Light salt brine concentration treatment system

Abstract

The invention discloses a light salt brine concentration treatment system, which is characterized in that condensed water generated by a falling film evaporator and a forced circulation evaporator is used as a preheating heat source to preheat mixed light salt brine stock solution, and meanwhile, secondary steam generated by the falling film evaporator and the forced circulation evaporator enters a compressor to be mechanically compressed; after being compressed, heated and pressurized, the secondary steam enters a falling film evaporator and a forced circulation evaporator as a heating source to exchange heat with the materials, so that the mixed light salt brine stock solution is subjected to evaporation concentration treatment twice to obtain a second concentrated salt solution; finally, the second concentrated salt solution is subjected to heat exchange treatment through a preheating assembly to obtain a strong brine product with relatively high salt concentration; when the light salt brine concentration treatment system is used for concentration treatment, fresh steam does not need to be supplied externally, secondary steam generated by the system and a compressor system serve as heat sources, the purpose of saving energy can be achieved, and then the concentration cost of light salt brine is effectively reduced.

Description

Technical Field

[0001] The invention relates to the technical field of industrial wastewater treatment, and in particular to a salt water concentration treatment system. Background Art

[0002] Industrial enterprises need to reduce or "zero discharge" the current wastewater discharge. In addition to conventional pollutants such as suspended solids and COD, the wastewater generated by industrial boilers also contains a large amount of inorganic salts and other salts accumulated in various process discharge links. The existing wastewater concentration process mainly adopts chemical dosing softening + clarification filtration + membrane concentration. The pollutants and water are separated by chemical reaction + physical filtration, and finally part of the water in the wastewater can be recycled. The remaining water and pollutants are treated in the next step to achieve the purpose of recycling the water in the wastewater. However, the investment and operation costs of the above treatment process are high, and the process flow is complicated, which requires a high level of operators. At present, there are many projects in China that cannot operate normally after the commissioning is completed and the contractor's technicians leave the site. At the same time, many operators are required, the labor cost is high, and unattended automatic operation cannot be achieved. At the same time, the above concentration process is still based on the traditional water treatment ideas, which fails to combine the actual situation of industrial boilers and fails to use energy according to local conditions, resulting in excessive costs and waste.

[0003] Therefore, there is an urgent need for a salt water concentration treatment system to solve the above technical problems. Summary of the invention

[0004] In view of this, the present application provides a desalinated water concentration processing system to solve the technical problem of excessively high cost of existing desalinated water concentration processes.

[0005] The object of the present invention is achieved through the following technical solutions: In order to achieve the above technical objectives, this application adopts the following technical solutions: The invention provides a system for concentrating and treating desalinated brine, comprising a preheating component, a falling film evaporator and a forced circulation evaporator; wherein the preheating component is used for preheating a mixed desalinated brine stock solution to obtain a preheated brine solution; the falling film evaporator is connected to the preheating component and is used for evaporating and concentrating the preheated brine solution to form a first concentrated brine solution; the forced circulation evaporator is connected to the falling film evaporator and is used for evaporating and concentrating the first concentrated brine solution to form a second concentrated brine solution, and the second concentrated brine solution is subjected to heat exchange treatment by the preheating component to obtain a concentrated brine product.

[0006] Preferably, the preheating component includes a condensate preheater and a concentrated brine preheater, the first inlet of the condensate preheater is connected to the raw material tank, the second inlet of the condensate preheater is connected to the outlet of the condensate tank, the first outlet of the condensate preheater is connected to the first inlet of the concentrated brine preheater, and the second outlet of the condensate preheater is used to discharge condensate.

[0007] Preferably, the second inlet of the concentrated brine preheater is communicated with the forced circulation evaporator, the first outlet of the concentrated brine preheater is communicated with the falling film evaporator, and the second outlet of the concentrated brine preheater is communicated with the concentrated brine tank.

[0008] Preferably, the falling film evaporator includes a falling film heater and a falling film separator, the first inlet of the falling film heater is connected to the first outlet of the concentrated brine preheater, and the second inlet of the falling film heater is connected to the first outlet of the compressor; the first outlet of the falling film heater is connected to the first inlet of the falling film separator, and the second outlet of the falling film heater is connected to the first inlet of the condensed water tank.

