CN116081793A - Ethylene waste alkali liquid treatment method and treatment device - Google Patents
Ethylene waste alkali liquid treatment method and treatment device Download PDFInfo
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- CN116081793A CN116081793A CN202111279094.7A CN202111279094A CN116081793A CN 116081793 A CN116081793 A CN 116081793A CN 202111279094 A CN202111279094 A CN 202111279094A CN 116081793 A CN116081793 A CN 116081793A
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- 239000002699 waste material Substances 0.000 title claims abstract description 141
- 239000003513 alkali Substances 0.000 title claims abstract description 103
- 239000007788 liquid Substances 0.000 title claims abstract description 78
- 238000000034 method Methods 0.000 title claims abstract description 68
- 239000005977 Ethylene Substances 0.000 title claims abstract description 55
- VGGSQFUCUMXWEO-UHFFFAOYSA-N Ethene Chemical compound C=C VGGSQFUCUMXWEO-UHFFFAOYSA-N 0.000 title claims abstract description 54
- 238000009279 wet oxidation reaction Methods 0.000 claims abstract description 62
- 239000007789 gas Substances 0.000 claims abstract description 35
- 238000007670 refining Methods 0.000 claims abstract description 24
- 238000000926 separation method Methods 0.000 claims abstract description 18
- 238000006243 chemical reaction Methods 0.000 claims abstract description 16
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims abstract description 11
- 239000001301 oxygen Substances 0.000 claims abstract description 11
- 229910052760 oxygen Inorganic materials 0.000 claims abstract description 11
- 239000007791 liquid phase Substances 0.000 claims abstract description 10
- 238000001816 cooling Methods 0.000 claims abstract description 5
- 239000000463 material Substances 0.000 claims description 18
- 238000003860 storage Methods 0.000 claims description 16
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 14
- KAKZBPTYRLMSJV-UHFFFAOYSA-N Butadiene Chemical compound C=CC=C KAKZBPTYRLMSJV-UHFFFAOYSA-N 0.000 claims description 10
- RRHGJUQNOFWUDK-UHFFFAOYSA-N Isoprene Chemical compound CC(=C)C=C RRHGJUQNOFWUDK-UHFFFAOYSA-N 0.000 claims description 10
- 238000007254 oxidation reaction Methods 0.000 claims description 10
- 239000000126 substance Substances 0.000 claims description 10
- LSDPWZHWYPCBBB-UHFFFAOYSA-N Methanethiol Chemical compound SC LSDPWZHWYPCBBB-UHFFFAOYSA-N 0.000 claims description 9
- UCKMPCXJQFINFW-UHFFFAOYSA-N Sulphide Chemical compound [S-2] UCKMPCXJQFINFW-UHFFFAOYSA-N 0.000 claims description 8
- 238000007667 floating Methods 0.000 claims description 8
- 230000003647 oxidation Effects 0.000 claims description 8
- ISWSIDIOOBJBQZ-UHFFFAOYSA-N Phenol Chemical compound OC1=CC=CC=C1 ISWSIDIOOBJBQZ-UHFFFAOYSA-N 0.000 claims description 7
- 150000001993 dienes Chemical class 0.000 claims description 6
- 239000010812 mixed waste Substances 0.000 claims description 6
- 239000003208 petroleum Substances 0.000 claims description 6
- 238000000197 pyrolysis Methods 0.000 claims description 6
- 230000035484 reaction time Effects 0.000 claims description 5
- 239000013505 freshwater Substances 0.000 claims description 3
- 230000003197 catalytic effect Effects 0.000 claims description 2
- 230000005484 gravity Effects 0.000 claims description 2
- 238000009423 ventilation Methods 0.000 claims description 2
- 150000003568 thioethers Chemical class 0.000 claims 1
- 230000007774 longterm Effects 0.000 abstract description 5
- 238000005265 energy consumption Methods 0.000 abstract description 4
- HEMHJVSKTPXQMS-UHFFFAOYSA-M sodium hydroxide Inorganic materials [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 72
- 239000010865 sewage Substances 0.000 description 8
- 239000012071 phase Substances 0.000 description 7
- 150000004763 sulfides Chemical class 0.000 description 7
- 238000005406 washing Methods 0.000 description 7
- 239000002351 wastewater Substances 0.000 description 5
- QAOWNCQODCNURD-UHFFFAOYSA-L Sulfate Chemical compound [O-]S([O-])(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-L 0.000 description 4
- 230000000694 effects Effects 0.000 description 4
- 229920000642 polymer Polymers 0.000 description 4
- DHCDFWKWKRSZHF-UHFFFAOYSA-N sulfurothioic S-acid Chemical compound OS(O)(=O)=S DHCDFWKWKRSZHF-UHFFFAOYSA-N 0.000 description 4
- 238000010438 heat treatment Methods 0.000 description 3
- 150000007524 organic acids Chemical class 0.000 description 3
- 235000005985 organic acids Nutrition 0.000 description 3
- 239000003507 refrigerant Substances 0.000 description 3
- 150000001875 compounds Chemical class 0.000 description 2
