A heat exchange device for papermaking and a method for recovering waste heat in white cardboard production

Abstract

The application discloses a heat exchange device for papermaking and a white cardboard production waste heat recovery method. A hollow cavity type movable partition plate is used to divide the inner cavity of the shell into two heat exchange cavities of tail gas and steam. A current collecting and distributing assembly, a regulating valve and multiple groups of built-in rubber wheel driving mechanisms are integrated in the cavity of the partition plate. The volume of the cavity is dynamically adjusted by the rolling of the rubber wheel to drive the translation of the partition plate. The bypass pipeline realizes follow-up sealing by means of a sliding sealing slider. The device collects medium temperature and pressure signals and partition plate position signals by sensors, and automatically controls the position of the partition plate and the opening of the valve by PLC, so as to adapt to working conditions such as full load of double heat sources, single heat source shutdown and load fluctuation. The structure has high integration degree and can be modularly prefabricated, so that the difficulty of on-site modification is greatly reduced. The heat exchange space can be fully utilized and the utilization rate of the equipment is improved. In addition, the idle heat exchange pipe can be bypassed, so that the heat loss caused by reverse heat exchange is effectively avoided, and the waste heat recovery efficiency of the boiler in the white cardboard production process is significantly improved.

Description

Technical Field

[0001] This invention relates to the technical field of waste heat recovery and heat exchange equipment for papermaking, specifically to a shell-and-tube heat exchanger with adaptive load regulation function that is used for combined waste heat recovery of boiler exhaust gas and steam in papermaking plants. Background Technology

[0002] During the operation of boilers in the papermaking industry, two types of waste heat sources are generated: high-temperature exhaust gas and saturated steam. Industrially, two heat exchangers or dual heat source heat exchangers are often used to recover the above heat and use it to heat the water used in the papermaking process, so as to achieve energy cascade utilization and energy saving and cost reduction.

[0003] Currently, there are published patents for dual-heat-source shell-and-tube heat exchangers applicable to this scenario. Among them, CN208779985U describes a dual-heat-source heat exchanger. This device has a fixed longitudinal partition inside the shell, dividing the shell into two independent chambers for introducing two different heat sources. The tube bundle adopts a conventional rigid straight tube structure, and the overall structure is a fixed partition structure. It can achieve heat exchange of three media within a single device, reducing the equipment's footprint. However, the shell partitioning and tube bundle layout of this device are both fixed. Under conditions of fluctuating boiler load in paper mills and intermittent shutdown of exhaust gas or steam, the idle chambers and corresponding tube bundles cannot participate in heat exchange, resulting in low equipment utilization. When the tube-side medium continuously flows through the idle tube bundle without a heat source, reverse heat exchange will occur, causing heat loss and increasing energy consumption.

[0004] Another design, CN107062670A, is a dual-channel variable capacity heat exchanger. This design changes the effective heat exchange area by switching the medium flow path in the tubes using valve groups, thus adapting to load changes. However, it lacks a partitioning structure inside the shell, and the shell cavity space cannot be allocated according to the actual supply status of the two heat sources. This still fails to solve the core problem of a large area of ​​the shell cavity space being idle after one side of the heat source stops operating.

[0005] In addition, traditional dual-source heat exchangers often employ externally distributed piping, valves, and drive components, resulting in low equipment integration. Retrofitting older heat exchangers involves complex on-site processes such as cutting, pipe connection, and drive mechanism installation, leading to a large workload. In summary, existing dual-source heat exchangers suffer from drawbacks such as inability to allocate cavity space as needed, low heat exchange utilization, significant ineffective heat loss, poor equipment integration, cumbersome on-site modifications, and insufficient operational stability under harsh conditions. These shortcomings make them unsuitable for meeting the actual requirements of waste heat recovery from boiler exhaust gas and intermittent, variable-load steam in paper mills. Summary of the Invention

[0006] To address the shortcomings of existing technologies, this invention provides a heat exchanger for papermaking. The baffle is designed as a hollow cavity integrated structure, housing all piping, valves, and the traveling mechanism, thus improving equipment integration and reducing on-site modification work. An internal rubber-wheel traveling mechanism replaces the traditional cylinder / hydraulic cylinder, adapting to harsh workshop conditions. The bypass piping, combined with a sliding sealing slider, achieves dynamic sealing, eliminating ineffective heat loss while dynamically adjusting the cavity volume, thereby improving overall heat exchange efficiency and operational stability.

[0007] To achieve the above objectives, the inventors provide a heat exchanger for papermaking, including a horizontal shell, a tube-side heat exchange assembly, a hollow cavity movable partition, a sensing and detection assembly, and an intelligent control assembly.

[0008] The hollow cavity movable partition is vertically slidably assembled inside the horizontal shell, dividing the shell cavity into an independent exhaust gas heat exchange chamber and a steam heat exchange chamber; the tube-side heat exchange assembly is a telescopic heat exchange tube or a U-shaped flexible heat exchange tube, with both ends of the heat exchange tube fixed to the tube sheet.

