CN111825261B - Treatment system and treatment process for salt-containing organic wastewater in para-aramid production - Google Patents
Treatment system and treatment process for salt-containing organic wastewater in para-aramid production Download PDFInfo
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- CN111825261B CN111825261B CN202010737607.3A CN202010737607A CN111825261B CN 111825261 B CN111825261 B CN 111825261B CN 202010737607 A CN202010737607 A CN 202010737607A CN 111825261 B CN111825261 B CN 111825261B
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- 239000002351 wastewater Substances 0.000 title claims abstract description 68
- 150000003839 salts Chemical class 0.000 title claims abstract description 58
- 229920003235 aromatic polyamide Polymers 0.000 title claims abstract description 36
- 238000000034 method Methods 0.000 title claims abstract description 29
- 238000004519 manufacturing process Methods 0.000 title claims description 17
- FAPWRFPIFSIZLT-UHFFFAOYSA-M Sodium chloride Chemical compound [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 claims abstract description 87
- 239000007788 liquid Substances 0.000 claims abstract description 79
- 238000001035 drying Methods 0.000 claims abstract description 69
- 239000011780 sodium chloride Substances 0.000 claims abstract description 44
- 238000000926 separation method Methods 0.000 claims abstract description 18
- 238000010438 heat treatment Methods 0.000 claims abstract description 10
- 239000007787 solid Substances 0.000 claims description 35
- 230000008020 evaporation Effects 0.000 claims description 22
- 238000001704 evaporation Methods 0.000 claims description 22
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 13
- 229910001415 sodium ion Inorganic materials 0.000 claims description 12
- 238000007790 scraping Methods 0.000 claims description 11
- 230000001276 controlling effect Effects 0.000 claims description 7
- FKNQFGJONOIPTF-UHFFFAOYSA-N Sodium cation Chemical compound [Na+] FKNQFGJONOIPTF-UHFFFAOYSA-N 0.000 claims description 6
- 239000000706 filtrate Substances 0.000 claims description 6
- 230000001105 regulatory effect Effects 0.000 claims description 5
- 238000001514 detection method Methods 0.000 claims description 4
- 238000007380 fibre production Methods 0.000 abstract description 5
- 238000004065 wastewater treatment Methods 0.000 abstract description 4
- 239000000701 coagulant Substances 0.000 abstract description 3
- 239000000243 solution Substances 0.000 description 37
- SECXISVLQFMRJM-UHFFFAOYSA-N N-Methylpyrrolidone Chemical compound CN1CCCC1=O SECXISVLQFMRJM-UHFFFAOYSA-N 0.000 description 31
- 239000012071 phase Substances 0.000 description 18
- 239000013078 crystal Substances 0.000 description 17
- 239000002904 solvent Substances 0.000 description 16
- 238000011084 recovery Methods 0.000 description 8
- 238000005119 centrifugation Methods 0.000 description 7
- 239000012452 mother liquor Substances 0.000 description 6
- 239000000047 product Substances 0.000 description 6
- 239000007864 aqueous solution Substances 0.000 description 5
- 229910000831 Steel Inorganic materials 0.000 description 4
- 238000009833 condensation Methods 0.000 description 4
- 230000005494 condensation Effects 0.000 description 4
- 239000010959 steel Substances 0.000 description 4
- VEXZGXHMUGYJMC-UHFFFAOYSA-M Chloride anion Chemical compound [Cl-] VEXZGXHMUGYJMC-UHFFFAOYSA-M 0.000 description 3
- 238000007599 discharging Methods 0.000 description 3
- 238000005259 measurement Methods 0.000 description 3
- 239000002245 particle Substances 0.000 description 3
- 238000006243 chemical reaction Methods 0.000 description 2
- 239000012141 concentrate Substances 0.000 description 2
- 239000000835 fiber Substances 0.000 description 2
- 229910021421 monocrystalline silicon Inorganic materials 0.000 description 2
- 125000001140 1,4-phenylene group Chemical group [H]C1=C([H])C([*:2])=C([H])C([H])=C1[*:1] 0.000 description 1
- HCSCWJCZRCSQFA-UHFFFAOYSA-N 1-methylpyrrolidin-2-one;hydrate Chemical compound O.CN1CCCC1=O HCSCWJCZRCSQFA-UHFFFAOYSA-N 0.000 description 1
- 241000894006 Bacteria Species 0.000 description 1
- 239000002253 acid Substances 0.000 description 1
- 239000003513 alkali Substances 0.000 description 1
- 230000007123 defense Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 239000003365 glass fiber Substances 0.000 description 1
- 239000012535 impurity Substances 0.000 description 1
- 239000002075 main ingredient Substances 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 229920003366 poly(p-phenylene terephthalamide) Polymers 0.000 description 1
- 238000006116 polymerization reaction Methods 0.000 description 1
- 238000001953 recrystallisation Methods 0.000 description 1
- 238000007670 refining Methods 0.000 description 1
- 239000010865 sewage Substances 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 239000012808 vapor phase Substances 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/02—Treatment of water, waste water, or sewage by heating
- C02F1/04—Treatment of water, waste water, or sewage by heating by distillation or evaporation