- 238000005238 degreasing Methods 0.000 description 2
- 238000001514 detection method Methods 0.000 description 2
- 238000006116 polymerization reaction Methods 0.000 description 2
- 230000001502 supplementing effect Effects 0.000 description 2
- ZCYVEMRRCGMTRW-UHFFFAOYSA-N 7553-56-2 Chemical compound [I] ZCYVEMRRCGMTRW-UHFFFAOYSA-N 0.000 description 1
- CBENFWSGALASAD-UHFFFAOYSA-N Ozone Chemical compound [O-][O+]=O CBENFWSGALASAD-UHFFFAOYSA-N 0.000 description 1
- 239000002253 acid Substances 0.000 description 1
- 150000001299 aldehydes Chemical class 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000000903 blocking effect Effects 0.000 description 1
- 239000003153 chemical reaction reagent Substances 0.000 description 1
- 230000000052 comparative effect Effects 0.000 description 1
- IYRDVAUFQZOLSB-UHFFFAOYSA-N copper iron Chemical compound [Fe].[Cu] IYRDVAUFQZOLSB-UHFFFAOYSA-N 0.000 description 1
- 230000006837 decompression Effects 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- SOCTUWSJJQCPFX-UHFFFAOYSA-N dichromate(2-) Chemical compound [O-][Cr](=O)(=O)O[Cr]([O-])(=O)=O SOCTUWSJJQCPFX-UHFFFAOYSA-N 0.000 description 1
- 238000007599 discharging Methods 0.000 description 1
- 239000003814 drug Substances 0.000 description 1
- 238000005868 electrolysis reaction Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 238000001704 evaporation Methods 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 230000002401 inhibitory effect Effects 0.000 description 1
- 229910052740 iodine Inorganic materials 0.000 description 1
- 239000011630 iodine Substances 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 150000002978 peroxides Chemical class 0.000 description 1
- 239000012716 precipitator Substances 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
- 238000003672 processing method Methods 0.000 description 1
- 239000000047 product Substances 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 150000003839 salts Chemical class 0.000 description 1
- 229910052708 sodium Inorganic materials 0.000 description 1
- 239000011734 sodium Substances 0.000 description 1
- 159000000000 sodium salts Chemical class 0.000 description 1
- 239000013589 supplement Substances 0.000 description 1
- 238000012546 transfer Methods 0.000 description 1
- 239000002912 waste gas Substances 0.000 description 1
- 238000003911 water pollution Methods 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
- C02F1/72—Treatment of water, waste water, or sewage by oxidation
-
- 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
- C02F1/40—Devices for separating or removing fatty or oily substances or similar floating material
-
- 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
- C02F2001/007—Processes including a sedimentation step
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- Chemical & Material Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- Hydrology & Water Resources (AREA)
- Engineering & Computer Science (AREA)
- Environmental & Geological Engineering (AREA)
- Water Supply & Treatment (AREA)
- Organic Chemistry (AREA)
- Analytical Chemistry (AREA)
- Treatment Of Water By Oxidation Or Reduction (AREA)
Abstract
The invention relates to a treatment method and a treatment device of ethylene waste alkali liquid, which mainly comprise an oil removal unit, a heat exchange unit, a wet oxidation unit and a gas-liquid separation unit, wherein the heat exchange unit mainly comprises a first heat exchanger and a second heat exchanger which use the same heat exchange medium; adding a proper amount of oil refining waste lye into ethylene waste lye, carrying out oil removal treatment, then conveying the treated ethylene waste lye to a first heat exchanger of a heat exchange unit, conveying the heated waste lye to a wet oxidation unit, carrying out contact reaction with oxygen-containing gas under the pressure condition that the waste lye is kept in a liquid phase, enabling the reacted waste lye to enter a second heat exchanger of the heat exchange unit, cooling and decompressing the waste lye after heat exchange, and then entering a gas-liquid separation unit. Aiming at the characteristics of ethylene waste alkali liquor, the invention can fully utilize the reaction heat, reduce the operation energy consumption, and simultaneously avoid the problems of heat exchange equipment blockage and scaling caused in long-term operation, local overtemperature of the wet oxidation reactor and the like.
Description
Technical Field
The invention belongs to the technical field of water pollution treatment, and particularly relates to a treatment method and a treatment device for ethylene waste alkali liquid.