[0009] The hollow cavity movable partition is equipped with a flow-combining and diversion assembly and a rubber wheel driving assembly. The flow-combining and diversion assembly includes a main pipe, a manifold, a diverter, a bypass pipe, and a regulating valve. The heat exchange tubes in the exhaust gas heat exchange chamber are connected to the main pipe through the manifold, and the main pipe is connected to the heat exchange tubes in the steam heat exchange chamber through the diverter. One end of the bypass pipe is connected to the main pipe, and the other end passes through the horizontal shell and is connected to the heating medium output pipe. The rubber wheel driving assembly includes multiple sets of rubber wheels and a matching transmission drive mechanism. The multiple sets of rubber wheels are evenly arranged around the circumference of the hollow cavity movable partition and are all housed inside the partition cavity. The outer edge of the rubber wheels rolls in contact with the inner wall of the horizontal shell. The drive mechanism drives the rubber wheels to roll synchronously, thereby driving the hollow cavity movable partition to move left and right.

[0010] The sensing and detection component includes a temperature sensor and a pressure sensor respectively installed in the exhaust gas heat exchange chamber and the steam heat exchange chamber, as well as a displacement sensor installed on the hollow cavity movable partition; the intelligent control component is electrically connected to the sensing and detection component, the rubber wheel walking drive component, and the regulating valve respectively, and automatically controls the sliding position of the partition and the opening degree of the regulating valve based on the collected temperature, pressure, and position signals.

[0011] Furthermore: a sliding sealing slider is provided at the penetration position of the bypass pipeline and the horizontal shell. The slider is fitted into the opening of the shell and slides and seals with the shell. The bypass pipeline is fixed on the slider and can slide synchronously with the hollow cavity movable partition.

[0012] Furthermore, the sliding seal slider is made of wear-resistant sealing material, and multiple layers of sealing filler or sealing rings are set between the slider and the opening of the housing. During the left and right sliding of the slider, a dynamic sealing state is always maintained to prevent the leakage of the medium inside the housing.

[0013] Furthermore: the hollow cavity movable partition is a sealed integrated modular structure, and the outer edge of the partition is equipped with an annular seal. The annular seal is tightly fitted with the inner wall of the horizontal shell to achieve medium isolation between the exhaust gas heat exchange chamber and the steam heat exchange chamber.

[0014] Furthermore, the maximum extension and contraction of the telescopic heat exchange tube and the deformation range of the U-shaped flexible heat exchange tube are not less than the maximum translational stroke of the hollow cavity movable partition.

[0015] Furthermore, the drive motor and transmission mechanism of the rubber wheel walking drive assembly are both arranged inside the hollow cavity movable partition, and the moving parts are completely in the sealed cavity, isolating them from external dust and moisture.

[0016] Furthermore: the horizontal shell is provided with exhaust gas inlet and outlet, steam inlet and outlet, top exhaust valve and bottom drain port; mechanical limiting structures are provided on both sides of the hollow cavity movable partition to limit the maximum sliding stroke of the partition and avoid squeezing and damaging the tube heat exchange components.

[0017] To address the aforementioned technical problems, this application also provides another technical solution:

[0018] A method for recovering waste heat in white cardboard production, employing a papermaking heat exchanger as described in any of the above-mentioned methods to perform waste heat recovery operations, includes the following steps:

[0019] S1 feeding operation: High-temperature exhaust gas and saturated steam from the boiler are fed into the corresponding heat exchange chambers of the heat exchanger, while low-temperature process water for white cardboard production is fed into the tube heat exchange components.

[0020] S2 Real-time Monitoring: The sensor continuously collects temperature, pressure, and partition position data from the two heat sources and uploads them to the intelligent control component;

[0021] S3 Intelligent Control: The intelligent control component determines the operating conditions based on monitoring data, automatically controls the rubber wheel to drive the partition to slide to adjust the volume of the heat exchange chambers on both sides, and simultaneously links the regulating valve to switch / adjust the on / off state and opening degree of the bypass pipeline; when both heat sources are in normal supply, the process water flows through all heat exchange tubes; when a single heat source is shut down or under low load, the partition shifts to the idle side, and the process water bypasses the idle heat exchange tubes through the bypass pipeline; when the heat source load fluctuates, the partition position and valve opening are simultaneously finely adjusted to achieve load matching;

[0022] S4 Water Reuse: The process water after heat exchange and heating is delivered to each water-using station in the white cardboard production process.

[0023] S5 Continuous Operation and Maintenance: Cyclicly executes monitoring, control and heat exchange output processes to achieve automated continuous waste heat recovery under all operating conditions.

[0024] Furthermore, the S3 intelligent control includes the following steps:

[0025] Operating Condition Determination and Adaptive Adjustment: The intelligent control component determines the operating condition of the heat source based on the collected temperature and pressure values ​​and outputs control commands.

[0026] When both exhaust gas and steam are in normal supply, the control rubber wheel drive assembly moves the hollow cavity movable partition to the center position of the shell, the regulating valve closes the bypass pipeline, and the low temperature process water flows through the tube heat exchange components corresponding to the exhaust gas heat exchange chamber and steam heat exchange chamber in sequence to continuously absorb the waste heat from the two heat sources.

