Method for temperature control in lubricating oil production

Abstract

The application provides a temperature control method in lubricating oil production, and relates to the technical field of lubricating oil processing and industrial automatic control, and comprises the following steps: obtaining the real-time temperature of a blending kettle, adjusting the medium flow rate entering a heating jacket according to the deviation amount from the set temperature; extracting the stirring motor current fluctuation amplitude of multiple sampling periods in the base oil heating stage, controlling the medium flow rate to be intermittently pulsed when in the high oscillation interval, and restoring the continuous supply when in the stable interval; maintaining the medium flow rate at the current value during the additive injection stage of the blending kettle, and synchronously obtaining the real-time running load of the motor, dynamically adjusting the additive injection flow rate based on the real-time running load, so that the additive injection flow rate and the running load are negatively correlated, and the mechanical shear heat is neutralized by the cold content of the additive. The application prevents the base oil from being damaged and the material from being condensed and caked, and guarantees the stability of the process temperature control.

Description

Technical Field

[0001] This invention relates to the field of lubricating oil processing and industrial automation control technology, and in particular to a temperature control method in lubricating oil production. Background Technology

[0002] Currently, the production process of lubricating oil usually requires heating and blending base oils with various functional additives in a blending tank.

[0003] In the initial stage of heating the base oil, the overall physical viscosity of the oil is generally high and its fluidity is relatively weak. At this time, the heat transfer inside the blending vessel mainly relies on the conduction from the metal vessel wall to the interior of the fluid. The heat energy continuously input by the external heating jacket tends to accumulate locally in the area near the edge of the vessel, while the overall temperature rise of the main oil in the center of the vessel will be slower due to the relatively slow thermal convection circulation process.

[0004] As the processing technology progresses to the additive injection stage, when additives at room temperature enter the high-temperature base oil system, the contact and fusion of multi-component fluids with different physical phases can lead to an increase in local viscous resistance. The stirring mechanism releases corresponding mechanical frictional heat when overcoming these high rheological resistances and performing forced mixing. Under conventional control logic, it is difficult to simultaneously balance the transient shear heat generation and conduction temperature difference within the fluid. When dealing with these high-load conditions, this can easily induce localized condensation and agglomeration of cold-state additives, thus interfering with the homogeneous dispersion of additives in the bulk oil and also causing an objective lag in the temperature closed-loop feedback of the blending equipment. Summary of the Invention

[0005] The purpose of this invention is to provide a temperature control method in lubricant production, in order to solve the technical problem that existing temperature control methods are unable to take into account both the uneven distribution of local heat field and the physical agglomeration tendency of materials when dealing with the limited conduction of high viscosity base oil and the mechanical heat generated by the mixing of multiple components. This leads to a lag in temperature regulation and affects the final homogeneous dispersion of the fluid.

[0006] This invention provides a temperature control method in lubricating oil production, comprising:

[0007] The real-time temperature inside the lubricating oil mixing vessel is obtained, and the deviation is obtained by comparing the real-time temperature with the set temperature. The flow rate of the medium entering the heating jacket of the lubricating oil mixing vessel is adjusted according to the deviation.

[0008] During the base oil heating stage, the real-time drive current of the stirring motor configured in the lubricating oil blending vessel is collected, and the current fluctuation amplitude within multiple consecutive sampling cycles is extracted.

[0009] When the current fluctuation amplitude is in the high-level oscillation range, it is determined that the base oil is in a state of blocked thermal convection. The medium flow rate is controlled to present an intermittent pulse supply to reduce the accumulation of heat on the wall and prevent the oil from coking.

[0010] When the current fluctuation amplitude is within a stable range, the medium flow rate is controlled to resume continuous supply;

[0011] During the stage of injecting additives into the lubricating oil mixing vessel, the flow rate of the medium is maintained at the current value, and the real-time operating load of the stirring motor is obtained simultaneously.

[0012] The injection flow rate of the additive is dynamically adjusted based on the real-time operating load, so that the injection flow rate is negatively correlated with the real-time operating load. The cooling capacity of the additive is used to effectively neutralize the mechanical shear heat until the additive injection is completed and the real-time temperature reaches the set temperature.

[0013] Optionally, the real-time temperature inside the lubricating oil mixing vessel can be obtained, including:

[0014] Simultaneously collect the boundary layer temperature close to the inner wall of the lubricating oil mixing vessel and the main body temperature close to the central stirring shaft;

[0015] The radial temperature difference is obtained by comparing the boundary layer temperature with the body region temperature.

[0016] When the radial temperature difference exceeds the preset heat transfer safety threshold and the current fluctuation amplitude does not reach the high-level oscillation range, the boundary layer temperature is used as the real-time temperature to participate in the step of comparing the real-time temperature with the set temperature to obtain the deviation, thereby reducing the medium flow rate and preventing local overheating of the inner wall surface.

[0017] When the radial temperature difference is within the preset heat transfer safety threshold, the main body temperature is used as the real-time temperature to participate in the step of comparing the real-time temperature with the set temperature to obtain the deviation.

[0018] Optionally, adjusting the flow rate of the medium introduced into the heating jacket according to the deviation includes:

[0019] The heating jacket is equipped with control valves at its inlet and outlet ends.

[0020] When the real-time temperature approaches the set temperature and the deviation is less than the preset first deviation threshold, the opening of the control valve at the liquid inlet end of the heating jacket is kept constant, and the opening of the control valve at the liquid outlet end is dynamically reduced.

[0021] By reducing the opening of the control valve at the drain end, the internal medium retention pressure of the heating jacket is increased, thereby increasing the proportion of heat energy transfer from the medium flow rate to the base oil, thus avoiding mechanical thermal inertia overshoot caused by increasing the opening of the control valve at the inlet end.

