CN214936175U

CN214936175U - Brine fractional evaporation crystallization system

Info

Publication number: CN214936175U
Application number: CN202120883272.6U
Authority: CN
Inventors: 刘小凯; 杨勇; 王玉立; 许亮
Original assignee: Jiangsu Maiande Energy Saving Evaporation Equipment Co ltd
Current assignee: Jiangsu Maiande Energy Saving Evaporation Equipment Co ltd
Priority date: 2021-04-27
Filing date: 2021-04-27
Publication date: 2021-11-30
Anticipated expiration: 2031-04-27

Abstract

The utility model relates to a brine fractional evaporation crystallization system, which comprises an evaporator and a crystallizer, wherein the lower part of a main cylinder body of the crystallizer is connected with a lower cone body of the crystallizer, the lower port of the lower cone body of the crystallizer is connected with an elutriation cylinder, the middle part of the side wall of the main cylinder body of the crystallizer is provided with a crystallization circulation outlet, and the lower cone body of the crystallizer is provided with a crystallization circulation inlet; the crystallization circulating outlet is connected with an inlet of an evaporation circulating pump through a circulating evaporation pipe, an outlet of the evaporation circulating pump is connected with an inlet at the bottom of the evaporator, and an outlet at the top of the evaporator is connected with a crystallization circulating inlet; a new material inlet is arranged in the middle of the elutriation cylinder, a side wall outlet of the crystal slurry is arranged on the circumference of the lower part of the elutriation cylinder, and the side wall outlet of the crystal slurry is connected with a crystal slurry discharge pipe; the upper circumference of the washing cylinder is provided with a washing cylinder clear liquid port which is connected with the circulating evaporation pipe. The brine fractional evaporation crystallization system can improve the grain diameter and purity of refined salt and greatly improve the added value of products while reducing the energy consumption of the system.

Description

Brine fractional evaporation crystallization system

Technical Field

The utility model relates to an industrial wastewater treatment system especially relates to a salt solution fractional evaporation crystallization system, belongs to industrial wastewater treatment and resource regeneration technical field.

Background

The chemical industry is in an important position in national production in China, most chemical industry produces waste salt, the yield of the chemical industry waste salt is close to 1000 ten thousand tons every year according to incomplete statistics, and most of the chemical industry waste salt contains sodium chloride. The conventional waste salt disposal means is mainly sea drainage and landfill, but the treatment mode has high cost, secondary pollution, even serious environmental problems and is forbidden, so the resource recycling of the waste salt becomes a new way for disposing the waste salt at present.

The method is characterized in that the conventional process of incineration, impurity removal, membrane treatment and evaporative crystallization is generally adopted in the recovery process of waste salt containing sodium chloride, and a sodium chloride product obtained by evaporative crystallization of sodium chloride concentrated brine obtained through the process of incineration, membrane treatment and impurity removal cannot be used as a raw material of high-end fine chemical engineering due to the fact that the particle size is less than or equal to 0.1mm, the specific surface area is large, the adhesive tapes are more, the purity is lower, the sodium chloride product can be generally used only as a low-end snow melting agent and a building material additive, and the selling price is about 50 yuan/ton; and the demand of the snow-melting agent is relatively small, the influence of seasons is large, the snow-melting agent needs to be stored in a compressed storage at most of time every year, and the additional value is almost negligible.

On the other hand, large-particle sodium chloride has small specific surface area and high purity, and can be used as a raw material of high-end fine chemical industry, the demand of the chemical industry for large-particle and high-purity sodium chloride is gradually increased, the selling price of sodium chloride products with the particle size of more than or equal to 0.3mm is more than 1000 yuan/ton, the problem that how to realize the refining production of sodium chloride concentrated brine is urgently needed to be solved is solved, and the development of the environmental protection industry is also restricted.

SUMMERY OF THE UTILITY MODEL

The utility model aims to overcome conventional evaporative crystallization energy consumption height, the product granule is thin, and the problem that purity is low provides a hierarchical evaporative crystallization system of salt solution, when the lowering system energy consumption, can improve the particle diameter and the purity of refined salt, increases substantially the added value of product.

In order to solve the technical problem, the utility model discloses a brine fractional evaporation crystallization system, including evaporimeter and crystallizer, the crystallizer includes crystallizer main cylinder, the lower part of crystallizer main cylinder is connected with crystallizer lower cone, the lower port of crystallizer lower cone is connected with elutriation section of thick bamboo, the lateral wall middle part of crystallizer main cylinder is equipped with the circulation of crystallization export, be equipped with the circulation of crystallization import on the crystallizer lower cone; the crystallization circulating outlet is connected with an inlet of an evaporation circulating pump through a circulating evaporation pipe, an outlet of the evaporation circulating pump is connected with a bottom inlet of an evaporator, and a top outlet of the evaporator is connected with the crystallization circulating inlet; a fresh material inlet is formed in the middle of the elutriation cylinder, a magma side wall outlet is formed in the circumference of the lower portion of the elutriation cylinder, and the magma side wall outlet is connected with a magma discharge pipe; an elutriation barrel clear liquid port is formed in the circumference of the upper portion of the elutriation barrel, and is connected with the circulating evaporation pipe.

As an improvement of the utility model, the crystallization circulation inlet is tangent to the middle side wall of the lower cone of the crystallizer, and the root part of the crystallization circulation inlet is inclined upwards by 3-7 degrees.

As the improvement of the utility model, the magma discharge pipe links to each other with the entry of discharge pump, the export of discharge pump links to each other with the lateral wall entry of swirler, the bottom of swirler links to each other with the entry of stiff ware through swirler underflow pipe, the bottom of stiff ware links to each other with centrifuge's entry through stiff ware underflow pipe, centrifuge's discharge gate passes through the wet salt elephant trunk and docks with band conveyer, band conveyer's export links to each other with the entry of dry bed.

