CN-121977346-A - Self-adaptive control method and system for sealing pressure of lithium iron phosphate rotary kiln

CN121977346ACN 121977346 ACN121977346 ACN 121977346ACN-121977346-A

Abstract

The invention relates to the technical field of industrial automation control, in particular to a self-adaptive control method and a self-adaptive control system for sealing pressure of a lithium iron phosphate rotary kiln, which aim to solve the technical problems of sealing gap fluctuation caused by barrel thermal creep and gravity bending and leakage and abrasion caused by existing feedback control hysteresis in the prior art. The method comprises the steps of collecting operation data of the rotary kiln, constructing a thermal gravity coupling deformation index based on an effective current value and accumulated operation time, constructing a target seal pressure feedforward model, calculating a theoretical optimal seal pressure set value at the current moment, and calculating a control quantity finally output to an executing mechanism. The invention can reduce the abrasion rate of the sealing element and provide guarantee for continuous sintering of high-quality materials.

Inventors

SUN LIUHUI
SU GENHUA
JIN LIUBIN
GE YANJIE
SUN YANGFAN

Assignees

河南郑矿机器有限公司

Dates

Publication Date: 20260505
Application Date: 20260122

Claims (10)

1. The self-adaptive control method for the sealing pressure of the lithium iron phosphate rotary kiln is characterized by comprising the following steps of: collecting operation data of the rotary kiln, wherein the operation data comprise a heating current original value, accumulated operation time, a real-time rotation angle and a sealing cavity pressure feedback value, and performing sliding window root mean square processing on the heating current original value to obtain a current effective value; Based on the current effective value and the accumulated running time, constructing a thermal gravity coupling deformation index, wherein the thermal gravity coupling deformation index is used for representing the deformation degree of downward bending of the suspended section of the cylinder, the value of the thermal gravity coupling deformation index is positively correlated with the heat input power represented by the current effective value, and the thermal gravity coupling deformation index is in nonlinear growth along with the increase of the accumulated running time; Constructing a target seal pressure feedforward model by using the thermal gravity coupling deformation index as an amplitude modulation parameter and combining the real-time rotation angle, and calculating a theoretical optimal seal pressure set value at the current moment, wherein the theoretical optimal seal pressure set value periodically fluctuates along with the rotation angle; Based on the deviation between the theoretical optimal sealing pressure set value and the sealing cavity pressure feedback value, the dynamic adjustment of the thermal gravity coupling deformation index to the sensitivity of the controller is combined, the control quantity finally output to the executing mechanism is calculated, and the sealing pressure of the rotary kiln is adaptively adjusted.
2. The self-adaptive control method for sealing pressure of lithium iron phosphate rotary kiln according to claim 1, wherein the sliding window root mean square processing of the heating current original value comprises the steps of setting the number of data points corresponding to the time length of a sliding window as N, and calculating the root mean square value of data in the sliding window as the current effective value so as to filter high-frequency noise introduced by power grid fluctuation and voltage regulation of a silicon controlled rectifier.
3. The method for adaptively controlling the sealing pressure of the lithium iron phosphate rotary kiln according to claim 1, wherein the calculation formula of the thermal gravity coupling deformation index is as follows: ; In the formula, Is that Thermal gravity coupling deformation index at moment; To be from the current moment Forward push Current effective values at the sampling moments; to calculate the time window length; Accumulating the running time for the high temperature of the rotary kiln; is the coefficient of thermal expansion influence; is the creep aging coefficient; as a natural logarithmic function.
4. The method for adaptively controlling the sealing pressure of a lithium iron phosphate rotary kiln according to claim 3, wherein the first term in a thermal gravity coupling deformation index calculation formula represents the square average of current in a past period of time and is used for evaluating the current average heat input power, and the second term utilizes a natural logarithmic function to simulate the creep characteristics of a metal material at a high temperature and represents the saturation effect that deformation is accumulated with time but the growth rate is gradually slowed down.
5. The method for adaptively controlling the sealing pressure of the lithium iron phosphate rotary kiln according to claim 1, wherein the calculation formula of the target sealing pressure feedforward model is as follows: ; In the formula, Is that Theoretical optimal sealing pressure set point at moment; a base seal pressure set point for the plant when it is cold and stationary; Is that Thermal gravity coupling deformation index at moment; is a base gain coefficient; Is a fluctuation amplitude coefficient; The real-time rotating speed angular frequency of the rotary kiln; Is the initial phase angle.
6. The method for adaptively controlling the sealing pressure of the lithium iron phosphate rotary kiln according to claim 5, wherein the initial phase angle corresponds to the lowest point of the bending geometric characteristic of the rotary kiln cylinder and is the angle at which the rotary kiln cylinder presses the sealing ring downwards most severely, when the cosine value part is positive, the actuating mechanism is pressurized in advance to seal the enlarged gap, and when the cosine value part is negative, the actuating mechanism is depressurized in advance, and the sealing is maintained by utilizing the dead weight of the cylinder.
7. The method for adaptively controlling the sealing pressure of a lithium iron phosphate rotary kiln according to claim 1, wherein the formula for calculating the control amount finally output to the actuator is: ; In the formula, For the current moment The control quantity is output to the executing mechanism; the output quantity of the last control period; is a basic proportional gain coefficient; Is that Thermal gravity coupling deformation index at moment; designing a deformation limit constant for the maximum allowable by the equipment; Is that Theoretical optimal sealing pressure set point at moment; Is the feedback value of the pressure of the sealing cavity.
8. The method for adaptively controlling the sealing pressure of a lithium iron phosphate rotary kiln according to claim 7, wherein the formula is as follows And as the thermal gravity coupling deformation index approaches to the maximum design deformation limit constant allowed by the equipment, the adaptive gain factor is increased, so that the controller outputs a larger adjustment amplitude to correct the pressure instability.
9. The method for adaptively controlling the sealing pressure of a lithium iron phosphate rotary kiln according to claim 7, further comprising the step of limiting the boundary if the sealing pressure of the lithium iron phosphate rotary kiln is calculated If the ratio is more than 100%, the value is 100%, if the ratio is calculated Less than 0%, the value is 0%.
10. The lithium iron phosphate rotary kiln sealing pressure adaptive control system is characterized by comprising a processor and a memory, wherein the memory stores computer program instructions, and when the computer program instructions are executed by the processor, the lithium iron phosphate rotary kiln sealing pressure adaptive control method is realized.

