Best Practices in Operation

(For Internal Circulation) COS-ISO-00-OIN/OPS/SYST/030

Rev. No. : 0 May 2009

OPERATION INFORMATION NOTE

Best Practices in Operation

CORPORATE OPERATION SERVICES

NTPC Limited

NTPC LIMITED

OPERATION & MAINTENANCE FORMAL DOCUMENTATION SYSTEM

OPERATION INFORMATION NOTE : COS-ISO-00-OIN/OPS/SYST/030

Rev. No.: 0 Date : May, 2009


Approved forImplementation by ……………………………………………………..

E. D. (OS)

Date: …………………………..

Enquiries to: Head of Corp. Operation Services


INDEX

S.N. Contents Page No.

1.0 INTRODUCTION 1

2.0 SUPERSEDED DOCUMENTS 1

3.0 BEST PRACTICES-GENERAL 1

4.0 BEST PRACTICES-STARTUP/ SHUTDOWN 5

5.0 BEST PRACTICES-NORMAL OPERATION 6

6.0 NORMAL OPERATION -STATION SPECIFIC PRACTICES 7

7.0 BEST PRACTICES-SCHEDULE CHANGE OVER/ CHECKING 10

8.0 SCHEDULE CHANGE OVER/ CHECKING - STATION SPECIFIC 11

9.0 BEST PRACTICES (TESTING OPERATION) 11

10.0 BEST PRACTICES-HEATE RATE IMPROVEMENT 12

11.0 BEST PRACTICES-APC REDUCTION 15

12.0 BEST PRACTICES-DM WATER REDUCTION 16

13.0 BEST PRACTICES-SPECIFIC OIL REDUCTION 17

14.0 BEST PRACTICES-OVERHAULLING AND RECOMMISSIONING 17

15.0 BEST PRACTICES-FORCED OUTAGE 19

16.0 NEW INITIATIVES 20

17.0 INSTITUTION BUILDING AND COMPETENCY 21

18.0 CONCLUSIONS 22

19.0 REVIEW 22

Page - 1COS-ISO-00-OIN/OPS/SYST/030 Rev. No.: 0

Best practices in Operation


1.0 INTRODUCTION

NTPC has achieved enviable performance levels in power generation. These achievements have come with steady improvements in O&M practices and strategies. Though Manufacturer’s recommendations and corporate guidelines are the basis for the O&M practices, experience gained over the years by the stations had helped in their improvement. Some of these best practices were shared in the last Head of Operations meet also.

However, the level of implementation of these practices / procedures varies from station to station. Also, some of the practices remain confined to individual stations. So a need was felt to compile the best practices followed at different stations for the benefit of our expanding fleet of stations. Some of the standard practices recommended by the different manufacturers are also included for emphasizing their regular implementation based on applicability.

Also, this document may help in institution building by serving as a good reference for the new entrants and as an update for the old timers.

2.0 SUPERSEDED DOCUMENTS - Nil

3.0 BEST PRACTICES-GENERAL

1) Standardization of all Operation procedures: Prepare detailed operation procedures for the unit and various equipments, in line with manufacturers’ recommendations/ CC guidelines covering all aspects of operation like, start up, shut down, normal operation, emergency handling, recommissioning, testing, preservation etc., with specific reference each type of unit/ equipment.

2) Review of all Operation procedures for improvement periodically: The laid out procedures shall be reviewed / updated regularly (preferably at a minimum frequency of once in two years or as per requirement-based on the addition of new units/ equipments or change in equipment or operating practices). The updated version shall be widely circulated and implemented.

3) Putting all Operation procedures on LAN: For wide circulation and easy reference. However a hard copy shall be maintained in each control room for better retrievability in case of emergencies.

4) Availability of details Important and critical incidents / activities with analysis on LAN. The details of important and critical incidents are to be put on LAN for wide circulation and easy reference.

5) Adherence strictly to Schedule Change-over: Schedule for change over of all equipments which have stand-by is to be prepared and to be followed strictly.

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6) Ensuring critical equipments availability and daily equipment trial run:

Availability of Equipments such as DC EOP,DC scanner Fan, DG Set and air motors of APH etc. are to be checked daily and the observations noted are to be mentioned in the log book

7) Use of standard checklist for all isolation and normalization: Standard check lists are to be used to avoid tripping during isolation & normalization of equipments and systems.

8) Improvement in the system by doing modifications: If any system requires modification for improvement, the required modification may be carried out as per COS-ISO-00-OD/GEN/006

9) Regular monitoring of parameters and improving them: Monitoring &

maintaining of parameters of boiler, turbine Generator and offsite at rated parameters on continuous basis.

10) Using of Lock Out boxes for PTW: For giving permit to 6.6 KV & 415 V equipments breakers/ modules are to be locked and key to be kept in lock out boxes.

11) Development of Web enabled Computerized Log Book for UCBs: Electronic log books (epilog) are envisaged as a part of RWE package. Stations to adopt epilog for their units and use it regularly, once it is made operational.

