System and method for prolonging operation of carnallite crystallization device

Abstract

The invention discloses a system and a method for prolonging operation of a carnallite crystallization device. The system comprises a carnallite crystallization device, a water inlet of the carnallite crystallization device is connected with a high-salinity water pipeline, and the carnallite crystallization device is configured to separate a saturated salt solution and secondary steam from the high-salinity water; the vacuum crystallization device is connected with an outlet of the carnallite crystallization device, the vacuum crystallization device is configured to pump out secondary steam, the vacuum device comprises a gas return pipeline, and the gas return pipeline is connected with a connecting pipeline between the carnallite crystallization device and the vacuum crystallization device; and the rotary drum drying device is connected with the carnallite crystallization device, and the rotary drum drying device is configured to pump out the saturated salt solution and separate salt in the saturated salt solution. Through cooperation of the vacuum crystallization device and the rotary drum drying device, the operation time of the carnallite crystallization device can be effectively prolonged, the maintenance and shutdown cost of the carnallite crystallization device can be reduced, and the environmental protection property of heavy salt water treatment can be improved.

Description

Technical Field

[0001] This invention relates to the field of extending the operation of a mixed salt crystallization device, and more particularly to a system and method for extending the operation of a mixed salt crystallization device. Background Technology

[0002] The coal chemical industry often generates large amounts of high-salinity wastewater during coal gasification, liquefaction, and the production of coal-based chemicals. This high-salinity wastewater typically contains high concentrations of dissolved salts, especially nitrates, chlorides, and sulfates. In many cases, the accumulation of these salts can adversely affect equipment, causing corrosion, scaling, and blockage. Scaling not only reduces equipment efficiency but can also lead to equipment downtime or even damage, resulting in high maintenance and downtime costs for businesses.

[0003] In the coal chemical industry, treating wastewater with high salt concentrations is a critical environmental issue. With advancements in coal chemical technology, many enterprises have adopted mixed salt crystallizers to treat end-of-pipe saline wastewater and separate dissolved salts. Existing high-salinity wastewater treatment technologies largely rely on physical, chemical, or combined methods, such as evaporation crystallization, reverse osmosis, and ion exchange. While these methods have achieved some success in certain situations, the excessively high salt concentration in mixed salt crystallizers often leads to crystallization and scaling during prolonged operation. This scaling not only reduces crystallizer efficiency, resulting in frequent maintenance and low overall efficiency, but also, because existing crystallizers typically operate under normal atmospheric pressure, their crystallization efficiency and equipment stability gradually decline over time, leading to a shortened operating cycle. The primary cause of scaling is the gradual increase in salt concentration inside the crystallizer, which easily deposits scale on the crystallizer walls. Once scaling occurs, it obstructs flow within the crystallizer and can even block the entire treatment system, causing equipment shutdown. Existing technologies typically employ physical cleaning and chemical cleaning methods to remove scale, but these methods have certain limitations, such as high cleaning frequency, high cost, and damage to equipment. Summary of the Invention

[0004] The present invention aims to solve at least one of the technical problems existing in the prior art or related art.

[0005] In view of this, the present invention provides a system and method for extending the operation of a mixed salt crystallization device. The system, through the cooperation of a vacuum crystallization device and a rotary drum drying device, can effectively extend the operating time of the mixed salt crystallization device and reduce the maintenance and downtime costs of the mixed salt crystallization device. On the other hand, it can also improve the environmental friendliness of high saline treatment. In addition to being applied to high saline treatment in the coal chemical industry, the system of this application can also be applied to wastewater treatment in other industries, making it easy to promote.

[0006] Specifically, the following technical solutions are included: An embodiment of the first aspect of the present invention provides a system for extending the operation of a mixed salt crystallization apparatus, wherein the system comprises: A mixed salt crystallization device, wherein the inlet of the mixed salt crystallization device is connected to a high-salt water pipeline, and the mixed salt crystallization device is configured to separate the high-salt water into a saturated salt solution and secondary steam; A vacuum crystallization device is connected to the outlet of the mixed salt crystallization device. The vacuum crystallization device is configured to extract the secondary steam. The vacuum device includes a return gas pipeline, which is connected to the connecting pipeline between the mixed salt crystallization device and the vacuum crystallization device. A rotary drum drying device is connected to the mixed salt crystallization device. The rotary drum drying device is configured to extract the saturated salt solution and separate the salts in the saturated salt solution.

[0007] Optionally, the mixed salt crystallization apparatus includes: A crystallizer, connected to the high-salt water pipeline, is configured to separate the high-salt water into a saturated salt solution and secondary steam. A heater is disposed on one side of the crystallizer, and the outlet of the heater is connected to the middle position of the crystallizer; A circulation pump is installed on the outlet pipe of the crystallizer, and the outlet of the circulation pump is connected to the inlet of the heater, supplying at least a portion of the saturated salt solution to the heater; A feed pump is installed on the outlet pipe of the crystallizer. The feed pump is connected in parallel with the circulation pump. The feed pump is configured to transport the saturated salt solution to the rotary drum drying device. A condenser, the inlet of which is connected to the gas phase pipeline of the crystallizer, and the outlet of which is connected to the vacuum crystallization device.

[0008] Optionally, the mixed salt crystallization apparatus further includes: A distillation tank is connected to the condensate pipe of the condenser. The distillation tank is configured to collect the condensate produced by the condenser. The outlet of the distillation tank is connected to an external pump.

[0009] Optionally, the vacuum crystallization apparatus includes: A first liquid ring vacuum pump and a second liquid ring vacuum pump, the gas phase inlets of which are both connected to the pipeline of the secondary steam. A gas-liquid separator, wherein the liquid phase inlet of the gas-liquid separator is connected to the gas phase outlets of the first liquid ring vacuum pump and the second liquid ring vacuum pump respectively, the first gas phase outlet of the gas-liquid separator is connected to an external discharge pipeline, and the second gas phase outlet of the gas-liquid separator is connected to a return gas pipeline; A plate heat exchanger, wherein the outlet of the plate heat exchanger is connected to the liquid phase inlet of the first liquid ring vacuum pump and the second liquid ring vacuum pump respectively, the inlet of the plate heat exchanger is connected to the water supply line of the working fluid, and the liquid phase outlet of the gas-liquid separator is connected to the water return line of the working fluid. A return gas regulating valve is provided, the inlet of which is connected to the return gas pipeline, and the outlet of which is connected to the gas phase inlet of the first liquid ring vacuum pump and the second liquid ring vacuum pump, respectively.

