Problem Solving through Design Thinking rooted in System

Thinking 451FN3 Cooler ESP Fan Bearings temperature high

“Systems” try hard to come back to itsequilibrium position by dissipating energy when pushed away from its equilibrium position.

The Story of the Cooler ESP Fan

Chimney

Fan Inlet Duct

Fan Outlet Duct

Fan NDE Bearing

Fan Outlet Duct for slag mill

Problem: High temperature of Fan Bearings that would lead to stoppage of the entire plant

Observationsa) High temperature of both DE & NDE Bearing (Max 104 C).

b) Temperature of bearing does not comes down appreciably by water spray & Fan cooling. Why?????

c) Temperature rising frequently in day & goes down in night. Why?????

d) Grease melting, Zn based additive used in grease.e) Displacement value of bearing high up to 100 microns.f) Virtual absence of fundamental Peak. Why??g) 2 N is dominant in spectrum. Why???????h) Acceleration value of Fan NDE Bearing increased

around 400%.

Problem: High temperature of Fan Bearings

Observationsi) Unbalance of Fan. No!! (no increase in velocity

component of 1N in the signature)j) Motor side vibration appears to be low, but higher

energy in higher frequency zone.k) Dumped vibration frequencies in spectrum due to

turbulence in air flow causing positive damping.l) Current fluctuation(100 Amp.) & speed fluctuation (30

RPM).m) Designed temperature of Fan gas operation 280 C &

Present gas operating temperature 250 C – 260 C (gas being cooled by water spray).

Why-Why?????

Temperature of bearing does not comes down appreciably by water & Fan cooling. Why?????

Ans: Presently bearing temperature is 104 C to 95 C (self destructionproperty) while normal operating temperature is around 50 C.Rise in temperature is 45 C to 54 C

Water & Fan cooling only decrease temperature up to 80 C.

So the dissipation of heat by conduction & convection = 15/45*100 = 33.33%

Hence, dissipation of heat in form of radiation = 67.67%.

Clue: The system is unstable (away from equilibrium) since the system has moved from conduction convection currents breakdown of boundary layers radiation. It is trying to come to equilibrium.

Why-Why?????

Temperature rising frequently in day & goes down in night. Why?????

Note: 66.67 % of heat (energy) is dissipated in form of radiation, which follows “ Stefan Boltzman’s Law ”Stefan Boltzman’s Law Q=εσA(T4 – TC

4 )where Q=heat dissipated

T=Temperature of the bearingTc=Ambient temperature.ε, σ are constant.

Clue: A system tries to come back to equilibrium by dissipating energy. So, what happens if we increase the air turbulence during day todissipate more energy? The system must become stable!

Grease melting, Zn based additive (reacts with metal surface ) used over EP2.

Effects: Zn based grease reacts (at higher temperature) with surface & reduces coefficient of friction of surface that’s why ball spin frequency appeared in the above spectrum & also the fundamental peak has very low amplitude in spectrum (slip – stick phenomenon of bearing and positive damping due to air turbulence on the system tries to resist the motion).

Why-Why?????

Effect of Gas temperature on gas density & load. HOW??

Ans. Fan Designed parameters:1) Capacity 625200 m3/ hr & Static pressure 150mm

WC2) Designed temperature of Fan gas operation280.C

& density 0.6 Kg/m3.

After calculation at Present gas temperature 250 C –260 c the calculated gas density is 0.67 Kg/m3, which ultimately increases the mass of gas.

What the extra energy is doing?

1) Increase in the angular momentum.2) Increase in the Kinetic Energy by more than

1000 times (KE = ½ Iω2) – a non linear relationship. RPM - relationship is therefore important.

3) ∆ KE=0.5xI(4002 - 3502)= 18750I ( 30% extra load on Fan)

1) The extra energy is also damped/dissipated through flow turbulence, if allowed. And that is a key to the solution of the problem

KILN - 451FN3 ESP FAN451FN3 -F1A FAN DE AXIAL

Analyze Spectrum 10-Sep-10 09:03:48

PK = 1.23 LOAD = 100.0 RPM = 400. (6.66 Hz)

0 6000 12000 18000 24000

0

0.3

0.6

0.9

1.2

Frequency in CPM

PK V

eloc

ity

in m

m/S

ec

Freq: Ordr: Spec:

399.82 1.000 .151

>SKF 23138 CCK/W3 D=BSF -IO

D D D D D D D D D D D D

Ball spin frequency in spectrum indicating the slipping of rolling elements

Why-Why?????Virtual absence of fundamental Peak & 2 N is dominant in spectrum – due to positive damping

