Water treatment device and method for supercritical carbon dioxide power generation system

Abstract

The invention provides a water treatment device and method for a supercritical carbon dioxide power generation system, belongs to the technical field of sintering power generation water treatment, and is used for solving the efficiency problem of a water treatment device in the supercritical carbon dioxide power generation system. The water treatment device for the supercritical carbon dioxide power generation system comprises a raw water pretreatment system, a soft water and demineralized water preparation system, a circulating water system and a wastewater recovery system. The cooling efficiency of the cooler and the cooling tower can be improved, the generating capacity is increased, water is saved, and zero discharge of wastewater of a whole plant is achieved.

Description

Technical Field

[0001] The invention belongs to the technical field of sintering power generation water treatment, and in particular relates to a water treatment device and method for a supercritical carbon dioxide power generation system. Background Art

[0002] The supercritical carbon dioxide power generation system is a Brayton cycle system with supercritical carbon dioxide as the working fluid. Its cycle process is as follows: first, the supercritical carbon dioxide is pressurized by the compressor; then, the working fluid is heated at isobaric pressure by the heat exchanger; then, the working fluid enters the turbine to drive the turbine to do work, and the turbine drives the motor to generate electricity; finally, the working fluid enters the cooler, returns to its initial state, and then enters the compressor to form a closed cycle. The supercritical carbon dioxide power generation system uses supercritical carbon dioxide as the working fluid, converts the heat of the heat source into mechanical energy, and its heat source can come from nuclear reactors, solar energy, geothermal energy, fossil fuel combustion, industrial waste heat, etc. In the steel industry, the waste heat of the sintering ring cooler is generally used as the heat source of the supercritical carbon dioxide power generation system, and is equipped with a water treatment device that matches the supercritical carbon dioxide power generation system. The main function of the water treatment device is to cool the carbon dioxide after work and maintain the compressor inlet temperature. The cooling temperature of carbon dioxide can directly affect the power generation of the supercritical carbon dioxide power generation system. The lower the temperature of carbon dioxide, the higher the power generation efficiency. Therefore, the design of the water treatment device is crucial. Summary of the invention

[0003] Therefore, the technical problem to be solved by the present invention is to provide a water treatment device and method for a supercritical carbon dioxide power generation system, which can improve the cooling efficiency, thereby facilitating the improvement of power generation efficiency. At the same time, water is saved, zero wastewater discharge is achieved, and the service life of the water treatment device is extended.

[0004] In order to solve the above problems, the present invention provides a water treatment device for a supercritical carbon dioxide power generation system, comprising: a raw water pretreatment system, a soft water desalted water preparation system, a circulating water system and a wastewater recovery system. The raw water pretreatment system comprises an integrated water purification device and an ultrafiltration device. The input end of the integrated water purification device is connected to the raw water source. The output end of the integrated water purification device is connected to the input end of the ultrafiltration device. The soft water desalted water preparation system comprises a soft water preparation module and a desalted water preparation module. The input end of the soft water preparation module is connected to the output end of the ultrafiltration device. The output end of the soft water preparation module is connected to the input end of the desalted water preparation module. The circulating water system comprises a cooler and a closed cooling tower. The input end of the cooler is connected to the output end of the desalted water preparation module. The closed cooling tower comprises an internal circulation and an external circulation. The output end of the cooler is connected to the water inlet end of the internal circulation. The water outlet end of the internal circulation is connected to the input end of the cooler. The output end of the soft water preparation module is also connected to the water inlet end of the external circulation. The wastewater from the raw water pretreatment system, the soft water desalination system and the circulating water system are respectively connected to the input end of the wastewater recovery system. The output end of the wastewater recovery system is connected to the sintering system to provide the sintering system with water for mixing and humidification.

[0005] Optionally, the ultrafiltration device further comprises a backwash water inlet and a backwash water outlet. The backwash water inlet is connected to the output end of the integrated water purification device. The backwash water outlet is connected to the input end of the wastewater recovery system.

[0006] Optionally, the water treatment device for the supercritical carbon dioxide power generation system further includes: a chemical cleaning system, which is respectively connected to the ultrafiltration device and the desalted water preparation module.

[0007] Optionally, the raw water pretreatment system further includes: a raw water pool, a reagent dosing device, a new water pool and a security filter. The water inlet of the raw water pool is connected to the raw water source. The water outlet of the raw water pool is connected to the input of the integrated water purification device through a variable frequency lift pump. The output of the reagent dosing device is connected to the dosing port of the integrated water purification device. The water inlet of the new water pool is connected to the output of the integrated water purification device. The water outlet of the new water pool is connected to the input of the security filter through a first lift pump. The output of the security filter is connected to the input of the ultrafiltration device.

[0008] Optionally, the soft water preparation module includes: an ultrafiltration water production pool, a sodium ion exchanger, a regeneration device and a soft water pool. The water inlet of the ultrafiltration water production pool is connected to the output end of the ultrafiltration device. The water outlet of the ultrafiltration water production pool is connected to the input end of the sodium ion exchanger through a second lift pump. The regeneration device is connected to the regeneration interface of the sodium ion exchanger. The water inlet of the soft water pool is connected to the output end of the sodium ion exchanger. The water outlet of the soft water pool is respectively connected to the input end of the desalted water preparation module and the water inlet end of the external circulation through a soft water pump. The wastewater of the sodium ion exchanger is connected to the input end of the wastewater recovery system.

[0009] Optionally, the demineralized water preparation module includes: a high-pressure pump and a reverse osmosis device. The input end of the reverse osmosis device is connected to the output end of the soft water preparation module through the high-pressure pump. The output end of the reverse osmosis device is connected to the input end of the cooler. The concentrated water of the reverse osmosis device is connected to the input end of the ultrafiltration device.

