MODULAR FLOW SYSTEM WITH ENHANCED VAPOR AND/OR LIQUID CHANNEL CONFIGURATION

Abstract

The invention relates to a modular flow system having a plurality of frame elements (101, 102) configured to be combined together to form a stack for forming a functional member. This functional member may be in particular a membrane distillation stage, a vapor generator, a condenser, a heat exchanger, a filter and/or a pervaporation stage. The frame elements (101, 102) each include: ⋅ an outer frame (39) and an inner frame (43), the inner frame (43) encasing a central inner region (40) and being surrounded by the outer frame (39), and ⋅ passage openings (13 to 16) and vapor and/or liquid channels (17, 18) arranged between the outer frame (39) and the inner frame (43). At least one of the two vapor and/or liquid channels (17, 18) is connected to the central inner region (40) by at least one vapor and/or liquid channel opening (22) constituting a through hole in the inner frame. In the frame elements (101, 102), when combined together to form the modular flow system, the vapor and/or liquid channels (17, 18) are arranged above the inner region (40).

Claims

1-22. (canceled)

23. A modular flow system having a plurality of frame elements configured to be combined together to form a stack for forming a functional member for at least one of a membrane distillation stage, a vapor generator, a condenser, a heat exchanger, a filter and a pervaporation stage, wherein the frame elements each include: an outer frame and an inner frame, the inner frame encasing a central inner region and being surrounded by the outer frame, passage openings and vapor channels and/or liquid channels arranged between the outer frame and the inner frame, wherein at least one of the two vapor channels and/or liquid channels is connected to the central inner region by at least one vapor channel and/or liquid channel opening constituting a through hole in the inner frame, and wherein in the frame elements, when combined together to form the modular flow system, the vapor channels and/or liquid channels are arranged above the inner region.

24. The modular flow system according to claim 23, wherein the central inner region is hollow or comprises a grid-like spacer.

25. The modular flow system according to claim 23, wherein the vapor channels and/or liquid channels are arranged next to each other and are bordered on one side by an outer side of the inner frame and on an opposing side by an inner side of the outer frame.

26. The modular flow system according to claim 23, wherein the cross-sectional area ratio of at least one of the vapor channels and/or liquid channels with regard to the central inner region is at least 13% and/or the cross-sectional area ratio of the entirety of vapor channels and/or liquid channels with regard to the central inner region is at least 26%.

27. The modular flow system according to claim 23, wherein the vapor channels and/or liquid channels are arranged on the same side of the central inner region and/or of the inner frame.

28. The modular flow system according to claim 23, further comprising: a condensate collection passage arranged below the inner region in the frame elements, when combined to form the modular flow system, and/or a condensate collection passage arranged on an opposite side of the central inner region and/or of the inner frame with regard to the vapor channels and/or liquid channels.

29. The modular flow system according to claim 23, wherein the complete cross-sectional area of the vapor channels and/or liquid channels is arranged on one side of the cross-sectional area of the central inner region and/or above the cross-sectional area of the central inner region.

30. The modular flow system according to claim 22, wherein the cross-sectional area of the vapor channels and/or liquid channels is separated from the cross-sectional area of the central inner region by the inner frame.

31. The modular flow system according to claim 23, wherein at least one passage opening is centrally arranged between the vapor channels and/or liquid channels.

32. The modular flow system according to claim 23, wherein at least one passage opening is provided on mutually opposite sides of each frame element, respectively.

33. The modular flow system according to claim 23, wherein the passage openings and the vapor and/or liquid channels are arranged on two opposing sides of the inner frame.

34. The modular flow system according to claim 23, wherein the inner frames comprise a rectangular form, and/or the outer frames and/or frame elements comprise a octagonal form.

35. The modular flow system according to claim 23, wherein the frame elements and/or their outer frames comprise at least one planar outer side.

36. The modular flow system according to claim 23, wherein the frame elements comprise two vapor channels and/or liquid channels, wherein only one of the two vapor channels and/or liquid channels is connected to the central inner region by a vapor channel opening and/or liquid channel opening.

37. The modular flow system according to claim 23, wherein the frame elements have a front side and a back side and are stacked in alternating orientation in the modular flow system, such that the front sides of adjacent frame elements face each other and the back sides of adjacent frame elements face each other.

38. The modular flow system according to claim 23, wherein the frame elements comprise: a first frame element comprising on both sides of the central inner region a film, and a second frame element comprising on both sides a water-tight, vapor-permeable membrane.

39. The modular flow system according to claim 37, wherein, when the first and second frame elements are stacked, in the first frame element only a first of the two vapor channels and/or liquid channels is connected to the central inner region by a vapor channel and/or liquid channel opening, and in the second frame element only the second of the two vapor channels and/or liquid channels is connected to the central inner region by a vapor channel and/or liquid channel opening.

40. The modular flow system according to claim 38, wherein in the first frame element the central inner region is further connected to at least one condensate collection passage by a condensate channel opening constituting a through hole in the inner frame, and in the second frame element the central inner region is further connected to at least one drain passage by a drain channel opening constituting a through hole in the inner frame.

41. The modular flow system according to claim 39, wherein the drain passage is separated in the frames from the condensate collection passage.

42. The modular flow system according to claim 23, wherein in the modular flow system frame elements with a film and frame elements with a water-tight, vapor-permeable membrane are stacked alternately.

43. The modular flow system according to claim 23, wherein each frame element is provided on at least one side with a respective welding web structure which, on the one hand, defines a region including the passage openings and the central inner region and defines at least two regions each including a vapor passage and/or liquid passage.