KILN - 451FN3 ESP FAN451FN3 -F1H FAN DE HORIZONTAL

Analyze Spectrum 10-Sep-10 09:01:39

PK = 4.50 LOAD = 100.0 RPM = 400. (6.67 Hz)

0 3000 6000 9000 12000 15000

0

1

2

3

4

5

6

Frequency in CPM

PK V

eloc

ity

in m

m/S

ec

Freq: Ordr: Spec:

399.93 1.000 .217

Ball spin frequency

PK V

eloc

ity

in m

m/S

ec

Frequency in CPM

KILN - 451FN3 ESP FAN451FN3 -F1H FAN DE HORIZONTAL

0 10000 20000 30000 40000

0

0.5

1.0

1.5

2.0

2.5

3.0

3.5Max Amp 3.96

09:00:2510-Sep-10

15:12:2904-Sep-10

10:55:2928-Aug-10

16:05:1119-Aug-10

No Unbalance of Fan.

KILN - 451FN3 ESP FAN451FN3 -F1H FAN DE HORIZONTAL

Analyze Spectrum 10-Sep-10 09:01:39

PK = 4.50 LOAD = 100.0 RPM = 400. (6.67 Hz)

0 3000 6000 9000 12000 15000

0

1

2

3

4

5

6

Frequency in CPM

PK V

eloc

ity

in m

m/S

ec

Freq: Ordr: Spec:

399.93 1.000 .217

Motor side vibration appears to be low, but higher energy in higher frequency zone

KILN - 451FN3 ESP FAN451FN3 -M2A MOTOR DE AXIAL

Route Spectrum 10-Sep-10 08:59:58

OVERALL= 1.80 V-DG PK = 1.80 LOAD = 100.0 RPM = 412. (6.87 Hz)

0 20000 40000 60000

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

Frequency in CPM

PK V

eloc

ity

in m

m/S

ec

Dumped vibration frequencies in spectrum

KILN - 451FN3 ESP FAN451FN3 -F2H FAN NDE HORIZONTAL

Analyze Spectrum 10-Sep-10 08:54:56

P-P = 50.45 LOAD = 100.0 RPM = 400. (6.67 Hz)

0 2000 4000 6000 8000 10000

0

10

20

30

40

50

Frequency in CPM

P-P

Displ

acem

ent

in M

icro

ns

399.

98

799.

96

1199

.9

1599

.9

1999

.9

2399

.9

2799

.9

3199

.8

3599

.8

3999

.8

4399

.8

4799

.8

5199

.7

5599

.7

5999

.7

6399

.7

6799

.7

7199

.7

7599

.6

7999

.6Freq: Ordr: Spec:

401.62 1.004 3.823

Indicates problem related to air flow (turbulence); damping reduces the amplitude of 1N peak

DATE :8/9/10 TO 10/9/10 TIME:11AM TO 7PM Process parameters & measurements

DATE : 10/9/10 TO 11/9/10 TO 10/9/10 TIME :10PM TO 12 PM Process parameters & measurements

Current fluctuation(100 Amp.) & speed fluctuation (30 RPM) – Self organizing

DATE 8/9/10 TO 10/9/10 10/9/10 TO 11/9/10

TIME 11AM TO 7PM 10PM TO 12 PM

CURRENT 431 340

RPM 411 352

DE TEMP. 84 (with external cooling)

72 C went down to 45 C

NDE TEMP. 89.9 (with external cooling)

74 went down to 48 C

GAS TEMP. 270 C 259 to 290 C

EXTERNAL COOLING ON BEARING

YES NO

SET POINT TO COOLER ESP FAN PANNEL

70% 60.3%

PID OPERATION MODE MANUAL AUTO

CONCLUSION : RPM OF COOLER FAN & GAS TEMP PRODUCE DRAMATIC EFFECT ON BEARING TEMPERATURE

What is to be done now?

Monitor fan bearingsMonitor Motor bearingsDon’t cool the gas: higher the temp better it is! Promote energy dissipation through turbulence.Keep the fan at low speed & in auto for the system to adjust & come back to equilibriumMonitor the Oxygen content of the Kiln

Is 405 TPH possible from designed level of 200 TPH?Yes - It is possible…(without investments)!!!

We recognize and understand Patterns & Relationships!The “system as a whole” is more important than “individual components”. The emergent behavior of any system is dependent on the changes in the relationships – the essence. Allow the system to come back to its equilibrium position, which it is always desperately trying to do – The Secret.

Thanks & Acknowledgement

I gratefully thank and acknowledge the active collaborative participation of Mr. Avinash, Mr. Ladha, Mr. Anil and the group of young plant engineers who participated in the 3 day fun-filled workshop in solving this important & curious problem, implemented the solutions immediately & helped prepare the slides. Any questions? Contact: Dibyendu De at dde337@gmail.com