CN-121980765-A - Thermal stress self-adaptive compensation method for external heating pipeline of BOPP film production line

CN121980765ACN 121980765 ACN121980765 ACN 121980765ACN-121980765-A

Abstract

The invention relates to the technical field of pipeline safety monitoring, and discloses a thermal stress self-adaptive compensation method for a heating pipeline outside a BOPP film production line, which is characterized in that a high-temperature-resistant sensor is arranged, data are acquired, temperature-strain-vibration decoupling and basic parameters are calculated under a high-temperature environment, a BOPP production line dedicated multi-load coupling stress calculation model is adopted, multi-section hinged corrugated pipe compensator parameter optimization, self-adaptive compensation adjustment and double closed loop iterative optimization are adopted, and the integrated technical path of high-temperature-resistant multi-dimensional sensing monitoring-parameter linkage stress calculation-high-frequency response corrugated pipe compensation optimization-stress-film thickness double closed loop iterative is realized, so that the thermal stress self-adaptive compensation of the BOPP film production line outside the heating pipeline under the working conditions of 200-250 ℃ and high-frequency load is realized.

Inventors

LI YIMING
WANG JIALIANG
ZHANG SHENGQIAN
GAO LEI
LIU XIXIAO
LIU CHUANLIANG
LI BIAO
ZHU YUMING
YANG JIAN

Assignees

南京国晟福智技术装备有限公司

Dates

Publication Date: 20260505
Application Date: 20251226

Claims (10)