12) Availability of Technical documents on LAN: Technical Documents like Schematic Diagrams, Start Up / shut down Curves, Interlock Protections, Technical Manuals, Emergency Instructions etc are to be prepared and to be put on LAN. However one copy of these documents are to be kept in UCBs for reference.

13) Preparation and Implementation of operational strategy for enhancing unit Parameters in terms of Efficiency/ Heat Rate: Based on the Efficiency tests, the Heat rate punch list are to be prepared & strict implementation of the recommendations of the tests is to be ensured.

14) Preparation and Implementation of operational strategy for enhancing maximum profitability in ABT regime:

a. To maximize declared capability within the ambit of CERC regulations and achieving >85% DC for Fixed Cost recovery.

b. To put all out efforts to generate optimally looking into the frequency trends.

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c. To analyze the performance of station generation for the previous day block by block and to discuss in daily plant meetings regarding the shortcomings in generation in each block.

d. To monitor carefully the generation in each shifts as per the guidelines given by CERC.

e. Maintain generation / revise DC in time, so as not to incur negative UI.

15) Mock drill of Emergency once in three Months: Mock drill of emergency is to be carried out once in three months (or as per the frequency specified by the station department which ever is earlier) to rectify any slackness in emergency handling system.

16) Preparation and Implementation of Location Management Instructions (LMI): Preparation, revision and implementation of LMIs for all areas based on Technical Compliance documents (OD/OGN/OIN) issued from CC OS.

17) Special Schedule Checking for smooth, safe and efficient running of Units with good house keeping: Proper house keeping is to be maintained (particularly after Overhaul) to ensure smooth, safe & efficient running of equipments.

18) Monitoring of Unit start up/ stabilization time with reference time as suggested by manufacturer: Comparing the time period from unit startup to synchronization with the time period given by the manufacturer will help in eliminating any slackness in the system.

19) Periodic Checking of Control Air & Service Air Leakage: The control air & service air systems are to be checked on routine basis to identify any leakage in the system, arresting the leakages at earliest opportunity and draining of moisture from instrument air system.

20) Physical checking of SADC and Burner tilt: Physical checking of SADC & Burner Tilt is to be carried out on regular basis (once in a week). Reasons for any mismatch between local & UCB command are to be found out & to be rectified at earliest opportunity.

21) Multi-skilling of operators by periodic location rotation: Stage Rotation for Executives and Location Rotation for Non Executives on continuous basis.

22) Weekly joint checking of ESP fields & Rapping motors healthiness with EMD & BMD: Joint checking of ESP fields & rapping motors by a team of Operation, EMD, BMD on weekly basis and attending of defects at earliest opportunity.

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23) New ideas through Professional circle & Quality circles: Evolving new ideas through forums like Professional Circles and Quality circles, Deptt. & Safety Council etc.

24) Synchronisation of all machines through auto synchronizer: The units provided with auto synchronizers are to be synchronized through it.

25) Regular combined checking of Fire Protection System: Fire Protection System of Cable gallery/ cable vault is to be checked on regular basis (once in a month) by the team comprising of Operation, C&I, EMD.

26) 220V DCDB inter unit tie: Inter connection to be provided for reliability & flexibility and the modules to be marked with distinct colour for easy identification during isolation /normalization.

27) Displaying Danger Tag at Local and Switch Gear: Danger tags to be displayed at local equipment, switch gear and control room (if applicable) without fail with permit no. to prevent accidental starting of equipment.

28) Local utility Box: Installing a utility box in all control rooms with all essential tools & tackles like gloves, goggles, ear-muff, handles for opening drain valves, PTW tags etc.

29) Displaying emergency instructions: Instructions for emergencies like Hydrogen leakage, H2 purging etc at local for quick & ready reference.

30) Using of non contact type Temp. sensor in High Energy drains: High pressure/ temp. valve passing detection through portable non contact type temperature thermometer wherever online measurement is not provided.

31) Furnace temperature measurement: Furnace temp. measurement using Infrared thermometer/ optical pyrometer to optimize combustion & boiler performance

32) Usage of Hydrogen leak detector: Thorough checking of generator and gas system with hydrogen leak detector, if H2 consumption is higher than normal. If leakage is beyond limits the unit shall be stopped at the earliest.

33) Running best efficiency equipments: Running best efficiency equipments on merit order rating without jeopardizing the flexibility of operation.

34) Joint Protection checking of all Off-site equipments: Regular Planning and Joint Protection checking of all Off-site equipments (CW/ CT/ IAC/ PAC etc.)

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4.0. BEST PRACTICES-START UP/ SHUT DOWN

1) Optimum Startup & Shutdown time: Safe start up and shut down of units and its auxiliaries within minimum time as provided in the integrated start up procedure. Reference benchmarks can be made for further improvement.

2) Following of standard Procedure & Checklist: Preparation of Standard procedure & checklist for start up & shut down of each equipment. Following of these standard checklists during all start ups/shut down.

3) Strict adherence to startup curves: Adherence to start up curves and procedures to avoid thermal stress.

4) Adherence to OEM recommended boiler cooling procedure: Boiler cooling procedure as recommended by OEM is to be followed. Boiler fast cooling at higher rates to be avoided strictly.

