A falling film evaporator

Abstract

This utility model belongs to the field of coal chemical wastewater treatment, specifically relating to a falling film evaporator, including a multi-effect heater and a multi-effect evaporator separator. Each effect evaporator separator includes a vacuum evaporator, a feed inlet, a U-shaped tube, several support rods, a conical cap, and a support frame. The feed inlet is located on the side wall of the vacuum evaporator. The U-shaped tube is located inside the vacuum evaporator, with its inlet end connected to the feed inlet and its outlet end in an inverted trapezoidal shape. Several support rods are located at the top of the outlet end of the U-shaped tube, and the conical cap is located on the top of the support rods, submerged in the concentrated liquid inside the vacuum evaporator. The support frame is located inside the vacuum evaporator, with one end connected to the inner side wall of the vacuum evaporator and the other end connected to the outlet end of the U-shaped tube. This utility model not only solves the problem of mist entrainment in traditional devices but also provides a falling film evaporator separator with uniform heat exchange, stable operation, no mist entrainment, and labor savings.

Description

Technical Field

[0001] This utility model belongs to the field of coal chemical wastewater treatment, specifically relating to a falling film evaporator. Background Technology

[0002] Currently, my country attaches great importance to ecological and environmental protection, adheres to the path of green and sustainable development, and recognizes that protecting the ecological environment is everyone's responsibility. Modern chemical wastewater treatment processes are crucial for protecting the ecological environment, achieving wastewater recycling, and near-zero discharge. Modern chemical industries primarily use coal as raw material and employ advanced technologies to produce essential materials for human survival, but this generates large amounts of highly polluting wastewater, causing a significant impact on the ecological environment. This is particularly acute in areas with relatively scarce water resources, where water pollution is especially prominent. This places higher technical demands on the improvement and optimization of wastewater treatment technologies in the modern chemical industry, as well as on achieving zero discharge.

[0003] Modern chemical wastewater treatment processes primarily utilize a combination of biochemical treatment, deep oxidation, reclaimed water reuse, membrane concentration, and multi-effect evaporation crystallization to achieve near-zero wastewater discharge. The multi-effect evaporation crystallization process, as the final stage in modern chemical wastewater treatment, plays a crucial role. In the falling film evaporator, live steam enters the system from the first effect, secondary steam from the first effect enters the second effect, and secondary steam from the second effect enters the third effect. Wastewater enters the system from the first effect, is concentrated, then transferred to the second effect, further concentrated, and finally transferred to the third effect, where it crystallizes into salt within the third-effect evaporation crystallization chamber. However, maintaining stable control of the heat exchange, liquid level, and vacuum level of the highly concentrated liquid within the third-effect evaporation crystallization chamber is extremely difficult. Problems such as uneven heat exchange, excessively high or low liquid levels, and mismatches with vacuum levels can easily lead to violent boiling within the chamber, fluctuating liquid levels, mist entrainment, and even vaporization of the highly concentrated liquid, polluting the circulating water. Meanwhile, due to the poor operational stability and low throughput of the device, it not only consumes a large amount of manpower but also easily affects the operational balance of the water system. Therefore, it is urgent to improve the falling film evaporator to solve the above-mentioned technical problems. Summary of the Invention

[0004] To address the shortcomings of the existing methods, this invention provides a falling film evaporator that offers uniform heat exchange, stable operation, no mist entrainment, and saves manpower, thereby solving the aforementioned technical problems and achieving zero wastewater discharge, especially zero discharge of chemical wastewater with high salt content.

