An evaporation crystallization system

Abstract

This utility model discloses an evaporation crystallization system, aiming to solve the shortcomings of existing multi-effect evaporation crystallization equipment, such as limited cycle times and high initial investment. The utility model includes a preheater, a plate falling film evaporator, a circulating heater, a circulating evaporator, a crystallizer, and a crystal slurry tank connected in sequence. The circulating heater includes a first circulating heater and a second circulating heater. The outlet of the plate falling film evaporator is connected to both the plate falling film evaporator and the evaporator's inlet. The circulating evaporator has a separation outlet and a separation inlet. The circulating evaporator is connected in series with the first and second circulating heaters via the separation outlet and then connected to the separation inlet. This achieves a flexible crystallization system that enables continuous production through multiple evaporation cycles, reducing initial investment and floor space requirements.

Description

Technical Field

[0001] This utility model relates to the field of liquid evaporation and separation, and more specifically, it relates to an evaporation crystallization system. Background Technology

[0002] Existing concentration and evaporation equipment mostly consists of multi-effect units connected in series, with a fixed number of material circulation cycles, making it difficult to handle materials with varying concentrations. Connecting multi-effect units in series can improve heat utilization efficiency and provide better separation efficiency compared to single-effect units. However, multi-effect units also require more initial investment and floor space.

[0003] Given the limitations of existing multi-effect evaporation crystallization equipment in terms of the number of cycles and the large initial investment, this application aims to provide a flexible crystallization system that achieves continuous production through multiple evaporation cycles, thereby reducing initial investment and floor space requirements. Utility Model Content

[0004] This invention provides an evaporation crystallization system that enables flexible crystallization through multiple cyclic evaporations to achieve continuous production, thereby reducing initial investment and floor space requirements.

[0005] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0006] An evaporation crystallization system includes a preheater, a plate falling film evaporator, a circulating heater, a circulating evaporator, a crystallizer, and a crystallization tank connected in sequence. The circulating heater includes a first circulating heater and a second circulating heater. The outlet of the plate falling film evaporator is connected to the inlet of the plate falling film evaporator and the evaporator, respectively. The circulating evaporator is provided with a separation outlet and a separation inlet. The circulating evaporator is connected in series with the first circulating heater and the second circulating heater through the separation outlet and then connected to the separation inlet.

[0007] The reverse circulation evaporation crystallization system in this application has two circulating evaporation structures. Material leaving the plate falling film evaporator can be continuously concentrated in the plate falling film evaporator. Another portion of the material enters a circulating heater-circulating evaporator cycle, where it is superheated. Then, in the circulating evaporator, the rapid pressure drop causes flash evaporation or rapid boiling of the wastewater. Solutions that do not meet the discharge standards are recirculated through the circulating heater-circulating evaporator until the material concentration reaches supersaturation. Afterward, the material enters the crystallizer and crystal slurry tank, where solid materials are separated through cooling and centrifugation. The remaining waste liquid returns to the circulating heater-circulating evaporator. This two-cycle heating-evaporation system achieves a continuous feeding and continuous discharging production method.

[0008] Preferably, the liquid outlet is located above the liquid inlet. This arrangement allows the hotter material to flow to the bottom of the circulating evaporator, accelerating heat exchange and maintaining the overall material temperature, thus enabling continuous boiling or flash evaporation.

[0009] Preferably, the circulating evaporator is equipped with an inner inlet pipe, one end of which is connected to the liquid outlet, and the other end of which is connected to a preset clear liquid height position in the circulating evaporator. The clear liquid in the upper layer of the circulating evaporator is taken through the inner inlet pipe. The clear liquid has a low concentration and is easy to flow in the circulation of the circulating heater and circulating evaporator.

[0010] Preferably, a forced circulation pump is also provided between the first and second circulating heaters. The forced circulation pump causes the material to overcome gravity and move upwards from the bottom of the second circulating heater into the circulating evaporator.

[0011] Preferably, the outlet of the plate falling film evaporator is connected to the inlet of the plate falling film evaporator via a falling film circulation pump; the outlet of the plate falling film evaporator is connected to the circulating evaporator via a feed pump. The material flowing out of the outlet of the plate falling film evaporator is split into two parts: one part flows back to the plate falling film evaporator via the falling film circulation pump, and the other part is sent into the circulating evaporator.

[0012] Preferably, the outlet of the plate falling film evaporator is connected to a four-way pipe. Four copper pipes are connected to the inlets of the falling film circulation pump and the feed pump, respectively. The four-way pipe is also connected to the inlet of the residual liquid tank. A switch valve is installed on the pipeline between the four-way pipe and the residual liquid tank. During system cleaning, the switch valve is opened to allow material to enter the residual liquid tank.