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01D—COMPOUNDS OF ALKALI METALS, i.e. LITHIUM, SODIUM, POTASSIUM, RUBIDIUM, CAESIUM, OR FRANCIUM
- C01D3/00—Halides of sodium, potassium or alkali metals in general
- C01D3/04—Chlorides
- C01D3/06—Preparation by working up brines; seawater or spent lyes
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01D—COMPOUNDS OF ALKALI METALS, i.e. LITHIUM, SODIUM, POTASSIUM, RUBIDIUM, CAESIUM, OR FRANCIUM
- C01D3/00—Halides of sodium, potassium or alkali metals in general
- C01D3/14—Purification
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01F—COMPOUNDS OF THE METALS BERYLLIUM, MAGNESIUM, ALUMINIUM, CALCIUM, STRONTIUM, BARIUM, RADIUM, THORIUM, OR OF THE RARE-EARTH METALS
- C01F11/00—Compounds of calcium, strontium, or barium
- C01F11/20—Halides
- C01F11/24—Chlorides
- C01F11/30—Concentrating; Dehydrating; Preventing the adsorption of moisture or caking
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01F—COMPOUNDS OF THE METALS BERYLLIUM, MAGNESIUM, ALUMINIUM, CALCIUM, STRONTIUM, BARIUM, RADIUM, THORIUM, OR OF THE RARE-EARTH METALS
- C01F11/00—Compounds of calcium, strontium, or barium
- C01F11/20—Halides
- C01F11/24—Chlorides
- C01F11/32—Purification
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/38—Treatment of water, waste water, or sewage by centrifugal separation
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2101/00—Nature of the contaminant
- C02F2101/30—Organic compounds
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- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Engineering & Computer Science (AREA)
- Inorganic Chemistry (AREA)
- Life Sciences & Earth Sciences (AREA)
- Environmental & Geological Engineering (AREA)
- Water Supply & Treatment (AREA)
- Materials Engineering (AREA)
- Hydrology & Water Resources (AREA)
- Geology (AREA)
- Analytical Chemistry (AREA)
- Mechanical Engineering (AREA)
- Heat Treatment Of Water, Waste Water Or Sewage (AREA)
- Vaporization, Distillation, Condensation, Sublimation, And Cold Traps (AREA)
Abstract
The application belongs to the technical field of wastewater treatment, and in particular relates to a treatment system and a treatment process of organic wastewater containing salt in para-aramid fiber production. The system comprises a plurality of evaporators connected in series, a drying device, a solid-liquid separation device, a heating device and a gas-phase condensing device; the upper part of the evaporator is provided with a first liquid inlet pipe, and the bottom of the evaporator is provided with a liquid outlet pipe; the liquid outlet pipe of the evaporator of the previous stage is connected with the first liquid inlet pipe of the evaporator of the next stage, and the liquid outlet pipe of the evaporator of the last stage is connected with the solid-liquid separation device. The drying device comprises a shell and a rotary drying assembly arranged in the shell; the shell is of an inverted conical structure, and a heating sleeve is arranged outside the shell. In the treatment system, a plurality of evaporators are used in series, are controlled separately and are matched with a subsequent drying device with a special structure, and NMP and CaCl are realized under the condition that other precipitants or coagulants are not added 2 And NaCl is separated, so that the treatment cost is low.
Description
Technical Field
The application belongs to the technical field of wastewater treatment, and in particular relates to a treatment system and a treatment process of organic wastewater containing salt in para-aramid fiber production.
Background
The poly-p-phenylene terephthamide (PPTA) fiber is a para-aramid fiber for short, has excellent performances of high strength, high modulus, high temperature resistance, acid and alkali resistance, light weight and the like, has specific strength of 5-6 times of steel wires, specific modulus of 2-3 times of steel wires or glass fiber, toughness of 2 times of steel wires, and weight of only about 20% of steel wires, and has wide application in civil and national defense fields. The liquid collected in the polymerization section of para-aramid production process is called mother liquor, and the mother liquor has low concentration of CaCl 2 NaCl, N-methylpyrrolidone (NMP) and a large amount of H 2 O. CHCl is used in the subsequent solvent section 3 NMP in the mother liquor is extracted, the extracted NMP is recycled, and the rest saline water solution becomes saline wastewater of a solvent section.Although the solvent section can recover most NMP, the recovery rate reaches 98 percent, NMP is very soluble in water, and the extracted salt-containing wastewater still inevitably contains a small amount of NMP. Therefore, the components in the salt-containing organic wastewater generated in the para-aramid solvent working section are CaCl 2 、NaCl、H 2 O, NMP, which is basically consistent with the components of the mother liquor, wherein the salt content is generally 3.5 to 5 percent, and CaCl 2 And NaCl mass ratio is about 4:1, NMP content is 800-3000 ppm.
