A device for treating high-hardness high-salt wastewater and a method of using the same

Abstract

The present application relates to wastewater treatment technical field, disclose a kind of high hardness high salt wastewater treatment device, including crystal seed fluidization tank, reagent storage tank and crystallization granulation fluidized bed, crystallization granulation fluidized bed is connected together with crystal seed fluidization tank and reagent storage tank pipeline respectively, the treatment device further includes multi-effect evaporation system, the liquid inlet of the multi-effect evaporation system is connected together with the liquid outlet end pipeline of crystallization granulation fluidized bed, the liquid return of the multi-effect evaporation system is connected together with the liquid inlet end pipeline of crystallization granulation fluidized bed, condenser is connected with pipeline on the gas outlet of the multi-effect evaporation system, condenser is connected with pipeline on vacuum pump;The liquid return of the multi-effect evaporation system is also connected with high hardness high salt wastewater outside on the liquid return, high hardness high salt wastewater can be mixed with from the liquid return of multi-effect evaporation system and then enter the liquid inlet end of crystallization granulation fluidized bed;The present application has the advantages of reducing floor area, reducing operating cost.

Description

Technical Field

[0001] The present invention relates to a device for treating high-hardness and high-salt wastewater and a method for using the same, belonging to the technical field of wastewater treatment. Background Art

[0002] At present, the existing methods for treating high-hardness and high-salt wastewater include the following: the first method: direct evaporation and concentration into salt; the second method: no pretreatment, direct use of multi-effect evaporation; the third method: pretreatment with chemical softening and then separation of water and salt by multi-effect evaporation.

[0003] However, the above treatment methods have the following problems: the first method uses direct evaporation and concentration to form salt, which has the problems of low heat source utilization efficiency, high heat consumption, high operating cost, easy scaling of components such as nozzles, and complex salt composition of produced water that cannot be utilized as resources; the second method does not do pretreatment and directly uses multi-effect evaporation to treat the water. Although it can save heating steam consumption and reduce operating costs by using the secondary steam of the first effect as the heating agent of the second effect, when treating high-hardness wastewater, it does not remove the hardness of the wastewater first, and the heater coil is prone to scaling, affecting the heat exchange efficiency and the amount of water treated. The third method uses chemical softening for pretreatment and then multi-effect evaporation. If the pretreatment uses traditional chemical softening, there will be problems such as high chemical consumption and low utilization rate. At the same time, the produced water needs to be acidified to adjust the pH, which will bring in a large amount of chloride ions or sulfate ions, resulting in a large amount of sludge that needs to be treated. If the pretreatment uses the crystallization granulation fluidized bed method, when the treated water volume is less than 50m³ / h and the tower diameter is less than 800mm, the tower wall is prone to scaling. When the hardness is higher than 1500mg / L, the calcium carbonate crystals generated by the chemical addition reaction are easy to self-nucleate and cannot adhere to the surface of the seed crystal to grow, resulting in high turbidity of the effluent water, and it takes a lot of cost to treat the wastewater.

[0004] The invention patent with Chinese patent authorization announcement number CN105152435B provides a zero-discharge treatment method for wastewater containing high-concentration active salts. It uses evaporation and crystallization technology to treat concentrated water discharged from the RO system, thereby achieving zero-discharge treatment of wastewater containing high-concentration salts. However, it does not integrate crystallization granulation and multi-effect evaporation, and corresponding improvements can be made. Summary of the Invention

[0005] In order to solve the above problems existing in the prior art, the present invention provides a treatment device for high-hardness and high-salt wastewater and a method for using the same.

[0006] The technical solutions of the present invention are as follows:

[0007] In the first aspect, the present invention provides a treatment device for high-hardness and high-salt wastewater, comprising a seed fluidized bed, a reagent storage tank and a crystallization granulation fluidized bed, the crystallization granulation fluidized bed being connected to the seed fluidized tank and the reagent storage tank with pipelines respectively, the treatment device also comprising a multi-effect evaporation system, the liquid inlet of the multi-effect evaporation system being connected to the liquid outlet pipeline of the crystallization granulation fluidized bed, the liquid return of the multi-effect evaporation system being connected to the liquid inlet pipeline of the crystallization granulation fluidized bed, the gas outlet pipeline of the multi-effect evaporation system being connected to a condenser, and the condenser pipeline being connected to a vacuum pump; the liquid return of the multi-effect evaporation system is also externally connected to high-hardness and high-salt wastewater, and the high-hardness and high-salt wastewater can be mixed with the return liquid flowing out from the liquid return of the multi-effect evaporation system and then enter the liquid inlet of the crystallization granulation fluidized bed.

[0008] Furthermore, the multi-effect evaporation system includes a first-effect heater, a first-effect separator, a second-effect heater and a second-effect separator, and the multi-effect evaporation system is used for performing rising film evaporation or falling film evaporation.