[0010] Optionally, the drum drying device includes: A rotary drum dryer is located downstream of the mixed salt crystallization device, and the rotary drum dryer is configured to separate the saturated salt solution to obtain solid salt and vapor; A water bath dust collector is connected to the gas phase pipeline of the rotary drum dryer, and the water bath dust collector is configured outside the system to control the steam. A dehumidifying fan is disposed between the water bath dust collector and the rotary drum dryer, and the dehumidifying fan is configured to deliver the steam to the water bath dust collector.

[0011] A second aspect of the present invention provides a method for extending the operation of a mixed salt crystallization apparatus, utilizing the above-described system, the method comprising the following steps: Based on the mixed salt crystallization device, high-salt water is separated into saturated salt solution and secondary steam; Based on the vacuum crystallization device, the secondary steam is extracted, and the pressure inside the mixed salt crystallization device is adjusted to a negative pressure working environment; Based on the aforementioned drum drying device, the saturated salt solution is decomposed into solid salt and vapor.

[0012] Optionally, the mixed salt crystallization apparatus includes a crystallizer, a heater, a circulating pump, a feed pump, a condenser, and a distillation tank, wherein separating the high-salt water into a saturated salt solution and secondary steam includes: The high-salt water enters the crystallizer under negative pressure, and the steam formed enters the condenser from the crystallizer. The condenser cools the steam, and the resulting distillate is sent out of the system through the distillate tank, while the secondary steam formed enters the vacuum crystallization device. The feed pump delivers at least a portion of the saturated salt solution to the rotary drum dryer, and the circulation pump draws at least a portion of the saturated salt solution into the heater, which then heats the crystallizer.

[0013] Optionally, the vacuum crystallization device includes a first liquid ring vacuum pump, a second liquid ring vacuum pump, a gas-liquid separator, a return gas pipeline, a plate heat exchanger, and a return regulating valve. Adjusting the pressure within the mixed salt crystallization device to a negative pressure working environment includes: The secondary steam enters the first liquid ring vacuum pump and the second liquid ring vacuum pump respectively. The first liquid ring vacuum pump and the second liquid ring vacuum pump compress at least part of the secondary steam to make its pressure reach the exhaust pressure, and then discharge it from the system through the external exhaust pipeline. At least a portion of the secondary steam enters the gas-liquid separator to obtain working liquid and steam; The steam enters the external discharge pipeline and the return gas pipeline and is discharged from the system; The vacuum levels at the inlets of the first liquid ring vacuum pump and the second liquid ring vacuum pump are adjusted by the opening of the return gas regulating valve, which is used to regulate the vacuum level inside the mixed salt crystallization device. The working fluid is replenished to the gas-liquid separator, the plate filter, the first liquid ring vacuum pump, and the second liquid ring vacuum pump through the water supply pipeline; The gas-liquid separator discharges excess working fluid through the overflow port and the drain pipe, and the excess working fluid is returned to the return water pipe.

[0014] Optionally, the vacuum degree of the crystallizer is -75 kPa to -35 kPa.

[0015] Optionally, the drum drying device includes a drum dryer, a water bath dust collector, and a dehumidifying fan, and the step of decomposing the saturated salt solution into solid salt and vapor includes: The saturated salt solution enters the rotary drum dryer, where the salts in the saturated salt solution are separated based on the high-temperature surface of the rotary drum dryer to obtain the solid salt and the vapor; The solid salt is discharged outside the system through the solid salt sludge hopper at the discharge port of the rotary drum dryer; The steam enters the water bath dust collector through the dehumidification fan and is then vented out of the system.

[0016] The present invention provides a system and method for extending the operation of a mixed salt crystallization device. The system includes a mixed salt crystallization device, a vacuum crystallization device, and a rotary drum dryer. High-salt water enters the mixed salt crystallization device through a pipeline, where it separates the high-salt water into a saturated salt solution and secondary steam. A vacuum pump extracts the secondary steam, and the vacuum level of the mixed salt crystallization device is controlled through a return gas pipeline. The saturated salt solution enters the rotary drum dryer and is separated into solid salt and steam. The combined use of the vacuum crystallization device and the rotary drum dryer reduces salt accumulation and scaling within the mixed salt crystallization device, thereby extending its continuous operating time without frequent cleaning and maintenance, thus improving its efficiency. Furthermore, the return gas pipeline reduces the internal pressure of the mixed salt crystallization device, further reducing salt accumulation, lowering maintenance costs, reducing maintenance and downtime, and improving the treatment efficiency of high-salt water and the processing capacity of the production line. It also reduces salt emissions in wastewater, minimizing environmental pollution and enhancing the environmental friendliness of the mixed salt crystallization device.

[0017] The above description is only an overview of the technical solution of this application. In order to better understand the technical means of this application and to implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of this application more obvious and understandable, the following are specific embodiments of this application. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 A schematic diagram of a system for extending the operation of a mixed salt crystallization apparatus according to an embodiment of the present invention; Figure 2 This is a schematic diagram of a mixed salt crystallization apparatus according to an embodiment of the present invention; Figure 3 This is a schematic diagram of a vacuum crystallization apparatus according to an embodiment of the present invention; Figure 4 This is a schematic diagram of a drum drying apparatus according to an embodiment of the present invention; Figure 5 This is a schematic diagram of a water bath dust collector according to an embodiment of the present invention.

[0020] in, Figures 1 to 5 The correspondence between the reference numerals and component names in the attached drawings is as follows: 100 Mixed Salt Crystallization Device, V1 Crystallizer, E1 Heater, P2 Circulating Pump, P2 Feed Pump, E2 Condenser, D1 Distillate Tank, P3A First External Pump, P3B Second External Pump, 200 Vacuum Crystallization Device, P-101A First Liquid Ring Vacuum Pump, P-101B Second Liquid Ring Vacuum Pump, V-101 Gas-Liquid Separator, E-101 Plate Heat Exchanger, PV-101 Return Gas Regulating Valve, 206 Return Gas Pipeline, BV-105 Manual Drain Valve, SR-101 Filter, BV-108 Manual Liquid Replenishment Valve, 300 Rotary Drum Dryer, PA213 Rotary Drum Dryer, S261 Water Bath Dust Collector, BL209 Exhaust Fan, Y201 Solid Salt Mud Hopper. Detailed Implementation

[0021] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0022] Before providing a further detailed description of the embodiments of the present invention, the directional terms used in the embodiments of the present invention, such as "upper part", "lower part" and "side part", are not intended to limit the scope of protection of the present invention.

[0023] To make the technical solutions and advantages of the present invention clearer, the embodiments of the present invention will be described in further detail below with reference to the accompanying drawings.