Background
In the ethylene production process, an alkaline washing method is generally adopted at present to remove CO in the pyrolysis gas 2 、H 2 S and other acid gases. The alkaline washing process produces a large amount of waste lye which contains, in addition to the remaining NaOH, na generated during the alkaline washing process 2 S、Na 2 CO 3 And inorganic salts. On the other hand, in the alkaline washing process, heavy components in the cracked gas are condensed and diolefins and aldehydes are polymerized to cause a large amount of organic matters to enter the waste alkali liquid. Because the ethylene waste alkali liquor contains high-concentration COD and sulfides, the biodegradability is poor, and most of treatment schemes for the ethylene waste alkali liquor at home and abroad are to firstly pretreat and remove the sulfides and organic matters in the ethylene waste alkali liquor so as to prevent the impact on biochemical systems of sewage treatment sites.
CN201010518009.31 discloses a method for treating ethylene waste lye, firstly, wet oxidation treatment is carried out on the ethylene waste lye to remove most sulfide and partial COD, then treatment is carried out by an iron-copper micro-electrolysis reactor which is introduced with ozone, biodegradability of waste water is improved, a precipitator is added to further remove sulfide and harmful substances in the waste water, and then biochemical treatment is carried out to further remove COD in the waste water. The method has the advantages of good sulfide and COD treatment effect and stable effluent quality. However, a plurality of medicaments are required to be added in the treatment process, the operation cost is high, and secondary pollution can be generated in the treatment process.
CN201310537921.7 discloses a method for treating ethylene waste alkali liquor, which adopts a combined process of air floatation degreasing-Gao Wenshi type oxidation-evaporation concentration-alkali concentration adjustment, can efficiently remove COD and sulfides in the ethylene waste alkali liquor, can recover sodium salt, and can recycle the treated sodium hydroxide solution, thereby realizing zero emission of the ethylene waste alkali liquor. But the operation energy consumption is high due to the high operation temperature.
In order to reduce the operation energy consumption and realize the effective utilization of heat, researchers propose to arrange a heat exchanger in front of a wet oxidation reactor, and preheat the imported waste lye by utilizing wet oxidized materials, so as to reduce the steam consumption of a reaction device.
US20050171390A1 discloses a wet oxidation treatment process and system in which wastewater of one or more compounds having carbon-heteroatom bonds is subjected to wet oxidation treatment at elevated temperature and pressure to break the carbon-heteroatom bonds of at least one of the compounds, and the treated wastewater is passed to a subsequent advanced oxidation system. According to the technology, a mode of preheating feeding by mixing waste alkali liquor and air for oxidation is adopted, on one hand, substances which are easy to thermally polymerize exist in ethylene waste alkali liquor, high polymers can be produced under the condition, and a heat exchanger can be blocked in a long-term operation process; and because the air contains oxygen, the oxygen can participate in generating peroxide self-polymers to further generate high polymers, so that the blockage of the heat exchanger is aggravated. In addition, the polymer-containing waste alkali liquid enters the subsequent wet oxidation reactor, and the long-term operation can cause the blockage and local overtemperature of the wet oxidation reactor, thereby affecting the treatment effect.
Disclosure of Invention
Aiming at the defects of the prior art, the invention provides a method and a device for treating ethylene waste lye. Aiming at the characteristics of ethylene waste alkali liquor, the invention can fully utilize the reaction heat, reduce the operation energy consumption, and simultaneously avoid the problems of heat exchange equipment blockage and scaling caused in long-term operation, local overtemperature of the wet oxidation reactor and the like.
The invention provides a method for treating ethylene waste alkali liquor, which comprises the following steps:
the treatment method mainly comprises an oil removal unit, a heat exchange unit, a wet oxidation unit and a gas-liquid separation unit, wherein the heat exchange unit mainly comprises a first heat exchanger and a second heat exchanger which use the same heat exchange medium; adding a proper amount of oil refining waste lye into ethylene waste lye, carrying out oil removal treatment, then conveying the treated ethylene waste lye to a first heat exchanger of a heat exchange unit, conveying the waste lye after heat removal to a wet oxidation unit, carrying out wet oxidation reaction by contacting the waste lye with oxygen-containing gas under the pressure condition that the waste lye keeps liquid phase, enabling the reacted waste lye to enter a second heat exchanger of the heat exchange unit, cooling and decompressing the waste lye after heat exchange, and then entering a gas-liquid separation unit.
In the method of the invention, whatThe ethylene waste alkali solution is waste alkali solution containing sulfide and COD generated in the process of refining ethylene pyrolysis gas alkali, and the COD concentration is 6000-100000mg/L, S 2- The concentration is 2000-50000mg/L, and the petroleum is 600-1600mg/L, wherein the petroleum contains substances which are easy to thermally polymerize, such as diolefins, and the diolefins are at least one of butadiene, isoprene, and the like.
