CN114656007A - Method and system for recycling volatile substances in wastewater - Google Patents
Method and system for recycling volatile substances in wastewater Download PDFInfo
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- CN114656007A CN114656007A CN202210146874.2A CN202210146874A CN114656007A CN 114656007 A CN114656007 A CN 114656007A CN 202210146874 A CN202210146874 A CN 202210146874A CN 114656007 A CN114656007 A CN 114656007A
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- 239000002351 wastewater Substances 0.000 title claims abstract description 151
- 239000000126 substance Substances 0.000 title claims abstract description 54
- 238000000034 method Methods 0.000 title claims abstract description 52
- 238000004064 recycling Methods 0.000 title claims abstract description 12
- 239000007789 gas Substances 0.000 claims abstract description 92
- 239000007788 liquid Substances 0.000 claims abstract description 71
- 238000009833 condensation Methods 0.000 claims abstract description 8
- 230000005494 condensation Effects 0.000 claims abstract description 8
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims description 77
- YMWUJEATGCHHMB-UHFFFAOYSA-N Dichloromethane Chemical compound ClCCl YMWUJEATGCHHMB-UHFFFAOYSA-N 0.000 claims description 60
- 229910052757 nitrogen Inorganic materials 0.000 claims description 35
- YLQBMQCUIZJEEH-UHFFFAOYSA-N Furan Chemical compound C=1C=COC=1 YLQBMQCUIZJEEH-UHFFFAOYSA-N 0.000 claims description 18
- 238000012856 packing Methods 0.000 claims description 16
- 238000000926 separation method Methods 0.000 claims description 14
- 239000005416 organic matter Substances 0.000 claims description 13
- JWUJQDFVADABEY-UHFFFAOYSA-N 2-methyltetrahydrofuran Chemical compound CC1CCCO1 JWUJQDFVADABEY-UHFFFAOYSA-N 0.000 claims description 11
- 238000009835 boiling Methods 0.000 claims description 11
- 239000000463 material Substances 0.000 claims description 11
- 229910001873 dinitrogen Inorganic materials 0.000 claims description 10
- 238000011084 recovery Methods 0.000 claims description 10
- OKKJLVBELUTLKV-UHFFFAOYSA-N Methanol Chemical compound OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 claims description 9
- 239000002184 metal Substances 0.000 claims description 8
- QJGQUHMNIGDVPM-UHFFFAOYSA-N nitrogen group Chemical group [N] QJGQUHMNIGDVPM-UHFFFAOYSA-N 0.000 claims description 3
- 239000000945 filler Substances 0.000 claims description 2
- 239000002912 waste gas Substances 0.000 abstract description 16
- 238000007664 blowing Methods 0.000 abstract 3
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 23
- 238000007599 discharging Methods 0.000 description 9
- 239000012535 impurity Substances 0.000 description 8
- 238000004065 wastewater treatment Methods 0.000 description 8
- 238000005265 energy consumption Methods 0.000 description 6
- 239000012071 phase Substances 0.000 description 6
- 239000012267 brine Substances 0.000 description 5
- HPALAKNZSZLMCH-UHFFFAOYSA-M sodium;chloride;hydrate Chemical compound O.[Na+].[Cl-] HPALAKNZSZLMCH-UHFFFAOYSA-M 0.000 description 5
- 239000007787 solid Substances 0.000 description 5
- HYBBIBNJHNGZAN-UHFFFAOYSA-N furfural Chemical compound O=CC1=CC=CO1 HYBBIBNJHNGZAN-UHFFFAOYSA-N 0.000 description 4
- JHMIHJYIJSMCQH-UHFFFAOYSA-N azane;furan Chemical compound N.C=1C=COC=1 JHMIHJYIJSMCQH-UHFFFAOYSA-N 0.000 description 3
- 238000001816 cooling Methods 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 239000007791 liquid phase Substances 0.000 description 3
- 239000000203 mixture Substances 0.000 description 3
- 238000010992 reflux Methods 0.000 description 3
- 238000012360 testing method Methods 0.000 description 3
- VQKFNUFAXTZWDK-UHFFFAOYSA-N 2-Methylfuran Chemical compound CC1=CC=CO1 VQKFNUFAXTZWDK-UHFFFAOYSA-N 0.000 description 2
- 150000001412 amines Chemical class 0.000 description 2
- 239000006227 byproduct Substances 0.000 description 2
- 239000003795 chemical substances by application Substances 0.000 description 2
- 238000007906 compression Methods 0.000 description 2
- 238000004821 distillation Methods 0.000 description 2
- 230000007613 environmental effect Effects 0.000 description 2
- 238000001914 filtration Methods 0.000 description 2
- 238000010438 heat treatment Methods 0.000 description 2
- 230000001502 supplementing effect Effects 0.000 description 2
- 238000012546 transfer Methods 0.000 description 2
- XVRIEWDDMODMGA-UHFFFAOYSA-N 5-chloropentan-2-one Chemical compound CC(=O)CCCCl XVRIEWDDMODMGA-UHFFFAOYSA-N 0.000 description 1
- GMPKIPWJBDOURN-UHFFFAOYSA-N Methoxyamine Chemical compound CON GMPKIPWJBDOURN-UHFFFAOYSA-N 0.000 description 1
- 240000002853 Nelumbo nucifera Species 0.000 description 1
- 235000006508 Nelumbo nucifera Nutrition 0.000 description 1
- 235000006510 Nelumbo pentapetala Nutrition 0.000 description 1
- 229910000589 SAE 304 stainless steel Inorganic materials 0.000 description 1
- 239000002253 acid Substances 0.000 description 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000006835 compression Effects 0.000 description 1
- 238000005260 corrosion Methods 0.000 description 1
- 230000007797 corrosion Effects 0.000 description 1
- 239000012043 crude product Substances 0.000 description 1
- 238000011049 filling Methods 0.000 description 1
- 239000006260 foam Substances 0.000 description 1
- 230000005484 gravity Effects 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 239000011368 organic material Substances 0.000 description 1
- 239000012074 organic phase Substances 0.000 description 1
- 239000001301 oxygen Substances 0.000 description 1
- 229910052760 oxygen Inorganic materials 0.000 description 1
