Detection and Diagnosis of Mechanical Seal Faults in Centrifugal Pumps Based on Acoustic Measurement

2020 ◽  
pp. 963-975
Author(s):  
Alsadak Daraz ◽  
Samir Alabied ◽  
Dong Zhen ◽  
Fengshou Gu ◽  
Andrew D. Ball
Keyword(s):  
Acoustic Measurement ◽  
Mechanical Seal ◽  
Centrifugal Pumps ◽  
Detection And Diagnosis

Centrifugal Pump Leak-Free Technology Introduction and Its Applications in EPR Nuclear Power Plant

2010 ◽  
Author(s):  
Guohui Cong ◽  
Ling Zhang
Keyword(s):  
Power Plant ◽  
Nuclear Power Plant ◽  
Centrifugal Pump ◽  
Nuclear Power ◽  
Operating Conditions ◽  
Critical Conditions ◽  
Mechanical Seal ◽  
Centrifugal Pumps ◽  
Canned Motor ◽  
Magnetic Drive

Environmental protection requirement is more and more critical now, and it increases the request to prevent dangerous liquid to leak outside in nuclear power plant too. Centrifugal pumps are the most important active equipments in nuclear power plant, but there is a shaft clearance between rotor and stator of centrifugal pump. The shaft clearance can lead pumped fluid to the outside, so the environment may be polluted by the leakage. In some critical conditions such as transferring high radioactive fluid in the pump, the leakage shall be totally forbidden. So solutions have to be found to make centrifugal pumps totally leak-free for applications in nuclear power plant. Normally there are three leak-free technologies for centrifugal pumps: mechanical seal with auxiliary system, canned motor and magnetic drive. In this paper, all the three leak-free technologies and some of their applications in EPR 3rd generation PWR nuclear power plants are presented and discussed. The results show that in EPR nuclear power plant, canned motor pumps can be preferably used for strict environmental requirement of leak-free if the pump power and operating conditions are applicable. For other conditions, pumps with double mechanical seal can also be used with additional sealing water system support. For centrifugal pumps with magnetic drive are not so applicable in high pressure condition, and the safety aspect is weaker than canned motor pumps, generally they are not used in EPR nuclear power plant at present.

Mechanical Seal Efficiency Considerations for Pumps in Utilities: Economics of Seals vs. Packing, and Savings With Best Available Seal Flush Arrangements

2008 ◽  
Author(s):  
Richard Smith ◽  
Alan Roddis ◽  
Heinz P. Bloch
Keyword(s):  
Case Studies ◽  
Best Practice ◽  
Energy Savings ◽  
Cooling Water ◽  
Oil Refining ◽  
Feed Water ◽  
Mechanical Seal ◽  
Centrifugal Pumps ◽  
Power Generators ◽  
Water Pumps

Applicable industrial standards for centrifugal pumps endorse several different sealing options as “best practice.” However, the overall acceptance of best practice techniques seems slow and is linked to the fact that sealing devices account for only a small fraction of the energy consumed by pumps. Yet, regardless of perception, significant energy conservation has been achieved by thoughtful sealing practices, as this paper will show. It will highlight case studies that provide guidance on issues of increasing technical and societal concerns relating to fluid emissions. Special attention will be directed to barrier fluid circulation devices used in dual mechanical seal arrangements as described by API-682 (Ref.1), a Standard widely used in the oil refining and petrochemical industries. The applicability of these ciculation devices to the Power Industry will be explained. Comparisons of three of the most widely used conventional integral flow induction/pumping ring devices will be made and the results of extensive testing presented. The paper and presentation also quantifies the value of advanced sealing technologies for pumps and highlights configurational differences between the newer and the more traditional (older) devices. Without exception, international utilities and power producers know that both energy and maintenance expenditures are affected by availability and reliability considerations relating to power generators and their turbine drivers. But feed water pumps and cooling water issues play their part as well. Consequently, a measure of attention has been given to “other big ticket items”, such as cooling tower losses and the like. However, there is compelling evidence that additional, less prominent or less obvious opportunities exist and that these can no longer be overlooked. Pump sealing falls into that category, although sealing devices and seal cooling account for only a small fraction of the energy consumed by pumps. In can be readily shown that significant energy savings have been achieved by thoughtful sealing practices. The general narrative and the implications conveyed by our case studies give visibility to the issues and provide guidance to the user.

