CN114804484B - Coking wastewater crystallization separation device and process - Google Patents

Abstract

The invention relates to a coking wastewater crystallization separation device, which at least comprises a crystallization component (4) capable of respectively crystallizing at least two separated coking wastewater components, wherein filtrate and trapped fluid separated in the separation component (3) respectively enter different evaporation crystallization channels of the crystallization component (4) selectively, so that the salt evaporation crystallization treatment of the filtrate and the trapped fluid is respectively completed through different evaporation procedures, the crystallization component (4) is further provided with a preheating unit (5) capable of sequentially preheating the separated filtrate and the trapped fluid, and the preheating unit (5) is coated on a liquid flow branch (43) of the crystallization component (4), so that the preheating unit (5) can finish the preheating treatment of the filtrate and the trapped fluid in the same period and orderly. In addition, the invention also relates to a coking wastewater crystallization separation process.

Description

Coking wastewater crystallization separation device and process

Technical Field

The invention relates to the technical field of coking wastewater treatment devices, in particular to a coking wastewater crystallization separation device and a coking wastewater crystallization separation process.

Background

A large amount of coking wastewater is generated in the coke production process. Coking wastewater generally contains ammonia, cyanide, thiocyanate, phenols and other organic matters. Since the coke production process involves a plurality of working procedures, and the coking production flow of each coking plant has differences, the concentration of main pollutants in the coking wastewater changes within a certain interval, but the characteristics of the coking wastewater are approximately the same, the following points can be summarized: (1) coking wastewater exhibits a composite toxic effect; (2) The concentration of pollutants is high, the content energy is high, and the degradability is poor; (3) The coking wastewater has complex components and coexists multiphase multi-element species; (4) high C/N ratio, rich nitrogen and deficient phosphorus; (5) high salinity and high chromaticity. Currently, enterprises generally adopt coupling processes of pretreatment, biological treatment and advanced treatment to treat coking wastewater. In order to meet the 'zero emission' requirement of the coal chemical industry, the desalting process also becomes an indispensable link in the coking wastewater treatment process.

The crystalline salt is used as a product of recycling at the tail end of coking wastewater treatment, and whether the production process and the purity of the generated industrial salt meet the requirements becomes a tripping stone for the zero emission requirement of the coking wastewater treatment is a problem which needs to be solved in related industries.

Patent document with publication number of CN109809592A discloses a salt separation recycling method of coking wastewater nanofiltration concentrated solution, the crystallization mode of the patent still belongs to a traditional classified crystallization method, the crystallization treatment of different components is required to be independently carried out, the crystallization time is long, the energy consumption is high, and the heat dissipated by an evaporation crystallization device in the working process cannot be reused.

Aiming at the defect that evaporation crystallization treatment of various coking wastewater components cannot be simultaneously realized in the prior art, and particularly the problems that the consumption of heat energy is overlarge and the actual utilization rate is low in the existing evaporation crystallization step, the application provides a separation device capable of improving the use efficiency of the evaporation crystallization treatment process on the heat energy and reducing the time consumed by the evaporation crystallization process in a preheating mode.

Furthermore, there are differences in one aspect due to understanding to those skilled in the art; on the other hand, as the inventors studied numerous documents and patents while the present invention was made, the text is not limited to details and contents of all that are listed, but it is by no means the present invention does not have these prior art features, the present invention has all the prior art features, and the applicant remains in the background art to which the rights of the related prior art are added.

Disclosure of Invention

Aiming at the defects of the prior art, the technical scheme of the invention provides a coking wastewater crystallization separation device which at least comprises a crystallization component capable of respectively crystallizing at least two separated coking wastewater components, wherein filtrate and trapped fluid separated from coking wastewater in the separation component respectively enter different evaporation crystallization channels of the crystallization component, so that salt evaporation crystallization treatment of the filtrate and the trapped fluid is respectively completed through different evaporation procedures, wherein a preheating unit capable of preheating the separated filtrate and the trapped fluid in sequence is further arranged on the crystallization component, and the preheating unit is coated on a liquid flow branch of the crystallization component, so that the preheating unit can complete preheating treatment of the filtrate and the trapped fluid in a synchronous and orderly manner. The preheating unit can preheat the filtrate and the trapped fluid after the separation of the separation component, particularly the two-effect evaporation crystallization treatment adopted when the filtrate is subjected to evaporation crystallization treatment and the three-effect evaporation crystallization treatment adopted when the trapped fluid is subjected to evaporation crystallization treatment are different, and the preheating unit firstly preheats the filtrate by utilizing high-temperature steam and then preheats the trapped fluid by utilizing exhaust steam generated by the high-temperature steam in exothermic reaction. The triple effect evaporation crystallization treatment can provide more heat energy for the trapped fluid, so that the trapped fluid can achieve the required preheating effect by adopting dead steam heating relative to the filtered fluid needing the double effect evaporation crystallization treatment, and particularly, the heat required to be consumed by materials in the evaporation crystallization process due to temperature rise can be reduced by the arrangement of the preheating treatment. In addition, the crystallization component can utilize the heat that its self loss to carry out the secondary heating to the liquid after the condensation in the preheating unit when carrying out evaporation crystallization to filtrate and trapped fluid, and convenient evaporation unit can change the liquid after the heating into high temperature steam fast.

According to a preferred embodiment, the preheating unit comprises at least a preheating coil capable of being coiled around the outside of the tube wall of the first flow branch for transporting the filtrate and a spent heating coil coiled around the outside of the tube wall of the second flow branch for transporting the retentate.

According to a preferred embodiment, the preheating coil and the spent heating coil are connected in a manner that forms an upstream and downstream conduit in communication with each other such that the high temperature steam flowing through the preheating coil heats the first flow leg and then flows along the conduit into the spent heating coil to heat the second flow leg.

According to a preferred embodiment, the first liquid flow branch communicates its downstream pipe outlet with the first crystallization assembly in such a way that the preheated filtrate in its pipe is conveyed to the crystallization treatment structure, so that the preheated filtrate can be evaporated and crystallized in the first crystallization assembly.

According to a preferred embodiment, the trapped fluid in the second liquid flow branch can be directionally conveyed to the second crystallization component after being preheated by the dead steam, and the second crystallization component carries out evaporation crystallization treatment on the trapped fluid after being preheated.

