System for treating salt-containing wastewater

Abstract

The utility model discloses a system for treating salt-containing wastewater, which comprises pretreatment equipment and a mechanical vapor recompression (MVR) processor, the pretreatment equipment comprises a floatation tank, an adsorption tank and an ion exchanger, and the MVR processor comprises an evaporator and a vacuum rake dryer; the air floatation tank comprises a desilting device and an output device, the desilting device is used for scraping suspended solids on the upper layer of the wastewater in the air floatation tank and inputting the scraped suspended solids into the sludge tank, and the output device is used for outputting liquid on the lower layer of the wastewater in the air floatation tank to the adsorption tank; the adsorption tank is used for absorbing organic matters in the wastewater; the ion exchanger is used for adsorbing calcium and magnesium ions in the wastewater; the evaporator is used for heating and evaporating the wastewater treated by the ion exchanger to improve the salt concentration in the wastewater; the vacuum rake dryer is used for drying the wastewater and / or crystal substances separated out from the wastewater to obtain dried salt. According to the system, the salt yield of the wastewater treatment system is improved, and the waste of water resources is reduced.

Description

Technical Field

[0001] The utility model relates to the technical field of wastewater treatment, in particular to a system for treating saline wastewater. Background Art

[0002] With the acceleration of my country's industrialization, many industries generate large amounts of high-salt wastewater during production, typically with a salt content of 1% or more. This wastewater contains not only large amounts of suspended solids but also a large number of inorganic ions such as chloride, sodium, calcium, and sulfate, as well as some organic matter.

[0003] Improper treatment of high-salinity wastewater wastes resources and pollutes the ecological environment. Effective treatment of high-salinity wastewater can, on the one hand, produce recyclable salts with high utilization value and recyclable water resources, enabling resource reuse and effectively alleviating the pressure of water shortages. On the other hand, it can also reduce costs and increase efficiency for enterprises, reduce waste generation in chemical production processes, and achieve industrial upgrading and transformation while promoting the development of the environmental protection industry.

[0004] Therefore, there is an urgent need in the prior art to provide a technology for treating high-salt wastewater. Utility Model Content

[0005] The purpose of the present invention is to provide a system for treating saline wastewater, so as to at least partially solve the above-mentioned problems in the prior art.

[0006] To achieve the above-mentioned object, the utility model provides a system for treating saline wastewater, comprising a pretreatment device and a mechanical vapor recompression evaporation MVR processor, wherein the pretreatment device comprises an air flotation tank, a desilter, an adsorption tank, and an ion exchanger, and the MVR processor comprises an evaporator and a vacuum rake dryer;

[0007] Flotation tanks are used to store wastewater;

[0008] The desilter is used to scrape the upper suspended matter of the wastewater in the flotation tank, and the lower liquid of the wastewater in the flotation tank is output to the adsorption tank;

[0009] The adsorption tank is connected to the flotation tank, and adsorption resin is set inside to absorb organic matter in the wastewater;

[0010] The ion exchanger is connected to the adsorption tank, which is equipped with a strong acidic cation exchange resin to adsorb calcium and magnesium ions in the wastewater;

[0011] The evaporator is used to heat and evaporate the wastewater after treatment by the ion exchanger to increase the salt concentration in the wastewater;

[0012] The vacuum rake dryer is used to dry wastewater and / or crystals precipitated from wastewater to obtain dry salt.

[0013] In one embodiment, the system further comprises:

[0014] Sludge tank, used to store the upper suspended matter of wastewater in the flotation tank scraped by the desilter;

[0015] The compressor is used to compress the suspended matter in the sludge tank to obtain sludge and filtrate, and input the filtrate into the adsorption tank.

[0016] In one embodiment, the system further includes a dosing device, which fully contacts and mixes the wastewater delivered from the raw water equipment with the solid-liquid separation liquid and then inputs it into the flotation tank.

[0017] In one embodiment, the adsorption tank includes a main adsorption tank, a backup adsorption tank, and an adsorption switching device. When the adsorption effect of the main adsorption tank does not meet the preset conditions, the switching device switches to use the backup adsorption tank for adsorption; and / or

[0018] The ion exchanger includes a main ion exchanger, a backup ion exchanger, and an ion exchange switching device. When the adsorption effect of the main ion exchanger does not meet the preset conditions, the ion exchange switching device switches to using the backup ion exchanger.

