TURBO SUPERVISORY INSTRUMNTS in TTPS

Presented by Deepak ranjan mohanty

TTPS AT A GLANCETalcher Thermal Power Station is located near Talcher in Angul District of Orissa which is about 150 KM from Bhubanswar. TTPS-TWO STAGES STAGE 1: 4 * 60 commissioned during 1967 to 1969 . STAGE 2: 2* 110 commissioned during 1982 to 1983 .

Coal -Mahanadi coal field. Water -Brahamani River.

What is T.S.I.The T.S.I. perform function of monitoring turbine health by measuring certain parameters of turbine continuously.

T.S.I parameters areI. Shaft Eccentricity II. Vibration III. Axial shift IV. Differential expansion V. Casing overall expansion VI. Speed VII. Turbine metal/steam temperature differentials

7 3 HPT 2 5 3

7 3 MPT MB 2 4 5 5

7 5 LPT 3 5 5 6 5 ECCENTRICITY 5 5 5

GEN5

EX 1

12

SPEEDCASING EXPANSION DIFFERENTIAL EXPANSION

7

4 5 6

AXIAL SHIFT VIBRATION TURNING GEAR

SPEED MEASUREMENTThe turbine speed indicators provides

Remote indication when the rotor is rotated by the barring gear. Remote as well as local digital indication of the turbine speed.

SPEED MEASUREMENTprobeSLOTTED DISK

AXIAL SHIFT OF ROTOR

There are some reasons of increasing the axial thrustMore/less resistance developed in steam flow path on account of salt deposits/erosion, wearing of it Thrust bearing failure. Oil flow failure/improper to thrust bearing. IT is measured by PROXIMITY PRINCIPLE.

THE PROXIMITY PRINCIPLE:Eddy Current

CONDUCTIVE MATERIAL PROXIMITORRadio Frequency Signal

The oscillator in the matching unit supplies(RF signal) the coil in the sensor

with a load Independent, high frequency alternating current.if the sensor isbrought near to a metal object,the eddy currents are induced in surface of the object and the power is absorbed thus alternating the voltage across

the coil.The alternating voltage is proportional to the distance between themeasured Object and the sensor.the output independent D.C. Voltage signal. amplifier forms a load

AXIAL SHIFT OF ROTORCALIBRTAIONSENSOR

COLLAR

Towards HPT

Towards generator

COLLAR MOVING AWAY FROM SENSOR INCREASES GAP READING IS VE . COLLAR MOVING TOWARDS SENSOR DECREASES GAP READING IS +VE.

DIFFRENTIAL EXPANSION

If rotor expands more than casing thenit is the positive expansion

If the casing expands more than the rotor then it is said to be Negative expansion

DIFFRENTIAL EXPANSIONThe measurement principle is same as axial shiftHP DE RANGE-7 to +7mm Alarm value -1.5 & 3.5mm MP DE RANGE- -7 to +7mm Alarm value -1.5 & 3.5mm LP DE RANGE- -7 to +7mm Alarm value -1.5 & 3.5mm

DIFFERENTIAL EXPANSION (HP DE)CALIBRTAIONSENSOR

COLLAR

Towards HPT

Towards generator

COLLAR MOVING AWAY FROM SENSOR INCREASES GAP RADING IS VE . COLLAR MOVING TOWARDS SENSOR DECREASES GAP RADING IS +VE.

DIFFERENTIAL EXPANSION (MP DE/LP DE)CALIBRTAIONSENSOR

COLLAR

Towards HPT

Towards generator

COLLAR MOVING AWAY FROM SENSOR INCREASES GAP RADING IS +VE .COLLAR MOVING TOWARDS SENSOR DECREASES GAP RADING IS -VE.

CASING EXPANSION

The turbine casing is anchored near the middle of the L.P casing and free to expand axially on either direction from the anchored point. Expansion measured at front pedestal is the cumulative expansion of the casing from the anchor point and thus indicate the degree of thermal socking of casing It is measured by L.V.D.T.transmitters.

LVDT : Linear variable Differential Transformers (Casing expansion)

AC

AC voltmeter

Secondary coil connected in series Opposition, In Null position secondary voltage will Cancel there will be no o/p voltage. When core is Displaced from null Position, two voltage no Longer cancel. A net o/p voltage will now result.

Voltage out

(+)

100

50 50 100 Core position (%)

(-)Nominal range LVDT voltage as a function of core position

ECCENTRICITY

Eccentricity is the sagging of the shaft due to it weight

ECCENTRICITYThis eccentricity level is starts increasing temporarily during the its starting ,normal running and shut down periods due to Temperature causes Other mechanical causes It is also measured by PROXIMITY PRINCIPLE.

VibrationVibration is the back and forth motion of the machine or machine parts under the influence of oscillatory forces caused by dynamically unbalanced masses in the rotating system. It can be cause of trouble, result of trouble, symptom of trouble or combination of all three. Vibration is measured on siesmic principle . siesmic tranducer is used for velocity measurement from which mechanical vibration amplitude can be calculated by integration & mechanical vibration acceleration by diff.

SIESMIC MASS : Plunger Coil principle Natural frequency of spring mass system = 2f = c/m m = mass of plunger coil with spring C = spring constant Above ,coil stands still due to its mass inertia When coupling the seismic sensor to vibrating structure, a relative movement is generated between permanent magnet & plunger coil. a voltage is induced in the coil Which is proportional to the vibration velocity : e=B.l.V 6 l= Length of conductors B= magnetic induction v =speed of vib. 3 N 5 1. 2. 3. 4. 5. 6. Exciter of vibration Permanent Magnet Plunger Coil Magnetic Return Path Spring Sensor Case

4

2

S 1

VibrationVibration level increases in due course of operation of the machine on account of

Fast out of balance changes like fracture etc. Slow out of balance changes like corrosion, erosion, deposits bends etc. Self-excited shaft, vibration like steam pulsation, oil pulsation, etc. Mechanical looseness in pedestal faults in coupling, bearing, etc

TURBINE METAL AND STEAM TEMPERATUREMetal temperature of turbine is the most essential parameter to be monitored since it directly reflects the amount of stress on various components. This service provides Continuous recording metal & steam temperature. Continuous recording of differential metal temperature. Audio visual annunciation in the event of impermissible differential metal temperature.

The detector comprises of chromel alumel thermocouple with stainless steel thermo well fixed at the different location of the turbine body.