Two-stage falling film MVR (mechanical vapor recompression) evaporation device

Abstract

The utility model discloses a two-stage falling film MVR (Mechanical Vapor Recompression) evaporation device, which comprises a falling film heater comprising a first accommodating cavity comprising a heating area and a liquid storage area, the heating area is positioned in the middle of the first accommodating cavity, and the liquid storage area is positioned at the bottom of the first accommodating cavity; the heat exchanger is arranged in the heating area; the partition piece is arranged in the liquid storage area, one end of the partition piece and the heat exchanger are arranged at intervals, the other end of the partition piece is connected with the bottom of the liquid storage area so that the liquid storage area can be divided into a first liquid storage cavity and a second liquid storage cavity, the lower end of the first liquid storage cavity is used for communicating with an external first material inlet, and the lower end of the second liquid storage cavity is used for communicating with an external discharging pump; two ends of the first circulating pump are respectively communicated with the first liquid storage cavity and the heat exchanger; the two ends of the second circulating pump communicate with the second liquid storage cavity and the heat exchanger correspondingly. According to the utility model, the heat exchange area of the falling-film evaporator can be effectively reduced while the consumption of live steam is saved, and the purposes of reducing the volume of the falling-film heater and reducing the occupied area are achieved while the operation cost is reduced.

Description

Technical Field

[0001] The utility model relates to the field of falling film evaporation and concentration, in particular to a two-stage falling film MVR evaporation device. Background Art

[0002] Traditional falling film evaporation equipment primarily consists of a falling film heater and a falling film separator. The traditional falling film heater utilizes an evaporation system with live steam as the heat source. Conventional single-stage falling film MVR (Mechanical Vapor Recompression) evaporators also combine falling film and MVR evaporation technologies, utilizing compressed secondary steam from the system as a heat source for heating. Only a small amount of live steam needs to be replenished during operation, significantly reducing live steam consumption. However, the single-stage MVR evaporator has a large heat exchange area. This large heat exchange area is designed to meet the heat exchange requirements during the material heating and concentration process, but it also results in the entire falling film heater becoming very large. This large size inevitably requires a larger floor space for installation, increasing equipment investment costs.

[0003] In the face of the above problems, there is an urgent need for a new type of falling film evaporator that can save raw steam consumption while reducing the heat exchange area of ​​the falling film evaporator, thereby reducing the volume of the falling film heater and reducing the floor space. Utility Model Content

[0004] The purpose of this utility model is to solve the technical problem of a single-stage falling-film MVR evaporator requiring a large heat exchange area, resulting in a large equipment footprint. This utility model provides a two-stage falling-film MVR evaporator that effectively reduces the heat exchange area of ​​the falling-film evaporator, thereby reducing operating costs while also reducing the size and floor space of the falling-film heater.

[0005] In order to solve the above technical problems, the embodiment of the present utility model discloses a two-stage falling film MVR evaporation device, which includes:

[0006] A falling film heater, comprising:

[0007] a first accommodating chamber, the first accommodating chamber comprising a heating area and a liquid storage area, the heating area being located in the middle of the first accommodating chamber, and the liquid storage area being located at the bottom of the first accommodating chamber;

[0008] a heat exchanger, the heat exchanger being disposed in the heating zone;

[0009] a separator, the separator being provided in the liquid storage area, one end of the separator being spaced apart from the heat exchanger, and the other end of the separator being connected to the bottom of the liquid storage area, so as to separate the liquid storage area into a first liquid storage chamber and a second liquid storage chamber, wherein the lower end of the first liquid storage chamber is used to communicate with an external first material inlet, and the lower end of the second liquid storage chamber is used to communicate with an external discharge pump;

[0010] a first circulation pump, wherein two ends of the first circulation pump are respectively connected to the first liquid storage chamber and the heat exchanger;

[0011] A second circulation pump, wherein both ends of the second circulation pump are respectively connected to the second liquid storage chamber and the heat exchanger.

[0012] Using this technical solution, external material can flow sequentially through the first external material inlet, the first liquid storage chamber, the first circulation pump, the heat exchanger, and the first liquid storage chamber. After primary concentration, the external material (the material in the first liquid storage chamber) overflows and transfers to the secondary concentration area (the material in the second liquid storage chamber), where it flows sequentially through the first liquid storage chamber, the second liquid storage chamber, the second circulation pump, the heat exchanger, the second liquid storage chamber, and the external discharge pump.

[0013] External material enters the first liquid storage chamber through the first material inlet, then flows through the first circulation pump into the heat exchanger. Surrounded by the hotter secondary steam, the material continuously evaporates and concentrates in the heat exchanger before returning to the first liquid storage chamber. Due to the heating process within the heat exchanger, the material's properties undergo significant changes. The material returning to the first liquid storage chamber is now closer to saturation than when it initially entered. This is analogous to a glass of salt water: as it is heated and evaporated, the salt concentration in the water increases, bringing it closer to saturation.

[0014] The material in the second liquid storage chamber overflows from the upper end of the first liquid storage chamber. During this process, new material continues to flow into the lower end of the first liquid storage chamber and continuously mixes with the material that has already undergone certain changes in the first liquid storage chamber. Therefore, the material concentration in the second liquid storage chamber is higher than that in the first liquid storage chamber. At this point, it is important to mention an important characteristic of the material: boiling point rise. Boiling point rise is a common phenomenon in solutions. It refers to the fact that the boiling point of a solution increases above that of the pure solvent due to the presence of a solute. For example, if salt is added to pure water to form a brine solution, the boiling point of the brine solution will be higher than that of pure water. Moreover, the closer the material is to saturation, the higher its boiling point rise. Accordingly, for a given heating steam temperature during evaporation, the smaller the effective temperature difference it can provide.