[0019] In one embodiment, the MVR processor further comprises a first separator, a circulation heat exchanger, and a second separator;

[0020] The first separator is connected to the evaporator to perform flash separation on the wastewater after heating and evaporation treatment to further increase the salt concentration;

[0021] The circulating heat exchanger is connected to the first separator through a forced circulation pump to circulate heat for the wastewater after flash separation treatment, so that the wastewater temperature continues to rise and is output to the second separator after reaching the preset temperature condition;

[0022] The second separator is connected to the circulating heat exchanger to perform secondary flash separation on the wastewater;

[0023] The vacuum rake dryer dries the wastewater after secondary flash evaporation treatment and / or the crystals precipitated in the wastewater.

[0024] In one embodiment, the MVR processor further includes a condensate plate heat exchanger and a fresh steam plate heat exchanger, wherein the condensate plate heat exchanger and the fresh steam plate heat exchanger successively exchange heat with the wastewater to increase the temperature of the wastewater;

[0025] The evaporator is connected to the fresh steam heat exchanger to heat and evaporate the wastewater after heat exchange treatment.

[0026] In one embodiment, the MVR processor further includes a thickener located between the second separator and the vacuum rake dryer, configured to receive the material crystals initially formed in the second separator, increase the consistency of the material crystals, and then output them to the vacuum rake dryer.

[0027] In one embodiment, the jacket and the rotating shaft of the vacuum rake dryer include heat-conducting oil to accelerate the drying and precipitation of salt.

[0028] In one embodiment, after the first separator performs flash separation on the heated wastewater, the generated steam is compressed by a compressor and then enters the evaporator and the circulating heat exchanger to continue heating the wastewater as a heat source.

[0029] In one embodiment, the vacuum rake dryer is connected to a vacuum pump, and the vacuum pump is used to draw negative pressure for the vacuum rake dryer.

[0030] Compared with the prior art, the present invention has at least the following advantages:

[0031] In the utility model, the upper suspended matter of the saline wastewater is first removed through the flotation tank, and then the organic matter in the water is adsorbed by the adsorption resin, and the calcium and magnesium ions in the wastewater are adsorbed by the ion exchanger, thereby improving the evaporation and crystallization effect of the saline wastewater and preventing the organic matter and calcium and magnesium ions in the saline wastewater from damaging the MVR processor; and through the combination of the evaporator and the vacuum rake dryer, the salt output of the wastewater treatment system can be increased, the salt content of the treated water can be reduced, the treated water can be recycled, and the waste of water resources can be reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 This is a schematic structural diagram of a system for treating saline wastewater provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0033] In order to help those skilled in the art better understand the present invention, the following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts should fall within the scope of protection of the present invention.

[0034] It should be noted that the terms "first," "second," and the like in the specification and claims of the present invention and the accompanying drawings are used to distinguish similar objects and are not necessarily used to describe a specific order or precedence. It should be understood that the terms used in this manner can be interchanged where appropriate to facilitate understanding of the embodiments of the present invention described herein. In addition, the terms "including," "having," and any variations thereof are intended to cover non-exclusive inclusions. For example, a product or device comprising a series of units is not necessarily limited to those units explicitly listed, but may include other units that are not explicitly listed or that are inherent to these products or devices.

[0035] In this utility model, terms such as "upper," "lower," "left," "right," "front," "back," "top," "bottom," "inner," "outer," "center," "vertical," "horizontal," "transverse," and "longitudinal" indicate positions or locations based on the positions or locations shown in the accompanying drawings. These terms are primarily intended to better describe the utility model and its embodiments and are not intended to limit the devices, elements, or components indicated to having a specific orientation, or to being constructed or operated in a specific orientation.

[0036] Furthermore, some of the above terms may be used to express other meanings besides indicating a position or location. For example, the term "on" may also be used to indicate a dependency or connection in certain circumstances. Those skilled in the art will understand the specific meanings of these terms in this utility model based on the specific circumstances.