- 238000003672 processing method Methods 0.000 description 1
- 239000000047 product Substances 0.000 description 1
- 238000000746 purification Methods 0.000 description 1
- 239000013589 supplement Substances 0.000 description 1
- 239000012855 volatile organic compound Substances 0.000 description 1
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/20—Treatment of water, waste water, or sewage by degassing, i.e. liberation of dissolved gases
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D45/00—Separating dispersed particles from gases or vapours by gravity, inertia, or centrifugal forces
- B01D45/04—Separating dispersed particles from gases or vapours by gravity, inertia, or centrifugal forces by utilising inertia
- B01D45/06—Separating dispersed particles from gases or vapours by gravity, inertia, or centrifugal forces by utilising inertia by reversal of direction of flow
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J19/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
- B01J19/14—Production of inert gas mixtures; Use of inert gases in general
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
- F25J1/00—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures
- F25J1/02—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures requiring the use of refrigeration, e.g. of helium or hydrogen ; Details and kind of the refrigeration system used; Integration with other units or processes; Controlling aspects of the process
- F25J1/0228—Coupling of the liquefaction unit to other units or processes, so-called integrated processes
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2101/00—Nature of the contaminant
- C02F2101/30—Organic compounds
- C02F2101/34—Organic compounds containing oxygen
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2101/00—Nature of the contaminant
- C02F2101/30—Organic compounds
- C02F2101/36—Organic compounds containing halogen
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2101/00—Nature of the contaminant
- C02F2101/30—Organic compounds
- C02F2101/38—Organic compounds containing nitrogen
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2103/00—Nature of the water, waste water, sewage or sludge to be treated
- C02F2103/34—Nature of the water, waste water, sewage or sludge to be treated from industrial activities not provided for in groups C02F2103/12 - C02F2103/32
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- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Organic Chemistry (AREA)
- Environmental & Geological Engineering (AREA)
- Water Supply & Treatment (AREA)
- Life Sciences & Earth Sciences (AREA)
- Physics & Mathematics (AREA)
- Mechanical Engineering (AREA)
- Thermal Sciences (AREA)
- General Engineering & Computer Science (AREA)
- Hydrology & Water Resources (AREA)
- Physical Water Treatments (AREA)
Abstract
The invention provides a method and a system for recovering volatile substances in wastewater. The invention separates out organic matters by fully contacting the waste water with the stripping gas; pressurizing the separated organic matters, condensing and recovering; contacting the waste water with stripping gas through a stripping tower to change volatile substances in the waste water into gas, and condensing the gas into liquid under pressure for recycling; the internal circulation mode of the blowing gas solves the problems of large waste gas generation amount and difficult waste gas treatment of the traditional blowing method, and the organic matters of the blowing condensation can be continuously recycled or sold as products, thereby creating economic value for enterprises.
Description
Technical Field
The invention relates to the field of water treatment, in particular to a method and a system for recovering volatile substances in wastewater.
Background
Waste water containing volatile substances is generated in the production process of chemical enterprises, and the volatile substances mainly comprise organic substances such as dichloromethane, furan, 2-methyltetrahydrofuran, methanol and the like. The concentration of organic matters in the wastewater is high and exceeds the treatment load of a conventional physicochemical-biochemical wastewater treatment system of a chemical enterprise, and the traditional treatment mode adopts heating rectification to separate low-boiling organic matters in the wastewater, but the method has high energy consumption and long wastewater treatment period.
Patent CN208200427U discloses a method for stripping dichloromethane (2% -10% dichloromethane in waste water) from waste water and condensing to recover dichloromethane, but the method has several problems: firstly, waste water needs to be preheated to 50-60 ℃, extra steam needs to be supplied, and energy consumption is high; secondly, the boiling point of dichloromethane is 39.8 ℃ under the condition of normal pressure (102.18kpa), the wastewater is treated by utilizing the steam stripping principle, the flow rate of extracted dichloromethane non-condensable gas is high, the requirement on the cooling effect of a condenser is extremely high, and dichloromethane can be lost along with waste gas due to poor cooling effect; thirdly, the traditional steam stripping method can generate a large amount of waste gas, the boiling point of dichloromethane is low, the problem of secondary pollution caused by incomplete condensation easily exists, waste gas containing dichloromethane cannot directly enter a conventional heat accumulating type incinerator for treatment, and an additional waste gas treatment device needs to be additionally arranged.
