WO2023016619A1

WO2023016619A1 - Frames for a multi-stage flash evaporation and condensation system and system comprising said frames

Info

Publication number: WO2023016619A1
Application number: PCT/EP2021/000096
Authority: WO
Inventors: Tobias HEINZL
Original assignee: Heinzl, Wolfgang
Priority date: 2021-08-12
Filing date: 2021-08-12
Publication date: 2023-02-16

Abstract

The present disclosure relates to a frame (1) configured to be used in a flash evaporation unit (50) of a membrane-less multi-stage flash evaporation and condensation system. The frame (1) comprises a circumferential section (2), a central section (4) and an intermediate section (3) arranged between the circumferential section (2) and the central section (4). The intermediate section (3) comprises multiple through holes extending from the front side (F) to the back side (B) of the frame (1). The multiple through holes comprise a first feed through hole (5), a second feed through hole (6), a vapor through hole (20, 21), a brine flash through hole (7), and a distillate through hole (8, 9). The intermediate section (3) further comprises a droplet separator receiving section (43) fluidly connecting the brine flash through hole (7) and the vapor through hole (20, 21) and being configured to to prevent droplets from flowing from the brine flash through hole (7) to the vapor through hole (20, 21). Further, the present disclosure relates to a membrane-less multi-stage flash evaporation and condensation system.

Description

FRAMES FOR A MULTI-STAGE FLASH EVAPORATION AND CONDENSATION SYSTEM AND SYSTEM COMPRISING SAID FRAMES

Description

Technical Field

[01] The present disclosure generally relates to the field of treatment and purification of liquids such as for example wastewater and more particularly, it relates to a frame for a membrane-less multi-stage flash evaporation and condensation system and to a membrane-less multi-stage flash evaporation and condensation system.

Background

[02] Most conventional evaporation and condensation systems are constructed from high-cost stainless steel or titanium to prevent corrosion in the high-pressure, high-temperature environment in which the evaporation and condensation systems operate.

[03] As an alternative, plastic based evaporation and condensation systems have been developed. Such systems are not prone to corrosion and plastic materials are cheaper than high-cost stainless steel or titanium.

[04] Known plastic based evaporation and condensation systems can be categorized in multi-effect (ME) evaporation and condensation systems and in multi-stage flash (MSF) evaporation and condensation systems.

[05] ME evaporation and condensation systems are characterized in that for the distillate production, vapor condenses on a surface of a heat conductive element such as a foil. The foil transfers the condensation heat to the opposite side of the foil and the condensation heat produces new vapor. Consequently, vapor on a first side of the foil directly produces other vapor on a second side of the foil. [06] To the contrary, MSF evaporation and condensation systems are characterized in that for the distillate production, vapor condenses on a surface of a heat conductive element such as a foil. The foil transfers the condensation heat to the opposite side of the foil and preheats the water to be treated. The water to be treated is further preheated by, e.g., a heat exchanger, and then flows into an evaporation unit of the MSF evaporation and condensation system where it at least partly evaporates. Consequently, vapor on a first side of the foil does not directly produce other vapor on a second side of the foil, but only preheats the water to be treated which is evaporated in a subsequent stage.

[07] Usually, ME evaporation and condensation systems and MSF evaporation and condensation systems comprise multiple evaporation and condensation units. An evaporation and condensation unit is characterized by a certain temperature and pressure level which differs from the temperature and pressure level of another evaporation and condensation unit of that system.

[08] Plastic based ME and MSF evaporation and condensation systems are known which comprise multiple frames made from plastic material which are stacked together to form a unit of the evaporation and condensation system. Usually, such systems use a thin membrane, which is arranged between two frames of the system, to filter vapor. The vapor passes the membrane in stacking direction of the frames. The membrane is a thin film which allows vapor to pass through but hinder droplets to pass through. Thus, the quality of the distillate may be increased as the vapor is free of (wastewater) droplets.

[09] WO 2018/232709 Al discloses a membrane-less MSF evaporation and condensation system. The system comprises a flash evaporation unit, an external heat source and a vacuum pump. The heat source is used to preheat the feed to be treated. The vacuum pump is used to put the flash evaporation unit in vacuum. Each flash evaporation unit comprises a plurality of modular frames. The plurality of modular frames comprises a flash evaporator frame, a condenser frames and a preheater frame. The flash evaporator frame, the condenser frame and the preheater frame are modular frames. Being modular means that the frames have the same basic design which can be adapted to different configurations by minor adjustments. The basic design includes multiple through holes and a central grid surrounded by the multiple through holes. Depending on whether the frame is configured to be a flash evaporator frame, a condenser frame or a preheater frame, selected through holes of the multiple through holes are fluidly connected to the central grid. The modular frames are stacked together to form a stack. The flash evaporation unit of the MSF evaporation and condensation system comprises such stack of modular frames and further comprises a cover and configuration plate which is arranged at the beginning and the end of the stack. Further, the flash evaporation unit of the MSF evaporation and condensation system comprises liquid-impermeable films which are arranged between adjacent modular frames of the stack. Accordingly, this system requires three different frames, i.e. a flash evaporator frame, a condenser frame and a preheater frame. Hence, the manufacturing costs may be high.

[10] The present disclosure is directed, at least in part, to improving or overcoming one or more aspects of known MSF evaporation and condensation systems. Especially, it is an object of the present disclosure to provide a cost efficient and compact membrane-less MSF evaporation and condensation system, which produces distillate of high quality.

Summary of the Disclosure

[11] According to one aspect, the present disclosure relates to a frame configured to be used in a flash evaporation unit of a membrane-less multi-stage flash evaporation and condensation system. The frame has a front side and a back side and comprises, viewed in a front view, a circumferential section, a central section and an intermediate section. The circumferential section is configured to provide mechanical stability to the frame. The central section is surrounded by the circumferential section and has an upper side, a lower side, a left side and a right side. The central section is configured to allow flow of a feed from the upper side to the lower side of the central section and vice versa and to allow flow of a vapor from the left side towards the right side and/or from the right side towards the left side of the central section. The intermediate section is arranged between the circumferential section and the central section. The intermediate section comprises multiple through holes which extend from the front side to the back side of the frame. The multiple through holes comprise a first feed through hole arranged above the central section. Further, the multiple through holes comprise a second feed through hole arranged below the central section and a vapor through hole arranged beside the central section. Further, the multiple through holes comprise a brine flash through hole arranged below the vapor through hole, and a distillate through hole arranged adjacent to the lower side of the central section. The intermediate section further comprises a droplet separator receiving section. The droplet separator receiving section fluidly connects the brine flash through hole and the vapor through hole and is configured to receive a droplet separator. The droplet separator is configured to prevent droplets from flowing from the brine flash through hole to the vapor through hole.

[12] According to another aspect, the present disclosure relates to a membrane-less multi-stage flash evaporation and condensation system. The membrane-less multi-stage flash evaporation and condensation system comprises at least one flash evaporation unit. The flash evaporation unit comprises a stack of frames. The stack of frames includes one or more first frames and one or more second frames. Between a first frame and a second frame a heat conductive and liquid impermeable film is arranged such that it separates the central section from adjacent frames.