[0015] For example, assuming the initial material has an evaporation temperature of 100°C, and the boiling point of the material in the first liquid storage chamber rises by 2°C, the temperature of the material in the first liquid storage chamber will be 102°C according to the principle of boiling point rise. If the boiling point of the material in the second liquid storage chamber rises by 5°C, the temperature of the material in the second liquid storage chamber will be 105°C. The temperature of the secondary steam used as the heating source is 112°C. Therefore, the effective temperature difference ΔT1 of the material in the first liquid storage chamber is 112°C - 102°C = 10°C, and the effective temperature difference ΔT2 of the material in the second liquid storage chamber is 112°C - 105°C = 7°C.

[0016] It can be concluded that the boiling point rise of the material in the second liquid storage chamber is higher than the boiling point rise of the material in the first liquid storage chamber. Accordingly, the effective temperature difference △T2 required for the evaporation of the material in the second liquid storage chamber is smaller than the effective temperature difference △T1 required for the evaporation of the material in the first liquid storage chamber. According to the formula S=Q / k△T (where S represents the heat exchange area, Q represents the heat load, k is the heat transfer coefficient, and △T is the effective temperature difference), under the same heat load Q, the smaller the effective temperature difference △T, the larger the heat exchange area S. The present application scheme sets a two-stage falling film (i.e., setting a first liquid storage chamber and a second liquid storage chamber), so that the effective temperature difference △T2 of the second liquid storage chamber is smaller than the effective temperature difference △T1 of the first liquid storage chamber. Compared with the traditional situation where the effective temperature difference △T is always △T2, the heat exchange area S is effectively reduced, thereby further reducing the volume of the equipment, thereby reducing the equipment footprint and reducing the equipment investment cost.

[0017] According to another specific embodiment of the present invention, the heat exchanger includes a first heat exchange tube and a second heat exchange tube, the two ends of the first heat exchange tube are respectively connected to the first circulation pump and the first liquid storage chamber, and the two ends of the second heat exchange tube are respectively connected to the second circulation pump and the second liquid storage chamber.

[0018] With this technical solution, external material can flow sequentially through the first material inlet, the first liquid storage chamber, the first circulation pump, the first heat exchange tube, and the first liquid storage chamber. After primary concentration, the external material overflows and is transferred to the secondary concentration area, where it flows sequentially through the first liquid storage chamber, the second liquid storage chamber, the second circulation pump, the second heat exchange tube, the second liquid storage chamber, and the discharge pump.

[0019] According to another specific embodiment of the present invention, the falling film heater includes a first liquid distribution pan, the first accommodating chamber includes a liquid distribution area, the liquid distribution area is located in the upper part of the first accommodating chamber, the first liquid distribution pan is arranged in the liquid distribution area, and the two ends of the first liquid distribution pan are respectively connected to the first circulation pump and the first heat exchange tube, so that external materials can flow through the first external material inlet, the first liquid storage chamber, the first circulation pump, the first liquid distribution pan, the first heat exchange tube and the first liquid storage chamber in sequence;

[0020] The falling film heater includes a second liquid distribution pan, which is arranged in the liquid distribution area. The two ends of the second liquid distribution pan are respectively connected to the second circulation pump and the second heat exchange tube. The external material can flow through the first liquid storage chamber, the second liquid storage chamber, the second circulation pump, the second liquid distribution pan, the second heat exchange tube, the second liquid storage chamber and the external discharge pump in sequence.

[0021] With the above technical solution, the material starts from the first circulation pump and is transported to the multiple first heat exchange tubes through the pipes connected to it. In the actual application scenario of industrial production, for cost-saving considerations, the diameter of the pipe connecting the first circulation pump and the multiple first heat exchange tubes is usually not designed to be too large. Due to the coverage range of the pipe, it is difficult for the material to completely cover all the first heat exchange tubes. Therefore, a first liquid distribution pan is set between the first circulation pump and the first heat exchange tubes to increase the surface area of ​​the material flowing at the first liquid distribution pan, overcome the problems caused by the previous pipe diameter limitation, and allow the material to enter the multiple first heat exchange tubes evenly.

[0022] Similarly, a second liquid distribution pan is set between the second circulation pump and the second heat exchange tube to increase the surface area of ​​the material flowing in the second liquid distribution pan, overcome the problem caused by the previous pipe diameter limitation, and the material can evenly enter multiple second heat exchange tubes.

[0023] According to another specific embodiment of the present invention, the lower end of the second liquid storage cavity is used to communicate with the external second material inlet, and the lower end of the first liquid storage cavity is used to communicate with the external discharge pump.

[0024] With the above technical solution, since the material concentration in the second liquid storage chamber is higher than that in the first liquid storage chamber, the material concentration in the second heat exchange tube is also higher than that in the first heat exchange tube. During the operation of a two-stage falling-film MVR evaporator, as the material passes through the second heat exchange tube, some of it inevitably adheres to the inner wall of the second heat exchange tube. This adhesion phenomenon becomes more severe over time. Just like scale gradually accumulating on the inner wall of a water pipe, if this continues for a long time, the adhered material will accumulate, eventually completely blocking the passages in the second heat exchange tube. Over time, this can even cause the two-stage falling-film MVR evaporator to cease operation.