In view of the above problems, a low-power consumption and high-efficiency processing method and system are needed.
Disclosure of Invention
In order to solve the problems in the prior art, the invention provides a method and a system for recovering volatile substances in wastewater.
In a first aspect, the present invention provides a method for recovering volatile substances in wastewater, comprising the following steps:
s1: contacting the wastewater with nitrogen to obtain an air flow containing volatile substances;
s2: and (4) pressurizing and condensing the gas flow containing the volatile substances obtained in the step (S1) and then recovering the gas flow.
As a specific embodiment of the present invention, in step S1, the volatile substance in the wastewater includes at least one of dichloromethane, furan, 2-methyltetrahydrofuran and methanol.
In a specific embodiment of the present invention, in step S1, the content of the volatile substances in the wastewater is 0.5 to 10 wt%.
In an embodiment of the present invention, in the step S2, the pressure value after pressurization is determined according to the boiling point of the separated volatile substance, and the pressure value after pressurization is preferably 700 to 1000Kpa (absolute pressure), and more preferably 726.70 to 903.21Kpa (absolute pressure).
In an embodiment of the present invention, in the step S2, the condensation temperature is determined according to the boiling point of the separated volatile substance, and the condensation temperature is preferably 0 to 20 ℃.
In a second aspect, the invention provides a system for recovering volatile substances in wastewater, which comprises a blowing-off device, a pressurizing device, a condensing device and a recovery device;
the stripping device is used for contacting the wastewater with nitrogen to separate volatile substances;
the pressurizing device is used for pressurizing the gas flow containing the volatile substances from the stripping device to obtain a pressurized material flow;
said condensing means is for condensing the pressurized stream;
the recovery device is used for separating and storing the condensed material flow.
As a specific embodiment of the invention, the air stripping device comprises an air stripping tower, the middle upper part of the air stripping tower is provided with a wastewater inlet and a wastewater distributor communicated with the wastewater inlet, and the bottom of the air stripping tower is provided with a wastewater outlet; the lower part of the stripping tower is provided with a gas inlet and a gas distributor, and the top of the stripping tower is provided with a gas-phase outlet, so that the wastewater sprayed by the wastewater distributor is in countercurrent contact with the gas sprayed by the gas distributor.
As a specific embodiment of the invention, at least one layer of corrugated metal wire mesh packing layer is arranged in the stripping tower; the waste water distributor nozzle type distributor; the gas distributor is a shower type gas distributor; the stripping tower also comprises a hole disc type redistributor arranged between the waste water distributor and the gas distributor; the stripping tower also comprises a demister arranged at the gas phase outlet; the gas source used in the blowing-off cycle is nitrogen, and the internal pressure of the blowing-off device is below 112Kpa (absolute pressure); the preferable feeding flow rate of the wastewater is 1-5 m3H; preferably, 2-4 layers of corrugated metal wire mesh packing layers are arranged in the stripping tower, and at least 2 layers of corrugated metal wire mesh packing layers are arranged between the waste water distributor and the gas distributor; more preferably, the orifice disk redistributor is arranged between the at least 2 layers of corrugated wire mesh filler layer.
As a specific embodiment of the present invention, the stripping device is a stripping tower, and the stripping tower is preferably a packed tower because the packed tower is suitable for a process with large gas handling capacity and small liquid handling capacity; more preferably a Φ 600 × 7500 packed column.
In order to increase the contact area of the gas phase and the liquid phase of the stripping tower and improve the mass transfer efficiency, a 316L wire mesh corrugated packing with the theoretical plate number of 4-5 n/m is preferably adopted in the stripping device, the height can be adjusted according to the separation difficulty, generally, the height of the packing is 3-5 m, and more preferably 4 m.
As a specific embodiment of the invention, in order to make the liquid phase uniformly distributed in the stripping tower and reduce the gas resistance, the redistributor in the tower is preferably a DN600, 316L hole disk distributor.
As an embodiment of the present invention, in order to make the stripping gas more uniform, the stripping gas inlet is preferably a DN300 shower distributor.
As a specific embodiment of the invention, in order to avoid the reaction between oxygen and organic matters in the wastewater and reduce the safety risk in the gas compression process, the gas source used in the blow-off cycle is nitrogen.
In the specific embodiment of the invention, the pressure of the gas storage tank is 726.70-903.21 Kpa (absolute pressure) in order to increase the boiling point of the volatile organic compounds to be higher than 80 ℃.
In order to increase the organic material volatility and to improve the stripping efficiency, the internal pressure of the stripping device is not more than 112Kpa (absolute pressure), and the gauge pressure is reflected to be 0.01MPa to 0.02MPa in actual operation.
As a specific embodiment of the invention, in order to control the speed of material inlet and outlet, the wastewater feed end and outlet end pipelines are provided with flow meters.
As a specific embodiment of the invention, in order to ensure complete stripping of volatile components in the wastewater, the feed flow rate of the wastewater is preferably 1-5 m3And h, adjusting the feeding flow rate and the discharging flow rate of the wastewater according to the components in the wastewater.
