A method and device for oscillating flash heat transfer in the pore channels of porous medium particles

Abstract

The present invention discloses a method and device for oscillating flash heat exchange in porous medium particle channels, which belongs to the field of gas-solid two-phase heat exchange technology and aims to solve the problem of how to make porous medium particles and gas-phase heat exchange medium quickly and fully exchange heat to improve the gas-solid two-phase heat exchange effect. The heat exchange method mixes porous medium particles with gas-phase heat exchange medium to form a fluid-solid mixture, and forms a three-dimensional rotating turbulent flow field, which can make the porous medium particles perform self-revolution coupled motion, and then make the gas-phase heat exchange medium in the channel oscillate and flash heat exchange with the porous medium particles, thereby improving the gas-solid two-phase heat transfer performance; by controlling the three-dimensional rotating turbulent flow field, it is ensured that there is at least a flow field section with alternating scale changes, which ensures that the gas-phase heat exchange medium can continue to oscillate for a long time, thereby maintaining the oscillating flash heat exchange process, so that the porous medium particles and the gas-phase heat exchange medium quickly and fully exchange heat, greatly improving the heat exchange effect between the two.

Description

Technical Field

[0001] The present invention belongs to the technical field of gas-solid two-phase heat exchange, and in particular relates to a method and device for oscillating flash heat exchange of porous medium particles. Background Art

[0002] The metallurgical and coal-fired power generation industries produce large quantities of high-temperature slag. Statistics show that, on average, every ton of metal produced produces 350 to 480 kg of high-temperature slag, with tapping temperatures exceeding 1300°C. This slag contains a significant amount of heat energy. Direct discharge of this slag not only wastes energy but also significantly harms the ecological environment. Therefore, it is necessary to develop methods for recovering and utilizing the heat energy from high-temperature slag to reduce energy consumption and emissions and improve energy efficiency in the metallurgical industry. Dry granulation and physical heat exchange are the primary methods for utilizing liquid high-temperature slag and recovering waste heat. For example, Chinese invention patent publication number CN109539821B discloses a method and apparatus for recovering the heat energy from high-temperature metallurgical slag. This method utilizes countercurrent heat exchange between high-temperature metallurgical slag and cold air to generate high-temperature air exceeding 300°C, which is then used for power generation. This method aims to increase the temperature of the gaseous heat exchange medium, speed up the cooling of the slag, and enhance thermal efficiency. Chinese invention patent publication number CN107674929B discloses a method for granulating and exchanging heat of molten liquid slag and a system device thereof, which uses a multi-stage cyclone heat exchanger to form strong convection heat exchange between the granulated slag and cold air, thereby improving the heat exchange effect.

[0003] Similarly, in the cement industry, cement raw meal particles require preheating and decomposition. Cyclone heat exchange is commonly used, mixing high-temperature gas with the cement raw meal and then preheating the cement raw meal through a multi-stage single-row or multi-stage double-row cyclone heat exchanger. For example, Chinese invention patent application publication number CN1210965A and Chinese utility model patent publication number CN2581925Y both utilize a five-stage cyclone system, raising the material temperature to 850°C for decomposition. However, because the cyclones employed tend to be more segregated to prevent loss of the cement raw material, the particles rapidly migrate to the side walls within the cyclone, limiting heat exchange between the particles and the gas. Consequently, the fifth-stage cyclone was replaced with a decomposition furnace.

[0004] According to the above content, in the gas-solid heat exchange needs of different industries, the use of cyclone heat exchangers to promote gas and particle two-phase heat transfer is feasible, but there is still a lot of room for improvement. It can be seen from the convective heat transfer formula (Formula 1) that the essential reason is that the rotation of the particles can fully contact the spirally flowing gas, which promotes the improvement of the convective heat transfer coefficient (k), thereby improving the heat transfer efficiency. Similarly, many studies have shown that the gas-solid contact area (A) can be increased by reducing the particle size, thereby improving the heat transfer performance. This is also one of the commonly used means to enhance heat transfer.

[0005] (1)

[0006] However, whether in the metallurgical industry, coal-fired power generation, or the cement industry, smaller particles are not necessarily better. Too small a particle size can cause it to be carried away from the heat exchanger by the gas, potentially clogging subsequent equipment pipelines or causing raw material loss. Furthermore, the simple internal structure of traditional cyclone heat exchangers can lead to excessive particle accumulation on the heat exchanger walls, which can affect heat transfer between the gas and particles and reduce heat transfer efficiency. Preventing particle movement and accumulation in traditional cyclone heat exchangers is a key issue that needs to be addressed in future designs for improved cyclone heat exchange structures.