1. A method for adaptively compensating thermal stress of a heating pipeline outside a BOPP film production line, comprising the steps of: S1, high temperature resistant sensor arrangement and data acquisition, namely adopting a ROTDR sensor, a BOTDA sensor and a metal welding FBG sensor combination scheme which are resistant to 250 ℃, wherein an optical fiber is provided with a fluorine resin sheath and is assisted with an air cooling sleeve, and the fluorine resin sheath is arranged in the areas of a pipeline straight pipe section, an elbow and a compensator according to preset intervals to acquire temperature change Brillouin frequency shift Bragg wavelength variation Parameters such as melt flow rate v; S2, temperature-strain-vibration decoupling and basic parameter calculation under the high-temperature environment, wherein the temperature change rate is obtained based on the data acquired in S1 and the high-temperature resistant sensing source understanding coupling Bending strain Mechanical strain Frequency of temperature change Vibration amplitude By adopting ROTDR +BOTDA combined with temperature compensation and circumferential average strain calculation, the decoupling error is ensured to be less than or equal to 0.5 percent at 220 ℃; S3, calculating the special multi-load coupling stress of the BOPP production line, namely integrating S2 output parameters, sequentially calculating bending stress, axial thermal stress, internal pressure coupling stress, shearing stress, temperature alternating fatigue stress and polymer adhesion vibration stress, and correcting length-diameter ratio parameters through k-n dynamic adaptation verification to obtain total stress Stress deviation Double safety verification of total stress and equivalent shear stress is adopted; s4, optimizing parameters of the multi-section hinged corrugated pipe compensator, namely calculating deformation energy, self-adaptive displacement and adjustment coefficient of the compensator based on stress parameters of S3 and temperature change rate of S2 by combining thermal expansion correction Updating compensator radius ; S5, self-adaptive compensation adjustment and double closed loop iteration optimization, namely setting compensation response speed and iteration times according to a stress classification strategy, and combining total stress Deviation from BOPP film thickness Iteratively adjusting compensator parameters until And is also provided with 。
2. The adaptive compensation method for the thermal stress of the heating pipeline outside the BOPP film production line according to claim 1, wherein in the S1, BOTDA sensors are welded on the longitudinal direction of the pipeline top, ROTDR sensors are arranged along the pipeline top or the pipeline bottom and are not bonded, FBG sensors are welded in pairs in hoop directions and longitudinally, a group is arranged at intervals of 2-5 m, 1 pair of FBG sensors are arranged at intervals of 2 pi/N along the circumferential direction of the pipeline, and the acquisition frequency is 5-10 Hz.
3. The adaptive compensation method for thermal stress of heating lines outside a BOPP film production line according to claim 1, wherein in S2, a BOTDA sensor decoupling formula is: ; Temperature compensation error checking: dynamically correcting the decoupling coefficient when the error exceeds the limit And ; Calculation of average strain in circumferential direction taking the average strain value of N pair of sensors Counteracting local strain deviations caused by longitudinal bending; Wherein, the In order to be a coefficient of strain, Is the coefficient of the internal friction temperature of the steel plate, 、 Is a decoupling coefficient.
4. The adaptive compensation method for thermal stress of heating lines outside a BOPP film production line according to claim 1, wherein in S2, the FBG sensor decoupling formula is: ; Wherein, the For apparent temperature sensitivity, through high temperature calibration correction, In order to be able to achieve a mechanical strain sensitivity, For the difference in thermal expansion coefficients of the pipeline and the optical fiber, Is the FBG decoupling coefficient.
5. The adaptive compensation method for thermal stress of heating pipeline outside BOPP film production line according to claim 1, wherein in S3, the shear stress calculation formula is: ; Wherein, the In order to cut the correction coefficient(s), In the event of a transverse force, Is the shear modulus; the dynamic calculation formula is: ; Wherein A is the sectional area of the pipeline, Is the moment of inertia of the cross section, Is the static moment of the magnetic field, Is the width of the section; k-n dynamic adaptation checking, namely calculating pipeline segment length ratio n=L2:L1 and length-diameter ratio parameters: ; Checking whether the following conditions are satisfied: Automatically correcting when the error exceeds 5% ; Gao Wenshi modulus of elasticity ; Wherein, the Is the normal-temperature elastic modulus of 316L stainless steel, The temperature correction coefficient is the elastic modulus; input S2 、 Calculating temperature alternating fatigue stress: ; Wherein, the For the frequency correction factor of the temperature change, Is the fatigue stress amplification factor.
6. The self-adaptive compensation method for thermal stress of heating pipeline outside BOPP film production line according to claim 1, wherein in S3, the formula of adhesion vibration stress of polymer is: ; Wherein, the In order to achieve an adhesion coefficient of the adhesive, For the melt flow rate collected in S2, In order to achieve a melt density, For the reference strain amplitude value, The vibration amplitude extracted for S2; The dual security check satisfies: constraint and equivalent shear stress verification: ; Wherein, the In the form of a hoop stress, As a result of the total stress in the axial direction, A 316L stainless steel yield strength; The total stress calculation formula is: ; stress deviation: ; Wherein, the Stress is allowed for BOPP lines.
7. The method for adaptively compensating for thermal stress of a heating line outside a BOPP film production line according to claim 1, wherein in S4, the compensator parameter is optimized to include thermal expansion correction: ; the compensator radius update formula: ; aspect ratio adaptation parameters: ; Wherein, the For the correction factor of the stress deviation to the adjustment factor, For the initial adjustment of the coefficient of the device, As a temperature change rate sensitivity coefficient, Is the correction coefficient of stress deviation to length-diameter ratio.
8. The method for adaptively compensating thermal stress of heating pipeline outside BOPP film production line according to claim 1, wherein in S5, the stress classification strategy is as follows And (5) classifying risk grades: The compensation response speed is less than 0.5s, and the iteration times are more than or equal to 3 times; The compensation response speed is less than 0.4s, and the iteration times are more than or equal to 4 times; III (40-60%) the compensation response speed is less than 0.35s, and the iteration times are more than or equal to 5 times; IV (60-80%) compensation response speed is less than 0.3s, and iteration times are more than or equal to 6 times; V-stage (> 80%) compensation response speed is less than 0.25s, and iteration times are more than or equal to 8.
9. The adaptive compensation method for thermal stress of heating pipeline outside BOPP film production line according to claim 1, wherein in S5, the pipeline radius adjustment formula during iterative optimization contains thermal expansion correction: ; Wherein, the For the correction coefficient of stress deviation to pipeline radius, the iteration termination condition is that And BOPP film thickness deviation 。
10. The self-adaptive compensation method for the thermal stress of the heating pipeline outside the BOPP film production line according to claim 1, wherein the response speed of the multi-section hinged corrugated pipe compensator is less than 0.5s, the power of the heat conducting oil pump after compensation is reduced by 12% -15%, the peak value of the vibration stress is reduced from 42MPa to below 8MPa, the total stress of the pipeline is less than or equal to 110MPa, and the thickness deviation of the BOPP film is less than or equal to 5%.