Because the salt content and NMP content in the salt-containing organic wastewater of the para-aramid solvent working section far exceed the normal discharge indexes, the salt-containing organic wastewater cannot be directly discharged and needs to be treated, but the problems faced by the current treatment of the wastewater mainly comprise: 1) Because the content of chloride ions far exceeds the maximum chloride ion standard of biochemical treatment (the content of chloride ions is required to be less than 0.6% in biochemical treatment), biochemical bacteria can be directly killed, and organic matters cannot be directly degraded by the biochemical treatment; 2) Wherein CaCl 2 Similar to NaCl in chemical nature, it is difficult to isolate it by simple methods. At present, a plurality of devices and processes for treating the mother liquor in the para-aramid production process exist, but the contents of all components of the salt-containing organic wastewater obtained in the solvent working section are greatly different from those of the mother liquor, so that the existing devices and processes for treating the salt-containing organic wastewater are not suitable and uneconomical. How to achieve low cost and can effectively use NMP (or NMP water solution) and CaCl 2 The salt-containing organic wastewater in the para-aramid solvent working section is effectively treated by separating NaCl from the para-aramid solvent working section, and the problem to be solved in the para-aramid industry is urgently solved.
Disclosure of Invention
In order to solve the technical problems, the purpose of the application is to provide a treatment system for organic wastewater containing salt in para-aramid production, by which the wastewater produced by para-aramid, especially NMP and CaCl in the wastewater produced by a para-aramid solvent section, can be treated by the treatment system 2 The NaCl and the NaCl are separated, and the treatment process is simple and effective; the present application also includes a process for treating the above-described organic wastewater containing salt using the treatment system, based on one general inventive concept.
In order to achieve the technical purpose, the application adopts the following technical scheme:
a treatment system of organic wastewater containing salt in para-aramid production comprises a plurality of evaporators, a drying device, a solid-liquid separation device, a heating device and a gas-phase condensing device which are connected in series;
the upper part of the evaporator is provided with a first liquid inlet pipe, and the bottom of the evaporator is provided with a liquid outlet pipe; the liquid outlet pipe of the evaporator of the previous stage is connected with the first liquid inlet pipe of the evaporator of the next stage, and the liquid outlet pipe of the evaporator of the last stage is connected with the solid-liquid separation device; the side wall of the evaporator is also provided with a second liquid inlet pipe which is communicated with the bottom liquid outlet pipe to form an internal liquid circulation line, and the heating device is positioned on the internal liquid circulation line; the evaporator is also provided with a gas phase pipeline, and is communicated with the gas phase condensing device through the gas phase pipeline;
the drying device comprises a shell and a rotary drying assembly arranged in the shell; the shell is of an inverted conical structure, and a heating sleeve is arranged outside the shell; the top of the shell is provided with a concentrated solution inlet pipe, and concentrated filtrate of the final-stage evaporator subjected to solid-liquid separation is led into the shell through a concentrated solution inlet pipe; a discharge hole is formed in the bottom of the shell, and the dried solid is discharged from the discharge hole; the rotary drying assembly comprises a rotating shaft, a connecting rod and a scraping plate; the top end of the rotating shaft is rotationally connected with the top of the shell; a plurality of connecting rods are sequentially arranged on the rotating shaft from bottom to top; the connecting rod is vertically arranged with the rotating shaft, and the length of the connecting rod is matched with the inner diameter of the shell in the same horizontal plane, so that the scraping plate arranged at the end part of the connecting rod can scrape attachments on the inner wall of the shell;
the gas-phase condensing device comprises a condenser, a condensate liquid storage tank and a vacuum pump; the condenser is communicated with the vacuum pump through a gas phase pipeline, and the condenser is communicated with the condensate liquid storage tank through a condensate liquid discharge pipe.
Preferably, the last-stage evaporator is further provided with a concentrated solution drain pipe, and the concentrated solution drain pipe is communicated with a concentrated solution inlet pipe of the drying device. The liquid discharge pipe is connected with the drying device, so that the concentrated solution in the evaporator of the last stage can be directly discharged into the drying device for drying.
Preferably, an automatic on-line sodium ion detection device is arranged in the final-stage evaporator. After three-stage evaporation concentration, a large amount of NaCl crystals can be separated out at the bottom of the three-stage evaporator, and the concentration of sodium ions in the concentrated solution can be detected in real time to judge the reaction end point by the on-line automatic sodium ion detection device.
Preferably, an umbrella-shaped baffle is arranged on the rotating shaft; the umbrella-shaped baffle is positioned above the connecting rod; the umbrella-shaped baffle is inclined downwards by taking the rotating shaft as the center, and a certain gap is reserved between the bottom of the umbrella-shaped baffle and the inner wall of the shell. The evaporation area can be increased by arranging umbrella-shaped baffles: the concentrated solution entering the shell falls on the umbrella-shaped baffle plate firstly, the umbrella-shaped baffle plate uniformly distributes the concentrated solution to the inner wall of the shell in the rotating process, and the concentrated solution is concentrated, separated out and dried in the sliding process along the inner wall of the shell, so that the drying efficiency of the concentrated solution is effectively improved.
Preferably, the scraping plate and the inner wall of the shell are arranged in parallel, and a gap of 3-10 mm is reserved between the scraping plate and the inner wall of the shell. The scraping plates which are parallel to the inner wall of the shell are arranged to facilitate scraping of the dry solids attached to the inside of the shell.
