Heating circulation system and heating circulation method for lyocell fiber production

Abstract

This invention relates to the field of fiber production equipment technology, and discloses a heating circulation system and its heating circulation method for lyocell fiber production. The system includes: a melting machine, a zoned jacket, a hot water circulation loop, a material handling loop, a multi-dimensional state sensing system, and a central control system. The method includes: acquiring torque signals from the melting machine and temperature signals from the hot water circulation loop through the multi-dimensional state sensing system; the central control system generating control commands based on the signals and sending them to each electronically controlled proportional valve to independently control the hot water flow. This method calculates the temperature difference of the hot water in each zone to determine the heat transfer efficiency, achieving dynamic cascaded heating; simultaneously, it collaboratively corrects the total heating power based on the comparison between the rate of change of the torque signal and the standard process curve. This invention, through the combination of multi-dimensional information feedback and zoned control, achieves precise control of the rapid heating process, improving thermal energy utilization efficiency and product process stability.

Description

Technical Field

[0001] This invention relates to the field of fiber production equipment technology, and in particular to a heating circulation system and heating circulation method for lyocell fiber production. Background Technology

[0002] In the production process of lyocell fiber, the dissolving machine is one of the core pieces of equipment. Its function is to heat and dissolve cellulose raw materials in N-methylmorpholine-N-oxide (NMMO) solvent to prepare a uniform and stable spinning solution. This dissolving process has strict requirements for temperature control and must be carried out at a specific temperature to ensure that the material is heated evenly in order to avoid solvent decomposition and ensure the quality of the final product.

[0003] In existing technologies, a common heating method involves installing a jacket around the melting tank and circulating heat transfer media such as heat transfer oil within the jacket. While this method can ensure heating uniformity to some extent, the overall heating rate is slow and the heating cycle is long due to limitations in the specific heat capacity and heat exchange efficiency of the heat transfer media. As market demands for production efficiency continue to increase, this traditional heating method has gradually become a bottleneck for increasing production capacity and is unable to meet the needs of rapid, high-volume production.

[0004] To improve the heating rate, the industry has proposed using steam with higher enthalpy to heat the circulating water, and then introducing the hot water into the jacket. However, while this simple improvement shortens the heating time, it introduces new and more complex technical problems. Due to the extremely rapid heat input, without an effective coordinated control strategy, the entire heating process becomes difficult to manage, easily causing localized temperature spikes. This not only increases the risk of NMMO solvent decomposition but also disrupts the internal temperature equilibrium of the solution. More importantly, existing control systems typically use temperature as the sole feedback target for programmed control, ignoring the actual physicochemical changes of the material within the tank. This control method cannot perceive the actual dissolution rate of the material, leading to a disconnect between heating behavior and dissolution requirements, making it difficult to guarantee the process stability and quality uniformity of the final spinning solution across different production batches.

[0005] Therefore, this invention proposes a heating circulation system and heating circulation method for the production of lyocell fibers to overcome the shortcomings of the prior art. Summary of the Invention

[0006] The purpose of this invention is to provide a heating circulation system and heating circulation method for the production of lyocell fibers, which solves the problem that the rapid heating process is disconnected from the actual dissolution state of the material, making it difficult to balance production efficiency and process stability.

[0007] To address the aforementioned technical problems, the first aspect of this invention provides a heating circulation system for lyocell fiber production. This system includes:

[0008] A dissolving machine, wherein the outer wall of the dissolving machine is provided with a partitioned jacket, the partitioned jacket being divided into at least two heating zones that can be independently supplied with hot water.

[0009] A hot water circulation loop, used to supply hot water to the zoned jacket, includes a steam water heater, a hot water circulation pump, an expansion pressure tank, a hot water outflow loop connecting the hot water circulation pump and the zoned jacket, and a hot water inflow loop connecting the zoned jacket and the hot water circulation pump. An electrically controlled proportional valve is installed on the hot water outflow loop corresponding to each independent heating zone. The steam-side inlet of the steam water heater is connected to the main steam pipe, and the steam-side outlet is connected to the main condensate pipe via a steam trap. The hot water circulation loop is also connected to the main soft water pipe for replenishing the circulating water.

[0010] The material handling circuit includes a feed pump for supplying material to the dissolving machine and a discharge pump for discharging material from the dissolving machine. The inlet of the discharge pump is connected to a top-insertion discharge pipe that extends from the top of the dissolving machine. A bottom discharge port is provided at the bottom of the dissolving machine.