Description

Thermal stress self-adaptive compensation method for external heating pipeline of BOPP film production line Technical Field The invention relates to the technical field of pipeline safety monitoring, in particular to a self-adaptive compensation method for thermal stress of a heating pipeline outside a BOPP film production line. Background The external pipeline (especially the external heating pipeline of the BOPP film production line) is used as a key infrastructure for industrial production, and in the long-term service process, the external pipeline not only generates thermal expansion due to environmental temperature fluctuation and causes obvious thermal stress due to pipeline laying constraint (such as soil fixation and supporting limit), but also needs to bear the special load of the BOPP production line, namely fatigue stress caused by high-frequency temperature cycle of fluctuation for 2-3 times per minute in the range of 180-220 ℃ and periodic vibration load of the pipeline induced by polymer melt flow. These loads are superimposed with longitudinal bending deformation caused by pipeline internal pressure, soil load and uneven foundation settlement, and the pipeline materials are easy to deteriorate and the weld joint is easy to fatigue crack under the long-term action. However, the existing thermal stress compensation technology has obvious defects that the existing thermal stress compensation technology is based on fixed structure compensation (such as a traditional U-shaped bent pipe), passive compensation under preset working conditions can only be realized, dynamic self-adaptive adjustment cannot be realized according to real-time stress states of pipelines, inertia is large, response is slow, the BOPP pipeline tiny displacement high-frequency response requirement is difficult to adapt, a stress calculation model often ignores coupling effects of longitudinal bending load, temperature and strain and BOPP production line specific load, stress calculation accuracy is insufficient, actual stress states of the pipelines are difficult to accurately reflect, a closed-loop control mechanism of 'real-time monitoring-compensation adjustment-effect check' is also lacked, a sensor scheme is not adaptive to a high-temperature environment of 200-250 ℃ of the BOPP pipeline, compensation effect cannot be verified and corrected timely, and long-term service safety of the pipelines is difficult to ensure. Therefore, the invention provides a self-adaptive compensation method for the thermal stress of the heating pipeline outside the BOPP film production line, and the technical problems are improved. Disclosure of Invention Aiming at the defects of the prior art, the embodiment of the invention provides a self-adaptive compensation method for the thermal stress of an external heating pipeline of a BOPP film production line, which adopts an integrated technical path of high temperature resistance multi-dimensional sensing monitoring, parameter linkage type stress calculation, high frequency response corrugated pipe compensation optimization, stress and film thickness double closed loop iteration, so as to realize the self-adaptive compensation for the thermal stress of the external heating pipeline of the BOPP film production line under the working conditions of high temperature of 200-250 ℃ and high frequency load, ensure that the total stress of the pipeline is less than or equal to 110MPa and the film thickness deviation is less than or equal to 5%. The technical aim of the invention is realized by the following technical scheme that the self-adaptive compensation method for the thermal stress of the external heating pipeline of the BOPP film production line comprises the following steps: S1, high temperature resistant sensor arrangement and data acquisition, adopting a scheme of a ROTDR sensor, a BOTDA sensor and a metal welding FBG sensor which are resistant to 250 ℃, wherein an optical fiber is provided with a fluorine resin sheath and is assisted with an air cooling sleeve, and the fluorine resin sheath is arranged in a pipeline straight section, an elbow and a compensator area according to preset intervals to acquire temperature change Brillouin frequency shiftBragg wavelength variationParameters such as melt flow rate v; s2, temperature-strain-vibration decoupling and basic parameter calculation under high-temperature environment, wherein the temperature change rate is obtained based on the data acquired in S1 and the high-temperature resistant sensing source understanding coupling Bending strainMechanical strainFrequency of temperature changeVibration amplitudeBy adopting ROTDR +BOTDA combined with temperature compensation and circumferential average strain calculation, the decoupling error is ensured to be less than or equal to 0.5 percent at 220 ℃; S3, calculating the special multi-load coupling stress of the BOPP production line, integrating S2 output parameters, sequentially calculating bending str