[0007] Furthermore, previous gas-solid heat exchange devices have overlooked the coupling between the particle structure and swirl flow. Maximizing the heat transfer potential between porous media particles and the gaseous heat exchange medium to enhance gas-solid two-phase heat transfer is a key issue that needs to be addressed in the design of existing gas-solid heat exchange devices. Summary of the Invention

[0008] The present invention provides a method and device for flash heat exchange of porous medium particle pore oscillation, aiming to solve the problem of how to quickly and fully exchange heat between porous medium particles and gas-phase heat exchange medium to improve the gas-solid two-phase heat exchange effect.

[0009] The technical solution adopted by the present invention to solve the technical problem is: a porous medium particle channel oscillation flash heat exchange method, comprising the following steps:

[0010] S1. Homogeneous mixing of fluid and solid phases: transporting porous medium particles into pressurized gas phase heat exchange medium to mix the two to form a fluid-solid mixture;

[0011] S2, fluid-solid mixing spiral flow: guide the fluid-solid mixture to do three-dimensional spiral motion, forming a three-dimensional rotating turbulent flow field;

[0012] S3. Particle self-rotation coupling: As the porous media particles orbit around the centerline of the three-dimensional rotating turbulent flow field, a rotational couple is applied to the porous media particles under the gradient of the rotational linear velocity of the three-dimensional rotating turbulent flow field, causing the porous media particles to rotate. During the process of the porous media particles' orbital and self-rotation, the gas-phase heat exchange medium in their pores oscillates and flash-exchanges heat with the porous media particles.

[0013] S4. Particle-pore oscillation excitation: The three-dimensional rotating turbulent flow field is controlled to have at least one flow field segment with alternating scales, so that the porous medium particles are repeatedly subjected to rotating couples, maintaining the oscillatory flash heat transfer process. The diameter of the flow field segment with alternating scales is gradually decreasing and then increasing in the downward direction along the centerline of the three-dimensional rotating turbulent flow field.

[0014] S5. Heat and mass separation: After heat exchange, the porous medium particles are separated from the gas phase heat exchange medium.

[0015] Furthermore, the temperature difference between the porous medium particles and the gas phase heat exchange medium is 50-1500°C.

[0016] Furthermore, the particle size of the porous medium particles is 0.1 to 20 mm, and the feed flow rate of the gas phase heat exchange medium is 2 to 35 m / s.

[0017] Furthermore, the minimum diameter of the flow field segment with alternating scales is 0.5 to 0.8 times the maximum inner diameter.

[0018] The present invention also provides a porous medium particle channel oscillation flash heat exchange device, comprising a fluid-solid homogenization module, a fluid-solid swirl generating module, an oscillation excitation module and a heat-mass separation module;

[0019] The fluid-solid homogenizing module is used to receive porous medium particles and gas-phase heat exchange medium and mix the two into a fluid-solid mixture;

[0020] The fluid-solid swirl generating module includes a swirl generating body connected to the output end of the fluid-solid homogenizing module, and a swirl generating structure provided in the swirl generating body for guiding the fluid-solid mixture to perform three-dimensional spiral motion;

[0021] The oscillation excitation module includes at least one diameter-reducing cylinder section coaxially connected to the vortex generator body, wherein the inner diameter of the diameter-reducing cylinder section gradually decreases and then gradually increases along its own axis;

[0022] The input end of the heat and mass separation module is connected to the output end of the oscillation excitation module, and is used to separate the porous medium particles from the gas phase heat exchange medium.

[0023] Furthermore, the fluid-solid homogenizing module includes a first feed pipe connected to the input end of the vortex generator body and having an inlet for gas-phase heat exchange medium, and a second feed pipe connected to the first feed pipe and having a feed port for porous medium particles.

[0024] Furthermore, the vortex generator body is a cylindrical structure with a closed upper end, and the vortex generating structure includes at least two vortex generating blades arranged in the vortex generator body and distributed in a ring array around the axis of the vortex generator body.

[0025] Furthermore, the oscillation excitation module includes at least two coaxially arranged variable diameter cylinder sections, and two adjacent variable diameter cylinder sections are connected by a transition cylinder section;

[0026] The maximum inner diameter D of the reducing cylinder section max Equal to the inner diameter D of the vortex generator body, its minimum inner diameter D min The maximum inner diameter Dmax 0.5 to 0.8 times of.

[0027] Furthermore, the heat and mass separation module includes an inverted cone cylinder connected to the lower end of the oscillation excitation module and maintained coaxially therewith, and the lower end of the inverted cone cylinder is provided with a porous medium particle discharge port.

[0028] Furthermore, the heat exchange device also includes an exhaust module;

[0029] The exhaust module includes a gas exhaust pipe, which is coaxially arranged with the vortex maker body. The upper end of the gas exhaust pipe has a gas exhaust port higher than the vortex maker body, and the lower end of the gas exhaust pipe passes through the inner cavity of the vortex maker body and the inner cavity of the reducing cylinder section and extends into the inner cavity of the inverted cone cylinder.

