TWI908589B - Water mist elimination barrel of mechanical vapor recompression system - Google Patents

Abstract

An embodiment of the present invention provides a mechanical vapor recompression system, which includes a distillation gas-water separation barrel, a gas compressor, a water mist elimination barrel, a main heat exchanger, a waste liquid preheating barrel, and a branch manifold. The mist elimination barrel is fluidly connected between the distillation gas-water separation barrel and the gas compressor, and is used to eliminate a mist from the distillation gas-water separation barrel. The waste liquid preheating barrel includes two regions for containing condensed water and waste liquid. The waste liquid in the waste liquid preheating barrel is heated by the heat energy of the condensed water before its supply to the main heat exchanger. The branch manifold is fluidly connected between the main heat exchanger and the distillation gas-water separation barrel, and is used to separate the steam from the waste liquid.

Description

Water mist elimination tank of mechanical vapor recompression system

This invention relates to a mechanical vapor recompression system, and more particularly to a mechanical vapor recompression system with energy-reducing characteristics.

As environmental regulations become increasingly stringent, manufacturers are required to upgrade their on-site water treatment equipment to reduce total wastewater discharge or even eliminate wastewater discharge altogether. On the other hand, in order to reduce greenhouse gas emissions and achieve the goal of reducing carbon footprint, manufacturers are also expected to abandon the traditional use of fossil fuels as energy for the above-mentioned water treatment processes and switch to renewable electricity.

While traditional distillation equipment can reduce wastewater concentration, it is quite energy-intensive. The higher the boiling point of the waste liquid, the more energy is required for its evaporation. However, if the boiling point and pressure of the waste liquid are not increased in order to reduce energy consumption, the boiling liquid will vaporize prematurely in the pipeline, producing water mist and crystal particles, which in turn will cause the crystal particles to clog the pipeline and affect the distillation efficiency.

Mechanical Vapor Recompression (MVR) systems offer a solution to traditional distillation equipment by recycling heat from the vapor compressor to generate more vapor, thereby reducing energy demand. Manufacturers can use MVR systems to treat or recycle high-concentration industrial wastewater (e.g., nitrate nitrogen) at a lower cost, or to desalinate seawater to provide increasingly scarce water resources.

However, in traditional MVR systems, wastewater generates a large number of floating droplets and mist within the separator. These droplets and mist form numerous crystals in the pipelines and vapor compressor, causing malfunctions. Therefore, operators must frequently shut down the system for maintenance and cleaning to prevent vapor compressor failures and prolong their lifespan. This not only hinders wastewater treatment efficiency but also increases operating costs. While reducing the concentration ratio can avoid mist, it also negatively impacts treatment efficiency.

In view of the shortcomings of traditional MVR systems, this invention proposes a new MVR system that has advantages over traditional MVR systems, including low energy consumption, high durability, high uptime, and low maintenance rate.

According to one embodiment of the present invention, the MVR system includes a distillation gas moisture separator; a gas compressor configured to pressurize vapor from the distillation gas moisture separator; a water mist elimination tank fluidly connected between the distillation gas moisture separator and the gas compressor and configured to eliminate water mist from the distillation gas moisture separator; a main heat exchanger configured to heat wastewater from a wastewater source by the pressurized vapor from the gas compressor; and a wastewater preheating tank including a receiving tank and a thermally conductive partition disposed within the receiving tank. The container is divided into at least a first region and a second region. The first region is fluidly connected between the wastewater source and the main heat exchanger and configured to accommodate the wastewater. The second region is fluidly connected between the main heat exchanger and a drain outlet and configured to accommodate condensate generated from the main heat exchanger after the vapor is condensed. The container also includes a branch manifold, which includes an inlet pipe fluidly connected to the main heat exchanger and a first outlet pipe and a second outlet pipe connected to the inlet pipe and fluidly connected to different height positions of the distillation gas-water separation tank.

According to another embodiment of the present invention, the MVR system includes a distillation gas-moisture separator; a gas compressor configured to pressurize a vapor from the distillation gas-moisture separator; a main heat exchanger configured to heat wastewater from a wastewater source by means of the pressurized vapor from the gas compressor; and a wastewater preheating tank including a container and a thermally conductive partition disposed within the container, the thermally conductive partition dividing the container into at least a first region and a second region. The system comprises: a first zone fluidly connected between the wastewater source and the main heat exchanger and configured to contain the wastewater; a second zone fluidly connected between the main heat exchanger and a drain outlet and configured to contain condensate generated in the main heat exchanger after the vapor is condensed; a heating pipe fluidly connected between the main heat exchanger and the distillation gas-water separation tank and configured to heat the wastewater from the main heat exchanger; and a heat source connected to the heating pipe.

According to another embodiment of the present invention, the MVR system includes a distillation gas moisture separator; a gas compressor configured to pressurize a vapor from the distillation gas moisture separator; a water mist elimination tank fluidly connected between the distillation gas moisture separator and the gas compressor and configured to eliminate water mist from the distillation gas moisture separator; a main heat exchanger configured to heat wastewater from a wastewater source by the pressurized vapor from the gas compressor; and a primary heat exchanger fluidly connected to the main heat exchanger and configured to allow heat exchange between the wastewater supplied to the main heat exchanger and the condensate from the main heat exchanger.

The following disclosure provides numerous different embodiments or examples for implementing various features of the provided object. Specific examples of elements and configurations will be described below to simplify this disclosure. Of course, these are merely examples and are not intended to be limiting. For example, in the following description, forming a first component above or on a second component may include embodiments in which the first and second components are in direct contact, and may also include embodiments in which additional components may be formed between the first and second components such that the first and second components are not in direct contact. Furthermore, element symbols and/or letters may be repeated in various embodiments of this disclosure. This repetition is for simplicity and clarity and does not in itself indicate a relationship between the various embodiments and/or configurations discussed.

