Deep treatment system for waste lye in propylene production

Abstract

The utility model relates to an advanced treatment system for waste lye in propylene production, which comprises a pretreatment unit and an evaporative crystallization unit, the pretreatment unit comprises an air flotation device, an acidification decarburization device and an advanced oxidation device, and the air flotation device, the acidification decarburization device, the advanced oxidation device and the evaporative crystallization unit are sequentially communicated through pipelines. The device has the beneficial effects that the structure is compact, the design is reasonable, the device capable of reducing, recycling and harmlessly treating the waste alkali liquid is provided, solid-liquid separation is realized through a complete set of process system, and finally evaporation condensate water for production and recycling and crystal salt with relatively high quality are obtained.

Description

Technical Field

[0001] The utility model relates to the technical field of chemical waste liquid treatment, in particular to a deep treatment system for waste alkali liquid in propylene production. Background Technique

[0002] Propylene is an important chemical raw material. In recent years, with the rapid growth of the demand for derivatives such as polypropylene, the demand for propylene has also increased year by year. Compared with the traditional process for producing propylene, the propane catalytic dehydrogenation (PDH) process for producing propylene has the advantages of high propylene yield and less equipment investment. Among the currently industrialized PDH processes for producing propylene, the Oleflex process is the most widely used. A by-product waste of the Oleflex process unit is waste alkali liquid, which is generated after the sulfur-containing waste gas (H2S) from the reaction section is washed and absorbed by a certain concentration of sodium hydroxide alkali liquid in the alkali washing tower. The COD content of this kind of waste alkali liquid is 80,000 - 120,000 mg / L, containing sodium sulfide (Na2S) 4.7 - 7.0 wt%, sodium hydrosulfide (NaHS) 3.3 - 5.0 wt%, and pH > 13. The COD and sulfide concentrations of this kind of alkali washing wastewater are high, with strong corrosiveness and are not easy to treat. The currently relatively mature preliminary treatment method is wet oxidation + acidification and neutralization.

[0003] After being treated by the wet oxidation process, the COD can be reduced to 1500 mg / L, the sulfide can be reduced to 1 mg / L, and the oil can be reduced to 100 mg / L. Although from the perspective of the process effect alone, the removal rates of various pollutant indicators all reach more than 90%, it still cannot meet the discharge or reuse standards. Traditional methods for treating high-salt wastewater all have certain technical defects and poor actual operation effects, and these problems also lead to a large amount of waste liquid in production enterprises being retained due to inability to be treated in time. Therefore, it is urgent to develop a reliable deep treatment technology for waste alkali liquid to ensure the stable operation of production. Content of the Utility Model

[0004] The utility model provides a deep treatment system for waste alkali liquid in propylene production, aiming to solve the problems in the prior art.

[0005] The technical solution of the utility model to solve the above technical problems is as follows:

[0006] A deep treatment system for waste alkali liquid in propylene production includes a pretreatment unit and an evaporation and crystallization unit. The pretreatment unit includes a flotation device, an acidification and decarbonization device, and an advanced oxidation device. The flotation device, the acidification and decarbonization device, the advanced oxidation device, and the evaporation and crystallization unit are sequentially connected through pipelines.

[0007] The beneficial effects of the present utility model are as follows: During the treatment process, first, the waste alkali liquor to be treated is transported to the air flotation device, and the residual oil in the waste alkali liquor is removed by adding a coagulant through the air flotation device; second, the treated waste alkali liquor enters the acidification and decarbonization device for decarbonization treatment, and the CO2 is discharged from the system and transported to the odor treatment system to ensure the normal operation of the subsequent process units; then, the wastewater treated by the acidification and decarbonization device enters the advanced oxidation device. The advanced oxidation adopts the Fenton oxidation process, and by sequentially adding reagents such as ferrous sulfate, hydrogen peroxide, and flocculant, COD, suspended solids, sulfides, colority, etc. are removed to ensure the stable operation of the evaporation and crystallization unit and reduce the amount of overly concentrated evaporation mother liquor; finally, the waste alkali liquor is transported to the evaporation and crystallization unit for evaporation and crystallization.

