Device and method for treating nitric oxide generated by cyclohexanone oximation wastewater

Abstract

The invention provides a device and method for treating nitrogen oxides generated by cyclohexanone oximation wastewater, the device comprises an air blower, a tail gas absorption tower, a first circulating pump and a condenser, the air inlet of the air blower is aligned with yellow smoke gas generated in the cyclohexanone oximation wastewater treatment process, and the exhaust port of the air blower is introduced into the bottom of the tail gas absorption tower; the bottom of the tail gas absorption tower is communicated to the top of the tail gas absorption tower through a circulating pipeline and extends into the tail gas absorption tower to be communicated with a liquid distributor, a first circulating pump and a condenser are sequentially arranged on the circulating pipeline, and an input pipeline is connected to the position, close to the top of the tail gas absorption tower, of the circulating pipeline; the input pipeline is used for introducing a dilute nitric acid solution, and the circulating pipeline is provided with an output pipeline at a position between the condenser and the top of the tail gas absorption tower. The method realizes atom recovery and cyclic utilization, reduces total nitrogen in wastewater, is economical and environment-friendly, and has good sustainability; meanwhile, the treatment cost of the wastewater can be reduced.

Description

Technical Field

[0001] The invention relates to the technical field of chemical preparation, and in particular to a device and method for treating nitrogen oxides generated by cyclohexanone oximation wastewater. Background Art

[0002] The wastewater generated in the cyclohexanone oximation process of caprolactam production often produces toxic and harmful nitrogen oxide yellow smoke during the treatment process, which not only pollutes the environment, but is also very detrimental to the health of on-site workers. In addition, due to the high total nitrogen content and difficulty in treatment, this wastewater has always been a technical difficulty and pain point in the industry.

[0003] At present, the treatment method for nitrogen oxides generated in the process of cyclohexanone oximation production wastewater treatment usually adopts alkaline solution absorption method or solid catalyst absorption method. Although both methods can effectively absorb nitrogen oxides, they have the following problems:

[0004] 1. High processing cost

[0005] The use of alkaline solution absorption method will produce the accumulation of inorganic salts, which need to be cleaned regularly. It will also produce a certain amount of wastewater entering the biochemical treatment device, which requires the addition of a composite carbon source to treat the wastewater, increasing the consumption cost of the composite carbon source and the wastewater treatment cost, and at the same time will increase the operating load of the biochemical treatment device.

[0006] The solid catalyst absorption method uses a solid catalyst, which is expensive and has a large loss during use.

[0007] 2. Low atomic economy utilization

[0008] Neither the alkaline solution absorption method nor the solid catalyst absorption method can achieve the recovery and recycling of nitrogen atoms, and the atomic economic utilization rate is low.

[0009] Therefore, how to reduce the total nitrogen in oxime wastewater, improve the economic utilization value of atoms, realize green recycling and utilization, and save treatment costs under the premise of ensuring effective absorption of nitrogen oxides is an important direction for the long-term development of the industry. Summary of the invention

[0010] In order to solve the above problems in the prior art, the present invention provides a device and method for treating nitrogen oxides produced by cyclohexanone oximation wastewater, which can reduce the treatment cost and improve the atomic economic utilization rate.

[0011] In order to achieve the above object, the technical solution adopted by the present invention is:

[0012] In a first aspect, the present invention provides a device for treating nitrogen oxides generated by cyclohexanone oximation wastewater, comprising a blower, a tail gas absorption tower, a first circulation pump and a condenser, wherein the air inlet of the blower is aligned with the yellow smoke gas generated in the process of treating the cyclohexanone oximation wastewater, and the exhaust port thereof is connected to the bottom of the tail gas absorption tower;

[0013] The bottom of the tail gas absorption tower is connected to the top of the tail gas absorption tower through a circulation pipeline, and extends into the tail gas absorption tower to be connected with a liquid distributor. The first circulation pump and the condenser are sequentially arranged on the circulation pipeline. The circulation pipeline is connected to an input pipeline at a position close to the top of the tail gas absorption tower. The input pipeline is used to pass a dilute nitric acid solution. The circulation pipeline is provided with an output pipeline at a position between the condenser and the top of the tail gas absorption tower.

