A screw conveyor and method for asphalt feeding

Abstract

This invention discloses a screw conveying method for asphalt, relating to the field of asphalt conveying technology. The method includes: real-time acquisition of screw torque, rotational speed, inlet and outlet temperatures, blade temperatures, and the previous setpoint for heat transfer oil temperature during the operation of the screw conveyor; obtaining the apparent viscosity of the asphalt based on the torque and rotational speed, obtaining a reference viscosity based on the outlet temperature, and determining the current viscosity deviation; obtaining the dynamic temperature difference between the blades and the asphalt based on the blade temperature and the inlet and outlet temperatures; determining the response delay time based on the screw rotational speed, and predicting the viscosity deviation after the delay time based on the viscosity change rate; obtaining the heat transfer oil temperature adjustment amount based on the predicted viscosity deviation, viscosity change rate, and dynamic temperature difference, and updating the current setpoint for heating control. This invention, by introducing dynamic temperature difference and response delay prediction, achieves proactive compensation for asphalt viscosity fluctuations, significantly improving the stability and control accuracy of the screw conveyor.

Description

Technical Field

[0001] This invention belongs to the field of asphalt conveying technology, and particularly relates to a spiral feeding device and method for asphalt. Background Technology

[0002] Currently, various asphalt screw conveyor devices are disclosed in the prior art. For example, some devices use heat-conducting oil heating pipes installed on the outer wall of the casing to insulate the asphalt, while others maintain the conveying temperature through a heatable bearing structure. These solutions typically employ simple temperature feedback control, adjusting the heat-conducting oil heating power based on the deviation between the outlet temperature and the set value. In practical engineering applications, operators often manually adjust the heating temperature based on experience to cope with changes in asphalt viscosity.

[0003] However, the existing technology has the following drawbacks: First, it only focuses on temperature control while ignoring the crucial parameter of asphalt viscosity, thus failing to directly reflect changes in conveying resistance. Second, it does not consider the dynamic temperature difference between the spiral blades and the asphalt; when the blade temperature differs from the core temperature of the material, it can easily lead to localized wall adhesion or coking. Third, it does not consider the response delay of asphalt viscosity to temperature changes; after the heat transfer oil temperature is adjusted, the viscosity change takes a considerable amount of time to be transmitted to the discharge port, resulting in control lag and potentially causing torque fluctuations or even equipment overload. Therefore, the existing technology struggles to achieve precise and stable control of asphalt spiral feeding. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a spiral feeding device and method for asphalt, which solves the aforementioned problems.

[0005] To achieve the above objectives, the present invention provides the following technical solution: a spiral feeding method for asphalt, comprising:

[0006] Data during the operation of the screw conveyor is collected in real time. The data includes at least the screw torque, screw speed, inlet temperature, outlet temperature, multiple temperature measurement points distributed along the screw blades, and the set value of the heat transfer oil temperature at the previous moment.

[0007] The apparent viscosity of asphalt is obtained based on the screw torque and screw speed, and the reference viscosity is obtained based on the outlet temperature, thereby determining the current viscosity deviation;

[0008] The dynamic temperature difference between the spiral blade and the asphalt is obtained based on the temperature measurement points of the blade and the temperature of the inlet and outlet.

[0009] The response delay time of asphalt viscosity to changes in heat transfer oil temperature is determined based on the current screw speed, and the predicted viscosity deviation after the response delay time is predicted in combination with the current viscosity change rate.

[0010] Based on the predicted viscosity deviation, the current viscosity change rate, and the dynamic temperature difference, the adjustment amount of the heat transfer oil temperature is obtained, and the current heat transfer oil temperature setpoint is updated accordingly to perform heating control.

[0011] Based on the above technical solutions, the present invention also provides the following optional technical solutions:

[0012] A further technical solution: The apparent viscosity of the asphalt is calculated using the following formula:

[0013]

[0014] in, Indicates time The apparent viscosity of asphalt, Indicates time The helical torque, Indicates time The rotational speed of the helix This represents the geometric constants of the screw conveyor (in cubic meters).

[0015] A further technical solution: The reference viscosity is calculated using the following formula:

[0016]

[0017] in, Indicates time The reference viscosity of the asphalt at the discharge port. This represents the theoretical minimum viscosity of asphalt. The temperature constant of a material is expressed in Kelvin. , This represents the activation energy required for asphalt flow. (represents the ideal gas constant) Indicates time The outlet temperature.

[0018] A further technical solution: The current viscosity deviation is obtained by the following formula:

[0019]

[0020] in, Indicates the current viscosity deviation (time). (viscosity deviation) Indicates time The apparent viscosity of asphalt, Indicates time The reference viscosity of the asphalt at the discharge port.

[0021] Further technical solution: The dynamic temperature difference is obtained through the following steps:

[0022] Obtain the average blade temperature and average temperature of asphalt The dynamic temperature difference is obtained based on the average blade temperature and the average asphalt temperature. Specifically: ,in, Indicates the number of blade temperature sensors. Indicates the first The measured values ​​of each blade temperature sensor at time 10:00. Indicates the inlet temperature. This indicates the temperature at the discharge port.

[0023] Further technical solution: The response delay time is obtained through the following steps:

[0024] The axial movement speed of the asphalt is obtained based on the current helical rotation speed and the pitch of the helical blades, specifically:

[0025]

[0026] in, Indicates the axial movement speed of the asphalt. Indicates the current screw speed. Indicates the pitch of the helical blade;

[0027] The response delay time is obtained based on the axial movement speed of the asphalt, the total length of the screw conveyor, and the inherent delay time of heat conduction. Specifically:

[0028]

[0029] in, Indicates the response delay time. This indicates the total length of the screw conveyor. Indicates the axial movement speed of the asphalt. This represents the inherent delay time of heat conduction.

[0030] A further technical solution: The viscosity deviation after the response delay time is obtained by the following formula:

[0031]

[0032] in, This indicates the predicted viscosity deviation after the response delay time. Indicates the response delay time. This represents the rate of change in viscosity. Indicates the current viscosity deviation;

[0033] The viscosity change rate is approximately calculated using the difference method:

[0034]

[0035] in, This represents the rate of change in viscosity. This represents the apparent viscosity at the current moment. This represents the apparent viscosity at the previous sampling time. Indicates the sampling time interval.

