Dadri station Highlight April to Sep 25

 

How to detect Boiler tube lkg in boiler

 **Detecting Boiler Tube Leakage in a 210 MW BHEL Boiler at NTPC Dadri**

Boiler tube leakage is a critical issue in power plants like NTPC Dadri’s 210 MW units, which use subcritical BHEL-designed boilers (Combustion Engineering type, commissioned 1991-1994). Early detection minimizes downtime, prevents secondary damage (e.g., to turbine or other tubes), and maintains efficiency. Dadri has a strong record for minimizing tube failures, ranking among NTPC’s top plants, but leaks can still occur due to aging (30+ years), erosion, corrosion, or thermal stresses in high-pressure zones (drum pressure ~155 bar, superheater ~535°C). Below is a detailed guide to detecting boiler tube leaks, tailored to Dadri’s 210 MW BHEL boilers, combining practical methods, NTPC practices, and industry standards.

Safety Valve float Test

 **Safety Valve Float Test in a Boiler (Specific to Power Plant Context like NTPC Dadri 210 MW Boiler)**

The safety valve float test, also known as the "popping test," is a critical procedure in a power plant boiler to verify that safety valves open at their designated set pressure to prevent overpressure conditions, ensuring boiler safety and compliance with regulations like the Indian Boiler Regulations (IBR) 1950. For a 210 MW boiler at NTPC Dadri, this involves testing drum and superheater safety valves (typically set at 155-160 bar for drum and 135-140 bar for superheater). Below is a concise, step-by-step guide to performing the safety valve float test, tailored to subcritical boilers like those at NTPC Dadri, with practical insights from thermal power plant operations.

Biomass Co-firing Operating Procedure

 

1)    Mill Operating Parameters and Operation procedure: -

Ø  Maintain Mill outlet temperature-> 55C

Ø  Mill inlet temperature -> not more than 180 C

Ø  Observe all 4 coal pipe temperature of Mills with biomass regularly. In case of any deviation from rest of the pipes(any abrupt rise or fall), stop the mill and give PTW for inspection.

Ø  Pre start and post shutdown purging of mill is mandatory.

Ø  Continuous monitoring of mill parameters most importantly mills inlet air temperature, mill outlet temperature, mill current and mill DP.

Mill Ignition Permit

TG Oil Flushing Procedure

TG OIL FLUSHING PROCEDURE

PURPOSE:

• · This document is prepared to guide the operation personnel to line up  for Lub oil Flushing  and achieve desired oil Parameters
  

SCOPE:  

• · This shall be applicable to the MOT Lub oil system of Stage-1 (210 MW*4) & Stage-2 (490MW*2)
  

PRECONDITIONS OF STARTING TG LUB OIL FLUSHING

S No	ACTIVITY	Responsibility	Status
1.	Ensure MOT inspection & Pedestal closing clearance and Lub oil flushing Clearance from TMD and C&I.	Operation
2	MOT Drain, Coolers drains and filters drain and vents are closed	Operation
3	MOT  level is >Low and <High	Operation
4	All Instruments root valves are charged, & all instruments are healthy	C&I
5	No insulation work is to be carried out on TG module and on its bearings during flushing & bearings pedestal area is to be maintained clean.	TMD
6	Check one cooler, whose oil side as well as water side are lined up, in service	Operation
7	MOT centrifuge is in service with purifier mode	TMD/Operation
8	One VEF in service	Operation
9	Provision of line filters in lub oil lines	TMD
10	Clean baskets strainers are put in MOT.	TMD
11	Availability of Lub oil pumps with P&I in service	Operation
12.	First DCEOP to be started for filling/venting of lines. Then DCEOP to be stopped &  AOP to be srated. Check AOP discharge pr., current & MOT level.	Operation

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13.	MOT level will start dropping. Monitor the same and take necessary precautions.	Operation
14.	See oil flow through each bearing return oil pipe.	Operation
15.	Inspect all pedestals for oil leakages ( both external and from internal fittings, hoses , gauges,etc).	Operation
16.	Check for any oil leakage in MOT room, oil canal & pedestal area.	Operation
17.	Monitor choking of duplex filter.	Operation/TMD
19.	MOT coolers are filled and venting done.	Operation
20.	Stop AOP and clean the Oil line filters and MOT basket strainer after first four hours of oil flushing.	Operation/TMD
21.	Clean duplex filter when choked more than 50%	TMD
22	Collection samples from MOT tank, Centrifuge inlet & outlet	Chemistry
23.	When frequency of cleaning   of duplex filter reduces considerably and simultaneously clearance is received from chemistry department of mechanical impurities and moisture (both < 100 ppm) , oil flushing is stopped .	Operation/TMD/chemistry
24.	Basket strainer is removed, cleaned and put back in position.	TMD
25.	Remove oil line filters and replace with oil throttles.	TMD