[0037] Furthermore, the terms "installed," "disposed," "provided with," "connected," "connected," and "socketed" should be interpreted broadly. For example, they can refer to fixed connections, removable connections, or integral structures; mechanical connections or electrical connections; direct connections, indirect connections through an intermediary, or internal communication between two devices, elements, or components. Those skilled in the art will understand the specific meanings of these terms in this utility model based on the specific circumstances.

[0038] It should be noted that, in the absence of conflict, the embodiments and features of the embodiments of the present invention can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0039] Example 1

[0040] The present invention provides a system for treating saline wastewater, which includes a pretreatment device and an MVR processor, wherein the pretreatment device includes an air flotation tank, a desilter, an adsorption tank, and an ion exchanger, and the MVR processor includes an evaporator and a vacuum rake dryer;

[0041] Flotation tanks are used to store wastewater;

[0042] The desilter is used to scrape the upper suspended matter of the wastewater in the flotation tank, and the lower liquid of the wastewater in the flotation tank is output to the adsorption tank;

[0043] The adsorption tank is connected to the flotation tank, and adsorption resin is set inside to absorb organic matter in the wastewater;

[0044] The ion exchanger is connected to the adsorption tank, which is equipped with a strong acidic cation exchange resin to adsorb calcium and magnesium ions in the wastewater;

[0045] The evaporator is used to heat and evaporate the wastewater after treatment by the ion exchanger to increase the salt concentration in the wastewater;

[0046] The vacuum rake dryer is used to dry wastewater and / or crystals precipitated from wastewater to obtain dry salt.

[0047] Among them, the adsorption resin used to absorb organic matter in wastewater includes D101 macroporous adsorption resin or XAD16 macroporous adsorption resin, and the strong acid cation exchange resin includes 001×7 strong acid cation exchange resin or 001×8 strong acid cation exchange resin.

[0048] In one embodiment, the system also includes a sludge tank and a compressor. The sludge tank is used to store the upper layer of suspended matter in the wastewater from the flotation tank scraped by the desilter; the compressor is used to compress the suspended matter in the sludge tank to produce sludge and filtrate, which is then fed into an adsorption tank. The compressed sludge can be packaged and shipped, and the compressed liquid can be fed into the adsorption tank for wastewater treatment, thereby increasing salt production and wastewater utilization efficiency. It will be readily understood that in other embodiments, the compressor may not be included, and the sludge tank may only store sludge without the need for compression. Alternatively, the compressor may compress the sludge in the sludge tank, but the compressed liquid does not need to be fed into the adsorption tank.

[0049] In one embodiment, the adsorption tank may include a primary adsorption tank, a backup adsorption tank, and an adsorption switching device. When the adsorption efficiency of the primary adsorption tank fails to meet preset conditions, the switching device switches to the backup adsorption tank for adsorption. The adsorption tank may also include an adsorption efficiency detector, such as a COD detection and display instrument, to determine whether a switch is necessary. After the switch, the primary adsorption tank can be cleaned, so that when the adsorption efficiency of the backup adsorption tank fails to meet preset conditions, the primary adsorption tank can be switched back to the primary adsorption tank.

[0050] In one embodiment, a desorption operation is required for the adsorption tank after adsorption has completed, using steam as the desorbent. First, the valves on the water inlet and outlet lines of the adsorption tank are closed, and the valves on the steam inlet and outlet lines of the tank are opened to perform desorption. Steam enters from the top and exits from the bottom. The desorbed liquid is sent to a desorption liquid tank for storage and periodic delivery. The steam used as the desorbent is preferably secondary steam.

[0051] In one embodiment, the ion exchanger may include a main ion exchanger, a backup ion exchanger, and an ion exchange switching device. When the adsorption effect of the main ion exchanger does not meet the preset conditions, the ion exchange switching device switches to using the backup ion exchanger. The ion exchanger may also include an adsorption effect detector, which determines whether switching is required by the adsorption effect detector. For example, a water hardness analyzer can be used as an adsorption effect detector, and a water hardness analyzer is set at the outlet of the ion exchanger. If the water hardness analyzer shows that the increase in water hardness meets the preset conditions, the ion exchanger is switched. In one embodiment, the switching device can select the ion exchanger to be entered by controlling the opening and closing of the input valve of the ion exchanger.