[13] Further, the flash evaporation unit comprises a droplet separator configured to be inserted into the droplet separator receiving sections of the one or more first frames and the one or more second frames. [14] The first frame has a front side and a back side and comprises, viewed in a front view, a circumferential section, a central section and an intermediate section. The circumferential section is configured to provide mechanical stability to the frame. The central section is surrounded by the circumferential section and has an upper side, a lower side, a left side and a right side. The central section is configured to allow flow of a feed from the upper side to the lower side of the central section and vice versa and to allow flow of a vapor from the left side towards the right side and/or from the right side towards the left side of the central section. The intermediate section is arranged between the circumferential section and the central section. The intermediate section comprises multiple through holes which extend from the front side to the back side of the frame. The multiple through holes comprise a first feed through hole arranged above the central section. Further, the multiple through holes comprise a second feed through hole arranged below the central section and a vapor through hole arranged beside the central section. Further, the multiple through holes comprise a brine flash through hole arranged below the vapor through hole, and a distillate through hole arranged adjacent to the lower side of the central section. The intermediate section further comprises a droplet separator receiving section. The droplet separator receiving section fluidly connects the brine flash through hole and the vapor through hole and is configured to receive a droplet separator. The droplet separator is configured to prevent droplets from flowing from the brine flash through hole to the vapor through hole.

[15] The droplet separator receiving section comprises one or more guiding elements such as for example a nose, protrusion or groove, configured to be connected to a complementary formed section of a droplet separator.

[16] The first frame further comprises a first set of through hole connecting channels which fluidly connects the vapor through hole to the left side or right side of the central section by means of a vapor connecting channel and the central section to the distillate through hole by means of a distillate connecting channel.

[17] The second frame comprises all features of the first frame with the exception of the first set of through hole connecting channels. The second frame does not comprise the first set of through hole connecting channels. In contrary, the second frame comprises a second set of through hole connecting channels which fluidly connect the first feed through hole to the upper side of the central section and the second feed through hole to the lower side of the central section by means of feed connecting channels.

[18] According to another aspect, the present disclosure relates to a membrane-less multi-stage flash evaporation and condensation system. The membrane-less multi-stage flash evaporation and condensation system comprises at least one flash evaporation unit. The flash evaporation unit comprises a stack of frames. The stack of frames includes one or more third frames and one or more fourth frames. Between a third frame and a fourth frame a heat conductive and liquid impermeable film is arranged such that it separates the central section from adjacent frames.

[19] The third frame has all features of the above disclosed first frame with the exception of the embodiment of the droplet separator receiving section and the third frame comprises the additional feature of a droplet separator. In more precise terms, this means that the droplet separator receiving section of the third frame is not specified by comprising one or more guiding elements such as for example a nose, protrusion or groove, configured to be connected to a complementary formed section of a droplet separator. Further, it means that the third frame comprises a droplet separator being received by the droplet separator receiving section.

[20] The fourth frame comprises all features of the third frame with the exception of the first set of through hole connecting channels. The fourth frame does not comprise the first set of through hole connecting channels. [21] In contrary, the fourth frame comprises a second set of through hole connecting channels which fluidly connect the first feed through hole to the upper side of the central section and the second feed through hole to the lower side of the central section by means of feed connecting channels.

[22] The present disclosure is based at least in part on the realization that the number of different parts of a plastic based membrane-less MSF evaporation and condensation system can be improved by integrating the process of feed evaporation and vapor condensation in one single frame. Further, it has been realized that the quality of distillate can be improved by integrating a droplet separator in that one single frame to separate droplets from the vapor which creates the distillate by condensation.

[23] The integration of the droplet separator may be realized by integrating a “small” droplet separator into every single frame or alternatively may be realized by integrating a “large” droplet separator into more than one single frame by insertion.

[24] Membrane-less means that the MSF evaporation and condensation system does not comprise a membrane, which is a microporous thin film arranged between two adjacent frames of the system and filtering vapor which passes the membrane in stacking direction of the two adjacent frames.

[25] For the first time ever, a brine flash through hole, in which liquid evaporates/flashes, a vapor through hole, in which vapor is collected, and a central section, in which the vapor condenses, are arranged in one frame such that the vapor can flow from the brine flash through hole of the frame over the vapor through hole of the same frame into the central section of the same frame for condensation.

[26] Further, it has been realized that by arranging a droplet separator between the brine flash through hole and the vapor through hole, the quality of the distillate can be increased as the droplet separator hinders droplets to flow from the brine flash through hole into the vapor through hole. The droplet separator is arranged such that vapor must pass the droplet separator when flowing upwards from the brine flash through hole to the vapor through hole, the vapor through hole being arranged above the brine flash through hole.

[27] The droplet separator is configured to filter the vapor which has a flow direction from the bottom to the top of the central section of the frame. The droplet separator filters the vapor within one frame.

[28] In an exemplary embodiment according to the present disclosure, the droplet separator receiving section receives a droplet separator. The droplet separator extends from the front side of the frame to the back side of the frame. The droplet separator receiving section for example may be formed in a pocket shape in which the droplet separator may be inserted. The pocket is integrally formed with the frame and comprises an inlet at the bottom and an outlet at the top. By means of insertion of the droplet separator, the filter material is provided within the pocket. The vapor to be filtered, enters the pocket through the inlet, passes the filter material and leaves the casing at the outlet. According to this embodiment every droplet separator receiving section of every frame comprises a single droplet separator. The droplet separator and the droplet separator receiving section are configured such that in inserted state the connection between the droplet separator and the droplet separator receiving section, e.g. the pocket, is fluid tight.

[29] As an alternative, the droplet separator receiving section comprises one or more guiding elements such as a nose, protrusion or groove, configured to be connected to a complementary formed section of a droplet separator. The droplet separator in that case comprises a casing with the complementary formed section such that the droplet separator may be inserted, preferably in stacking direction into a stack of frames. The droplet separator extends over at least two adjacent frames, preferably over the entire length of the stack of frames in stacking direction. This alternative is beneficial in terms of manufacturing and exchangeability. When inserting the droplet separator between the brine flash through hole and the vapor through hole, it is important to ensure that the droplet separator fits tightly in the droplet separator receiving section such that the vapor cannot bypass the droplet separator when flowing from the brine flash through hole into the vapor through hole.

[30] A droplet separator according to the present disclosure may comprise a casing in which the filter material is embedded. Especially in an embodiment in which the droplet separator is inserted into a stack of frames and extends over more than one frame, the droplet separator may have a rigid casing which comprises the complementary formed section to the droplet separator receiving section.

[31] The circumferential section of the frame is configured to provide mechanical stability to the entire frame. The circumferential section of the frame provides sufficient stability to the frame that the frame withstand the forces caused by the pressure differences inside of the frame and the ambient pressure outside the frame when the frame is installed in a MSF evaporation and condensation system which is in operation.

[32] The liquid and vapor flow in the multiple through holes of the intermediate section. When multiple frames are stacked together, the multiple through holes of the plurality of frames form multiple fluid channels in stacking direction. Such fluid channels extend in stacking direction and provide the fluid channels for the liquid and vapor within the stack. The through hole connecting channels preferably extend in a direction perpendicular to the stacking direction. By means of the through hole connecting channels, selected through holes of the frame are connected to the central section. Consequently, the fluid channels formed of these selected through holes are connected to the central section as well.

[33] The central section is configured to allow the flow of a feed from the upper side to the lower side of the central section and vice versa, and the flow of a vapor from the left side towards the right side and/or from the right side towards the left side of the central section. The central section has the function to distribute water and vapor within the central section, the water and vapor entering the central section on the upper side/lower side/right side/left side. The central section may comprise a plurality of flow channels allowing water to flow in up- down direction and allowing vapor to flow in left-right direction.

[34] The present disclosure is based at least in part on the realization that the stack of a flash evaporation unit can comprise only two different configurations of a (basic) frame. The (basic) frame is designed to be modular. Modular means that the basic design of the frame can be adapted by providing a first set or a second set of through hole connecting channels. By providing the first set of through hole connecting channels, the frame is configured to be an evaporation-condensation frame. By providing the second set of through hole connecting channels, the frame is configured to be a preheat frame. At least one of such an evaporation-condensation frame and at least one of such a preheat frame are stacked together to form the stack.

