Phenylacetonitrile brine circulating treatment device

Abstract

The utility model provides a phenylacetonitrile brine circulating treatment device, which belongs to the technical field of wastewater treatment and comprises a decyanation and decarbonization unit, a purification unit, a separation unit and a condensation unit which are sequentially connected through pipelines, and a first absorption unit and a second absorption unit are connected between the separation unit and the condensation unit in parallel. The purification unit comprises an adsorption column and a recovery liquid storage tank; the separation unit comprises a separator, a separation liquid storage tank and a separation liquid circulating pump, and the separation liquid circulating pump is connected to a circulating pipeline between the separation liquid storage tank and the separator; the first absorption unit comprises a first absorber, a first absorption liquid storage tank and a first absorption liquid circulating pump; the second absorption unit comprises a second absorber, a second absorption liquid storage tank and a second absorption liquid circulating pump; and the second absorber is used for absorbing HCN gas escaped by the separation liquid. Through cyclic treatment of HCN, the obtained high-quality sodium cyanide solution can be directly used as a production raw material for benzyl cyanide production, so that cyclic utilization of resources is realized.

Description

Technical Field

[0001] The utility model belongs to the technical field of wastewater treatment, and particularly relates to a device for recycling and treating phenylacetonitrile brine. Background Art

[0002] As an important intermediate, phenylacetonitrile is widely used in the pharmaceutical and agricultural industries for manufacturing phoxim, dialifos, penicillin, phenobarbital, etc. At present, the main method for synthesizing phenylacetonitrile is to use benzyl chloride and sodium cyanide as raw materials, and carry out a cyanidation synthesis reaction under the action of a catalyst to obtain a crude product of phenylacetonitrile and a brine mixture. After standing and separating, the oil phase is distilled to obtain the finished product of phenylacetonitrile, while the main component in the brine is a large amount of sodium chloride, and it also contains sodium cyanide, sodium carbonate, etc. Sodium cyanide has a bitter almond smell and is highly toxic. Skin contact or inhalation can cause poisoning and death. Therefore, the phenylacetonitrile brine must be subjected to decyanation treatment before entering the evaporation and biochemical water treatment systems.

[0003] At present, the decyanation treatment method is to set up a stripping method to escape the cyanide-containing and carbon-containing tail gas and other organic impurities in the wastewater in the form of gas. After the organic impurities in the tail gas are adsorbed by a resin adsorption column, the cyanide-containing and carbon-containing tail gas enters an absorption device, and the HCN and CO2 are absorbed by an alkaline solution to obtain a sodium cyanide solution. Then, a calcium chloride solution is added through a filtering device to generate a precipitate of CO3 2- ions, and the sodium cyanide solution is obtained through plate-frame filtration and recycled to the phenylacetonitrile production system. Adding calcium chloride solution can convert Na2CO3 into BaCO3 precipitate, and the CO3 2- ions are removed after filtration. However, there are excessive cyanide ions in the BaCO3 precipitate after filtration and cannot be completely separated, increasing the treatment cost. At the same time, due to the presence of Ba 2+ in the recycled sodium cyanide solution, when it is reused in the synthesis reaction process of phenylacetonitrile products again, the quality of phenylacetonitrile products cannot be guaranteed. Summary of the Utility Model

[0004] The embodiment of the utility model provides a device for recycling and treating phenylacetonitrile brine, aiming to solve the problem of poor quality of the recycled sodium cyanide from the current phenylacetonitrile brine.

[0005] To achieve the above object, the technical solution adopted by the utility model is: providing a device for recycling and treating phenylacetonitrile brine, including: a decyanation and decarbonization unit, a purification unit, a separation unit, and a condensation unit connected in sequence through pipelines, and a first absorption unit and a second absorption unit are connected in parallel between the separation unit and the condensation unit;

[0006] The purification unit includes an adsorption column and a recovered liquid storage tank; the bottom air inlet of the adsorption column is communicated with the top air outlet of the decyanation and decarbonization unit; the recovered liquid storage tank is communicated with the bottom liquid outlet of the adsorption column;

[0007] The separation unit includes a separator, a separated liquid storage tank, and a separated liquid circulation pump. The separator air inlet on the side of the separator communicates with the top air outlet of the adsorption column. The separated liquid storage tank is connected to the separator liquid outlet at the bottom of the separator. The separated liquid circulation pump is connected to the circulation pipeline between the separated liquid storage tank and the separator. A heat exchanger is provided on the circulation pipeline between the separated liquid storage tank and the separator;

