A method and device for treating ethylene waste alkali liquor

Abstract

The present invention relates to a treatment method and a treatment device for ethylene waste alkali liquid, which mainly include an oil removal unit, a heat exchange unit, a wet oxidation unit and a gas-liquid separation unit. The heat exchange unit mainly includes a first heat exchanger and a second heat exchanger, and the two use the same heat exchange medium; an appropriate amount of oil refining waste alkali liquid is added to the ethylene waste alkali liquid, and the waste alkali liquid is transported to the first heat exchanger of the heat exchange unit after oil removal treatment, and the waste alkali liquid after heat removal is transported to the wet oxidation unit, and is contacted with oxygen-containing gas under a pressure condition that keeps the waste alkali liquid in liquid phase for reaction, and the waste alkali liquid after reaction enters the second heat exchanger of the heat exchange unit, and the waste alkali liquid after heat exchange enters the gas-liquid separation unit after cooling and decompression. In view of the characteristics of ethylene waste alkali liquid, the present invention can fully utilize the reaction heat and reduce the operating energy consumption, and can avoid the problems of blockage and scaling of heat exchange equipment caused by long-term operation, as well as local overheating of the wet oxidation reactor.

Description

Technical Field

[0001] The invention belongs to the technical field of water pollution control, and specifically relates to a treatment method and a treatment device for ethylene waste alkali liquid. Background Art

[0002] In the process of ethylene production, alkali washing is currently widely used to remove acidic gases such as CO2 and H2S in cracked gas. The alkali washing process produces a large amount of waste alkali liquid, which contains not only residual NaOH but also inorganic salts such as Na2S and Na2CO3 generated during the alkali washing process. On the other hand, the condensation of heavy components in the cracked gas and the polymerization of dienes and aldehydes during the alkali washing process cause a large amount of organic matter to enter the waste alkali liquid. Since ethylene waste alkali liquid contains high concentrations of COD and sulfides and has poor biodegradability, most of the treatment plans for ethylene waste alkali liquid at home and abroad are to pre-treat it to remove sulfides and organic matter in it to prevent impact on the biochemical system of the sewage treatment plant.

[0003] CN201010518009.31 discloses a method for treating ethylene waste alkali liquor, firstly, the ethylene waste alkali liquor is subjected to wet oxidation treatment to remove most of the sulfides and part of the COD therein, then the waste alkali liquor is treated in an iron-copper micro-electrolysis reactor into which ozone is introduced to improve the biodegradability of the wastewater, then a precipitant is added to further remove the sulfides and harmful substances in the wastewater, and then the COD in the wastewater is further removed by biochemical treatment. The method has good treatment effects on sulfides and COD and stable effluent water quality. However, multiple reagents need to be added during the treatment process, the operating cost is high, and secondary pollution will be generated during the treatment process.

[0004] CN201310537921.7 discloses a method for treating ethylene waste alkali liquor, which adopts a combined process of flotation oil removal-high temperature wet oxidation-evaporation concentration-alkali concentration adjustment, which can efficiently remove COD and sulfide in ethylene waste alkali liquor, and can also recover sodium salt and reuse the treated sodium hydroxide solution to achieve zero discharge of ethylene waste alkali liquor. However, due to its high operating temperature, its operating energy consumption is high.

[0005] In order to reduce operating energy consumption and achieve effective use of heat, the researchers proposed installing a heat exchanger in front of the wet oxidation reactor to preheat the imported waste alkali solution using the wet oxidation material to reduce the steam consumption of the reaction device.

[0006] US20050171390A1 discloses a wet oxidation treatment process and system, which is to wet oxidize wastewater containing one or more compounds with carbon-heteroatom bonds under high temperature and high pressure to destroy the carbon-heteroatom bonds of at least one of the compounds, and the treated wastewater enters the subsequent advanced oxidation system. This technology uses the method of preheating the feed by mixing waste alkali liquid with oxidation air. On the one hand, there are substances that are prone to thermal polymerization in the ethylene waste alkali liquid, which will produce high polymers under this condition, causing blockage of the heat exchanger during long-term operation; and because the air contains oxygen, oxygen will participate in the generation of peroxide self-polymerization, leading to further generation of high polymers, aggravating the blockage of the heat exchanger. In addition, the polymer-containing waste alkali liquid enters the subsequent wet oxidation reactor, and long-term operation will also cause blockage and local overheating of the wet oxidation reactor, affecting the treatment effect. Summary of the invention

[0007] In view of the shortcomings of the prior art, the present invention provides a method and device for treating ethylene waste alkali liquor. The present invention, in view of the characteristics of ethylene waste alkali liquor, can fully utilize the reaction heat and reduce the operating energy consumption, while avoiding the problems of heat exchange equipment blockage and scaling caused by long-term operation, as well as local overheating of the wet oxidation reactor.

