A mobile bed heat exchanger and a directional regulation and control disturbance enhanced heat exchange method thereof

Abstract

The application discloses a mobile bed heat exchanger and a directional regulation and control disturbance enhanced heat exchange method thereof. The mobile bed heat exchanger comprises a driving chain, a transmission mechanism, a driving motor with a control system, a disturbance part performing horizontal sinusoidal motion and a temperature sensor. The directional regulation and control disturbance enhanced heat exchange method of the mobile bed heat exchanger is mainly realized through the driving chain, the disturbance part performing horizontal sinusoidal motion and the driving motor with the control system. When high-temperature bulk materials enter the heat exchanger, the driving motor drives the disturbance part through the chain to simultaneously perform horizontal sinusoidal motion above and below the heat exchange pipe, and the bulk materials are disturbed. Based on the design, the particle accumulation area and the cavity area above and below the heat exchange pipe are respectively destroyed, the bulk material flow direction is changed to "turbulent flow" with strong heat and mass exchange, and the heat exchange efficiency is improved. The device is suitable for indirect heat exchange between solid bulk materials with small thermal diffusion coefficient and poor fluidity and different fluid media.

Description

Technical Field

[0001] This invention belongs to the field of industrial heat recovery and energy saving technology, and specifically relates to a moving bed heat exchanger and its directional control turbulence-enhanced heat transfer method, which can quickly achieve the purpose of enhanced heat transfer in the moving bed heat exchanger. Background Technology

[0002] Industries such as metallurgy and building materials generate a large amount of industrial bulk materials containing considerable waste heat every year. According to incomplete statistics, my country's annual output of high-temperature solid bulk materials is approximately 4.5 billion tons, equivalent to 100 million tons of standard coal, of which 60% of the waste heat remains unutilized. The rational recovery of waste heat from solid bulk materials can yield significant economic and environmental benefits. However, the recovery of waste heat from industrial solid bulk materials has not yet received widespread attention or application.

[0003] Current solid bulk material waste heat recovery devices have gradually shifted from the widely used direct heat exchange methods such as fluidized beds and stacked beds to indirect heat exchange technologies like gravity-driven moving bed heat exchangers. Compared to traditional heat exchange technologies, gravity-driven moving bed heat exchanger systems are simpler. The heat exchange tubes are arranged from top to bottom, with the circulating working fluid channel located inside the tubes and the bulk material flow channel located outside. High-temperature solid bulk material flow and the circulating working fluid exchange heat through indirect heat exchange. Therefore, the working fluid inside the tubes can be freely selected based on the intended use of the waste heat, such as air, water, or thermal oil, which is beneficial for recovering high-quality waste heat and achieving cascade utilization. This indirect heat exchange method has advantages such as low cost, low heat loss, applicability to bulk material flows with wide particle sizes, and broad application range.

[0004] However, gravity-driven moving bed heat exchangers currently have lower heat exchange efficiency compared to traditional heat exchange methods such as fluidized beds and packed beds. In moving beds, the particle velocity is typically on the order of mm / s, and heat exchange is primarily conduction, with heat in the bulk material flow transferred to the fluid inside the pipes via thermal diffusion. However, the thermal diffusivity of actual industrial bulk materials is low. The thermal conductivity of the solid phase is generally below 2 W / (m·K), but the density exceeds 1000 kg / m³. 3 Furthermore, interparticle air further restricts heat conduction in bulk materials. Therefore, particle-side heat transfer enhancement technology is still needed in moving bed systems to promote uniform flow and heat exchange of bulk materials.

[0005] In conclusion, in the field of industrial solid bulk material waste heat recovery, developing a reasonable gravity-driven moving bed indirect heat exchange enhancement technology is of great significance for the in-depth utilization of bulk material waste heat and can achieve good economic and environmental benefits. Summary of the Invention

[0006] In view of the current demand for enhanced heat transfer on the particle side of moving bed heat exchangers, and in view of the shortcomings and limitations of existing research, this invention proposes a moving bed heat exchanger and its directional control of turbulent flow to enhance heat transfer.

[0007] The technical solution of the present invention is realized as follows:

[0008] A moving bed heat exchanger includes a driving chain, a transmission mechanism, a driving motor with a control system, a disturbing member that performs horizontal sinusoidal motion, and temperature sensors. The disturbing members are arranged above and below the heat exchange tubes and are driven by an external motor through the driving chain.