[0008] The first absorption unit includes a first absorber, a first absorption liquid storage tank, and a first absorption liquid circulation pump. The side air inlet of the first absorber communicates with the separator air outlet at the top of the separator. The first absorption liquid storage tank is connected to the bottom liquid outlet of the first absorber. The first absorption liquid circulation pump is connected to the circulation pipeline between the first absorption liquid storage tank and the first absorber. The top air outlet of the first absorber communicates with the condensation unit;

[0009] The second absorption unit includes a second absorber, a second absorption liquid storage tank, and a second absorption liquid circulation pump. The side air inlet of the second absorber communicates with the separator air outlet at the top of the separator. The second absorption liquid storage tank is connected to the bottom liquid outlet of the second absorber. The second absorption liquid circulation pump is connected to the circulation pipeline between the second absorption liquid storage tank and the second absorber. The top air outlet of the second absorber communicates with the condensation unit.

[0010] In an implementable manner, a storage unit is further included. The storage unit includes a pre-treatment brine storage tank, a hydrochloric acid storage tank, a post-treatment brine storage tank, a recovered sodium cyanide storage tank, and a sodium carbonate storage tank. The pre-treatment brine storage tank and the hydrochloric acid storage tank are connected in parallel to the side liquid inlet of the cyanide and carbon dioxide removal unit. The post-treatment brine storage tank is connected to the liquid outlet of the cyanide and carbon dioxide removal unit. The sodium carbonate storage tank is connected to the circulation pipeline between the first absorption liquid storage tank and the first absorber. The recovered sodium cyanide storage tank is connected to the circulation pipeline between the second absorption liquid storage tank and the second absorber.

[0011] In an implementable manner, the cyanide and carbon dioxide removal unit includes an adjustment device, a cyanide and carbon dioxide removal tower, a reboiler, and a withdrawal pump connected in sequence. The feed inlet of the adjustment device is respectively connected to the discharge outlets of the pre-treatment brine storage tank and the hydrochloric acid storage tank. The discharge outlet of the adjustment device is connected to the side liquid inlet of the cyanide and carbon dioxide removal tower. The top air outlet of the cyanide and carbon dioxide removal tower is connected to the bottom air inlet of the adsorption column. The bottom liquid outlet of the cyanide and carbon dioxide removal tower is connected to the reboiler. The withdrawal pump is connected to the post-treatment brine storage tank.

[0012] In an implementable manner, a spraying device and a separation device are arranged in the separator from top to bottom.

[0013] In an achievable manner, the separation device includes a plurality of groups of packing plates arranged in layers from top to bottom. Each group of packing plates includes a plurality of packing plate sheets arranged obliquely in the same direction. The packing plate sheets in two adjacent groups of packing plates from top to bottom are inclined in different directions and are correspondingly connected one by one. The two packing plate sheets connected up and down are arranged at an included angle.

[0014] In an achievable manner, an on-line temperature monitor is provided on the circulation pipeline between the separation liquid storage tank and the separator. The on-line temperature monitor is arranged at the outlet end of the separation liquid circulation pump.

[0015] In an achievable manner, a first on-line density monitor is installed on the circulation pipeline between the first absorption liquid storage tank and the first absorber; a second on-line density monitor is installed on the circulation pipeline between the second absorption liquid storage tank and the second absorber.

[0016] In an achievable manner, the condensation unit includes an induced draft fan, a condenser and a condensate collection tank. The air inlet of the induced draft fan is respectively communicated with the top air outlets of the first absorber and the second absorber. The air outlet of the induced draft fan is communicated with the side air inlet of the condenser. The bottom discharge port of the condenser is communicated with the feed port of the condensate collection tank.

[0017] In an achievable manner, a tail gas deep treatment device and a gas on-line analyzer are provided at the top air outlet of the condenser.

[0018] In an achievable manner, a gas-liquid separator is further included and is communicated between the first absorber, the second absorber and the condensation unit.

[0019] The phenylacetonitrile brine circulation treatment device provided by the present utility model, compared with the prior art, has the beneficial effects that: a separation unit is provided, and a separator is arranged in the separation unit. Through the different solubilities of HCN and CO2 in the separation liquid in the separator, the gas separation of HCN and CO2 is realized. Then, HCN is analyzed from the separation liquid by heating and analyzing the separation liquid through a heat exchanger; in the second absorption unit, HCN is converted into a high-quality sodium cyanide solution through the absorption of the absorption liquid and is directly used as a production raw material in the production process of phenylacetonitrile.