[0030] The beneficial effects of the present invention are as follows:

[0031] (1) The heat exchange method provided by the present invention mixes porous medium particles with gas-phase heat exchange medium to form a fluid-solid mixture, and makes the fluid-solid mixture form a three-dimensional rotating turbulent flow field, which can make the porous medium particles rotate while performing orbital motion, thereby making the gas-phase heat exchange medium in its pores oscillate and flash heat exchange with the porous medium particles; on the basis of the heat exchange on the surface of the porous medium particles, a particle pore heat exchange mechanism is further formed, which not only increases the heat exchange area between the porous medium particles and the gas-phase heat exchange medium, but also promotes a significant improvement in the convective heat transfer coefficient, thereby achieving an improvement in the gas-solid two-phase heat transfer performance.

[0032] (2) By controlling the three-dimensional rotating turbulent flow field so that there is at least one flow field segment with alternating scale changes, not only can the gas-phase heat exchange medium be guaranteed to oscillate for a long time, thereby maintaining the oscillating flash heat exchange process, but also because the convective heat transfer coefficient of the oscillating flow of the gas-phase heat exchange medium in the pores is also related to the oscillation frequency, the oscillation frequency increased by the alternating scale change is conducive to the increase of the convective heat transfer coefficient, further enhancing the heat transfer performance; therefore, the porous medium particles and the gas-phase heat exchange medium can exchange heat quickly and fully, greatly improving the heat exchange effect between the two and improving the heat recovery rate.

[0033] (3) The heat exchange device provided by the present invention is mainly composed of a fluid-solid homogenization module, a fluid-solid vortex generating module, an oscillation excitation module and a heat-mass separation module. It can not only realize the above-mentioned heat exchange method, but also has a simple and compact structure and high heat exchange efficiency. Compared with the existing gas-solid heat exchange device, under the condition of achieving the same heat exchange effect, the number of stages can be reduced, which is conducive to reducing the construction land and investment costs of the heat exchange system.

[0034] The technical effects brought about or directly produced by other technical features of the present invention will be described in detail in the subsequent specific implementation methods. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 This is a process flow chart of a porous medium particle channel oscillation flash heat exchange method provided by the present invention;

[0036] Figure 2 This is a schematic structural diagram of a porous medium particle channel oscillation flash heat exchange device provided by the present invention;

[0037] Figure 3 This is a heat exchange principle of a porous medium particle channel oscillation flash heat exchange device provided by the present invention and a corresponding diagram of the rotational couple and oscillation changes of porous medium particles at different positions;

[0038] Figure 4 1 is a diagram showing the manufacturing cost of different numbers of oscillation excitation units and their effect on the temperature of the slag after heat exchange in Example 1;

[0039] Marked in the figure: 100-fluid-solid homogenization module, 101-porous medium particle feed inlet, 102-gas phase heat exchange medium inlet, 110-fluid-solid swirl module, 111-swirl blades, 120-oscillation excitation module, 130-heat and mass separation module, 131-porous medium particle discharge outlet, 141-gas discharge pipe, 142-gas discharge outlet. DETAILED DESCRIPTION

[0040] The present invention will be further described below with reference to the accompanying drawings and embodiments. The same reference numerals in the accompanying drawings represent components with the same or similar functions. Although various aspects of the embodiments are shown in the accompanying drawings, the drawings are not necessarily drawn to scale unless otherwise indicated.

[0041] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like to indicate orientations or positions, and dimensional relationships are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of description, and do not indicate or imply that the device or component referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0042] When the term "plurality" refers to a quantity, it generally refers to three or more. For example, "a plurality" generally refers to three or more. Terms like "about" and "approximately" used to describe a numerical range generally refer to a range within ±10%. For example, "approximately 100 mm" generally refers to 90-110 mm. The expression "consisting primarily of" should be interpreted as including components not mentioned in the sentence. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0043] like Figure 1 As shown, a porous medium particle channel oscillation flash heat exchange method includes the following steps:

[0044] S1. Homogeneous mixing of fluid and solid phases: Porous media particles are transported into a pressurized gaseous heat exchange medium to mix the two to form a fluid-solid mixture. Since temperature difference is the driving force for heat transfer, a certain temperature difference between the porous media particles and the gaseous heat exchange medium is required, and the temperature difference between the two is usually 50-1500°C. Heat can be exchanged between high-temperature porous media particles and low-temperature gaseous heat exchange medium, or between low-temperature porous media particles and high-temperature gaseous heat exchange medium. The porous media particles can be particles of metallurgical slag, high-temperature coal ash, or cement raw meal. The gaseous heat exchange medium can be gases such as air, nitrogen, or water vapor. The pressure of the pressurized gaseous heat exchange medium is usually above 1 atm.

[0045] S2. Fluid-solid mixing spiral flow: The fluid-solid mixture is guided to perform a three-dimensional spiral motion, forming a three-dimensional rotating turbulent flow field. Generally, the fluid-solid mixture can be guided to perform a three-dimensional spiral motion by using a vortex-generating structure such as a three-dimensional spiral groove, a vortex-generating impeller, a vortex-generating blade group, or a circular cavity tangential inlet structure.