[0025] In addition, since the discharge pump is only used for discharging materials on the side with higher concentration, in the present application, the lower end of the second liquid storage chamber is designed to be connected to the second material inlet of the outside world, and the lower end of the first liquid storage chamber is designed to be connected to the discharge pump of the outside world. After the two-stage falling film MVR evaporation device has been running continuously for a period of time, the material entry path and discharge path can be changed. The material no longer enters from the first material inlet, but enters the second liquid storage chamber through the second material inlet, and is discharged from the first liquid storage chamber through the discharge pump. In this case, the second liquid storage chamber is equivalent to playing the role of a "new liquid storage chamber". Since the concentration of the material entering from the second material inlet is low, when these low-concentration materials flow from the "new liquid storage chamber" to the second heat exchange tube, they can flush out the old material attached to the second heat exchange tube, thereby solving the problem caused by material attachment.

[0026] By arranging the first liquid storage chamber to be connected to the second material inlet of the outside, or the second liquid storage chamber to be connected to the second material inlet of the outside, the feeding position can be switched to prevent the first heat exchange tube or the second heat exchange tube from being blocked, thereby ensuring that the two-stage falling film MVR evaporation device can operate continuously and stably.

[0027] According to another specific embodiment of the present invention, the two-stage falling film MVR evaporation device includes a falling film separator and a falling film compressor, and the two ends of the falling film compressor are respectively connected to the falling film separator and the heating zone, and the secondary steam evaporated from the external material can flow through the upper end of the first liquid storage chamber, the upper end of the second liquid storage chamber, the falling film separator, the falling film compressor and the heating zone in sequence.

[0028] With this technical solution, secondary steam generated by evaporating the external material exits the upper ends of the first and second liquid storage chambers and passes through a falling film separator for defoaming. This defoamed secondary steam then enters a falling film compressor, where it is compressed. As the compression process progresses, the temperature of the secondary steam gradually increases, and its internal energy also increases accordingly.

[0029] The heated secondary steam then enters the heating zone, which is the shell side of the heat exchanger (i.e., the outside of the first and second heat exchange tubes), providing heat to the first and second heat exchange tubes, allowing the material to continuously evaporate and concentrate within the heat exchange tubes. This recycling of secondary steam as a heat source not only improves energy efficiency but also reduces dependence on external energy sources.

[0030] According to another specific embodiment of the present invention, the falling film separator includes a connected second accommodating chamber and a tangential air inlet, and the tangential air inlet is connected to the upper end of the second liquid storage chamber, so the tangential air inlet is used for the secondary steam from the outside to enter the second accommodating chamber tangentially; the falling film separator includes a folded plate demister and a wire mesh demister arranged in the second accommodating chamber, and the tangential air inlet, the folded plate demister and the wire mesh demister are arranged in sequence at intervals.

[0031] With the above-mentioned technical solution, the secondary steam generated by the evaporation of the external material carries with it some material foam before entering the second holding chamber. When the secondary steam carries the material foam tangentially into the second holding chamber, a high-speed rotating flow field is formed in the second holding chamber. This rotational motion subjects the fluid to the action of centrifugal force. The physical properties of material foam and steam differ. Generally speaking, the density of material foam is greater than that of steam. Under the same rotation conditions, the material foam with a larger mass is subjected to a greater centrifugal force. Therefore, the material foam will be thrown to the edge area of ​​the falling film separator, while the steam, due to the smaller centrifugal force it is subjected to, will tend to gather near the center of rotation or form a relatively independent steam flow layer inside the falling film separator. This separation method based on centrifugal force is like a rotating "sieve". According to the difference in material mass, the material foam and steam are initially separated to achieve the effect of first-stage defoaming.

[0032] In addition, in the falling film separator, the secondary steam will also pass through the folded plate demister to achieve the second stage of defoaming and the wire mesh demister to achieve the third stage of defoaming. Compared with the existing technology that relies only on a single defoaming method, the three-stage defoaming in the present application scheme has a better defoaming effect.

[0033] In the present application, the secondary steam evaporated by the external material passes through the falling film compressor and serves as the heat source for the first heat exchange tube and the second heat exchange tube, which can effectively save the raw steam consumption.

[0034] According to another specific embodiment of the present invention, the falling film separator includes a plurality of spray parts, one end of the plurality of spray parts is used to communicate with an external water pump, and the other end of the plurality of spray parts is arranged in the second accommodating cavity. The other end of a part of the plurality of spray parts is arranged toward the folding plate demister, and the other end of another part of the plurality of spray parts is arranged toward the wire mesh demister.

[0035] With the above technical solution, when the secondary steam passes through the folded plate demister and the wire mesh demister, some entrained material foam may adhere to the folded plate demister and the wire mesh demister. This may cause clogging of the folded plate demister and the wire mesh demister over time, affecting the defoaming effect. Therefore, the spray section is set towards the folded plate demister and the wire mesh demister to flush away the liquid foam adhering to the folded plate demister and the wire mesh demister.