[0024] It should be noted that all letters on the equipment and instruments in the diagram are professional notation methods used in the chemical industry. For example, M represents a motor, V represents a tank, P represents pressure, PG represents a pressure gauge on the field pipeline, PI represents remote pressure transmission, SR represents a filter, F represents flow rate, FC represents a flow control valve, E represents heat exchangers, coolers, heaters, evaporators, etc., and BV represents valves adapted to various pipelines and phases. The combination of letters and numbers is the conventional way for the chemical industry to number equipment and instruments. Items not marked are common connection methods and intermediate equipment used in this field, which are basic common knowledge in the industry and are covered in basic professional textbooks in the chemical industry, so they will not be elaborated further.

[0025] Figure 1 This is a schematic diagram of a system for extending the operation of a mixed salt crystallization apparatus according to an embodiment of the present invention.

[0026] like Figure 1 As shown, one embodiment of the present invention provides a system for extending the operation of a mixed salt crystallization apparatus, the system comprising: The mixed salt crystallization device 100 has its inlet connected to a high-salt water pipeline. The mixed salt crystallization device 100 is configured to separate saturated salt solution and secondary steam from high-salt water. Vacuum crystallization device 200 is connected to the outlet of mixed salt crystallization device 100. Vacuum crystallization device 200 is configured to extract secondary steam. Vacuum device includes return gas pipeline 206, which is connected to the connecting pipeline between mixed salt crystallization device 100 and vacuum crystallization device 200. A rotary drum drying device 300 is connected to a mixed salt crystallization device 100. The rotary drum drying device 300 is configured to extract a saturated salt solution and separate the salt from the saturated salt solution.

[0027] The system includes a mixed salt crystallization device 100, a vacuum crystallization device 200, and a rotary drum drying device 300. High-salt water enters the mixed salt crystallization device 100 through a pipeline. The mixed salt crystallization device 100 classifies the high-salt water into a saturated salt solution and secondary steam. A vacuum pump extracts the secondary steam and controls the vacuum level of the mixed salt crystallization device 100 through a return gas pipeline 206. After the saturated salt solution enters the rotary drum drying device, it is separated into solid salt and steam. By using the vacuum crystallization device 200 and the rotary drum drying device 300 in combination, the accumulation and scaling of salt inside the mixed salt crystallization device 100 can be reduced, thereby extending the continuous operation time of the mixed salt crystallization device 100 without the need for frequent cleaning and maintenance, thus improving the efficiency of the mixed salt crystallization device 100. Furthermore, by reducing the pressure inside the mixed salt crystallization device 100 through the return air pipeline 206, the accumulation of salt inside the mixed salt crystallization device 100 is further reduced, thereby reducing the maintenance cost of the mixed salt crystallization device 100, reducing maintenance and downtime, improving the treatment efficiency of high-salt water and the processing capacity of the production line, and also reducing the amount of salt discharged in wastewater, reducing environmental pollution, and improving the environmental friendliness of the mixed salt crystallization device 100.

[0028] Specifically, the mixed salt crystallization device 100 is connected to the upstream high-salt water pipeline and is used to separate the high-salt water into saturated salt solution and secondary steam in a negative pressure environment; the vacuum crystallization device 200 extracts the secondary steam in the mixed salt crystallization device 100 through vacuum crystallization technology, changing the internal environment of the mixed salt crystallization device 100 from atmospheric pressure to negative pressure; the vacuum crystallization device 200 can also adjust the vacuum degree of the mixed salt crystallization device 100 through the setting of the return gas pipeline 206; the rotary drum dryer is used to separate the salt in the saturated salt solution to obtain solid salt and steam, and the steam is discharged after treatment. The combined use of vacuum crystallization technology and rotary drum drying technology can significantly reduce the accumulation and scaling of salt inside the mixed salt crystallization device 100 (crystallizer V1), significantly extend the operating time of the mixed salt crystallization device 100 (crystallizer V1), improve the operating efficiency of the mixed salt crystallization device 100 (crystallizer V1), reduce the maintenance and downtime costs of the mixed salt crystallization device 100 (crystallizer V1), improve the treatment efficiency of high-salt water, and has significant environmental protection and wide application characteristics.

[0029] It should be noted that the rotary drum dryer 300 is used to separate salt from a saturated salt solution, obtaining solid salt and steam. The solid salt is used in subsequent processes to prepare salt products or intermediate products. The steam is treated by a water bath dust collector S261. The specific treatment principle of the water bath dust collector S261 is existing technology, but it forms a new process when connected to the rotary drum dryer 300 through pipelines and auxiliary equipment. Figure 4 As shown, the water bath dust collector S261 is installed on the gas phase pipeline of the rotary drum dryer PA213 and connected to the gas phase pipeline to vent steam to the outside of the system. The exhaust fan BL209 is installed in front of the water bath dust collector S261 and located between the water bath dust collector S261 and the rotary drum dryer PA213. The outlet pipeline of the exhaust fan BL209 is connected to the inlet pipeline of the water bath dust collector S261 to extract steam and transport it to the water bath dust collector S261. The solution in the crystallizer V1 enters the rotary drum dryer PA213 through the feed pump P1. The high-temperature surface of the rotary drum dryer PA213 separates the salts in the crystallizer V1. The solid salts enter the discharge port through a spiral. The steam generated by the rotary drum dryer enters the water bath dust collector S261 for venting, thereby preventing recrystallization of the salts and reducing scaling in the crystallizer V1.

[0030] Figure 2 This is a schematic diagram of a mixed salt crystallization apparatus according to an embodiment of the present invention.

[0031] In one feasible implementation, such as Figure 2 As shown, the mixed salt crystallization apparatus 100 includes: Crystallizer V1 is connected to a high-salt water pipeline and is configured to separate saturated salt solution and secondary steam from high-salt water. Heater E1 is located on one side of crystallizer V1, and the outlet of heater E1 is connected to the middle position of crystallizer V1. The circulation pump P2 is installed on the outlet pipe of the crystallizer V1. The outlet of the circulation pump P2 is connected to the inlet of the heater E1, and delivers at least a portion of the saturated salt solution to the heater E1. Feed pump P1 is installed on the outlet pipe of crystallizer V1. Feed pump P1 is connected in parallel with circulation pump P2. Feed pump P1 is configured to transport saturated salt solution to rotary drum drying device 300. Condenser E2 has its inlet connected to the gas phase pipeline of crystallizer V1, and its outlet connected to vacuum crystallizer 200.

[0032] In one feasible embodiment, the mixed salt crystallization apparatus 100 further includes: Distillation tank D1 is connected to the condensate pipe of condenser E2. Distillation tank D1 is configured to collect the condensate produced by condenser E2. The outlet of distillation tank D1 is connected to an external pump.

