Porous medium particle pore channel oscillation flash heat exchange method and device

Abstract

The invention discloses a porous medium particle pore channel oscillation flash heat exchange method and a porous medium particle pore channel oscillation flash heat exchange device, belongs to the technical field of gas-solid two-phase heat exchange, and aims to solve the problem of how to enable porous medium particles and a gas-phase heat exchange medium to quickly and fully exchange heat so as to improve the gas-solid two-phase heat exchange effect. According to the heat exchange method, porous medium particles and a gas-phase heat exchange medium are mixed to form a fluid-solid mixture, the fluid-solid mixture is made to form a three-dimensional rotating turbulent flow field, the porous medium particles can do self-revolution coupling motion, then the gas-phase heat exchange medium in pore channels of the porous medium particles oscillates and conducts flash heat exchange with the porous medium particles, and therefore the gas-phase heat exchange effect is achieved. The gas-solid two-phase heat transfer performance is improved; by controlling the three-dimensional rotating turbulent flow field, the three-dimensional rotating turbulent flow field has at least one flow field section with the size changing alternately, it is guaranteed that the gas-phase heat exchange medium can continuously oscillate for a long time, and therefore the oscillating flash heat exchange process is maintained, the porous medium particles and the gas-phase heat exchange medium rapidly and sufficiently exchange heat, and the heat exchange effect between the porous medium particles and the gas-phase heat exchange medium is greatly improved.

Description

Technical Field

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

[0002] The metallurgical industry and the coal-fired power generation industry generate a large amount of high-temperature molten slag. According to statistics, on average, 350 kg - 480 kg of high-temperature molten slag is generated per ton of metal produced, and the slag discharge temperature is above 1300 °C, containing a large amount of thermal energy. If directly discharged, it will not only cause waste of thermal energy but also cause great damage to the ecological environment. Therefore, it is necessary to develop a method for heat energy recovery and utilization of high-temperature molten slag to achieve energy conservation and emission reduction in the metallurgical industry and improve energy efficiency. Dry granulation and physical heat transfer are the main ways to utilize liquid high-temperature molten slag and recover waste heat. For example: Chinese invention patent with publication number CN109539821B discloses a method and device for heat energy recovery and utilization of high-temperature metallurgical slag, which uses countercurrent heat transfer between high-temperature metallurgical slag and cold air to obtain high-temperature air above 300 °C, and the generated high-temperature hot air is used for power generation. To increase the temperature of the gas-phase heat transfer medium, improve the cooling rate of the molten slag, and enhance the thermal efficiency. Chinese invention patent with publication number CN107674929B discloses a method and its system device for granulating and heat exchanging molten liquid slag, which uses a multi-stage cyclone heat exchanger to form strong convective heat transfer between the granulated molten slag and cold air, and the heat exchange effect is improved.

[0003] Similarly, in the cement industry, cement raw material particles need to be preheated and decomposed. Generally, the way of cyclone heat transfer is adopted, in which high-temperature gas is mixed with cement raw material particles, and the preheating of cement raw material particles is completed through the structural form of a multi-stage single-row or multi-stage double-row cyclone heat exchanger. For example: Chinese invention patent application with publication number CN1210965A and Chinese utility model patent with publication number CN2581925Y both adopt a 5-stage cyclone system to raise the material temperature to 850 °C for decomposition. However, since the adopted cyclone is biased towards separation design to ensure that the cement raw material does not escape, the particles quickly migrate to the side wall in the cyclone, and the contact heat transfer between the particles and the gas is limited. Therefore, a decomposition furnace is used to replace the fifth-stage cyclone.

[0004] According to the above content, among the gas-solid heat transfer requirements in different industries, the method of applying a cyclone heat exchanger to promote heat transfer between gas and particles is feasible, but there is still a large 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 helically flowing gas, promoting the increase of the convective heat transfer coefficient (k). Therefore, the heat transfer efficiency can be improved. Similarly, many studies have shown that the heat transfer performance can be improved by reducing the particle size to increase the gas-solid contact area (A), which 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 industry or cement industry, the smaller the particles are not necessarily better. If the particle size is too small, the particles will be carried away by the gas from the heat exchanger, and the subsequent equipment pipelines are prone to blockage or raw material loss. And the internal structure of the traditional cyclone heat exchanger is simple, and there is a possibility that the particle accumulation will form on the heat exchanger wall due to excessive particle quantity, which will affect the heat transfer effect between the gas and the particles and reduce the heat transfer efficiency. How to avoid the particle wall attachment movement and accumulation in the traditional cyclone heat exchanger is one of the important problems to be solved in the subsequent improvement design of the cyclone heat transfer structure.

