Mother liquor treatment system after evaporation of coal chemical industry wastewater

Abstract

The utility model belongs to the technical field of wastewater treatment, and relates to a mother liquor treatment system after evaporation of coal chemical wastewater, which comprises a vacuum evaporation unit, a dehydration drying unit, a separation thickener and a drum dryer, the vacuum evaporation unit is communicated with the dewatering and drying unit through the separation thickener; the separation thickener is also communicated with the drum dryer; and the vacuum evaporation unit is also respectively communicated with the dewatering and drying unit and the roller dryer. By arranging the vacuum evaporation unit, the dewatering and drying unit, the separation thickener and the drum dryer, the treatment capacity of evaporated mother liquor is improved, the application range of COD (Chemical Oxygen Demand) is widened, and the treatment requirement is met.

Description

Technical Field

[0001] The utility model belongs to the technical field of wastewater treatment and relates to a system for treating mother liquor after evaporation of coal chemical wastewater. Background Art

[0002] In recent years, with the improvement of environmental protection requirements and the long-term development of enterprises, it has become a must for coal chemical enterprises to use "zero emission" water treatment technology for wastewater discharged during production. The "zero emission" water treatment process mainly includes three main treatment processes: softening treatment, membrane treatment, and concentrated water evaporation and crystallization. Among them, the commonly used treatment processes for concentrated water evaporation and crystallization are multi-effect evaporation and MVR evaporation and crystallization. However, these evaporation and crystallization methods will produce evaporation mother liquor when producing sodium chloride and sodium sulfate crystal salt products that meet the requirements. At present, these evaporation mother liquors are dispatched externally. However, due to the characteristics of high salt and high COD, the evaporation mother liquor usually has a salt content of more than 100,000 mg / L and a COD concentration of more than 10,000 mg / L, and is also mixed with sodium sulfate crystal salt solid particles and viscous substances. If it is directly discharged, it will pollute the environment, and the mixed sodium sulfate crystal salt will cause loss and waste. Therefore, it is necessary to treat the evaporation mother liquor.

[0003] At present, the commonly used method for treating the mother liquor after evaporation is to use a single drying equipment for treatment, such as spray drying, rake drying, drum drying and vacuum scraper drying equipment. Reference to the Chinese patent document with announcement number CN214270569U, which discloses a zero-emission disposal system for evaporation mother liquor, including an evaporation mother liquor collection tank, an intermittent reaction tank, a solid-liquid separation device, a liquid storage tank, a low-temperature evaporation concentration device and a water washing spray tower arranged in sequence, which can effectively reduce the amount of evaporation mother liquor and achieve zero pollution discharge during the treatment process. Although this method can completely realize the treatment of mother liquor, its biggest drawback is that the mother liquor treatment volume is small, generally not exceeding 1m 3 / h, COD has a narrow adaptability range and is only applicable to the mother liquor of COD components that are difficult to volatilize; it cannot meet the 3-5m 3 / h processing capacity and the demand for more volatile COD components in the mother liquor. Utility Model Content

[0004] Aiming at the technical problems that the existing treatment method for the mother liquor after evaporation has a small treatment capacity and a narrow COD adaptability range, the utility model provides a system for treating the mother liquor after evaporation of coal chemical wastewater.

[0005] The utility model increases the processing capacity of the mother liquor after evaporation by arranging a vacuum evaporation unit, a dehydration drying unit, a separation thickener and a drum dryer, broadens the application range of COD and meets the processing needs.

[0006] In order to achieve the above purpose, the technical solution adopted by the utility model is:

[0007] A system for treating mother liquor after evaporation of coal chemical wastewater, comprising a vacuum evaporation unit, a dehydration drying unit, a separation thickener and a drum dryer;

[0008] The vacuum evaporation unit is connected to the dehydration and drying unit via a separation thickener; the separation thickener is also connected to a drum dryer; the vacuum evaporation unit is also connected to the dehydration and drying unit and the drum dryer respectively.

[0009] It is further defined that the vacuum evaporation unit includes a heat exchanger, a heating chamber and a vacuum evaporator; the heat exchanger is connected to the heating chamber; one end of the heating chamber returns to the other end of the heating chamber after passing through the vacuum evaporator to form a mother liquid circulation pipeline; the vacuum evaporator is respectively connected to the dehydration and drying unit, the separation thickener and the drum dryer.

[0010] It is further defined that a salt leg communicating with the interior of the vacuum evaporator is disposed at the bottom of the vacuum evaporator, and the salt leg is communicated with the dehydration and drying unit.

[0011] It is further defined that the heating chamber is externally connected with a steam inlet pipe, and the steam inlet pipe is connected with the heat exchanger and the drum dryer respectively after passing through the heating chamber and the vacuum evaporator.