[0052] In one embodiment, a desorption operation is performed on an ion exchanger that has completed adsorption. A 10% sodium chloride solution is used as the desorbent. First, the valves on the water inlet and outlet lines of the ion exchanger are closed, and the valves on the desorbent inlet and outlet lines of the exchanger are opened to perform desorption. The desorbent enters from the bottom and exits from the top. This method prevents resin compaction within the exchanger and removes suspended matter trapped in the resin layer during operation. The desorbed liquid is stored in a desorption liquid tank and shipped periodically.

[0053] In one embodiment, the MVR processor further comprises a first separator, a circulation heat exchanger, and a second separator;

[0054] The first separator is connected to the evaporator to perform flash separation on the wastewater after heating and evaporation treatment to further increase the salt concentration;

[0055] The circulating heat exchanger is connected to the first separator through a forced circulation pump to circulate heat for the wastewater after flash separation treatment, so that the wastewater temperature continues to rise and is output to the second separator after reaching the preset temperature condition;

[0056] The second separator is connected to the circulating heat exchanger to perform secondary flash separation on the wastewater;

[0057] The vacuum rake dryer dries the wastewater after secondary flash evaporation treatment and / or the crystals precipitated in the wastewater.

[0058] In one embodiment, the evaporator is a falling film evaporator, which rapidly heats the wastewater. The generated steam is compressed by a compressor and reused. The wastewater with increased salt concentration then enters a circulating heat exchanger for further heating and concentration. The circulating heat exchanger is preferably a forced circulation heat exchanger. A falling film circulation pump can be used to continuously circulate the wastewater within the falling film evaporator, thereby improving evaporation efficiency.

[0059] The first separator can be a falling film separator, which flash-evaporates the saline wastewater. Part of the liquid is vaporized into water vapor and enters the secondary separation tank. The flash-evaporated wastewater enters a circulating heat exchanger for further heating. Once it reaches a preset temperature, it enters the second separator for flash evaporation. Once the salt concentration in the wastewater reaches the required discharge concentration, it is pumped to a vacuum rake dryer via a discharge pump.

[0060] In one embodiment, the MVR processor also includes a condensate plate heat exchanger and a fresh steam plate heat exchanger, wherein the condensate plate heat exchanger and the fresh steam plate heat exchanger successively exchange heat with the wastewater to increase the temperature of the wastewater; the evaporator is connected to the fresh steam heat exchanger to heat and evaporate the wastewater after heat exchange treatment.

[0061] In one embodiment, the MVR processor also includes a thickener located between the second separator and the vacuum rake dryer. This thickener receives the initial crystals formed in the second separator, increases their consistency, and then delivers them to the vacuum rake dryer. Specifically, after the brine crystallizes in the second separator, it enters the thickener and, after a period of continued crystallization, is delivered to the vacuum rake dryer for drying.

[0062] In one embodiment, heat transfer oil is introduced into the jacket and shaft of the vacuum rake dryer to accelerate the drying and precipitation of salt. The evaporated water is condensed and reused. The condenser's circulating water can then be reused as heat transfer water, avoiding energy waste.

[0063] In one embodiment, after the heated wastewater is flash-evaporated and separated by the primary separator, the steam enters the circulating heat exchanger and serves as a heat source to continue heating the wastewater.

[0064] In one embodiment, the vacuum rake dryer is connected to a vacuum pump, and the vacuum pump is used to draw negative pressure for the vacuum rake dryer.

[0065] In one embodiment, the fresh steam from the boundary area enters the evaporator, the circulating heat exchanger and the fresh steam heat exchanger, and steam is generated in the heated wastewater. The steam is then flashed through the first separator and the second separator to obtain secondary steam. The secondary steam enters the secondary separation tank, and the liquefied liquid enters the liquid collecting tank. The steam enters the compressor to increase the temperature and pressure. The liquid liquefied in the compressor enters the liquid collecting tank. The secondary steam after temperature and pressure increase enters the evaporator, the circulating heat exchanger, etc., and exchanges heat with the wastewater solution to become condensed water. It flows by gravity to the distilled water tank and is pumped to the condensed water plate heat exchanger by the distilled water pump. After its heat is recovered, it is sent to the boundary area (the boundary area of ​​the production device). Secondary steam can also enter adsorption tank A 8 and adsorption tank B 9 as a desorbent and output as a desorbed liquid. Among them, the fresh steam from the boundary area is only used at the start of operation. After the system is operating normally, the secondary steam can meet the system needs, which can greatly reduce energy consumption.