[0008] The present invention provides a method for treating ethylene waste alkali liquor, comprising the following contents:

[0009] The treatment method mainly includes an oil removal unit, a heat exchange unit, a wet oxidation unit and a gas-liquid separation unit. The heat exchange unit mainly includes a first heat exchanger and a second heat exchanger, and the two use the same heat exchange medium. An appropriate amount of waste alkali liquid from oil refining is added to the waste alkali liquid of ethylene, and the waste alkali liquid is transported to the first heat exchanger of the heat exchange unit after oil removal treatment. The waste alkali liquid after heat removal is transported to the wet oxidation unit, and is contacted with oxygen-containing gas under a pressure condition that keeps the waste alkali liquid in liquid phase to carry out a wet oxidation reaction. After the reaction, the waste alkali liquid enters the second heat exchanger of the heat exchange unit. After the heat exchange, the waste alkali liquid is cooled and decompressed and then enters the gas-liquid separation unit.

[0010] In the method of the present invention, the ethylene waste alkali liquid is a waste alkali liquid containing sulfide and COD produced in the ethylene cracking gas alkali refining process, and the COD concentration is 6000-100000 mg / L, S 2- The concentration is 2000-50000 mg / L, and the petroleum is 600-1600 mg / L, which contains substances that are prone to thermal polymerization, such as diene substances, etc. The diene substances are at least one of butadiene, isoprene, etc.

[0011] In the method of the present invention, the oil refining waste alkali liquid is at least one of dry gas sweetening waste alkali liquid, liquefied gas sweetening waste alkali liquid, catalytic gasoline waste alkali liquid, etc., wherein the COD concentration is 30000-70000 mg / L, S2- The concentration is 10000-25000 mg / L, the phenol concentration is 1000-1500 mg / L, and it also contains thiols.

[0012] In the method of the present invention, the oil removal treatment can adopt conventional oil removal methods in the art, preferably gravity oil removal to ensure that there is no floating oil in the waste alkali liquid entering the wet oxidation system.

[0013] In the method of the present invention, the mass ratio of the ethylene waste alkali liquid to the oil refining waste alkali liquid is 1-50:1, and the phenol concentration in the mixed waste alkali liquid is controlled to be not less than 100 mg / L.

[0014] In the method of the present invention, the heat exchange medium can be at least one of fresh water, circulating water, desalted water, deoxygenated water, etc., preferably deoxygenated water.

[0015] In the method of the present invention, the temperature of the waste alkali solution after heat exchange in the first heat exchanger is controlled to be 80-170°C, preferably 100-150°C.

[0016] In the method of the present invention, the wet oxidation reactor used in the wet oxidation unit can be any of the conventional reactors in the art, preferably a sleeve-type internal circulation reactor, and direct introduction of gas into the wet oxidation reactor can achieve full mixing. The reaction temperature of the wet oxidation is 150-230°C, preferably 170-210°C, 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.

[0017] In the method of the present invention, the oxygen-containing gas introduced into the wet oxidation unit can be at least one of air, oxygen, etc., and the ventilation volume is 100%-300% of the gas volume required for complete oxidation of COD in the waste alkali liquid, preferably 110%-200%.

[0018] In the method of the present invention, if the COD concentration in the waste alkali liquid is low, resulting in insufficient heat release in the oxidation reaction, superheated steam can be introduced into the wet oxidation reactor to supplement heat.

[0019] In the method of the present invention, the waste alkali liquid after the wet oxidation unit treatment enters the second heat exchanger, and the temperature of the waste alkali liquid after the heat exchange is controlled to be 110-170°C.

[0020] In the method of the present invention, the first heat exchanger and the second heat exchanger of the heat exchange unit use the same heat exchange medium, and a heat exchange medium storage tank is provided between the two, and the heat exchange medium enters the heat exchange medium storage tank. In the second heat exchanger, the heat exchange medium exchanges heat with the material at the outlet of the wet oxidation reactor, enters the first heat exchanger after the temperature is increased, exchanges heat with the mixed waste alkali solution, and returns to the heat exchange medium storage tank after the temperature is reduced.