5) On line monitoring of chemistry parameters: Operation persons are to be proactive in monitoring online chemistry parameters & take up the deviations with shift chemist.

6) Steam dumping after overhaul: Steam dumping after overhaul during startup for achieving better chemical parameters early.

7) Chemistry clearance before rolling of turbine: Chemistry clearance is to be obtained before turbine rolling.

8) Steam blowing after capital OH: Main steam pipe blowing through strainer as per the scheme given by corporate OS.

9) ATRS Rolling: Turbine rolling only through ATRS wherever available. Bypassing of steps shall not be resorted to except under unavoidable situations. Problems noticed if any during rolling shall be attended at the earliest.

10) Providing Thermocouple in High energy Drains: To detect passing of steam, the high energy drains are to be provided with thermocouple preferably on the upstream side of the drain valves.

11) Checking of High energy drains: Checking of high energy drains after every startup. Tightening of drain valves, if found passing. However keeping manual isolating valves closed is not advisable.

12) Quality of CW: Systems like Debris Filter, Condenser back washing, TWS at CW intake canal etc to be operated regularly.

13) Chemical treatment of CW water to avoid deterioration in condenser performance due to fouling and scaling.

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5.0 BEST PRACTICES-NORMAL OPERATION

1) Constant monitoring of parameters to keep them within limits and near to design value for better heat rate.

2) Avoiding MS/ HRH temp. excursions during all operating conditions.

3) Monitoring trends of multiple parameters simultaneously.

4) Training to be imparted to operation executives about importance of chemistry in plant and its short-term, long-term impact on boiler and turbine.

5) Isolation & normalization are to be followed through ERP Plant Maintenance module where detailed procedure is already entered.

6) A senior operation executive shall be involved during switchyard isolation/ normalization.

7) Continuous monitoring of Generator parameters: Stator current, MVR, slot temp, winding temp etc at higher loads.

8) Checking of Emitter rapping and collector rapping mechanisms of all fields in all units on daily basis.

9) Online monitoring of SPM in all units and display in control room and LAN.

10) Periodic Inspection of ESP: If more than 2 fields are out of service in a particular pass it is to be isolated and fields to be rectified.

11) DO levels in condensate shall be monitored: Regular checking of CEP in service, Makeup water etc for DO variation in condensate. Any air ingress into the condenser to be attended.

12) Maintaining & monitoring Aux PRDS: Rated parameters of Aux steam to be maintained to avoid barring gear stopping problem and to ensure proper working of steam ejectors. For this source of aux steam to be optimized and adequate draining is to be ensured.

13) Walk down survey: Weekly walk down survey for leakages to reduce DM water consumption.

14) Water Wall Soot Blowers & LRSB: Tier wise and requirement wise WWSB operation & Optimised operation of LRSB is to be done. Soot Blower pressure checking on regular basis is to be carried out to ensure effectiveness of blowing. Regular inspection & Gap Setting of Wall blower is to be done to avoid direct impinging of steam on tubes. Soot blowers retract position checking after every soot blowing is to be ensured.

15) Maintaining proper records, for verification at a later stage, history, RLA etc.

16) Operation executives shall be aware of relevant codes and their latest revisions (Grid Code, NFPA, CERC guidelines etc) and follow them.

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17) Ensuring healthiness/ readiness of standby equipments, supplies: The healthiness of standby by equipments is to be ensured by periodic checking & attending to the problems.

18) Aging Machines- Extra care and vigil to be observed to avoid outage on account of aging of machines. Early identification and rectification of defects to be resorted to reduce outage.

19) New Machines- Parameter deviation (from design) observed in many units. Maintain safe operating limits (steam temp, metal temp, first stage pressure etc.)

20) Regular checking of oil guns to ensure availability for emergency oil support and start up.

21) Optimization of Spray: Right mix of burner tilt and attemperation to control metal / steam temp.

22) Monitoring of coal pipe temperatures: Close monitoring of coal pipe temperatures for early detection of coal pipe choking to avoid mill outage.

23) Trial run of important auxiliaries: Whenever trial run of some important auxiliary (CW pump, Cond. Extraction pump etc) is taken after Overhaul or breakdown maintenance, all important parameters like vibration, temperatures etc. are to be closely monitored and recorded for sufficient duration to observe their trends.

24) Adherence to Turbine ATT (Protective devices & Valves) as per schedule.

25) Ammonia dosing at ESP inlet: Regulated dosing of Ammonia at ESP inlet to keep emission within limits.

26) Follow all steps during isolation, normalisation, start up and regular operation.

27) All protections are to be kept in service. If it is to be bypassed under unavoidable circumstances, standard procedure to be adhered. Extra vigil to be maintained during the period of protection non availability. Bypassed protections to be normalized at the earliest opportunity.

28) Urgency is not an excuse for compromising equipment & human safety. Even under pressure the basics of Operation shall not be compromised.

6.0 NORMAL OPERATION-STATION SPECIFIC PRACTICES

A. BEST PRACTICES-NORMAL OPERATION-KORBA

Turbine 1st stage pressure counter and alarm provided in both Stage-1 &2, it gives the integrated time in minutes for which the 1st stage pressure crossed the permissible value.