[0020] The phenylacetonitrile brine circulation treatment device provided by the present utility model has a simple treatment process, can solve the problems of poor quality of the recycled sodium cyanide solution and inability to be recycled normally in the process of phenylacetonitrile brine treatment, thereby realizing the recycling of resources and reducing the production cost of phenylacetonitrile. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1The structural schematic diagram of the phenylacetonitrile brine circulation treatment device provided by the embodiment of the present utility model;

[0022] Figure 2 The structural schematic diagram inside the separator of the separation unit provided by the embodiment of the present utility model;

[0023] Figure 3 For Figure 2 The partial enlarged structural schematic diagram at position A in

[0024] Explanation of reference numerals:

[0025] 1. Dehydrogenation and decarbonization unit; 11. Adjusting device; 12. Dehydrogenation and decarbonization tower; 13. Reboiler; 14. Product pump; 2. Purification unit; 21. Adsorption column; 22. Recovery liquid storage tank; 23. VOC on-line monitor; 3. Separation unit; 31. Separator; 32. Separation liquid storage tank; 33. Separation liquid circulation pump; 34. Temperature on-line monitor; 4. First absorption unit; 41. First absorber; 42. First absorption liquid storage tank; 43. First absorption liquid circulation pump; 44. First on-line density monitor; 5. Second absorption unit; 51. Second absorber; 52. Second absorption liquid storage tank; 53. Second absorption liquid circulation pump; 54. Second on-line density monitor; 6. Condensation unit; 61. Induced draft fan; 62. Condenser; 63. Condensate collection tank; 7. Storage unit; 71. Brine storage tank before treatment; 72. Hydrochloric acid storage tank; 73. Brine storage tank after treatment; 74. Sodium cyanide recovery storage tank; 75. Sodium carbonate storage tank; 8. Gas-liquid separator; 91. Tail gas deep treatment device; 92. Gas on-line analyzer; 10. Heat exchanger; 311. Separator gas outlet; 312. Spraying device; 313. Separation device; 314. Separator gas inlet; 315. Separator liquid outlet. Detailed implementation manners

[0026] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present utility model clearer, the present utility model will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present utility model and are not used to limit the present utility model.

[0027] In this application, terms such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual quantity, primary-secondary or sequential relationship between these entities or operations.

[0028] Please refer to Figure 1As shown in the figure, the benzonitrile brine circulation treatment device provided by the present utility model will be described. The benzonitrile brine circulation treatment device includes a cyanide and carbon dioxide removal unit 1, a purification unit 2, a separation unit 3, and a condensation unit 6 that are sequentially connected through pipelines. A first absorption unit 4 and a second absorption unit 5 are connected in parallel between the separation unit 3 and the condensation unit 6.

[0029] The purification unit 2 includes an adsorption column 21 and a recovered liquid storage tank 22; the bottom air inlet of the adsorption column 21 is communicated with the top air outlet of the cyanide and carbon dioxide removal unit 1; the recovered liquid storage tank 22 is communicated with the bottom liquid outlet of the adsorption column 21; the adsorption column 21 in the purification unit 2 is used to adsorb organic impurities such as benzonitrile, benzyl alcohol, and catalyst entrained in the cyanide and carbon-containing tail gas discharged from the top air outlet of the cyanide and carbon dioxide removal tower 12; the liquid in the adsorption column 21 is recovered into the recovered liquid storage tank 22 from the bottom liquid outlet. Among them, a VOC on-line monitor 23 is also provided at the top air outlet of the adsorption column 21 for real-time monitoring of the gas at the outlet of the purification unit 2. When the value of the VOC on-line monitor 23 reaches the set value, it indicates that the adsorption column 21 is saturated with adsorption, and the organic impurities are recovered by analyzing the saturated adsorption column 21.

[0030] Preferably, the inside of the adsorption column 21 is filled with 1.5 m 3 of non-polar resin, and the analysis medium is selected as high-temperature steam.