[0011] A multi-dimensional state sensing system, comprising a torque sensor mounted on the stirring drive of the dissolving machine, and a temperature sensor network for monitoring the temperature of the hot water circulation loop.

[0012] The central control system is electrically connected to the multi-dimensional state sensing system and each of the electronically controlled proportional valves.

[0013] In the technical solution provided by this invention, the central control system receives signals from the multi-dimensional state sensing system. These signals include torque information characterizing the material's dissolution state and temperature information characterizing the system's thermal energy state. Based on these two different dimensions of information, the central control system generates control commands and sends them to each of the electrically controlled proportional valves to independently adjust the flow rate of hot water into each independent heating zone. Through this structure, the system can actively manage the spatial distribution and temporal sequence of heat based on the real-time dissolution process of the material and the actual heat absorption of each zone, thereby effectively controlling the heating process while achieving rapid heating using steam-water heat exchange.

[0014] As a specific technical solution, the temperature sensor network includes a first temperature sensor disposed on the main hot water circulation loop, and second temperature sensors disposed on the hot water circulation loop in each independent heating zone. The central control system is configured to calculate the temperature difference of the hot water flowing through each independent heating zone based on the signals from the first temperature sensor and the signals from each of the second temperature sensors. This hot water temperature difference... It can be represented by the following formula: ;

[0015] In the formula, t represents time, and i represents the index of the independent heating region. The temperature value acquired by the first temperature sensor at time t. This is the temperature value acquired by the second temperature sensor in region i at time t. This temperature difference value... It characterizes the real-time thermal energy absorption efficiency of region i at time t.

[0016] Furthermore, the central control system is also configured to continuously monitor the temperature difference of the hot water in an independent heating zone when heating is being performed in that zone. .when When the change meets preset conditions, such as decreasing to a certain threshold, it indicates that the heat transfer efficiency of the area has decreased. The central control system then triggers the opening control of the electronically controlled proportional valve of the next adjacent independent heating area, thereby forming a dynamic cascade heating.

[0017] Furthermore, the central control system is also configured to continuously receive torque signals from the torque sensor during the heating process. And calculate its rate of change based on the torque signal. : ;

[0018] The central control system will change the rate of change The process is compared with a preset process curve, and based on the comparison results, the opening degree of all the electrically controlled proportional valves in the open state is coordinated and adjusted to correct the overall heating power. This method couples physical heating control with the chemical dissolution process.

[0019] As another specific technical solution, the system further includes a discharge cooling heat exchanger. The process-side inlet of the discharge cooling heat exchanger is connected to the outlet of the discharge pump. The cooling-side inlet of the discharge cooling heat exchanger is connected to the cooling water main pipe, and the cooling-side outlet is connected to the cooling water outlet pipe, for cooling the material after dissolution.

[0020] A second aspect of the present invention provides a heating cycle method for the production of lyocell fibers, the method being applied to any of the aforementioned systems, comprising the following steps:

[0021] S1. The torque signal inside the dissolving machine and the temperature signal of the hot water circulation loop are acquired in real time through the multi-dimensional state sensing system.

[0022] S2. The acquired torque signal and temperature signal are sent to the central control system;

[0023] S3. The central control system generates control commands based on the received torque signal and temperature signal;

[0024] S4. The central control system sends the control command to each of the electronically controlled proportional valves to independently control the flow rate of hot water flowing through each independent heating zone of the partitioned jacket.

[0025] As a specific implementation method, the steps of the central control system controlling the hot water flow rate include:

[0026] First, open the electronically controlled proportional valve of the first independent heating zone along the direction of material gravity;

[0027] Then, the inlet and outlet water temperature difference of the first independent heating zone is continuously calculated. When the temperature difference is lower than the preset threshold, the electronically controlled proportional valve of the next adjacent independent heating zone is opened.

[0028] As another specific implementation method, the step of the central control system controlling the hot water flow rate further includes:

[0029] During the heating process, the rate of change of the torque signal acquired by the torque sensor is continuously calculated;

[0030] Based on the comparison between the rate of change and the standard process curve, the opening degree of all the opened electronically controlled proportional valves is simultaneously increased or decreased to correct the total heating power.

[0031] Furthermore, the method also includes a heating termination determination step:

[0032] When the material temperature in the dissolving machine reaches the target temperature, or when the torque signal obtained by the torque sensor reaches the target torque value, the central control system controls all the electronically controlled proportional valves to enter the uniform temperature maintenance state or close them.

