Thermal power plant reverse osmosis concentrated water treatment method and treatment system

Abstract

The invention discloses a thermal power plant reverse osmosis concentrated water treatment method and treatment system.The thermal power plant reverse osmosis concentrated water treatment method comprises the steps that reverse osmosis concentrated water generated by a thermal power plant is introduced into a pretreatment unit to be pretreated, and pretreatment comprises pH value adjusting and suspended matter filtering and removing; introducing the pretreated reverse osmosis concentrated water into an induced crystallization unit to be in full contact with a crystallization carrier in the induced crystallization unit, and carrying out induced crystallization treatment on the crystallization carrier; feeding the reverse osmosis concentrated water subjected to induced crystallization treatment by the crystallization carrier into a hollow fiber nanofiltration device, and carrying out nanofiltration treatment; and feeding the produced water subjected to nanofiltration treatment by the hollow fiber nanofiltration device into a nanofiltration produced water recycling unit. According to the thermal power plant reverse osmosis concentrated water treatment method provided by the embodiment of the invention, reduction treatment and recycling of reverse osmosis concentrated water are realized through crystal carrier induced crystallization treatment and filtration treatment of the hollow fiber nanofiltration device.

Description

Technical Field

[0001] The present invention relates to the field of reverse osmosis concentrated water treatment, and in particular to a method and a treatment system for treating reverse osmosis concentrated water in a thermal power plant. Background Art

[0002] As an efficient and widely used standard water treatment technology, reverse osmosis technology has been deeply involved in the purification treatment of industrial and domestic water, and has become an important part of ensuring water quality safety. In industrial production, especially in high water-consuming industries such as thermal power plants, reverse osmosis technology plays an irreplaceable role. However, during the reverse osmosis process, a large amount of reverse osmosis concentrated water will inevitably be generated. These reverse osmosis concentrated waters contain high concentrations of dissolved solids, inorganic salts, organic substances, and potentially heavy metals and other pollutants. Their components are complex and difficult to directly discharge or reuse, posing a potentially serious threat to the environment and human health. Summary of the Invention

[0003] The present invention aims to at least solve one of the technical problems existing in the prior art. To this end, an object of the present invention is to provide a method for treating reverse osmosis concentrated water in a thermal power plant, which can achieve the reduction treatment and recycling of reverse osmosis concentrated water.

[0004] The present invention also provides a treatment system for treating reverse osmosis concentrated water in a thermal power plant.

[0005] The method for treating reverse osmosis concentrated water in a thermal power plant according to the first aspect embodiment of the present invention includes: introducing the reverse osmosis concentrated water generated during the reverse osmosis process in the thermal power plant into a pretreatment unit for pretreatment, where the pretreatment includes adjusting the pH value and filtering to remove suspended solids; introducing the pretreated reverse osmosis concentrated water into an induced crystallization unit, and fully contacting with the crystallization carrier in the induced crystallization unit for crystallization carrier-induced crystallization treatment; sending the reverse osmosis concentrated water after the crystallization carrier-induced crystallization treatment into a hollow fiber nanofiltration device for nanofiltration treatment; and sending the water produced after the nanofiltration treatment by the hollow fiber nanofiltration device into a nanofiltration produced water recycling unit for recycling.

[0006] According to the reverse osmosis concentrated water treatment method of the embodiment of the present invention, pretreatment is carried out through a pretreatment unit to adjust the pH value of the reverse osmosis concentrated water and filter out suspended solids, so that large particle impurities in the suspended solids are filtered out from the reverse osmosis concentrated water, preventing the suspended solids from affecting the subsequent induced crystallization process and nanofiltration treatment process; through crystallization carrier induced crystallization treatment, the dissolved solids in the reverse osmosis concentrated water are precipitated in a crystalline form, thereby reducing the dissolved solid content in the reverse osmosis concentrated water; through filtration treatment by a hollow fiber nanofiltration device, water molecules and small molecule solutes pass through the hollow fiber nanofiltration device, and pollutants such as dissolved solids, inorganic salts, organic substances and heavy metals are separated from the reverse osmosis concentrated water, thereby realizing the reduction treatment and recycling of the reverse osmosis concentrated water.

[0007] According to some embodiments of the present invention, in the pretreatment step, the adjusting of the pH value includes: adjusting the pH value to between 10 and 12.

[0008] According to some embodiments of the present invention, in the pretreatment step, the filtration accuracy of the filtration treatment is 5 to 10 μm, and the filtration media used for the filtration treatment include quartz sand, anthracite and fiber balls.

[0009] According to some embodiments of the present invention, the process parameters of the crystallization carrier induced crystallization treatment include: water temperature 20 to 40 °C, pH 10 to 12, pressure 0.4 to 0.6 MPa, and stirring speed less than 200 rpm;

[0010] According to some embodiments of the present invention, the crystallization carrier is a silicate-based crystal seed, and the silicate-based crystal seed includes a solid mixture containing calcium, silicon and aluminum, a strong base and a binder. The silicate-based crystal seed has a porous structure and a hydroxyl functional group on its surface, and the surface of the silicate-based crystal seed has a microstructure that promotes crystal growth.