Condenser Ball cleaning system kept in service 24 Hrs in all 500MW units.

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Stage-1 units (except U-3) Drum level Control is changed from FRS DP to BFP scoop control. The control loops incorporated in DAS. Resulting in power saving of 200KW/Unit.

Stage-I Units AOP#2 supply given from Emergency switchgear.

MOT level indicator provided in control room and level drop rate alarm provided

Switchyard Air compressor & lighting supply provided from DG sets: Easy handling of grid emergencies.

Extensive use of Digital camera helped in better plant housekeeping.

Deployment of CCTV for continuous Bottom Ash Hopper monitoring (U#5).

B. BEST PRACTICES- START UP MONITORING -RIHAND

Standard curves were developed for each type of start up.

Start up time is compared with ideal and best achieved curve and discussed during planning meeting.

Corrective action is taken for the deviations observed during start up, for improvement.

C. BEST PRACTICES- OUTAGE ANALYSIS-SIMHADRI

‘Power play’ Scheme is developed to play back the information from DDCMIS to reconstruct the events in the past for better analysis of emergencies.

It facilitates a virtual reality very close to the actual situations as if the emergency is currently experienced; Helps in better analysis and training.

The scheme has facility for replay and pause similar to video.

D. BEST PRACTICES-NORMAL OPERATION FOR LUB OIL MOISTURE IMPROVEMENT-TSTPS

Seal Steam pressure optimized to 250 mmwc from 350 mmwc.

MOT centrifuge inlet outlet moisture is monitored.

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MOT tank vacuum is maintained at 40-50mmwc.

Bearing pedestal vacuum is maintained at 10-15 mmwc.

E. BEST PRACTICES-NORMAL OPERATION-AURAIYA

Load hunting and malfunctioning of GT E/H valves were taking place due to deterioration of control oil quality during GT in service.

Portable oil purifier incorporated for online filtering of control oil to enhance GT control oil quality.

Monitoring of GT Compressor efficiency which indicates the qualitative performance as well as the safe margin of operation of the compressor above the surge line.

When the efficiency is deteriorating, “Wet Cleaning” is carried out to restore the efficiency.

F. BEST PRACTISES-NORMAL OPERATION IMPROVEMENT OF NAPHTHA SYSTEM HEALTHINESS BY KEEPING NAPHTHA SYSTEM ALWAYS IN LINED-UP CONDITION-AURAIYA

Earlier filter choking, nozzle chocking and MFOP jamming problem was observed in naphtha system due to rust formation in naphtha lines by stagnant naphtha.

Now, if GT is not running on naphtha its system is being kept in lined-up condition to ensure circulation of naphtha through the system by running one Transfer Pump.

Regular trial of MFOP is taken to ensure its healthiness.

G. BEST PRACTICES-NORMAL OPERATION GT LIQUID FUEL OPERATION-KAWAS

In case of GT tripping on naphtha, Heavy Purging is required.

Before initiating Heavy Purge sequence, we are force-opening the HSD stop valve and manually flushing the fuel lines with HSD, ensuring complete purging of naphtha.

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H. BEST PRACTICES-NORMAL OPERATION-NAPTHA HANDLING-KAWAS

Following practices are adopted for safe operation:

One valve in each pipeline (tank filling, drain tank return, tanker unloading and The moisture in ST control fluid is being maintained at low levels (< 300 ppm)

by providing dry air (instrument air) blanketing over the control fluid surface inside the tank.

7.0. BEST PRACTICES-SCHEDULE CHANGE OVER/ CHECKING

1) Implementation of change over schedule: Preparing a change over schedule of all equipments having stand by & following change over schedule strictly.

2) Following checks are to be carried out in Shifts:

a) Vacuum checking of each line during shift starting.

b) Soot blowers retract position checking after soot blowing.

c) Furnace checking for any tube leakage.

d) Furnace checking for any ash build up

e) Bottom Ash hopper checking for any ash build up.

f) Turbine valve room checking for any oil leakage

g) Turbine minus meter checking for any water accumulation.

h) Boiler Firing floor inspection for any oil leakage

i) ESP hoppers checking for any ash build up.

j) Turbine MOT room checking for any oil leakage

k) Following of walk down check list, specific to site.

3) Following Schedule checks are to be carried out:

a) ESP Hopper heaters, CERM/ EERM healthiness checking twice/ week

b) ESP, APH hopper healthiness checking.

c) Joint ESP inspection during every opportunity like BTL, O/H and whenever

ESP pass is under shutdown.

d) ESP ash evacuation: For dry mode of operation, schedule for leakage identification and rectification at proper air pressure.

8.0 SCHEDULE CHANGE OVER/ CHECKING- STATION SPECIFIC

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A. ID FAN Schedule Change Over-SINGRAULI

ID fan change over was done once in a month. This resulted in increased level of vibration due to sagging of the shaft of standby ID fan. Frequent balancing was required to bring down high vibration.

