Salient Technical Features

Unchahar Stage-I boiler is provided with single bank of Economizer Coils. At present, flue gas temp at economizer outlet is high. Considering high flue gas temperature at economizer outlet, there is a scope of additional flue gas heat recovery by increasing heat recovery surface area in economiser. The intent of this specification is to replace the existing Economizer coils with increased heat transfer area to increase feedwater temperature at economiser outlet, reduce the economizer outlet flue gas temperature and to improve the performance of the boiler.

The scope of supply and erection work for the package includes the following:

a.Complete replacement of existing economiser coils with new economiser coils

with increased area having inline, bare tube economiser, thereby increasing the existing surface area of 3760 m2 by 20% to make a total area of 4512 m2.

b.Checking of load bearing capacity of existing foundation & support structure for the increased load due to increase in economiser surface area and replacement of existing hanger tubes.

c.Strengthening of existing structure and providing new hanger tubes (as required) for additional economizer load.

d.Bidder to check that there shall be no steaming with increase in economiser surface area. Bidder shall bring out any limitation in increasing the area (if any) in his offer.

e.Header rearrangement (if required) including connection to feed water piping shall be in bidder’s scope along with all insulation (if required).

f.Any cutting and restoration of the boiler wall shall also be in the bidder’s scope.

g.Supply of Mandatory spares as detailed in technical specification.