[0046] S3. Particle self-rotation coupling: As the porous media particles orbit around the centerline of the three-dimensional rotating turbulent flow field, a rotational couple is applied to the porous media particles under the gradient of the rotational linear velocity of the three-dimensional rotating turbulent flow field, causing the porous media particles to rotate. During the process of the porous media particles' orbital and self-rotation, the gas-phase heat exchange medium in their pores oscillates and flash-exchanges heat with the porous media particles.

[0047] S4. Particle Pore Oscillation Excitation: The three-dimensional rotating turbulent flow field is controlled to have at least one flow field segment with alternating scales. This allows the porous media particles to be repeatedly subjected to rotating couples, causing the gas-phase heat exchange medium in their pores to continuously oscillate, thereby maintaining the oscillating flash heat transfer process. The diameter of the flow field segment with alternating scales gradually decreases and then increases in a downward direction along the centerline of the three-dimensional rotating turbulent flow field.

[0048] S5. Heat and mass separation: After the fluid-solid mixture has undergone heat exchange, the porous medium particles are separated from the gaseous heat exchange medium. Generally, the two can be separated by centrifugation or filtration. Preferably, the porous medium particles that have undergone sufficient heat exchange and the gaseous heat exchange medium are transported into a cyclone separator, and the centrifugal effect is used to make the porous medium particles adhere to the wall of the cone section of the cyclone separator and spiral down to be discharged from the bottom outlet, while the gaseous heat exchange medium forms an internal vortex flow field and spirals up to be discharged from the top outlet.

[0049] This heat transfer method further forms a particle channel heat transfer mechanism based on the surface heat transfer of porous medium particles. That is, when the porous medium particles rotate, the gas phase heat transfer medium in the channel is affected by the turbulent airflow on the particle surface, and continuously oscillates in the channel to participate in the convection heat transfer process inside the channel, which increases the heat transfer area (A) of the porous medium particles. Not only the particle surface ( ) participates in heat transfer, the inner surface of the pore ( ) also participates in the heat transfer (see formula 2), which not only increases the heat transfer area between the porous medium particles and the gas-phase heat transfer medium, but also significantly improves the convective heat transfer coefficient (k), thereby improving the gas-solid two-phase heat transfer performance. By controlling the three-dimensional rotating turbulent flow field so that there is at least one flow field segment with alternating scale changes, it can not only ensure that the gas-phase heat transfer medium oscillates for a long time, thereby maintaining the oscillating flash heat transfer process, but also because the convective heat transfer coefficient (k) of the oscillating flow of the gas-phase heat transfer medium in the pores is not only related to the basic Nusselt number (Nu), Prandtl number (Pr) and Reynolds number (Re), but also to the oscillation frequency (F pore ) (see Equation 3). The increased oscillation frequency caused by the alternating scales contributes to an increase in the convective heat transfer coefficient; thus, it allows for rapid and sufficient heat exchange between the porous media particles and the gas-phase heat exchange medium, significantly enhancing the heat exchange efficiency between the two and increasing the heat recovery rate. Furthermore, the alternating scale flow field segments allow the porous media particles to repeatedly break away from the walls that constrain them, allowing them to move toward the axis, thus preventing the porous media particles from stacking on the walls and hindering gas-solid heat exchange.

[0050] (2)

[0051] (3)

[0052] In some embodiments, porous media particles with a particle size of 0.1 to 20 mm are preferably used for heat exchange, in order to provide a larger specific surface area and more pores to enhance heat transfer efficiency. To generate vortex in the solid-convection mixture, increase the convective heat transfer rate, and reduce pressure loss, the feed flow rate of the gas-phase heat exchange medium is preferably controlled at 2 to 35 m / s. Furthermore, when the porous media particle size is 0.1 to 10 mm, the feed flow rate of the gas-phase heat exchange medium is controlled at 2 to 12 m / s; when the porous media particle size is 10 to 20 mm, the feed flow rate of the gas-phase heat exchange medium is controlled at 15 to 35 m / s.

[0053] In some embodiments, in order to ensure smooth flow of the fluid-solid mixture and reduce the wall adhesion time of the porous medium particles, the minimum diameter of the flow field segment with alternating scales is preferably 0.5 to 0.8 times its maximum inner diameter.

[0054] like Figure 2 As shown, a porous medium particle channel oscillation flash heat exchange device includes a fluid-solid homogenization module 100, a fluid-solid swirl generating module 110, an oscillation excitation module 120 and a heat-mass separation module 130;

[0055] The fluid-solid homogenizing module 100 is used to receive porous medium particles and gas-phase heat exchange medium and mix the two into a fluid-solid mixture; the fluid-solid homogenizing module 100 can be a feeding and mixing pipeline assembly, a feeding and mixing integrated machine, etc.