[0009] Furthermore, the liquid outlet of the crystallization granulation fluidized bed is respectively connected to the bottom port of the first-effect heater and the bottom port of the second-effect heater through pipes, the top port of the first-effect heater is connected to the feed end pipe of the first-effect separator, the side air inlet pipe of the first-effect heater is connected with the heat source steam, the liquid outlet of the first-effect separator is connected to the liquid inlet pipe of the crystallization granulation fluidized bed, the air outlet of the first-effect separator is connected to the side air inlet pipe of the second-effect heater, and the first-effect separator is arranged above the crystallization granulation fluidized bed; the top port of the second-effect heater is connected to the feed end pipe of the second-effect separator, the side air outlet of the second-effect heater is connected to the condenser through a pipe, the liquid outlet of the second-effect separator is respectively connected to the bottom port of the second-effect heater and the external dehydration and drying system pipe, and the air outlet of the second-effect separator is connected to the condenser through a pipe.

[0010] Furthermore, a first-effect forced circulation pump is provided on the pipeline connecting the liquid outlet of the first-effect separator and the liquid inlet of the crystallization granulation fluidized bed, and the pipeline connecting the high-hardness and high-salt wastewater and the liquid inlet of the crystallization granulation fluidized bed passes through the first-effect forced circulation pump.

[0011] Furthermore, a second-effect forced circulation pump is provided on the pipeline connecting the liquid outlet of the crystallization granulation fluidized bed and the bottom port of the second-effect heater, and the pipeline connecting the liquid outlet of the second-effect separator and the bottom port of the second-effect heater passes through the second-effect forced circulation pump.

[0012] Furthermore, the liquid outlet of the crystallization and granulation fluidized bed is connected to the top port pipeline of the first-effect heater, the bottom port of the first-effect heater is connected to the liquid inlet end pipeline of the crystallization and granulation fluidized bed, the side port of the first-effect heater is connected to the feed end pipeline of the first-effect separator, the side air inlet pipeline of the first-effect heater is connected with heat source steam, the liquid outlet of the first-effect separator is respectively connected to the liquid inlet end of the crystallization and granulation fluidized bed and the top port pipeline of the second-effect heater, the air outlet end of the first-effect separator is connected to the side air inlet pipeline of the second-effect heater, the bottom port of the second-effect heater is connected to the top port pipeline of the second-effect heater, the side port of the second-effect heater is connected to the feed end pipeline of the second-effect separator, the liquid outlet of the second-effect separator is respectively connected to the top port of the second-effect heater and the external dehydration and drying system pipeline, and the air outlet end of the second-effect separator is connected to the condenser by pipeline.

[0013] Furthermore, a first-effect forced circulation pump is provided on the pipeline connecting the bottom port of the first-effect heater and the liquid inlet end of the crystallization granulation fluidized bed, and the pipeline connecting the liquid outlet end of the first-effect separator and the liquid inlet end of the crystallization granulation fluidized bed and the pipeline connecting the high-hardness and high-salt wastewater and the liquid inlet end of the crystallization granulation fluidized bed both pass through the first-effect forced circulation pump.

[0014] Furthermore, a second-effect forced circulation pump is provided on the pipeline connecting the liquid outlet end of the first-effect separator and the top port of the second-effect heater, and the pipeline connecting the bottom port of the second-effect heater and the top port of the second-effect heater and the pipeline connecting the liquid outlet end of the second-effect separator and the top port of the second-effect heater both pass through the second-effect forced circulation pump.

[0015] Furthermore, a seed dosing pump is provided on the pipeline connecting the feed end of the crystallization granulation fluidized bed and the seed fluidized tank, and a drug dosing pump is provided on the pipeline connecting the drug feed end of the crystallization granulation fluidized bed and the drug storage tank.

[0016] In a second aspect, the present invention provides a method for using the aforementioned high-hardness and high-salt wastewater treatment device, comprising the following steps:

[0017] Step 1: adding seed crystals into the seed fluidization tank, then feeding fluidizing water into the bottom of the seed fluidization tank to fluidize the seed crystals in the seed fluidization tank, starting the seed crystal feeding pump, and the seed crystal feeding pump feeds the fluidized seed crystals in the seed fluidization tank into the crystallization granulation fluidized bed for crystallization granulation;

[0018] Step 2: Start the first-effect forced circulation pump to allow the wastewater generated by the crystallization granulation to enter the multi-effect evaporation system for circulation, start the reagent dosing pump, and the reagent dosing pump adds the alkaline reagent in the reagent storage tank into the crystallization granulation fluidized bed to react with the mixed high-hardness and high-salt wastewater to remove hardness ions;

[0019] Step 3: introducing heat source steam into the multiple-effect evaporation system to heat and evaporate the incoming wastewater, mixing the return liquid flowing out of the return liquid of the multiple-effect evaporation system with the high-hardness and high-salt wastewater, and the mixed high-hardness and high-salt wastewater enters the liquid inlet end of the crystallization granulation fluidized bed;

[0020] Step 4: Start the second-effect forced circulation pump and the vacuum pump to start circulation inside the multi-effect evaporation system and discharge gas, condensed water and high brine.

[0021] The present invention has the following beneficial effects:

[0022] The present invention integrates crystallization and granulation with multi-effect evaporation, so that the treatment device can simultaneously perform crystallization and granulation to remove hardness during the multi-effect evaporation concentration process. During the production process, the wastewater separated by the single-effect separator can be mixed with high-hardness and high-salt wastewater, which can have the following effects:

[0023] 1. It can reduce the hardness of wastewater entering the crystallization granulation fluidized bed, reduce the occurrence of self-nucleation of calcium carbonate crystals, make calcium carbonate grow on the crystal seeds, ensure low turbidity of hard water, and do not need to set up sedimentation and sludge dewatering systems.