[0036] A further technical solution: The adjustment amount of the heat transfer oil temperature is calculated using the following formula:

[0037]

[0038] in, This indicates the adjustment amount of the heat transfer oil temperature at the current moment. Indicates the predicted viscosity deviation. This represents the rate of change in viscosity. Indicates dynamic temperature difference. Represents the proportionality coefficient. Represents the differential coefficient. This represents the feedforward coefficient.

[0039] A further technical solution: The current setpoint for the heat transfer oil temperature is updated using the following formula:

[0040]

[0041] in, This indicates the current setpoint for the heat transfer oil. This indicates the amount of heat transfer oil temperature adjustment at the current moment. This indicates the setpoint temperature of the heat transfer oil at the previous moment.

[0042] A spiral feeding device for asphalt includes a spiral feeder, which adopts the above-mentioned spiral feeding method for asphalt. The spiral feeder is a hollow blade or jacket structure, and the blades are filled with heat transfer oil.

[0043] This invention provides a spiral feeding device and method for asphalt, which has the following advantages compared with the prior art:

[0044] 1. This invention collects the screw torque in real time and converts it into apparent viscosity, using viscosity as a direct control target. Compared with the traditional method of only monitoring temperature, it can more realistically reflect the flow state of asphalt during transportation, avoiding the problem of a sharp increase in transportation resistance caused by abnormal viscosity.

[0045] 2. This invention calculates the dynamic temperature difference between the blade temperature and the average asphalt temperature and introduces it as a feedforward compensation term into the control algorithm. When an excessive temperature difference is detected, the heating amount is adjusted in advance, which effectively prevents wall sticking and blockage caused by local overcooling and asphalt aging and coking caused by local overheating, thus extending the service life of the equipment.

[0046] 3. This invention overcomes the control problem caused by the large thermal inertia of asphalt and the lag in viscosity response by introducing the concept of response delay time and combining it with the viscosity change rate to predict the viscosity deviation after the delay. It achieves advance compensation and avoids the overshoot oscillation phenomenon in traditional feedback control.

[0047] 4. This invention adopts a proportional-derivative-feedforward composite control structure, which integrates three parameters with clear physical meanings—predicted viscosity deviation, viscosity change rate, and dynamic temperature difference—into the same control law. These parameters correspond to future error compensation, trend suppression, and local temperature difference correction, respectively, significantly improving the robustness and adaptability of the control system. Attached Figure Description

[0048] Figure 1 This is a schematic diagram of the process of the present invention. Detailed Implementation

[0049] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0050] The specific implementation of the present invention will be described in detail below with reference to specific embodiments.

[0051] Please see Figure 1 The present invention provides a spiral feeding method for asphalt, comprising the following steps:

[0052] Data during the operation of the screw conveyor is collected in real time. The data includes at least the screw torque, screw speed, inlet temperature, outlet temperature, multiple temperature measurement points distributed along the screw blades, and the set value of the heat transfer oil temperature at the previous moment.

[0053] The apparent viscosity of asphalt is obtained based on the screw torque and screw speed, and the reference viscosity is obtained based on the outlet temperature, thereby determining the current viscosity deviation;

[0054] The dynamic temperature difference between the spiral blade and the asphalt is obtained based on the temperature measurement points of the blade and the temperature of the inlet and outlet.

[0055] The response delay time of asphalt viscosity to changes in heat transfer oil temperature is determined based on the current screw speed, and the predicted viscosity deviation after the response delay time is predicted in combination with the current viscosity change rate.

[0056] Based on the predicted viscosity deviation, the current viscosity change rate, and the dynamic temperature difference, the adjustment amount of the heat transfer oil temperature is obtained, and the current heat transfer oil temperature setpoint is updated accordingly to perform heating control.

[0057] In this embodiment of the invention, firstly, data is collected in real time during the operation of the screw conveyor. This data includes at least the screw torque, screw speed, inlet temperature, outlet temperature, multiple temperature measurement points distributed along the screw blades, and the previous setpoint for the heat transfer oil temperature. Specifically, data collection can be achieved by installing various sensors on the screw conveyor. For example, a torque sensor can be installed on the screw shaft to measure the torque borne by the screw shaft; a speed sensor can be installed on the motor shaft to measure the motor speed; and temperature sensors can be arranged at different locations at the inlet, outlet, and screw blades to measure the temperature of the asphalt and the blades. The previous setpoint for the heat transfer oil temperature can be directly read from the control system. Alternatively, data collection can be achieved through an integrated industrial control system or a distributed control system. These systems typically have the ability to interface with various field instruments and sensors, and can automatically acquire and store the required operating data at a preset sampling frequency.

[0058] Secondly, the apparent viscosity of the asphalt is obtained based on the screw torque and screw speed, and a reference viscosity is obtained based on the discharge port temperature, thus determining the current viscosity deviation. Specifically, the apparent viscosity can be calculated using a pre-established empirical model or a simplified rheological model. For example, the apparent viscosity of the asphalt can be estimated based on the relationship between the geometric parameters of the screw conveyor, torque, and speed, through table lookup or simple algebraic operations. The reference viscosity can be obtained by consulting a material handbook or a pre-set temperature-viscosity curve, based on the type of asphalt and the target discharge temperature. The current viscosity deviation is determined by directly comparing the calculated apparent viscosity with the obtained reference viscosity. Alternatively, the apparent viscosity can be obtained through more complex numerical simulations or machine learning models. For example, a regression model can be trained using historical operating data, taking torque and speed as input and outputting apparent viscosity. The reference viscosity can be accurately calculated based on theoretical models such as the Arrhenius equation for asphalt, combined with the discharge port temperature. Subsequently, the calculated apparent viscosity is subtracted from the reference viscosity to obtain the current viscosity deviation.

[0059] Furthermore, the dynamic temperature difference between the helical blades and the asphalt is obtained based on the blade temperature measurement points and the inlet and outlet temperatures. Specifically, the average blade temperature can be obtained by arithmetically averaging the temperature values ​​from multiple temperature measurement points distributed along the helical blades. Simultaneously, the average asphalt temperature can be obtained by averaging the inlet and outlet temperatures. Then, the average blade temperature is compared with the average asphalt temperature, and the difference is the dynamic temperature difference. Alternatively, a weighted average or other statistical methods can be used to process the blade temperature measurement points to more accurately reflect the overall blade temperature. For example, higher weights can be assigned to blade measurement points near the outlet, and the average asphalt temperature can be estimated using a more complex heat transfer model. Then, the dynamic temperature difference is obtained by calculating the instantaneous difference between the blade temperature and the asphalt temperature.