[0056] The fluid-solid swirl generating module 110 includes a swirl generating body connected to the output end of the fluid-solid homogenizing module 100, and a swirl generating structure disposed within the swirl generating body for guiding the fluid-solid mixture to perform a three-dimensional spiral motion. The swirl generating structure may be a three-dimensional spiral groove, a swirl generating impeller, a swirl generating blade assembly, a circular cavity tangential inlet flow structure, or the like.

[0057] The oscillation excitation module 120 includes at least one variable diameter cylinder section coaxially connected to the vortex generator body, the inner diameter of which gradually decreases and then gradually increases along its own axis. The variable diameter cylinder section serves as an important structure for oscillation excitation and maintenance, and has an oscillation excitation unit composed of a coaxially connected gradually converging flow channel and a gradually expanding flow channel, and the internal space is generally hourglass-shaped. Generally, one or more variable diameter cylinder sections can be selected according to the particle size of the porous medium particles. The inner diameters of the upper and lower ends of the variable diameter cylinder section are generally equal.

[0058] The input end of the heat and mass separation module 130 is connected to the output end of the oscillation excitation module 120 to separate the porous medium particles from the gas phase heat exchange medium; the heat and mass separation module 130 can be a cyclone separator, a filter separator, a sedimentation separator, etc.

[0059] For example Figure 2As shown, in some embodiments, to simplify the structure, the fluid-solid homogenizing module 100 includes a first feed pipe connected to the input end of the vortex generator body and having a gas-phase heat exchange medium inlet 102, and a second feed pipe connected to the first feed pipe and having a porous medium particle feed port 101. To facilitate mixing and feeding, the first feed pipe is preferably arranged horizontally, and the second feed pipe is preferably arranged vertically above the first feed pipe.

[0060] For example Figure 2 As shown, in some embodiments, the swirler body is a cylindrical structure with a closed upper end, capable of providing a feeding and swirling space for the fluid-solid mixture. The swirling structure includes at least two swirling blades 111 disposed within the swirler body and arranged in an annular array around the axial axis of the swirler body to guide the fluid-solid mixture in a three-dimensional spiral motion. Considering that the swirling motion of the fluid-solid mixture significantly influences the oscillation excitation of gas within the pores of the porous media particles, to ensure sufficient rotation of the fluid-solid mixture, preferably four to eight swirling blades 111 are arranged.

[0061] For example Figure 2 As shown, in some embodiments, the oscillation excitation module 120 includes at least two coaxially arranged variable diameter cylinder sections, and two adjacent variable diameter cylinder sections are connected by a transition cylinder section; in order to facilitate the connection, the maximum inner diameter D of the variable diameter cylinder section is usually max Equal to the inner diameter D of the vortex generator body; in order to ensure that the porous medium particles can smoothly pass through the minimum inner diameter D of the variable diameter cylinder section min To avoid particle blockage, the minimum inner diameter D of the reducer section is usually min Not less than the maximum inner diameter D max 0.5 times; at the same time, in order to avoid the minimum inner diameter D of the reducer section min Too large, which causes the porous medium particles to stick to the inner wall for too long, usually making the minimum inner diameter D of the reducer section min Not greater than the maximum inner diameter D max In this way, it is ensured that the fluid-solid mixture flows smoothly through the interior of the oscillation excitation module 120 and that the porous medium particles and the gas-phase heat exchange medium can fully exchange heat.

[0062] For example Figure 2 As shown, in some embodiments, the heat and mass separation module 130 includes an inverted cone-shaped cylinder connected to the lower end of the oscillation excitation module 120 and maintained coaxially therewith. The lower end of the inverted cone-shaped cylinder is provided with a porous medium particle discharge port 131. To achieve efficient separation of the fluid-solid mixture, the cone angle of the inverted cone-shaped cylinder is preferably half α, and 3°≤α≤45°.

[0063] For example Figure 2As shown, in some embodiments, the heat exchange device also includes an exhaust module; the exhaust module includes a gas exhaust pipe 141, the gas exhaust pipe 141 is coaxially arranged with the vortex maker body, the upper end of which has a gas exhaust port 142 higher than the vortex maker body, and the lower end of which passes through the inner cavity of the vortex maker body and the inner cavity of the reducing cylinder section and extends into the inner cavity of the inverted cone cylinder, so as to facilitate the smooth discharge of the gas-phase heat exchange medium. Since the gas exhaust pipe 141 passes through the inner cavity of the vortex maker body and the inner cavity of the reducing cylinder section and extends into the inner cavity of the inverted cone cylinder, an annular space for the movement of the fluid-solid mixture is formed in the heat exchange device, which is conducive to the rotational flow of the porous medium particles and the gas-phase heat exchange medium while ensuring that the two have sufficient contact time in each area, thereby suppressing the generation of gas-phase short-circuit flow and the disadvantage of insufficient contact time between the gas and solid phases.