[0007] In addition, the coupling characteristics of the particle's own structural characteristics and the swirling flow have been ignored in the previous gas-solid heat exchange devices. How to exert the heat transfer potential between the porous medium particles and the gas-phase heat exchange medium to improve the gas-solid two-phase heat exchange effect is also one of the important problems to be solved in the improvement design of the existing gas-solid heat exchange devices. Summary of the Invention

[0008] The present invention provides a method and device for oscillating flash heat transfer in the pore channels of porous medium particles, aiming to solve the problem of how to enable the porous medium particles to exchange heat quickly and fully with the 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 its technical problems is: a method for oscillating flash heat transfer in the pore channels of porous medium particles, comprising the following steps:

[0010] S1. Homogeneous mixing of fluid-solid two-phase: The porous medium particles are transported into the pressurized gas-phase heat exchange medium to mix the two, forming a fluid-solid mixture;

[0011] S2. Spiral flow of fluid-solid mixture: Guide the fluid-solid mixture to perform three-dimensional spiral motion to form a three-dimensional rotating turbulent flow field;

[0012] S3. Self-rotation coupling of particles: While the porous medium particles revolve around the center line of the three-dimensional rotating turbulent flow field, under the change of the rotational linear velocity gradient of the three-dimensional rotating turbulent flow field, the porous medium particles are applied with a rotational couple, causing the porous medium particles to rotate; during the revolution and rotation of the porous medium particles, the gas-phase heat exchange medium in their pore channels oscillates and flashes heat exchange with the porous medium particles;

[0013] S4. Oscillation excitation of particle pores: Control the three-dimensional rotating turbulent flow field to have at least one flow field segment with alternating scales, so that the porous medium particles are repeatedly affected by the rotational couple to maintain the oscillating flash heat transfer process; the flow field segment with alternating scales is: along the direction downward along the center line of the three-dimensional rotating turbulent flow field, the diameter of this flow field segment first gradually becomes smaller and then gradually becomes larger;

[0014] S5. Thermal 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 - 20 mm, and the feed flow rate of the gas-phase heat exchange medium is 2 - 35 m / s.

[0017] Furthermore, for the flow field section with alternating scales, its minimum diameter is 0.5 - 0.8 times the maximum inner diameter.

[0018] The present invention also provides a porous medium particle pore channel oscillating flash heat exchange device, which includes a fluid-solid homogeneous module, a fluid-solid swirling module, an oscillation excitation module, and a thermal mass separation module;

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

[0020] The fluid-solid swirling module includes a swirling device main body connected to the output end of the fluid-solid homogeneous module, and a swirling structure arranged in the swirling device main body for guiding the fluid-solid mixture to perform three-dimensional spiral motion;

[0021] The oscillation excitation module includes at least one variable-diameter cylinder section coaxially connected to the swirling device main body, and the inner diameter of the variable-diameter cylinder section gradually decreases first and then gradually increases along its own axis;

[0022] The input end of the thermal 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 homogeneous module includes a first feed pipe connected to the input end of the swirling device main body and having a gas-phase heat exchange medium inlet, and a second feed pipe connected to the first feed pipe and having a porous medium particle feed port.

[0024] Furthermore, the swirling device main body is a cylindrical structure with a closed upper end, and the swirling structure includes at least two swirling blades arranged in the swirling device main body and distributed in an annular array around the axis of the swirling device main body.

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

[0026] The maximum inner diameter D of the variable-diameter cylinder section max is equal to the inner diameter D of the swirling device main body, and its minimum inner diameter D min is the maximum inner diameter Dmax 0.5 to 0.8 times of

[0027] Further, the heat and mass separation module includes an inverted conical cylinder connected to the lower end of the oscillation excitation module and coaxial with it, and a porous medium particle discharge port is provided at the lower end of the inverted conical cylinder.