[0010] Optionally, the circulating water system further comprises: a desalted water tank, a circulating water pump, a pre-filter and a dosing device. The water inlet of the desalted water tank is connected to the output of the desalted water preparation module. The water outlet of the desalted water tank is connected to the input of the pre-filter through the circulating pump. The output of the pre-filter is connected to the input of the cooler. The output of the dosing device is connected to the water inlet of the external circulation.

[0011] Optionally, the wastewater recovery system includes a reuse water pool and a third lift pump. The wastewater of the raw water pretreatment system, the soft water desalted water preparation system and the circulating water system are respectively connected to the input end of the reuse water pool. The output end of the reuse water pool is connected to the sintering system through the third lift pump.

[0012] Optionally, the water treatment device for the supercritical carbon dioxide power generation system further includes: a control system. The control system is respectively connected to the raw water pretreatment system, the soft water desalted water preparation system, the circulating water system and the waste water recovery system.

[0013] The present invention also provides a water treatment method for a supercritical carbon dioxide power generation system, comprising the following steps:

[0014] Pre-treating raw water to form ultra-filtered water and producing pre-treated wastewater;

[0015] Softening the ultrafiltration water to form soft water and produce softened sewage;

[0016] Desalination treatment is performed on part of the soft water to form desalted water and produce concentrated water;

[0017] The remaining soft water is used as external circulation water for the closed cooling tower;

[0018] Use desalted water as internal circulation water in closed cooling tower;

[0019] Use pre-treated sewage and softened sewage as mixed material humidification water for the sintering system;

[0020] The concentrated water is returned to the raw water pretreatment system to achieve cascade utilization.

[0021] Beneficial Effects

[0022] 1. The water treatment device for the supercritical carbon dioxide power generation system provided by the present invention includes a raw water pretreatment system, a soft water desalted water preparation system, a circulating water system and a wastewater recovery system. The raw water pretreatment system includes an integrated water purification device and an ultrafiltration device. Since the raw water source is generally industrial water, the main components are rainwater and recycled water, and the turbidity, hardness and conductivity are high, the raw water can be pretreated by the integrated water purification device and the ultrafiltration device to reduce the turbidity, hardness and conductivity of the raw water to meet the use requirements of the subsequent water treatment process and alleviate the problem of water shortage in the factory area. The soft water desalted water preparation system includes a soft water preparation module and a desalted water preparation module. The raw water treated by the raw water pretreatment system enters the soft water preparation module. After being treated by the soft water preparation module, soft water is formed. The soft water is divided into two paths. One path of soft water is used as the external circulation water of the closed cooling tower. The other path of soft water is treated by the desalted water preparation module to form desalted water. The desalted water is used as the internal circulation water of the closed cooling tower, which can effectively reduce the scaling in the circulating water system, which is beneficial to improve the heat exchange efficiency, and then it is beneficial to reduce the temperature of carbon dioxide and increase the power generation. At the same time, it can also extend the service life of the circulating water system, extend the maintenance cycle and reduce the maintenance cost. In addition, in the circulating water system, the output end of the cooler is connected to the water inlet end of the internal circulation, and the water outlet end of the internal circulation is connected to the input end of the cooler, that is, the internal circulation adopts a closed circulation, so the demand for desalted water is small, which is beneficial to energy saving. The raw water pretreatment system, the soft water desalted water preparation system and the sewage of the circulating water system are respectively connected to the input end of the wastewater recovery system. The output end of the wastewater recovery system is connected to the sintering system to provide water for mixing and humidifying the sintering system, achieving zero emissions throughout the site.

[0023] 2. The water treatment method for the supercritical carbon dioxide power generation system provided by the present invention can treat industrial water step by step, and then use it as cooling circulation water for the closed cooling tower, which is beneficial to reduce scaling, improve the cooling efficiency of the cooler and the closed cooling tower, increase power generation, and realize the cascade utilization, circulation and recovery of water, save water, and achieve zero discharge of wastewater in the entire plant. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 A schematic diagram of a water treatment device for a supercritical carbon dioxide power generation system according to an embodiment of the present invention;

[0025] Figure 2 A schematic structural diagram of a raw water pretreatment system according to an embodiment of the present invention;

[0026] Figure 3 A schematic diagram of the structure of a system for preparing soft water and demineralized water according to an embodiment of the present invention;

[0027] Figure 4A schematic diagram of the structure of a circulating water system according to an embodiment of the present invention;

[0028] Figure 5 A schematic diagram of the structure of a wastewater recovery system according to an embodiment of the present invention;

[0029] Figure 6 A flow chart of a water treatment method for a supercritical carbon dioxide power generation system according to an embodiment of the present invention.

[0030] The reference numerals are as follows:

[0031] 1. Raw water pretreatment system; 2. Soft water and desalted water preparation system; 3. Circulating water system; 4. Wastewater recovery system; 5. Chemical cleaning system; 6. Sintering system;

[0032] 11. Raw water pool; 12. Variable frequency lifting pump; 13. Integrated water purification device; 14. Chemical dosing device; 15. New water pool; 16. First lifting pump; 17. Security filter; 18. Ultrafiltration device;

[0033] 21. Ultrafiltration water pool; 22. Second booster pump; 23. Sodium ion exchanger; 24. Regeneration device; 25. Soft water pool; 26. Soft water pump; 27. High pressure pump; 28. Reverse osmosis device;

[0034] 31. Desalination tank; 32. Circulating water pump; 33. Pre-filter; 34. Cooler; 35. Closed cooling tower; 36. Dosing device;

[0035] 351, internal circulation water inlet; 352, internal circulation water outlet; 353, external circulation water inlet; 354, external circulation water tank; 355, spray pump; 356, external circulation sewage;

[0036] 41. Recycling water pool; 42. The third lifting pump. DETAILED DESCRIPTION

[0037] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0038] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0039] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be an indirect connection through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0040] The preferred embodiments of the present invention are described below in conjunction with the accompanying drawings. It should be understood that the preferred embodiments described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention.