Furthermore, for ease of description, spatial relative terms (such as "below," "under," "down," "above," "over," "on," "on," and similar terms) are used herein to describe the relationship between one element or component and another element(s), as illustrated in the figures. In addition to the orientations depicted in the figures, spatial relative terms are also intended to cover different orientations of the device during use or operation. The device may be oriented in other ways (rotated 90 degrees or otherwise), and the spatial relative descriptors used herein can be interpreted accordingly.

As used herein, terms such as “first,” “second,” and “third” describe various elements, components, regions, layers, and/or segments, but these elements, components, regions, layers, and/or segments should not be limited by these terms. These terms may be used only to distinguish elements, components, regions, layers, or segments from one another. Unless clearly indicated herein, the terms such as “first,” “second,” and “third” used herein do not imply a sequence or order.

As used in this article, the terms “approximately,” “substantially,” “substantially,” and “about” are used to describe and take into account minor variations. When used in conjunction with an event or situation, the terms may refer to examples of events or situations that exactly occurred as well as examples of events or situations that are very close to occurring.

As used herein, the terms “pipeline,” “pipeline,” “flow path,” and “pipeline” are used interchangeably and refer to any type, size, or configuration of flow conduit commonly used in the art for transporting liquid and/or gaseous materials and combinations thereof.

Figure 1 shows a schematic diagram of a mechanical vapor recompression system 1 according to a portion of the embodiments disclosed herein. The mechanical vapor recompression system 1 includes a primary heat exchanger 21, a main heat exchanger 23, a heating tube 25, a waste liquid preheating tank 30, a branch manifold 40, a distillate water separator 50, a water mist eliminator 60, a gas compressor 70, and a control device 90. The components of the mechanical vapor recompression system 1 may be added or removed as needed, and are not limited to the embodiment shown in Figure 1.

The secondary heat exchanger 21, the primary heat exchanger 23, and the waste liquid preheating tank 30 are configured to heat waste liquid from a waste liquid source 81, causing the waste liquid to boil when it enters the distillate gas moisture separation tank 50. In an exemplary embodiment, the waste liquid source 81 is a scrubbing tower for cleaning combustion exhaust gas. The waste liquid WO from the scrubbing tower can first pass through a heavy metal filter to remove heavy metal impurities, and then be transported to the secondary heat exchanger 21 via pipeline 101 and pump 91 (e.g., electric pump).

The steps of heating waste liquid using secondary heat exchanger 21, primary heat exchanger 23 and waste liquid preheating tank 30 include: (1) heating waste liquid W0 in secondary heat exchanger 21 by the heat energy from condensate L2 from waste liquid preheating tank 30 to make it waste liquid W1 with a first boost temperature (e.g., 60~98°C, the value of the interval will change with the operating pressure); (2) supplying waste liquid W1 to waste liquid preheating tank 30 through pipeline 102, and heating it by the heat energy from condensate L1 contained in waste liquid preheating tank 30 to make it with a second boost temperature. (2) Heat the waste liquid W2 to a temperature of (e.g., 61~99°C, the value of the interval endpoint will change with the operating pressure); (3) Supply the waste liquid W2 from the waste liquid preheating tank 30 to the main heat exchanger 23 through the pipeline 103 and the pump 92 (e.g., pneumatic pump), and heat it with the heat energy of the high-pressure steam HG in the main heat exchanger 23 to make it into a (vapor-containing) waste liquid W3 with a boiling temperature of (e.g., 62~130°C, the value of the interval endpoint will change with the operating pressure), so that the steam in it can be separated from the waste liquid in the distillation gas moisture separation tank 50.

In some embodiments, as shown in Figure 1, the wastewater preheating tank 30 includes a hollow container 31 and a thermally conductive partition 32. The thermally conductive partition 32 may be made of a material with a high thermal conductivity (e.g., aluminum). The thermally conductive partition 32 is disposed in the container 31 and extends vertically from the top surface 311 of the container 31 to the bottom surface 310 of the container 31, thereby dividing the container 31 into a first region 33 and a second region 34. The first region 33 and the second region 34 are independent of each other and are not interconnected.

The first zone 33 is connected to the secondary heat exchanger 21 via a pipeline 102 at one end relative to the top surface 311 of the container 31. The first zone 33 is connected to the main heat exchanger 23 via a pipeline 103 at one end relative to the bottom surface 310 of the container 31. The second zone 34 is connected to the main heat exchanger 23 via a pipeline at one end relative to the top surface 311 of the container 31. The second zone 34 is connected to the secondary heat exchanger 21 via a pipeline 111 at one end relative to the bottom surface 310 of the container 31. During operation of the mechanical vapor recompression system 1, waste liquid W1 from the secondary heat exchanger 21 and condensate L1 from the main heat exchanger 23 are supplied to the first zone 33 and the second zone 34 respectively, and heat exchange occurs through the thermally conductive partition 32. In this way, the heat energy of the condensate L1 will be further utilized, thus reducing the energy required to heat the waste liquid W1.

In some embodiments, the waste liquid and condensate stored in the waste liquid preheating tank 30 are supplied to and discharged from the waste liquid preheating tank 30 at a fixed flow rate (i.e., the waste liquid and condensate are not stored statically in the waste liquid preheating tank 30). In other embodiments, the waste liquid and condensate supplied into the waste liquid preheating tank 30 are stored statically in the waste liquid preheating tank 30 for a predetermined time, and are discharged from the waste liquid preheating tank 30 after the predetermined time has elapsed. The aforementioned flow rate can be calculated based on parameters such as the temperature of the condensate, the temperature of the waste liquid, the volume of the waste liquid preheating tank 30, and the heat transfer efficiency of the thermally conductive partition 32. In some embodiments, the secondary heat exchanger 21 is omitted, and the waste liquid reaches a desired temperature by exchanging heat with the condensate in the waste liquid preheating tank 30.