Relationship Between Vibrations and Mechanical Seal Failures in Centrifugal Pumps

2005 ◽  
Author(s):  
David B. Stefanko ◽  
Robert A. Leishear
Keyword(s):  
Industrial Applications ◽  
The Other ◽  
Fluid Film ◽  
Operating Speed ◽  
Mechanical Seal ◽  
Mechanical Seals ◽  
Centrifugal Pumps ◽  
Radial Vibrations ◽  
The Common ◽  
Bearing Design

A reduction of radial vibrations in mechanical seals increases the life of the seals in centrifugal pumps. Mechanical seals consist of two smooth seal faces. One face is stationary with respect to the pump. The other rotates. Between the faces a fluid film evaporates as the fluid moves radially. Ideally, the film evaporates as it reaches the outer surface of the seal faces, thereby preventing leakage from the pump and effectively lubricating the two surfaces. Relative vibrations between the two surfaces affect the fluid film, damage the faces, and decrease the life of the seals. In a series of industrial applications, different techniques were used to minimize vibration, and the life of the seals was shown to significantly increase. The operating speed was controlled in one case, the bearing design was replaced in another case, and the stiffness of the pump was altered in still another case. The common corrective action in each case was a reduction in vibration.

Cavitation Detection of a Centrifugal Pump Using Instantanous Angular Speed

Volume 3 ◽  
2004 ◽  
Author(s):  
S. Al-Hashmi ◽  
F. Gu ◽  
Y. Li ◽  
A. D. Ball ◽  
Tao Fen ◽  
...  
Keyword(s):  
High Frequency ◽  
Angular Speed ◽  
Centrifugal Pumps ◽  
Third Order ◽  
New Approach ◽  
Order Spectrum ◽  
Shaft Encoder ◽  
Detection And Diagnosis ◽  
Cavitation Detection ◽  
Harmful Effects

Cavitation is a common fault in centrifugal pumps. The detection and diagnosis of the onset and severity of the cavitation provide the means of preventing the cavitation from causing harmful effects such as deterioration of the hydraulic performance, damage to pump components and the pollution by vibration and noise. This paper presents a new approach to monitoring cavitation based on the measurement of instantaneous angular speed (IAS) of the pump. IAS is measured using a cheap shaft encoder and processed using order spectrum analysis. It has been found that the normalised amplitude at the third order of the rotational speed can be used as a primary monitoring feature to detect the onset of the cavitation and to quantify the severity of the cavitation. A secondary detection feature is also defined in the high frequency range. This makes the detection results more reliable.

scholarly journals Relationship Between Vibrations and Mechanical Seal Life in Centrifugal Pumps

2007 ◽  
Author(s):  
Robert A. Leishear ◽  
David B. Stefanko
Keyword(s):  
Crack Growth ◽  
Fatigue Damage ◽  
The Other ◽  
Fluid Film ◽  
Time To Failure ◽  
Mechanical Seal ◽  
Mechanical Seals ◽  
Centrifugal Pumps ◽  
Vibration Data ◽  
Cyclic Stresses

A reduction of vibrations in mechanical seals increases the life of the seals in centrifugal pumps by minimizing fatigue damage. Mechanical seals consist of two smooth seal faces. One face is stationary with respect to the pump. The other rotates. Between the faces a fluid film evaporates as the fluid moves radially outward across the seal face. Ideally, the film evaporates as it reaches the outer surface of the seal faces, thereby preventing leakage from the pump and effectively lubricating the two surfaces. Relative vibrations between the two surfaces affect the fluid film and lead to stresses on the seal faces, which lead to fatigue damage. As the fluid film breaks down, impacts between the two seal faces create tensile stresses on the faces, which cycle at the speed of the motor rotation. These cyclic stresses provide the mechanism leading to fatigue crack growth. The magnitude of the stress is directly related to the rate of crack growth and time to failure of a seal. Related to the stress magnitude, vibration data is related to the life of mechanical seals in pumps.

