Salt-containing wastewater concentration device

Abstract

The salt-containing wastewater concentration device comprises a concentration tower, the concentration tower is divided into a heat exchange section and an evaporation section which are distributed up and down and do not communicate with each other, and the heat exchange section is located below the evaporation section; a wastewater pool, a first heat exchanger and a salt-containing wastewater distributor are sequentially arranged in the heat exchange section from bottom to top; a concentrated water tank, a second heat exchanger, a wastewater spraying layer, a liquid collecting layer and a condensation demisting layer are sequentially arranged in the evaporation section from bottom to top, an air inlet is formed in the tower wall of the evaporation section below the second heat exchanger, an exhaust port is formed in the top of the evaporation section, and a fan is arranged at the exhaust port; in the heat exchange section, waste steam of the power plant and salt-containing wastewater are subjected to heat exchange and temperature rise through the first heat exchanger, in the evaporation section, high-temperature salt-containing wastewater and ambient air are subjected to countercurrent flow heat exchange and evaporation to achieve wastewater concentration, the waste steam of the power plant is subjected to further heat exchange and temperature rise through the second heat exchanger, and the evaporation rate of the wastewater is increased. The concentration device integrates waste water heat exchange, waste water concentration and condensate water recovery.

Description

Technical Field

[0001] The utility model relates to the technical field of industrial wastewater treatment, and particularly relates to a device for concentrating saline wastewater. Background Art

[0002] In the industrial process, a large amount of saline wastewater is discharged. The discharge volume of saline wastewater is large and the treatment cost is high. One of the main measures is to reduce the volume of wastewater treatment by evaporating and concentrating the wastewater, thereby reducing the wastewater treatment cost. For example, the Chinese utility model patent document with the publication number 213643748U discloses a plate membrane device for wastewater concentration, separation and purification treatment, which includes a support frame; a diversion box is fixedly installed at the bottom of the support frame by welding, and a collection box is also fixedly installed at the bottom of the support frame; a bottom bearing frame is fixedly installed at the bottom of the support frame; six pressure reduction blocks are movably installed inside the support frame, and five pressing plates are movably installed inside the support frame; a front baffle is fixedly installed on the left side of the support frame; a rear baffle is movably installed on the right side inside the support frame.

[0003] In traditional methods, membrane concentration and multi-effect steam concentration are mainly used for wastewater concentration, and there are technical problems such as high system operation energy consumption, easy corrosion and blockage. Summary of the Utility Model

[0004] The present application provides a device for concentrating saline wastewater, which integrates wastewater heat exchange, wastewater concentration and condensate recovery, has no blockage or corrosion, does not require pretreatment of wastewater, and can stably concentrate wastewater from a salt content of 2%-3% to 15%-20%.

[0005] A device for concentrating saline wastewater includes a concentration tower, and the concentration tower is divided into a heat exchange section and an evaporation section which are distributed up and down and do not communicate with each other, and the heat exchange section is located below the evaporation section;

[0006] Inside the heat exchange section, from bottom to top, there are a wastewater pool, a first heat exchanger and a saline wastewater distributor in sequence;

[0007] Inside the evaporation section, from bottom to top, there are a concentrated water pool, a second heat exchanger, a wastewater spray layer, a liquid collection layer and a condensate demisting layer in sequence. An air inlet is opened on the tower wall of the evaporation section below the second heat exchanger, and an exhaust port is opened at the top of the evaporation section and a fan is arranged at the exhaust port;

[0008] The concentrated water pool in the evaporation section and the wastewater pool in the heat exchange section are respectively connected to the wastewater spray layer through water pumps;

[0009] The first heat exchanger includes at least one first heat exchange module, and the first heat exchange module includes two first water conduits, a plurality of first heat exchange plates, a plurality of first seals, and liquid guiding ribs; a first waste steam channel with a back-and-forth flow is formed inside the first heat exchange plates, and a water inlet hole and a water outlet hole that penetrate through the heat exchange plates and are communicated with the first waste steam channel are formed at one pair of diagonal corners of the heat exchange plates; the liquid guiding ribs are arranged between adjacent first heat exchange plates and are fastened and pressed by the first heat exchange plates to form a first waste water channel with a back-and-forth flow between every two adjacent first heat exchange plates, and the inlet of the first waste water channel is communicated with the space above the first heat exchanger and the outlet is communicated with the space below the first heat exchanger; the two first water conduits respectively penetrate through the water inlet holes and water outlet holes of a plurality of first heat exchange plates, and corresponding first seals are sleeved on the parts between adjacent first heat exchange plates, and after fastening, the first heat exchange module is formed; high-temperature waste steam flows in a back-and-forth and upward direction in the first waste steam channel; low-temperature saline wastewater flows in a back-and-forth and downward direction in the first waste water channel;