In some embodiments, as shown in Figure 2A, the thermally conductive partition 32 is disposed at the center of the receiving tank 31 of the waste liquid preheating tank 30 to equally separate the first region 33 and the second region 34. However, the configuration of the waste liquid preheating tank is not limited to this; the thermally conductive partition can be disposed in the hollow body in other ways. For example, as shown in Figure 2B, the waste liquid preheating tank 30a includes a receiving tank 31a and two thermally conductive partitions 32a and 35a. The thermally conductive partitions 32a and 35a are located in the receiving tank 31a and are arranged perpendicularly to each other to separate the two first regions 33a and the two second regions 34a. In the circumferential direction of the receiving tank 31a, the first regions 33a and the second regions 34a are arranged alternately. Alternatively, as shown in Figure 2C, the wastewater preheating tank 30b includes a container 31b and an annular heat-conducting partition 32b. The heat-conducting partition 32b is concentrically disposed within the container 31b to separate a first region 33b and a second region 34b. The second region 34b is located at the center of the container 31b, and the first region 33b is arranged in a ring around the second region 34b.

The cross-section of the partition in the above embodiments can be corrugated, serrated, or finned to increase the contact area between the partition and the liquid, thereby improving heat exchange efficiency. The partition can be made of a material with high thermal conductivity and corrosion resistance to the waste liquid to be received (e.g., steel-aluminum composite plate) to increase the service life of the partition.

In traditional MVR systems, wastewater from the secondary heat exchanger 21 and condensate from the primary heat exchanger 23 are stored separately in two tanks for use in subsequent processes. Because these two tanks are separate, the temperature of the wastewater and condensate decreases with storage time, hindering heat recovery. Compared to the traditional MVR system design, the wastewater preheating tank 30 of this embodiment can fully recover the heat energy of the condensate to heat the wastewater, reducing heat loss caused by heating the wastewater in the primary heat exchanger. Furthermore, the wastewater preheating tank 30 of this embodiment offers the advantage of reducing equipment footprint compared to the traditional two-tank configuration.

Referring again to Figure 1, in some embodiments, the waste liquid W3 from the main heat exchanger 23 enters the distillate gas moisture separator 50 via a branch manifold 40. In some embodiments, the branch manifold 40 includes a first outlet pipe 41, a second outlet pipe 42, and an inlet pipe 43. One end of the inlet pipe 43 is fluidly connected to the outlet of the main heat exchanger, and the other end of the inlet pipe 43 is coupled to the first outlet pipe 41 and the second outlet pipe 42. The opposite ends of the first outlet pipe 41 and the second outlet pipe 42, which are connected to the inlet pipe 43, are fluidly connected to the first inlet port 521 and the second inlet port 522 located at different heights on the distillate gas moisture separator 50, respectively. In some embodiments, as shown in Figure 3A, the branch manifold 40 has a substantial Y-shaped structure, wherein the major axis T1 of the first outlet pipe 41 and the major axis T0 of the inlet pipe 43 form a first angle α1, and the major axis T2 of the second outlet pipe 42 and the major axis T0 of the inlet pipe 43 form a second angle α2. However, it should be understood that many variations and modifications can be made to the embodiments disclosed herein. In some other embodiments, as shown in Figure 3B, the second outlet pipe 42a of the branch manifold 40a is not directly coupled to the inlet pipe 43a, but is coupled to the upper side of the first outlet pipe 41a. The major axis T1 of the first outlet pipe 41a and the major axis T0 of the inlet pipe 43a form a first angle a1, and the major axis T2 of the second outlet pipe 42a and the major axis T1 of the first outlet pipe 41a form a second angle a2. In some other embodiments, as shown in Figure 3C, the first outlet pipe 41b and the second outlet pipe 42b of the branch manifold 40b do not intersect. The junction of the first outlet pipe 41b and the inlet pipe 43b is closer to or further away from the main heat exchanger (i.e., the inlet of the inlet pipe 43b) than the junction of the second outlet pipe 42b and the inlet pipe 43b.

The aforementioned first included angle a1 can be between approximately 15 degrees and approximately 70 degrees. For example, the first included angle a1 can be selected from any degree of 15 degrees, 20 degrees, 25 degrees, 30 degrees, 35 degrees, 40 degrees, 45 degrees, 50 degrees, 55 degrees, 60 degrees, 65 degrees, or 70 degrees. With the provision of the first outlet pipe 41, the waste liquid W4 formed after the waste liquid W3 from the main heat exchanger 23 is discharged (all or part) of the vapor will move downward along the inner wall of the first outlet pipe 41 by gravity and enter the distillation gas-water separation tank 50 (Figure 1) through the first inlet port 521 (Figure 1). Since the waste liquid W4 is not directly supplied to the distillation gas moisture separator 50 via a pipeline perpendicular to the side wall 512, the suspended matter or tiny droplets caused by the splashing of waste liquid W4 within the distillation gas moisture separator 50 can be reduced or avoided. Therefore, the risk of damage to the gas compressor due to waste liquid crystallization can be further reduced. In an exemplary embodiment, the first included angle a1 is set at 45 degrees to facilitate the smooth entry of waste liquid W4 into the first outlet pipe 41.

