Cascade split-ranging control method for waste heat recycling system of setting machine

Abstract

The invention discloses a cascade split-ranging control method for a waste heat recycling system of a setting machine. According to the method, the waste heat of the setting machine is collected and utilized, and the heat energy utilization efficiency is optimized. The method comprises the following specific steps: high-temperature waste gas generated by a printing and dyeing setting machine enters a rotating wheel type heat exchanger through an exhaust fan and an additionally arranged pipeline, is converted into low-temperature waste gas and is discharged; normal-temperature air flows into the rotating wheel type heat exchanger through a pipeline by the fresh air machine and is changed into high-temperature air after heat exchange, and then the high-temperature air is conveyed to all branch pipelines through the air supply main pipeline and supplied to all drying ovens of the setting machine. A cascade split-ranging control method is adopted, a temperature control ring achieves temperature feedback through a tail gas temperature transmitter, and a flow control ring conducts flow feedback through a flow transmitter. And finally, the controller performs split-range control on each air supply valve according to the feedback data, and the air supply amount is automatically adjusted, so that the self-adaptive adjustment control of the system is realized. The control method can effectively reduce energy consumption and improve the overall efficiency of equipment, and has remarkable economic and environment-friendly benefits.

Description

Technical Field

[0001] The invention belongs to the field of waste heat recovery, and specifically provides a cascade step-by-step control method for a waste heat recovery and utilization system of a setting machine. Background Art

[0002] my country is a major textile printing and dyeing country. In recent years, the industry has developed rapidly and promoted economic growth. With the enhancement of environmental awareness and the implementation of national policies to control air pollution, the focus of pollution control in the printing and dyeing industry has gradually shifted to "air pollution control". As a key equipment for textile printing and dyeing finishing, the energy consumption of the setting machine accounts for more than 60% of the entire dyeing and finishing process, and the utilization rate is extremely low. A large amount of heat energy is discharged through exhaust, causing environmental pollution. These exhaust gases not only contain a lot of heat, but also contain harmful substances such as grease, dust and benzene. Therefore, it is imperative to recover and purify the exhaust gas.

[0003] Waste gas waste heat recovery technology can meet the energy conservation and emission reduction needs of the shaping process of textile printing and dyeing enterprises. Energy saving can be achieved by recovering the waste heat gas discharged from the shaping machine and transferring its heat energy to the shaping machine oven. This "gas-gas" heat exchange method usually uses a heat pipe heat exchanger or a rotary heat exchanger. The high-temperature waste flue gas releases heat on the heat absorption side of the heat exchanger, and the heat is quickly transferred to the heat release side. After being absorbed and heated by fresh air, it is sent into the oven through the pipe by the fan, thereby smoothly achieving the purpose of energy saving.

[0004] Although the existing waste heat recovery technology has improved the energy utilization efficiency to a certain extent, in practical applications, there is still the problem that the control system is not sophisticated enough. The feedback of parameters such as temperature, pressure, flow rate, etc. in the heat recovery process is not timely, resulting in insufficient operating efficiency of the overall system and failure to fully realize the potential of waste heat recovery. Therefore, it is necessary to introduce more advanced control strategies. The cascade split-range control method is a technology that achieves comprehensive control by adjusting different control links of the system in steps. This method can improve the dynamic response capability of the system and ensure that the waste heat recovery system can quickly adjust the operating state when the process parameters change. It helps to maintain the stability and efficiency of the system under fluctuating production conditions. Therefore, applying the cascade split-range control method to the waste heat recovery and utilization system of the stereotyper will help to improve the recovery rate, optimize energy utilization, and reduce environmental impact. Summary of the invention

[0005] The purpose of the present invention is to overcome the shortcomings of the prior art. The present invention provides a cascade split-range control method for a waste heat recovery system of a setting machine. The technical solution meets the needs of enterprises and provides a cascade split-range control solution for the existing waste heat recovery device and system of the waste gas of the setting machine. The method can improve the dynamic response capability of the system and ensure that the waste heat recovery system can quickly adjust the operating state when the process parameters change. It helps to maintain the stability and efficiency of the system under fluctuating production conditions.

[0006] In order to achieve the above-mentioned purpose, the present invention provides the following scheme: The present invention provides a cascade split-range control method for a waste heat recovery and utilization system of a setting machine. The high-temperature exhaust gas generated by the printing and dyeing setting machine enters the heat exchanger through an exhaust fan through an additional pipeline, and is converted into low-temperature exhaust gas and discharged; the normal temperature air flows into the heat exchanger through a pipeline from a new air fan, and becomes high-temperature air after heat exchange, and is then transported to each branch pipeline through the main air supply pipeline to supply each oven of the setting machine.