[0028] Further, the heat exchange device further includes an exhaust module;

[0029] The exhaust module includes a gas discharge pipe, the gas discharge pipe is coaxially arranged with the swirler main body, the upper end thereof has a gas discharge port higher than the swirler main body, and the lower end thereof passes through the inner cavity of the swirler main body and the inner cavity of the variable diameter cylinder section and extends into the inner cavity of the inverted conical 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 a 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 around a common center while rotating on their own axes, and further make the gas-phase heat exchange medium in their pores oscillate and flash heat exchange with the porous medium particles; on the basis of 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 significantly improves the convective heat transfer coefficient, realizing the improvement of the heat transfer performance between gas and solid phases.

[0032] (2) By controlling the three-dimensional rotating turbulent flow field to have at least one flow field section with alternating scales, not only can the gas-phase heat exchange medium be ensured to oscillate continuously for a long time, thus maintaining the oscillating flash heat exchange process, but also since the convective heat transfer coefficient of the gas-phase heat exchange medium oscillating in the pores is also related to the oscillation frequency, the increased oscillation frequency caused by the alternating scales is beneficial to the increase of the convective heat transfer coefficient, further strengthening the heat transfer performance; therefore, the porous medium particles and the gas-phase heat exchange medium can be quickly and fully heat exchanged, greatly improving the heat exchange effect between the two and increasing the heat recovery utilization rate.

[0033] (3) The heat exchange device provided by the present invention is mainly composed of a fluid-solid homogeneous module, a fluid-solid swirling module, an oscillation excitation module and a heat and mass separation module. It can not only realize the above 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 beneficial to reducing the construction land and investment cost of the heat exchange system.

[0034] The technical effects brought by or directly generated by other technical features of the present invention will be described in detail in the subsequent specific implementation part. Description of the Drawings

[0035] Figure 1 It is the process flow chart of a method for oscillating flash heat transfer in the pore channels of porous medium particles provided by the present invention;

[0036] Figure 2 It is the structural schematic diagram of a device for oscillating flash heat transfer in the pore channels of porous medium particles provided by the present invention;

[0037] Figure 3 It is the heat transfer principle of a device for oscillating flash heat transfer in the pore channels of porous medium particles provided by the present invention and the corresponding diagram of the porous medium particles under the rotational couple and oscillation changes at different positions;

[0038] Figure 4 It is the diagram of the manufacturing cost of different numbers of oscillation excitation units in Example 1 and the influence on the temperature after heat transfer of steel slag;

[0039] The markings in the figure are: 100 - fluid - solid homogeneous module, 101 - porous medium particle feed inlet, 102 - gas - phase heat - exchange medium inlet, 110 - fluid - solid rotation - creating module, 111 - rotation - creating blade, 120 - oscillation excitation module, 130 - heat and mass separation module, 131 - porous medium particle discharge outlet, 141 - gas discharge pipeline, 142 - gas discharge outlet. Detailed implementation mode

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

[0041] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counter - clockwise", "axial", "radial", "circumferential", etc. indicate the orientation or position and dimension relationship based on the orientation or position relationship shown in the drawings, and are only for the convenience of description, rather than indicating or implying that the device or component referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus cannot be understood as a limitation to the present invention.

[0042] When the term "plural" refers to a quantity, it generally means three or more. For example, "a plurality of" usually means three or more. Terms such as "about" and "around" usually refer to an error within ±10% when describing a numerical range. For example, about 100 mm usually refers to 90 - 110 mm. The expression "consisting essentially of" is interpreted to mean that it may also contain structural components not mentioned in the sentence. In addition, the terms "first" and "second" are only used for descriptive purposes and should not be construed as indicating or implying relative importance.

[0043] As Figure 1 shown, a method for oscillating flash heat transfer in pores of porous medium particles includes the following steps:

[0044] S1. Homogeneous mixing of fluid and solid phases: The porous medium particles are transported into a pressurized gas-phase heat transfer medium to mix the two, forming a fluid-solid mixture; since the temperature difference is the driving force for heat transfer, there needs to be a certain temperature difference between the porous medium particles and the gas-phase heat transfer medium, and the temperature difference between the two is usually 50 - 1500 °C; it can be the heat transfer between high-temperature porous medium particles and low-temperature gas-phase heat transfer medium, or the heat transfer between low-temperature porous medium particles and high-temperature gas-phase heat transfer medium; the porous medium particles can be particles such as metallurgical slag, high-temperature coal ash slag, or cement raw meal; the gas-phase heat transfer medium can be gases such as air, nitrogen, or water vapor; the pressure of the pressurized gas-phase heat transfer medium is usually above 1 atm.