[0036] According to another specific embodiment of the present invention, the falling film separator includes a pressure sensor arranged in the second accommodating chamber, the falling film separator also includes an outlet, the tangential air inlet, the second accommodating chamber and the outlet are connected in sequence, the pressure sensor is electrically connected to the multiple spray parts, the pressure sensor is used to detect the pressure difference between the tangential air inlet and the outlet, and the multiple spray parts are used to start when the pressure difference is higher than a set value.

[0037] Using the above technical solution, during the defoaming process of the falling film separator, if the pressure difference between the tangential air inlet (i.e., the inlet of the secondary steam) and the outlet (i.e., the outlet of the secondary steam) is greater than the set value (the set value is determined by the specific situation on site, for example, it can be 500pa), it means that the folding plate demister or the wire mesh demister is blocked at this time, and the spray part will start to flush the folding plate demister and the wire mesh demister.

[0038] According to another specific embodiment of the present invention, the falling film separator includes a timer, which is electrically connected to the multiple spray parts. The timer is used to start the multiple spray parts every time a set time period passes.

[0039] By adopting the above technical solution, the flushing of the folding plate demister and the wire mesh demister can also be controlled by a timer. For example, every hour, the folding plate demister and the wire mesh demister are flushed for 60 seconds to prevent the folding plate demister and the wire mesh demister from being blocked.

[0040] According to another specific embodiment of the present invention, the two-stage falling film MVR evaporation device includes a condensed water collection part, which includes a connected condensed water tank and a condensed water pump. The condensed water tank is connected to the heating zone. The condensed water tank is used to collect condensed water on the outer surfaces of the first heat exchange tube and the second heat exchange tube, and the condensed water pump is used to discharge the condensed water. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 A schematic diagram of a two-stage falling film MVR evaporation device according to an embodiment of the present invention is shown.

[0042] Figure 2 A schematic diagram of a falling film separator according to an embodiment of the present invention is shown.

[0043] Description of Reference Numerals

[0044] Falling film heater 10;

[0045] First accommodating chamber 11; heating area 111; liquid storage area 112; liquid distribution area 113; partition 12; first circulation pump 13; second circulation pump 14; first liquid storage chamber 15; second liquid storage chamber 16; first liquid distribution tray 17; second liquid distribution tray 18;

[0046] Falling film separator 20;

[0047] Second accommodating chamber 21; tangential air inlet 22; folded plate demister 23; wire mesh demister 24; spray portion 25; outlet 26;

[0048] Falling film compressor 30;

[0049] Condensate collecting portion 40; condensate tank 41; condensate pump 42;

[0050] First material import 100;

[0051] Discharge pump 200;

[0052] The second material is imported 300. DETAILED DESCRIPTION

[0053] The following is an explanation of the implementation of the present invention by means of specific specific embodiments. Those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. Although the description of the present invention will be introduced in conjunction with the preferred embodiment, this does not mean that the features of this utility model are limited to this implementation. On the contrary, the purpose of introducing the utility model in conjunction with the implementation is to cover other options or modifications that may be extended based on the claims of the present invention. In order to provide an in-depth understanding of the present invention, the following description will contain many specific details. The present invention can also be implemented without using these details. In addition, in order to avoid confusion or blurring the focus of the present invention, some specific details will be omitted in the description. It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments can be combined with each other.

[0054] It should be noted that in this specification, similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, it does not need to be further defined or explained in subsequent drawings.

[0055] In the description of this embodiment, it should be noted that the terms "upper", "lower", "inner", "bottom", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, or are the orientations or positional relationships in which the utility model product is usually placed when in use. They are only for the convenience of describing the utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, they cannot be understood as a limitation on the utility model.

[0056] The terms “first”, “second”, etc. are only used for distinguishing descriptions and should not be understood as indicating or implying relative importance.

[0057] In the description of this embodiment, it should be noted that, unless otherwise specified or limited, the terms "disposed," "connected," and "connected" should be understood broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; mechanical connections or electrical connections; direct connections or indirect connections through an intermediate medium; and internal connections between two components. Those skilled in the art will understand the specific meanings of the above terms in this embodiment based on specific circumstances.

[0058] In order to make the purpose, technical solutions and advantages of the present invention more clear, the embodiments of the present invention will be described in further detail below with reference to the accompanying drawings.

[0059] refer to Figure 1 and Figure 2 An embodiment of the present application provides a two-stage falling film MVR evaporation device including a falling film heater 10 , which includes a first accommodating chamber 11 , a heat exchanger (not shown in the figure), a partition 12 , a first circulation pump 13 and a second circulation pump 14 .

[0060] The first accommodating chamber 11 includes a heating area 111 and a liquid storage area 112 . The heating area 111 is located in the middle of the first accommodating chamber 11 , and the liquid storage area 112 is located at the bottom of the first accommodating chamber 11 . A heat exchanger (not shown) is provided in the heating area 111 .

[0061] A separator 12 is disposed within the liquid storage area 112. One end of the separator 12 is spaced from the heat exchanger, and the other end of the separator 12 is connected to the bottom of the liquid storage area 112, thereby dividing the liquid storage area 112 into a first liquid storage chamber 15 and a second liquid storage chamber 16. The lower end of the first liquid storage chamber 15 is connected to the external first material inlet 100, while the lower end of the second liquid storage chamber 16 is connected to the external discharge pump 200. The first circulating pump 13 is connected to the first liquid storage chamber 15 and the heat exchanger at both ends, while the second circulating pump 14 is connected to the second liquid storage chamber 16 and the heat exchanger at both ends.

