Best O & M practices at 2 X125 MW Akarimota Thermal Power...

Best O & M practices at 2 X125 MW Best O & M practices at 2 X125 MW AkarimotaAkarimota Thermal Power StationThermal Power Station

By: Shri. By: Shri. JanardanJanardan N. Dave: GM (Power)N. Dave: GM (Power)-- Corporate OfficeCorporate OfficeShri. Dinesh S. Shri. Dinesh S. MakwanaMakwana: I/C GM (PP): I/C GM (PP)--ATPSATPSShri. Shri. HirenHiren S. S. SilajiyaSilajiya (EE(EE--Power)Power)--Corporate OfficeCorporate Office

Background

•GMDC is mainly a mining company. It started itsmining business in the year 1963.

• In the year 1994, it had been decided to invest inlignite based 2 x 125 KW Akrimota Thermal PowerStation in Kutch.

•The investment decision was taken for forwardintegration and value addition in the wake of powershortage. The other objective was also to avail taxbenefits for depreciation.

Background

The project got clearance from CEA in the year 1999. The estimated cost of the project was Rs. 1357.11 Cr (Revised).

26 vendors were engaged to execute the power project including MNCs like Alsthom, Germany and Ansaldo, Italy.

Total strength of manpower sanctioned for the power project is 216, out of which 168 are technical personnel.

Background

The plant is using CFBC Boilers which can firelignite and is environment friendly.

The lignite is supplied from nearest Panandhro,Umasar & Matano Madh mines of GMDC andwater is taken from 1.4 KM sea-water intake channelfrom Kori Creek.

GMDC has a Power Purchase Agreement with M/sGUVNL to supply the entire power to the grid.

The plant started commercial generation fromMarch, 2006

PerformanceFINANCIAL YEAR GENERATION (MU) PLF

%INCOME

Rs/CrEXP.Rs/Cr

LOSS/PROFITRs/Cr

2005 – 06 175 8.01 13.26 233.65 - 220.39

2006 – 07 377 17.25 122.53 266.86 -144.27

2007 – 08 1009 45.95 161.54 243.82 - 82.28

2008 – 09 1105 50.49 186.86 235.80 - 48.96

2009 – 10 1393 63.65 273.42 229.80 + 43.62

2010 – 11 1171 53.45 243.25 212.20 + 31.15

2011 – 12 870.9 39.66 142.64 204.49 -61.85

2012 – 13 921.6 42.08 178.55 196.40 -17.85

2013 – 14 985.4 45.00 175.77 186.21 -10.44

2014-15 1358.8 62.04 238.80 222.20 +16.60

2015-16 1427.4 65.00 258.18 252.43 +5.75

2016-17 1392.9 63.60 309.07 309.02 +0.05

2017-18 1360.1 62.11 270.49 256.38 +14.11

Cost AnalysisFINANCIAL YEAR UNITS SOLD (MU) COST PER

UNIT (Rs.)REVENUE EARNED/

UNIT(Rs.)

DIFFERENCE(±)

2007 – 08 848 2.86 1.87 - 0.99

2008 – 09 928 2.53 1.97 - 0.56

2009 – 10 1193 1.92 2.25 + 0.33

2010 – 11 992 2.13 2.45 + 0.32

2011 – 12 733.036 2.35 1.64 -0.71

2012 – 13 774.974 2.13 1.94 -0.19

2013 – 14 859.041 1.89 1.78 -0.11

2014-15 1176.896 1.64 1.76 +0.12

2015-16 1234.287 1.77 1.81 +0.04

2016-17 1177.148 2.22 2.22 +0.0004

2017-18 1158.521 1.88 1.99 +0.10

Best Performance

Highest Daily Generation 03-12-2008 6.08 MU PLF – 101.3%

Highest Monthly Generation March - 2018 155.2 MU PLF – 83.4%

Highest Quarterly Generation Q4:2017-18 446.2 MU PLF – 82.64%

Highest Yearly Generation FY 2015 - 16 1427 MU PLF – 65.0%

Technical Analysis

It has been observed that ATPS achieved more than 100% daily PLFand 83% Monthly PLF several times, efforts are in place for continuebetter performance on sustainable basis.

This inconsistent achievement of good PLF & better performance ismainly owing to ATPS boilers.