[35] The evaporation-condensation frame is characterized in that it comprises a first set of through hole connecting channels which fluidly connect the vapor through hole to the left side or right side of the central section by means of a vapor channel, and the central section to the distillate through hole by means of a distillate connecting channel.

[36] The preheat frame is characterized in that it comprises a second set of through hole connecting channels which fluidly connect the first feed through hole to the upper side of the central section and the second feed through hole to the lower side of the central section by means of feed connecting channels.

[37] A flash evaporation unit further comprises a cover and configuration plate at the beginning and the end of the stack of frames. The cover and configuration plate is configured to allow fluid to enter/exit the stack only at certain positions, such that some of the fluid channels with a stack of frames are blocked. Fluid channels are formed by the through holes of the frames in stacking direction.

[38] The cover and configuration plate may for example be a flat body which has approximately the same dimensions as the modular frame. The flat body comprises through holes that are arranged such that some of the fluid channels are blocked by the cover and configuration plate.

[39] Alternatively, the cover and configuration plate may for example comprise the same basic design as the modular frame. In contrary to the modular frame, some of the through holes as well as the central section are closed. Such exemplary embodiment may be advantageous in terms of manufacturing as -for example with injection molding- the basic design of the frame may be manufactured in which the presence of through holes and the central section is modified. To prevent the flow through the central section, for example, the central section of a cover and configuration plate may be closed with a heat conductive and liquid impermeable film which covers the central section on both sides.

[40] Evaporation and condensation systems usually will comprise multiple of such flash evaporation units which may differ in number and arrangement of frames. In addition, evaporation and condensation systems will comprise external periphery devices such as for example an external heat source and a vacuum pump.

[41] Preferably, frames with the same basic construction are used within a stack of frames. The same basic construction allows that flow channels with uniform cross-sectional area within the stack are formed by the multiple through holes of the frames and that a tight connection between the frames may be realized.

[42] Preferably, the frame is manufactured as a single injection molded part. The frame is made of plastics. All polymers that can be processed by injection molding may be used as material for the frame, e.g., PE, PP, PVDF. [43] According to an exemplary embodiment, the frame has a width of 550 - 950 mm, preferably 700 - 800 mm.

[44] According to an exemplary embodiment, the frame has a height of 700 -1300 mm, preferably 850 - 1100 mm.

[45] According to an exemplary embodiment, the frame has a depth of 3 - 10 mm, preferably 4.5 - 8 mm.

[46] With the present disclosure a cost efficient and compact membrane-less MSF evaporation and condensation system for treatment and purification of liquids such as for example waste water, waste solutions or salt water or any other treatment process that improves the quality of a liquid (solution) to make it appropriate for a specific end-use is provided.

[47] The following section describes exemplary embodiments according to the present disclosure of the frame and of the membrane-less multistage flash evaporation and condensation system.

[48] In an exemplary embodiment according to the present disclosure, the evaporation and condensation frames and the preheat frames in a stack of multiple frames are arranged alternately in stacking direction. Alternately in stacking direction means that the evaporation and condensation frames and the preheat frames within the stack are arranged such that the front side of an evaporation and condensation frame faces the back side of an adjacent preheat frame, respectively the back side of an evaporation and condensation frame faces the front side of an adjacent preheat frame.

[49] In an exemplary embodiment according to the present disclosure, the stack of frames comprises a first distillate channel on the left side of the central section and a second distillate channel on the right side of the central section. A first cover and configuration plate at the beginning of the stack of frames blocks the flow of distillate into or out of the first distillate channel and a second cover and configuration plate at the end of the stack of frames blocks the flow of distillate into or out of the second distillate channel. [50] The distillate channels are formed of the distillate through holes of the multiple frames which are stacked together and extend from the front side of the stack to the back side of the stack.

[51 ] Such a configuration of cover and configuration plates allows a zic-zac flow of the distillate in multiple flash evaporation units. Due to this configuration, distillate has to cross the central section of the evaporationcondensation frame as only the left respectively the right distillate channel is fluidly connected with a distillate channel of the next flash evaporation unit.

[52] Due to the crossing of the central section by the distillate, noncondensable gases may also be moved and flow with the distillate into the distillate channels. When the feed is heated, the non-condensable gases are released, flow with the vapor stream into the central area of the condensation frame and accumulate there. The non-condensable gases are heavier than vapor and accumulate in the lower portion of central section of the condensation frame. If the distillate flows from one side to the other, the non-condensable gases are also moved and flow with the distillate into the distillate channels.

[53] In an exemplary embodiment according to the present disclosure, the cover and configuration plate comprises an air shortcut opening configured to allow the flow of air in or out of the first feed channel of the stack of frames.

[54] Such air shortcut opening may for example be a through bore with a diameter of 1-7 mm, preferably 2-5 mm.

[55] In an exemplary embodiment according to the present disclosure, the brine flash through hole has a width extending in parallel to the direction from the left side of the central section to the right side of the central section. The one or more vapor through holes each have a width. The ratio of the width of the brine flash through hole (B7) to the sum of the width of the one or more vapor through holes (B20, B21) is in the range of 1.5 to 4, more preferably in the range of 2-3.2, viewed in a front view of the frame. In a formula this feature reads as: B7 / S (B20, B21) = 1.5-4 resp. B7 / S (B20, B21) - 2-3.2.

[56] With such a ratio, advantageous vapor flow velocities for the process may be obtained in the vapor channels (formed by the vapor through holes of the frames of the stack of frames of a stage). Consequently, an effective evaporation and condensation process may be realized. In multi-stage plants, approximately equal vapor mass flow rates occur in each stage. However, the vapor volume increases toward low temperatures and thus the vapor velocities in each stage increase in the direction of decreasing temperature. As an example, in a system comprising eight stages with an operating temperature of 80°C in the first stage and an operating temperature of 30°C in the final stage, the speeds significantly differ depending on the temperature at which the stage operates.

[57] At about 80°C, the preferred speeds are in the range of 2 to 8 m/sec, preferably in the range of 3 to 5 m/sec.

[58] At about 30°C, the preferred speeds are in the range of 25 to 55 m/sec, preferably in the range of 35 to 45 m/sec. These differences in velocity result from the significantly larger spec, volume of the vapor at 30 °C than at 80 °C.

[59] A ratio in the above identified range has been proven to deliver a good and effective interaction of the two through holes and effectiveness of the flash evaporation unit.

[60] In an exemplary embodiment according to the present disclosure, the droplet separator comprises a mesh made out of a polymer or metal.

[61] For the droplet separator any filter structure can be used which allows that vapor flows through it while droplets are hindered to flow through it. For the droplet separator for example a mash out of a polymer or metal can be sufficient. If the boiling feed tends to create foam as for example spent wash a more selective filter structure is needed. This can for example be a filter cartridge with a pleated filter material out of a microporous, Polymer as expanded PTFE. [62] The droplet separator may comprise a mesh made out of metal, e.g. steel 1.4301, steel 1.4541, steel 1.4401, steel 1.4571, Monel, Nickel, Titan or Tantal with a specific surface of 150 - 600 m²/m³. The droplet separator may comprise a mesh made out of polymer, e.g. PE, PP or PVC with a specific surface of 500 - 1100 m²/m³.

[63] Generally, it is aimed for a high separation efficiency of the droplet separator. Depending of the application the frame is used for, the droplet separator may retain droplets down to a droplet size of e.g. 2pm. As an example, the droplet separators according to type T-01-M, T-02-M, T-03-M, T-10-M, T- 20-M, T-30-M, T-01-P, T-02-P, T-03-P offered by company “Vereinigte Fiillkorper-Fabriken GmbH&Co. KG” at the time of filing the application regarding the present disclosure may be used as droplet separator according to the present disclosure.