[0064] Combine Figure 2 and Figure 3 As shown, the porous medium particle channel oscillation flash heat exchange device provided by the present invention is used to make the porous medium particles and the gas-phase heat exchange medium perform heat exchange process as follows: the porous medium particles entering from the porous medium particle feed port 101 and the pressurized gas-phase heat exchange medium entering from the gas-phase heat exchange medium inlet 102 are mixed in the pipeline and then transported into the fluid-solid vortex module 110. Under the guidance of the vortex blades 111, the fluid-solid mixture performs three-dimensional spiral motion. At the same time, the porous medium particles are applied with a small rotational force couple through the guiding action of the vortex blades 111, so that the porous medium particles rotate and the gas-phase heat exchange medium in the channels of the porous medium particles oscillates slightly. When the fluid-solid mixture flows into the oscillation excitation module 120, due to the alternating changes in the inner diameter scale of the variable diameter cylinder section, the porous medium particles are subjected to a larger rotational force couple, generating a higher speed and frequency self-revolution coupled motion. At this time, the surface airflow of the porous medium particles is also affected by the rotation of the particles, and the surface airflow continuously falls off at the tail vortex. A Karman vortex step is formed, causing the wall airflow to be in an oscillating state, causing the gas-phase heat exchange medium in the channel to be oscillated by the airflow outside the channel, thereby inducing gas inflow and outflow. In addition, the centrifugal force generated by the revolution and rotation of the porous medium particles intensifies the tendency of the gas-phase heat exchange medium in the channel to move toward the particle surface, causing the fluid in the channel to be subjected to periodic tension and compression transformations. At the same time, the action of the gradually converging and expanding flow channels in the reducing cylinder section can maintain the self-revolutionary coupled motion of the porous medium particles, inhibiting the wall motion of the porous medium particles. This allows the porous medium particles to fully contact with the gas-phase heat exchange medium, while the oscillation amplitude and frequency of the gas-phase heat exchange medium in the channel are enhanced, thereby improving the heat exchange effect between the gas and solid phases. After sufficient heat exchange, the fluid-solid mixture flows into the heat and mass separation module 130, and the porous medium particles spirally descend along the wall and are discharged from the porous medium particle outlet 131 at the bottom, while the gas-phase heat exchange medium forms an internal vortex flow field and spirally rises along the gas discharge pipe 141 and is discharged from the gas outlet 142.

[0065] Example 1

[0066] This embodiment analyzes the matching relationship between the number of oscillation excitation units and the particle size of porous medium particles. A porous medium particle channel oscillation flash heat exchange method provided by the present invention is used to conduct gas-solid heat exchange tests. The heat exchange devices respectively use an existing gas-solid heat exchange device (without oscillation excitation units) and a porous medium particle channel oscillation flash heat exchange device provided by the present invention with 1 to 5 oscillation excitation units. The porous medium particles use three types of steel slag particles with a temperature of 400 ° C and particle sizes of 1 mm, 10 mm, and 20 mm, respectively. Air is used as the gas-phase heat exchange medium, and the feed flow rate is 20 m / s. After heat exchange, the changes in the outlet temperature of the steel slag particles and the number of oscillation excitation units and the cumulative manufacturing cost of the oscillation excitation units are as follows: Figure 4 As shown in the figure, the optimal heat transfer effect for steel slag particles of different particle sizes corresponds to different numbers of oscillation excitation units. As the number of oscillation excitation units increases, the temperature of the three steel slag particle sizes at the heat exchanger outlet first decreases significantly and then tends to level off, while the cumulative manufacturing cost shows a gradually increasing trend. Considering the manufacturing cost and heat transfer effect, the following conclusions can be drawn: for steel slag particles with a particle size of 1 mm, a heat exchanger with one oscillation excitation unit is suitable for heat transfer; for steel slag particles with a particle size of 10 mm, a heat exchanger with three or four oscillation excitation units is suitable for heat transfer; and for steel slag particles with a particle size of 20 mm, a heat exchanger with four oscillation excitation units is suitable for heat transfer.