[0007] Furthermore, by setting up multiple control loops, the waste heat recovery system is divided into multiple stages for control according to the actual working state of the setting machine, so as to achieve efficient heat energy utilization.

[0008] The multiple control loops include a temperature control loop and a flow control loop, which respectively monitor and adjust different operating parameters in real time.

[0009] Furthermore, the temperature control loop is characterized by comprising the following aspects:

[0010] Function: The main function of the temperature control loop is to monitor and adjust the temperature parameters in the waste heat recovery system to ensure that the system operates within the optimal operating temperature range to improve heat exchange efficiency.

[0011] Real-time monitoring: Temperature sensors are installed to continuously monitor the temperature of key locations in the system, including the exhaust temperature of the setting machine and the operating temperature in the waste heat recovery device. These sensors feed real-time data back to the controller.

[0012] Adjustment mechanism: The controller adjusts the system's operating state based on the deviation between the set target temperature and the actual temperature. Adjustment measures may include: automatically adjusting the heat exchanger's operating mode, such as changing the fan speed or valve opening to ensure that the system temperature remains within the set range.

[0013] Furthermore, the flow control loop is characterized by comprising the following aspects:

[0014] Function: The flow control loop is responsible for monitoring and regulating the flow of fluid in the system to ensure the effective transfer and utilization of heat in the system. The stability of the flow is essential to maintain the efficiency of heat exchange.

[0015] Real-time monitoring: The flow velocity and flow rate of the fluid (fresh air) are monitored in real time through sensors such as flow meters. The data will be fed back to the controller for analysis.

[0016] Adjustment mechanism: The controller uses a control algorithm to adjust the system flow according to the difference between the set flow target and the actual flow. Specific adjustment measures include: adjusting the valve opening in the pipeline to achieve precise control of the fresh air flow, ensuring that the fresh air flow is always maintained at the optimal level of each branch pipeline under different working conditions.

[0017] Furthermore, the two control loops do not work independently, and they need to coordinate and interact to ensure the efficient operation of the overall system. Changes in temperature may affect flow demand, and changes in flow may affect temperature stability. Therefore, in the cascade control method, the temperature control loop and the flow control loop feed back and adjust together to achieve the optimal energy efficiency and stability of the system.

[0018] By simultaneously monitoring and adjusting temperature and flow, the system efficiency can be effectively avoided from being reduced due to fluctuations in a certain parameter, thereby maximizing the overall energy efficiency of waste heat recovery in the setting machine and achieving the goal of energy conservation and emission reduction. This comprehensive control strategy provides intelligent management for the waste heat recovery system, which can better adapt to the dynamically changing production environment and needs and optimize the operation effect.

[0019] Furthermore, the PID control algorithm is used to process the input signals of each control loop: the temperature data of each measurement point is fed back in real time through the temperature sensor to provide input signals for the PID control algorithm. The real-time flow data is collected through the flow meter to provide a basis for flow control decisions. The PID controller is a classic feedback control algorithm that achieves the control target based on the three components of the system error (proportional, integral, and differential), which are described as follows:

[0020] Proportional control (P): This part makes adjustments based on the current error (the difference between the set value and the actual value). The output of the controller is proportional to the current error. For example, if the temperature or flow rate deviates from the target value, the PID controller will immediately adjust it to ensure that the system returns to the set state as quickly as possible.

[0021] Integral control (I): The integral control part takes into account past errors and calculates the accumulation of errors over time to eliminate long-term deviations. When there is a deviation in the system, the integral term will continue to increase or decrease the control output, helping the system to gradually correct and stabilize near the target value. This is very effective in eliminating static errors.

[0022] Derivative control (D): The derivative control part is used to predict the future error behavior and make adjustments based on the current rate of change of the error. This mechanism helps the system respond in advance, even in fast-changing situations, reducing overshoot and oscillation, and improving the system's response speed and stability.

[0023] Further, input signal processing: temperature and flow sensors transmit real-time data to the controller, such as the difference between the actual temperature and the set temperature, and process the flow data accordingly. PID calculation: The controller uses the PID algorithm to calculate the error of each control loop to generate the corresponding control output signal. For example: in the temperature control loop, the PID controller will generate a regulation signal to control the operating status of the valve or fan. In the flow control loop, the PID controller will adjust the opening of the air supply valve to ensure that the flow remains at the required level.

