ntpc vindhyachal-six sigma project

8/11/2019 NTPC Vindhyachal-six Sigma Project

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Place your Organization logo here

Six Sigma ProjectOrganization

Name

VINDHYACHAL SUPER

THREMAL POWER

PROJECT,NTPC LIMITED

Plant Location VINDHYANAGAR, SIDHI, M.P.

CHAMPION P.K.MOHAPATRA

TEAM

MEMBERS

L.D.SAHOO, Leader

SBANERJEE, Black belt

NILESH DANGAYACH, Green belt

Place the team

photograph here


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NTPC PROFILE Indias premier national

power generatingcompany

Multi fuel, multi locationplants

Comprehensive

capabilities in Building and operating

power plants

In house projectimplementation

Negotiating fuelpurchase, bulk powersale

Consultancy services

VINDHYACHAL


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Place your Organization logo here 3260 MW


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0

500

1000

1500

2000

2500

3000

3500

U1(87) U2(88) U3(89) U4(89) U5(90) U6(91) U7(99) U8(00) U9(06) U10(07)

Unit (Year)

THE LARGEST

POWER PLANT OF THE NATION

CAPACIT

Y(MW)

6x210 MW + 2x500 MW + 2x500 MW

3260 MW


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DDefine

M & A

Measure &Analyse

IImprove

CControl

DEFINE

MEASURE & ANALYSE

IMPROVE

CONTROL


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Phase1- Problem Definition

Problem Statement

At NTPC Vindhyachal Stage-II (2 x 500 MW)

boiler exit flue gas loss causing huge heat rate

deviation, reducing thermal power efficiency

and increasing carbon di oxide emission.


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Part number selected for study Stage II (2 x 500 MW) BOILER

PART NUMBER HAVING SIMILAR DESIGN

STAGE III (2 x 500 MW) newly

commissioned units


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Process stages where the Problem is suspected Less heat absorption in first pass as well as super and re-

heater section of the boiler

Soot deposit in water wall and radiant zone of the furnace aswell as super heater area

Less optimized operational parameters like:

Total air flow

Burner tilt,

Mills under performances,

Poor fineness, SADC position, etc.

Air ingress

Poor performances of Air preheater


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Current average rejection for last 6 months

Exit flue gas temperature is around 20 0C more

than the designed value 140 0C,

Heat loss of around 28 kcal/kwhr.

Maximum and Minimum rejection in last 6 months

Maximum/month : 165 0C (35 kcal /kwhr)Minimum/month : 160 0C (28 kcal/kwhr)


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Objective of the Project

To optimize exit flue gas loss of boiler

throughoperational f ine tuning, increasing

efficiency of thermal power cycle, to reduce

coal consumption and thus saving natural

resources, reducing carbon dioxide emission


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Potential annual savings

Every one 0C reduction in exit Flue gas temperature

saves 1.4 kcal/kwhr of heat rate , (saving of 1.4 x

2200 MT of coal annually in stage II units) 20 0C reduction from its design value means

saving 61000 MT of coal annually in stage II

Cost of coal/MT =Rs 1000/-(approx.) Potential saving = 6.1 crores annually in stage II

units

6


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Response

Variable : Exit flue gas temp at the boiler

outlet in 0C.

Specification (if the response is variable)

Less than 140 0C

6


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3%

Stack

Clean-up

Equipment

5%

Auxiliary

Power

10%

Stack

Losses

37%

Electricity

Production45%

Rejected Heat to

Cooling Water/ Cooling Tower

Heat Input into a Large Coal Fueled Power Plant

6


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6


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BOTTOM RNG HDR & Z-PANEL 1STPASS W.W

1STPASS W.W O/L HDRS ROOF I/L HEADER

2NDPASS UPPER C-HDR 2ndPASS LOWER C-HDRS

LTSH I/L HEADER LTSH O/L HEADER

D.P.I/L HEADER D.P.O/L HEADER

S.H. HEADER R.H.HEADER

2NDPASS ROOF O/L HDR(REAR ECONOMISER

M.S

H.

R.

