共查询到17条相似文献,搜索用时 171 毫秒
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利用光纤、压力传感器同时获取气固流化床不同位置颗粒浓度、压差、压力信号时间序列,运用涨落复杂性参数分析三种信号时间序列,研究聚氯乙烯颗粒在低气速下的流化状况.实验结果表明三种信号复杂性分析都体现床内运动存在涨落过程,同时结果表明涨落复杂性参数在不同信号中的趋势是一致的,有理由认为涨落复杂性参数对应的仅是系统本身的一定流型运动状况. 相似文献
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提取复杂性理论中的涨落复杂性Cf及算法复杂性C(n)参数对气固流化床压力脉动信号随流化床操作气速增大历经不同流型的变化趋势进行分析.研究结果表明,在起始流化至鼓泡态转变的过程中,气-固体系会进行一种所谓的"重构"现象,复杂性参数能明确地指示固定床、鼓泡流化及湍动流化等不同流型之间的转变过程,为流型识别提供了新思路. 相似文献
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基于模糊信息融合的气固流化床流型及其转换的识别研究 总被引:3,自引:0,他引:3
本文在模糊集理论的基础上介绍了多传感器、多参数识别气固流化床流型的信息融合模型。将压力脉动信号的算法复杂性Cn、涨落复杂性Cf和香农熵En作为融合的特征参数,进行特征层的多参数融合;根据特征参数建立了过渡流型的隶属度函数;对多个传感器的特征层识别结果进行决策层融合,得到了多传感器对不同流化状态的最终识别结果。实验结果表明,采用香农熵特征参数能较好地解决鼓泡与湍动2种流化状态转换的识别;应用多传感器、多参数数据融合对流态化不同流型及其转换的识别能得到较好的效果。 相似文献
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利用压力涨落信号对气固流化床颗粒结块故障进行早期诊断,有着重要的工业应用意义。本文首先从信号产生的物理背景出发,认为压力涨落信号可分解为分形布郎运动和高斯白噪声的加和。结合正交小波变换理论,应用期望最大化算法(EM),得到了压力涨落信号的自相似参数H和高斯白噪声强度σW的极大似然估计,从而证实了这种分解的可行性。应用参数H和σW对模拟颗粒结块故障的研究表明,流化床床层下部压力涨落信号的H和σW参数均对此故障敏感,本文对结果进行了物理解释。因此,H和σW参数有望应用于对此故障的早期诊断。 相似文献
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模糊控制在循环流化床锅炉床层温度控制中的应用 总被引:3,自引:0,他引:3
近年来循环流化床锅炉因其高效、低污染、低成本等特点得到了迅速的发展,但由于其燃烧过程十分复杂,很难用准确的数学模型来描述,因此难于实现常规方法的控制。本文设计了一个带自调整因子的模糊控制器并进行了仿真研究,仿真结果表明该控制器具有良好的控制性能,有望用于流化床锅炉燃烧系统这类复杂过程的控制。 相似文献
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To overcome the fouling problem that is common in heat exchangers for waste heat recovery, a new type of fluidized heat exchanger
was devised and tested. Fluidized bed heat exchangers are considered to be a good candidate for waste heat recovery flue gases
due to their demonstrated ability to avoid fouling or to clean out deposition on heat transfer surfaces, but have a major
drawback with significant pressure losses. These pressure drops typically associated with the distributor plate, which is
a key component in constructing any conventional fluidized bed system, limit the applicability of fluidized bed heat exchangers
for use as an energy saving device. In a new design, however, dilute gassolid particulate is maintained without having a distributor
plate. The main feature of this no-distributor-fluidized (NDF) heat exchanger is the self-cleaning action by ingested circulating
particles at minimal additional pressure loss. In the present study, a multi riser NDF heat exchanger of 7,000 kcal/hr capacity
was built to evaluate its heat transfer performance and fouling reduction characteristics. To experimentally simulate the
fouled condition, fuel rich combustion gas with soot was introduced to the heat exchanger, then a cleaning test was performed
by introducing glass bead particles (600μm) inside the gas passage of the heat exchanger unit. Through the present experimental
study, the performance degradation due to fouling was successfully demonstrated and the cleaning role of particle circulation
was identified. It was also demonstrated that small amounts of circulating particles contribute not only to the fouling reduction
on the gas side, but also to the heat transfer enhancement. Experimental operation data for 50 hours including accelerated
fouling are obtained to simulate the long-term behavior of the system. 相似文献
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筛箱是流化床的主要工作部件,受强大的交变载荷作用,受力条件恶劣,强度问题突出。在此背景下开展了筛箱的有限元分析,利用Pro/E建立了筛箱的三维模型;利用有限元分析软件ANSYS Workbe nch对筛箱结构进行了静态分析;用模态分析理论分析了筛箱结构固有频率和振型。以模态分析为基础,进行筛箱横梁等部分的结构优化,避免共振;采用的研究方法和研究成果为流化床的设计人员提供了有益的参考,提高了设计研究的效率。 相似文献
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Bangyou Wu Guang Yu Celine Bellehumeur Apostolos Kantzas 《Flow Measurement and Instrumentation》2007,18(5-6):197-203
Pressure fluctuations and X-ray computed tomography (CT) measurements were utilized to characterize the flow behavior of gas–solid fluidized beds using polyethylene particles in three Plexiglas columns with diameters of 10, 20, and 30 cm. Air was used as the gas phase. The gas–solid flow dynamic under ambient conditions was characterized from statistical analysis of pressure fluctuation data and CT images. The time-averaged voidage distribution, bubble-phase area fraction, bubble diameter and bubble number distribution varying with the bed heights were extracted from all the three columns. The bed scales had significant effect on the hydrodynamics. The scale-up effects on the gas–solid two-phase flow behavior were discussed. 相似文献
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基于ARMA模型,提出了一种新的气固流化床流态化过程监控方案。利用Honeywell公司生产的24PC系列压力/差压传感器获取气固流化床压力波动信号,拟合n阶自回归m阶滑动平均模型ARMA(n,m)。通过分析,确定自回归阶数n的阈值,实现流态化过程监控。监控在实验室的气固流化床实验装置上进行,初步实验表明,方案用于气固流化床流态化过程监控是有效的。 相似文献