[0022] Optionally, before obtaining the real-time temperature inside the lubricating oil mixing vessel, the following steps are also included:

[0023] The initial viscosity of the lubricating oil before it is injected into the mixing vessel is measured.

[0024] Based on the initial oil viscosity assessment, the threshold of heat absorption required to reach the inflection point of flow transition is determined.

[0025] In the initial stage of introducing the medium into the heating jacket, the slope of the medium flow rate increase over time is limited so that the supplied heat matches the absorbed heat threshold, preventing the base oil from hindering heat conduction to the interior in its initial thick agglomerate state.

[0026] Optionally, after comparing the real-time temperature with the set temperature to obtain the deviation, the method further includes:

[0027] When the difference between the real-time temperature and the set temperature is less than the preset advance threshold, the action of inputting new medium into the heating jacket is cut off.

[0028] Obtain the temperature of the stored medium at the drain end of the heating jacket, and compare the stored medium temperature with the current real-time temperature;

[0029] The residual heat stored in the heating jacket is used to complete the end temperature rise, effectively eliminating the temperature overshoot caused by the thermal inertia of the metal vessel structure.

[0030] Optionally, the current fluctuation amplitude over multiple consecutive sampling periods can be extracted, including:

[0031] Record the time span during which the real-time drive current experiences a sudden peak change;

[0032] Compare the time span with the mechanical passage cycle formed by the stirring blades inside the lubricating oil mixing vessel sweeping over the fixed baffle inside the lubricating oil mixing vessel;

[0033] If the time span coincides with the mechanical cycle, it is confirmed that the mechanical resistance fluctuation is caused by the impact of high-viscosity agglomerated material on the baffle fixed inside the lubricating oil mixing vessel.

[0034] The range of the envelope formed by the abrupt peaks is captured, and the range of the envelope is used as the current fluctuation amplitude to characterize the degree of internal flow stagnation.

[0035] Optionally, controlling the medium flow rate to be supplied in an intermittent pulse pattern includes:

[0036] During the pulse shutdown period that cuts off the flow of the medium, the residual heat decay slope of the inner wall of the lubricating oil blending vessel is monitored at high frequency;

[0037] When the absolute value of the residual heat decay slope is less than the preset balance threshold, indicating that the heat stored on the inner wall of the lubricating oil mixing vessel has been fully diffused to the surrounding cold oil, a subsequent pulse start command is triggered.

[0038] Using the residual heat attenuation slope as a physical feedback node, the duration of each pulse's off state is dynamically determined, forming an adaptive pulse duty cycle.

[0039] Optionally, the real-time operating load of the stirring motor can be acquired synchronously, including:

[0040] As the additive is continuously injected, the total volume of the injected liquid is accumulated, and the height of the liquid level rise inside the lubricating oil mixing vessel is calculated based on the total volume of the injected liquid.

[0041] The basic physical resistance of the stirring motor due to the increase in immersion area is estimated based on the height of the liquid level rise.

[0042] The effective resistance load caused by the significant change in viscosity of the multi-component fluid is extracted by subtracting the basic physical resistance from the overall load consumed by the stirring motor.

[0043] The effective resistance load is used as the real-time operating load and is negatively correlated with the injection flow rate.

[0044] Optionally, the injection flow rate is negatively correlated with the real-time operating load, including:

[0045] When the real-time operating load increases, it indicates a sharp increase in local viscous resistance, accompanied by a large accumulation of mechanical shear heat.

[0046] At this time, the injection flow rate of the additive is reduced, thereby prolonging the physical residence time of the additive in the high shear region;

[0047] By utilizing the extended physical retention time, the additive, injected at a low flow rate, is sufficiently sheared and dispersed. The accompanying cooling effectively neutralizes the enriched mechanical shear heat, preventing localized agglomeration and clumping of the material induced by rapid, high-flow-rate cold injection.

[0048] Optionally, after the additive injection is completed and the real-time temperature reaches the set temperature, the process further includes:

[0049] Continuously track the fluctuation range of the real-time operating load;

[0050] When the fluctuation range change trajectory tends to be stable and the real-time driving current no longer shows abrupt peaks, it is determined that the additive has reached a homogeneous dispersion state inside the main oil.

[0051] Subsequently, the lockout restriction on the medium flow rate is released, and continuous closed-loop control of the real-time temperature is restored, completing the final constant-temperature homogenization curing of the finished product.

[0052] The present invention has achieved the following beneficial effects:

[0053] The temperature control method for lubricating oil production provided by this invention assesses the internal thermal convection hindrance state of the fluid by collecting the current fluctuation amplitude of the stirring motor during the base oil heating stage, and outputs intermittent pulsed medium supply commands accordingly. This alleviates the excessive accumulation of heat energy on the inner wall of the blending vessel due to conduction limitations, reducing the probability of edge thermal deterioration of the oil under high viscosity conditions. During the additive injection stage, this method establishes a negative correlation mechanism between the additive injection flow rate and the real-time operating load extracted by the stirring motor, dynamically extending the physical residence time of the additive in the high-shear region. It relies on the inherent cold-state heat capacity of the additive at room temperature to directly neutralize the internal shear heat generated by mechanical stirring. The entire control architecture effectively coordinates the external thermal input parameters of the equipment with the rheological impedance characteristics of the materials inside the reactor, reducing condensation caused by cold material aggregation, smoothing thermal field fluctuations during multi-component phase transitions, and facilitating a stable temperature transition and homogeneous dispersion throughout the blending cycle.

[0054] Other features and advantages of the invention will be set forth in the following description, and will be apparent in part from the description, or may be learned by practicing the invention. The objects and other advantages of the invention may be realized and obtained by means of the structures particularly pointed out in the written description and the accompanying drawings.

