettle liquid of the light component removal column is input into the middle upper part of the heavy component removal column to remove heavy components, the heavy component removal column kettle liquid is heavy components, and is discharged from the system after being condensed; (12) The crude phenol after dehydration, light component removal and heavy component removal is taken out from the top of the heavy component removal column, is input into the middle upper part of the phenol column after being condensed, phenol is separated, phenol is taken out from the top of the phenol column, and is discharged from the system after being condensed; (13) The phenol column kettle liquid is input into the middle upper part of the o-cresol column to separate o-cresol, o-cresol is taken out from the top of the o-cresol column, and is discharged from the system after being condensed; (14) The o-cresol column kettle liquid is input into the middle upper part of the m,p-cresol column to separate m,p-cresol, m,p-cresol is taken out from the top of the m,p-cresol column, and is discharged from the system after being condensed, and the kettle liquid is mixed dimethylphenol.

9. The method for resource recovery and comprehensive treatment of semicoke wastewater according to claim 8, characterized in that, In step (9), the phenol water comprises water and a small amount of phenolic substances, after the phenol water is condensed, part of it is refluxed to the top of the dehydration column, and the other part is mixed into the semicoke wastewater raw material of step S1 to adjust the water quality; the dehydration column kettle liquid is crude phenol after water removal, part of which is returned to the bottom of the dehydration column after being heated by the dehydration column reboiler, and the other part is input into the light component removal column; In step (10), light components and a small amount of phenolic substances are taken out from the top of the light component removal column, after the taken-out material is condensed, part of it is refluxed to the top of the light component removal column, and the other part is discharged from the system or collected; the light component removal column kettle liquid is crude phenol after light component removal, part of which is returned to the bottom of the light component removal column after being heated by the light component removal column reboiler, and the other part is input into the heavy component removal column; In step (11), phenolic substances after heavy component removal are taken out from the top of the heavy component removal column after being condensed, part of which is refluxed to the top of the heavy component removal column, and the other part is input into the phenol column; The heavy component removal column kettle liquid is heavy components, part of which is returned to the bottom of the heavy component removal column after being heated by the heavy component removal column reboiler, and the other part is cooled and then discharged from the system or collected; In step (12), phenol substances are taken out from the top of the phenol column after being condensed, part of which is refluxed to the top of the phenol column, and the other part is condensed and then discharged from the system or collected; the phenol column kettle liquid is crude phenol after phenol removal, part of which is returned to the bottom of the phenol column after being heated by the phenol column reboiler, and the other part is input into the o-cresol column; In step (13), o-cresol substances are taken out from the top of the o-cresol column after being condensed, part of which is refluxed to the top of the o-cresol column, and the other part is condensed and then discharged from the system or collected; the o-cresol column kettle liquid is crude phenol after o-cresol removal, part of which is returned to the bottom of the o-cresol column after being heated by the o-cresol column reboiler, and the other part is input into the m,p-cresol column; In step (14), meta-p-cresol is obtained from the top of the meta-p-cresol column, and after condensation, part of the meta-p-cresol is returned to the top of the meta-p-cresol column, and the other part is discharged from the system or collected after condensation; the liquid in the kettle of the meta-p-cresol column is mixed cresol, part of which is returned to the bottom of the mixed cresol column after being heated by the mixed cresol column reboiler, and the other part is collected after cooling.

10. The method for resource recovery and comprehensive treatment of semicoke wastewater according to claim 6, characterized in that, In step S5, the following steps are included: (15) The kettle bottom liquid of the water column in step (6) is input into the conditioning pool to adjust the water quality, and then input into the sedimentation pool to remove emulsified oil and suspended solids in the wastewater; (16) The water produced by the sedimentation pool is input into the hydrolysis acidification pool to carry out hydrolysis acidification reaction to improve the biodegradability; (17) The water produced by the hydrolysis acidification pool is input into the internal circulation biological reaction pool to carry out denitrification, nitrification and sedimentation treatment in turn to degrade pollutants and remove nitrogen and phosphorus at the same time, and the wastewater is separated from the sludge and then discharged; (18) The water produced by the internal circulation biological reaction pool is input into the AO pool to carry out anoxic treatment and aerobic treatment in turn, and then input into the secondary sedimentation pool to carry out sludge sedimentation; (19) The supernatant of the secondary sedimentation pool is subjected to coagulation treatment in the coagulation reaction pool, and then subjected to filtration, ozone oxidation treatment and rapid filtration to obtain the produced water, which can be used as reclaimed water.

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