[64] As further examples, as the droplet separator the following products available at the time of filing the application regarding the present disclosure may be used: wire mesh mist eliminator of company RVT, droplet separator made of PVC-U, PP, PPs, PE and PVDF (type series TA 125-2 I TA125-2-S, TA 125-2-A / TA 125-2-A-S) of company KWERK GmbH, wire mesh filter / droplet separator made of steel, galvanised steel, aluminium, stainless steels of all kinds, copper, plastics in fibres and threads (PP, PE, etc.) of company Bode Industrievertretung GmbH, or plastic wire mesh type DA of company SKT Schrupp GmbH.

[65] In an exemplary embodiment according to the present disclosure, the frame comprises a first distillate through hole on the left side of the central section and a second distillate through hole on the right side of the central section.

[66] Such arrangement allows that distillate can flow from the first distillate through hole to the second distillate through hole by crossing the central section of the frame. By the provision of a cover and configuration plate between two such frames, the distillate may be forced to cross the central section in order to flow out of the first or second distillate through hole. The cover and configuration plate in this case includes only one distillate passage for the first distillate through hole on the left side of the central section or the second distillate through hole on the right side of the central section.

[67] In an exemplary embodiment according to the present disclosure, the central section comprises a grid with a plurality of central section flow channels configured to distribute water and vapor in the central section of the frame.

[68] A grid is a simple construction which allows to distribute water and vapor in the central section. The grid further may be used to support a heat conductive and liquid impermeable film which is attached to the frame.

[69] In an exemplary embodiment according to the present disclosure, on the front side and /or back side of the frame a heat conductive and liquid impermeable film is attached such that it covers the central section.

[70] The heat conductive and liquid impermeable film may for example be attached to the frame by means of sealing or gluing. Any method to fluidly tight connect the heat conductive and liquid impermeable film to the frame may be used. The heat conductive and liquid impermeable film is made of plastics. Preferably, the heat conductive and liquid impermeable film is made of PE, PP, PVDF. For a good heat transfer and sufficient mechanical strength, the thickness of the heat conductive and liquid impermeable film is in the range of 5 pm to 100 pm, preferably in the range of 10 pm to 20 pm.

[71] The heat conductive and liquid impermeable film may be attached on one side or on both sides of a frame. The heat conductive and liquid impermeable film may be attached to the preheat frame and/or the evaporationcondensation frame. The heat conductive and liquid impermeable film is attached to the multiple frames such that it covers the central section of the frame. In a stack formed of these frames, the central section of each frame is enclosed by two heat conductive and liquid impermeable films.

[72] In an exemplary embodiment according to the present disclosure, the frame further comprises an internal frame which surrounds the central section and separates the intermediate section from the central section, wherein the heat conductive and liquid impermeable film is attached to the internal frame.

[73] The internal frame may provide a surface to which the heat conductive and liquid impermeable film may for example be attached by means of sealing or gluing.

[74] In an exemplary embodiment according to the present disclosure, the internal frame is fixed to the circumferential section of the frame by means of fixation bars. The fixation bars comprises a S-shape or a multi S-shape.

[75] With the S-shape or the multi S-shape a design is used which may allow to reduce deformations of the internal frame caused by a deformation of the circumferential section.

[76] In an exemplary embodiment according to the present disclosure, a reinforcement structure is provided in a through hole of the multiple through holes. The reinforcement structure has a depth which extends over 25% to 75%, preferably over 40% to 60% of the frame depth from the front side to the back side of the frame, such that the remaining part of the frame depth is available as useable volume of the through hole.

[77] The reinforcement structure may provide additional mechanical stability to the frame. In contrast to the circumferential section of the frame, the reinforcement structure has a width which does not extend over the full distance from the front side to the back side of the frame. Accordingly, part of the distance from the front side to the back side is available as useable volume.

[78] In an exemplary embodiment according to the present disclosure, the reinforcement structure is provided in the brine flash through hole and/or in the vapor through hole. [79] Due to the pressure/the mechanical load conditions, especially the provision of the reinforcement structure in the flash through hole and/or in the vapor through hole may be advantageous to improve the mechanical stability of the frame.

[80] Other features and aspects of this disclosure will be apparent from the following description and the accompanying drawings.

Brief Description of the Drawings

[81] Fig. 1 illustrates a frame according to a first embodiment of the present disclosure in a simplified structure.

[82] Fig. 2 illustrates the frame of Fig. 1 including a droplet separator (the droplet separator is shown in cross-sectional view).

[83] Fig. 3 is a cross-sectional view of the frame of Fig. 1 and Fig. 2 along line A-A.

[84] Fig. 4 illustrates a stack of five frames according to the first embodiment shown in Fig. 1.

[85] Fig. 5 illustrates a frame according to a second embodiment of the present disclosure in a simplified structure, a so called evaporation-condensation frame 100.

[86] Fig. 6 illustrates a frame according to a third embodiment of the present disclosure in a simplified structure, a so called preheat frame 200.

[87] Fig. 7 illustrates a flash evaporation unit 50 of a membrane-less multi-stage flash evaporation and condensation system comprising a frame 100 according to Fig. 4 and a frame 200 according to Fig. 5

[88] Fig. 8 illustrates the flash evaporation unit 50 of Fig. 6 and indicates the flow of feed 28 and brine 22 within the flash evaporation unit 50 when it is in operation. [89] Fig. 9 illustrates the flash evaporation unit 50 of Fig. 6 and indicates the flow of brine 22 and vapor 15 within the flash evaporation unit 50 when it is in operation.

[90] Fig. 10 illustrates the flash evaporation unit 50 of Fig. 6 and indicates the flow of distillate 16 within the flash evaporation unit 50 when it is in operation.

[91] Fig. 11 illustrates an exemplary embodiment of the droplet separator receiving section according to the present disclosure.

[92] Fig. 12 illustrates an exemplary embodiment of frames 100 according to Fig. 4 and frames 200 according to Fig. 5 within two flash evaporation units 50 of a MSF evaporation and condensation system which are connected in series.

[93] Fig. 13 illustrates an evaporation-condensation frame 400 according to a further embodiment of the present disclosure. With arrows the flow of brine 22, vapor 15 and distillate 16 is indicated when the frame 400 is installed in an evaporation and condensation system which is in operation.

[94] Fig. 14 illustrates a preheat frame 500 according to a further embodiment of the present disclosure. With arrows the flow of feed 28 is indicated when the frame 500 is installed in an evaporation and condensation system which is in operation.

Detailed Description

[95] Fig. 1 illustrates a frame 1 according to a first embodiment of the present disclosure in a simplified structure. The frame 1 comprises three sections, which are the circumferential section 2, the intermediate section 3 and the central section 4.

[96] The circumferential section 2 encloses the intermediate section 3 and the central section 4. The intermediate section 3 comprises multiple through holes. The multiple through holes of the intermediate section 3 comprise a first feed through hole 5, which is arranged above the central section a second feed through hole 6 arranged below the central section 4. Further, the multiple through holes comprise a brine flash through hole 7 which to a large extend is arranged below the second feed through hole 6 and extends on both sides of the second feed through hole 6 in upward direction.

[97] Further, the multiple through holes comprise a first vapor through hole 20 arranged on the left side of the central section 4 and a second vapor through hole 21 arranged on the right side of the central section. Each of the first vapor through hole 20 and the second vapor through hole 21 is fluidly connected to the brine flash through hole 7 by means of a droplet separator receiving section

43. The droplet separator receiving section is configured to receive a droplet separator 42. The droplet separator receiving section comprises guiding elements

44. The guiding elements 44 have the form of protruding noses. The guiding elements are integrally formed with the frame.