[0008] The structure of the present utility model is compact and the design is reasonable. Its purpose is to provide a device capable of treating waste alkali liquor for reduction, resource utilization, and harmless treatment, realizing solid-liquid separation through a complete set of process systems, and finally obtaining evaporation condensate water that can be used for production reuse and relatively high-quality crystal salts.

[0009] Based on the above technical solutions, the present utility model can be further improved as follows.

[0010] Further, the evaporation and crystallization unit includes a multi-effect evaporation heat crystallization device. The multi-effect evaporation heat crystallization device is connected to the advanced oxidation device through a pipeline, and a feed pump four is fixedly installed on the pipeline connecting the multi-effect evaporation heat crystallization device and the advanced oxidation device.

[0011] The beneficial effect of adopting the above further solution is that the structure is simple and the design is reasonable. The waste alkali liquor treated by the high oxidation device is transported to the multi-effect evaporation heat crystallization device for evaporation and crystallization by using the feed pump four.

[0012] Further, the evaporation and crystallization unit further includes an evaporator water inlet tank. The top of the evaporator water inlet tank is connected to the advanced oxidation device through a pipeline, and the bottom of the evaporator water inlet tank is connected to the inlet of the feed pump four through a pipeline.

[0013] The beneficial effect of adopting the above further solution is that the structure is simple and the design is reasonable. The evaporator water inlet tank is used to store the waste alkali liquor to be evaporated and crystallized, which is convenient for treatment.

[0014] Further, a filter is fixedly installed on the pipeline connecting the evaporator water inlet tank and the advanced oxidation device.

[0015] The beneficial effect of adopting the above further solution is that the structure is simple and the design is reasonable. The filter is used to remove impurities such as suspended solids and colloids in the water and then enter the evaporation and crystallization unit to ensure the normal operation of the process.

[0016] Further, a feed pump three is fixedly installed on the pipeline connecting the evaporator water inlet tank and the advanced oxidation device.

[0017] The beneficial effect of adopting the above further scheme is that the structure is simple and the design is reasonable. The waste alkali liquid treated by the high oxidation treatment device is sent into the evaporator water inlet tank by the feed pump three.

[0018] Further, the pretreatment unit further includes an adjustment device which is connected to the flotation device through a pipeline, and a feed pump one is fixedly installed on the pipeline connecting the adjustment device and the flotation device.

[0019] The beneficial effect of adopting the above further scheme is that the structure is simple and the design is reasonable. The waste alkali liquid to be treated is sent into the adjustment device for static settlement to adjust the water quality and water volume.

[0020] Further, the adjustment device includes at least one adjustment tank which is connected to the flotation device through a pipeline, and the feed pump one is located on the pipeline connecting the adjustment tank and the flotation device.

[0021] The beneficial effect of adopting the above further scheme is that the structure is simple and the design is reasonable. The waste alkali liquid to be treated is sent into the adjustment tank for static settlement to adjust the water quality and water volume.

[0022] Further, the adjustment device includes two adjustment tanks which are arranged side by side and are respectively connected to the flotation device through pipelines, and the feed pump one is fixedly installed on the pipelines connecting the two adjustment tanks and the flotation device respectively.

[0023] The beneficial effect of adopting the above further scheme is that the structure is simple and the design is reasonable. With two adjustment tanks, it can operate in two forms of parallel or series according to different working conditions, effectively regulating the water quality and water volume.

[0024] Further, the acidification and decarbonization device includes a pre-decarbonization mechanism and a deep aeration decarbonization mechanism. The flotation device, the pre-decarbonization mechanism, the deep aeration decarbonization mechanism and the advanced oxidation device are sequentially connected through pipelines; a feed pump two is fixedly installed on the pipeline connecting the pre-decarbonization mechanism and the deep aeration decarbonization mechanism.

[0025] The beneficial effect of adopting the above further scheme is that through the pre-decarbonization mechanism + deep aeration decarbonization mechanism, CO2 is discharged from the system and sent to the odor treatment system to ensure the normal operation of the subsequent process units.

[0026] Further, the tops of the pre-decarbonization mechanism and the deep aeration decarbonization mechanism are respectively connected to one end of a gas recovery pipeline, and the other end of the gas recovery pipeline is used to connect to the waste gas treatment system.