According to a preferred embodiment, the exhaust steam generated by exothermic reaction of the heating steam flowing in the preheating coil can flow into the exhaust heating coil; the gas-liquid mixture generated after the trapped fluid in the second liquid flow branch is heated by the heat released by the exhaust steam directionally flowing in the exhaust heating coil can be conveyed to the condensing unit. According to a preferred embodiment, the liquid produced by the condensing unit can be returned to the evaporating unit; the liquid produced by the condensing unit can flow back to the evaporating unit; the high-temperature steam generated by the evaporation unit can directionally flow into the preheating coil, the evaporation unit at least comprises a first heating unit which is arranged outside the first crystallization component and the second crystallization component in a cladding mode, and the first heating unit can absorb heat dissipated by the first crystallization component and the second crystallization component in the evaporation crystallization treatment process to heat liquid.

According to a preferred embodiment, the evaporation unit further comprises a second evaporation unit capable of evaporating the heated liquid, said second evaporation unit being in communication with the preheating coil.

According to a preferred embodiment, the output ends of the first and second crystallization modules are further connected with a separation module capable of separating the crystallization salt from the residual mother liquor and a salt leg for storing the crystallization salt.

The application also provides a coking wastewater crystallization salt separation process, which at least comprises the following steps:

the impurities in the coking wastewater are filtered in a pretreatment filtering mode;

carrying out water reduction treatment on the coking wastewater subjected to impurity filtration;

separating sodium sulfate concentrated water and sodium chloride concentrated water in the coking wastewater;

evaporating and crystallizing the separated sodium sulfate concentrated water and sodium chloride concentrated water by utilizing a salt extraction evaporation crystallization device to obtain crystalline salt;

and (3) placing the residual mother liquor after evaporation and crystallization into a mixed salt crystallization device to produce mixed salt, and re-dissolving and re-conveying the obtained mixed salt to a circulating nanofiltration device to continue salt separation treatment.

Drawings

FIG. 1 is a schematic flow chart of a preferred coking wastewater crystallization separation device according to the present invention;

FIG. 2 is a schematic structural view of a preferred coking wastewater crystallization separation device according to the present invention;

FIG. 3 is a schematic structural view of a separation assembly of a preferred coking wastewater crystallization separation device according to the present invention;

FIG. 4 is a schematic side view of a flow filtering plate of a preferred coking wastewater crystallization separator according to the present invention;

FIG. 5 is a schematic plan view of a flow filtering plate of a preferred coking wastewater crystallization separator according to the present invention.

List of reference numerals

1: a filter assembly; 2: a concentration unit; 3: a separation assembly; 4: a crystallization assembly; 5: a preheating unit; 6: a separation assembly; 7: salt legs; 11: a filter box; 12: a liquid inlet pipe; 13: a liquid outlet pipe; 111: a flow filtering plate; 112: a precipitation step groove; 113: an interception module; 114: opening holes; 115: an adsorption unit; 116: an isolation layer; 21: a medium pressure membrane concentration unit; 22: a high pressure membrane concentration unit; 31: an outer sleeve; 32: separating and filtering the structure; 33: a support structure; 321: a mixed flow structure; 322: a sub-runner; 323: a microchannel; 41: a first crystallization component; 42: a second crystallization component; 43: a liquid flow branch; 431: a first fluid flow branch; 432: a second fluid flow branch; 51: preheating the coil; 52: a spent heating coil; 53: a condensing unit; 54: an evaporation unit; 541: a first heating unit; 542: and a second vaporizing unit.

Detailed Description

The following detailed description refers to the accompanying drawings.

Example 1

The application provides a coking wastewater crystallization separation device, which can comprise a filtering component 1, a concentration unit 2, a separation component 3, a crystallization component 4 and a preheating unit 5.

According to a specific embodiment, the filter assembly 1 receives coking wastewater generated in an industrial production process, and after the coking wastewater is subjected to hardness removal and filtration treatment, the treated coking wastewater is conveyed to the concentration unit 2 to be subjected to dewatering concentration treatment so as to increase the proportion of salt-containing substances (sodium chloride and sodium sulfate) in the coking wastewater, and the concentrated coking wastewater is subjected to separation treatment of sodium chloride and sodium sulfate components in the coking wastewater in the separation assembly 3. The output end of the separation assembly 3 is also connected with a crystallization assembly 4 which can carry out evaporative crystallization on the separated filtrate and trapped fluid with single components. The crystallization unit 4 is provided with a preheating unit 5 on a liquid delivery line for preheating the filtrate and the retentate separated by the separation unit 3, respectively. The preheating unit 5 is also capable of absorbing the heat dissipated by the crystallization assembly 4 during the evaporative crystallization process. The preheating unit 5 is able to increase the temperature of the filtrate and retentate flowing into the evaporative crystallisation apparatus of the crystallisation assembly 4 by heating the different liquid flow branches 43 of the crystallisation assembly 4. The preheating unit 5 can selectively perform the liquid preheating treatment with steam at different temperatures according to the difference in the evaporation and crystallization treatment process performed in the crystallization unit 4 for the filtrate and retentate separated from the coking wastewater. The preheating unit 5 can carry out secondary liquefaction and vaporization treatment on the steam-water mixture generated after heat release, thereby realizing the cyclic heat absorbing and releasing work of the preheating unit 5.

As shown in fig. 1, the crystallization unit 4 includes a first crystallization unit 41 and a second crystallization unit 42 capable of performing different evaporative crystallization operations on the filtrate and retentate after separation of the coking wastewater, respectively. The crystallization module 4 further comprises a flow branch 43 capable of communicating the different outputs of the separation module 3 with the first crystallization module 41 and the second crystallization module 42, respectively. Specifically, the first liquid flow branch 431 is capable of communicating the filtrate output of the separation module 3 with the first crystallization module 41; the second liquid flow branch 432 is capable of communicating the retentate output of the separation module 3 with the second crystallization module 42. Preferably, the preheating unit 5 performs the preheating treatment of the filtrate flowing through the first flow branch 431 and the retentate flowing through the second flow branch 432, respectively, in such a manner that the first flow branch 431 and the second flow branch 432 can be heated by the flowing high-temperature steam.

As shown in fig. 1, the preheating unit 5 includes a preheating coil 51 coiled around a portion of the outer wall of the conduit of the first flow leg 431 and a spent heating coil 52 coiled around a portion of the outer wall of the conduit of the second flow leg 432. Preferably, the high temperature steam directed in the pre-heating coil 51 is capable of exothermically transferring heat to a portion of the lumen of the first flow leg 431 that is surrounded thereby, thereby increasing the temperature of the filtrate flowing through the first flow leg 431. A spent heating coil 52 is also preferably connected downstream of the pre-heating coil 51. After the high-temperature steam completes one heat release, the heat content of the high-temperature steam is reduced, and the exhaust steam generated by the exothermic reaction is conveyed to a downstream pipeline, and the exhaust steam can generate a gas-liquid mixture mainly containing liquid after further heat release in the exhaust heating coil 52. Preferably, the exhaust steam is exothermic in a manner that transfers heat within the lumen of the second flow leg 432 in the exhaust heating coil 52. Preferably, the exposed outer tube walls of the preheating coil 51 and the spent heating coil 52 are wrapped by heat insulation materials, and the part of the tube walls of the preheating coil 51 and the spent heating coil 52, which are close to the first liquid flow branch 431 and the second liquid flow branch 432, are made of materials which are easy to transfer heat, so that heat released by steam and exhaust steam in exothermic reaction can be conducted directionally.