[0013] Preferably, the outlet of the first circulating heater is connected to the inlet of the residual liquid tank, and a switching valve is installed between the pipeline of the first circulating heater and the residual liquid tank. The switching valve and the residual liquid tank temporarily hold materials during the cleaning system.

[0014] Preferably, the bottom of the circulating evaporator is connected to the upper part of the circulating evaporator and the crystallizer via a discharge pump. This structure achieves a third circulation, where part of the material enters the crystallizer for crystallization, while the remainder flows back to the circulating evaporator, entering the circulating heater-circulating evaporator cycle.

[0015] Preferably, the system also includes a steam compressor connected to a low-pressure steam source. The steam compressor's inlet is connected to an inlet pipe, which in turn connects to a plate-type falling film evaporator and a circulating evaporator. The steam compressor's outlet is connected to a supply pipe, and the supply pipe connects to the plate-type falling film evaporator and a circulating heater. The steam compressor generates heat through mechanical action, compresses the steam to increase its thermal energy, and then the pressurized steam enters the plate-type falling film evaporator and the circulating heater. The steam discharged from the plate-type falling film evaporator and the circulating evaporator is then returned, continuously providing heat through repeated cycles.

[0016] Preferably, the preheater includes a first preheater and a second preheater. A low-pressure steam source is connected to the second preheater and exchanges heat with the material in the second preheater. The condensate generated by the plate falling film evaporator and the circulating heater is connected to the first preheater through pipelines and exchanges heat with the material in the first preheater. The low-pressure steam source supplements steam and, together with the condensate, heats the first and second preheaters in a stepped manner, thus reusing heat and reducing heat loss.

[0017] Compared with the prior art, the beneficial effects of this utility model are:

[0018] (1) The continuous feeding and discharging production mode is achieved through the circulation of the plate falling film evaporator and the circulation of the circulating heater-circulating evaporator, which is suitable for long-term stable production;

[0019] (2) By circulating the plate falling film evaporator and circulating the circulating heater-circulating evaporator, the number of equipment is reduced, the production efficiency per unit area is improved, and the pipeline layout is simplified.

[0020] (3) By setting up multiple circulation flows, it can effectively cope with material flows with variable concentrations, and improve the versatility of the system by adjusting the number of circulations. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the present invention;

[0022] Figure 2 This is a schematic diagram of the material flow related to this utility model;

[0023] Figure 3 This is a schematic diagram of the steam flow of this utility model;

[0024] Figure 4 This is a schematic diagram of the circulation of condensate and non-condensable gas according to this utility model;

[0025] In the picture

[0026] Plate falling film evaporator 1, circulating evaporator 2, crystallizer 3, crystal slurry tank 4, first circulation heater 5, second circulation heater 6, separated liquid outlet 7, separated liquid inlet 8, internal guiding pipe 9, forced circulation pump 10, falling film circulation pump 11, feeding pump 12, switch valve 13, residual liquid tank 14, discharging pump 15, steam compressor 16, first preheater 17, second preheater 18, non-condensable gas pipe 19, vacuum pump 20, condensate water tank 21, condenser 22, condensate water pipe 23. Detailed implementation manners

[0027] The present disclosure will be further described below in conjunction with the drawings and embodiments.

[0028] It should be noted that the following detailed descriptions are all illustrative and intended to provide further explanations for the present application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which the present application belongs.

[0029] It should be noted that the terms used herein are only for describing specific implementation manners and are not intended to limit the exemplary implementation manners according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0030] In the present disclosure, terms such as "upper", "lower", "left", "right", "front", "rear", "vertical", "horizontal", "side", "bottom", etc. indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings. They are only relationship terms determined for the convenience of describing the structural relationship of each component or element of the present disclosure and do not specifically refer to any component or element in the present disclosure and should not be construed as a limitation to the present disclosure.

[0031] In the present disclosure, terms such as "fixed connection", "connected", "connection", etc. should be understood in a broad sense, indicating that it can be a fixed connection, an integral connection or a detachable connection; it can be directly connected or indirectly connected through an intermediate medium. For those related scientific research or technical personnel in the field, the specific meanings of the above terms in the present disclosure can be determined according to specific situations and should not be construed as a limitation to the present disclosure.