[0033] Furthermore, the method also includes a discharge step:

[0034] After the dissolution process is completed, the discharge pump is started to extract the material from the dissolution machine through the top insertion discharge pipe and transport it to the discharge cooling heat exchanger. At the same time, cooling water from the cooling water main pipe flows through the discharge cooling heat exchanger to cool the material.

[0035] In summary, the present invention has at least one of the following beneficial technical effects:

[0036] 1. This invention, by setting up a partitioned jacket and installing electrically controlled proportional valves on the water inlet pipes of each independent heating zone, combined with a multi-dimensional state sensing system capable of sensing temperature and torque, enables the central control system to independently and differentiate the heating process in different zones. This structure transforms the original single, monolithic heating surface of the dissolving machine into a multi-zone controllable object that can be precisely managed. Therefore, based on the steam-water rapid heating method, it achieves precise control over the spatial distribution and temporal sequence of heat, improving the controllability of the entire heating process.

[0037] 2. This invention monitors the temperature difference of hot water flowing through each independent heating zone to assess the heat absorption efficiency of each zone in real time. Based on this efficiency assessment, the central control system employs a dynamic cascaded heating strategy to prioritize and concentrate heat supply to the zone with the highest heat absorption efficiency. This approach avoids ineffective or inefficient heating of areas that are already close to saturation, ensuring that heat is always delivered to the material interface where it is most needed, thereby improving heat utilization efficiency and reducing unnecessary energy dissipation.

[0038] 3. This invention incorporates the torque signal, which characterizes the material dissolution process, into the heating control closed loop. The central control system not only controls based on temperature as a single physical quantity, but also determines the actual material dissolution rate based on the rate of change of the torque signal, and uses this as a basis to adjust the overall heating power. This design establishes a direct correlation between the physical heat transfer process and the macroscopic dissolution process of the material, making heating control no longer an isolated temperature-raising task, but a process that actively adapts to and serves the dissolution process itself, which is beneficial to ensuring the process stability of the final spinning solution.

[0039] 4. This invention achieves rapid heating to meet high-efficiency production requirements through the synergistic effect of zoned control, cascaded heating based on heat absorption efficiency, and power correction based on the dissolution process. Simultaneously, it ensures heating uniformity and safety through multi-dimensional precise control. This method effectively avoids problems such as localized overheating and solvent decomposition caused by excessively rapid heating. Furthermore, it achieves rapid temperature uniformity through zoned fine-tuning after heating, ultimately obtaining a uniform and stable spinning solution. This improves the adaptability of the production process to different production cycles and the uniformity of the final product quality. Attached Figure Description

[0040] Figure 1 This is a schematic diagram of the overall structure of the heating circulation system for lyocell fiber production according to the present invention;

[0041] Figure 2 This is a block diagram of the logic function of the central control system of the present invention;

[0042] Figure 3 This is a flowchart of the heating cycle method for producing lyocell fibers according to the present invention;

[0043] Figure 4 This is a schematic diagram of the heating circulation system for producing lyocell fibers according to the present invention.

[0044] The components include: 1. Dissolving machine; 2. Partitioned jacket; 3. Top insertion discharge pipe; 4. Bottom discharge port; 5. Feed pump; 6. Discharge pump; 7. Steam water heater; 8. Hot water circulation pump; 9. Discharge cooling heat exchanger; 10. Expansion pressure tank; 11. Electrically controlled proportional valve; 12. Drain valve; 13. Multi-dimensional status sensing system; 131. Torque sensor; 132. Temperature sensor network; and 14. Central control system. Detailed Implementation

[0045] The following is in conjunction with the appendix Figure 1 - Appendix Figure 4 The present invention will be further described in detail below.

[0046] Reference Figures 1 to 4 This embodiment provides a heating circulation system for the production of lyocell fibers. This system, through integrated physical devices and control logic, performs closed-loop control of heat distribution and the dissolution process while utilizing steam for rapid heating.

[0047] As attached Figure 1 As shown, the system includes: a dissolving machine 1, a partitioned jacket 2 installed on the outer wall of the dissolving machine 1, a top insertion type discharge pipe 3 inserted from the top of the dissolving machine 1, a bottom discharge port 4 installed at the bottom of the dissolving machine 1, a feed pump 5, a discharge pump 6, a steam water heater 7, a hot water circulation pump 8, a discharge cooling heat exchanger 9, an expansion pressure tank 10, multiple electrically controlled proportional valves 11 installed on the hot water pipeline, a steam trap 12, a multi-dimensional status sensing system 13, and a central control system 14.

[0048] The multidimensional state sensing system 13 includes a torque sensor 131 installed on the stirring drive of the dissolving machine 1 and a temperature sensor network 132 for monitoring the temperature of the hot water circulation loop.