[0005] This utility model provides a falling film evaporation device, including a first-effect evaporation unit, a second-effect evaporation unit, and a third-effect evaporation unit. The first-effect evaporation unit includes a first-effect heater and a first-effect evaporator separator; the second-effect evaporation unit includes a second-effect heater and a second-effect evaporator separator; and the third-effect evaporation unit includes a third-effect heater and a third-effect evaporator separator. The bottom inlets of the first-effect heater, the second-effect heater, and the third-effect heater are sequentially connected, wherein:

[0006] Each effect evaporator / separator includes a vacuum evaporator, a feed inlet, a U-shaped tube, several support rods, a conical cap, and a support frame. The feed inlet is located on the side wall of the vacuum evaporator, and its installation height is higher than the liquid level of the concentrate inside the vacuum evaporator. The U-shaped tube is located inside the vacuum evaporator and includes a first tube body, a bend, and a second tube body connected in sequence. The end of the first tube body away from the bend is connected to the feed inlet, and the end of the second tube body away from the bend is inverted trapezoidal in shape, i.e., the diameter of the U-shaped tube outlet is greater than the diameter of the U-shaped tube body / the diameter at the inlet. Several support rods are located at the top of the end of the second tube body away from the bend, and the conical cap is located at the top of the support rods. The support frame is located inside the vacuum evaporator, with one end connected to the inner side wall of the vacuum evaporator and the other end connected to the end of the second tube body away from the bend. The first tube body is partially immersed in the concentrate inside the vacuum evaporator, and the bend, the second tube body, and the conical cap are completely immersed in the concentrate inside the vacuum evaporator.

[0007] Preferably, the U-shaped tube, several support rods, conical tube cap, and support frame are made of high-temperature corrosion resistant materials.

[0008] Preferably, the first tube immersed in the concentrate in the vacuum evaporator is provided with three sets of transverse openings. The three sets of transverse openings are provided on three sides of the first tube away from the inner wall of the vacuum evaporator. That is, except for the side near the inner wall of the vacuum evaporator where the feed inlet is provided, the other three sides are provided with transverse openings and are evenly distributed at equal intervals on the three sides. Each set of transverse openings includes several small holes on the same vertical line.

[0009] Preferably, an observation window is also provided on the outer wall of the vacuum evaporator to observe the height of the concentrated liquid inside the vacuum evaporator.

[0010] Preferably, it also includes a concentrated brine unit, an atmospheric condenser, and a brine collection unit. The outlet of the concentrated brine unit is connected to the bottom inlet of the first-effect heater, the second-effect heater, and the third-effect heater respectively via a first-effect circulating pump, a second-effect circulating pump, and a third-effect circulating pump.

[0011] Preferably, the concentrated brine unit includes a mixing tank, a third-effect condensate preheater, a first-effect condensate preheater, and a deaerator. The outlet of the deaerator is connected to the bottom inlet of the first-effect heater, the second-effect heater, and the third-effect heater, respectively.

[0012] Preferably, the salt mud collection unit includes a centrifuge, one outlet of which is connected to the salt mud silo, and the other outlet is connected to the filtrate tank, and the outlet of the filtrate tank is connected to the concentrated brine unit.

[0013] Preferably, the side wall of the first-effect heater is provided with a steam inlet and a condensate outlet, and the top outlet of the first-effect heater is connected to the feed inlet of the first-effect evaporator separator; the top outlet of the first-effect evaporator separator is connected to the steam inlet of the second-effect heater, and the bottom outlet is connected to the bottom inlet of the first-effect heater through the first-effect circulating pump.

[0014] The side wall of the second-effect heater is provided with a steam inlet and a condensate outlet. The top outlet of the second-effect heater is connected to the feed inlet of the second-effect evaporator separator. The top outlet of the second-effect evaporator separator is connected to the steam inlet of the third-effect heater, and the bottom outlet is connected to the bottom inlet of the second-effect heater through the second-effect circulating pump.

[0015] The side wall of the III-effect heater is provided with a steam inlet and a condensate outlet. The top outlet of the III-effect heater is connected to the feed inlet of the III-effect evaporator separator. The top outlet of the III-effect evaporator separator is connected to the atmospheric condenser. The first bottom outlet is connected to the bottom inlet of the III-effect heater through the III-effect circulating pump. The second bottom outlet is connected to the salt mud collection unit.

[0016] Preferably, on the side wall of each heater, the steam inlet is located at the upper part of the side wall, and the condensate outlet is located at the lower part of the side wall.