44. The modular flow system according to claim 23, wherein the vapor channels and/or liquid channels and/or the passage opening and/or the welding web structure of each of the stacked frame elements are aligned with one another, respectively.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0318] FIG. 1 shows a schematic representation of the principle design of the frame elements according to embodiments of the present disclosure;

[0319] FIG. 2 shows a schematic representation of a first frame element in particular with vapor and/or liquid channels according to embodiments of the present disclosure;

[0320] FIG. 3 shows a schematic representation of a second frame element in particular with vapor and/or liquid channels according to embodiments of the present disclosure;

[0321] FIG. 4A shows a schematic representation of the vapor and liquid flow in a first frame element according to embodiments of the present disclosure;

[0322] FIG. 4B shows a schematic representation of the feed flow in between a first and a second frame element according to embodiments of the present disclosure;

[0323] FIG. 4C shows a schematic representation of the vapor and liquid flow in a second frame element adjacent to the first frame element according to embodiments of the present disclosure;

[0324] FIG. 5A shows a schematic representation of a first frame element in particular with liquid passages according to embodiments of the present disclosure;

[0325] FIG. 5B shows a cross section of the first frame element of FIG. 5A along the line B-B;

[0326] FIG. 5C shows a cross section of the first frame element of FIG. 5A along the line C-C;

[0327] FIG. 6 shows a schematic representation of a second frame element in particular with liquid passages according to embodiments of the present disclosure;

[0328] FIG. 7 shows a schematic representation of a second frame element in particular with a welding web structure according to embodiments of the present disclosure;

[0329] FIG. 8 shows a schematic representation of a multistage membrane distillation apparatus, in particular comprising a modular flow system, according to embodiments of the present disclosure;

[0330] FIG. 9A shows a schematic representation of a centralized heating stage according to a first embodiment of the present disclosure;

[0331] FIG. 9B shows a schematic representation of a centralized heating stage according to a second embodiment of the present disclosure;

[0332] FIG. 9C shows a schematic representation of a centralized heating stage according to a third embodiment of the present disclosure;

[0333] FIG. 10 shows a schematic representation of a centralized condensation stage according to embodiments of the present disclosure;

[0334] FIG. 11 shows a schematic representation of a droplet elimination device according to a first embodiment of the present disclosure;

[0335] FIG. 12A shows a top view of a schematic representation of a droplet elimination device according to a second embodiment of the present disclosure;

[0336] FIG. 12B shows a side view of the droplet elimination device of FIG. 12A; and

[0337] FIG. 13 shows a side view of a schematic representation of a module comprising an integrated droplet elimination device according to embodiments of the present disclosure.

DESCRIPTION OF THE EMBODIMENTS

[0338] Reference will now be made in detail to exemplary embodiments of the disclosure, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like parts.

[0339] The present disclosure is shown in particular e.g. in FIGS. 11 to 13.

[0340] However, the features of the frame elements 101, 102 are described first which may form the membrane distillation apparatus.

[0341] FIG. 1 shows a schematic representation of the principle design of the frame elements according to embodiments of the present disclosure. The frame element is shown in a front view. The frame elements 101, 102 have an outer frame 39 and an inner frame 43.

[0342] Accordingly, the outer frame surrounds the inner frame. The inner frame encases (i.e. borders or defines in its inside) an inner region which desirably is used as an active area of the frame element (as described in more detail in other passages of the present disclosure).

[0343] Hence, there remains an available area between the outer frame and the inner frame. In this available area passage openings and vapor and/or liquid channels are arranged.

[0344] This configuration leads to a more efficient utilization of the total area inside the frame element, as the complete area between outer and inner frame may be utilized for passage openings and channels. For example, the vapor and/or liquid channels can have an increased size what leads to a higher possible output and efficiency of the modular flow system, as described in other passages of the present disclosure.

[0345] The inner frame 43 may comprise a rectangular form. The outer frame may comprise a octagonal form, more desirably an octagonal form. In other words, the frame element may have a octagonal shape. Accordingly, the form of the outer frame may approximate a circular form, when having a octagonal form. Therefore, the pressure inside the frame element can be balanced (equalized) what reduces the maximum pressure and hence allows thinner walls and increased openings, channels and inner region.

[0346] The frame elements 101, 102 may be made of a plastic, i.e. a synthetic material.

[0347] FIG. 2 shows a schematic representation of a first frame element 101 in particular with vapor and/or liquid channels according to embodiments of the present disclosure.

[0348] The frame element 101 is shown in a front view in the orientation it has when being stacked in a modular flow system. Accordingly, vapor and/or liquid channels 17, 18 are arranged above the inner region 40 in the modular flow system (i.e. desirably with regard to the gravitational direction pointing downwards).

[0349] Desirably the vapor and/or liquid channels have a trapezoidal form. In this case they can efficiently fill the area above the (desirably rectangular) inner region in a frame element having a octagonal form. Thus, the vapor and/or liquid channels can efficiently use the space in the frame element above the inner region 40. Consequently the frame element can have an outer shape which converges toward a circle form (e.g. by having the form of a octagon). In a circle form the pressure inside the frame element is ideally balanced. Therefore, the frame configuration of the present disclosure allows a reduced material use (i.e. thinner walls), as the maximum pressure in the frame element can be reduced compared to e.g. an elongated frame element form. As a further consequence, due to the material reduction the relative size of the inner region, the channels and passage opening can be increased, what ameliorates the efficiency of the modular flow system.

[0350] The cross-sectional area ratio of at least one of the vapor and/or liquid channels 17, 18 of a frame element 101, 102 with regard to the central inner region 40 may be at least 13%, more desirably 15%. In other words, the cross-sectional area ratio of the entirety of vapor and/or liquid channels 17, 18 with regard to the central inner region 40 may be at least 26%, more desirably 30%.

[0351] It is noted that the schematic figures do not necessarily represent these dimensions correctly.

[0352] Accordingly, the relative sizes of the vapor and/or liquid channels may be increased in comparison to the systems of the prior art. This is possible due to the new arrangement of the channels above the inner regions what allows a more balanced pressure inside the frame element and hence a decreased maximum pressure. In particular, the inventors have found that the defined relative sizes lead to an optimum efficiency of the complete modular flow system. Indeed, a relative increase of the sizes of the vapor and/or liquid channels 17, 18 also implies a reduction of the active area (40, 40′) of the membrane frame. However, due to the increased sizes of the vapor and/or liquid channels, more vapor can be transported to and from the active areas (i.e. the condensation/evaporation areas). Hence, the modular flow system may contain more frame elements in one stage and/or in one module (as described below in more detail) what increases the efficiency and the output of the flow system. The inventors have found that the described relative sizes lead to an optimum size balance leading to improved total efficiency of the modular flow system.

[0353] The inner region 40 is desirably bordered (i.e. covered) on its front and back side by a film, foil, or other heat transmitting but gas and liquid tight material. In particular, the central inner region 40 may be hollow or comprises a grid-like spacer. The film may be arranged, in particular welded, on the two sides of the spacer. The film may cover the total spacer but the passage openings and the channels may be kept free.