[0012] It is further defined that a circulation pump is provided on the mother liquid circulation pipeline; the circulation pump is located between the vacuum evaporator and the heating chamber.

[0013] It is further defined that the dehydration and drying unit includes a centrifuge and a fluidized dryer which are connected in sequence, and the centrifuge is connected to the salt leg and the separation thickener respectively.

[0014] It is further defined that the system for treating mother liquor after evaporation of coal chemical wastewater also includes a condenser connected to the drum dryer.

[0015] It is further defined that the coal chemical wastewater evaporation mother liquor treatment system also includes a vacuum pump connected to the condenser.

[0016] Compared with the prior art, the utility model can process a larger amount of water and has a wide range of water quality adaptability; in addition, it also has the advantages of easy operation and low cost, which are specifically manifested in:

[0017] 1. The utility model first uses a vacuum evaporation unit to concentrate the evaporated mother liquor, which not only greatly reduces the amount of discharged mother liquor, but also takes away most of the volatile components and organic matter in the mother liquor; when it is further processed through a separation thickener, a dehydration drying unit and a drum dryer, the processing volume is reduced, the volatile components of the water quality fluctuate little, and a high-yield evaporated mother liquor can be processed to meet actual processing requirements.

[0018] 2. In the utility model, a drum dryer (single or multiple in parallel) is used to economically and effectively dry the mother liquor discharged from the vacuum evaporation device, which is not only easy to operate but also has low processing cost.

[0019] 3. In the utility model, a salt leg connected to the inside of the vacuum evaporator is provided at the bottom of the vacuum evaporator, so that part of the salt is precipitated after vacuum evaporation and concentration, and the salt material that is easier to precipitate is gathered in the salt leg, and the salt material that is difficult to precipitate is sent to the separation thickener through the external discharge mother liquor, and then the dehydration and drying unit is used to further precipitate and concentrate the salt material, thereby realizing the graded recovery and utilization of salt.

[0020] 4. In the utility model, the steam inlet pipe is connected to the heat exchanger and the drum dryer respectively after passing through the heating chamber and the vacuum evaporator. The steam condensate after cooling can be used to preheat the evaporation mother liquor before entering the vacuum evaporation unit, and the flash steam (or low-grade steam) in the vacuum evaporation unit can be used as the heat source of the drum dryer for heating and drying, thereby realizing heat recovery and reducing costs.

[0021] 5. In the utility model, a vacuum pump is connected to the condenser, and a vacuum is drawn by the vacuum pump to realize negative pressure operation of the condenser, thereby reducing energy consumption. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 A schematic diagram provided for the utility model;

[0023] in:

[0024] 10-heat exchanger; 20-mother liquor inlet pipe; 30-steam inlet pipe; 40-heating chamber; 50-mother liquor circulation pipeline; 60-salt leg; 70-circulation pump; 80-vacuum evaporator; 90-separation thickener; 100-first slurry pump; 110-second slurry pump; 120-centrifuge; 130-fluidized bed dryer; 140-drum dryer; 150-condenser; 160-vacuum pump; 170-liquid outlet pipe. DETAILED DESCRIPTION

[0025] The preferred embodiments of the present invention are described in detail below in conjunction with the accompanying drawings so that the advantages and features of the present invention can be more easily understood by those skilled in the art, thereby making a clearer and more definite definition of the protection scope of the present invention.

[0026] Example 1

[0027] See also Figure 1The present embodiment provides a system for treating mother liquor after evaporation of coal chemical wastewater, comprising a vacuum evaporation unit, a dehydration and drying unit, a separation thickener 90 and a drum dryer 140; the vacuum evaporation unit is connected to the dehydration and drying unit via the separation thickener 90; the separation thickener 90 is also connected to the drum dryer 140; the vacuum evaporation unit is also connected to the dehydration and drying unit and the drum dryer 140 respectively.

[0028] The system for treating mother liquor after evaporation of coal chemical wastewater provided in this embodiment further includes a condenser 150 connected to the drum dryer 140 .

[0029] The system for treating mother liquor after evaporation of coal chemical wastewater provided in this embodiment further includes a vacuum pump 160 connected to the condenser 150 .

[0030] In this embodiment, after the mother liquor is evaporated, it enters the vacuum evaporation unit for vacuum evaporation and concentration, and the generated flash steam enters the drum dryer 140 as the heat source of the drum dryer 140, saving energy consumption; after drying in the drum dryer 140, the impure salt is obtained; at the same time, the flash steam enters the condenser 150, and after cooling in the condenser 150, it forms condensed water for recycling; at the same time, during condensation, the vacuum pump 160 is used to evacuate the vacuum to achieve negative pressure operation of the condenser 150, reducing energy consumption. In the vacuum evaporation unit, the salt material that is easier to precipitate is gathered at the bottom of the vacuum evaporation unit for direct recovery or enters the dehydration and drying unit for dehydration and drying to recover the impure salt; the salt material that is not easy to precipitate is discharged through the mother liquor to the separation thickener 90 for the mother liquor, and after cyclone separation, the upper clear liquid is sent to the drum dryer 140 (for drying treatment; the precipitated and concentrated salt material obtained enters the dehydration and drying unit to complete dehydration and drying, realizing the recovery of impure salt.

