科里奥利式质量流量计的改进设计

发布时间：2018-06-21 15:45

本文选题：科里奥利式 + 质量流量计　；参考：《中南林业科技大学》2016年硕士论文

【摘要】：科里奥利质量流量计(Coriolis Mass Flowmeter,以下简称科氏质量流量计)能直接对质量流量的参数进行测量,且较同类产品测量的精度高,稳定性好。但我国的科氏流量计市场却被少数几家国外品牌所垄断,售价很高。研究分析表明,国内的科氏流量计与国外同类产品比较主要在精度和稳定度方面有较大的差距。本文针对科氏流量计对测量精度和稳定度的要求,从振动原理、信号测量到驱动控制技术等方面进行较全面的研究和实验,应用嵌入式系统的硬件和相应的软件算法对科氏流量计进行了改进设计。进行的工作和取得的主要成果如下。(1)现存的微弯型科氏质量流量计变送器在对小流量信号进行测量时,在测量精度和稳定度上无法达到理想效果。针对这一问题,基于原有处理信号的算法,对其进行改进和优化,利用两级滤波与四点拉格朗日插值方法相结合的“组合算法”,能更加彻底的滤除噪声,实现过零点检测计算。对后期得到的数据进行平均处理,使测量结果具有良好的精度和稳定度。(2)采用模糊PID控制方法对测量管振动进行控制,极大地增强了测量管振动的抗干扰能力。实验结果表明,测量管从起振到振幅稳定使用传统PID控制时则需要13s,而使用模糊PID控制只需要4s左右。特别地,当测量管内流体突然变成气液二相流时,传统控制下需要22秒能恢复正常振动,而模糊控制方法只需要13s。(3)在综合前述研究成果的基础上,研制出一款流量计变送器。与国外15mm口径微弯型传感器相匹配进行空管零点测试,并在实验平台上进行水流量测试实验,测试结果表明,变送器在长时间内均能具有很好的零点稳定性,且在20：1的量程比范围内达到了0.5级测量精度,且重复性达到万分之三。实验测试证实了改进设计后的变送器系统能很好地提高微弯型传感器的测量精度和稳定度。
[Abstract]:Coriolis Mass Flowmeter (Coriolis Mass Flowmeter) can measure the parameters of mass flow directly, and has higher accuracy and better stability than similar products. But our country's Coriolis Flowmeter market is monopolized by a few foreign brands and the price is very high. The research and analysis show that the Coriolis Flowmeter has a big difference in precision and stability. According to the requirements of Coriolis Flowmeter for measuring accuracy and stability, this paper makes a comprehensive research and experiment on vibration principle, signal measurement and drive control technology. The design of Coriolis Flowmeter is improved by using the hardware of embedded system and the corresponding software algorithm. The work and main results obtained are as follows: 1) the existing microcurved Coriolis mass Flowmeter transmitter can not achieve ideal results in measuring the small flow signals in terms of measurement accuracy and stability. To solve this problem, based on the original signal processing algorithm, it is improved and optimized, and the combined algorithm which combines two-stage filter and four-point Lagrangian interpolation method can filter noise more thoroughly. The calculation of zero crossing detection is realized. Through the average processing of the data obtained in the later period, the measurement results have good accuracy and stability. The fuzzy pid control method is used to control the vibration of the measuring tube, which greatly enhances the anti-interference ability of the measurement tube vibration. The experimental results show that the conventional pid control and fuzzy pid control are needed for 13 s and 4 s respectively. In particular, when the fluid in the tube suddenly becomes gas-liquid two-phase flow, it takes 22 seconds to recover the normal vibration under traditional control, while the fuzzy control method only needs 13s.m3) on the basis of synthesizing the above research results, a Flowmeter transmitter is developed. Matching with 15mm microbend sensor, the zero point of empty tube is tested, and the water flow is tested on the experimental platform. The test results show that the transmitter has good zero stability in a long period of time. In the range of 20:1 measurement range, the accuracy is 0.5 and the repeatability is 3/10000. The experimental results show that the improved transmitter system can improve the measurement accuracy and stability of the microbend sensor.
【学位授予单位】：中南林业科技大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TH814

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