[0055] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0056] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used in conjunction with embodiments of the invention to explain the invention and do not constitute a limitation thereof. In the drawings:

[0057] Figure 1 This is a structural diagram of the modular composition of the automated control system and field equipment in an embodiment of the present invention;

[0058] Figure 2 This is an overall flowchart of a temperature control method in lubricant production according to an embodiment of the present invention;

[0059] Figure 3This is a flowchart of the logic control for obtaining real-time temperature and determining radial temperature difference in an embodiment of the present invention.

[0060] Figure 4 This is a flowchart illustrating the verification and judgment process for extracting the current fluctuation amplitude in an embodiment of the present invention.

[0061] Figure 5 This is a flowchart illustrating the feedback determination process for controlling intermittent pulse supply in an embodiment of the present invention.

[0062] Figure 6 This is a flowchart illustrating the extraction of effective resistance load and dynamic adjustment of negative correlation control in an embodiment of the present invention. Detailed Implementation

[0063] The preferred embodiments of the present invention will be described below with reference to the accompanying drawings. It should be understood that the preferred embodiments described herein are for illustration and explanation only and are not intended to limit the present invention.

[0064] It should be noted that the temperature control method for lubricating oil production provided in this embodiment is implemented by an automated control system equipped with a processor. This automated control system establishes a communication connection with sensors and actuators at the lubricating oil blending process site. For example... Figure 1 As shown, in the implementation environment, the system is built on an existing industrial-grade programmable logic controller (PLC) to form the underlying execution base. The field temperature sensor uses a standard PT100 platinum resistance thermometer, transmitting physical quantities to the PLC's AI (analog input) card via a 4-20mA standard analog signal. Online rheological measurement uses an insertion-type tuning fork viscometer. The first regulating valve at the inlet end and the second regulating valve at the outlet end of the heating jacket in the actuator are both equipped with electric valve positioners. The PLC polls the spindle inverter in real time via RS485 hardwired connections (such as the Modbus RTU industrial bus protocol) to obtain its feedback data, including the operating current and other underlying register data. This heavy-duty industrial control hardware array, characterized by a physical scan cycle and mechanical motion delay, constitutes the basic constraint environment for executing the underlying control actions such as width setting, amplitude limiting, table lookup, and stepping in this embodiment.

[0065] Based on the above system environment, the overall process is as follows: Figure 2 As shown in the figure, this embodiment provides a temperature control method in lubricant production, which specifically includes the following steps:

[0066] Step S1: Before obtaining the real-time temperature inside the lubricating oil mixing vessel, perform a preliminary measurement of the physical state and a heat supply constraint operation.

[0067] Specifically, before obtaining the real-time temperature inside the lubricating oil blending vessel, the process includes: measuring the initial viscosity of the oil before it is injected into the lubricating oil blending vessel; assessing the heat absorption threshold required to reach the inflection point of the flow regime based on the initial oil viscosity; and limiting the slope of the increase in the flow rate of the medium over time during the initial stage of introducing the medium into the heating jacket, so that the supplied heat matches the heat absorption threshold, and preventing the base oil from hindering the conduction of heat to the interior in its initial thick agglomerate state.

[0068] The control system's underlying storage area contains a pre-set two-dimensional empirical mapping table of initial viscosity and heat absorption extracted from historical feed test data. The system reads the initial oil viscosity value fed back by the online viscometer and uses this value as an index to perform linear interpolation in the mapping table, directly extracting the empirical threshold for the heat absorption required for the current grade of oil. The construction of the two-dimensional empirical mapping table does not require complex mathematical modeling; its physical calibration process is as follows: Under no-load cold conditions, multiple groups of conventional grade base oils with different initial viscosities are selected for heating test runs; the total amount of heat source medium consumed by the heating jacket is recorded when each group of base oils reaches the inflection point of the flow transition (i.e., the corresponding temperature point when the spindle operating current drops from violent fluctuations and remains stable); the above discrete test data are directly linearly interpolated and connected with viscosity as the horizontal axis and cumulative heat consumption as the vertical axis to generate a workshop-level two-dimensional quick reference table.

[0069] In the initial stage of introducing the medium into the heating jacket, the control system calls the ramp function module of the underlying PLC. Based on the extracted heat absorption threshold, the system sets the step increment limit parameter of the first regulating valve opening, for example, forcibly setting the maximum percentage increase of the valve opening per minute to 3%. This percentage value is directly taken from the intersection of the minimum stable stroke dead zone of the field control valve and the maximum allowable water hammer pressure limit of the heating pipeline network, to ensure that mechanical execution does not oscillate. This physical timing constraint forcibly slows down the initial heat source input rate, making it match the slow actual heat conduction rhythm of the oil under high viscosity, and using mechanical action limitation to avoid local coking of the metal vessel wall caused by the instantaneous influx of large flow of heat energy. The specific method for determining the variable slope is an empirical test method: when the equipment is run at room temperature with an empty vessel, the reference time required to safely heat the base oil to the inflection point of the flow state at a small stable opening is recorded; the effective mechanical opening range of the first regulating valve is divided by this reference time, and the resulting fixed quotient is used as the constant variable slope under automatic control.

[0070] Step S2: Obtain the real-time temperature inside the lubricating oil mixing vessel, compare the real-time temperature with the set temperature to obtain the deviation, and adjust the flow rate of the medium entering the heating jacket of the lubricating oil mixing vessel according to the deviation.

[0071] Among them, such as Figure 3As shown, the real-time temperature inside the lubricating oil blending vessel is obtained, including: simultaneously acquiring the boundary layer temperature close to the inner wall of the vessel and the main body temperature close to the central stirring shaft; specifically, from the perspective of equipment hardware installation: the temperature probe for the boundary layer temperature is fixedly inserted to a radial depth of 3 to 5 cm from the inner metal wall of the vessel; the temperature probe for the main body temperature is vertically installed at half the theoretical radius of the vessel to avoid the blind zone of mechanically forced eddies around the central stirring shaft. The radial temperature difference is obtained by comparing the boundary layer temperature and the main body temperature.