[0009] The driving chain is a rotatable metal link. There are mounting holes for the disturbing members on the chain, and it is installed above and below the heat exchange tubes at a height range of 0.8D - D from the center of the heat exchange tubes (D is the outer diameter of the heat exchange tubes). The chain and the heat exchange tubes are arranged perpendicular to each other to ensure that the installation of the flow disturbing device and the heat exchange tubes do not interfere with each other. Preferably, along the direction of the heat exchange tubes, more than one driving chain can be installed at each installation position according to requirements to form a driving chain group, thereby increasing the driving force on the disturbing members. The driving chain is directly associated with the transmission mechanism, and the transmission mechanism is directly controlled by the motor.

[0010] The transmission mechanism is installed on the side wall of the heat exchanger box and converts the rotational torque of the external motor into a horizontal drive for the chain. The disturbing member is a rigid long rod that can disturb solid bulk materials in the horizontal direction. Preferably, the cross-sectional shape of the disturbing member can be freely selected, including but not limited to circular, diamond-shaped or lens-shaped, to adjust the resistance in different dense bulk materials and the disturbing ability for the bulk materials. Preferably, the disturbing member and the driving chain are connected by a flexible joint. This design is aimed at operation problems such as wear and is beneficial for the installation, maintenance and replacement of sub-components. Preferably, different numbers of disturbing members can be freely installed on the driving chain according to requirements to expand the disturbing range.

[0011] Several (at least 2) driving chains and disturbing members are arranged perpendicular to each other and completed the connection, locally forming a stable "field" - shaped grid structure, and the plane where it is located is parallel to the heat exchange tubes. Based on this structure, the external driving motor can controllably drive the driving chain and the disturbing member to perform horizontal reciprocating motion through the transmission mechanism, thereby realizing the disturbance of the bulk materials.

[0012] A method for enhancing heat transfer through directional control and turbulence in a moving bed heat exchanger involves using a feedback-controlled perturbation mechanism to transform the bulk material flow from an ordered "plunger flow" to a "turbulent flow" with strong heat and mass exchange near the heat exchange tubes. The method is characterized by the following: when high-temperature bulk material flows downwards into the heat exchanger and exchanges heat with the horizontal heat exchange tubes, a drive motor with a control system drives a drive chain to move horizontally via a rotation mechanism. This causes the perturbation rod to move horizontally in a sinusoidal motion, disturbing the solid bulk material and altering its flow structure within the heat exchanger, thus disrupting the particle accumulation and cavitation regions above and below the heat exchange tubes. The specific adjustment of the perturbation frequency and amplitude is controlled by the motor's control system, based on the motor's drive power consumption and temperature feedback from a temperature sensor. Between different tube banks, the horizontal reciprocating motion of the grid rectifies the bulk material flow, enhancing heat and mass diffusion. Simultaneously, the perturbation above the heat exchange tubes disrupts the solid bulk material accumulation structure above the tubes, promoting material renewal within the heat exchanger and reducing the thermal resistance of the accumulated bulk material. The disturbance below the heat exchange tubes forces the material to change its trajectory and diffuse towards the wall. This ultimately suppresses cavitation and reduces air thermal resistance. In addition, while inducing velocity fluctuations, the disturbance can disrupt the stable force chains in the bulk flow, preventing bridging and blockage between tubes.

[0013] Compared with the prior art, the present invention has the following advantages:

[0014] 1. The moving bed heat exchanger of the present invention has the characteristics of simple process and compact structure. Compared with the traditional moving bed, it can increase the flow disturbance to improve the heat exchange efficiency and can effectively reduce the blockage phenomenon in the moving bed, thus enhancing the heat exchange effect.

[0015] 2. This invention discloses a directional control and turbulence-enhanced heat transfer method based on a moving bed heat exchanger. By optimizing and controlling the flow structure of the bulk material flow, it enhances heat and mass diffusion, thereby reducing particle-side thermal resistance and promoting uniform flow and heat transfer of particles within the heat exchanger housing. It can meet the needs of different tube arrangement configurations and has advantages such as low cost, simple system, flexible configuration, and strong practicality.

[0016] To better understand and implement this invention, the following detailed description is provided in conjunction with the accompanying drawings. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of a directional control turbulence-enhanced heat transfer method based on a moving bed heat exchanger.

[0018] Figure 2 This is a schematic diagram of the flow structure of bulk material near a horizontal heat exchanger tube (without disturbance).