[0024] 2. The inlet water temperature can be increased, thereby reducing the solubility of calcium carbonate, reducing the concentration of reagents required for the reaction, saving reagents and reducing operating costs.

[0025] 3. High-salt and high-hardness incoming water usually has a small amount of water. After being mixed with the reflux water, it enters the crystallization granulation fluidized bed, which can increase the water flow entering the crystallization granulation fluidized bed and avoid the situation where the tower diameter is too small and the tower wall is prone to scaling when the flow rate is small.

[0026] 4. It makes full use of the advantages of multi-effect evaporation, which is highly efficient and energy-saving, and reduces the operating cost of the evaporation and concentration process.

[0027] 5. Using crystallization granulation to remove hardness also extends the operating cycle of the multi-effect evaporation system and reduces the cost of descaling the heat exchanger coil.

[0028] At the same time, the gas discharged from the top of the second-effect separator can be condensed through the condenser and reused as high-quality water, and the liquid at the bottom of the second-effect separator can produce product salt after passing through the subsequent dehydration and drying system to achieve zero emissions. Compared with the existing technology, it has the advantages of reducing floor space and lowering operating costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 This is a schematic structural diagram of the present invention in a rising film evaporation mode;

[0030] Figure 2This is a schematic structural diagram of the present invention in the falling film evaporation mode.

[0031] The reference numerals in the figures are as follows:

[0032] 1. Seed fluidizing tank; 2. Reagent storage tank; 3. Crystallization and granulation fluidized bed; 4. Condenser; 5. Vacuum pump; 6. First-effect heater; 7. First-effect separator; 8. Second-effect heater; 9. Second-effect separator; 10. First-effect forced circulation pump; 11. Second-effect forced circulation pump; 12. Seed dosing pump; 13. Reagent dosing pump. DETAILED DESCRIPTION

[0033] The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0034] Example 1: Please refer to Figure 1 This example provides a treatment device for high-hardness and high-salt wastewater, including a seed fluidized bed 1, a reagent storage tank 2 and a crystallization granulation fluidized bed 3. The seed fluidized bed 1 is filled with the required seed crystals, and the reagent storage tank 2 is filled with the required alkaline reagent. The feed end of the crystallization granulation fluidized bed 3 is connected to the seed fluidized bed 1 through a pipeline, and a seed dosing pump 12 is provided on the pipeline connecting the feed end of the crystallization granulation fluidized bed 3 and the discharge end of the seed fluidized tank 1. The seed dosing pump 12 can pump the seed crystals in the seed fluidized tank 1 into the crystallization granulation fluidized bed 3. The drug feed end of the crystallization granulation fluidized bed 3 is connected to the reagent storage tank 2 through a pipeline, and a drug dosing pump 13 is provided on the pipeline connecting the drug feed end of the crystallization granulation fluidized bed 3 and the discharge end of the reagent storage tank 2. The drug dosing pump 13 can pump the reagent in the reagent storage tank 2 into the crystallization granulation fluidized bed 3.

[0035] The treatment device also includes a multi-effect evaporation system, the liquid inlet of the multi-effect evaporation system is connected to the liquid outlet pipe of the crystallization granulation fluidized bed 3, the liquid return of the multi-effect evaporation system is connected to the liquid inlet pipe of the crystallization granulation fluidized bed 3, the gas outlet pipe of the multi-effect evaporation system is connected to a condenser 4, and the pipe on the condenser 4 is connected to a vacuum pump 5; the liquid return of the multi-effect evaporation system is also externally connected to high-hardness and high-salt wastewater, and the high-hardness and high-salt wastewater can be mixed with the return liquid flowing out from the liquid return of the multi-effect evaporation system and then enter the liquid inlet of the crystallization granulation fluidized bed 3.

[0036] In this embodiment, the multi-effect evaporation system is a rising film evaporation system, comprising a first-effect heater 6, a first-effect separator 7, a second-effect heater 8, and a second-effect separator 9. The liquid outlet of the crystallization and granulation fluidized bed 3 is connected to the bottom port of the first-effect heater 6 and the bottom port of the second-effect heater 8 through pipes, respectively. This allows wastewater discharged from the liquid outlet of the crystallization and granulation fluidized bed 3 to enter the first-effect heater 6 and the second-effect heater 8 for heating and evaporation. Furthermore, the first-effect separator 7 can be positioned above the crystallization and granulation fluidized bed 3 to save floor space.

[0037] The top port of the single-effect heater 6 is connected to the feed end pipe of the single-effect separator 7. The wastewater heated by the single-effect heater 6 can enter the single-effect separator 7 for flash evaporation. The pipe on the side air inlet of the single-effect heater 6 is connected to the heat source steam, which provides the required heat source for the heating and evaporation work of the single-effect heater 6.