[0033] The crystallizer V1 is connected to the upstream high-salt water pipeline to change the solubility of salts in the high-salt water under negative pressure, separating the high-salt water into a saturated salt solution and steam. The outlet of heater E1 is connected to the middle inlet of crystallizer V1, and the inlet of heater E1 is connected to circulation pump P2. Circulation pump P2 delivers a small portion of the saturated salt solution to heater E1, where it is heated before being returned to crystallizer V1 to provide heat to the interior of crystallizer V1. This can be adjusted based on the pipe diameter and pump power to deliver a small portion of the saturated salt solution to heater E1 and the majority to the rotary drum dryer 300. Feed pump P1 is located on the outlet pipeline of crystallizer V1, upstream of the circulation pump P2 pipeline, allowing the saturated solution and salt solution to be delivered to the circulation pump via the outlet pipeline of feed pump P1. Inside pump P2, most of the saturated salt solution is transported to the rotary drum dryer 300 via feed pump P1. Condenser E2 is located on the gas phase pipeline at the top of crystallizer V1. The inlet of condenser E2 is connected to the gas phase pipeline of crystallizer V1. After condensing the vapor, condenser E2 produces condensate and secondary vapor. The secondary vapor is transported to the vacuum crystallizer 200, while the condensate is connected to the distillation tank D1. The condensate is collected through the distillation tank D1. The outlet pipeline of distillation tank D1 is equipped with a first external pump P3A and a second external pump P3B. The first external pump P3A or the second external pump P3B transports the condensate to the outside of the system for processing. The two external pumps are set up to meet the requirement of one in use and one in standby, ensuring the normal operation of the system. That is, when one external pump operates abnormally or stops suddenly, the other standby external pump is automatically restarted through interlocking, ensuring the continuous and stable operation of the entire mixed salt crystallization device 100. The salt has already been crystallized by evaporation under negative pressure in crystallizer V1, so it will not cause pollution. Even if there is a very small amount of salt in the condensate, it will be discharged to the subsequent collection tank through the external drainage pipeline, so it will not cause pollution to the working environment or the external environment.

[0034] It should be noted that the crystallization device under development, including crystallizer V1, heater E1, circulating pump P2, feed pump P1, condenser E2, and distillate tank D1, delivers the secondary steam generated by condenser E2 to the crystallization vacuum device. This causes the crystallization vacuum device to reduce the internal pressure of crystallizer V1 from atmospheric pressure to negative pressure. The vacuum degree of crystallizer V1 is adjusted by regulating the opening of the return gas regulating valve PV-101 (located on the return gas pipeline 206) to adjust the vacuum degree of the liquid ring vacuum pump inlet. This provides a low-pressure environment for the precipitation of salts with higher solubility in high brine, enabling more salts to precipitate from crystallizer V1 under negative pressure and reducing structural phenomena on the inner wall of crystallizer V1.

[0035] Figure 3 This is a schematic diagram of a vacuum crystallization apparatus according to an embodiment of the present invention.

[0036] In one feasible implementation, such as Figure 3 As shown, the vacuum crystallization apparatus 200 includes: The gas phase inlets of the first liquid ring vacuum pump P-101A and the second liquid ring vacuum pump P-101B are both connected to the secondary steam pipeline. The liquid phase inlet of the gas-liquid separator V-101 is connected to the gas phase outlet of the first liquid ring vacuum pump P-101A and the second liquid ring vacuum pump P-101B respectively. The first gas phase outlet of the gas-liquid separator V-101 is connected to the external pipeline, and the second gas phase outlet of the gas-liquid separator V-101 is connected to the return gas pipeline 206. Plate heat exchanger E-101, the outlet of plate heat exchanger E-101 is connected to the liquid phase inlet of the first liquid ring vacuum pump P-101A and the second liquid ring vacuum pump P-101B respectively, the inlet of plate heat exchanger E-101 is connected to the water supply line of the working fluid, and the liquid phase outlet of gas-liquid separator V-101 is connected to the water return line of the working fluid. The inlet of the return gas regulating valve PV-101 is connected to the return gas pipeline 206, and the outlet of the return gas regulating valve PV-101 is connected to the gas phase inlet of the first liquid ring vacuum pump P-101A and the second liquid ring vacuum pump P-101B, respectively.

[0037] The vacuum crystallization device 200 includes a first liquid ring vacuum pump P-101A, a second liquid ring vacuum pump P-101B, a gas-liquid separator V-101, a plate heat exchanger E-101, and a return gas regulating valve PV-101. The gas phase inlets of both the first liquid ring vacuum pump P-101A and the second liquid ring vacuum pump P-101B are connected to the secondary steam pipeline of the condenser E2. The gas phase outlets of both pumps are connected to the liquid phase inlet of the gas-liquid separator V-101. The first and second liquid ring vacuum pumps P-101A and P-101B can extract the secondary steam from the crystallizer V1, thereby reducing the pressure inside the crystallizer V1 to a negative pressure state and maintaining this negative pressure state. The gas phase outlet of the gas-liquid separator V-101 is divided into two paths: one is an external discharge pipeline, and the other is a return gas pipeline 206. Understandably, the first liquid ring vacuum pump P-101A and the second liquid ring vacuum pump P-101B are also based on the principle of one in use and one on standby, in order to improve the efficiency of the system and avoid system downtime caused by failure; at the same time, when the power of one of the liquid ring vacuum pumps is not enough, the other can be turned on as a power supplement.

[0038] It should be noted that in this embodiment, the liquid level range of the gas-liquid separator V-101 is 90mm to 210mm. When the liquid level of the gas-liquid separator V-101 gradually decreases to 90mm, it reaches a low liquid level and issues an alarm signal. It is necessary to open the manual liquid replenishment valve BV-108 of the gas-liquid separator V-101 to replenish the liquid. When the liquid level of the gas-liquid separator V-101 gradually rises to 190mm, it will overflow through the overflow port of the gas-liquid separator V-101. If the liquid level continues to rise to a high liquid level of 210mm, an alarm signal will also be issued, prompting that the manual liquid drain valve BV-105 of the gas-liquid separator V-101 needs to be opened to drain the liquid. The above process ensures the normal operation of the first liquid ring vacuum pump P-101A and the second liquid ring vacuum pump P-101B, thereby maintaining the vacuum level within the crystallizer V1 within the preset range. This guarantees the normal precipitation of salts within the crystallizer V1 and reduces scaling on its inner wall. If the pumping volume of the first liquid ring vacuum pump P-101A and / or the second liquid ring vacuum pump P-101B is insufficient, or if the liquid level inside the gas-liquid separator V-101 is high due to poor drainage, this constitutes an abnormal operating condition. An alarm signal will be used to promptly detect and resolve the problem, improving the reliability and stability of the system.