[0011] According to some embodiments of the present invention, in the crystallization carrier induced crystallization treatment step, by monitoring the crystallization situation in the induced crystallization unit to judge whether the preset crystallization treatment requirements are met. Among them, the preset crystallization treatment requirements include: the crystal size distribution satisfies that D50 is between 100 and 500 μm, the crystal morphology is regular, and the crystal concentration is between 10 and 50 g / L.

[0012] According to some embodiments of the present invention, in the nanofiltration treatment step, the hollow fiber nanofiltration device uses a hollow fiber membrane as a filtration medium, and the reverse osmosis concentrated water is driven through the hollow fiber nanofiltration membrane by a high-pressure pump to realize the nanofiltration treatment of the reverse osmosis concentrated water.

[0013] According to some embodiments of the present invention, in the nanofiltration treatment step, the operating pressure is controlled at 0.6 MPa, and the flow rate range is 1.8 - 6.0 m 3 / hr.

[0014] According to some embodiments of the present invention, in the nanofiltration treatment step, it is judged whether the nanofiltration treatment requirements are met according to the water production rate and rejection rate of the hollow fiber nanofiltration device. Among them, the nanofiltration treatment requirements include: the water production rate is between 20 and 25 m 3 / h, and the rejection rate of divalent salts is between 90% and 95%.

[0015] According to some embodiments of the present invention, the water produced after nanofiltration treatment is recycled, including: recycling the water produced after nanofiltration treatment as cooling water, process water or other non-drinking water uses in a thermal power plant.

[0016] The reverse osmosis concentrate treatment system for a thermal power plant according to the second aspect embodiment of the present invention is used to implement the reverse osmosis concentrate treatment method for a thermal power plant in the first aspect embodiment of the present invention above. The reverse osmosis concentrate treatment system for a thermal power plant includes: the pretreatment unit, the induced crystallization unit, the hollow fiber nanofiltration device, and the nanofiltration produced water recycling unit.

[0017] According to the reverse osmosis concentrate treatment system for a thermal power plant of the embodiment of the present invention, the above-mentioned reverse osmosis concentrate treatment method for a thermal power plant can be realized by using this reverse osmosis concentrate treatment system for a thermal power plant. Through the pretreatment unit for pretreatment, the pH value of the reverse osmosis concentrate is adjusted, and suspended solids are filtered out, so that large particle impurities in the suspended solids are filtered out from the reverse osmosis concentrate, preventing subsequent suspended solids from blocking the induced crystallization unit and the hollow fiber nanofiltration device and affecting the precipitation of dissolved solids in the crystallization carrier-induced crystallization treatment; through the crystallization carrier-induced crystallization treatment, the dissolved solids in the reverse osmosis concentrate are precipitated in a crystalline form, thereby reducing the content of dissolved solids in the reverse osmosis concentrate; through the filtration treatment by the hollow fiber nanofiltration device, water molecules and small molecule solutes pass through the hollow fiber nanofiltration device, and pollutants such as dissolved solids, inorganic salts, organic substances, and heavy metals are separated from the reverse osmosis concentrate, thereby realizing the reduction treatment and recycling of the reverse osmosis concentrate.

[0018] According to some embodiments of the present invention, the pretreatment unit includes a first chemical dosing device and a multi-media filter. The first chemical dosing device is used to add alkali to the reverse osmosis concentrate to adjust the pH value. The first chemical dosing device includes a first chemical storage tank and a first metering pump. The first metering pump is connected to the first chemical storage tank and is used to put the alkali in the first chemical storage tank into the reverse osmosis concentrate. The first chemical storage tank is made of corrosion-resistant material, and the corrosion-resistant material is polyvinyl chloride or fiberglass.

[0019] According to some embodiments of the present invention, the induced crystallization unit includes a crystallization reactor, a temperature sensor, and a pH sensor. The temperature sensor and the pH sensor are both installed in the crystallization reactor. A crystallization carrier is placed in the crystallization reactor. The temperature sensor is used to detect the temperature in the crystallization reactor, and the pH sensor is used to detect the pH value of the reverse osmosis concentrated water in the crystallization reactor.

[0020] According to some embodiments of the present invention, the reverse osmosis concentrated water treatment system of the thermal power plant further includes an online turbidimeter or a particle analyzer, which is used to online monitor the crystallization situation in the crystallization reactor;

[0021] According to some embodiments of the present invention, the reverse osmosis concentrated water treatment system of the thermal power plant further includes a second chemical dosing device, which is used to put alkali into the crystallization reactor.