[0041] In a first aspect, this embodiment provides a water treatment device for a supercritical carbon dioxide power generation system. Figure 1 A schematic diagram of a water treatment device for a supercritical carbon dioxide power generation system provided in this embodiment.

[0042] like Figure 1 As shown, the water treatment device for the supercritical carbon dioxide power generation system of this embodiment includes: a raw water pretreatment system 1, a soft water desalted water preparation system 2, a circulating water system 3 and a wastewater recovery system 4. The raw water pretreatment system 1 includes an integrated water purification device 13 and an ultrafiltration device 18. The input end of the integrated water purification device 13 is connected to the raw water source. The output end of the integrated water purification device 13 is connected to the input end of the ultrafiltration device 18. The soft water desalted water preparation system 2 includes a soft water preparation module and a desalted water preparation module. The input end of the soft water preparation module is connected to the output end of the ultrafiltration device 18. The output end of the soft water preparation module is connected to the input end of the desalted water preparation module. The circulating water system 3 includes a cooler 34 and a closed cooling tower 35. The input end of the cooler 34 is connected to the output end of the desalted water preparation module. The closed cooling tower 35 includes an internal circulation and an external circulation. The output end of the cooler 34 is connected to the internal circulation water inlet end 351. The internal circulation water outlet end 352 is connected to the input end of the cooler 34. The output end of the soft water preparation module is also connected to the external circulation water inlet 353. The sewage from the raw water pretreatment system 1, the soft water desalted water preparation system 2 and the circulating water system 3 are respectively connected to the input end of the wastewater recovery system 4. The output end of the wastewater recovery system 4 is connected to the sintering system 6 to provide the sintering system 6 with water for mixing and humidification.

[0043] In this embodiment, the integrated water purification device 13 integrates the functions of flocculation, sedimentation, filtration, backwashing, and sewage discharge, and can operate automatically, which not only ensures the efficient transition of the water purification system, but also can automatically backwash. There is no need to set up electrical equipment such as backwashing water pumps or air compressors. There is no need to manually operate the integrated water purification device 13. Only regular inspections are required, which saves a lot of infrastructure investment and daily operation, repair, and maintenance costs. The quality of raw water treated by the integrated water purification device 13 can meet the use requirements of subsequent treatment processes. The sewage generated in the integrated water purification device 13 has poor water quality and can be directly discharged into the wastewater recovery system 4.

[0044] In this embodiment, the ultrafiltration device 18 adopts advanced membrane separation technology. The water body treated by the integrated water purification device 13 contains various small solutes. After entering the ultrafiltration device 18, the water passes through the filter membrane from the high-pressure side of the ultrafiltration device 18 to the low-pressure side, and the solutes can be filtered out to obtain a permeate or ultrafiltrate; wherein, the micropore size specification of the ultrafiltration membrane in the ultrafiltration device 18 can be set according to actual use requirements, and this embodiment does not impose too many restrictions on this. The wastewater generated on the high-pressure side of the ultrafiltration device 18 has poor water quality and can be directly discharged into the wastewater recovery system 4.

[0045] In this embodiment, the output end of the soft water preparation module is divided into two paths, one of which is connected to the desalted water preparation module, and the other is connected to the external circulation water inlet end 353 of the closed cooling tower 35, as the supplementary water of the spraying system of the closed cooling tower 35. The soft water prepared by the soft water preparation module is used as the spraying water of the closed cooling tower 35, which can effectively reduce the scaling of the closed cooling tower 35, is conducive to improving the heat exchange efficiency of the closed cooling tower 35, and is conducive to reducing the temperature of the carbon dioxide working medium to improve the power generation efficiency. At the same time, it is also conducive to extending the service life of the closed cooling tower 35, extending the maintenance cycle, and reducing maintenance costs. The wastewater of the soft water preparation module is recycled to the wastewater recovery system 4.

[0046] In this embodiment, the output end of the desalted water preparation module is connected to the internal circulation water inlet end 351 of the closed cooling tower 35 through the cooler 34, as the supplementary water for the internal circulation. The desalted water prepared by the desalted water preparation module is used as the internal circulation water, and the water quality is good, and it is not easy to structure, and has good fluidity and heat exchange efficiency. It is beneficial to reduce the temperature of the carbon dioxide working fluid, and it is beneficial to extend the service life of the closed cooling tower 35 and the cooler 34. The wastewater produced by the desalted water preparation module has good water quality, and its water quality is better than the raw water source, and it can be returned to the front process for reuse. However, in other embodiments, the wastewater produced by the desalted water preparation module can also be discharged into the wastewater recovery system 4.

[0047] In this implementation, due to the high dust level at the project site, in order to improve cooling efficiency and extend the service life of the cooler 34, the internal circulation of the closed cooling tower 35 adopts a closed circulation. Since the desalted water circulates between the cooler 34 and the closed cooling tower 35 and is repeatedly used, the required amount of desalted water replenishment is small, generally only reaching 0.1% of the circulating water volume, with low energy consumption, energy saving and environmental protection.