[0031] The separation unit 3 includes a separator 31, a separated liquid storage tank 32, and a separated liquid circulation pump 33. The separator air inlet 314 on the side of the separator 31 is communicated with the top air outlet of the adsorption column 21. The separated liquid storage tank 32 is communicated with the separator liquid outlet 315 at the bottom of the separator 31. The separated liquid circulation pump 33 is connected to the circulation pipeline between the separated liquid storage tank 32 and the separator 31; a heat exchanger 10 is provided on the circulation pipeline between the separated liquid storage tank 32 and the separator 31; the separated liquid in the separator 31 in the separation unit 3 absorbs HCN, and CO2 gas is insoluble in the separated liquid, so as to achieve the purpose of separating HCN and CO2. Then, the separated liquid is analyzed by circulating and heating the separated liquid through the heat exchanger 10 to separate HCN from the separated liquid. The HCN in the separator 31 enters the second absorber 51 through its top air outlet. Since there is still some HCN dissolved in the separated liquid and it cannot be separated completely at one time, the separated liquid enters the separated liquid storage tank 32, and is circulated back into the separator 31 from the top of the separator 31 through the bottom liquid outlet of the separated liquid storage tank 32 by the separated liquid circulation pump 33 for separation again. After multiple cycles of treatment, when the temperature monitored by the temperature on-line monitor 34 reaches 98 - 100 °C, it indicates that the HCN in the separator 31 is separated completely, and the obtained high-quality sodium cyanide solution can be directly used as a production raw material in the benzonitrile production process, thus realizing the recycling of resources.

[0032] Among them, the separation liquid stored in the separation liquid storage tank 32 is a sulfuric acid solution, the concentration of the sulfuric acid solution is 13-15%, the temperature of the outlet liquid of the heat exchanger 10 is controlled at 12-14°C, and the absorption end point of the separation liquid is CN ～ The content is 30-40%, and the temperature is controlled at 98-100°C during the analysis of the separation liquid.

[0033] The first absorption unit 4 includes a first absorber 41, a first absorption liquid storage tank 42 and a first absorption liquid circulation pump 43; the side air inlet of the first absorber 41 is communicated with the separator gas outlet 311 at the top of the separator 31, the first absorption liquid storage tank 42 is communicated with the bottom liquid outlet of the first absorber 41, and the first absorption liquid circulation pump 43 is connected to the circulation pipeline between the first absorption liquid storage tank 42 and the first absorber 41; the top gas outlet of the first absorber 41 is communicated with the condensation unit 6; the first absorber 41 is used to absorb the CO2 gas escaping from the separation unit 3. Similarly, the liquid recovered into the first absorption liquid storage tank 42 is circulated back into the first absorber 41 through the first absorption liquid circulation pump 43. After multiple repeated absorptions, the full utilization of resources is realized. After being monitored by the first on-line density monitor 44 and meeting the requirements, no further circulation treatment is carried out.

[0034] Among them, the absorption liquid selected in the first absorption liquid storage tank is a sodium hydroxide solution, the concentration of the sodium hydroxide solution is 32%, and the absorption temperature is controlled at 25-28°C.

[0035] The second absorption unit 5 includes a second absorber 51, a second absorption liquid storage tank 52 and a second absorption liquid circulation pump 53; the side air inlet of the second absorber 51 is communicated with the separator gas outlet 311 at the top of the separator 31, the second absorption liquid storage tank 52 is communicated with the bottom liquid outlet of the second absorber 51, and the second absorption liquid circulation pump 53 is connected to the circulation pipeline between the second absorption liquid storage tank 52 and the second absorber 51; the top gas outlet of the second absorber 51 is communicated with the condensation unit 6; the second absorber 51 is used to absorb the HCN gas escaping from the separation liquid analysis. Similarly, the absorption liquid recovered into the second absorption liquid storage tank 52 is circulated back into the second absorber 51 through the second absorption liquid circulation pump 53. After multiple repeated treatment absorptions, HCN is converted into a high-quality sodium cyanide solution, realizing the full utilization of resources, and can solve the problems of poor quality of the recovered sodium cyanide solution and inability to be recycled normally during the treatment of phenylacetonitrile brine, thereby realizing the recycling of resources and reducing the production cost of phenylacetonitrile. After being monitored by the second on-line density monitor 54 and meeting the requirements, no further circulation treatment is carried out. Through the secondary circulation treatment of HCN, the obtained high-quality sodium cyanide solution can be directly used as a production raw material in the phenylacetonitrile production process, thereby realizing the recycling of resources.

[0036] Preferably, the absorbent liquid selected in the second absorbent liquid storage tank is sodium hydroxide solution, the concentration of the sodium hydroxide solution is 32%, and the temperature of the liquid material is controlled at 40-45 °C.

[0037] The phenylacetonitrile brine circulation treatment device provided by the present utility model is provided with a separation unit 3. A separator 31 is arranged in the separation unit 3. Through the different solubilities of HCN and CO2 in the separation liquid in the separator 31, the gas separation of HCN and CO2 is realized, and then HCN is analyzed from the separation liquid by heating and analyzing the separation liquid through a heat exchanger 10; in the second absorption unit 5, HCN is converted into a high-quality sodium cyanide solution by the absorption of the absorbent liquid and directly used as a production raw material in the production process of phenylacetonitrile.

