Residual heat type anti-fouling low-temperature multi-effect high-salinity mine water treatment system and method

Abstract

The application provides a waste heat type anti-fouling low-temperature multi-effect high-mineralization mine water treatment system and method, which adopts a low-temperature multi-effect evaporation technology to concentrate and desalinate high-mineralization mine water, fully utilizes waste heat of a power plant as power steam, reduces water production cost and saves energy. In order to prevent crystallization and fouling of high-mineralization mine water in a low-temperature multi-effect evaporator, an anti-fouling automatic control device is used to monitor mine water evaporation temperature and mine water salinity of the high-mineralization mine water in real time as input conditions in a low-temperature multi-effect evaporation process, a central processing module is used to give corresponding control instructions, operation parameters of the low-temperature multi-effect evaporation device are controlled, the mine water evaporation temperature reaches a preset temperature, the mine water salinity reaches a preset salinity, and the low-temperature multi-effect evaporation device is prevented from fouling, so that stable operation of the system is ensured.

Description

Technical Field

[0001] This invention relates to the field of mine water treatment technology, and in particular to a waste heat-type anti-scaling low-temperature multi-effect high-mineralization mine water treatment system and method. Background Technology

[0002] Coal mining damages underground aquifers, generating large amounts of mine water. Currently, the utilization rate of mine water is very low, mainly because major coal mines in my country (northwest China) primarily produce high-mineralized mine water characterized by high salt content and high hardness. The salt content is generally between 1000 and 20000 mg / L, and the water quality is mostly neutral or slightly alkaline, exhibiting high hardness and a tendency to scale. Therefore, effective treatment and water resource recovery are necessary before mine water can be used. Currently, concentration and desalination are both key and challenging aspects of mine water resource utilization.

[0003] Currently, there are two main categories of high-salinity water concentration and desalination technologies in China: thermal methods (including multi-stage flash evaporation, low-temperature multi-effect evaporation, and gas compression distillation) and membrane methods (including nanofiltration, reverse osmosis, and electrolysis). Among these, membrane technologies combining ultrafiltration, nanofiltration, and reverse osmosis have become widely used in the treatment of high-salinity mine water in China due to their low energy consumption, lack of phase change, and high water recovery rate.

[0004] However, ultrafiltration, nanofiltration, and high-pressure reverse osmosis membrane systems have high investment costs, and improper operation can lead to irreversible membrane fouling. Existing technologies require flexible adjustments to pretreatment methods and cleaning formulas based on the different qualities of mine water, further increasing overall investment and operating costs. If low-temperature multi-effect evaporation technology from the thermal method could replace membrane separation technology for concentrating and desalinating high-salinity mine water, it would undoubtedly effectively reduce investment costs for mine water with high salinity and large water quality fluctuations. Low-temperature multi-effect evaporation connects a series of horizontal tube falling film evaporators in series, dividing them into several effect groups. High-salinity mine water undergoes multiple evaporations; as the evaporation temperature decreases with each effect, the secondary steam generated in the previous effect can serve as a heat source for the next effect. Only the first effect, with the highest temperature, needs to be irrigated with heating steam to obtain several times the amount of fresh water as the heat source steam. It has advantages such as low pretreatment requirements, high-quality fresh water, and high operational flexibility, and has been widely used in seawater desalination and industrial high-salinity water treatment in recent years. However, for low-temperature multi-effect evaporation systems used for high-salinity water and seawater desalination, during the preheating and evaporator heating processes, the high salinity, hardness, total dissolved solids, and other impurities in the water can cause some low-solubility components to become supersaturated, leading to scaling on the heat exchange surfaces of the evaporator. Therefore, energy saving and scaling prevention are key aspects of low-temperature multi-effect evaporation technology for treating highly salinized mine water. Summary of the Invention

[0005] The technical problem to be solved by this invention is the high cost and easy scaling of existing mine water treatment systems. To this end, this invention proposes a waste heat-type anti-scaling low-temperature multi-effect high-mineralization mine water treatment system and method.

[0006] To address the aforementioned technical problems, the present invention provides the following technical solution:

[0007] In a first aspect, the technical solution of this application provides a waste heat-type anti-scaling low-temperature multi-effect high-salinity mine water treatment system, including a low-temperature multi-effect evaporator and an anti-scaling automatic control device, wherein:

[0008] The low-temperature multi-effect evaporator includes a multi-effect evaporator and a steam ejector: the low-pressure secondary steam output from the previous evaporator in the multi-effect evaporator is input to the next evaporator; the steam ejector receives waste heat steam from the power plant and low-pressure secondary steam output from the last effect evaporator in the multi-effect evaporator at its inlet end, the first path of its outlet end is connected to the first effect evaporator in the multi-effect evaporator, the second path of its outlet end is connected to the middle section evaporator in the multi-effect evaporator, and the third path of its outlet end is connected to the last effect evaporator.