[0010] The second heat exchanger includes at least one second heat exchange module, and the second heat exchange module includes two second water conduits, a plurality of second heat exchange plates, and second seals; a second waste steam channel with a back-and-forth flow is formed inside the second heat exchange plates, and a water inlet hole and a water outlet hole that penetrate through the second heat exchange plates and are communicated with the second waste steam channel are formed at one pair of diagonal corners of the second heat exchange plates; the two second water conduits respectively penetrate through the water inlet holes and water outlet holes of a plurality of second heat exchange plates, and corresponding second seals are sleeved on the parts between adjacent second heat exchange plates, and after fastening, the second heat exchange module is formed, and the through gap between adjacent second heat exchange plates is the second waste water channel; high-temperature waste steam flows in a back-and-forth and upward direction in the second waste steam channel; in the second waste water channel, the concentrated wastewater contacts the air flowing from bottom to top in the concentration tower through the air inlet in a countercurrent manner from top to bottom.

[0011] The concentration device of the present application integrates wastewater heat exchange, wastewater concentration, and condensate recovery. The power plant waste steam enters the heat exchange section heat exchanger all the way to heat the saline wastewater to 45 - 65 °C; the other way enters the evaporation section heat exchanger to maintain the wastewater temperature in the evaporation heat exchange process at 50 - 60 °C and improve the wastewater evaporation rate. The heat exchanger in the heat exchange section preliminarily heats the saline water; the heat exchanger in the evaporation section maintains the temperature of the wastewater evaporation and concentration process on the one hand to ensure the wastewater evaporation rate, and on the other hand, distributes the sprayed wastewater to increase the gas-liquid contact area; the condensate demister is used for recycling the evaporated water vapor; the fan pushes the ambient air to enter the evaporation section to contact the wastewater in a countercurrent manner for evaporation.

[0012] The following also provides several optional ways, but they are not additional limitations to the above overall solution, but only further supplements or optimizations. On the premise of no technical or logical contradictions, each optional way can be combined with the above overall solution alone, or multiple optional ways can be combined with each other.

[0013] Optionally, the saline wastewater distributor includes a water distribution pipe network and nozzles evenly distributed on the water distribution pipe network.

[0014] Optionally, the wastewater spray layer includes a first spray layer and a second spray layer which are distributed in sequence from bottom to top. The wastewater pool in the evaporation section is connected to the first spray layer through a water pump, and the wastewater pool in the evaporation section is connected to the second spray layer through a water pump.

[0015] Optionally, the condensation and demisting layer includes a water inlet pipe, a water outlet pipe, and a plurality of demisting blades stacked in sequence. The demisting blades have a condensed water channel inside the blade and a water inlet hole and a water outlet hole respectively opened at the water inlet end and the water outlet end of the condensed water channel. The water inlet pipe sequentially passes through the water inlet holes of the demisting blades and is connected to the condensed water channel, and the water outlet pipe sequentially passes through the water outlet holes of the demisting blades and is connected to the condensed water channel. The gap between adjacent demisting blades is an air channel.

[0016] Optionally, the demisting blade is a corrugated plate, and the water inlet end of the condensed water channel is located at the top and the water outlet end is located at the bottom.

[0017] Optionally, the first heat exchange plate and the second heat exchange plate have the same structure, including:

[0018] A heat exchange membrane sheet, in which there are a plurality of through channels arranged in parallel. The water inlet hole and the water outlet hole corresponding to the heat exchange plate are respectively located at one pair of diagonals of the heat exchange membrane sheet. The through channels penetrate the heat exchange membrane sheet along the direction parallel to the heat exchange membrane sheet, and the water inlet hole and the water outlet hole penetrate the heat exchange membrane sheet along the direction perpendicular to the heat exchange membrane sheet;

[0019] Two guide water tanks are respectively located on both sides of the heat exchange membrane sheet in the vertical direction and are hermetically connected to the heat exchange membrane sheet as a whole. The guide water tanks are sequentially divided into a plurality of independent open slots along the vertical direction, and the open slots are correspondingly connected to the through channels in the heat exchange membrane sheet, so as to form corresponding waste steam channels in the heat exchange plate.