Preferably, a gas phase pipeline is arranged at the top of the shell, and the drying device is communicated with the condenser through the gas phase pipeline.
A process for treating organic wastewater containing salt in para-aramid fiber production by utilizing the treatment system specifically comprises the following steps:
1) Conveying the organic wastewater containing salt in para-aramid production into a first-stage evaporator for evaporation concentration, wherein the vacuum degree in the first-stage evaporator is controlled within the range of-70 to-90 kpa, the temperature is controlled within the range of 65-75 ℃, and the salt concentration after concentration is 5-8%;
2) Delivering the concentrated wastewater to a secondary evaporator from a liquid outlet pipe of the primary evaporator for continuous evaporation, controlling the vacuum degree to-75 to-95 kpa, and the temperature to 65-75 ℃, wherein the concentration of the concentrated salt is 10-15%;
3) Delivering the concentrated wastewater to a third-stage evaporator from a liquid outlet pipe of the second-stage evaporator for continuous evaporation, controlling the vacuum degree to-85 to-95 kpa, and controlling the temperature to 60-68 ℃ and the concentration of the concentrated salt to be 35-45%;
4) The gas evaporated in the steps 1) to 3) enters a condenser through a gas phase pipeline, the condensate liquid is the water solution containing NMP, and the water solution is discharged into a condensate liquid storage tank;
5) Introducing the concentrated wastewater obtained in the step 3) into a solid-liquid separation device for solid-liquid separation, wherein the obtained solid is NaCl; after solid-liquid separation, the filtrate is led into a drying device for further drying;
6) The rotating speed of the rotating shaft of the drying device is regulated to be 10-100 rpm, the drying temperature is 180-200 ℃, the dried solid attached to the inner wall of the shell is scraped by a rotating scraper and falls into a discharge hole to be discharged, and the main component of the dried solid is CaCl 2 。
Preferably, the vacuum degree in the step 1) is-80 kpa, and the temperature is 70 ℃; the vacuum degree in the step 2) is-85 kpa, and the temperature is 66 ℃; the vacuum degree in the step 3) is-92 kpa, and the temperature is 62 ℃.
Preferably, the vacuum degree in the step 6) is-90 kpa.
Preferably, the salt-containing organic wastewater in the para-aramid fiber production is preheated before entering the primary evaporator, and the preheating temperature is 30-50 ℃.
In the treatment system, a plurality of evaporators are used in series, are controlled separately and are matched with a subsequent drying device with a special structure, and NMP and CaCl are realized under the condition that other precipitants or coagulants are not added 2 And NaCl is separated, so that the treatment cost is low. After the calculation and the treatment by the device, naCl crystals with the purity of more than 99 percent can be obtained in the solid-liquid separation step, and the recovery rate of the NaCl crystals is more than 74.29 percent. More than about 75% of the NMP can be recovered in the condensate storage tank through the evaporative condensation process. The final dry product contains CaCl containing crystal water as main component 2 Wherein CaCl 2 ﹒2H 2 O and CaCl 2 ﹒4H 2 O is about 1:1 by mass and contains no more than 4.15% NaCl. The final dried product can be recrystallized or otherwise refined to obtain CaCl with higher purity 2 The product can also be directly used for other purposes, such as treating sewage in monocrystalline silicon industry.
The processing system is simple in structure and high in controllability; the process has high treatment efficiency and easy realization, and provides an economical and effective feasible way for continuously treating the salt-containing organic wastewater in the para-aramid solvent working section on a large scale.
Drawings
FIG. 1 is a schematic diagram showing the connection of the components of a salt-containing organic wastewater treatment system in para-aramid production.
Detailed Description
The present application is described in further detail below in connection with specific embodiments. The terms "upper", "lower", "inner", "outer" and the like in the embodiments are merely for illustrating the relative positional relationship of the structures, and are not intended to limit the scope of the present application, and the changes or modifications of the relative relationship are considered to be within the scope of the present application without substantial changes in the technical content.
Example 1
A treatment system of salt-containing organic wastewater in para-aramid production comprises a primary evaporator 1, a secondary evaporator 2, a tertiary evaporator 3, a drying device, a centrifugal machine 8, a heat exchanger and a vapor phase condensing device which are connected in series in three stages;
the upper part of the evaporator is provided with a first liquid inlet pipe 6, and organic wastewater containing salt in para-aramid fiber production enters the evaporator through the first liquid inlet pipe 6; the first liquid inlet pipe 6 is provided with a heat exchanger 7 which can be used for preheating the wastewater. The bottom of the evaporator is provided with a liquid outlet pipe 9, and the liquid outlet pipe 9 of the evaporator of the previous stage is connected with the first liquid inlet pipe 6 of the evaporator of the next stage through a connecting pipe, so that the evaporation concentrate in the evaporator 1 of the first stage can enter the evaporator 2 of the second stage for continuous evaporation, and the evaporation concentrate in the evaporator 2 of the second stage can enter the evaporator 3 of the third stage for continuous evaporation, thereby improving the evaporation efficiency; the liquid outlet pipe 9 is provided with a circulating water pump 21. The side wall of the evaporator is also provided with a second liquid inlet pipe 10, the second liquid inlet pipe 10 and a liquid outlet pipe 9 form an internal liquid circulation line through a connecting pipe, and a forced circulation pump 20 and a heat exchanger 7 are arranged on the internal liquid circulation line; the forced circulation pump 20 is started to circulate the wastewater at the bottom of the evaporator in an internal feed liquid circulation line, and the temperature of the wastewater in the evaporator is controlled within a certain range by heating the water in the pipeline through the heat exchanger 7 in the circulation process, so that the evaporation concentration of the wastewater in the evaporator is realized; after the concentrated solution is concentrated to a certain degree, the circulating water pump 21 is started to pump out the evaporated concentrated solution, and the evaporated concentrated solution is sent to the next-stage evaporator for continuous evaporation concentration.