[0009] Preferably, the first outlet of the falling film separator is communicated with the inlet of the forced circulation evaporator, and the second outlet of the falling film separator is communicated with the inlet of the compressor.

[0010] Preferably, the forced circulation evaporator includes a forced heater and a forced separator, the first inlet of the forced heater is connected to the first outlet of the falling film separator, and the second inlet of the forced heater is connected to the second inlet of the compressor; the first outlet of the forced heater is connected to the first inlet of the forced separator, and the second outlet of the forced heater is connected to the second inlet of the condensed water tank.

[0011] Preferably, the first outlet of the forced separator is communicated with the second inlet of the concentrated brine preheater, and the second outlet of the forced separator is communicated with the inlet of the compressor.

[0012] Preferably, both the falling film separator and the forced separator are MVR evaporators.

[0013] Preferably, the salt water concentration treatment system also includes a scrubbing tower, a first inlet of the scrubbing tower is connected to the second outlet of the falling film separator, a second inlet of the scrubbing tower is connected to the second outlet of the forced separator; and an outlet of the scrubbing tower is connected to the inlet of the compressor.

[0014] Preferably, the concentration range of the mixed light brine stock solution is 150-250 g / L, and the temperature range of the mixed light brine stock solution is 20-60°C; the concentration range of the concentrated brine product is 250-350 g / L, and the temperature range of the concentrated brine product is 60-100°C.

[0015] Beneficial effect: The present invention uses the condensed water generated by the falling film evaporator and the forced circulation evaporator as a preheating heat source to preheat the mixed brine stock solution, and at the same time, the secondary steam generated by the falling film evaporator and the forced circulation evaporator enters the compressor for mechanical compression, and the secondary steam is compressed, heated and pressurized, and then enters the falling film evaporator and the forced circulation evaporator as a heating heat source to exchange heat with the material, so that the mixed brine stock solution is evaporated and concentrated twice to obtain a second concentrated brine, and finally the second concentrated brine is heat-exchanged by the preheating component to obtain a concentrated brine product with a higher salt concentration; the present brine concentration treatment system does not require external fresh steam during the concentration treatment, and uses the secondary steam generated by the system itself and the compressor system as heat sources to achieve the purpose of energy saving, thereby effectively reducing the concentration cost of the brine. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is a process flow chart of a desalinated water concentration treatment system provided in an embodiment of the present application. DETAILED DESCRIPTION

[0017] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0018] Aiming at the technical problem that the existing salt water concentration process has high cost, the present invention can solve the above technical problem.

[0019] See also Figure 1 , Figure 1 A process flow chart of a desalinated brine concentration treatment system provided in an embodiment of the present application; wherein the desalinated brine concentration treatment system provided by the present invention comprises a preheating component, a falling film evaporator and a forced circulation evaporator; Among them, the preheating component is used to preheat the mixed light salt water stock solution to obtain a preheated salt solution; the falling film evaporator is connected to the preheating component, and is used to evaporate and concentrate the preheated salt solution to form a first concentrated salt solution; the forced circulation evaporator is connected to the falling film evaporator, and is used to evaporate and concentrate the first concentrated salt solution to form a second concentrated salt solution, and the second concentrated salt solution is subjected to heat exchange treatment by the preheating component to obtain a concentrated salt water product.

[0020] In the embodiment of the present invention, the function of the preheating component is to increase the temperature of the mixed salt water stock solution to save energy for the subsequent evaporation and concentration process. Through the two-stage preheating of the preheating component, the waste heat of the condensed water can be fully utilized to greatly reduce the energy demand in the evaporation and concentration process.

[0021] Specifically, the preheating component includes a condensate preheater and a concentrated brine preheater. The first inlet of the condensate preheater is connected to the raw material tank, the second inlet of the condensate preheater is connected to the outlet of the condensate tank, the first outlet of the condensate preheater is connected to the first inlet of the concentrated brine preheater, and the second outlet of the condensate preheater is used to discharge condensate.

[0022] Specifically, the second inlet of the concentrated brine preheater is communicated with the forced circulation evaporator, the first outlet of the concentrated brine preheater is communicated with the falling film evaporator, and the second outlet of the concentrated brine preheater is communicated with the concentrated brine tank.

