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 and mill capacity constraints 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 (pulverizers, coal pipes,
PA/ID fans, air-pre heater), retrofitting of certain items [low NOx firing system and low pressure
economizer (LPE)] and related boiler works (thermal performance test & modelling, flow correction,
leakage reduction etc.).
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 etc.
Air- pre heater (APH) performance improvement shall be achieved by replacing baskets with high
performance element profiles, sealing system modification, regulation of rotational speed to optimum,
refurbishment/replacement of housing/ internals 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 pulverizer enhancement is envisaged through proven methods of ball-race modification, retrofit
of dynamic classifier and replacement/modification of internals, mill motor replacement while retaining
the existing foundation. Higher coal and air requirement calls for replacement of PC pipes as well.
Capacity enhancement of PA & ID fans is envisaged through changes/replacement to fan rotary
parts/housing, speed etc. while retaining the existing foundation. Motor replacement is also to be
carried out.
Further, in line with NTPC’s commitment to environment, the specified NOx values are much lower
than standards. Accordingly, the scope includes replacement of existing coal burners with low NOx
burners. OFAs (over fire air) to be installed if deemed necessary.
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 steam generator insulation replacement, introduction of
3
rd
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 (reheater/superheater) in included based on
assessment.
The above works will require performance diagnostics for which certain design and performance data
for existing equipment is 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) and mill wear parts life. Accordingly, these parameters
are also required to 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.