As the improvement of the utility model, the top overflow mouth of swirler passes through the swirler overflow pipe and links to each other with the overflow jar, the overflow mouth on stiff ware upper portion links to each other with the overflow jar through the stiff ware overflow pipe, the bottom export of overflow jar links to each other with the entry of feed back pump through backward flow mother liquor pipe, the outlet pipe of feed back pump with circulation evaporation pipeline links to each other.

As an improvement of the utility model, the liquid phase outlet of the centrifuge is connected with the inlet of the centrifuge mother liquor tank through a centrifuge mother liquor pipe, the inlet of the centrifuge mother liquor tank is also connected with a sodium chloride strong brine pipe, the inner cavity of the centrifuge mother liquor tank is provided with a stirring device, the bottom outlet of the centrifuge mother liquor tank is connected with the inlet of the centrifuge mother liquor pump through a mother liquor tank discharge pipe, the outlet of the centrifuge mother liquor pump is connected with the main inlet of a pipeline mixer, a forward rotatable spiral is arranged in the pipeline mixer, the pipeline mixer is tangentially connected with an oxidant inlet, an oxidant injection port is connected with an oxidant injection pipe, the outlet of the pipeline mixer is connected with the upper inlet of an oxidation tower, the circulating liquid outlet of the oxidation tower is connected with the inlet of an oxidation tower circulating pump, the outlet of the oxidation tower circulating pump is connected with the upper circulating liquid inlet of the oxidation tower and an internal spray head, and a discharge hole in the middle of the oxidation tower is connected with an inlet of the overflow tank.

As an improvement of the utility model, a material stopper for guiding solid wet salt to an inlet of the drying bed is arranged at an outlet end of the belt conveyor, and a reverse water-stop plate is arranged at the bottom of the belt conveyor; the outlet of the drying bed is connected with the inlet of a high-frequency vibrating screen, the high-frequency vibrating screen is provided with an inclined double-layer screen, a product I with the grain diameter of more than or equal to 0.3mm is led out from the oversize product outlet, and the yield of the product I is more than or equal to 50%; a second product with the grain size of 0.1-0.3 mm is led out from the middle outlet, a third product with the grain size of less than or equal to 0.1mm is led out from the screen underflow outlet, and the yield of the third product is less than or equal to 20%.

As an improvement of the utility model, the top gas vent of dry bed links to each other with cyclone's lateral wall air intake, cyclone's bottom export is derived the particle diameter and is less than or equal to 0.1 mm's product three, cyclone's top export links to each other with the air intake of drip washing tower through the dust removal exhaust pipe, the bottom outlet of drip washing tower links to each other with the entry of drip washing tower circulating pump, the export of drip washing tower circulating pump with the upper portion of drip washing tower sprays the mouth and links to each other, the top gas vent of drip washing tower links to each other with the entry of draught fan, the export of draught fan communicates with each other with the exhaust-gas treatment pipeline.

Compared with the prior art, the utility model discloses following beneficial effect has been obtained: 1. heating the evaporation circulation feed liquid by an evaporator, heating to 108-110 ℃, enabling the evaporation circulation feed liquid to enter an inner cavity of a lower cone of a crystallizer from a crystallization circulation inlet along a tangential direction and upwards inclining for 3-7 degrees, enabling the evaporation circulation feed liquid to flow to an upper main cylinder of the crystallizer while rotating, and carrying out evaporation crystallization in the flowing process, wherein the evaporation temperature is 100 ℃; and a rotational flow grading force field is formed at a certain flow velocity, so that the first grading of the sodium chloride salt is realized. The fine particle sodium chloride salt floats upwards under the action of the rotational flow, overflows from a crystallization circulating outlet of a main cylinder body of the crystallizer, and enters a circulating evaporation pipe for secondary circulating crystallization. The content and the granularity of sodium chloride in the circulating feed liquid are reduced by the first grading, the probability of salt formation when the circulating feed flows through the heat exchange area of the tube array of the evaporator is reduced, and the stability of an evaporation system is improved. The cyclone classification force field improves the surface area of an evaporation area of the crystallizer, reduces the evaporation intensity, and the low evaporation intensity can improve the granularity of primary salt crystallization to achieve the virtuous cycle of the system.

2. After being cached by a feeding tank, sodium chloride concentrated brine with the weight of 20 +/-5 percent is sent to a preheating unit by a feeding pump for preheating, enters an elutriation barrel below a lower cone of the crystallizer from a new material inlet, and elutriates sodium chloride in the upward flowing process. The lower port of the lower cone of the crystallizer forms an annular material falling area, when strong brine enters the lower cone of the crystallizer from the elutriation cylinder, the flow velocity is reduced due to the amplification of the section, turbulence is formed, part of fine-particle sodium chloride is dissolved, large-particle sodium chloride is sunk into the elutriation cylinder, and the fine-particle sodium chloride floats upwards, so that the secondary classification of the sodium chloride is realized. The fine particle sodium chloride salt and the saturated sodium chloride solution float to a clear liquid port of the elutriation cylinder to be discharged, and enter a circulating evaporation tube to participate in the recycling process of an evaporation system. The recycling of the elutriation clear liquid overcomes the phenomena of blockage and agglomeration caused by high salt content and slow flow rate, the secondary-graded magma continuously sinks to the outlet of the side wall of the magma at the lower part of the elutriation cylinder to be discharged, the annular falling material and the feeding elutriation are combined together to reduce the content of fine-particle sodium chloride in the elutriation discharge material, and the quality of the discharge material is further improved.

