Method for precise control of moisture and temperature at the outlet of a conditioning machine

Abstract

The application discloses a kind of accurate control methods of moisture and temperature of moisture regaining machine outlet, comprising:1, function relationship of hot air moisture content Wg in cylinder with tobacco flow, outlet moisture, ambient temperature and humidity data is established;2, the function relationship of hot air moisture content in moisture regaining cylinder with water addition, steam application amount is obtained by pipeline and wind volume calculation in moisture regaining cylinder;3, by coordinating control water addition and steam application amount, ensure that temperature and moisture two major index control stability.The application not only solves the problem of mutual restriction, mutual influence between temperature and moisture two sets of PID control system, but also effectively solves the problem of water stained tobacco due to system overshoot.

Description

Technical Field

[0001] This invention relates to the fields of artificial intelligence, intelligent sensors, and industrial communication, specifically a method for precise control of moisture and temperature at the outlet of a rehumidifier. Background Technology

[0002] In the tobacco industry, the loosening and rehumidification process is the first step in tobacco processing. It primarily involves applying steam and water to the tobacco leaves inside the drum to loosen and humidify them. The CPK (Cumulative Pressure Kilometer) of the tobacco leaf temperature and moisture content at the outlet of the loosening and rehumidification machine is a crucial control indicator, forming the basis for subsequent tobacco processing steps. The existing control method involves uniformly increasing the water and steam application rates from 0 to a set value at the start of production. Once the temperature and moisture meters at the outlet of the loosening and rehumidification machine detect the temperature and moisture content, the system switches from feedforward control to feedback control. This involves comparing the actual outlet temperature with the set value and using PID control to adjust the water application rate; similarly, comparing the actual outlet moisture content with the set value and using PID control to adjust the steam application rate. Therefore, the loosening and rehumidification machine contains two PID control systems: an outlet temperature PID control system and an outlet moisture PID control system. These two PID control systems influence each other. For example, the steam application rate controlling the outlet temperature affects both the outlet temperature and outlet moisture content; similarly, the water application rate controlling the outlet moisture content affects both the outlet temperature and outlet moisture content. This results in only one indicator being controlled during actual production, while the other is also being considered. Furthermore, during production, changes in ambient temperature, humidity, steam pressure, and moisture content can cause the PID control system parameters to become unsuitable, leading to overshoot and potentially causing water stains and smoke. Summary of the Invention

[0003] The present invention aims to address the shortcomings of the prior art by proposing a precise control method for the moisture and temperature at the outlet of a rehumidifier. This method aims to simultaneously achieve precise control of both the moisture and temperature at the outlet of the loose rehumidifier without causing water stains or smoke, thereby improving the production quality of the loose rehumidifier.

[0004] To achieve the above-mentioned objectives, the present invention adopts the following technical solution:

[0005] The present invention provides a method for precise control of moisture and temperature at the outlet of a rehumidifier, characterized by comprising the following steps:

[0006] Step 1: Obtain data on tobacco leaf flow rate, outlet moisture, ambient temperature and humidity, and hot air moisture content in the loose rehumidification cylinder for each batch of tobacco leaves under stable conditions, and establish a functional relationship between the moisture content Wg of the hot air in the loose rehumidification cylinder and the data on tobacco leaf flow rate, outlet moisture, and ambient temperature and humidity.

[0007] Step 2: Obtain the maximum value of the hot air moisture content in the loose rehumidification cylinder through experiments, and record it as MaxWg; set the maximum value MaxWg as the alarm threshold.

[0008] Step 3: Calculate the density ρ of the hot air inside the loose rehumidifier using equation (1):

[0009] ρ=K1÷(273+T) (1)

[0010] In equation (1), T is the temperature of the hot air being expelled from the loose rehumidifier, and K1 is a constant.

[0011] Step 4: Calculate the wind speed V of the hot air inside the loosening and rehydration cylinder using equation (2):

[0012] V=K2×sqrt(2×P÷ρ) (2)

[0013] In equation (2), P is the negative pressure of the exhaust hot air, sqrt represents the square root operation, and K2 is a constant;

[0014] Step 5: Calculate the air volume Q of the hot air inside the loosening and rehumidifying cylinder using equation (3):

[0015] Q = K3 × V × π × r 2 (3)

[0016] In equation (3), r is the radius of the drainage pipe, and K3 is a constant;

[0017] Step 6: Based on the actual temperature value at the outlet of the rehumidifier and the set temperature value, use the PID control model to adjust the opening of the steam diaphragm valve so that the actual temperature value at the outlet of the rehumidifier reaches the set temperature value, and measure the steam application rate FL2 through the vortex flow meter behind the steam diaphragm valve.