[0027] When the exhaust gas is supplied normally, the steam is shut down, or the load is lower than the set threshold, the hollow cavity movable baffle is controlled to slide to the side of the steam heat exchange chamber to expand the effective volume of the exhaust gas heat exchange chamber. At the same time, the regulating valve is fully opened, and the low temperature process water is directly transported to the white cardboard production process through the manifold and diversion components and bypass pipelines, without entering the tube heat exchange components corresponding to the steam heat exchange chamber.

[0028] When steam is supplied normally, exhaust gas is shut down, or the load is lower than the set threshold, the hollow cavity movable baffle is controlled to slide to the side of the exhaust gas heat exchange chamber to expand the effective volume of the steam heat exchange chamber. At the same time, the flow path is switched so that the low temperature process water bypasses the tube heat exchange components corresponding to the exhaust gas heat exchange chamber through the bypass pipeline.

[0029] When exhaust gas and steam are running simultaneously and the load of a single heat source fluctuates slightly, the position of the hollow cavity movable baffle is finely adjusted according to the heat source load ratio, and the opening of the regulating valve is adjusted accordingly, so that part of the process water flows through the two-way tube heat exchange components and the remaining process water is output from the bypass pipeline, matching the real-time heat exchange load.

[0030] Unlike existing technologies, the above-mentioned heat exchanger for papermaking features a hollow cavity-type movable baffle vertically slidingly assembled inside a horizontal shell, dividing the shell cavity into independent exhaust gas heat exchange chambers and steam heat exchange chambers. The movable baffle can dynamically adjust the volume of the heat exchange chambers on both sides, reducing idle heat exchange space. Bypass pipelines, in conjunction with regulating valves, bypass idle tube bundles, avoiding heat loss caused by reverse heat exchange, significantly improving heat exchange efficiency and energy recovery rate. Furthermore, the baffle is designed as a hollow cavity structure, with all pipelines, valves, and traveling mechanisms built-in, forming an integrated modular component. It can be prefabricated at the factory and directly assembled on-site, greatly reducing the amount of work required for on-site cutting, external pipeline installation, and external drive mechanism modification. Moreover, it uses multiple built-in rubber wheels for rolling drive, replacing external cylinders and hydraulic cylinders. With moving parts inside the cavity, it is isolated from dust and moisture in the papermaking workshop, making it wear-resistant, waterproof, dustproof, and with a longer service life.

[0031] The above description of the invention is merely an overview of the technical solution of this application. In order to enable those skilled in the art to better understand the technical solution of this application and to implement it based on the description and drawings, and to make the above-mentioned objectives and other objectives, features and advantages of this application easier to understand, the following description is provided in conjunction with the specific embodiments and drawings of this application. Attached Figure Description

[0032] The accompanying drawings are only used to illustrate the principles, implementation methods, applications, features, and effects of specific embodiments of the present invention and other related contents, and should not be considered as limitations on this application.

[0033] In the accompanying drawings of the instruction manual:

[0034] Figure 1 This is a schematic diagram of the structure of the heat exchanger for papermaking described in a specific embodiment;

[0035] Figure 2 This is a schematic diagram of the internal structure of the hollow cavity movable partition described in the specific embodiment;

[0036] Figure 3 This is a schematic diagram of the external structure of the hollow cavity movable partition described in the specific embodiment;

[0037] Figure 4 The process flow diagram is shown for the waste heat recovery method in the production of white cardboard as described in the specific implementation method;

[0038] The reference numerals used in the above figures are explained as follows:

[0039] 1. Horizontal shell; 10. Inner wall; 11. Exhaust gas heat exchange chamber; 12. Steam heat exchange chamber;

[0040] 110. First-pass heat exchanger assembly; 111. Exhaust gas inlet; 112. Exhaust gas outlet;

[0041] 120. Second-pass heat exchanger assembly; 121. Steam inlet; 122. Steam outlet;

[0042] 2. Hollow cavity type movable partition; 21. Main pipe; 22. Manifold; 221. Connection hole; 23. Diverter; 24. Regulating valve; 25. Sealing slider; 26. Bypass pipeline; 27. Rubber wheel travel mechanism; 271. Rubber wheel; 28. Sealing ring; Detailed Implementation

[0043] To illustrate the possible application scenarios, technical principles, implementable specific solutions, and achievable objectives and effects of this application in detail, the following description, in conjunction with the listed specific embodiments and accompanying drawings, provides a detailed explanation. The embodiments described herein are merely illustrative of the technical solutions of this application and are therefore intended to limit the scope of protection of this application.

[0044] In this document, the term "embodiment" means that a specific feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The term "embodiment" appearing in various places throughout the specification does not necessarily refer to the same embodiment, nor does it specifically limit its independence or connection with other embodiments. In principle, in this application, as long as there are no technical contradictions or conflicts, the technical features mentioned in each embodiment can be combined in any way to form corresponding implementable technical solutions.