3. The large-particle sodium chloride salt discharged from the outlet of the side wall of the crystal slurry enters the crystal slurry discharge pipe, the solid content of discharged crystal slurry is 20 +/-5 percent by weight, and the low-solid-content discharged crystal slurry reduces the risk of blockage of a discharge pipeline, simultaneously reduces the solid content in circulating materials, reduces the load of a circulating pump and also reduces the risk of blockage of an evaporator tube nest. The discharging of the crystal slurry is sent into a swirler by a discharging pump, and the swirler carries out third grading on the discharging of the sodium chloride crystal slurry; the solid content of the overflow of the cyclone is 5 +/-2 percent wt and enters an overflow tank, the solid content of the underflow of the cyclone is 30 +/-5 percent wt and enters a thickener, the thickener performs fourth classification on the underflow of the cyclone, the solid content of the overflow of the thickener is 3 +/-1 percent and enters the overflow tank, the solid content of the underflow of the thickener is 45 +/-3 percent wt and enters a centrifuge for solid-liquid separation, and the content of particles with the thickness of more than or equal to 0.3mm in the feed of the centrifuge is more than or equal to 50 percent. Through third, quartic grading, further improve the sodium chloride particle size of centrifuge feeding, improve the solid-to-liquid ratio of centrifuge feeding, compare traditional handicraft, the centrifugal salt moisture content that goes out reduces 3%, effectively reduces the energy consumption of drying bed, improves the loose degree of drying bed feeding simultaneously, has stopped the inside caking phenomenon's of drying bed emergence basically, further improves final product quality.

4. Mother liquor separated by the centrifuge enters a centrifugal mother liquor tank for caching, the moisture content of solid wet salt discharged by the centrifuge is reduced to 2 +/-0.5%, the solid wet salt falls on a belt conveyor, the belt conveyor effectively guarantees loosening and rapid transportation of the centrifuged salt, an outlet of the belt conveyor is guided into an inlet of a drying bed by a material stopper, salt loss in the conveying process is reduced, and then the drying is carried out by hot air in the drying bed. When the centrifugal machine washes, the belt conveyor runs reversely, the reversing water-stop sheet can effectively reduce the entrainment of washing water of the centrifugal machine, effectively block the influence of the centrifugal washing water on the drying bed, and improve the operation stability of the drying bed. Drying the wet salt by hot air in a drying bed, wherein the water content of the finished salt discharged from the drying bed is less than or equal to 0.5%, and screening the finished salt by a high-frequency vibrating screen to obtain three products according to particle size classification.

5. The air outlet of the drying bed enters a cyclone separator, sodium chloride fine particle salt carried by the tail gas is further recovered, the yield and the recovery rate of the product are improved, the air outlet of the cyclone separator enters a leaching tower for washing, a circulating pump of the leaching tower is provided with a plurality of layers of opposite rotatable spray heads, and self-circulation spray washing is carried out through the circulating pump of the leaching tower, so that the carrying of the tail gas is further reduced, and the tail gas treatment difficulty is reduced.

6. Adding the other part of 20 +/-5 wt% of sodium chloride concentrated brine from the sodium chloride concentrated brine pipe into a centrifugal mother liquor tank, mixing the centrifugal mother liquor separated by a centrifuge at the temperature of 95 +/-5 ℃ and the solid content of 5 +/-2 wt%, dissolving a small amount of sodium chloride fine particle salt remained in the centrifugal mother liquor after mixing the low-temperature sodium chloride concentrated brine with the centrifugal mother liquor, and cooling to 60 +/-5 ℃. Centrifugal mother liquor in the centrifugal mother liquor tank is conveyed to the oxidation tower by the centrifugal mother liquor pump, a pipeline mixer is arranged on an outlet pipeline of the centrifugal mother liquor pump and is mixed with an entering strong oxidant, the centrifugal mother liquor after uniform mixing enters the oxidation tower to perform catalytic oxidation reaction, organic matters are decomposed, the oxidation tower realizes the circulation of the centrifugal mother liquor by an external oxidation tower circulating pump, and the oxidation reaction time of the centrifugal mother liquor can reach 2 hours. The discharge of the oxidation tower enters an overflow tank under the pressure difference, the overflow of the cyclone and the overflow of the thickener also enter the overflow tank, and the mixed materials are conveyed to a circulating evaporation pipe by a feed back pump to participate in the circulation of secondary heat exchange evaporation crystallization. COD content in the sodium chloride strong brine is 200mg/L usually, after entering the evaporation crystallization system and evaporating in succession, can cause the organic matter enrichment, influence product quality, this system passes through the oxidation tower and carries out degradation once more to a small amount of organic matters of evaporation enrichment in to centrifugal mother liquor, can be with the COD content control in the crystallizer below 1000mg/L, effectively guarantee the quality of the sodium chloride salt of backward flow mother liquor evaporation crystallization output once more, guaranteed the continuity and the stability of system's production.

7. The brine grading, evaporating and crystallizing system increases crystallized salt particles by reducing evaporation speed, carrying out primary cyclone classification, carrying out overflow recycling and secondary salt-precipitating elutriation classification, then conveying the crystallized salt particles to a cyclone and a thickener by a discharge pump for carrying out three-time and four-time classification, further improving the solid-liquid ratio and the granularity of the feed of a centrifugal machine, enabling the water content of the centrifuged salt to be 2 +/-0.5%, connecting a salt outlet of a drying bed with a high-frequency vibrating screen to classify products, separating high and low added-value products, and obtaining the high added-value product with the particle size of more than or equal to 0.3mm, reaching more than 50%, and reducing the low added-value product with the particle size of less than or equal to 0.1mm to less than 20%. The method reduces the energy consumption of the system, increases the particle size of the sodium chloride salt through multiple grading, improves the added value, realizes the grading of the system product, improves the competitiveness of the product, and widens the high-end utilization field of the industrial waste salt.

8. The high-temperature feeding participates in elutriation, so that the granularity of sodium chloride in the discharged material of the crystallizer can be effectively improved, the problems of caking and blockage caused by fine salt granularity are solved, the primary crystallization grading can be effectively realized by a small-angle up-cutting structure adopted by a circulating feed liquid inlet, the aim of reducing the evaporation speed and improving the granularity of the crystallized salt is achieved, the solubility of trace impurities is further improved through normal-pressure evaporation, the entrainment in the crystal nucleus forming process of the sodium chloride crystallized salt is reduced, the particle size and the purity of the salt are improved, the added value of the product is greatly improved, and the separation of high-price and low-price products is reliably realized.