[0062] Using the above technical solution, external material can flow sequentially through the external first material inlet 100, the first liquid storage chamber 15, the first circulation pump 13, the heat exchanger, and the first liquid storage chamber 15. After the primary concentration, the external material (the material in the first liquid storage chamber 15) overflows and is transferred to the secondary concentration area (the material in the second liquid storage chamber 16), and then flows sequentially through the first liquid storage chamber 15, the second liquid storage chamber 16, the second circulation pump 14, the heat exchanger, the second liquid storage chamber 16, and the external discharge pump 200.

[0063] External material enters the heat exchanger through the first material inlet 100 and then flows through the first circulation pump 13. Surrounding the heat exchanger is the hotter secondary steam, causing the material to continuously evaporate and concentrate within the heat exchanger before returning to the first liquid storage chamber 15. Due to the heating process within the heat exchanger, the material's properties undergo significant changes. The material returning to the first liquid storage chamber 15 is now closer to saturation than the initial material. This is like a glass of salt water: as it is heated and evaporated, the salt concentration in the water increases, bringing it closer to saturation.

[0064] The material in the second liquid storage chamber 16 overflows from the upper end of the first liquid storage chamber 15. During this process, new material continues to enter the lower end of the first liquid storage chamber 15 and continuously mixes with the material that has already undergone certain changes in the first liquid storage chamber 15. Therefore, the material concentration in the second liquid storage chamber 16 is higher than that in the first liquid storage chamber 15. At this point, it is important to mention an important characteristic of the material - boiling point rise. Boiling point rise is a common phenomenon in solutions. It refers to the fact that the boiling point of a solution is higher than that of the pure solvent due to the presence of a solute. For example, if salt is added to pure water to form a brine solution, the boiling point of the brine solution will be higher than that of pure water. Moreover, the closer the material is to saturation, the higher its boiling point rise. Accordingly, when the temperature of the heating steam during evaporation is constant, the smaller the effective temperature difference it can provide.

[0065] For example, assuming the evaporation temperature of the initial material is 100°C, and the boiling point of the material in the first liquid storage chamber 15 rises by 2°C, based on the principle of boiling point rise, the temperature of the material in the first liquid storage chamber 15 is 102°C. If the boiling point of the material in the second liquid storage chamber 16 rises by 5°C, the temperature of the material in the second liquid storage chamber 16 is 105°C. The temperature of the secondary steam serving as the heating source is 112°C. Therefore, the effective temperature difference ΔT1 of the material in the first liquid storage chamber 15 is 112°C - 102°C = 10°C, and the effective temperature difference ΔT2 of the material in the second liquid storage chamber 16 is 112°C - 105°C = 7°C.

[0066] It can be seen from this that the boiling point rise of the material in the second liquid storage chamber 16 is higher than the boiling point rise of the material in the first liquid storage chamber 15. Accordingly, the effective temperature difference ΔT2 required for the evaporation of the material in the second liquid storage chamber 16 is smaller than the effective temperature difference ΔT1 required for the evaporation of the material in the first liquid storage chamber 15. According to the formula S=Q / kΔT (where S represents the heat exchange area, Q represents the heat load, k is the heat transfer coefficient, and ΔT is the effective temperature difference), under the same heat load Q, the smaller the effective temperature difference ΔT, the larger the heat exchange area S. The present application scheme sets a two-stage falling film (i.e., setting a first liquid storage chamber 15 and a second liquid storage chamber 16), so that the effective temperature difference ΔT2 of the second liquid storage chamber 16 is smaller than the effective temperature difference ΔT1 of the first liquid storage chamber 15. Compared with the traditional situation where the effective temperature difference ΔT is always ΔT2, the heat exchange area S is effectively reduced, thereby further reducing the volume of the equipment, thereby reducing the equipment footprint and reducing the equipment investment cost.

[0067] In some possible implementations, reference Figure 1 and Figure 2 The heat exchanger includes a first heat exchange tube (not shown in the figure) and a second heat exchange tube (not shown in the figure). The two ends of the first heat exchange tube are respectively connected to the first circulation pump 13 and the first liquid storage chamber 15, and the two ends of the second heat exchange tube are respectively connected to the second circulation pump 14 and the second liquid storage chamber 16.

[0068] Using the above technical solution, external materials can flow sequentially through the first material inlet 100, the first liquid storage chamber 15, the first circulation pump 13, the first heat exchange tube, and the first liquid storage chamber 15. After the primary concentration, the external materials overflow and are transferred to the secondary concentration area, flowing sequentially through the first liquid storage chamber 15, the second liquid storage chamber 16, the second circulation pump 14, the second heat exchange tube, the second liquid storage chamber 16, and the discharge pump 200.

[0069] In some possible implementations, reference Figure 1 and Figure 2 The falling film heater 10 includes a first liquid distribution pan 17. The first accommodating chamber 11 includes a liquid distribution area 113 located above the first accommodating chamber 11. The first liquid distribution pan 17 is disposed within the liquid distribution area 113. The first liquid distribution pan 17 is connected to the first circulation pump 13 and the first heat exchange tube at both ends, allowing external material to flow sequentially through the first material inlet 100, the first liquid storage chamber 15, the first circulation pump 13, the first liquid distribution pan 17, the first heat exchange tube, and the first liquid storage chamber 15.