[0060] Furthermore, the response delay time of asphalt viscosity to changes in heat transfer oil temperature is determined based on the current screw speed, and the predicted viscosity deviation after this response delay time is predicted in conjunction with the current viscosity change rate. Specifically, the response delay time can be determined using a preset lookup table or empirical formula based on the material conveying speed and heat conduction characteristics at different screw speeds. For example, the higher the screw speed, the shorter the residence time of the material in the screw conveyor, and the shorter the response delay time. The viscosity change rate can be approximated by comparing the apparent viscosity at the current moment with that at the previous moment. The predicted viscosity deviation is obtained by adding the current viscosity deviation to the increment of the viscosity change rate multiplied by the response delay time. Alternatively, the response delay time can be dynamically calculated by establishing a material flow and heat transfer model within the screw conveyor. For example, the axial movement speed of the material can be calculated based on parameters such as screw speed, screw blade pitch, and screw conveyor length, and the total response delay time can be determined by combining this with the inherent delay time of heat conduction. The viscosity change rate can be obtained by performing linear regression or difference operations on viscosity data from multiple consecutive sampling points. The predicted viscosity deviation is obtained by superimposing the current viscosity deviation with the future viscosity change calculated based on the response delay time and viscosity change rate.

[0061] Finally, based on the predicted viscosity deviation, the current viscosity change rate, and the dynamic temperature difference, the adjustment amount for the heat transfer oil temperature is obtained, and the current heat transfer oil temperature setpoint is updated accordingly to execute heating control. Specifically, the adjustment amount for the heat transfer oil temperature can be calculated using a simple proportional-derivative controller combined with feedforward control. The predicted viscosity deviation serves as the input to the proportional term, the viscosity change rate as the input to the derivative term, and the dynamic temperature difference as the input to the feedforward term. These inputs are multiplied by their respective gain coefficients and then summed to obtain the total adjustment amount. The current heat transfer oil temperature setpoint is updated by adding the previous setpoint to this adjustment amount. Alternatively, more advanced control algorithms, such as model predictive control or fuzzy logic control, can be used to obtain the adjustment amount for the heat transfer oil temperature. These algorithms can comprehensively consider multiple input variables and the dynamic characteristics of the system to optimize and calculate the optimal adjustment amount. After updating the heat transfer oil temperature setpoint, this setpoint is sent to the heat transfer oil heating system, thereby achieving heating control of the asphalt to maintain its viscosity within the target range.

[0062] The following example will provide a more detailed explanation of the above technical solution:

[0063] Suppose user A operates an asphalt screw conveyor at location A to transport asphalt from a storage tank to a mixing plant. The goal is to ensure that the asphalt maintains a stable viscosity during transport to guarantee the quality of subsequent mixing and the smooth operation of the equipment.

[0064] During operation, sensors on the screw conveyor collect various data in real time. For example, a torque sensor continuously monitors the torque of the screw shaft, a speed sensor records the screw speed, and temperature sensors at the inlet and outlet measure the inlet and outlet temperatures of the asphalt, respectively. Simultaneously, multiple temperature measuring points distributed along the screw blades provide temperature data for the blade surface. Furthermore, the control system records the previous temperature setpoint of the heat transfer oil.

[0065] The collected screw torque and screw speed are input into the calculation module, which calculates the apparent viscosity of the asphalt based on the preset rheological model. At the same time, based on the outlet temperature, the reference viscosity at the current moment is calculated through the temperature-viscosity relationship curve of the asphalt. Then, the apparent viscosity is compared with the reference viscosity to obtain the current viscosity deviation. For example, if the calculated apparent viscosity is 1500 mPa·s, while the reference viscosity is 1200 mPa·s, the current viscosity deviation is 300 mPa·s, indicating that the asphalt is currently too thick.

[0066] The temperature values ​​at multiple blade measuring points are averaged to obtain the average blade temperature. The inlet and outlet temperatures are also averaged to obtain the average asphalt temperature. By calculating the difference between the average blade temperature and the average asphalt temperature, the dynamic temperature difference between the helical blade and the asphalt is obtained. For example, if the average blade temperature is 160℃ and the average asphalt temperature is 170℃, the dynamic temperature difference is -10℃, indicating that the blade temperature is lower than the asphalt temperature, which may indicate insufficient heat transfer.

[0067] Based on the current screw rotation speed, the system dynamically calculates the residence time of asphalt within the screw conveyor and, combined with the inherent delay in heat conduction, determines the response delay time of asphalt viscosity to changes in the temperature of the heat transfer oil. For example, if the calculated response delay time is 30 seconds, the system also calculates the viscosity change rate by comparing the apparent viscosity at the current moment with that at the previous moment. For instance, if the viscosity change rate is 5 mPa·s / s, using the current viscosity deviation (300 mPa·s), the viscosity change rate (5 mPa·s / s), and the response delay time (30 seconds), the system predicts that the predicted viscosity deviation of the asphalt after 30 seconds will be 300 + 5 × 30 = 450 mPa·s. This prediction value can anticipate potential future viscosity issues.

[0068] Based on the predicted viscosity deviation (450 mPa·s), the current viscosity change rate (5 mPa·s / s), and the dynamic temperature difference (-10℃), the control algorithm calculates the adjustment amount for the heat transfer oil temperature. For example, if the predicted viscosity deviation is positive (asphalt is too thick), the viscosity change rate is positive (viscosity is still increasing), and the dynamic temperature difference is negative (blade temperature is lower than asphalt temperature, resulting in insufficient heat transfer), a large positive adjustment amount, such as +5℃, will be calculated, which increases the heat transfer oil temperature. This adjustment amount is added to the heat transfer oil temperature setpoint from the previous moment to form the current heat transfer oil temperature setpoint. The new setpoint is sent to the heat transfer oil heating system, thereby precisely adjusting the heating power to achieve stable control of the asphalt viscosity.

[0069] Existing technologies typically rely solely on outlet temperature for simple feedback control, but temperature does not directly reflect the conveying resistance of asphalt. This application directly quantifies the flow characteristics of asphalt by acquiring its apparent viscosity in real time and comparing it with a reference viscosity. For example, in the above example, even if the outlet temperature appears normal, if the apparent viscosity is too high, this application can promptly detect and adjust it, avoiding conveying difficulties or equipment overload caused by excessive viscosity—something that existing technologies cannot achieve.