[0038] The liquid outlet of the first-effect separator 7 is connected to the liquid inlet of the crystallization granulation fluidized bed 3 through a pipeline. The high-temperature water remaining after the flash separation of the first-effect separator 7 can flow back into the crystallization granulation fluidized bed 3 through this pipeline. A first-effect forced circulation pump 10 is provided on the pipeline connecting the liquid outlet of the first-effect separator 7 and the liquid inlet of the crystallization granulation fluidized bed 3. The pipeline connecting the high-hardness and high-salt wastewater and the liquid inlet of the crystallization granulation fluidized bed 3 passes through the first-effect forced circulation pump 10, so that the high-hardness and high-salt wastewater can be mixed with the high-temperature return liquid, thereby increasing the inlet temperature of the high-hardness and high-salt wastewater entering the crystallization granulation fluidized bed 3, so as to reduce the solubility of calcium carbonate and the supersaturation required for crystallization, thereby reducing the subsequent dosage of reagents and reducing operating costs. At the same time, it can also reduce the occurrence of self-nucleation of calcium carbonate crystals, so that calcium carbonate grows on the seed crystals, ensuring low turbidity of hardness-removed water, and no sedimentation and sludge dewatering system is required. Furthermore, mixing high-hardness, high-salt wastewater with the return fluid increases the inlet and outlet flow rates of the crystallization and granulation fluidized bed 3, preventing scaling of the tower walls due to a small tower diameter at low flow rates. The softened water, after de-hardening by crystallization and granulation, enters the primary heater 6, reducing scaling within the primary heater 6.

[0039] The gas outlet end of the first-effect separator 7 is connected to the side air inlet pipe of the second-effect heater 8. The secondary steam generated after flash evaporation in the first-effect separator 7 can enter the second-effect heater 8 through this pipeline, providing the required heat source for the heating and evaporation work of the second-effect heater 8, thereby reducing operation and maintenance costs.

[0040] The top port of the second-effect heater 8 is connected to the feed end pipeline of the second-effect separator 9. The wastewater heated by the second-effect heater 8 can enter the second-effect separator 9 for flash evaporation. The side air outlet of the second-effect heater 8 is connected to the condenser 4 through a pipeline, so that the steam generated at the top of the second-effect heater 8 can enter the condenser 4 from the side air outlet for condensation, generating condensate for reuse. A second-effect forced circulation pump 11 is provided on the pipeline connecting the liquid outlet of the crystallization and granulation fluidized bed 3 and the bottom port of the second-effect heater 8. The second-effect forced circulation pump 11 can input part of the wastewater flowing out of the liquid outlet of the crystallization and granulation fluidized bed 3 into the second-effect heater 8 for heating and evaporation. The specific output and working mode can be determined according to actual conditions.

[0041] The liquid outlet of the second effect separator 9 is respectively connected to the bottom port of the second effect heater 8 and the external dehydration and drying system pipeline. The gas outlet of the second effect separator 9 is connected to the condenser 4 by a pipeline. A portion of the high-temperature brine remaining at the bottom of the second effect separator 9 after flash evaporation can be returned to the second effect heater 8 for circulation treatment and mixed with the wastewater entering the crystallization granulation fluidized bed 3 to increase the temperature of the wastewater entering the second effect heater 8 and improve heat utilization efficiency. The other portion can be input into the external dehydration and drying system for dehydration and drying to generate product salt for collection. The secondary steam accumulated at the top of the second effect separator 9 after flash evaporation can enter the condenser 4 from the gas outlet to be condensed, generating condensed water for reuse. At the same time, the pipeline connecting the liquid outlet of the second effect separator 9 and the bottom port of the second effect heater 8 passes through a second effect forced circulation pump 11 to achieve control of the circulation.

[0042] The method for using the processing device comprises the following steps:

[0043] The first step: adding crystal seeds into the crystal seed fluidization tank 1, then feeding fluidizing water into the bottom of the crystal seed fluidization tank 1 to fluidize the crystal seeds in the crystal seed fluidization tank 1, starting the crystal seed adding pump 12, and the crystal seed adding pump 12 adds a certain amount of crystal seeds in the crystal seed fluidization tank 1 into the crystallization granulation fluidized bed 3 for crystallization granulation. After the crystal seed adding is completed, the crystal seed adding pump 12 is turned off.

[0044] Step 2: Start the first-effect forced circulation pump 10 to allow the high-hardness, high-salt wastewater to fill the multi-effect evaporation system and circulate. When the high-hardness, high-salt wastewater enters the granulation fluidized bed 3, the seed crystals begin to fluidize. Start the reagent dosing pump 13, which injects the alkaline reagent from the reagent storage tank 2 into the crystallization granulation fluidized bed 3 to react with the mixed high-hardness, high-salt wastewater to remove hardness ions. At this time, the hardness removed in the crystallization granulation fluidized bed 3 adheres to the surface of the seed crystals and begins to form calcium carbonate particles.