[0045] Unless otherwise defined, the technical terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the use of related terms herein is merely for the purpose of describing particular embodiments and is not intended to limit this application.

[0046] In the description of this application, the term "and / or" is used to describe the logical relationship between objects, indicating that three relationships can exist. For example, A and / or B means: A exists, B exists, and A and B exist simultaneously. Additionally, the character " / " in this document generally indicates that the preceding and following objects have an "or" logical relationship.

[0047] In this application, terms such as “first” and “second” are used only to distinguish one entity or operation from another, and do not necessarily require or imply any actual quantity, hierarchy or order relationship between these entities or operations.

[0048] Without further limitations, the use of terms such as “comprising,” “including,” “having,” or other similar open-ended expressions in this application is intended to cover non-exclusive inclusion, which does not exclude the presence of additional elements in a process, method, or product that includes the stated elements, such that a process, method, or product that includes a list of elements may include not only those defined elements but also other elements not expressly listed, or elements inherent to such a process, method, or product.

[0049] In this application, expressions such as "greater than", "less than", and "exceeding" are understood to exclude the stated number; expressions such as "above", "below", and "within" are understood to include the stated number. Furthermore, in the description of the embodiments of this application, "multiple" means two or more (including two), and similar expressions related to "multiple" are also understood in this way, such as "multiple groups" and "multiple times", unless otherwise explicitly specified.

[0050] In the description of the embodiments of this application, the space-related expressions used, such as "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "vertical," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential," indicate the orientation or positional relationship based on the orientation or positional relationship shown in the specific embodiments or drawings. They are only for the purpose of describing the specific embodiments of this application or for the reader's understanding, and do not indicate or imply that the device or component referred to must have a specific position, a specific orientation, or be constructed or operated in a specific orientation. Therefore, they should not be construed as limitations on the embodiments of this application.

[0051] Unless otherwise expressly specified or limited, the terms "installation," "connection," "linking," "fixing," and "setting," as used in the description of the embodiments of this application, should be interpreted broadly. For example, "connection" can be a fixed connection, a detachable connection, or an integral arrangement; it can be a direct connection or an indirect connection through an intermediate medium; it can be a relationship of two components combined together, an interaction relationship between two components, or a connection within two structures. Those skilled in the art to which this application pertains can understand the specific meaning of the above terms in the embodiments of this application according to the specific circumstances.

[0052] Please see Figures 1 to 3 This embodiment provides a heat exchanger for papermaking. The heat exchanger for papermaking includes a horizontal shell 1, a tube-side heat exchange assembly, a hollow cavity movable baffle, a flow distribution assembly, a flow path switching assembly, a travel drive assembly, a sensing and detection assembly, and an intelligent control assembly.

[0053] The horizontal housing 1 has a sliding mechanism inside (i.e., Figure 1A hollow, movable baffle 2 (pointed to by arrow L, with arrow H indicating the height) divides the inner cavity of the shell into an exhaust gas heat exchange chamber 11 and a steam heat exchange chamber 12. The tube-side heat exchange components employ telescopic heat exchange tubes or U-shaped flexible heat exchange tubes to accommodate the displacement and deformation of the baffle. The tube-side heat exchange components include a first tube-side heat exchange component 110 disposed in the exhaust gas heat exchange chamber 11 and a second tube-side heat exchange component 120 disposed in the steam heat exchange chamber 12. The shell corresponding to the exhaust gas heat exchange chamber 11 is provided with an exhaust gas inlet 111 and an exhaust gas outlet 112, and the shell corresponding to the steam heat exchange chamber 12 is provided with a steam inlet 121 and a steam outlet 122.

[0054] like Figure 2 and Figure 3 As shown, the hollow cavity movable partition 2 integrates a main pipe 21, a manifold 22, a distributor 23, a regulating valve 24, and multiple sets of rubber wheel walking mechanisms 27 inside the cavity, resulting in a highly integrated structure. The rubber wheel walking mechanism 27 includes multiple sets of rubber wheels 271 evenly arranged circumferentially, and a drive motor for driving the rubber wheels. The hollow cavity movable partition 2 achieves translation by the rolling cooperation between the multiple sets of rubber wheels 271 inside the cavity and the inner wall 10 of the shell, thereby eliminating the need for external drive components. The manifold 22 is located at one end of the hollow cavity movable partition 2 near the exhaust gas heat exchange chamber 11. Multiple connection holes 221 are evenly arranged on the surface of the manifold 22, and the connection holes 221 are connected to the main pipe through a horn-shaped guide shroud. The distributor 23 is arranged parallel to the manifold at one end near the steam heat exchange chamber 12, and its surface is also provided with connection holes for connecting to the heat exchange tubes. Multiple sealing rings 28 are provided on the outer periphery of both ends of the hollow cavity movable partition 2 to seal the gap between the hollow cavity movable partition 2 and the shell.

