Steam-water heat exchanger

Abstract

The utility model discloses a steam-water heat exchanger which comprises at least one heat exchange module, and each heat exchange module comprises two water guide pipes, a plurality of heat exchange plates and sealing pieces. Each heat exchange plate comprises a heat exchange membrane and two water guide tanks, the heat exchange membranes and the water guide tanks are connected into a whole in a sealed mode and form baffling through liquid flow channels in the heat exchange plates, and a water inlet and a water outlet are formed in one pair of opposite angles of each heat exchange plate. The two water guide pipes penetrate through the water inlet and the water outlet of each heat exchange plate correspondingly, and a sealing piece penetrates through the position between every two adjacent heat exchange plates on the water guide pipes. A heat exchange water circulation channel is formed among the water guide pipe, the liquid channels in the heat exchange plates and the sealing piece, a wet flue gas / steam circulation channel is formed by a gap between every two adjacent heat exchange plates and the sealing piece, heat exchange water and high-temperature wet flue gas / steam conduct reverse flow / cross flow indirect heat exchange through the wall faces of the heat exchange plates, and heat of the wet flue gas / steam is recycled. And water vapor in the wet flue gas / steam is condensed into liquid water to be recycled.

Description

Technical Field

[0001] The utility model relates to a heat exchanger, in particular to a steam-water heat exchanger. Background Art

[0002] A steam-water heat exchanger is a device that exchanges heat from high-temperature steam into low-temperature water to raise the water's temperature. Steam-water heat exchangers typically include tubular and plate types. A tubular heat exchanger uses the walls of the tube bundle enclosed in the shell as a heat transfer surface. When used for steam-water heat exchange, the low-temperature liquid flows through the tubes, while the high-temperature steam or high-humidity gas flows through the gaps between the tube bundles. The two heat exchange media exchange heat indirectly using the walls as the heat transfer surface. Common plate heat exchangers are composed of a series of stacked metal sheets with a certain corrugated shape. Thin rectangular channels are formed between the plates. Adjacent thin rectangular channels carry the low-temperature liquid medium and the high-temperature steam / high-humidity flue gas medium, respectively, and heat exchange occurs through the plates.

[0003] Existing steam-water heat exchangers are primarily used for recovering waste heat from high-temperature, high-pressure steam. These heat exchangers are primarily made of metal, requiring a large temperature difference between the hot and cold fluids during the heat exchange process. Furthermore, the operating pressure of the heat medium within the heat exchanger is high. This creates a mismatch between the amount of heat recovered and the investment and operating costs for recovering waste heat from lower-temperature steam. Currently, there is a lack of adaptable, efficient heat exchange equipment and methods for recovering waste heat from low-temperature steam, below 70°C. Utility Model Content

[0004] The present application provides a steam-water heat exchanger, which is mainly used for recovering waste heat from high-humidity flue gas / steam with a temperature less than 70°C. It has high heat exchange efficiency and is easy to produce, transport and assemble.

[0005] A steam-water heat exchanger comprises at least one heat exchange module, wherein the heat exchange module comprises two water pipes, a plurality of heat exchange plates and a sealing member;

[0006] A single heat exchange plate includes:

[0007] A heat exchange diaphragm having a plurality of parallel first flow channels therein, a water inlet and a water outlet respectively provided at a pair of corners of the heat exchange diaphragm, the first flow channels penetrating the heat exchange diaphragm in a direction parallel to the heat exchange diaphragm, and the water inlet and the water outlet penetrating the heat exchange diaphragm in a direction perpendicular to the heat exchange diaphragm;

[0008] Two water guide boxes are located on opposite sides of the heat exchange diaphragm and are sealed and connected to the heat exchange diaphragm as a whole. The water guide boxes are divided into a number of independent second flow channels by water barriers. The second flow channels are connected to the first flow channels and form a baffled liquid flow channel in the heat exchange plate. The inlet of the liquid flow channel is connected to the water inlet of the heat exchange diaphragm, and the outlet of the liquid flow channel is connected to the water outlet of the heat exchange diaphragm.