Vibration levels were found high even after changer over frequency was increased to once in fortnight. After resorting to cooling of ID fan shaft during stopping, vibrations were found to be stable.

9.0. BEST PRACTICES- TESTING (OPERATION)

1) Interlock & Protection Checking: Interlock /protection checking of all auxiliary equipment and unit after every overhaul as per OD/OPS/SYST/007.

2) Carrying out ATT: ATT (Valve & protective) checking on regular basis as per LMI.

3) Actual Over speed testing of Main turbine & BFP turbine as per LMI (once in a year).

4) Oil Injection test of Turbine regularly as per LMI.

5) Checking of auto start of Fire fighting pump in case of low pressure.

6) Checking of Sprinkler system of all transformers: Checking of Sprinkler system of GT and other transformers with actual operation as per CC guidelines (once in three month).

7) Checking of deluge valve: Scheduled operation checking of deluge valve (mulsifier system) of GT/UAT/ST/ICT etc.

8) DC lighting testing: DC lighting testing is to be done once in a week.

9) Smoke detector testing: Smoke detector testing is to be carried out once in a month.

10) Ensuring the following tests:

a) Transformer Oil - Dissolved Gas Analysis

b) Lub Oil Moisture Checking - Weekly

c) FRF Oil Acidity Checking - Weekly

d) Hydrogen Purity/ Dew Point - Weekly

e) Stator Water dissolved Oxygen and pH

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10.0 BEST PRACTICES- : HEAT RATE IMPROVEMENT

1) Daily heat rate deviation discussion in daily planning meeting.

2) Heat rate deviation discussion based on weekly average in daily planning meeting and review of action plan for major deviations.

3) Using software package for real time performance analysis & efficiency optimization.

4) Merit order operation of the units.

5) Continuous on line monitoring of combustion with CO/ O2 analyzer. Dry flue gas loss reduction through excess air optimization.

6) Proper closing/ sealing of manholes and peep holes to reduce tramp air entry into the boiler.

7) Optimization of tempering air to mills. Hot primary air temp shall be maintained near rated values by controlling the flue gas dampers.

8) Mill outlet temp. maintaining around 90 deg.

9) Regular monitoring of combustibles in Bottom ash/ Fly ash and correlating with PF fineness and other combustion variables.

10) Trending of SH/ RH spray levels for early identification of deviations.

11) Auto operation of burner tilt to control reheat spray and temp gain.

12) Regular monitoring of condenser vacuum and backwashing as per requirement. Monitoring of condenser performance by on-line kenetometer.

13) Condenser Pass cleaning by load reduction on available opportunities (Low SG period / Partial loading during Equipment outage/ Grid restriction/ short shutdown / etc).

14) Planned CT Fill cleaning. Cold Basin cleaning during O/H.

15) Monitoring of CEP Gland seal water & supplying only from CEP discharge header.

16) Regular checking of air ingress to Condenser by monitoring Vacuum Pump discharge quantity.

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17) Arresting air ingress points of condenser through physical inspection & Helium leak detection test .

18) Monitoring of Ejector/ Vacuum Pump performance.

19) Optimized operation of On Load Tube Cleaning system.

20) Maintaining of Chemical regime of CW system by proper chemical dosing so that vacuum is maintained around –design value from Overhaul To Overhaul

21) Condenser cleaning by hydro-jetting during overhaul.

22) HP/LP Heater Performance Optimization by adjusting

a) Level, Outlet and Drip Temp.

b) Parting Plate Inspection in overhaul

23) APH performance monitoring by regular testing and operation of ALCS (500 MW units) accordingly.

24) Optimization of ARCW (Auxiliary Raw Cooling Water) pumps and AWU (Air Washer Units) operation.

25) Identifying and attending instrument and plant air leakages during unit shut down, which results in reduction of compressor running hours.

26) Regular energy audits and implementation of recommendations.

27) Implementation of on line Energy Management system.

28) Regular monitoring of flue gas outlet temp. and DP across APH .

29) APH hot water washing during opportunities.

A. FISHER NET IN CW INTAKE CANNEL: SINGRAULI

In 2005 during rainy seasons floating debris / grass clogged the Traveling Screen and also choked the Condenser Tubes causing Gen Loss of 14.53 MUs.Following initiatives are taken to avoid the re-occurrence.

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Installation of good quality of Nylon net in combination with fishing net in intake channels.

Provision for height adjustment of the nets as reservoirs level rises.

Arrangement for adequate lighting in evening & night.

Round the clock work for lifting the debris from intake.

Deployment of adequate boats with sufficient manpower.

Arrangement for floater in addition to boats.

B. IMPROVED PROCEDURE OF CALCULATION OF CALORIFIC VALUE OF GAS FUEL-AURAIYA

Earlier the CV of fuel gas was being taken only once in a day. This was causing inaccuracies in the fuel billing and Heat Rate calculation.

After taking up with GAIL authorities, the CV of gas is being taken two-hourly and average of 12 values is taken as the CV for the day from Sept 2000 onwards.

This resulted in getting better representative value of CV and more accurate gas billing.