[0022] The additional aspects and advantages of the present invention will be partly given in the following description, partly will become obvious from the following description, or will be understood through the practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The above and / or additional aspects and advantages of the present invention will become obvious and easy to understand from the description of the embodiments in conjunction with the following drawings, in which:

[0024] Figure 1 Flow schematic diagram of the reverse osmosis concentrated water treatment method for a thermal power plant according to some embodiments of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0025] The embodiments of the present invention will be described in detail below. The examples of the embodiments are shown in the drawings, in which the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the drawings are exemplary and are only used to explain the present invention and should not be construed as a limitation of the present invention.

[0026] Reference is made below to Figure 1 Describe the reverse osmosis concentrated water treatment method for a thermal power plant according to the embodiments of the present invention.

[0027] The reverse osmosis concentrated water treatment method for a thermal power plant according to the first aspect embodiment of the present invention includes:

[0028] The reverse osmosis concentrate generated in the reverse osmosis process of a thermal power plant is introduced into a pretreatment unit for pretreatment. The pretreatment includes adjusting the pH value and filtering to remove suspended solids. By adjusting the pH value of the reverse osmosis concentrate, the reverse osmosis concentrate can meet the reaction conditions for subsequent treatment steps. By filtering to remove suspended solids, the particulate impurities in the suspended solids are filtered out from the reverse osmosis concentrate, preventing the suspended solids from affecting the subsequent induced crystallization process and nanofiltration treatment process. For example, it can prevent or reduce the influence of suspended solids in the solution on the precipitation efficiency of dissolved solids in the crystallization carrier-induced crystallization treatment during the induced crystallization process. For example, it can also reduce or prevent the blockage of the hollow fiber nanofiltration device used in the nanofiltration treatment by suspended solids, thus affecting its filtration effect, which is beneficial to improving the efficiency and treatment quality of subsequent treatment steps;

[0029] The pretreated reverse osmosis concentrate is introduced into the induced crystallization unit and brought into full contact with the crystallization carrier in the induced crystallization unit for crystallization carrier-induced crystallization treatment. Among them, the crystallization carrier can play a role in initiating the growth of active component crystals or crystal grains. In the induced crystallization unit, the reverse osmosis concentrate is in full contact with the crystallization carrier, and under suitable crystallization conditions, dissolved solids can crystallize and precipitate;

[0030] The reverse osmosis concentrate after crystallization carrier-induced crystallization treatment is sent to a hollow fiber nanofiltration device for nanofiltration treatment. Among them, compared with ordinary filtration methods, hollow fiber nanofiltration has a higher filtration accuracy, and the hollow fiber nanofiltration device has the characteristics of high flux and high rejection rate. When the reverse osmosis concentrate is treated by the hollow fiber nanofiltration device, water molecules and small molecule solutes will not be blocked by the hollow fiber nanofiltration device, while most pollutants such as dissolved solids, inorganic salts, organic substances, and heavy metals are retained outside the device;

[0031] The water produced after nanofiltration treatment by the hollow fiber nanofiltration device is sent to the nanofiltration produced water recycling unit for recycling.

[0032] According to the reverse osmosis concentrated water treatment method of the embodiment of the present invention, pretreatment is carried out through a pretreatment unit to adjust the pH value of the reverse osmosis concentrated water and filter out suspended solids, so that large particle impurities in the suspended solids are filtered out from the reverse osmosis concentrated water, preventing the suspended solids from affecting the subsequent induced crystallization process and nanofiltration treatment process. It can prevent or reduce the influence of suspended solids in the solution on the precipitation efficiency of dissolved solids in the crystallization carrier-induced crystallization treatment during the induced crystallization process, and can also reduce or prevent the blockage of the hollow fiber nanofiltration device used in the nanofiltration treatment by suspended solids, thus affecting its filtration effect, which is beneficial to improving the efficiency and treatment quality of subsequent steps; through the crystallization carrier-induced crystallization treatment, the dissolved solids in the reverse osmosis concentrated water are precipitated in a crystalline form, thereby reducing the content of dissolved solids in the reverse osmosis concentrated water; through the filtration treatment by the hollow fiber nanofiltration device, water molecules and small molecule solutes pass through the hollow fiber nanofiltration device, and pollutants such as dissolved solids, inorganic salts, organic substances, and heavy metals are separated from the reverse osmosis concentrated water, thereby realizing the reduction treatment and recycling of the reverse osmosis concentrated water.

[0033] According to some embodiments of the present invention, in the pretreatment step, adjusting the pH value includes: adjusting the pH value to between 10 and 12. For example, the pH value adjusted in the pretreatment step can be 10, 10.5, 11, 11.5, 12, etc. The solubility of different salts is different at different pH values. By adjusting the pH value, this solubility difference can be utilized to achieve the separation of dissolved solids.