[0023] Furthermore, the condensate preheater utilizes the waste heat of the condensate to preheat the mixed brine stock solution, fully recovering the heat of the condensate and reducing energy consumption. The condensate releases heat in this process and is discharged.

[0024] Furthermore, the concentrated brine preheater includes a plurality of concentrated brine preheating plates arranged in parallel, and the concentrated brine preheater can further increase the temperature of the brine, create better conditions for the subsequent evaporation and concentration process, and improve the energy efficiency of the entire system.

[0025] In an embodiment of the present invention, the falling film evaporator includes a falling film heater and a falling film separator, the first inlet of the falling film heater is connected to the first outlet of the concentrated brine preheater, and the second inlet of the falling film heater is connected to the first outlet of the compressor; the first outlet of the falling film heater is connected to the first inlet of the falling film separator, and the second outlet of the falling film heater is connected to the first inlet of the condensed water tank; the first outlet of the falling film separator is connected to the inlet of the forced circulation evaporator, and the second outlet of the falling film separator is connected to the inlet of the compressor.

[0026] Specifically, the falling film heater rapidly heats the salt solution by introducing a high-temperature medium from the compressor to exchange heat with the preheated salt solution. Due to the falling film heating method, the salt solution forms a uniform liquid film along the inner wall of the heating tube under the action of gravity, thereby increasing the heat transfer area and improving the heat transfer efficiency. The falling film heater quickly heats the preheated salt solution to prepare for subsequent evaporation and concentration. At the same time, the generated condensed water is discharged to the condensed water tank to achieve the recycling of the condensed water.

[0027] The falling film separator uses the density difference between the gas and liquid phases to separate the heated brine. Steam and other gases are discharged from the top outlet, while the initially concentrated brine flows out from the bottom outlet. The falling film separator is mainly used to achieve gas-liquid separation, and the initially concentrated first concentrated brine is transported to the forced circulation evaporator for further processing. At the same time, part of the gas may be sent back to the compressor for recycling to improve energy efficiency.

[0028] Furthermore, the falling film separator is an MVR evaporator, which is a mechanical vapor recompression evaporator. MVR evaporation crystallization is an evaporation crystallization technology. MVR is the abbreviation of "Mechanical Vapor Recompression", which means mechanical vapor recompression. In the MVR evaporation crystallization process, the solution to be treated is heated and evaporated, and the generated vapor is compressed to increase its temperature and pressure. Then, the compressed vapor is used as a heating source to heat the solution again, realizing the cycle of evaporation and crystallization.

[0029] Furthermore, MVR evaporation crystallization has the following advantages: Energy saving: By recovering and reusing the energy of steam, the MVR evaporator can significantly reduce energy consumption and has higher energy efficiency than traditional evaporation crystallization methods.

[0030] Environmental protection: Due to the reduction of steam emissions, the MVR evaporator has less impact on the environment and meets the requirements of sustainable development.

[0031] Simple operation: MVR evaporator usually has automatic control function, which is relatively simple to operate and can achieve stable operation and production.

[0032] In an embodiment of the present invention, the forced circulation evaporator includes a forced heater and a forced separator, the first inlet of the forced heater is connected to the first outlet of the falling film separator, and the second inlet of the forced heater is connected to the second inlet of the compressor; the first outlet of the forced heater is connected to the first inlet of the forced separator, and the second outlet of the forced heater is connected to the second inlet of the condensed water tank; the first outlet of the forced separator is connected to the second inlet of the concentrated brine preheater, and the second outlet of the forced separator is connected to the inlet of the compressor.

[0033] Specifically, the forced heater introduces a high-temperature medium from the compressor to exchange heat with the preliminarily concentrated first concentrated salt solution, so that the first concentrated salt solution continues to heat up and accelerates the evaporation and concentration process. The forced circulation method ensures that the first concentrated salt solution continues to flow in the heater, avoids local overheating and scaling, and improves heat transfer efficiency. The forced heater is used to further heat the first concentrated salt solution from the falling film separator to achieve a higher degree of concentration. At the same time, the generated condensed water is discharged to the condensed water tank for recycling.