C. CONDENSER WATER BOX CLEANING DURING FULL MODULE OPERATION-AURAIYA

EARLIER PRACTICE: Condenser water box cleaning was carried out during water box chocking, at half module operation or at ST S/D to avoid loss of condenser vacuum.

NEW PRACTICE: Condenser water box cleaning is being done in full module also, at partial loads, especially during winter months without any sacrifice of condenser vacuum.

D. USE OF INLET AIR FILTER WRAP TO REDUCE AVERAGE GT IAF DP-AURAIYA

Earlier average GT inlet air filter DP during the year was approx. 8-10 inch of W.C. and it was reaching up to 12-14” of WC at the time of replacement of inlet air filter just before winter.

After the use of filter wrap average filter DP has came down to 4-6 inch.

of WC. Filter wraps are easy to clean and no need to stop the unit.

E. OPERATION PRACTICES-DADRI-GAS: IMPROVEMENT IN CT PERFORMANCE

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CT fans switched off(with water isolation) during winter/half module operation, maintaining CW temperature and vacuum.

11.0. BEST PRACTICES-APC REDUCTION

1) Stopping of CT Fans during winter season to reduce APC.

2) Arresting air leakage & Optimizing no. of Compressors (Instrument & Plant air)

3) Running 2 CEPS instead of 3 & optimizing no. of CW pumps in winter season.

4) Interconnection of Stage -1 & 2 Compressors.

5) Proper Coal blending to be carried out to restrict to 4/7 mill operation.

6) Regular checking of recirculation valve passing of TDBFP /CEP through temp gun.

7) On Line Energy Measurement / Power consumption of Major Equipment

8) Optimizing number of lights in service

9) Optimizing the interval between bottom ash flushing to save power and water

A. OPERATION PRACTICES-DADRI-GAS

One CEP in service during half module operation

Steam turbine designed with 3 x 50% CEP pumps.

During half module operation (one WHRB) two CEPs were generally kept in service.

Now during half module operation one CEP is kept in service keeping common header pressure within desirable limits.

APC of 175kw is saved on continuous basis.

B. OPTIMISATION OF CW PUMP OPERATION-DADRI-COAL

During winter season (months of DEC to FEB) advantage of low ambient temperature taken.

Six out of eight CW pumps are run (isolating one Cooling Tower)

To reduce aux. Power consumption

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Reduces Cooling tower plume, which falls on switchyard area thereby reducing tracking on insulators.

C. BFP RECIRCULATION VALVE PASSING AND RECTIFICATION-DADRI-COAL

BFP R/C valve major contributor to Aux. Power wastage.

Regular checking done by noting the flow difference after closing of manual R/C valve.

Minor passing by checking the downstream temp. by Temp. gun.

BFP R/C valves replaced with Drag make (USA) valve in a phased manner.

12.0. BEST PRACTICES-DM WATER REDUCTION

1) Monitoring DM water consumption in each shift.

2) Monitoring Soot blowing drain valve passing.

3) Monitoring passing / simmering of Boiler Safety valves, HPH /LPH safety valves using non contact thermometer.

4) Special teams may be formed for identifying and reporting the DM water/steam leakages in various units & offsite locations.

5) Attending water/steam leakages as early as possible.

A. RECYCLING OF STEAM SAMPLES TO REDUCE DM WATER CONSUMPTION-KAWAS

Passing of drain valves is identified by opening the man hole of boiler

drain tank while doing hydro test.

Continuous samples from the boiler drum and steam lines are going to SWAS room for measurement of pH and conductivity. After analysis these samples are going to drain pit.

Now the steam samples after analysis are sent back to CST tank with the help of a pump.

13.0. BEST PRACTICES-SP. OIL REDUCTION

1) Documented standardized startup & shut down procedure are to be prepared & adhered to.

2) Unit start up times is to be critically examined.

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3) Startup after Annual Overhauling is to be properly planned in consultation with maintenance groups.

4) Maintaining healthy Fuel oil heating, atomizing and tracing steam system at burner front.

5) Maintaining healthiness of Oil guns and regular availability checking by actually taking it into service. Issues related to oil gun performance to be addressed to ensure trouble free light up.

A. STATION SPECIFIC –KORBA

Start up activities are broken down to small activities like light up, parameter rising, safety valve floating, testing, rolling and stabilization etc. and benchmark figures are compiled for each of them. During each start up, oil consumption for each of these activities is compared with the benchmarks. Reasons for deviations are analyzed and corrective action is initiated for improvement.

14.0 BESTPRACTICES-OVERHAULING& RECOMMISSIONING

1) Recommissioning team to be formed well in advance for proper coordination of overhaul activities. Recommissioning schedule to be prepared and followed for timely completion of all activities in sequential manner avoiding last minute rush

2) Preparation of check lists, protocols, procedures & extensive use of them during recommissioning of all equipments.

3) Adherence to Pre start & start-up checklists for boiler and turbine to be ensured by a senior operation executive. Completed checklists to be duly signed and preserved for future reference.

4) Elaborate defect list to be prepared and incorporated in the scope of work to ensure the liquidation during overhaul.

5) Participate in Inspection teams and assist to supervise overhaul jobs.