[0032] Embodiment:

[0033] Refer Figure 1As shown in the figure, an evaporation crystallization system includes a preheater, a plate falling film evaporator 1, a circulation heater, a circulation evaporator 2, a crystallizer 3 and a crystal slurry tank 4, which are connected in sequence. The circulation heater includes a first circulation heater 5 and a second circulation heater 6. The discharge port of the plate falling film evaporator 1 is respectively connected to the feed ports of the plate falling film evaporator 1 and the evaporator. The circulation evaporator 2 is provided with a separated liquid outlet 7 and a separated liquid inlet 8. The circulation evaporator 2 is connected in series with the first circulation heater 5 and the second circulation heater 6 through the separated liquid outlet 7 and then accesses the separated liquid inlet 8.

[0034] Among them, a forced circulation pump 10 is further provided between the first circulation heater 5 and the second circulation heater 6. Through the forced circulation pump 10, the material overcomes gravity and flows upward from the bottom of the second circulation heater 6 into the circulation evaporator 2.

[0035] Refer Figure 2 As shown in the figure, the discharge port of the plate falling film evaporator 1 is connected to the feed port of the plate falling film evaporator 1 through a falling film circulation pump 11; the discharge port of the plate falling film evaporator 1 is connected to the circulation evaporator 2 through a passing material pump 12. The material flowing out of the discharge port of the plate falling film evaporator 1 is divided into two parts. One part flows back to the plate falling film evaporator 1 through the falling film circulation pump 11, and the other part is sent into the circulation evaporator 2.

[0036] The separated liquid outlet 7 is located above the separated liquid inlet 8. This setting enables the relatively hot material to flow to the lower part of the circulation evaporator 2, accelerating the heat exchange of the material and maintaining the temperature of the overall material, so as to continuously boil or flash. Among them, the circulation evaporator 2 is provided with an internal guiding pipe 9. One end of the internal guiding pipe 9 is connected to the separated liquid outlet 7, and the other end of the internal guiding pipe 9 is connected to a preset clear liquid height position of the circulation evaporator 2. The clear liquid in the upper layer of the circulation evaporator 2 is taken through the internal guiding pipe 9. The concentration of the clear liquid is relatively low and it is easy to flow in the cycle of the circulation heater - circulation evaporator 2.

[0037] The discharge port of the plate falling film evaporator 1 is connected to a four-way pipe. The four copper pipes are respectively connected to the liquid inlet of the falling film circulation pump 11 and the passing material pump 12. The four-way pipe is also connected to the liquid inlet of the residual liquid tank 14. A switching valve 13 is provided on the pipeline between the four-way pipe and the residual liquid tank 14. When cleaning the system, the switching valve 13 is opened to allow the material to enter the residual liquid tank 14. The liquid outlet of the first circulation heater 5 is connected to the liquid inlet of the residual liquid tank 14. A switching valve 13 is provided on the pipeline between the first circulation heater 5 and the residual liquid tank 14. The switching valve 13 and the residual liquid tank 14 temporarily store the material when cleaning the system.

[0038] The bottom of the circulation evaporator 2 is connected to the upper part of the circulation evaporator 2 and the crystallizer 3 respectively through a discharge pump 15. This structure realizes the third cycle. Part of the material enters the crystallizer 3 for crystallization, and the rest flows back into the circulation evaporator 2 and enters the cycle of the circulation heater - circulation evaporator 2.

[0039] As shown Figure 3 The route of the steam is indicated by a dotted line. There is also a steam compressor 16. The steam compressor 16 is connected to a low-pressure steam source. The intake port of the steam compressor 16 is connected to an intake pipe, and the intake pipe is connected to the plate falling film evaporator 1 and the circulation evaporator 2. The outlet port of the steam compressor 16 is connected to a supply pipe, and the supply pipe is connected to the plate falling film evaporator 1 and the circulation heater. The steam compressor 16 generates heat through mechanical work, increases the thermal energy of the steam by compressing the steam, and the pressurized steam enters the plate falling film evaporator 1 and the circulation heater, and then sends back the steam discharged from the plate falling film evaporator 1 and the circulation evaporator 2. Through repeated circulation, heat is continuously provided. The preheater includes a first preheater 17 and a second preheater 18. The low-pressure steam source is connected to the second preheater 18 and exchanges heat with the material in the second preheater 18. The condensed water generated by the plate falling film evaporator 1 and the circulation heater is connected to the first preheater 17 through a pipeline and exchanges heat with the material in the first preheater 17. The low-pressure steam source supplements steam and heats the second preheater 18. The low-pressure steam source and the condensed water heat the first preheater 17 and the second preheater 18 in a stepped manner, reusing heat and reducing heat loss.