[0354] There is provided a vapor and/or liquid channel opening 22a between the vapor and/or liquid channel 17 and the inner region 40. Said vapor and/or liquid channel opening 22a may be e.g. a through hole inside an upper first frame wall of the inner frame 43. Said frame wall may hence separate the inner region 40 from the vapor and/or liquid channels 17, 18. Accordingly, vapor may be transported via a vapor and/or liquid channel 17 and the vapor and/or liquid channel opening 22a from or to the inner region 40.

[0355] Further, condensate collection passages 19a, 19b are arranged below the inner region 40. The central inner region may further be connected to at least one of the condensate collection passages by a condensate channel opening (or openings) 22b constituting a through hole in the inner frame. The condensed vapor generated inside said inner region when the vapor cools down may thus, run out through the condensation collection passage.

[0356] On the left and or right side of the inner region at least one passage opening 14, 15 may be provided for other functions of the modular flow system than a membrane distillation stage (as e.g. formed by the exemplary first and second frame elements shown in FIGS. 2 and 3).

[0357] Below the inner region 40 and between the condensate collection passages 19a, 19b there may be arranged first passage openings 16a, 16b which are described in more detail in context of FIG. 5A.

[0358] Further, below the inner region 40 and between the first passage openings 16a, 16b there may be arranged a central drain passage which is described in more detail in context of FIG. 4C.

[0359] FIG. 3 shows a schematic representation of a second frame element in particular with vapor and/or liquid channels according to embodiments of the present disclosure.

[0360] The frame element 102 is desirably again shown in a front view in the orientation it has in when being stacked in a modular flow system, i.e. in the same view as frame 101 of FIG. 2. The second frame element 102 may be to adjacent to the first frame element 101 in the modular flow system. Accordingly, the first and second frame element may be stacked. More desirably, a plurality of first frame elements 101 and a plurality of second frame elements 102 may be stacked alternately, as it is shown e.g. in FIG. 8.

[0361] The second frame element 102 principally corresponds to the first frame element 101. However, the inner region 40 of second frame element 102 is desirably bordered (i.e. covered) on its front and back side by a vapor-permeable (and liquid tight) membrane. Thus, the border may serve to transmit vapor and block liquid (i.e. the feed).

[0362] Beside this, it might be possible that the second frame element 102 corresponds to the first frame element and is merely turned in FIG. 3 around a vertical symmetry axis. However, it is desired that the first and second frame elements comprise further structural differences, at least regarding the configuration of the liquid passages 45, 46 (as shown in FIGS. 5 and 6).

[0363] As a further desired difference of the second frame element with regard to the first frame element, instead of the condensate channel openings 22b the frame element 102 comprises a drain channel opening (or openings) 22c constituting a through hole in the inner frame (i.e. a second frame wall below the inner region 40) connecting the central inner region 40 to the drain passage 20.

[0364] As further shown in FIGS. 2 and 3, at least one of the vapor and/or liquid channels 17, 18 comprises at least one internal strut member 48a, 48b extending between the inner frame 43 and the outer frame 39. Hence, the structure of the frame element 101 is reinforced by the at least one internal strut member. Hence, the size of the vapor and/or liquid channels may be increased without decreasing the steadiness (stability) of the frame element.

[0365] In particular, the strut members may be provided to connect the outer frame with the inner frame what leads to a higher stability. Accordingly, the frame walls may be made thinner.

[0366] The at least one strut member may comprise at least one connecting internal strut member 48a connecting the inner frame 43 with the outer frame 39, and/or

[0367] at least one non-connecting internal strut member 48b protruding from the inner frame 43 toward the outer frame 39 or from the outer frame 39 toward the inner frame 43 without connecting the inner frame 43 with the outer frame 39.

[0368] In the present example of e.g. FIG. 2 the channel 17 comprises two non-connecting internal strut members 48b and the channel 18 comprises two connecting internal strut members 48a. In the present example of e.g. FIG. 3 the channel 17 comprises two connecting internal strut member 48a and the channel 18 comprises two non-connecting internal strut members 48b.

[0369] When the frame elements 101, 102 are stacked alternately, the connecting and non-connecting internal strut members are desirably also stacked alternately.

[0370] Accordingly, due to a possible use of connecting internal strut members, the stability of the frame element can be effectively increased. Further, due to a possible use of non-connecting internal strut members, the liquid or vapor inside the channel can still pass from one side of the internal strut member to the other. Hence, pressure differences can be equalized (balanced). Thus, the channel may also be regarded as one functional channel in spite of the (connecting) internal strut member separating it in at least two sub channels (which may be arranged at adjacent frame elements in the stack).

[0371] Finally, since frame elements may be stacked such that connecting internal strut members and non-connecting internal strut members are arranged alternately in a vapor and/or liquid channel (17, 18), the overall stability of the modular flow system, provided by the structure forming said vapor and/or liquid channel (17, 18) can be increased.

[0372] Desirably the internal strut members 48 may be provided at least partially with the welding web structure 11 (cf. FIG. 7). The welding web structure is used to attach the frame elements to each other, in particular to close any channels, where necessary and to increase the all over stability of the modular flow system.

[0373] In particular, when the adjacent first and second frame elements 101, 102 are stacked, a welding web structure 11 of the connecting internal strut members 48a are aligned and match with the welding web structure of the non-connecting internal strut members 48b. For example, the welding web structure extends across the complete non-connecting internal strut members 48b and only on a matching section on the connecting internal strut members 48a (as shown e.g. in FIG. 7). Thus, a reliable connection across the complete stack of frame elements can be obtained in the area of the non-connecting internal strut members 48b, what provides an increased stiffness of the modular flow system. At the same time a vapor inside the channels 17, 18 can still be equalized within the channel due to the open sections in each second frame element.

[0374] Due to the connecting internal strut members 48a (e.g. in FIG. 2) the channel 18 may be regarded as comprising three adjacent sub-channels 18a, 18b, 18c which, when the frame elements are stacked together, traverse across the frame elements. These sub channels have openings between each other in some of the frame elements (e.g. in an adjacent frame element 102 as shown in FIG. 3). Accordingly, due to the openings between the sub channels, the liquid or vapor inside the channel can still pass from one side of the internal strut member to the other. Hence, pressure differences can be equalized (balanced). Thus, the channel may also be regarded as one functional channel in spite of the plurality of comprised sub channels.

