R&M AND UPRATING OF AUXILIARIES AND RELATED BOILER WORKS STAGE-1 (3X200 MW)

UNITS OF RAMAGUNDAM STPS

SALIENT TECHNICAL FEATURES

Ramagundam stage-1 steam generators are natural circulation, dry bottom, front wall fired, balanced

draft & convective reheat type with direct fired pulverized coal and baffle bypass damper in convection

path as primary mode of reheater (RH) temperature control.

The steam generators were designed for Indian coals with heating value of 4300 kcal/kg which over the

time has deteriorated and now hovers around 3500 kcal/kg. The boiler now operates with high exit

temperature along with saturation of margin on ID fans.

NTPC intends to undertake necessary works on the stage- I steam generators & auxiliaries to correct

and improve their performance essentially by uprating/upgrading of auxiliaries (like ID fans),

replacement of complete air-pre heater, retrofitting of certain items [coal burners and low pressure

economizer (LPE)], performance improvement related boiler works along with certain replacements viz.

safety valves, spray station valves, spray header & all manhole doors of pass-II etc. and including

supply of spares.

It is also intended under the package scope that the boiler cater to steam parameter requirements of

uprated turbine (210 MW) which is being undertaken as a separate package.

The scope of the package has been developed to cater to these above requirements.

Thermal performance test (TPT) on all the three units is envisaged to map the boiler performance

while thermal modelling is to be used for boiler performance prediction.

Related boiler works to improve and sustain the performance improvement include air & gas tightness

test, cold air velocity test (CAVT), boiler roof and economizer hopper refractory replacement, duct

refurbishment, insulation replacement and replacement of boiler 2

pass skin casing etc.

Air- pre heater (APH) performance improvement shall be achieved by proven methodology, inter alia,

towards the objective of achieving the specified minimum total flue gas temperature reduction at the

exit of the steam generator by way of replacement of air-preheaters and regulation of rotational speed

to optimum etc. Performance correction through improvement in air flow is expected. Accordingly,

minimization of boiler leakages is one key focus. Further, to augment heat pickup in the APH,

installation of Low pressure economizer (LPE) in the flue gas duct after APH is included.

Coal burners’ replacement is included for the specified requirement of coal and NOx values.

Capacity enhancement of ID fans is envisaged through either modification or replacement of the

existing ID fans while retaining the existing foundation. Motor replacement is also to be carried out.

The bidder can also make alternative offers (with proper supporting data) which in their judgment are

superior to existing requirements along with its implications on performance parameters. Some of the

alternatives included in the specifications are introduction of 3

ID fan, addition of high temperature

economizer and burner rig test.

Bidder is required to carry out feasibility check for adding surface to economizer (high pressure) within

the steam generator before the APH. Further, spray levels and metal temperatures are to be checked

and necessary alteration/addition in heat transfer surfaces (re-heater/super-heater), as certain

specified quantum, is also included which shall be refined based on assessments.

The above works will require performance diagnostics for which certain design and performance data

for existing equipment is already provided. However, the bidders are also required to visit

Ramagundam site, interact with personnel, collect data etc. and carry out their own review & analysis

to accurately directionalize their interventions for achieving the boiler performance objectives.

The package performance is envisaged to be evaluated based on reduction in boiler exit temperature

(both by APH & LPE) achieved by the bidders for which a range is specified. Evaluation parameters

also include auxiliary power consumption (APC) which shall be guaranteed by the bidder.

Other than above guarantees, certain mandatory and demonstration guarantees are also included

while BMCR capacity demonstration is included as part of trial operation.

Necessary & related works & supplies, as specified in technical specifications, for civil, control &

instrumentation, electrical and quality control etc. are also included in the package scope.