[0045] S2. Spiral flow of fluid-solid mixture: Guide the fluid-solid mixture to perform a three-dimensional spiral motion to form a three-dimensional rotating turbulent flow field; generally, a swirl structure such as a three-dimensional spiral groove, a swirl impeller, a swirl vane group, or a tangential inlet structure for a circular cavity can be used to guide the fluid-solid mixture to perform a three-dimensional spiral motion.

[0046] S3. Coupling of particle self-revolution: While the porous medium particles perform a revolution around the center line of the three-dimensional rotating turbulent flow field, under the change of the rotational linear velocity gradient of the three-dimensional rotating turbulent flow field, a rotational couple is applied to the porous medium particles, causing the porous medium particles to perform a self-rotation motion; during the revolution and self-rotation motion of the porous medium particles, the gas-phase heat transfer medium in their pores oscillates and flashes heat transfer with the porous medium particles.

[0047] S4. Oscillation excitation of particle pores: Control the three-dimensional rotating turbulent flow field so that it has at least one flow field section with alternating scales, and then the porous medium particles are repeatedly affected by the rotational couple, and the gas-phase heat transfer medium in their pores continuously oscillates to maintain the oscillating flash heat transfer process; the flow field section with alternating scales is: along the direction downward of the center line of the three-dimensional rotating turbulent flow field, the diameter of this flow field section first gradually decreases and then gradually increases.

[0048] S5. Thermal mass separation: After the heat exchange between the fluid-solid mixture, the porous medium particles are separated from the gas-phase heat exchange medium; generally, the two can be separated by centrifugation or filtration; preferably, the well-heated porous medium particles and the gas-phase heat exchange medium are transported into a cyclone separator, and the porous medium particles are spirally descended along the wall in the conical section of the cyclone separator and discharged from the bottom outlet by centrifugal action, so that the gas-phase heat exchange medium forms an internal eddy flow field and spirally ascends and is discharged from the top outlet.

[0049] Based on the heat exchange on the surface of the porous medium particles, this heat exchange method further forms a heat exchange mechanism in the particle pores, that is, when the porous medium particles rotate, the gas-phase heat exchange medium in their pores is affected by the turbulent air flow on the particle surface and continuously oscillates in the pores to participate in the convective heat transfer process inside the pores. This increases the heat exchange area (A) of the porous medium particles. Not only the particle surface ( ), but also the inner surface of the pores ( ) participates in the heat exchange (see Equation 2). This not only increases the heat exchange area between the porous medium particles and the gas-phase heat exchange medium, but also significantly promotes the convective heat transfer coefficient (k), achieving an improvement in the heat transfer performance between the gas and solid phases. By controlling the three-dimensional rotating turbulent flow field to have at least one flow field section with alternating scales, not only can the gas-phase heat exchange medium be continuously oscillated for a long time to maintain the oscillating flash heat exchange process, but also since the convective heat transfer coefficient (k) of the gas-phase heat exchange medium oscillating in the pores is not only related to the basic Nusselt number (Nu), Prandtl number (Pr), and Reynolds number (Re), but also related to the oscillation frequency (F pore ) (see Equation 3), the increased oscillation frequency due to the alternating scales is beneficial to the increase of the convective heat transfer coefficient. Therefore, the porous medium particles and the gas-phase heat exchange medium can be quickly and fully heat exchanged, greatly improving the heat exchange effect between the two and increasing the heat recovery utilization rate. In addition, the flow field section with alternating scales can also enable the porous medium particles to repeatedly break away from the wall that restricts them, move towards the axis, thus avoiding the stacking of the porous medium particles at the wall and hindering the gas-solid heat exchange.

[0050] (2)

[0051] (3)

[0052] In some embodiments, in order to enable the porous medium particles to provide a large specific surface area while having more pores to enhance the heat transfer efficiency, it is preferred to use porous medium particles with a particle size of 0.1 - 20 mm for heat transfer; in order to create swirl in the solid-fluid mixture, improve the convective heat transfer rate and reduce the pressure loss, it is preferred to control the feed flow rate of the gas-phase heat transfer medium to 2 - 35 m / s. Further preferably, when the particle size of the porous medium particles is 0.1 - 10 mm, the feed flow rate of the gas-phase heat transfer medium is controlled at 2 - 12 m / s; when the particle size of the porous medium particles is 10 - 20 mm, the feed flow rate of the gas-phase heat transfer medium is controlled at 15 - 35 m / s.