[0017] Preferably, the condensate outlets of the I, II, and III effect heaters are connected to the inlets of the I, II, and III effect condensate tanks, respectively; the steam inlets of the I, II, and III effect heaters are connected to the steam outlets of the I, II, and III effect condensate tanks, respectively; the outlet of the I effect condensate tank is connected to the inlet of the flash evaporator; the condensate outlet of the flash evaporator is connected to the I effect condensate preheater; the steam outlet of the flash evaporator is connected to the steam inlet of the II effect heater; the condensate outlet of the II effect condensate tank is connected to the condensate inlet of the III effect condensate tank; and the condensate outlet of the III effect condensate tank is connected to the III effect condensate preheater.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] 1. In this utility model, a U-shaped tube is installed with a conical cap at the top of the outlet end of the U-shaped tube. The conical cap is completely immersed in the concentrate in the vacuum evaporator. The concentrate, heated by the heater, enters the interior of the vacuum evaporator directly through the inlet and the U-shaped tube. Due to the obstruction of the conical cap, the high-temperature concentrate will not spray or splash onto the steam in the vacuum evaporator, effectively avoiding the problem of mist entrainment when recovering steam at the top of the evaporator separator. At the same time, since the outlet end of the U-shaped tube is immersed in the concentrate in the vacuum evaporator, the high-temperature concentrate, heated by the heater, enters the interior of the vacuum evaporator, effectively avoiding the problem of secondary steam mist entrainment and pollution of circulating water quality caused by uneven heat exchange, violent boiling, and fluctuating liquid level in the concentrate.

[0020] 2. The practical application of this utility model has shown good results. It not only effectively improves the operational stability and continuous safe and stable operation of the evaporation device, but also reduces manpower consumption while avoiding pollution of the circulating water quality and ensuring the balance of the water system operation.

[0021] 3. This utility model has a simple structure, a short modification period, does not require a large amount of manpower and material resources, and its actual application effect and value creation far exceed the modification cost, resulting in a high economic benefit ratio.

[0022] 4. This utility model can be used to modify similar multi-effect evaporation devices, forming a mature and controllable modification scheme to achieve continuous, safe and stable operation of the evaporation system.

[0023] 5. When this utility model is applied to modern chemical wastewater treatment processes, the entire process achieves compliant wastewater treatment and reuse, successfully achieving near-zero wastewater discharge, reducing water resource consumption, minimizing the threat of coal-to-gas industry to ecological and environmental pollution, alleviating local water resource pressure, and fulfilling the social responsibility of conserving water resources and protecting the environment. Attached Figure Description

[0024] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0025] Figure 1 This is a schematic diagram of the falling film evaporator of this utility model;

[0026] Figure 2 This is a frontal cross-sectional view of the evaporator separator of this utility model;

[0027] Figure 3This is a schematic diagram of the first tube with a transverse opening unfolded on all four sides in this utility model. Detailed Implementation

[0028] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0029] like Figure 1-2 As shown, this utility model provides a falling film evaporation device, including a first-effect evaporation unit 1, a second-effect evaporation unit 2, and a third-effect evaporation unit 3. The first-effect evaporation unit 1 includes a first-effect heater 11 and a first-effect evaporator separator 12. The second-effect evaporation unit 2 includes a second-effect heater 21 and a second-effect evaporator separator 22. The third-effect evaporation unit 3 includes a third-effect heater 31 and a third-effect evaporator separator 32. The bottom inlets of the first-effect heater 11, the second-effect heater 21, and the third-effect heater 31 are connected sequentially, wherein:

[0030] Each effect evaporator / separator includes a vacuum evaporator 71, a feed inlet 72, a U-shaped tube 73, several support rods 74, a conical tube cap 75, and a support frame 76. The feed inlet 72 is located on the side wall of the vacuum evaporator 71, and its installation height is higher than the liquid level of the concentrate inside the vacuum evaporator 71. The U-shaped tube 73 is located inside the vacuum evaporator 71 and includes a first tube body 731, a bend 732, and a second tube body 733 connected in sequence. The end of the first tube body 731 away from the bend 732 is connected to the feed inlet 72. The end of the second tube body 733 away from the bend 732 is in an inverted trapezoidal shape, that is, the diameter of the outlet end of the U-shaped tube 73 is larger than the U-shaped tube 73. The diameter of the tube body 73 is equal to the diameter at the inlet; several support rods 74 are disposed on the top of the end of the second tube body 733 away from the bend 732, and a conical tube cap 75 is disposed on the top of the several support rods 74; a support frame 76 is disposed inside the vacuum evaporator 71, with one end connected to the inner wall of the vacuum evaporator 71 and the other end connected to the end of the second tube body 733 away from the bend 732; the first tube body 731 is partially immersed in the concentrated liquid in the vacuum evaporator 71, and the bend 732, the second tube body 733 and the conical tube cap 75 are completely immersed in the concentrated liquid in the vacuum evaporator 71.

[0031] In this utility model, the diameter of the U-shaped tube 73 body is DN400; the diameter of the outlet end of the U-shaped tube 73 is DN400×600, that is, the minimum diameter of the outlet end of the U-shaped tube 73 is DN400 and the maximum diameter is DN600.

[0032] Traditional evaporator separators have a high feed inlet, allowing concentrated liquid to be sprayed directly into the vacuum evaporator. Due to this high inlet position, when the top of the evaporator recovers steam, it is easy to simultaneously recover highly concentrated liquid droplets, creating a mist entrainment problem. In addition, the newly injected concentrated liquid is heated by the heater, and its temperature is higher than that of the concentrated liquid inside the vacuum evaporator. The concentrated liquid is sprayed directly into the surface of the concentrated liquid inside the vacuum evaporator without penetrating into the inner layer, which easily leads to uneven heat exchange. Moreover, when the new and old concentrated liquids meet, they splash and boil violently due to the temperature difference, causing the liquid level to fluctuate, resulting in secondary steam mist entrainment, and even causing highly concentrated liquid to vaporize and fly out, polluting the circulating water quality. In this invention, a U-shaped tube 73 is installed, with a conical cap 75 at the top of its outlet end. The conical cap 75 is completely submerged in the concentrate within the vacuum evaporator 71. The concentrate, heated by the heater, is sprayed into the vacuum evaporator 71 from the outlet end of the U-shaped tube 73 through the inlet 72 and the U-shaped tube 73. At this point, the conical cap 75 plays a crucial role in buffering and guiding, effectively preventing the concentrate from directly splashing into the steam area within the vacuum evaporator 71. This avoids potential safety hazards and process fluctuations caused by violent collisions between the high-temperature concentrate and steam. Furthermore, the conical cap 75 provides additional protection. The high-temperature concentrate slides naturally down its smooth inner wall and smoothly merges into the concentrate inside the tank. This not only achieves a smooth introduction of the concentrate but also fundamentally solves the problem of mist entrainment that is very easy to occur when steam is recovered at the top of the evaporator separator. At the same time, since the outlet end of the U-shaped tube 73 is immersed in the concentrate in the vacuum evaporator 71, the high-temperature concentrate heated by the heater enters the concentrate inside the vacuum evaporator 71. The collision between the old and new concentrates caused by the temperature difference diffuses from the inside out, gradually becoming gentler. This effectively avoids the problem of secondary steam mist entrainment and pollution of circulating water quality caused by uneven heat exchange, violent boiling, and fluctuating liquid level of the concentrate.

[0033] Preferably, the U-shaped tube 73, several support rods 74, conical tube cap 75, and support frame 76 are made of high-temperature corrosion resistant material.