[0034] Specifically, the forced separator uses the density difference between the gas and liquid phases to separate the heated first concentrated salt solution again. Gases such as secondary steam are discharged from the top outlet, while the highly concentrated second concentrated salt solution flows out from the bottom outlet. The forced separator is used to achieve gas-liquid separation, and the highly concentrated second concentrated salt solution is transported to the brine preheater for heat exchange, providing heat for the mixed light brine stock solution entering the system, thereby realizing energy recovery. At the same time, part of the gas may be sent back to the compressor for recycling to improve energy efficiency.

[0035] Preferably, the forced separator is an MVR evaporator.

[0036] In an embodiment of the present invention, the salt water concentration treatment system further includes a scrubber, wherein the first inlet of the scrubber is connected to the second outlet of the falling film separator, and the second inlet of the scrubber is connected to the second outlet of the forced separator; the outlet of the scrubber is connected to the inlet of the compressor. The scrubber improves the performance of the entire salt water concentration treatment system by removing impurities in the secondary steam generated by the falling film evaporator and the forced circulation evaporator. The reduction of impurities can reduce the risk of system blockage, improve heat transfer efficiency, and ensure continuous operation of the system.

[0037] In an embodiment of the present invention, the concentration range of the mixed light brine stock solution is 150-250 g / L, and the temperature range of the mixed light brine stock solution is 20-60°C; the concentration range of the concentrated brine product is 250-350 g / L, and the temperature range of the concentrated brine product is 60-100°C. Among them, compared with the mixed light brine stock solution, the concentrated brine product has a higher concentration and achieves the treatment goal. The concentrated brine product in this concentration range can meet specific industrial needs; at the same time, the temperature of the concentrated brine product is relatively high, which is the result of evaporation and concentration treatment. Higher temperatures may affect subsequent processing or use links, and appropriate cooling or insulation measures are required.

[0038] The technical solution of the present invention is now further described in conjunction with specific embodiments.

[0039] Embodiment 1: See also Figure 1 The evaporation rate of condensed water in the salt water concentration treatment system provided in Example 1 of the present invention is 50m 3 / h, the processing capacity of mixed salt water is 150m 3 / h, the discharge volume of concentrated brine product is 100m 3 / h.

[0040] Specifically, the process parameters of the desalinated water concentration treatment system provided in Example 1 of the present invention are shown in Table 1 below: Table 1 Process parameters of Example 1 of the present invention

[0041] Specifically, the specific process flow of Example 1 of the present invention is as follows: Material flow: First, the mixed light brine stock solution (150t / h, 200g / L, 50℃) flows out from the buyer's raw material tank and is transported to the condensate preheater through the feed pump; then, the mixed light brine stock solution (150t / h, 200g / L, 69℃) after heat exchange with evaporated condensed water enters two parallel concentrated brine preheating plates for heat exchange with concentrated brine to obtain preheated brine (150t / h, 200g / L, 84℃); then, the preheated brine after heat exchange enters the falling film evaporator for evaporation and concentration; the first concentrated liquid (116.5t / h, 257.5g / L, 104℃) of the falling film evaporation is transferred to the forced circulation evaporator through the material transfer regulating valve for further evaporation and concentration. After that, the second concentrated liquid that meets the requirements (100t / h, 300g / L, 108℃) is transported to the brine preheater through the discharge pump, and after heat exchange and cooling with the dilute brine (100t / h, 300g / L, 86℃), it is sent out of the system to the buyer's brine tank.

[0042] (2) Secondary steam process: The secondary steam (33.5t / h, -0.002MPa, 100℃) generated by the falling film separator and the secondary steam (16.5t / h, -0.002MPa, 100℃) generated by the forced separator enter the scrubbing tower together, and are in direct contact with the evaporated condensed water for washing. After washing, the secondary steam (50t / h, -0.002MPa, 100℃) enters the steam compressor for mechanical compression. After the secondary steam is compressed and heated and pressurized (50t / h, 0.086MPa, 118℃), it enters the falling film evaporator and forced circulation evaporator as a heating heat source to exchange heat with the material, and the secondary steam is condensed into condensed water.