[0049] See attached document Figure 3This embodiment also provides a heating cycle method for producing lyocell fibers applied to the aforementioned system. The method is executed by a central control system 14 and may include the following steps:

[0050] Step S1: Receive and process real-time signals from the multi-dimensional state perception system 13. The central control system 14 continuously acquires torque signals fed back by the torque sensor 131 and multiple temperature signals fed back by the temperature sensor network 132.

[0051] Step S2: Calculations are performed based on the acquired signals to obtain key parameters characterizing the system's operating status. In this step, the central control system 14 performs at least two core calculations. The first is to calculate the real-time heat absorption efficiency of each zone, which can be determined by the temperature difference of the hot water flowing through each independent heating zone. Characterization; the second core calculation is to obtain the rate of material dissolution, which is determined by the rate of change of the torque signal. Characterization;

[0052] Step S3: Based on the calculation results of step S2, generate and output control commands. The central control system 14 integrates a control logic module a, which calculates the temperature difference value in real time. and torque change rate Based on the preset process parameters, an independent control command is generated for each electronically controlled proportional valve 11.

[0053] Step S4: Execute control commands. The central control system 14 sends the generated control commands to each electronically controlled proportional valve 11 to precisely adjust the flow rate of hot water into each independent heating zone, thereby achieving active control over the total heating power, heat spatial distribution, and heating sequence.

[0054] See attached document Figure 1 , Figure 1 This is a schematic diagram of a heating circulation system for producing lyocell fibers according to an embodiment of the present invention.

[0055] The heating circulation system of this embodiment can be physically divided into a material handling subsystem, a heat energy supply and closed-loop circulation subsystem, a discharge cooling subsystem, and a sensing and control subsystem.

[0056] The material handling subsystem constitutes the core flow path of lyocell fiber materials from input, dissolution to output. The core equipment of the subsystem is the dissolving machine 1, which is equipped with a stirring device to mix and agitate the materials.

[0057] The outlet of the feed pump 5 is connected to the feed port at the top of the dissolving machine 1 via a pipe, and is used to transport raw materials such as cellulose and NMMO solvent into the dissolving machine 1.

[0058] The material is discharged from the top. A top-insertion discharge pipe 3 is inserted vertically from the top cover of the dissolving machine 1, with its lower opening extending to near the bottom of the dissolving machine 1. The inlet of the discharge pump 6 is connected to the upper end of the top-insertion discharge pipe 3.

[0059] At the very bottom of the vessel of the dissolving machine 1, there is a bottom discharge port 4. This bottom discharge port 4 is closed during normal production and is used for material discharge or equipment cleaning after the production batch is completed.

[0060] The heat supply and closed-loop circulation subsystem is the unit that provides and precisely controls the heat energy for the dissolving process. The outer wall of the dissolving machine 1 is provided with a partitioned jacket 2. In this embodiment, the partitioned jacket 2 is divided into three independent heating zones along the vertical direction, namely the lower zone, the middle zone, and the upper zone.

[0061] A closed hot water circulation loop provides a heat source for the zoned jacket 2. This loop consists of a steam water heater 7, a hot water circulation pump 8, an expansion pressure tank 10, and connecting pipelines. The hot water circulation pump 8 serves as the power source, and its outlet is connected to the water-side inlet of the steam water heater 7.

[0062] The steam-side inlet of the steam-water heater 7 is connected to the external steam main pipe for introducing high-pressure steam; its steam-side outlet is connected to the external condensate drain main pipe through the steam trap 12 for discharging condensate.

[0063] A main hot water circulation loop is led out from the water-side outlet of the steam water heater 7. Near the dissolving machine 1, this main loop branches into three parallel branches, each connected to the inlet of one of the three independent heating zones of the partitioned jacket 2. Each branch is equipped with an electrically controlled proportional valve 11.

[0064] The outlets of the three independent heating zones also lead to three independent branch circuits from the hot water circulation system. These three branch circuits eventually converge into a main hot water circulation circuit, which is connected back to the inlet of the hot water circulation pump 8, forming a complete closed loop.

[0065] The expansion pressure tank 10 is connected in parallel to the main hot water circulation loop via a pipe to stabilize the loop pressure and accommodate changes in water volume. Additionally, the hot water circulation loop is also connected to an external soft water main via a pipe to replenish the loop with softened water.

[0066] The discharge cooling subsystem is used to cool the dissolved high-temperature spinning solution. The outlet of the discharge pump 6 is connected to the process-side inlet of the discharge cooling heat exchanger 9. The process-side outlet of the discharge cooling heat exchanger 9 is then connected to the subsequent process.