[0009] The anti-scaling automatic control device includes a data acquisition module and a central processing module. The data acquisition module is used to collect the evaporation temperature and salinity of the mine water in the low-temperature multi-effect evaporator, and to obtain the degree of scaling of the low-temperature multi-effect evaporator according to the scaling prediction model. The operating parameters of the low-temperature multi-effect evaporator are controlled according to the degree of scaling to ensure that the evaporation temperature of the mine water reaches a preset temperature and the salinity of the mine water reaches a preset salinity, so as to prevent scaling of the low-temperature multi-effect evaporator.

[0010] In some solutions, the waste heat-type anti-scaling low-temperature multi-effect high-mineralization mine water treatment system uses a calcium sulfate solubility model in a high-mineralization mine water system as a scaling prediction model in the central treatment module.

[0011] In some solutions, the waste heat-type anti-scaling low-temperature multi-effect high-mineralization mine water treatment system further includes, as described, a low-temperature multi-effect evaporator:

[0012] A first heating steam control valve is located between the second path of the steam ejector outlet and the intermediate section evaporator in the multi-effect evaporator;

[0013] The second heating steam control valve is located between the third path at the outlet end of the steam ejector and the last effect evaporator in the multi-effect evaporator;

[0014] The first heating steam control valve and the second heating steam control valve are connected to the central processing module.

[0015] In some solutions, the waste heat-type anti-scaling low-temperature multi-effect high-mineralization mine water treatment system includes a data acquisition module that is also used to collect the mine water evaporation pressure of the low-temperature multi-effect evaporation device and send the mine water evaporation pressure to the central processing module.

[0016] The central processing module controls the evaporation pressure of the mine water to a target pressure so that the evaporation temperature of the mine water reaches a preset temperature and the salinity of the mine water reaches a preset salinity.

[0017] In some solutions, the waste heat-type anti-scaling low-temperature multi-effect high-mineralization mine water treatment system further includes, as described, a low-temperature multi-effect evaporator:

[0018] A condenser is located at the rear end of the last-effect evaporator and receives a portion of the low-pressure secondary steam output from the last-effect evaporator. Its output end is connected to the raw material inlet of the first-effect evaporator.

[0019] A pretreatment module is installed between the input end of the condenser and the raw material tank. It is used to pretreat the high-mineralization mine water output from the raw material tank and then transport the pretreated high-mineralization mine water to the condenser.

[0020] In some solutions, the waste heat-type anti-scaling low-temperature multi-effect high-mineralization mine water treatment system includes a data acquisition module that is also used to collect the freshwater flow rate output by the low-temperature multi-effect evaporator and send the freshwater flow rate to the central processing module.

[0021] The central processing module controls the flow rate of high-mineralized mine water entering the first-effect evaporator based on the relationship between the freshwater flow rate and the preset standard flow rate.

[0022] In some solutions, the waste heat-type anti-scaling low-temperature multi-effect high-mineralization mine water treatment system further includes, as described, a low-temperature multi-effect evaporator:

[0023] A concentrate tank is connected to the output port of the last-effect evaporator and is used to collect the concentrate output by the last-effect evaporator.

[0024] A freshwater tank is connected to the freshwater outlet of each stage of the evaporator and is used to collect the freshwater output from each stage of the evaporator.

[0025] In some solutions, the waste heat-type anti-scaling low-temperature multi-effect high-mineralization mine water treatment system further includes, as described, a low-temperature multi-effect evaporator:

[0026] A raw material pump is installed between the pretreatment module and the raw material tank;

[0027] A concentrate pump is installed between the final-effect evaporator and the concentrate tank;

[0028] A freshwater pump is installed between the freshwater outlet of each stage evaporator and the freshwater tank;

[0029] The raw material pump, the concentrate pump, and the desalination pump all operate under the control of the central processing module.

[0030] In some solutions, the waste heat-type anti-scaling low-temperature multi-effect high-mineralization mine water treatment system further includes an anti-scaling automatic control device that includes:

[0031] An A / D conversion module is located between the data acquisition module and the central processing module, and converts the information acquired by the data acquisition module into a digital signal and inputs it to the central processing module.

[0032] The PID control module is used to convert the control strategy output by the central processing module into control commands to adjust the operating parameters of the low-temperature multi-effect evaporator.

[0033] The D / A conversion module is connected to the PID control module and is used to convert the control command into an analog control signal and send it to the output execution terminal.

[0034] Secondly, the technical solution of this application provides a method for treating industrial waste heat-type anti-scaling low-temperature multi-effect high-mineralization mine water, including:

[0035] The study aimed to obtain the variation of calcium sulfate solubility in high-mineralization mine water under low-temperature multi-effect evaporation within a set range, as a function of mine water evaporation temperature and mine water salinity.

[0036] Based on the process flow simulation system software, the thermodynamic parameters and parameter model of calcium sulfate dissolution were obtained by fitting the ELECNRTL model.

[0037] Based on the aforementioned variation pattern, the thermodynamic parameters and parameter model are adjusted and optimized to obtain a calcium sulfate solubility model that varies within the specified range, which serves as a scaling prediction model.