Drawings

The invention will be described in further detail with reference to the drawings and the detailed description, which are provided for reference and illustration purposes only and are not intended to limit the invention.

Fig. 1 is a flow chart of the brine fractional evaporation crystallization system of the present invention.

Fig. 2 is an enlarged view of the crystallizer of fig. 1.

In the figure: 1. a feed tank; 2. a primary preheater; 3. a secondary preheater; a steam-water separator; 4. a condensate tank; 5. an evaporator; 6. a crystallizer; 6a, a crystallization circulation outlet; 6b, a crystallization circulation inlet; 6c, a new material inlet; 6d, a side wall outlet of the crystal slurry; 6e, a bottom outlet of the crystal slurry; 6f, washing a clear liquid port of the barrel; 6g, a secondary steam outlet; 7. a secondary separator; 8. a vapor compressor; 9. a swirler; 10. a thickener; 11. a centrifuge; 12. an overflow tank; 13. centrifuging the mother liquor tank; 14. a pipeline mixer; 15. an oxidation tower; 16. a belt conveyor; 17. drying the bed; 18. a cyclone dust collector; 19. leaching the tower; 20. an induced draft fan; 21. a blower; 22. a heat exchanger; 23. a high-frequency vibrating screen; B1. a feed pump; B2. a condensate pump; B3. an evaporation circulating pump; B4. a discharge pump; B5. a material return pump; B6. a centrifugal mother liquor pump; B7. a circulating pump of the oxidation tower; B8. a circulating pump of the leaching tower; G1. a sodium chloride concentrated brine pipe; G2. a condensate pipe; G3. a noncondensable gas discharge pipe; G4. a secondary steam pipe; G5. pressurizing a steam pipe; G6. secondary separation drain pipe; G7. a crystal slurry discharge pipe; G8. an overflow pipe of the cyclone; G9. a swirler underflow tube; G10. a thickener overflow pipe; G11. a thickener underflow pipe; G12. a wet salt chute; G13. centrifuging the mother liquor pipe; G14. a mother liquid tank discharge pipe; G15. an oxidant injection pipe; G16. a reflux mother liquor pipe; G17. a filtered air tube; G18. a raw steam pipe; G19. a steam-generating condensate pipe; G20. a dust removal exhaust pipe; G21. a first product; G22. a second product; G23. and (5) obtaining a third product.

Detailed Description

In the following description of the present invention, the terms "upper", "lower", "front", "rear", "left", "right", "inner", "outer", and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, and are only for convenience of description and simplification of description, and do not mean that the device must have a specific orientation.

As shown in fig. 1 and fig. 2, the graded evaporative crystallization system for brine of the present invention comprises a feed tank 1 connected to a concentrated brine pipe G1 of sodium chloride, the bottom of the feed tank 1 is connected to an inlet of a feed pump B1, an outlet of the feed pump B1 is connected to a fresh material inlet 6c of a crystallizer 6, a crystallization circulation outlet 6a of the crystallizer 6 is connected to an inlet of an evaporative circulation pump B3 through a circulation evaporation pipe, an outlet of the evaporative circulation pump B3 is connected to a bottom inlet of an evaporator 5, a top outlet of the evaporator 5 is connected to a crystallization circulation inlet 6B of the crystallizer 6, a magma discharge pipe G7 of the crystallizer 6 is connected to an inlet of a discharge pump B4, an outlet of the discharge pump B4 is connected to a sidewall inlet of a cyclone 9, a bottom of the cyclone 9 is connected to an inlet of a thickener 10 through a cyclone bottom flow pipe G9, a bottom of the thickener 10 is connected to an inlet of a centrifuge 11 through a thickener bottom flow pipe G11, the discharge of the centrifuge 11 is connected to a belt conveyor 16 via a wet salt chute G12, the outlet of the belt conveyor 16 being connected to the inlet of the drying bed 17.

The outlet of the feed pump B1 is connected with the cold side inlet of the primary preheater 2, the cold side outlet of the primary preheater 2 is connected with the cold side inlet of the secondary preheater 3, and the cold side outlet of the secondary preheater 3 is connected with the circulating inlet of the crystallizer 6; an outlet of the condensate water pump B2 is connected with a hot side inlet of the primary preheater 2, and a hot side outlet of the primary preheater 2 is connected with a workshop condensate water recovery device; the non-condensable gas outlet of the shell pass of the evaporator 5 is connected with the hot side inlet of the second-stage preheater 3, the hot side outlet of the second-stage preheater 3 is connected with the inlet of the steam-water separator 3a, the exhaust port of the steam-water separator 3a is connected with a non-condensable gas discharge pipe G3, and the liquid discharge port of the steam-water separator 3a is connected with the condensed water tank 4 through a liquid seal.

Preheating the sodium chloride concentrated brine to 85 +/-5 ℃ at the first stage by utilizing 118 +/-5 ℃ steam condensate water discharged from the shell pass of the evaporator 5, and enabling the temperature of the condensate water discharged from the hot side of the first-stage preheater 2 to be 40 +/-5 ℃, and enabling the condensate water to enter a workshop condensate water recovery device for recycling; the non-condensable gas discharged from the shell pass of the evaporator 5 enters a secondary preheater 3 to secondarily preheat the sodium chloride concentrated brine to 93 +/-3 ℃. The preheating mode combining primary preheating of condensed water and secondary preheating of non-condensable gas is adopted, the primary preheater 2 effectively recovers heat of the condensed water, the secondary preheater 3 recovers heat of the non-condensable gas and a small amount of steam discharged by the evaporator 5, energy consumption of the system is reduced, meanwhile, the temperature of the discharged non-condensable gas is reduced, difficulty of subsequent waste gas treatment is reduced, and steam consumption per ton of water evaporated by the non-condensable gas preheating system can be reduced by 20-25 kg/h.