Description

Self-adaptive control method and system for sealing pressure of lithium iron phosphate rotary kiln Technical Field The invention relates to the technical field of industrial automation control, in particular to a self-adaptive control method and a self-adaptive control system for sealing pressure of a lithium iron phosphate rotary kiln. Background In the production process of lithium ion battery cathode materials, in particular lithium iron phosphate (LFP), high-temperature solid-phase sintering is a key procedure affecting the material performance. The procedure generally adopts an electric heating rotary kiln, and maintains a micro-positive pressure nitrogen protection atmosphere in the kiln to prevent oxidation, so that the dynamic and static sealing performance of the kiln head and the kiln tail is important. At present, a composite sealing structure combining mechanical contact and a gas barrier is commonly adopted in the industry, and a sealing ring is attached to a cylinder flange by applying pressure. However, the rotary kiln cylinder body can generate thermal creep under high-temperature electric heating, the yield strength is reduced, and together with the dead weight of the cylinder body and the load of materials, the suspended section can generate irreversible sagging deformation. Such deformations lead to the sealing end surface exhibiting an eccentric runout during rotation, so that the sealing gap fluctuates drastically during the rotation period. The existing control technology mainly relies on a pressure sensor in a sealed cavity for PID feedback adjustment, but due to the compressibility of a gaseous medium and the action delay of an actuating mechanism, the feedback mechanism of hysteresis cannot adapt to a rapidly-changing gap. When the gap becomes larger, the pressure compensation is not timely carried out, so that oxygen can be permeated, and when the gap becomes smaller, the pressure is not timely released, so that the sealing ring and the cylinder body can be severely rubbed. This double failure of blow-by-wear problem not only increases maintenance costs, but also severely affects the sintering consistency of the product. Disclosure of Invention In order to solve the problems of the prior art, such as seal clearance fluctuation caused by barrel thermal creep and gravity bending, and leakage and abrasion caused by the existing feedback control hysteresis, the invention provides solutions in various aspects as follows. In a first aspect, the invention provides a sealing pressure self-adaptive control method for a lithium iron phosphate rotary kiln, which comprises the following steps: collecting operation data of the rotary kiln, wherein the operation data comprise a heating current original value, accumulated operation time, a real-time rotation angle and a sealing cavity pressure feedback value, and performing sliding window root mean square processing on the heating current original value to obtain a current effective value; Based on the current effective value and the accumulated running time, constructing a thermal gravity coupling deformation index, wherein the thermal gravity coupling deformation index is used for representing the deformation degree of downward bending of the suspended section of the cylinder, the value of the thermal gravity coupling deformation index is positively correlated with the heat input power represented by the current effective value, and the thermal gravity coupling deformation index is in nonlinear growth along with the increase of the accumulated running time; Constructing a target seal pressure feedforward model by using the thermal gravity coupling deformation index as an amplitude modulation parameter and combining the real-time rotation angle, and calculating a theoretical optimal seal pressure set value at the current moment, wherein the theoretical optimal seal pressure set value periodically fluctuates along with the rotation angle; Based on the deviation between the theoretical optimal sealing pressure set value and the sealing cavity pressure feedback value, the dynamic adjustment of the thermal gravity coupling deformation index to the sensitivity of the controller is combined, the control quantity finally output to the executing mechanism is calculated, and the sealing pressure of the rotary kiln is adaptively adjusted. The control mode of traditional passive feedback is changed, deformation indexes constructed by using current and time data can be utilized to pre-judge the deformation trend before the change of the physical gap, and a dynamic pressure instruction changing along with the angle is generated; the feedforward mechanism of the invention eliminates control lag and ensures that the sealing pressure is always synchronous with the eccentric runout of the cylinder. Further, the sliding window root mean square processing of the heating current original value comprises the steps of setting the number of data points corresponding t