In the method, the oil refining waste lye is at least one of dry gas mercaptan removal waste lye, liquefied gas mercaptan removal waste lye, catalytic gasoline waste lye and the like, wherein the COD concentration is 30000-70000mg/L and S 2- The concentration is 10000-25000mg/L, the concentration of phenol is 1000-1500mg/L, and the product contains mercaptan.
In the method, the oil removal treatment can be carried out by adopting a conventional oil removal method in the field, preferably adopting gravity oil removal, so as to ensure that no floating oil exists in the waste alkali liquid entering the wet oxidation system.
In the method, the mass ratio of the ethylene waste alkali liquor to the oil refining waste alkali liquor is 1-50:1, and the concentration of phenol in the mixed waste alkali liquor is controlled to be not lower than 100mg/L.
In the method of the invention, the heat exchange medium can be at least one of fresh water, circulating water, desalted water, deoxidized water and the like, and deoxidized water is preferred.
In the method of the invention, the temperature of the waste alkali liquid after heat exchange by the first heat exchanger is controlled to be 80-170 ℃, preferably 100-150 ℃.
In the method of the present invention, the wet oxidation reactor used in the wet oxidation unit may be various reactors conventionally used in the art, preferably a sleeve-type internal circulation reactor, in which the gas is directly introduced to achieve sufficient mixing. The reaction temperature of the wet oxidation is 150-230 ℃, preferably 170-210 ℃, the reaction pressure is 2.0-5.0MPa, preferably 3.0-4.5MPa, and the reaction time is 0.5-3.0h, preferably 1.0-2.0h.
In the method of the invention, the oxygen-containing gas introduced into the wet oxidation unit can be at least one of air, oxygen and the like, and the ventilation amount is 100% -300%, preferably 110% -200% of the air amount required by the complete oxidation of COD in the waste alkali solution.
In the method, if the COD concentration in the waste alkali solution is low, the heat release of the oxidation reaction is insufficient, and the superheated steam can be introduced into the wet oxidation reactor to supplement heat.
In the method, the waste alkali liquid treated by the wet oxidation unit enters a second heat exchanger, and the temperature of the waste alkali liquid after heat exchange is controlled to be 110-170 ℃.
In the method, the first heat exchanger and the second heat exchanger of the heat exchange unit use the same heat exchange medium, a heat exchange medium storage tank is arranged between the first heat exchanger and the second heat exchanger, and the heat exchange medium enters the heat exchange medium storage tank. In the second heat exchanger, heat exchange medium exchanges heat with the material at the outlet of the wet oxidation reactor, and enters the first heat exchanger after being heated, exchanges heat with mixed waste alkali liquor, and returns to the heat exchange medium storage tank after being cooled.
In the method of the invention, the first heat exchanger and the second heat exchanger can adopt any one of a tube type heat exchanger, a double-tube type heat exchanger, a shell-and-tube type heat exchanger, a U-shaped tube type heat exchanger and the like.
In the method, the waste alkali liquor is subjected to cooling and decompression treatment after heat exchange, is cooled to 30-50 ℃ and is decompressed to 0.35-0.5MPa.
In the method, the cooled and decompressed waste alkali liquor is conveyed to the gas-liquid separation unit, and the separated liquid phase enters the sewage treatment field, so that sulfide is effectively treated, and the sewage treatment cannot be influenced. The temperature of the separated gas phase is 30-50 ℃, and the gas phase is conveyed to an exhaust gas treatment unit.
The invention also provides a treatment device for the ethylene waste lye treatment method, which mainly comprises an oil removal unit, a heat exchange unit, a wet oxidation unit and a gas-liquid separation unit, wherein the oil removal unit mainly comprises an oil removal tank and is used for removing floating oil in the waste lye; the heat exchange unit mainly comprises a first heat exchanger, a heat exchange medium storage tank and a second heat exchanger and is used for exchanging heat among discharged materials, heat exchange medium and feed waste alkali liquid of the wet oxidation unit; the wet oxidation unit mainly comprises a wet oxidation reactor for removing sulfides and part of organic matters in the waste alkali liquid, the oxidized material enters a second heat exchanger for heat exchange, and the material after heat exchange is cooled and decompressed and then enters the gas-liquid separation unit.
In the invention, the gas phase after gas-liquid separation can be conveyed to an exhaust gas treatment unit, and the liquid phase enters a sewage treatment field for treatment.
Compared with the prior art, the invention has the following beneficial effects:
(1) In the case of wet oxidation treatment of ethylene lye, in order to realize heat utilization, researchers have proposed to provide a heat exchanger in front of the reactor, and to directly heat the inlet lye with hot materials discharged from the wet oxidation reactor. However, the inventor finds that the heat exchanger is blocked and scaled along with the long-term operation of the treatment device, and researches find that the heat exchanger is caused by some polymerization substances in the waste lye.