After the organic wastewater containing salt is concentrated by three-stage evaporation, a large amount of crystals are precipitated at the bottom of the three-stage evaporator 3, and the components of the organic wastewater mainly comprise NaCl. An automatic on-line sodium ion detector (not shown) is arranged in the three-stage evaporator 3, the concentration degree can be monitored on line by detecting the concentration of sodium ions in the concentrated solution, the reaction end point is judged, and the material can be discharged and discharged when the NaCl in the wastewater is 2.23-3.13%. The concentrated solution containing NaCl crystals is discharged from a liquid outlet pipe of the three-stage evaporator 3 and enters a centrifugal machine 8 for centrifugation; directly drying the solid after centrifugation to obtain NaCl crystals; the filtrate after centrifugation enters a drying device from a concentrated solution inlet pipe 11 for further concentration and drying. In order to improve the concentration efficiency, the three-stage evaporator 3 is also provided with a concentrated solution drain pipe 12, and the concentrated solution drain pipe 12 is communicated with a concentrated solution inlet pipe 11; and when the concentration of NaCl in the concentrated wastewater in the three-stage evaporator 3 is reduced to 2.23-3.13%, the upper concentrated clear liquid without solid crystals on the upper layer can be directly discharged into a drying device for drying, so that the processing capacity of the subsequent centrifugal operation is reduced.
The drying device comprises a shell 4 and a rotary drying assembly arranged in the shell 4; the shell 4 is in an inverted conical structure, and a heating sleeve (not shown in the figure) is arranged outside the shell 4; the top of the shell 4 is connected with a concentrated solution inlet pipe 11, and the filtrate after centrifugation enters the shell 4 from the concentrated solution inlet pipe 11 for drying; the bottom of the shell 4 is provided with a discharge hole, and the dried solid is discharged from the discharge hole; the dry solid contains CaCl as main ingredient 2 . The rotary drying assembly comprises a rotating shaft 17, an umbrella-shaped baffle 19 arranged on the rotating shaft 17, a plurality of horizontally arranged connecting rods 18 and a scraper 181 arranged at the end part of the connecting rods 18. The rotating shaft 17 is positioned on the axial center line of the shell 4, and the top end of the rotating shaft 17 is rotationally connected with the top of the shell 4. The umbrella-shaped baffle 19 is positioned at the upper part of the rotating shaft 17, the umbrella-shaped baffle 19 is inclined downwards by taking the rotating shaft 17 as the center, and a certain gap is reserved between the bottom of the umbrella-shaped baffle 19 and the inner wall of the shell 4; by arranging umbrella shapeThe baffle 19 can greatly increase the evaporation area in the housing 4: the concentrated solution entering the shell 4 firstly falls on the umbrella-shaped baffle 19, the umbrella-shaped baffle 19 uniformly distributes the concentrated solution to the inner wall of the shell 4 in the rotating process, and the concentrated solution is concentrated, separated out and dried in the sliding process along the inner wall of the shell 4, so that the drying efficiency of the concentrated solution is effectively improved. A connecting rod 18 is arranged below the umbrella-shaped baffle 19, the connecting rod 18 is arranged perpendicular to the rotating shaft 17, and the length of the connecting rod 18 is matched with the inner diameter of the same horizontal plane shell 4. The scraping plates 181 are positioned at two ends of the connecting rod 18; the two ends of the scraper 181 extend to the upper and lower sides of the connecting rod 18 respectively, and the scraper 181 is approximately parallel to the inner wall of the shell 4, so that the scraper 181 can scrape the inner wall of the shell 4 as large as possible. In order to avoid friction damage of the scraper 181 to the inner wall of the shell 4, a gap of 3-10 mm is reserved between the scraper 181 and the inner wall of the shell 4.
The top parts of the primary evaporator 1, the secondary evaporator 2, the tertiary evaporator 3 and the shell 4 are all communicated with a gas phase pipeline 13, and the evaporator and the drying device are communicated with a gas phase condensing device through the gas phase pipeline 13. The gas-phase condensing device comprises a condenser 14, a condensate liquid storage tank 5 and a vacuum pump 15; the condenser 14 is communicated with the vacuum pump 15 through a gas phase pipeline, and the condenser 14 is communicated with the condensate liquid storage tank 5 through a condensate liquid discharge pipe 16. The gas evaporated in the evaporation and drying process is pumped by a vacuum pump 15 and enters a condenser 14 through a gas phase pipeline 13 to be cooled and condensed, the obtained condensate is the aqueous solution containing NMP, and the aqueous solution is discharged into a condensate liquid storage tank 5 to be stored.