The second included angle a2 can be between approximately 15 degrees and approximately 90 degrees. For example, the second included angle a2 can be selected from any degree of 15 degrees, 20 degrees, 25 degrees, 30 degrees, 35 degrees, 40 degrees, 45 degrees, 50 degrees, 55 degrees, 60 degrees, 65 degrees, 70 degrees, 75 degrees, 80 degrees, 85 degrees, or 90 degrees. Due to its lighter specific gravity, the vapor W5 from the waste liquid W3 of the main heat exchanger 23 will enter the second outlet pipe 42 upwards and enter the distillation gas-moisture separator 50 (Figure 1) through the second inlet port 522 (Figure 1). Since the vapor W5 and waste liquid W4 are separated before entering the distillation gas moisture separation tank 50 (Figure 1), the presence of water mist or fine droplets in the vapor within the distillation gas moisture separation tank 50 can be reduced or avoided. Therefore, the risk of damage to the gas compressor due to waste liquid crystallization can be further reduced. In an exemplary embodiment, the second included angle a2 is set at 45 degrees to facilitate the smooth entry of vapor W5 into the second outlet pipe 42.

Figure 4 shows a schematic diagram of a distillation gas moisture separator 50 according to a partial embodiment of the present invention. The distillation gas moisture separator 50 is configured to separate the vapor from the residual waste liquid in the waste liquid W4. In a partial embodiment, the distillation gas moisture separator 50 includes a separation tank 51, a connecting pipe 54, and a storage tank 55. The separation tank 51 is a hollow cylindrical structure with a predetermined height. The first inlet port 521 and the second inlet port 522 of the distillation gas moisture separator 50 are respectively formed on the side wall 512 of the separation tank 51 and are separated by a height difference H1 in the vertical direction. The height difference H1 can be appropriately selected to minimize the possibility of vapor W5 being contaminated by suspended matter or fine droplets in waste liquid W4, without obstructing the vapor separated from waste liquid W4 from leaving the distillate moisture separation tank 50 through outlet 523.

Connecting pipe 54 connects the bottom surface 510 of separation tank 51 and the top surface 551 of storage tank 55. The concentrated waste liquid CL, which has been devastated in separation tank 51, is pulled by gravity and enters storage tank 55 through connecting pipe 54, and is discharged through discharge hole 552 formed on the bottom surface 550 of storage tank 55. As shown in Figure 1, the concentrated waste liquid CL discharged from storage tank 55 can be discharged to dryer 83 through pipeline 106 for further treatment, removing a large amount of water from the concentrated waste liquid to form wet sludge, thereby achieving the goal of zero wastewater discharge. Alternatively, after entering the storage tank 55, the concentrated waste liquid CL can be re-supplied to the main heat exchanger 23 via pipeline 114 and pump 94 (e.g., pneumatic pump) to mix with the waste liquid W2.

Referring to Figures 4 and 5, in some embodiments, the first inlet port 521 and the second inlet port 522 of the distillation gas-water separation tank 50 are eccentrically positioned relative to the center C of the separation tank 51. For example, as shown in Figure 5, the first inlet port 521 is connected to the side wall 512 of the separation tank 51, wherein the outer wall of the first inlet port 521 is tangent to the outer wall of the separation tank 51, and the major axis T4 of the first inlet port 521 extends perpendicular to the radial direction of the separation tank 51 and is separated from the center C of the separation tank 51 by a distance D1. The second inlet port 522 can be connected to the separation tank 51 in a similar manner to the first inlet port 521.

As shown in Figure 4, since the first inlet port 521 and the second inlet port 522 are arranged eccentrically, the waste liquid W4 through the first inlet port 521 and the steam W5 through the second inlet port 522 will enter the separation tank 51 in a swirling manner. In this way, the waste liquid W4 can be prevented from splashing in the separation tank 51, thereby reducing or avoiding concerns about water mist or droplets mixing into the steam. On the other hand, through the swirling movement of the steam W5, most of the water mist in the steam W5 will be discharged from the steam W5 by the centrifugal force. In some embodiments, the vapor W5 in the separation tank 51 and the vapor separated from the waste liquid W4 will mix to form a composite gas flow W6, which will be discharged from the distillate gas moisture separation tank 50 through an outlet 523 formed on the top surface 511 of the separation tank 51. The outlet 523 may be arranged at an angle relative to the top surface 511 of the separation tank 51 to facilitate the discharge of the swirling composite gas flow W6. In some embodiments, the distillate gas moisture separation tank 50 may further include one or more viewing windows 56, 57 for the operator to inspect the condition of the separation tank 51 and the storage tank 55.

Referring again to Figure 1, in some embodiments, after the waste liquid W4 leaves the branch manifold 40 and before entering the distillation gas-water separation tank 50, the waste liquid W4 is further heated through the heating tube 25. In some embodiments, as shown in Figures 6A and 6B, the heating tube includes a shell 26, a fluid inlet 27, a fluid outlet 28, and a plurality of flow channels 29. The shell 26 has a sidewall 261 and two end faces 262 and 263 located at both ends of the sidewall 261. The shell 26 is a hollow structure, with its upper end connected to the fluid inlet 27 and its lower end connected to the fluid outlet 28. The flow channels 29 are tubular structures with openings at both ends and extending parallel to the sidewall 261. One end of the flow channel 29 located on end face 262 is connected to the first outlet pipe 41 of the fluid connection to the branch manifold 40 (Figure 1), and the other end of the flow channel 29 located on end face 263 is connected to the first inlet port 521 of the fluid connection to the distillate gas-water separation tank 50 (Figure 1). When heating waste liquid W4, as shown in Figure 6B, heating steam G1 enters the shell 26 through fluid inlet 27, and after flowing through the outer surface of the flow channel 29, it exits the shell 26 through fluid outlet 28.