6) An experienced senior operation executive to monitor activities/ critical parameters in UCB & coordinate with maintenance.

7) One representative each from BMD, TMD, EMD, C&I shall be available in UCB for coordination.

8) Written clearance, as per LMI, from Senior chemistry executive for steam parameters to be taken before start of rolling.

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9) Water is to be taken into boiler only after proper deaeration and chemical dozing.

10) Physical checking of SADC and Burner Tilt during all units shut down.

11) Using boiler fill pump in place of Motor Driven BFP for boiler water filling during re commissioning.

12) Steam Blowing of MS lines after major overhauling of the boiler.

13) Air tightness test of Boiler during shut down/ overhauling to identify defects. Test may be repeated after attending all defects, before light up.

14) Setting of safety valves (spring loaded and ERVs) of MS and RH as per CC guidelines.

15) Re-commissioning of APH soot blower, fire nozzle, water washing nozzle etc and other requirements for preventing APH fire before unit light up.

16) Fire Fighting system checking of Lube oil / Seal Oil / GT /UATs/ Boiler etc.

17) Checklist and Protocols are to be properly filled & signed.

18) Interlock and Protection checking of all equipments / systems with standard protocols.

19) Auto closing scheme of Bus Couplers of various switchgears/ MCCs to be tested and kept ready.

20) Check and ensure readiness of Unit Bus breakers in all respect before supply change over.

21) Load Test of Battery to be carried out at recommended frequency.

22) Load test of DG set during unit overhaul with sufficient load.

23) Periodic protection checking of offsite equipments before and after overhauling (DG set, Compressors, CW Pumps etc.).

24) Checking of emergency equipments after supply restoration.

25) Cleaning and inspection of MOT (once in two years) & Control Fluid Tank (as per recommendations from CC-OS) during overhauling.

26) Deaerator storage tank heating before cold start-ups to bring down dissolved oxygen levels.

27) Check oil carry over at APH during cold start up.

28) Ensure availability of alarm/ warning systems in the case of abnormal temperature rise at APHs.

29) Deployment of operation personnel for major activities like inspection, testing etc. to ensure round the clock monitoring for quality.

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30) Proper coordination between various maintenance agencies and recommissioning team is to be ensured to achieve desired targets.

A. NEW PRACTICE (OVER HAULING)- DADRI-COAL

RH safety valve setting being done before boiler shut down if no work is planned on S/V during O/H.

APH water washing done till pH value of water before & after stabilizes

Air pressurization test of Boiler done after overhauling to identify leakages

Charging only two (out of four) ESP passes during cold start up.

15.0 BEST PRACTICES-FORCED OUTAGE.

1) Tripping analysis of all the trips of NTPC plants, specially tripping due to human error is to be discussed.

2) Analyse all outages, failures etc, to find the root cause and implement recommendations/ preventive measures.

3) Stopping of the unit and equipments in time to reduce secondary damage in the event of uncertain incidents.

4) Discussion of case studies with operation staff on regular basis with remedial measures.

5) Detailed analysis of unit trips and near miss trips are to be discussed in each group and in each UCB.

6) Preparation and circulation of Check list of starting and stopping of all equipments.

7) Proper recommissioning of all equipments as per standard checklists during Overhaul.

BEST PRACTICES-FORCED OUTAGE- STATION SPECIFIC

A. REDUCING FORCED OUTAGE BY CHANGING FUEL CHANGEOVER LOGIC-AURAIYA

As per original logic of “Fuel Changeover”, Main Fuel Oil Pump (MFOP) was required to be kept in auto mode before giving changeover command, and if MFOP did not start within 5 seconds the GT got tripped.

Now, after logic modification fuel changeover command can be given without selecting MFOP in auto mode. As per present logic, we start MFOP in SWGR mode before giving change over command, and MFOP is changed to Auto mode after fuel changeover is complete.

Thus MFOP healthiness is ensured before fuel changeover.

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B. ROOT CAUSE ANALYSIS AND MODIFICATION-DADRI-COAL

For system availability, better performance and better safety various modifications have been carried out.

Few of important modifications are:

APH motor supply shifting to EMCC.

ID FAN VFD supplies (DC and LT) modification.

Shifting of lube oil MCC supplies from ESP MCC to Boiler MCC.

AOP/JOP supply modification.

Providing time delay in seal air fan discharge damper opening.

Flame scanner supply distribution from UPS and FSSS.

Immediate starting of stand by LOPs of ID/FD/PA fans.

16.0 NEW INITIATIVES

A. UNCHAHAR

Commissioning of Mill Reject System of Stage-1 completed

22 numbers LRSB in unit -II and 6 numbers in unit -I commissioned first time since take over.

220 KV SWYD bus sectionalisation done and ST- II bus coupler commissioned.

Oil gun tracing (electrical) heater attended in both stage-1 units.

B. SINGRAULI

Coal Bunker Arching Removal

Stage-I Unit Coal Bunker stuck up with sticky coal in one side due to old design bunker of Trapezoidal shape.

So Arching removal of all the bunkers of Stage I Units is performed on regular basis to avoid bunker run out and Fire Hazard also.