The secondary steam outlet 6G at the top of the crystallizer 6 is connected with the top inlet of the secondary separator 7 through a secondary steam pipe G4, a defoaming device is arranged in the secondary separator 7, the steam outlet of the secondary separator 7 is connected with the inlet of the steam compressor 8, the outlet of the steam compressor 8 is connected with the heat medium inlet at the upper part of the shell pass of the evaporator 5 through a pressurizing steam pipe G5, and the heat medium inlet of the evaporator 5 is also connected with a raw steam pipe G18.

A condensed water outlet at the lower part of the shell pass of the evaporator is connected with a condensed water tank 4 to realize liquid seal, an outlet at the bottom of the condensed water tank 4 is connected with an inlet of a condensed water pump B2, and an outlet of the condensed water pump B2 is connected with a condensed water pipe G2; the outlet of the vapor compressor 8 is internally provided with a rotary atomizing nozzle for cooling the compressed vapor to a saturated state, and a condensate pipe G2 is connected with the water inlet of the rotary atomizing nozzle through a flow meter and an adjusting valve.

The pressure at the top of the crystallizer 6 is normal pressure, the temperature of secondary steam generated by evaporation is 100-102 ℃, the secondary steam enters a steam compressor 8 for compression after being defoamed and sprayed by a secondary separator 7, the secondary steam generated by evaporation is compressed and heated by the steam compressor 8 according to a certain fixed pressure ratio, the temperature of the compressed superheated steam is 150 +/-5 ℃, in order to eliminate the superheat degree of the steam, a rotary atomizing nozzle is arranged in an outlet of the steam compressor 8, and part of condensed water pumped out by a condensed water pump B2 is used as atomized spray water supply of the rotary atomizing nozzle, so that the temperature of the superheated steam is reduced to reach a complete saturation state; the atomized condensed water absorbs heat to be vaporized, the superheat degree is eliminated, meanwhile, the steam quantity entering the evaporator 5 is increased, the enthalpy value of the steam is improved, the spraying quantity is accurately adjusted through the flow meter and the adjusting valve, so that the temperature of the pressurized steam pipe G5 is guaranteed to be stabilized at 118 +/-5 ℃, and a stable heat source is improved for the evaporator 5. The raw steam may be used only as a start-up or a supplement.

The condensate pipe G2 is also connected with a flushing port of the defoaming device, a water outlet at the bottom of the secondary separator 7 is connected with a balance port of the crystallizer 6 through a secondary separation water outlet pipe G6, and the balance port is positioned above the crystallization circulating outlet 6a. A part of the condensed water pumped by the condensed water pump B2 is used as a rinse for the demister built in the secondary separator 7. During the process of secondary steam defoaming device, 95% of entrained feed liquid can be removed, the entrained feed liquid forms condensate droplets to be gathered at the bottom of the secondary separator 7, a liquid discharge port at the bottom of the secondary separator 7 is provided with a water seal device, an outlet of the water seal device is connected with a balance port of the crystallizer 6, condensate and shower water can be timely conveyed to the crystallizer 6 through a secondary separation drain pipe G6 to participate in the secondary circulation evaporation crystallization, meanwhile, the internal pressure of the secondary separator 7 is ensured to be consistent with the internal pressure of the crystallizer 6 all the time, and the resistance loss and the heat loss of the secondary steam flowing through the secondary separator 7 are reduced. The demister of secondary separator 7 sets up washing terminals, adopts high temperature condensate water to wash, further reduces the calorific loss of operation in-process flash steam, can further improve flash steam's quality, has effectively guaranteed the stability and the pureness of steam compressor 8 admission, reduces steam compressor 8 because the secondary steam takes the emergence of the impeller damage that liquid leads to, has ensured the steady operation of system. The secondary separator 7 adopts an upper inlet and side outlet structure, so that the separation effect of secondary steam is further improved, and the maintenance difficulty of the defoaming device is reduced. Meanwhile, the quality of the steam discharged by the steam compressor 8 is improved, the shell of the evaporator is protected from being corroded, and the quality of the condensed water is further improved, so that the condensed water completely meets the requirement of continuous recycling.

The crystallizer 6 comprises a crystallizer main cylinder, the lower part of the crystallizer main cylinder is connected with a lower crystallizer cone, a crystallization circulation inlet 6b is tangentially connected with the middle side wall of the lower crystallizer cone and upwards inclines by 3-7 degrees, and a crystallization circulation outlet 6a is tangentially connected with the middle side wall of the crystallizer main cylinder.

Heating the evaporation circulation feed liquid by an evaporator 5, raising the temperature to 108-110 ℃, enabling the evaporation circulation feed liquid to enter an inner cavity of a lower cone of a crystallizer from a crystallization circulation inlet 6b along a tangential direction and inclining upwards by 3-7 degrees, enabling the evaporation circulation feed liquid to flow towards an upper main cylinder of the crystallizer while rotating, and performing evaporation crystallization in the flowing process, wherein the evaporation temperature is 100 ℃; and a rotational flow grading force field is formed at a certain flow velocity, so that the first grading of the sodium chloride salt is realized. The fine particle sodium chloride salt floats upwards under the action of the rotational flow, overflows from a crystallization circulation outlet 6a of the main cylinder of the crystallizer, and enters a circulation evaporation tube for secondary circulation crystallization. The content and the granularity of sodium chloride in the circulating feed liquid are reduced by the first grading, the probability of salt formation when the circulating feed flows through the heat exchange area of the tube array of the evaporator is reduced, and the stability of an evaporation system is improved. The cyclone classification force field improves the surface area of an evaporation area of the crystallizer, reduces the evaporation intensity, and the low evaporation intensity can improve the granularity of primary salt crystallization to achieve the virtuous cycle of the system.