As a specific embodiment of the present invention, the synergy of the components in the blow-off device in actual operation: the middle upper part of the stripping device is provided with a wastewater feeding end and a wastewater backflow end, the outlet of the feeding end adopts a nozzle type distributor, regular corrugated wire mesh packing is adopted in the stripping device, a hole disc type distributor is arranged in the stripping device, the bottom of the stripping device is provided with a nitrogen inlet, the nitrogen inlet adopts a shower nozzle type distributor, so that the wastewater falls to fully contact with nitrogen, and the top of the stripping device is provided with a demister; according to the display of a flow meter arranged in front of the wastewater feeding end, the frequency of a wastewater delivery pump is adjusted, so that the wastewater inflow rate of the air stripping device is controlled, and the optimal wastewater inflow rate is 1-5 m3H; waste water gets into from the feed end of blowing-off device, through nozzle formula distributor evenly distributed to the packing layer, is the liquid film through the action of gravity along the packing surface and flows down, and gaseous then gets into from blowing-off device bottom seedpod of the lotus formula distributor, under the promotion of pressure difference, passes the clearance of packing layer, makes volatile material in the waste water become gaseous, removes the foam through blowing-off device top demister, discharges from blowing-off device top.
As a specific embodiment of the present invention, the pressurizing device is a screw compressor; preferably, the inlet of the pressurizing device is connected with the gas phase outlet of the stripping tower, and the outlet of the pressurizing device is connected with the inlet of the condensing device.
As an embodiment of the present invention, the pressurization is preferably a screw compressor, since part of the liquid condenses during the compression of the gas and to reduce the footprint of the equipment.
As a specific embodiment of the invention, the feeding end of the condensing device is connected with the discharging end of the pressurizing device, and the bottom of the condensing device is provided with condensate and nitrogen outlet pipes; and the condensing device condenses volatile components in the nitrogen at the discharge end of the pressurizing device into liquid.
As a specific embodiment of the invention, the recovery device comprises a gas-liquid separator and a liquid storage device; the gas-liquid separator is provided with a feed inlet, a nitrogen gas outlet, an organic matter discharge port and a baffle plate, the baffle plate is arranged between the feed inlet and the nitrogen gas outlet to form a liquid separation channel, and the organic matter discharge port is arranged at the bottom of the gas-liquid separator and communicated with the liquid separation channel; the inlet of the liquid storage device is connected with the organic matter discharge hole; preferably, the feed inlet with the nitrogen gas outlet is located gas-liquid separator's upper portion and relative setting, gas-liquid separator's lower part is provided with the liquid separation board, the organic matter discharge gate via the liquid separation board with divide liquid channel intercommunication.
In the present invention, a baffling type gas-liquid separator is used as the separation means to completely separate the liquid organic substances in the gas phase.
As a specific embodiment of the invention, in order to supplement nitrogen in the original driving process and prevent the accidental loss of the nitrogen in the use process, a nitrogen supplementing feeding end is arranged on the liquid storage part.
As a specific embodiment of the invention, in order to ensure the use safety of equipment, avoid environmental corrosion and reduce the discharge frequency of organic matters, the material of the liquid storage part is 304 steel, the shape can be a vertical storage tank, and the preferred shape is 1.5m3Can-shaped.
As a specific implementation mode of the invention, the working principle of the system for recovering volatile substances in the wastewater is as follows:
the traditional stripping and steam stripping method is a method for removing dissolved gases or volatile substances in wastewater. The principle is that gas is blown into waste water to change the dissolved gas or volatile matter into gas which is diffused into gas diffusing agent airflow, thereby achieving the process of purifying water quality. The method has the advantages of high treatment efficiency, low energy consumption and the like, but has the problems of large waste gas generation amount and difficult collection of organic matter components in the waste gas, the invention improves the traditional stripping method, the gas at the outlet of the stripping tower is compressed by a gas compressor to 726.70-903.21 Kpa (absolute pressure), the boiling point of dichloromethane is increased to 110-120 ℃ from 39.8 ℃, the condensation and recovery are easy, the stripping gas adopts a nitrogen closed cycle mode, the secondary pollution is not generated, and the problems are effectively solved.
As a specific implementation mode of the invention, the system for recovering volatile substances in wastewater has the following working procedures:
s1: starting a gas condensing device to enter and exit frozen brine, and filling a certain amount of nitrogen into a liquid storage device;
s2: opening an air inlet valve of a liquid storage device;
s3: starting the pressurizing device, and after the pressurizing device is completely started, opening an air inlet valve of the blow-off device and adjusting the air inlet flow of blow-off gas to ensure that the internal pressure of the blow-off device is stable;
s4: the gas stably runs for 5-20 minutes, starting wastewater to enter from the feed end of the stripping device, discharging qualified wastewater from the bottom of the stripping device after nitrogen stripping and separating organic matters in the wastewater, and adjusting the backflow flow rate of the wastewater at the bottom of the stripping device according to the composition of the wastewater and the content of the organic matters in the effluent of the stripping device;
s5: and the gas after stripping is discharged from the top of the stripping device, after solid impurities are separated by the defoaming device, the gas is pressurized by the pressurizing device, after the gas pressure is increased, the boiling point of the volatile substance is increased, the volatile substance is cooled by the condensing device, the condensed volatile substance flows into the liquid storage device through the separating device, and the stripping gas returns to the stripping device after passing through the separating device and is continuously recycled.