In some embodiments, as shown in Figure 1, the heating pipe 25 can be fluidly connected to a heat source 82 via a valve 93 to receive heated steam from the heat source 82. Furthermore, the heating pipe 25 can be fluidly connected to a second outlet pipe 42 via a pipeline 105 to discharge the heated steam into a distillation gas-water separator 50 via the second outlet pipe 42. In an exemplary embodiment, the heat source 82 is high-temperature steam discharged from a factory device (not shown), thus reducing the carbon footprint generated by the mechanical vapor recompression system 1. In some embodiments, the heating process for the waste liquid W4 is only performed when the mechanical vapor recompression system 1 is started and stops when the waste liquid W4 reaches a predetermined temperature. In some other embodiments, the heating process of waste liquid W4 is automatically executed when the temperature of waste liquid W4 is lower than a predetermined temperature. In still other embodiments, the heating process of waste liquid W4 is continuously executed during the operation of the mechanical vapor recompression system 1.

Traditional MVR systems directly heat the waste liquid using a heater installed in the separation tank. During the heating process, the heater vibrates due to its operation. This vibration generates waste liquid droplets in the separation tank, and these droplets adhere to the gas compressor along with the vapor. The heating tube of this invention effectively avoids the drawbacks of traditional MVR systems. Furthermore, since the high-temperature vapor heats the waste liquid W4 through the outer surface of the flow channel 29, rather than directly heating the waste liquid W4, the generation of water mist and droplets is further reduced.

Figure 7 shows a cross-sectional schematic view of a water mist elimination tank 60 according to a partial embodiment of the present invention. According to a partial embodiment, the water mist elimination tank 60 includes a body 61, an inlet port 621, an outlet port 622, a plurality of mesh plates 631, 632, 633, 634, 635, a mesh frame 64, a plurality of annular packing materials 65, and a channel 66.

The main body 61 has a hollow cylindrical structure. An inlet port 621 is located on the side 612 of the main body 61 and adjacent to its top surface 611. The inlet port 621 is configured to receive the combined airflow W6 delivered via the pipeline 107 (FIG. 1) from the separation tank 51. In some embodiments, similar to the arrangement of the first inlet port 521 shown in FIG. 5, the inlet port 621 of the water mist elimination tank 60 is eccentrically positioned relative to the center of the main body 61. In this way, the combined airflow W6 through the inlet port 621 enters the main body 61 in a swirling manner.

The outlet port 622 is located at the center of the top surface 611 of the main body 61. The channel 66 is a hollow tube. The upper end (first end) of the channel 66 is connected to the outlet port 622, and extends towards the bottom surface 610 of the main body 61 in a direction away from the outlet port 622 to its lower end (second end). The lower end of the channel 66 is separated from the bottom surface 610 of the main body 61 by a height difference H2, and does not directly contact the bottom surface 610 of the main body 61.

A plurality of grid plates 631, 632, 633, 634, and 635 are disposed within the body 61 and located below the entrance port 621. Each of the grid plates 631, 632, 633, 634, and 635 has an annular structure, with its outer circumference abutting against the inner wall surface of the body 61 and its inner circumference abutting against the outer surface of the channel 66. Specifically, as shown in Figure 8, each of the inner circumferences of the grid plates 631, 632, 633, 634, and 635 defines an opening 6315, 6325, 6335, 6345, and 6355, respectively. The channel 66 passes through the openings 6315, 6325, 6335, 6345, and 6355 and abuts against their inner edges. The adjacent grid panels 631, 632, 633, 634, and 635 are separated by spacers 67, with each panel separated by one space.

In some embodiments, the mesh plates 631, 632, 633, 634, and 635 further include perforations for allowing fluid to pass through, wherein the perforations of two of the adjacent mesh plates 631, 632, 633, 634, and 635 are staggered. For example, as shown in Figure 8, mesh plates 631 and 632 each include a plurality of perforations 6310 and 6320, wherein the perforations 6310 on mesh plate 631 are staggered with the perforations 6320 on mesh plate 632. That is, when viewed in the direction parallel to channel 66, the perforations 6310 on mesh plate 631 and the perforations 6320 on mesh plate 632 do not overlap.

Referring again to Figure 7 and in conjunction with Figure 9, the mesh frame 64 has an annular structure configured to allow fluid passage. In some embodiments, the mesh frame 64 is disposed within the body 61, with its outer circumference abutting the inner wall of the body 61 and its inner circumference abutting the outer surface of the channel 66. The mesh frame 64 is separated from the bottom surface 610 of the body 61 by a height difference H3. In an exemplary embodiment, the height difference H3 is greater than the height difference H2 (i.e., the lower end of the channel 66 is closer to the bottom surface 610 of the body 61 than the mesh frame 64). A plurality of annular packings 65 are distributed on the mesh frame 64. The annular packings 65 may each be a Pall ring, configured to remove water mist from the airflow. In some embodiments, as shown in FIG9, the annular packing 65 includes an annular body 651, wherein a plurality of notches 652 are formed on the annular body 651, and one edge of each notch 652 is connected to an inwardly bent blade 653.

The method by which the water mist elimination tank 60 eliminates water mist is explained as follows: First, after the composite airflow W6 enters the main body 61 through the inlet port 621, the composite airflow W6 enters the separation tank 51 in a swirling manner. Therefore, the water mist with a larger mass in the composite airflow W6 will be eliminated from the composite airflow W6 by centrifugal force. Furthermore, when the composite airflow W6 passes through the perforations of the mesh plates 631, 632, 633, 634, and 635, the staggered arrangement of the perforations will remove the water mist with a smaller mass from the composite airflow W6, thus forming a composite airflow W7 with very little water mist content. Furthermore, when the composite airflow W7 passes through the annular packing 65, the annular packing 65, due to its structural characteristics, removes most of the water mist from the composite airflow W7, forming steam W8 with little or no water mist. The steam W8, after passing through the annular packing 65 and the mesh frame 64, leaves the water mist elimination tank 60 via the channel 66 and the outlet port 622. However, it should be understood that the configuration of the water mist elimination tank 60 of this invention is not limited to the above embodiments. In some embodiments, one or both of the three mechanisms used to remove water mist in the water mist elimination tank 60 (i.e., swirling airflow, mesh plate, and annular packing) can be selectively omitted.