Preferably, the vapor-liquid mixture produced by the directionally flowing exhaust steam in the exhaust heating coil 52 after the heat release heats the retentate in the second liquid flow leg 432 can be delivered to the condensing unit 53. Through carrying out condensation liquefaction to the gas-liquid mixture that the exhaust steam produced after exothermic for preheat steam finally can flow back to evaporation unit 54 after exothermic liquefaction, thereby evaporation unit 54 can carry out evaporation treatment to liquid again, the setting of condensation unit 53 has prevented that evaporation unit 54 from directly carrying out the secondary heating evaporation to the gas-liquid mixture that the exhaust steam produced after exothermic, avoided the gas-liquid mixture can't absorb the heat that evaporation unit 54's heating structure produced effectively in evaporation unit 54, cause heating structure to appear unusual operating condition such as dry combustion method and reduced self life. In the process of generating high-temperature steam by cyclic heating, the generation of steam is the process of vaporizing liquid, if the substance to be heated is vaporized, the heat generated or transferred by the heating structure can not be fully transferred, and the phenomenon easily causes damage to the heating structure due to the fact that the heating structure is at an excessive temperature for a long time, so that better heat transfer effect can be obtained by filling the liquid to be heated in the heating space of the heating structure, and damage to the heating structure due to overheat reaction is avoided. Preferably, the liquid produced by the condensing unit 53 can be refluxed to the evaporating unit 54;

The high temperature steam generated by the evaporation unit 54 can be directed into the preheating coil 51. The evaporation unit 54 includes a first heating unit 541 that surrounds the first and second crystallization assemblies 41 and 42, and a second evaporation unit 542 that evaporates the heated liquid. The second vaporization unit 542 communicates with the pre-heating coil 51. The first heating unit 541 is capable of heating the liquid by absorbing heat dissipated by the first and second crystallization assemblies 41, 42 during the salt vapor crystallization process. This reduces the energy consumption of the evaporation unit 54 when it generates steam, and at the same time, it also can recycle the heat which is not fully utilized in the evaporation and crystallization process and dissipated outwards, thus reducing the energy consumption of the whole device and improving the crystalline salt output efficiency of the device.

The downstream line outlet of the first flow branch 431 communicates with the first crystallization assembly 41 so that the preheated filtrate can be rapidly crystallized in the first crystallization assembly 41. By directly introducing the preheated filtrate into the first crystallization component 41 for the second-effect crystallization treatment, the amount of steam consumed by heating the filtrate in the first crystallization component 41 is greatly shortened, the production speed of the crystallized salt is accelerated, meanwhile, the whole temperature of the filtrate can be ensured by the preheating treatment, the quality and the particle size uniformity of the crystallized salt are improved, and the number of fine crystals generated by the filtrate due to uneven heating is reduced. The retentate in the second flow branch 432 can be directed to the second crystallization assembly 42 after the dead steam preheating treatment, and the second crystallization assembly 42 performs the evaporative crystallization treatment on the preheated retentate. Preferably, the first crystallization assembly 41 is capable of subjecting the separated concentrated water containing sodium chloride to the following treatments: concentrating by MVR, feeding into a salt double-effect evaporation crystallizer, discharging salt at the low temperature section of the evaporation crystallizer, thickening by a thickener, dewatering by a centrifuge, feeding into a dryer, and conveying the dried finished sodium chloride to a product packaging line. Preferably, the second crystallization assembly 42 is capable of treating the separated concentrated water containing sodium sulfate by: concentrating by MVR, feeding into a nitrate countercurrent triple-effect evaporation crystallizer, discharging nitrate at the high temperature section of the evaporation crystallizer, thickening by a thickener, dewatering by a centrifugal machine, feeding into a dryer, and conveying the dried finished sodium sulfate to a product packaging line. Preferably, the output ends of the first crystallization assembly 41 and the second crystallization assembly 42 are further connected with a separation assembly 6 capable of separating the crystallization salt from the residual mother liquor and a salt leg 7 for storing the crystallization salt. Preferably, the residual mother liquor separated by the separation component 6 can enter a two-effect salt mixing crystallizer for salt mixing crystallization treatment, and the produced salt mixing crystals enter a first-stage nanofiltration device for salt separation treatment after being dissolved back. Preferably, the separation module 6 may employ a separation sieve capable of separating the crystallized salt from the mother liquor. Preferably, the salt leg 7 is also communicated with a back flushing pump capable of back flushing the inner chamber of the salt leg, and the back flushing pump pumps diluted stock solution or gas into the salt leg through a back flushing port, so that fine crystals in the salt leg float again and enter a crystal growth area, and qualified large particles fall on the bottom of the salt leg 7, thereby ensuring the crystallization quality and particle size uniformity of the product. Meanwhile, the stock solution or gas filled into the salt legs 7 can wash the product once, and the crystals adhered to the inner walls of the salt legs are washed, so that the internal blocking phenomenon is reduced.

Example 2

In the industrial coke production process, a large amount of coking wastewater is often generated, and the coking wastewater generally contains a large amount of ammonia, cyanide, thiocyanate, phenols and other organic matters and is characterized by complex toxic effect, high pollutant concentration, high content energy, poor degradability, complex components and the like, so that the coking wastewater is generally treated by adopting a coupling process of pretreatment, biological treatment and advanced treatment in order to meet the 'zero emission' requirement of the chemical industry, wherein the desalination treatment of the coking wastewater is an essential link in the coking wastewater treatment process. Although the existing coking wastewater treatment process can effectively control the output of pollutants in each link in the whole coking wastewater treatment process, the formation mechanism of the final crystalline salt is not clear, the components of the crystalline salt in the prior art are relatively mixed, and the crystalline salt with the purity meeting the industrial salt requirement cannot be directly produced, so that the application aims at the defects of the prior art, the component separation treatment is carried out on the industrial salt solution mixed by sodium chloride and sodium sulfate after solid phase substances such as tar and sludge are removed from the coking wastewater, and the sodium chloride and sodium sulfate in the industrial salt solution in a mixed state can be rapidly and fully separated, and the crystalline salt product reaching the purity standard of the industrial salt can be directly output after the salt solution with different components is subjected to evaporation crystallization treatment by utilizing different evaporation crystallization processes.