[0067] The cooling side inlet of the discharge cooling heat exchanger 9 is connected to the external cooling water main pipe, and its cooling side outlet is connected to the external cooling water main pipe.

[0068] The sensing and control subsystem is the hardware foundation for realizing automated control. It includes a multi-dimensional state sensing system 13 and a central control system 14.

[0069] The multi-dimensional state perception system 13 is used to acquire the multi-dimensional operating status of the system. Among them, the torque sensor 131 is installed on the drive shaft of the stirring device inside the dissolving machine 1, and is used to measure the resistance torque experienced by the stirring paddle when it rotates in the material in real time.

[0070] The temperature sensor network 132 consists of a set of temperature sensors. A first temperature sensor is located on the main hot water circulation loop, before the three parallel branch loops branch off, to measure the total hot water temperature before it enters all zones. Three second temperature sensors are respectively located on the three branch loops from the hot water circulation loop, before they merge into the main loop, to measure the hot water temperature after it flows out of the lower, middle, and upper independent heating zones.

[0071] The central control system 14, such as a programmable logic controller (PLC), is the control core of the entire system. The input terminals of the central control system 14 are electrically connected to the torque sensor 131 and all temperature sensors in the temperature sensor network 132 to receive the signals they collect. The output terminals of the central control system 14 are electrically connected to three electronically controlled proportional valves 11, respectively, to send independent control commands to them.

[0072] See attached document Figure 1 , Figure 2 and Figure 3 Below is Figure 3 The specific steps of the heating cycle method for lyocell fiber production are described in detail. The main body executing this method is the central control system 14, and its specific workflow begins with initialization and input of process parameters.

[0073] Before initiating a heating task for a production batch, a set of preset process parameters needs to be input into the parameter storage module b inside the central control system 14 via a human-machine interface (not shown). These parameters provide a benchmark and target for subsequent automated control logic. In this embodiment, the key process parameters that need to be input include:

[0074] Target dissolution temperature This parameter defines the final process temperature that the material in the dissolving machine 1 needs to reach, and is one of the conditions for determining whether the heating process is complete.

[0075] Target torque value This parameter defines the resistance torque that the stirring device should experience when the material reaches an ideal dissolved state. This value is measured by torque sensor 131 and is another key condition for determining whether the macroscopic rheological properties of the material meet the requirements and whether the dissolution process is complete.

[0076] Heat transfer efficiency saturation threshold This parameter is a preset temperature difference value used to determine whether the heat transfer efficiency of a specific heating zone has significantly decreased during dynamic cascade heating. The central control system 14 calculates the hot water temperature difference for a given zone based on real-time collected temperature data. When it is below this threshold, i.e. If the heating in that area is close to saturation, then heating of the next area can be triggered.

[0077] Standard torque ratio curve This parameter is either a set of data or a function pre-stored in the central control system 14, defining the desired trajectory of the rate of change of the stirring torque over time under ideal process conditions. This curve serves as the benchmark for subsequent global correction of the total heating power.

[0078] These parameters, once input, are stored in the central control system 14, providing a basis for the system to execute subsequent sensing, calculation, and control steps.

[0079] See attached document Figures 1 to 4 The principle of dynamic cascaded heating control in this embodiment will be explained in detail below. This control principle is the core of achieving efficient and precise heating, and its execution body is the control logic module a inside the central control system 14.

[0080] After the process parameters are initialized, the central control system 14 starts the heating program. This program does not supply heat to all heating areas simultaneously, but adopts an event-triggered cascaded control strategy to ensure that heat energy is preferentially applied to the material areas that most need heating.

[0081] When the heating process starts, the central control system 14 first sends an opening command to the electronically controlled proportional valve 11 corresponding to the independent heating area at the bottom of the partitioned jacket 2, so that it opens to a preset opening degree, while the electronically controlled proportional valves 11 in other areas remain closed.

[0082] During the heating process in this lower region, the central control system 14 continuously acquires the inlet and outlet water temperatures of this region through a temperature sensor network 132. To quantify the heat transfer status of this region, a thermal efficiency calculation module c within the system calculates the hot water temperature difference in real time, which directly characterizes the region's heat absorption efficiency. This calculation is based on the following formula for calculating the real-time heat absorption efficiency of the zone: ;

[0083] In the formula: t is time; i is the index of the independent heating area (in this embodiment, the lower, middle and upper areas can be indexed as 1, 2 and 3 respectively); Let be the hot water temperature difference in the i-th independent heating zone at time t; The hot water temperature in the main hot water circulation loop at time t is measured by the first temperature sensor. The hot water temperature of the branch circuit from the i-th independent heating zone at time t is measured by the corresponding second temperature sensor.