[0009] The two water pipes include a first water pipe and a second water pipe. The first water pipe and the second water pipe are both hollow cylindrical structures with one end open and the other end sealed. A plurality of water guide holes are evenly opened on the wall of each water pipe. The first water pipe passes through the water inlet of each heat exchange plate, and the second water pipe passes through the water outlet of each heat exchange plate. The first water pipe and the second water pipe are both connected to the liquid flow channel through their water guide holes. A seal is inserted between every two adjacent heat exchange plates on the water pipe.

[0010] The thickness of each heat exchange membrane is 5~8mm; the thickness of each water guide box is 8~12mm.

[0011] Several heat exchange plates and seals are stacked alternately in sequence, and the water inlet and outlet are respectively provided on the first water pipe and the second water pipe, and are fastened to form a heat exchange module. The water pipe, the liquid flow channel inside the heat exchange plate and the seal constitute a hot water flow channel, i.e., a liquid flow channel. The gap formed by the seal between two adjacent heat exchange plates constitutes a wet flue gas / steam flow channel. The heat exchanger and the high-temperature wet flue gas / steam are indirectly exchanged with each other through countercurrent and cross-flow through the wall of the heat exchange plate.

[0012] In the heat exchange module of the present application, each heat exchange diaphragm is sealed and fixed to two water guide boxes to form an independent single heat exchange plate. Several independent heat exchange plates are installed on two water guide pipes. Seals are installed on the water guide pipes and between the heat exchange plates. The seals, on the one hand, separate adjacent heat exchange plates to form a continuous steam flow channel, and on the other hand, completely seal and block the steam flow channel from the liquid flow channel. The heat exchange plate has a through-flow liquid flow channel. The low-temperature liquid flows in through the water inlet and out through the water outlet, presenting a top-down back-and-forth flow pattern within the heat exchange plate. The high-temperature wet flue gas or steam circulates from the bottom to the top within the heat exchange module, realizing steam-water countercurrent and cross-current flow, thereby improving heat exchange efficiency. Individual heat exchange plates can be independently produced and transported, and assembly on the construction site is convenient and quick.

[0013] Several optional methods are also provided below, but they are not intended to be additional limitations on the above-mentioned overall solution. They are merely further supplements or optimizations. Under the premise that there are no technical or logical contradictions, each optional method can be combined separately for the above-mentioned overall solution, or multiple optional methods can be combined.

[0014] Optionally, each second flow channel corresponds to two adjacent first flow channels and the second flow channels in the two water guide boxes are staggered, the parts of the second flow channels in the two water guide boxes that overlap in height share one first flow channel, and the two adjacent first flow channels are connected in sequence through the corresponding second flow channels.

[0015] Optionally, the heat exchange diaphragm is a plastic diaphragm.

[0016] Optionally, the thickness of each heat exchange membrane is 5~8mm; the thickness of each water guide box is 8~12mm.

[0017] Optionally, the heat exchange membrane is a membrane formed by melt-extrusion of polyester plastic or polypropylene plastic and graphite, and the mass percentage of graphite in the heat exchange membrane is 0.3%-5%.

[0018] The present application distributes the flow channels of the heat exchange diaphragm and the water guide box to achieve back-and-forth flow of hot water from bottom to top in each heat exchange plate, achieving countercurrent and cross-current flow with the upward wet flue gas / steam, and improving the steam-water heat exchange efficiency by controlling the flow rate of hot water and the gap between the diaphragms. On this basis, the present application also makes optimal settings for the material and thickness of the heat exchange diaphragm. The diaphragm adopts a plastic diaphragm, for example, a plastic diaphragm formed by melt-extrusion of polyester plastic or polypropylene plastic and graphite. The addition of graphite can further improve the thermal conductivity of the diaphragm and improve the steam-water heat exchange efficiency. The thickness of the diaphragm is only 5~8mm, the overall thickness of the diaphragm is small, the thickness of the heat exchange wall is even smaller, and the heat exchange efficiency is further improved. It is suitable for low-grade heat recovery scenarios with steam / flue gas temperature less than 70℃.