In the treatment system of the embodiment, a plurality of evaporators are used in series, are controlled separately step by step and are matched with a subsequent drying device with a special structure, and NMP and CaCl are realized under the condition that other precipitants or coagulants are not added 2 The NaCl is separated, and the treatment cost is low; and the three components do not change in property, and other impurities are not introduced, so that the three components are further extracted and purified.
Example 2
A process for treating organic wastewater containing salt in para-aramid production by using the treatment system in the embodiment 1 comprises the following specific steps:
the organic wastewater containing salt generated in the para-aramid solvent working section is preheated to 40 ℃ firstly, and then enters a first-stage evaporator, wherein the salt content is about 3.5%, and the NMP content is 1600ppm.
Controlling the vacuum degree of the primary evaporator to be-80 kpa and the temperature to be 70 ℃, and concentrating the organic wastewater containing salt to about 5.44%; the first-stage wastewater enters a second-stage evaporator, and the salt-containing organic wastewater is concentrated to about 11.56% under the conditions of the vacuum degree of-85 kpa and the temperature of 66 ℃; the secondary wastewater enters a tertiary evaporator, and after concentration under the conditions of the vacuum degree of-92 kpa and the temperature of 62 ℃, the salt content is about 40.62%. The concentration of NaCl in the concentrated solution is 2.61% by the detection of an on-line automatic monitor of sodium ions, and a large amount of crystals are precipitated at the bottom of the three-stage evaporator.
And (3) conveying the mixed concentrated solution containing crystal particles to a centrifugal machine for centrifugation by using a discharging pipe at the bottom of the three-stage evaporator, drying the obtained solid, measuring the components of the solid, and measuring the obtained solid to obtain NaCl with the purity of 99.2%. And (3) conveying the concentrated solution obtained by solid-liquid separation and the concentrated wastewater in the three-stage evaporator to a drying device for further concentration and drying.
The rotating speed of the rotating shaft in the drying device is regulated to be 50rpm, the temperature is controlled to be 190 ℃, and the vacuum degree is controlled to be-90 kpa. In the drying process, the dried solids attached to the inner wall are scraped off by the scraper and fall from the discharge port. The obtained dried solid is mainly CaCl 2 And a small amount of NaCl.
In the evaporation and drying processes, the gas evaporated in the evaporator is pumped by a vacuum pump and enters a condenser through a gas phase pipeline to be cooled and condensed, the obtained condensate is an aqueous solution containing NMP, and the NMP content in a condensate liquid storage tank is measured to be 1200ppm.
In actual production, the evaporation and concentration process is continuously carried out: after the concentrated wastewater in the first-stage evaporator flows into the second-stage evaporator, the new wastewater is replenished in the first-stage evaporator, and the treatment is continued. After accounting, the treatment system is utilized to continuously treat the salt-containing organic wastewater of the para-aramid solvent working section for 24 hours, wherein the salt content is about 140kg. After centrifugal drying by measurement, 20.8kg of NaCl solid was obtained, and the recovery rate of NaCl was about 74.29%. The recovery of NMP during condensation was about 75%.
After drying by a drying device, about 173.7kg of dried solid can be obtained, and the content of sodium ions in the solid can be measured to obtain the sodium chloride content of 7.2kg, wherein the mass ratio is 4.15%. The rest components are CaCl containing crystal water 2 By determination of CaCl therein 2 ﹒2H 2 O is 54.5kg, caCl 2 ﹒4H 2 O was 112kg. According to CaCl 2 As can be seen from the calculation of the amount of CaCl after the treatment 2 Is close to 100% but due to final CaCl 2 The product is mixed with a small amount of NaCl and a trace amount of NMP which is not steamed out, and CaCl with higher purity is obtained later 2 The product can be subjected to subsequent recrystallization or other refining processes; the CaCl with small amount of NaCl and trace amount of NMP is obtained 2 The product can also be directly used, such as waste water treatment process used in monocrystalline silicon industry.
Example 3
A process for treating organic wastewater containing salt in para-aramid production by using the treatment system in the embodiment 1 comprises the following specific steps:
the salt-containing organic wastewater of the para-aramid solvent section is preheated to 40 ℃ firstly, and then is input into a first-stage evaporator, wherein the salt content is about 4.2%, and the NMP content is 2000ppm.
Concentrating the organic wastewater containing salt to about 6.45% by a first-stage evaporator under a vacuum degree of-80 kpa and a temperature of 70 ℃; the first-stage wastewater enters a second-stage evaporator, and the salt-containing organic wastewater is concentrated to about 12.32% under the conditions of the vacuum degree of-85 kpa and the temperature of 66 ℃; the secondary wastewater enters a tertiary evaporator, and after concentration under the conditions of the vacuum degree of-92 kpa and the temperature of 62 ℃, the salt content is about 40.89 percent. The NaCl concentration is 2.61% by the on-line automatic monitor of sodium ion, and a large amount of NaCl crystals are precipitated at the bottom of the three-stage evaporator.