Compared with the prior art, the invention has the beneficial effects that:
1. the principle of the method and the system for recovering volatile substances in waste water is that gas is blown into the waste water, so that dissolved gas or volatile substances are changed into gas and diffused into gas diffusing agent airflow, and the process of purifying water quality is achieved. The method has the advantages of high treatment efficiency, low energy consumption and the like, and the traditional stripping method has the problems of large waste gas generation amount and difficult collection of organic matter components in the waste gas.
2. The embodiment of the invention shows that the invention can treat the wastewater containing dichloromethane, 2-methyltetrahydrofuran and furan, and has good removal effect on micromolecular and volatile amine substances; after the wastewater is treated by the method, the organic matter content of the wastewater is obviously reduced, and the wastewater can directly enter a traditional biochemical system to be treated until the wastewater reaches the standard and is discharged.
3. The method and the system for recovering volatile substances in the wastewater adopt a nitrogen stripping and stripping gas internal circulation mode, so that waste gas and secondary pollution are avoided.
4. The method and the system for recovering volatile substances in the wastewater treat the wastewater at room temperature without heating or cooling the wastewater, and have lower energy consumption compared with treatment methods such as distillation or rectification and the like.
Drawings
FIG. 1 is a schematic view of a system for recovering volatile substances in wastewater according to example 1 of the present invention;
FIG. 2 is a schematic view of the structure of a stripping column in example 1 of the present invention;
FIG. 3 is a schematic view showing the structure of a gas-liquid separation apparatus in example 1 of the present invention.
Wherein, 11-wastewater feed pump; 12-a waste water filter; 13-a stripping column; 21-a gas compressor; 31-a condenser; 41-a gas-liquid separation device; 42-a liquid storage tank;
1301-a demister; 1302-wire mesh packing; 1303-supporting grid plate; 1304-a wastewater inlet; 1305-nozzle distributors; 1306-hole disk redistributor; 1307-showerhead gas distributor; 1308 — gas inlet; 1309-stripping tower body; 13010-waste water outlet of stripping tower; 13011-skirt support; 13012-gas phase outlet of stripping tower;
4101-gas inlet; 4102-gas outlet; 4103-baffle plate; 4104-liquid separation plate; 4105-automatic water drain valve; 4106-liquid phase outlet.
Detailed Description
The present invention is further illustrated by the following examples, which are not to be construed as limiting the invention in any way.
The stripping column used in the examples of the present invention was a phi 600 x 7500 packed column.
Example 1
The embodiment provides a system and an operation flow for recovering volatile substances in wastewater, and the specific details are as follows:
a system for recovering volatile substances from waste water, comprising: the device comprises a stripping device, a pressurizing device, a condensing device and a recovery device; wherein the stripping device comprises a wastewater feeding pump 11, a wastewater filter 12 and a stripping tower 13, and the stripping tower 13 consists of a skirt support 13011 and a tower body 1309; a wastewater feeding end 1304 is arranged at the middle upper part of the tower body 1309, a flow meter is arranged in front of the wastewater feeding end 1304, and the wastewater feeding end is connected with a nozzle type water inlet distributor 1305; regular corrugated metal wire mesh packing 1302 is adopted in the stripping tower, 2-4 layers of metal wire mesh packing are arranged according to the height of the tower, 3 layers are arranged in the embodiment, and the metal wire mesh packing 1302 is supported on the wall of the stripping tower through a support grid plate 1303; a perforated disc distributor 1306 is arranged in the middle of the stripping tower, a stripping gas inlet 1308 and a shower type gas dispersing port 1307 are arranged at the bottom of the stripping tower, the waste water falls and contacts the stripping gas in the perforated disc distributor 1306, a waste gas outlet port 13012 is arranged at the top of the stripping device, and a demister 1301 is arranged at the front section of the waste gas outlet; the bottom is provided with a waste water outlet 13010.
The pressurizing device comprises a screw type gas compressor 21, the feed end of the gas compressor 21 is connected with the waste gas outlet end at the top of the stripping tower, and the outlet end of the gas compressor is connected with the inlet of the condenser 31;
the condensing device is a condenser 31, the feed end of the condenser is connected with the outlet end of the gas compressor 21, and the bottom of the condenser is provided with condensate and nitrogen outlet pipes; the condenser condenses volatile components in the compressed nitrogen at the discharge end of the gas compressor 21 into liquid;
the recovery device comprises a gas-liquid separator 41 and a liquid storage tank 42, the feed end of the gas-liquid separator 41 is connected with the discharge end of the condenser 31, and the discharge end 4106 of the gas-liquid separator 41 is connected with the liquid storage tank 42; the top of the gas-liquid separator 41 is provided with a nitrogen gas outlet 4102 which is connected with the nitrogen gas inlet end of the stripping tower 13, and the nitrogen gas can be recycled; a gas-liquid mixture inlet 4101 at the top of the gas-liquid separator 41, wherein baffle plates 4103 and liquid separation plates 4104 are arranged inside the gas-liquid separator, the baffle plates are arranged in a staggered manner to increase the contact area, and the condensed gas-liquid mixture is separated into nitrogen and recovered organic matters; the top of the liquid storage tank 42 is provided with a feed end connected with the gas-liquid separator 41 and a supplementary nitrogen feed end.
