VIBRATION ANALYSIS AT THERMAL POWER PLANTS

VIBRATION ANALYSIS AT THERMAL POWER PLANTS: 

VIBRATION ANALYSIS AT THERMAL POWER PLANTS SHIVAJI CHOUDHURY

OBJECTIVE: 

OBJECTIVE to increase equipment protection; to improve safety for personnel; to improve maintenance procedures; to detect problems early; to avoid catastrophic failures; to extend equipment life; to enhance operations.

VIBRATION MONITORING: 

VIBRATION MONITORING Vibration monitoring is the technology of measuring vibration characteristics such as amplitude, frequency, and velocity at specific locations (for example, bearing housings) to identify abnormal conditions or faulty components in rotating machinery. Vibration problems can originate from design, installation, set up, in-service wear, or maintenance.

VIBRATION ANALYSIS(FREQUENCY DOMAIN): 

VIBRATION ANALYSIS(FREQUENCY DOMAIN) A great deal of vibration analysis is done in the frequency domain because the various sources of vibration can usually be isolated by the frequencies at which they occur. A single channel analysed in the frequency domain gives a great deal of information, but often it is important to relate vibration to a second channel as either a phase or amplitude reference, or both.

VIBRATION ANALYSIS(FFT): 

VIBRATION ANALYSIS(FFT) The basic technique for converting a broadband time trace to discrete frequencies, or frequency bands, is by the application of the Fourier transform (FT), a mathematical technique that identifies the sinusoidal components that make up the total vibration signal, including any mechanical or electrical noise that may be present. This analysis can be realized with the help of a computer and signal processing software, by special devices (which are usually called a Fourier analyser), or by hardware microchips (DSPs). More commonly used in analysers now is a more efficient mathematical routine, the fast Fourier transform (FFT).

DEFECT DETECTED USING VIBRATION ANALYSIS(FFT): 

DEFECT DETECTED USING VIBRATION ANALYSIS(FFT) 1.UNBALANCE MACHINE 2.ECCENTRIC ROTOR 3.BENT SHAFT 4.COMPONENTS LOOSE IN ROTOR 5.ROTOR RUB 6.JOURNAL BEARING 7.GEARS 8.BELT DRIVE 9.ELECTRICAL PROBLEM 10.BEARING

1.UNBALANCE MACHINE: 

1.UNBALANCE MACHINE Changes in balance will give change in the 1x vector. At fixed speed vibration amplitudes are constants. Amplitude varies proportional to the square of speed.

2.BENT SHAFT: 

2.BENT SHAFT Change of 1x is most common ,if rotor is bent near coupling a higher 2x axial vibration is frequently observed At a fixed speed the rotor vibration values are constant.

3.COMPONENTS LOOSENESS IN ROTOR: 

3.COMPONENTS LOOSENESS IN ROTOR Vibration values may be erratic and inconsistent between start-stop cycle. Sometime subhormonics frequencies are also observed.

4.ROTOR RUB: 

4.ROTOR RUB Most commonly 1X,but also multiples of 1X ,subsynchronous frequencies and natural frequencies.

5.JOURNAL BEARING : 

5.JOURNAL BEARING Vibration frequency-1X,2X,3X. Changes in bearing operating condition or geometry can cause changes in steady state vibration at 1X and higher harmonics or cause subsynchronous (oil or steam whirl) ,in latter case the vibration is usually unsteady and can increase with time ,often rapidly.

6.GEAR: 

6.GEAR Detection requires transducers with high frequency responses. For defect in one tooth: 1x multiples. For worn teeth gear mesh frequency with sidebands and multiples.

6.1.GEARS: 

6.1.GEARS

7.ELECTRIC PROBLEMS: 

7.ELECTRIC PROBLEMS Stiffness dissymmetry (e g axial winding slot in generator/motor rotor): vibration peaks when 2X stimulus is coincident with rotor critical speed .compensating grooves are used as large machine to minimize stimulus. Thermal dissymmetry: can caused by nonuniform rotor ventilation or shorted electrical winding or nonuniform tightness of parts ,cause rotor to bow with the same vibration characteristic as unbalance.

7.1.ELECTRIC MOTOR: 

7.1.ELECTRIC MOTOR

7.2.ELECTRIC MOTOR: 

7.2.ELECTRIC MOTOR

8.BEARING: 

8.BEARING Bearing misalignment :1X,2X,or high harmonics. Parallel or angular bearing misalignment is generally caused by foundation movement .bearing misalignment is not direct cause of vibration excitation but changes the dynamics characteristics of support system. Roller element bearing wear : wideband acceleration at high frequency.

8.1.BEARING : 

8.1.BEARING

VIBRATION ANALYSIS AT THERMAL POWER PLANT: 

VIBRATION ANALYSIS AT THERMAL POWER PLANT Vibration sensors have been routinely installed on main turbines, generator and some large pumps to monitor bearing vibration levels. Main Turbine is the heart of the power plant. Turbine is the most critical part of the plant & it is mandatory to use maximum protections as well as on line measurements of different parameters to avoid any unexpected failure/shutdown. Power plants have begun to use this technology as a predictive maintenance tool for identifying incipient failures in many types of rotating equipment such as fans, pumps, and compressors.

VIBRATION EXCITATION SOURCE IN TURBINE: 

VIBRATION EXCITATION SOURCE IN TURBINE

ONLINE MONITORING OF STEAM TURBINE: 

ONLINE MONITORING OF STEAM TURBINE

ONLINE TURBINE MONITORING SYSTEM: 

ONLINE TURBINE MONITORING SYSTEM

VIBRATION ANALYSIS AND DIAGNOSTIC: 

VIBRATION ANALYSIS AND DIAGNOSTIC Online expert and diagnostic software are available in most of thermal power plants, which can indicate machine fault in advance. This software can generates different kind of plots like Orbit/lissgenus plot ,pattern/bode plot, niquist plot ,polar plot, vector plot ,waveform ,1X,2X,Harmonics . It can give diagnostic results for machine faults like: Unbalance, misalignment, critical speed, permanent bow. Lost rotor parts ,rotor crack, nonsymmetrical rotor. Gear inaccuracy Seal rub Oil whirl Oil whip Steam whirl cavitations

VIBRATION MONITORING OF CRITICAL EQUIPMENTS OF POWER PLANTS: 

VIBRATION MONITORING OF CRITICAL EQUIPMENTS OF POWER PLANTS Boiler feed pumps (TDBFP OR MDBFP) Condensate extraction pumps (CEP) Circulating water pumps Induced draft fans (ID Fan) Force draft fans (FD Fan) Primary air fan Raw water pumps Cooling water pumps Mill motors Coal crushers compressors

STANDARDS: 

STANDARDS

STANDARDS : 

STANDARDS

THANKYOU: 

THANKYOU