[0070] Furthermore, existing technologies do not consider the dynamic temperature difference between the spiral blades and the asphalt, which can easily lead to localized wall adhesion or coking. This application calculates the dynamic temperature difference between the spiral blades and the asphalt by collecting multiple temperature measurement points distributed along the spiral blades and the inlet and outlet temperatures. In the example above, if the dynamic temperature difference is negative, it indicates uneven heat exchange between the blades and the asphalt, which may cause the asphalt to locally cool and thicken or even coke on the blade surface. This application incorporates this dynamic temperature difference into the control considerations, enabling more precise adjustment of heating, effectively avoiding localized wall adhesion and coking, and improving the stability of the conveying process.

[0071] Furthermore, existing technologies do not consider the response delay of asphalt viscosity to temperature changes, resulting in control lag. This application dynamically determines the response delay time based on the current screw speed and predicts the viscosity deviation after this delay time by combining the viscosity change rate. In the example above, after the heat transfer oil temperature is adjusted, it takes a certain amount of time for the asphalt viscosity to change at the outlet. By predicting future viscosity deviations, this application can adjust the heating in advance, effectively overcoming the control lag problem, avoiding torque fluctuations and equipment overload caused by lag control, and achieving more precise and stable heating control.

[0072] Preferably, the apparent viscosity of the asphalt is calculated using the following formula:

[0073]

[0074] in, Indicates time The apparent viscosity of asphalt, Indicates time The helical torque, Indicates time The rotational speed of the helix The geometric constants of the screw conveyor (in cubic meters);

[0075] The reference viscosity is calculated using the following formula:

[0076]

[0077] in, Indicates time The reference viscosity of the asphalt at the discharge port. This represents the theoretical minimum viscosity of asphalt. The temperature constant of a material is expressed in Kelvin. , This represents the activation energy required for asphalt flow. (represents the ideal gas constant) Indicates time The outlet temperature;

[0078] The current viscosity deviation is obtained by the following formula:

[0079]

[0080] in, Indicates the current viscosity deviation (time). (viscosity deviation) Indicates time The apparent viscosity of asphalt, Indicates time The reference viscosity of the asphalt at the discharge port.

[0081] Among them, the formula for calculating the apparent viscosity of asphalt. Used to accurately quantify the flow resistance characteristics of asphalt during screw conveying. Screw torque. It directly reflects the shear resistance of the asphalt to the helical blades, and the helical rotation speed. The shear rate is determined by the geometric constants of the screw conveyor. This formula characterizes the structural properties of the screw conveyor and can be determined through expert experience, experimental calibration, or fitting of historical data. Using this formula, the actual apparent viscosity of asphalt under current operating conditions can be obtained in real time and dynamically. This can be achieved by pre-setting the mathematical model in the control system and calculating using real-time input of torque and speed data collected by sensors; or by consulting a pre-established viscosity lookup table based on torque, speed, and geometric parameters. (Refer to viscosity calculation formula) The viscosity value used to determine asphalt under ideal or target conditions is usually closely related to the temperature characteristics of the asphalt. This is the outlet temperature, a key parameter for asphalt to reach its target viscosity. (Constant) and These are inherent properties of asphalt materials, which can be obtained through experimental calibration or by consulting material handbooks. The formula can be implemented by embedding the exponential model into the control system and calculating it in real-time using outlet temperature data; or by obtaining it through a pre-established reference viscosity curve or lookup table based on outlet temperature. Current viscosity deviation calculation formula. This formula is used to quantify the difference between the actual apparent viscosity of asphalt and the target reference viscosity. This deviation value is a key indicator for measuring whether the asphalt viscosity is in an ideal state. Its sign and magnitude directly indicate the degree and direction of the viscosity deviation from the target value. Through this formula, it is possible to intuitively determine whether the current asphalt fluidity meets the process requirements. It can be implemented by directly performing a subtraction operation in the control system to compare the real-time calculated apparent viscosity with the reference viscosity; or by inputting the two viscosity values ​​into the comparison module, which then outputs the difference.

[0082] This application's solution quantifies the apparent viscosity, reference viscosity, and deviations between them of asphalt by introducing a precise mathematical model, thus providing an accurate basis for subsequent heat transfer oil temperature adjustment. Specifically, the spiral torque... and screw speed It is a physical quantity that directly reflects the shear force and shear rate experienced by asphalt in a screw conveyor. By substituting these real-time collected data into the apparent viscosity calculation formula based on fluid mechanics principles, This allows for real-time and objective reflection of the actual flow characteristics of asphalt under current working conditions. Furthermore, considering the sensitivity of asphalt viscosity to temperature, the outlet temperature is used as a reference. Combined with the inherent constants of asphalt materials and Using the exponential form of the reference viscosity calculation formula This allows for the accurate determination of the ideal viscosity of asphalt at the target temperature. Subsequently, the apparent viscosity, calculated in real time, is then... Compared with the ideal reference viscosity Comparison, through simple subtraction. This will allow us to obtain the current viscosity deviation. This deviation value not only quantifies the degree to which the asphalt viscosity deviates from the target value, but also indicates the direction of the deviation, providing a precise feedback signal for subsequent heating control. This precise calculation method based on physical models and material properties means that the assessment of asphalt viscosity no longer relies on empirical judgment or rough estimation, but is based on scientific quantification. This significantly improves the accuracy and reliability of viscosity control, thereby effectively solving the problems of low efficiency and product quality fluctuations caused by inaccurate viscosity control during asphalt transportation.

[0083] In one specific implementation method, the screw conveyor system for asphalt can employ an industrial control computer or programmable logic controller (PLC) as the core processing unit. This unit receives data from torque sensors, speed sensors, and temperature sensors. When the apparent viscosity of the asphalt needs to be calculated, the control program calls a pre-stored formula. ,in and These are values ​​uploaded by the sensors in real time. The values ​​are constants that are calibrated and fixed in the program during system debugging based on the specific geometric dimensions of the screw conveyor (such as blade diameter, shaft diameter, and pitch). For the calculation of the reference viscosity, the control program will call the formula... ,in It is the value measured in real time by the outlet temperature sensor, and and These are parameters determined through laboratory rheological testing for specific asphalt materials, and these parameters are also preset in the program. Once the apparent viscosity... and reference viscosity Once everything is calculated, the control program will immediately perform the subtraction operation. This yields the current viscosity deviation, which is then transmitted to subsequent control modules for further decisions regarding heat transfer oil temperature adjustment. For example, if... A positive and large value indicates that the asphalt viscosity is too high, and the temperature of the heat transfer oil needs to be increased; a negative and large value indicates that the viscosity is too low, and the temperature of the heat transfer oil may need to be decreased.