[0038] The evaporation temperature and salinity of the low-temperature multi-effect evaporator are collected in real time. The operating parameters of the low-temperature multi-effect evaporator are controlled according to the scaling prediction model so that the evaporation temperature of the mine water reaches the preset temperature and the salinity of the mine water reaches the preset salinity, thereby preventing scaling of the low-temperature multi-effect evaporator.

[0039] The technical solution of the present invention has the following technical effects compared with the prior art:

[0040] This invention provides a waste heat-based anti-scaling low-temperature multi-effect high-mineralization mine water treatment system and method. It employs low-temperature multi-effect evaporation technology to concentrate and desalinate high-mineralization mine water, fully utilizing waste heat from power plants as power steam to reduce water production costs and save energy. To prevent crystallization and scaling in the low-temperature multi-effect evaporator, an automatic anti-scaling control device is used. During the low-temperature multi-effect evaporation process, the evaporation temperature and salinity of the high-mineralization mine water are monitored in real time as input conditions. A central processing module provides corresponding control commands to control the operating parameters of the low-temperature multi-effect evaporator, ensuring that the evaporation temperature and salinity reach preset levels. This prevents scaling in the low-temperature multi-effect evaporator, guarantees stable system operation, and provides technical guidance for pretreatment hardness removal processes. Attached Figure Description

[0041] The preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings, which will help to understand the purpose and advantages of the present invention, wherein:

[0042] Figure 1 This is a structural block diagram of a waste heat-type anti-scaling low-temperature multi-effect high-mineralization mine water treatment system according to one embodiment of this application;

[0043] Figure 2 This is a schematic diagram of the low-temperature multi-effect evaporator in a waste heat-type anti-scaling low-temperature multi-effect high-mineralization mine water treatment system according to an embodiment of this application.

[0044] Figure 3 This is a structural block diagram of an automatic anti-scaling control device in a waste heat-type anti-scaling low-temperature multi-effect high-mineralization mine water treatment system according to an embodiment of this application. Detailed Implementation

[0045] The technical solution of the present invention will now be clearly and completely described 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.

[0046] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0047] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0048] Furthermore, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0049] The solutions described in the following embodiments of the present invention address the problems of high investment costs, high energy consumption during evaporation, and easy scaling associated with existing high-salinity mine water concentration and desalination technologies. Based on this objective, the present invention provides a waste heat-type anti-scaling low-temperature multi-effect high-salinity mine water treatment system and method, such as... Figure 1 As shown, the system includes a low-temperature multi-effect evaporator and an automatic anti-scaling control device. The waste heat-type anti-scaling low-temperature multi-effect high-mineralization mine water treatment system and method provided by this invention uses low-temperature multi-effect evaporation technology to concentrate and desalinate high-mineralization mine water, fully utilizing waste heat from coal-fired power plants as a heat source to improve energy utilization efficiency, significantly reduce costs, and achieve high freshwater recovery rate and high water production ratio. Simultaneously, to prevent crystallization and scaling of high-mineralization mine water in the multi-effect evaporator, this system includes an automatic anti-scaling control device. During the low-temperature multi-effect evaporation process, the system monitors the mine water evaporation temperature and salinity of each stage of the evaporator in real time. Combined with a pre-set scaling prediction model, the degree of scaling in the low-temperature multi-effect evaporator is obtained. Based on the degree of scaling, the system adjusts the mine water evaporation temperature and salinity of the low-temperature multi-effect evaporator to prevent scaling and ensure stable system operation.

[0050] The waste heat-type anti-scaling low-temperature multi-effect high-mineralization mine water treatment system provided in this embodiment, combined with Figure 2 and Figure 3As shown: The low-temperature multi-effect evaporator includes a multi-effect evaporator and a steam ejector 13. The low-pressure secondary steam output from the previous evaporator in the multi-effect evaporator is input to the next evaporator. The steam ejector 13 receives waste heat steam from the power plant as motive steam and low-pressure secondary steam output from the last effect evaporator 3 in the multi-effect evaporator at its inlet. Its outlet has a first path connected to the first effect evaporator 1 in the multi-effect evaporator, a second path connected to the intermediate evaporator in the multi-effect evaporator, i.e., the [2-(n-1)] effect evaporator 2, and a third path connected to the [n-1] effect evaporator 2. The final-effect evaporator 3 is described above; the automatic anti-scaling control device includes a data acquisition module and a central processing module; the data acquisition module is used to collect the mine water evaporation temperature and mine water salinity of the low-temperature multi-effect evaporator, and to obtain the degree of scaling of the low-temperature multi-effect evaporator according to the scaling prediction model, which is pre-stored in the central processing module; the operating parameters of the low-temperature multi-effect evaporator are controlled according to the degree of scaling of the low-temperature multi-effect evaporator, so that the mine water evaporation temperature reaches the preset temperature and the mine water salinity reaches the preset salinity, so as to prevent scaling of the low-temperature multi-effect evaporator.