[0019] Optionally, the sealing member includes:

[0020] An annular sealing gasket is sleeved on the water pipe, and both end surfaces of the sealing gasket along the axial direction are provided with annular grooves;

[0021] The two sealing gaskets are made of soft annular polyester material and are respectively embedded in the corresponding grooves of the sealing gasket. They are used to seal the heat exchange diaphragm and the sealing gasket section during the fastening process of the heat exchange module.

[0022] The sealing gasket is used to seal the water flow channel and the wet flue gas / steam flow channel during the assembly and tightening process of the heat exchange module. The gap between the heat exchange diaphragms in the heat exchange module can be adjusted by changing the thickness of the sealing gasket. Optionally, the thickness of the sealing gasket is 8-20mm.

[0023] The method for performing steam-water heat exchange using the steam-water heat exchanger includes:

[0024] The low-temperature hot water is fed into the liquid flow channels in each heat exchange plate in parallel from the top of the steam-water heat exchanger by the first water conduit, flows through the liquid flow channels from top to bottom in sequence, and then is collected in the second water conduit from the bottom of the steam-water heat exchanger and flows out from the second water conduit; at the same time, the high-temperature wet flue gas or steam is fed into the bottom of the steam-water heat exchanger and flows through the steam flow channels between adjacent heat exchange plates from bottom to top, forming a countercurrent and crosscurrent flow with the low-temperature hot water body in the heat exchange plate, and is discharged from the top of the heat exchanger; the low-temperature hot water and the high-temperature wet flue gas or steam undergo indirect countercurrent / crosscurrent heat exchange through the wall of the heat exchange plate, recovering the heat of the wet flue gas or steam, and condensing the water vapor in the wet flue gas or steam into liquid water for recovery.

[0025] Optionally, the steam-water heat exchanger is suitable for wet flue gas / steam temperature <70°C; the temperature difference between the inlet temperature of the low-temperature hot water and the inlet temperature of the high-temperature wet flue gas / steam is >10°C.

[0026] Optionally, the flow rate of the high-temperature wet flue gas / steam in the gas flow channel is 3.5-6.0 m / s; the water flow rate of the low-temperature hot water in each heat exchange plate is 50-200 L / h.

[0027] Optionally, the operating pressure of the low-temperature hot water in each heat exchange plate is 0.02-0.07 MPa.

[0028] This heat exchanger is suitable for steam-water heat exchange scenarios with steam / flue gas temperature less than 70°C. The sealing gasket thickness is 8-20mm; the steam / wet flue gas flow rate in the diaphragm gap is 3.5-6.0m / s, the hot water flow rate in each diaphragm is 50-300L / h, and the temperature difference between the hot water inlet temperature and the steam inlet temperature of the diaphragm is greater than 10°C.

[0029] Compared with the prior art, this application has at least one of the following beneficial effects:

[0030] (1) The utility model provides a low-cost steam-water heat exchanger that can be quickly assembled: a first water conduit is passed through the water inlet of each heat exchange plate, a second water conduit is passed through the water outlet of each tube heat exchange plate, and a seal is passed through between every two adjacent heat exchange plates. By fastening the heat exchange plates and the seal, the steam-water flow path is separated. Each component of the heat exchange module can be independently produced and transported, and the assembly at the construction site is convenient and fast.

[0031] (2) The utility model provides an efficient steam-water heat exchange method: by distributing the flow channels of the heat exchange membrane and the water guide box, the heat exchange water can flow back and forth from bottom to top in each heat exchange plate, and realize countercurrent + crosscurrent flow with the upward wet flue gas / steam. By controlling the heat exchange water flow rate and the membrane gap, the steam-water heat exchange efficiency is further improved;

[0032] (3) The utility model provides a highly efficient steam-water heat exchange material: a multi-channel heat exchange membrane formed by melt extrusion of polyester plastic / polypropylene plastic and graphite is used as a heat conduction medium. By controlling the porous pore size, membrane thickness and graphite addition amount, the steam-water heat conduction efficiency is improved, and the heat transfer performance of the steam-water heat exchanger is further improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 and Figure 2 Schematic diagram of the top view of the heat exchange module from different angles;