The water mist eliminator 60 of this invention, designed to remove water mist from a complex airflow using various mechanisms, offers at least the following technical advantages: (1) Since the water mist eliminator 60 can reduce the water mist content in the vapor W8 supplied to the gas compressor 70 to a minimum or even completely remove it, the gas compressor 70 will not be easily damaged by crystals formed by water mist. (1) The service life of the gas compressor 70 is extended and the gas compressor 70 does not need to be frequently maintained; (2) Since the expensive annular packing 65 is used to treat the complex airflow W7 with low water mist content and passing through the grid plates 631, 632, 633, 634, and 635, the service life of the annular packing 65 is extended and the annular packing 65 does not need to be frequently replaced.

Referring again to Figure 1, after leaving the water mist elimination tank 60, steam W8 is supplied to the gas compressor 70 via pipeline 108. The gas compressor 70 compresses the steam W8 to increase its pressure and temperature, converting it into high-pressure steam HG. The high-pressure steam HG is transported from the gas compressor 70 to the main heat exchanger 23 via pipeline 109, where it exchanges heat with the waste liquid W2. The high-pressure steam HG condenses in the main heat exchanger 23 to form condensate L1. The condensate L1 is then transported via pipeline 110 and pump 95 (e.g., a pneumatic pump) to the second zone 34 of the waste liquid preheating tank 30 to exchange heat with the waste liquid W1 in the first zone 33 of the waste liquid preheating tank 30, and is converted into condensate L2 with a lower temperature. The condensate L2 is then transported via pipeline 111 to the secondary heat exchanger 21 to exchange heat with the waste liquid W0, and is converted into condensate L3 with an even lower temperature. The condensate L3 is then transported via pipeline 112 to the condensate storage tank 84 for storage. Since the source of the condensate (i.e., high-pressure steam HG) no longer contains water mist (or contains only a very small amount of water mist), the water quality of the condensate produced by the mechanical vapor recompression system 1 of this embodiment is superior to that of the condensate produced by the conventional distillation system.

Referring again to Figure 1 and in conjunction with Figure 9, in some embodiments, the mist elimination tank 60 further includes a drain outlet 623 (Figure 7) and a vent. The drain outlet 623 is disposed on the bottom surface 610 of the body 61 of the mist elimination tank 60 and is configured to discharge the waste liquid accumulated by the collected mist from the mist elimination tank 60. The waste liquid from the mist elimination tank 60 is discharged through pipeline 113 to the first area 33 of the waste liquid preheating tank 30, and mixed with the waste liquid W1 before undergoing a distillation process again.

In some embodiments, at least some components of the mechanical vapor recompression system 1 are positioned at different heights, thereby reducing the area required for the mechanical vapor recompression system 1. For example, as shown in Figure 1, the water mist eliminator 60 and the gas compressor 70 of the mechanical vapor recompression system 1 are positioned above the height line LV, while the remaining components of the mechanical vapor recompression system 1 can be positioned below the height line LV, thereby reducing the space occupied by the mechanical vapor recompression system 1. The height line LV can be formed by an elevated platform (not shown).

Control device 90 is configured to control the operation of electronic components in the mechanical vapor recompression system 1. For example, control device 90 is programmed to control the operation of pumps 91, 92, 94, 95, valve 93, and gas compressor 70. Control device 90 may be a computer and includes a processor, memory, an input/output interface, a communication interface, a system bus, and other components. Control device 90 may selectively open valve 93 to supply vapor into heating tube 25 based on a detector (e.g., a thermometer installed at the first inlet port 521) installed in the mechanical vapor recompression system 1.

Table 1 shows a comparison of the energy consumption and cost of the mechanical vapor recompression system 1 of the present invention and conventional distillation equipment. Types of Distillers Energy consumption (kWh/ton) Cost (NT/ton.hr) Four-effect steamer 217~250 543~625 Heat pump distiller 290~400 725~1000 Mechanical vapor recompression system of this invention 50~85 175~213 Table 1. Energy Consumption Comparison of Distillation Equipment (1 kWh = NT$2.5)

The data shown in Table 1 demonstrate that the mechanical vapor recompression system 1 of the present invention has superior energy-saving performance compared to traditional distillation equipment. Therefore, the mechanical vapor recompression system 1 of the present invention can effectively reduce carbon emissions and save on wastewater treatment costs.

Figure 10 shows a schematic diagram of a mechanical vapor recompression system 1a according to another embodiment of this disclosure. Components in mechanical vapor recompression system 1a that are the same as or similar to those in mechanical vapor recompression system 1 will be given similar symbols, and their features will not be described further. In some embodiments, the differences between mechanical vapor recompression system 1a and mechanical vapor recompression system 1 include the omission of the branch manifold 40 and the water mist elimination tank 60 in mechanical vapor recompression system 1a. Waste liquid W3 from the main heat exchanger 23 is directly transported to the first inlet port 521 via pipeline 115 and heated to a boiling state via heating pipe 25. Therefore, when waste liquid W3 enters the separation tank 51 of the distillation gas-water separation tank 50a, the vapor W9 generated by the heating of waste liquid W3 will be separated from the concentrated waste liquid CL and transported to the gas compressor 70 for compression via pipeline 116. Since the waste liquid W3 is not heated by the heater installed in the separation tank 51, there will be no water mist from the waste liquid in the vapor W9 (or only a very small amount of water mist), and it will not cause any negative impact on the gas compressor 70.