[0020] Optionally, each open slot corresponds to two adjacent through channels, and the open slots in the two guide water tanks are staggered in the height direction. The staggered part of the open slots on both sides shares a through channel, and adjacent two through channels are sequentially connected through the corresponding open slots.

[0021] Optionally, the extending direction of the liquid guiding rib is parallel to the extending direction of the first waste steam channel; the liquid guiding rib includes a transverse rib and a longitudinal rib. The longitudinal ribs are respectively close to the two guide water tanks of the first heat exchange plate and are consistent with the extending direction of the guide water tank. The transverse ribs extend horizontally and are distributed in a staggered manner up and down; one end of the transverse rib is spacedly abutted against the longitudinal rib on this side, and a water passing opening is reserved between the other end and the longitudinal rib on the opposite side.

[0022] After the adjacent heat exchange plates are butted and pressed, the longitudinal raised strips seal the vertical sides of the gaps between the heat exchange plates, and the transverse raised strips divide the space enclosed by the longitudinal raised strips into a second channel with a back-and-forth flow pattern.

[0023] Optionally, the heat exchange membrane is a plastic membrane; the thickness of the heat exchange membrane is 5-7 mm.

[0024] Optionally, the thickness of the liquid guiding rib is 3-6 mm.

[0025] As a preferred solution for the plastic membrane, the heat exchange membrane is formed by melting and extruding polyester plastic or polypropylene plastic with graphite, and the mass percentage content of graphite is 0.3%-5%. Adding graphite can increase the thermal conductivity of the membrane and improve the steam-water heat exchange efficiency.

[0026] Optionally, the first water conduit and the second water conduit have the same structure, both are metal hollow circular tubes with one end open and one end closed, and the water outlet holes are evenly distributed on the wall surface of the water conduit.

[0027] Optionally, the first sealing member and the second sealing member can adopt the same structure or different structures, for example, a conventional sealing gasket can be used.

[0028] Preferably, a sealing member with the following structure can also be used, including:

[0029] An annular sealing gasket is sleeved on the corresponding water conduit, and annular grooves are provided on both end faces of the sealing gasket along the axial direction;

[0030] Two sealing gaskets, made of soft annular polyester material, are respectively embedded in the corresponding grooves of the sealing gasket, and are used to seal the cross section of the heat exchange membrane and the sealing gasket during the fastening process of the heat exchange module.

[0031] The sealing gasket is used to seal the water flow channel and the wet flue gas / steam channel during the assembly and fastening process of the heat exchange module, and the gap between the heat exchange membranes in the heat exchange module is adjusted by changing the thickness of the sealing gasket. Optionally, the thickness of the sealing gasket is 8-20 mm.

[0032] The method for concentrating saline wastewater by using the saline wastewater concentration device includes:

[0033] The saline wastewater is fed into the heat exchange section and evenly distributed by the saline wastewater distributor. The saline wastewater flows in a zigzag pattern from top to bottom in the first wastewater channel of the first heat exchanger, while the power plant waste steam is fed into the first waste steam channel of the first heat exchanger and flows in a zigzag pattern from bottom to top. The saline wastewater and the power plant waste steam exchange heat in the first heat exchanger, the saline wastewater is heated to 45-65 °C and falls into the wastewater pool in the heat exchange section, and the condensate of the power plant waste steam after heat exchange in the first heat exchanger is discharged outside the concentration tower;

[0034] After the salt-containing wastewater is heated to 45-65℃, it is sent to the wastewater spray layer of the evaporation section through the preheating pump, and then enters the second heat exchanger after being sprayed and distributed by the wastewater spray layer, and falls along the surface of the heat exchange membrane of the second heat exchanger. At the same time, the ambient air flows upward through the gap between the heat exchange membrane of the second heat exchanger driven by the fan; the power plant exhaust steam is sent to the second exhaust steam channel of the second heat exchanger and flows from bottom to top; the power plant exhaust steam maintains the temperature in the second heat exchanger at 50-60℃, and the salt-containing wastewater exchanges heat with the ambient air on the surface of the heat exchange membrane of the second heat exchanger and evaporates;

[0035] The condensed water after the power plant exhaust steam completes heat exchange in the second heat exchanger is discharged to the outside of the concentration tower; the ambient air carrying water vapor flows upward, is condensed and demisted by the condensation demister, and then discharged from the exhaust port on the top of the tower.

[0036] Optionally, the flow rate of the ambient air in the second heat exchanger is 0.7-2.0 m / s.