[0045] Step 3: Heat source steam is introduced into the first-effect heater 6, and the first-effect heater 6 heats the product water after the hardness is removed by the crystallization granulation fluidized bed 3. The wastewater heated by the first-effect heater 6 enters the first-effect separator 7 for flash separation. After flash evaporation, a high-temperature return liquid will be generated at the bottom of the first-effect separator 7, which is mixed with the incoming high-hardness and high-salt wastewater on the corresponding pipeline and forced to mix and increase the pressure under the action of the first-effect forced circulation pump 10. This increases the inlet temperature of the subsequent crystallization granulation fluidized bed 3 and ensures the flow rate required for the fluidization of the crystal seeds in the crystallization granulation fluidized bed 3. The mixed high-hardness and high-salt wastewater enters the liquid inlet end of the crystallization granulation fluidized bed 3. The mixing ratio can be adjusted, that is, the amount of high-hardness and high-salt wastewater entering the crystallization granulation fluidized bed 3 can be adjusted according to the flow rate of the return liquid to control the hardness of the high-hardness and high-salt wastewater entering the crystallization granulation fluidized bed 3 so that its hardness is less than 1500 mg / L. This can reduce the self-nucleation of calcium carbonate crystals, thereby ensuring that the turbidity of the product water is low enough and there is no need to add a precipitation and dehydration system.

[0046] Step 4: Start the second-effect forced circulation pump 11 and the vacuum pump 5, and use the hot steam generated by the flash evaporation of the first-effect separator 7 to continue heating and evaporating the wastewater concentrated by the first-effect evaporation, so that the internal circulation of the multi-effect evaporation system begins and the gas, condensed water and high brine are discharged; Specifically: under the negative pressure of the vacuum pump 5, the hot steam generated by the flash evaporation of the first-effect separator 7 will enter the second-effect heater 8, providing the required heat source for the operation of the second-effect heater 8, thereby reducing the operating cost;

[0047] Under the action of the second-effect forced circulation pump 11, a portion of the wastewater generated by the crystallization and granulation fluidized bed 3 can also enter the second-effect heater 8 for heating. The specific amount of wastewater entering can be determined according to actual conditions and can be regulated by setting a valve structure such as a regulating valve on the corresponding pipeline. After entering the second-effect heater 8 and being heated, the wastewater then enters the second-effect separator 9 for flash concentration. The top of the second-effect separator 9 produces higher-temperature secondary steam, and high-temperature brine remains at the bottom. A portion of the high-temperature brine produced at the bottom of the second-effect separator 9 will flow back to the second-effect heater 8 for circulation treatment and can be mixed with the wastewater entering from the crystallization and granulation fluidized bed 3 to increase the temperature of the wastewater entering the second-effect heater 8 and improve heat utilization efficiency. The remaining portion can be input into an external dehydration and drying system for dehydration and drying to generate product salt for collection. The specific split flow rate selection and control should be determined according to actual conditions. The steam accumulated on the top of the second-effect separator 9 can enter the condenser 4 from the air outlet to be condensed, and the condensed water is generated for reuse. The steam generated by the second-effect heater 8 can also enter the condenser 4 from the side air outlet to be condensed, and the condensed water is generated for reuse.

[0048] The fifth step is to shut down the treatment device after it has been working for a certain period of time, and then clean the crystallization and granulation fluidized bed 3 to discharge the mature calcium carbonate particles outward, and then add new crystal seeds to enter a new treatment process.

[0049] Because rising film evaporation causes wastewater to flow from bottom to top, a very small amount of calcium carbonate particles not adsorbed on the seed crystals may adhere to the heat exchange surfaces of the first-effect heater 6 and the second-effect heater 8 due to their own gravity, potentially causing scaling in the first-effect heater 6 and the second-effect heater 8. To minimize this, a second embodiment is proposed.

[0050] Example 2: Please refer to Figure 2 The present embodiment provides a treatment device for high-hardness and high-salt wastewater, comprising a seed fluidized bed 1, a reagent storage tank 2 and a crystallization granulation fluidized bed 3. The seed fluidized bed 1 is filled with the required seed crystals, and the reagent storage tank 2 is filled with the required alkaline reagent. The feed end of the crystallization granulation fluidized bed 3 is connected to the seed fluidized bed 1 through a pipeline, and a seed dosing pump 12 is provided on the pipeline connecting the feed end of the crystallization granulation fluidized bed 3 and the discharge end of the seed fluidized tank 1. The seed dosing pump 12 can pump the seed crystals in the seed fluidized bed 1 into the crystallization granulation fluidized bed 3. The drug feed end of the crystallization granulation fluidized bed 3 is connected to the reagent storage tank 2 through a pipeline, and a drug dosing pump 13 is provided on the pipeline connecting the drug feed end of the crystallization granulation fluidized bed 3 and the discharge end of the reagent storage tank 2. The drug dosing pump 13 can pump the reagent in the reagent storage tank 2 into the crystallization granulation fluidized bed 3.

[0051] The treatment device also includes a multi-effect evaporation system, the liquid inlet of the multi-effect evaporation system is connected to the liquid outlet pipe of the crystallization granulation fluidized bed 3, the liquid return of the multi-effect evaporation system is connected to the liquid inlet pipe of the crystallization granulation fluidized bed 3, the gas outlet pipe of the multi-effect evaporation system is connected to a condenser 4, and the pipe on the condenser 4 is connected to a vacuum pump 5; the liquid return of the multi-effect evaporation system is also externally connected to high-hardness and high-salt wastewater, and the high-hardness and high-salt wastewater can be mixed with the return liquid flowing out from the liquid return of the multi-effect evaporation system and then enter the liquid inlet of the crystallization granulation fluidized bed 3.