[0018] Step 7: Calculate the amount of moisture FL3 absorbed by the tobacco leaves in the loosening and rehydration cylinder per unit time based on the actual moisture content of the tobacco leaves at the inlet and the set moisture content at the outlet.

[0019] Step 8: Based on the fact that the moisture content Wg of the hot air in the loosening and rehumidifying cylinder is equal to the moisture discharged from the loosening and rehumidifying cylinder, calculate the amount of water FL1 applied to the loosening and rehumidifying cylinder per unit time using formula (4):

[0020] FL1 = Q × Wg + FL3 - FL2 (4)

[0021] In equation (4), FL2 represents the amount of steam applied to the loose rehydration cylinder per unit time;

[0022] Step 9: Calculate the maximum amount of water FL applied to the loose rehydration cylinder per unit time using formula (5). max :

[0023] FL max =MaxWg×Q+FL3-FL2 (5)

[0024] Step 10: Adjust the frequency of the water pump using the flow rate FL1 as the set value, so that the applied water volume is equal to FL1 and does not exceed FL. max .

[0025] The present invention provides an electronic device, including a memory and a processor, wherein the memory is used to store a program that supports the processor in executing the precise control method, and the processor is configured to execute the program stored in the memory.

[0026] The present invention discloses a computer-readable storage medium on which a computer program is stored, wherein the computer program is executed by a processor to perform the steps of the precise control method.

[0027] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0028] This invention establishes the correlation between the inlet tobacco flow rate, outlet moisture content, ambient temperature and humidity, and hot air moisture content inside the loose rehumidification cylinder using a TensorFlow time series prediction model. By adjusting the ratio of water addition and steam application, the moisture content of the hot air inside the loose rehumidification cylinder is kept stable. Simultaneously, by using PID to track the outlet temperature and adjust the steam application and water addition, not only can the outlet moisture content and outlet temperature be precisely controlled at the same time, but the occurrence of water-stained smoke is also effectively prevented by stabilizing the moisture content of the hot air inside the cylinder. Detailed Implementation

[0029] In this embodiment, a precise method for controlling the outlet moisture and temperature of a loosening and rehumidifying machine is implemented using a Siemens 1500 series PLC and a ProfiBus-PA network system to construct a data acquisition, processing, and output control system. The PLC collects data from electromagnetic flow meters, steam flow meters, moisture meters, temperature sensors, and negative pressure sensors. A TensorFlow time-series prediction model is used to establish the correlation between the inlet tobacco flow rate, outlet moisture, ambient temperature and humidity, and the moisture content of the hot air inside the loosening and rehumidifying cylinder. A PID controller tracks the outlet temperature and adjusts the steam application rate while simultaneously adjusting the water application rate to ensure a stable moisture content in the hot air inside the loosening and rehumidifying cylinder. Through this model, not only can the outlet moisture and temperature be precisely controlled simultaneously, but the moisture content of the hot air inside the cylinder is also effectively controlled to prevent water stains in the smoke. Specifically, this method is carried out according to the following steps:

[0030] Step 1: Obtain data on tobacco leaf flow rate, outlet moisture content, ambient temperature and humidity, and hot air moisture content in the loose rehumidification cylinder for each batch of tobacco leaves under stable conditions. Establish a functional relationship between the hot air moisture content Wg in the loose rehumidification cylinder and the tobacco leaf flow rate, outlet moisture content, and ambient temperature and humidity data.

[0031] Step 2: Obtain the maximum value of the hot air moisture content in the loose rehumidification cylinder through experiments, and record it as MaxWg; set the maximum value MaxWg as the alarm threshold.

[0032] Step 3: Calculate the density ρ of the hot air inside the loose rehumidifier using equation (1):

[0033] ρ=K1÷(273+T) (1)

[0034] In equation (1), T is the temperature of the hot air venting the loose rehumidification cylinder, and K1 is a constant. In this example, K1 = 35.96.

[0035] Step 4: Calculate the wind speed V of the hot air inside the loosening and rehydration cylinder using equation (2):

[0036] V=K2×sqrt(2×P÷ρ) (2)

[0037] In equation (2), P is the negative pressure of the exhaust hot air, sqrt represents the square root operation, and K2 is a constant. In this example, K2 = 0.593.

[0038] Step 5: Calculate the air volume Q of the hot air inside the loosening and rehumidifying cylinder using equation (3):

[0039] Q = K3 × V × π × r 2 (3)

[0040] In equation (3), r is the radius of the drainage pipe, and K3 is a constant. In this example, K3 = 900.

[0041] Step 6: Based on the actual temperature value at the outlet of the rehumidifier and the set temperature value, use the PID control model to adjust the opening of the steam diaphragm valve so that the actual temperature value at the outlet of the rehumidifier reaches the set temperature value, and measure the steam application rate FL2 through the vortex flow meter behind the steam diaphragm valve.