[98] Each of the vapor through holes 20, 21 has a width B20, B21. The brine flash through hole 7 has a width B7. The width is measured viewed in the left - right direction of the frame.

[99] Further, the multiple through holes comprise two distillate through holes 8, 9 which are arranged on a left lower portion of the central section 4 respectively on a right lower portion of the active section 4.

[100] Within the central section 4 the flow of a feed 28 from the upper side to the lower side of the central section 4 and vice versa is indicated with an arrow. Further, the flow of a vapor 15 from the left side towards the right side and from the right side towards the left side of the central section 4 is indicated with arrows.

[101] Fig. 2 corresponds to Fig. 1 but further comprises a droplet separator. The droplet separator is shown in a cross sectional view. The droplet separator is inserted between the protruding noses 44. Vapor which flows from the brine flash through hole into the vapor through hole has to pass the droplet separator 42.

[102] Fig. 3 is a cross-sectional view of the frame of Fig. 1 and Fig. 2 along line A- A. The first feed through hole 5, the second feed through hole 6 and the brine flash through hole extend from the front side F of the frame to the back side (B) of the frame. Within the central section 4 the flow of a feed 28 from the upper side to the lower side of the central section 4 and vice versa is indicated with an arrow.

[103] Fig. 4 illustrates a stack of frames (five) 48 according to the first embodiment shown in Fig. 1. The stack of frames is not functional in a MSF evaporation and condensation system as the frame does not comprise any through hole connecting channels. Fig. 3 intends to illustrate the forming of fluid channels 49 in the stack of frames by means of the through holes of the frames 1.

[104] Fig. 5 illustrates a frame according to a second embodiment of the present disclosure in a simplified structure, a so called evaporation-condensation frame 100.

[105] The embodiment of Fig. 5 corresponds to the embodiment of Fig. 2, but further comprises a first set of through hole connecting channels. The first set of through hole connecting channels comprise a vapor channel 12 which fluidly connects the vapor through hole 20 to the left side of the central section 4. The first set of through hole connecting channels further comprise a vapor connecting channel 13 which fluidly connects the vapor through hole 21 to the right side of the central section 4. The first set of through hole connecting channels further comprise distillate connecting channels 10, 11 which fluidly connect the distillate through holes 8, 9 to the central section 4. With arrows the flow of vapor 15 and distillate 16 is indicated.

[106] Fig. 6 illustrates a frame according to a third embodiment of the present disclosure in a simplified structure, a so called preheat frame 200. The embodiment of Fig. 6 corresponds to the embodiment of Fig. 2, but further comprises a second set of through hole connecting channels. The through hole connecting channels comprise a first feed connecting channel 27, which fluidly connects the first feed through hole 5 to the central section 4, and a second feed connecting channel 26, which fluidly connects the second feed through hole 6 to the central section 4. With arrows the flow of feed 28 is indicated.

[107] Fig. 7 illustrates a flash evaporation unit 50 of a membrane-less multi-stage flash evaporation and condensation system comprising a frame 100 according to Fig. 5 and a frame 200 according to Fig. 6.

[108] Further, the flash evaporation unit 50 comprises two cover plates 300, one at the beginning and one at the end of the stack of the two frames 100, 200. Between the frame 100 and the frame 200, a heat conductive and liquid impermeable film 17 is arranged. The heat conductive and liquid impermeable film 17 is attached to frame 200.

[109] The flash evaporation unit 50 comprises a droplet separator 42. The droplet extends over the entire length of the stack of frames 48 in stacking direction (i.e. from cover and configuration plate to cover and configuration plate) and is received by the droplet separator receiving section 43 of frame 100 and frame 200.

[110] The cover and configuration plate 300 comprises a brine passage 46 through which brine enters respectively leaves the flash evaporation unit 50. The cover and configuration plate 300 comprises a distillate passage 47 through which distillate enters respectively leaves the flash evaporation unit 50. One of the two cover plates has the distillate passage 47 on the right of the center. The other one of the two cover plates has the distillate passage 47 on the left of the center. The cover and configuration plate 300 comprises two feed passages 45 through which feed enters respectively leaves the flash evaporation unit 50. One of the two cover plates has the feed passages 45 below of the center. The other one of the two cover plates has the feed passages 45 above of the center. [111] Fig. 8 to Fig. 10 are described further below in the section “Industrial Applicability”.

[112] Fig. 11 illustrates an exemplary embodiment of the droplet separator receiving section according to the present disclosure. The droplet separator 42 comprises grooves. The grooves are complementary formed to protruding noses / tongues 44 which are integrally formed with the frame. The droplet separator 42 separates the brine flash through hole 7 from the vapor through hole 20.

[113] Fig. 12 illustrates the arrangement of frames 100 according to Fig. 4 and frames 200 according to Fig. 5 within two flash evaporation units 50 of a MSF evaporation and condensation system which are connected in series. The flash evaporation unit on the left hand side comprises a stack of sixteen frames and the flash evaporation unit on the right hand side comprises a stack of eight frames. At the beginning and end of each stack a cover and configuration plate 300 is arranged. In the stack of frames of the flash evaporation units, frames 100 according to Fig. 4 and frames 200 according to Fig. 5 are arranged alternately in stacking direction.

[114] Fig. 13 illustrates an evaporation-condensation frame 400 according to a further embodiment of the present disclosure. With arrows the flow of brine 22, vapor 15 and distillate 16 is indicated when the frame 400 is installed in an evaporation and condensation system which is in operation. The central section 4 holds a grid 14. The grid 14 is shown in a simplified manner as it is shown only for the bottom left portion of the central section 4. Actually, the grid 14 extends over / fills the whole central section 4. The grid 14 comprises multiple central section flow channels extending in parallel in up-down direction and multiple central section flow channels extending in parallel in left-right direction. The central section 4 is fluidly connected to the vapor through hole 20 by means of the vapor connecting channel 12 and is fluidly connected to the vapor through hole 21 by means of the vapor connecting channel 13. Further, the central section 4 is fluidly connected to the distillate through hole 8 by means of the distillate connecting channel 10 and is fluidly connected to the distillate through hole 9 by means of the distillate connecting channel 11. The central section 4 respectively the intermediate section 3 is fixed to the circumferential section 2 by means of fixation bars 180. The circumferential section 2 comprises a zic-zac structure. The brine flash through hole 7 and the vapor through holes

20, 21 comprise a reinforcement structure 53. The reinforcement structure comprises a zic-zac structure. The reinforcement structure 53 has a depth DI which is smaller than the frame depth D2 from the front side F to the back side B of the frame. Thus, the remaining part of the frame depth D2 is available as useable volume of the brine flash through hole 7 and the vapor through holes 20,

21. The circumferential section 2 is enclosed by a gasket 190. Also the multiple through holes of the intermediate section 2 and the central section 4 are enclosed by a gasket 19.

[115] A droplet separator 42 is arranged between the brine flash through hole 7 and the vapor through holes 20, 21. The embodiment of the droplet separator in Fig. 13 differs from the embodiment in Fig. 7-10 in that the droplet separator extends with the front side and the back side of the frame. The droplet separator receiving section is formed in a pocket shape. The droplet separator is inserted in that pocket. The pocket is an integrally formed part of the frame. The pocket has openings in up-down direction such that vapor can flow from the brine flash through hole into the vapor through hole by passing the droplet separator. The mesh made out of a polymer or metal filters / holds back the droplets such that vapor without droplets is provided in the vapor through hole.