[0034] According to some embodiments of the present invention, in the pretreatment step, the filtration accuracy of the filtration treatment is 5 to 10 μm, and the filtration media used in the filtration treatment include quartz sand, anthracite, and fiber balls. For example, the filtration accuracy of the filtration treatment in the pretreatment step can be 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, etc. By filtering with filtration media such as quartz sand, anthracite, and fiber balls, large particle suspended solids in the reverse osmosis concentrated water can be removed, reducing the difficulty of treating the reverse osmosis concentrated water in subsequent steps.

[0035] According to some embodiments of the present invention, the process parameters of the crystallization carrier-induced crystallization treatment include: water temperature 20 to 40 °C, pH 10 to 12, pressure 0.4 to 0.6 MPa, and stirring speed less than 200 rpm.

[0036] For example, the water temperature of the process parameters for the crystallization carrier-induced crystallization treatment can be 20°C, 25°C, 30°C, 35°C, 40°C, etc.; the pressure of the process parameters for the crystallization carrier-induced crystallization treatment can be 0.4 MPa, 0.45 MPa, 0.5 MPa, 0.55 MPa, 0.6 MPa, etc.; the stirring speed of the process parameters for the crystallization carrier-induced crystallization treatment can be 195 rpm, 190 rpm, 185 rpm, 180 rpm, etc. By adjusting the appropriate water temperature, pressure, and stirring speed, a lower supersaturation can be maintained in the reverse osmosis concentrated aqueous solution, enabling more soluble impurities to precipitate in solid form.

[0037] According to some embodiments of the present invention, the crystallization carrier is a silicate-based seed crystal. The silicate-based seed crystal includes a solid mixture containing calcium, silicon, and aluminum, a strong base, and a binder. The silicate-based seed crystal has a porous structure and a hydroxyl functional group on its surface, and the surface of the silicate-based seed crystal has a microstructure that promotes crystal growth.

[0038] Among them, the crystallization carrier is a silicate-based seed crystal. During the precipitation process of soluble impurities, the silicate-based seed crystal serves as the nucleation starting point, which can reduce the energy barrier for nucleation and provide the surface required for nucleation, thereby promoting the formation of soluble impurity crystals; the silicate-based seed crystal has a porous structure and a hydroxyl functional group on its surface, which can increase the specific surface area for the precipitation of soluble impurity crystals and improve the precipitation efficiency of soluble impurity crystals; the surface of the silicate-based seed crystal has a microstructure that promotes crystal growth, which can accelerate the precipitation rate of soluble impurities in crystal form.

[0039] According to some embodiments of the present invention, in the crystallization carrier-induced crystallization treatment step, by monitoring the crystallization situation in the induction crystallization unit, it is determined whether the preset crystallization treatment requirements are met. Among them, the preset crystallization treatment requirements include: the crystal size distribution satisfies that D50 is between 100 and 500 μm, the crystal morphology is regular, and the crystal concentration is between 10 and 50 g / L. By monitoring the crystallization situation in the induction crystallization unit, corresponding adjustments can be made to the process parameters of the induction crystallization unit.

[0040] The median diameter (D50) refers to the particle size value corresponding to when the cumulative distribution percentage reaches 50%, that is, in a sample, 50% of the particle sizes are larger than D50 and 50% of the particle sizes are smaller than D50.

[0041] For example, the D50 that satisfies the crystal size distribution required by the preset crystallization treatment can be: 100μm, 150μm, 200μm, 250μm, 300μm, 350μm, 400μm, 450μm, 500μm, etc.; the crystal concentration required by the preset crystallization treatment can be: 10g / L, 15g / L, 20g / L, 25g / L, 30g / L, 35g / L, 40g / L, 45g / L, 50g / L, etc. When the crystal size and crystal concentration do not meet the requirements of the preset crystallization treatment, the rate of reverse osmosis concentrate reaction crystallization can be increased by adjusting the water temperature, pressure, stirring speed, etc.

[0042] According to some embodiments of the present invention, in the nanofiltration treatment step, a hollow fiber nanofiltration device uses a hollow fiber membrane as a filtration medium, and drives the reverse osmosis concentrate through the hollow fiber nanofiltration membrane by a high-pressure pump to achieve the nanofiltration treatment of the reverse osmosis concentrate.

[0043] The hollow fiber membrane is in the shape of a fiber and has a selective permeability. The hollow fiber membrane is composed of many fine hollow fiber filaments, and these fiber filaments have tiny pores, and the size of these pores can precisely control the passage of substances at the molecular level.

[0044] The hollow fiber nanofiltration device has the characteristics of high flux and high rejection rate. Driven by a high-pressure pump, water molecules and small molecule solutes in the reverse osmosis concentrate can pass through the tiny pores of the fiber filaments, while macromolecular substances such as dissolved solids, inorganic salts, organic substances, and heavy metal pollutants are effectively intercepted, so as to achieve the effect of separating impurities from the reverse osmosis concentrate.

[0045] According to some embodiments of the present invention, in the nanofiltration treatment step, the operating pressure is controlled at 0.6MPa, and the flow rate range is 1.8 - 6.0m 3 / hr.