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

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

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

[0056] The solid-fluid swirling module 110 includes a swirling device main body connected to the output end of the solid-fluid homogenization module 100, and a swirling structure arranged inside the swirling device main body for guiding the solid-fluid mixture to perform a three-dimensional spiral motion; the swirling structure can be a variety of structures such as a three-dimensional spiral groove, a swirling impeller, a swirling blade group, a circular cavity tangential inflow structure, etc.;

[0057] The oscillation excitation module 120 includes at least one variable-diameter cylinder section coaxially connected to the swirling device main body, and the inner diameter of the variable-diameter cylinder section gradually decreases first and then gradually increases along its own axis; the variable-diameter cylinder section is an important structure for oscillation excitation and maintenance, and it has an oscillation excitation unit composed of a gradually shrinking flow channel and a gradually expanding flow channel connected coaxially, and the internal space is usually in the shape of an hourglass; generally, one or several variable-diameter cylinder sections can be selected according to the particle size of the porous medium particles; the inner diameters at the upper and lower ends of the variable-diameter cylinder section are usually 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, and is used to separate the porous medium particles from the gas-phase heat transfer medium; the heat and mass separation module 130 can be a variety of devices such as a cyclone separator, a filter separator, a sedimentation separator, etc.

[0059] Again, as Figure 2As shown, in some embodiments, to simplify the structure, the fluid-solid homogenization module 100 includes a first feed pipe connected to the input end of the swirl generator main 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 inlet 101. To facilitate mixing and feeding, it is preferably to horizontally arrange the first feed pipe and vertically arrange the second feed pipe on the upper side of the first feed pipe.

[0060] Again, Figure 2 As shown, in some embodiments, the swirl generator main body is a cylindrical structure with a closed upper end, which can provide a feeding and swirling space for the fluid-solid mixture; the swirling structure includes at least two swirling vanes 111 arranged in an annular array around the axis of the swirl generator main body to guide the fluid-solid mixture to perform a three-dimensional spiral motion. Considering that the swirling motion of the fluid-solid mixture has an important impact on the oscillation excitation of the gas in the pores of the porous medium particles, in order to ensure that the fluid-solid mixture can rotate sufficiently, it is preferably to arrange 4 to 8 swirling vanes 111.

[0061] Again, Figure 2 As shown, in some embodiments, the oscillation excitation module 120 includes at least two coaxially arranged variable-diameter cylinder sections, and adjacent two variable-diameter cylinder sections are connected by a transition cylinder section; for the convenience of matching and connection, usually the maximum inner diameter D of the variable-diameter cylinder section max is equal to the inner diameter D of the swirl generator main body; to ensure that the porous medium particles can smoothly pass through the minimum inner diameter D of the variable-diameter cylinder section min and avoid particle blockage problems, usually the minimum inner diameter D of the variable-diameter cylinder section min is not less than 0.5 times of the maximum inner diameter D max ; at the same time, to avoid the minimum inner diameter D of the variable-diameter cylinder section min from being too large, resulting in too long a contact time between the porous medium particles and its inner wall surface, usually the minimum inner diameter D of the variable-diameter cylinder section min is not greater than 0.8 times of the maximum inner diameter D max . In this way, it can be ensured that the fluid-solid mixture flows smoothly through the inside of the oscillation excitation module 120, and it can be ensured that the porous medium particles and the gas-phase heat exchange medium can fully exchange heat.

[0062] Again, Figure 2 As shown, in some embodiments, the heat and mass separation module 130 includes an inverted cone cylinder connected to the lower end of the oscillation excitation module 120 and coaxial with it, and a porous medium particle discharge port 131 is provided at the lower end of the inverted cone cylinder. To enable the fluid-solid mixture to be efficiently separated, it is preferably to make half of the cone angle of the inverted cone cylinder be α, 3° ≤ α ≤ 45°.