[0375] Only some of the sub-channels (e.g. sub-channels 18a and 18c of the first frame element 101) may be connected to the central inner region (40) (e.g. via a vapor and/or liquid channel opening (22) of an adjacent second frame element of the stack). It is noted that this feature is not illustrated in the schematic FIGS. 2 and 3.

[0376] Furthermore, in order to further strengthen the stability of the frame element 101, 102, the outer frame 39 may include additional outer strut members 48c, 48d, 48e, 48f (48f is shown in FIG. 7).

[0377] Moreover, the inner frame 43 and the outer frame 39 may be connected by additional intermediate strut members (e.g. a strut member separating a vapor and/or liquid channels 17, 18 and the first passage opening 13.

[0378] In FIG. 4A to 4C the process of a membrane distillation using adjacent stacked frame elements 101 and 102 is shown. Generally, the inner region 40 (and desirably also the feeding area in front of the inner region in a front view of the frame element) may serve as the active area, in particular for membrane distillation. Said inner region and the feeding area may namely either be separated by a film, foil, or other heat transmitting and gas and liquid tight material, or by a vapor-permeable membrane. Hence, in case a film or there like is used, the border between inner region and feeding area may serve for heat transfer. In case a membrane is used, the border may serve to transmit vapor and block liquid (i.e. the feed).

[0379] FIG. 4A shows a schematic representation of the vapor and liquid flow in a first frame element 101 according to embodiments of the present disclosure. Vapor V1 is supplied by the first vapor and/or liquid channel and enters into the inner region 40 of the first frame element 101. Since this inner region 40 is bordered on its front and back side by a film, the vapor cannot pass the film (i.e. in a direction perpendicular to the frame element. Instead, the vapor condenses at the foil, such that a condensate (liquid) Cl runs out of the inner region into one or several condensate collection passages (19a and/or b). However, the heat of the vapor is transferred by the film to its opposite side, when the vapor condenses.

[0380] FIG. 4B shows a schematic representation of the feed flow F in between a first frame element 101 and a second frame element 102 according to embodiments of the present disclosure.

[0381] The frame elements 101, 102 are configured such (e.g. by the welding web structure(s) in between) that a gap remains between the frame elements when they are stacked in the modular flow system. This gap in particular forms a feeding area 40′ being aligned with the inner regions of the stacked frame elements and being in front of and outside of the inner regions 40 of the adjacent frame elements.

[0382] Since the inner region 40 of the second frame element 102 is bordered on its front and back side by a vapor-permeable membrane, the feeding area 40′ is bordered on a first side by a film (toward the first frame element 101) and on a second side by a vapor-permeable membrane (toward the second frame element 102).

[0383] A feed F is supplied via the first passage opening 13 to the feeding area 40′. Said feed may be a liquid, e.g. salt water or dirt water which is distilled and/or cleaned by the modular flow system. The feed may have a temperature slightly lower than the vapor V1, e.g. a difference of 4 to 6° C.

[0384] Due to the heat transferred from the condensing vapor V1, the feed F is heated and vaporizes. In this regard it is possible that the pressure within the feeding area or in parts of the modular flow system is reduced such that the feed boils when heated. The vapor passes the vapor-permeable membrane what leads to a membrane distillation MD.

[0385] FIG. 4C shows a schematic representation of the vapor and liquid flow in the second frame element 102 adjacent to the first frame element 101 according to embodiments of the present disclosure.

[0386] Due to the membrane distillation MD, vapor enters from the feeding area 40′ into the inner region 40 of the frame element 102. Said vapor may have a slightly lower temperature than the vapor V1, e.g. 2 to 3° C. and leaves the inner region 40 via the second vapor and/or liquid channel 18.

[0387] The arrangement shown in FIG. 4A to 4C shows a first stage of the modular flow system. Said vapor leaving the second frame element 102 may be transmitted to a second stage of the modular flow system where it may be used as (heating) vapor in a first frame element 101 again. Thus, the modular flow system may have several stages (e.g. 10 or more) wherein in each subsequent stage the temperatures of the supplied vapor and feed are slightly decreased with regard to the preceding stage.

[0388] As further shown in FIG. 4C, in case any feed undesirably passes the membrane (e.g. due to defects in the membrane) said feed (i.e. leakage) DR can leave the inner region 40 of the second frame element via the drain passage 20. Due to the arrangement of the vapor and/or liquid channel 18 above the inner region 40, the whole inner region 40 may serve as a barrier for leakage. In other words, the leakage would need to fill the complete inner region, in order to pass the barrier given by the configuration of the frame element, i.e. to flow into the vapor and/or liquid channel 18. Hence, any contamination of the final product (i.e. the distillate) can be effectively prevented.

[0389] FIG. 5A shows a schematic representation of a first frame element 101 in particular with liquid passages 45a, 46a according to embodiments of the present disclosure.

[0390] The liquid passages 45, 46 are desirably provided (e.g. as notches) on a first upper frame wall and a second lower frame wall of the inner frame 43. The first upper frame wall may separate the vapor and/or liquid channels 17, 18 and the first passage opening 13 from the inner region 40. The second lower frame wall may separate the passages 19, 20 and openings 16 from the inner region 40.

[0391] A first liquid passage 45 is provided by the first upper frame wall and is configured to distribute a feed from the first passage opening 13 to the feeding area 40′. The liquid passage 45 may extend asymmetrically by extending from a central section of the first frame side (below the first opening 13) into only one first direction along the first frame side (e.g. in FIG. 5A to the right) without extending into the opposite direction. The first liquid passage 45 may be connected to the first passage opening 13, in particular by connecting notches 47 provided on a front side of the first upper frame wall or a connecting channel provided inside said frame wall.

[0392] A second liquid passage 46 is provided by the second lower frame wall and is configured to collect a liquid from the feeding area 40′ to the first passage openings 16a, 16b. The second liquid passage 46 may extend discontinuously by extending only across the central region but not across the peripheral regions of the second lower frame wall. The second liquid passage 46 may be connected to the second passage openings 16a, 16b, in particular by a connecting notches 47 provided on a front side of the second lower frame wall or a connecting channel provided inside the second lower frame wall.

[0393] FIG. 5B shows a cross section of the first frame element of FIG. 5A along the line B-B. It is noted that FIG. 5B only shows the front side structure of the frame element 101 but does not consider its structure on the back side (as it is shown e.g. in FIG. 5C). Said back side structure may be symmetrical to the shown front side structure.