[0027] The beneficial effects of adopting the above further solution are as follows: the structure is simple and the design is reasonable. The gas recovery pipeline is used to simultaneously recover the CO2 generated in the pre-decarbonization mechanism + the deep aeration decarbonization mechanism, and discharge the CO2 out of the system and transport it to the odor treatment system to ensure the normal operation of the subsequent process units. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a schematic structural diagram of the present utility model.

[0029] In the drawings, the list of components represented by each reference numeral is as follows:

[0030] 1. Regulation tank; 2. Feed pump I; 3. Flotation device; 4. Pre-decarbonization mechanism; 5. Feed pump II; 6. Deep aeration decarbonization mechanism; 7. Advanced oxidation device; 8. Feed pump III; 9. Filter; 10. Evaporator water inlet tank; 11. Feed pump IV; 12. Multi-effect evaporation heat crystallization device; 13. Gas recovery pipeline. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0031] It should be noted that, without conflict, the embodiments in the present utility model and the features in the embodiments can be combined with each other.

[0032] In the description of the present utility model, it should be understood that the orientation or positional relationship indicated by the terms "center", "longitudinal", "transverse", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present utility model and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as a limitation to the present utility model. In addition, the terms "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the quantity of the indicated technical features. Thus, the features defined with "first", "second", etc. may explicitly or implicitly include one or more of such features. In the description of the present utility model, unless otherwise stated, the meaning of "a plurality" is two or more.

[0033] In the description of the present utility model, it should be noted that, unless otherwise clearly defined and limited, the terms "installed", "connected", "connected" should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or an integral connection; it may be a mechanical connection or an electrical connection; it may be directly connected or indirectly connected through an intermediate medium, and it may be the internal communication of two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present utility model can be understood according to specific circumstances.

[0034] The present utility model will be described in detail below with reference to the accompanying drawings and in conjunction with embodiments.

[0035] Embodiment 1

[0036] As Figure 1 shown, this embodiment provides a deep treatment system for spent caustic liquor in propylene production, including a pretreatment unit and an evaporation crystallization unit. The pretreatment unit includes a flotation device 3, an acidification and decarbonization device, and an advanced oxidation device 7. The flotation device 3, the acidification and decarbonization device, the advanced oxidation device 7, and the evaporation crystallization unit are sequentially connected through pipelines.

[0037] During the treatment process, first, the spent caustic liquor to be treated is transported to the flotation device 3, and the residual oil in the spent caustic liquor is removed by the flotation device by adding a coagulant. Secondly, the treated spent caustic liquor enters the acidification and decarbonization device for decarbonization treatment, and the CO2 is discharged from the system and transported to the odor treatment system to ensure the normal operation of the subsequent process units. Then, the wastewater treated by the acidification and decarbonization device enters the advanced oxidation device 7. The advanced oxidation adopts the Fenton oxidation process, and reagents such as ferrous sulfate, hydrogen peroxide, and flocculant are added in sequence to remove COD, suspended solids, sulfides, color, etc., to ensure the stable operation of the evaporation crystallization unit and reduce the amount of over-concentrated evaporation mother liquor. Finally, the spent caustic liquor is transported to the evaporation crystallization unit for evaporation crystallization.

[0038] It should be noted that the above-mentioned flotation device 3 and advanced oxidation device 7 respectively adopt existing technologies, and their specific structures and principles will not be elaborated here.

[0039] In addition, the Oleflex production process is a process mainly used for producing propylene.

[0040] The structure of this embodiment is compact and reasonably designed. Its purpose is to provide a device capable of treating spent caustic liquor in a reduced, resourceful, and harmless manner, realizing solid-liquid separation through a complete set of process systems, and finally obtaining evaporation condensate water that can be used for production reuse and relatively high-quality crystalline salts.

[0041] Embodiment 2

[0042] Based on Embodiment 1, in this embodiment, the evaporation crystallization unit includes a multi-effect evaporation heat crystallization device 12. The multi-effect evaporation heat crystallization device 12 is connected to the advanced oxidation device 7 through a pipeline, and a feed pump four 11 is fixedly installed on the pipeline connecting the multi-effect evaporation heat crystallization device 12 and the advanced oxidation device 7.