[0034] Preferably, the first tube 731 immersed in the concentrated liquid in the vacuum evaporator 71 is provided with three sets of transverse openings. The three sets of transverse openings are provided on three sides of the first tube 731 away from the inner wall of the vacuum evaporator 71. That is, except for the side near the inner wall of the vacuum evaporator 71 where the feed inlet 72 is provided, the other three sides are provided with transverse openings and are evenly distributed at equal intervals on the three sides. Each set of transverse openings includes several small holes 77 on the same vertical line.

[0035] like Figure 2-3 As shown, in this utility model, each group of horizontal openings includes two small holes 77 located on the same vertical line.

[0036] In the embodiments of this application, Figure 2 This is a schematic diagram of the cross-sectional structure of an evaporator separator. Figure 2 The side with the feed inlet 72 is designated as left-facing, and the side with the conical cap 75 is designated as right-facing. Figure 2 The direction shown is for reference. Figure 3 Figure a shows the front unfolded view of the first tube 731, figure b shows the right-side unfolded view of the first tube 731, figure c shows the back unfolded view of the first tube 731, and figure d shows the left-side unfolded view of the first tube 731. From Figure 3 It can be clearly seen that, except for the side of the inner wall near the vacuum evaporator 71 where the feed inlet 72 is located, i.e. the left side, the other three sides of the first tube 731 are provided with horizontal openings.

[0037] In traditional evaporator separators, the highly concentrated liquid flows directly towards the inlet of the circulating pump. This invention, through the design of the U-shaped tube 73, changes the flow direction of the fluid. The highly concentrated liquid no longer directly impacts the inlet of the circulating pump, but instead undergoes more thorough mixing and flow within the system, extending its residence time and reducing the possibility of short-circuiting. Furthermore, the transverse openings on the first tube 731, which is immersed in the concentrated liquid in the vacuum evaporator 71, further divert and guide the highly concentrated liquid. After changing direction through the U-bend, it has a new flow option, preventing the highly concentrated liquid from concentrating towards the inlet of the circulating pump. Instead, it is dispersed to different directions and areas, thus solving the problem of short-circuiting caused by the highly concentrated liquid flowing directly towards the inlet of the circulating pump.

[0038] Preferably, an observation window 78 is also provided on the outer wall of the vacuum evaporator 71 for observing the height of the concentrated liquid inside the vacuum evaporator 71.

[0039] In this invention, an observation window 78 is provided so that operators can monitor the level of the concentrated liquid in the vacuum evaporator 71 in real time, ensuring that the liquid level is below the inlet 72 and above the conical cap 75. When the liquid level in the vacuum evaporator 71 is too high or too low, operators can adjust the flow rate of the high-temperature concentrated liquid entering the vacuum evaporator 71 by controlling the valve opening.

[0040] Preferably, it also includes a concentrated brine unit 4, an atmospheric condenser 5, and a salt mud collection unit 6. The outlet of the concentrated brine unit 4 is connected to the bottom inlet of the first-effect heater 11, the second-effect heater 21, and the third-effect heater 31 through the first-effect circulation pump 13, the second-effect circulation pump 23, and the third-effect circulation pump 33, respectively.

[0041] Preferably, the concentrated brine unit 4 includes a mixing tank 41, a third-effect condensate preheater 42 and a first-effect condensate preheater 43, and a deaerator 44. The outlet of the deaerator 44 is connected to the bottom inlet of the first-effect heater 11, the second-effect heater 21, and the third-effect heater 31, respectively.

[0042] Preferably, the salt mud collection unit 6 includes a centrifuge 61, one outlet of which is connected to the salt mud silo 62, and the other outlet is connected to the filtrate tank 63, and the outlet of the filtrate tank 63 is connected to the concentrated brine unit 4.

[0043] Preferably, the side wall of the first-effect heater 11 is provided with a steam inlet and a condensate outlet, the top outlet of the first-effect heater 11 is connected to the feed inlet of the first-effect evaporator 12; the top outlet of the first-effect evaporator 12 is connected to the steam inlet of the second-effect heater 21, and the bottom outlet is connected to the bottom inlet of the first-effect heater 11 through the first-effect circulating pump 13.