[0048] The water treatment device for the supercritical carbon dioxide power generation system of this embodiment includes a raw water pretreatment system 1, a soft water desalted water preparation system 2, a circulating water system 3 and a wastewater recovery system 4. The raw water pretreatment system 1 includes an integrated water purification device 13 and an ultrafiltration device 18. Since the raw water source is generally industrial water, the main components are rainwater and recycled water, and the turbidity, hardness and conductivity are relatively high, the raw water can be pretreated by the integrated water purification device 13 and the ultrafiltration device 18 to reduce the turbidity, hardness and conductivity of the raw water to meet the use requirements of the subsequent water treatment process and alleviate the problem of water shortage in the factory area. The soft water desalted water preparation system includes a soft water preparation module and a desalted water preparation module. The raw water treated by the raw water pretreatment system enters the soft water preparation module. After being treated by the soft water preparation module, soft water is formed. The soft water is divided into two paths. One path of soft water is used as the external circulation water of the closed cooling tower 35. The other path of soft water is treated by the desalted water preparation module to form desalted water. The desalted water is used as the internal circulation water of the closed cooling tower 35, which can effectively reduce the scaling in the circulating water system 3, which is beneficial to improve the heat exchange efficiency, thereby helping to reduce the temperature of carbon dioxide and increase the power generation. At the same time, it can also extend the service life of each device in the circulating water system 3, extend the maintenance cycle, and reduce the maintenance cost. In addition, in the circulating water system 3, the output end of the cooler 34 is connected to the internal circulation water inlet end 351, and the internal circulation water outlet end 352 is connected to the input end of the cooler 34, that is, the internal circulation adopts a closed circulation, so the demand for desalted water is small, which is beneficial to energy saving. The sewage of the raw water pretreatment system 1, the soft water desalted water preparation system 2 and the circulating water system 3 are respectively connected to the input end of the wastewater recovery system 4. The output end of the wastewater recovery system 4 is connected to the sintering system 6 to provide the sintering system 6 with water for mixing and humidifying, thereby achieving zero emission in the whole site.

[0049] In some embodiments, see Figure 1 The ultrafiltration device 18 also includes a backwash water inlet and a backwash drain. The backwash water inlet is connected to the output end of the integrated water purification device 13. The backwash drain is connected to the input end of the wastewater recovery system 4.

[0050] During the operation of the ultrafiltration device 18 of this embodiment, as solid matter accumulates on the high-pressure side of the filter membrane, the pressure difference will gradually increase and affect the filtering function of the filter membrane. Therefore, the ultrafiltration device 18 of this embodiment also includes a backwash inlet and a backwash outlet to achieve backwashing of the ultrafiltration device 18 and ensure the normal operation of the ultrafiltration device 18. The backwash water of the ultrafiltration device 18 of this embodiment uses raw water purified by the integrated water purification device 13, which is locally sourced and does not require additional backwash water, which is beneficial to reducing costs and achieving water conservation. The backwash water of the ultrafiltration device 18 has poor water quality and does not need to be returned to the previous process for reuse. Therefore, it is directly recycled to the wastewater recovery system 4.

[0051] Figure 2 This is a schematic structural diagram of a raw water pretreatment system 1 provided in this embodiment. Figure 3 Schematic diagram of a soft water desalination water preparation system 2 provided in this embodiment. In some embodiments, Figure 2 and Figure 3 As shown, the water treatment device for the supercritical carbon dioxide power generation system also includes: a chemical cleaning system 5, which is connected to the ultrafiltration device 18 and the demineralized water preparation module respectively.

[0052] During the operation of the ultrafiltration device 18 and the reverse osmosis device 28 of the demineralized water preparation module, the substances accumulated on the membrane surface will be deposited and become sticky. It is impossible to completely clean them only by backwashing water. Over time, the accumulation of these stubborn attachments will affect the normal operation of the ultrafiltration device 18 and the reverse osmosis device 28. Therefore, the present embodiment is provided with a chemical cleaning system 5 to perform regular chemical cleaning on the ultrafiltration device 18 and the reverse osmosis device 28. The chemical cleaning system 5 includes a cleaning tank, a cleaning pump, a cleaning filter, and matching instruments, pipes, valves, etc.

[0053] It should be noted that, in this embodiment, the type and point of dosing of the water supply of the chemical cleaning system 5 are determined according to the characteristics of the membrane components selected by the ultra-ultrafiltration device 18 and the reverse osmosis device 28 and the water quality, and this embodiment does not impose too many restrictions on this.

[0054] In some embodiments, Figure 2 As shown, the raw water pretreatment system 1 also includes: a raw water tank 11, a reagent dosing device 14, a new water tank 15 and a security filter 17. The water inlet of the raw water tank 11 is connected to the raw water source. The water outlet of the raw water tank 11 is connected to the input end of the integrated water purification device 13 through a variable frequency boost pump 12. The output end of the reagent dosing device 14 is connected to the dosing port of the integrated water purification device 13. The water inlet of the new water tank 15 is connected to the output end of the integrated water purification device 13. The water outlet of the new water tank 15 is connected to the input end of the security filter 17 through a first boost pump 16. The output end of the security filter 17 is connected to the input end of the ultrafiltration device 18.

[0055] In this embodiment, the outer shell of the security filter 17 is generally made of stainless steel, and the inner part uses PP melt-blown, wire-sintered, folded, titanium filter element, activated carbon filter element and other tubular filter elements as filter elements. Different filter elements are selected according to different filter media and design processes to meet the requirements of effluent water quality.

[0056] In this embodiment, the raw water source is generally industrial water, which is collected in the raw water pool 11; the industrial water in the raw water pool 11 enters the integrated water purification device 13 under the drive of the variable frequency lifting pump 12, and after a series of treatment processes such as flocculation, sedimentation, and filtration, the obtained new water is discharged into the new water pool 15, and the generated sewage is discharged into the wastewater recovery system 4; the new water in the new water pool 15 is driven by the first lifting pump 16, filtered by the security filter 17 to further remove impurities, and then enters the ultrafiltration device 18 for further filtration, and the obtained ultrafiltration water enters the soft water preparation module, and the sewage is discharged into the wastewater recovery system 4. The security filter 17 is arranged in front of the ultrafiltration device 18, which can protect the ultrafiltration membrane of the ultrafiltration device 18. The output end of the reagent dosing device 14 is connected to the dosing port of the integrated water purification device 13, which is used to add drugs to the integrated water purification device 13 to achieve the purification of the raw water. The raw water pretreatment system 1 of this embodiment can purify industrial water step by step, reducing the burden of each water treatment process, and not only improving water quality but also improving water treatment efficiency.