[0072] When the radial temperature difference exceeds the preset heat transfer safety threshold and the current fluctuation amplitude extracted by the system does not reach the high-level oscillation range, the boundary layer temperature is used as the real-time temperature to participate in the step of comparing the real-time temperature with the set temperature to obtain the deviation, thereby reducing the medium flow rate and preventing local overheating of the inner wall surface.

[0073] When the radial temperature difference is within the preset heat transfer safety threshold, the main body temperature is used as the real-time temperature to participate in the step of comparing the real-time temperature with the set temperature to obtain the deviation.

[0074] The control system synchronously reads the boundary layer temperature close to the inner wall and the main body temperature of the central stirring zone according to the PLC's scanning cycle, and performs arithmetic subtraction to obtain the real-time radial temperature difference. The preset heat transfer safety threshold directly calls the historical test data of the anti-coking critical temperature difference pre-stored in the process formula library (e.g., a setting of 15℃ for solidification). The specific method for determining the heat transfer safety threshold is as follows: Consult the Material Safety Data Sheet (MSDS) of the base oil to be processed, extract its physical local thermal decomposition temperature, multiply the difference between this thermal decomposition temperature and the process target temperature by an industrial engineering safety factor of 0.8, and the result is the heat transfer safety threshold. When the bottom-level comparison command determines that the measured radial temperature difference unidirectionally exceeds this 15℃ empirical threshold, and the parallel monitored current does not trigger a high-level clumping alarm, the system determines that actual heat transfer hindrance has occurred in the boundary layer.

[0075] At this point, the control system triggers typical DCS override control logic, forcibly redirecting the PID temperature control module's measured value (PV value) feedback channel from the main body temperature measurement point to the boundary layer temperature measurement point via an internal multiplexer command. Because the system instantly captures the sudden increase in boundary layer temperature, the temperature deviation calculated by the PID algorithm quickly converges or even turns negative, directly outputting a command to reduce the analog quantity, driving the first regulating valve to automatically reduce its opening. Once the heat from the inner wall gradually penetrates towards the center and the radial temperature difference naturally decreases to below 15°C, the system resets the address mapping, resuming conventional closed-loop tracking based on the main body temperature.

[0076] Step S3: During the base oil heating stage, the real-time drive current of the stirring motor configured in the lubricating oil blending vessel is collected, and the current fluctuation amplitude within multiple consecutive sampling cycles is extracted.

[0077] Specifically, such as Figure 4 As shown, the current fluctuation amplitude is extracted over multiple consecutive sampling periods, including: recording the time span of the sudden peak of the real-time driving current; comparing the time span with the mechanical passage cycle formed by the stirring blade inside the lubricating oil mixing vessel passing over the fixed baffle inside the lubricating oil mixing vessel; if the time span coincides with the mechanical passage cycle, it is confirmed as a mechanical resistance fluctuation caused by the impact of high-viscosity agglomerated material on the fixed baffle inside the lubricating oil mixing vessel; capturing the envelope range formed by the sudden peak, and using the envelope range as the current fluctuation amplitude characterizing the degree of internal flow stagnation.

[0078] The control system continuously monitors the drive current of the stirring motor using a current transmitter in the main circuit. When the current value exceeds the average baseline for stable operation and forms a sudden peak, the system triggers an internal high-speed timer to record the absolute time difference between two consecutive peak current values, which is recorded as the time span. Simultaneously, the control system reads the current operating frequency of the main shaft inverter, and, combined with the gear ratio of the reducer fixed on the equipment nameplate, the known number of stirring blades, and the number of fixed baffles evenly distributed on the inner wall of the vessel, calculates the theoretical physical time it takes for a single blade to sequentially pass over two adjacent baffles using basic multiplication and division arithmetic, and sets this as the mechanical passage cycle.

[0079] The system sets a fixed-width tolerance band for engineering timers (e.g., ±0.5 seconds) in its underlying logic to filter out false peaks caused by mechanical speed fluctuations or transient low-frequency disturbances in the fluid. If the recorded time span falls within this tolerance band, the control system confirms from the spatial operating rhythm of the physical equipment that the current mutation in this fixed period originates from the physical impedance generated when agglomerated high-viscosity fluid material is forcibly pushed over a rigid baffle. After verification, to eliminate interference from harmonics in the power grid and high-frequency mechanical vibrations, the system directly calls the first-order low-pass filter function built into the analog input channel of the underlying PLC and sets a fixed hardware sampling period of 100 milliseconds to obtain the smoothed effective current signal. Subsequently, the system captures the highest peak of the current within this mutation period and subtracts it from the adjacent attenuation trough to obtain the envelope range, which is then assigned to the current fluctuation amplitude data block.

[0080] Step S4: When the current fluctuation amplitude is in the high-level oscillation range, it is determined that the base oil is in a state of blocked thermal convection. The medium flow rate is controlled to be supplied in an intermittent pulse manner to reduce the accumulation of heat on the wall surface and prevent the oil from coking. When the current fluctuation amplitude is in the stable range, the medium flow rate is controlled to resume continuous supply.

[0081] Among them, such as Figure 5 As shown, controlling the medium flow rate to present an intermittent pulsed supply includes: during the pulse shutdown period of cutting off the medium flow rate, high-frequency monitoring of the residual heat decay slope of the inner wall of the lubricating oil blending vessel; when the absolute value of the residual heat decay slope is less than a preset balance threshold, indicating that the heat stored on the inner wall of the lubricating oil blending vessel has been fully diffused to the surrounding cold oil, triggering a subsequent pulse start command; using the residual heat decay slope as a physical feedback node, dynamically determining the duration of each pulse shutdown state to form an adaptive pulse duty cycle.