The operation flow of the system for recovering volatile substances in wastewater in example 1 is as follows:
s1: the gas condenser 31 is opened to allow the frozen brine to enter and exit, the liquid storage tank 42 is filled with nitrogen with certain pressure, and the liquid inlet valve of the gas storage tank is opened. And starting the compressor 21, opening an air inlet valve of the stripping tower 13 after the compressor 21 is completely started, and adjusting the flow of inlet nitrogen to ensure that the tower pressure of the stripping tower 13 is between 0.01 and 0.02MPa (gauge pressure). The gas was run for 10 minutes with stability.
S2: after solid impurities in the wastewater are filtered by a wastewater delivery pump 11 and a wastewater filter 12, continuously feeding the wastewater from a stripping tower 13 at a certain flow rate, after feeding for 10min, opening an adjusting valve on a water outlet pipeline at the bottom of the stripping tower 13, controlling a certain water outlet flow rate to be consistent with the water inlet flow rate, transferring the effluent of the stripping tower into a water outlet collecting tank, and adjusting the wastewater flow rate in the stripping tower 13 according to the wastewater quality and the effluent quality of the stripping tower after the kettle bottom of the stripping tower 13 reflows.
S3: the drain valve at the bottom of the liquid storage tank 42 is periodically opened to drain the condensed and recovered organic matter.
S4: if the pressure of the liquid storage tank 42 is reduced to be below 0.6MPa (gauge pressure) in the operation process, nitrogen is supplemented to be 0.65-0.80 MPa (gauge pressure).
Example 2
The embodiment provides a method for recycling dichloromethane in wastewater, which is realized by adopting the device provided in embodiment 1, wherein the treated object is wastewater of a furan ammonium salt project, and the main components of the furan ammonium salt wastewater are 98.00-99.00 wt% of water, 0.8-1.5 wt% of dichloromethane, 0.03-0.05 wt% of furan ammonium salt, 0.05-0.08 wt% of furoic acid, 0.08-0.17 wt% of methoxyamine and 0.04-0.20 wt% of other organic impurities. The method comprises the following specific steps:
s1: the gas condenser 31 is opened to allow the frozen brine to enter and exit, the liquid storage tank 42 is filled with nitrogen gas of 0.70MPa (gauge pressure), and the liquid inlet valve of the gas storage tank is opened. And starting the compressor 21, opening an air inlet valve of the stripping tower 13 after the compressor 21 is completely started, and adjusting the flow of inlet nitrogen to ensure that the tower pressure of the stripping tower 13 is between 0.01 and 0.02MPa (gauge pressure). The gas was run for 10 minutes with stability.
S2: the wastewater (pH 7) in the wastewater collection tank is filtered by a wastewater filter 12 through a wastewater transfer pump 11 to remove solid impurities, and then the wastewater is filtered at 5.0m3H flow rate, continuously feeding the material from the stripping tower 13, after feeding for 10min, opening an adjusting valve on a water outlet pipeline at the bottom of the stripping tower 13, and controlling the water outlet flow rate to be 5.0m3H, keeping the flow rate consistent with the inflow water, transferring the effluent of the stripping tower into an effluent collecting tank, and refluxing the kettle bottom of the stripping tower 13 to the flow rate of the wastewater in the stripping tower 13 of 1.0m3/h。
S3: and detecting the COD of the wastewater in the wastewater collection tank every 2 hours, discharging the effluent COD less than or equal to 2500mg/L into a biochemical system of an environment-friendly workshop for treatment.
S4: and opening a liquid discharge valve at the bottom of the liquid storage tank 42 every 5 hours, and recycling the dichloromethane and discharging the recycled dichloromethane into the dichloromethane storage tank for recycling.
S5: when the pressure of the liquid storage tank 42 is reduced to be below 0.6MPa (gauge pressure) in the operation process, nitrogen is supplemented to be 0.65-0.80 MPa (gauge pressure).
The test results before and after the wastewater treatment in example 2 are shown in Table 1:
TABLE 1 test results before and after wastewater treatment in example 2
Example 2 shows that the effluent data of the stripping tower is stable, the COD removal rate is 87.36-88.43%, the total nitrogen removal rate is 82.31-83.61%, and the total recovery rate of dichloromethane is 1076.5kg, the stripping method can recover dichloromethane in the wastewater, and can also remove other amines with low boiling point and other organic matters in the wastewater, thereby reducing the difficulty of wastewater treatment.
Example 3
The embodiment provides a method for recycling 2-methyltetrahydrofuran in wastewater, which is implemented by adopting the device provided in embodiment 1, the treated wastewater is wastewater of a 5-chloro-2-pentanone project process, and the wastewater of the project mainly comprises 91.5-94.5 wt% of water, 5.0-8.0 wt% of 2-methyltetrahydrofuran, 0.3-0.5 wt% of 2-methylfuran and 0.1-0.2 wt% of other organic impurities. The method comprises the following specific steps:
s1: the gas condenser is started to enter and exit frozen brine, the liquid storage tank is filled with nitrogen with the pressure of 0.70MPa (gauge pressure), and the gas inlet valve of the gas storage tank is started. Starting the compressor, opening an air inlet valve of the stripping tower after the compressor is completely started, adjusting the flow of inlet nitrogen to ensure that the tower pressure of the stripping tower is between 0.01 and 0.02MPa (gauge pressure), and stably operating the gas for 10 minutes.