[0037] Compared with the prior art, the present invention has at least one of the following beneficial effects:

[0038] (1) It integrates wastewater heat exchange, wastewater concentration, and condensate recovery. There is no clogging or corrosion, and wastewater does not require pretreatment.

[0039] (2) It can stably concentrate wastewater from 2%-3% salt content to 15%-20%;

[0040] (3) In the concentration process of the present application, the heat exchange medium forms a baffled flow state in the heat exchanger, which prolongs the heat exchange time, increases the heat exchange area, and improves the heat exchange efficiency;

[0041] (4) The heat exchanger has an exquisite structure design, which is easy to transport and assemble. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 This is a schematic diagram of the structure of the salt-containing wastewater concentration device of the present application;

[0043] Figure 2 A top view of a heat exchange module of the first heat exchanger (for the convenience of marking, the liquid-conducting ribs are only partially shown);

[0044] Figure 3 for Figure 2 A partial enlarged view of part A;

[0045] Figure 4 It is a schematic diagram of the heat exchange plate split of the first heat exchanger;

[0046] Figure 5 This is a schematic diagram of the exhaust steam channel inside the first heat exchange plate;

[0047] Figure 6 Schematic diagram of the cooperation between the first heat exchange plate and the liquid guiding rib in the first heat exchanger;

[0048] Figure 7 Schematic diagram of the structure of the liquid guiding rib in the first heat exchanger;

[0049] Figure 8 Top view structural diagram of a heat exchange module of the second heat exchanger;

[0050] Figure 9 Schematic diagram of the structure of the heat exchange plate of the second heat exchanger;

[0051] Figure 10 Schematic diagram of the assembled structure of the second heat exchanger;

[0052] Figure 11 Schematic diagram of the structure of the condensation and demisting layer.

[0053] The reference numerals shown in the figure are as follows:

[0054] 1. Heat exchange section; 2. First heat exchanger; 3. Salty wastewater distributor; 4. Evaporation section; 5. Air inlet; 6. Second heat exchanger; 7. First spray layer; 8. Second spray layer; 9. Liquid collection layer; 10. Condensation and demisting layer; 11. Exhaust port; 12. Fan; 13. First water pump; 14. Second water pump;

[0055] 21. First heat exchange plate, 22. First water conduit, 23. First seal, 24. Liquid guiding rib;

[0056] 211. Heat exchange membrane, 212. Water guiding tank, 213. First water inlet hole, 214. First water outlet hole, 215. Through channel, 216. Open slot;

[0057] 241. Transverse rib, 242. Longitudinal rib, 243. Water passing opening;

[0058] 61. Second heat exchange plate, 62. Second water conduit, 63. Second seal. Detailed implementation manners

[0059] Next, the technical solutions in the embodiments of the present application will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present application.

[0060] For a better description and illustration of the embodiments of the present application, one or more drawings may be referred to. However, the additional details or examples used to describe the drawings should not be considered as limiting the scope of any of the utility models, the currently described embodiments, or the preferred modes of the present application.

[0061] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which this application belongs. The terms used in the description of this application herein are only for the purpose of describing specific embodiments and are not intended to limit this application.

[0062] A salt-containing wastewater concentration device, as Figure 1 shown, includes a concentration tower. The concentration tower is divided into a heat exchange section 1 and an evaporation section 4 which are distributed vertically. The heat exchange section 1 is located below the evaporation section 4. The heat exchange section and the evaporation section are separated by a partition, and the upper and lower parts of the partition are not communicated with each other. In the heat exchange section 1, from bottom to top, there are a wastewater pool (located at the bottom of the heat exchange section, not marked in the figure), a first heat exchanger 2, and a salt-containing wastewater distributor 3 in sequence. In the evaporation section 4, from bottom to top, there are a concentrated water pool (located at the bottom of the evaporation section, not marked in the figure), a second heat exchanger 6, a wastewater spray layer (the first spray layer 7 and the second spray layer 8 in sequence), a liquid collection layer 9, and a condensation and demisting layer 10. An air inlet 5 is opened on the tower wall between the second heat exchanger and the concentrated water pool. An exhaust port 11 is opened at the top of the evaporation section, and a fan 12 is arranged at the exhaust port. The wastewater pool in the evaporation section 1 is connected to the second spray layer 8 through a first water pump 13, and the wastewater pool in the evaporation section 3 is connected to the first spray layer 7 through a second water pump 14.