[116] Fig. 14 illustrates a preheat frame 500 according to a further embodiment of the present disclosure. With arrows the flow of feed 28 is indicated when the frame 500 is installed in an evaporation and condensation system which is in operation. The basic structure of the embodiment of Fig. 14 corresponds to the basic structure of the embodiment of Fig. 13, but differs in the arrangement of through hole connecting channels. In Fig. 14 feed connecting channels 26, 27 fluidly connect the first feed through hole 5 and the second feed through hole 6 to the central section 4.

Industrial Applicability

[117] The present disclosure uses a polymer based basic frame design that can be modified to be an evaporation-condensation frame or a preheat frame. Multiple of such frames are stacked together to a stack of frames. Different stacks of frames then may be connected in series wherein the different stacks are separated by cover and configuration plates. The basic design of the frame comprises multiple through holes. In the stacked state, the multiple through holes form fluid channels in stacking direction. By means of the cover and configuration plates, fluid channels may be closed/blocked such that fluid may not exit or enter the closed fluid channel on the side on which the cover and configuration plate is arranged. Due to the arrangement of different frames and the arrangement and modification of the cover plates, the fluid flow within the stack of frames is configurable.

[118] The modification of the basic frame is performed by providing through hole connecting channels. Depending on the configuration, different through holes of the basic frame are connected to the central section of the frame.

[119] Due to the modular design of the frames, manufacturing steps for the evaporation-condensation frame and the preheat frame may be standardized. Thus, the manufacturing process may be simplified.

[120] With reference to Fig. 5-6 and Fig. 8-10, the use of the frame respectively the fluid flows within a stack of frames is explained.

[121] In the sense of this disclosure, feed is referred to as the fluid to be concentrated which flows through frames to be preheated and is not yet concentrated through evaporation. On the other hand, brine is referred to as the fluid which is already concentrated by means of evaporation of part of the fluid. [122] Fig. 5 illustrates an evaporation-condensation frame 100. With dotted arrows the flow of vapor 15 is indicated. With solid arrows the flow of distillate 16 is indicated. Such flows occur in the frame assuming that multiple frames are stacked together in a flash evaporation unit of a MSF evaporation and condensation system and such system is in operation.

[123] In the brine flash through hole, brine flashes and produces vapor 15. The vapor 15 flows to the droplet separators 42. The vapor 15 passes the droplet separators 42 and enters the vapor through holes 20 and 21. The droplet separator 42 hinders droplets from entering the vapor through holes 20, 21. From the vapor through holes 20 and 21, the vapor 15 enters the central section 4 by passing the vapor connecting channels 12 and 13. The vapor is distributed in the central section 4 and condenses on a film 17. The film 17 is not shown in Fig. 4, but covers the central section 4 on both sides. By condensing, the distillate 16 is produced. The distillate 16 flows down the film 17 and enters the distillate through holes 8 and 9 by passing the distillate connecting channels 10 and 11.

[124] Fig. 6 illustrates a preheat frame 200 and indicates with solid arrows the flow of feed 28 which flows in the preheat frame 200. The feed 28 flows from the top (first feed through hole 5) to the bottom (second feed through hole 6). Depending from the arrangement of evaporation-condensation frames 100 and preheat frames 200 within the stack of frames 1 forming the flash evaporation unit, the feed 28 may flow from the bottom (second feed through hole 6) to the top (first feed through hole 5) as well.

[125] Fig. 8 to Fig. 10 illustrate the flash evaporation unit of Fig. 7 and indicates with solid and/or dotted arrows the flow of feed 28 and brine 22 in Fig. 8, the flow of brine 22 and vapor 15 in Fig. 9 and the flow of distillate 16 in Fig. 10, when the flash evaporation unit is in operation.

[126] In Fig. 8, feed 28 enters the flash evaporation unit at feed passages 45 of the cover and configuration plate 300 on the left hand side of the stack. The feed 28 flows through the second feed through hole 6 of the evaporation- condensation frame 100 into the second feed through hole 6 of the preheat frame 200. The feed 28 then enters in the central section 4 of the preheat frame 200, passes the central section 4 and flows into the first feed through hole 5. The feed 28 then leaves the stack of frames at feed passage 45 of the cover and configuration plate 300 on the right hand side of the stack. While passing the flash evaporation unit, the feed 28 is preheated. Before the preheated feed 28 enters the stack again, the preheated feed 28 may be further preheated by flowing for example through further flash evaporation units 50 and/or may be further preheated by flowing through external heat exchangers (both not shown in Fig. 5). Then the further preheated feed 28, now referred to as brine 22, enters the stack of frames again. The brine 22 enters the stack of frames at brine passage 46 of the cover and configuration plate 300 on the right hand side of the stack. The brine 22 passes the brine flash through hole 7 of the preheat frame 200, then passes the brine flash through hole 7 of the evaporation-condensation frame 100 and then leaves the stack of frames at brine passage 46 of the cover and configuration plate 300 on the left hand side of the stack. As part of the brine 22 is flashed, the brine 22 is concentrated while passing the flash evaporation unit.

[127] Fig. 9 illustrates the flow of brine 22 and vapor 15. When the brine 22 enters the flash evaporation unit 50, it flashes to vapor 15 at a lower temperature and pressure according the thermodynamic conditions. The vapor 15 flows from the brine flash through hole 7 to the vapor through holes 20, 21 by passing the droplet separator 42. In the evaporation-condensation frame 100 the vapor through holes 20, 21 are fluidly connected to the central section 4. Thus, the vapor 15 flows from the vapor through holes 20, 21 into the central section 4 of the evaporation-condensation frame 100. The vapor 15 does not flow into the central section 4 of the preheat frame 200 as the central section 4 is fluidly not connected to the vapor through holes 20, 21.

[128] Fig. 10 illustrates the flow of the distillate 16. The vapor 15 flows into the central section 4 and condenses on the outer surface of the heat conductive and liquid impermeable film 17 which covers the central section 4 on both sides. Due to the heat of condensation, the feed 28 which flows on the other side of the heat conductive and liquid impermeable film 17 is heated up. The condensed vapor 15 forms the distillate 16. The distillate 16 flows down at the heat conductive and liquid impermeable film 17, is collected in the distillate through holes 8, 9 and leaves the flash evaporation unit at distillate passage 47 of the cover and configuration plate 300 on the right hand side of the stack.

Connection of frames within a stack

[129] Heat and mass transfer devices based on individual plastic frames, such as evaporators, condensers, mass and heat exchangers are well known. By joining the individual frames together, blocks are built up which can then in turn be joined together to form stages, modules and complete systems.

[130] Individual frames can be permanently j oined together by processes such as friction welding, hot plate welding, bonding and other processes.

[131] Alternatively, individual frames can also be assembled into blocks and joined together using a gasket connection. This is advantageous when industrial waste water or waste solutions are treated with the equipment. Industrial processes are constantly changing due to changing production conditions, environmental regulations and other influences. These changes in the process very often lead to a change in the composition of the liquid stream to be treated. If this flow is to be concentrated, the changed chemical composition, organic or inorganic, can spontaneously lead to fouling or scaling, usually in the form of coatings, in the system made up of frames.

[132] These fouling and/or scaling coatings are often difficult or impossible to remove with acids, alkalis or other chemicals. These coatings can also completely block the fluid channels and cause the process to be aborted. In the case of permanently connected frames, the only option is to replace individual or all blocks. It may be appropriate to replace individual blocks, for example, if fouling and scaling only occur locally in evaporation-condensation systems depending on the temperature and concentration of the liquid.

[133] Using a gasket connection, the frame may be further characterized by the following aspects.

[134] According to a first aspect, the frame further comprises a gasket surrounding at least one of the circumferential section, the intermediate section, the central section or one of the multiple through holes of the intermediate section.