[0043] (3) Condensate process: The secondary steam condensate in the falling film evaporator (33.5t / h, 0.086MPa, 118℃) and the secondary steam condensate in the forced circulation evaporator (16.5t / h, 0.086MPa, 118℃) flow into the same condensate tank by gravity. The condensate (50t / h, 0.086MPa, 118℃) flows from the bottom of the tank to the condensate plate exchanger for heat exchange and cooling with the original liquid. It then comes out of the plate exchanger (50t / h, normal pressure, 60℃) and is pumped out of the system through the evaporation condensate pump.

[0044] Embodiment 2: See also Figure 1 The evaporation rate of condensed water in the salt water concentration treatment system provided in Example 2 of the present invention is 100m 3 / h, the processing capacity of mixed salt water is 300m 3 / h, the discharge volume of concentrated brine product is 200m 3 / h.

[0045] Specifically, the process parameters of the desalinated water concentration treatment system provided in Example 2 of the present invention are shown in Table 2 below: Table 2 Process parameters of Example 2 of the present invention

[0046] Specifically, the specific process flow of Example 2 of the present invention is as follows: Material flow: First, the mixed light brine stock solution (300t / h, 200g / L, 50℃) flows out from the buyer's raw material tank and is transported to the condensate preheater through the feed pump; then, the mixed light brine stock solution (300t / h, 200g / L, 69℃) after heat exchange with the evaporated condensate water enters two parallel concentrated brine preheating plates for heat exchange with the concentrated brine to obtain preheated brine (300t / h, 200g / L, 84℃); then, the preheated brine after heat exchange enters the falling film evaporator for evaporation and concentration; the first concentrated liquid (233t / h, 257.5g / L, 104℃) of the falling film evaporation is transferred to the forced circulation evaporator through the material transfer regulating valve for further evaporation and concentration. After that, the second concentrated liquid that meets the requirements (200t / h, 300g / L, 108℃) is transported to the brine preheater through the discharge pump, and after heat exchange and cooling with the dilute brine (200t / h, 300g / L, 86℃), it is sent out of the system to the buyer's brine tank.

[0047] (2) Secondary steam process: The secondary steam (67t / h, -0.002MPa, 100℃) generated by the falling film separator and the secondary steam (33t / h, -0.002MPa, 100℃) generated by the forced separator enter the scrubbing tower together, and are in direct contact with the evaporated condensed water for washing. After washing, the secondary steam (100t / h, -0.002MPa, 100℃) enters the steam compressor for mechanical compression. After the secondary steam is compressed and heated and pressurized (100t / h, 0.086MPa, 118℃), it enters the falling film evaporator and forced circulation evaporator as a heating heat source to exchange heat with the material, and the secondary steam is condensed into condensed water.

[0048] (3) Condensate process: The secondary steam condensate in the falling film evaporator (67t / h, 0.086MPa, 118℃) and the secondary steam condensate in the forced circulation evaporator (33t / h, 0.086MPa, 118℃) flow by gravity into the same condensate tank. The condensate (100t / h, 0.086MPa, 118℃) flows by gravity from the bottom of the tank to the condensate plate exchanger for heat exchange and cooling with the original liquid. It then comes out of the plate exchanger (100t / h, normal pressure, 60℃) and is pumped out of the system through the evaporation condensate pump.

[0049] The desalinated brine concentration treatment system provided by the present invention adopts MVR evaporation crystallization method, adopts "MVR falling film + forced circulation" process, and is designed with two production lines. One line has an evaporation capacity of 50m³ / h, a processing capacity of 150m³ / h, and a discharge capacity of 100m³ / h; the other line has an evaporation capacity of 100m³ / h, a processing capacity of 300m³ / h, and a discharge capacity of 200m³ / h.

[0050] The present invention adopts a domestically produced centrifugal compressor as the main device for providing temperature rise, the inlet temperature of the compressor is 100°C, and the outlet temperature is 118°C.