[0051] In the above scheme, the inlet end of the steam ejector 13 receives waste heat steam from the power plant as power steam. By introducing industrial waste heat from coal-fired power plants and other sources to drive low-temperature multi-effect evaporation technology, it replaces membrane methods to concentrate and desalinate high-mineralized mine water and produce fresh water, thereby achieving comprehensive utilization of water resources and effectively reducing the cost of fresh water production. The high-mineralized mine water first enters the first-effect evaporator 1 to exchange heat with heating steam, and the resulting secondary steam and residual brine enter the subsequent 2 to (n-1) effect evaporators respectively. The secondary steam generated by each stage of evaporator can be used as heating steam for the next stage of evaporator. The low-pressure secondary steam generated in the final-effect evaporator 3 is mixed with waste heat steam from the power plant and then pressurized by the steam ejector 13 to serve as the heating source for the first-effect evaporator 1, reducing the treatment cost of high-mineralized mine water.

[0052] To prevent scaling and precipitation of high-salinity mine water in the evaporators due to supersaturation of some salt components, which could affect the stable operation of the system, this solution equips the low-temperature multi-effect evaporator with an automatic anti-scaling control device. This device automatically controls and adjusts operating parameters such as evaporation pressure or flow rate to maintain the evaporation temperature at the optimal level, ensuring that no scaling occurs in the evaporators during the low-temperature multi-effect evaporation process. This saves on cleaning or equipment replacement costs. Specifically, the low-temperature multi-effect evaporator itself has a controller; the central processing module sends the control strategy to the corresponding controller to adjust the operating parameters of the low-temperature multi-effect evaporator.

[0053] In specific implementation, the central processing module uses CaSO4 in high-salinity mine water systems (Na+) + -Mg2+ -Ca 2 + -K + -Cl - -SO4 2- The solubility model of CaSO4 is used as a scaling prediction model. Preferably, CaSO4 is used in high-salinity mine water systems (Na+). + -Mg 2+ -Ca 2+ -K + -Cl - -SO4 2- The solubility model for ) was obtained as follows:

[0054] CaSO4 in high-salinity mine water systems (Na) + -Mg 2+ -Ca 2+ -K + -Cl - -SO4 2- The reaction represented by equation (1) will occur in ).

[0055]

[0056] The subscript aq indicates an aqueous solution.

[0057] The solubility constant Ksp of CaSO4 can be expressed as equation (2):

[0058]

[0059]

[0060] In the above formula, a is the activity of the component (unit: 1), m is the molality of the substance (unit: mol / kg), γ is the activity coefficient of the component (unit: 1), and S is the solubility (mol / kg).

[0061] The excess Gibbs free energy in the electrolyte NRTL activity coefficient model is decomposed into a long-range interaction (PDH) term described by the Pitzer-Debye-Hückel model and a short-range local interaction (lc) term described by the NRTL model, i.e.

[0062]

[0063] in, Indicates the excess Gibbs free energy. This represents the excess Gibbs free energy in the long-range interaction term. This represents the excess Gibbs free energy in the short-range interaction term, expressed in J / mol.

[0064] The activity coefficient of a mixed electrolyte can be expressed as:

[0065]

[0066] Where, γ i Let be the activity coefficient of component i, PDH represent the long-range interaction term, and lc represent the short-range interaction term.

[0067] The local compositional activity coefficients of molecules and cations (anions) in the mixed electrolyte NRTL model are as follows:

[0068] Activity coefficients of molecular components:

[0069]

[0070] Activity coefficients of cations (anions):

[0071]

[0072] Where X is the effective mole fraction; Z is the charge number of the ion; G is the excess Gibbs free energy (in J / mol); τ is the energy interaction parameter; subscripts a, a′, a″ represent anions; subscripts B, B′ represent molecules; subscripts c, c′, c″ represent cations; k represents the component number; ca represents electrolyte (cation-anion); ac represents electrolyte (anion-cation); i, j, k represent components.

[0073]

[0074] Among them, G iB Using the assumptions of local electrical neutrality and binary interactions, the normalization factor α follows the molar-average mixing rule.

[0075] The energy parameter τ can be obtained through the following relationship:

[0076] τ Ba,ca(ac) =τ a(c)B -τ ca,B +τ B,ca τ ca,c’a =-τ c’a,ca #(9)

[0077] The relationship between the normalization factor α and temperature is as follows:

[0078] α ij =A ij +B ij (TT r )#(10)

[0079] Normally, B = 0 in the formula, and the normalization factor is independent of temperature. When electrolytes interact with molecules, the normalization factor α generally takes the default value of 2; when electrolytes interact with each other, the normalization factor α generally takes the default value of 0.2. Energy interaction parameter τ ca,B(B,ca) , τ ca’,ca”(c’a,c”a) The relationship with temperature is as follows:

[0080]

[0081]

[0082] Among them, T r The reference temperature is typically 298.15 K, where T is the absolute temperature (in K), A and B are adjustable parameters of the normalization coefficient, and C, D, and E are adjustable parameters of the energy parameters.

[0083] By determining the energy parameter coefficients C, D, and E, the energy action parameters can be identified. The adjustable parameters C, D, and E can be obtained from the experimental data using maximum likelihood programming regression. The objective function for maximum likelihood programming optimization is:

[0084]

[0085] Where σ is the standard deviation, exp is the experimental value, cal is the simulated value, and ω1, ω2, and ω3 are empirical parameters obtained by fitting the experimental data.