[0024] Feedback adjustment: The feedback signal from real-time monitoring is input into the controller again for closed-loop adjustment. The controller ensures that the system can quickly adapt and maintain the ideal state under changing load and external environmental conditions through dynamic adjustment.

[0025] Further, there is the split-range control: the complexity of the system is simplified by decomposing it into multiple manageable sub-ranges, each of which can independently control specific variables (such as temperature, flow); split-range control is to divide the controller output signal into several signal segments, each signal segment controls a control valve, and each control valve only works within a certain segment of the entire range of the controller output signal. It is mainly used in systems with multiple control means with logical relationships and the same control purpose, in order to coordinate the actions of different control means. In different sub-ranges, the controller transmits signals and information to achieve coordinated actions between different links, ensuring the stability and efficiency of the overall operation of the system.

[0026] In the waste heat recovery system of the setting machine, the control process can be divided into a temperature control sub-process and a flow control sub-process.

[0027] Temperature control sub-program: responsible for monitoring and adjusting the temperature of the heat medium (exhaust gas from the setting machine) in the system to achieve the best waste heat recovery effect.

[0028] Flow control sub-range: According to the output of the temperature control sub-range, adjust the fresh air supply flow rate to ensure reasonable energy exchange.

[0029] Control implementation: Apply the PID control method described above in each sub-process, dynamically adjust the control signal according to the feedback data, and achieve precise control of the target variable. The control signal of the temperature control sub-process affects the execution of the flow control sub-process, forming a closed-loop feedback mechanism to ensure the coordinated operation of the two sub-processes.

[0030] The cascade sub-range control method for the waste heat recovery system of a setting machine provided by the present invention realizes the refined management of parameters such as temperature and flow rate by decomposing the complex waste heat recovery system of the setting machine into multiple independent but interrelated control sub-ranges. This method improves the response speed and energy efficiency of the system, while ensuring the safety and stability of the production process, and is an important means to improve the efficiency of waste heat recovery. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] The present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments, and the above and other advantages of the present invention will become more clear.

[0032] Figure 1 The present invention is a structural schematic diagram of a waste heat recovery system specifically used for a setting machine.

[0033] Figure 2 The present invention is a control block diagram of a cascade split-range control method for a waste heat recovery system of a setting machine. DETAILED DESCRIPTION

[0034] In order to make the above-mentioned purposes, features and advantages of the present invention more obvious and easy to understand, the technical scheme in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work belong to the scope of protection of the present invention.

[0035] Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.

[0036] The following is a detailed description of a cascade split-range control method for a waste heat recovery system of a setting machine provided by the present invention in conjunction with the accompanying drawings. An embodiment of a cascade split-range control method for a waste heat recovery system of a setting machine: The high-temperature exhaust gas generated by the printing and dyeing setting machine enters the rotary heat exchanger through an exhaust fan through an additional pipeline, and is converted into low-temperature exhaust gas and discharged; the normal temperature air flows into the rotary heat exchanger through a pipeline from a new air fan, and becomes high-temperature air after heat exchange, and is then transported to each branch pipeline through the main air supply pipeline to supply each oven of the setting machine.

[0037] Figure 1The schematic diagram of a waste heat recovery system for a setting machine is shown, and the cascade split-range control method is specifically applied. The setting machine includes 10 ovens S1-S10, and the exhaust gas is discharged to the exhaust main pipe through pipes. Temperature sensors T1-T10 are installed on the exhaust pipe of each oven to measure the exhaust gas temperature. During the waste heat recovery process, the pipe is connected to the exhaust main pipe to extract the exhaust gas, and a temperature sensor T13 is installed here.

[0038] The exhaust gas undergoes heat exchange through the rotary heat exchanger H, and the temperature decreases after entering. The low-temperature exhaust gas is discharged by the fan F2. At the same time, the fresh air is extracted by the fan F1, and is heated to high-temperature fresh air after passing through the rotary heat exchanger H, and then sent to the oven of the setting machine. The low-temperature fresh air side is equipped with a flow meter Q11, a temperature sensor T11 and a pressure sensor P1. The temperature sensor T12, the pressure sensor P2, the flow meters Q1-Q10 and the regulating valves L1-L10 are installed in the main pipeline and each branch pipeline to accurately control the flow and pressure.