[0043] This scheme has a simple structure and is reasonably designed. The feed pump four 11 is used to transport the spent caustic liquor treated by the advanced oxidation device 7 to the multi-effect evaporation heat crystallization device 12 for evaporation crystallization.

[0044] It should be noted that the above-mentioned multi-effect evaporation crystallization device 12 adopts the existing technology, and its specific structure and principle will not be elaborated here.

[0045] Example 3

[0046] Based on Example 2, in this example, the evaporation crystallization unit further includes an evaporator water inlet tank 10. The top of the evaporator water inlet tank 10 is connected to the advanced oxidation device 7 through a pipeline, and the bottom of the evaporator water inlet tank 10 is connected to the inlet of the fourth feed pump 11 through a pipeline.

[0047] This solution has a simple structure and reasonable design. The evaporator water inlet tank 10 is used to store the waste alkali solution to be evaporated and crystallized, which is convenient for treatment.

[0048] Example 4

[0049] Based on Example 3, in this example, a filter 9 is fixedly installed on the pipeline connecting the evaporator water inlet tank 10 and the advanced oxidation device 7.

[0050] This solution has a simple structure and reasonable design. After removing suspended solids, colloids and other impurities in the water by the filter 9, it enters the evaporation crystallization unit to ensure the normal operation of the process.

[0051] It should be noted that the above-mentioned filter 9 adopts the existing technology, and its specific structure and principle will not be elaborated here.

[0052] In addition, the filtration accuracy of the above-mentioned filter 9 is 100 μm.

[0053] Example 5

[0054] Based on any one of Examples 3 to 4, in this example, a third feed pump 8 is fixedly installed on the pipeline connecting the evaporator water inlet tank 10 and the advanced oxidation device 7.

[0055] This solution has a simple structure and reasonable design. The third feed pump 8 is used to send the waste alkali solution treated by the advanced oxidation device 7 into the evaporator water inlet tank 10.

[0056] Based on the above solution, when the filter 9 and the third feed pump 8 are both set, the filter 9 is located between the third feed pump 8 and the evaporator water inlet tank 10.

[0057] Example 6

[0058] Based on the above-mentioned each example, in this example, the pretreatment unit further includes an adjusting device. The adjusting device is connected to the air flotation device 3 through a pipeline, and a first feed pump 2 is fixedly installed on the pipeline connecting the adjusting device and the air flotation device 3.

[0059] This solution has a simple structure and a reasonable design. The waste alkali liquor to be treated is sent to the regulating device for static settlement to adjust the water quality and quantity.

[0060] Example 7

[0061] On the basis of Example 6, in this example, the regulating device includes at least one regulating tank 1. The regulating tank 1 is connected to the air flotation device 3 through a pipeline, and the first feeding pump 2 is located on the pipeline connecting the regulating tank 1 and the air flotation device 3.

[0062] This solution has a simple structure and a reasonable design. The waste alkali liquor to be treated is sent to the regulating tank 1 for static settlement to adjust the water quality and quantity.

[0063] Based on the above solution, the waste alkali liquor to be treated is continuously fed into the regulating tank 1 through a pipeline, and after being placed in the regulating tank 1 for a period of time, it is then sent into the air flotation device 3.

[0064] It should be noted that the above-mentioned regulating tank 1 adopts the existing technology, and its specific structure and principle will not be elaborated here.

[0065] Example 8

[0066] On the basis of Example 7, in this example, the regulating device includes two regulating tanks 1. The two regulating tanks 1 are arranged side by side and are respectively connected to the air flotation device 3 through pipelines, and the first feeding pumps 2 are fixedly installed on the pipelines connecting the two regulating tanks 1 and the air flotation device 3.

[0067] This solution has a simple structure and a reasonable design. By adopting a double regulating tank, it can operate in two forms of parallel connection or series connection according to different working conditions, effectively regulating the water quality and quantity.

[0068] Preferably, in this example, the residence time of the waste alkali liquor in a single regulating tank is at least 12 hours.