[0055] The heat exchange tubes of the first-pass heat exchange assembly 110 in the exhaust gas heat exchange chamber 11 are connected to the main pipe inside the chamber via a manifold 22. The main pipe 21 is connected to the heat exchange tubes in the steam heat exchange chamber 12 via a distributor 23. A regulating valve 24 is integrated on the main pipe 21, and a bypass pipe 26 is connected to the side of the main pipe 21. The bypass pipe 26 passes through the side wall of the shell, and a sliding sealing slider 25 is installed at the exit position. The sealing slider 25 is in sliding sealing cooperation with the inner wall of the opening of the horizontal shell 1. The bypass pipe 26 is fixed on the slider and can slide left and right synchronously with the partition. The slider always maintains a sealed state. The end of the bypass pipe is connected to the heating medium output pipe. The control harness of the regulating valve 24 and the rubber wheel travel mechanism 27 can be routed along the bypass pipe 26 and then extended to the outside of the shell through the sealing slider 25.

[0056] The horizontal shell 1 is a pressure vessel cylinder with tube sheets fixed at both ends. The side walls are respectively provided with exhaust gas inlet and steam inlet and outlet. An exhaust valve is provided at the top and a drain outlet is provided at the bottom. The inner wall of the shell is smooth and serves as a guide surface for the rolling of rubber wheels.

[0057] The main pipe 21 is connected to the bypass pipe 26 through the regulating valve 24. A sliding sealing slider is provided at the position where the bypass pipe exits the shell. The slider and the shell slide and seal together, so that the bypass pipe can move synchronously with the partition, while ensuring the airtightness of the shell.

[0058] The equipment is equipped with temperature, pressure, and displacement sensors and a PLC controller. Based on the temperature and pressure parameters of the exhaust gas and steam, it automatically controls the position of the baffles and the opening of the regulating valves, dynamically matching the heat source load to achieve adaptive operation under all working conditions. This equipment can be modularly produced as a whole, requiring only simple cutting and assembly on-site to complete the modification, significantly reducing construction difficulty.

[0059] Tube-side heat exchange assembly: Composed of several telescopic heat exchange tubes or U-shaped flexible heat exchange tubes. The two ends of the heat exchange tubes are fixed to the tube sheets at both ends of the shell. The papermaking process water to be heated flows inside the tubes; the telescopic / bending stroke of the heat exchange tubes matches the maximum sliding distance of the hollow partition.

[0060] The hollow cavity movable baffle 2 is an integral, thick, sealed hollow cavity structure, vertically arranged within the shell cavity, dividing the shell into a left exhaust gas heat exchange cavity and a right steam heat exchange cavity; a sealing structure is set on the outer edge of the baffle to ensure that the media in the two cavities do not flow between each other. The cavity integrates a main pipe, manifold, distributor, regulating valve, multiple sets of rubber wheels and rubber wheel drive mechanism, and all fluid components and moving parts are concealed internally with no external protruding structures.

[0061] The rubber-wheel walking mechanism 27 is a walking drive assembly, including multiple sets of rubber wheels 271 evenly arranged circumferentially within the hollow partition cavity. The outer edges of the rubber wheels 271 roll in contact with the inner wall 10 of the shell. An independent drive motor and transmission mechanism are installed inside the hollow cavity movable partition 2, synchronously driving all the rubber wheels to rotate, and relying on the rolling of the rubber wheels to drive the entire hollow partition to move left and right. An annular bracket is provided in the middle of the hollow cavity movable partition 2, fitting circumferentially against the inner wall. The rubber wheels 271, independent drive motors, and transmission mechanisms are evenly spaced on the annular bracket (for example, one set of rubber wheels 271 and independent drive motors and transmission mechanisms is provided every 90 degrees). Adjustable clearance holes are correspondingly provided on the outer wall of the hollow cavity movable partition 2 to allow the rubber wheels to partially protrude from the hollow cavity movable partition 2 and contact the inner wall of the shell.

[0062] The transmission mechanism is preferably a worm gear transmission mechanism, so that the self-locking function of the worm gear can prevent the hollow cavity movable partition 2 from shifting due to external force.

[0063] Temperature and pressure sensors are installed in the exhaust gas heat exchange chamber and steam heat exchange chamber, respectively, and a displacement sensor is installed on the hollow partition. All sensors, regulating valves, and rubber wheel drive motors are connected to a PLC controller. The controller determines the heat source load based on the detected medium temperature and pressure, automatically controls the rotation of the rubber wheels to adjust the partition position, and simultaneously links the regulating valves to change the medium flow path.

[0064] Exhaust gas side sensor group: Temperature and pressure sensors are installed at the exhaust gas inlet 111 and exhaust gas outlet 112 on the left side of the housing, respectively, to detect exhaust gas temperature and pressure and determine exhaust gas heat load and on / off status; dustproof sleeves and online purging devices are added to the outside of the sensors to prevent dust from clogging the measuring points. Steam side sensor group: High-temperature resistant pressure and temperature sensors are installed at the steam inlet 121 and steam outlet 122 on the right side of the housing, respectively, to detect steam pressure and saturation temperature and determine steam supply status and load;

[0065] Pipe-side medium sensor group: Temperature sensors are installed at the inlet and outlet of the pipe side to monitor the inlet and outlet water temperatures of the production water, serving as feedback signals for the heat exchange effect.