[0066] Among them, non-condensable gas is also produced in the evaporator and forced circulation heat exchanger. The non-condensable gas is sucked into the rake dryer under the action of the vacuum pump, and then enters the gas-liquid separator through the heat exchanger with the water vapor evaporated from the rake dryer to complete gas-liquid separation and then is stored in the non-condensable gas tank and finally discharged outside the boundary area.

[0067] The system for treating saline wastewater provided by the utility model first removes suspended matter in the upper layer of the saline wastewater through a flotation tank, then uses an adsorption resin to adsorb organic matter in the water, and uses an ion exchanger to adsorb calcium and magnesium ions in the wastewater, thereby improving the evaporation and crystallization effects of the saline wastewater and preventing the organic matter and calcium and magnesium ions in the saline wastewater from damaging an MVR processor. Furthermore, the combination of the evaporator and the vacuum rake dryer can increase the salt output of the wastewater treatment system, reduce the salt content of the treated water, and allow the treated water to be recycled, thereby reducing the waste of water resources.

[0068] Example 2

[0069] This embodiment provides a system for treating saline wastewater. This system differs from Example 1 in that it also includes a dosing device. This device thoroughly mixes wastewater delivered from a raw water system with a solid-liquid separation solution before feeding the solution into a flotation tank. The raw water system, for example, is a wastewater discharge system for chemical production. The dosing device is connected to the raw water system to treat the wastewater.

[0070] In other implementations, the dosing device may also add solid-liquid separation liquid into the flotation tank, so that the wastewater in the flotation tank presents upper and lower stratification.

[0071] In one embodiment, the dosing device includes a premixer and a dosing reactor. The raw water device can be a raw water tank. Raw water in the raw water tank is pumped to the premixer via a raw water pump. It fully contacts the liquid medicine delivered from the dosing reactor and then enters the flotation tank for solid-liquid separation. The added agent can be lime water or phosphate. Dosing effectively reduces the calcium and magnesium ion content and hardness of the raw water.

[0072] In the flotation tank, solid particles float to the water surface under the capture and adsorption of a large number of microbubbles, and are collected by the scraper and sent to the sludge tank. When the sludge tank reaches a certain liquid level, the sludge pump sends it to the filter press for mud removal. The treated sludge is packaged and sent out, and the filtrate is sent to the adsorption tank, which is filled with adsorption resin to complete the adsorption of organic matter; the clarified liquid in the flotation tank directly enters the adsorption tank; after filtration, it enters the ion exchanger, which is filled with strong acidic cation exchange resin to achieve further adsorption of calcium and magnesium ions in the water, ensuring that the hardness of the raw water is reduced to a minimum, preventing it from causing scaling of equipment in subsequent sections. The raw water that has passed the pretreatment is sent to the brine tank of the MVR processor.

[0073] Example 3

[0074] The present invention provides a specific example of a system for treating saline wastewater. The system includes a pretreatment device and an MVR processor, such as Figure 1 As shown, the pretreatment equipment includes a raw water tank 1, a dosing reactor 2, a premixer 3, a flotation tank 4, a scraper 5, a sludge tank 6, a filter press 7, an adsorption tank A 8, an adsorption tank B 9, a desorbent tank 10, an ion exchanger A 11, an ion exchanger B 12, a desorption liquid tank 13, a raw water pump 14, a sludge pump 15, and a desorbent pump 16.