[135] By means of the gasket, a detachably connection between the frames in a stack may be realized. The gasket is configured to fluid-tightly connect sections and/or through holes of two adjacent frames in a stacked state of multiple frames. The gasket can comprise multiple elements or can be formed out of one single gasket element. In an exemplary embodiment according to the present disclosure, the circumferential section is enclosed by a first gasket element and the multiple through holes of the intermediate section and the central section are enclosed by a second contiguous gasket element. Alternatively, the second contiguous gasket element can be formed of multiple, non-contiguous gasket elements, each enclosing one or more of the multiple through holes of the intermediate section and the central section.

[136] According to an exemplary embodiment, the gasket sealing the circumferential sections of adjacent frames has a width of 1 - 7 mm, preferably 2.5 - 5 mm and a height of 1 - 4 nun, preferably 2 - 3 mm, and the gasket sealing the multiple through holes and the central section of adjacent frames has a width of 1.5 - 4 mm, preferably 2 - 3 mm and a height of 1 - 3.5 mm, preferably 2 - 3 mm.

[137] According to a further aspect, the frame according to the above aspect further comprises a groove configured to receive the gasket.

[138] By means of the groove, the gasket may be fixed and held in position. [139] According to a further aspect, the frame according to the above aspects further comprises a protruding tongue, wherein the arrangement of the protruding tongue at least partly matches the arrangement of the gasket, when viewed in a front view, such that the protruding tongue at least partly pushes on the gasket of an adjacent frame in a stacked state of frames.

[140] By means of a tongue which pushes on the gasket of an adjacent frame, the fluid-tightly connection between sections and/or through holes of adjacent frames in a stacked state of multiple frames may be improved.

[141] According to a further aspect, the frame according to the above aspects further comprises a protruding distance bar, wherein the protruding distance bar is configured to provide a pre-defined gap between two adjacent frames in a stacked state.

[142] The protruding distance bar may protect the gaskets as they ensure that the gaskets are compressed only to a certain extent.

[143] The plastics frequently used for the frames include polyolefins, such as polyethylene PE and polypropylene PP. Frames made of PE and PP are easy to produce reliably in large quantities by injection moulding.

[144] The disadvantage for gasket-based systems made of frames is the anti-adhesive surface. This means that if a gasket made of e.g. silicone or polyurethane is applied to the frames, there is no or only very insufficient adhesion of the gasket material to the surface of the frame without pre-treatment of the frames.

[145] The adhesion of the gasket material to the surface of the frame can be improved by flame or plasma treatment to such an extent that the gasket, the gasket material can only be removed destructively. These subsequently applied gaskets are usually applied with multi-axis dosing systems. The manufacturing process of pre-treatment and dosing is very susceptible to failure and must be carefully monitored at all times. [146] To improve or overcome one or more aspects of known gasketbased systems for evaporation and condensation systems, a gasket made of a thermoplastic elastomer (TPE) may be applied. The TPE can also be applied to the e.g. PE- or PP-material of the frame by injection moulding. The physical characteristics of TPE is such that they adhere very well to PE and PP and can only be removed destructively.

[147] According to a first aspect, the TPE may be applied to the frames by using the process of core pull injection moulding. Such method comprises the step of providing a core pull injection mould. The core pull injection mould comprises a first cavity for the frame and can be modified by pulling a core such that a second cavity for the gasket is formed. The method further comprises the step of injecting the frame material into the first cavity wherein the core is not pulled yet. When the frame material has been injected, in a next step, the core is pulled such that the second cavity is formed within the core pull injection mould. In a further step, the TPE material is injected into the second cavity for the gasket.

[148] According to a further aspect, the TPE may be applied to the frames by using two injection moulds, the first one for the frame and the second one for the gasket. Such method comprises the step of providing a first injection mould and a second injection mould. The first injection mould comprises the cavity for the frame. The second injection mould comprises the cavity for the gasket. The method further comprises the step of injecting the frame material into the cavity of the first injection mould, the step of removing the frame out of the first injection mould, the step of inserting the frame into the second mould and injecting the TPE material into the cavity of the second mould.

[149] A difficulty when using this method is the shrinkage behaviour of the frame which is hot when it leaves the first injection mould. Thus, the fitting of the frame into the second mould may be problematic. [150] According to a further aspect, the TPE may be applied to the frames by using a method with a cube mould. In the cube mould, in a first step the frame material is injected into a cavity comprising a first cavity half and a second cavity half. After the injection of the frame material into the cavity, the cavity is opened such that the frame remains in the first cavity half wherein one side of the frame is exposed to the outside (as the second cavity half has been removed). The cube mould including the first cavity half rotates such that the first cavity half is moved. In a next step the first cavity half is closed with a third (counter) cavity half forming a new cavity for the TPE. The TPE is then injected into the new cavity forming the gasket.

[151] The connection between gasket and frame may be improved by providing grooves or holes in the gasket/frame such that a positive connection between the gasket and the frame may be realized.

[152] Terms such as “about“, “around“, “approximately⁴⁴, or “substantially” as used herein when referring to a measurable value such as a parameter, an amount, a temporal duration, and the like, is meant to encompass variations of ±10% or less, preferably ±5% or less, more preferably ±1% or less, and still more preferably ±0.1% or less of and from the specified value, insofar as such variations are appropriate to perform in the disclosed invention. It is to be understood that the value to which the modifier “about” refers is itself also specifically, and preferably, disclosed. The recitation of numerical ranges by endpoints includes all numbers and fractions subsumed within the respective ranges, as well as the recited endpoints.

[153] Although the preferred embodiments of this invention have been described herein, improvements and modifications may be incorporated without departing from the scope of the following claims.

Claims

-33- Claims

1. A frame (1) configured to be used in a flash evaporation unit (50) of a membrane-less multi-stage flash evaporation and condensation system, the frame (1) having a front side (F) and a back side (B) and comprising, viewed in a front view: a) a circumferential section (2) configured to provide mechanical stability to the frame (1), b) a central section (4) surrounded by the circumferential section (2), the central section (4) having an upper side, a lower side, a left side and a right side, and configured to allow

- flow of a feed (28) from the upper side to the lower side of the central section (4) and vice versa, and

- flow of a vapor (15) from the left side towards the right side and/or from the right side towards the left side of the central section (4), and c) an intermediate section (3) arranged between the circumferential section (2) and the central section (4), the intermediate section (3) comprising multiple through holes extending from the front side (F) to the back side (B) of the frame (1), the multiple through holes comprising:

- a first feed through hole (5), arranged above the central section (4),

- a second feed through hole (6) arranged below the central section (4),

- a vapor through hole (20, 21) arranged beside the central section (4),

- a brine flash through hole (7) arranged below the vapor through hole (20, 21), and -34-

- a distillate through hole (8, 9) arranged adjacent to the lower side of the central section (4), the intermediate section (3) further comprising a droplet separator receiving section (43), fluidly connecting the brine flash through hole (7) and the vapor through hole (20, 21) and being configured to receive a droplet separator (42), the droplet separator (42) being configured to prevent droplets from flowing from the brine flash through hole (7) to the vapor through hole (20, 21).

2. The frame (1) according to claim 1, comprising a first vapor through hole (20) arranged on the left side of the central section (4), and a second vapor through hole (21) arranged on the right side of the central section (4), wherein:

- each of the first vapor through hole (20) and the second vapor through hole (21) is fluidly connected to the brine flash through hole (7) by means of a first respectively second droplet separator receiving section (43), and

- the brine flash through hole (7) at least partly extends below the central section (4).

3. The frame (1) according to claim 1 or 2, wherein the brine flash through hole (7) at least partly extends below the second feed through hole (6).