[0057] In some embodiments, Figure 3 As shown, the soft water preparation module includes: an ultrafiltration water production pool 21, a sodium ion exchanger 23, a regeneration device 24 and a soft water pool 25. The water inlet end of the ultrafiltration water production pool 21 is connected to the output end of the ultrafiltration device 18. The water outlet end of the ultrafiltration water production pool 21 is connected to the input end of the sodium ion exchanger 23 through a second lift pump 22. The regeneration device 24 is connected to the regeneration interface of the sodium ion exchanger 23. The water inlet end of the soft water pool 25 is connected to the output end of the sodium ion exchanger 23. The water outlet end of the soft water pool 25 is connected to the input end of the desalted water preparation module and the external circulation water inlet end 353 of the closed cooling tower 35 through a soft water pump 26. The wastewater of the sodium ion exchanger 23 is connected to the input end of the wastewater recovery system 4.

[0058] In this embodiment, the sodium ion exchanger 23 is used to remove calcium ions and magnesium ions in water to produce softened water. The calcium and magnesium ions that make up the hardness of the water are exchanged with the ion exchange resin in the softener, and the calcium and magnesium ions in the water are exchanged with sodium ions, making it difficult for carbonate scale and sulfate scale to form in the water, thereby obtaining softened water.

[0059] The working state of the sodium ion exchanger 23 is as follows: operation → regeneration (backwashing, salt absorption, displacement, forward washing) → operation. During regeneration, the regeneration device 24 mixes the regeneration agent and soft water to a predetermined concentration (5% to 8%) through an ejector and then feeds the mixture into the sodium ion exchanger 23. The preparation concentration of the regeneration agent can be adjusted by a valve on the regeneration device 24. In this embodiment, the commonly used regeneration agent is a sodium chloride solution. The sodium ions in the sodium chloride solution can exchange with the hardness ions such as calcium and magnesium adsorbed on the resin, thereby removing these hardness ions and restoring the ion exchange capacity of the resin. In addition, the sodium chloride solution can also clean the impurities and dirt on the surface and inside of the resin to keep the resin clean and active.

[0060] The water inlet end of the ultrafiltration water production pool 21 of this embodiment is connected to the output end of the ultrafiltration device 18, and is used to store water filtered by the ultrafiltration device 18; the water in the ultrafiltration water production pool 21 enters the sodium ion exchanger 23 under the drive of the second lifting pump 22, and after being softened in the sodium ion exchanger 23, the obtained soft water is discharged into the soft water pool 25; the soft water in the soft water pool 25 is driven by the soft water pump 26 and is divided into two paths, one of which flows to the desalted water preparation module, and the other flows to the external circulation water inlet end 353 of the closed cooling tower 35, as the external spray water of the closed cooling tower 35.

[0061] In some embodiments, Figure 3 As shown, the demineralized water preparation module includes: a high-pressure pump 27 and a reverse osmosis device 28. The input end of the reverse osmosis device 28 is connected to the output end of the soft water preparation module through the high-pressure pump 27. The output end of the reverse osmosis device 28 is connected to the input end of the cooler 34. The concentrated water of the reverse osmosis device 28 is connected to the input end of the ultrafiltration device 18.

[0062] In this embodiment, the working principle of the reverse osmosis device 28 is a membrane separation technology that uses pressure as a driving force by means of the function of a selectively permeable (semi-permeable) membrane. When the pressure applied in the device is greater than the osmotic pressure of the influent solution, water molecules continuously pass through the membrane and flow into the central tube through the water production channel, while impurities in the water, such as ions, organic matter, bacteria, viruses, etc., are retained on the inlet side of the membrane to form concentrated water, which then flows out at the concentrated water outlet, thereby achieving the purpose of separation and purification.

[0063] The concentrated water from the reverse osmosis device 28 has a better quality than the raw water, and can be returned to the new water pool 15 of the raw water pretreatment system 1, mixed with the water in the new water pool 15, and then filtered in the ultrafiltration device 18 to achieve cascade utilization. In other embodiments, the concentrated water can also be directly discharged to the wastewater recovery system 4.

[0064] The demineralized water preparation module of this embodiment includes a high-pressure pump 27 and a reverse osmosis device 28. Driven by the soft water pump 26, the soft water in the soft water tank 25 is divided into two paths. One path flows through the high-pressure pump 27 for secondary pressurization and enters the reverse osmosis device 28. After being filtered by the reverse osmosis device 28, it becomes demineralized water; after being cooled by the cooler 34, the demineralized water enters the internal circulation of the closed cooling tower 35 for heat exchange, which can reduce scaling in the internal circulation and help improve the heat exchange efficiency.

[0065] Figure 4 Schematic diagram of a circulating water system 3 provided in this embodiment. In some embodiments, Figure 4 As shown, the circulating water system 3 also includes: a desalted water tank 31, a circulating water pump 32, a pre-filter 33 and a dosing device 36. The water inlet of the desalted water tank 31 is connected to the output end of the reverse osmosis device 28 of the desalted water preparation module. The water outlet of the desalted water tank 31 is connected to the input end of the pre-filter 33 through the circulating pump 32. The output end of the pre-filter 33 is connected to the input end of the cooler 34. The output end of the dosing device 36 is connected to the external circulation water tank 354 through the external circulation water inlet 353.