As shown in fig. 2, an axially upper end face of the filter housing 11 of the filter assembly 1 is communicated with a liquid inlet pipe 12 which can inject coking wastewater to be treated into the filter housing 11. The axial lower end of the filter box 11 is connected with a liquid outlet pipe 13. The liquid outlet pipe 13 is communicated with a concentration unit 2 which can concentrate the pretreated coking wastewater. The filter box 11 divides its chamber into at least three communicating filter areas by providing different filter structures inside. Further preferably, the three filtering areas which are mutually communicated and orderly arranged are respectively a slow flow section, a filtering section and an output section. The slow flow section can perform coarse filtration and buffer diversion treatment on the coking wastewater flowing in from the top end of the filter box 11, so that the coking wastewater can uniformly and dispersedly flow into the filter section. Preferably, the flow-retarding sections are provided with flow-filtering plates 111 staggered on two opposite side walls of the inner cavity thereof in a spaced-apart arrangement along the axis of the chamber thereof. The filter plate 111 is obliquely attached to the chamber wall, and the filter plate 111 can be selectively pulled out of the chamber, so that the filter plate 111 with a certain amount of impurities intercepted therein is taken out of the chamber for removing the precipitated impurities. Preferably, the sum of the plate areas of the adjacent two filter plates 111 is larger than the area of the cross section of the filter housing 11.

As shown in fig. 4 and 5, the flow filtering plate 111 is provided with a multistage progressive precipitation step groove 112 on the plate surface thereof so as to be capable of precipitating and separating precipitable impurities. Preferably, the plurality of strip-shaped plate surfaces of the filtering plates 111 separated by the settling step grooves 112 are further provided with interception modules 113 at intervals, which can intercept flocculent sundries. Further preferably, the interception module 113 includes an interception net vertically supported on the plate surface of the flow filtering plate 111 and an interception post provided at a side of the interception net away from the flow filtering plate 111. Preferably, the plurality of interception modules 113 and the precipitation step grooves 112 are alternately arranged, so that a stepped multiple impurity interception structure is formed on the flow filtering plate 111, the interception efficiency of the non-precipitated impurities is improved, meanwhile, the total interception amount of the impurities of the single flow filtering plate 111 can be improved, the rough filtration performance of the flow filtering plate 111 is improved to a certain extent, and the requirement of a large amount of industrial coking wastewater treatment on long-time sustainable use of the device is met. The settling step groove 112 can prevent the coking wastewater from flowing through the filtering flow plate 111 in a stable and direct state because the settling step groove 112 arranged on the plate surface prevents the coking wastewater from flowing through the filtering flow plate 111. As the water stream passes through the trough body of the precipitation step trough 112, the precipitable impurities in the coking wastewater stream can gradually sink from the water stream to precipitate on the surface of the flow filtering plate 111, and the precipitable impurities can fall into the precipitation step trough 112, so that while the water stream continues downstream movement, the precipitable impurities are intercepted by the precipitation step trough 112 and accumulated in the trough body, thereby realizing separation of the precipitable impurities from the coking wastewater. Preferably, a plurality of settling step tanks 112 for intercepting and accommodating the subsideable impurities, which are spaced apart in the water flow direction, can accomplish the filtration of the impurities of different volumes and masses in a stepwise filtration manner. Particularly, the interception module 113 matched with the precipitation step groove 112 can enable impurities in coking wastewater to complete solid-liquid separation in a multiple filtration mode by gradually reducing the mesh size of an interception net.

Preferably, the cross-sectional area of the settling step groove 112 on the single filtering plate 111 is gradually reduced along the flow direction of the water flow, so that the settling step groove 112 located at the upstream position can filter out more precipitable impurities from the water flow with more impurities, and achieve effective accommodation of the impurities. Preferably, the settling step groove 112 of the downstream region of the same flow filtering plate 111 is provided with a smaller cross-sectional area so that the influence of the groove body on the water flow is reduced when the water flow passes through the position, the flow velocity of the water flow is reduced so that the water flow can flow through the region at a relatively slow velocity so that impurities which are advanced by the water flow without settling upstream and/or which are intercepted can be separated and settled in the relatively gentle water flow, thereby settling in the downstream settling step groove 112.

Preferably, the cross-sectional area of the tank body of the settling step tank 112 may be set to be arc-shaped, and the arc-shaped radian can be adjusted according to the difference of the positions of the settling step tank 112 on the filtering plate 111, so that the arc-shaped radian of the tank body section of the settling step tank 112 located in the water flow upstream area is larger than the arc-shaped radian of the tank body section of the downstream area, and thus the upstream tank body can accommodate more settling impurities with larger volume. Preferably, the precipitation step slot 112 is selectively opened in such a manner that its arc mandrel is located inside or outside the slot. For example, the settling step groove 112 in the upstream area of the water flow is opened in such a way that the arc mandrel a is positioned above the groove cavity, and the curved surface radian formed by the groove cavity is smaller, so that the settling step groove 112 in the position does not have a larger influence on the flow velocity of the water flow, and the water flow passes through the upstream area at a relatively higher speed under the action of gravity, so that the settling step groove 112 in the upstream area does not have a larger resistance to the water flow, and the settling step groove 112 in the area mainly provides a containing space for the precipitable impurities with a larger volume; the precipitation step groove 112 positioned in the downstream area of the water flow is formed in a mode that the arc mandrel B is positioned in the groove cavity, and the precipitation step groove 112 in the downstream area is formed in a mode that the arc of the grooved section of the precipitation step groove and the plate body of the flow filtering plate 111 form a certain inclined included angle, so that impurities driven by the water flow to be flushed into the precipitation step groove 112 can be effectively intercepted by the arc-shaped groove, and the kinetic energy carried by the impurities is counteracted, so that the impurities are captured by the arc-shaped groove body.

Preferably, the plurality of precipitation step grooves 112 are transversely arranged in a manner that the curvature of the precipitation step grooves gradually increases along the water flow direction, so that the precipitation step grooves 112 which are positioned on the same filtering flow module and belong to the downstream area of the water flow can resist the power of the water flow with a larger curvature groove wall, the flow speed of the water flow is effectively slowed down, fine and low-weight impurities carried by the water flow can be precipitated in the precipitation step grooves 112 of the downstream area, and the coking wastewater with higher purity is obtained.