HC.R.H

FROM F.R.S

6


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PAPH-A

SAPH-A

SAPH-B

PAPH-B

FD FAN -B

FD FAN-A

PA FAN -A

PA FAN -A

SCAPH-B

PRIMARY

SCAPH-B

SECOND

SCAPH-A

PRIMARY

SCAPH-A

SECOND

TO MILLS

TO MILLS

HOTPAHDR

HOT

SAHDR

ECO BYPASS

ECO BYPASS

ECONOM

ISER-3

ECONOMISER-2

ECONO

MISER-1

HORIZONTALS.H

REHEATER

PLATEN

S.H

DIVISION

PANELE

TTES.H

COMBUSTION

CHAMBER

AEROFOIL

AEROFOIL

COLD SEC. AIR

COLD PRIM AIR

HOT PRIMARY AIR

HOT SEC. AIR

FLUE GAS

PNEUMATICALLY O/P

KNIFE EDGE GATE

MOTOR O/P LOUVER

DAMPER

PNEUMATICALLY O/P

LOUVER DAMPER

MOTOR O/P GATE

BIPLANE DAMPER

DIVERTER DAMPER

AA201

AA202AA203

AA204

AA205

AA201

AA202AA203AA205

AA204

AIR AND FLUE GAS PATH TYPICAL 500 MW BOILER

TO ESP

TO ESP

6


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FLUE GAS FLOW DIAGRAM

P

L

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IV

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U

R

N

A

CE

RE

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ER

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PAPH B

SAPH B

SAPH A

PAPH A

960

964

846

944

750

810

549

606

365

379

LH

S

RH

S

DUE TO UNEQUAL HEAT ABSORBTION IN DIFFERENT SECTIONS

OF THE BOILER LEADING TO HIGH FLUE GAS EXIT TEMP IN0

C PAPHO/L TEMP145 0C

SAPH BO/L TEMP

160 0C

SAPH A

O/L TEMP

164

0

C

SAPH B

O/L TEMP

145 0C

6


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In this project our main reference of control is

exit flue gas at air preheater outlet, but for our

analysis flue gas temp at economizer inlet is

taken as reference

Assumpt ion

6


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P

L

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A

CE

RE

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T

ER

H

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PAPH B

SAPH B

SAPH A

PAPH A

960

964

846

944

750

810

549

606

365

379

LH

S

RH

S

Flue gas temp at eco i/lIs treated as our reference

PAPHO/L TEMP

145 0C

SAPH BO/L TEMP

160 0C

SAPH A

O/L TEMP

164 0C

SAPH B

O/L TEMP

145 0C

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Project Planning

Phases Planned Startdate

PlannedCompletio

n date

Actual startdate

Actualcompletion

date

STATUS

Define 1STWEEK MAY2006

4THWEEK

OF MAY

1STWEEK MAY

2006

4THWEEK OF

MAY

COMPLETED

Measure

&

Analyze

IST WEEK OF

JUNE 06

4THWEEK

OF JULY 06

1STWEEK

JUNE06

4THWEEK OF

AUG 2006

COMPLETED

Improve 1STWEEK OFJULY 06

4THWEEK

OF SEPT 06

1STWEEK OF

AUG 2006

4THWEEK OF

OCT 2006

COMPLETED

Control 1STWEEK AUG2006

4THWEEK

OF OCT 2006

1STWEEK OF

AUG 2006

TO CONTINUE IN PROGRESS

6

PHOTOGRAPH OF DEFECTIVE PARTS


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BOILER DRUM

LHS

RHS

FR

REAR

CC PUMP SUC HDR

PHOTOGRAPH OF DEFECTIVE PARTS

SootBuilt up

In 1stpass

6


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BOTTOM RNG HDR & Z-PANEL 1STPASS W.W

1STPASS W.W O/L HDRS ROOF I/L HEADER

2NDPASS UPPER C-HDR 2ndPASS LOWER C-HDRS

LTSH I/L HEADER LTSH O/L HEADER

D.P.I/L HEADER D.P.O/L HEADER

S.H. HEADER R.H.HEADER

2NDPASS ROOF O/L HDR(REAR ECONOMISER

M.S

H.

R.