[0070] The falling film heater 10 includes a second liquid distribution pan 18, which is located in the liquid distribution area 113. The two ends of the second liquid distribution pan 18 are connected to the second circulation pump 14 and the second heat exchange tube, respectively. External material can flow sequentially through the first liquid storage chamber 15, the second liquid storage chamber 16, the second circulation pump 14, the second liquid distribution pan 18, the second heat exchange tube, the second liquid storage chamber 16, and the external discharge pump 200.

[0071] With the above technical solution, the material starts from the first circulation pump 13 and is transported to the multiple first heat exchange tubes through the pipes connected thereto. In the actual application scenario of industrial production, for cost-saving considerations, the diameter of the pipe connecting the first circulation pump 13 and the multiple first heat exchange tubes is usually not designed to be too large. Limited by the coverage range of the pipe, it is difficult for the material to completely cover all the first heat exchange tubes. Therefore, a first liquid distribution pan 17 is set between the first circulation pump 13 and the first heat exchange tubes to increase the surface area of ​​the material flowing at the first liquid distribution pan 17, overcome the problems caused by the previous pipe diameter limitation, and allow the material to enter the multiple first heat exchange tubes evenly.

[0072] Similarly, a second liquid distribution pan 18 is provided between the second circulation pump 14 and the second heat exchange tube to increase the surface area of ​​the material flowing in the second liquid distribution pan 18, thereby overcoming the problem caused by the previous tube diameter limitation and allowing the material to evenly enter the multiple second heat exchange tubes.

[0073] In some possible implementations, reference Figure 1 and Figure 2 The lower end of the second liquid storage chamber 16 is used to communicate with the second material inlet 300 of the outside, and the lower end of the first liquid storage chamber 15 is used to communicate with the external discharge pump 200.

[0074] With the above technical solution, since the material concentration in the second liquid storage chamber 16 is higher than that in the first liquid storage chamber 15, the material concentration in the second heat exchange tube is correspondingly higher than that in the first heat exchange tube. During the operation of the two-stage falling-film MVR evaporator, as the material passes through the second heat exchange tube, some of the material inevitably adheres to the inner wall of the second heat exchange tube. This adhesion phenomenon becomes more severe over time. Just like scale gradually accumulating on the inner wall of a water pipe, if this continues for a long time, the adhered material will accumulate, eventually completely blocking the passages in the second heat exchange tube. Over time, this may even cause the two-stage falling-film MVR evaporator to cease operation.

[0075] Furthermore, because the discharge pump is only used to discharge material from the side with higher concentration, in this application, the lower end of the second liquid storage chamber 16 is designed to communicate with the external second material inlet 300, and the lower end of the first liquid storage chamber 15 is designed to communicate with the external discharge pump 200. After the two-stage falling-film MVR evaporator has been operating continuously for a period of time, the material entry path can be changed. Instead of entering through the first material inlet 100, the material enters the second liquid storage chamber 16 through the second material inlet 300 and is discharged from the first liquid storage chamber 15 via the discharge pump 200. In this case, the second liquid storage chamber 16 acts as a "new liquid storage chamber." Because the material entering through the second material inlet 300 is of lower concentration, when this low-concentration material flows from the "new liquid storage chamber" to the second heat exchange tubes, it can flush out the old material adhering to the second heat exchange tubes, thus completely resolving the problem caused by material adhesion.

[0076] By providing the first liquid storage chamber 15 in communication with the second material inlet 300 from the outside, or by providing the second liquid storage chamber 16 in communication with the second material inlet 300 from the outside, the feed position can be switched, thereby preventing the first heat exchange tube or the second heat exchange tube from being blocked, thereby ensuring the continuous and stable operation of the two-stage falling film MVR evaporation device.

[0077] In some possible implementations, reference Figure 1 and Figure 2 The two-stage falling film MVR evaporation device includes a falling film separator 20 and a falling film compressor 30. The two ends of the falling film compressor 30 are respectively connected to the falling film separator 20 and the heating zone 111. The secondary steam evaporated from the external material can flow through the upper end of the first liquid storage chamber 15, the upper end of the second liquid storage chamber 16, the falling film separator 20, the falling film compressor 30 and the heating zone 111 in sequence.

[0078] Using this technical solution, secondary vapor generated by evaporation of the external material exits the upper ends of the first and second liquid storage chambers 15, 16, and passes through the falling film separator 20 for defoaming. The defoamed secondary vapor then enters the falling film compressor 30, where it is compressed. As the compression process progresses, the temperature of the secondary vapor gradually increases, and its internal energy also increases accordingly.

[0079] The heated secondary steam then enters heating zone 111, the shell side of the heat exchanger (i.e., the exterior of the first and second heat exchange tubes), providing heat to the first and second heat exchange tubes, allowing the material to continuously evaporate and concentrate within the tubes. This recycling of secondary steam as a heat source not only improves energy efficiency but also reduces dependence on external energy sources.

[0080] In some possible implementations, reference Figure 1and Figure 2 The falling film separator 20 includes a second accommodating chamber 21 and a tangential air inlet 22, which are connected to the upper end of the second liquid storage chamber 16. The tangential air inlet 22 is used to allow external secondary steam to enter the second accommodating chamber 21 tangentially. The falling film separator 20 includes a folded plate demister 23 and a wire mesh demister 24 disposed within the second accommodating chamber 21. The tangential air inlet 22, folded plate demister 23, and wire mesh demister 24 are arranged in sequence.