[0066] The desalted water tank 31 of this embodiment is connected to the output end of the reverse osmosis device 28 in the desalted water preparation module, and is used to store the desalted water obtained after being processed by the reverse osmosis device 28; the desalted water in the desalted water tank 31 is pressurized and lifted by the circulation pump 32, enters the pre-filter 33, and after being filtered by the pre-filter 33, enters the cooler 34 for cooling; the cooled desalted water enters the closed cooling tower 35, and is used as the internal circulation water of the closed cooling tower 35; after heat exchange in the internal circulation of the closed cooling tower 35, it returns to the desalted water tank 31 and is mixed with the desalted water in the desalted water tank 31 for recycling. Figure 4 As shown, the external circulation water inlet end 353 of the closed cooling tower 35 of this embodiment is connected to the external circulation water tank 354. The soft water in the external circulation water tank 354 enters the spraying system of the closed cooling tower 35 under the drive of the spray pump 355, and is sprayed on the circulation pipe inside the closed cooling tower 35 to achieve the effect of cooling, and has a certain cleaning effect. The external circulation wastewater 356 generated after spraying is collected through the pipeline and discharged to the wastewater recovery system 4. The dosing device 36 is connected to the external circulation water inlet end 353 of the closed cooling tower 35, and is used to regularly add bactericidal algaecide and slow-release antiscalant to the external circulation water tank 354 to reduce the probability of scaling of the cooling coil of the closed cooling tower 35, thereby improving the heat exchange efficiency of the closed cooling tower 35.

[0067] The closed cooling tower 35 of this embodiment is a countercurrent closed cooling tower, and the main part is composed of a shell, a heat exchanger, a fan, a spray system, an air inlet grille, an external circulation water tank 354 and other parts. By increasing the coil area of ​​the internal circulation heat exchanger, the cooling efficiency can be improved to ensure that the temperature difference between the inlet temperature and the outlet temperature of the cooled medium is not less than 10°C. A connecting pipe is provided at the bottom of the closed cooling tower 35, and the external circulation water tanks 354 at the bottom of multiple closed cooling towers 35 can be combined into one, which is convenient for the control of the spray pump 355.

[0068] In the circulating water system 3 of this embodiment, the desalted water is circulated in a closed loop, and the desalted water that is heat exchanged through the cooler 34 and the closed cooling tower 35 only has its temperature increased and is not contaminated by other factors. Therefore, only when the system is discharged or leaking does it need to be supplemented with a small amount of desalted water, and the energy consumption is relatively low.

[0069] Figure 5 A schematic diagram of the structure of a wastewater recovery system 4 provided in this embodiment. In some embodiments, Figure 5 As shown, the wastewater recovery system 4 includes a reuse water tank 41 and a third lift pump 42. The wastewater from the raw water pretreatment system 1, the soft water desalted water preparation system 2 and the circulating water system 3 are respectively connected to the input end of the reuse water tank 41. The output end of the reuse water tank 41 is connected to the sintering system 6 through the third lift pump 42.

[0070] The wastewater recovery system 4 of this embodiment is used to recover the sewage from the raw water pretreatment system 1, the soft water desalted water preparation system 2 and the circulating water system 3, including the backwash drainage of the ultrafiltration device 18, the sewage from the sodium ion exchanger 23, the sewage from the external circulation of the closed cooling tower 35, etc. These sewages are collected through pipelines and discharged to the reuse water pool 41, and are lifted by the third lifting pump 42 to the sintering system 6 as water for mixing humidification, thereby achieving zero emission.

[0071] In some embodiments, see Figures 1 to 5 The water treatment device for the supercritical carbon dioxide power generation system also includes: a control system. The control system is connected to the raw water pretreatment system 1, the soft water desalted water preparation system 2, the circulating water system 3 and the waste water recovery system 4 respectively.

[0072] The control system is connected to the integrated water purification device 13. A regulating valve is provided at the input end of the integrated water purification device 13. The control system is connected to the regulating valve and the variable frequency boost pump. When the water consumption of the system fluctuates, the control system can adjust the water volume by controlling the opening of the regulating valve or the variable frequency operation of the variable frequency boost pump.

[0073] The control system is connected to the ultrafiltration device 18, obtains the internal pressure of the ultrafiltration device 18, and controls the automatic operation and stop of the ultrafiltration backwash water pump according to the internal pressure; in addition, the water production flow valve of the ultrafiltration device 18, the switch of the ultrafiltration pneumatic valve, and the alarm of the ultrafiltration device are all connected to the control system, realizing the full automatic control of water production, backwashing, isobaric washing and other processes, greatly reducing the work intensity in the daily maintenance of the equipment and the cleaning of the ultrafiltration membrane, and extending the service life of the ultrafiltration membrane. The control system includes an industrial computer system and a microcomputer control system.

[0074] The control system is connected to the sodium ion exchanger 23. A hardness meter and a flow meter are provided at the output end of the sodium ion exchanger 23. The control system controls the regeneration and operation of the sodium ion exchanger 23 according to the hardness of the produced water of the sodium ion exchanger 23, and adjusts the produced water flow according to the flow meter. The adjustment is simple and the operation is stable.

[0075] The control system is connected to the reverse osmosis device 28. Sampling points are set at the desalted water output end and the concentrated water discharge end of the reverse osmosis device 28. Defects can be effectively diagnosed and determined according to the number and position of the sampling points. When the reverse osmosis device 28 is shut down, measures are set to eliminate the static pressure on the fresh water side. The reverse osmosis device 28 is also provided with an automatic flushing interface, and automatic flushing discharge ports are set on the concentrated water and fresh water sides. Cleaning interfaces are set on the water inlet side, concentrated water side and water outlet side of the reverse osmosis device 28, and an explosion-proof membrane is installed on the output end pipeline of the reverse osmosis device 28. Pressure switches, conductivity meters, flow meters, etc. are set at the input and output ends of the reverse osmosis device 28, all of which are connected to the control system to ensure safe, stable and reliable operation of the device.