C. KAHALGAON

Opening of seal steam header drain once in a day to avoid occasional condensation---Eccentricity variation problem resolved.

Installed guide plates at ESP inlet at unit-4 and conducted GD test.

SH spray line backwashing helps in reducing choking of the nozzles.

D. KAWAS

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As per original scheme, the standby CW pump can be connected to any one block by opening its header valve towards that block. Now it has been modified for simultaneous opening of header valves towards both the blocks.

All the important schematics of gas turbines are reproduced by using AutoCAD software and displayed in central control room for easy reference.

Compressor wet washing valves relocated.

Display of valves nos. at various elevations in all boilers.

Installation of timers in phosphate dosing p/ps for exact dosing.

Making water level gauges (CW and RAW Water) with radium tapes to increase the visibility.

Polymer coating of the CW pumps.

Online washing of compressors.

Accurate GT and compressor efficiency calculation through mathematical model.

E. DADRI-COAL

Blow down of CW fore bay water which is known as service water is being reused for following purposes-

Crusher cooling in Coal handling plants.

Spray water in Coal Yard and track Hopper.

Cleaning purpose in plant.

Pole cooling in HVDC.

Spray water in ash mound

Horticulture (watering gardens).

17.0. INSTITUTION BUILDING AND COMPETENCY

1) Conducting Daily Operation Review Meetings.

2) Regular Communication meetings by HOD with operation personnel to share latest developments and other important information related to other stations.

3) Sharpening of skills through training (simulator, workshops, seminars, group discussions etc).

4) Transfer of vast knowledge and experience of senior executives of operation and maintenance departments to new entrants through hand holding, mentoring etc.

5) Blending of experienced and fresh executives in shift operation for better operational control and grooming.

6) Conducting regular feedback session head of operation department.

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7) Encouraging operation executives to take decision during emergencies in the overall interest of the station upholding safety of men and machines as supreme.

8) Ensuring participation of new executives in recommissioning activities after unit overhauling.

18.0 CONCLUSIONS

Islands of knowledge are not helpful to overall development of expertise in any field. Only with proper dissemination of knowledge to the frontline operation staff we can hope to bring out best results. It is expected that all stations shall adopt the best practices compiled in this document and implement it in true spirit to take our performance to still higher levels.

19.0 REVIEW

The Executive Director (OS) will be responsible for reviewing the document every 2-years or as necessary.

NTPC Limited

Document for Distribution to:

CONTROLLEDI. Power Stations

1. Head of Station Rihand

2. Head of Station Vindhyachal

3. Head of Station Kahalgaon

4. Head of Station Farakka

5. Head of Station Dadri (Coal & Gas)

6. Head of Station Unchahar

7. Head of Station Korba

8. Head of Station Ramagundam

9. Head of Station Badarpur

10. Head of Station Talcher Kaniha

11. Head of Station Anta

12. Head of Station Kawas

13. Head of Station Simhadri

14. Head of Station Singrauli

15. Head of Station Sipat

16. Head of Station Tanda

17. Head of Station Talcher Thermal

18. Head of Station Auraiya

19. Head of Station Jhanor Gandhar

20. Head of Station Faridabad

21. Head of Station Kayamkulam

UNCONTROLLED

II Regional Head Quarters22. RED (N) Lucknow

23. RED (S) Hyderabad

24. RED(W) Mumbai

25. RED(ER 1), Patna

26. RED(ER 2), Bhubaneswar

27. RED (NC) Noida

III Corporate Head Quarter28. STA to Chairman & Managing Director, SCOPE, New Delhi

29. STA to Director (Technical), SCOPE, New Delhi

30. STA to Director (Operations) , SCOPE, New Delhi

31. STA to Director (Commercial), SCOPE, New Delhi

32. STA to Director (Projects) , SCOPE, New Delhi

33. Executive Director, PMI, Noida

34. Executive Director (Engg.), EOC, Noida

35. Executive Director (OS),EOC, Noida

36. General Manager (R&D), Noida

37. General Manager (CENPEEP), Noida

38. Concerned Group Heads in Operation Services, CC

IV Head of O&M39. Singrauli 40. Korba 41. Ramagundam 42.Farakka

43. Rihand 44. Vindhyachal 45. Kahalgaon 46.Dadri(Coal)

47. Unchahar 48. Talcher Kaniha 49. Talcher Thermal 50.Badarpur

51. Simhadri 52. Auraiya 53. Gandhar 54.Kawas

55. Anta 56. Dadri (Gas 57. Kayamkulam 58.Faridabad

59. Tanda 60. Sipat

V Head of Operation61. Singrauli 62. Korba 63. Ramagundam 64.Farakka

65. Rihand 66. Vindhyachal 67. Kahalgaon 68.Dadri(Coal)

69. Unchahar 70. Talcher Kaniha 71. Talcher Thermal 72.Badarpur

73. Simhadri 74. Auraiya 75. Gandhar 76.Kawas

77. Anta 78. Dadri (Gas 79. Kayamkulam 80.Faridabad

81. Tanda 82. Sipat

Best Practices in Operation

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