[0046] In the nanofiltration treatment step, by controlling an appropriate operating pressure, the good operation of the hollow fiber nanofiltration device can be controlled. An excessively high operating pressure may cause damage to the hollow fiber membrane, while an excessively low operating pressure will affect the filtration effect; by controlling an appropriate flow rate range, the water flow rate of the hollow fiber nanofiltration device can be controlled. An excessively fast water flow rate may cause damage to the hollow fiber membrane, while an excessively slow water flow rate will affect the filtration effect.

[0047] According to some embodiments of the present invention, in the nanofiltration treatment step, it is judged whether the nanofiltration treatment requirements are met according to the water production and rejection rate of the hollow fiber nanofiltration device. Among them, the nanofiltration treatment requirements include: the water production is between 20 - 25m 3 / h, and the rejection rate of divalent salts is between 90 - 95%.

[0048] For example, the water production required for nanofiltration treatment can be 20 m 3 / h, 21 m 3 / h, 22 m 3 / h, 23 m 3 / h, 24 m 3 / h, 25 m 3 / h, etc.; the rejection rate of divalent salts required for nanofiltration treatment can be 90%, 91%, 92%, 93%, 94%, 95%, etc. If the water production and rejection rate required for nanofiltration treatment meet the requirements, the reverse osmosis concentrated water after nanofiltration treatment can be discharged; if the water production and rejection rate required for nanofiltration treatment do not meet the requirements, the reverse osmosis concentrated water can be repeatedly subjected to nanofiltration treatment.

[0049] According to some embodiments of the present invention, the water produced after nanofiltration treatment is recycled, including: recycling the water produced after nanofiltration treatment as cooling water, process water or other non-drinking water uses in a thermal power plant.

[0050] By recycling the water produced after nanofiltration treatment, the utilization efficiency of water resources can be improved, the cost of the cooling system in the thermal power plant can be reduced, and the purpose of secondary utilization of reverse osmosis concentrated water can be achieved.

[0051] According to the reverse osmosis concentrated water treatment system for a thermal power plant in the second aspect embodiment of the present invention, the reverse osmosis concentrated water treatment system for a thermal power plant is used to implement the reverse osmosis concentrated water treatment method for a thermal power plant in the first aspect embodiment of the present invention above. The reverse osmosis concentrated water treatment system for a thermal power plant includes: a pretreatment unit, an induced crystallization unit, a hollow fiber nanofiltration device, and a nanofiltration produced water recycling unit.

[0052] Among them, the pretreatment unit can adjust the pH value of the reverse osmosis concentrated water and filter out suspended solids. By adjusting the pH value of the reverse osmosis concentrated water, the reverse osmosis concentrated water can meet the reaction conditions for subsequent step treatment; by filtering out suspended solids, the particulate impurities in the suspended solids are filtered out from the reverse osmosis concentrated water, preventing subsequent suspended solids from blocking the induced crystallization unit and the hollow fiber nanofiltration device, and also preventing the suspended solids in the solution from affecting the precipitation of dissolved solids in the crystallization carrier induced crystallization treatment, which is beneficial to improving the efficiency of subsequent step treatment.

[0053] Among them, the induced crystallization unit can induce the dissolved solids in the reverse osmosis concentrated water to precipitate in a crystalline form. Under suitable crystallization conditions, the dissolved solids can precipitate in crystals.

[0054] Among them, the hollow fiber nanofiltration device plays a role in nanofiltration treatment. After the reverse osmosis concentrated water is treated by the hollow fiber nanofiltration device, water molecules and small molecule solutes will not be blocked by the hollow fiber nanofiltration device, and most of the dissolved solids, inorganic salts, organic substances, heavy metals and other pollutants are retained outside the device.

[0055] Among them, the nanofiltration produced water recycling unit sends the produced water after nanofiltration treatment by the hollow fiber nanofiltration device into the nanofiltration produced water recycling unit for recycling.

[0056] For the reverse osmosis concentrate treatment system of a thermal power plant according to an embodiment of the present invention, pretreatment is carried out through a pretreatment unit to adjust the pH value of the reverse osmosis concentrate and filter out suspended solids, so that large particle impurities in the suspended solids are filtered out from the reverse osmosis concentrate, preventing the suspended solids from affecting the subsequent induced crystallization process and nanofiltration treatment process. It can prevent or reduce the influence of suspended solids in the solution on the precipitation efficiency of dissolved solids in the crystallization carrier induced crystallization treatment during the induced crystallization process, and can also reduce or prevent the blockage of the hollow fiber nanofiltration device used in the nanofiltration treatment by suspended solids, thus affecting its filtration effect, which is conducive to improving the efficiency and treatment quality of subsequent steps; by adopting the above-mentioned reverse osmosis concentrate treatment method of a thermal power plant, the reverse osmosis concentrate is subjected to treatments such as crystallization carrier induced crystallization treatment and filtration by a hollow fiber nanofiltration device, so that pollutants such as dissolved solids, inorganic salts, organic substances, and heavy metals are separated from the reverse osmosis concentrate, thereby realizing the reduction treatment and recycling of the reverse osmosis concentrate.