HC.R.H

FROM F.R.S

Clinker and sootDeposit in super

Heater and reheater

6

h bl fi i i


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COPQ (Cost of Poor Quali ty)


Deviation of exit flue gas temp.

from its designed value

20 0C( six monthly average value)

Deviation of exit flue gas temp.

from its designed value in last

month

20 0C

Boiler heat rate loss due to tempvariation

1.4 kcal/kwhr x 20 = 28 kcal/kwhr

Amount of coal required to burn

more due to heat rate loss

28 x 2200 MT of coal annually i.e 61000

MT of coal (considering 90% plant load

factor in stage II units)

Financial implication of extracoal burnt

6.1 crores of Rs( considering coal cost of1000 Rs per MT of coal on an average)

Indirect /extra

cost/environmental implication

Less power cycle efficiency, more co2emission

6

h 1 bl fi i i


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Suspected Sources of Variation for theProblem statement (SSVs)

More convective flow less retention of heat in 1stpass

Less heat absorption in 1stpass due to slagging

Less heat absorption in super heater and re heater areadue to dirtiness in the area ,clinkering formation inradiant zone

Improper secondary damper position Poor performance of air preheater and its air ingress

Air ingress in the furnace from pent house and throduct and dampers

6


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DDefine

M & A

Measure &Analyse

IImprove

CControl

DEFINE

MEASURE & ANALYSE

IMPROVE

CONTROL

6

Ph 2 M d A l


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Phase2- Measure and Analyze

Analysis #1

-

More convective flow means

Less retention of heat in 1st pass

Higher total air flow

Higher spray is due to less heat absorption in

1st

pass

6


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Slide number: 28Place your Organization logo here

Data taken with varying total air flow and different spray

Data entry in Minitab

6

R i A l i


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Regression Analysis

FG TEMP AT ECO(R) = 273 + 0.206 total air flow + 0.314 S/H spray

Predictor Coef SE Coef T P

Constant 272.65 61.89 4.41 0.001

total air flow 0.20579 0.03930 5.24 0.000

s/h spray 0.31400 0.04592 6.84 0.000

S = 2.57008 R-Sq = 85.9% R-Sq(adj) = 83.3%

Analysis of Variance

Source DF SS MS F P

Regression 2 442.56 221.28 33.50 0.000

Residual Error 11 72.66 6.61Total 13 515.21

Source DF Seq SS

total air flow 1 133.75s/h spray 1 308.80

An high R-sq value shows that theregression equation is explaining 85.9

percent variation in FG temperature.

Positive coefficient means

More total air flow, higher spray

results in higher FG temp at

ECO(R)

6

h d l


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Analysis # 2

OBJECTIVE:

Optimization of soot blower practices so as to

improve heat absorption in 1stpass and reduce

super heater spray

OBSERVATION:

1. Effect of 4th tier is minimum in terms of S/H and R/H spray2. 1st TIER EFFECT IS MAXIMUM AND SH/RH TEMP. Falls sharply so

is the spray.

6


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1 2 3 4 5 6

23 24 25 26 27 28

45 46 47 48 49 50

67 68 69 70 71 72

12 13 14 15 16 17

34 35 36 37 38 39

56 57 58 59 60 61

78 79 80 81 82 83

FRONT SIDE SOOT BLOWERS REAR SIDE SOOT BLOWERS

1ST TIER

2NDTIER

3RDTIER

4THTIER

1ST TIER

2NDTIER

3RDTIER

4THTIER

6


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18 19 20 21 22

40 41 42 43 44

62 63 64 65 66

84 85 86 87 88

7 8 9 10 11

29 30 31 32 33

51 52 53 54 55

73 74 75 76 77

LHS SOOT BLOWERS RHS SOOT BLOWERS

1ST TIER 1ST TIER

2NDTIER 2NDTIER

3RDTIER 3RDTIER

4THTIER 4THTIER

6


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6

Ph 2 M d A l


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Act ion Taken

1. 4thTIER SOOT BLOWING STARTED ONCE IN TWO

DAYS

2. Sequence is reversed 3,2,1,3,2,1,3,2,1,3

3. 1s t

TIER IS STARTED IN NIGHT SHIFT AT GOODVACUUM CONDITION

6

HYPOTHESIS TESTING


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HYPOTHESIS TESTING

NULL HYPOTHESIS Ho- (ONE TAILED)Super heater/reheater spray before and after the

changed intervention is same

ALTERNATE HYPOTHESIS Ha

super heater /reheater spray before is higher

than super heater/reheater spray after

6

Data Entr in Minitab for


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Data Entry in Minitab for

6

Phase 2 Meas re and Anal e


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WATER WALL SOOT BLOWING PRATICES CHANGED FROMPATTERN 1234 TO PATTERN 321 AND 3214

ADVANTAGES OBTAINED- S/H SPRAY AND R/H SPRAY REDUCED

Two-sample T for super heater spray(before) vs super heater spray (after)