[0066] Intelligent control components: The core is a PLC controller, equipped with a human-machine interface touch screen and an audible and visual alarm; all sensors, cylinder solenoid directional valves, electric proportional regulating valves, and displacement sensors are electrically connected to the PLC controller via signal lines; the touch screen is used for parameter setting, operation data display, and automatic / manual mode switching; the audible and visual alarm is used for fault alarms such as over-temperature, over-pressure, and baffle jamming.

[0067] This heat exchanger for papermaking has multiple operating modes:

[0068] Dual heat source full-load operation: exhaust gas and steam parameters are within the rated range, PLC controls the rubber wheel to drive the baffle in the center, and the heat exchange chambers on both sides are evenly divided in volume; the regulating valve closes the bypass pipeline, and the medium flows through all the heat exchange tubes on both sides in sequence to fully absorb the heat from the two heat sources.

[0069] When only the exhaust gas is normal and the steam is shut down: When the steam side parameters are below the threshold, the baffle slides towards the steam side to expand the volume of the exhaust gas heat exchange chamber; the regulating valve 24 is fully open, and the medium is directly output through the main pipe 21 and the bypass pipe 26, without entering the idle tube bundle on the steam side, thus avoiding heat loss.

[0070] Steam is normal only, exhaust gas is shut down: the baffle slides towards the exhaust gas side to expand the volume of the steam heat exchange chamber; the medium bypasses the exhaust gas side tube bundle through the bypass and concentrates on using the steam heat source for heat exchange.

[0071] Heat source load fluctuation: The controller fine-tunes the position of the baffle and the opening of the regulating valve according to the load ratio. Part of the medium flows through the heat exchange tube and part of it goes through the bypass to achieve precise load matching and maintain optimal heat exchange efficiency.

[0072] In summary, this heat exchanger for papermaking has the following technical advantages:

[0073] 1. High integration and easy modification: The baffle is designed as a hollow cavity structure, with all pipelines, valves and walking mechanisms built in, forming an integrated modular component. It can be directly assembled on site after being prefabricated in the original factory, which greatly reduces the amount of modification work such as on-site cutting of heat exchangers, external pipelines, and external drive mechanisms.

[0074] 2. Optimized drive structure and high reliability: It adopts a built-in multi-set rubber wheel rolling drive to replace the external cylinder and oil cylinder. The moving parts are located inside the cavity, which isolates them from the dust and water vapor corrosion in the papermaking workshop. It is wear-resistant, waterproof, dustproof and has a longer service life.

[0075] 3. Reliable sliding seal: A sliding seal slider is installed between the bypass pipeline and the shell, which not only meets the displacement requirements of the pipeline sliding left and right with the partition, but also ensures long-term sealing at the shell interface and prevents media leakage.

[0076] 4. Dynamic capacity adjustment + flow path switching for dual energy saving: The movable baffle dynamically adjusts the volume of the heat exchange chambers on both sides, eliminating idle heat exchange space; the bypass pipeline, in conjunction with the regulating valve, bypasses idle tube bundles, avoiding heat loss caused by reverse heat exchange, and significantly improving heat exchange efficiency and energy recovery rate.

[0077] 5. Wide adaptability: The flexible / telescopic heat exchange tubes are matched with the partition displacement, which can be compatible with both boiler dust-containing exhaust gas and high-temperature and high-pressure steam. It can directly retrofit old dual-heat source heat exchangers and has strong versatility.

[0078] like Figure 4 As shown, in one embodiment, a method for recovering waste heat in white cardboard production is provided. This method uses the papermaking heat exchanger described in the above embodiments to perform waste heat recovery operations, and includes the following steps:

[0079] S1 Medium Introduction: High-temperature exhaust gas from the boiler of the white cardboard production system is introduced into the exhaust gas heat exchange chamber of the heat exchanger, saturated steam from the boiler is introduced into the steam heat exchange chamber of the heat exchanger, and low-temperature process water required for white cardboard production is introduced into the tube heat exchange components of the heat exchanger.

[0080] S2 Real-time Parameter Acquisition: The temperature and pressure data of the medium inside the exhaust gas heat exchange chamber and steam heat exchange chamber are continuously collected through the sensing and detection components. At the same time, the real-time position signal of the hollow cavity movable partition is collected, and all data is transmitted to the PLC controller.

[0081] S3 Operating Condition Determination and Adaptive Adjustment: The PLC controller determines the operating condition of the heat source based on the collected temperature and pressure values ​​and outputs control commands.

[0082] When both exhaust gas and steam are in normal supply, the control rubber wheel drive assembly moves the hollow cavity movable partition to the center position of the shell, the regulating valve closes the bypass pipeline, and the low temperature process water flows through the tube heat exchange components corresponding to the exhaust gas heat exchange chamber and steam heat exchange chamber in sequence to continuously absorb the waste heat from the two heat sources.