S2: filtering solid impurities in wastewater (pH 8) in a wastewater collecting tank by a wastewater conveying pump through a wastewater filter, and then filtering by 3.0m3H flow rate, continuously feeding the material from the stripping tower, after feeding for 10min, opening an adjusting valve on a water outlet pipeline at the bottom of the stripping tower, and controlling the water outlet flow rate to be 3.0m3H, keeping the flow rate consistent with the inflow water, and transferring the wastewater into a wastewater collection tank; the kettle bottom of the stripping tower refluxes to the stripping tower for wasteThe water flow rate is 6.0m3/h。
S3: and detecting the COD of the wastewater in the wastewater collection tank every 2 hours, discharging the effluent COD less than or equal to 2500mg/L into a biochemical system of an environment-friendly workshop for treatment.
S4: opening a liquid discharge valve at the bottom of the liquid storage tank every 2 hours, recovering the 2-methyltetrahydrofuran, discharging into a temporary tank, and separately rectifying and recovering the byproduct 2-methyltetrahydrofuran.
S5: when the pressure of the liquid storage tank is reduced to be below 0.6MPa (gauge pressure) in the operation process, nitrogen is supplemented to be 0.65-0.80 MPa (gauge pressure).
The results of examination of the wastewater before and after the treatment in example 3 are shown in Table 2:
TABLE 2 examination results before and after wastewater treatment in example 3
Example 3 shows that the effluent data of the stripping tower is stable, the COD removal rate is 98.30-98.49%, and the treated wastewater can directly enter an environmental protection workshop biochemical system for treatment. 3178.6kg of 2-methyltetrahydrofuran is totally recovered, wherein the content of the 2-methyltetrahydrofuran is 98.7 percent, the moisture content is 0.38 percent, and the recovered 2-methyltetrahydrofuran can be sold as a byproduct after rectification and purification.
Example 4
The embodiment provides a treatment method for recovering furan in wastewater, which is realized by adopting the device provided by the embodiment 1, the treated wastewater is furan project process wastewater, and the main components of the project wastewater are 97.3-98.6 wt% of water, 1.0-2.0 wt% of furan, 0.3-0.5 wt% of furfural and 0.1-0.2 wt% of other organic impurities. The method comprises the following specific steps:
s1: the gas condenser is opened to allow the frozen brine to enter and exit, the liquid storage tank is filled with nitrogen at 0.75MPa (gauge pressure), and the gas inlet valve of the gas storage tank is opened. And starting the compressor, opening an air inlet valve of the stripping tower after the compressor is completely started, and adjusting the flow of inlet nitrogen to ensure that the tower pressure of the stripping tower is between 0.01 and 0.02MPa (gauge pressure). The gas was run steadily for 10 minutes.
S2: in a waste water collecting tankThe wastewater (pH 7) was filtered through a wastewater filter with a wastewater pump to remove solid impurities, and then was treated at 5.0m3H flow rate, continuously feeding the material from the stripping tower, opening an adjusting valve on a water outlet pipeline at the bottom of the stripping tower after feeding for 10min, and controlling the water outlet flow rate to be 5.0m3H, keeping the flow rate consistent with the inflow water, and transferring the wastewater into a wastewater collection tank; the bottom of the stripping tower refluxes to the waste water flow rate of 3.0m in the stripping tower3/h。
S3: and detecting the COD of the wastewater in the wastewater collection tank every 2 hours, discharging the effluent COD less than or equal to 2500mg/L into a biochemical system of an environment-friendly workshop for treatment.
S4: opening a liquid discharge valve at the bottom of the liquid storage tank every 2 hours, and discharging the recovered organic phase into a temporary storage tank.
S5: and when the pressure of the liquid storage tank is reduced to be below 0.7MPa (gauge pressure) in the operation process, supplementing nitrogen to be 0.75-0.80 MPa (gauge pressure).
The results of examination of the wastewater before and after the treatment in example 4 are shown in Table 3:
table 3 test results before and after wastewater treatment in example 4
Example 4 shows that the effluent data of the stripping tower is stable, the COD removal rate is 91.28-92.26%, and the treated wastewater can directly enter an environment-friendly workshop biochemical system for treatment. The total amount of the furan crude product recovered by stripping is 111.7kg, wherein the furan content is 78.7 wt%, the furfural content is 18.4 wt%, and the water content is 1.73 wt%.
In conclusion, the method and the system for recycling the volatile substances in the wastewater can completely remove the volatile organic substances in the wastewater, reduce the difficulty of wastewater treatment, and can directly enter a biochemical system of a chemical enterprise for treatment to reach the standard. Compared with distillation and rectification, the energy consumption is lower. The method and the system of the invention are improved on the basis of the traditional stripping method, and the problems of large waste gas generation amount and difficult waste gas treatment of the traditional stripping method are solved by the modes of pressurization condensation and internal circulation of stripping gas, and the stripped condensed organic matter can be continuously recycled or sold as a product, thereby creating economic value for enterprises.
Any numerical value mentioned in this specification, if there is only a two unit interval between any lowest value and any highest value, includes all values from the lowest value to the highest value incremented by one unit at a time. For example, if it is stated that the amount of a component, or a value of a process variable such as temperature, pressure, time, etc., is 50 to 90, it is meant in this specification that values of 51 to 89, 52 to 88 … …, and 69 to 71, and 70 to 71, etc., are specifically enumerated. For non-integer values, units of 0.1, 0.01, 0.001, or 0.0001 may be considered as appropriate. These are only some specifically named examples. In a similar manner, all possible combinations of numerical values between the lowest value and the highest value enumerated are to be considered to be disclosed in this application.