[0081] By adopting the above technical solution, the secondary steam evaporated from the external material will carry some material foam before entering the second accommodating chamber 21. When the secondary steam carries the material foam tangentially into the second accommodating chamber 21, a high-speed rotating flow field will be formed in the second accommodating chamber 21. This rotational motion causes the fluid to be affected by centrifugal force. There are differences in the physical properties of material foam and steam. Generally speaking, the density of material foam is greater than that of steam. Under the same rotation conditions, the material foam with a larger mass is subjected to a greater centrifugal force. Therefore, the material foam will be thrown to the edge area of ​​the falling film separator 20, while the steam will tend to gather near the center of rotation or form a relatively independent steam flow layer inside the falling film separator 20 due to the smaller centrifugal force it is subjected to. This separation method based on centrifugal force is like a rotating "sieve". According to the different mass of the materials, the material foam and steam are preliminarily separated to achieve the effect of first-stage defoaming.

[0082] In addition, in the falling film separator 20, the secondary steam will also pass through the folded plate demister 23 to achieve the second stage of defoaming, and pass through the wire mesh demister 24 to achieve the third stage of defoaming. Compared with the prior art that relies only on a single defoaming method, the three-stage defoaming in the present application scheme has a better defoaming effect.

[0083] In the present application, the secondary steam evaporated by the external material passes through the falling film compressor 30 and serves as the heat source for the first heat exchange tube and the second heat exchange tube, which can effectively save the raw steam consumption.

[0084] In some possible implementations, reference Figure 1 and Figure 2 The falling film separator 20 includes two spray parts 25, one end of the two spray parts 25 is used to communicate with an external water pump (not shown in the figure), and the other end of the two spray parts 25 is arranged in the second accommodating cavity 21, the other end of one of the spray parts 25 is arranged toward the folded plate demister 23, and the other end of the other spray part 25 is arranged toward the wire mesh demister 24.

[0085] With the above technical solution, when the secondary steam passes through the folded plate demister 23 and the wire mesh demister 24, some entrained material foam may adhere to the folded plate demister 23 and the wire mesh demister 24. This may cause clogging of the folded plate demister 23 and the wire mesh demister 24 over time, affecting the defoaming effect. Therefore, a spray portion 25 is provided facing the folded plate demister 23 and the wire mesh demister 24 to flush away the liquid foam adhering to the folded plate demister 23 and the wire mesh demister 24.

[0086] It should be noted that the embodiment of the present application does not impose any specific limitation on the number of the spray parts 25. For example, in other possible implementations, the number of the spray parts 25 can also be three, four, etc.

[0087] In some possible implementations, reference Figure 1 and Figure 2 The falling film separator 20 includes a pressure sensor (not shown) disposed within the second accommodating chamber 21. The falling film separator 20 also includes an outlet 26. The tangential air inlet 22, the second accommodating chamber 21, and the outlet 26 are sequentially connected. The pressure sensor is electrically connected to two spray sections 25. The pressure sensor is used to detect the pressure difference between the tangential air inlet 22 and the outlet 26. The two spray sections 25 are configured to activate when the pressure difference exceeds a set value.

[0088] Using the above technical solution, during the defoaming process of the falling film separator 20, if the pressure difference between the tangential air inlet 22 (i.e., the inlet of the secondary steam) and the outlet 26 (i.e., the outlet of the secondary steam) is greater than the set value (the set value is determined by the specific situation on site, for example, it can be 500 Pa), it means that the folding plate demister 23 or the wire mesh demister 24 is blocked at this time, and the spray part 25 will start to flush the folding plate demister 23 and the wire mesh demister 24.

[0089] It should be noted that the embodiment of the present application does not impose any specific restrictions on the set value of the pressure difference. For example, in other possible implementations, the set value of the pressure difference can also be 450Pa, 550Pa, etc. The set value of the pressure difference depends on the specific situation.

[0090] In some possible implementations, reference Figure 1 and Figure 2 The falling film separator 20 includes a timer (not shown in the figure), which is electrically connected to the two spray parts 25. The timer is used to start the two spray parts 25 every time a set time period passes.

[0091] By adopting the above technical solution, the flushing of the folding plate demister 23 and the wire mesh demister 24 can also be controlled by a timer. For example, every hour, the folding plate demister 23 and the wire mesh demister 24 are flushed for 60 seconds to prevent the folding plate demister 23 and the wire mesh demister 24 from being blocked.

[0092] It should be noted that the specific duration of the set time period is not specifically limited in the present embodiment. For example, in other possible embodiments, the set time period can be 50 minutes, 75 minutes, etc., and the specific duration of the set time period is determined by the specific situation. The flushing time is not specifically limited in the present embodiment. For example, in other possible embodiments, the flushing time can be 55 seconds, 65 seconds, etc., and the flushing time is determined by the specific situation.

[0093] In some possible implementations, reference Figure 1 and Figure 2 The two-stage falling film MVR evaporation device includes a condensed water collection part 40, which includes a connected condensed water tank 41 and a condensed water pump 42. The condensed water tank 41 is connected to the heating area 111. The condensed water tank 41 is used to collect condensed water on the outer surfaces of the first heat exchange tube and the second heat exchange tube. The condensed water pump 42 is used to discharge the condensed water.