[0057] According to some embodiments of the present invention, the pretreatment unit includes a first chemical dosing device and a multimedia filter. The first chemical dosing device is used to add alkali into the reverse osmosis concentrate to adjust the pH value. The first chemical dosing device includes a first chemical storage tank and a first metering pump. The first metering pump is connected to the first chemical storage tank and is used to put the alkali in the first chemical storage tank into the reverse osmosis concentrate. The first chemical storage tank is made of corrosion-resistant material, and the corrosion-resistant material is polyvinyl chloride or fiberglass.

[0058] Among them, the first metering pump in the first chemical dosing device plays the role of transporting alkali, and the first chemical storage tank plays the role of storing alkali. When the pH value in the reverse osmosis concentrate does not meet the preset value, the first chemical dosing device transports the alkali in the first chemical storage tank into the reverse osmosis concentrate through the first metering pump.

[0059] Among them, the filtering medium in the multimedia filter can be filtering materials such as quartz sand, anthracite, and fiber balls, which can play the role of filtering out large particle suspended solids in the reverse osmosis concentrate.

[0060] By using corrosion-resistant polyvinyl chloride or fiberglass as the material of the first chemical storage tank, it can prevent the corrosion of the first chemical storage tank by corrosive materials such as alkali.

[0061] According to some embodiments of the present invention, the induced crystallization unit includes a crystallization reactor, a temperature sensor, and a pH sensor. The temperature sensor and the pH sensor are both installed in the crystallization reactor. A crystallization carrier is placed in the crystallization reactor. The temperature sensor is used to detect the temperature in the crystallization reactor, and the pH sensor is used to detect the pH value of the reverse osmosis concentrate water in the crystallization reactor.

[0062] The temperature sensor is used to detect the temperature in the crystallization reactor, so that the reverse osmosis concentrate water in the induced crystallization unit crystallizes under suitable temperature conditions.

[0063] The pH sensor is used to detect the pH value of the reverse osmosis concentrate water in the crystallization reactor, so that the reverse osmosis concentrate water in the induced crystallization unit crystallizes under suitable pH conditions.

[0064] A crystallization carrier is placed in the crystallization reactor. The crystallization carrier can play a role in initiating the growth of active component crystals or crystal grains. In the induced crystallization unit, the reverse osmosis concentrate water is in full contact with the crystallization carrier. Under suitable crystallization conditions, dissolved solids can crystallize out.

[0065] According to some embodiments of the present invention, the reverse osmosis concentrate water treatment system for thermal power plants further includes an online turbidimeter or a particle analyzer, which is used to online monitor the crystallization situation in the crystallization reactor.

[0066] The online turbidimeter can calculate the turbidity of the reverse osmosis concentrate water through the change of light intensity, so as to measure the content of suspended particulate matter in the reverse osmosis concentrate water to judge the crystallization situation.

[0067] The particle analyzer can determine the size and distribution of crystallization particles based on the movement, optical or electrical properties of the crystallization particles in the reverse osmosis concentrate water to judge the crystallization situation.

[0068] According to some embodiments of the present invention, the reverse osmosis concentrate water treatment system for thermal power plants further includes a second chemical dosing device, which is used to put alkali into the crystallization reactor.

[0069] The second chemical dosing device is used to put alkali into the crystallization reactor to keep the pH value in the crystallization reactor stable within a suitable range for the crystallization of dissolved solids in the reverse osmosis concentrate water.

[0070] The reverse osmosis concentrate water treatment method and treatment system of the present invention will be further described below in conjunction with embodiments.

[0071] Example 1,

[0072] The reverse osmosis concentrate water treatment system and the corresponding treatment method of Example 1 are described as follows.

[0073] (1) Crystalline carrier-induced crystallization unit: This unit mainly includes a crystallization reactor, a crystalline carrier, and a control system. The crystallization reactor is reasonably designed and is internally equipped with a stirring device to promote the uniform progress of the crystallization reaction. The crystalline carrier is made of a special material, specifically a zeolite-based seed crystal, which consists of a solid mixture containing components such as calcium, silicon, and aluminum, a strong base, and a binder. It has a porous structure and high surface energy, with a large number of hydroxyl functional groups on the surface. The surface of the seed crystal has a microstructure that promotes crystal growth and can efficiently induce the crystallization and precipitation of dissolved solids (such as salts) in the concentrated water. The control system is responsible for monitoring and adjusting key parameters such as temperature (20 - 40 °C), pressure (0.4 - 0.6 MPa), and pH value (8 - 12) during the crystallization process to ensure that the crystallization reaction proceeds under optimal conditions.