[0038] The phenylacetonitrile brine circulation treatment device provided by the present utility model has a simple treatment process, can solve the problems of poor quality of the recovered sodium cyanide solution and inability to be recycled normally in the process of phenylacetonitrile brine treatment, thereby realizing the recycling of resources and reducing the production cost of phenylacetonitrile.

[0039] As Figure 1 shown, the phenylacetonitrile brine circulation treatment device provided by the present utility model further includes a storage unit 7. The storage unit 7 includes a pre-treatment brine storage tank 71, a hydrochloric acid storage tank 72, a post-treatment brine storage tank 73, a recovered sodium cyanide storage tank 74 and a sodium carbonate storage tank 75; the pre-treatment brine storage tank 71 and the hydrochloric acid storage tank 72 are connected in parallel to the side inlet of the de-cyanation and de-carbonation unit 1; the post-treatment brine storage tank 73 is communicated with the outlet of the de-cyanation and de-carbonation unit 1; the sodium carbonate storage tank 75 is communicated with the circulation pipeline between the first absorbent liquid storage tank 42 and the first absorber 41; the recovered sodium cyanide storage tank 74 is communicated with the circulation pipeline between the second absorbent liquid storage tank 52 and the second absorber 51.

[0040] In some embodiments, as Figure 1 shown, the de-cyanation and de-carbonation unit 1 includes a regulating device 11, a de-cyanation and de-carbonation tower 12, a reboiler 13 and a withdrawal pump 14 connected in sequence; the feed inlet of the regulating device 11 is respectively communicated with the discharge outlets of the pre-treatment brine storage tank 71 and the hydrochloric acid storage tank 72, the discharge outlet of the regulating device 11 is communicated with the side inlet of the de-cyanation and de-carbonation tower 12, the top gas outlet of the de-cyanation and de-carbonation tower 12 is communicated with the bottom gas inlet of the adsorption column 21, and the bottom liquid outlet of the de-cyanation and de-carbonation tower 12 is communicated with the reboiler 13; the withdrawal pump 14 is communicated with the post-treatment brine storage tank 73.

[0041] The regulating device 11 therein adopts a static pipeline mixing device, and a liquid mixing channel is arranged inside, which can mix the discharges from the pre-treatment brine storage tank 71 and the hydrochloric acid storage tank 72 evenly in the regulating device 11 and improve the subsequent treatment effect of phenylacetonitrile brine.

[0042] An anti-cyanide and decarbonization tower 12 is successively provided with a demister, a first packing layer and a second packing layer from top to bottom. Among them, the feed inlet of the anti-cyanide and decarbonization tower 12 is located between the first packing layer and the second packing layer, and the feed liquid inlet and outlet of the reboiler 13 is located below the second packing layer and also at the bottom of the anti-cyanide and decarbonization tower 12.

[0043] Preferably, the anti-cyanide and decarbonization tower 12 adopts a stainless steel tower part with a size of Φ1600×10000mm. The demister at the top is made of stainless steel with a size of Φ1600×250mm and is of HP high-penetration type, which can efficiently prevent gas from entraining liquid into the purification unit 2. The first packing layer and the second packing layer adopt regular stainless steel packings with a packing height of 3000mm.

[0044] In some embodiments, as Figure 2 shown, a spraying device 312 and a separating device 313 are successively arranged in the separator 31 from top to bottom. The spraying device 312 is provided with nozzles and sprays the separating liquid from top to bottom. The spraying device 312 selects stainless steel solid nozzles with a nozzle model of 6SH and a spraying flow rate of 50m 3 / h.

[0045] The separating liquid storage tank 32 is provided with a heating device, including but not limited to heating methods such as jackets and coils.

[0046] In some embodiments, as Figure 2 and Figure 3 shown, the separating device 313 includes multiple layers of packing plate groups arranged in layers from top to bottom. Each layer of packing plate group includes multiple packing plate pieces arranged obliquely in the same direction. The packing plate pieces in the two adjacent packing plate groups above and below are inclined in different directions and are correspondingly connected one by one. The two adjacent packing plate pieces are arranged at an included angle. The separating device 313 is a stainless steel packing layer composed of stainless steel packing plate pieces with a packing diameter of Φ1500 - 2500mm, a packing height of 2000 - 3000mm, a packing plate piece thickness of 2 - 5mm, and an included angle a between adjacent packing plate pieces of 90°, so that the separating liquid can fully contact the cyanide- and carbon-containing tail gas, and the HCN gas can be completely absorbed.