4. The frame (1) according to any one of claims 1 to 3, wherein - the brine flash through hole (7) has a width (B7) extending in parallel to the direction from the left side of the central section (4) to the right side of the central section (4),

- the one or more vapor through holes (20, 21) each have a width (B20, B21) extending in parallel to the direction from the left side of the central section (4) to the right side of the central section (4), and

- the ratio of the width (B7) of the brine flash through hole (7) to the sum of the widths (B20, B21) of the one or more vapor through holes (20, 21) is in the range of 1.5 to 4, more preferably in the range of 2-3.2, viewed in a front view of the frame (1).

5. The frame (1) according to any one of claims 1 to 4 comprising a first distillate through hole (8) on the left side of the central section (4) and a second distillate through hole (9) on the right side of the central section (4).

6. The frame (1) according to any one of claims 1 to 5, wherein the central section (4) comprises a grid (14) with a plurality of central section flow channels configured to distribute water and vapor in the central section (4) of the frame (1).

7. The frame (1) according to any one of claims 1 to 6, wherein on the front side and/or back side of the frame (1) a heat conductive and liquid impermeable film (17) is attached such that it covers the central section (4).

8. The frame (1) according to claim 7, further comprising an internal frame (18) which surrounds the central section

(4) and separates the intermediate section (3) from the central section (4), wherein the heat conductive and liquid impermeable film (17) is attached to the internal frame (18).

9. The frame (1) according to claim 8, wherein the internal frame (18) is fixed to the circumferential section (2) of the frame (1) by means of fixation bars (180), the fixation bars (180) comprising a S-shape or a multi S- shape.

10. The frame (1) according to any one of claims 1 to 9, further comprising: a reinforcement structure (53) provided in a through hole of the multiple through holes, the reinforcement structure (53) having a depth (DI) which extends over 25% to 75%, preferably over 40% to 60% of the frame depth (D2) from the front side (F) to the back side (B) of the frame (1), such that the remaining part of the frame depth (D2) is available as useable volume of the through hole.

11. The frame (1) according to claim 10, wherein the reinforcement structure (51) is provided in the brine flash through hole (7) and/or in the vapor through hole (20, 21).

12. The frame (1) according to any one of. claims 1 to 1 1 , further comprising:

- a droplet separator (42) being received by the droplet separator receiving section (43).

13. The frame (1) according to claim 12, wherein the droplet separator (42) comprises a mesh made out of a polymer or metal, e.g. a mesh -37- made out of steel with a specific surface of 150 - 600 m²/m³ or a mesh made out of PE with a specific surface of 550 - 1100 m²/m³.

14. The frame (1) according to claim 12 or 13, wherein the droplet separator receiving section (43) is formed in a pocket shape in which the droplet separator (42) is insertable.

15. The frame (1) according to any one of claims 12 to 14, wherein the droplet separator (42) and the droplet separator receiving section (43) are configured such that in inserted state the connection between the droplet separator (42) and the droplet separator receiving section (43) is fluid tight.

16. The frame (1, 400) according to any one of claims 12 to 15, further comprising a first set of through hole connecting channels (10, 11, 12, 13) comprising at least one vapor connecting channel (12, 13) and at least one distillate connecting channel (10, 11), wherein the at least one vapor connecting channel (12, 13) fluidly connects the vapor through hole (20, 21) to the left side or right side of the central section (4) and the at least one distillate connecting channel (10, 11) fluidly connects the central section (4) to the distillate through hole (8, 9)

17. The frame (1 , 500) according to any one of claims 12 to

15, further comprising a second set of through hole connecting channels (26, 27) comprising at least a first feed connecting channel (27) and at least a second feed connecting channel (26), wherein the at least first feed connecting channel (27) fluidly connects the first feed through hole (5) to the upper side of the central section (4) and the at least second feed connecting channel (26) fluidly connects the second feed through hole (6) to the lower side of the central section (4). -38-

18. The frame (1 , 200) according to any one of claims 1 to 11 , wherein the droplet separator receiving section (43) comprises one or more guiding elements (44) such as for example a nose, protrusion or groove, configured to be connected to a complementary formed section of a droplet separator (42).

19. The frame (1, 100) according to claim 18, further comprising a first set of through hole connecting channels (10, 11, 12, 13) comprising at least one vapor connecting channel (12, 13) and at least one distillate connecting channel (10, 11), wherein the at least one vapor connecting channel (12, 13) fluidly connects the vapor through hole (20, 21) to the left side or right side of the central section (4) and the at least one distillate connecting channel (10, 11) fluidly connects the central section (4) to the distillate through hole (8, 9).

20. The frame (1, 200) according to claim 18, further comprising a second set of through hole connecting channels (26, 27) comprising at least a first feed connecting channel (27) and at least a second feed connecting channel (26), wherein the at least first feed connecting channel (27) fluidly connects the first feed through hole (5) to the upper side of the central section (4) and the at least second feed connecting channel (26) fluidly connects the second feed through hole (6) to the lower side of the central section (4).

21. A membrane-less multi-stage flash evaporation and condensation system comprising at least one flash evaporation unit (50) with a stack of frames (48), the stack of frames (48) including: one or more first frames (100) according to claim 19, and -39- one or more second frames (200) according to claim 20, wherein between a first frame and a second frame (100, 200) a heat conductive and liquid impermeable film (17) is arranged such that it separates the central section (4) from adjacent frames (100, 200), and a droplet separator (44) configured to be inserted into the droplet separator receiving sections (43) of the one or more first frames (100) and the one or more second frames (200).

22. The membrane-less multi-stage flash evaporation and condensation system according to claim 21 , wherein the droplet separator (42) extends over at least two adjacent frames (1), preferably over the entire length of the stack of frames (48) in stacking direction.

23. The membrane-less multi-stage flash evaporation and condensation system according to claims 21 or 22, wherein in the stack of frames (48), first frames (100) and second frames (200) are arranged alternately side by side in stacking direction such that the front side (F) of a first frame (100) faces the back side (B) of an adjacent second frame (200) and the back side (B) of a first frame (100) faces the front side (F) of an adjacent first frame (100).

24. The membrane-less multi-stage flash evaporation and condensation system according to any one of claims 21 to 23, further comprising: a cover and configuration plate (300) at the beginning and/or the end of the stack of frames (48), the cover and configuration plate (300) being configured to block the flow of fluid in and out of some fluid channels (49) wherein the fluid channels (49) are formed by the through holes of the frames (1).

25. The membrane-less multi-stage flash evaporation and condensation system according to claim 24, wherein the cover and configuration -40- plate (300) comprises an air shortcut opening configured to allow the flow of air in or out of the first feed channel of the stack of frames (48).

26. The membrane-less multi-stage flash evaporation and condensation system according to claim 25, wherein the air shortcut opening is a through bore with a diameter of 1-7 mm, preferably 2-5 mm.

27. The membrane-less multi-stage flash evaporation and condensation system according to any one of claims 21 to 26, wherein

- the stack of frames (48) comprises a first distillate channel formed by the multiple distillate through holes (8) on the left side of the central section (4) and a second distillate channel formed by the multiple distillate through holes (9) on the right side of the central section (4) and

- a first cover and configuration plate (300) at the beginning of the stack of frames (48) blocks the flow of distillate into or out of the first distillate channel and a second cover and configuration plate (300) at the end of the stack of frames (48) blocks the flow of distillate into or out of the second distillate channel.

28. A membrane-less multi-stage flash evaporation and condensation system comprising at least one flash evaporation unit (50) with a stack of frames (48), the stack of frames (48) including: one or more third frames (400) according to claim 16, and one or more fourth frames (500) according to claim 17, wherein between a third frame and a fourth frame (400, 500) a heat conductive and liquid impermeable film (17) is arranged such that it separates the central section (4) from adjacent frames (400, 500).