[0039] Furthermore, the outlet of plate heat exchanger E-101 is connected to the liquid phase inlet of the first liquid ring vacuum pump P-101A and the second liquid ring vacuum pump P-101B via the working fluid supply line, and the liquid phase outlet of gas-liquid separator V-101 is connected to the working fluid return line (according to the "low inlet, high outlet" principle, the arrow pointing into plate heat exchanger E-101 is the supply line, and the arrow pointing out of plate heat exchanger E-101 is the return line); the return gas regulating valve PV-101 is installed on the return gas line 206, and the inlet of the return gas regulating valve PV-101 is connected to the return gas line 206. Connected to line 206, the outlet of the return gas regulating valve PV-101 is connected to the inlet pipelines of the first liquid ring vacuum pump P-101A and the second liquid ring vacuum pump P-101B, respectively. This allows adjustment of the vacuum level at the inlet of the liquid ring vacuum pumps, thereby changing the pressure inside the vacuum crystallizer 200 from atmospheric pressure to negative pressure. The return gas regulating valve PV-101 also regulates the vacuum level at the inlets of the first liquid ring vacuum pump P-101A and the second liquid ring vacuum pump P-101B, thus adjusting the vacuum level inside the crystallizer V1. This ensures that more salts precipitate from the high-salt water under a stable negative pressure environment. It should be noted that the amount of crystallization from high-salt water under negative pressure is greater than that under atmospheric pressure. The vacuum environment of the crystallizer V1 is established by evacuating the vacuum pumps (first liquid ring vacuum pump P-101A and / or second liquid ring vacuum pump P-101B), and the vacuum level of the crystallizer V1 is indirectly adjusted by regulating the outlet flow rate of the vacuum pumps, ensuring efficient operation of the crystallizer V1.

[0040] As is understandable, BV in the diagram represents a valve. Depending on the needs, manual valves, solenoid valves, and / or check valves are set up, as well as pressure gauges PG and temperature gauges TG on other pipelines. SG is a signal generator, which is part of the control system. These are all common drawing techniques in this field and will not be explained in detail.

[0041] Figure 4 This is a schematic diagram of a drum drying apparatus according to an embodiment of the present invention; Figure 5 This is a schematic diagram of a water bath dust collector according to an embodiment of the present invention.

[0042] In one feasible implementation, such as Figure 4 and Figure 5 As shown, the drum drying device 300 includes: The rotary drum dryer PA213 is located downstream of the mixed salt crystallization device 100. The rotary drum dryer PA213 is configured to separate saturated salt solutions to obtain solid salt and vapor. Water bath dust collector S261 is connected to the gas phase pipeline of the rotary drum dryer. Water bath dust collector S261 is configured outside the steam control system. The exhaust fan BL209 is located between the water bath dust collector S261 and the rotary drum dryer. The exhaust fan BL209 is configured to deliver steam to the water bath dust collector S261.

[0043] The rotary drum dryer PA213 has its inlet pipe connected to the outlet pipe of the feed pump P1. The rotary drum dryer separates saturated salt solutions through its high-temperature internal surface, producing solid salt and steam. The water bath dust collector S261 is connected to the gas phase pipe of the rotary drum dryer, venting the steam from the dryer's separation point to the outside of the system for subsequent centralized treatment before venting. The outlet pipe of the exhaust fan BL209 is connected to the inlet pipe of the water bath dust collector S261, extracting the steam separated within the rotary drum dryer PA213 and transporting it to the water bath dust collector S261. The water bath dust collector S261 removes a small amount of impurities from the steam and water vapor before discharge, improving the purity of the discharged gas and preventing pollution. Essentially, the water bath dust collector S261 forces the dust-laden gas into the water at a certain speed, utilizing the large number of bubbles and water droplets generated by the intense collision between the gas and the liquid surface to capture dust particles in the gas, thus achieving purification. Dust-laden gas is introduced into the water bath dust collector S261 through the exhaust fan BL209. The gas impacts the liquid surface (water tank) or the water curtain sprayed from specially designed nozzles inside the dust collector at a high speed. The impact of the high-speed airflow will violently agitate the water layer, generating a large number of bubbles, water splashes and water mists of different sizes that tumble and jump. This process forms a huge three-phase mixing area of ​​water, gas and dust, which is the so-called "water bath" area. The dust particles have a large mass and a large inertia. When the airflow changes direction and curves upwards in water, dust particles cannot follow the streamline as flexibly as in gas. Instead, they break through the water-air interface, collide with and become trapped in water droplets or foam. Fine dust particles are captured by Brownian motion upon contact with the water droplets. After being wetted, the dust particles agglomerate into larger clusters, making them easier to separate. The purified gas, carrying a large number of water droplets, moves upwards after being washed in the water bath. Before leaving the dust collector, the gas passes through baffles or demisters. These devices effectively intercept the water droplets entrained in the gas, ensuring that dry, clean gas exits from the top outlet. The captured dust deposits at the bottom of the water tank of the S261 water bath dust collector, forming sludge. This sludge needs to be cleaned regularly through a drain valve to maintain dust removal efficiency. The S261 water bath dust collector has a simple structure, high dust removal efficiency, low cost, safe and reliable operation, and a certain purification capacity for harmful gases.

[0044] Specifically, the saturated salt solution in crystallizer V1 is transported to the rotary drum dryer PA213 via feed pump P1. The high-temperature surface of the rotary drum dryer separates the saturated salt solution into solid salt and steam. The solid salt enters the discharge port through a spiral, while the steam enters the water bath dust collector S261 for venting. This avoids recrystallization of the salt, reduces scaling in crystallizer V1, extends the operating time of crystallizer V1, and improves the efficiency of high-salt water treatment.

[0045] like Figure 1As shown, one embodiment of the present invention provides a method for extending the operation of a mixed salt crystallization apparatus. Utilizing the above-described system, the method includes the following steps: Based on the mixed salt crystallization device, high-salt water is separated into saturated salt solution and secondary steam; Based on the vacuum crystallization device, the secondary steam is extracted, and the pressure inside the mixed salt crystallization device is adjusted to a negative pressure working environment. Based on the rotary drum dryer, saturated salt solution is decomposed into solid salt and vapor.

[0046] The method, through the combined use of the mixed salt crystallization device 100, the vacuum crystallization device 200, and the rotary drum drying device, effectively solves the problem of scaling in crystallizer V1 during the high-salt water treatment process in coal chemical industry. By reducing the internal pressure of crystallizer V1 and combining vacuum crystallization and rotary drum drying technologies, the accumulation of salt in crystallizer V1 is reduced, extending its operating time, lowering its maintenance costs, and improving the efficiency of the entire high-salt water treatment process. This method not only significantly improves the economic efficiency of American chemical enterprises but also makes a positive contribution to environmental protection.