Preferably, the interception module 113 provided on the plate surface of the filtering plate 111 is capable of separating impurities in the focusing wastewater flow in cooperation with the settling step groove 112. Specifically, the interception module 113 can intercept floating impurities such as non-precipitated floccules, thereby further improving the purity of the coking wastewater. Preferably, the interception module 113 is combined with the plurality of precipitation step grooves 112, that is, one interception module 113 is disposed at a downstream position of each precipitation step groove 112, that is, one interception module 113 is supported on the plate surface of the flow filtering plate 111 between two adjacent precipitation step grooves 112. Preferably, the interception net of the interception module 113 is capable of intercepting floating impurities not settled in the settling step groove 112 upstream thereof. As the water permeability of the interception module 113 gradually decreases due to the gradual accumulation of impurities, the upstream water level of the interception module 113 gradually rises, and the interception module 113 is further connected with an interception column capable of intercepting large-volume flocculent impurities floating in water flow on an interception net. Preferably, the interception posts are spaced at the upper edge of the interception net so that when the water level reaches a certain height, the interception module 113 improves the passing efficiency of the water flow by intercepting only a part of the large-volume floc. Preferably, the water flow impurities which are not filtered by the interception module 113 of the upstream area are filtered for two or more times by the interception module 113 of the downstream area, so that the purity of the coking wastewater is gradually improved. Preferably, the size of the mesh gap of the interception net of the interception module 113 on the same filtering flow plate 111 is gradually reduced according to the position of the interception module, so that the filtering of impurities with different sizes is realized in a step-by-step filtering mode. Preferably, the interception net of the interception module 113 can intercept the impurities which can not be precipitated in the precipitation step groove 112 in a floating state, and can intercept the impurities which can be carried forward by the water flow according to the size of the impurities, thereby further intercepting the impurities which are missed by the precipitation step groove 112.

Preferably, the flow filtering plates 111 of the slow flow section of the filtering box 11 are arranged at intervals along the axis of the chamber at intervals, and are fixed on the chamber wall of the slow flow section of the filtering box 11 in a mode of inclined flow guiding of the plate bodies of the flow filtering plates 111, and coking wastewater after filtering treatment on the flow filtering plate 111 of the upper stage can fall on the flow filtering plate 111 of the lower stage just after being separated from the plate bodies, so that secondary flow filtering treatment is completed on the flow filtering plate 111 of the lower stage. Preferably, the plurality of filtering plates 111 are manually disassembled according to the use period, the filtering amount and the like thereof, so as to clean the impurities intercepted by the filtering plates. Preferably, the wall of the filtering box 11 is provided with a plurality of openings 114 into which the filtering plates 111 can be inserted and fixed.

Preferably, a filtering section is further provided downstream of the slow flow section of the filtering box 11. Preferably, an adsorption unit 115 capable of further adsorbing and removing fine impurities in the coking wastewater is provided in the filtering section of the filtering tank 11. Preferably, the adsorption unit 115 may select fine coke powder generated after coking, so that the coking wastewater after pretreatment and filtration is passed through the slow infiltration adsorption unit 115 and discharged from the axial lower end of the filtration section to complete the removal of fine impurities in the coking wastewater. Preferably, fine coke powder generated after coking has a very strong adsorption capacity because moisture and volatile organic compounds therein are discharged through pyrolysis, so that a large-area porous structure is formed inside the fine coke powder, and if the fine coke powder can be used for adsorbing and purifying coking wastewater, the coking wastewater treatment efficiency is greatly improved. Preferably, the axial lower end of the filter segment is provided with an isolating layer 116 capable of supporting the adsorption unit 115. The isolation layer 116 can define the location of the adsorption unit 115 and ensures that the coked wastewater after the completion of impurity adsorption can flow through the isolation layer 116 to the output section. Preferably, the isolation layer 116 may be a filter screen made of a plurality of fine gauze layers, which enables the coking wastewater to flow through the isolation layer 116, but the adsorption unit 115 composed of fine coke powder does not fall into the output section of the filter housing 11.

Preferably, the adsorption unit 115 may be divided into two adsorption units by a partition plate, so that the adsorption units located axially below the filter plate 111 are changed by rotating the adsorption unit 115, thereby facilitating the replacement of the adsorption unit 115 by a worker and ensuring the continuous adsorption capacity of the adsorption unit 115 under the condition of uninterrupted operation. The output section of the filter housing 11 can collect the filtered coking wastewater and flow from the liquid outlet pipe 13 into the concentration unit 2 which can concentrate the coking wastewater. Preferably, the concentration unit 2 may include a medium-pressure membrane concentration unit 21 and a high-pressure membrane concentration unit 22. The filtered coking wastewater can sequentially pass through the medium-pressure membrane concentration unit 21 and the high-pressure membrane concentration unit 22, thereby completing the concentration decrement treatment of the coking wastewater.

In the prior art, industrial salt solution mixed by components after pretreatment of coking wastewater is generally input into a chamber in a negative pressure environment, so that sodium chloride in the coking wastewater is separated out in a way that the sodium chloride passes through a nanofiltration membrane under the negative pressure condition, and separation of sodium chloride solution and sodium sulfate solution in the mixed salt solution is realized. However, the separation effect of the sodium chloride solution and the sodium sulfate solution cannot be ensured in the prior art, and a large amount of sodium chloride still exists in the separated sodium sulfate solution, so that the purity of the crystal salt generated by the sodium sulfate solution cannot meet the purity requirement of the finished industrial salt. This application improves separation subassembly 3 to current sodium chloride solution and sodium sulfate solution's separator's defect, accomplishes sodium chloride's separation through the flow state of control coking wastewater in the runner, especially through the velocity of flow, hydraulic pressure and the flow of change coking wastewater in the different regions of flow channel for coking wastewater can fully contact with the nanofiltration membrane that constitutes the runner wall of separation filtration structure 32, promotes sodium chloride in the coking wastewater and can effectively permeate the nanofiltration membrane and take place the separation with sodium sulfate solution.

A separation module 3 capable of separating the components of the filtered and concentrated coking wastewater is preferably connected downstream of the concentration unit 2. As shown in fig. 3, the separation assembly 3 comprises an outer sleeve 31 and a separation filter structure 32. The outer sleeve 31 is suspended with a separation and filtration structure 32 capable of separating the coking wastewater in the axial direction thereof in the lumen by a supporting structure 33. Specifically, a part of specific components which can permeate through the nanofiltration membrane in the coking wastewater enters a lumen channel between the outer sleeve 31 and the separation and filtration structure 32 in a manner of penetrating through the flow channel wall of the separation and filtration structure 32, and the residual coking wastewater which cannot be filtered out from the separation and filtration structure 32 directionally flows along a liquid flow channel formed by the separation and filtration structure 32, so that the separation of the coking wastewater components is completed by connecting the output end of the outer sleeve 31 with the output end of the separation and filtration structure 32 through a different crystallization assembly 4. Preferably, the specific component of the flow of the coking wastewater that can permeate the nanofiltration membrane is sodium chloride solution, and the liquid retained in the flow channel is sodium sulfate solution.