[0014] The beneficial effects of the present invention are as follows: the yellow smoke generated in the process of treating production wastewater is eliminated by adopting the method of countercurrent absorption of nitrogen oxides by dilute nitric acid, and the dilute nitric acid generated after the nitrogen dioxide in the nitrogen oxides is dissolved in water and absorbed can be continuously used, thereby realizing atomic recovery and recycling, reducing the total nitrogen in the wastewater, being economical, environmentally friendly and having good sustainability; at the same time, no expensive solid catalyst is required, the total amount of wastewater generated is reduced, the consumption of composite carbon sources is reduced, and thus the treatment cost is reduced.

[0015] Optionally, it further comprises a ceramic membrane filter, an oximation production wastewater storage tank, a pH adjustment storage tank, a static mixer, a stirring mixer, a Fenton reaction tank and a biochemical tank, wherein the wastewater outlet of the ceramic membrane filter is connected to the water inlet of the oximation production wastewater storage tank, the water outlet of the oximation production wastewater storage tank and the water outlet of the pH adjustment storage tank are simultaneously connected to the water inlet of the static mixer, the water outlet of the static mixer is connected to the water inlet of the stirring mixer, the water outlet of the stirring mixer leads to the Fenton reaction tank, and the water outlet of the Fenton reaction tank is connected to the water inlet of the biochemical tank;

[0016] The air inlet of the blower is aligned with the top of the Fenton reaction tank, and the output end of the output pipeline is connected to the top of the ceramic membrane filter.

[0017] Optionally, the output pipeline is connected to a dilution pipeline, and the dilution pipeline is used to input desalted water.

[0018] According to the above description, the output solution is diluted to a suitable concentration by desalted water for easy recycling.

[0019] Optionally, a control valve is also provided on the output pipeline.

[0020] In a second aspect, a method for treating nitrogen oxides generated by cyclohexanone oximation wastewater comprises the following steps:

[0021] S1. Blowing the yellow smoke generated in the cyclohexanone oximation wastewater treatment process into the bottom of the tail gas absorption tower through a blower;

[0022] S2, the dilute nitric acid solution enters the liquid distributor at the top of the tail gas absorption tower through the input pipeline, and the dilute nitric acid solution is sprayed through the liquid distributor to countercurrently absorb the yellow smoke gas, and circulates through the circulation pipeline for multiple absorption, and removes the reaction heat through the condenser;

[0023] S3. After the absorption is completed, the dilute nitric acid solution generated is output through the output pipeline and circulated back to the ceramic membrane filter for membrane tube cleaning.

[0024] Optionally, the mass concentration of the dilute nitric acid solution sprayed into the tail gas absorption tower is 15%-30%.

[0025] Optionally, the absorption temperature of the tail gas absorption tower is 15-20°C and the pressure is 0.1-0.3MPa.

[0026] Optionally, the method further comprises the steps of:

[0027] The wastewater after cleaning the ceramic membrane filter is collected in the oximation production wastewater storage tank. The wastewater in the oximation production wastewater storage tank is input into the static mixer through the second circulation pump and the concentrated sulfuric acid in the pH adjustment tank is input into the static mixer through the third circulation pump for mixing. The pH of the wastewater is adjusted to be acidic, and then the wastewater is introduced into the stirring mixer for secondary stirring to be evenly mixed.

[0028] The wastewater evenly mixed in the stirring mixer is added to the Fenton reaction tank for reaction. The wastewater that meets the treatment standards enters the subsequent biochemical pool for treatment and is discharged into the river after meeting the discharge standards.

[0029] Among them, the technical effect corresponding to the method for treating nitrogen oxides generated by cyclohexanone oximation wastewater provided in the second aspect refers to the relevant description of the device for treating nitrogen oxides generated by cyclohexanone oximation wastewater provided in the first aspect. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 This is a schematic structural diagram of a device for treating nitrogen oxides generated by cyclohexanone oximation wastewater according to an embodiment of the present invention;

[0031] Figure 2 The present invention is a schematic flow chart of a method for treating nitrogen oxides produced by cyclohexanone oximation wastewater according to an embodiment of the present invention.

[0032] Description of reference numerals:

[0033] 1. Blower; 2. Tail gas absorption tower; 3. First circulation pump; 4. Condenser; 5. Circulation pipeline; 6. Liquid distributor; 7. Input pipeline; 8. Output pipeline; 9. Ceramic membrane filter; 10. Oximation production wastewater storage tank; 11. pH adjustment tank; 12. Static mixer; 13. Stirring mixer; 14. Fenton reaction tank; 15. Biochemical tank; 16. Dilution pipeline; 17. Control valve; 18. Second circulation pump; 19. Third circulation pump. DETAILED DESCRIPTION

[0034] In order to better understand the above technical solution, exemplary embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. Although exemplary embodiments of the present invention are shown in the accompanying drawings, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments described herein. On the contrary, these embodiments are provided to enable a clearer and more thorough understanding of the present invention and to fully convey the scope of the present invention to those skilled in the art.