[0047] In one feasible implementation, such as Figure 2 As shown, the mixed salt crystallization apparatus 100 includes a crystallizer V1, a heater E1, a circulating pump P2, a feed pump P1, a condenser E2, and a distillation tank D1. The process of separating high-salt water into a saturated salt solution and secondary steam includes: High-salt water enters the crystallizer under negative pressure, and the resulting steam enters the condenser from the crystallizer. The condenser E2 cools the steam, and the resulting distillate is sent out of the system through the distillate tank, while the secondary steam formed enters the vacuum crystallization device. The feed pump delivers at least a portion of the saturated salt solution to the rotary drum dryer, and the circulation pump draws at least a portion of the saturated salt solution into the heater, which then heats the crystallizer.

[0048] Specifically, when high-salt water enters the crystallizer V1 under negative pressure, the solubility of the salts changes, and salts with higher solubility begin to precipitate. The vapor generated by the crystallizer V1 enters the condenser E2 from the top gas phase outlet. The condenser E2 cools the vapor through heat exchange to obtain distillate. The distillate is sent out of the system through the first external pump P3A and the second external pump P3B. The distillate can be used for large-scale circulation or discharged to the main distillate pipeline for centralized treatment. The feed pump P1 delivers most of the saturated salt solution to the drum dryer, while the circulation pump P2 extracts a small portion of the saturated salt solution to the heater E1 for heating before returning it to the crystallizer V1, providing heat to the crystallizer V1. The heat and vacuum environment accelerate the evaporation of the high-salt water in the crystallizer V1, improving the solid salt precipitation efficiency.

[0049] It should be noted that by changing the solubility of salts in high-salt water under negative pressure in crystallizer V1, salts with higher solubility are precipitated, reducing the dissolved salt content in high-salt water and increasing the amount of salt precipitated. This reduces recrystallization of the solution in crystallizer V1 and avoids scaling on the inner wall of crystallizer V1.

[0050] In one feasible implementation, such as Figure 3 As shown, the vacuum crystallization device 200 includes a first liquid ring vacuum pump P-101A, a second liquid ring vacuum pump P-101B, a gas-liquid separator V-101, a return gas pipeline 206, a plate heat exchanger E-101, and a return gas regulating valve PV-101. The working environment for regulating the pressure within the mixed salt crystallization device to a negative pressure includes: Secondary steam enters the first liquid ring vacuum pump P-101A and the second liquid ring vacuum pump P-101B respectively. The first liquid ring vacuum pump P-101A and the second liquid ring vacuum pump P-101B compress at least part of the secondary steam, bringing its pressure to the exhaust pressure, and then discharges it through the external exhaust pipe (connected to...). Figure 3 The DRAIN pipeline is part of the exhaust system, and it is the same as the gas exhaust pipeline in the gas-liquid separation process. To prevent other contaminants from being present in the steam, it can be treated before being discharged.

[0051] At least a portion of the secondary steam enters the gas-liquid separator V-101 to obtain working liquid and steam; Steam enters the external exhaust pipeline and the return gas pipeline to be discharged from the system; The vacuum level at the inlet of the first liquid ring vacuum pump P-101A and the second liquid ring vacuum pump P-101B is adjusted by the opening of the return gas regulating valve PV-101, which is used to regulate the vacuum level in the mixed salt crystallization device. The working fluid (the liquid separated by the gas-liquid separator V-101) is replenished to the gas-liquid separator V-101, plate heat exchanger E-101, first liquid ring vacuum pump P-101A and second liquid ring vacuum pump P-101B through the water supply pipeline; the gas-liquid separator V-101 discharges excess working fluid through the overflow port and the drain pipeline, and the excess working fluid returns to the return water pipeline.

[0052] The working fluid is supplied to the gas-liquid separator V-101, plate heat exchanger E-101, first liquid ring vacuum pump P-101A, and second liquid ring vacuum pump P-101B via a water supply pipeline. The working fluid forms the liquid rings of the first liquid ring vacuum pump P-101A and the second liquid ring vacuum pump P-101B, provides cooling to the plate heat exchanger E-101, and replenishes the liquid level in the gas-liquid separator V-101, ensuring the normal operation of the system.

[0053] It should be noted that in the vacuum crystallization process described above, the secondary steam extracted by the first liquid ring vacuum pump P-101A and the second liquid ring vacuum pump P-101B is sent to the gas-liquid separator V-101 for gas-liquid separation. The gas-liquid separator V-101 is also connected to the return gas regulating valve PV-101 to maintain the pressure inside the crystallizer V1 under negative pressure. This creates a favorable crystallization environment for the high-salt water to precipitate more salts, thereby reducing scaling on the inner wall of the crystallizer V1 (high-salt water is easily saturated under negative pressure, making it easier to precipitate solid salts more quickly). At the same time, the plate heat exchanger E-101 provides the first liquid ring vacuum pump P-101A and the second liquid ring vacuum pump P-101B with the required working fluid to maintain the liquid ring inside the first liquid ring vacuum pump P-101A and the second liquid ring vacuum pump P-101B, thus ensuring that the crystallizer V1 always operates under negative pressure. The plate heat exchanger E-101 is used to reduce the temperature of the liquid discharged from the first liquid ring vacuum pump P-101A and the second liquid ring vacuum pump P-101B by means of heat exchange. Figure 3 In this context, CWS represents low-temperature circulating water supply, while CWR represents high-temperature circulating water return.

[0054] In one feasible implementation, the vacuum degree of the crystallizer V1 is -75 kPa to -35 kPa.

[0055] Specifically, high-salt water can precipitate more salts within a vacuum range of -75 kPa to -35 kPa, thereby reducing the structural problems caused by salt crystallization within crystallizer V1. In this embodiment, the vacuum degree of crystallizer V1 is selected as -40 kPa. Under this vacuum degree, the amount of salt precipitated within crystallizer V1 increases significantly, greatly reducing scaling on the inner wall of crystallizer V1.

[0056] In one feasible implementation, such as Figure 4 and Figure 5 As shown, the drum drying device 300 includes a drum dryer, a water bath dust collector S261, and an exhaust fan BL209, which decomposes the saturated salt solution into solid salt and vapor. A saturated salt solution enters a rotary drum dryer, where the salts are separated from the saturated salt solution by the high-temperature surface of the rotary drum dryer, yielding solid salt and vapor. Solid salt is discharged out of the system through the solid salt sludge hopper at the discharge port of the rotary drum dryer; Steam is released into the water bath dust collector via the dehumidification fan and discharged outside the system.

[0057] The saturated salt solution enters the rotary drum dryer via feed pump P1, where it is separated into solid salt and steam. The solid salt enters the solid salt sludge hopper Y201 at the dryer's discharge port and is then discharged from the system. The steam is drawn into the water bath dust collector S261 by exhaust fan BL209 for external discharge. It should be noted that the solid salt can be stored and sold or used for other purposes.