N Mean StDev SE Mean

super heater (Before) 20 67.7 16.1 3.6

super heater (After) 20 56.7 15.8 3.5

Difference = mu (super heater spray(before)) - mu (super heater spray (after))

Estimate for difference: 11.0000

95% CI for difference: (0.7782, 21.2218)

T-Test of difference = 0 (vs not =): T-Value = 2.18 P-Value = 0.036 DF = 37

6

Phase 2 Measure and Analyze


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WATER WALL SOOT BLOWING PRATICES CHANGED FROM

PATTERN 1234 TO PATTERN 321 AND 3214

Two-sample T for REHEATER SPRAY(BEF) T/HR vs REHEATER SPRAY(AFTER)


REHEATER SPRAY(B 20 17.90 5.41 1.2

REHEATER SPRAY(A 20 15.40 3.87 0.87

Difference = mu (REHEATER SPRAY(BEF) T/HR) - mu (REHEATER SPRAY(AFTER))


95% lower bound for difference: -0.01494

T-Test of difference = 0 (vs >): T-Value = 1.68 P-Value = 0.051 DF = 34

NULL HYPOTHESIS IS REJECTED

ALT HYPOTHESIS IS ACCEPTED

6



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Data

super heater spray (after)super heater spray(before)

100

90

80

70

60

50

40

30

Boxplot of super heater spray(before), super heater spray (after)

SH SPRAY BEFORE AND AFTER THIS SOOT BLOWING PATTERN

Box plotBefore & After)

6



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Data

REHEATER SPRAY(AFTER)REHEATER SPRAY(BEF) T/HR

30

25

20

15

10

BOXPLT SHOWING THE DIFF

RH SPRAY BEFORE AND AFTER THIS SOOT BLOWING PATTERN

6



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CONCLUSION

Change in soot blowing practices

helped in reducing super heater and

reheater spray


6



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Analysis #3

Objective

To increase heat absorption in super heater and reheater

section of the boiler, in running condition we have themeasure of long retractable soot blowing operation and to

clear dirtiness, soot , clinkers inside the boiler.

The elaborate arrangements of LRSB along with thefigures are attached herewith.

6


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125 127

129

131133

137 135

119

121

123

BOILER RHS LRSB

105

107

109

117

115

113

111

2ndpass

6


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106

108

110

136 138

132 134

130

128 126

BOILER LHS LRSB

124

122

120

118

116

114

1122ndpass

6



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PAPH B

SAPH B

SAPH A

PAPH A

960

964

846

944

750

810

549

606

365

379

L

H

S

RH

S

FLUE GAS TEMP NOTEDAT THE ECONOMISER INLET

6

HYPOTHESIS TESTING


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HYPOTHESIS TESTING

NULL HYPOTHESIS Ho- (ONE TAILED)Flue gas temperature before economizer inlet is

almost same before and after LRSB operation

ALTERNATE HYPOTHESIS Ha

Flue gas temp is higher than temp after the

LRSB operation.

6

Data entry in Minitab for


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6


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Two-Sample T-Test and CI: ECO INLET FLUE GAS TEMP BEF ANDAFTER LRSB


ECO INLET FLUE G 20 594.90 7.72 1.7

ECO FLUE GAS TEM 20 573.80 6.39 1.4

Difference = mu (ECO INLET FLUE GAS TEMP BEF LRS) - mu (ECO FLUEGAS TEMP AFTER

LRSB)


95% lower bound for difference: 17.3159


SO NULL HYPOTHESIS IS REJECTED

6

Box plots for


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Box plots for .

Data

ECO FLUE GAS TEMP AFTER LRSBECO INLET FLUE GAS TEMP BEF LRS

610

600

590

580

570

560

xplot of ECO INLET FLUE GAS TEMP BEF LRS, ECO FLUE GAS TEMP AFTER LR

6

CONCLUSION


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CONCLUSION

FLUE GAS TEMP BEFORE

ECONOMISER REDUCED

CONSIDERABLYAFTER LRSB OPERATION

6

Phase 2- Measure and Analyze


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Total Analysis summary

Cause(s) identified for the problem: Less optimized operational parameter like total air flow,

first pass low heat absorption due to slagging leading to

higher super heater spray.

Low heat absorption in super heater and reheater

section

Root cause(s) identified for the problem:

Low heat absorption in super heater and reheater plays

dominant role along with total air flow in the furnace.