(2) Aiming at the problems of blockage and scaling of the heat exchanger and the water quality characteristics of the ethylene waste lye and the oil refining waste lye, the oil refining waste lye is used for inhibiting the heat polymerization of some diolefins in the ethylene waste lye by adding a proper amount of oil refining waste lye into the ethylene waste lye, so that the blockage and scaling of the heat exchanger are avoided; meanwhile, the effective treatment of part of oil refining waste alkali liquor can be realized, and the economical efficiency is better.
(3) The first heat exchanger and the second heat exchanger are arranged and the same heat exchange medium is used, so that the problem of blockage and scaling caused by directly taking materials discharged from wet oxidation as heat media is further avoided, and the long-period operation of the device is ensured.
(4) The sleeve type internal circulation reactor is adopted, the temperature in the reactor is uniform, and the gas-liquid mass transfer efficiency and the oxidation effect can be ensured.
Drawings
FIG. 1 is a schematic illustration of a process flow of the treatment method and apparatus of the present invention;
wherein: 101-1-ethylene waste lye, 101-2-oil refining waste lye, 102-compressed air, 103-steam, 104-tail gas and 105-treated waste lye; 201-a degreasing tank, 202-a feeding pump, 203-a heat exchange medium circulating pump, 204-a heat exchange medium storage tank, 205-a first heat exchanger, 206-a second heat exchanger, 207-a wet oxidation reactor, 208-a cooler and 209-a gas-liquid separator.
Detailed Description
The processing method, processing apparatus and effect of the present invention will be described in further detail by examples. The embodiments and specific operation procedures are given on the premise of the technical scheme of the invention, but the protection scope of the invention is not limited to the following embodiments.
The experimental methods in the following examples, unless otherwise specified, are all conventional in the art. The experimental materials used in the examples described below, unless otherwise specified, were purchased from conventional biochemical reagent stores.
The treatment device adopted in the embodiment of the invention mainly comprises an oil removal unit, a heat exchange unit, a wet oxidation unit and a gas-liquid separation unit, wherein the oil removal unit mainly comprises an oil removal tank 201, the heat exchange unit mainly comprises a first heat exchanger 205, a heat exchange medium storage tank 204 and a second heat exchanger 206, the wet oxidation unit mainly comprises a wet oxidation reactor 207, and the gas-liquid separation unit mainly comprises a cooler 208 and a gas-liquid separator 209. The first heat exchanger 205 and the second heat exchanger 206 use the same heat exchange medium, a heat exchange medium storage tank 204 is arranged between the first heat exchanger 205 and the second heat exchanger, the heat exchange medium enters the heat exchange medium storage tank, enters the second heat exchanger 204 through a heat exchange medium circulating pump 203, exchanges heat with the materials at the outlet of the wet oxidation reactor 207, enters the first heat exchanger 205 after the temperature of the heat exchange medium rises, exchanges heat with the deoiled waste lye, and returns to the heat exchange medium storage tank 204 after the temperature is reduced. The ethylene waste alkali liquor and the oil refining waste alkali liquor respectively enter a degreasing tank 201 for standing to remove floating oil in the waste alkali liquor, the degreased waste alkali liquor is conveyed to a first heat exchanger 205 through a feed pump 202, the waste alkali liquor after heat exchange enters a wet oxidation reactor 207 and is contacted with oxygen-containing gas under the condition that the solution is kept in a liquid phase, sulfide in the waste alkali liquor is converted into sulfate and thiosulfate, oxidized materials enter a second heat exchanger 206 for discharging heat exchange with the wet oxidation reactor, the materials after heat exchange enter a gas-liquid separator after passing through a cooler 208, gas phase is removed for waste gas treatment after separation, and the liquid phase enters a sewage treatment field.
In the invention, the detection method of COD is a method specified by HJ 828-2017 (determination of water quality chemical oxygen demand by dichromate method); s is S 2- The detection method of (2) is a method defined by HJ-T60-2000 (iodine determination method of water quality sulfide).
Example 1
The ethylene waste alkali liquid comes from waste alkali liquid discharged in the alkaline washing process of ethylene pyrolysis gas of a certain factory, wherein the COD concentration is 35000mg/L, S 2- The concentration is 15200mg/L, and the petroleum is 1320mg/L, including butadiene, isoprene and other substances.
The waste alkali liquid of oil refining is from the waste alkali liquid discharged in the process of removing mercaptan from a liquefied gas, wherein the COD concentration is 40000mg/L, S 2- The concentration is 12000mg/L, and the phenol concentration is 1200mg/L.