[0082] During the empty reactor and ambient temperature base oil trial run in the equipment commissioning phase, the average current range under stable conditions is extracted as the baseline amplitude. In production control, the lower limit of the high-level oscillation range is rigidly set to 1.8 times the baseline amplitude, and the upper limit of the stable range is set to 1.2 times the baseline amplitude. These multiples are directly derived from industrial motor operating standards: 1.2 times aligns with the long-term overload warning coefficient of the stirring motor, indicating that the material begins to exhibit high viscosity resistance; 1.8 times aligns with the feedforward defense line of the instantaneous hardware protection trip threshold of the frequency converter, indicating that if the medium is not cut off at this time, it will trigger a hard shutdown protection of the equipment. When the measured current fluctuation amplitude exceeds the lower limit of 1.8 times, the control system takes over the output of the first regulating valve and activates the time relay pulse intervention logic: after issuing a full-scale opening command and holding it for a set number of seconds, it immediately issues a full-close command to physically cut off the flow. The method for setting the set number of seconds is as follows: the basic replacement time is obtained by dividing the physical volume inside the heating jacket by the rated volumetric flow rate of the medium circulation pump, and this basic replacement time is used as the set number of seconds. This physical setting ensures that a single activation pulse completes a full space replacement of the old medium inside the jacket, avoiding excessive injection that could lead to excessive heat buildup.

[0083] During the valve shut-off pulse period, the system captures the sampled value of the inner wall temperature sensor every 10 seconds and subtracts it from the previous sampled value to obtain the temperature drop rate as the residual heat attenuation slope. When the temperature drop rate within 10 seconds is less than 0.1℃ for three consecutive monitoring periods (i.e., the absolute value of the residual heat attenuation slope is less than the preset equilibrium threshold), it indicates from a heat transfer perspective that the residual heat accumulated on the metal vessel wall has been absorbed by the surrounding cold oil, and the interface heat transfer has reached dynamic equilibrium. The physical basis for setting this equilibrium threshold is that 0.1℃ is exactly equal to the minimum engineering measurement accuracy limit of the PT100 temperature transmitter and the background noise dead zone of the digital filtering system. When the temperature drop rate falls into the error range that the transmitter cannot distinguish, it is confirmed from a hardware physical perspective that the release of residual heat has tended to stagnate. The system directly uses this physical characteristic of the temperature drop tending to stabilize as the hardware trigger condition for the state machine, ending the shutdown waiting state and releasing the next round of opening pulses. Therefore, the pulse shutdown duration is adaptively determined by the actual heat absorption and cooling performance of the material until the current fluctuation drops to within 1.2 times the reference amplitude, at which point the system automatically exits the pulse intervention mode.

[0084] Step S5, adjusting the flow rate of the medium entering the heating jacket according to the deviation, includes: the inlet and outlet ends of the heating jacket are respectively provided with control valves; when the real-time temperature approaches the set temperature and the deviation is less than a preset first deviation threshold, the opening of the control valve at the inlet end of the heating jacket is kept constant, and the opening of the control valve at the outlet end is dynamically reduced; by reducing the opening of the control valve at the outlet end, the internal medium retention pressure of the heating jacket is increased, and the proportion of heat energy transfer from the medium flow rate to the base oil is increased, so as to avoid mechanical thermal inertia overshoot caused by increasing the opening of the control valve at the inlet end.

[0085] When the temperature deviation calculated by the PID controller drops to the buffer zone calibrated by the process (e.g., within 3°C below the target value, i.e., less than the preset first deviation threshold, which is a fixed engineering constant based on historical production data from the workshop, typically ranging from 2°C to 5°C, and its specific value is directly taken from the average temperature recorded by the same specification blending equipment during normal heating full-load operation, due to mechanical thermal inertia and natural sliding overshoot), the system automatically locks the current mechanical opening output of the first regulating valve at the inlet end. Simultaneously, the control system activates the typical split-range control logic at the underlying level to take over the second regulating valve at the outlet end. The system linearly maps this remaining 3°C temperature difference to the closing stroke of the second regulating valve, driving the outlet valve opening to gradually decrease. The specific physical boundary conditions for this linear mapping are: when the temperature difference equals the first deviation threshold (e.g., 3°C), the outlet valve maintains the maximum process opening set by the basic parameters (e.g., 100% fully open); when the temperature difference approaches 0°C, the outlet valve opening correspondingly shrinks to the minimum safe pressure relief opening allowed by the field pipeline network (e.g., 15%). The system performs a proportional conversion output between these two physical extremes to avoid completely closing the drain valve and causing water hammer pressure buildup in the pipeline. This mechanical-physical throttling directly increases the mechanical back pressure of the return water network inside the heating jacket, prolonging the physical residence time of the high-temperature medium on the heat transfer wall, thereby maximizing the release rate of stored heat energy.

[0086] As the temperature continues to rise, when the difference between the real-time temperature and the set temperature is less than the preset advance threshold (e.g., only 1.0°C away from the target value), the system issues a high-priority hardware full-close command to the first regulating valve, cutting off the input of new medium to the heating jacket (i.e., forcibly cutting off the external medium pipeline). This advance parameter is directly derived from the extreme value of the natural sliding temperature rise during the initial no-load water test run of the equipment. Considering the thermodynamic differences between the production material and the water test run medium, the system performs material heat capacity correction through ratio calculation: referring to the basic material manual, the specific heat capacity constant of water is divided by the specific heat capacity constant of the current lubricating oil base oil to obtain an amplification factor. The extreme value of the natural sliding temperature rise during the heat cut-off is multiplied by this amplification factor to directly calculate and convert it into the actual advance threshold of the current oil, thereby eliminating the thermal inertia conversion error caused by the change of medium. At this time, the system only maintains stirring operation, relying on the physical sensible heat of the physically sealed medium inside the jacket and the heat storage of the heavy metal vessel for natural heat conduction and sliding transition. This interruption method, based on the intrinsic thermal inertia calibration of the equipment, avoids the occurrence of overshoot and temperature overshoot at the end point from the energy input source.