6



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REGRESSIONFunneling #1

Funneling :

Funneling Summary

Funneling # 2

POOR HEAT ABSORBTION INSUPER HEATER AND REHEATER

SECTION

Funneling # 3


HYPOTHESIS

TESTING

HYPOTHESIS

TESTING

MORE CONVECTIVE FLOW MEANS LESS

RETENTION OF HEAT IN 1ST PASS

POOR HEAT ABSORBTION IN 1 ST PASS

6


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DDefine

M & A

Measure &Analyse

IImprove

CControl

DEFINE

MEASURE & ANALYSE

IMPROVE

CONTROL

6

Validation of root cause #1


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To validate regression equation for 2nddegree

using response surface methodology, in order

to fine tune total air flow and super heater spray

for further optimization of eco inlet flue gas

temperature

Validation of root cause #1

Validation of the Root cause(s)

6 Regression: FG TEMP AT ECO(R) versus total airfl S/H


58/88


flow, S/H spray

The analysis was done using coded units.

Estimated Regression Coefficients for FG TEMP AT ECO(R)

Term Coef SE Coef T P

Constant 606.668 0.6806 891.336 0.000

total air flow 5.961 1.4930 3.993 0.003

s/h spray 7.589 1.0626 7.142 0.000

total air flow*s/h spray -3.022 2.0172 -1.498 0.165

S = 2.436 R-Sq = 88.5% R-Sq(adj) = 85.0%

Analysis of Variance for FG TEMP AT ECO(R)

Source DF Seq SS Adj SS Adj MS F P

Regression 3 455.871 455.871 151.957 25.61 0.000

Linear 2 442.556 451.757 225.878 38.06 0.000

Interaction 1 13.315 13.315 13.315 2.24 0.165

Residual Error 10 59.343 59.343 5.934

Total 13 515.214

6

Residual Analysis


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Residual Analysis

Residual

Percent

5.02.50.0-2.5-5.0

99

90

50

10

1

Fitted Value

Residual

615610605600595

5.0

2.5

0.0

-2.5

-5.0

Residual

Frequency

420-2-4

4

3

2

1

0

Observation Order

Resid

ual

1413121110987654321

5.0

2.5

0.0

-2.5

-5.0

Normal Probability Plot of the Residuals Residuals Versus the Fitted Values

Histogram of the Residuals Residuals Versus the Order of the Data

Residual Plots for FG TEMP AT ECO(R)

6

Contour Plot for searching optimal point


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Contour Plot for searching optimal point

total air flow

s/hspra

y

1600159015801570156015501540

55

50

45

40

35

30

25

20

15

FG TEMP

600 - 605

605 - 610

610

AT ECO(R)

- 615

> 615

< 595

595 - 600

Contour Plot of FG TEMP AT ECO(R) vs s/h spray, total air flow

total air flow = 1562.08

s/h spray = 27.5537FG TEMP AT ECO(R) = 602.571

6

Phase 3 - Improve


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Phase 3 Improve

Optimization of total air flow in the furnace

and to contain super heater spray by water

wall soot blowing is having a limited effect

in controlling eco inlet flue gas temp.

CONCLUSION

6

ROOT CAUSE NO2


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Validation of the Root cause(s)

To improve heat absorption in super heater

and reheater section through selective long

retractable soot blowing operation and later

using ANOVA analysis

6

2 d


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125 127

129

131133

137 135

119

121

123

BOILER RHS LRSB

105

107

109

117

115

113

111

LRSB ARE DIVIDED

INTO

A-S/H RIGHT R/H

LEFT

B-S/H R/H RIGHT

AND 2ND PASS

C-2ND PASS ONLY

D-S/H RIGHT AND

R/H LEFT

2ndpass

6



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6

STACKED DATA OF ECO INLET FLUE GAS TEMP


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STACKED DATA OF ECO INLET FLUE GAS TEMP

6

HYPOTHESIS FOR ANOVA


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NULL HYPOTHESIS-HoMean of Flue gas temp before eco is same in all

four cases of experiment

ALT HYPOTHESISHa

At least one mean is different than others.