[0019] Figure 3 This is a schematic diagram of an overall implementation example (in sequence) of the present invention in a moving bed heat exchanger.

[0020] Figure 4 yes Figure 3 Schematic diagram of the AA section grid structure.

[0021] Figure 5 yes Figure 3 A schematic diagram of the transmission mechanism between the motor and the drive chain.

[0022] Figure 6 This is a schematic diagram of an embodiment of the disturbance component of the present invention.

[0023] Figure 7 This is a schematic diagram illustrating the calibration of the heat transfer enhancement effect of the perturbation method of the present invention.

[0024] Figure 8 This is a schematic diagram of the motor load characteristic curve required by the disturbance method of the present invention.

[0025] Figure 9 This is a schematic diagram illustrating the operational optimization of the perturbation method of the present invention.

[0026] Wherein, 1 is the horizontal heat exchange tube; 2 is the drive chain; 3 is the transmission mechanism: 31 is the fixed rotating shaft, 32 is the rotating wheel, 33 is the connecting rod, and 34 is the sliding groove; 4 is the drive motor; 5 is the disturbance chamber: 51 is the round rod, 52 is the rhomboid cross-section rod, and 53 is the lens cross-section rod; 6 is the temperature sensor. For the relevant parameter: α is the angle of the accumulation zone; It is the particle friction angle; H represents the height of the chain installation position; D is the outer diameter of the heat exchange tube; D A Γ is the displacement amplitude; f is the motion frequency; Γ is the turbulence intensity. u is the bulk material flow rate; 1 / h is the particle-side thermal resistance of the moving bed heat exchanger; R c It is the contact thermal resistance in the bulk material flow; k' is the increase in equivalent thermal conductivity caused by the turbulence device; W F It is the power consumption required for the motor to overcome the resistance of the moving parts. Detailed Implementation

[0027] This invention discloses a directional turbulence control method for enhancing indirect heat exchange of solid bulk materials. Based on feedback-controlled perturbation mechanism motion, the bulk material flow is transformed from an ordered "plunger flow" to a "turbulent flow" with strong heat and mass exchange. During operation, the moving bed indirect heat exchanger housing is pre-filled with high-temperature bulk material. At the start of heat exchange, the bulk material is discharged through a bottom discharge device while simultaneously being continuously fed into the heat exchanger inlet, flowing from top to bottom through horizontal heat exchange tubes. A cold working fluid (usually air or water) is introduced into the heat exchange tubes to exchange heat with the high-temperature bulk material. At this time, a motor located on the side of the heat exchange housing starts, controlling a drive chain to drive a perturbation rod in a sinusoidal motion in the horizontal direction.

[0028] The driving chain 2 is installed above and below the heat exchange tube 1 at the same time, and the installation position is within the height range of 0.8D - D at the center of the heat exchange tube 1 (D is the outer diameter of the heat exchange tube). Specifically, at each installation position, 3 driving chains are arranged equidistantly along the direction of the heat exchange tube to form a driving chain group, so as to improve the driving force on the disturbing member 5.

[0029] When the heat exchange tubes are arranged in a staggered pattern and the center-to-center distance between the upper and lower tube rows is about 2D, the corresponding accumulation areas and cavity areas between adjacent tube rows can be disrupted by the same set of driving chains. The driving chain 2 and the heat exchange tube 1 are arranged perpendicular to each other to ensure that the installation of the flow disturbing device and the heat exchange tube does not interfere with each other; the driving is completed through the transmission mechanism 3 on the side wall of the heat exchanger and is associated with the motor 1 on the side of the heat exchanger. Specifically, the driving motor 1 directly drives the fixed rotating shaft 31 installed on the side wall of the heat exchanger to rotate, thereby driving the rotating wheel 32 near the inner wall of the heat exchanger to rotate. Then, the rotating wheel 32 drives the driving chain 2 to perform a horizontal sine motion inside the heat exchanger through the eccentrically connected connecting rod 33 and the chute 34. The disturbing member 5 and the driving chain 2 are connected by a flexible joint, and several disturbing members 5 are arranged equidistantly in the direction perpendicular to the chain. Locally, a stable "field" - shaped grid structure is formed, and the plane where it is located is parallel to the heat exchange tube 1. Under the action of the driving motor 4, the driving chain 2 drives the disturbing member 5 to perform a horizontal sine motion to rectify the bulk material flow.