[0087] The control system sends a safety-level shutdown command to the first regulating valve, cutting off the medium pipeline circuit. The system reads the value of the resistance temperature detector (RTD) installed at the drain end to obtain the temperature of the stored medium at the drain end of the heating jacket, and compares the stored medium temperature with the current real-time temperature. If the system determines that the temperature is higher than the real-time temperature, it maintains the normal operation of the stirring mechanism, relying on the residual heat carried by the medium in the sealed jacket and the heat stored in the metal container structure to achieve smooth heat conduction and penetration. The residual heat stored in the medium inside the heating jacket is used to complete the end temperature rise, effectively eliminating the temperature overshoot caused by the thermal inertia of the metal vessel structure, and achieving the target temperature set by the process.

[0088] In step S6, during the stage of injecting additives into the lubricating oil mixing vessel, the flow rate of the medium is maintained at the current value, and the real-time operating load of the stirring motor is acquired simultaneously.

[0089] Specifically, the control system locks the first and second regulating valves at their current mechanical opening positions, establishing a static heating boundary environment with a constant physical flow state to prevent dynamic changes in external regulating variables from interfering with the state monitoring of the material phase change mixing stage.

[0090] Among them, such as Figure 6 As shown, the real-time operating load of the stirring motor is simultaneously acquired, including: accumulating the total volume of injected liquid as the additive is continuously injected, and calculating the rise height of the liquid level inside the lubricating oil mixing vessel based on the total volume of injected liquid; estimating the basic physical resistance of the stirring motor due to the increase in immersion area based on the rise height of the liquid level; deducting the basic physical resistance from the overall load consumed by the stirring motor, and extracting the effective resistance load caused by the significant change in viscosity of the multi-component fluid; and using the effective resistance load as the real-time operating load to perform the negative correlation with the injection flow rate.

[0091] During continuous additive injection, the control system accumulates and integrates the pulse signals fed back from the mass flow meter in the injection pipeline to obtain the total volume of injected liquid. Based on the cross-sectional area constant inside the mixing vessel, it performs division to calculate the actual liquid level rise height within the vessel. The system's underlying layer pre-loads empirical line graphs of liquid level versus no-load current measured during the equipment's clean water and standard base oil joint commissioning. These line graphs visually reflect the increase in background power consumption caused by the rise in liquid level and the increased frictional area of ​​the impeller immersion. The steps for mapping these liquid level versus no-load current empirical line graphs are as follows: During the clean water or standard base oil commissioning phase before equipment production in the workshop, liquid is injected into the mixing vessel in fixed liquid level increments (e.g., every 0.5 meters); after the liquid level is completely calm at each injection stage, the steady-state operating current value output by the spindle frequency converter is recorded; the data from each liquid level node are sequentially connected as a physical reference for querying the mechanical background power consumption during the production phase.

[0092] The system consults the line graph based on the measured liquid level rise and directly extracts the corresponding predicted background current value as the estimated basic physical resistance. The control unit reads the total operating current of the inverter as the overall load consumption and executes a simple subtraction instruction in each PLC execution cycle to directly deduct the basic physical resistance obtained from the table and the equipment's rated idling current from the total operating current. This filtering calculation effectively filters out the steady-state load rise caused by the expansion of the liquid's geometric volume. The extracted net current value is the effective resistance load, which reflects the physical impedance caused by the local phase contraction and increased viscous resistance when the cold additive is mixed with the high-temperature system. It is then assigned a value and pushed into the register to participate in subsequent closed-loop regulation.

[0093] Step S7: Dynamically adjust the injection flow rate of the additive based on the real-time operating load, so that the injection flow rate is negatively correlated with the real-time operating load, and use the cooling capacity of the additive to neutralize the mechanical shear heat until the additive injection is completed and the real-time temperature reaches the set temperature.

[0094] The method of making the injection flow rate negatively correlated with the real-time operating load includes: when the real-time operating load increases, it indicates a sharp increase in local viscous resistance and a large accumulation of mechanical shear heat; at this time, the injection flow rate of the additive is reduced to prolong the physical residence time of the additive in the high-shear region; by utilizing the prolonged physical residence time, the additive injected at a low flow rate is fully sheared and dispersed, and the accompanying cooling effectively neutralizes the accumulated mechanical shear heat, preventing the local coagulation and agglomeration of materials induced by rapid cold injection at a high flow rate.

[0095] When cold additives are poured into a high-temperature base oil system, the temperature difference at the interface can cause a sudden phase contraction, forming highly viscous agglomerates. This leads to an increase in the effective resistance load at the bottom layer, indicating that a large amount of mechanical work is being converted into localized internal friction shear heat. To address this, the control system presets a maximum load current limit to ensure normal material dispersion. This limit is based on the equipment's hardware nameplate parameters: the rated operating current specified on the agitator motor's nameplate is subtracted from the basic physical resistance calculated in step S6, and 80% of the difference is set as the maximum limit. This physical setting fully utilizes the maximum allowable work capacity of the agitator motor while reserving a 20% safety margin to prevent hardware tripping due to sudden material lock-up. When the real-time effective resistance load exceeds this limit, the system activates an inverse proportional step-down frequency reduction logic to take over the additive injection pump.