It should be noted that the above-mentioned embodiments are only for explaining the present invention, and do not constitute any limitation to the present invention. The present invention has been described with reference to exemplary embodiments, but the words which have been used herein are words of description and illustration, rather than words of limitation. The invention can be modified, as prescribed, within the scope of the claims and without departing from the scope and spirit of the invention. Although the invention has been described herein with reference to particular means, materials and embodiments, the invention is not intended to be limited to the particulars disclosed herein, but rather extends to all other methods and applications having the same functionality.
Claims (10)
1. A method for recovering volatile substances in wastewater is characterized by comprising the following steps:
s1: contacting the wastewater with nitrogen to obtain an air flow containing volatile substances;
s2: the volatile substance-containing gas stream obtained in step S1 is recovered after being pressurized and condensed.
2. The method for recycling volatile substances in wastewater according to claim 1, wherein in step S1, the volatile substances in wastewater include at least one of dichloromethane, furan, 2-methyltetrahydrofuran and methanol.
3. The method for recycling volatile substances in wastewater according to claim 1 or 2, wherein in step S1, the content of volatile substances in the wastewater is 0.5-10 wt%.
4. The method for recycling volatile substances in wastewater according to any one of claims 1 to 3, wherein in the step S2, the pressure value after pressurization is determined according to the boiling point of the separated volatile substances, and the pressure value after pressurization is preferably 700 to 1000Kpa, and more preferably 726.70 to 903.21 Kpa.
5. The method for recycling volatile substances in wastewater according to any one of claims 1 to 4, wherein in step S2, the condensation temperature is determined according to the boiling point of the separated volatile substances, and the condensation temperature is preferably 0-20 ℃.
6. A system for recovering volatile substances in wastewater, comprising: the device comprises a stripping device, a pressurizing device, a condensing device and a recovery device;
the stripping device is used for contacting the wastewater with nitrogen to separate volatile substances;
the pressurizing device is used for pressurizing the gas flow containing the volatile substances from the blow-off device to obtain a pressurized material flow;
said condensing means is for condensing the pressurized stream;
the recovery device is used for separating and storing the condensed material flow.
7. The system of claim 6, wherein the stripping device comprises a stripping tower, a wastewater inlet and a wastewater distributor communicated with the wastewater inlet are arranged at the middle upper part of the stripping tower, and a wastewater outlet is arranged at the bottom of the stripping tower; the lower part of the stripping tower is provided with a gas inlet and a gas distributor, and the top of the stripping tower is provided with a gas phase outlet, so that the wastewater sprayed by the wastewater distributor is in countercurrent contact with the gas sprayed by the gas distributor.
8. The system according to claim 6 or 7, characterized in that at least one layer of corrugated wire mesh packing layer is arranged in the stripping tower;
and/or, the waste water distributor nozzle distributor;
and/or, the gas distributor is a shower-type gas distributor;
and/or the stripping tower further comprises a hole disc type redistributor arranged between the waste water distributor and the gas distributor;
and/or the stripping tower further comprises a demister arranged at the gas phase outlet;
and/or the air source used in the blowing-off cycle is nitrogen, and the internal pressure of the blowing-off device is below 112 Kpa; the preferable feeding flow rate of the wastewater is 1-5 m3/h；
Preferably, 2-4 layers of corrugated metal wire mesh packing layers are arranged in the stripping tower, and at least 2 layers of corrugated metal wire mesh packing layers are arranged between the waste water distributor and the gas distributor; more preferably, the orifice disk redistributor is disposed between the at least 2 layers of corrugated wire mesh filler layer.
9. The system of any one of claims 6-8, wherein the pressurization device is a screw compressor;
preferably, the inlet of the pressurizing device is connected with the gas phase outlet of the stripping tower, and the outlet of the pressurizing device is connected with the inlet of the condensing device.
10. The system according to any one of claims 6 to 9, wherein the recovery device comprises a gas-liquid separator and a liquid storage device;
the gas-liquid separator is provided with a feed inlet, a nitrogen gas outlet, an organic matter discharge port and a baffle plate, the baffle plate is arranged between the feed inlet and the nitrogen gas outlet to form a liquid separation channel, and the organic matter discharge port is arranged at the bottom of the gas-liquid separator and communicated with the liquid separation channel;
the inlet of the liquid storage device is connected with the organic matter discharge hole;
preferably, the feed inlet with the nitrogen gas outlet is located gas-liquid separator's upper portion and relative setting, gas-liquid separator's lower part is provided with the liquid separation board, the organic matter discharge gate via the liquid separation board with divide liquid channel intercommunication.
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| CN115624773A (en) * | 2022-10-12 | 2023-01-20 | 万华化学集团股份有限公司 | Devolatilization device and method for removing small molecular substances and reducing odor in polyether polyol |
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| CN115624773A (en) * | 2022-10-12 | 2023-01-20 | 万华化学集团股份有限公司 | Devolatilization device and method for removing small molecular substances and reducing odor in polyether polyol |
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