[0086] Establishing CaSO4 in high-salinity mine water systems (Na) + -Mg 2+ -Ca 2+ -K + -Cl - -SO4 2- The process of developing the solubility model is as follows: Based on Aspen Plus software, using the ELECNRTL model, and after determining Ksp, the solubility model is developed using formula F. OB To optimize the objective function, regression analysis was performed on all experimental data to obtain the electrolyte pair parameters of the target system.

[0087] Utilizing the established CaSO4 in high-salinity mine water systems (Na) + -Mg 2+ -Ca 2+ -K + -Cl - -SO4 2- The solubility model for CaSO4 can predict its solubility at different temperatures and salinities relatively well. This model is then input into the central processing module as a scaling prediction model.

[0088] Furthermore, such as Figure 2As shown, the low-temperature multi-effect evaporator further includes: a first heating steam control valve 15, located between the second path of the steam ejector outlet and the intermediate section evaporator in the multi-effect evaporator; a second heating steam control valve 16, located between the third path of the steam ejector outlet and the final effect evaporator 3 in the multi-effect evaporator; the first heating steam control valve 15 and the second heating steam control valve 16 are connected to the central processing module. The central processing module can adjust the steam flow rate for heating the intermediate section evaporator and the final effect evaporator by controlling the opening degree of the first heating steam control valve 15 and the second heating steam control valve 16, thereby regulating the heating temperature of the intermediate section evaporator and the final effect evaporator. In specific implementation, the data acquisition module is also used to acquire the evaporation pressure of the mine water in the low-temperature multi-effect evaporator and send the evaporation pressure to the central processing module; the central processing module controls the evaporation pressure to a target pressure so that the evaporation temperature of the mine water reaches a preset temperature and the salinity of the mine water reaches a preset salinity. In the low-temperature multi-effect evaporation process, the evaporation temperature, pressure, and salinity of high-mineralization mine water are monitored in real time as input conditions. The central processing module automatically generates a control strategy, changing parameters such as the evaporation temperature and adjusting the heating steam flow rate to prevent scaling in the evaporator and ensure stable system operation. The target pressure, preset temperature, and preset salinity can be empirical values ​​or predetermined through calibration tests and stored in the central processing module. These values ​​correspond to those that ensure the evaporator of the low-temperature multi-effect evaporation device will not structurally fail.

[0089] Preferably, such as Figure 2As shown, the low-temperature multi-effect evaporator also includes a condenser 4, located at the rear end of the last-effect evaporator 3, which receives a portion of the low-pressure secondary steam output from the last-effect evaporator 3. Its output end is connected to the raw material inlet of the first-effect evaporator 1. A pretreatment module 14 is located between the input end of the condenser 4 and the raw material tank 12, used to pretreat the high-mineralization mine water output from the raw material tank 12, and then transport the pretreated high-mineralization mine water to the condenser 4. Specifically, the high-mineralization mine water is stored in the raw material tank 12. After preheating, the high-mineralization mine water in the raw material tank 12 is pumped into the condenser 4 by the raw material pump 7. The high-mineralization mine water raw material is then added to the first-effect evaporator 1 by spraying. After heat exchange and evaporation, the concentrate enters the next-effect evaporator for further evaporation, and so on until the last-effect evaporator 3. The concentrate discharged from the last-effect evaporator 3 enters the concentrate tank 10 for subsequent processing. During this process, the raw material pump 7 can be controlled by the central processing module. It can determine whether to increase or decrease the amount of mine water entering the evaporator based on the fresh water flow rate, thereby determining whether to increase or decrease the power of the raw material pump 7 to change the amount of mine water entering the low-temperature multi-effect evaporator. If the current fresh water flow rate is appropriate, the power of the raw material pump 7 is controlled to remain constant. Waste heat steam from the power plant is used as motive steam, entering the steam inlet of the steam ejector 13 and entraining the low-pressure secondary steam from the final-effect evaporator 3. The resulting heating steam, after mixing in the steam ejector 13, becomes the heating source for the first-effect evaporator 1. This heating steam is added from the steam inlet of the first-effect evaporator 1 and exchanges heat with the preheated high-mineralization mine water raw material liquid. The condensed heating steam then becomes fresh water. The low-pressure secondary steam generated from the evaporation of the high-mineralization mine water raw material liquid serves as the heating steam for the next stage evaporator. This process continues, with part of the low-pressure secondary steam generated by the final-effect evaporator 3 being entrained by the motive steam into the steam ejector 13, and the remainder entering the condenser 4 to preheat the high-mineralization mine water before condensing it into fresh water.

[0090] In the above scheme, the low-temperature multi-effect evaporator further includes a concentrate tank 10, connected to the output port of the last-effect evaporator 3, for collecting the concentrate output by the last-effect evaporator 3; and a desalination tank 11, connected to the desalination output port of each stage evaporator, for collecting the desalination output by each stage evaporator. The raw material pump 7 in the low-temperature multi-effect evaporator is located between the pretreatment module 14 and the raw material tank 12.

