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基于数字孪生与双源Pareto融合的颗粒饲料制粒工艺参数优化

Process Parameter Optimization for Feed Pelleting Based on Digital Twin and Dual-source Pareto Fusion

  • 摘要: 针对颗粒饲料制粒工艺参数依赖经验设定、颗粒质量与生产效率难以协同优化的问题,该研究提出一种基于数字孪生与双源Pareto融合的工艺参数优化方法。构建Stacking集成预测模型,利用新增现场数据进行日滚动更新;采用基于树结构Parzen估计器的多目标贝叶斯优化与非支配排序遗传算法Ⅱ进行多目标寻优,通过双源Pareto融合、工程约束筛选和多准则决策形成推荐工况,并开展现场对照验证。模型更新后,颗粒硬度、颗粒耐久性指数和生产率预测的平均绝对百分比误差分别降至2.15%、2.19%和4.45%。在相同总函数评价预算下,融合方案的解集分布均匀性和目标空间覆盖表现出一定优势。在现场验证中,S1产能优先工况的生产率提高22.2%,但PDI下降;S2均衡折中工况的生产率提高13.8%,PDI同步提高。该方法实现了制粒工艺参数预测、优化推荐与现场数据反馈更新的衔接,可为不同新配方生产场景下颗粒质量与生产效率的协调调控提供决策支持。

     

    Abstract: This study aimed to develop a digital-twin-based optimization method incorporating dual-source Pareto fusion for feed pelleting. The method addressed the dependence of process parameter settings on operator experience and the difficulty of balancing pellet quality and production efficiency under different feed formulation scenarios. A stacking ensemble prediction model was constructed using historical production data and was used as the digital twin evaluator. Newly collected field data were incorporated through daily rolling retraining to improve the evaluator's adaptability to changing production conditions. Steam pressure, feeder frequency, and conditioning temperature were selected as adjustable process parameters, whereas feed formulation, environmental conditions, and equipment and production status were treated as fixed scenario characteristics within each production batch. Tree-structured Parzen estimator-based multi-objective Bayesian optimization (TPE-MOBO) and the non-dominated sorting genetic algorithm II (NSGA-II) were employed to search for candidate operating conditions. Candidate Pareto solutions generated by the two algorithms were merged, deduplicated, screened against engineering constraints, and subjected to non-dominated sorting. The resulting archive was further processed through parameter discretization, evaluator-based verification, and multi-criteria decision-making to obtain executable operating recommendations. The optimization methods were compared under an equal total budget of 600 function evaluations, and field experiments were conducted to compare empirical operating conditions with selected optimized recommendations. Field forward validation using 11 production batches showed that daily rolling retraining improved the prediction performance for pellet hardness, pellet durability index (PDI), and productivity. The mean absolute percentage errors decreased from 2.40%, 3.48%, and 4.97% to 2.15%, 2.19%, and 4.45%, respectively. The root mean square errors for hardness, PDI, and productivity decreased from 1.143 to 0.919 N, from 2.963 to 1.805 percentage points, and from 0.994 to 0.955 t/h, respectively. The corresponding coefficients of determination increased from 0.400 to 0.612, from 0.725 to 0.898, and from 0.608 to 0.638. The improvement was most pronounced for PDI prediction. Under the equal evaluation budget, the dual-source fusion archives contained 14 and 43 Pareto solutions in production scenarios S1 and S2, respectively. Their spacing values were 0.054 and 0.0215, both lower than those of the corresponding individual algorithms, while the maximum spread values were 1.36 and 1.37. However, the hypervolume values of the fusion archives did not exceed those of both individual algorithms in either scenario. These results indicated that the principal contribution of fusion was not a consistent improvement in every optimization metric, but the integration of complementary non-dominated operating conditions and the provision of a more diverse set of quality–productivity trade-offs. Field comparison further demonstrated scenario-dependent effects. In S1, the productivity-priority recommendation increased measured productivity from 12.30 to 15.03 t/h, representing an increase of 22.2%, while PDI decreased from 72.69% to 68.43% and mean pellet hardness decreased from 28.75 to 26.21 N. In S2, the balanced-compromise recommendation increased productivity from 13.00 to 14.80 t/h, representing an increase of 13.8%; meanwhile, PDI increased from 71.32% to 74.84% and mean pellet hardness increased from 30.43 to 32.89 N. The results demonstrated that the productivity-priority strategy involved a quality–efficiency trade-off in S1, whereas the balanced-compromise strategy improved both productivity and PDI in S2. The proposed method integrated production performance prediction, dual-algorithm Pareto optimization, executable operating-condition selection, field validation, and daily model updating into a unified decision-support workflow. It provided a practical approach for selecting process parameters according to the requirements of different feed formulations. Further validation across a wider range of formulations, raw material batches, and equipment operating conditions was needed to determine the robustness and applicability of the recommended operating conditions.

     

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