[0021] In the method of the present invention, the first and second heat exchangers may be any one of a shell-and-tube heat exchanger, a sleeve-and-tube heat exchanger, a shell-and-tube heat exchanger or a U-tube heat exchanger.

[0022] In the method of the present invention, the waste alkali liquid is cooled and decompressed after heat exchange, cooled to 30-50° C., and decompressed to 0.35-0.5 MPa.

[0023] In the method of the present invention, the waste alkali liquid is transported to the gas-liquid separation unit after cooling and decompression, and the liquid phase enters the sewage treatment plant after separation. Since the sulfide is effectively treated, it will not affect the sewage treatment. The temperature of the gas phase after separation is 30-50°C and is transported to the waste gas treatment unit.

[0024] On the other hand, the present invention also provides a treatment device for the above-mentioned ethylene waste alkali liquid treatment method, which mainly includes an oil removal unit, a heat exchange unit, a wet oxidation unit, and a gas-liquid separation unit, wherein the oil removal unit mainly includes an oil removal tank for removing floating oil in the waste alkali liquid; the heat exchange unit mainly includes a first heat exchanger, a heat exchange medium storage tank and a second heat exchanger, which are used for heat exchange between the wet oxidation unit discharge material, the heat exchange medium and the feed waste alkali liquid; the wet oxidation unit mainly includes a wet oxidation reactor, which is used to remove sulfide and part of organic matter in the waste alkali liquid, and the oxidized material enters the second heat exchanger for heat exchange, and the material after heat exchange is cooled and decompressed and then enters the gas-liquid separation unit.

[0025] In the present invention, after gas-liquid separation, the gas phase can be transported to a waste gas treatment unit, and the liquid phase is sent to a sewage treatment plant for treatment.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] (1) When wet oxidation is used to treat ethylene waste alkali liquid, in order to achieve heat utilization, researchers proposed to install a heat exchanger in front of the reactor and use the hot materials discharged from the wet oxidation reactor to directly heat the imported waste alkali liquid. However, the inventors of this application found in experiments that with the long-term operation of the treatment device, the heat exchanger will be blocked and scaled. After research, it was found that some polymeric substances in the waste alkali liquid were the cause. Based on this discovery, the inventors added an appropriate amount of oil refinery waste alkali liquid to the ethylene waste alkali liquid, and used the oil refinery waste alkali liquid to inhibit the polymerization of this part of organic matter in the ethylene waste alkali liquid. At the same time, the indirect heat exchange method was used to exchange heat for the wet oxidation import and export materials. On the basis of achieving full utilization of heat, the risk of heat exchanger blockage and scaling was reduced, and the subsequent wet oxidation reactor blockage and local overheating problems were solved, ensuring the long-term stable operation of the device and reducing the energy consumption of the device.

[0028] (2) In view of the blockage and scaling problems of the heat exchanger and the water quality characteristics of ethylene waste alkali liquid and oil refinery waste alkali liquid, an appropriate amount of oil refinery waste alkali liquid is added to the ethylene waste alkali liquid. The oil refinery waste alkali liquid is used to inhibit the thermal polymerization of some dienes in the ethylene waste alkali liquid, thereby avoiding blockage and scaling of the heat exchanger. At the same time, effective treatment of part of the oil refinery waste alkali liquid can be achieved, which is more economical.

[0029] (3) The first heat exchanger and the second heat exchanger are provided and use the same heat exchange medium to further avoid blockage and scaling problems caused by the materials discharged from wet oxidation being directly used as heat medium, thereby ensuring long-term operation of the device.

[0030] (4) The use of a sleeve-type internal circulation reactor ensures uniform temperature inside the reactor, which can ensure gas-liquid mass transfer efficiency and oxidation effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 It is a process flow diagram of the treatment method and device of the present invention;

[0032] Among them: 101-1-ethylene waste alkali liquor, 101-2-oil refining waste alkali liquor, 102-compressed air, 103-steam, 104-tail gas, 105-treated waste alkali liquor; 201-oil removal tank, 202-feed pump, 203-heat exchange medium circulation pump, 204-heat exchange medium storage tank, 205-first heat exchanger, 206-second heat exchanger, 207-wet oxidation reactor, 208-cooler, 209-gas-liquid separator. DETAILED DESCRIPTION

[0033] The following examples further illustrate the treatment method, treatment device and effects of the present invention. The examples are implemented based on the technical solution of the present invention, and provide detailed implementation methods and specific operation processes, but the protection scope of the present invention is not limited to the following examples.