[0063] Again, Figure 2As shown, in some embodiments, the heat exchange device further includes an exhaust module; the exhaust module includes a gas discharge pipe 141, the gas discharge pipe 141 is coaxially arranged with the swirl generator body, and its upper end has a gas discharge port 142 higher than the swirl generator body, and its lower end passes through the inner cavity of the swirl generator body and the inner cavity of the variable diameter section and extends into the inner cavity of the inverted cone cylinder, so as to facilitate the smooth external discharge of the gas-phase heat exchange medium. Since the gas discharge pipe 141 penetrates through the inner cavity of the swirl generator body and the inner cavity of the variable diameter 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 beneficial to the rotation of the porous medium particles and the gas-phase heat exchange medium while ensuring sufficient contact time between the two in each area, thus suppressing the drawback of insufficient gas-solid two-phase contact time caused by the generation of gas-phase short-circuit flow.

[0064] Combined with Figure 2 and Figure 3 As shown, the heat exchange process between the porous medium particles and the gas-phase heat exchange medium using a porous medium particle pore oscillation flash heat exchange device provided by the present invention is as follows: The porous medium particles entering from the porous medium particle feed port 101 are mixed with the pressurized gas-phase heat exchange medium entering from the gas-phase heat exchange medium inlet 102 in the pipeline and then transported into the fluid-solid swirl module 110. Under the guidance of the swirl blades 111, the fluid-solid mixture performs a three-dimensional spiral motion. At the same time, the porous medium particles are applied with a small rotational couple under the guiding action of the swirl blades 111, causing the porous medium particles to rotate self, and the gas-phase heat exchange medium in the pores of the porous medium particles oscillates slightly; When the fluid-solid mixture flows into the oscillation excitation module 120, due to the alternating change of the inner diameter scale of the variable diameter section, the porous medium particles are subjected to a large rotational couple, generating a higher-speed and higher-frequency self-rotation and revolution coupled motion. At this time, the surface airflow of the porous medium particles is affected by the self-rotation of the particles, and the surface airflow continuously detaches at the wake to form a Karman vortex street, so the wall airflow is in an oscillating state, resulting in the gas-phase heat exchange medium in the pores being oscillated by the airflow outside the pores, thus triggering the inflow and outflow of gas. In addition, the centrifugal force formed by the revolution and self-rotation of the porous medium particles intensifies the tendency of the gas-phase heat exchange medium in the pores to move towards the particle surface, resulting in periodic tensile and compressive transformation of the fluid in the pores; At the same time, under the action of the converging and diverging flow channels in the variable diameter section, the self-rotation and revolution coupled motion of the porous medium particles can be maintained, suppressing the wall-attached motion of the porous medium particles, enabling the porous medium particles to be in full contact with the gas-phase heat exchange medium while the oscillation amplitude and frequency of the gas-phase heat exchange medium in its pores are enhanced, thereby improving the heat exchange effect between the gas-solid two phases; After sufficient heat exchange, the fluid-solid mixture flows into the heat and mass separation module 130, and the porous medium particles adhere to the wall and spiral down and are discharged from the porous medium particle discharge port 131 at the bottom, while the gas-phase heat exchange medium forms an inner eddy current flow field and spirals upward and is discharged from the gas discharge port 142 along the gas discharge pipe 141.

[0065] Example 1

[0066] In this embodiment, the matching relationship between the number of oscillation excitation units and the particle size of the porous medium particles is analyzed. An air-solid heat exchange experiment is carried out using a method for oscillating flash heat transfer in the pores of porous medium particles provided by the present invention. The heat exchange devices selected are an existing air-solid heat exchange device (without oscillation excitation units) and a porous medium particle pore oscillating flash heat exchange device with 1 to 5 oscillation excitation units provided by the present invention. The porous medium particles are three kinds of steel slag particles with a temperature of 400 °C and particle sizes of 1 mm, 10 mm, and 20 mm respectively. The gaseous heat exchange medium is air, and the feeding 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 as well as the cumulative manufacturing cost of the oscillation excitation units are as shown in Figure 4 the figure; it can be seen that the optimal heat exchange effects of steel slag particles with different particle sizes correspond to different numbers of oscillation excitation units. As the number of oscillation excitation units increases, the temperatures of the three kinds of steel slag particles at the outlet of the heat exchange device first decrease significantly and then tend to be flat, while the cumulative manufacturing cost shows a gradually increasing trend. Considering the manufacturing cost and heat exchange effect comprehensively, the following conclusions can be drawn: For steel slag particles with a particle size of 1 mm, it is suitable to use a heat exchange device with 1 oscillation excitation unit for heat exchange; for steel slag particles with a particle size of 10 mm, it is suitable to use a heat exchange device with 3 or 4 oscillation excitation units for heat exchange; for steel slag particles with a particle size of 20 mm, it is suitable to use a heat exchange device with 4 oscillation excitation units for heat exchange.