[0047] In some embodiments, as Figure 1 shown, a temperature on-line monitor 34 is arranged on the circulation pipeline between the separating liquid storage tank 32 and the separator 31. The temperature on-line monitor 34 is arranged at the outlet end of the separating liquid circulation pump 33. And the temperature on-line monitor is electrically connected to the self-controlled valve for sampling on the separating liquid storage tank 32 through a controller to achieve automatic control.

[0048] In some embodiments, as Figure 1As shown, a first on-line density monitor 44 is installed on the circulation pipeline between the first absorption liquid storage tank 42 and the first absorber 41. The first on-line density monitor 44 is used to monitor the density of the first absorption liquid in real time; a second on-line density monitor 54 is installed on the circulation pipeline between the second absorption liquid storage tank 52 and the second absorber 51. The second on-line density monitor 54 is used to monitor the density of the second absorption liquid in real time.

[0049] Among them, the inlet valves of the separation liquid storage tank 32, the first absorption liquid storage tank 42, and the second absorption liquid storage tank 52 are electrically connected to their respective liquid level monitoring devices through a controller. And the first on-line density monitor 44 is electrically connected to the self-control extraction valve of the first absorption liquid storage tank 42 through the controller, and the second on-line density monitor 54 is electrically connected to the self-control extraction valve of the second absorption liquid storage tank 52 through the controller to achieve automatic control.

[0050] It should be noted that heat exchangers 10 are provided on the circulation pipelines of the separation unit 3, the first absorption unit 4, and the second absorption unit 5 in this application. The function of the heat exchangers 10 is to heat, which can be universal. Of course, according to the respective separation purposes, the heating temperature can be adjusted separately according to the separation or absorption purposes of each unit without affecting each other, and the reference numerals are not distinguished in the figure. Among them, a heat exchanger 10 is also provided on the pipeline between the adsorption column 21 and the recovered liquid storage tank 22. The function of the heat exchanger 10 is that the recovered liquid enters the recovered liquid storage tank 22 after being cooled, and the reference numerals are not distinguished either.

[0051] It should also be noted that in this application, each unit is connected by pipelines, and self-control valves are set on the connected pipelines as required, which is a conventional technical means in the art, so they are not shown or labeled in the figure.

[0052] In some embodiments, as Figure 1 shown, the condensation unit 6 includes an induced draft fan 61, a condenser 62, and a condensate collection tank 63. The air inlet of the induced draft fan 61 is respectively communicated with the top air outlets of the first absorber 41 and the second absorber 51. The air outlet of the induced draft fan 61 is communicated with the side air inlet of the condenser 62. The bottom discharge port of the condenser 62 is communicated with the feed port of the condensate collection tank 63. The cooling medium in the condenser 62 is cooled by circulating water, and the temperature of the air outlet of the condenser 62 is controlled at 30-40 °C.

[0053] In some embodiments, as Figure 1As shown in the figure, a tail gas deep treatment device 91 and a gas on-line analyzer 92 are arranged at the top gas outlet of the condenser 62. The non-condensable gas at the top gas outlet of the condenser 62 enters the tail gas deep treatment device 91. The tail gas deep treatment device 91 is filled with medium activated carbon to further adsorb and treat the non-condensable gas. After the gas is monitored and qualified by the gas on-line analyzer 92 at the outlet pipeline of the tail gas deep treatment device 91, it is discharged up to standard.

[0054] As Figure 1 shown in the figure, the phenylacetonitrile brine circulation treatment device provided by the present utility model further includes a gas-liquid separator 8 communicated between the first absorber 41, the second absorber 51 and the condensation unit 6. By arranging the gas-liquid separator 8, the small liquid droplets entrained in the tail gas escaping from the absorption unit are intercepted, the air inlet of the induced draft fan 61 is kept dry, and the induced draft fan 61 is prevented from being damaged.