[0034] The experimental methods in the following examples, unless otherwise specified, are all conventional methods in the art. The experimental materials used in the following examples, unless otherwise specified, were purchased from conventional biochemical reagent stores.

[0035] The processing device used in the embodiment of the present invention is as shown in the attached Figure 1As shown, it mainly includes an oil removal unit, a heat exchange unit, a wet oxidation unit, and a gas-liquid separation unit, wherein the oil removal unit mainly includes an oil removal tank 201, the heat exchange unit mainly includes a first heat exchanger 205, a heat exchange medium storage tank 204, and a second heat exchanger 206, the wet oxidation unit mainly includes a wet oxidation reactor 207, and the gas-liquid separation unit mainly includes 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, and a heat exchange medium storage tank 204 is set between the two. The heat exchange medium enters the heat exchange medium storage tank, enters the second heat exchanger 204 through the heat exchange medium circulation pump 203, and exchanges heat with the outlet material of the wet oxidation reactor 207. After the heat exchange medium is heated, it enters the first heat exchanger 205, exchanges heat with the waste alkali liquid after oil removal, and returns to the heat exchange medium storage tank 204 after cooling. The ethylene waste alkali liquid and the oil refining waste alkali liquid respectively enter the oil removal tank 201 to stand and remove the floating oil in the waste alkali liquid. After oil removal, it is transported to the first heat exchanger 205 through the feed pump 202. After heat exchange, the waste alkali liquid enters the wet oxidation reactor 207, contacts with the oxygen-containing gas under the condition of keeping the solution in liquid phase, and converts the sulfide in the waste alkali liquid into sulfate and thiosulfate. The oxidized material enters the second heat exchanger 206 for heat exchange with the discharge of the wet oxidation reactor. After heat exchange, the material passes through the cooler 208 and enters the gas-liquid separator. After separation, the gas phase is treated with waste gas, and the liquid phase enters the sewage treatment plant.

[0036] In the present invention, the detection method of COD is the method specified in HJ 828-2017 (Determination of Chemical Oxygen Demand of Water Quality - Dichromate Method); S 2- The detection method is the method specified in HJ-T 60-2000 (Determination of sulfide in water quality - iodine titration method).

[0037] Example 1

[0038] The ethylene waste alkali liquid comes from the waste alkali liquid discharged during the alkali washing process of ethylene cracking gas in a certain factory, with a COD concentration of 35000mg / L and S 2- The concentration is 15200 mg / L, and that of petroleum is 1320 mg / L, including butadiene, isoprene and other substances.

[0039] The waste alkali liquid from oil refining comes from the waste alkali liquid discharged from the desulfurization process of a certain liquefied gas, with a COD concentration of 40000mg / L and S 2- The concentration is 12000mg / L and the phenol concentration is 1200mg / L.

[0040] Use attached Figure 1 The treatment process and device shown are used to treat the ethylene waste alkali liquid and the refinery waste alkali liquid in a mass ratio of 10:1, and then transported to the deoiling tank for deoiling treatment, and allowed to settle for 72 hours to remove the floating oil.

[0041] Deoxygenated water is used as the heat exchange medium to enter the heat exchange medium storage tank, and is lifted to the second heat exchanger by the heat exchange medium circulation pump. The deoxygenated water is used as a refrigerant to exchange heat with the reactor discharge. After the deoxygenated water is heated, it enters the first heat exchanger as a heat medium. The first and second heat exchangers use shell-and-tube heat exchangers.

[0042] After degreasing, the mixed waste alkali liquor is transported to the first heat exchanger through the feed pump, and then enters the wet oxidation reactor after heat exchange to 110°C to react with the compressed air introduced. The wet oxidation reactor adopts a sleeve-type internal circulation reactor, and the air volume is 150% of the gas volume required for complete oxidation of COD in the waste alkali liquor. The reaction temperature is 190°C, the reaction pressure is 3.0MPa, and the reaction time is 2.0 hours. In the wet oxidation reactor, the sulfide in the waste alkali liquor is oxidized into sulfate and thiosulfate, and the organic matter is oxidized into low molecular organic acid.