[0067] Example 2

[0068] In this embodiment, the physical and chemical properties of the porous medium particles are analyzed. Taking the porous steel slag particles obtained from a certain metallurgy as the porous medium particles, the mass percentage content of each chemical component is as shown in the following table:

[0069]

[0070] The physical properties of the porous steel slag particles are as 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] Calculated according to the physical properties of the porous steel slag particles, the total surface area (A surface +A pore ) of 1 g of porous steel slag particles and the surface area (A surfaceThe ratio is approximately 1500:1. Therefore, the contact area between the gas-phase heat exchange medium and the porous steel slag particles is significantly increased, thus having the potential to increase the heat exchange area. Using the porous steel slag particles (1400 °C) in this embodiment for heat exchange, the feed mass flow rate is 100 kg / s, the particle size is 1 - 3 mm. Since the particle size of the porous steel slag particles is relatively small and the heat exchange specific surface area is large, according to the results of Example 1, a heat exchange device with 1 oscillation excitation unit is selected for the test. The gas-phase heat exchange medium is air (25 °C), the feed flow rate is 20 m / s, and the pressure during feeding is 1 atm. After heat exchange, the mass flow rate of the porous steel slag particles when discharged from the porous medium particle discharge port 131 is 100 kg / s, and the temperature is 522 °C; the temperature of the gas-phase heat exchange medium when discharged from the gas discharge port 142 is 613 °C, the flow rate is 31 m / s, and the pressure is 1.11 atm. Under the same conditions, compared with the heat exchange results of the existing gas-solid heat exchange device (without an oscillation excitation unit), the following table shows:

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

[0074] It can be seen that after heat exchange by the existing gas-solid heat exchange device, the temperature of the gas-phase heat exchange medium is increased to 498 °C, while a porous medium particle pore 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 in the present invention is increased by 23%. It can be seen that it strengthens the gas-solid heat exchange effect and enhances the waste heat recovery and utilization efficiency.

[0075] Example 3

[0076] A gas-solid heat exchange test is carried out using a porous medium particle pore oscillation flash heat exchange method and device provided by the present invention. In this embodiment, the high-temperature ash slag of a coal-fired boiler is used as the porous medium particle, and the particle size of the high-temperature ash slag is 10 - 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 3 oscillation excitation units is selected for the test. The feed mass flow rate of the high-temperature ash slag 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, compared with the heat exchange results of the existing gas-solid heat exchange device (without an oscillation excitation unit), the following table shows:

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

[0078] As can be seen from the results, the temperature of the gaseous heat exchange medium after heat exchange using the method and device of the present invention is higher than that of the gaseous heat exchange medium after heat exchange by the existing gas-solid heat exchange device, with an increase of about 17%. The temperature of the ash slag at the outlet is reduced to 511 °C, which is lower than the existing heat exchange result. Therefore, it shows that a porous medium particle pore oscillation flash heat exchange method and device provided by the present invention can strengthen the heat transfer performance of the gas-solid two-phase, thereby enhancing the heat exchange effect.

[0079] This description of various embodiments of the present invention is presented 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 chosen to best explain the principles of the embodiments, practical applications, or technological advancements, or to enable other skilled artisans in the art to understand the embodiments disclosed herein, as compared to the technologies found in the market.

[0080] In this document, various embodiments of the present invention may be presented in a range format. It should be understood that the description in range format is merely for convenience and brevity and should not be construed as a rigid limitation on the scope of the present invention. Thus, the description of a range should be considered to specifically disclose all possible sub-ranges as well as the individual values within that 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 the individual values within that range, such as 1, 2, 3, 4, 5, 6, regardless of the width of the range.

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

[0082] All publications, patents, and patent applications mentioned herein are hereby incorporated by reference in their entirety as if each individual publication, patent, or patent application was specifically and individually indicated to be incorporated by reference. Additionally, the citation or identification of any reference in this document should not be construed as an admission that such reference is available as prior art to the present invention. With respect to the use of section headings, the section headings should not be construed as necessary limitations.