[0063] The first heat exchanger 2 includes at least one first heat exchange module. The structure of the first heat exchange module is as Figure 2 and Figure 3 shown. The first heat exchange module includes several first heat exchange plates 21, two first water guide pipes 22, several first seals 23, and several liquid guide ribs 24. Water outlet holes are evenly opened on the two first water guide pipes.

[0064] The first heat exchange module is vertically installed in the heat exchange section with the first heat exchange plates 21. For the structure of a single first heat exchange plate, refer to Figures 4 to 7, the first heat exchange plate 21 includes a heat exchange membrane 211 and two water guide tanks 212. The heat exchange membrane 211 has a number of through channels 215 arranged in parallel. The first water inlet hole 213 and the first water outlet hole 214 are respectively located at a pair of corners of the heat exchange membrane. Among them, the first water inlet hole is located at the bottom end of the diagonal line, and the first water outlet hole is located at the top end of the diagonal line, with low inlet and high outlet. The through channels, the first water inlet hole and the first water outlet hole are all through holes of the membrane, and the through directions are perpendicular to each other. Specifically, the through channel 215 penetrates the heat exchange membrane along the direction parallel to the heat exchange membrane 211, and the first water inlet hole and the first water outlet hole penetrate the heat exchange membrane along the direction perpendicular to the heat exchange membrane. The axes of the water inlet and outlet holes are perpendicular to the axis of the through channel. The two water guide tanks 212 are respectively located on the vertical sides of the heat exchange membrane, and the two water guide tanks 212 are respectively sealed and connected to the two end ports of the through channel 215. For example, the water guide tank and the heat conduction membrane can be welded into a whole by welding. The inside of the water guide tank 212 is sequentially divided into a number of independent open slots 216 in the vertical direction. The open slots 216 are correspondingly communicated with the through channel 215, so as to form the first waste steam channel in the heat exchange plate 21 as described above.

[0065] As a corresponding communication method between the open slot 216 and the through channel 215, see Figure 5 , each open slot 216 corresponds to two adjacent through channels 215. The open slots in the two water guide tanks are staggered in the height direction, and the overlapping parts of the open slots on both sides share a through channel in the height. For example, taking Figure 5 the shown orientation as an example, from bottom to top, the first row of through channels and the second row of through channels are connected by a water guide groove on the right side, and the second row of through channels and the third row of through channels are connected by a water guide groove on the left side. The overlapping parts of the open slots on the left and right sides share the second row of through channels in the height direction, and so on. Two adjacent through channels are sequentially connected by the corresponding open slots to form the first waste steam channel in the heat exchange plate, so that the first waste steam channel forms a back-and-forth flow channel from bottom to top.

[0066] The liquid guide rib 24 is located in the gap between adjacent first heat exchange plates and is used to form a first waste water channel with back-and-forth flow in the gap between the first heat exchange plates. As a distribution method of the liquid guide rib 24, see Figure 6 and Figure 7 , including a horizontal rib 241 and a vertical rib 242. The vertical ribs are respectively arranged close to the two water guide tanks, and the trend of the vertical ribs is the same as that of the water guide tank. All the horizontal ribs extend horizontally and are staggered up and down; one end of the horizontal rib abuts against the vertical rib on this side at intervals, and a water passing opening 243 is reserved between the other end and the vertical rib on the opposite side at intervals. For example, taking Figure 6 and Figure 7For example, at the left ends of the horizontal ribs in all even rows from bottom to top, they abut against the left vertical rib, and there is a water passage opening reserved between the right ends and the right vertical rib. At the right ends of the horizontal ribs in all odd rows, they abut against the right vertical rib, and there is a water passage opening reserved between the left ends and the left vertical rib. The connection between the horizontal ribs and the vertical ribs is sealed. For example, the horizontal rib and the vertical rib it abuts against may be of an integrally formed structure. After adjacent heat exchange plates are butt-jointed and pressed tightly, the vertical ribs seal the vertical sides of the gap between the heat exchange plates, and the horizontal ribs divide the space enclosed by the vertical ribs into second water channels that flow back and forth from top to bottom. The second water channels each have a water inlet and a water outlet. The water inlet is located at the top of the diaphragm and communicates with the space above the first heat exchanger, and the water outlet is located at the bottom of the diaphragm and communicates with the space below the first heat exchanger. The saline wastewater forms a back-and-forth flow state from top to bottom in the first wastewater channel.