[0039] The cascade split-range control method consists of two controllers connected in series to form a double closed-loop control system, including a temperature control loop and a flow control loop. The temperature control loop measures the temperature of the sizing machine exhaust gas through temperature sensors T1-T10 and the temperature deviation is calculated by the PID controller; the flow control loop feeds back the fresh air flow through flow meters Q1-Q10 and the flow deviation is calculated by the PID controller.

[0040] The two control loops do not work independently, and they need to coordinate and interact with each other to ensure the efficient operation of the overall system. For example, changes in temperature may affect flow demand, and changes in flow may affect temperature stability. Therefore, in the cascade control method, the temperature control loop and the flow control loop feed back and adjust together to achieve the optimal energy efficiency and stability of the system.

[0041] Further, there is the split-range control: the complexity of the system is simplified by decomposing it into multiple manageable sub-ranges, each of which can independently control specific variables (such as temperature, flow); split-range control is to divide the controller output signal into several signal segments, each signal segment controls a control valve, and each control valve only works within a certain segment of the entire range of the controller output signal. It is mainly used in systems with multiple control means with logical relationships and the same control purpose, in order to coordinate the actions of different control means. In different sub-ranges, the controller transmits signals and information to achieve coordinated actions between different links, ensuring the stability and efficiency of the overall operation of the system.

[0042] The temperature of the ovens S1-S10 of the setting machine is divided into three sections according to the different setting processes. The front section ovens S1-S3 are the setting evaporation stage, with a lower temperature, suitable for sending in high-temperature fresh air; S4-S9 are the setting stage, with the highest temperature, so no fresh air is needed; S10 is the last section, with a lower temperature, and high-temperature fresh air can be sent in. Therefore, the ovens that need to use a split-range controller to adjust the valve are S1, S2, S3 and S10.

[0043] Therefore, the split-range control is to divide the output signal of a PID regulator into 4 segments, each segment of the signal controls an actuator accordingly, and the 4 actuators adjust the opening of the fresh air flow valve in segments. The air volume can be sent to the oven of the setting machine by split-range control as needed. The PID control method described above is applied in each split-range, and the control signal is dynamically adjusted according to the feedback data to achieve precise control of the target variable. The control signal of the temperature control split-range affects the execution of the flow control split-range, forming a closed-loop feedback mechanism to ensure the coordinated work of the two split-ranges.

[0044] So far, the technical solutions of the present invention have been described in conjunction with the embodiments shown in the drawings. However, it is easy for those skilled in the art to understand that the protection scope of the present invention is obviously not limited to these specific embodiments. Without departing from the principles of the present invention, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will fall within the protection scope of the present invention.

Claims

1. A cascade split-range control method for a waste heat recovery system of a setting machine, characterized in that: The high-temperature exhaust gas generated by the printing and dyeing setting machine enters the rotary heat exchanger through the exhaust fan through the additional pipeline, and is converted into low-temperature exhaust gas and discharged; the normal temperature air flows into the rotary heat exchanger through the pipeline from the fresh air fan, and becomes high-temperature air after heat exchange, and then is transported to each branch pipeline through the main air supply pipeline to supply each oven of the setting machine. By setting multiple control loops, the waste heat recovery system is divided into multiple stages for control according to the actual working status of the setting machine to achieve efficient heat energy utilization.

2. A control method for cascade separation of waste heat recovery system of a setting machine according to claim 1, characterized in that: The multiple control loops include a temperature control loop and a flow control loop, which respectively monitor and adjust different operating parameters in real time.

3. Two control rings according to claim 2, characterized in that The two control loops do not work independently, and they need to coordinate and interact with each other to ensure the efficient operation of the overall system. Changes in temperature may affect flow demand, and changes in flow may affect temperature stability. Therefore, in the cascade control method, the temperature control loop and the flow control loop feed back and adjust together to achieve the optimal energy efficiency and stability of the system.

4. The method according to claim 1, characterized in that The PID control algorithm is used to process the input signals of each control loop to improve the response speed and stability of the system.

5. The method according to claim 1, characterized in that Set the priority rules to automatically adjust the working state of the control loop according to the exhaust temperature of the air supply oven of the setting machine.

6. The method according to claim 1, characterized in that Based on real-time data feedback, the waste heat recovery effect of the exhaust gas from the setting machine is adjusted and optimized.

7. A waste heat recovery system for a setting machine, characterized in that: The control is performed by adopting the cascade split-range control method described in any one of claims 1 to 6.

Images