The mixed concentrated solution containing crystal particles is conveyed to a centrifugal machine for centrifugation by utilizing a discharging pipe at the bottom of the three-stage evaporator, the obtained solid is dried and the components of the solid are measured, and the obtained solid is determined to be NaCl with the purity of 98.7 percent. And (3) conveying the concentrated solution obtained by solid-liquid separation and the concentrated wastewater in the three-stage evaporator to a drying device for further concentration and drying.
The rotating speed of the rotating shaft in the drying device is regulated to be 50rpm, the temperature is controlled to be 190 ℃, and the vacuum degree is controlled to be-90 kpa. In the drying process, the dried solids attached to the inner wall are scraped off by a scraper, fall down through a discharge hole and are discharged. The obtained dried solid is mainly CaCl 2 And a small amount of NaCl.
In the evaporation and drying processes, the gas evaporated in the evaporator is pumped by a vacuum pump and enters a condenser through a gas phase pipeline to be cooled and condensed, the obtained condensate is an aqueous solution containing NMP, and the NMP content in a condensate liquid storage tank is measured to be 1600ppm.
After accounting, the treatment system is utilized to continuously treat the salt-containing organic wastewater of the para-aramid solvent working section for 24 hours, wherein the salt content is about 168kg. After measurement and centrifugal drying, 25.9kg of NaCl solid was obtained, and the recovery rate of NaCl was about 77.08%. The recovery of NMP during condensation was about 80%. After drying by a drying device, about 207.48kg of dried solid can be obtained, wherein the content of sodium ions is measured to be available, and the content of sodium chloride is 7.7kg, and the mass ratio is 3.71%. The rest components are CaCl containing crystal water 2 By determination of CaCl therein 2 ﹒2H 2 O is 65.38kg, caCl 2 ﹒4H 2 O was 134.4kg.
Example 4
A process for treating organic wastewater containing salt in para-aramid production by using the treatment system in the embodiment 1 comprises the following specific steps:
the organic wastewater containing salt in the para-aramid solvent section is preheated to 40 ℃ and then fed into a first-stage evaporator, wherein the salt content is about 5%, and the NMP content is 2200ppm.
Concentrating the organic wastewater containing salt to about 7.05% by a first-stage evaporator under vacuum of-80 kpa and at a temperature of 70 ℃; the first-stage wastewater enters a second-stage evaporator, and the salt-containing organic wastewater is concentrated to about 13.07% under the conditions of the vacuum degree of-85 kpa and the temperature of 66 ℃; the secondary wastewater enters a tertiary evaporator, and after concentration under the conditions of the vacuum degree of-92 kpa and the temperature of 62 ℃, the salt content is about 40.96%. The NaCl concentration is 2.61% by the on-line automatic monitor of sodium ion, and a large amount of NaCl crystals are precipitated at the bottom of the three-stage evaporator.
And (3) conveying the mixed concentrated solution containing crystal particles to a centrifugal machine for centrifugation by using a discharging pipe at the bottom of the three-stage evaporator, drying the obtained solid, measuring the components of the solid, and measuring the obtained solid to obtain NaCl with the purity of 99.0%. And (3) conveying the concentrated solution obtained by solid-liquid separation and the concentrated wastewater in the three-stage evaporator to a drying device for further concentration and drying.
The rotating speed of the rotating shaft in the drying device is regulated to be 50rpm, the temperature is controlled to be 190 ℃, and the vacuum degree is controlled to be-90 kpa. In the drying process, the dried solids attached to the inner wall are scraped off by a scraper, fall down through a discharge hole and are discharged. The obtained dried solid is mainly CaCl 2 And a small amount of NaCl.
In the evaporation and drying processes, the gas evaporated in the evaporator is pumped by a vacuum pump and enters a condenser through a gas phase pipeline to be cooled and condensed, the obtained condensate is an aqueous solution containing NMP, and the NMP content in a condensate liquid storage tank is determined to be 1800ppm.
After accounting, the treatment system is utilized to continuously treat the salt-containing organic wastewater of the para-aramid solvent working section for 24 hours, wherein the salt content is about 200kg. After measurement and centrifugal drying, 30.4kg of NaCl solid was obtained, and the recovery rate of NaCl was about 76%. The recovery of NMP during condensation was approximately 81.82%. After drying by a drying device, about 247.44kg of dried solid can be obtained, wherein the content of sodium ions is measured to be available, and the content of sodium chloride is 9.6kg, and the mass ratio is 3.87%. The rest components are CaCl containing crystal water 2 By determination of CaCl therein 2 ﹒2H 2 O is 77.84kg, caCl 2 ﹒4H 2 O was 160kg.