[0091] The low-temperature multi-effect evaporator also includes a concentrate pump 6, located between the last-effect evaporator 3 and the concentrate tank 10; and a desalination pump 8, located between the desalination outlet of each stage evaporator and the desalination tank 11. The raw material pump 7, the concentrate pump 6, and the desalination pump 8 all operate under the control of the central processing module. As shown in the figure, the above device also includes a demister 5 in each stage evaporator, which also includes a vacuum pump 9 for performing a vacuum operation on the evaporator. In this scheme, a concentrate pump 6 is installed on the pipeline before the concentrate tank 10 to assist in transporting the concentrated liquid discharged from the last-effect evaporator 3 into the concentrate tank 10. A raw material pump 7 is installed on the pipeline between the raw material tank 12 and the condenser 4 to assist in transporting high-mineralization mine water to the condenser 4. A pretreatment module 14 is installed on this pipeline to pretreat the high-mineralization mine water, removing suspended solids, volatile organic compounds, and hardness. A freshwater pump 8 is installed on the pipeline before the freshwater tank 11 to assist in transporting the condensed freshwater output from each evaporator to the freshwater tank 11.

[0092] When high-mineralized mine water evaporates in various evaporators, local heat transfer fluctuations may cause some components of the brine to exceed their solubility on the evaporator surface, precipitating crystals and causing scaling. This solution configures an anti-scaling automatic control system for the overall low-temperature multi-effect evaporation system. Figure 3 As shown, the anti-scaling automatic control device also includes an A / D conversion module, a human-machine interface module, a D / A conversion module, a PID control module, and an output execution port. The data acquisition module includes a temperature sensor, a salinity sensor for high-salinity mine water, a flow sensor, and a pressure sensor. Using these sensors, the data acquisition module can obtain parameters such as the flow rate of heating steam and the evaporation temperature, salinity, and pressure of mine water in different evaporators. The human-machine interface module provides feedback on the system's operating status to the control personnel and allows for the setting of control parameters for the low-temperature multi-effect evaporation system, including the amount of heating steam and fresh water. The D / A and A / D conversion modules are used for converting between analog and digital signals; the central processing module stores the system's core control algorithm, high-salinity mine water solubility data, the ELECNRTL model, and required physical property parameters; the PID control module smooths the control logic obtained from the algorithm; and the output execution port sends adjustment commands to the system to regulate the system's pressure and flow rate.

[0093] This application also provides an industrial waste heat-type anti-scaling low-temperature multi-effect high-mineralization mine water treatment method, including:

[0094] S10: Obtain the variation of calcium sulfate solubility in high-mineralization mine water during low-temperature multi-effect evaporation within a set range, as a function of mine water evaporation temperature and mine water salinity. This step can be determined through calibration experiments.

[0095] S20: Based on the process flow simulation system software, the thermodynamic parameters and parameter model of calcium sulfate dissolution are obtained by fitting the ELECNRTL model.

[0096] S30: Based on the aforementioned variation pattern, the thermodynamic parameters and parameter model are adjusted and optimized to obtain a calcium sulfate solubility model that varies within the specified range, which serves as a scaling prediction model.

[0097] S40: Real-time acquisition of the evaporation temperature and mine water salinity of the low-temperature multi-effect evaporator, and control of the operating parameters of the low-temperature multi-effect evaporator according to the scaling prediction model, so that the evaporation temperature of the mine water reaches the preset temperature and the salinity of the mine water reaches the preset salinity, in order to prevent scaling of the low-temperature multi-effect evaporator.

[0098] In practical applications, the central processing module first obtains high-mineralization mine water with composition variations within a certain range through experimental testing. The solubility variations of typical low-solubility salts (e.g., CaSO4) with temperature and salinity during low-temperature multi-effect evaporation are compiled into a database. A new thermodynamic parameter and model are obtained by fitting the electrolyte solution ELECNRTL model. Through parameter adjustment and optimization, a scaling model for high-mineralization mine water with composition variations within a certain range is obtained as the algorithm for the generation control strategy. During the low-temperature multi-effect evaporation of high-mineralization mine water, the data acquisition module collects the mine water evaporation temperature and salinity in real time, and sends the collected data to the central processing module via the A / D conversion module. The central processing module determines the scaling situation of the evaporator under current conditions based on the internally stored CaSO4 solubility data variation pattern and the structural prediction model. After smoothing by the PID control module, the control method is sent to the output execution port via the D / A conversion module to control the operating parameters of the low-temperature multi-effect evaporation device, such as mine water flow rate and pressure, and heating steam flow rate and pressure.