[0084] Through the above technical solution, this application provides a more accurate and reliable asphalt viscosity assessment mechanism. By introducing a physical model-based apparent viscosity calculation formula and a material property-based reference viscosity calculation formula, the actual and target viscosity states of asphalt during the screw conveying process can be accurately quantified. This precise quantification method overcomes the empirical or estimation errors that may exist in traditional methods, ensuring that the calculated viscosity deviation results have high accuracy and real-time performance. Therefore, it provides a solid data foundation for subsequent heat transfer oil temperature adjustment, significantly improves the viscosity control accuracy of the entire asphalt screw conveying process, helps maintain asphalt in the optimal flow state for transportation, thereby improving conveying efficiency, reducing energy consumption, and ensuring the stability of the final product quality.

[0085] Preferably, the dynamic temperature difference is obtained through the following steps:

[0086] Obtain the average blade temperature and average temperature of asphalt The dynamic temperature difference is obtained based on the average blade temperature and the average asphalt temperature. Specifically: ,in, Indicates the number of blade temperature sensors. Indicates the first The measured values ​​of each blade temperature sensor at time 10:00. Indicates the inlet temperature. This indicates the temperature at the discharge port.

[0087] Among them, the average leaf temperature This refers to the average temperature of the helical blades at a specific moment. Its function is to reflect the actual temperature state of the helical blades as the heating medium. This average blade temperature... Temperature can be obtained in several ways. For example, multiple temperature sensors (such as thermocouples or resistance temperature detectors) can be evenly distributed inside or on the surface of the spiral blades to collect temperature values ​​at each point in real time, and then these measurements can be arithmetically averaged. Alternatively, an infrared thermal imager can be used to scan the surface of the spiral blades to obtain the temperature distribution on the blade surface, and the average temperature can be calculated using image processing techniques. (Asphalt average temperature) This refers to the average temperature of asphalt inside the screw conveyor. Its function is to reflect the overall heating state of the asphalt during the conveying process. This average asphalt temperature... Temperature sensors can be installed at both the inlet and outlet to measure the inlet temperature. and discharge port temperature The arithmetic mean of these values ​​is then used to obtain the temperature; alternatively, multiple temperature sensors can be evenly arranged axially inside the screw conveyor to measure the temperature of the asphalt at different locations, and then the average of these temperatures can be calculated. Dynamic temperature difference. This refers to the difference between the average temperature of the spiral blades and the average temperature of the asphalt. Its function is to directly quantify the thermal potential difference between the heating medium (blades) and the heated material (asphalt), and it is a key factor driving heat transfer. It can more accurately reflect the efficiency and direction of heat exchange. This dynamic temperature difference... The average blade temperature can be calculated and average temperature of asphalt The temperature difference can be obtained directly by subtraction; alternatively, factors such as the heat exchange coefficient can be considered to obtain a more precise dynamic temperature difference through model calculation, but the core is still based on the temperature difference between the blade and the asphalt.

[0088] This application's solution directly quantifies the heat transfer potential between the heating medium and the heated object by acquiring the average temperature of the spiral blades and the average temperature of the asphalt in real time and calculating the dynamic temperature difference between them. Building upon the existing method of obtaining the apparent viscosity of the asphalt based on the spiral torque and rotation speed, and the reference viscosity based on the outlet temperature to determine the current viscosity deviation, the dynamic temperature difference is introduced as additional thermal state information. This allows the system to not only sense changes in asphalt viscosity but also directly assess the efficiency of heat exchange. This combined approach ensures that the adjustment of the heat transfer oil temperature no longer relies solely on indirect viscosity feedback but incorporates direct thermodynamic information, enabling more accurate prediction and response to the heating needs of the asphalt. This effectively overcomes the lag and inaccuracy that may exist in control based solely on viscosity deviation.

[0089] The following is a specific example illustrating how to obtain dynamic temperature differences in the spiral feeding method for asphalt. The following method can be used: First, distribute evenly on the spiral blades. Each thermistor (e.g., an NTC thermistor) serves as a blade temperature sensor, and the measured value of each thermistor is acquired in real time. These measurements are then transmitted to the controller for processing. The controller calculates the arithmetic mean of these measurements to obtain the average blade temperature. Meanwhile, platinum resistance temperature sensors (e.g., PT100) are installed at both the inlet and outlet of the screw conveyor to measure the inlet temperature in real time. and discharge port temperature The controller calculates the arithmetic mean of these two temperature values ​​to obtain the average temperature of the asphalt. Finally, the controller will average the blade temperature. Subtract the average temperature of asphalt This gives us the dynamic temperature difference $\Delta T(t)$ at the current moment.

[0090] By explicitly considering the dynamic temperature difference between the heating blades and the asphalt, this application can more accurately assess the actual heat exchange efficiency and the heating state of the asphalt. This allows for more precise and timely adjustment of the heat transfer oil temperature, effectively avoiding temperature overshoot or under-adjustment caused by thermal inertia or insufficient heat transfer. This ensures that the temperature and viscosity of the asphalt remain within the target range during the screw conveying process, improving the stability and accuracy of heating control.

[0091] Preferably, the response delay time is obtained through the following steps:

[0092] The axial movement speed of the asphalt is obtained based on the current helical rotation speed and the pitch of the helical blades, specifically:

[0093]

[0094] in, Indicates the axial movement speed of the asphalt. Indicates the current screw speed. Indicates the pitch of the helical blade;

[0095] The response delay time is obtained based on the axial movement speed of the asphalt, the total length of the screw conveyor, and the inherent delay time of heat conduction. Specifically:

[0096]

[0097] in, Indicates the response delay time. This indicates the total length of the screw conveyor. Indicates the axial movement speed of the asphalt. This represents the inherent delay time of heat conduction;

[0098] The viscosity deviation after the response delay time is obtained by the following formula:

[0099]

[0100] in, This indicates the predicted viscosity deviation after the response delay time. Indicates the response delay time. This represents the rate of change in viscosity. Indicates the current viscosity deviation;

[0101] The viscosity change rate is approximately calculated using the difference method:

[0102]

[0103] in, This represents the rate of change in viscosity. This represents the apparent viscosity at the current moment. This represents the apparent viscosity at the previous sampling time. Indicates the sampling time interval.