[0035] Embodiment 1

[0036] The existing alkaline solution absorption method or solid catalyst absorption method has the problems of high treatment cost and low atomic economic utilization rate. Therefore, this embodiment adopts the method of countercurrent absorption of nitrogen oxides by dilute nitric acid to eliminate the yellow smoke generated in the process of production wastewater treatment, thus solving the existing problems. The specific improvements are as follows:

[0037] Please refer to Figure 1 A device for treating nitrogen oxides produced by cyclohexanone oximation wastewater comprises a blower 1, a tail gas absorption tower 2, a first circulation pump 3, a condenser 4, a ceramic membrane filter 9, an oximation production wastewater storage tank 10, a pH adjustment storage tank 11, a static mixer 12, a stirring mixer 13, a Fenton reaction tank 14 and a biochemical tank 15.

[0038] Among them, the wastewater outlet of the ceramic membrane filter 9 is connected to the water inlet of the oximation production wastewater storage tank 10, the water outlet of the oximation production wastewater storage tank 10 is connected to the water inlet of the static mixer 12 through the second circulation pump 18 and the water outlet of the pH adjustment tank 11 through the third circulation pump 19, the water outlet of the static mixer 12 is connected to the water inlet of the stirring mixer 13, the water outlet of the stirring mixer 13 is connected to the Fenton reaction tank 14, and the water outlet of the Fenton reaction tank 14 is connected to the water inlet of the biochemical tank 15.

[0039] In this embodiment, concentrated sulfuric acid is introduced into the pH adjustment tank 11 for pH adjustment, and the pH of the wastewater in the static mixer 12 is between 2-5.

[0040] Among them, the air inlet of the blower 1 is aimed at the top of the Fenton reaction tank 14, and at the yellow smoke gas generated during the treatment of cyclohexanone oximation wastewater, and its exhaust port is connected to the bottom of the tail gas absorption tower 2. The bottom of the tail gas absorption tower 2 is connected to the top of the tail gas absorption tower 2 through a circulation pipeline 5, and extends into the tail gas absorption tower 2 to be connected with a liquid distributor 6. The circulation pipeline 5 is sequentially provided with a first circulation pump 3 and a condenser 4. The circulation pipeline 5 is connected to an input pipeline 7 at a position close to the top of the tail gas absorption tower 2. The input pipeline 7 is used to pass a dilute nitric acid solution. The circulation pipeline 5 is provided with an output pipeline 8 at a position between the condenser 4 and the top of the tail gas absorption tower 2. The output end of the output pipeline 8 is connected to the top of the ceramic membrane filter 9.

[0041] The output pipeline 8 is connected to a dilution pipeline 16 for inputting desalted water. The desalted water dilutes the dilute nitric acid solution in the output pipeline 8 to a suitable concentration and then passes into the ceramic membrane filter 9 for cleaning.

[0042] The output pipeline 8 is also provided with a control valve 17 so that the control valve 17 is opened to output the treated solution only after multiple cycles of absorption.

[0043] like Figure 1 As shown, the tail gas absorption tower 2 is also provided with a tail gas discharge pipeline for tail gas discharge.

[0044] The working principle of this embodiment refers to that of the second embodiment.

[0045] Embodiment 2

[0046] A method for treating nitrogen oxides generated by cyclohexanone oximation wastewater comprises the following steps:

[0047] S01, collecting the wastewater after cleaning the ceramic membrane filter 9 in the oximation production wastewater storage tank 10, the wastewater in the oximation production wastewater storage tank 10 is input into the static mixer 12 through the second circulation pump 18 and the concentrated sulfuric acid in the pH adjustment storage tank 11 through the third circulation pump 19 for mixing, adjusting the pH of the wastewater to acidic, and then passing into the stirring mixer 13 for secondary stirring and mixing evenly;

[0048] In this embodiment, concentrated sulfuric acid is used to adjust the pH of the wastewater in the oximation production wastewater storage tank 10 so that the pH of the wastewater in the static mixer 12 is between 2-5.