[0075] The raw water in the raw water tank 1 is sent to the premixer 3 by the raw water pump 14 to fully contact with the liquid medicine delivered by the dosing reactor 2, and then enters the flotation tank 4 for solid-liquid separation. The upper suspended matter (usually solid particles) is collected by the scraper 5 and sent to the sludge tank 6. When the sludge tank 6 reaches a certain liquid level, the sludge pump 15 sends it to the filter press 7 for mud removal. The treated sludge is packaged and sent out, and the filtrate is sent to the adsorption tank A 8 or the adsorption tank B 9, which is filled with adsorption resin to complete the adsorption of organic matter; the lower layer liquid in the flotation tank 4 (such as clarified liquid) directly enters the adsorption tank, and after adsorption filtration, it enters the ion exchanger A11 or the ion exchanger B12, which is filled with strong acidic cation exchange resin to achieve further adsorption of calcium and magnesium ions in the water, ensuring that the hardness of the raw water is reduced to a minimum. The raw water that has passed the pretreatment is sent to the brine tank 17 of the MVR processor.

[0076] After adsorption is complete, the adsorption tank needs to be desorbed. The desorbent is secondary steam generated by the compressor. First, close the valves on the water inlet and outlet pipes of the adsorption tank, and open the valves on the steam inlet and outlet pipes of the tank to perform desorption. Steam enters from the top and exits from the bottom. The desorbed liquid is sent to the desorption liquid tank for storage and regular delivery.

[0077] The ion exchanger, which has completed adsorption, needs to undergo desorption. A 10% sodium chloride solution is used as the desorbent. First, close the valves on the water inlet and outlet pipes of the ion exchanger and open the valves on the desorbent inlet and outlet pipes. Desorption is performed using a bottom-in, top-out method. This method prevents resin compaction within the exchanger and removes suspended solids trapped in the resin layer during operation. The desorbed liquid is stored in a desorption liquid tank and shipped periodically.

[0078] Among them, the MVR processor mainly includes a brine tank 17, a brine pump 34, a condensate plate heat exchanger 18, a fresh steam plate heat exchanger 19, a falling film evaporator 20, a falling film separator 21, a forced circulation heat exchanger 22, a crystallizer 23, a thickener 24, a vacuum rake dryer 25, a heat exchanger 26, an air-water separator 27, a water tank 28, a non-condensable gas tank 29, a secondary separation tank 30, a compressor 31, a liquid collecting tank 32, a distilled water tank 33, a falling film circulation pump 35, a forced circulation pump 36, a discharge pump 37, a water pump 38, a vacuum pump 39, a liquid collecting pump 40 and a distilled water pump 41.

[0079] The brine in the brine tank 17 is heated by two plate heat exchangers and then enters the falling film evaporator 20 for heating. The heated solution flows by gravity to the falling film separator 21 for flash separation. The flashed steam is compressed by the compressor 31 and reused for a second time. The brine with increased concentration is pumped into the forced circulation heat exchanger 22 for further heating to increase the concentration. After crystallization in the crystallizer 23, it enters the thickener 24. After a period of continued crystallization, it is discharged to the vacuum rake dryer 25 for drying. Preferably, a vacuum pump 39 is used to draw negative pressure to the vacuum rake dryer 25 to extract the non-condensable gas in the system. The boiling point of the solution is effectively reduced under negative pressure conditions, and the evaporation efficiency of the liquid in the material is accelerated.

[0080] In one embodiment, heat transfer oil is introduced into the jacket and the rotating shaft of the vacuum rake dryer 25 as a heating medium to accelerate the drying and precipitation of salts. The evaporated water is condensed and sent to the water tank 28 for reuse.

[0081] In this embodiment, brine from brine tank 17 is pumped via brine pump 34 into condensate plate heat exchanger 18. There, the high-salt brine exchanges heat with steam condensate, raising its temperature using the heat from the steam condensate. The brine then enters fresh steam plate heat exchanger 19, where it exchanges heat with fresh steam, further raising its temperature. The brine then enters falling film evaporator 20 for further heating and evaporation. Falling film circulation pump 35 continuously circulates the brine within the falling film evaporator, improving evaporation efficiency. The brine then undergoes flash evaporation in falling film separator 21, partially vaporizing into water vapor that enters secondary separation tank 30. A wire mesh demister is located within secondary separation tank 30. When the water vapor carrying mist passes through the mesh at a certain speed, the mist is trapped on the mesh surface. Gravity forces the mist to coalesce into droplets. When the aggregated droplets become large enough that their own gravity exceeds the combined force of the gas's upward force and the liquid's surface tension, the droplets separate and fall from the filaments. After the gas passes through the wire mesh demister, it basically contains no mist.