Adopting the treatment process and the device shown in the attached figure 1 to carry out treatment, mixing ethylene waste alkali liquid and oil refining waste alkali liquid according to the mass ratio of 10:1, then conveying to an oil removal tank to carry out oil removal treatment, and standing and settling for 72 hours to remove floating oil.
Deoxidized water is taken as a heat exchange medium to enter a heat exchange medium storage tank, is lifted to a second heat exchanger through a heat exchange medium circulating pump, is taken as a refrigerant to exchange heat with the discharged material of the reactor, is taken as a heating medium to enter a first heat exchanger after being heated, and adopts a tube type heat exchanger.
The mixed waste alkali liquor is deoiled, conveyed to a first heat exchanger through a feed pump, subjected to heat exchange to 110 ℃, and then enters a wet oxidation reactor to react with introduced compressed air, wherein the wet oxidation reactor adopts a sleeve type internal circulation reactor, the air quantity is 150% of the air quantity required by the complete oxidation of COD in the waste alkali liquor, the reaction temperature is 190 ℃, the reaction pressure is 3.0MPa, and the reaction time is 2.0 hours. In the wet oxidation reactor, sulfides in the waste alkali solution are oxidized into sulfate and thiosulfate, and organic matters are oxidized into low-molecular organic acids.
And (3) after the ethylene waste alkali liquid subjected to wet oxidation treatment enters a second heat exchanger to exchange heat to 160 ℃, the ethylene waste alkali liquid is cooled to 45 ℃ by a cooler, is depressurized to 0.4MPa, enters a gas-liquid separator for gas-liquid separation, and the separated gas phase is sent to an exhaust gas treatment unit, and the separated liquid phase is discharged into a sewage treatment field.
By adopting the treatment process, the heat exchanger is operated for 2000 hours, and the blockage phenomenon does not occur. S in the effluent 2- The concentration is less than 1.0mg/L, and the COD is less than 3500mg/L. If ethylene waste alkali liquid is treated independently, after the same time of operation, the heat exchanger is blocked, the waste alkali liquid can only be exchanged to 105 ℃, steam is supplemented into the reactor to maintain the reaction temperature, and COD is less than 4000mg/L.
Example 2
The ethylene waste alkali liquid comes from waste alkali liquid discharged in the alkaline washing process of ethylene pyrolysis gas of a certain factory, wherein the COD concentration is 35000mg/L, S 2- The concentration is 15200mg/L, and the petroleum is 1320mg/L, including butadiene, isoprene and other substances.
The waste alkali liquid of oil refining is from the waste alkali liquid discharged in the process of removing mercaptan from a liquefied gas, wherein the COD concentration is 40000mg/L, S 2- The concentration is 12000mg/L, and the phenol concentration is 1200mg/L.
Adopting the treatment process and the device shown in the attached figure 1 to carry out treatment, mixing ethylene waste alkali liquid and oil refining waste alkali liquid according to the mass ratio of 10:1, then conveying to an oil removal tank to carry out oil removal treatment, and standing and settling for 72 hours to remove floating oil.
Deoxidized water is taken as a heat exchange medium to enter a heat exchange medium storage tank, is lifted to a second heat exchanger through a heat exchange medium circulating pump, is taken as a refrigerant to exchange heat with the discharged material of the reactor, is taken as a heating medium to enter a first heat exchanger after being heated, and adopts a tube type heat exchanger.
The mixed waste alkali liquor is deoiled, then is conveyed to a first heat exchanger through a feed pump, enters a wet oxidation reactor after heat exchange to 103 ℃, reacts with the introduced compressed air, and the wet oxidation reactor adopts a sleeve type internal circulation reactor, wherein the air quantity is 110% of the air quantity required by the complete oxidation of COD in the waste alkali liquor, the reaction temperature is 150 ℃, the reaction pressure is 3.0MPa, and the reaction time is 2.0 hours. In the wet oxidation reactor, sulfides in the waste alkali solution are oxidized into sulfate and thiosulfate, and organic matters are oxidized into low-molecular organic acids.
After wet oxidation treatment, the ethylene waste alkali liquor enters a second heat exchanger to exchange heat to 140 ℃, is cooled to 35 ℃ by a cooler, is depressurized to 0.35MPa, enters a gas-liquid separator for gas-liquid separation, and the separated gas phase is sent to an exhaust gas treatment unit, and the separated liquid phase is discharged into a sewage treatment field.
By adopting the treatment process, the heat exchanger is operated for 2000 hours, and the blockage phenomenon does not occur. S in the effluent 2- The concentration is less than 20mg/L, and the COD is less than 6000mg/L. If no oil refining waste alkali liquid is added, the heat exchanger is blocked after the same operation time, the waste alkali liquid can only be exchanged to 92 ℃, and the reaction temperature needs to be maintained by supplementing steam into the reactor, so that the COD is less than 6500mg/L.