[0043] The ethylene waste alkali liquid after wet oxidation treatment enters the second heat exchanger for heat exchange to 160°C, then is cooled to 45°C in the cooler, and after being reduced in pressure to 0.4MPa, it enters the gas-liquid separator for gas-liquid separation. The separated gas phase is sent to the waste gas treatment unit, and the separated liquid phase is discharged into the sewage treatment plant.

[0044] Using the treatment process of the present invention, after 2000 hours of operation, the heat exchanger did not experience blockage. 2- The concentration is less than 1.0mg / L, and the COD is less than 3500mg / L. If the ethylene waste alkali solution is treated alone, the heat exchanger will be blocked after the same operation time, and the waste alkali solution can only be heated to 105℃. Steam needs to be added to the reactor to maintain the reaction temperature, and the COD is less than 4000mg / L.

[0045] Example 2

[0046] The ethylene waste alkali liquid comes from the waste alkali liquid discharged during the alkali washing process of ethylene cracking gas in a certain factory, with a COD concentration of 35000mg / L and S 2- The concentration is 15200 mg / L, and that of petroleum is 1320 mg / L, including butadiene, isoprene and other substances.

[0047] The waste alkali liquid from oil refining comes from the waste alkali liquid discharged from the desulfurization process of a certain liquefied gas, with a COD concentration of 40000mg / L and S 2- The concentration is 12000mg / L and the phenol concentration is 1200mg / L.

[0048] Use attached Figure 1 The treatment process and device shown are used to treat the ethylene waste alkali liquid and the refinery waste alkali liquid in a mass ratio of 10:1, and then transported to the deoiling tank for deoiling treatment, and allowed to settle for 72 hours to remove the floating oil.

[0049] Deoxygenated water is used as the heat exchange medium to enter the heat exchange medium storage tank, and is lifted to the second heat exchanger by the heat exchange medium circulation pump. The deoxygenated water is used as a refrigerant to exchange heat with the reactor discharge. After the deoxygenated water is heated, it enters the first heat exchanger as a heat medium. The first and second heat exchangers use shell-and-tube heat exchangers.

[0050] After degreasing, the mixed waste alkali liquor is transported to the first heat exchanger through the feed pump, and then enters the wet oxidation reactor after heat exchange to 103°C to react with the compressed air introduced. The wet oxidation reactor adopts a sleeve-type internal circulation reactor. The air volume is 110% of the gas volume required for complete oxidation of COD in the waste alkali liquor. The reaction temperature is 150°C, the reaction pressure is 3.0MPa, and the reaction time is 2.0 hours. In the wet oxidation reactor, the sulfide in the waste alkali liquor is oxidized into sulfate and thiosulfate, and the organic matter is oxidized into low molecular organic acid.

[0051] After wet oxidation treatment, the ethylene waste alkali liquid enters the second heat exchanger for heat exchange to 140°C, then is cooled to 35°C in the cooler, and after being reduced in pressure to 0.35MPa, it enters the gas-liquid separator for gas-liquid separation. After separation, the gas phase is sent to the waste gas treatment unit, and the separated liquid phase is discharged into the sewage treatment plant.

[0052] Using the treatment process of the present invention, after 2000 hours of operation, the heat exchanger did not experience blockage. 2- The concentration is less than 20mg / L and the COD is less than 6000mg / L. If the waste alkali liquid from oil refinery is not added, the heat exchanger will be blocked after the same operation time, and the waste alkali liquid can only be heated to 92℃. Steam needs to be added to the reactor to maintain the reaction temperature so that the COD is less than 6500mg / L.

[0053] Example 3

[0054] The ethylene waste alkali liquid comes from the waste alkali liquid discharged during the alkali washing process of ethylene cracking gas in a certain factory, with a COD concentration of 35000mg / L and S 2- The concentration is 15200 mg / L, and that of petroleum is 1320 mg / L, including butadiene, isoprene and other substances.

[0055] The waste alkali liquid from oil refining comes from the waste alkali liquid discharged from the desulfurization process of a certain liquefied gas, with a COD concentration of 40000mg / L and S 2- The concentration is 12000mg / L and the phenol concentration is 1200mg / L.