[0084] In the initial stage of heating, due to the low temperature of the material and the large temperature difference between it and the hot water, heat transfer is significant, therefore the calculated... The value is relatively large. As the temperature of the material in this area increases, the temperature difference between it and the hot water decreases, and the heat absorption rate slows down. The value also gradually decreases.

[0085] The cascaded logic judgment module d within the central control system 14 will calculate in real time... Value and heat transfer efficiency saturation threshold Continuous comparisons are performed. The triggering condition for cascade heating is defined as: When this condition is met for the currently heated region i, it indicates that the heat transfer efficiency of that region has decreased to a low level, and the efficiency of continuing to heat it with high power is reduced. At this time, the central control system 14 performs a cascade operation, that is, sends an opening command to the electronically controlled proportional valve 11 corresponding to the next adjacent, upper independent heating region (region i+1).

[0086] This process repeats sequentially. Once the heating of region i+1 meets its trigger condition, the system will then begin heating region i+2. In this way, the system achieves a bottom-up, wave-like heating process. This process is not driven by a fixed time program, but by the actual physical heat transfer state of each region. This ensures that throughout the heating phase, heating energy is consistently concentrated on the material interface that most effectively absorbs heat, avoiding energy waste and overheating of regions already close to the target temperature.

[0087] See attached document Figure 1 , Figure 2 and Figure 4 While performing the aforementioned dynamic cascade heating based on temperature feedback, the central control system 14 also executes a global power correction logic based on the material dissolution process in parallel. This logic does not target a single heating zone, but rather coordinates the total heating power of the entire system, with the aim of matching the physical heating rate with the macroscopic dissolution rate of the material.

[0088] The correction logic takes the signal acquired by torque sensor 131 as input. During the dissolution process, cellulose gradually dissolves from solid particles into the NMMO solvent, and the viscosity of the entire mixture undergoes complex changes. This change is directly reflected in the resistance torque experienced by the stirring device. Therefore, the rate of change of torque directly characterizes the macroscopic process rate of the dissolution reaction.

[0089] A dissolution rate calculation module e within the central control system 14 calculates the dissolution rate based on the received torque signal. The rate of change is calculated in real time, based on the following formula for calculating the rate of dissolution: ;

[0090] In the formula: t is time; The torque value acquired by torque sensor 131 at time t; The torque change rate over time t represents the macroscopic dissolution rate of the material in a physical sense.

[0091] Subsequently, the power correction module f within the system will use the real-time calculated dissolution rate. Compared with the standard torque rate curve The module compares the current heating rate to determine whether it is too fast or too slow. Based on this comparison, it calculates a global heating power adjustment factor. Its calculation can be based on the following formula: ;

[0092] In the formula: The heating power adjustment factor for time t; It is a preset, dimensionless proportional gain coefficient, the value of which determines the strength of the corrected response; This represents the expected rate of change of torque at time t on the standard torque rate curve. This represents the current real-time calculated rate of change in torque.

[0093] When the actual dissolution rate is lower than the standard rate, i.e. If the difference is positive, the calculated adjustment factor Conversely, when the actual dissolution rate is higher than the standard rate, the difference is negative, and the calculated adjustment factor... .

[0094] Calculate the adjustment factor Subsequently, the central control system 14 applies this factor to all currently open electronically controlled proportional valves 11. Specifically, the system multiplies the current opening degree of each of these valves by this adjustment factor. This allows for a coordinated increase or decrease in the total heating power.

[0095] See attached document Figure 1 , Figure 2 and Figure 3 After the main heating phase continues, the system needs to determine the end of the main heating phase based on the actual state of the material, and then enter the temperature equalization control phase. This process is executed in coordination by the central control system 14 to ensure that the material can obtain a uniform temperature distribution after reaching the target state.

[0096] A heating termination judgment module g within the central control system 14 continuously and in parallel monitors two different dimensions of process parameters: one is the real-time temperature of the material obtained through a temperature sensor (not shown) located inside the dissolving machine 1. Secondly, the real-time torque value is obtained through the torque sensor 131. .

[0097] The termination of the main heating stage is not determined by a single parameter, but rather by a multi-dimensional heating termination condition. This condition is defined as: ;

[0098] In the formula: The real-time temperature of the material at time t; The preset target dissolution temperature; This represents the real-time torque value at time t. V represents the preset target torque value; V is the logical OR operator.