[0067] One assembly method of the first heat exchange module is to pass a first heat exchange plate through two first water guide pipes. One first water guide pipe passes through the water inlet hole 213 of the first heat exchange plate, and one first water guide pipe passes through the water outlet hole 214 of the first heat exchange plate. Then, a first seal 23 is sleeved on the first water guide pipe, and the liquid guiding rib 24 is closely attached to the heat exchange plate. Then, another first heat exchange plate is passed through the first water guide pipe, and they are stacked and installed in sequence. The first heat exchange plates are pressed tightly, and after fastening, the first heat exchange module is formed. As Figure 2 and Figure 3 shown in the assembly method, after the first heat exchange plates are pressed tightly, the water guide tanks of adjacent first heat exchange plates abut and connect, the first seal is just pressed tightly between adjacent heat exchange diaphragms, and the liquid guiding ribs are pressed tightly to form the first wastewater channel.

[0068] The heat exchange diaphragm can be a plastic diaphragm. As a preferred choice of the plastic diaphragm, it can be formed by melting and extruding polyester plastic and graphite, and through holes are formed inside the diaphragm. The added mass percentage of graphite is 0.3%-5%. The liquid guiding rib is made of rigid polyvinyl chloride. The water guide pipe 22 can be a metal hollow circular pipe with one end open and one end closed, and the through holes are evenly distributed on the wall of the water guide pipe. The seal 23 can be an annular sealing gasket.

[0069] In the first heat exchanger, the thickness of the heat exchange diaphragm is 5-7 mm; the thickness of the liquid guiding rib is 3-6 mm; the flow rate ratio of the first wastewater channel to the first exhaust steam channel is 0.7-1.1:1.

[0070] The saline wastewater distributor 3 is located above the first heat exchanger 2 and includes a water spray pipe and nozzles located on the water spray pipe, and is used to evenly distribute the saline wastewater so that the falling saline wastewater enters the first wastewater channel in the first heat exchanger more evenly.

[0071] The air inlet is arranged on the tower wall of the evaporation section 3 and can be circumferentially arranged on the tower wall in the form of louvers.

[0072] The main difference between the second heat exchanger and the first heat exchanger is that there are no liquid-conducting ribs between adjacent heat exchange plates of the second heat exchanger; in addition, there may be differences in the thickness selection of the heat exchange membrane and the water guide box.

[0073] The second heat exchanger includes at least one second heat exchange module, and the second heat exchange module includes two second water pipes 62, a plurality of second heat exchange plates 61 and a plurality of second sealing members 63, and its top view is as shown in FIG. Figure 8 .

[0074] The structure of a single second heat exchange plate is as follows Figure 9 As shown, its components and connection relationships are the same as those of the first heat exchange plate, and the same parts are not repeated. Between adjacent second heat exchange plates, low-temperature saline wastewater flows from top to bottom along the membrane surface, and ambient air enters the concentration tower from the air inlet and flows from bottom to top into the second heat exchanger. Low-temperature saline wastewater and air are in countercurrent contact on the membrane surface; high-temperature exhaust steam flows from bottom to top in the second exhaust steam channel, maintaining the wastewater temperature at 50-60°C during the evaporation heat exchange process, thereby increasing the wastewater evaporation rate.

[0075] For the assembly method of the second heat exchanger, refer to Figure 10 As shown, the difference from the first heat exchanger is that there is no need to install liquid guiding ribs.

[0076] In addition, the thickness of the water guide box of the second heat exchanger can be smaller than that of the first heat exchanger. The overall thickness of the heat exchange membrane in the second heat exchanger is 5 to 8 mm; the thickness of each water guide box is 8 to 12 mm, that is, the thickness of the water guide box is greater than the thickness of the heat exchange membrane. Figure 10 During assembly, the water guide boxes between adjacent heat exchange plates can be connected in abutment or spaced a certain distance apart.

[0077] The first spray layer 7 and the second spray layer 8 both adopt a spray mechanism commonly used in a spray tower.

[0078] The liquid collecting layer 9 is used to receive the condensed water from the condensation demister 10, and can adopt the liquid collecting mechanism commonly used in dehumidification towers.

[0079] The condensation demisting layer 10 is used to capture the evaporated water carried by the ambient air during the evaporation of the salt-containing wastewater. As an implementation method of the condensation demisting layer, see Figure 1 and Figure 11, the condensation and demisting layer includes a water inlet pipe, a water outlet pipe, and several demisting blades stacked in sequence. The demisting blades are of a hollow structure, with a condensed water channel inside the blades. The upper end (water inlet end) and the lower end (water outlet end) of the demisting blades are respectively provided with a water inlet hole and a water outlet hole. The condensed water channel extends along the streamline direction of the blade inside the blade, and both the water inlet hole and the water outlet hole penetrate through the blade. The water inlet pipe sequentially passes through the water inlet holes of the demisting blades, and the water outlet pipe sequentially passes through the water outlet holes of the demisting blades. Both the water inlet pipe and the water outlet pipe are connected to the condensed water channel inside the blade through the openings on their surfaces. The gap between adjacent demisting blades is an air channel.