[0031] In this embodiment, a vacuum evaporation unit is first used to concentrate a large amount of evaporated mother liquor, which not only greatly reduces the amount of discharged mother liquor, but also takes away most of the volatile components and organic matter in the mother liquor; when it is further processed through a separation thickener, a dehydration drying unit and a drum dryer, the processing volume is reduced, the volatile components of the water quality fluctuate little, and the actual processing requirements are met.

[0032] Example 2

[0033] See also Figure 1 On the basis of Example 1, in the mother liquor treatment system after evaporation of coal chemical wastewater provided in this embodiment, the vacuum evaporation unit includes a heat exchanger 10, a heating chamber 40 and a vacuum evaporator 80; the heat exchanger 10 is connected to the heating chamber 40; one end of the heating chamber 40 returns to the other end of the heating chamber 40 after passing through the vacuum evaporator 80 to form a mother liquor circulation pipeline 50; the vacuum evaporator 80 is respectively connected to the dehydration drying unit, the separation thickener 90 and the drum dryer 140.

[0034] In this embodiment, the heat exchanger 10 is a plate type or shell and tube type structure, wherein a liquid with a lower temperature flows through one path, and steam with a higher temperature flows into the other path to achieve heat exchange. Preferably, the evaporated mother liquid flows through the tube side, and steam flows through the shell side. During implementation, the heat exchanger 10 is connected to a mother liquid inlet pipe 20 and a liquid outlet pipe 170 respectively; the setting position of the mother liquid inlet pipe 20 is lower than the setting position of the liquid outlet pipe 170.

[0035] During implementation, the evaporated mother liquid enters the heat exchanger 10 from the mother liquid inlet pipe 20, and after being preheated with the steam entering the heat exchanger 10, the evaporated mother liquid with increased temperature continues to enter the heating chamber 40 to continue to heat up; the steam with reduced temperature is discharged from the liquid outlet pipe 170.

[0036] In this embodiment, the heating chamber 40 also adopts a shell and tube structure, one of which is for the evaporated mother liquid and the other is for the heating steam. The evaporated mother liquid preheated by the heat exchanger 10 enters the heating chamber 40 from the lower position of the heating chamber 40, and a steam inlet pipe 30 is externally connected to the heating chamber 40 to facilitate the steam to enter the heating chamber 40 to heat the preheated evaporated mother liquid. Specifically, the steam inlet pipe 30 is set at a position higher than the position where the evaporated mother liquid enters the heating chamber 40.

[0037] In this embodiment, the steam inlet pipe 30 is connected to the heat exchanger 10 and the drum dryer 140 respectively after passing through the heating chamber 40 and the vacuum evaporator 80. After the steam enters the heating chamber 40 from the steam inlet pipe 30 to complete the heating of the preheated evaporated mother liquor, the cooled steam condensate (the temperature is higher than the evaporated mother liquor) enters the heat exchanger 10 from the lower part of the heating chamber 40 for heat exchange (preheating the mother liquor) and is then discharged from the liquid outlet pipe 170 for recovery; the preheated evaporated mother liquor enters the vacuum evaporator 80 for vacuum evaporation, and the generated flash steam or steam is discharged from the top of the vacuum evaporator 80 and enters the drum dryer 140 as a heat source for drying.

[0038] In practice, there can be one drum dryer 140 or multiple drum dryers 140 arranged in parallel. When multiple drum dryers are arranged in parallel, the utilization rate of the heat source and the drying processing capacity and efficiency are improved.

[0039] In this embodiment, the top of the heating chamber 40, the middle and lower part of the vacuum evaporator 80 and the bottom of the heating chamber 40 form a mother liquid circulation pipeline 50. A circulation pump 70 is arranged on the mother liquid circulation pipeline 50 between the middle and lower part of the vacuum evaporator 80 and the bottom of the heating chamber 40. During implementation, the evaporated mother liquid is continuously introduced through the mother liquid inlet pipe 20, and then in the heating chamber 40 and the vacuum evaporator 80, while vacuum evaporation concentration is realized, the preheated evaporated mother liquid that has not undergone vacuum evaporation concentration is continuously circulated through the mother liquid circulation pipeline 50, while the vacuum evaporation efficiency and vacuum evaporation effect are improved, the processing volume is increased, and continuous processing is realized.