[0052] In this embodiment, the multi-effect evaporation system is a falling film evaporation system, which includes a first-effect heater 6, a first-effect separator 7, a second-effect heater 8, and a second-effect separator 9. The liquid outlet of the crystallization and granulation fluidized bed 3 is connected to the top end of the first-effect heater 6 through a pipe, so that the wastewater discharged from the liquid outlet of the crystallization and granulation fluidized bed 3 can enter the first-effect heater 6 for heating and evaporation. At the same time, this layout ensures that the flow path of the wastewater in the first-effect heater 6 is from top to bottom, which is the same direction of movement of the calcium carbonate particles under the action of gravity. This allows the calcium carbonate particles to be easily discharged from the first-effect heater 6, thereby minimizing scaling of the first-effect heater 6.

[0053] The bottom port of the first-effect heater 6 is connected to the liquid inlet pipe of the crystallization granulation fluidized bed 3, and the side port of the first-effect heater 6 is connected to the feed pipe of the first-effect separator 7, so that part of the wastewater after de-hardening by the first-effect heater 6 can enter the first-effect separator 7 for flash evaporation, and the other part can flow back to the crystallization granulation fluidized bed 3 for circulation. A first-effect forced circulation pump 10 is provided on the pipeline connecting the bottom port of the first-effect heater 6 and the liquid inlet end of the crystallization granulation fluidized bed 3. The pipeline connecting the high-hardness and high-salt wastewater and the liquid inlet end of the crystallization granulation fluidized bed 3 passes through the first-effect forced circulation pump 10. The wastewater heated by the first-effect heater 6 has a high temperature. The high-hardness and high-salt wastewater can be mixed with the return liquid with a high temperature, thereby increasing the water inlet temperature of the high-hardness and high-salt wastewater entering the crystallization granulation fluidized bed 3, so as to reduce the solubility of calcium carbonate and the supersaturation required for crystallization, thereby reducing the subsequent dosage of the reagent and reducing the operating cost. At the same time, it can also reduce the occurrence of self-nucleation of calcium carbonate crystals, so that calcium carbonate grows on the crystal seeds, ensuring low turbidity of hard water, and no sedimentation and sludge dewatering system is required. In addition, after the high-hardness and high-salt wastewater is mixed with the return liquid, the inlet and outlet flow of the crystallization granulation fluidized bed 3 can be increased, avoiding the situation where the tower diameter is too small and the tower wall is easily scaled when the flow rate is small. The water softened by crystallization and granulation enters the first-effect heater 6, which can reduce the occurrence of scaling in the first-effect heater 6. The side air inlet pipe of the first-effect heater 6 is connected to the heat source steam, which provides the required heat source for the heating and evaporation work of the first-effect heater 6.

[0054] The liquid outlet end of the first-effect separator 7 is respectively connected to the liquid inlet end of the crystallization granulation fluidized bed 3 and the top port pipe of the second-effect heater 8. After flash evaporation in the first-effect separator 7, part of the wastewater with high temperature will flow back to the crystallization granulation fluidized bed 3, and the other part will enter the second-effect heater 8 for secondary heating and evaporation. The water inlet form of the second-effect heater 8 is arranged in this way, which can make the flow path of the wastewater in the second-effect heater 8 from top to bottom, which is the same as the movement direction of the calcium carbonate particles under the action of gravity, so that the calcium carbonate particles can be easily discharged from the second-effect heater 8 to avoid scaling of the second-effect heater 8 as much as possible. At the same time, the temperature of the wastewater entering the second-effect heater 8 from the first-effect separator 7 is high, so that the second-effect heater 8 has a higher water inlet temperature, which can improve the heat utilization efficiency. The pipeline connecting the liquid outlet of the first-effect separator 7 and the liquid inlet of the crystallization and granulation fluidized bed 3 also passes through the first-effect forced circulation pump 10. This part of the refluxed wastewater also serves to increase the inlet temperature and flow rate of the crystallization and granulation fluidized bed 3. The gas outlet of the first-effect separator 7 is connected to the side gas inlet pipe of the second-effect heater 8. The hot steam generated after flash evaporation in the first-effect separator 7 can enter the second-effect heater 8 through this pipeline, providing the required heat source for the heating and evaporation work of the second-effect heater 8, thereby reducing operation and maintenance costs.

[0055] The bottom port of the second-effect heater 8 is connected to the top port pipe of the second-effect heater 8 to realize the circulation of wastewater, and the side port of the second-effect heater 8 is connected to the feed end pipe of the second-effect separator 9 so that the wastewater heated and evaporated by the second-effect heater 8 can enter the second-effect separator 9 for flash concentration.