[0049] S02, adding the wastewater mixed evenly in the stirring mixer 13 to the Fenton reaction tank 14 for reaction, and the wastewater that meets the treatment standard enters the subsequent biochemical tank 15 for treatment, and is discharged into the river after meeting the discharge standard;

[0050] S1, blowing the yellow smoke gas generated in the cyclohexanone oximation wastewater treatment process into the bottom of the tail gas absorption tower 2 through the blower 1;

[0051] The blower 1 is arranged above the Fenton reaction pool 14 to absorb the toxic and harmful yellow smoke gas generated in the upper part of the Fenton reaction pool 14 into the tail gas absorption tower 2 for treatment.

[0052] Among them, the main components of yellow smoke gas are:

[0053] NO2: 1000-1500mg / m 3 ; NO: 200-300mg / m 3 ; N2O: 0-100mg / m 3 .

[0054] S2. The dilute nitric acid solution enters the liquid distributor 6 at the top of the tail gas absorption tower 2 through the input pipeline 7, and the dilute nitric acid solution is sprayed through the liquid distributor 6 to countercurrently absorb the yellow smoke gas, and is circulated through the circulation pipeline 5 for multiple absorption, and the reaction heat is removed through the condenser 4.

[0055] In this embodiment, the mass concentration of the dilute nitric acid solution is 15%-30%, such as 18% and 23%. In this embodiment, the absorption temperature of the tail gas absorption tower 2 is 15-20°C and the pressure is 0.1-0.3MPa, such as the absorption temperature is 16°C and the pressure is 0.18MPa. The condenser 4 cools the solution in the circulation line 5 to below 20°C.

[0056] Among them, the nitrogen monoxide in the nitrogen oxides will be oxidized into nitrogen dioxide and dissolved in a dilute nitric acid solution. Since new nitrogen monoxide will be generated during the absorption process, multiple absorptions are required to reduce the concentration of nitrogen oxides in the gas to the expected target.

[0057] S3. After the absorption is completed, the dilute nitric acid solution generated is output through the output pipeline 8 and circulated back to the ceramic membrane filter 9 for membrane tube cleaning and recycling.

[0058] Among them, the nitrogen oxide concentration in the gas after absorption is less than 80mg / m 3 , its absorption effect reaches more than 98%.

[0059] The dilute nitric acid solution is returned to the ceramic membrane filter 9 through the output pipeline 8 for membrane tube cleaning, thereby achieving nitrogen oxide absorption and recycling.

[0060] In summary, the above embodiment uses the method of countercurrent absorption of nitrogen oxides by dilute nitric acid to eliminate the yellow smoke generated in the process of industrial wastewater treatment, which has the following advantages:

[0061] (1) Reduce total nitrogen content and reduce wastewater treatment costs: Compared with the alkaline solution absorption method, the total amount of wastewater generated is reduced and the consumption of composite carbon sources is reduced; compared with the solid catalyst absorption method, no expensive solid catalyst is required, thereby reducing the treatment cost.

[0062] (2) High atomic economic utilization rate: The nitrogen dioxide in nitrogen oxides is dissolved in water and absorbed to generate dilute nitric acid which is returned to the oximation production process for cleaning membrane tubes, thus achieving atomic recovery and recycling, reducing the total nitrogen in wastewater, being economical, environmentally friendly and sustainable.

[0063] (3) Optimized process: No by-product salt precipitation is produced, and no manual intervention is required for cleaning, which simplifies the process.

[0064] (4) Green and environmentally friendly: It eliminates the generation of toxic and harmful gases during the treatment of cyclohexanone oximation wastewater, ensuring the health of on-site workers.

[0065] In the description of the present invention, it should be understood that the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0066] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium; it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0067] In the present invention, unless otherwise clearly specified and limited, when a first feature is “on” or “below” a second feature, it may be that the first and second features are in direct contact, or that the first and second features are in indirect contact through an intermediate medium. Moreover, when a first feature is “above”, “above” or “above” a second feature, it may be that the first feature is directly above or obliquely above the second feature, or it may simply mean that the first feature is higher in level than the second feature. When a first feature is “below”, “below” or “below” a second feature, it may be that the first feature is directly below or obliquely below the second feature, or it may simply mean that the first feature is lower in level than the second feature.