[0099] In the above scheme, the evaporation temperature is controlled to the optimal temperature by timely adjusting the operating parameters of the low-temperature multi-effect evaporator, ensuring stable system operation after temperature changes. During operation, the first and second steam heating control valves can be opened to supplement the evaporator with heating steam to ensure stable system operation. When the evaporation temperature is at the optimal temperature and the freshwater production and water production ratio meet the target values, the evaporation temperature and salinity of the next effect are collected. By continuously collecting data from the first effect to the last effect, the evaporation temperature and salinity of high-mineralization mine water are monitored in real time, thereby preventing scaling in the evaporator. In practical applications, sensors can be installed on each evaporator to collect the required data, and a steam heating control valve can be installed at the steam inlet of each stage of the evaporator. Therefore, this scheme can perform the above data collection and operating parameter adjustment for each stage of the evaporator. After the operating parameters of the first stage of the evaporator meet the anti-scaling requirements, data collection and operating parameter adjustment for the next stage of the evaporator can be performed.

[0100] The following is a specific example of a process for treating highly salinized mine water:

[0101] Table 1. Water quality of high-salinity mine water in a certain mine.

[0102] Test results 38.4 267.3 1881 75.6 1302 2925 7.7 6490 401

[0103] Table 1 shows the water quality of highly salinized mine water collected from a certain mine. Except for pH, all data are in mg / L; alkalinity is expressed as bicarbonate. The mine water shown in Table 1 was treated using the apparatus described in the above embodiments:

[0104] First, high-mineralized mine water, with a temperature of 25℃, a TDS (Total Dissolved Solids) of 6490 mg / L, and a flow rate of 116 kg / h, enters the pretreatment module 14 under the action of the raw material pump 7. After removing suspended solids, volatile organic compounds, and hardness, it enters the condenser 4 for preheating to a temperature of 38℃, and then enters the first-effect evaporator 1, where the evaporation temperature is 70℃. Waste heat steam from the power plant at 295℃ is used as motive steam, entering the steam ejector 13 and entraining a portion of the secondary steam at 40℃ generated by the last-effect evaporator 3. Together, these secondary steam serve as the heating steam for the first-effect evaporator 1, which is saturated steam at 80℃. After heat exchange and evaporation in the first-effect evaporator 1, the concentrated liquid enters the next-effect evaporator under the pressure difference between effects, continuing until the last-effect evaporator 3. A six-effect evaporator with co-current flow is used to treat the high-salinity mine water. The evaporation temperature of each effect decreases by 6°C. The concentrated liquid is discharged from the last-effect evaporator 3 and, driven by the concentrated water pump 6, enters the concentrated liquid storage tank 10 for further processing. The secondary steam generated in the first-effect evaporator 1 passes through the demister 5 and enters the next-effect evaporator as a heating source, where it is condensed into fresh water. This process continues until the last effect. The fresh water generated by each effect evaporator is collected and sent to the fresh water storage tank 11 by the fresh water pump 8.

[0105] Industrial waste heat: Waste heat steam from coal-fired power plants is the main heat source for low-temperature multi-effect evaporation systems, with a temperature of 295℃.

[0106] The results obtained through actual low-temperature multi-effect evaporation operations are shown in Table 2: the concentrate content and CaSO4 content (unit: mg / L) in each effect evaporator, and the freshwater yield (unit: kg / h) in each effect evaporator.

[0107] Table 2. Saltwater concentration and evaporation rate in each effect evaporator

[0108] Concentrate content 7235 8255 9683 11798 15216 21597 <![CDATA[Calcium sulfate content]]> 1005 1147 1345.3 1639 2114 3000 Freshwater production 12.14 12.83 13.42 13.92 14.31 14.6

[0109] By comparing Table 2 and Table 1, it can be determined that after six-effect evaporation, the salt content of the high-mineralization mine water changed from 6490 mg / L to 21597 mg / L, meaning that more CaSO4 was retained in the concentrate; since CaSO4 is a slightly soluble substance... 2+ and SO4 2- CaSO4 easily combines and forms precipitates that adhere to the surface of the evaporator heat transfer tubes, leading to decreased heat transfer efficiency and reduced freshwater production. Therefore, this embodiment uses a mixed electrolyte NRTL model to regress experimental data and obtain new model parameters. The model can be used to predict the solubility of CaSO4 in a high-salinity mine water system (Na+-Mg2+-Ca2+-K+-Cl--SO42-) at different temperatures and concentrations, providing a theoretical basis for avoiding CaSO4 scaling in high-salinity mine water during low-temperature multi-effect evaporation.

[0110] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A waste heat-type anti-scaling low-temperature multi-effect high-mineralization mine water treatment system, characterized in that, This includes a low-temperature multi-effect evaporator and an automatic anti-scaling control device, wherein: The low-temperature multi-effect evaporator includes a multi-effect evaporator and a steam ejector: the low-pressure secondary steam output from the previous evaporator in the multi-effect evaporator is input to the next evaporator; the steam ejector receives waste heat steam from the power plant and low-pressure secondary steam output from the last effect evaporator in the multi-effect evaporator at its inlet end, the first path of its outlet end is connected to the first effect evaporator in the multi-effect evaporator, the second path of its outlet end is connected to the middle section evaporator in the multi-effect evaporator, and the third path of its outlet end is connected to the last effect evaporator. The anti-scaling automatic control device includes a data acquisition module and a central processing module. The data acquisition module is used to collect the evaporation temperature and salinity of the mine water in the low-temperature multi-effect evaporator, and to obtain the degree of scaling of the low-temperature multi-effect evaporator according to the scaling prediction model. The operating parameters of the low-temperature multi-effect evaporator are controlled according to the degree of scaling to ensure that the evaporation temperature of the mine water reaches a preset temperature and the salinity of the mine water reaches a preset salinity, so as to prevent scaling of the low-temperature multi-effect evaporator.