[0069] Example 9

[0070] On the basis of the above-mentioned examples, in this example, the acidification and decarbonization device includes a pre-decarbonization mechanism 4 and a deep aeration decarbonization mechanism 6. The air flotation device 3, the pre-decarbonization mechanism 4, the deep aeration decarbonization mechanism 6 and the advanced oxidation device 7 are sequentially connected through pipelines; a second feeding pump 5 is fixedly installed on the pipeline connecting the pre-decarbonization mechanism 4 and the deep aeration decarbonization mechanism 6.

[0071] This solution discharges CO2 from the system to the odor treatment system through the pre-decarbonization mechanism 4 + the deep aeration decarbonization mechanism 6, ensuring the normal operation of the subsequent process units.

[0072] It should be noted that the above-mentioned preliminary decarbonization mechanism 4 adopts an aeration decarbonization stirring reaction device in the prior art, and the deep aeration decarbonization mechanism 6 adopts an aeration decarbonization packing tower in the prior art. The specific structures and principles of the aeration decarbonization stirring reaction device and the deep aeration decarbonization mechanism 6 will not be elaborated here.

[0073] Before decarbonization treatment, the pH value of the waste alkali liquor is reduced to below 5 by adding sulfuric acid to ensure the decarbonization efficiency.

[0074] Based on the above solution, the preliminary decarbonization mechanism 4 conducts preliminary decarbonization, with strong impact resistance and high design load.

[0075] In addition, the deep aeration decarbonization mechanism 6 conducts deep decarbonization, and the carbonate index of the effluent can be reduced to below 30 mg / L.

[0076] Example 10

[0077] On the basis of Example 9, in this embodiment, the tops of the preliminary decarbonization mechanism 4 and the deep aeration decarbonization mechanism 6 are respectively connected to one end of a gas recovery pipeline 13 through pipelines, and the other end of the gas recovery pipeline 13 is used to connect to an exhaust gas treatment system.

[0078] This solution has a simple structure and reasonable design. The gas recovery pipeline 13 is used to recover the CO2 generated in the preliminary decarbonization mechanism 4 + deep aeration decarbonization mechanism 6 at the same time, and the CO2 is discharged from the system and transported to the odor treatment system to ensure the normal operation of the subsequent process units.

[0079] The working principle of the present utility model is as follows:

[0080] The neutralized waste alkali liquor first enters the regulating tank 1 for water quality and quantity regulation. The water outlet of the regulating tank 1 is transported to the air flotation device 3 through the first feed pump 2. At the same time, a coagulant is added to the air flotation device 3 (that is, first add PAC (polyaluminum chloride), the dosage is 150 grams per ton of waste alkali liquor, and then add PAM (polyacrylamide), the dosage is 5 grams per ton of waste alkali liquor) to remove the residual oil in the wastewater by using the air flotation device 3.

[0081] The wastewater treated by the air flotation device 3 flows automatically (flows from the air flotation device 3 to the preliminary decarbonization mechanism 4, and at the same time, an appropriate amount of sulfuric acid with a mass fraction of 98% is added to the preliminary decarbonization mechanism 4 until the pH value is adjusted to below 5) into the acidification decarbonization device; since the pH value of the wastewater is relatively high and there are a large amount of sodium carbonate and sodium bicarbonate, it will affect the evaporation crystallization efficiency, and will directly affect the reaction efficiency of the subsequent advanced oxidation process unit under the condition of high-concentration carbonate. Therefore, the pH value is adjusted to an appropriate range (pH value less than 5) by adding concentrated sulfuric acid to ensure that after the carbonate and bicarbonate are converted into CO2, the CO2 is discharged from the system through the preliminary decarbonization mechanism 4 + deep aeration decarbonization mechanism 6 and transported to the odor treatment system to ensure the normal operation of the subsequent process units.