The lower port of the lower cone of the crystallizer is connected with an elutriation cylinder, a new material inlet 6c is positioned in the middle of the elutriation cylinder, a side wall outlet 6d of crystal slurry is arranged on the circumference of the lower part of the elutriation cylinder, and the side wall outlet 6d of the crystal slurry is connected with a crystal slurry discharge pipe G7; the bottom of the elutriation barrel is provided with a magma bottom outlet 6e, and the magma bottom outlet 6e is also connected with an inlet of a discharge pump B4; the upper circumference of the washing cylinder is provided with a washing cylinder clear liquid port 6f, and the washing cylinder clear liquid port 6f is connected with the circulating evaporation pipe.

After being cached in the feeding tank 1, the sodium chloride concentrated brine with the weight of 20 +/-5 percent is sent to the preheating unit by the feeding pump B1 for preheating, enters the elutriation cylinder below the lower cone of the crystallizer from the new material inlet 6c, and elutriates sodium chloride in the upward flowing process. The lower port of the lower cone of the crystallizer forms an annular material falling area, when strong brine enters the lower cone of the crystallizer from the elutriation cylinder, the flow velocity is reduced due to the amplification of the section, turbulence is formed, part of fine-particle sodium chloride is dissolved, large-particle sodium chloride is sunk into the elutriation cylinder, and the fine-particle sodium chloride floats upwards, so that the secondary classification of the sodium chloride is realized. The fine particle sodium chloride salt and the saturated sodium chloride solution float to a clear liquid port 6f of the elutriation cylinder to be discharged, and enter a circulating evaporation tube to participate in the recycling process of an evaporation system. The recycling of the elutriation clear liquid overcomes the phenomena of blockage and agglomeration caused by high salt content and slow flow rate, the secondary-graded magma continuously sinks to the magma side wall outlet 6d at the lower part of the elutriation cylinder to be discharged, the annular falling material and the feeding elutriation are combined to reduce the content of fine-particle sodium chloride in the elutriation discharge material, and the quality of the discharge material is further improved.

Large-particle sodium chloride salt discharged from the outlet 6d on the side wall of the crystal slurry enters a crystal slurry discharge pipe G7, the solid content of discharged crystal slurry is 20 +/-5% by weight, the low solid content discharged crystal slurry reduces the risk of blockage of a discharge pipeline on the one hand, simultaneously reduces the solid content in circulating materials, reduces the load of a circulating pump and also reduces the risk of blockage of an evaporator tube nest.

The top overflow port of the cyclone 9 is connected with the overflow tank 12 through a cyclone overflow pipe G8, the overflow port at the upper part of the thickener 10 is connected with the overflow tank 12 through a thickener overflow pipe G10, the bottom outlet of the overflow tank 12 is connected with the inlet of a feed back pump B5 through a reflux mother liquor pipe G16, and the outlet pipeline of the feed back pump B5 is connected with a circulating evaporation pipeline.

The discharging of the crystal slurry is sent into a cyclone 9 by a discharging pump B4, and the cyclone 9 carries out third grading on the discharging of the sodium chloride crystal slurry; the solid content of the overflow of the cyclone is 5 +/-2 percent wt and enters an overflow tank 12, the solid content of the underflow of the cyclone is 30 +/-5 percent wt and enters a thickener 10, the thickener 10 carries out fourth grading on the underflow of the cyclone, the solid content of the overflow of the thickener is 3 +/-1 percent and enters an overflow tank 12, the solid content of the underflow of the thickener is 45 +/-3 percent wt and enters a centrifuge 11 for solid-liquid separation, and the content of particles with the thickness of more than or equal to 0.3mm in the feed of the centrifuge is more than or equal to 50 percent. Through the third and fourth grading, the particle size of the sodium chloride salt fed by the centrifuge is further improved, the solid-liquid ratio of the fed material by the centrifuge is improved, compared with the traditional process, the water content of the centrifuged salt is reduced by 3%, the energy consumption of the drying bed 17 is effectively reduced, meanwhile, the looseness of the fed material of the drying bed 17 is improved, the occurrence of the caking phenomenon in the drying bed 17 is basically avoided, and the quality of the final product is further improved.

The liquid phase outlet of the centrifuge 11 is connected with the inlet of the centrifuge mother liquor tank 13 through a centrifuge mother liquor pipe G13, the inlet of the centrifuge mother liquor tank 13 is further connected with a sodium chloride concentrated brine pipe G1, the inner cavity of the centrifuge mother liquor tank 13 is provided with a stirring device, the bottom outlet of the centrifuge mother liquor tank 13 is connected with the inlet of a centrifuge mother liquor pump B6 through a mother liquor tank discharge pipe G14, the outlet of the centrifuge mother liquor pump B6 is connected with the main inlet of a pipeline mixer 14, a forward-flow rotatable spiral is arranged in the pipeline mixer 14, an oxidant inlet is tangentially connected with the pipeline mixer 14, an oxidant injection inlet is connected with an oxidant injection pipe G15, the outlet of the pipeline mixer 14 is connected with the upper inlet of an oxidation tower 15, the circulating liquid outlet of the oxidation tower 15 is connected with the inlet of an oxidation tower circulating pump B7, the outlet of the oxidation tower circulating pump B7 is connected with the upper circulating liquid inlet and a built-in spray head of the oxidation tower 15, and the middle discharge outlet of the oxidation tower 15 is connected with the inlet of an overflow tank 12.