In the embodiment where the first inlet port 521 is eccentrically positioned relative to the center C of the separator 51, since the vapor W9 swirls within the separator 51, most of the water mist within the vapor W9 will also be further expelled from the vapor W9 due to centrifugal force. Therefore, even if the water mist elimination tank 60 is omitted, concerns about damage to the gas compressor 70 due to water mist crystallization can be avoided or reduced. In other embodiments, the mechanical vapor recompression system 1 reduces the number of either the branch manifold 40 or the water mist eliminator 60, but retains the other one, thus still avoiding or reducing concerns about damage to the gas compressor 70 due to water mist crystallization.

Figure 11 shows a schematic diagram of a mechanical vapor recompression system 1b according to another embodiment of this disclosure. Components in the mechanical vapor recompression system 1b that are the same as or similar to those in the mechanical vapor recompression system 1 will be given similar symbols, and their features will not be described further. In some embodiments, the differences between the mechanical vapor recompression system 1b and the mechanical vapor recompression system 1 include the omission of the wastewater preheating tank 30 and the branch manifold 40 in the mechanical vapor recompression system 1b. During operation, wastewater W10 from the secondary heat exchanger 21 is directly transported to the primary heat exchanger 23 via pipeline 117. Furthermore, the waste liquid W11 from the main heat exchanger 23 is directly transported to the first inlet port 521 via pipeline 119. After entering the separation tank 51, the waste liquid W11 swirls within the tank to remove most of the water mist and liquid, forming a composite gas stream W12 that is discharged from the distillation gas-water separation tank 50b. The composite gas stream W12 from the distillation gas-water separation tank 50b is then supplied to the water mist elimination tank 60, where it eliminates the water mist and forms steam W13 that does not contain water mist. The steam W13 is then supplied to the gas compressor 70 for compression. Since there is no water mist from waste liquid in the steam W13, it will not have a negative impact on the gas compressor 70. In some other embodiments, the mechanical vapor recompression system 1 reduces the installation of either the waste liquid preheating tank 30 or the branch manifold 40, but retains the other one, which can still avoid or reduce concerns about damage to the gas compressor 70 due to water mist crystallization.

Gas compressor 70 compresses steam W13 to increase its pressure and temperature, converting it into high-pressure steam HG. High-pressure steam HG is transported from gas compressor 70 to main heat exchanger 23 via pipeline 109, where it exchanges heat with waste liquid W10. The high-pressure steam HG condenses in main heat exchanger 23 to form condensate L4. Condensate L4 is then transported via pipeline 118 and pump 95 (e.g., a pneumatic pump) to secondary heat exchanger 21 to exchange heat with waste liquid W0, converting it into lower-temperature condensate L5. Condensate L5 is then transported via pipeline 112 to condensate storage tank 84 for storage. Since the source of the condensate (i.e., high-pressure steam HG) no longer contains water mist (or contains only a very small amount of water mist), the water quality of the condensate produced by the mechanical vapor recompression system 1b of this embodiment is superior to that of the condensate produced by a conventional distillation system.

The foregoing has outlined the structure of several embodiments, enabling those skilled in the art to better understand the nature of the embodiments of the present invention. Those skilled in the art should understand that this disclosure is readily applicable to the design or modification of other processes and structures to achieve the same purpose and/or attain the same advantages of the embodiments introduced herein. Those skilled in the art should also recognize that such equivalent constructions should not depart from the spirit and scope of the present invention, and that various changes, substitutions, and alterations can be made to this document without departing from the spirit and scope of the present invention.

1, 1a, 1b: Mechanical vapor recompression system 21: Secondary heat exchanger 23: Primary heat exchanger 25: Heating tube 26: Shell 261: Side wall 262: End face 263: End face 27: Fluid inlet 28: Fluid outlet 29: Flow channel 30, 30a, 30b: Waste liquid preheating tank 31, 31a, 31b: Main body 32, 32a, 32b: Thermally conductive partition 33, 33a, 33b: First zone 34, 34a, 34b: Second zone 35a: Thermally conductive partition 40, 40a, 40b: Branch manifold 41, 41a, 41b: First outlet pipe 42, 42a, 42b: Second outlet pipe 43, 43a, 43b: Inlet pipe 50, 50a, 50b: Distilled gas-water separation tank 51: Main body 54: Connecting pipe 55: Storage tank 56, 57: Inspection window 60: Water mist elimination tank 61: Main body 64: Grid frame 65: Annular packing 66: Channel 67: Spacer 70: Gas compressor 81: Waste liquid source 82: Heat source 83: Dryer 84: Condensate storage tank 90: Control equipment 91, 92, 94, 95: Pump 93: Valve 101, 102, 103, 104, 105, 106, 107, 108, 109: Pipelines 110, 111, 112, 113, 114, 115, 116, 117, 118, 119: Pipelines 510: Bottom surface 511: Top surface 512: Side wall 521: First inlet port 522: Second inlet port 523: Outlet port 550: Bottom surface 551: Top surface 552: Drainage hole 610: Bottom surface 611: Top surface 612: Side surface 621: Inlet port 622: Outlet port 623: Drainage outlet 631, 632, 633, 634, 635: Grid plate 651: Annular body 652: Notch 653: Blade 6310, 6320: Perforation 6315, 6325, 6335, 6345, 6355: Opening a1: First angle a2: Second angle CL: Concentrated waste liquid D1: Spacing G1: Heating steam H1, H2, H3: Height difference HG: High-pressure steam L1, L2, L3, L4, L5: Condensate LV: Height line T0, T1, T2, T4: Long axis W0, W1, W2, W3, W4, W10, W11: Waste liquid W5, W8, W9, W13: Steam W6, W7, W12: Complex airflow

The following [Implements] are best understood by reading in conjunction with the drawings. It should be noted that, according to industry standard practice, the structures are not drawn to scale. In fact, the dimensions of the structures can be arbitrarily increased or decreased for clarity of discussion.

