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International Standard Serial Number:
ISSN 1001-4551
Sponsor:
Zhejiang University;
Zhejiang Machinery and Electrical Group
Edited by:
Editorial of Journal of Mechanical & Electrical Engineering
Chief Editor:
ZHAO Qun
Vice Chief Editor:
TANG ren-zhong,
LUO Xiang-yang
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86-571-87041360,87239525
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86-571-87239571
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No.9 Gaoguannong,Daxue Road,Hangzhou,China
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meem_contribute@163.com
Abstract: The rotary energy recovery device (RERD) was used in the seawater desalination process. The rotational speed of the rotor can directly reflect the operative state of the RERD. The rotor was entirely covered by the outer shell. Therefore, the rotational speed of the rotor was difficult to measure directly. To solve the problem, the vibration frequency and rotor rotation frequency of rotary energy recovery device were analyzed, and a method for measuring rotor speed of rotary energy recovery device based on vibration signal was proposed. Firstly, the vibration data and the rotational speed data at different flow rates were collected by experiments. It was found that the main vibration frequency corresponded well to the 8 times rotational frequency by analyzing the vibration frequency of the device and the rotational frequency of the rotor. The relationship between the main frequency and the rotational frequency was established. Then, the method of processing signals and calculating the rotational frequency was studied to obtain the rotational frequency information from vibration signals, including eliminating baseline drift by wavelet transform, demodulating vibration signals to reflect the rotational frequency better; in order to accurately calculate the rotor speed, the frequency conversion range was estimated through vibration energy. Finally, the accuracy of the speed measurement method was verified on the experimental platform. The results show that the maximum error rate of rotational speed is 2.55% under the steady state and the maximum error rate is 4.58% under an unsteady state. It can meet the requirements of online and accurate measurement of the RERD rotational speed.
Key words: rotary energy recovery device(RERD); rotor speed measurement method; vibration signals; baseline drift; signal envelope demodulation; vibration main frequency; rotational frequency