[0040] As shown Figure 4 The double-dotted line represents non-condensable gas, and the dotted line represents condensed water. There is also a condensate pipe 23. The condensed water is connected to the steam compressor 16, the plate falling film evaporator 1 and the circulation heater and is connected to the condensate tank 21. There is also a non-condensable gas pipe 19. The non-condensable gas pipe 19 is connected to a vacuum pump 20 that generates negative pressure and is connected to the plate falling film evaporator 1 and the circulation heater. The non-condensable gas generated by the plate falling film evaporator 1 and the circulation heater is connected to the condenser 22 through the non-condensable gas pipe 19, and after cooling, it enters the external water pool. In some optional solutions, the condensate pipe 23 is also connected to the non-condensable gas pipe 19 to lead the non-condensable gas in the condensate pipe 23 into the non-condensable gas pipe 19.

[0041] The reverse circulation evaporation crystallization system in this application has two circulating evaporation structures. Material leaving the plate falling film evaporator 1 can be continuously concentrated within it. Another portion of the material enters a circulation heater-circulating evaporator 2, where it is superheated. Upon entering the circulating evaporator 2, the rapid pressure drop causes flash evaporation or rapid boiling of the wastewater. Solutions that do not meet the discharge standards are repeatedly circulated between the heater and evaporator 2 until the material concentration reaches supersaturation. Then, the material enters the crystallizer 3 and crystal slurry tank 4, where solid materials are separated through cooling and centrifugation. The remaining waste liquid returns to the heater-circulating evaporator 2. This two-cycle heating-evaporation system achieves continuous feeding and continuous discharging.

[0042] The embodiments described above are merely preferred solutions of this utility model and are not intended to limit this utility model in any way. Other variations and modifications are possible without departing from the technical solutions described in the claims.

Claims

1. An evaporative crystallization system, characterized by, It includes a preheater, a plate falling film evaporator, a circulating heater, a circulating evaporator, a crystallizer, and a crystal slurry tank connected in sequence. The circulating heater includes a first circulating heater and a second circulating heater. The outlet of the plate falling film evaporator is connected to the inlet of the plate falling film evaporator and the evaporator, respectively. The circulating evaporator is provided with a separation outlet and a separation inlet. The circulating evaporator is connected in series with the first circulating heater and the second circulating heater through the separation outlet and then connected to the separation inlet.

2. An evaporative crystallization system according to claim 1, characterized in that The liquid outlet is located above the liquid inlet.

3. The evaporation crystallization system according to claim 2, characterized in that, The circulating evaporator is equipped with an inner inlet pipe. One end of the inner inlet pipe is connected to the liquid outlet, and the other end of the inner inlet pipe is connected to the preset clear liquid height position of the circulating evaporator.

4. The evaporation crystallization system according to claim 1, characterized in that, A forced circulation pump is also provided between the first and second circulating heaters.

5. The evaporation crystallization system according to claim 1, characterized in that, The outlet of the plate falling film evaporator is connected to the inlet of the plate falling film evaporator through a falling film circulation pump; the outlet of the plate falling film evaporator is connected to the circulating evaporator through a feed pump.

6. The evaporation crystallization system according to claim 5, characterized in that, The outlet of the plate falling film evaporator is connected to a four-way pipe. The four copper pipes are respectively connected to the inlet of the falling film circulation pump and the feed pump. The four-way pipe is also connected to the inlet of the residual liquid tank. A switch valve is installed on the pipeline between the four-way pipe and the residual liquid tank.

7. The evaporation crystallization system according to claim 6, characterized in that, The outlet of the first circulating heater is connected to the inlet of the residual liquid tank, and a switch valve is provided between the pipeline of the first circulating heater and the residual liquid tank.

8. The evaporation crystallization system according to claim 1, characterized in that, The bottom of the circulating evaporator is connected to the top of the circulating evaporator and the crystallizer via a discharge pump.

9. The evaporation crystallization system according to claim 1, characterized in that, It also includes a steam compressor, which is connected to a low-pressure steam source. The steam compressor's inlet is connected to an inlet pipe, which is connected to a plate falling film evaporator and a circulating evaporator. The steam compressor's outlet is connected to a supply pipe, which is connected to a plate falling film evaporator and a circulating heater.

10. An evaporation crystallization system according to any one of claims 1 to 9, characterized in that, The preheater includes a first preheater and a second preheater. A low-pressure steam source is connected to the second preheater and exchanges heat with the material in the second preheater. The condensate generated by the plate falling film evaporator and the circulating heater is connected to the first preheater through pipelines and exchanges heat with the material in the first preheater.

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