[0042] Step 7: Calculate the amount of moisture FL3 absorbed by the tobacco leaves in the loosening and rehydration cylinder per unit time based on the actual moisture content of the tobacco leaves at the inlet and the set moisture content at the outlet.

[0043] Step 8: According to the fact that the amount of water and steam applied into the cylinder per unit time is equal to the amount of water absorbed by the tobacco leaves per unit time and the amount of water discharged by the moisture exhaust system, and the moisture content Wg of the hot air in the loose and re-drying cylinder is equal to the moisture discharged by the moisture exhaust of the loose and re-drying cylinder, use Equation (4) to calculate the amount of water FL1 applied into the loose and re-drying cylinder per unit time:

[0044] FL1 = Q × Wg + FL3 - FL2 (4)

[0045] In Equation (4), FL2 represents the amount of steam applied into the loose and re-drying cylinder per unit time.

[0046] Step 9: To avoid water-stained tobacco, the moisture content Wg of the hot air in the loose and re-drying cylinder must be less than the experimentally obtained MaxWg, that is, FL1 < MaxWg × Q + FL3 - FL2, so as to use Equation (5) to calculate the maximum amount of water FL applied into the loose and re-drying cylinder per unit time max :[[ID=十二]]

[0047] FL max = MaxWg × Q + FL3 - FL2 (5)

[0048] Step 10: Take the flow rate FL1 as the set value to adjust the frequency of the water pump, so that the amount of water applied is equal to FL1 and does not exceed FL max .

[0049] In this embodiment, an electronic device includes a memory and a processor. The memory is used to store a program that supports the processor to execute the above method, and the processor is configured to execute the program stored in the memory.

[0050] In this embodiment, a computer-readable storage medium stores a computer program, and when the computer program is run by a processor, it executes the steps of the above method.

Claims

1. A method for precise control of moisture content and temperature at the outlet of a rehumidifier, characterized in that, Includes the following steps: Step 1: Obtain data on tobacco leaf flow rate, outlet moisture, ambient temperature and humidity, and hot air moisture content in the loose rehumidification cylinder for each batch of tobacco leaves under stable conditions, and establish a functional relationship between the moisture content Wg of the hot air in the loose rehumidification cylinder and the data on tobacco leaf flow rate, outlet moisture, and ambient temperature and humidity. Step 2: Obtain the maximum value of the hot air moisture content in the loose rehumidification cylinder through experiments, and record it as MaxWg; set the maximum value MaxWg as the alarm threshold. Step 3: Calculate the density ρ of the hot air inside the loose rehumidifier using equation (1): ρ=K1÷(273+T) (1) In equation (1), T is the temperature of the hot air being expelled from the loose rehumidifier, and K1 is a constant. Step 4: Calculate the wind speed V of the hot air inside the loosening and rehydration cylinder using equation (2): V=K2×sqrt(2×P÷ρ) (2) In equation (2), P is the negative pressure of the exhaust hot air, sqrt represents the square root operation, and K2 is a constant; Step 5: Calculate the air volume Q of the hot air inside the loosening and rehumidifying cylinder using equation (3): Q=K3×V×π×r 2 (3) In equation (3), r is the radius of the drainage pipe, and K3 is a constant; Step 6: Based on the actual temperature value at the outlet of the rehumidifier and the set temperature value, use the PID control model to adjust the opening of the steam diaphragm valve so that the actual temperature value at the outlet of the rehumidifier reaches the set temperature value, and measure the steam application rate FL2 through the vortex flow meter behind the steam diaphragm valve. Step 7: Calculate the amount of moisture FL3 absorbed by the tobacco leaves in the loosening and rehydration cylinder per unit time based on the actual moisture content of the tobacco leaves at the inlet and the set moisture content at the outlet. Step 8: Based on the fact that the moisture content Wg of the hot air in the loosening and rehumidifying cylinder is equal to the moisture discharged from the loosening and rehumidifying cylinder, calculate the amount of water FL1 applied to the loosening and rehumidifying cylinder per unit time using formula (4): FL1 = Q × Wg + FL3 - FL2 (4) In equation (4), FL2 represents the amount of steam applied to the loose rehydration cylinder per unit time; Step 9: Calculate the maximum amount of water FL applied to the loose rehydration cylinder per unit time using formula (5). max : IN max =MaxWg×Q+FL3-FL2 (5) Step 10: Adjust the frequency of the water pump using the flow rate FL1 as the set value, so that the applied water volume is equal to FL1 and does not exceed FL. max .

2. An electronic device, comprising a memory and a processor, characterized in that, The memory is used to store a program that supports the processor in executing the precise control method of claim 1, and the processor is configured to execute the program stored in the memory.

3. A computer-readable storage medium storing a computer program, characterized in that, The computer program is executed by the processor to perform the steps of the precise control method of claim 1.