[0099] When any of the above conditions are met, the heating termination judgment module g determines that the main heating stage has ended. At this time, the central control system 14 issues a command to switch the system from the main heating mode to the uniform temperature maintenance mode.

[0100] In the uniform temperature maintenance mode, the control objective shifts from rapidly increasing the temperature to eliminating any temperature gradients that may exist within the dissolving machine 1, in order to ensure the overall uniformity of the final spinning solution. At this time, the system fully utilizes its partitioned jacket 2 and independent electronically controlled proportional valve 11.

[0101] The central control system 14 ceases executing the aforementioned cascade heating and global power correction logic. Instead, it performs fine-tuning control of the electronically controlled proportional valves 11 in all independent heating zones. The system continuously monitors the outlet water temperature of all zones. The system adjusts the opening of the corresponding valves based on the differences between these temperature values. For example, for areas with high outlet water temperature, the system will reduce the opening of the corresponding electro-hydraulic proportional valve 11 to reduce the hot water flow in that area; conversely, for areas with low outlet water temperature, the system will appropriately increase the valve opening.

[0102] By implementing independent negative feedback regulation for each zone, the system can actively transfer heat from higher-temperature areas to lower-temperature areas until the outlet water temperature of all zones is reduced. The temperature tends to be uniform and stabilizes near a certain set value, indicating that the wall temperature of the entire dissolving machine 1 has reached uniformity, thus ensuring the temperature uniformity of the internal materials. Alternatively, under certain process requirements, the central control system 14 can also directly control all electronically controlled proportional valves 11 to be completely closed after the main heating stage is completed, relying on the thermal conductivity of the materials themselves for passive temperature uniformity.

[0103] See attached document Figure 1 and Figure 3 After the temperature equalization and holding phase is completed and the central control system 14 confirms that the material status fully meets the process requirements, the system will enter the discharge and reset procedure.

[0104] The central control system 14 first sends a stop command to the hot water circulation system, closes the steam inlet valves of the hot water circulation pump 8 and the steam heater 7, and stops heating the dissolving machine 1.

[0105] Subsequently, the central control system 14 starts the discharge pump 6 in the material handling subsystem. The discharge pump 6 starts working and draws the high-temperature, high-viscosity spinning solution that has been dissolved in the dissolving machine 1 from the top through the top insertion discharge pipe 3.

[0106] Simultaneously, the central control system 14 activates the discharge cooling subsystem. An opening command is sent to the valve connected to the cooling side of the discharge cooling heat exchanger 9, causing cooling water from the cooling water main to flow into the cooling side channel of the discharge cooling heat exchanger 9 and be discharged from the cooling water main.

[0107] The high-temperature spinning solution discharged from the discharge pump 6 is conveyed to the process-side channel of the discharge cooling heat exchanger 9. Here, the spinning solution exchanges heat with cooling water under physically isolated conditions, and its temperature is rapidly reduced to the temperature required for subsequent processes. The cooled material flows out from the process-side outlet of the discharge cooling heat exchanger 9 and is conveyed to the next production unit.

[0108] This discharge process continues until the material in the dissolving machine 1 is basically emptied.

[0109] After the material is discharged, the central control system 14 stops the operation of the discharge pump 6 and the cooling water valve. At this time, the equipment can be thoroughly emptied and cleaned through the bottom discharge port 4 on the dissolving machine 1 as needed.

[0110] After all processes are completed, all components of the system return to their initial standby state, the central control system 14 is reset, and it is ready to receive instructions for the next production batch. The entire production cycle ends here.

[0111] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A heating circulation system for lyocell fiber production, characterized in that, The system includes: A dissolving machine (1) has a partitioned jacket (2) on its outer wall, which is divided into at least two independent heating zones. The hot water circulation loop includes a steam water heater (7), a hot water circulation pump (8), an expansion pressure tank (10), and a hot water outflow loop and a hot water inflow loop connected to each independent heating zone of the partitioned jacket (2). An electrically controlled proportional valve (11) is installed on the hot water outflow loop at the position corresponding to each independent heating zone. The steam inlet of the steam water heater (7) is connected to the main steam pipe, and the steam outlet of the steam water heater (7) is connected to the main condensate pipe via a steam trap (12). The hot water circulation loop is also connected to the main soft water pipe. The material handling circuit includes a feed pump (5) for conveying material to the dissolving machine (1) and a discharge pump (6) for discharging material from the dissolving machine (1); the inlet of the discharge pump (6) is connected to a top-insertion discharge pipe (3) inserted from the top of the dissolving machine (1); and the bottom of the dissolving machine (1) is provided with a bottom discharge port (4). A multi-dimensional state sensing system (13) includes a torque sensor (131) installed on the stirring drive device of the dissolving machine (1) and a temperature sensor network (132) for monitoring the temperature of the hot water circulation loop. The central control system (14) is electrically connected to the multi-dimensional state perception system (13) and each of the electronically controlled proportional valves (11), and is used to receive signals from the multi-dimensional state perception system (13) and control the opening degree of each of the electronically controlled proportional valves (11).