[0056] Use attached Figure 1 The treatment process and device shown are used to treat the ethylene waste alkali liquid and the refinery waste alkali liquid in a mass ratio of 10:1, and then transported to the deoiling tank for deoiling treatment, and allowed to settle for 72 hours to remove the floating oil.

[0057] Deoxygenated water is used as the heat exchange medium to enter the heat exchange medium storage tank, and is lifted to the second heat exchanger by the heat exchange medium circulation pump. The deoxygenated water is used as a refrigerant to exchange heat with the reactor discharge. After the deoxygenated water is heated, it enters the first heat exchanger as a heat medium. The first and second heat exchangers use shell-and-tube heat exchangers.

[0058] After degreasing, the mixed waste alkali liquor is transported to the first heat exchanger through the feed pump, and then enters the wet oxidation reactor after heat exchange to 140°C to react with the introduced compressed air. The wet oxidation reactor adopts a sleeve-type internal circulation reactor. The air volume is 200% of the gas volume required for complete oxidation of COD in the waste alkali liquor. The reaction temperature is 220°C, the reaction pressure is 4.5MPa, and the reaction time is 2.0 hours. In the wet oxidation reactor, the sulfide in the waste alkali liquor is oxidized into sulfate and thiosulfate, and the organic matter is oxidized into low molecular organic acid.

[0059] The ethylene waste alkali liquid after wet oxidation treatment enters the second heat exchanger for heat exchange to 170°C, then is cooled to 50°C in the cooler, and after being reduced in pressure to 0.5MPa, it enters the gas-liquid separator for gas-liquid separation. The separated gas phase is sent to the waste gas treatment unit, and the separated liquid phase is discharged into the sewage treatment plant.

[0060] Using the treatment process of the present invention, after 2000 hours of operation, the heat exchanger did not experience blockage. 2- The concentration is less than 1.0mg / L and the COD is less than 2000mg / L. If the waste alkali liquid from oil refinery is not added, the heat exchanger will be blocked after the same operation time, and the waste alkali liquid can only be heated to 126℃. Steam needs to be added to the reactor to maintain the reaction temperature so that the effluent COD is less than 2400mg / L.

[0061] Example 4

[0062] Same as Example 1, except that the mass ratio of ethylene waste alkali liquid to oil refining waste alkali liquid is 5:1. The device was operated for 2000 hours, and the heat exchanger did not block. 2- The concentration is less than 1.0mg / L and COD is less than 4500mg / L.

[0063] Example 5

[0064] Same as Example 1, except that fresh water is used as the heat exchange medium. The device runs for 2000 hours and heats the waste alkali solution to 150°C. 2- The concentration is less than 1.0mg / L and COD is less than 4000mg / L.

[0065] Example 6

[0066] Same as Example 1, except that the first and second heat exchangers are double-tube heat exchangers. The device was operated for 2000 hours, and no blockage occurred in the heat exchanger.2- The concentration is less than 1.0mg / L and COD is less than 3500mg / L.

[0067] Comparative Example 1

[0068] Same as Example 1, except that the heat exchanger uses direct heat exchange instead of heat exchange medium. The device ran for 2000 hours and there were blockage and scaling phenomena. 2- The concentration is less than 1.0mg / L and COD is less than 4500mg / L.

Claims

1. A method for treating ethylene waste alkali liquor, characterized in that The invention comprises the following contents: the treatment method mainly comprises an oil removal unit, a heat exchange unit, a wet oxidation unit and a gas-liquid separation unit, the heat exchange unit mainly comprises a first heat exchanger and a second heat exchanger, and the two use the same heat exchange medium; an appropriate amount of oil refining waste alkali liquid is added to the ethylene waste alkali liquid, and the waste alkali liquid is transported to the first heat exchanger of the heat exchange unit after oil removal treatment, and the waste alkali liquid after heat removal is transported to the wet oxidation unit, and is contacted with oxygen-containing gas under pressure conditions that keep the waste alkali liquid in liquid phase for wet oxidation reaction, and the waste alkali liquid after the reaction enters the second heat exchanger of the heat exchange unit, and the waste alkali liquid after heat exchange is cooled and decompressed and enters the gas-liquid separation unit; the ethylene waste alkali liquid is a waste alkali liquid containing sulfide and COD produced in the ethylene cracking gas alkali refining process, and the COD concentration is 6000-100000mg / L, S 2- The concentration is 2000-50000mg / L, the petroleum is 600-1600mg / L, and it contains diolefins that are prone to thermal polymerization; the oil refining waste alkali liquid is at least one of dry gas sweetening alcohol waste alkali liquid, liquefied gas sweetening alcohol waste alkali liquid, and catalytic gasoline waste alkali liquid, wherein the COD concentration is 30000-70000mg / L, S 2- The concentration is 10000-25000 mg / L, the phenol concentration is 1000-1500 mg / L, and mercaptan is contained; the mass ratio of the ethylene waste alkali liquid to the oil refining waste alkali liquid is 1-50:

1.

2. The method according to claim 1, characterized in that: The diene substance is at least one of butadiene and isoprene.

3. The method according to claim 1, characterized in that: The oil removal treatment adopts gravity oil removal to ensure that there is no floating oil in the waste alkali liquid entering the wet oxidation unit.

4. The method according to claim 1, characterized in that: The phenol concentration in the mixed waste alkali liquid is controlled to be no less than 100 mg / L.

5. 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 deoxygenated water.

6. The method according to claim 5, characterized in that: The heat exchange medium is deoxygenated water.

7. The method according to claim 1, characterized in that: The temperature of the waste alkali solution after heat exchange in the first heat exchanger is controlled to be 80-170°C.

8. The method according to claim 7, characterized in that: The temperature of the waste alkali solution after heat exchange in the first heat exchanger is controlled to be 100-150°C.

9. The method according to claim 1, characterized in that: The wet oxidation reactor used in the wet oxidation unit is a sleeve-type internal circulation reactor.

10. The method according to claim 1 or 9, characterized in that: The reaction temperature of the wet oxidation is 150-230° C., the reaction pressure is 2.0-5.0 MPa, and the reaction time is 0.5-3.0 h.

11. The method according to claim 10, characterized in that: The reaction temperature of the wet oxidation is 170-210° C., the reaction pressure is 3.0-4.5 MPa, and the reaction time is 1.0-2.0 h.

12. 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 volume is 100%-300% of the gas volume required for complete oxidation of COD in the waste alkali liquid.

13. The method according to claim 12, characterized in that: The ventilation volume is 110%-200% of the volume required for complete oxidation of COD in the waste alkali liquid.

14. The method according to claim 1, characterized in that: If the COD concentration in the waste alkali liquid is low, resulting in insufficient heat release in the oxidation reaction, superheated steam is introduced into the wet oxidation reactor to supplement heat.

15. The method according to claim 1, characterized in that: The waste alkali liquid after treatment in the wet oxidation unit enters the second heat exchanger, and the temperature of the waste alkali liquid after heat exchange is controlled to be 110-170°C.

16. 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, and a heat exchange medium storage tank is arranged between the two, and the heat exchange medium enters the heat exchange medium storage tank; in the second heat exchanger, the heat exchange medium exchanges heat with the material at the outlet of the wet oxidation reactor, enters the first heat exchanger after heating, exchanges heat with the waste alkali liquid, and returns to the heat exchange medium storage tank after cooling.

17. The method according to claim 1, characterized in that: The first and second heat exchangers are any one of a shell-and-tube heat exchanger, a sleeve-and-tube heat exchanger, a shell-and-tube heat exchanger or a U-tube heat exchanger.

18. The method according to claim 1, characterized in that: After the heat exchange, the waste alkali liquid is cooled and decompressed to 30-50°C and decompressed to 0.35-0.5MPa.

19. A treatment device for the method for treating ethylene waste alkali liquor according to any one of claims 1 to 18, characterized in that It mainly includes an oil removal unit, a heat exchange unit, a wet oxidation unit, and a gas-liquid separation unit, wherein the oil removal unit mainly includes an oil removal tank for removing floating oil in the waste alkali liquid; the heat exchange unit mainly includes a first heat exchanger, a heat exchange medium storage tank and a second heat exchanger, which are used for heat exchange between the wet oxidation unit discharge material, the heat exchange medium and the feed waste alkali liquid; the wet oxidation unit mainly includes a wet oxidation reactor, which is used to remove sulfide and part of organic matter in the waste alkali liquid, and the oxidized material enters the second heat exchanger for heat exchange, and after the heat exchange, the material is cooled and decompressed and then enters the gas-liquid separation unit.

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