[0104] Among them, the axial movement speed of asphalt This represents the actual speed at which asphalt moves along the axial direction inside the screw conveyor. Its concept lies in quantifying the dynamic behavior of asphalt during the conveying process. It is a key parameter for calculating the residence time of asphalt within the conveyor, and this speed can be obtained from the current screw rotation speed. pitch with the helical blade The product is used to obtain the screw speed. The speed can be measured in real time by a speed sensor (e.g., encoder, photoelectric sensor, or Hall sensor) mounted on the drive shaft of the screw conveyor. The pitch of the screw blades... These are the inherent geometric parameters of the screw conveyor, typically determined during equipment design or manufacturing, and can be pre-stored in the control system. Response delay time. This refers to the total time required from the change in the temperature of the heat transfer oil to the corresponding change in the viscosity of the asphalt at the outlet. It comprehensively considers the physical transport time of the asphalt within the screw conveyor and the inherent delay time of heat transfer from the heat transfer oil to the asphalt and its effect on its viscosity. The physical conveying time of asphalt within the conveyor can be determined by the total length of the screw conveyor. Divide by the axial movement speed of asphalt To estimate the total length These are the fixed geometric parameters of the screw conveyor, including the inherent delay time of heat conduction. This reflects the physical characteristics of heat transfer, which can be estimated through experimental calibration, based on heat transfer models, or assigned values ​​based on expert experience. (Predicting viscosity deviation) Indicates the response delay time Subsequently, the difference between the expected viscosity of the asphalt at the discharge port and the reference viscosity serves to provide a forward-looking control signal, enabling the control system to anticipate future viscosity conditions rather than simply reacting to the current state. This prediction is calculated by measuring the current viscosity deviation. With response delay time The amount of change that may occur in the internal viscosity (i.e., response delay time) Multiply by the viscosity change rate The viscosity change rate is obtained by adding the two components together. This quantifies the rate of change of the apparent viscosity of asphalt over time. It is an important indicator for assessing the viscosity trend of asphalt and is crucial for predicting future viscosity conditions. This rate of change can be approximated using the finite difference method, i.e., using the apparent viscosity at the current moment. Subtract the apparent viscosity at the previous sampling time Divide by the sampling time interval Sampling time interval It is a fixed period for the control system to acquire and process data, which can be set to 1 second, 5 seconds or 10 seconds.

[0105] The proposed solution significantly improves the accuracy and stability of asphalt heating control by introducing a prediction mechanism for the system's dynamic response delay. Specifically, after acquiring the operating data of the screw conveyor in real time, the system first determines the accuracy based on the current screw speed. And the pitch of the helical blades The axial speed of asphalt within the screw conveyor was calculated. This axial movement speed This directly reflects the residence time of asphalt within the conveyor and is the basis for determining the physical transport delay. Subsequently, the total length of the screw conveyor is considered. and the inherent delay time of heat conduction The response time of asphalt viscosity to changes in heat transfer oil temperature was accurately obtained. This response delay time It is dynamically changing because it depends on the real-time variation of the screw speed, thus making the estimation of the delay time closer to actual operating conditions. In obtaining the response delay time... At the same time, the system also analyzes the apparent viscosity at the current moment. Apparent viscosity at the previous sampling time By performing a difference operation, the rate of change of asphalt viscosity can be approximately calculated. This viscosity change rate The changing trend of asphalt viscosity was revealed. Finally, the current viscosity deviation was... With consideration of response latency The viscosity changes are superimposed to predict the response delay time. Predicted viscosity deviation This predicted viscosity deviation This represents the viscosity state of the asphalt at a future point in time (i.e., after the response delay time), allowing subsequent adjustments to the heat transfer oil temperature to be based on predictions of the future state rather than simply a delayed response to the current state. In this way, the entire control system can react to changes in asphalt viscosity earlier, ensuring that the viscosity is maintained more precisely within the target range when the asphalt reaches the discharge port, effectively avoiding control lag and viscosity fluctuations caused by the delay effect.

[0106] The following is a concrete example to illustrate this. Assume the screw conveyor is equipped with a speed sensor, capable of sampling at 1-second intervals. Real-time output of screw speed The pitch of the helical blade The total length of the screw conveyor is 0.5 meters. The inherent time delay of heat conduction is 10 meters. The experimentally calibrated time was 5 seconds. At a certain moment... The system collects the current screw speed. The apparent viscosity at the previous sampling time is 2 revolutions per second. The apparent viscosity at the current moment is 100 Pa·s. The current viscosity deviation is 102 Pa·s. The value is 5 Pa·s. First, calculate the axial movement velocity of the asphalt. =1 m / s. Next, calculate the response delay time. =15 seconds. Then, calculate the viscosity change rate. =2 Pa·s / second. Finally, the predicted viscosity deviation after the response delay time is calculated. =35 Pa·s. Through the above calculation, the control system obtains the predicted deviation of the asphalt viscosity 15 seconds later, rather than just the current deviation. Based on this predicted value, the system can adjust the heat transfer oil temperature in advance, so that the viscosity of the asphalt when it actually reaches the outlet is closer to the target value.

[0107] Through the above technical solution, this application can effectively solve the response delay problem in asphalt heating control. By calculating the axial movement speed of the asphalt in real time and combining it with the geometric parameters and thermal conductivity characteristics of the screw conveyor, the response delay time is dynamically determined, making the prediction of future viscosity states more accurate. This forward-looking prediction of viscosity deviation means that the adjustment of the heat transfer oil temperature is no longer just a delayed response to the current state, but can anticipate and compensate for the inherent delay effect of the system in advance. Therefore, in the process of screw conveying asphalt, the accuracy and stability of asphalt viscosity control can be significantly improved, reducing viscosity overshoot or undershoot caused by temperature fluctuations, ensuring that asphalt is transported in a more stable viscosity state, thereby optimizing the efficiency and quality of the entire asphalt heating and transportation process.