[0058] Example 1 High-salt water enters the crystallizer V1 through the pipeline. During the operation of the first liquid ring vacuum pump P-101A and the second liquid ring vacuum pump P-101B, secondary steam is extracted from the outlet pipeline of the condenser E2. By combining with the self-adjusting opening of the return gas regulating valve PV-101, the vacuum degree in the crystallizer V1 is adjusted, so that the vacuum degree in the crystallizer V1 is in a negative pressure environment of -75 kPa. Under the low pressure environment, the solubility of salts in the high-salt water changes, especially salts with high solubility such as nitrates begin to precipitate, reducing the salt content in the solution in the crystallizer V1. The amount of salt precipitated in the crystallizer V1 increases significantly, thereby reducing the scaling phenomenon on the inner wall of the crystallizer V1.

[0059] A small portion of the saturated salt solution produced simultaneously in crystallizer V1 is transported to heater E1 via circulating pump P2. After being heated by heater E1, this portion of the saturated salt solution flows back into crystallizer V1, ensuring that the temperature load in crystallizer V1 meets the crystallization temperature requirements, thereby ensuring the continuous precipitation of salts.

[0060] If this moisture (the treated high-salt wastewater) is not removed in time, it may cause the salt to redissolve and redeposit on the inner wall of crystallizer V1, forming secondary scaling, thus affecting the long-term operation of crystallizer V1. To solve this problem, most of the saturated salt solution is transported to the rotary drum dryer through the feed pump P1. The drum of the rotary drum dryer is cylindrical, and the heating medium steam is introduced into the cylinder to raise the outer wall of the cylinder to a certain temperature. The material to be dried (most of the saturated salt solution) is coated on the outside of the cylinder in an appropriate manner. During the rotation of the cylinder, it is heated by the outer wall of the cylinder, and the moisture in the material vaporizes and is discharged. When the moisture in the material drops to a set value, it is scraped off the outer wall of the rotating cylinder by a scraper, thus achieving the purpose of separating the salt in the saturated salt solution on the high-temperature surface of the rotary drum dryer. The resulting solid salt enters the solid salt mud hopper Y201 at the discharge port through a screw and is then discharged from the system. The heat transfer mechanism of the rotary drum dryer is heat conduction, and the heat transfer direction remains consistent throughout the entire operating cycle. Except for heat loss through the cover and thermal radiation, all remaining heat is used for the evaporation of moisture from the drum film, achieving a thermal efficiency of 80% to 90%. The rotary drum dryer offers high operational flexibility and wide applicability, adapting to different material concentrations, heating medium temperatures, and drum rotation speeds for efficient evaporation and drying. The drying cycle is typically only 10 to 300 seconds, making it suitable for heat-sensitive materials. Because the coating film applied to the drum wall is very thin, generally 0.3 mm to 1.5 mm, and the heat and mass transfer directions are consistent, the film surface can maintain an evaporation rate of 2070 kg·m²·h to 70 kg·m²·h. Therefore, during the operation of the rotary drum dryer, the hot drum surface comes into contact with the saturated salt solution, causing the water in the saturated salt solution to evaporate, and the solid salt enters the feed inlet through a scraper, effectively reducing the risk of redissolution and scaling of the salt in the saturated salt solution. Rotary drum drying not only improves the efficiency of salt removal, but also completes the dehydration process in a shorter time, avoiding the prolonged residence of high-salt water in the system.

[0061] Example 2 High-salt water enters the crystallizer V1 through pipelines. During operation, the first liquid ring vacuum pump P-101A and the second liquid ring vacuum pump P-101B extract secondary steam from the outlet pipeline of the condenser E2. By combining with the self-adjusting opening of the return gas regulating valve PV-101, the crystallizer V1 is adjusted to a negative pressure environment with a vacuum degree of -35 kPa. The solubility of salts in the high-salt water changes under low pressure, especially salts with high solubility such as nitrates begin to precipitate, reducing the salt content of the solution in the crystallizer V1. The amount of salt precipitated in the crystallizer V1 increases significantly, thereby reducing scaling on the inner wall of the crystallizer V1.

[0062] A small portion of the saturated salt solution produced simultaneously in crystallizer V1 is transported to heater E1 via circulating pump P2. After being heated by heater E1, this portion of the saturated salt solution is returned to crystallizer V1 to ensure that the temperature inside crystallizer V1 meets the crystallization temperature requirements, thereby ensuring continuous salt precipitation. Other aspects are the same as in Comparative Example 1 and will not be repeated.

[0063] Example 3 In this comparative example, the crystallizer V1 is adjusted to a negative pressure environment with a vacuum degree of -40 kPa by combining the self-adjusting opening of the return gas regulating valve PV-101. Everything else is the same as in Comparative Example 1, and will not be repeated here.

[0064] The above three embodiments verify that the system and method for extending the operation of the mixed salt crystallization device of this application, through the combined use of vacuum crystallization technology and rotary drum drying technology, can significantly reduce the accumulation of salt and scaling inside the crystallizer V1. Compared with traditional methods, the crystallizer V1 can operate continuously for a longer period of time without frequent cleaning and maintenance, thereby improving the utilization efficiency of the crystallizer V1 and effectively solving the scaling problem of the crystallizer V1 in the high-salt water treatment process of coal chemical industry. Because the operating time of the crystallizer V1 is extended, the maintenance and downtime costs of the crystallizer V1 can be reduced. By reducing the pressure inside the crystallizer V1, the precipitation of salts in the high-salt water is increased, reducing the accumulation of salt in the crystallizer V1, thereby reducing maintenance and downtime costs, improving the efficiency of the entire high-salt water treatment process, and also increasing the processing capacity of the production line. By reducing scaling inside the crystallizer V1, the amount of salt discharged in wastewater (high-salt water) is reduced, environmental pollution is reduced, and it helps to achieve the sustainable development goals of the coal chemical industry. The proposed solution is not only applicable to the treatment of high salinity water in the coal chemical industry, but can also be widely used in wastewater treatment processes in other industries, and has good market prospects and promotional value.

[0065] In this invention, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance. The term "a plurality" refers to two or more unless otherwise expressly defined.

[0066] Other embodiments of the invention will readily occur to those skilled in the art upon consideration of the specification and practice of the invention disclosed herein. The invention is intended to cover any variations, uses, or adaptations of the invention that follow the general principles of the invention and include common knowledge or customary techniques in the art not disclosed herein. The specification and examples are to be considered exemplary only.

[0067] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A system for extending the operation of a double salt crystallization plant, characterized in that, The system comprises: a mixed salt crystallization device, a water inlet of the mixed salt crystallization device being connected with a high-salinity water pipeline, the mixed salt crystallization device being configured to separate the high-salinity water into a saturated salt solution and secondary steam; a vacuum crystallization device, connected with an outlet of the mixed salt crystallization device, the vacuum crystallization device being configured to extract the secondary steam, the vacuum device comprising a return gas pipeline, the return gas pipeline being connected with a connecting pipeline between the mixed salt crystallization device and the vacuum crystallization device; a rotary drum drying device, connected with the mixed salt crystallization device, the rotary drum drying device being configured to extract the saturated salt solution and separate salt in the saturated salt solution.