Mother liquor separated by the centrifuge 11 enters a centrifugal mother liquor tank 13 for buffering, another part of 20 +/-5 wt% sodium chloride concentrated brine from a sodium chloride concentrated brine pipe G1 is added into the centrifugal mother liquor tank 13, the temperature of the centrifugal mother liquor separated by the centrifuge 11 is 95 +/-5 ℃, the solid content is 5 +/-2 wt%, and after the low-temperature sodium chloride concentrated brine is mixed with the centrifugal mother liquor, a small amount of residual sodium chloride fine particle salt in the centrifugal mother liquor is dissolved and cooled to 60 +/-5 ℃. Centrifugal mother liquor pump B6 carries the centrifugal mother liquor in centrifugal mother liquor tank 13 to oxidation tower 15, and centrifugal mother liquor pump B6 outlet pipe is equipped with pipeline mixer 14, mixes with the strong oxidizer that gets into, and the centrifugal mother liquor after the misce bene carries out catalytic oxidation reaction in getting into oxidation tower 15, decomposes the organic matter, and oxidation tower 15 relies on external oxidation tower circulating pump B7 to realize centrifugal mother liquor circulation, and the oxidation reaction time of centrifugal mother liquor can reach 2 hours. The discharge of the oxidation tower enters an overflow tank 12 under the pressure difference, the overflow of the cyclone and the overflow of the thickener also enter the overflow tank 12, and the mixed materials are conveyed to a circulating evaporation pipe by a feed back pump B5 to participate in the circulation of secondary heat exchange evaporation crystallization. COD content in the sodium chloride strong brine is 200mg/L usually, get into the evaporation crystallization system after evaporating in succession, can cause the organic matter enrichment, influence product quality, this system degrades a small amount of organic matters of evaporation enrichment in to the centrifugal mother liquor once more through oxidation tower 15, can be with the COD content control in crystallizer 6 below 1000mg/L, effectively guarantee the quality of the sodium chloride salt of backward flow mother liquor evaporation crystallization output once more, guaranteed the continuity and the stability of system's production.

The moisture content of solid wet salt discharged by the centrifuge 11 is reduced to 2 +/-0.5%, the solid wet salt falls on the belt conveyor 16, a material stopper guiding the solid wet salt to an inlet of the drying bed 17 is arranged at an outlet end of the belt conveyor 16, and a reverse water-stop plate is arranged at the bottom of the belt conveyor 16. The belt conveyor 16 effectively ensures the loose and fast transportation of the centrifuged salt, the outlet of the belt conveyor 16 is guided into the inlet of the drying bed 17 by the material stopper, the salt loss in the conveying process is reduced, and then the salt is dried by hot air in the drying bed 17. When the centrifuge 11 washes, the belt conveyor 16 runs reversely, and the reversing water-stop sheet can effectively reduce the entrainment of the centrifuge washing water, effectively block the influence of the centrifuge washing water on the drying bed 17, and improve the operation stability of the drying bed 17.

The hot air inlet of the drying bed 17 is connected with the hot air outlet of the heat exchanger 22, the cold air inlet of the heat exchanger 22 is connected with the outlet of the air blower 21, the inlet of the air blower 21 is connected with a filtered air pipe G17, the heat medium inlet of the heat exchanger 22 is connected with a steam generation pipe G18, the heat medium outlet of the heat exchanger 22 is connected with a steam generation condensation water pipe G19, and the outlet of the steam generation condensation water pipe G19 is connected with a boiler water supply system. The blower 21 sends filtered air with the temperature of 20 +/-10 ℃ to the cold side of the heat exchanger 22, raw steam with the temperature of 160 +/-5 ℃ enters the hot side of the heat exchanger 22 to heat the filtered air to 120 +/-5 ℃ and is sent to the air inlet of the drying bed 17, condensed water generated after heat release is not polluted, and the condensed water enters a boiler water supply system from a raw steam condensed water pipe G19 to directly recover softened water and heat. The wet salt is dried by hot air in the drying bed 17, and the water content of the finished salt discharged from the drying bed 17 is less than or equal to 0.5 percent.

The top exhaust port of the drying bed 17 is connected with the side wall air inlet of the cyclone dust collector 18, the bottom outlet of the cyclone dust collector 18 guides out the product III G23 with the particle size of less than or equal to 0.1mm, the top outlet of the cyclone dust collector 18 is connected with the air inlet of the leaching tower 19 through a dust removal exhaust pipe G20, the bottom water outlet of the leaching tower 19 is connected with the inlet of a leaching tower circulating pump B8, the outlet of the leaching tower circulating pump B8 is connected with the upper spraying port of the leaching tower 19, the top exhaust port of the leaching tower 19 is connected with the inlet of an induced draft fan 20, and the outlet of the induced draft fan 20 is communicated with a waste gas treatment pipeline. The air outlet of the drying bed enters a cyclone separator, sodium chloride fine particle salt carried by the tail gas is further recovered, the yield and the recovery rate of the product are improved, the air outlet of the cyclone separator enters a leaching tower 19 for washing, a circulating pump B8 of the leaching tower is provided with a plurality of layers of opposite rotatable nozzles, and self-circulation spray washing is carried out through a circulating pump B8 of the leaching tower, so that the carrying of the tail gas is further reduced, and the difficulty in tail gas treatment is reduced.

The outlet of the drying bed 17 is connected with the inlet of the high-frequency vibrating screen 23, the dried sodium chloride salt enters the high-frequency vibrating screen 23 for screening, the high-frequency vibrating screen 23 is provided with an inclined double-layer screen, a product G21 with the grain size being more than or equal to 0.3mm is led out from the outlet of the oversize product, and the yield of the product G21 is more than or equal to 50%; the product II G22 with the grain size of 0.1-0.3 mm is led out from the middle outlet, the product III G23 with the grain size of less than or equal to 0.1mm is led out from the screen underflow outlet, and the yield of the product III G23 is less than or equal to 20%.