[0394] FIG. 5C shows a cross section of the first frame element of FIG. 5A along the line C-C. FIG. 5C schematically shows the structure of the frame element 101 on its front side and on its back side. As it can be seen, the front and back side of the frame elements can correspond to each other, desirable they are symmetric in a top view of the frame elements (which corresponds to the direction of view in FIG. 5B). In other words a frame element may be symmetric to a center plane of the frame element which is parallel to a plane defined by the front or back side of the frame element.

[0395] As it is shown in 5C, a feed supplied by the first opening 13 can enter the notch 45a via the connecting notch 47. Due to a barrier on the lower side of the notch (shown in FIG. 5C) which actually forms one side wall of the notch (or cavity) 45a, the feed is first fills the notch before it enters the (relatively thin) feeding area 40′ by passing the barrier.

[0396] FIG. 6 shows a schematic representation of a second frame element 102 in particular with liquid passages 45, 46 according to embodiments of the present disclosure;

[0397] As shown, the second frame elements desirably comprises complementary liquid passages 45, 46, such that the liquid passages of stacked first and adjacent second frame elements 101, 102 form together a liquid passage extending across (i.e. over the full length of) the complete first upper and second lower sides the feeding area 40′ (regarding peripheral liquid passages 46b, this is only schematically shown).

[0398] Accordingly, the liquid passage 45 of the second frame element 102 may extend asymmetrically by extending from a central section of the first frame side (below the first opening 13) into only a second direction along the first frame side (e.g. in FIG. 6 to the left) without extending into the opposite first direction.

[0399] A second liquid passage 46 of the second frame element 102 may extend discontinuously by extending only across the peripheral regions of the second lower frame wall but not across the central region.

[0400] As a consequence, it is possible to provide channel openings 22a, 22b, 22c constituting through holes in the inner frame in those areas where no liquid passage is provided. As a consequence, there is no interference of the liquid passage and the other function. Hence, the thickness of the frame wall (in particular in a front view of the frame member) may be reduced and hence, desirably of the complete frame element. As a consequence, more frame elements may be used in a modular flow system and the heat transfer may be increased due to the reduced thickness. This leads to a higher efficiency and an increased output of the flow system.

[0401] FIG. 7 shows a schematic representation of a second frame element in particular with a welding web structure 11 according to embodiments of the present disclosure. The first frame element 101 may have a corresponding welding web structure (with respective differences on e.g. the strut members 48a, 48b).

[0402] The welding web structure 11 is schematically shown by a solid line in FIG. 7. The other structural elements and features of the frame elements are indicated by dashed lines.

[0403] The welding web structure 11 defines regions including the passage openings 13 to 16 and the central inner region 40 and defines at least two regions each including a vapor and/or liquid passage 17, 18. As shown in FIG. 7, the region defining the central region 40 may also include the first passage opening 13 and the second passage openings 16a, 16b. In this way, a feed supplied by the first passage opening 13 can enter the feeding area 40′ between two adjacent frame elements and leave the feeding area via the second passage openings 16a, 16b.

[0404] The further passage openings 14, 15, channels 17, 18 and passages 20 are each desirably enclosed by a welding web structure 11 such that they are separated from each other in the area between two adjacent frame elements.

[0405] As further shown in FIG. 7, the welding web structure desirably extends across the complete non-connecting internal strut members 48b and only on a matching section on the connecting internal strut members 48a. Due to the different arrangement of the non-connecting internal strut members in the first frame element 101, the arrangement of the welding web structure desirably differs correspondingly.

[0406] As further shown in FIG. 7, in order to additionally strengthen the stability of the frame element 101, 102, the outer frame 39 may include additional outer strut members 48f. Such outer strut members may be provided with the welding web structure 11. Accordingly, outer strut members may be provided inside the outer frame, e.g. on an additional base element provided at the bottom of the frame element (shown in FIG. 7 but not in FIGS. 1 to 6).

[0407] Said welding web structure 11 is provided on only one side of a frame element (as schematically shown e.g. in FIG. 5C) but it may also be arranged (e.g. symmetrically) on both sides.

[0408] FIG. 8 shows a schematic representation of a multistage membrane distillation apparatus, in particular comprising a modular flow system, according to embodiments of the present disclosure.

[0409] The multistage membrane distillation apparatus 5000 comprises a plurality of multistage membrane distillation modules 500, 600. The modules are configured to be flowed through in parallel by a liquid (i.e. a feed, e.g. salt or dirt water) F to be concentrated. The modules are also supplied in parallel by a (heating) steam V1, as described below.

[0410] Each module comprises a plurality of serial condensation/evaporation stages 50, 60 etc. configured to be flowed through in series by the liquid to be concentrated. This is shown in FIG. 8 for module 500 only. Further stages may be subsequently connected in series to stage 60.

[0411] A steam (i.e. vapor) V2 generated in a first stage 50 may be supplied to a subsequent second stage 60 to heat said second stage. In this way the stages are also (at least functionally) connected (or coupled) in series with regard to the steam V1, V2. The steam supplied to the first stage (by the centralized heating stage 300) may have a temperature of 80-85° C. The temperature difference between an incoming and a generated outgoing steam in a stage (i.e. V1 and V2) may be 4-5° C. Accordingly, in case the steam supplied to the last stage has 40-45° C., it is possible that a module comprises 8 to 10 stages.

[0412] Each condensation/evaporation stage 50, 60 etc. comprises a plurality of parallel condensation/evaporation elements 101, 102 configured to be flowed through in parallel by the liquid to be concentrated. Desirably the condensation/evaporation elements 101, 102 are also configured to be flowed through in parallel by the steam. This is schematically shown in FIG. 8 for condensation/evaporation stage 50, 60.

[0413] Each condensation/evaporation element comprises at least one condensation unit 101 (e.g. a first frame element 101) and at least one evaporation unit 102 (e.g. a second frame element 102), as shown in stages 50 and 60. In the example of FIG. 8 two condensation/evaporation elements are shown which are formed each by an evaporation unit 102 sandwiched by two condensation units 101. Accordingly, the condensation/evaporation elements share a condensation unit 101 arranged between them.

[0414] It is noted that a stage may comprise one hundred parallel condensation/evaporation elements or more, e.g., more than one hundred condensation units 101 (e.g. first frame elements 101) and evaporation units 102 (e.g. second frame elements 102).