6

Analysis data for validation


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One-way ANOVA: C15 versus C14

Source DF SS MS F P

C14 3 3094.6 1031.5 18.95 0.000

Error 56 3048.7 54.4

Total 59 6143.2

S = 7.378 R-Sq = 50.37% R-Sq(adj) = 47.72%

Individual 95% CIs For Mean Based on

Pooled StDev

Level N Mean StDev ---------+---------+---------+---------+

A 15 557.40 8.07 (----*-----)

B 15 569.47 10.37 (-----*----)

C 15 576.20 4.00 (----*-----)D 15 561.93 5.39 (-----*----)

---------+---------+---------+---------+

560.0 567.0 574.0 581.0

Pooled StDev = 7.38

Reject the null hypothesis

At least one form is creating

significant improvement

Analysis data for validation

6


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C14 = A subtracted from:

C14 Lower Center Upper --------+---------+---------+---------+-

B 4.942 12.067 19.192 (-----*-----)

C 11.675 18.800 25.925 (-----*-----)

D -2.592 4.533 11.658 (-----*-----)--------+---------+---------+---------+-

-12 0 12 24

Confidence interval that contain do not zero means

There is a statistically significant difference between

A and B & C &Dso LRSBsection A containing RHS of 1stpass

and LHS of 2ndpass to be employed frequently

6 Box plot showing the best results for the LRSB A


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C14

C

15

DCBA

590

580

570

560

550

540

Individual Value Plot of C15 vs C14

C14

C15

DCBA

590

580

570

560

550

540

Boxplot of C15 by C14

6 RESIDUAL VALUE OF THE STACK VALUE


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Residual

Percent

20100-10-20

99.9

99

90

50

10

1

0.1

Fitted Value

Residual

575570565560555

20

10

0

-10

-20

Residual

Frequency

1680-8-16

16

12

8

4

0

Observation Order

Residual

605550454035302520151051

20

10

0

-10

-20

Normal Probability Plot of the Residuals Residuals Versus the Fitted Values

Histogram of the Residuals Residuals Versus the Order of the Data

Residual Plots for C15

Residuals are normally distributed , there is no reason to reject the model

6

Phase 3 Improve Actions Summary


71/88


Phase 3 Improve Actions Summary

No Root cause(s) Actions Planned Planned

Complet

ion date

Resp Actual

complet

ion date

Status

1 More convective

flow means less

retention of heat in

1st pass andslagging in 1stpass

1. Total air flow is to be

maintained in

between 1560-1620

TPH2. To employ new

pattern of water wall

soot blowing

From 1st

week of

JULY

2006

Shiftchargeengineerin

st2operation

Water

all

sootblo

wingdone

every in

each

shift

Implemented

2, Low heat

absorption super

heater and reheater

section

Increase the frequency

of LRSB in new pattern

of section A

1ST

WEEK

OF

SEPT

2007

Shiftcharge

en

gineerinst2

op

eration

It

willcontinue

ev

eryalternate

da

ysonly

Im

plemented

6


72/88


1 2 3 4 5 6

23 24 25 26 27 28

45 46 47 48 49 50

67 68 69 70 71 72

12 13 14 15 16 17

34 35 36 37 38 39

56 57 58 59 60 61

78 79 80 81 82 83

FRONT SIDE SOOT BLOWERSREAR SIDE SOOT BLOWERS

1ST TIER

2NDTIER

3RDTIER

4THTIER

1ST TIER

2NDTIER

3RDTIER

4THTIER

6


73/88


18 19 20 21 22

40 41 42 43 44

62 63 64 65 66

84 85 86 87 88

7 8 9 10 11

29 30 31 32 33

51 52 53 54 55

73 74 75 76 77

LHS SOOT BLOWERS RHS SOOT BLOWERS

1ST TIER 1ST TIER

2NDTIER 2NDTIER

3RDTIER 3RDTIER

4THTIER 4THTIER

6


74/88


125 127

129

131133

137 135

119

121

123

BOILER RHS LRSB

105

107

109

117

115

113

111

BOILER RHS REDCLOURED LRSB

SELECTED BASED ON

THE RESULTS OF

ANOVA

6


75/88


106

108

110

136 138

132 134

130

128 126

BOILER LHS LRSB

120

124

122

112

114

116

118

RED

COLOURED

LRSBS

IN REHEATER

6


76/88


DDefine

M & A

Measure &Analyse

IImprove

CControl

DEFINE

MEASURE & ANALYSE