[0074] (2) Hollow fiber nanofiltration unit: This unit mainly consists of a hollow fiber nanofiltration membrane module, a high-pressure pump, a reflux valve, and a control system. The hollow fiber nanofiltration membrane module features high flux and high rejection rate, and can effectively retain pollutants such as dissolved solids, inorganic salts, organic substances, and heavy metals in the concentrated water. The high-pressure pump provides the necessary driving force to make the concentrated water pass through the hollow fiber nanofiltration membrane. The reflux valve is used to adjust the water inlet volume and membrane surface pressure of the nanofiltration membrane to ensure the stability and efficiency of the nanofiltration process. The control system is responsible for monitoring parameters such as pressure and flow rate during the nanofiltration process. The operating pressure is controlled at about 0.6 MPa, and the flow rate range can vary from 1.8 - 6.0 m 3 / hr / unit depending on the model and design of the membrane module. And adjust the operating conditions as needed.

[0075] (3) Nanofiltration product water recycling unit: This unit mainly includes a storage tank, a pumping system, and a control system. The storage tank is used to store the product water after nanofiltration treatment, and the pumping system is responsible for transporting the product water to the cooling system, process water system of the thermal power plant, or for other non-drinking water uses. The control system is responsible for monitoring the water level in the storage tank and the operating status of the pumping system to ensure the timely recovery and effective utilization of the product water.

[0076] The reverse osmosis concentrated water treatment method is as follows.

[0077] (1) Introduce the concentrated water generated in the reverse osmosis process of the thermal power plant into the pretreatment system for necessary pretreatment operations such as adjusting the pH value and filtering to remove suspended solids. Adjust the pH value to between 10 and 12 by adding alkali. The dosing device selects a metering pump, and the chemical storage tank uses corrosion-resistant materials such as polyvinyl chloride (PVC) or fiberglass. The filtration treatment uses a multi-media filter to filter, and removes suspended solids, sediment, and particulate impurities in the water by physical interception. The filtration accuracy can reach 5 - 10 μm, and the effluent turbidity can be reduced to below 1 NTU. The filtration media includes quartz sand, anthracite, fiber balls, etc., and the filter material can be selected from stainless steel, fiberglass, or carbon steel lined with rubber. Through the above steps, ensure the smooth progress of the subsequent treatment reaction process.

[0078] (2) Feed the pretreated concentrated water into the crystallization carrier-induced crystallization unit. In the crystallization reactor, the concentrated water is in full contact with the crystallization carrier. Under suitable crystallization conditions (water temperature 20 - 40 °C, pH 10 - 12, low-speed stirring (<200 rpm)), the dissolved solids start to crystallize and precipitate. The control system maintains the temperature at 20 - 40 °C, monitored by a temperature sensor, and automatically adjusts the heating or cooling device when out of range. The pH value is maintained at 10 - 12, monitored by a pH sensor, and the alkali dosing pump is automatically started to adjust. The stirring speed is controlled at <200 rpm, monitored by a rotational speed sensor and automatically adjusts the stirring motor. At the same time, use an online turbidimeter or particle analyzer to monitor the crystal growth situation in real-time. Through the above methods, the control system monitors and adjusts the crystallization conditions to ensure the stability and efficiency of the crystallization reaction.

[0079] (3) Feed the concentrated water after crystallization carrier-induced crystallization treatment into the hollow fiber nanofiltration unit. Under the action of a high-pressure pump, the concentrated water passes through the hollow fiber nanofiltration membrane. Water molecules and small molecule solutes pass through the membrane pores into the permeate side, while most of the dissolved solids, inorganic salts, organic substances, and heavy metal pollutants are retained outside the membrane. Monitor the key parameters in the nanofiltration process through the control system and adjust the operating conditions as needed to ensure the stability and efficiency of the nanofiltration process.

[0080] (4) Feed the permeate after hollow fiber nanofiltration treatment into the nanofiltration permeate recycling unit. The permeate is stored in a storage tank and transported to the cooling system, process water system of the thermal power plant or used for other non-drinking water purposes through a pumping system. The control system is responsible for monitoring the water level in the storage tank and the operating status of the pumping system to ensure the timely recovery and effective utilization of the permeate.

[0081] In the description of this specification, the description with reference to terms such as "one embodiment", "some embodiments", "schematic embodiments", "examples", "specific examples", or "some examples", etc. means that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0082] Although the embodiments of the present invention have been shown and described, those of ordinary skill in the art can understand that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention, and the scope of the present invention is defined by the claims and their equivalents.

Claims

1. A reverse osmosis concentrated water treatment method for thermal power plants, characterized in that, Comprising: Introducing the reverse osmosis concentrated water generated in the reverse osmosis process of the thermal power plant into a pretreatment unit for pretreatment, where the pretreatment includes adjusting the pH value and filtering to remove suspended solids; Introducing the pretreated reverse osmosis concentrated water into an induced crystallization unit, and fully contacting it with the crystallization carrier in the induced crystallization unit for crystallization carrier-induced crystallization treatment; Sending the reverse osmosis concentrated water after the crystallization carrier-induced crystallization treatment into a hollow fiber nanofiltration device for nanofiltration treatment; Sending the water produced after the nanofiltration treatment by the hollow fiber nanofiltration device into a nanofiltration produced water recycling unit for recycling.