[0056] The liquid outlet end of the second effect separator 9 is respectively connected to the top port of the second effect heater 8 and the external dehydration and drying system pipeline. A second effect forced circulation pump 11 is provided on the pipeline connecting the liquid outlet end of the first effect separator 7 and the top port of the second effect heater 8. The pipeline connecting the bottom port of the second effect heater 8 and the top port of the second effect heater 8 and the pipeline connecting the liquid outlet end of the second effect separator 9 and the top port of the second effect heater 8 both pass through the second effect forced circulation pump 11. Through the above-mentioned arrangement, a part of the high-temperature brine remaining at the bottom of the second effect separator 9 after flash evaporation can flow back to the second effect heater 8 for circulation treatment, and can be mixed with the wastewater discharged by the second effect heater 8 and the wastewater discharged by the first effect separator 7 to increase the water inlet amount and water inlet temperature of the wastewater entering the second effect heater 8, thereby improving the heat utilization efficiency. The other part can be input into the external dehydration and drying system for dehydration and drying to generate product salt for collection. The gas outlet end of the second-effect separator 9 is connected to the condenser 4 through a pipeline, so that the secondary steam accumulated on the top of the second-effect separator 9 after flash evaporation can enter the condenser 4 from the gas outlet end for condensation to generate condensed water for reuse.

[0057] The method for using the processing device comprises the following steps:

[0058] The first step: adding crystal seeds into the crystal seed fluidization tank 1, then feeding fluidizing water into the bottom of the crystal seed fluidization tank 1 to fluidize the crystal seeds in the crystal seed fluidization tank 1, starting the crystal seed adding pump 12, and the crystal seed adding pump 12 adds a certain amount of crystal seeds in the crystal seed fluidization tank 1 into the crystallization granulation fluidized bed 3 for crystallization granulation. After the crystal seed adding is completed, the crystal seed adding pump 12 is turned off.

[0059] Step 2: Start the first-effect forced circulation pump 10 to allow the high-hardness, high-salt wastewater to fill the multi-effect evaporation system and circulate. When the high-hardness, high-salt wastewater enters the granulation fluidized bed 3, the seed crystals begin to fluidize. Start the reagent dosing pump 13, which injects the alkaline reagent from the reagent storage tank 2 into the crystallization granulation fluidized bed 3 to react with the mixed high-hardness, high-salt wastewater to remove hardness ions. At this time, the hardness removed in the crystallization granulation fluidized bed 3 adheres to the surface of the seed crystals and begins to form calcium carbonate particles.

[0060] Step 3: Heat source steam is introduced into the first-effect heater 6, and the first-effect heater 6 heats the product water after the hardness is removed by the crystallization granulation fluidized bed 3. The wastewater heated by the first-effect heater 6 enters the first-effect separator 7 for flash separation. After flash evaporation, a high-temperature return liquid will be generated at the bottom of the first-effect separator 7, which is mixed with the incoming high-hardness and high-salt wastewater on the corresponding pipeline and forced to mix and increase the pressure under the action of the first-effect forced circulation pump 10. This increases the inlet temperature of the subsequent crystallization granulation fluidized bed 3 and ensures the flow rate required for the fluidization of the crystal seeds in the crystallization granulation fluidized bed 3. The mixed high-hardness and high-salt wastewater enters the liquid inlet end of the crystallization granulation fluidized bed 3. The mixing ratio can be adjusted, that is, the amount of high-hardness and high-salt wastewater entering the crystallization granulation fluidized bed 3 can be adjusted according to the flow rate of the return liquid to control the hardness of the high-hardness and high-salt wastewater entering the crystallization granulation fluidized bed 3 so that its hardness is less than 1500 mg / L. This can reduce the self-nucleation of calcium carbonate crystals, thereby ensuring that the turbidity of the product water is low enough and there is no need to add a precipitation and dehydration system.

[0061] Step 4: Start the second-effect forced circulation pump 11 and the vacuum pump 5, and use the hot steam generated by the flash evaporation of the first-effect separator 7 to continue heating and evaporating the wastewater concentrated by the first-effect evaporation, so that the internal circulation of the multi-effect evaporation system begins and the gas, condensed water and high brine are discharged; Specifically: under the negative pressure of the vacuum pump 5, the hot steam generated by the flash evaporation of the first-effect separator 7 will enter the second-effect heater 8, providing the required heat source for the operation of the second-effect heater 8, thereby reducing the operating cost;

[0062] Under the action of the second-effect forced circulation pump 11, a portion of the wastewater generated by the first-effect separator 3 can also enter the second-effect heater 8 for heating. The specific amount of wastewater entering can be determined according to actual conditions and can be regulated by setting a valve structure such as a regulating valve on the corresponding pipeline. After the wastewater enters the second-effect heater 8 and is heated, it then enters the second-effect separator 9 for flash evaporation and concentration. The top of the second-effect separator 9 produces higher-temperature secondary steam, and high-temperature brine remains at the bottom. A portion of the high-temperature brine produced at the bottom of the second-effect separator 9 flows back into the second-effect heater 8 for circulation and can be mixed with the wastewater entering from the bottom 3 of the first-effect separator to increase the temperature of the wastewater entering the second-effect heater 8 and improve heat utilization efficiency. The remaining portion can be input into an external dehydration and drying system for dehydration and drying to generate product salt for collection. The specific split flow rate selection and control need to be determined according to actual conditions. The steam accumulated at the top of the second-effect separator 9 can enter the condenser 4 from the air outlet to condense, generating condensate for reuse.

[0063] The fifth step is to shut down the treatment device after it has been working for a certain period of time, and then clean the crystallization and granulation fluidized bed 3 to discharge the mature calcium carbonate particles outward, and then add new crystal seeds to enter a new treatment process.