Cavitation Detection of a Centrifugal Pump Using Noise Spectrum

2005 ◽  
Author(s):  
Seyed Farshid Chini ◽  
Hassan Rahimzadeh ◽  
Mohsen Bahrami
Keyword(s):  
Rate Increase ◽  
Noise Pollution ◽  
Noise Spectrum ◽  
Centrifugal Pumps ◽  
New Approach ◽  
Cavitation Effect ◽  
Flow Rate Increase ◽  
Detection And Diagnosis ◽  
Cavitation Detection ◽  
Harmful Effects

Cavitation is a common fault in centrifugal pumps. The detection and diagnosis of the onset and severity of the cavitation provide the means for preventing harmful effects such as deterioration of the hydraulic performance, damage to pump components, vibration and noise pollution. This paper presents a new approach for monitoring cavitation based on the noise measurement spectrum and analysis. Noise is measured using a microphone and a P.C. equipped with soundcard and Matlab6.1 uses Fast Fourier Transform to change the domain from time to frequency. It has been found that the sound pressure level at some frequencies can be used as a primary monitoring feature to detect the onset of the cavitation and to quantify the severity of the cavitation. One of these frequencies is related to the number of blades. Other detection features are defined in other frequencies, as well. Flow rate increase was used to have stronger cavitation effect.

scholarly journals Structural Analysis of Mechanical Seal Holding for Mixer Pumps

2020 ◽  
Vol 9 (3) ◽  
pp. 3867-3872
Keyword(s):  
Structural Analysis ◽  
Design Guidelines ◽  
Chamber Pressure ◽  
Mechanical Seal ◽  
Technical Service ◽  
Critical Area ◽  
Centrifugal Pumps ◽  
Shaft Diameter ◽  
Seal Chamber

A mechanical seal is a device that used to reduce leakage containing pressure or ignoring contamination. Mechanical seal is the device used in centrifugal Pumps, Mixers, Agitators and Compressors to arrest or reduce the leakage. The mechanical seal standard API 682 provides the design guidelines for the seals which are fits below 110mm shaft diameter and 4.2 N/mm2 seal chamber pressure. Any seal more than these parameters required special engineering or guidelines needs from technical service. The main aim is to design the mechanical seal for more than 110mm shaft diameter and more than 4.2 N/mm2 pressure. Since the basic seal components are mostly standardized and already tested than the seal gland connections are seems to be critical for large shaft diameter and high or heavy pressure applications. Hence the stress and deflection of the mechanical seal gland is analyzed based on barrier pressure and seal chamber pressure with the help of Inventor and another critical area is the seal drive arrangements.

Fuzzy Comprehensive Evaluation Method for Mechanical Seal Risk Assessment of Centrifugal Pumps

2011 ◽  
Vol 474-476 ◽  
pp. 1283-1287
Author(s):  
Ying Jie Hao ◽  
Bo Qin Gu
Keyword(s):  
Evaluation Method ◽  
Comprehensive Evaluation ◽  
Fuzzy Comprehensive Evaluation ◽  
Risk Level ◽  
Stable Operation ◽  
Mechanical Seal ◽  
Mechanical Seals ◽  
Centrifugal Pumps ◽  
Fuzzy Comprehensive Evaluation Method ◽  
Comprehensive Evaluation Method

A failure analysis of mechanical seals of centrifugal pumps was presented with fuzzy comprehensive evaluation method. Both failure probability and failure consequence were analyzed to evaluate the risk grade of the mechanical seals. The potential risk level of a mechanical seal was estimated by the application of risk matrix. The proposed fuzzy comprehensive evaluation method can be used to judge the reliability of mechanical seals and provide an important reference for the safe and stable operation of centrifugal pumps.