[0055] As Figure 1 shown in the figure, the process of phenylacetonitrile brine circulation treatment using the phenylacetonitrile brine circulation treatment device provided by the present application is as follows:

[0056] Phenylacetonitrile brine enters the cyanide and carbon dioxide removal unit 1 at a feeding speed of 12 m 3 / h. After being adjusted by the adjusting device 11 to have a brine pH value between 2 and 3, it enters the cyanide and carbon dioxide removal tower 12. After being heated to 80 - 90 °C in the cyanide and carbon dioxide removal tower 12, gases such as HCN and CO2 in the brine escape. After passing through the adsorption column 21 of the purification unit 2, organic impurities such as phenylacetonitrile, benzyl alcohol, and catalyst entrained in the cyanide- and carbon-containing gas are adsorbed, and the cyanide- and carbon-containing tail gas enters the separation unit 3; a VOC on-line monitor 23 is installed on the pipeline at the top gas outlet of the purification unit 2 to monitor the gas after impurity removal in real time. When the concentration of the monitored organic impurities is higher than the set value, it indicates that the adsorption column 21 is saturated with adsorption, and the adsorption column 21 is desorbed. The recovered liquid enters the recovered liquid storage tank 22 after being cooled by the heat exchanger 10 between the adsorption column 21 and the recovered liquid storage tank 22; the cyanide- and carbon-containing gas enters the separation unit 3, and the HCN is absorbed by the absorption liquid in the separator 31, thereby realizing the separation of HCN and CO2; the separated CO2 gas enters the first absorption unit 4 for absorption. When the CN ～ content in the separated liquid is 30 - 40%, it indicates that the separated liquid is saturated with absorption, and the separated liquid storage tank 32 starts to be heated to desorb HCN. When heated to 70 °C, HCN gas starts to escape and enters the second absorption unit 5 for absorption. When heated to 98 - 100 °C, HCN gas completely escapes and the desorption is completed.

[0057] The tail gas absorbed by the first absorption unit 4 and the second absorption unit 5 enters the condensation unit 6 after passing through the gas-liquid separator 8. After the gas is condensed in the condensation unit 6, the condensate enters the condensate collection tank 63, and the non-condensable gas enters the tail gas deep treatment device 91 for further adsorption. After being monitored and qualified by the gas online analyzer 92 on the outlet pipeline of the tail gas deep treatment device 91, it is discharged up to the standard.

[0058] This application utilizes the principle that the solubilities of HCN and CO2 gases in the separation liquid are different under low-temperature conditions to separate HCN and CO2 in the cyanide- and carbon-containing gas. Then, HCN is desorbed from the separation liquid by heating and analyzing the separation liquid, and high-quality recovered sodium cyanide solution is obtained by absorbing with an alkaline solution. Furthermore, the sodium carbonate content in the recovered sodium cyanide solution is reduced. The recovered high-quality sodium cyanide solution can be directly applied to the production process of phenylacetonitrile, thereby realizing the recycling of resources and achieving the purpose of reducing the production cost of phenylacetonitrile.

[0059] The structures and working principles of the temperature online monitor 34, VOC online monitor 23, first online density monitor 44, second online density monitor 54, and gas online analyzer 92 involved in this application all belong to the prior art and can be fully realized by those skilled in the art without further elaboration. The content protected by this application also does not involve improvements to software and methods.

[0060] In the above embodiments, the descriptions of each embodiment have their own focuses. For the parts not detailed or recorded in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0061] 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, and improvements made within the spirit and principle of the present utility model shall be included within the protection scope of the present utility model.

Claims

1. A benzyl cyanide brine circulation treatment device, characterized in that, include: A decyanation and decarbonation unit (1), a purification unit (2), a separation unit (3) and a condensation unit (6) connected in sequence through pipelines, wherein a first absorption unit (4) and a second absorption unit (5) are connected in parallel between the separation unit (3) and the condensation unit (6); The purification unit (2) comprises an adsorption column (21) and a recovery liquid storage tank (22); the bottom air inlet of the adsorption column (21) is connected to the top air outlet of the decyanation and decarbonization unit (1); the recovery liquid storage tank (22) is connected to the bottom liquid outlet of the adsorption column (21); The separation unit (3) comprises a separator (31), a separation liquid storage tank (32) and a separation liquid circulation pump (33); a separator air inlet (314) on the side of the separator (31) is connected to a top air outlet of the adsorption column (21); the separation liquid storage tank (32) is connected to a separator liquid outlet (315) at the bottom of the separator (31); and the separation liquid circulation pump (33) is connected to a circulation pipeline between the separation liquid storage tank (32) and the separator (31); a heat exchanger (10) is provided on the circulation pipeline between the separation liquid storage tank (32) and the separator (31); The first absorption unit (4) comprises a first absorber (41), a first absorption liquid storage tank (42) and a first absorption liquid circulation pump (43); the side air inlet of the first absorber (41) is connected to the separator air outlet (311) at the top of the separator (31), the first absorption liquid storage tank (42) is connected to the bottom liquid outlet of the first absorber (41), and the first absorption liquid circulation pump (43) is connected to the circulation pipeline between the first absorption liquid storage tank (42) and the first absorber (41); the top air outlet of the first absorber (41) is connected to the condensing unit (6); The second absorption unit (5) comprises a second absorber (51), a second absorption liquid storage tank (52) and a second absorption liquid circulation pump (53); the side air inlet of the second absorber (51) is connected to the separator air outlet (311) at the top of the separator (31), the second absorption liquid storage tank (52) is connected to the bottom liquid outlet of the second absorber (51), and the second absorption liquid circulation pump (53) is connected to the circulation pipeline between the second absorption liquid storage tank (52) and the second absorber (51); the top air outlet of the second absorber (51) is connected to the condensing unit (6).