CAUSE EFFECT REMARKS

Explosion of Lignite Feeder Severe Eliminated

Omega Panel Tube Leakage Severe Eliminated

Loop Seal Bellow Leakage Severe Eliminated

Boiler Tube Leakage Severe Reduces with plasma coating

Plate Heat Exchanger Failure Moderate Eliminated

N/A of Lignite Feeder Partial Loading Maintenance Activities Reviewed

Gujarat Mineral Development Corporation Limited (GMDC) isoperating 2x125 MW CFBC Boilers at Village Nani Chher,Taluka Lakhpat, District Kutchchh. The salient features ofBoilers,

Boiler:Supplier : M/a AlstomCapacity : 405 TPHPressure : 138 Kg/Cm2Temperature: 535 +/- 5 Dec CType : Circulating Fluidized Boiler, Top supported.Auxiliaries : 2 PA fans, 2 SA Fans, 2 ID Fans, 2 Ash coolerfans, 3 Fluidizing air fans

Brief of ATPS CFBC Boiler

Turbine:

Supplier : M/s. ANSALDOType : ReactionType of Governing : Electro HydraulicNo. of Cylinder :02Speed : 3000 rpm.Main steam Parameter (HP inlet):Pressure :132.6 kg/cm2Temp :535 Degree CIP Inlet :Pressure :31.93 kg/cm2Temp :535 Degree CNo of stages : Control stage +22/16/7.

CombustorLoop-Seal

CFBC-BOILER

CYCLONE

GAS

SH-3

RH-1

ECO

SH-4 Omega PanelTAPH

BURNERS

BED ASH

DRUM

SH-5RH-2 Omega Panel

ESP

CHIMNEY

FLY ASH

COAL+ LIME

AIR

BACK PASS

DRUM

SH-5

RH-1

Condenser

CRH

FromBFP

BOILER

SH-4

RH-2

TURBINEG

IP TURBINE

SH-3

LIGNITE ENTRY

BED ASH

AIR

ECO

Con. Water to Boiler

Electricity Generation from Lignite

Sea water o/l Sea water inlet

Cyclone -A

Boiler Combustion & Cyclone Area

Boiler Drum

Combustor

Cyclone - B

Flue Gas Direction

EROSION PRONE ZONE

SS 310 Shield on Pull out bend at RTZ

level

Elevation At gravimetric feeder floor.

Boiler Combustor (Inside View)

Troubleshooting carried out a ATPS

Shield condition• Initially there was shield on water wall tube in furnace

RTZ area. • However shield and tube erosion has been observed in

RTZ area which led to boiler tube leakages.• We have modified RTZ area shield and replaced with

refractory application. • It improves the condition and reduce the boiler tube

leakages. • Additional hanger tube shields reconditioning has been

carried out.

Furnace RTZ area



Recovering of L-valves• Previously we were facing problems of L-valves choking.

• It restricts the bed material draining and increase the

furnace bed pressure.

• We have carried out modification in L-valves.

• L-valve sleeve has been modified and extended inside the

furnace (500 mm) to avoid choking from big material like,

refractory piece, clinker piece, etc.

L-valve Modified Sleeve Sleeve inside Furnace



Rectifying of primary air leakages• We have arrested primary air leakage which resulted in

increased PA flow and improve the fluidization and

combustion efficiency.

• It also helps in reducing auxiliary power consumption.


Recovery of Draglink chain conveyor• We were facing generation loss due to tripping of lignite

draglink feeder.

• We have carried out overhauling of draglink with replacement of

chain sprocket, guide plates, liner plates and links.


Recovery of damaged refractory lining• Refractory condition is very important part in CFBC

boiler. We have carried out damaged refractory recovering in the following area.

• Both Ash coolers, • Loop seal, • Furnace inside, • Cyclone-1A ,• Cyclone -1B area

Recovery of Damaged Refractory


ModificationIn Refractory for

Prevention of water wall tube

erosion

Omega Panel

Refractory Sealing box

(Inside Combustor)

Sealing Rope

Pressure Plate

Combustor water wall

tubes

Combustor water wall Erosion

adjacent refractory seal box in each

omega panel

BEFORE AFTER

REFRACTORY MODIFICATION

SicromalPlate

OMEGA PANEL– sealing rope arrangement and sincromal plate


Recovering of all the sealing air connection• Sealing air line bellow found damaged condition same

was removed from its position and Non- metallic bellow replaced with metallic bellow.