[0415] Accordingly, the apparatus may be or comprise at least one modular flow system according to the present disclosure. Also each module 500, 600 may be a modular flow system according to the present disclosure.

[0416] A stage 50, 60 may be terminated on its both ends by covers (i.e. closing frame members) 103, which close at least some of the openings, channels, passages, etc. in the outmost frame members 101, 102 (in FIG. 8 frame members 101).

[0417] The multistage membrane distillation apparatus 5000 has thus, a hierarchical organization with three levels. On the first (highest) level, the apparatus comprises a plurality of parallel multistage membrane distillation modules 500, 600. On the second (lower) level, the apparatus comprises a plurality of serial condensation/evaporation stage 50, 60. On the third (lowest) level, the apparatus comprises a plurality of parallel condensation/evaporation elements 101, 102. A condensation/evaporation element may comprise a first frame element 101 and a second frame element 102.

[0418] Due to this arrangement the apparatus may comprise up to several thousand condensation/evaporation elements, e.g. by simply combining several thousand first and second frame elements, respectively.

[0419] The apparatus 5000 may further comprise a centralized heating stage 300 configured to generate steam (i.e. a vapor) and to provide the steam to each of the modules in parallel, and/or a centralized condensation stage 400 configured to receive steam from each of the modules in parallel and to condense the steam.

[0420] Furthermore, by providing such an apparatus, it is possible that several modules commonly use a centralized (or single) heating stage and/or a centralized (or single) condensation stage. Therefore, the energy consumption of the centralized (or single) heating stage and/or a centralized (or single) condensation stage may be shared by a plurality of parallel modules, which can lead to an optimized energy efficiency of the apparatus and at the same time (due to the use of more than one module) to a higher total output of the apparatus.

[0421] The centralized heating stage 300 generates steam (i.e. a vapor) and provides the steam to each of the modules in parallel. Accordingly the modules are heated with the supplied steam. In comparison to heating with supplied (hot) liquid, this has the advantage that due to the thermodynamics steam will automatically be attracted most by the coldest surface in a steam space (in the present case the steam channel from the heating stage 300 to the condensation units 101 of each module's first stage). Hence, a module which is colder than the others will automatically be heated more. As a consequence, the temperature of the modules is automatically balanced.

[0422] In comparison, heating with (hot) liquid would require a very precise control implying high effort and reduced reliability.

[0423] The same applies to a centralized condensation stage 400. Due to thermodynamics the vapor (or steam) generated in the last stage of each module will automatically be attracted by the centralized condensation stage depending on the temperature of the vapor. Hence, a module which generates hotter vapor (or steam) in its last stage will automatically supply more steam to the centralized condensation stage and will therefore, be cooled more than the other (colder) modules. As a consequence, the temperature of the modules is automatically balanced. In other words, the set temperature of the modules can be automatically controlled.

[0424] The centralized heating stage 300 may be configured to provide the steam in each module to a first stage 50 of the serial condensation/evaporation stages. Accordingly, the first stage of each module may be heated by the centralized heating stage.

[0425] In particular; the steam is provided in each module to the condensation units 101 of the first stage in parallel. Said condensation units of the first stages are thus heated to a first predetermined temperature, e.g. in the range of 80-85° C.

[0426] Accordingly, the condensation units of a first stage 50 of each module may be heated by the generated steam. Condensation units of subsequent stages 60 may be heated with the steam (vapor) generated in preceding stages 50. The feed F may be heated to a second temperature which is slightly lower than the temperature of the generated steam, e.g. 4 to 6° C. lower. In this way the steam V1 can heat the feed F in the first stage such that the liquid vaporizes and passes the membrane walls of the evaporation units 102, thereby causing a membrane distillation.

[0427] The centralized condensation stage 400 may be configured to receive steam from a last stage of the serial condensation/evaporation stages 50, 60 of each module.

[0428] In particular, the centralized condensation stage 400 may be configured to receive steam from the evaporation units 102 (of each last stage) in parallel, in particular for cooling said evaporation units to a third predetermined temperature, e.g. in the range of 30 to 35° C., being lower than the first and the second predetermined temperatures. Accordingly, the evaporation units 102 of a last stage of each module may be cooled by the centralized condensation stage. Evaporation units 102 of preceding stages 50 may be cooled by subsequent stages 60 (i.e. the condensation units 101 of subsequent stages).

[0429] Each of the condensation units 101 may comprise a first steam space corresponding to the inner region 40 of the frame element 101 at least partly limited by a condensation wall, in particular a film. Accordingly, a condensation unit may be a first frame element 101, as described above.

[0430] Each of the respective evaporation units 102 may comprise a second steam space corresponding to the inner region 40 of the frame element 101 at least partly limited by a steam-permeable, liquid tight membrane wall. Accordingly, an evaporation unit may be a second frame element 102, as described above.

[0431] At least one flow channel (formed by a feeding area 40′ between adjacent frame elements 101, 102) for the liquid to be concentrated may be provided between a condensation unit 101 and an adjacent evaporation unit 102 such that the liquid inside the flow channel is heated via the condensation wall and the steam arising from the liquid to be concentrated moves through the membrane wall into the second steam space.

[0432] It is noted that for simplicity reasons the schematic illustration of FIG. 8 does not show any channels, in which the condensate C can flow out of the condensation units 101 (e.g. via condensate collection passages 19a, 19b). This condensate C may constitute, in particular together with the condensed vapor Vn in the centralized condensation stage 400, the final product of the apparatus (i.e. the distillate). Said final product may be collected in a container (not shown in FIG. 8). Furthermore, FIG. 8 does not show a drainage channel which may be configured to guide the drainage DR of the evaporation units 102 (e.g. via the drain passages 20) to a drainage container or to recirculate it to the feed supply channels which supply the feed F to the apparatus.

[0433] In the example of FIG. 8 in each condensation/evaporation stage 50, 60 the evaporation units 102 and condensation units 101 are stacked alternately. The evaporation units 102 have steam outlet passages in form of the vapor and/or liquid channels 18 connected with another, in particular facing one another and/or being aligned with each other. The condensation units 101 have steam inlet passages in the form of the vapor and/or liquid channels 17 connected with another, in particular facing one another.