2. The system for prolonging the operation of a double salt crystallization plant according to claim 1, characterized in that, The mixed salt crystallization device comprises: a crystallizer, connected with the high-salinity water pipeline, the crystallizer being configured to separate the high-salinity water into a saturated salt solution and secondary steam; a heater, provided at one side of the crystallizer, an outlet of the heater being connected with an intermediate position of the crystallizer; a circulating pump, provided on an outlet pipeline of the crystallizer, an outlet of the circulating pump being connected with an inlet of the heater, the circulating pump being configured to transport at least part of the saturated salt solution to the heater; a feed pump, provided on the outlet pipeline of the crystallizer, the feed pump being provided in parallel with the circulating pump, the feed pump being configured to transport the saturated salt solution to the rotary drum drying device; a condenser, an inlet of the condenser being connected with a gas phase pipeline of the crystallizer, an outlet of the condenser being connected with the vacuum crystallization device.

3. The system for prolonging the operation of a double salt crystallization plant according to claim 2, characterized in that, The mixed salt crystallization device further comprises: a distillate tank, connected with a condensate pipeline of the condenser, the distillate tank being configured to collect condensate generated by the condenser, an outlet of the distillate tank being connected with an external delivery pump.

4. The system for prolonging the operation of a double salt crystallization plant according to claim 1, characterized in that, The vacuum crystallization device comprises: a first liquid ring vacuum pump and a second liquid ring vacuum pump, gas phase inlets of the first liquid ring vacuum pump and the second liquid ring vacuum pump being connected with a pipeline of the secondary steam; a gas-liquid separator, liquid phase inlets of the gas-liquid separator being connected with gas phase outlets of the first liquid ring vacuum pump and the second liquid ring vacuum pump respectively, a first gas phase outlet of the gas-liquid separator being connected with an external delivery pipeline, a second gas phase outlet of the gas-liquid separator being connected with the return gas pipeline; a plate heat exchanger, outlets of the plate heat exchanger being connected with liquid phase inlets of the first liquid ring vacuum pump and the second liquid ring vacuum pump respectively, an inlet of the plate heat exchanger being connected with a water supply pipeline of working liquid, a liquid phase outlet of the gas-liquid separator being connected with a water return pipeline of the working liquid; a return gas regulating valve, an inlet of the return gas regulating valve being connected with the return gas pipeline, outlets of the return gas regulating valve being connected with gas phase inlets of the first liquid ring vacuum pump and the second liquid ring vacuum pump respectively.

5. The system for prolonging the operation of a double salt crystallization plant according to claim 1, characterized in that, The rotary drum drying device comprises: a rotary drum dryer, provided downstream of the mixed salt crystallization device, the rotary drum dryer being configured to separate the saturated salt solution to obtain solid salt and steam; a water bath dust collector, connected with a gas phase pipeline of the rotary drum dryer, the water bath dust collector being configured to control the steam to the outside of the system. A moisture removal fan is arranged between the water bath dust collector and the rotary drum dryer, and the moisture removal fan is configured to deliver the steam to the water bath dust collector.

6. A method of prolonging the operation of a double salt crystallization plant using the system of any one of claims 1 to 4, characterized in that, The method comprises the following steps: Separating high-salinity water into saturated salt solution and secondary steam based on a heterogeneous salt crystallization device; Extracting the secondary steam and adjusting the pressure in the heterogeneous salt crystallization device to a negative pressure working environment based on a vacuum crystallization device; Decomposing the saturated salt solution into solid salt and steam based on the rotary drum drying device.

7. The method of extending the operation of a double salt crystallization apparatus of claim 6, wherein, The heterogeneous salt crystallization device comprises a crystallizer, a heater, a circulating pump, a feed pump, a condenser, and a distillate tank, and the separating of the high-salinity water into the saturated salt solution and the secondary steam comprises: The high-salinity water enters the crystallizer in a negative pressure state, and the steam formed in the crystallizer enters the condenser; The condenser cools the steam, and the distillate obtained is sent out of the system through the distillate tank, and the secondary steam formed enters the vacuum crystallization device; The feed pump delivers at least part of the saturated salt solution to the rotary drum drying device, and the circulating pump extracts at least part of the saturated salt solution to the heater, and the heater supplies heat to the crystallizer.

8. The method of extending the operation of a double salt crystallization apparatus of claim 6, wherein, The vacuum crystallization device comprises a first liquid ring vacuum pump, a second liquid ring vacuum pump, a gas-liquid separator, a gas return pipeline, a plate heat exchanger, and a gas return regulating valve, and the adjusting of the pressure in the heterogeneous salt crystallization device to a negative pressure working environment comprises: The secondary steam enters the first liquid ring vacuum pump and the second liquid ring vacuum pump respectively, the first liquid ring vacuum pump and the second liquid ring vacuum pump compress at least part of the secondary steam to reach an exhaust pressure, and the secondary steam is discharged out of the system through an exhaust pipeline; At least part of the secondary steam enters the gas-liquid separator to obtain working liquid and steam; The steam enters the exhaust pipeline and the gas return pipeline to be discharged out of the system; The vacuum degree of the inlets of the first liquid ring vacuum pump and the second liquid ring vacuum pump is adjusted by the opening degree of the gas return regulating valve, so as to adjust the vacuum degree in the heterogeneous salt crystallization device; The working liquid is supplemented to the gas-liquid separator, the plate filter, the first liquid ring vacuum pump, and the second liquid ring vacuum pump through a water supply pipeline; The gas-liquid separator discharges excess working liquid through an overflow port and a liquid discharge pipeline, and the excess working liquid returns to a water return pipeline.

9. The method of extending the operation of a double salt crystallization apparatus of claim 7, wherein, The vacuum degree of the crystallizer is -75 kPa to -35 kPa.

10. The method of extending the operation of a double salt crystallization apparatus of claim 6, wherein, The rotary drum drying device comprises a rotary drum dryer, a water bath dust collector, and a moisture removal fan, and the decomposing of the saturated salt solution into solid salt and steam comprises: The saturated salt solution enters the rotary drum dryer, and the salt in the saturated salt solution is separated based on the high-temperature surface of the rotary drum dryer to obtain the solid salt and the steam; The solid salt is discharged out of the system through a solid salt hopper at a discharge port of the rotary drum dryer; The steam enters the water bath dust collector through the moisture removal fan, is vented, and is discharged out of the system.

Images