scholarly journals Analysis of Vibration Characteristics of Centrifugal Pump Mechanical Seal under Wear and Damage Degree

2021 ◽  
Vol 2021 ◽  
pp. 1-9
Author(s):  
Yin Luo ◽  
Wenqi Zhang ◽  
Yakun Fan ◽  
Yuejiang Han ◽  
Weimin Li ◽  
...  
Keyword(s):  
Shock Wave ◽  
Centrifugal Pump ◽  
Frequency Spectrum ◽  
Flow Rate ◽  
Vibration Amplitude ◽  
Vibration Signal ◽  
Mechanical Seal ◽  
Centrifugal Pumps ◽  
Time Frequency ◽  
Seal Failure

Mechanical seal is a kind of shaft sealing equipment. Face wear is one of the main causes of mechanical seal failure. Mechanical seal condition is also related to the reduction of energy consumption and carbon emission. Therefore, we need to detect the centrifugal pump seal condition. At present, vibration signal is a common method for fault monitoring and diagnosis of centrifugal pump. In this paper, the vibration signal under the condition of damaged centrifugal pump seal is measured by studying the characteristics of vibration signal after the end face damage of centrifugal pump. Statistical indicators such as RMS and kurtosis were taken to analyze the average energy and shock wave energy of vibration signal. The time-frequency characteristics of vibration signal are analyzed by frequency spectrum. The results show that there are a large extent variation of vibration amplitude in the direction of base and axis and a weak variation of vibration amplitude in the direction of radial and vertical. With the increasing of flow rate, the RMS of vibration signal falls at first, then keeps steady, and mounts at last when the flow rate is over the design flow rate. It can be shown from the time-frequency spectrum that there is a shock wave and pause signals caused by the shock wave, which are reflected by the higher frequency band components of the vibration signal that can provide a reference to the diagnosis of the occurrence of damaged mechanical seal. From the analysis, the energy of vibration signal is related to the running condition, we can find that the occurrence of mechanical seal wear makes the centrifugal pump to produce high-frequency vibration signal, and the axial vibration is the strongest and the instability in the fluid makes the vibration signal produce high amplitude characteristics. Analyzing the vibration signal characteristics of centrifugal pumps with damaged mechanical seal is of great significance to find the mechanical seal failure of the centrifugal pumps and adjust the operating parameters.

Research on stator current characteristics of centrifugal pumps under different mechanical seal failures

2021 ◽  
pp. 095440622110610
Author(s):  
Jiamin Zou ◽  
Yin Luo ◽  
Yuejiang Han ◽  
Yakun Fan
Keyword(s):  
Centrifugal Pump ◽  
Negative Impact ◽  
Maximum Amplitude ◽  
Mechanical Seal ◽  
Centrifugal Pumps ◽  
Pump System ◽  
Seal Failure ◽  
Stator Current ◽  
Marginal Spectrum ◽  
Current Characteristics

Mechanical seal failure has a great negative impact on the operation of a centrifugal pump system. A method to analyze the stator current characteristics of the motor in a centrifugal pump system is proposed to monitor the internal flow of the centrifugal pump and to identify the failure status of the mechanical seal. Experiments were conducted under different mechanical seal states. Based on sensorless technology, the stator current signal of the motor is collected, processed by windowing function, anti-aliasing filter, singular value decomposition, Hilbert–Huang transform, and the marginal spectrum of correlation quantity is drawn. The results show that according to the external characteristic curve of the centrifugal pump, after the failure of the mechanical seal, the head and efficiency of the centrifugal pump decrease, and the head is greatly affected by the degree of failure, while the degree of mechanical seal failure has little effect on the shaft power of the centrifugal pump; the centrifugal pump has good operation stability under design conditions or near slightly large flow; the stability of centrifugal pump operation decreases with the aggravation of mechanical seal failure; the corresponding maximum amplitude in the marginal spectrum can be used as an index to diagnose the damage degree of the mechanical seal.

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