[0044] Preferably, the side wall of the II-effect heater 21 is provided with a steam inlet and a condensate outlet, the top outlet of the II-effect heater 21 is connected to the feed inlet of the II-effect evaporator 22; the top outlet of the II-effect evaporator 22 is connected to the steam inlet of the III-effect heater 21, and the bottom outlet is connected to the bottom inlet of the II-effect heater 21 through the II-effect circulating pump 23.

[0045] Preferably, the side wall of the III-effect heater 31 is provided with a steam inlet and a condensate outlet, the top outlet of the III-effect heater 31 is connected to the feed inlet of the III-effect evaporator 32; the top outlet of the III-effect evaporator 32 is connected to the atmospheric condenser 5, the first bottom outlet 321 is connected to the bottom inlet of the III-effect heater 31 through the III-effect circulating pump 33, and the second bottom outlet 322 is connected to the salt mud collection unit 6.

[0046] Preferably, on the side wall of each heater, the steam inlet is located at the upper part of the side wall, and the condensate outlet is located at the lower part of the side wall.

[0047] Preferably, the condensate outlets of the I, II, and III effect heaters are connected to the inlets of the I, II, and III effect condensate tanks, respectively; the steam inlets of the I, II, and III effect heaters are connected to the steam outlets of the I, II, and III effect condensate tanks, respectively; the outlet of the I effect condensate tank 14 is connected to the inlet of the flash evaporator 15; the condensate outlet of the flash evaporator 15 is connected to the I effect condensate preheater 43; the steam outlet of the flash evaporator 15 is connected to the steam inlet of the II effect heater 21; the condensate outlet of the II effect condensate tank 24 is connected to the condensate inlet of the III effect condensate tank 34; and the condensate outlet of the III effect condensate tank 34 is connected to the III effect condensate preheater 42.

[0048] In actual operation, the concentrated brine is fed into the mixing cylinder 41, and then preheated in two stages by the III-effect condensate preheater 42 and the I-effect condensate preheater 43. The heated concentrated brine then enters the deaerator 44 to remove non-condensable gases such as ammonia, oxygen, and carbon monoxide from the solution. The removed non-condensable gases are sent to the atmospheric condenser and discharged through the vacuum system. The degassed concentrated brine is discharged from the bottom of the deaerator 44 and sent to the I, II, and III effect heaters.

[0049] Low-pressure steam enters the steam ejector, recovering part of the secondary steam generated by the first-effect evaporator 12. After mixing at the steam ejector outlet, it enters the first-effect heater 11, where it exchanges heat and condenses. The condensate is pumped by the first-effect condensate pump 13 to the first-effect condensate tank 14, and then to the flash tank 15 for preheating and recovery. Steam enters the second-effect heater 21, and the condensate is sent to the first-effect condensate preheater 43, where it exchanges heat with the concentrated brine to form the first-effect condensate, which is then sent to the turbidity circulating membrane concentration reverse osmosis permeate tank. The unevaporated concentrated brine in the first-effect evaporator 12 is partially circulated back to the first-effect heater 11 by the first-effect circulating pump 13 for reheating and evaporation, while the remainder flows to the bottom inlet of the second-effect heater 21.

[0050] Part of the secondary steam generated by the first-effect evaporator 12 is returned to the steam ejector, while the other part enters the second-effect heater 21 as a heat source. After heat exchange in the second-effect heater 21, the steam condenses, and the condensate is sent by the second-effect condensate pump 24 through the second-effect condensate tank 24 to the third-effect condensate tank 34. The unevaporated concentrated brine in the second-effect evaporator 22 is partially circulated back to the second-effect heater 21 by the second-effect circulation pump 24 for reheating and evaporation, while the remainder flows to the bottom inlet of the third-effect heater 31.