[0083] When the exhaust gas is supplied normally, the steam is shut down, or the load is lower than the set threshold, the hollow cavity movable baffle is controlled to slide to the side of the steam heat exchange chamber to expand the effective volume of the exhaust gas heat exchange chamber. At the same time, the regulating valve is fully opened, and the low temperature process water is directly transported to the white cardboard production process through the manifold and diversion components and bypass pipelines, without entering the tube heat exchange components corresponding to the steam heat exchange chamber.

[0084] When steam is supplied normally, exhaust gas is shut down, or the load is lower than the set threshold, the hollow cavity movable baffle is controlled to slide to the side of the exhaust gas heat exchange chamber to expand the effective volume of the steam heat exchange chamber. At the same time, the flow path is switched so that the low temperature process water bypasses the tube heat exchange components corresponding to the exhaust gas heat exchange chamber through the bypass pipeline.

[0085] When exhaust gas and steam are running simultaneously and the load of a single heat source fluctuates slightly, the position of the hollow cavity movable baffle is finely adjusted according to the heat source load ratio, and the opening of the regulating valve is adjusted accordingly, so that part of the process water flows through the two-way tube heat exchange components and the remaining process water is output from the bypass pipeline, matching the real-time heat exchange load.

[0086] S4 circulating heat exchange output: After heat exchange and heating, the process water is continuously transported to water-using stations such as pulping, wire section and drying section in white cardboard production to realize waste heat recovery and reuse.

[0087] S5 Cycle Monitoring: Repeat steps S2~S4 throughout the entire process, dynamically adjust the position of the baffle and the medium flow path in real time, and maintain the waste heat recovery efficiency under all operating conditions.

[0088] In this embodiment, the boiler of the white cardboard production line is running continuously, and the exhaust gas and steam often experience intermittent interruptions and load fluctuations. This method relies on the built-in rubber wheel drive structure of the heat exchanger to drive the hollow partition to move flexibly, combined with the sliding sealing slider to ensure the bypass pipeline is sealed accordingly. No manual intervention is required throughout the process, realizing automated continuous operation.

[0089] In this embodiment, on the one hand, the shell cavity space is dynamically allocated by the partition, so that the effective heat source can make full use of the entire shell heat exchange space; on the other hand, the flow path is split by the bypass pipeline to avoid the process water flowing through the idle heat exchange pipe and generating reverse heat dissipation, thus reducing energy loss in two ways and improving the recycling rate of boiler waste heat in white cardboard production.

[0090] Finally, it should be noted that although the above embodiments have been described in the text and drawings of this application, this should not limit the scope of patent protection of this application. Any technical solutions that are based on the essential concept of this application and utilize the content described in the text and drawings of this application, resulting in equivalent structural or procedural substitutions or modifications, as well as the direct or indirect application of the technical solutions of the above embodiments to other related technical fields, are all included within the scope of patent protection of this application.

Claims

1. A heat exchanger for papermaking, comprising a horizontal shell and a tube-side heat exchange assembly, characterized in that: It also includes hollow cavity movable partitions, sensing and detection components, and intelligent control components; The hollow cavity movable partition is vertically slidably assembled inside the horizontal shell, dividing the shell cavity into an independent exhaust gas heat exchange chamber and a steam heat exchange chamber; the tube-side heat exchange assembly is a telescopic heat exchange tube or a U-shaped flexible heat exchange tube, with both ends of the heat exchange tube fixed to the tube sheet. The hollow cavity movable partition is equipped with a flow-combining and diversion assembly and a rubber wheel driving assembly. The flow-combining and diversion assembly includes a main pipe, a manifold, a diverter, a bypass pipe, and a regulating valve. The heat exchange tubes in the exhaust gas heat exchange chamber are connected to the main pipe through the manifold, and the main pipe is connected to the heat exchange tubes in the steam heat exchange chamber through the diverter. One end of the bypass pipe is connected to the main pipe, and the other end passes through the horizontal shell and is connected to the heating medium output pipe. The rubber wheel driving assembly includes multiple sets of rubber wheels and a matching transmission drive mechanism. The multiple sets of rubber wheels are evenly arranged around the circumference of the hollow cavity movable partition and are all housed inside the partition cavity. The outer edge of the rubber wheels rolls in contact with the inner wall of the horizontal shell. The drive mechanism drives the rubber wheels to roll synchronously, thereby driving the hollow cavity movable partition to move left and right. The sensing and detection component includes a temperature sensor and a pressure sensor respectively installed in the exhaust gas heat exchange chamber and the steam heat exchange chamber, as well as a displacement sensor installed on the hollow cavity movable partition; the intelligent control component is electrically connected to the sensing and detection component, the rubber wheel walking drive component, and the regulating valve respectively, and automatically controls the sliding position of the partition and the opening degree of the regulating valve based on the collected temperature, pressure, and position signals.