[0434] The evaporation units 102 further comprise passage openings in the form of the vapor and/or liquid channels 17 facing the steam inlet passages 17 of the condensation units 101. The condensation units also comprise passage openings in the form of the vapor and/or liquid channels 18 facing steam outlet passages 18 of the evaporation units 102. Said passage openings are hence vapor and/or liquid channels 17, 18 which are not connected to the inner region by channel openings 22a. In other words, in an evaporation unit 102 the steam outlet passage 18 and the passage opening 17 are be symmetrical, and in a condensation unit 101 the steam inlet passage 17 and the passage opening 18 are symmetrical.

[0435] Since the vapor and/or liquid channels, and also the further openings and passages 13 to 16 and 19, 20 match each other in both frame elements 101, 102. Hence, each condensation/evaporation element comprises a single stack of frame elements providing the respective condensation units and evaporation units of the condensation/evaporation element. Furthermore, also each condensation/evaporation stage 50 is formed by a single stack of frame elements providing the parallel condensation/evaporation elements.

[0436] By this configuration a set of parallel connected evaporation and condensation units can be obtained in a stage.

[0437] Furthermore, as shown in the example of FIG. 8, the steam outlet passages 18 of the evaporation units 102 of a preceding stage 50 may be connected to the steam inlet passages 17 of the condensation units 101 of a successive stage 60 for forming a steam channel providing steam from the preceding stage to the successive stage. Hence, the subsequent stage 60 can be heated by the steam generated in the preceding stage 50. At the same time, said steam is the distillate (e.g. distilled and hence cleaned water).

[0438] Said units 101, 102 may be in particular arranged such that the respective steam outlet passages 18 of the preceding stage 50 and the respective steam inlet passages 17 of the successive stage face 60 one another. This is e.g. possible by turning the frame elements of a subsequent stage around their vertical symmetry axis. Therefore, each module can be formed by a single stack of frame elements.

[0439] Consequently, the heating steam V1 (e.g. generated by a centralized heating stage) can be easily supplied to each module 500, 600. The heating steam may namely be supplied only to the first frame element (forming a condensation unit 101) of a stacked module 500 (the outset closing frame members 103 may have a respective opening to allow the heating steam to enter the vapor and/or liquid channel 17 of the first frame member 101). In this way, the steam V1 is supplied to the parallel condensation units 101 of the first stage 50 of the module 500. The same applies to the steam generated in the last stage which may be supplied e.g. to a centralized condensation stage 400. The centralized condensation stage may be connected to the vapor and/or liquid channel 18 of the last frame element of the module stack. Said last frame element may e.g. form a condensation unit 101.

[0440] Therefore, the overall structure of the apparatus can be simplified and made more compact, which can enhance its efficiency, in particular with regard to the energy consumption.

[0441] FIG. 9A shows a schematic representation of a centralized heating stage 300 according to a first embodiment of the present disclosure. This centralized heating stage 300 may be used e.g. in the multistage membrane distillation apparatus 5000 of FIG. 8.

[0442] The centralized heating stage 300 may comprise a heating device 310 and an evaporation device 320, e.g. a flash tank. The heating device 310 may comprise a heating liquid space configured to heat a liquid and to supply it to the evaporation device 320. The evaporation device 320 may comprise a steam space 322 at least partly limited by a mesh tab and/or a steam-permeable, liquid-tight membrane wall 321 such that the steam V1 arising from the liquid moves through the mesh tab and/or the membrane wall into the plurality of multistage membrane distillation modules 500, 600 via a plurality of parallel steam passages.

[0443] It is desirable to use a liquid-tight membrane wall such 321. In this way it becomes possible to integrate a droplet elimination device (as described in more detail in context of FIGS. 11 to 13) into the heating stage.

[0444] In one exemplary embodiment, the evaporation device 320 may be fed by an unheated liquid (or feed) FO which is to be concentrated (i.e. to be distilled). In this way the liquid FO can be heated in the evaporation device, in order to generate the steam V1 and to supply the heated liquid F to the modules 500, 600. The liquid F may in particular be heated to a second predetermined temperature being lower than the first predetermined temperature of the steam V1. For this purpose the evaporation device 320 may be connected to the modules in parallel via a supply channel 331. Additionally the evaporation device 320 may be connected to the heating device 310 via a return channel 332. The supply channel 331 and the return channel 332 may comprise a common pump 330. The supply channel 331 may further comprise a valve 340 and any further means to adapt the pressure of the liquid F to a desired level.

[0445] The centralized heating stage may be configured as a vapor-liquid separator, in particular as a demister.

[0446] FIG. 9B shows a schematic representation of a centralized heating stage according to a second embodiment of the present disclosure. In this example, the centralized heating stage 300′ is configured as a kettle-type heating device and/or a submerged tube evaporator.

[0447] FIG. 9C shows a schematic representation of a centralized heating stage according to a third embodiment of the present disclosure. In this example, the centralized heating stage 300″ is configured as a thermosiphon heating device and/or as a natural circulation steam boiler.

[0448] The centralized heating stage may also have any other configuration for generating steam.

[0449] FIG. 10 shows a schematic representation of a centralized condensation stage 400 according to embodiments of the present disclosure. This centralized condensation stage 400 may be used e.g. in the multistage membrane distillation apparatus 5000 of FIG. 8. The centralized condensation stage 400 may comprise e.g. a mixing condenser or a plate-type condenser.

[0450] In one example, the centralized condensation stage 400 may comprise a cooling device 410 with a cooling liquid space 412 and a condensation device with a steam space 413. The cooling liquid space may be supplied with e.g. a cooled water supplied by a flow-through cooler (not shown). The spaces 412, 413 are separated by a liquid-tight, heat-conducting wall 411.

[0451] The steam space 413 may be connected to the last stage of each module 500, 600 in parallel via a plurality of respective steam passages. In this way the centralized condensation stage 400 can receive and condense a vapor Vn generated in the last stages. The condensate, i.e. the distillate leaves the steam space 413 via a distillate channel 414.

[0452] Furthermore, the steam space 413 may be connected via a vacuum channel 415 to a vacuum pump. In this way the pressure of the steam space 413 and also of the modules may be controlled. E.g. the modules may be applied with a predetermined negative pressure. Due to a pressure reduction the boiling temperature of the liquid is namely reduced, as well, which can enhance the membrane distillation process.