Preferably, the flow channels of the separation and filtration structures 32 are streamlined. At least one mixed flow structure 321 capable of splitting and secondarily mixing the liquid flow in the flow channel is arranged in the flow channel of the separation and filtration structure 32. Specifically, the mixed flow structure 321 is a split island provided in the flow channel of the separation filter structure 32. The mixed flow structure 321 can divide the flow channel of the separation and filtration structure 32 into two sub-flow channels 322, so that the liquid flow can be divided into two sub-liquid flows respectively flowing to different sub-flow channels 322 by the front end of the mixed flow structure 321. It is further preferred that the sub-streams flowing into the sub-channels 322 are capable of converging at the end of the mixing structure 321 after exiting the sub-channels 322, such that the two sub-streams converging with each other are capable of generating a relative impact force such that the components of the sub-streams are secondarily mixed. Preferably, the flow channels of the separating and filtering structure 32 are arranged in such a way that the longitudinal cross-section of the inner chamber thereof is undulating, i.e. the transverse cross-section of the inner chamber of the flow channels is varied in such a way that it gradually increases and then gradually decreases. The region of the inner chamber having a larger transverse cross-sectional area is provided with a mixing structure 321 capable of constructing two sub-channels 322 in cooperation with the channel walls of the channels. The mixing structure 321 may be configured as a shuttle structure that can mate with the internal flow channel chamber such that a section of the flow channel having a larger cross-sectional area can be separated into two parallel sub-flow channels 322 by the mixing structure 321. Preferably, the head ends of the two sub-channels 322 are in communication with each other; the trailing ends of the two sub-channels 322 are also in communication with each other. When the liquid in the concentration unit 2 enters the flow channel, the liquid is a mixed state liquid, and when the liquid passes through the section of the mixed flow structure 321, the liquid is divided into two mixed state sub-liquid flows, and the sub-liquid flows directionally flow along the sub-flow channel 322. When the sub-streams flow out of the sub-channels 322, the two sub-streams merge at the ends where the two sub-channels 322 communicate with each other. Preferably, the sub-flow channels 322 are capable of altering the distribution of the sodium chloride composition in the fluid stream so that the sodium chloride composition in the fluid stream can be redistributed during the splitting/merging of the fluid stream, increasing the probability of contact of the sodium chloride composition with the flow channel walls so that the sodium chloride composition can be more effectively separated from the fluid stream. Preferably, the total flow rate of the two sub-channels 322 is greater than that of the mixed flow section of the channel, so that the flow in the sub-channels 322 accelerates the movement of the flow component molecules in the splitting process and simultaneously reduces the overall flow speed of the sub-flow, and thus the sodium chloride component in the sub-flow is fully contacted with the channel wall under the condition of keeping continuous movement, and the sodium chloride component is accelerated to permeate the channel wall, and finally, the component separation of the flow is realized. Preferably, the mixed flow section refers to a section of the flow channel which is not divided into two sub-flow channels 322 by the mixed flow structure 321. For the sodium chloride component which still exists in the sub-liquid flow and has lower activity and is positioned in the liquid flow, the kinetic energy of the residual sodium chloride component is obtained in the secondary merging process of the two sub-liquid flows through the secondary merging of the two sub-liquid flows, the activity of the residual sodium chloride component in the liquid flow is improved, and the residual sodium chloride component can accelerate to pass through the flow channel wall, so that the component separation of the liquid flow is realized.

Preferably, the mixing structure 321 is streamlined and is capable of splitting the flow in the flow channel at the streamline initial section of the mixing structure 321, so that the split two part flows can flow along the two sub-flow channels 322, thereby forming a split flow. The flow paths that are separated at the termination end of the flow line are streamlined so that the split streams within the two sub-flow paths 322 converge and mix to form a first mixed stream. In the process of mixing liquid flows, the whole flow passage is narrowed, the liquid pressure of the liquid flows is increased, and the micro-positive pressure of the liquid flows is increased. In addition, during the mixing process of the liquid flow, due to the change of the pressure and the flow velocity of the liquid flow, coking wastewater components which can permeate through the flow channel wall in the liquid flow can accelerate the separation of specific components from the coking wastewater under the conditions of mixing, impacting and pressing of the coking wastewater liquid flow, and the coking wastewater components permeate through the flow channel wall of the separation and filtration structure 32 and enter the pipe cavity channel between the outer sleeve 31 and the separation and filtration structure 32. Preferably, in the case where the coking wastewater stream is split into the sub-channels 322, the flow contact area with the channel walls of the separation and filtration structure 32 is increased and the mixing state of the specific components in the coking wastewater is re-agitated so that the specific components in the coking wastewater can better permeate the channel walls of the sub-channel 322 area to complete the exuded component separation. Preferably, under the condition that two split-flow liquid flows are mixed at the tail end of the sub-flow channel 322, the opposite flow fusion of the liquid flows can be accelerated, and the defect of uneven components in the liquid flow caused by filtration is eliminated, so that the component separation of the liquid flow by a subsequent structure is facilitated. Preferably, the merging of the sub-channels 322 may also create turbulence, thereby enabling a better transfer of the higher concentration of the filterable components inside the fluid to the surface of the fluid, thereby accelerating the passage through the channel wall in contact with the surface of the fluid.

Preferably, the separation and permeation structure 32 is constructed by disposing nanofiltration membranes capable of separating sodium chloride and sodium sulfate components on a flow channel molding structure net. Further preferably, the specific flow channel shape of the separation and filtration structure 32 can be adjusted according to the requirement, and the structural net can be made of flexible materials with high erosion resistance. Preferably, the flow channel wall of the separation and filtration structure 32 is a nanofiltration membrane capable of separating sodium chloride and sodium sulfate components, wherein the nanofiltration membrane can be attached to the inner wall side of the flow channel forming structure net, so that the structure net does not influence the flow of the liquid flow in the flow channel. Preferably, the filtrate permeable to the nanofiltration membrane is sodium chloride liquid and the liquid retained by the nanofiltration membrane is sodium sulphate liquid.

Preferably, in the case where a plurality of mixed flow structures 321 are provided in the middle of the streamline-shaped separation permeation structure 32, the profile of the mixed flow channel is adapted to the mixed flow structures 321 and the mixed flow section between the two mixed flow structures 321 is provided in a tendency that the flow channel width becomes narrower. Preferably, when the mixed liquid stream after the first diversion meets the second diversion module again, the first mixed liquid stream is separated and gathered again, so that a second mixed liquid stream is generated. Preferably, the liquid outlets of the flow channels are arranged as streamlined converging channels facilitating the gathering of the liquid, i.e. the liquid outlets are arranged at the end of the mixing structure 321. At this time, the liquid flows in the sub-flow channels 322 are converged, the liquid pressure is increased, and the micro-liquid pressure is formed to be larger, so that sodium chloride liquid can pass through the flow channel wall of the mixed flow section more conveniently. Preferably, the streamline flow passages can be mutually communicated, so that the air flow can be split and gathered at will.