2. The heat exchanger for papermaking according to claim 1, characterized in that: The bypass pipeline is provided with a sliding sealing slider at the penetration position between the horizontal shell and the bypass pipeline. The slider is fitted into the opening of the shell and slides and seals with the shell. The bypass pipeline is fixed on the slider and can slide synchronously with the hollow cavity movable partition.

3. The heat exchanger for papermaking according to claim 2, characterized in that: The sliding seal slider is made of wear-resistant sealing material. Multiple layers of sealing filler or sealing rings are set between the slider and the opening of the housing. The slider maintains a dynamic sealing state during the left and right sliding process to prevent the leakage of the medium inside the housing.

4. The heat exchanger for papermaking according to claim 1, characterized in that: The hollow cavity movable partition is a sealed integrated modular structure. The outer edge of the partition is equipped with an annular seal, which is tightly fitted to the inner wall of the horizontal shell to achieve medium isolation between the exhaust gas heat exchange chamber and the steam heat exchange chamber.

5. A heat exchanger for papermaking according to claim 1, characterized in that: The maximum extension and contraction of the telescopic heat exchange tube and the deformation range of the U-shaped flexible heat exchange tube are both not less than the maximum translational stroke of the hollow cavity movable partition.

6. The heat exchanger for papermaking according to claim 1, characterized in that: The drive motor and transmission mechanism of the rubber-wheel walking drive assembly are arranged inside the hollow cavity movable partition, and the moving parts are completely in the sealed cavity, isolating them from external dust and moisture.

7. The heat exchanger for papermaking according to claim 1, characterized in that: The horizontal shell is equipped with exhaust gas inlet and outlet, steam inlet and outlet, top exhaust valve and bottom drain outlet; mechanical limiting structures are set on both sides of the hollow cavity movable partition to limit the maximum sliding stroke of the partition and avoid squeezing and damaging the tube heat exchange components.

8. A method for recovering waste heat in white cardboard production, characterized in that, Performing waste heat recovery operations using a heat exchanger for papermaking as described in any one of claims 1 to 7 includes the following steps: S1 feeding operation: High-temperature exhaust gas and saturated steam from the boiler are fed into the corresponding heat exchange chambers of the heat exchanger, while low-temperature process water for white cardboard production is fed into the tube heat exchange components. S2 Real-time Monitoring: The sensor continuously collects temperature, pressure, and partition position data from the two heat sources and uploads them to the intelligent control component; S3 Intelligent Control: The intelligent control component determines the operating conditions based on monitoring data, automatically controls the rubber wheel to drive the partition to slide to adjust the volume of the heat exchange chambers on both sides, and simultaneously links the regulating valve to switch / adjust the on / off state and opening degree of the bypass pipeline; when both heat sources are in normal supply, the process water flows through all heat exchange tubes; when a single heat source is shut down or under low load, the partition shifts to the idle side, and the process water bypasses the idle heat exchange tubes through the bypass pipeline; when the heat source load fluctuates, the partition position and valve opening are simultaneously finely adjusted to achieve load matching; S4 Water Reuse: The process water after heat exchange and heating is delivered to each water-using station in the white cardboard production process. S5 Continuous Operation and Maintenance: Cyclicly executes monitoring, control and heat exchange output processes to achieve automated continuous waste heat recovery under all operating conditions.

9. The method for recovering waste heat from white cardboard production according to claim 8, characterized in that, The S3 intelligent control includes the following steps: Operating Condition Determination and Adaptive Adjustment: The intelligent control component determines the operating condition of the heat source based on the collected temperature and pressure values ​​and outputs control commands. When both exhaust gas and steam are in normal supply, the control rubber wheel drive assembly moves the hollow cavity movable partition to the center position of the shell, the regulating valve closes the bypass pipeline, and the low temperature process water flows through the tube heat exchange components corresponding to the exhaust gas heat exchange chamber and steam heat exchange chamber in sequence to continuously absorb the waste heat from the two heat sources. When the exhaust gas is supplied normally, the steam is shut down, or the load is lower than the set threshold, the hollow cavity movable baffle is controlled to slide to the side of the steam heat exchange chamber to expand the effective volume of the exhaust gas heat exchange chamber. At the same time, the regulating valve is fully opened, and the low temperature process water is directly transported to the white cardboard production process through the manifold and diversion components and bypass pipelines, without entering the tube heat exchange components corresponding to the steam heat exchange chamber. When steam is supplied normally, exhaust gas is shut down, or the load is lower than the set threshold, the hollow cavity movable baffle is controlled to slide to the side of the exhaust gas heat exchange chamber to expand the effective volume of the steam heat exchange chamber. At the same time, the flow path is switched so that the low temperature process water bypasses the tube heat exchange components corresponding to the exhaust gas heat exchange chamber through the bypass pipeline. When exhaust gas and steam are running simultaneously and the load of a single heat source fluctuates slightly, the position of the hollow cavity movable baffle is finely adjusted according to the heat source load ratio, and the opening of the regulating valve is adjusted accordingly, so that part of the process water flows through the two-way tube heat exchange components and the remaining process water is output from the bypass pipeline, matching the real-time heat exchange load.

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