[0051] To sum up, different from the prior art, the present invention uses the condensed water produced by the falling film evaporator and the forced circulation evaporator as a preheating heat source to preheat the mixed brine stock solution, and at the same time, the secondary steam produced by the falling film evaporator and the forced circulation evaporator enters the compressor for mechanical compression, and after the secondary steam is compressed and heated and pressurized, it enters the falling film evaporator and the forced circulation evaporator as a heating heat source to exchange heat with the material, so that the mixed brine stock solution is evaporated and concentrated twice to obtain a second concentrated brine, and finally the second concentrated brine is heat exchanged by the preheating component to obtain a concentrated brine product with a higher salt concentration; the present brine concentration treatment system does not require external fresh steam during the concentration treatment, and uses the secondary steam generated by the system itself and the compressor system as heat sources to achieve the purpose of energy saving, thereby effectively reducing the concentration cost of the brine.

[0052] The above are only preferred specific implementations of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by any technician familiar with the technical field within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention.

Claims

1. A system for concentrating and treating desalinated water, characterized in that: include: A preheating component, used for preheating the mixed salt water stock solution to obtain a preheated salt solution; A falling film evaporator, connected to the preheating assembly, for evaporating and concentrating the preheated salt solution to form a first concentrated salt solution; as well as The forced circulation evaporator is connected to the falling film evaporator and is used to evaporate and concentrate the first concentrated salt solution to form a second concentrated salt solution. The second concentrated salt solution is subjected to heat exchange treatment by the preheating component to obtain a concentrated salt water product.

2. The desalinated water concentration treatment system according to claim 1, characterized in that: The preheating assembly includes a condensate preheater and a concentrated brine preheater. The first inlet of the condensate preheater is connected to the raw material tank, the second inlet of the condensate preheater is connected to the outlet of the condensate tank, the first outlet of the condensate preheater is connected to the first inlet of the concentrated brine preheater, and the second outlet of the condensate preheater is used to discharge condensate.

3. The desalinated water concentration treatment system according to claim 2, characterized in that: The second inlet of the concentrated brine preheater is communicated with the forced circulation evaporator, the first outlet of the concentrated brine preheater is communicated with the falling film evaporator, and the second outlet of the concentrated brine preheater is communicated with the concentrated brine tank.

4. The desalinated water concentration treatment system according to claim 2, characterized in that: The falling film evaporator includes a falling film heater and a falling film separator, wherein the first inlet of the falling film heater is connected to the first outlet of the concentrated brine preheater, and the second inlet of the falling film heater is connected to the first outlet of the compressor; the first outlet of the falling film heater is connected to the first inlet of the falling film separator, and the second outlet of the falling film heater is connected to the first inlet of the condensed water tank.

5. The desalinated water concentration treatment system according to claim 4, characterized in that: The first outlet of the falling film separator is communicated with the inlet of the forced circulation evaporator, and the second outlet of the falling film separator is communicated with the inlet of the compressor.

6. The desalinated water concentration treatment system according to claim 4, characterized in that: The forced circulation evaporator includes a forced heater and a forced separator, wherein the first inlet of the forced heater is connected to the first outlet of the falling film separator, and the second inlet of the forced heater is connected to the second inlet of the compressor; the first outlet of the forced heater is connected to the first inlet of the forced separator, and the second outlet of the forced heater is connected to the second inlet of the condensed water tank.

7. The desalinated water concentration treatment system according to claim 6, characterized in that: The first outlet of the forced separator is communicated with the second inlet of the concentrated brine preheater, and the second outlet of the forced separator is communicated with the inlet of the compressor.

8. The desalinated water concentration treatment system according to claim 6, characterized in that: The falling film separator and the forced separator are both MVR evaporators.

9. The desalinated water concentration treatment system according to claim 6, characterized in that: The desalinated brine concentration treatment system also includes a scrubbing tower, a first inlet of the scrubbing tower is connected to the second outlet of the falling film separator, a second inlet of the scrubbing tower is connected to the second outlet of the forced separator; and the outlet of the scrubbing tower is connected to the inlet of the compressor.

10. The desalinated water concentration treatment system according to claim 1, characterized in that: The concentration range of the mixed light brine stock solution is 150-250 g / L, and the temperature range of the mixed light brine stock solution is 20-60° C.; the concentration range of the concentrated brine product is 250-350 g / L, and the temperature range of the concentrated brine product is 60-100° C.

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