[0076] The control system is connected to the closed cooling tower 35. The external circulation water tank 354 at the bottom of the closed cooling tower 35 is provided with a remote level gauge and a high and low level alarm. The external circulation water inlet 353 is provided with an electric valve, which is interlocked with the start and stop of the soft water pump 26 for easy interlock control. The closed cooling tower 35 is provided with a remote thermometer for measuring the outlet water temperature of the closed cooling tower 35. The control system automatically controls the start and stop of the fan and the spray pump 355 in the closed cooling tower 35 according to the outlet water temperature, saving electric energy.

[0077] The control system is connected to the circulating water pump 32. The output end of the circulating water pump 32 is provided with a remote pressure and flow detection device. The circulating water system 3 adopts a closed cycle. The amount of desalted water replenished is small, only 0.1% of the circulating water volume, and the energy consumption is low.

[0078] The control system is connected to the chemical cleaning device 5, and the PLC controls the adding, starting and stopping of the chemical cleaning.

[0079] This embodiment realizes intelligent control through the control system, which is beneficial to improving cooling efficiency and reducing costs.

[0080] In a second aspect, this embodiment also provides a water treatment method for a supercritical carbon dioxide power generation system. Figure 6 A flow chart of a water treatment method for a supercritical carbon dioxide power generation system provided in this embodiment.

[0081] like Figure 6 As shown, the water treatment method for the supercritical carbon dioxide power generation system of this embodiment includes the following steps:

[0082] S1. Pre-treat the raw water to form ultra-filtered water and produce pre-treated wastewater;

[0083] Specifically, raw water is generally industrial water, the main components of which are rainwater and recycled water, and the water quality is as follows: SS ≤ 30 mg / L, hardness ≤ 450 mg / L, conductivity ≤ 1500 μs / cm. Figure 1 Figure 2 As shown, the raw water pretreatment system 1 is used to pretreat the raw water, including: first, the raw water is treated by the integrated water purification device 13 to obtain new water, and the new water is then treated by the ultrafiltration device 18 to finally obtain ultrafiltered water. The quality of the ultrafiltered water can reach: SS ≤ 10 mg / L, hardness ≤ 400 mg / L, conductivity ≤ 1400 mg / L. The generated pretreated wastewater includes the wastewater of the integrated water purification device 13, the filtered wastewater of the ultrafiltration device 18, and the backwash water of the ultrafiltration device 18.

[0084] S2. Softening the ultrafiltration water to form soft water and produce softened sewage;

[0085] Specifically, Figure 3 As shown, the ultrafiltration water is softened by using a sodium ion exchanger 23 , and the softened sewage is the wastewater of the sodium ion exchanger 23 .

[0086] S3. Desalting part of the soft water to form desalted water and produce concentrated water;

[0087] Specifically, Figure 3 As shown, the soft water is desalinated by using a reverse osmosis device 28. The concentrated water produced is the wastewater on the concentrated water side of the reverse osmosis device 28.

[0088] S4. The remaining soft water is used as the external circulation water of the closed cooling tower 35;

[0089] Specifically, Figure 4 As shown, the soft water treated by the sodium ion exchanger 23 is driven by the soft water pump 26 and is divided into two paths. One path enters the external circulation water tank 354 through the external circulation water inlet end 353 of the closed cooling tower 35, and is then lifted to the spray system by the spray pump 355 to spray and cool the heat exchange tube coil in the closed cooling tower 35.

[0090] S5. The deionized water is used as the internal circulation water of the closed cooling tower 35;

[0091] Specifically, Figure 4 As shown, the soft water treated by the sodium ion exchanger 23 is divided into two paths under the drive of the soft water pump 26, one of which is used as the external circulation water of the closed cooling tower 35, and the other is pressurized by the high-pressure pump 27 for the second time and enters the osmosis device 28 for desalination, and then under the drive of the circulating water pump 32, passes through the pre-filter 33, enters the cooler 34 for heat exchange, and then enters the closed cooling tower 35 for internal circulation heat exchange through the internal circulation water inlet end 351, and then enters the desalted water pool 31 through the internal circulation water outlet end 352, and after mixing with the desalted water therein, under the drive of the circulating water pump 32, passes through the pre-filter 33, enters the cooler 34 for heat exchange, and then enters the closed cooling tower 35 for internal circulation heat exchange through the internal circulation water inlet end 351, so as to realize closed circulation and repeated utilization.

[0092] S6. The pretreated sewage and softened sewage are used as the mixed humidification water of the sintering system 6;

[0093] Specifically, Figure 5 As shown, the pre-treated sewage includes the sewage from the integrated water purification device 13, the filtered sewage from the ultrafiltration device 18, and the backwash water from the ultrafiltration device 18; the softened sewage includes the sewage from the sodium ion exchanger 23. In addition, the external circulation sewage 356 of the closed cooling tower 35 will also be collected into the reuse water pool 41 together with the pre-treated sewage and the softened sewage. The sewage in the reuse water pool 41 can enter the sintering system 6 under the drive of the third lifting pump 42 as mixed material humidification water.

[0094] S7. Return the concentrated water to the raw water pretreatment system 1 to achieve cascade utilization.

[0095] Specifically, since the concentrated water from the reverse osmosis device 28 has a better quality than the raw water, it can be introduced back into the new water pool of the raw water pretreatment system 1 for cascade utilization.

[0096] The water treatment method for the supercritical carbon dioxide power generation system of this embodiment can treat industrial water step by step, and then use it as cooling circulation water for the closed cooling tower 35, which is beneficial to reduce scaling, improve the cooling efficiency of the cooler 34 and the closed cooling tower 35, increase power generation, and realize the cascade utilization, circulation and recovery of water, save water, and achieve zero discharge of wastewater in the entire plant.