[0064] The above descriptions are merely embodiments of the present invention and are not intended to limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made using the contents of the present invention's description and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A device for treating high-hardness and high-salt wastewater, comprising a seed fluidized bed tank (1), a reagent storage tank (2) and a crystallization granulation fluidized bed (3), wherein the crystallization granulation fluidized bed (3) is connected to the seed fluidized bed tank (1) and the reagent storage tank (2) through pipelines, and is characterized in that: The treatment device also includes a multi-effect evaporation system, wherein the liquid inlet of the multi-effect evaporation system is connected to the liquid outlet pipe of the crystallization granulation fluidized bed (3), the liquid return of the multi-effect evaporation system is connected to the liquid inlet pipe of the crystallization granulation fluidized bed (3), the gas outlet pipe of the multi-effect evaporation system is connected to a condenser (4), and the condenser (4) is connected to a vacuum pump (5); the liquid return of the multi-effect evaporation system is also externally connected to high-hardness and high-salt wastewater, and the high-hardness and high-salt wastewater can be mixed with the liquid return flowing out of the liquid return of the multi-effect evaporation system and then enter the liquid inlet of the crystallization granulation fluidized bed (3); The multiple-effect evaporation system comprises a first-effect heater (6), a first-effect separator (7), a second-effect heater (8) and a second-effect separator (9), and the multiple-effect evaporation system is used for performing rising film evaporation or falling film evaporation; The liquid outlet of the crystallization granulation fluidized bed (3) is connected to the bottom port of the first-effect heater (6) and the bottom port of the second-effect heater (8) respectively, the top port of the first-effect heater (6) is connected to the feed end pipe of the first-effect separator (7), the side air inlet pipe of the first-effect heater (6) is connected to the heat source steam, the liquid outlet of the first-effect separator (7) is connected to the liquid inlet pipe of the crystallization granulation fluidized bed (3), the air outlet of the first-effect separator (7) is connected to the side of the second-effect heater (8) The first-effect separator (7) is arranged above the crystallization granulation fluidized bed (3); the top port of the second-effect heater (8) is connected to the feed end pipeline of the second-effect separator (9); the side air outlet of the second-effect heater (8) is connected to the condenser (4) through a pipeline; the liquid outlet end of the second-effect separator (9) is respectively connected to the bottom port of the second-effect heater (8) and the external dehydration and drying system pipeline; the air outlet end of the second-effect separator (9) is connected to the condenser (4) through a pipeline.

2. The device for treating high-hardness and high-salt wastewater according to claim 1, characterized in that: A first-effect forced circulation pump (10) is provided on the pipeline connecting the liquid outlet end of the first-effect separator (7) and the liquid inlet end of the crystallization granulation fluidized bed (3), and the pipeline connecting the high-hardness and high-salt wastewater and the liquid inlet end of the crystallization granulation fluidized bed (3) passes through the first-effect forced circulation pump (10).

3. The device for treating high-hardness and high-salt wastewater according to claim 2, characterized in that: A second-effect forced circulation pump (11) is provided on the pipeline connecting the liquid outlet end of the crystallization granulation fluidized bed (3) and the bottom port of the second-effect heater (8), and a pipeline connecting the liquid outlet end of the second-effect separator (9) and the bottom port of the second-effect heater (8) passes through the second-effect forced circulation pump (11).

4. The device for treating high-hardness and high-salt wastewater according to claim 3, characterized in that: A seed dosing pump (12) is provided on the pipeline connecting the feed end of the crystallization granulation fluidized bed (3) and the seed fluidized tank (1), and a drug dosing pump (13) is provided on the pipeline connecting the drug feed end of the crystallization granulation fluidized bed (3) and the drug storage tank (2).

5. A method for using the high-hardness and high-salt wastewater treatment device according to claim 4, characterized in that: The following steps are involved: Step A1: adding seed crystals into the seed crystal fluidization tank (1), then feeding fluidizing water into the bottom of the seed crystal fluidization tank (1) to fluidize the seed crystals in the seed crystal fluidization tank (1), starting the seed crystal feeding pump (12), and the seed crystal feeding pump (12) feeds the fluidized seed crystals in the seed crystal fluidization tank (1) into the crystallization granulation fluidized bed (3) for crystallization granulation; Step A2: starting a single-effect forced circulation pump (10) to allow the wastewater generated by the crystallization granulation to enter the multi-effect evaporation system for circulation, starting the reagent dosing pump (13), and the reagent dosing pump (13) adds the alkaline reagent in the reagent storage tank (2) into the crystallization granulation fluidized bed (3) to react with the mixed high-hardness and high-salt wastewater to remove hardness ions; Step A3: introducing heat source steam into the multi-effect evaporation system, causing the multi-effect evaporation system to heat and evaporate the incoming wastewater, mixing the return liquid flowing out of the return liquid point of the multi-effect evaporation system with the high-hardness and high-salt wastewater, and the mixed high-hardness and high-salt wastewater enters the liquid inlet end of the crystallization granulation fluidized bed (3); Step A4: Start the second-effect forced circulation pump (11) and the vacuum pump (5) to start circulation inside the multi-effect evaporation system and discharge gas, condensed water and high-salt water.

Images