[0082] The wastewater treated by the acidification and decarbonization device enters the advanced oxidation device 7. The advanced oxidation adopts the Fenton oxidation process. By sequentially adding medicaments such as ferrous sulfate, hydrogen peroxide, and PAM, the dosage amounts are 1.5 kg, 2 L, and 5 g per ton of waste alkali liquor respectively, to remove COD, suspended solids, sulfides, chromaticity, etc., ensure the stable operation of the evaporation and crystallization unit, and reduce the amount of overly concentrated evaporation mother liquor. The effluent of the advanced oxidation process unit enters the evaporator inlet tank 10 of the evaporation and crystallization unit after removing suspended solids, colloids and other impurities in the water through the filtration of the filter 9.

[0083] After the waste liquid is adjusted in terms of water quality and quantity in the evaporator inlet tank 10, it is transported by the evaporator feed pump four 11 to the multi-effect evaporation and heat crystallization device 12 for evaporation and crystallization.

[0084] This process adopts a treatment scheme of multi-effect evaporation + heat crystallization. The solid-containing bottom liquid discharged from the thickener after the feed liquid is evaporated and concentrated enters the centrifuge for solid-liquid separation. The concentrated mother liquor that cannot be recycled is returned to the front section of the system for further treatment. The steam forms condensate through heat exchange and can be recycled, and the crystalline salt can be sold as an industrial product.

[0085] Compared with the current wastewater treatment technologies at home and abroad, the treatment system and process provided by the present utility model have the following advantages and positive effects:

[0086] (1) The front end of the system adopts a double-adjustment tank, which can operate in two forms of parallel or series according to different working conditions, and effectively regulate the water quality and quantity;

[0087] (2) The optimization combination of each process unit in the pretreatment system: remove light organic matters such as oils through air flotation to reduce the dosage of the advanced oxidation treatment; since carbonate and bicarbonate have a quenching effect on the hydroxyl radicals, which play the most important role in the advanced oxidation unit, eliminate the influence by placing the decarbonization unit in front; both the decarbonization unit and the Fenton oxidation unit need to lower the pH value to acidic to achieve the maximum efficiency, but the pH value needs to be adjusted back in the later stage of the Fenton reaction. Therefore, the decarbonization unit is placed in front to achieve one-time adjustment of the acidity and alkalinity, simplify the process, and save medicaments; finally, remove the remaining suspended solids through the mechanical filter to ensure the optimal conditions for the water inlet of the evaporation system;

[0088] (3) If indicators such as sulfides and pH value in the feed liquid far exceed the design values, ensure the normal operation of the system by adjusting the water quality at the front end, increasing the dosage of medicaments and operation settings;

[0089] (4) Due to the high carbonate content of the feed liquid, the decarbonization unit adopts a two-stage treatment system to achieve separate treatment of different qualities, improve the reaction efficiency, and reduce energy consumption; the first stage adopts an aeration decarbonization reaction tank with a high design load, strong impact resistance, and low engineering cost; the second stage adopts a decarbonization packing tower with a high reaction efficiency, and the effluent CO2 index can be reduced to 5 mg / L;

[0090] (5) Reduce the contents of organic matters, oils, and non-target miscellaneous salts, etc. before evaporation crystallization, so as to reduce the output of by-product evaporation concentrated solution, improve the quality of salt products and recycled condensed water, and reduce the risk of scale formation during the operation of the evaporator.

[0091] (6) There are only two major process units in the entire advanced treatment system, namely the pretreatment unit and the evaporation crystallization unit. The equipment quantity is small, the process flow is simple, and the degree of automation is high, which further reduces the failure rate of the equipment, increases the process stability, and ensures continuous operation.

[0092] The process system provided by the present utility model is also applicable to treating a type of industrial wastewater containing oil, high COD, high salinity, and having low-boiling organic matters with low solubility or inorganic matters such as ammonia and sulfur. Ultimately, stable operation, zero discharge, and by-product resource utilization can be achieved. Main application fields: petrochemical industry, fine chemical industry, pharmaceutical industry, etc.

[0093] It should be noted that all the electronic components involved in the present utility model adopt existing technologies, and the above-mentioned components are electrically connected to the controller. The control circuit between the controller and each component is an existing technology.