[0097] It is easy for those skilled in the art to understand that, under the premise of no conflict, the above-mentioned advantageous methods can be freely combined and superimposed.

[0098] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention shall be included in the protection scope of the present invention. The above are only preferred embodiments of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and variations can be made without departing from the technical principles of the present invention, and these improvements and variations should also be regarded as the protection scope of the present invention.

Claims

1. A water treatment device for a supercritical carbon dioxide power generation system, characterized in that: include: Raw water pretreatment system, soft water and demineralized water preparation system, circulating water system and wastewater recovery system; The raw water pretreatment system includes an integrated water purification device and an ultrafiltration device; The input end of the integrated water purification device is connected to the raw water source; the output end of the integrated water purification device is connected to the input end of the ultrafiltration device; The soft water desalted water preparation system comprises a soft water preparation module and a desalted water preparation module; the input end of the soft water preparation module is connected to the output end of the ultrafiltration device; the output end of the soft water preparation module is connected to the input end of the desalted water preparation module; The circulating water system includes a cooler and a closed cooling tower; the input end of the cooler is connected to the output end of the demineralized water preparation module; the closed cooling tower includes an internal circulation and an external circulation; the output end of the cooler is connected to the water inlet end of the internal circulation; the water outlet end of the internal circulation is connected to the input end of the cooler; the output end of the soft water preparation module is also connected to the water inlet end of the external circulation; The raw water pretreatment system, the soft water desalted water preparation system and the wastewater of the circulating water system are respectively connected to the input end of the wastewater recovery system; the output end of the wastewater recovery system is connected to the sintering system to provide water for mixing and humidifying the sintering system.

2. The water treatment device for a supercritical carbon dioxide power generation system according to claim 1, characterized in that: The ultrafiltration device also includes a backwash water inlet and a backwash drain; the backwash water inlet is connected to the output end of the integrated water purification device; the backwash drain is connected to the input end of the wastewater recovery system.

3. The water treatment device for a supercritical carbon dioxide power generation system according to claim 1, characterized in that: Also includes: The chemical cleaning system is connected to the ultrafiltration device and the demineralized water preparation module respectively.

4. The water treatment device for a supercritical carbon dioxide power generation system according to claim 1, characterized in that: The raw water pretreatment system also includes: a raw water pool, a reagent dosing device, a new water pool and a security filter; The water inlet of the raw water pool is connected to the raw water source; the water outlet of the raw water pool is connected to the input end of the integrated water purification device through a variable frequency boost pump; The output end of the drug dosing device is connected to the drug dosing port of the integrated water purification device; The water inlet of the new water pool is connected to the output of the integrated water purification device; the water outlet of the new water pool is connected to the input of the safety filter through a first lifting pump; and the output of the safety filter is connected to the input of the ultrafiltration device.

5. The water treatment device for a supercritical carbon dioxide power generation system according to claim 1, characterized in that: The soft water preparation module includes: an ultrafiltration water production pool, a sodium ion exchanger, a regeneration device and a soft water pool; The water inlet of the ultrafiltration water production pool is connected to the output end of the ultrafiltration device; the water outlet of the ultrafiltration water production pool is connected to the input end of the sodium ion exchanger through a second boost pump; The regeneration device is connected to the regeneration interface of the sodium ion exchanger; The water inlet of the soft water tank is connected to the output end of the sodium ion exchanger; the water outlet of the soft water tank is connected to the input end of the demineralized water preparation module and the water inlet of the external circulation through a soft water pump; The wastewater from the sodium ion exchanger is connected to the input end of the wastewater recovery system.

6. The water treatment device for a supercritical carbon dioxide power generation system according to claim 1, characterized in that: The desalted water preparation module comprises: a high-pressure pump and a reverse osmosis device; The input end of the reverse osmosis device is connected to the output end of the soft water preparation module through the high-pressure pump; the output end of the reverse osmosis device is connected to the input end of the cooler; The concentrated water of the reverse osmosis device is connected to the input end of the ultrafiltration device.

7. The water treatment device for a supercritical carbon dioxide power generation system according to claim 1, characterized in that: The circulating water system also includes: a desalted water tank, a circulating water pump, a pre-filter and a dosing device; The water inlet end of the desalted water tank is connected to the output end of the desalted water preparation module; The water outlet of the desalted water tank is connected to the input end of the pre-filter through the circulation pump; The output end of the pre-filter is connected to the input end of the cooler; The output end of the dosing device is connected to the water inlet end of the external circulation.

8. The water treatment device for a supercritical carbon dioxide power generation system according to claim 1, characterized in that: The wastewater recovery system includes a reuse water pool and a third lift pump; The raw water pretreatment system, the soft water desalted water preparation system and the wastewater of the circulating water system are respectively connected to the input end of the reuse water tank; the output end of the reuse water tank is connected to the sintering system through the third lifting pump.

9. The water treatment device for a supercritical carbon dioxide power generation system according to claim 1, characterized in that: Also includes: A control system is connected to the raw water pretreatment system, the soft water desalted water preparation system, the circulating water system and the waste water recovery system respectively.

10. A water treatment method for a supercritical carbon dioxide power generation system, characterized in that: The method comprises the following steps: Pre-treating raw water to form ultra-filtered water and producing pre-treated wastewater; Softening the ultrafiltration water to form soft water and produce softened sewage; Desalting part of the soft water to form desalted water and produce concentrated water; The remaining soft water is used as external circulation water for the closed cooling tower; Using the desalted water as internal circulation water of a closed cooling tower; Using the pretreated sewage and the softened sewage as mixed material humidification water for the sintering system; The concentrated water is returned to the raw water pretreatment system to achieve cascade utilization.

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