[0067] Example 2

[0068] This example analyzes the physical and chemical properties of porous media particles. Porous steel slag particles obtained from a certain metallurgical process are used as porous media particles. The mass percentages of the chemical components are shown in the following table:

[0069]

[0070] The physical properties of porous steel slag particles are shown in the following table:

[0071] Physical and chemical properties value Particle size 0.1 mm~5 mm density <![CDATA[3.6 g / cm 3 ]]> Specific surface area <![CDATA[0.3 m 2 / g]]> Porosity 12.05%

[0072] According to the physical properties of porous steel slag particles, the total surface area of 1 g of porous steel slag particles (A surface +A pore ) and the surface area of 1 g slag sphere (A surface) ratio is approximately 1500:1. Therefore, the contact area between the gaseous heat exchange medium and the porous slag particles is significantly increased, potentially increasing the heat exchange area. In this example, porous slag particles (1400°C) were used for heat exchange, with a feed mass flow rate of 100 kg / s and a particle size of 1 to 3 mm. Because the porous slag particles have a relatively small particle size and a large heat exchange specific surface area, a heat exchange device with one oscillation excitation unit was selected for testing based on the results of Example 1. The gaseous heat exchange medium was air (25°C), with a feed flow rate of 20 m / s and a pressure of 1 atm. After heat exchange, the porous slag particles discharged from the porous medium particle outlet 131 had a mass flow rate of 100 kg / s and a temperature of 522°C. The gaseous heat exchange medium discharged from the gas outlet 142 had a temperature of 613°C, a flow rate of 31 m / s, and a pressure of 1.11 atm. Under the same conditions, the heat transfer results are compared with those of the existing gas-solid heat exchange device (without oscillation excitation unit), as shown in the following table:

[0073] Waste heat recovery method The present invention Existing gas-solid heat exchange device Gas outlet temperature 613 ℃ 498 ℃ Slag outlet temperature 522 ℃ 641 ℃

[0074] It can be seen that the temperature of the gas-phase heat exchange medium is increased to 498°C after heat exchange by the existing gas-solid heat exchange device, while the porous medium particle channel oscillation flash heat exchange device provided by the present invention can achieve the temperature of the gas-phase heat exchange medium after heat exchange to be increased to 613°C. Compared with the former, the temperature of the gas-phase heat exchange medium after heat exchange of the present invention increases by 23%. It can be seen that it enhances the gas-solid heat exchange effect and improves the waste heat recovery efficiency.

[0075] Example 3

[0076] A gas-solid heat exchange test was conducted using a porous medium particle pore oscillation flash heat exchange method and device provided by the present invention. This embodiment uses high-temperature ash from a coal-fired boiler as the porous medium particles. The particle size of the high-temperature ash is 10 to 20 mm. Compared with the porous steel slag particles in Example 2, the former has a larger particle size. According to the results of Example 1, a heat exchange device with three oscillation excitation units was selected for the test. The feed mass flow rate of the high-temperature ash is 1.6 kg / s and the temperature is 900 °C; the gas-phase heat exchange medium is air, the temperature is 25 °C, and the feed flow rate is 35 m / s. Under the same conditions, the heat exchange results are compared with those of the existing gas-solid heat exchange device (without an oscillation excitation unit), as shown in the following table:

[0077] Waste heat recovery method The present invention Existing gas-solid heat exchange device Gas outlet temperature 504 ℃ 432 ℃ Ash outlet temperature 511 ℃ 597 ℃

[0078] The results show that the temperature of the gas-phase heat exchange medium after heat exchange using the method and device of the present invention is higher than that of the gas-phase heat exchange medium after heat exchange using the existing gas-solid heat exchange device, which is increased by about 17%. The temperature of the ash at the outlet is reduced to 511°C, which is lower than the existing heat exchange results. Therefore, it is shown that the porous medium particle channel oscillation flash heat exchange method and device provided by the present invention can enhance the heat transfer performance of the gas-solid two-phase, thereby enhancing the heat exchange effect.

[0079] The description of various embodiments of the present invention is presented herein for illustrative purposes only and is not intended to be exhaustive or limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments. The terms used herein are selected to best explain the principles of the embodiments, practical applications, or technological advancements, or to enable others skilled in the art to understand the embodiments disclosed herein, as compared to commercially available technology.

[0080] In this article, various embodiments of the present invention may be presented in the form of ranges. It should be understood that the description in range form is merely for convenience and brevity and should not be construed as a hard limit to the scope of the invention. Therefore, the description of a range should be considered to specifically disclose all possible sub-ranges and individual values within the range. For example, a description of a range such as from 1 to 6 should be considered to specifically disclose sub-ranges, such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., as well as individual values within the range, such as 1, 2, 3, 4, 5, 6, which has nothing to do with the width of the range.

[0081] It should be understood that certain features of the invention described in the context of separate embodiments for the sake of clarity may also be provided in combination in a single embodiment. Conversely, various features of the invention described in the context of a single embodiment for the sake of brevity may also be provided individually or in any suitable subcombination, or in any other described embodiment of the invention, where appropriate. Certain features described in the context of various embodiments are not considered essential features of those embodiments unless the embodiment would not function without those features.

[0082] All publications, patents, and patent applications mentioned herein are incorporated herein by reference in their entirety, to the same extent as if each individual publication, patent, or patent application was specifically and individually indicated as being incorporated herein by reference. In addition, the citation or identification of any reference herein should not be construed as an admission that such reference is available as prior art to the present invention. To the extent that section headings are used, such headings should not be construed as necessarily limiting.