2. The method for treating reverse osmosis concentrated water in a thermal power plant according to claim 1, characterized in that In the pretreatment step, the adjusting of the pH value includes: adjusting the pH value to between 10 and 12; In the pretreatment step, the filtration accuracy of the filtration treatment is 5 to 10 μm, and the filtration media used for the filtration treatment include quartz sand, anthracite, and fiber balls.

3. The reverse osmosis concentrated water treatment method for thermal power plants according to claim 1, characterized in that, The process parameters of the crystallization carrier-induced crystallization treatment include: water temperature 20 to 40 °C, pH 10 to 12, pressure 0.4 to 0.6 MPa, and stirring speed less than 200 rpm; And / or, the crystallization carrier is a silicate-based seed crystal, and the silicate-based seed crystal includes a solid mixture containing calcium, silicon, and aluminum, a strong base, and a binder. The silicate-based seed crystal has a porous structure and contains hydroxyl functional groups on its surface, and the surface of the silicate-based seed crystal has a microstructure that promotes crystal growth.

4. The reverse osmosis concentrated water treatment method for thermal power plants according to claim 1, characterized in that, In the crystallization carrier-induced crystallization treatment step, by monitoring the crystallization situation in the induced crystallization unit to judge whether the preset crystallization treatment requirements are met; Among them, the preset crystallization treatment requirements include: the crystal size distribution satisfies that D50 is between 100 and 500 μm, the crystal morphology is regular, and the crystal concentration is between 10 and 50 g / L.

5. The reverse osmosis concentrated water treatment method for thermal power plants according to claim 1, characterized in that, In the nanofiltration treatment step, the hollow fiber nanofiltration device uses a hollow fiber membrane as a filtration medium, and drives the reverse osmosis concentrated water through the hollow fiber nanofiltration membrane by a high-pressure pump to achieve the nanofiltration treatment of the reverse osmosis concentrated water; In the nanofiltration treatment step, the operating pressure is controlled at 0.6 MPa, and the flow rate ranges from 1.8 to 6.0 m 3 / hr.

6. The reverse osmosis concentrated water treatment method for thermal power plants according to claim 1, characterized in that, In the nanofiltration treatment step, according to the water production and rejection rate of the hollow fiber nanofiltration device, judge whether the nanofiltration treatment requirements are met; Among them, the nanofiltration treatment requirements include: the water production is between 20 and 25 m 3 / h, and the rejection rate of divalent salts is between 90% and 95%.

7. The reverse osmosis concentrated water treatment method for thermal power plants according to claim 1, characterized in that, Recycling the water produced after the nanofiltration treatment includes: recycling the water produced after the nanofiltration treatment as cooling water, process water, or other non-drinking water uses in the thermal power plant.

8. A reverse osmosis concentrated water treatment system for a thermal power plant, characterized in that, The reverse osmosis concentrated water treatment system for a thermal power plant is used to implement the method for treating reverse osmosis concentrated water in a thermal power plant according to any one of claims 1-7. The reverse osmosis concentrated water treatment system for a thermal power plant includes: the pretreatment unit, the induced crystallization unit, the hollow fiber nanofiltration device, and the nanofiltration produced water recycling unit.

9. The reverse osmosis concentrated water treatment system for thermal power plants according to claim 8, characterized in that, The pretreatment unit includes a first chemical dosing device and a multi-media filter. The first chemical dosing device is used to add alkali into the reverse osmosis concentrate to adjust the pH value. The first chemical dosing device includes a first chemical storage tank and a first metering pump. The first metering pump is connected to the first chemical storage tank and is used to put the alkali in the first chemical storage tank into the reverse osmosis concentrate. The first chemical storage tank is made of corrosion-resistant material, and the corrosion-resistant material is polyvinyl chloride or fiberglass.

10. The reverse osmosis concentrated water treatment system for thermal power plants according to claim 8, characterized in that, The induced crystallization unit includes a crystallization reactor, a temperature sensor, and a pH sensor. The temperature sensor and the pH sensor are both installed in the crystallization reactor. A crystallization carrier is placed in the crystallization reactor. The temperature sensor is used to detect the temperature in the crystallization reactor, and the pH sensor is used to detect the pH value of the reverse osmosis concentrate in the crystallization reactor. The reverse osmosis concentrate treatment system for thermal power plants further includes an online turbidimeter or a particle analyzer, which is used to online monitor the crystallization situation in the crystallization reactor. The reverse osmosis concentrate treatment system for thermal power plants further includes a second chemical dosing device, which is used to put alkali into the crystallization reactor.

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