[0094] Although the present invention has been illustrated and described with reference to certain preferred embodiments of the present invention, it should be understood by those skilled in the art that the above description is provided to further illustrate the present invention in conjunction with specific embodiments, and that the present invention should not be construed as being limited to these descriptions. Those skilled in the art may make various changes in form and detail, including simple deductions or substitutions, without departing from the spirit and scope of the present invention.

Claims

1. A two-stage falling film MVR evaporation device, characterized in that: The two-stage falling film MVR evaporation device comprises: A falling film heater, comprising: a first accommodating chamber, the first accommodating chamber comprising a heating area and a liquid storage area, the heating area being located in the middle of the first accommodating chamber, and the liquid storage area being located at the bottom of the first accommodating chamber; a heat exchanger, the heat exchanger being disposed in the heating zone; a separator, the separator being provided in the liquid storage area, one end of the separator being spaced apart from the heat exchanger, and the other end of the separator being connected to the bottom of the liquid storage area, so as to separate the liquid storage area into a first liquid storage chamber and a second liquid storage chamber, wherein the lower end of the first liquid storage chamber is used to communicate with an external first material inlet, and the lower end of the second liquid storage chamber is used to communicate with an external discharge pump; a first circulation pump, wherein two ends of the first circulation pump are respectively connected to the first liquid storage chamber and the heat exchanger; A second circulation pump, wherein both ends of the second circulation pump are respectively connected to the second liquid storage chamber and the heat exchanger.

2. The two-stage falling film MVR evaporation device according to claim 1, characterized in that: The heat exchanger includes a first heat exchange tube and a second heat exchange tube. Both ends of the first heat exchange tube are respectively connected to the first circulation pump and the first liquid storage chamber. Both ends of the second heat exchange tube are respectively connected to the second circulation pump and the second liquid storage chamber.

3. The two-stage falling film MVR evaporation device according to claim 2, characterized in that: The falling film heater includes a first liquid distribution pan, the first accommodating chamber includes a liquid distribution area, the liquid distribution area is located in the upper part of the first accommodating chamber, the first liquid distribution pan is arranged in the liquid distribution area, and the two ends of the first liquid distribution pan are respectively connected to the first circulation pump and the first heat exchange tube, so that external materials can flow through the first external material inlet, the first liquid storage chamber, the first circulation pump, the first liquid distribution pan, the first heat exchange tube and the first liquid storage chamber in sequence; The falling film heater includes a second liquid distribution pan, which is arranged in the liquid distribution area. The two ends of the second liquid distribution pan are respectively connected to the second circulation pump and the second heat exchange tube. The external material can flow through the first liquid storage chamber, the second liquid storage chamber, the second circulation pump, the second liquid distribution pan, the second heat exchange tube, the second liquid storage chamber and the external discharge pump in sequence.

4. The two-stage falling film MVR evaporation device according to claim 1, characterized in that: The lower end of the second liquid storage cavity is used to communicate with an external second material inlet, and the lower end of the first liquid storage cavity is used to communicate with an external discharge pump.

5. The two-stage falling film MVR evaporation device according to claim 1, characterized in that: The two-stage falling film MVR evaporation device includes a falling film separator and a falling film compressor. The two ends of the falling film compressor are respectively connected to the falling film separator and the heating zone. The secondary steam evaporated by the external material can flow through the upper end of the first liquid storage chamber, the upper end of the second liquid storage chamber, the falling film separator, the falling film compressor and the heating zone in sequence.

6. The two-stage falling film MVR evaporation device according to claim 5, characterized in that: The falling film separator includes a connected second accommodating chamber and a tangential air inlet, and the tangential air inlet is connected to the upper end of the second liquid storage chamber, so the tangential air inlet is used for the secondary steam from the outside to enter the second accommodating chamber tangentially; the falling film separator includes a folded plate demister and a wire mesh demister arranged in the second accommodating chamber, and the tangential air inlet, the folded plate demister and the wire mesh demister are arranged in sequence at intervals.

7. The two-stage falling film MVR evaporation device according to claim 6, characterized in that: The falling film separator includes a plurality of spray parts, one end of the plurality of spray parts is used to communicate with an external water pump, and the other end of the plurality of spray parts is arranged in the second accommodating cavity. The other end of a part of the plurality of spray parts is arranged toward the folded plate demister, and the other end of another part of the plurality of spray parts is arranged toward the wire mesh demister.

8. The two-stage falling film MVR evaporation device according to claim 7, characterized in that: The falling film separator includes a pressure sensor arranged in the second accommodating chamber, and the falling film separator also includes an outlet. The tangential air inlet, the second accommodating chamber and the outlet are connected in sequence. The pressure sensor is electrically connected to the multiple spray parts. The pressure sensor is used to detect the pressure difference between the tangential air inlet and the outlet. The multiple spray parts are used to start when the pressure difference is higher than a set value.

9. The two-stage falling film MVR evaporation device according to claim 7, characterized in that: The falling film separator includes a timer, which is electrically connected to the multiple spray parts. The timer is used to start the multiple spray parts every time a set time period passes.

10. The two-stage falling film MVR evaporation device according to claim 3, characterized in that: The two-stage falling film MVR evaporation device includes a condensed water collection part, which includes a connected condensed water tank and a condensed water pump. The condensed water tank is connected to the heating zone. The condensed water tank is used to collect condensed water on the outer surfaces of the first heat exchange tube and the second heat exchange tube. The condensed water pump is used to discharge the condensed water.

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