[0080] The condensed water is fed into the blade from the lower end of the demister, flows through the inside of the blade from bottom to top and is discharged from the upper end. The ambient air carrying the evaporated water enters from the bottom of the demister and flows upward. The evaporated water in the ambient air is captured and condensed on the surface of the blade under the action of the condensed water in the blade, and then falls along the surface of the blade to the liquid collection layer. This demister has a self-cleaning function and there is no need to set up a demister flushing layer anymore.

[0081] As an implementation manner of the demisting blade, the demisting blade is a corrugated plate, and there is at least one corrugated structure on the corrugated plate, which is more conducive to the sliding of the condensed water and flushing the demisting blade during the sliding process.

[0082] A method for concentrating saline wastewater using the above device includes:

[0083] The saline wastewater is fed into the heat exchange section and evenly distributed by the saline wastewater distributor. The saline wastewater flows in a zigzag manner from top to bottom in the first wastewater channel of the first heat exchanger. At the same time, the power plant exhaust steam is fed into the first exhaust steam channel of the first heat exchanger and flows in a zigzag manner from bottom to top. The saline wastewater and the power plant exhaust steam exchange heat in the first heat exchanger, heating the saline wastewater to 45 - 65 °C and then dropping into the wastewater pool in the heat exchange section. The condensed water of the power plant exhaust steam after heat exchange in the first heat exchanger is discharged outside the concentration tower;

[0084] The saline wastewater heated to 45 - 65 °C is sent to the wastewater spraying layer in the evaporation section by the preheating pump, and after being sprayed and distributed by the wastewater spraying layer, it enters the second heat exchanger and drops along the surface of the heat exchange membrane of the second heat exchanger. At the same time, the ambient air flows upward through the gap between the heat exchange membranes of the second heat exchanger driven by the fan; the power plant exhaust steam is fed into the second exhaust steam channel of the second heat exchanger and flows in a zigzag manner from bottom to top; the power plant exhaust steam keeps the temperature in the second heat exchanger at 50 - 60 °C, and the saline wastewater exchanges heat and evaporates with the ambient air on the surface of the heat exchange membrane of the second heat exchanger;

[0085] The condensed water of the power plant exhaust steam after heat exchange in the second heat exchanger is discharged outside the concentration tower; the ambient air carrying water vapor flows upward, is condensed and demisted by the condensation and demister, and is discharged from the exhaust port at the top of the tower.

[0086] The technical features of the above-described embodiments can be combined arbitrarily. For the sake of brevity of description, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as the scope described in this specification.

[0087] The above-described embodiments only express several implementation manners of the present application, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the utility model patent. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present application, several modifications and improvements can still be made, and these all belong to the protection scope of the present application. Therefore, the protection scope of the patent of the present application shall be subject to the appended claims.