Claims (4)
1. A process for treating salt-containing organic wastewater in para-aramid production is characterized in that the process is realized by a treatment system of the salt-containing organic wastewater in para-aramid production;
the treatment system comprises three stages of evaporators, a drying device, a solid-liquid separation device, a heating device and a gas-phase condensing device which are connected in series;
the upper part of the evaporator is provided with a first liquid inlet pipe, and the bottom of the evaporator is provided with a liquid outlet pipe; the liquid outlet pipe of the evaporator of the previous stage is connected with the first liquid inlet pipe of the evaporator of the next stage, and the liquid outlet pipe of the evaporator of the last stage is connected with the solid-liquid separation device; the side wall of the evaporator is also provided with a second liquid inlet pipe which is communicated with the bottom liquid outlet pipe to form an internal liquid circulation line, and the heating device is positioned on the internal liquid circulation line; the evaporator is also provided with a gas phase pipeline, and is communicated with the gas phase condensing device through the gas phase pipeline;
the drying device comprises a shell and a rotary drying assembly arranged in the shell; the shell is of an inverted conical structure, and a heating sleeve is arranged outside the shell; the top of the shell is provided with a concentrated solution inlet pipe, and concentrated filtrate of the final-stage evaporator subjected to solid-liquid separation is led into the shell through a concentrated solution inlet pipe; a discharge hole is formed in the bottom of the shell, and the dried solid is discharged from the discharge hole; the rotary drying assembly comprises a rotating shaft, a connecting rod and a scraping plate; the top end of the rotating shaft is rotationally connected with the top of the shell; a plurality of connecting rods are sequentially arranged on the rotating shaft from bottom to top; the connecting rod is vertically arranged with the rotating shaft, and the length of the connecting rod is matched with the inner diameter of the shell in the same horizontal plane, so that the scraping plate arranged at the end part of the connecting rod can scrape attachments on the inner wall of the shell;
the gas-phase condensing device comprises a condenser, a condensate liquid storage tank and a vacuum pump; the condenser is communicated with the vacuum pump through a gas phase pipeline, and the condenser is communicated with the condensate liquid storage tank through a condensate liquid discharge pipe;
the final-stage evaporator is also provided with a concentrated solution drain pipe which is communicated with a concentrated solution inlet pipe of the drying device;
an automatic online sodium ion detection device is arranged in the final-stage evaporator;
an umbrella-shaped baffle is arranged on the rotating shaft; the umbrella-shaped baffle is positioned above the connecting rod; the umbrella-shaped baffle is inclined downwards by taking the rotating shaft as the center, and a certain gap is reserved between the bottom of the umbrella-shaped baffle and the inner wall of the shell;
the scraping plate is arranged in parallel with the inner wall of the shell, and a gap of 3-10 mm is reserved between the scraping plate and the inner wall of the shell;
the top of the shell is provided with a gas phase pipeline, and the drying device is communicated with the condenser through the gas phase pipeline;
the process comprises the following steps:
1) Conveying the organic wastewater containing salt in para-aramid production into a first-stage evaporator for evaporation concentration, wherein the vacuum degree in the first-stage evaporator is controlled within the range of-70 to-90 kpa, the temperature is controlled within the range of 65-75 ℃, and the salt concentration after concentration is 5-8%;
2) Delivering the concentrated wastewater to a secondary evaporator from a liquid outlet pipe of the primary evaporator for continuous evaporation, controlling the vacuum degree to-75 to-95 kpa, and the temperature to 65-75 ℃, wherein the concentration of the concentrated salt is 10-15%;
3) Delivering the concentrated wastewater to a third-stage evaporator from a liquid outlet pipe of the second-stage evaporator for continuous evaporation, controlling the vacuum degree to-85 to-95 kpa, and controlling the temperature to 60-68 ℃ and the concentration of the concentrated salt to be 35-45%;
4) The gas evaporated in the steps 1) to 3) enters a condenser through a gas phase pipeline, the condensate liquid is the water solution containing NMP, and the water solution is discharged into a condensate liquid storage tank;
5) Introducing the concentrated wastewater obtained in the step 3) into a solid-liquid separation device for solid-liquid separation, wherein the obtained solid is NaCl; after solid-liquid separation, the filtrate is led into a drying device for further drying;
6) The rotating speed of the rotating shaft of the drying device is regulated to be 10-100 rpm, and the drying temperature is 180-200 ℃; the dried solid attached to the inner wall of the shell is scraped by a rotary scraper and falls into a discharge port to be discharged, and the main component of the obtained dried solid is CaCl 2 。
2. The process of claim 1, wherein: the vacuum degree in the step 1) is-80 kpa, and the temperature is 70 ℃; the vacuum degree in the step 2) is-85 kpa, and the temperature is 66 ℃; the vacuum degree in the step 3) is-92 kpa, and the temperature is 62 ℃.
3. The process of claim 1, wherein: the vacuum degree of the step 6) is-90 kpa.
4. The process of claim 1, wherein: the salt-containing organic wastewater in the para-aramid production is preheated before entering the primary evaporator, and the preheating temperature is 30-50 ℃.
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| KR20040026202A (en) * | 2002-09-23 | 2004-03-30 | 주식회사 세화엔스텍 | method of evaporatoring for vacuum evaporator |
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