[0034] Figure 3 Schematic diagram of the assembled structure of a single heat exchange plate;

[0035] Figure 4 Schematic diagram of the split of a single heat exchange plate;

[0036] Figure 5 Schematic diagram of the liquid flow path inside a single heat exchange plate;

[0037] Figure 6 It is a partial enlarged view of the assembly method of adjacent heat exchange plates;

[0038] Figure 7 Schematic diagram of the structure of the seal;

[0039] Figure 8 Schematic diagram of the structure of the water pipe.

[0040] The reference numerals shown in the figures are as follows:

[0041] 1. Heat exchange plate, 11. Heat exchange diaphragm, 12. Water guide box, 13. Water inlet, 14. Water outlet, 15. First flow channel, 16. Second flow channel, 17. Water barrier;

[0042] 2. aqueduct, 21. water guide hole;

[0043] 3. seal, 31. sealing gasket, 32. groove;

[0044] 4. Steam flow channel. DETAILED DESCRIPTION

[0045] The following will be combined with the drawings in the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the embodiments described are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0046] In order to better describe and illustrate the embodiments of the present application, reference may be made to one or more drawings, but the additional details or examples used to describe the drawings should not be considered as limiting the scope of the utility model invention of the present application, any of the currently described embodiments or preferred methods.

[0047] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application pertains. The terms used herein in the specification of this application are for the purpose of describing specific embodiments only and are not intended to limit this application.

[0048] A steam-water heat exchanger includes at least one heat exchange module, which includes two water pipes 2, a plurality of heat exchange plates 1 and a plurality of seals 3. Figure 1 and Figure 2 shown.

[0049] The two water pipes 2 are respectively the first water pipe and the second water pipe. The first water pipe and the second water pipe have the same structure. Figure 8 As shown, the first water pipe and the second water pipe are provided with water holes 21 on their walls. In one embodiment, the water pipes can be metal hollow circular tubes with one end open and the other end closed, and the water outlets are evenly distributed on the wall of the water pipes.

[0050] The structure of a single heat exchange plate 1 is as follows Figures 3 to 5 As shown, it includes a heat exchange membrane 11 and two water guide boxes 12, and the heat exchange membrane has a plurality of first flow channels 15 arranged in parallel (see Figure 5 ), a water inlet 13 and a water outlet 14 are respectively provided on one of the corners of the heat exchange membrane, and the water inlet 13 and the water outlet 14 are both connected to the corresponding first flow channel. Figures 3 to 5 In the orientation shown, the water inlet 13 is located at the top of the diagonal line of the heat exchange membrane, and the water outlet 14 is located at the bottom of the diagonal line of the heat exchange membrane. The first flow channel 15 penetrates the heat exchange membrane 11 in a direction parallel to the heat exchange membrane, and the water inlet and water outlet penetrate the heat exchange membrane 11 in a direction perpendicular to the heat exchange membrane. The axis of the first flow channel is perpendicular to the axis of the water inlet and water outlet. Figure 5 and Figure 3 From the orientation shown, it can also be understood that the axis of the first flow channel 15 is parallel to the paper surface, and the axial directions of the water inlet and the water outlet are perpendicular to the paper surface.

[0051] The two water guide boxes 12 are respectively located on the opposite sides of the heat exchange diaphragm, and the two water guide boxes are respectively sealed and connected to the two ends of the first flow channel. For example, the heat exchange diaphragm and the two water guide boxes can be welded into a whole. The water guide box 12 is divided into several independent second flow channels 16 by the water barrier 17. The second flow channels 16 are correspondingly connected with the first flow channels 15 to form a liquid flow channel that is folded from top to bottom in the heat exchange plate 1. The inlet of the liquid flow channel is connected with the water inlet of the heat exchange diaphragm, and the outlet of the liquid flow channel is connected with the water outlet of the heat exchange diaphragm.