Completion Criteria:  

• · Mechanical Impurities & Moisture Content in samples are less than 100ppm by weight
  
• · MOT strainer should remain clean after 24 hours of TG Oil flushing
  
• · There should not be any hard particle in line filters
  
• · Duplex filters are required to be cleaned after 12 hours of oil flushing
  

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CHECK LIST FOR PUTTING TG ON BARRING

Sr. No	ITEM DESCRIPTION	Responsibility	Status
1	Clearance from C&I, TMD, chemistry before putting on Barring	Operation
2	Oil vapour extractor Normalised & ON	Operation
3	Generator bearing chamber exhauster ON.	Operation
4	Check for local line up of lube oil and jacking oil systems.	Operation
5	All pipe connections are OK.	Operation/TMD
6	Check lift of rotor journals at all bearing pedestals.	TMD
7	Check hand barring is free prior to putting oil barring.	Operation/TMD

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NTPC dadri Information

 NTPC Dadri power plant, also known as National Capital Power Station (NCPS), is a coal and gas-fired thermal power plant located in Uttar Pradesh, India. National Thermal Power Corporation (NTPC) is the project owner.

With a total installed capacity of 2.63GW, the Dadri power plant is one of the biggest thermal power plants in India and the only coal and gas-fired power plant in the country. Of the total power generated, 1,820MW comes from the coal-fired plant and the remaining 817MW from the gas-fired plant.

Dadri S/Y Line loading

 

                                                      NTPC-DADRI TRANSMISSION LINE LOADING

 

Lines                         conductor           SIL             CA           Cent clair     stability       thermal             operation

                                                                                                    graph mw       mw          limit mw             limit mw

 

Maharanibag  54km                            692          2371              2371        5896               1962                 1962

Mandaula 1&2  46km                         692           2533             2533        6923                1962                 1962

Greater Noida 13 km                          692           3679             3679       24179              1962                 1962

Malerkotla 297 km                             517             560                692           811                852                    852

Panipat 1&2  112 km                          517             1247            1247          2145             852                 852

Murad nagar  33 km                           517              2143            2143          7280             852                 852

Dadri Switchyard

Dadri: biomass Operating Procedure

 

1)    Mill Operating Parameters and Operation procedure: -

Ø  Maintain Mill outlet temperature-> 55 C

Ø  Mill inlet temperature -> not more than 180 C

Ø  Observe all 4 coal pipe temperature of Mills with biomass regularly. In case of any deviation from rest of the pipes (any abrupt rise or fall), stop the mill and give PTW for inspection.

Ø  Pre start and post shutdown purging of mill is mandatory.

Ø  Continuous monitoring of mill parameters most importantly mills inlet air temperature, mill outlet temperature, mill current and mill DP.

Ø  Mill inlet temperature should not be more than 180 C in any case

Ø  Mill reject system to be kept under observation continuously

Ø  Operator should be deployed at local for monitoring in wake of fire hazard.

Ø  In case of fire, mill should be tripped and steam inerting should be done immediately by opening steam interting motorized valve, keeping watch on furnace pressure.  Fire tender may also be used if required.  

Ø  Clinkering and slagging tendency to be observed from local as well as from rise in SH zone FG temperature. Soot blowing and LRSB to be done accordingly.

SOP for Mills Operation along with Bio Mass

 1) Mill Operating Parameters and Operation procedure:

Bunker fire : Prevention

Bunker fire

PREVENTION OF BUNKER FIRE

 Ensure Feeder outlet gate closes on auto when Feeder stopped/tripped. Otherwise give
a close command for closing.

APH Hot Washing

1 Water washing of air heaters should be carried out in hot condition after boiler shutdown.Flue gas inlet temperature should be between 200 deg C to 150 deg C
2 Both FD/ID/PA fans should be in stopped condition
3 All APH flue gas outlet damper should be closed