Claims

1. A porous medium particle channel oscillation flash heat exchange method, characterized in that: The following steps are involved: S1. Homogeneous mixing of fluid and solid phases: transporting porous medium particles into pressurized gas phase heat exchange medium to mix the two to form a fluid-solid mixture; S2, fluid-solid mixing spiral flow: guide the fluid-solid mixture to do three-dimensional spiral motion, forming a three-dimensional rotating turbulent flow field; S3. Particle self-rotation coupling: As the porous media particles orbit around the centerline of the three-dimensional rotating turbulent flow field, a rotational couple is applied to the porous media particles under the gradient of the rotational linear velocity of the three-dimensional rotating turbulent flow field, causing the porous media particles to rotate. During the process of the porous media particles' orbital and self-rotation, the gas-phase heat exchange medium in their pores oscillates and flash-exchanges heat with the porous media particles. S4. Particle-pore oscillation excitation: The three-dimensional rotating turbulent flow field is controlled to have at least one flow field segment with alternating scales, so that the porous medium particles are repeatedly subjected to rotating couples, maintaining the oscillatory flash heat transfer process. The diameter of the flow field segment with alternating scales is gradually decreasing and then increasing in the downward direction along the centerline of the three-dimensional rotating turbulent flow field. S5. Heat and mass separation: After heat exchange, the porous medium particles are separated from the gas phase heat exchange medium.

2. The porous medium particle channel oscillation flash heat exchange method according to claim 1, characterized in that: The temperature difference between the porous medium particles and the gas phase heat exchange medium is 50-1500°C.

3. The porous medium particle channel oscillation flash heat exchange method according to claim 1, characterized in that: The particle size of the porous medium particles is 0.1 to 20 mm, and the feed flow rate of the gas phase heat exchange medium is 2 to 35 m / s.

4. A porous medium particle channel oscillation flash heat exchange method according to any one of claims 1 to 3, characterized in that: The minimum diameter of the flow field section with alternating scales is 0.5 to 0.8 times the maximum inner diameter.

5. A porous medium particle channel oscillation flash heat exchange device, characterized by: It includes a fluid-solid homogenizing module (100), a fluid-solid swirl generating module (110), an oscillation excitation module (120), and a heat-mass separation module (130); The fluid-solid homogenizing module (100) is used to receive porous medium particles and gas-phase heat exchange medium and mix the two into a fluid-solid mixture; The fluid-solid swirl generating module (110) comprises a swirl generating body connected to the output end of the fluid-solid homogenizing module (100), and a swirl generating structure arranged in the swirl generating body for guiding the fluid-solid mixture to perform three-dimensional spiral motion; The oscillation excitation module (120) comprises at least one diameter-reducing cylinder section coaxially connected to the vortex generator body, wherein the inner diameter of the diameter-reducing cylinder section gradually decreases and then gradually increases along its own axial direction; The input end of the heat and mass separation module (130) is connected to the output end of the oscillation excitation module (120) and is used to separate the porous medium particles from the gas phase heat exchange medium.

6. The porous medium particle channel oscillation flash heat exchange device according to claim 5, characterized in that: The fluid-solid homogenizing module (100) comprises a first feed pipe connected to the input end of the vortex generator body and having a gas-phase heat exchange medium inlet (102), and a second feed pipe connected to the first feed pipe and having a porous medium particle feed port (101).

7. The porous medium particle channel oscillation flash heat exchange device according to claim 5, characterized in that: The vortex generator body is a cylindrical structure with a closed upper end, and the vortex generating structure comprises at least two vortex generating blades (111) arranged in the vortex generator body and distributed in a ring array around the axis of the vortex generator body.

8. The porous medium particle channel oscillation flash heat exchange device according to claim 7, characterized in that: The oscillation excitation module (120) comprises at least two coaxially arranged variable diameter cylinder sections, and two adjacent variable diameter cylinder sections are connected via a transition cylinder section; The maximum inner diameter D of the reducing cylinder section max Equal to the inner diameter D of the vortex generator body, its minimum inner diameter D min The maximum inner diameter D max 0.5 to 0.8 times of.

9. The porous medium particle channel oscillation flash heat exchange device according to claim 7 or 8, characterized in that: The heat and mass separation module (130) comprises an inverted cone cylinder connected to the lower end of the oscillation excitation module (120) and coaxial therewith, and a porous medium particle discharge port (131) is provided at the lower end of the inverted cone cylinder.

10. The porous medium particle channel oscillation flash heat exchange device according to claim 9, characterized in that: Also includes exhaust mods; The exhaust module comprises a gas exhaust pipe (141), which is coaxially arranged with the vortex generator body, and has a gas exhaust port (142) at its upper end that is higher than the vortex generator body, and a lower end that passes through the inner cavity of the vortex generator body and the inner cavity of the reducing cylinder section and extends into the inner cavity of the inverted cone cylinder.

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