Claims

1. A salt-containing wastewater concentration device, characterized in that: The concentrating tower comprises a concentrating tower, wherein the concentrating tower is divided into a heat exchange section and an evaporating section which are distributed up and down and are not connected to each other, and the heat exchange section is located below the evaporating section; The heat exchange section includes a wastewater tank, a first heat exchanger and a saline wastewater distributor from bottom to top; The evaporation section includes a concentrated water pool, a second heat exchanger, a wastewater spray layer, a liquid collection layer and a condensation demisting layer from bottom to top. An air inlet is provided on the tower wall of the evaporation section below the second heat exchanger, an exhaust port is provided at the top of the evaporation section and a fan is provided at the exhaust port. The concentrated water pool in the evaporation section and the waste water pool in the heat exchange section are connected to the waste water spray layer through water pumps respectively; The first heat exchanger comprises at least one first heat exchange module, which comprises two first water pipes, a plurality of first heat exchange plates, a plurality of first seals and liquid guide ribs; the first heat exchange plate has a first exhaust steam channel for back and forth flow, and one of the two corners of the heat exchange plate has a water inlet and a water outlet that penetrate the heat exchange plate and communicate with the first exhaust steam channel; the liquid guide ribs are arranged between adjacent first heat exchange plates and are tightened by the first heat exchange plates to form a first waste water channel for back and forth flow between each two adjacent first heat exchange plates, the inlet of the first waste water channel is connected to the space above the first heat exchanger, and the outlet is connected to the space below the first heat exchanger; the two first water pipes respectively penetrate the water inlet and outlet holes of the plurality of first heat exchange plates, and the first seals are correspondingly put on the part between the adjacent first heat exchange plates, and the first heat exchange module is formed after tightening; The high-temperature exhaust steam flows in a baffled manner from bottom to top in the first exhaust steam channel; The low-temperature saline wastewater flows in a baffled manner from top to bottom in the first wastewater channel; The second heat exchanger includes at least one second heat exchange module, which includes two second water pipes, a plurality of second heat exchange plates and a second seal; the second heat exchange plate has a second exhaust steam channel that folds back and forth, and one of the two corners of the second heat exchange plate has a water inlet hole and a water outlet hole that penetrate the second heat exchange plate and connect to the second exhaust steam channel; the two second water pipes penetrate the water inlet holes and the water outlet holes of the plurality of second heat exchange plates respectively, and the second seals are correspondingly put on the parts between the adjacent second heat exchange plates, and the second heat exchange module is formed after being fastened, and the through gap between the adjacent second heat exchange plates is the second wastewater channel; The high-temperature exhaust steam flows in a baffled manner from bottom to top in the second exhaust steam channel; in the second wastewater channel, the concentrated wastewater contacts from top to bottom with the air that enters the concentration tower through the air inlet and flows from bottom to top in countercurrent.

2. The salt-containing wastewater concentration device according to claim 1, characterized in that: The wastewater spray layer includes a first spray layer and a second spray layer which are sequentially distributed from bottom to top. The wastewater pool in the heat exchange section is connected to the first spray layer through a water pump, and the concentrated water pool in the evaporation section is connected to the second spray layer through a water pump.

3. The salt-containing wastewater concentration device according to claim 1, characterized in that: The condensation demisting layer includes a water inlet pipe, a water outlet pipe and a plurality of demisting blades stacked in sequence, the demisting blades having a condensation water channel located inside the blades and a water inlet hole and a water outlet hole respectively opened at the water inlet end and the water outlet end of the condensation water channel, the water inlet pipe sequentially passes through the water inlet holes of the demisting blades and is connected to the condensation water channel, the water outlet pipe sequentially passes through the water outlet holes of the demisting blades and is connected to the condensation water channel, and the gap between adjacent demisting blades is an air channel.

4. The salt-containing wastewater concentration device according to claim 3, characterized in that: The demisting blade is a corrugated plate, the water inlet end of the condensed water channel is located at the top, and the water outlet end is located at the bottom.

5. The salt-containing wastewater concentration device according to claim 1, characterized in that: The first heat exchange plate and the second heat exchange plate have the same structure, including: A heat exchange membrane, wherein the heat exchange membrane has a plurality of through channels arranged in parallel, the water inlet holes and the water outlet holes corresponding to the heat exchange plates are respectively located at one of the corners of the heat exchange membrane, the through channels penetrate the heat exchange membrane in a direction parallel to the heat exchange membrane, and the water inlet holes and the water outlet holes penetrate the heat exchange membrane in a direction perpendicular to the heat exchange membrane; The two water guide boxes are respectively located on both sides of the heat exchange diaphragm in the vertical direction and are sealed and connected to the heat exchange diaphragm as a whole. The water guide boxes are vertically divided into a number of independent open grooves, and the open grooves are correspondingly connected to the through channels in the heat exchange diaphragm to form corresponding exhaust steam channels in the heat exchange plate.

6. The salt-containing wastewater concentration device according to claim 5, characterized in that: Each opening groove corresponds to two adjacent through channels and the opening grooves in the two water guide boxes are staggered in the height direction. The parts of the opening grooves on both sides that are staggered in height share a through channel, and the two adjacent through channels are connected in sequence through the corresponding opening grooves.

7. The salt-containing wastewater concentration device according to claim 5, characterized in that: The extension direction of the liquid-conducting ribs is parallel to the extension direction of the first exhaust steam channel; the liquid-conducting ribs include transverse ribs and longitudinal ribs, the longitudinal ribs are respectively close to the two water guide boxes of the first heat exchange plate and are consistent with the extension direction of the water guide boxes, and the transverse ribs extend horizontally and are staggered up and down; one end of the transverse rib is spaced apart from the longitudinal rib on this side, and the other end is spaced apart from the longitudinal rib on the opposite side to reserve a water opening.

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