The brine grading, evaporating and crystallizing system increases crystallized salt particles by reducing evaporation speed, carrying out primary cyclone grading, overflowing and recycling, and carrying out secondary salt-precipitating and elutriating grading, and then conveying the crystallized salt particles to a cyclone 9 and a thickener 10 by a discharge pump B4 for three-time and four-time grading, so that the solid-liquid ratio and the granularity of the feed material of the centrifuge are further improved, the water content of the centrifuged salt is 2 +/-0.5%, a salt outlet of a drying bed is connected with a high-frequency vibrating screen 23 to grade the product, and the high-value and low-value added products are separated to obtain the high-value added product with the particle size of more than or equal to 0.3mm, the high-value added product is more than 50%, and the low-value added product with the particle size of less than or equal to 0.1mm is reduced to less than 20%.

The above description is only a preferred embodiment of the present invention, and not intended to limit the scope of the present invention. In addition to the above embodiments, the present invention may have other embodiments. All the technical solutions formed by adopting equivalent substitutions or equivalent transformations fall within the protection scope claimed by the present invention. The undescribed technical features of the present invention can be realized by or using the prior art, and are not described herein again.

Claims

1. A brine fractional evaporation crystallization system comprises an evaporator and a crystallizer, and is characterized in that: the crystallizer comprises a crystallizer main cylinder, the lower part of the crystallizer main cylinder is connected with a crystallizer lower cone, the lower port of the crystallizer lower cone is connected with an elutriation cylinder, the middle part of the side wall of the crystallizer main cylinder is provided with a crystallization circulation outlet, and the crystallizer lower cone is provided with a crystallization circulation inlet; the crystallization circulating outlet is connected with an inlet of an evaporation circulating pump through a circulating evaporation pipe, an outlet of the evaporation circulating pump is connected with a bottom inlet of an evaporator, and a top outlet of the evaporator is connected with the crystallization circulating inlet; a fresh material inlet is formed in the middle of the elutriation cylinder, a magma side wall outlet is formed in the circumference of the lower portion of the elutriation cylinder, and the magma side wall outlet is connected with a magma discharge pipe; an elutriation barrel clear liquid port is formed in the circumference of the upper portion of the elutriation barrel, and is connected with the circulating evaporation pipe.

2. The brine fractional evaporative crystallization system of claim 1, wherein: the crystallization circulating inlet is tangent to the side wall of the middle part of the lower cone of the crystallizer, and the root part of the crystallization circulating inlet is inclined upwards by 3-7 degrees.

3. The brine fractional evaporative crystallization system of claim 1, wherein: the magma discharge pipe links to each other with the entry of discharge pump, the export of discharge pump links to each other with the lateral wall entry of swirler, the bottom of swirler links to each other with the entry of stiff ware through swirler underflow pipe, the bottom of stiff ware passes through the stiff ware underflow pipe and links to each other with centrifuge's entry, centrifuge's discharge gate passes through the wet salt elephant trunk and docks with band conveyer, band conveyer's export links to each other with the entry of dry bed.

4. The brine fractional evaporative crystallization system of claim 3, wherein: the top overflow mouth of swirler passes through the swirler overflow pipe and links to each other with the overflow jar, the overflow mouth on stiff ware upper portion passes through the stiff ware overflow pipe and links to each other with the overflow jar, the bottom export of overflow jar passes through the backward flow mother liquor pipe and links to each other with the entry of feed back pump, the export pipeline of feed back pump with circulation evaporation pipeline links to each other.

5. The brine fractional evaporative crystallization system of claim 4, wherein: the liquid phase outlet of the centrifuge is connected with the inlet of a centrifuge mother liquor tank through a centrifuge mother liquor pipe, the inlet of the centrifuge mother liquor tank is also connected with a sodium chloride strong brine pipe, the inner cavity of the centrifugal mother liquor tank is provided with a stirring device, the bottom outlet of the centrifugal mother liquor tank is connected with the inlet of the centrifugal mother liquor pump through a mother liquor tank discharge pipe, the outlet of the centrifugal mother liquor pump is connected with the main inlet of the pipeline mixer, a spiral which can rotate along the flowing direction is arranged in the pipeline mixer, the pipeline mixer is tangentially connected with an oxidant inlet, the oxidant injection port is connected with an oxidant injection pipe, the outlet of the pipeline mixer is connected with the inlet at the upper part of the oxidation tower, and a circulating liquid outlet of the oxidation tower is connected with an inlet of an oxidation tower circulating pump, an outlet of the oxidation tower circulating pump is connected with an upper circulating liquid inlet of the oxidation tower and a built-in spray head, and a middle discharge hole of the oxidation tower is connected with an inlet of the overflow tank.

6. The brine fractional evaporative crystallization system of claim 3, wherein: a material stopper for guiding the solid wet salt to the inlet of the drying bed is arranged at the outlet end of the belt conveyor, and a reverse water-stop plate is arranged at the bottom of the belt conveyor; the outlet of the drying bed is connected with the inlet of a high-frequency vibrating screen, the high-frequency vibrating screen is provided with an inclined double-layer screen, a product I with the grain diameter of more than or equal to 0.3mm is led out from the oversize product outlet, and the yield of the product I is more than or equal to 50%; a second product with the grain size of 0.1-0.3 mm is led out from the middle outlet, a third product with the grain size of less than or equal to 0.1mm is led out from the screen underflow outlet, and the yield of the third product is less than or equal to 20%.

7. The brine fractional evaporative crystallization system of claim 3, wherein: the top gas vent of dry bed links to each other with cyclone's lateral wall air intake, cyclone's bottom export derives the product three that the particle diameter is less than or equal to 0.1mm, cyclone's top export links to each other through the air intake of dust removal exhaust pipe with the drip washing tower, the bottom outlet of drip washing tower links to each other with the entry of drip washing tower circulating pump, the export of drip washing tower circulating pump with the upper portion spraying mouth of drip washing tower links to each other, the top gas vent of drip washing tower links to each other with the entry of draught fan, the export and the exhaust-gas treatment pipeline of draught fan communicate with each other.