Example 3
The ethylene waste alkali liquid comes from waste alkali liquid discharged in the alkaline washing process of ethylene pyrolysis gas of a certain factory, wherein the COD concentration is 35000mg/L, S 2- The concentration is 15200mg/L, and the petroleum is 1320mg/L, including butadiene, isoprene and other substances.
The waste alkali liquid of oil refining is from the waste alkali liquid discharged in the process of removing mercaptan from a liquefied gas, wherein the COD concentration is 40000mg/L, S 2- The concentration is 12000mg/L, and the phenol concentration is 1200mg/L.
Adopting the treatment process and the device shown in the attached figure 1 to carry out treatment, mixing ethylene waste alkali liquid and oil refining waste alkali liquid according to the mass ratio of 10:1, then conveying to an oil removal tank to carry out oil removal treatment, and standing and settling for 72 hours to remove floating oil.
Deoxidized water is taken as a heat exchange medium to enter a heat exchange medium storage tank, is lifted to a second heat exchanger through a heat exchange medium circulating pump, is taken as a refrigerant to exchange heat with the discharged material of the reactor, is taken as a heating medium to enter a first heat exchanger after being heated, and adopts a tube type heat exchanger.
The mixed waste alkali liquor is deoiled, conveyed to a first heat exchanger through a feed pump, subjected to heat exchange to 140 ℃, and then enters a wet oxidation reactor to react with the introduced compressed air, wherein the wet oxidation reactor adopts a sleeve type internal circulation reactor, the air quantity is 200% of the air quantity required by the complete oxidation of COD in the waste alkali liquor, the reaction temperature is 220 ℃, the reaction pressure is 4.5MPa, and the reaction time is 2.0 hours. In the wet oxidation reactor, sulfides in the waste alkali solution are oxidized into sulfate and thiosulfate, and organic matters are oxidized into low-molecular organic acids.
And (3) after the ethylene waste alkali liquid subjected to wet oxidation treatment enters a second heat exchanger to exchange heat to 170 ℃, the ethylene waste alkali liquid is cooled to 50 ℃ by a cooler, is depressurized to 0.5MPa, enters a gas-liquid separator for gas-liquid separation, and the separated gas phase is sent to an exhaust gas treatment unit, and the separated liquid phase is discharged into a sewage treatment field.
By adopting the treatment process, the heat exchanger is operated for 2000 hours, and the blockage phenomenon does not occur. S in the effluent 2- The concentration is less than 1.0mg/L, and the COD is less than 2000mg/L. If no oil refining waste alkali liquid is added, the heat exchanger is blocked after the same operation time, the waste alkali liquid can only be exchanged to 126 ℃, and the reaction temperature needs to be maintained by supplementing steam into the reactor, so that the COD of the effluent is less than 2400mg/L.
Example 4
The difference from example 1 is that: the mass ratio of the ethylene waste alkali liquor to the oil refining waste alkali liquor is 5:1. the device runs for 2000 hours, and the heat exchanger is not blocked. S in the effluent 2- The concentration is less than 1.0mg/L, COD and 4500mg/L.
Example 5
The difference from example 1 is that: fresh water is used as a heat exchange medium. The apparatus was run for 2000 hours and the spent lye was heat exchanged to 150 ℃. S in the effluent 2- The concentration is less than 1.0mg/L, COD and 4000mg/L.
Example 6
The difference from example 1 is that: the first heat exchanger and the second heat exchanger adopt sleeve type heat exchangers. The device runs for 2000 hours, and the heat exchanger is not blocked. S in the effluent 2- The concentration is less than 1.0mg/L, COD and 3500mg/L.
Comparative example 1
The difference from example 1 is that: the heat exchanger adopts a direct heat exchange mode and does not adopt a heat exchange medium. Device operation2000 hours, there is blocking and scaling phenomenon, S in the effluent 2- The concentration is less than 1.0mg/L, COD and 4500mg/L.
Claims (17)
1. The treatment method of the ethylene waste alkali liquid is characterized by comprising the following steps: the treatment method mainly comprises an oil removal unit, a heat exchange unit, a wet oxidation unit and a gas-liquid separation unit, wherein the heat exchange unit mainly comprises a first heat exchanger and a second heat exchanger which use the same heat exchange medium; adding a proper amount of oil refining waste lye into ethylene waste lye, carrying out oil removal treatment, then conveying the treated ethylene waste lye to a first heat exchanger of a heat exchange unit, conveying the waste lye after heat removal to a wet oxidation unit, carrying out wet oxidation reaction by contacting the waste lye with oxygen-containing gas under the pressure condition that the waste lye keeps liquid phase, enabling the reacted waste lye to enter a second heat exchanger of the heat exchange unit, cooling and decompressing the waste lye after heat exchange, and then entering a gas-liquid separation unit.