2. The waste heat-type anti-scaling low-temperature multi-effect high-mineralization mine water treatment system according to claim 1, characterized in that: In the central processing module, the solubility model of calcium sulfate in a high-mineralization mine water system is used as the scaling prediction model.

3. The waste heat-type anti-scaling low-temperature multi-effect high-mineralization mine water treatment system according to claim 1, characterized in that, The low-temperature multi-effect evaporator also includes: A first heating steam control valve is located between the second path of the steam ejector outlet and the intermediate section evaporator in the multi-effect evaporator; The second heating steam control valve is located between the third path at the outlet end of the steam ejector and the last effect evaporator in the multi-effect evaporator; The first heating steam control valve and the second heating steam control valve are connected to the central processing module.

4. The waste heat-type anti-scaling low-temperature multi-effect high-mineralization mine water treatment system according to claim 1, characterized in that: The data acquisition module is also used to acquire the mine water evaporation pressure of the low-temperature multi-effect evaporation device and send the mine water evaporation pressure to the central processing module; The central processing module controls the evaporation pressure of the mine water to a target pressure so that the evaporation temperature of the mine water reaches a preset temperature and the salinity of the mine water reaches a preset salinity.

5. The waste heat-type anti-scaling low-temperature multi-effect high-mineralization mine water treatment system according to claim 1, characterized in that, The low-temperature multi-effect evaporator also includes: A condenser is located at the rear end of the last-effect evaporator and receives a portion of the low-pressure secondary steam output from the last-effect evaporator. Its output end is connected to the raw material inlet of the first-effect evaporator. A pretreatment module is installed between the input end of the condenser and the raw material tank. It is used to pretreat the high-mineralization mine water output from the raw material tank and then transport the pretreated high-mineralization mine water to the condenser.

6. The waste heat-type anti-scaling low-temperature multi-effect high-mineralization mine water treatment system according to claim 5, characterized in that: The data acquisition module is also used to acquire the freshwater flow rate output by the low-temperature multi-effect evaporator and send the freshwater flow rate to the central processing module; The central processing module controls the flow rate of high-mineralized mine water entering the first-effect evaporator based on the relationship between the freshwater flow rate and the preset standard flow rate.

7. The waste heat-type anti-scaling low-temperature multi-effect high-mineralization mine water treatment system according to claim 6, characterized in that, The low-temperature multi-effect evaporator also includes: A concentrate tank is connected to the output port of the last-effect evaporator and is used to collect the concentrate output by the last-effect evaporator. A freshwater tank is connected to the freshwater outlet of each stage of the evaporator and is used to collect the freshwater output from each stage of the evaporator.

8. The waste heat-type anti-scaling low-temperature multi-effect high-mineralization mine water treatment system according to claim 7, characterized in that, The low-temperature multi-effect evaporator also includes: A raw material pump is installed between the pretreatment module and the raw material tank; A concentrate pump is installed between the final-effect evaporator and the concentrate tank; A freshwater pump is installed between the freshwater outlet of each stage evaporator and the freshwater tank; The raw material pump, the concentrate pump, and the desalination pump all operate under the control of the central processing module.

9. The waste heat-type anti-scaling low-temperature multi-effect high-mineralization mine water treatment system according to any one of claims 1-8, characterized in that, The automatic anti-scaling control device also includes: An A / D conversion module is located between the data acquisition module and the central processing module, and converts the information acquired by the data acquisition module into a digital signal and inputs it to the central processing module. The PID control module is used to convert the control strategy output by the central processing module into control commands to adjust the operating parameters of the low-temperature multi-effect evaporator. The D / A conversion module is connected to the PID control module and is used to convert the control command into an analog control signal and send it to the output execution terminal.

10. A method for treating high-mineralization, low-temperature, multi-effect mine water using industrial waste heat-based anti-scaling technology, characterized in that... include: The study aimed to obtain the variation of calcium sulfate solubility in high-mineralization mine water under low-temperature multi-effect evaporation within a set range, as a function of mine water evaporation temperature and mine water salinity. Based on the process flow simulation system software, the thermodynamic parameters and parameter model of calcium sulfate dissolution were obtained by fitting the ELECNRTL model. Based on the aforementioned variation pattern, the thermodynamic parameters and parameter model are adjusted and optimized to obtain a calcium sulfate solubility model that varies within the specified range, which serves as a scaling prediction model. The evaporation temperature and salinity of the low-temperature multi-effect evaporator are collected in real time. The operating parameters of the low-temperature multi-effect evaporator are controlled according to the scaling prediction model so that the evaporation temperature of the mine water reaches the preset temperature and the salinity of the mine water reaches the preset salinity, thereby preventing scaling of the low-temperature multi-effect evaporator.

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