2. The benzyl cyanide brine circulation treatment device according to claim 1, characterized in that: The invention also comprises a storage unit (7), wherein the storage unit (7) comprises a pre-treatment salt water storage tank (71), a hydrochloric acid storage tank (72), a post-treatment salt water storage tank (73), a sodium cyanide recovery storage tank (74) and a sodium carbonate storage tank (75); the pre-treatment salt water storage tank (71) and the hydrochloric acid storage tank (72) are connected in parallel to the side liquid inlet of the decyanation and decarbonation unit (1); the post-treatment salt water storage tank (73) is connected to the liquid outlet of the decyanation and decarbonation unit (1); the sodium carbonate storage tank (75) is connected to the circulation pipeline between the first absorption liquid storage tank (42) and the first absorber (41); and the sodium cyanide recovery storage tank (74) is connected to the circulation pipeline between the second absorption liquid storage tank (52) and the second absorber (51).

3. The benzyl cyanide brine circulation treatment device according to claim 2, characterized in that: The decyanation and decarbonation unit (1) comprises a regulating device (11), a decyanation and decarbonation tower (12), a reboiler (13) and an extraction pump (14) which are connected in sequence; the feed port of the regulating device (11) is respectively connected to the discharge ports of the pre-treated brine storage tank (71) and the hydrochloric acid storage tank (72); the discharge port of the regulating device (11) is connected to the side liquid inlet of the decyanation and decarbonation tower (12); the top air outlet of the decyanation and decarbonation tower (12) is connected to the bottom air inlet of the adsorption column (21); the bottom liquid outlet of the decyanation and decarbonation tower (12) is connected to the reboiler (13); and the extraction pump (14) is connected to the treated brine storage tank (73).

4. The benzyl cyanide brine circulation treatment device according to claim 1, characterized in that: The separator (31) is provided with a spray device (312) and a separation device (313) from top to bottom.

5. The benzyl cyanide brine circulation treatment device according to claim 4, characterized in that: The separation device (313) comprises a plurality of filler plate groups arranged in layers from top to bottom, each layer of the filler plate group comprises a plurality of filler plate sheets arranged obliquely in the same direction, the filler plate sheets in two adjacent groups of filler plate groups are inclined in different directions and connected one by one, and the two connected filler plate sheets are arranged at an angle.

6. The benzyl cyanide brine circulation treatment device according to claim 1, characterized in that: An online temperature monitor (34) is provided on the circulation pipeline between the separation liquid storage tank (32) and the separator (31), and the online temperature monitor (34) is provided at the outlet end of the separation liquid circulation pump (33).

7. The benzyl cyanide brine circulation treatment device according to claim 1, characterized in that: A first online density monitor (44) is installed on the circulation pipeline between the first absorption liquid storage tank (42) and the first absorber (41); and a second online density monitor (54) is installed on the circulation pipeline between the second absorption liquid storage tank (52) and the second absorber (51).

8. The benzyl cyanide brine circulation treatment device according to claim 1, characterized in that: The condensing unit (6) comprises an induced draft fan (61), a condenser (62) and a condensate collecting tank (63); an air inlet of the induced draft fan (61) is respectively connected to the top air outlets of the first absorber (41) and the second absorber (51); an air outlet of the induced draft fan (61) is connected to the side air inlet of the condenser (62); and a bottom outlet of the condenser (62) is connected to the feed inlet of the condensate collecting tank (63).

9. The benzyl cyanide brine circulation treatment device according to claim 8, characterized in that: The top gas outlet of the condenser (62) is provided with a tail gas deep processing device (91) and a gas online analyzer (92).

10. The benzyl cyanide brine circulation treatment device according to claim 1, characterized in that: It also includes a gas-liquid separator (8) connected between the first absorber (41), the second absorber (51) and the condensing unit (6).

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