[0082] At this point, the brine concentration in the falling film separator 21 continues to increase. After reaching the required discharge concentration, it is transferred to the forced circulation heat exchanger 22 via the forced circulation pump 36 for further heating. The brine solution then enters the crystallizer 23 for flash evaporation. The vaporized water vapor and the secondary steam generated by the falling film separator enter the secondary separation tank 30. The brine concentration in the crystallizer 23 continues to increase. After reaching the required discharge concentration, it is fed by the discharge pump 37 to the thickener 24 to increase the material consistency. The material is then discharged to the vacuum rake dryer 25 for drying. The generated water vapor is pre-cooled by the heat exchanger, enters the gas-liquid separator, and is pumped out. The salt produced after drying is packaged and shipped.

[0083] The fresh steam from the boundary area enters the falling film evaporator 20 , the circulating heat exchanger 22 and the fresh steam heat exchanger 19 .

[0084] Steam is generated from the heated wastewater, which then flashes through the falling film separator 21 and crystallizer 23 to produce secondary steam. This secondary steam enters the secondary separation tank 30, and the liquefied liquid (e.g., the mist removed by the filter) enters the liquid collection tank 32. The steam then enters the compressor 31 to increase its temperature and pressure. The liquefied liquid in the compressor 31 enters the liquid collection tank 32. The heated and pressurized secondary steam enters the falling film evaporator 20 and the circulating heat exchanger 22, where it exchanges heat with the wastewater solution and becomes condensed water. This condensed water flows by gravity to the distilled water tank 33, where it is pumped by the distilled water pump 41 to the condensed water plate heat exchanger 18. The heat is recovered and then sent to the boundary area, the boundary area of ​​the production facility, for subsequent processing. The secondary steam can also be used as a desorbent and enter adsorption tanks A 8 and B 9, where it is output as desorbed liquid. The fresh steam from the boundary area is only used during startup. Once the system is operating normally, the secondary steam can meet system needs, significantly reducing energy consumption.

[0085] Non-condensable gas is also produced in the falling-film evaporator 20 and the forced-circulation heat exchanger 22. This non-condensable gas is drawn into the rake dryer 25 by the action of a vacuum pump 39. It then enters the gas-liquid separator 27 through the heat exchanger 26, along with the water vapor evaporated from the rake dryer 25. After gas-liquid separation, it is stored in the non-condensable gas tank 29 and finally discharged outside the boundary area for venting. The liquid in the gas-liquid separator 27 is pumped into the water tank 28 by a water pump 38.

[0086] Heat exchanger 26 adopts a shell-and-tube heat exchanger. In this heat exchanger, the medium entering the tube side is the water vapor evaporated from the rake dryer and the non-condensable gas produced by the falling film evaporator and the forced circulation heat exchanger; the medium entering the shell side is circulating cooling water, which passes through the heat exchanger in a bottom-in and top-out manner to ensure sufficient heat exchange effect. Figure 1 As shown in the figure, CWS refers to circulating cooling water supply water and CWR refers to circulating cooling water return water.

[0087] In the present invention, fresh steam is only used at the start of operation. After the system is operating normally, the secondary steam generated by the system itself can meet the system needs, which can greatly reduce energy consumption.

[0088] The system for treating saline wastewater provided by the utility model first removes suspended matter in the upper layer of the saline wastewater through a flotation tank, then uses an adsorption resin to adsorb organic matter in the water, and uses an ion exchanger to adsorb calcium and magnesium ions in the wastewater, thereby improving the evaporation and crystallization effects of the saline wastewater and preventing the organic matter and calcium and magnesium ions in the saline wastewater from damaging an MVR processor. Furthermore, the combination of the evaporator and the vacuum rake dryer can increase the salt output of the wastewater treatment system, reduce the salt content of the treated water, and allow the treated water to be recycled, thereby reducing the waste of water resources.