[0052] The first flow channel 15 in the heat exchange membrane 11 is connected to the second flow channel 16 in the water guide box. A communication method of the first flow channel and the second flow channel is as follows: Figure 5 As shown, each second flow channel 16 corresponds to two adjacent first flow channels 16, and the second flow channels 16 in the two water guide boxes are staggered. The parts of the second flow channels 16 in the two water guide boxes that are staggered in height share one first flow channel 15, and the two adjacent first flow channels 15 are connected in sequence through the corresponding second flow channels 16. Figure 5Taking the orientation shown in as an example, from top to bottom, the first flow channels of the first row and the second row are connected by the second flow channel on the right, the first flow channels of the second row and the third row are connected by the second flow channel on the left, and the parts of the second flow channels on the left and the second flow channels on the right that overlap in height share the first flow channel of the second row, and so on, a liquid flow channel that bends back and forth as shown in 5 is formed in the heat exchange plate.

[0053] The heat exchange membrane is preferably a plastic membrane, for example, a membrane formed by melt-extrusion of polyester or polypropylene plastic and graphite. The membrane is extruded to form a parallel porous structure (through holes are the first flow channels). The mass percentage of graphite is 0.3%-5%. The overall thickness of the heat exchange membrane is 5-8mm; the thickness of each water guide box is 8-12mm, that is, the thickness of the water guide box is greater than the thickness of the heat exchange membrane. Figure 6 .

[0054] The seal 3 is inserted into the portion of the water pipe 2 between adjacent heat exchange plates. The adjacent heat exchange plates are separated by corresponding seals to form a through steam flow channel 4. The steam flow channel and the liquid flow channel, as well as the steam flow channel and the two water pipes are sealed and blocked by the seal 3. On the one hand, the seal 3 separates the adjacent heat exchange plates to form a through steam flow channel 4, and on the other hand, it completely seals and blocks the steam flow channel and the liquid flow channel, so that the low-temperature hot water sent in by the water pipe will not leak into the gap between the adjacent heat exchange plates.

[0055] As an embodiment of the sealing member 3, Figure 7 As shown, the heat exchange module comprises an annular sealing gasket 31 and two sealing washers (not shown). The sealing gasket 31 has an annular groove 32 on each of its axial end faces, and the two sealing washers are respectively embedded in the corresponding grooves 32. The sealing washers are made of a soft, annular polyester material. During the assembly and tightening process of the heat exchange module, they are compressed and deformed to seal the liquid flow path and the wet flue gas / steam flow path. The sealing gasket can be made of a hard material. By adjusting the thickness of the sealing gasket, the gap between the heat exchange membranes in the heat exchange module can be adjusted. Preferably, the thickness of the sealing gasket is between 8 and 20 mm.

[0056] In this application, a single heat exchange plate can be used as an independent production and transportation unit. During the assembly process, see Figure 6 First, put a heat exchange plate on the water pipe (the first water pipe corresponds to the water inlet 13, and the second water pipe corresponds to the water outlet 14), then put the seal 3 on the water pipe, and then put a heat exchange plate on it, and press the heat exchange plate tightly. In this way, assemble and tighten it in sequence to form a heat exchange module (see Figure 1 and Figure 2In the heat exchange module, the water pipe, the internal liquid flow channel of the heat exchange plate, and the seals form the hot water circulation channel, i.e., the liquid flow channel. The gap formed by the seals between two adjacent heat exchange plates constitutes the wet flue gas / steam circulation channel. The heat exchanger and the high-temperature wet flue gas / steam exchange heat indirectly through the wall of the heat exchange plate in countercurrent / crossflow.

[0057] A method for performing steam-water heat exchange using the steam-water heat exchanger as described above includes:

[0058] The low-temperature hot water is fed into the liquid flow channels in each heat exchange plate in parallel from the top of the steam-water heat exchanger by the first water conduit, flows through the liquid flow channels from top to bottom, and then is collected in the second water conduit from the bottom of the steam-water heat exchanger and flows out from the second water conduit; at the same time, the high-temperature wet flue gas or steam is fed into the bottom of the steam-water heat exchanger and flows through the steam flow channels between adjacent heat exchange plates from bottom to top, forming a countercurrent or crosscurrent flow with the low-temperature hot water body in the heat exchange plate, and is discharged from the top of the heat exchanger; the low-temperature hot water and the high-temperature wet flue gas or steam are indirectly exchanged with each other in countercurrent / crosscurrent through the wall of the heat exchange plate, recovering the heat of the wet flue gas or steam, and condensing the water vapor in the wet flue gas or steam into liquid water for recovery.