Claims

1. A method for oscillating flash heat transfer in the pore channels of porous medium particles, characterized in that, It includes the following steps: S1. Fluid-solid two-phase homogeneous mixing: Porous medium particles are transported into a pressurized gas-phase heat exchange medium to mix the two, forming a fluid-solid mixture; S2. Fluid-solid mixed spiral flow: Guide the fluid-solid mixture to perform a three-dimensional spiral motion to form a three-dimensional rotating turbulent flow field; S3. Particle self-rotation coupling: While the porous medium particles perform a revolution around the center line of the three-dimensional rotating turbulent flow field, under the change of the rotational linear velocity gradient of the three-dimensional rotating turbulent flow field, a rotational couple is applied to the porous medium particles, causing the porous medium particles to perform a self-rotation motion; during the process of the porous medium particles performing revolution and self-rotation motions, the gas-phase heat exchange medium in their pores oscillates and flashes heat exchange with the porous medium particles; S4. Particle pore oscillation excitation: Control the three-dimensional rotating turbulent flow field so that there is at least one flow field segment with alternating scales, so that the porous medium particles are repeatedly affected by the rotational couple to maintain the oscillating flash heat exchange process; the flow field segment with alternating scales is: along the direction downward of the center line of the three-dimensional rotating turbulent flow field, the diameter of this flow field segment first gradually decreases and then gradually increases; S5. Heat and mass separation: After heat exchange, separate the porous medium particles from the gas-phase heat exchange medium.

2. A method for oscillating flash heat transfer in the pore channels of porous medium particles 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. A method for oscillating flash heat transfer in the pores of a porous medium particle according to claim 1, characterized in that: The particle size of the porous medium particles is 0.1 - 20 mm, and the feed flow rate of the gas-phase heat exchange medium is 2 - 35 m / s.

4. A method for oscillating flash heat transfer in the pore channels of porous medium particles according to any one of claims 1 to 3, characterized in that: For the flow field segment with alternating scales, its minimum diameter is 0.5 - 0.8 times the maximum inner diameter.

5. A porous medium particle pore channel oscillating flash heat exchange device, characterized in that: It includes a fluid-solid homogeneous module (100), a fluid-solid swirling module (110), an oscillation excitation module (120), and a heat and mass separation module (130); The fluid-solid homogeneous module (100) is used to receive porous medium particles and a gas-phase heat exchange medium and mix the two into a fluid-solid mixture; The fluid-solid swirling module (110) includes a swirling main body connected to the output end of the fluid-solid homogeneous module (100), and a swirling structure arranged in the swirling main body for guiding the fluid-solid mixture to perform a three-dimensional spiral motion; The oscillation excitation module (120) includes at least one variable-diameter cylinder section coaxially connected to the swirling main body, and the inner diameter of the variable-diameter cylinder section gradually decreases and then gradually increases along its own axis; 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 pore channel oscillating flash heat exchange device according to claim 5, characterized in that: The fluid-solid homogeneous module (100) includes a first feed pipe connected to the input end of the swirling main 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. A porous medium particle pore channel oscillating flash heat exchange device according to claim 5, characterized in that: The swirling main body is a cylindrical structure with a closed upper end, and the swirling structure includes at least two swirling vanes (111) arranged in the swirling main body and distributed in an annular array around the axis of the swirling main body.

8. A porous medium particle pore channel oscillating flash heat exchange device according to claim 7, characterized in that: The oscillation excitation module (120) includes at least two coaxially arranged variable-diameter cylinder sections, and adjacent variable-diameter cylinder sections are connected by a transition cylinder section; The maximum inner diameter D of the variable-diameter cylinder section max is equal to the inner diameter D of the swirler main body, and its minimum inner diameter D min is 0.5 to 0.8 times of the maximum inner diameter D max .

9. A porous medium particle pore channel oscillating flash heat exchange device according to claim 7 or 8, characterized in that: The heat-mass separation module (130) includes an inverted conical cylinder body 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 conical cylinder body.

10. A porous medium particle pore channel oscillating flash heat exchange device according to claim 9, characterized in that: An exhaust module is further included; The exhaust module includes a gas discharge pipe (141), the gas discharge pipe (141) is coaxially arranged with the swirler main body, a gas discharge port (142) higher than the swirler main body is provided at its upper end, and its lower end extends into the inner cavity of the inverted conical cylinder body through the inner cavity of the swirler main body and the inner cavity of the reduced diameter cylinder section.

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