Preferably, at least one micro-channel 323 capable of communicating with the sub-channel 322 is further formed in the body of the mixed flow structure 321. Preferably, the slotting direction of the micro flow channel 323 is consistent with the flow of the liquid flow in the sub flow channel 322, and the flow channel opening of the micro flow channel 323 is arranged in a manner of penetrating through the surface of the mixed flow structure 321 and communicating with the sub flow channel 322, so that the micro flow channel 323 can perform double flow division on the sub liquid flow in the sub flow channel 322. Preferably, the micro flow channels 323 within the mixed flow structure 321 may also selectively merge and split. Preferably, the micro flow channel 323 communicates the start end region and the end region of the sub flow channel 322. Because the micro flow channel 323 can partially drain the sub-liquid flow flowing into the sub-flow channel 322, the hydraulic pressure of the sub-liquid flow flowing through the micro flow channel 322 before and after the position of the liquid inlet of the micro flow channel 323 is changed, so that the activity of the sodium chloride component in the sub-liquid flow is further improved, the sodium chloride component is accelerated, the sodium chloride component can better and faster contact with the flow channel wall, and the efficiency of the sodium chloride component penetrating through the flow channel wall is improved. Preferably, the aperture of the micro flow channel 323 is smaller than the aperture of the sub flow channel 322, and the gas flow velocity in the micro flow channel 323 is faster under the same hydraulic condition, so that the component separation in the coking wastewater flow is more effectively completed. And the arrangement of the micro-runner 323 can compensate the flow velocity of the coking wastewater in the sub-runner 322, so that the defect that the flow velocity of the coking wastewater is reduced due to the fact that the hydraulic pressure in the sub-runner 322 is reduced is overcome, and the defect that the component separation of the coking wastewater flow is influenced due to the fact that the flow velocity is reduced due to the split flow in the whole runner is avoided. The invention ensures that the coking wastewater flow always maintains a higher flow rate by the arrangement of the micro-channels 323, and the separation of coking wastewater components is efficiently completed.

Example 3

The application also provides a coking wastewater crystallization salt separation process, which at least comprises the following steps:

(1) Pretreatment: mainly removes hardness, silicon dioxide, F-, CODcr and residual impurities in the coking wastewater, eliminates the influence of impurities on membrane concentration and evaporative crystallization treatment, ensures the quality of crystallized salt, and reduces the amount of waste crystallized salt as much as possible. The hardness is removed by adopting a lime soda softening method to remove most of the hardness, and the residual hardness is completely removed by adopting an ion exchange method.

(2) Membrane concentration: mainly uses two-stage membrane concentration to reduce the water and improve the salt content of the concentrated water; on the basis, the two-stage nanofiltration membrane is utilized to carry out membrane separation on sodium sulfate and sodium chloride.

The effluent of the weak acid cation bed firstly enters a GTR3 medium-pressure membrane concentration device for concentration and decrement, the concentrated water produced by the GTR3 medium-pressure membrane concentration device enters a GTR4 high-pressure membrane concentration device for continuous concentration and decrement, and various indexes such as hardness, F-, silicon, COD and the like of the concentrated water produced by the GTR4 high-pressure membrane concentration device are greatly concentrated, so that the concentrated water needs to be treated before entering a subsequent system.

(3) Separating salt: after the hardness of the chelate resin is removed, the chelate resin enters a first-stage nanofiltration membrane device for salt separation, in order to improve the purity of sodium chloride crystal salt and the recovery rate of sodium sulfate crystal salt, the produced water of the first-stage nanofiltration membrane device enters a second-stage nanofiltration membrane device, the concentrated water of the second-stage nanofiltration membrane device flows back to the first-stage nanofiltration membrane device for continuous treatment, the produced water of the second-stage nanofiltration membrane device enters a sodium chloride RO device for concentration, and the concentrated brine of the sodium chloride RO device enters a sodium chloride evaporation crystallization component; the concentrated water of the first-stage nanofiltration membrane device enters a sodium sulfate evaporation crystallization component to carry out evaporation crystallization treatment after COD is reduced by ozone oxidation; and the produced water of the GTR3 and GTR4 two-stage membrane concentration device and the sodium chloride RO device enters a recycling water pool.

(4) Extracting salt, evaporating and crystallizing: mainly separating sodium sulfate, sodium chloride crystal salt and other products, wherein the sodium sulfate crystal salt is obtained by adopting nitrate MVR+ countercurrent triple-effect evaporation crystallization; salt MVR+ concurrent double-effect evaporation crystallization is utilized to obtain sodium chloride crystal salt; the mother liquor of the nitrate triple-effect evaporative crystallization and the mother liquor of the salt double-effect evaporative crystallization enter a mixed salt double-effect evaporative crystallization together, and the residual mother liquor enters an evaporative crystallization drying integrated machine.

Concentrated water containing nitrate is concentrated by MVR and then enters a nitrate countercurrent triple-effect evaporation crystallizer, nitrate is discharged from a high temperature section of the evaporation crystallizer, the concentrated water is thickened by a thickener and then enters a dryer after being dehydrated by a centrifuge, and the dried finished sodium sulfate is sent to a product packaging line.

The concentrated water containing salt enters a salt double-effect evaporation crystallizer after being concentrated by MVR, salt is discharged from a low-temperature section of the evaporation crystallizer, the concentrated water is thickened by a thickener, and then enters a dryer after being dehydrated by a centrifugal machine, and the dried finished sodium chloride is sent to a product packaging line.

The residual mother liquor of the nitrate crystallizer and the salt crystallizer enters a two-effect salt mixing crystallizer to produce mixed salt, and enters a first-stage nanofiltration device for continuous salt separation treatment after re-dissolution.

And drying the residual mother liquor of the salt mixing crystallizer by an evaporation crystallization drying integrated machine to obtain mixed salt.

It should be noted that the above-described embodiments are exemplary, and that a person skilled in the art, in light of the present disclosure, may devise various solutions that fall within the scope of the present disclosure and fall within the scope of the present disclosure. It should be understood by those skilled in the art that the present description and drawings are illustrative and not limiting to the claims. The scope of the invention is defined by the claims and their equivalents. Throughout this document, the word "preferably" is used in a generic sense to mean only one alternative, and not to be construed as necessarily required, so that the applicant reserves the right to forego or delete the relevant preferred feature at any time.