[0453] FIG. 11 shows a schematic representation of a droplet elimination device 320′ according to a first embodiment of the present disclosure. FIG. 11 may show a side view or a top view of the droplet elimination device. The droplet elimination device comprises a membrane 321′ configured to separate droplets from the steam generated by the heating stage. The membrane comprises in particular a steam-permeable, liquid-tight membrane wall.

[0454] The membrane is arranged in a steam chamber which is separated by the membrane into a steam incoming chamber 322′ and a steam outgoing chamber 324′.

[0455] In particular, the droplet elimination device comprises a steam incoming chamber 322′ which is supplied with steam VD (potentially comprising droplets) generated by the heating stage via a steam incoming channel 326. It further comprises a steam outgoing chamber 324′ on the other side of the membrane which provides the steam V.sub.ND separated from droplets to the condensation/evaporation stages via a steam outgoing channel 327. The steam V.sub.ND may be used e.g. as steam V1 in FIG. 8 which is provided to the first stage of each module.

[0456] The separated droplets DL can flow down on the membrane in the steam incoming chamber 322′ due to the gravitational force (in this case FIG. 11 shows a side view of the droplet elimination device).

[0457] The droplet elimination device may be used in a membrane distillation apparatus for producing water for injection. In particular, it may be used in the multi-stage membrane distillation apparatus, as described above, which may hence be used for producing water for injection purposes. For example, the droplet elimination device may be integrated into the heating stage 300 or a respective droplet elimination device may be integrated into each module 500, 600. Alternatively (or additionally), a droplet elimination device may be arranged in a steam channel between and externally to the heating stage and the modules, in particular before the steam channel is split to distribute the steam to each of the modules.

[0458] FIG. 12A shows a top view of a schematic representation of a droplet elimination device 320″ according to a second embodiment of the present disclosure.

[0459] As shown, the membrane has a folded form when seen from said top view. The folds extend hence in a vertical direction. It may however comprise (additional) folds extending in a horizontal direction. Accordingly, due to the increased surface a flow speed of the steam can be reduced, as the flow speed depends on the flow volume per surface size. Hence, since the pressure loss caused by the membrane correlates with the flow speed of the steam, a pressure loss can be reduced due to the decreased flow speed. Furthermore, due to the folded form, the droplet elimination device may anyway have a compact form. Droplets DL may be caught in the folds which extend into the direction of the steam outgoing channel 327 and may there flow down on the membrane.

[0460] FIG. 12B shows a side view of the droplet elimination device of FIG. 12A. As shown in this side view, the membrane comprises a steam-permeable, liquid-tight membrane wall section 321″ and arranged above a steam- and liquid-tight wall section 325. The membrane may have a folded form like that of FIG. 12A or a straight form like in FIG. 11 (for simplicity, the membrane is schematically illustrated as only one dotted line 321″ and not in a folded form)

[0461] Furthermore, the steam incoming channel 326 and the steam outgoing channel 327 are arranged above the membrane 321″. The spatial relationship “above” relates to the positioning in the droplet elimination device when the droplet elimination is installed in the membrane distillation apparatus.

[0462] Accordingly, a separation of any droplets can be achieved by using the gravitational force on the droplets. Since at least the steam outgoing channel is arranged above the membrane, the droplets cannot enter the outgoing channel, even if the membrane is damaged.

[0463] In particular, due to the steam- and liquid-tight wall section a droplet can be hindered from directly passing from the steam incoming channel to the steam outgoing channel. Furthermore, even if the membrane is damaged, any droplets passing the membrane (i.e. leakage) cannot enter the outgoing channel 326 due to its positioning above the membrane. Accordingly, the steam outgoing chamber 324″ forms a barrier for any leakage DR due to the raised position of the outgoing channel 327.

[0464] The steam outgoing chamber 324′ may comprise an additional outlet channel on its bottom for any potential leakage.

[0465] FIG. 13 shows a side view of a schematic representation of a module comprising an integrated droplet elimination device according to embodiments of the present disclosure.

[0466] The module may correspond to the module 500 described above and shown in FIG. 8, wherein it additionally comprises an integrated droplet elimination device. The module comprises a plurality of condensation/evaporation stage 50, 60, N, wherein for each stage for simplicity reasons of the schematic illustration only one condensation/evaporation element is shown in FIG. 13. For each condensation/evaporation element a condensation units 101 and an evaporation unit 102 is schematically shown.

[0467] From the condensation units 101 a condensate is extracted (e.g. via collection passages 19a, 19b) which constitutes (together with the condensed vapor Vn generated in the last stage N) the distillate, i.e. the water for injection.

[0468] From the evaporation units 102 a leakage may be extracted (e.g. via second passage openings 16a, 16b).

[0469] The module further comprises as a first unit (i.e. with regard to the steam flow coming from the heating stage) the droplet elimination device 320″. Said droplet elimination device may e.g. be provided by one or two frames added to the stack which forms the module shown in FIG. 8. The steam VD generated by the heating stage 300 passes the droplet elimination device, in particular its membranes 321″, whereby any potential droplets are separated from the steam. The purified steam V1 is then transmitted to the first stage 50, in order to heat the condensation units 101.

[0470] Accordingly, a compact arrangement of the droplet elimination device 320 can be provided, which has a simple structure due to the use of additional frame elements added to the module stack. Furthermore, since the droplet elimination device has a substantially equal steam pressure on both sides of the membrane 321″, there is a reduced risk of any membrane damage, any additional pressure adaptation in the droplet elimination device 320″ is unnecessary and the droplet elimination device 320″ does not substantially reduce the efficiency of the module. Finally, since the steam incoming channel and the steam outgoing channel are aligned with the steam inlet passages and the steam outlet passages and are arranged above the membrane 321″ and the feed areas 40′, standardized (frame) elements can be used and a safe leakage barrier is obtained.

[0471] Throughout the description, including the claims, the term “comprising a” should be understood as being synonymous with “comprising at least one” unless otherwise stated. In addition, any range set forth in the description, including the claims should be understood as including its end value(s) unless otherwise stated. Specific values for described elements should be understood to be within accepted manufacturing or industry tolerances known to one of skill in the art, and any use of the terms “substantially” and/or “approximately” and/or “generally” should be understood to mean falling within such accepted tolerances.

[0472] Although the present disclosure herein has been described with reference to particular embodiments, it is to be understood that these embodiments are merely illustrative of the principles and applications of the present disclosure.

[0473] It is intended that the specification and examples be considered as exemplary only, with a true scope of the disclosure being indicated by the following claims.