IMPROVE

CONTROL

6

Phase4Control Phase


77/88


No Root cause Variation analysis

done

Type of control method

decided

Status of

implementati

on

1 MORE CONVECTIVEFLOW MEANS LESSRETENTION OF HEAT

IN 1ST PASS AND

SLAGGING IN 1STPASS

EXPERIMENTATION AND

VALIDATION

THRO PAIRED T

TEST AND

REGRESSION

AND RESPONSE

SURFACEMETHODOLOGY

1.CHANGES IN SOOTBLOWING

PROCEDURE

REVISED AND

STANDARDISED

2. POKAYOKA

METHODOLOGY

THROUGH

INTRODUCING

ANNUNCIATION

CKT WHEN AIR

FLOW CROSSING

1630 TPH

IMPLEMENTED FROM

JULY 2006

2. LOW HEATABSORBTIOIN SUPER

HEATER AND

REHEATER SECTION

EXPERIMENTATIO

N AND

VALIDATION

THROUGH ANOVA

ANALYSIS

STANDARD CHART

INTRODUCED

SUGGESTING LRSB

NOS

IMPLEMEN

TED FROM

SEPT 2006

6

Phase4- Control


78/88


Analysis # 1

Objective: To establish whether the improvement actions

employed bring in improvement in our objective data which

is SAPH/PAPH outlet temp (exit flue gas temp)

Tool/technique used: Hypothesis testing of comparison

-

6

Phase4- Control


79/88


Data collected for Control


6

Phase 4 - Control


80/88


Two-sample T for SAPHA O/L BEF vs SAPHA O/L AFT


SAPHA O/L BEF 27 158.70 4.69 0.90

SAPHA O/L AFT 27 155.00 4.28 0.82

Difference = mu (SAPHA O/L BEF) - mu (SAPHA O/L AFT)


95% lower bound for difference: 1.65715


SAPH A OUTLET TEMP COMPARED BETWEEN ONE MONTH VALUE

BEFORE AND AFTER THE IMPROVEMENT ACTION IMPLEMENTED

Establish significant improvement

6

Box and Individual plot


81/88


Data

SAPHA O/L AFTSAPHA O/L BEF

170

165

160

155

150

145

140

Boxplot of SAPHA O/L BEF, SAPHA O/L AFT

Data

SAPHA O/L AFTSAPHA O/L BEF

170

165

160

155

150

145

140

Individual Value Plot of SAPHA O/L BEF, SAPHA O/L AFT

6

Phase4- Control


82/88


Project Summary

THE FACTORS LIKE TOTAL AIR FLOW, SUPER HEATER

METAL TEMP, LESS HEAT ABSORBTION

IN 1STPASS AND SUPER HEATER AND REHEATER ETC

ARE IMPORTANT.

ROOT CAUSES- LESS HEAT ABSORBTION IN

SUPER HEATER AND REHEATER

FOLLOWING FOCUSSED LRSB IMPROVED HEAT

ABSORBTION AND REDUCED EXIT FLUE GAS TEMP.

6

Tangible Benef its der ived through the project


83/88


HEAT RATE SAVING FROM IMPROVEMENT ACTION

Every one degree decrease in average flue gas temp.At APH O/L gives

heat rate improvement to 1.4kcal/kwh.

On an average there is a decrease of 4.5 degC of exit flue gas.

So by decreasing 4.5 degC we are saving heat rate 1.4 x 4.5 = 6.4 kcal

/kwhr.

I kcal/kwhr saving means coal saving of 2200 mt of coal annually in

stage II.[ considering 90% plf on an average, AVCV is 3800 kcal/kg]

By this project reduction of 6.4 kcal/kwh of heat rate achieved

Saving 6.4 x 2200 MT of coal= 14080MT of coal in a year. Considering cost of coal Rs 1000/- per MT

The financial gain from the project is 14016 MT x Rs 1000= Rs 1.40

crores

6

Phase 4 - Control


84/88

Slide number: 84


I ntangible benef its der ived through the project

1. Less coal burnt means less carbon di oxide

emission and ash generation

2. Adopting intelligent soot blowing and selective

LRSB operation thus reducing steam consumption

3. Optimization of total air flow reducing Aux PowerConsumption of ID fans

6

Phase 4 - Control


85/88

Slide number: 85


Current control plan Continuous monitoring of super heater spray

and total air flow in shift operation

Monitoring of flue gas eco inlet temp which

decides the timing of LRSB operation as per

chart.

6

Phase 4 - Control


86/88

Slide number: 86


Proposed control plan O2trimming device will be provided soon

which will optimize total air flow further.

Proposal for procuring software for

intelligent soot blowing operation is being

mooted

6

THANKS


87/88

Slide number: 87


THANKS

6


88/88

ntpc vindhyachal-six sigma project

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