[0096] The system is configured with a fixed frequency reduction step factor (e.g., for every 5% increase in the effective resistance load beyond the rated current of the stirring motor, the operating frequency command sent to the injection pump inverter is forcibly reduced by one control level of physical bandwidth). This frequency reduction step factor is based on the coarse-grained robust control setting of the on-site inverter: the full-range frequency modulation bandwidth of the injection pump inverter is obtained and divided into 10 fixed control levels; the effective resistance load exceeding the process upper limit is used as the trigger condition, and for every 5% increase in the effective resistance load beyond the rated current of the stirring motor, the injection pump is instructed to reduce the physical bandwidth of one control level. Through this rigid flow rate reduction action, the instantaneous physical flux of cold additives entering the mixing vessel is stepped down. The smaller supply flow rate allows the small amount of cold additives entering to undergo a longer period of reciprocating physical pulling in the high-shear zone at the impeller tip, thus being fully sheared and dispersed; simultaneously, the room-temperature physical coldness carried by the additive body has ample time to neutralize the heat dissipated by friction in this micro-region. Once the package is broken up and the effective resistance load drops below the upper limit, the system gradually restores the operating flow rate of the injection pump in equal Hertz steps.

[0097] Step S8, after the additive injection is completed and the real-time temperature reaches the set temperature, further includes: continuously tracking the fluctuation range change trajectory of the real-time operating load; when the fluctuation range change trajectory tends to be stable and the real-time drive current no longer shows a sudden peak, it is determined that the additive has reached a homogeneous dispersion state inside the main oil; then the locking restriction on the medium flow rate setting is released, the continuous closed-loop control of the real-time temperature is restored, and the final constant temperature homogeneous curing of the finished product is completed.

[0098] After the fluid injection process is completed, the control system allocates a fixed-length FIFO (First-In-First-Out) data queue in its running memory, for example, covering a continuous 60-second sliding time window, specifically for caching discrete sampled values ​​of the effective resistance load. The fixed sampling period for these discrete sampled values ​​is set to a standard 1 second, meaning that within this 60-second sliding time window, the system consistently maintains 60 valid data samples for continuous range comparison. In each scan cycle, the system performs only the most basic traversal comparison arithmetic: extracting the maximum and minimum values ​​of the data within the time window and calculating their difference to determine the trajectory of the fluctuation range change.

[0099] When the range is monitored to converge to the preset equipment no-load background noise dead zone for 3 consecutive minutes (for example, the range fluctuation is less than 0.5 Amperes, that is, the fluctuation range change trajectory tends to be stable), and the time span monitoring module is checked to find that the rigid impact peak is no longer captured (that is, the real-time drive current no longer shows a sudden peak), it can be confirmed from the physical performance of the stable macroscopic electrical work that the high-viscosity agglomerates have been fully sheared and crushed, and the multi-component phase state has reached a homogeneous dispersion state.

[0100] It should be noted that the above time-frequency domain determination parameters are all derived from the physical measurements and geometric correlations of the workshop equipment: Specifically, the 0.5 ampere dead zone lower limit is the average current difference between mechanical friction and grid harmonics measured and extracted when the mixing vessel is running without liquid and under no-load conditions; the 60-second sliding time window length must cover at least three complete mechanical rotation cycles of the agitator at the lowest process speed; and the 3-minute convergence confirmation time is the macroscopic fluid circulation mixing time calculated by dividing the total volume of the mixing vessel by the theoretical pumping displacement of the agitator blades. These engineering parameters ensure a strong correlation between homogeneous phase determination and the physical spatial capabilities of the specific equipment.

[0101] After confirming homogeneity, the system needs to release the lock restriction on the medium flow rate setting (remove the manual lock on the underlying medium valve). To prevent significant fluctuations in valve opening due to PID integral term accumulation when the control loop switches back to automatic (AUTO) mode, the control system executes an industry-standard bumpless transfer: directly capturing the actual physical mechanical valve position feedback signals (4-20mA corresponding values) of the two regulating valves at this moment and writing them backwards into the initial tracking parameter interface of the PID function block. After completing the forced alignment of the underlying values, the system smoothly switches to full closed-loop mode, resuming continuous closed-loop control of the real-time temperature. At this time, the controller's initial control command smoothly connects to the current physical flow resistance state, relying on small opening pulses to compensate for the natural heat dissipation of the vessel, and the equipment smoothly enters the constant temperature homogenization curing stage of the finished product, completing the final constant temperature homogenization curing of the finished product.

[0102] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. A method for temperature control in lubricant production, characterized in that, include: The real-time temperature inside the lubricating oil mixing vessel is obtained, and the deviation is obtained by comparing the real-time temperature with the set temperature. The flow rate of the medium entering the heating jacket of the lubricating oil mixing vessel is adjusted according to the deviation. During the base oil heating stage, the real-time drive current of the stirring motor configured in the lubricating oil blending vessel is collected, and the current fluctuation amplitude within multiple consecutive sampling cycles is extracted. When the current fluctuation amplitude is in the high-level oscillation range, it is determined that the base oil is in a state of blocked thermal convection. The medium flow rate is controlled to present an intermittent pulse supply to reduce the accumulation of heat on the wall and prevent the oil from coking. When the current fluctuation amplitude is within a stable range, the medium flow rate is controlled to resume continuous supply; During the stage of injecting additives into the lubricating oil mixing vessel, the flow rate of the medium is maintained at the current value, and the real-time operating load of the stirring motor is obtained simultaneously. The injection flow rate of the additive is dynamically adjusted based on the real-time operating load, so that the injection flow rate is negatively correlated with the real-time operating load. The cooling capacity of the additive is used to effectively neutralize the mechanical shear heat until the additive injection is completed and the real-time temperature reaches the set temperature.