Figure 1 shows a schematic diagram of a mechanical vapor recompression system according to a first embodiment of the present invention.

Figures 2A, 2B, and 2C show top views of a waste liquid preheating tank according to some embodiments of the present invention.

Figure 3A shows a schematic diagram of some components of a mechanical vapor recompression system according to a partial embodiment of the present invention.

Figure 3B shows a schematic diagram of a bifurcation manifold according to a partial embodiment of the present invention.

Figure 3C shows a schematic diagram of a bifurcation manifold according to a partial embodiment of the present invention.

Figure 4 shows a schematic diagram of a distillation gas moisture separation tank according to a partial embodiment of the present invention.

Figure 5 shows a cross-sectional schematic diagram of a distillation gas-moisture separation tank according to a partial embodiment of the present invention.

Figure 6A shows a schematic diagram of a heating tube according to a partial embodiment of the present invention.

Figure 6B shows a schematic cross-sectional view of a heating tube according to a partial embodiment of the present invention.

Figure 7 shows a cross-sectional schematic diagram of a water mist elimination bucket according to a partial embodiment of the present invention.

Figure 8 shows a cross-sectional schematic diagram of a plurality of grid plates according to a portion of the present invention.

Figure 9 shows a schematic diagram of a Pauel ring according to a partial embodiment of the present invention.

Figure 10 shows a schematic diagram of a mechanical vapor recompression system according to a second embodiment of the present invention.

Figure 11 shows a schematic diagram of a mechanical vapor recompression system according to a third embodiment of the present invention.

50: Distillation gas-moisture separation tank 51: Main body 54: Connecting pipe 55: Storage tank 56, 57: Inspection window 510: Bottom surface 511: Top surface 512: Side wall 521: First inlet port 522: Second inlet port 523: Outlet port 550: Bottom surface 551: Top surface 552: Discharge port CL: Concentrated waste liquid H1: Height difference W4: Waste liquid W5: Vapor W6: Combined airflow

Claims (10)

A water mist elimination tank is suitable for removing water mist from an airflow originating from a separator in a mechanical vapor recompression system. The water mist elimination tank comprises: a body having a hollow structure and including an inlet port and an outlet port; a channel having a first end and a second end, wherein the first end is connected to the outlet port, and the channel extends within the body away from the outlet port toward a bottom surface of the body to the second end; and a plurality of mesh plates disposed within the body and below the inlet port, wherein each of the mesh plates includes a plurality of perforations allowing fluid to pass through, wherein the second end of the channel is closer to the bottom surface of the body than the one of the plurality of mesh plates closest to the bottom surface of the body. The water mist elimination tank as described in claim 1 further comprises: a mesh frame disposed within the body and spaced from the bottom surface of the body by a second height difference, wherein the second end of the channel has a first height difference with the bottom surface of the body, and the second height difference is greater than the first height difference; and a plurality of annular packing materials distributed on the mesh frame, the annular packing materials being configured to remove water mist from the airflow. The water mist elimination bucket as described in claim 1, wherein the inlet port of the water mist elimination bucket is offset from the center of the body. The water mist eliminating bucket as described in any of claims 1-3, wherein the perforations of two of the adjacent grid panels are staggered. The water mist elimination bucket as described in any of claims 1-3, wherein the body is a hollow cylindrical structure, the first end of the outlet port is connected to a top surface of the body and extends toward the bottom surface of the body to the second end in a direction away from the outlet port, and wherein each of the mesh plates has an annular structure, the outer circumference of the mesh plates abuts against the inner wall surface of a side of the body, and the inner circumference of the mesh plates abuts against the outer surface of the channel. A water mist eliminator is suitable for removing water mist from an airflow originating from a separator in a mechanical vapor recompression system. The water mist eliminator comprises: a body having a hollow structure and including an inlet port and an outlet port; a channel having a first end and a second end, wherein the first end is connected to the outlet port, and the channel extends within the body away from the outlet port toward a bottom surface of the body to the second end, the second end of the channel having a first height difference with respect to the bottom surface of the body; a mesh frame disposed within the body and spaced from the bottom surface of the body by a second height difference, the second height difference being greater than the first height difference; and a plurality of annular packings distributed on the mesh frame, the annular packings being configured to remove water mist from the airflow. The water mist elimination bucket as described in claim 6, wherein the channel is a hollow tube, and the water mist elimination bucket further includes: a plurality of mesh plates disposed within the body and located below the inlet port, wherein each of the mesh plates includes a plurality of perforations allowing fluid to pass through, each of the mesh plates defining an opening, the channel passing through the openings of the mesh plates, wherein the second end of the channel is closer to the bottom surface of the body than one of the plurality of mesh plates that is closest to the bottom surface of the body. The water mist eliminator as described in claim 7, wherein the inlet port of the water mist eliminator is offset from the center of the body. The water mist elimination tank as described in any of claims 6-8, wherein each of the annular fillers includes an annular body, wherein a plurality of notches are formed on the annular body, and one edge of each of the notches is connected to an inwardly bent blade. The water mist eliminating bucket as described in any of claims 6-8, wherein the body is a hollow cylindrical structure, the first end of the outlet port is connected to a top surface of the body and extends toward the bottom surface of the body to the second end in a direction away from the outlet port, and wherein the mesh frame has an annular structure, the outer circumference of which abuts against a side surface of the body and the inner circumference abuts against the outer surface of the channel.