2. The heating circulation system for lyocell fiber production according to claim 1, characterized in that, The temperature sensor network (132) includes a first temperature sensor located on the main pipeline before the hot water circulation loop enters the electronically controlled proportional valve (11), and second temperature sensors located on the hot water circulation loop in each independent heating zone. The central control system (14) includes: calculating the temperature difference of hot water flowing through each independent heating zone based on the temperature signals of the first temperature sensor and each of the second temperature sensors.

3. The heating circulation system for lyocell fiber production according to claim 2, characterized in that, The central control system (14) further includes: after heating is completed in an independent heating area, the heat transfer efficiency of the area is determined according to the hot water temperature difference, and based on the change in heat transfer efficiency, the opening control of the electronically controlled proportional valve (11) of the next adjacent independent heating area is triggered to form dynamic cascade heating.

4. The heating circulation system for lyocell fiber production according to claim 3, characterized in that, The central control system (14) further includes: during the dynamic cascade heating process, continuously receiving torque signals from the torque sensor (131), and coordinating the opening degree of all the electrically controlled proportional valves (11) in the open state according to the rate of change of the torque signal, so as to correct the overall heating power.

5. The heating circulation system for lyocell fiber production according to claim 1, characterized in that, The system also includes: Discharge cooling heat exchanger (9); the process side inlet of the discharge cooling heat exchanger (9) is connected to the outlet of the discharge pump (6); the cooling side inlet of the discharge cooling heat exchanger (9) is connected to the cooling water main pipe, and the cooling side outlet of the discharge cooling heat exchanger (9) is connected to the cooling water main pipe.

6. A heating cycle method for producing lyocell fibers, applied to the system described in any one of claims 1-5, characterized in that, The method includes the following steps: S1. The torque signal and the temperature signal of the hot water circulation loop inside the dissolving machine (1) are obtained in real time through the multi-dimensional state sensing system (13); S2. The acquired torque signal and temperature signal are sent to the central control system (14). S3. The central control system (14) generates control commands based on the received torque and temperature signals; S4. The central control system (14) sends control commands to each electronically controlled proportional valve (11) to independently control the flow rate of hot water flowing through each independent heating zone of the partitioned jacket (2).

7. The heating cycle method for producing lyocell fiber according to claim 6, characterized in that, In step S4, the step of the central control system (14) sending control commands to each of the electronically controlled proportional valves (11) includes: First, open the electronically controlled proportional valve (11) of the first independent heating zone along the direction of material gravity. The temperature difference between the inlet and outlet water of the first independent heating zone is continuously calculated. When the temperature difference is lower than a preset threshold, the electronically controlled proportional valve (11) of the next adjacent independent heating zone is opened.

8. The heating cycle method for producing lyocell fiber according to claim 6, characterized in that, In step S4, the step of the central control system (14) sending control commands to each of the electronically controlled proportional valves (11) further includes: During the heating process, the rate of change of the torque signal acquired by the torque sensor (131) is continuously calculated; Based on the comparison between the rate of change of the torque signal and the standard process curve, the opening degree of all the opened electronically controlled proportional valves (11) is increased or decreased synchronously to correct the total heating power.

9. The heating cycle method for producing lyocell fiber according to claim 8, characterized in that, The method further includes: When the material temperature in the dissolving machine (1) reaches the target temperature, or when the torque signal obtained by the torque sensor (131) reaches the target torque value, the central control system (14) controls all the electronically controlled proportional valves (11) to enter the uniform temperature maintenance state or close.

10. The heating cycle method for producing lyocell fiber according to claim 6, characterized in that, The method further includes: After the dissolution process is completed, the discharge pump (6) is started, and the material in the dissolution machine (1) is extracted through the top insertion discharge pipe (3) and transported to the discharge cooling heat exchanger (9). At the same time, the cooling water from the cooling water main pipe flows through the discharge cooling heat exchanger (9) to cool the material.

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