[0051] The secondary steam generated by the second-effect evaporator 22 enters the third-effect heater 31, where it exchanges heat and condenses. The condensate is pumped by the third-effect condensate pump to the third-effect condensate tank 34, where it mixes with the condensate from the second-effect condensate tank 24 and is then sent to the third-effect condensate preheater 42. After heat exchange with the concentrated brine, it forms the third-effect condensate, which is sent to the turbid circulating water system as makeup water for reuse. The unevaporated concentrated brine in the third-effect evaporator 32 flows out from the first bottom 321 and is circulated back to the third-effect heater 31 by the third-effect circulating pump 34 for reheating and evaporation. During this process, a large amount of crystals gradually deposit at the bottom of the third-effect evaporator 32 and flows into the salt mud collection unit 6 along with the concentrated brine through the second bottom 322.

[0052] The concentrated brine containing a large amount of crystals is introduced into the brine collection unit 6 and then into the centrifuge 61. The separated brine is introduced into the brine silo 62 and loaded onto trucks for transport. The filtrate is introduced into the filtrate tank 63 and then into the concentrated brine unit 4 for further processing.

[0053] In this invention, the outlet of the filtrate tank 63 is connected to the outlet of the deaerator 44. That is, after the filtrate flows out of the filtrate tank 63, it is mixed with the concentrated brine discharged from the deaerator 44 and then sent back to the I, II, and III effect heaters for evaporation treatment.

[0054] The secondary steam generated by the third-effect evaporator 32 enters the atmospheric condenser 5, where it directly contacts and condenses with the circulating cooling water from the turbid circulating water system, thus creating a certain degree of vacuum and obtaining evaporative condensate. The evaporative condensate is then sent back to the turbid circulating water system as makeup water for reuse. The non-condensable gases in each effect heater are sequentially discharged into the next effect heater, and the tail-effect non-condensable gases are discharged into the atmospheric condenser 5 and finally extracted by the steam ejector.

[0055] During system operation, the steam used for heating in the I, II, and III effect heaters can be further separated through the I, II, and III effect condensate tanks, respectively, and the steam with heat can be reused in the heater of the same effect.

[0056] Traditional falling film evaporators produce condensate with substandard water quality, while the improved falling film evaporator produced by this invention produces condensate with acceptable water quality.

[0057] Traditional falling film evaporators require shutdown and cleaning after about 20 days of operation. However, the improved falling film evaporator of this invention can run for 45-50 days at a time. Compared with traditional devices, it not only doubles the operating cycle but also effectively saves on expensive cleaning costs.

[0058] Finally, it should be noted that the above description is only a preferred embodiment of the present utility model and is not intended to limit the present utility model. Although the present utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.

Claims

1. A falling film evaporation device, comprising a first-effect evaporation unit, a second-effect evaporation unit, and a third-effect evaporation unit, wherein the first-effect evaporation unit includes a first-effect heater and a first-effect evaporator separator, the second-effect evaporation unit includes a second-effect heater and a second-effect evaporator separator, and the third-effect evaporation unit includes a third-effect heater and a third-effect evaporator separator, wherein the bottom inlets of the first-effect heater, the second-effect heater, and the third-effect heater are sequentially connected, characterized in that: Each effect evaporator / separator includes a vacuum evaporator, a feed inlet, a U-shaped tube, several support rods, a conical cap, and a support frame. The feed inlet is located on the side wall of the vacuum evaporator, and its installation height is higher than the liquid level of the concentrate inside the vacuum evaporator. The U-shaped tube is located inside the vacuum evaporator and includes a first tube body, a bend, and a second tube body connected in sequence. The end of the first tube body away from the bend is connected to the feed inlet, and the end of the second tube body away from the bend is inverted trapezoidal in shape, i.e., the diameter of the U-shaped tube outlet is greater than the diameter of the U-shaped tube body / the diameter at the inlet. Several support rods are located at the top of the end of the second tube body away from the bend, and the conical cap is located at the top of the support rods. The support frame is located inside the vacuum evaporator, with one end connected to the inner side wall of the vacuum evaporator and the other end connected to the end of the second tube body away from the bend. The first tube body is partially immersed in the concentrate inside the vacuum evaporator, and the bend, the second tube body, and the conical cap are completely immersed in the concentrate inside the vacuum evaporator.