[0059] This heat exchanger is suitable for steam-water heat exchange scenarios with steam / flue gas temperatures below 70°C. The sealing gasket thickness is 10-20mm; the steam / wet flue gas flow rate in the diaphragm gap is 3.5-6.0m / s, the hot water flow rate in each diaphragm is 50-300L / h, and the temperature difference between the hot water inlet temperature and the steam inlet temperature is greater than 10°C; the operating pressure of low-temperature hot water in each heat exchange plate is 0.02-0.07MPa.

[0060] The technical features of the above-mentioned embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above-mentioned embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0061] The above-described embodiments merely represent several implementation methods of the present application. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the utility model patent. It should be noted that a person skilled in the art could make various modifications and improvements without departing from the spirit of the present application, all of which fall within the scope of protection of the present application. Therefore, the scope of protection of the present patent application shall be determined by the appended claims.

Claims

1. A steam-water heat exchanger, comprising at least one heat exchange module, characterized in that: The heat exchange module includes two water pipes, a number of heat exchange plates and sealing elements; A single heat exchange plate includes: A heat exchange diaphragm having a plurality of parallel first flow channels therein, a water inlet and a water outlet respectively provided at a pair of corners of the heat exchange diaphragm, the first flow channels penetrating the heat exchange diaphragm in a direction parallel to the heat exchange diaphragm, and the water inlet and the water outlet penetrating the heat exchange diaphragm in a direction perpendicular to the heat exchange diaphragm; Two water guide boxes are located on opposite sides of the heat exchange diaphragm and are sealed and connected to the heat exchange diaphragm as a whole. The water guide boxes are divided into a number of independent second flow channels by water barriers. The second flow channels are connected to the first flow channels and form a baffled liquid flow channel in the heat exchange plate. The inlet of the liquid flow channel is connected to the water inlet of the heat exchange diaphragm, and the outlet of the liquid flow channel is connected to the water outlet of the heat exchange diaphragm. The two water pipes include a first water pipe and a second water pipe. The first water pipe and the second water pipe are both hollow cylindrical structures with one end open and the other end sealed. A plurality of water guide holes are evenly opened on the wall of each water pipe. The first water pipe passes through the water inlet of each heat exchange plate, and the second water pipe passes through the water outlet of each heat exchange plate. The first water pipe and the second water pipe are both connected to the liquid flow channel through their water guide holes. A seal is inserted between every two adjacent heat exchange plates on the water pipe. The thickness of each heat exchange membrane is 5~8mm; the thickness of each water guide box is 8~12mm.

2. The steam-water heat exchanger according to claim 1, characterized in that: Each second flow channel corresponds to two adjacent first flow channels and the second flow channels in the two water guide boxes are staggered. The parts of the second flow channels in the two water guide boxes that overlap in height share one first flow channel, and the two adjacent first flow channels are connected in sequence through the corresponding second flow channels.

3. The steam-water heat exchanger according to claim 1, characterized in that: The heat exchange diaphragm is a plastic diaphragm.

4. The steam-water heat exchanger according to claim 1, characterized in that: The sealing member comprises: An annular sealing gasket is sleeved on the water pipe, and both end surfaces of the sealing gasket along the axial direction are provided with annular grooves; The two sealing gaskets are made of soft annular polyester material and are respectively embedded in the corresponding grooves of the sealing gasket. They are used to seal the heat exchange diaphragm and the sealing gasket section during the fastening process of the heat exchange module.

5. The steam-water heat exchanger according to claim 4, characterized in that: The thickness of the sealing gasket is 8-20 mm.

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