[0094] For those skilled in the art, it is obvious that the present utility model is not limited to the details of the above-mentioned exemplary embodiments, and without departing from the spirit or basic characteristics of the present utility model, the present utility model can be implemented in other specific forms. Therefore, from any point of view, the embodiments should be regarded as exemplary and non-restrictive. The scope of the present utility model is defined by the appended claims rather than the above description. Therefore, all changes falling within the meaning and scope of the equivalent elements of the claims are intended to be included in the present utility model. Any reference signs in the claims should not be regarded as limiting the claimed rights.

[0095] In addition, it should be understood that although this specification is described according to the embodiments, not every embodiment only contains an independent technical solution. This narrative way of the specification is only for clarity. Those skilled in the art should regard the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

[0096] The above are only the preferred embodiments of the present utility model and are not intended to limit the present utility model. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present utility model shall be included in the protection scope of the present utility model.

Claims

1. A deep treatment system for waste alkali liquor in propylene production, characterized in that: It includes a pretreatment unit and an evaporation crystallization unit. The pretreatment unit includes a flotation device (3), an acidification and decarbonization device, and an advanced oxidation device (7). The flotation device (3), the acidification and decarbonization device, the advanced oxidation device (7), and the evaporation crystallization unit are connected in sequence through pipelines.

2. The deep treatment system for waste alkali liquor in propylene production according to claim 1, wherein: The evaporation crystallization unit includes a multi-effect evaporation heat crystallization device (12). The multi-effect evaporation heat crystallization device (12) is connected to the advanced oxidation device (7) through a pipeline, and a feed pump four (11) is fixedly installed on the pipeline connecting the multi-effect evaporation heat crystallization device (12) and the advanced oxidation device (7).

3. The deep treatment system for spent caustic liquor in propylene production according to claim 2, characterized in that: The evaporation crystallization unit further includes an evaporator water inlet tank (10). The top of the evaporator water inlet tank (10) is connected to the advanced oxidation device (7) through a pipeline, and the bottom of the evaporator water inlet tank (10) is connected to the inlet of the feed pump four (11) through a pipeline.

4. The deep treatment system for waste alkali liquor in propylene production according to claim 3, wherein: A filter (9) is fixedly installed on the pipeline connecting the evaporator water inlet tank (10) and the advanced oxidation device (7).

5. The deep treatment system for spent caustic liquor in propylene production according to claim 3, characterized in that: A feed pump three (8) is fixedly installed on the pipeline connecting the evaporator water inlet tank (10) and the advanced oxidation device (7).

6. The deep treatment system for waste alkali liquor in propylene production according to any one of claims 1-5, characterized in that: The pretreatment unit further includes a regulating device. The regulating device is connected to the flotation device (3) through a pipeline, and a feed pump one (2) is fixedly installed on the pipeline connecting the regulating device and the flotation device (3).

7. The deep treatment system for waste alkali liquor in propylene production according to claim 6, characterized in that: The regulating device includes at least one regulating tank (1). The regulating tank (1) is connected to the flotation device (3) through a pipeline, and the feed pump one (2) is located on the pipeline connecting the regulating tank (1) and the flotation device (3).

8. The deep treatment system for spent caustic liquor in propylene production according to claim 7, characterized in that: The regulating device includes two regulating tanks (1). The two regulating tanks (1) are arranged side by side and are respectively connected to the flotation device (3) through pipelines, and the feed pump one (2) is fixedly installed on the pipelines connecting the two regulating tanks (1) and the flotation device (3) respectively.

9. The deep treatment system for spent caustic liquor in propylene production according to any one of claims 1-5, characterized in that: The acidification and decarbonization device includes a pre-decarbonization mechanism (4) and a deep aeration decarbonization mechanism (6). The flotation device (3), the pre-decarbonization mechanism (4), the deep aeration decarbonization mechanism (6), and the advanced oxidation device (7) are connected in sequence through pipelines; a feed pump two (5) is fixedly installed on the pipeline connecting the pre-decarbonization mechanism (4) and the deep aeration decarbonization mechanism (6).

10. The deep treatment system for waste alkali liquor in propylene production according to claim 9, characterized in that: The tops of the pre-decarbonization mechanism (4) and the deep aeration decarbonization mechanism (6) are respectively connected to one end of a gas recovery pipeline (13), and the other end of the gas recovery pipeline (13) is used to connect to an exhaust gas treatment system.

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