[0068] In the description of this specification, the description of the terms "one embodiment", "some embodiments", "embodiment", "example", "specific example" or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, unless they are contradictory.

[0069] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations of the present invention. A person skilled in the art may alter, modify, replace and modify the above embodiments within the scope of the present invention.

Claims

1. A device for treating nitrogen oxides produced by cyclohexanone oximation wastewater, characterized in that: It includes a blower, a tail gas absorption tower, a first circulation pump and a condenser, wherein the air inlet of the blower is aimed at the yellow smoke gas generated in the process of treating cyclohexanone oximation wastewater, and the exhaust port thereof is connected to the bottom of the tail gas absorption tower; The bottom of the tail gas absorption tower is connected to the top of the tail gas absorption tower through a circulation pipeline, and extends into the tail gas absorption tower to be connected with a liquid distributor. The first circulation pump and the condenser are sequentially arranged on the circulation pipeline. The circulation pipeline is connected to an input pipeline at a position close to the top of the tail gas absorption tower. The input pipeline is used to pass a dilute nitric acid solution. The circulation pipeline is provided with an output pipeline at a position between the condenser and the top of the tail gas absorption tower.

2. The device for treating nitrogen oxides produced by cyclohexanone oximation wastewater according to claim 1, characterized in that: It also includes a ceramic membrane filter, an oximation production wastewater storage tank, a pH adjustment storage tank, a static mixer, a stirring mixer, a Fenton reaction tank and a biochemical tank, wherein the wastewater outlet of the ceramic membrane filter is connected to the water inlet of the oximation production wastewater storage tank, the water outlet of the oximation production wastewater storage tank and the water outlet of the pH adjustment storage tank are simultaneously connected to the water inlet of the static mixer, the water outlet of the static mixer is connected to the water inlet of the stirring mixer, the water outlet of the stirring mixer leads to the Fenton reaction tank, and the water outlet of the Fenton reaction tank is connected to the water inlet of the biochemical tank; The air inlet of the blower is aligned with the top of the Fenton reaction tank, and the output end of the output pipeline is connected to the top of the ceramic membrane filter.

3. The device for treating nitrogen oxides produced by cyclohexanone oximation wastewater according to claim 1, characterized in that: The output pipeline is connected with a dilution pipeline, and the dilution pipeline is used for inputting desalted water.

4. The device for treating nitrogen oxides produced by cyclohexanone oximation wastewater according to claim 1, characterized in that: The output pipeline is also provided with a control valve.

5. A method for treating nitrogen oxides produced by cyclohexanone oximation wastewater, characterized in that: The following steps are involved: S1. Blowing the yellow smoke generated in the cyclohexanone oximation wastewater treatment process into the bottom of the tail gas absorption tower through a blower; S2, the dilute nitric acid solution enters the liquid distributor at the top of the tail gas absorption tower through the input pipeline, and the dilute nitric acid solution is sprayed through the liquid distributor to countercurrently absorb the yellow smoke gas, and circulates through the circulation pipeline for multiple absorption, and removes the reaction heat through the condenser; S3. After the absorption is completed, the dilute nitric acid solution generated is output through the output pipeline and circulated back to the ceramic membrane filter for membrane tube cleaning.

6. The method for treating nitrogen oxides produced by cyclohexanone oximation wastewater according to claim 5, characterized in that: The mass concentration of the dilute nitric acid solution sprayed into the tail gas absorption tower is 15%-30%.

7. The method for treating nitrogen oxides produced by cyclohexanone oximation wastewater according to claim 5, characterized in that: The absorption temperature of the tail gas absorption tower is 15-20°C and the pressure is 0.1-0.3MPa.

8. The method for treating nitrogen oxides produced by cyclohexanone oximation wastewater according to claim 5, characterized in that: Also includes the steps: The wastewater after cleaning the ceramic membrane filter is collected in the oximation production wastewater storage tank. The wastewater in the oximation production wastewater storage tank is input into the static mixer through the second circulation pump and the concentrated sulfuric acid in the pH adjustment tank is input into the static mixer through the third circulation pump for mixing. The pH of the wastewater is adjusted to be acidic, and then the wastewater is introduced into the stirring mixer for secondary stirring to be evenly mixed. The wastewater evenly mixed in the stirring mixer is added to the Fenton reaction tank for reaction. The wastewater that meets the treatment standards enters the subsequent biochemical pool for treatment and is discharged into the river after meeting the discharge standards.

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