2. Falling film evaporator according to claim 1, characterized in that The U-shaped tube, several support rods, conical tube cap, and support frame are made of high-temperature corrosion resistant materials.

3. A falling film evaporator according to claim 1, characterized in that: The first tube, which is immersed in the concentrated liquid in the vacuum evaporator, has three sets of transverse openings. The three sets of transverse openings are located on three sides of the first tube away from the inner wall of the vacuum evaporator. That is, except for the side near the inner wall of the vacuum evaporator where the feed inlet is located, the other three sides are provided with transverse openings, which are evenly distributed at equal intervals on the three sides. Each set of transverse openings includes several small holes on the same vertical line.

4. A falling film evaporator according to claim 1, characterized in that: An observation window is also provided on the outer wall of the vacuum evaporator to observe the level of the concentrated liquid inside the vacuum evaporator.

5. A falling film evaporator according to claim 1, characterized in that: It also includes a concentrated brine unit, an atmospheric condenser, and a brine collection unit. The outlet of the concentrated brine unit is connected to the bottom inlet of the first-effect heater, the second-effect heater, and the third-effect heater respectively via a first-effect circulating pump, a second-effect circulating pump, and a third-effect circulating pump.

6. A falling film evaporator according to claim 5, characterized in that: The concentrated brine unit includes a mixing tank, a III-effect condensate preheater, an I-effect condensate preheater, and a deaerator. The outlet of the deaerator is connected to the bottom inlet of the I-effect heater, the II-effect heater, and the III-effect heater, respectively.

7. A falling film evaporator according to claim 5, characterized in that: The salt mud collection unit includes a centrifuge. One outlet of the centrifuge is connected to the salt mud silo, and the other outlet is connected to the filtrate tank. The outlet of the filtrate tank is connected to the concentrated brine unit.

8. A falling film evaporator according to claim 1, characterized in that: The side wall of the first-effect heater is provided with a steam inlet and a condensate outlet. The top outlet of the first-effect heater is connected to the feed inlet of the first-effect evaporator separator. The top outlet of the first-effect evaporator separator is connected to the steam inlet of the second-effect heater, and the bottom outlet is connected to the bottom inlet of the first-effect heater through the first-effect circulating pump. The side wall of the second-effect heater is provided with a steam inlet and a condensate outlet. The top outlet of the second-effect heater is connected to the feed inlet of the second-effect evaporator separator. The top outlet of the second-effect evaporator separator is connected to the steam inlet of the third-effect heater, and the bottom outlet is connected to the bottom inlet of the second-effect heater through the second-effect circulating pump. The side wall of the III-effect heater is provided with a steam inlet and a condensate outlet. The top outlet of the III-effect heater is connected to the feed inlet of the III-effect evaporator separator. The top outlet of the III-effect evaporator separator is connected to the atmospheric condenser. The first bottom outlet is connected to the bottom inlet of the III-effect heater through the III-effect circulating pump. The second bottom outlet is connected to the salt mud collection unit.

9. A falling film evaporator according to claim 1, characterized in that: On the side wall of each heater, the steam inlet is located at the upper part of the side wall, and the condensate outlet is located at the lower part of the side wall.

10. A falling film evaporator according to claim 1, characterized in that: The condensate outlets of the I, II, and III effect heaters are connected to the inlets of the I, II, and III effect condensate tanks, respectively. The steam inlets of the I, II, and III effect heaters are connected to the steam outlets of the I, II, and III effect condensate tanks, respectively. The outlet of the I effect condensate tank is connected to the inlet of the flash evaporator. The condensate outlet of the flash evaporator is connected to the I effect condensate preheater. The steam outlet of the flash evaporator is connected to the steam inlet of the II effect heater. The condensate outlet of the II effect condensate tank is connected to the condensate inlet of the III effect condensate tank. The condensate outlet of the III effect condensate tank is connected to the III effect condensate preheater.

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