[0030] Along the direction of the bulk material flow, the number of disturbing members 5 installed on the driving chain 2 gradually increases, so that the disturbing range of the bulk material expands with the development of the temperature boundary layer. Specifically, the disturbing member 5 in the present invention can be selected from different types according to requirements, including but not limited to a round - section rod 51, a diamond - section rod 52, and a lens - section rod 53. The specific cross - sectional shape can be determined according to actual requirements and optimization goals. Among them, the round - section rod has a small volume and low cost; the diamond - section rod 52 has a strong disturbing ability for materials; and the lens - section rod 53 can be regarded as a partial combination of the round - section rod 51 and the diamond - section rod 52, which is beneficial to reducing resistance. Specifically, the external motor 4 controls the flow disturbing member 5 to perform a horizontal sine motion. Among them, the disturbing amplitude D A is between 0.25D - 0.5D; and the disturbing frequency f is a low frequency, controlled below 15 Hz. Regarding the active control of the disturbing intensity Γ, it needs to be completed based on the feedback of the driving motor power consumption and the bulk material temperature, comprehensively considering the disturbing resistance and the heat transfer enhancement effect.

[0031] In order to calibrate the enhancement effect of the flow disturbing member under different disturbing intensities Γ, within a certain flow velocity range, a characteristic fitting line of 1 / h and can be made. The intercept of the line represents the contact thermal resistance R c between the bulk material flow and the wall surface, which is related to the comprehensive influence of the flow disturbing member on the accumulation area and the cavity area. The change in the slope of the line can be used to analyze the enhancement of the flow disturbing device on the internal heat and mass diffusion (k’) of the bulk material flow. As the disturbing intensity Γ increases, Rc As k decreases and k' increases, the slope of the fitted line decreases.

[0032] Load feedback W of drive motor 6 F , is a function of turbulence intensity Γ and flow velocity u. It can be determined based on the calibrated W. F =f(Γ,u) characteristic curve, through load feedback W F To determine the density / sparseness of the powder flow inside the heat exchanger and the flow velocity u, the adjustment of the disturbance frequency should consider enhancing particle-side thermal resistance and saving motor power consumption. When the bulk material flow rate is high, the particle-side thermal resistance depends more on the contact thermal resistance R. c The dependence on k' decreases. At this point, the turbulence intensity Γ only needs to disrupt the accumulation and cavitation regions. Conversely, the particle-side thermal resistance depends on the permeation thermal resistance, requiring sufficient turbulence intensity Γ to disturb the interior of the bulk flow. Therefore, the turbulence intensity Γ should decrease with increasing bulk flow velocity u, saving power consumption W. F At the same time, it significantly enhances heat exchange, achieving a balance between the two.

[0033] On the other hand, the disturbance range should not exceed the temperature boundary layer. As the heat transfer Q of the bulk material changes, the temperature distribution (T) of the bulk material changes, and the disturbance amplitude D... A Adjustments are needed. Temperature sensor 6, mounted on disturbance rod 5, records the temperature (T) distribution and temperature gradient during operation. The change in temperature boundary layer thickness is used to predict the temperature boundary layer thickness, and D is adjusted based on feedback within the range of 0.25D-0.5D. A Preferably, the threshold ε is set to 5K / m, when... It is assumed that the current motion region of the disturbed component exceeds the temperature boundary layer, and D is reduced. A Conversely, it can increase D. A .

[0034] Compared with existing technologies, the directional control turbulence method for enhancing indirect heat transfer of solid bulk materials proposed in this invention actively alters the flow structure of the bulk material flow through optimized control, thereby enhancing heat and mass diffusion, reducing particle-side thermal resistance, and promoting uniform flow and heat transfer of particles within the heat exchanger housing. It can meet the needs of different tube bank arrangements and has advantages such as low cost, system simplicity, flexible configuration, and strong practicality.

[0035] The above content is merely a technical concept of the present invention and should not be construed as limiting the scope of protection of the present invention. Any modifications or alterations made based on the technical concept proposed in this invention are also within the scope of protection of the claims of this invention.