[0108] Preferably, the adjustment amount of the heat transfer oil temperature is calculated using the following formula:

[0109]

[0110] in, This indicates the adjustment amount of the heat transfer oil temperature at the current moment. Indicates the predicted viscosity deviation. This represents the rate of change in viscosity. Indicates dynamic temperature difference. This represents the proportionality coefficient (unit: ℃ / Pa·s). This represents the differential coefficient (unit: °C·s / Pa·s). Indicates the feedforward coefficient;

[0111] The current setpoint for the heat transfer oil temperature is updated using the following formula:

[0112]

[0113] in, This indicates the current setpoint for the heat transfer oil. This indicates the amount of heat transfer oil temperature adjustment at the current moment. This indicates the setpoint temperature of the heat transfer oil at the previous moment.

[0114] Among them, the adjustment amount of heat transfer oil temperature This refers to the incremental or incremental adjustment the system needs to make to the heat transfer oil temperature setpoint at the current moment. It represents the specific control action calculated by the control algorithm based on various input signals, aiming to correct asphalt viscosity deviation and maintain its stability. This adjustment can be positive (increasing temperature) or negative (decreasing temperature), and its magnitude directly affects the response speed and accuracy of the heating system. (Predicting viscosity deviation) This refers to the deviation between the predicted future asphalt viscosity and the reference viscosity, taking into account the system response delay time. As a primary input to the control algorithm, it reflects the potential degree of viscosity deviation in the future. By introducing this prediction deviation, the control system can react to potential viscosity changes in advance, rather than simply responding to current deviations with a lag. Viscosity change rate This refers to the rate at which the apparent viscosity of asphalt changes over time. As another important input to the control algorithm, it provides information on the trend of viscosity change. For example, if the viscosity is rising rapidly, even if the current deviation is small, the system should take more aggressive measures to suppress this trend. Dynamic temperature difference. This refers to the difference between the average temperature of the spiral blades and the average temperature of the asphalt. As a feedforward input to the control algorithm, it reflects the efficiency of heat exchange within the spiral conveyor and the direct heating condition of the asphalt. A large dynamic temperature difference may indicate insufficient or excessive heat transfer, requiring corresponding adjustments to the heat transfer oil temperature to maintain the ideal state of the asphalt. Proportional coefficient. It is a parameter in the control algorithm used to measure the strength of the response to predicted viscosity deviation; a larger value indicates a stronger response. A higher value means the system is more sensitive to prediction bias and can adjust more accordingly; a smaller value means the system is more responsive to prediction bias and can adjust more accordingly. The value makes the system response smoother; its function is to provide control proportional to the magnitude of the deviation, so as to quickly eliminate the deviation. It can be determined through expert experience assignment, experimental calibration, or fitting of historical data. Differential coefficients It is a parameter in the control algorithm used to measure the strength of the response to the rate of viscosity change. It enables the system to make predictive adjustments based on the trend of viscosity change, thereby suppressing the rate of viscosity change. A larger [response rate]... The value helps reduce overshoot and oscillations, improving system stability. Feedforward coefficient This is a parameter in the control algorithm used to measure the strength of the response to dynamic temperature differences. It allows the system to pre-compensate for external disturbances (such as changes in heat exchange efficiency) without waiting for viscosity deviations to occur before correction. Through feedforward control, the system can more proactively respond to known or measurable disturbances, improving the real-time performance and accuracy of control. The current setpoint for the heat transfer oil temperature. This refers to the target temperature that the heating system needs to adjust the heat transfer oil to at the current moment. It is obtained by adding the setpoint from the previous moment to the currently calculated adjustment amount. The heat transfer oil temperature setpoint from the previous moment... This refers to the setpoint of the heat transfer oil temperature in the immediately preceding sampling or control cycle. It serves as the benchmark for updating the current setpoint, reflecting the iterative and continuous nature of the control process.

[0115] This application proposes a composite heat transfer oil temperature adjustment strategy by combining predicted viscosity deviation, viscosity change rate, and dynamic temperature difference. Specifically, the system first utilizes the predicted viscosity deviation obtained in previous steps, which already accounts for the response delay during asphalt transportation, enabling the control system to predict future viscosity conditions. Simultaneously, the viscosity change rate provides trend information on asphalt viscosity changes, allowing the system to not only correct current and predicted deviations but also suppress rapid accumulation of deviations. Furthermore, the dynamic temperature difference, as a feedforward signal, directly reflects the heat exchange status between the helical blades and the asphalt, allowing the system to compensate for fluctuations in heat transfer efficiency before significant changes in actual viscosity occur. These three key pieces of information—predicted viscosity deviation, viscosity change rate, and dynamic temperature difference—are weighted using proportional, derivative, and feedforward coefficients, respectively, to jointly calculate the adjustment amount for the heat transfer oil temperature at the current moment. The proportional term primarily eliminates prediction deviations, the derivative term suppresses the rate of viscosity change, and the feedforward term counteracts measurable disturbances. This control logic, combining prediction, derivative, and feedforward, ensures that the adjustment amount for the heat transfer oil temperature comprehensively and accurately reflects the requirements for asphalt viscosity control. Finally, the calculated adjustment is added to the previous heat transfer oil temperature setpoint to update the current heat transfer oil temperature setpoint. Through this iterative update mechanism, the heating control system can continuously and dynamically adjust the heat transfer oil temperature to precisely maintain the asphalt viscosity within the target range. This method not only responds quickly to viscosity deviations but also effectively addresses inherent system delays and external disturbances, significantly improving the stability and control accuracy of the asphalt heating process.

[0116] As a specific implementation, the above-mentioned process of calculating the adjustment amount and updating the setpoint of the heat transfer oil temperature can be implemented by an embedded controller or an industrial PC. This controller can be configured with multiple analog input ports to receive data from sensors, such as screw torque, screw speed, inlet temperature, outlet temperature, and multiple temperature measurement points distributed along the screw blades. The software module running inside the controller periodically performs steps such as data acquisition, viscosity calculation, temperature difference calculation, response delay time determination, predicted viscosity deviation calculation, and viscosity change rate calculation. After obtaining the predicted viscosity deviation, viscosity change rate, and dynamic temperature difference, the controller will adjust the settings according to a preset proportional coefficient. Differential coefficients and feedforward coefficients The adjustment amount of the heat transfer oil temperature can be calculated using the above formula. These coefficients can be optimized and tuned through expert experience assignment, offline simulation, system identification, or online adaptive algorithms to adapt to the needs of different asphalt types and working conditions. For example, a more aggressive approach can be adopted when the system starts up or when working conditions change significantly. and The value is adjusted to speed up the response; when the system is running stably, the coefficient can be appropriately reduced to improve control smoothness. Subsequently, the controller will calculate... Compared with the previous stored setting value of the heat transfer oil temperature Add them together to get the new current setpoint for the heat transfer oil temperature. This new setpoint is output via a digital-to-analog converter (DAC) and sent to the actuators of the heat transfer oil heating system (e.g., solid-state relays regulating heater power or electric valves regulating heat transfer oil flow), thereby achieving precise control of the heat transfer oil temperature. The entire process can be executed cyclically at a preset sampling period (e.g., once per second or every few seconds), ensuring real-time, continuous control of the asphalt viscosity.