Cleaning of expansion joints underneath PA wind box.

• We are carrying out cleaning of expansion joint underneath PA win box in ever shutdown for proper expansion to avoid any potential damage.


Rectifying of L-valve supports• We have carried out L-valve bellow replacement and

provide the supports to avoid deformation of L-valve bellow and to prevent it from damage.


Recovering of damaged fluidizing nozzles• Fluidizing nozzles is very important for proper fluidization in

CFBC boiler.• We are carrying out nozzle mapping to check for damaged

nozzles. • After mapping result we have carried out damaged fluidizing

nozzles replacement. • We are also arranging PA nozzles holes in cross direction to

avoid damage of other nozzle from high velocity jet of air.


Furnace nozzles


Vortex condition• Previously cyclone vortex deformation and ditched

from its position has been observed.

• Vortex damage leads to unit shutdown and huge generation loss.

• We have restrict the cyclone inlet temperature to avoid damage cyclone vortex.

• We have also carried out strengthening and provide support and refractory to vortex.


Cyclone vortex strengthening


Photo graph shows deposition between two tubes

Sequence of work execution.1. Cutting of tubes.2. Hydro jet cleaning with 400 bar.3. New tube installation.

TAPH tube replacement work


FURNACE RTZ AREA PLASMA COATING WORK IN U#1 & 2

Before-Eroded tubes in RTZ area After-Plasma coating of 500

microns.


PASS”B” outlet

PASS”B” InletPASS”A”

Intlet

PASS”A” outlet


Condenser cleaning work :

Pneumatic de-chocking tool Hydro-jet machine

Gauge showing pressure of 500 bar for hydro-jet machine.


Condenser chocked & de-chocked tubes.

CONDENSER DETAIL :-• Condenser having around 9600 tubes.•Condenser chocked tube status(2741 Nos.)• Pass A inlet 1060 nos. & outlet 1021 Nos.• Pass B inlet 442 Nos. & outlet 218 Nos.• At present 1304 nos. of tubes de-chocking & 1350 nos. hydro-jetting done rest in progress.


0

50

100

150

200

250

300

350

Load (MW) Vacuum (mbar) Total Air Flow (kg/s)Parameter

Unit-1 performance improvement

Before AOH

After AOH

Performance improvement after troubleshooting in Unit-1.

Parameters Before AOH After AOH % Improvement

Load (MW) 84 112 33.33

Vacuum (mbar) 302 137 54.64

Total Air Flow (kg/s) 113 133 17.70

Performance improvement after troubleshooting in Unit-2.

Parameters Before AOH After AOH % Improvement

Load (MW) 94 110 17.02

Vacuum (mbar) 296 95 67.91

Total Air Flow (kg/s) 115 126 9.57

A) Measures on Boiler Pressure Parts :

Combustor waterwall tube thickness survey

Inspection of SH-4 & RH-2 Omega tubes for any localized erosion.

Combustor intermediate wall tubes inspection at front an rear wall corners.

Above refractory transition zone shield inspection and replacement.

Inspection of corner tubes adjacent to cyclone entry

Roof tubes adjacent to cyclone entry gets inspected through thickness survey

This being pressurized boiler all the fins are inspected thoroughly and any

punctured/wear/tear is observed , shall be attended.

Second Pass hanger tubes and front wall tube thickness survey.

Second pass hanger tues and front wall tubes shield inspection and replacement.

Best Practice adopted to avoid unforeseen outage

B) Measures towards Refractory :

Physical inspection of cyclone refractory based on which future course of action takes place.

Thermography of cyclones to ensure internal condition of the overall refractory .

Based on thermography and visual inspection corrective measures is outlined.

Examination of vortex and corrective measures.

Inspection of all the eight loop seal bellows , inspection cyclone down comer to loop seal entry and return leg to combustor as damage of refractory in this area cusses deformation and oxidation of parent material.

Best Practice adopted to avoid unforeseen outage

Thank You

Best O & M practices at 2 X125 MW Akarimota Thermal Power...

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