[0089] Finally, it should be noted that the above embodiments are intended only to illustrate the technical solutions of the present invention and are not intended to limit them. Those skilled in the art will appreciate that modifications may be made to the technical solutions described in the above embodiments, or that some of the technical features therein may be replaced with equivalents; such modifications or replacements do not deviate from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A system for treating saline wastewater, characterized in that: It includes pretreatment equipment and mechanical vapor recompression evaporation MVR processor, wherein the pretreatment equipment includes flotation tank, desilter, adsorption tank, and ion exchanger, and the MVR processor includes evaporator and vacuum rake dryer; Flotation tanks are used to store wastewater; The desilter is used to scrape the upper suspended matter of the wastewater in the flotation tank, and the lower liquid of the wastewater in the flotation tank is output to the adsorption tank; The adsorption tank is connected to the flotation tank, and adsorption resin is set inside to absorb organic matter in the wastewater; The ion exchanger is connected to the adsorption tank, which is equipped with a strong acidic cation exchange resin to adsorb calcium and magnesium ions in the wastewater; The evaporator is used to heat and evaporate the wastewater after treatment by the ion exchanger to increase the salt concentration in the wastewater; The vacuum rake dryer is used to dry wastewater and / or crystals precipitated from wastewater to obtain dry salt.

2. The system for treating saline wastewater according to claim 1, characterized in that: Also includes: Sludge tank, used to store the upper suspended matter of wastewater in the flotation tank scraped by the desilter; The compressor is used to compress the suspended matter in the sludge tank to obtain sludge and filtrate, and input the filtrate into the adsorption tank.

3. The system for treating saline wastewater according to claim 1, characterized in that: It also includes a dosing device, which fully contacts and mixes the wastewater transported by the raw water equipment with the solid-liquid separation liquid and then inputs it into the flotation tank.

4. The system for treating saline wastewater according to any one of claims 1 to 3, characterized in that: The adsorption tank includes a main adsorption tank, a backup adsorption tank, and an adsorption switching device. When the adsorption effect of the main adsorption tank does not meet the preset conditions, the switching device switches to use the backup adsorption tank for adsorption; and / or The ion exchanger includes a main ion exchanger, a backup ion exchanger, and an ion exchange switching device. When the adsorption effect of the main ion exchanger does not meet the preset conditions, the ion exchange switching device switches to using the backup ion exchanger.

5. The system for treating saline wastewater according to claim 1, characterized in that: The MVR processor also includes a first separator, a circulating heat exchanger, and a second separator; The first separator is connected to the evaporator to perform flash separation on the wastewater after heating and evaporation treatment to further increase the salt concentration; The circulating heat exchanger is connected to the first separator through a forced circulation pump to circulate heat for the wastewater after flash separation treatment, so that the wastewater temperature continues to rise and is output to the second separator after reaching the preset temperature condition; The second separator is connected to the circulating heat exchanger to perform secondary flash separation on the wastewater; The vacuum rake dryer dries the wastewater after secondary flash evaporation treatment and / or the crystals precipitated in the wastewater.

6. The system for treating saline wastewater according to claim 5, characterized in that: The MVR processor also includes a condensate plate heat exchanger and a fresh steam plate heat exchanger, wherein the condensate plate heat exchanger and the fresh steam plate heat exchanger successively exchange heat with the wastewater to increase the temperature of the wastewater; The evaporator is connected to the fresh steam heat exchanger to heat and evaporate the wastewater after heat exchange treatment.

7. The system for treating saline wastewater according to claim 5, characterized in that: The MVR processor also includes a thickener located between the second separator and the vacuum rake dryer, which is used to receive the material crystals initially formed in the second separator, increase the consistency of the material crystals, and then output them to the vacuum rake dryer.

8. The system for treating saline wastewater according to any one of claims 5 to 7, characterized in that: The jacket and shaft of the vacuum rake dryer contain heat-conducting oil to accelerate the drying and precipitation of salt.

9. The system for treating saline wastewater according to any one of claims 5 to 7, characterized in that: After the first separator performs flash evaporation separation on the heated wastewater, the generated steam is compressed by the compressor and then enters the evaporator and circulating heat exchanger to continue heating the wastewater as a heat source.

10. The system for treating saline wastewater according to any one of claims 5 to 7, characterized in that: The vacuum rake dryer is connected to a vacuum pump, and the vacuum pump is used to pump negative pressure for the vacuum rake dryer.

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