Claims

1. A method for directional regulation and turbulence enhancement of heat exchange in a moving bed heat exchanger, characterized in that: It includes a driving chain, a transmission mechanism, a driving motor with a control system, a disturbing member that performs horizontal sinusoidal motion, and a temperature sensor; the driving chain consists of mutually rotating metal links, which are installed above and below the horizontal heat exchange tubes, and there are mounting holes for the disturbing members on the chain; the transmission mechanism is installed on the side wall of the heat exchanger box body, converting the rotational torque of the external motor into a horizontal drive for the chain; the driving motor with a control system is installed outside the side wall of the heat exchanger box body, inputting a directionally regulated driving force to the transmission mechanism; the disturbing member is a rigid long rod, connected to and driven by several driving chains, and can disturb solid bulk materials in the horizontal direction; the temperature sensor collects and monitors the temperature data of the bulk materials near the disturbing member. Disturbance frequency adjustment, drive motor power consumption W F Turbulence intensity and flow rate u The function; based on pre-calibrated Characteristic curves, obtained through load feedback from the drive motor W F Determine the density / sparseness of the powder flow inside the heat exchanger and the flow velocity. u Adjust the disturbance frequency f； Turbulence intensity The amount should be reduced as the bulk material flow rate increases, and a balance should be struck with the need for enhanced control of thermal resistance on the particle side. The disturbance amplitude adjustment, the disturbance rod disturbance range should not exceed the temperature boundary layer; therefore, with the bulk material heat exchange capacity Q changes, bulk material temperature T distribution changes, the disturbance amplitude D A needs to be adjusted; by installing temperature sensors on the disturbance rod, recording the temperature T distribution and temperature gradient changes during operation, the temperature boundary layer thickness is predicted; a threshold is set < , it is considered that the current disturbance member movement area exceeds the temperature boundary layer, and the D A is reduced D A ; When the high-temperature bulk materials flow into the heat exchanger from top to bottom and exchange heat with the horizontal heat exchange tubes, the driving motor with a control system drives the driving chain to perform horizontal motion through the rotating mechanism, and the disturbing rod is driven to perform horizontal sinusoidal motion to disturb the solid bulk materials; it changes the flow structure of the solid bulk materials in the heat exchanger, and destroys the particle accumulation area and cavity area above and below the heat exchange tubes; specifically, the adjustment of the disturbing frequency and the disturbing amplitude are completed by the control system of the motor based on the driving power consumption of the motor and the temperature feedback of the temperature sensor.

2. The method of claim 1, wherein: The driving chains are installed above and below the heat exchange pipes, and the installation positions are within the height range of 0.8 D - D of the center of the heat exchange pipe, D is the outer diameter of the heat exchange pipe; the chains are arranged perpendicular to the heat exchange pipes, ensuring that the installation of the disturbance devices and the heat exchange pipes does not interfere with each other; along the direction of the heat exchange pipes, more than 2 driving chains are installed at each installation position according to the needs, forming a driving chain group, thereby improving the driving force of the disturbance rods.

3. The method of claim 1, wherein: The cross-sectional shape of the disturbing member can be freely selected, including but not limited to circular, diamond-shaped or lens-shaped, to adjust the motion resistance in different dense bulk materials and the disturbing ability to the bulk materials.

4. The method of claim 1, wherein: Install different numbers of disturbing members on the driving chain freely according to requirements to expand the disturbing range; several at least 2 driving chains and the disturbing members are arranged perpendicular to each other and completed the connection, locally forming a stable "field" character grid structure, and the plane where it is located is parallel to the heat exchange tubes; based on this structure, the external driving motor can controllably drive the driving chain and the disturbing member to perform horizontal reciprocating motion through the transmission mechanism, so as to realize the disturbance of the bulk materials.

5. The method as claimed in claim 1, wherein: Motor control system, through the motor control heat exchanger in the disturbance piece to do horizontal periodic sinusoidal displacement, disturbance intensity is expressed as: wherein, D A is the displacement amplitude, the range is 0.25 D -0.5 D interval; and f is the motion frequency, low frequency is used, controlled below 15 Hz.

6. The method as claimed in claim 1, wherein: The particle side thermal resistance is enhanced and controlled, and is divided into contact thermal resistance and penetration thermal resistance. The contact thermal resistance is related to the stagnant structure near the heat exchange tube in the bulk flow, including the gap between the particle and the wall surface, the thermal resistance of the accumulation zone and the thermal resistance of the cavity zone. The penetration thermal resistance is related to the heat exchange inside the bulk flow. When the bulk flow speed is relatively fast, the particle side thermal resistance is more dependent on the contact thermal resistance, and the disturbance strength Only the destruction of the accumulation zone and the cavity zone needs to be met; otherwise, the particle side thermal resistance depends on the penetration thermal resistance, and sufficient disturbance strength is required Disturbance is applied to the inside of the bulk flow.

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