2. The method according to claim 1, characterized in that: the ethylene waste alkali liquid is waste alkali liquid containing sulfide and COD generated in the process of refining ethylene pyrolysis gas alkali, and the COD concentration is 6000-100000mg/L, S 2- The concentration is 2000-50000mg/L, and the petroleum is 600-1600mg/L, and contains diolefin substances which are easy to thermally polymerize.
3. The method according to claim 2, characterized in that: the diolefin substance is at least one of butadiene and isoprene.
4. The method according to claim 1, characterized in that: the oil refining waste alkali liquid is at least one of dry gas mercaptan removal waste alkali liquid, liquefied gas mercaptan removal waste alkali liquid and catalytic gasoline waste alkali liquid, wherein the COD concentration is 30000-70000mg/L, S 2- The concentration is 10000-25000mg/L, the concentration of phenol is 1000-1500mg/L, and the product contains mercaptan.
5. The method according to claim 1, characterized in that: the oil removal treatment adopts gravity oil removal to ensure that no floating oil exists in the waste alkali liquid entering the wet oxidation unit.
6. The method according to claim 1, characterized in that: the mass ratio of the ethylene waste alkali liquor to the oil refining waste alkali liquor is 1-50:1, and the concentration of phenol in the mixed waste alkali liquor is controlled to be not lower than 100mg/L.
7. The method according to claim 1, characterized in that: the heat exchange medium is at least one of fresh water, circulating water, desalted water and deoxidized water, and deoxidized water is preferable.
8. The method according to claim 1, characterized in that: the temperature of the waste alkali liquid after heat exchange by the first heat exchanger is controlled to be 80-170 ℃, preferably 100-150 ℃.
9. The method according to claim 1, characterized in that: the wet oxidation reactor adopted by the wet oxidation unit is a sleeve type internal circulation reactor.
10. The method according to claim 1 or 9, characterized in that: the wet oxidation reaction temperature is 150-230 ℃, preferably 170-210 ℃, the reaction pressure is 2.0-5.0MPa, preferably 3.0-4.5MPa, and the reaction time is 0.5-3.0h, preferably 1.0-2.0h.
11. The method according to claim 1, characterized in that: the oxygen-containing gas introduced into the wet oxidation unit is at least one of air and oxygen, and the ventilation amount is 100% -300%, preferably 110% -200% of the amount of the COD in the waste alkali solution required for complete oxidation.
12. The method according to claim 1, characterized in that: if the COD concentration in the waste alkali solution is low, the heat release of the oxidation reaction is insufficient, and the heat is supplemented by introducing superheated steam into the wet oxidation reactor.
13. The method according to claim 1, characterized in that: the waste alkali liquid treated by the wet oxidation unit enters a second heat exchanger, and the temperature of the waste alkali liquid after heat exchange is controlled to be 110-170 ℃.
14. The method according to claim 1, characterized in that: the first heat exchanger and the second heat exchanger of the heat exchange unit use the same heat exchange medium, a heat exchange medium storage tank is arranged between the first heat exchanger and the second heat exchanger, and the heat exchange medium enters the heat exchange medium storage tank; in the second heat exchanger, heat exchange medium exchanges heat with the material at the outlet of the wet oxidation reactor, and enters the first heat exchanger after being heated, exchanges heat with waste alkali liquid, and returns to the heat exchange medium storage tank after being cooled.
15. The method according to claim 1, characterized in that: the first heat exchanger and the second heat exchanger adopt any one of a shell-and-tube heat exchanger, a sleeve heat exchanger, a shell-and-tube heat exchanger or a U-shaped tube heat exchanger.
16. The method according to claim 1, characterized in that: and cooling the waste alkali liquor after heat exchange to 30-50 ℃ and decompressing to 0.35-0.5MPa.
17. A treatment device for the ethylene waste lye treatment method according to any one of claims 1-16, characterized in that it mainly comprises a deoiling unit, a heat exchanging unit, a wet oxidation unit, a gas-liquid separation unit, wherein the deoiling unit mainly comprises a deoiling tank for removing floating oil in the waste lye; the heat exchange unit mainly comprises a first heat exchanger, a heat exchange medium storage tank and a second heat exchanger and is used for exchanging heat among discharged materials, heat exchange medium and feed waste alkali liquid of the wet oxidation unit; the wet oxidation unit mainly comprises a wet oxidation reactor for removing sulfides and part of organic matters in the waste alkali liquid, the oxidized material enters a second heat exchanger for heat exchange, and the material after heat exchange is cooled and decompressed and then enters the gas-liquid separation unit.
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