2. The temperature control method in lubricating oil production according to claim 1, characterized in that, Obtain the real-time temperature inside the lubricating oil mixing vessel, including: Simultaneously collect the boundary layer temperature close to the inner wall of the lubricating oil mixing vessel and the main body temperature close to the central stirring shaft; The radial temperature difference is obtained by comparing the boundary layer temperature with the body region temperature. When the radial temperature difference exceeds the preset heat transfer safety threshold and the current fluctuation amplitude does not reach the high-level oscillation range, the boundary layer temperature is used as the real-time temperature to participate in the step of comparing the real-time temperature with the set temperature to obtain the deviation, thereby reducing the medium flow rate and preventing local overheating of the inner wall surface. When the radial temperature difference is within the preset heat transfer safety threshold, the main body temperature is used as the real-time temperature to participate in the step of comparing the real-time temperature with the set temperature to obtain the deviation.

3. The temperature control method in lubricating oil production according to claim 1, characterized in that, Adjusting the flow rate of the medium entering the heating jacket according to the aforementioned deviation includes: The heating jacket is equipped with control valves at its inlet and outlet ends. When the real-time temperature approaches the set temperature and the deviation is less than the preset first deviation threshold, the opening of the control valve at the liquid inlet end of the heating jacket is kept constant, and the opening of the control valve at the liquid outlet end is dynamically reduced. By reducing the opening of the control valve at the drain end, the internal medium retention pressure of the heating jacket is increased, thereby increasing the proportion of heat energy transfer from the medium flow rate to the base oil, thus avoiding mechanical thermal inertia overshoot caused by increasing the opening of the control valve at the inlet end.

4. The temperature control method in lubricating oil production according to claim 1, characterized in that, Before obtaining the real-time temperature inside the lubricating oil mixing vessel, the following steps are also included: The initial viscosity of the lubricating oil before it is injected into the mixing vessel is measured. Based on the initial oil viscosity assessment, the threshold of heat absorption required to reach the inflection point of flow transition is determined. In the initial stage of introducing the medium into the heating jacket, the slope of the medium flow rate increase over time is limited so that the supplied heat matches the absorbed heat threshold, preventing the base oil from hindering heat conduction to the interior in its initial thick agglomerate state.

5. The temperature control method in lubricating oil production according to claim 1, characterized in that, After comparing the real-time temperature with the set temperature to obtain the deviation, the method further includes: When the difference between the real-time temperature and the set temperature is less than the preset advance threshold, the action of inputting new medium into the heating jacket is cut off. Obtain the temperature of the stored medium at the drain end of the heating jacket, and compare the stored medium temperature with the current real-time temperature; The residual heat stored in the heating jacket is used to complete the end temperature rise, effectively eliminating the temperature overshoot caused by the thermal inertia of the metal vessel structure.

6. The temperature control method in lubricating oil production according to claim 1, characterized in that, Extract the current fluctuation amplitude over multiple consecutive sampling periods, including: Record the time span during which the real-time drive current experiences a sudden peak change; Compare the time span with the mechanical passage cycle formed by the stirring blades inside the lubricating oil mixing vessel sweeping over the fixed baffle inside the lubricating oil mixing vessel; If the time span coincides with the mechanical cycle, it is confirmed that the mechanical resistance fluctuation is caused by the impact of high-viscosity agglomerated material on the baffle fixed inside the lubricating oil mixing vessel. The range of the envelope formed by the abrupt peaks is captured, and the range of the envelope is used as the current fluctuation amplitude to characterize the degree of internal flow stagnation.

7. The temperature control method in lubricating oil production according to claim 1, characterized in that, Controlling the medium flow rate to present an intermittent pulsed supply includes: During the pulse shutdown period that cuts off the flow of the medium, the residual heat decay slope of the inner wall of the lubricating oil blending vessel is monitored at high frequency; When the absolute value of the residual heat decay slope is less than the preset balance threshold, indicating that the heat stored on the inner wall of the lubricating oil mixing vessel has been fully diffused to the surrounding cold oil, a subsequent pulse start command is triggered. Using the residual heat attenuation slope as a physical feedback node, the duration of each pulse's off state is dynamically determined, forming an adaptive pulse duty cycle.

8. The temperature control method in lubricating oil production according to claim 1, characterized in that, Synchronously acquire the real-time operating load of the stirring motor, including: As the additive is continuously injected, the total volume of the injected liquid is accumulated, and the height of the liquid level rise inside the lubricating oil mixing vessel is calculated based on the total volume of the injected liquid. The basic physical resistance of the stirring motor due to the increase in immersion area is estimated based on the height of the liquid level rise. The effective resistance load caused by the significant change in viscosity of the multi-component fluid is extracted by subtracting the basic physical resistance from the overall load consumed by the stirring motor. The effective resistance load is used as the real-time operating load and is negatively correlated with the injection flow rate.

9. The temperature control method in lubricating oil production according to claim 1, characterized in that, The injection flow rate is negatively correlated with the real-time operating load, including: When the real-time operating load increases, it indicates a sharp increase in local viscous resistance, accompanied by a large accumulation of mechanical shear heat. At this time, the injection flow rate of the additive is reduced, thereby prolonging the physical residence time of the additive in the high shear region; By utilizing the extended physical retention time, the additive, injected at a low flow rate, is sufficiently sheared and dispersed. The accompanying cooling effectively neutralizes the enriched mechanical shear heat, preventing localized agglomeration and clumping of the material induced by rapid, high-flow-rate cold injection.

10. The temperature control method in lubricating oil production according to claim 1, characterized in that, After the additive injection is completed and the real-time temperature reaches the set temperature, the process further includes: Continuously track the fluctuation range of the real-time operating load; When the fluctuation range change trajectory tends to be stable and the real-time driving current no longer shows abrupt peaks, it is determined that the additive has reached a homogeneous dispersion state inside the main oil. Subsequently, the lockout restriction on the medium flow rate is released, and continuous closed-loop control of the real-time temperature is restored, completing the final constant-temperature homogenization curing of the finished product.

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