Three estimators for the estimation of the flue gas mass flow in biomass boilers are presented and compared, namely a sliding-mode observer, a Kalman filter, and a so-called steady-state estimator. The flue gas mass flow is an important process variable in biomass boilers as it contains information about the supplied mass flows of air and decomposed fuel. It is also related to the generated heat flow. Furthermore, its knowledge may be exploited in model-based control strategies which allow one to keep pollutant emissions low, on the one hand, and to achieve high efficiency, on the other hand. However, due to fouling of the equipment over time, measurements and existing estimation methods are not suitable for long-term applications. The estimators proposed in this article are based on a dynamic model for gas tube heat exchangers. They are capable of handling the fouling of the heat exchanger and, additionally, they offer the possibility of monitoring the degree of fouling. By incorporating an additional differential pressure measurement and extending the aforementioned estimators, an improvement regarding the dynamic response and the estimation accuracy is achieved. The application of the estimators to real measurement data from both, a medium-scale and a small-scale biomass boiler, demonstrates their wide applicability.

中文翻译：

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基于模型的生物质锅炉烟气质量流量估算

介绍并比较了用于估算生物质锅炉烟气质量流量的三种估算器，即滑模观测器、卡尔曼滤波器和所谓的稳态估算器。烟气质量流量是生物质锅炉中的一个重要过程变量，因为它包含有关空气和分解燃料的供应质量流量的信息。它还与产生的热流有关。此外，它的知识可以用于基于模型的控制策略，一方面可以使污染物排放保持在低水平，另一方面可以实现高效率。然而，由于设备会随着时间的推移结垢，测量和现有的估计方法不适合长期应用。本文中提出的估算器基于气体管式换热器的动态模型。它们能够处理热交换器的污垢，此外，它们还提供了监控污垢程度的可能性。通过结合额外的压差测量并扩展上述估计器，实现了关于动态响应和估计精度的改进。将估算器应用于来自中型和小型生物质锅炉的实际测量数据，证明了它们的广泛适用性。