[0040] In this embodiment, a salt leg 60 connected to the inside of the vacuum evaporator 80 is provided at the bottom of the vacuum evaporator 80, and the salt leg 60 is connected to the dehydration and drying unit. Because in the vacuum evaporation and concentration of the vacuum evaporator 80, the salt material that is easier to precipitate gathers at the salt leg 60 at the bottom of the vacuum evaporator 80, and the salt material that is not easy to precipitate is discharged through the external discharge pipeline, and the position of the external discharge pipeline is set above the position where the mother liquid circulation pipeline 50 is set; the salt material gathered at the salt leg 60 can be directly collected, or it can be further dried in the dehydration and drying unit to obtain impure salt; the salt material that is not easy to precipitate is subjected to cyclone separation by the separation thickener 90; after cyclone separation, the upper clear liquid is sent to the drum dryer 140 for drying treatment; the precipitated and concentrated salt material obtained enters the dehydration and drying unit to complete dehydration and drying, and realizes the recovery of impure salt.

[0041] Example 3

[0042] See also Figure 1 On the basis of Example 1 or Example 2, in the mother liquor treatment system after evaporation of coal chemical wastewater, the dehydration and drying unit includes a centrifuge 120 and a fluidized dryer 130 connected in sequence, and the centrifuge 120 is connected to the salt leg 60 and the separation thickener 90 respectively.

[0043] In practice, the salt material gathered at the salt leg 60 and the precipitated concentrated salt material obtained in the separation thickener 90 are all sent to the dehydration and drying unit to complete dehydration and drying. Specifically, the bottom of the separation thickener 90 is connected to the centrifuge 120 via the first slurry pump 100, and the salt leg 60 is connected to the centrifuge 120 via the second slurry pump 110. After centrifugal dehydration in the centrifuge 120, dehydrated impure salt is obtained, and the dehydrated impure salt enters the fluidized dryer 130 for further drying to obtain impure salt.

[0044] The treatment system provided by the utility model can process up to 5 tons / h of mother liquor after evaporation, and the applicable range of COD can reach up to 30,000 mg / L, which can meet the treatment needs of large treatment volume and wide treatment range in the coal chemical industry and has a prospect for promotion and application.

[0045] The above description is only an embodiment of the present invention, and does not limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made by using the contents of the specification and drawings of the present invention, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A system for treating mother liquor after evaporation of coal chemical wastewater, characterized in that: It includes a vacuum evaporation unit, a dehydration drying unit, a separation thickener (90) and a drum dryer (140); The vacuum evaporation unit is connected to the dehydration and drying unit via a separation thickener (90); the separation thickener (90) is also connected to a drum dryer (140); and the vacuum evaporation unit is also connected to the dehydration and drying unit and the drum dryer (140) respectively.

2. The system for treating mother liquor after evaporation of coal chemical wastewater according to claim 1, characterized in that: The vacuum evaporation unit comprises a heat exchanger (10), a heating chamber (40) and a vacuum evaporator (80); the heat exchanger (10) is in communication with the heating chamber (40); one end of the heating chamber (40) passes through the vacuum evaporator (80) and returns to the other end of the heating chamber (40) to form a mother liquid circulation pipeline (50); the vacuum evaporator (80) is respectively in communication with the dehydration drying unit, the separation thickener (90) and the drum dryer (140).

3. The system for treating mother liquor after evaporation of coal chemical wastewater according to claim 2, characterized in that: A salt leg (60) communicating with the interior of the vacuum evaporator (80) is provided at the bottom of the vacuum evaporator (80), and the salt leg (60) is communicated with the dehydration and drying unit.

4. The system for treating mother liquor after evaporation of coal chemical wastewater according to claim 3, characterized in that: The heating chamber (40) is externally connected to a steam inlet pipe (30), and the steam inlet pipe (30) is respectively connected to a heat exchanger (10) and a drum dryer (140) after passing through the heating chamber (40) and the vacuum evaporator (80).

5. The system for treating mother liquor after evaporation of coal chemical wastewater according to claim 4, characterized in that: A circulation pump (70) is arranged on the mother liquid circulation pipeline (50); the circulation pump (70) is located between the vacuum evaporator (80) and the heating chamber (40).

6. The system for treating mother liquor after evaporation of coal chemical wastewater according to claim 5, characterized in that: The dehydration and drying unit comprises a centrifuge (120) and a fluidized dryer (130) which are connected in sequence, and the centrifuge (120) is connected to the salt leg (60) and the separation thickener (90) respectively.

7. The system for treating mother liquor after evaporation of coal chemical wastewater according to any one of claims 1 to 6, characterized in that: The system for treating mother liquor after evaporation of coal chemical wastewater further comprises a condenser (150) connected to the drum dryer (140).

8. The system for treating mother liquor after evaporation of coal chemical wastewater according to claim 7, characterized in that: The system for treating mother liquor after evaporation of coal chemical wastewater further comprises a vacuum pump (160) connected to the condenser (150).

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