Claims (10)

1. A coking wastewater crystallization separation device at least comprises a crystallization component (4) capable of respectively crystallizing at least two separated coking wastewater components, and is characterized in that filtrate and trapped liquid separated in the separation component (3) respectively enter different evaporation crystallization channels of the crystallization component (4) selectively, so that the salt evaporation crystallization treatment of the filtrate and the trapped liquid is respectively completed through different evaporation procedures,

The crystallization component (4) is further provided with a preheating unit (5) capable of preheating the filtrate and the trapped fluid after separation treatment in sequence, and the preheating unit (5) is coated on a liquid flow branch (43) of the crystallization component (4) so that the preheating unit (5) can synchronously and orderly complete the preheating treatment of the filtrate and the trapped fluid;

the separation assembly (3) comprises an outer sleeve (31) and a separation and filtration structure (32), and the separation and filtration structure (32) capable of separating the coking wastewater is suspended in the lumen along the axial direction of the outer sleeve (31) through a supporting structure (33);

wherein, the specific components of the part of the permeable nanofiltration membrane in the coking wastewater enter a pipe cavity channel between the outer sleeve (31) and the separation and filtration structure (32) in a way of penetrating through the flow channel wall of the separation and filtration structure (32), and the residual coking wastewater which cannot be filtered out from the separation and filtration structure (32) directionally flows along a liquid flow channel formed by the separation and filtration structure (32), thereby completing the separation of the components of the coking wastewater in a way of connecting the output end of the outer sleeve (31) with the output end of the separation and filtration structure (32), wherein the specific components of the permeable nanofiltration membrane in the liquid flow of the coking wastewater are sodium chloride solution, and the liquid remained in the flow channel is sodium sulfate solution;

The flow channel of the separation and filtration structure (32) is streamline, at least one mixed flow structure (321) which can split and secondarily mix the liquid flow in the flow channel is arranged in the flow channel of the separation and filtration structure (32), the mixed flow structure (321) is a split island arranged in the flow channel of the separation and filtration structure (32), the flow channel of the separation and filtration structure (32) can be divided into two sub-flow channels (322) by the mixed flow structure (321), the liquid flow can be divided into two sub-liquid flows which respectively flow to different sub-flow channels (322) by the front end of the mixed flow structure (321), the sub-liquid flows flowing into the sub-flow channels (322) can be converged at the tail end of the mixed flow structure (321) after flowing out of the sub-flow channels (322), and therefore, the two sub-liquid flows which are mutually converged can generate relative impact force, and the components in the sub-liquid flows are secondarily mixed;

the flow channels of the separation and filtration structure (32) are arranged in a way that the longitudinal cross section of the inner cavity is wavy, namely, the transverse cross section of the inner cavity of the flow channels is changed in a way that the cross section of the inner cavity is gradually increased and then gradually decreased.

2. The device according to claim 1, characterized in that the preheating unit (5) comprises at least a preheating coil (51) capable of being coiled around the outside of the wall of the first flow branch (431) for the transport of the filtrate and a spent heating coil (52) coiled around the outside of the wall of the second flow branch (432) for the transport of the retentate.

3. The apparatus of claim 2 wherein the preheating coil (51) and the spent heating coil (52) are connected in a manner that forms an upstream and downstream conduit in communication with each other such that high temperature steam flowing through the preheating coil (51) heats the first flow leg (431) and then flows into the spent heating coil (52) along the conduit to heat the second flow leg (432).

4. A coking wastewater crystallization separation device according to claim 3, characterized in that said first liquid flow branch (431) communicates its downstream pipe outlet with the first crystallization assembly (41) in such a way that the preheated filtrate in its pipe is conveyed to the crystallization treatment structure, so that the preheated filtrate can be evaporated and crystallized in said first crystallization assembly (41).

5. The coking wastewater crystallization separation device according to claim 4, wherein the trapped fluid in the second liquid flow branch (432) can be directionally conveyed to the second crystallization component (42) after being preheated by dead steam, and the second crystallization component (42) performs evaporative crystallization treatment on the preheated trapped fluid.

6. The coking wastewater crystallization separation device according to claim 5, wherein exhaust steam generated by exothermic reaction of the heating steam flowing in the preheating coil (51) can flow into the exhaust heating coil (52);

the gas-liquid mixture generated after the trapped fluid in the second fluid flow branch (432) is heated by the heat released by the exhaust steam directionally flowing in the exhaust heating coil (52) can be conveyed to a condensing unit (53).

7. The coking wastewater crystallization separation device according to claim 6, wherein the liquid produced by the condensing unit (53) can flow back to the evaporating unit (54);

the high-temperature steam generated by the evaporation unit (54) can directionally flow into the preheating coil (51), the evaporation unit (54) at least comprises a first heating unit (541) which is arranged outside the first crystallization component (41) and the second crystallization component (42) in a coating mode, and the first heating unit (541) can absorb heat dissipated by the first crystallization component (41) and the second crystallization component (42) in the evaporation crystallization treatment process to heat liquid.

8. The coking wastewater crystallization separation device according to claim 7, wherein the evaporation unit (54) further comprises a second evaporation unit (542) capable of evaporating the heated liquid, the second evaporation unit (542) being in communication with the preheating coil (51).

9. The coking wastewater crystallization separation device according to claim 8, wherein the output ends of the first crystallization assembly (41) and the second crystallization assembly (42) are further connected with a separation assembly capable of separating crystalline salt from residual mother liquor and a salt leg (7) for storing the crystalline salt.

10. A coking wastewater crystallization separation process of a coking wastewater crystallization separation device according to one of claims 1 to 9, characterized by comprising at least the steps of:

the impurities in the coking wastewater are filtered in a pretreatment filtering mode;

carrying out water reduction treatment on the coking wastewater subjected to impurity filtration;

the method comprises the steps of separating sodium sulfate concentrated water from sodium chloride concentrated water in coking wastewater, and changing the flow rate, hydraulic pressure and flow rate of the coking wastewater in different areas of a liquid flow channel, so that the coking wastewater can be fully contacted with a nanofiltration membrane forming a flow channel wall of a separation and filtration structure, and sodium chloride in the coking wastewater can be promoted to permeate the nanofiltration membrane to be separated from a sodium sulfate solution;

evaporating and crystallizing the separated sodium sulfate concentrated water and sodium chloride concentrated water by utilizing a salt extraction evaporation crystallization device to obtain crystalline salt;

and (3) placing the residual mother liquor after evaporation and crystallization into a mixed salt crystallization device to produce mixed salt, and re-dissolving and re-conveying the obtained mixed salt to a circulating nanofiltration device to continue salt separation treatment.

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