[0117] Through the above technical solution, this application effectively solves the problem of how to transform complex predictive information into accurate, stable, and responsive heating control commands during asphalt spiral conveying. Traditional control methods often adjust based solely on current deviations, making them susceptible to inherent system delays, leading to control lag, viscosity fluctuations, and even overshoot. This application introduces predicted viscosity deviations, enabling the control system to anticipate future trends in asphalt viscosity and take corrective measures before the deviation actually occurs. Combined with the derivative action of the viscosity change rate, the system effectively suppresses rapid viscosity changes and avoids drastic fluctuations. Furthermore, the feedforward compensation mechanism for dynamic temperature differences allows the system to proactively respond to external disturbances in heat exchange efficiency, further improving the real-time performance and anti-interference capabilities of the control. This comprehensive control strategy significantly improves the accuracy and stability of heat transfer oil temperature control, ensuring that asphalt remains within the ideal viscosity range during spiral conveying, thereby improving feeding efficiency and product quality while reducing energy consumption.

[0118] A spiral feeding device for asphalt includes a spiral feeder and adopts the above-mentioned spiral feeding method for asphalt. The spiral feeder is a hollow blade or jacket structure, and heat transfer oil is circulated inside the blade.

[0119] It should be noted that, in this document, relational 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 such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus.

[0120] 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 method for spiral feeding of asphalt, characterized in that, include: Data during the operation of the screw conveyor is collected in real time. The data includes at least the screw torque, screw speed, inlet temperature, outlet temperature, multiple temperature measurement points distributed along the screw blades, and the set value of the heat transfer oil temperature at the previous moment. The apparent viscosity of asphalt is obtained based on the screw torque and screw speed, and the reference viscosity is obtained based on the outlet temperature, thereby determining the current viscosity deviation; The dynamic temperature difference between the spiral blade and the asphalt is obtained based on the temperature measurement points of the blade and the temperature of the inlet and outlet. The response delay time of asphalt viscosity to changes in heat transfer oil temperature is determined based on the current screw speed, and the predicted viscosity deviation after the response delay time is predicted in combination with the current viscosity change rate. Based on the predicted viscosity deviation, the current viscosity change rate, and the dynamic temperature difference, the adjustment amount of the heat transfer oil temperature is obtained, and the current heat transfer oil temperature setpoint is updated accordingly to perform heating control. The apparent viscosity of the asphalt is calculated using the following formula: in, Indicates time The apparent viscosity of asphalt, Indicates time The helical torque, Indicates time The rotational speed of the helix Represents the geometric constants of the screw conveyor; The reference viscosity is calculated using the following formula: in, Indicates time The reference viscosity of the asphalt at the discharge port. This represents the theoretical minimum viscosity of asphalt. Represents the temperature constant of the material. Indicates time The temperature at the discharge port.

2. The spiral feeding method for asphalt according to claim 1, characterized in that, The current viscosity deviation is obtained by the following formula: in, Indicates the current viscosity deviation. Indicates time The apparent viscosity of asphalt, Indicates time The reference viscosity of the asphalt at the discharge port.

3. The spiral feeding method for asphalt according to claim 1, characterized in that, The dynamic temperature difference is obtained through the following steps: Obtain the average blade temperature and average temperature of asphalt The dynamic temperature difference is obtained based on the average blade temperature and the average asphalt temperature, specifically: ,in, Indicates the number of blade temperature sensors. Indicates the first The measured values ​​of each blade temperature sensor at time 10:

00. Indicates the inlet temperature. This indicates the temperature at the discharge port.

4. The spiral feeding method for asphalt according to claim 1, characterized in that, The response delay time is obtained through the following steps: The axial movement speed of the asphalt is obtained based on the current helical rotation speed and the pitch of the helical blades, specifically: in, Indicates the axial movement speed of the asphalt. Indicates the current screw speed. Indicates the pitch of the helical blade; The response delay time is obtained based on the axial movement speed of the asphalt, the total length of the screw conveyor, and the inherent delay time of heat conduction. Specifically: in, Indicates the response delay time. This indicates the total length of the screw conveyor. Indicates the axial movement speed of the asphalt. This represents the inherent delay time of heat conduction.

5. The spiral feeding method for asphalt according to claim 1, characterized in that, The viscosity deviation after the response delay time is obtained by the following formula: in, This indicates the deviation in predicted viscosity after the response delay time. Indicates the response delay time. This represents the rate of change in viscosity. Indicates the current viscosity deviation; The viscosity change rate is approximately calculated using the difference method: in, This represents the rate of change in viscosity. This represents the apparent viscosity at the current moment. This represents the apparent viscosity at the previous sampling time. Indicates the sampling time interval.

6. The spiral feeding method for asphalt according to claim 1, characterized in that, The adjustment amount for the heat transfer oil temperature is calculated using the following formula: in, This indicates the adjustment amount of the heat transfer oil temperature at the current moment. Indicates the predicted viscosity deviation. This represents the rate of change in viscosity. Indicates dynamic temperature difference. This represents the proportionality coefficient. Denotes the differential coefficient. This represents the feedforward coefficient.

7. The spiral feeding method for asphalt according to claim 1, characterized in that, The current setpoint for the heat transfer oil temperature is updated using the following formula: in, This indicates the current setpoint for the heat transfer oil. This indicates the amount of heat transfer oil temperature adjustment at the current moment. This indicates the setpoint temperature of the heat transfer oil at the previous moment.

8. A screw conveyor for asphalt, comprising a screw conveyor, characterized in that, The asphalt feeding method according to any one of claims 1-7 is adopted, wherein the screw feeder is a hollow blade or jacket structure, and the blade is filled with heat transfer oil.

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