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ABOUT THE CUSTOMER:

BALCO Captive Power Plant II is unit of BALCO & Vedanata Resources Pvt Ltd.,

located in Korba, Chattisgargh. BALCO was incorporate in the year 1965 as aPublic Sector Unit of Government of India.

In 2001 government of India divested 51% of its stake to Vedanta Resources. The

captive power plant II has a installed capacity of 540 MW consisting of 04 units of

135 MW each. It is a coal based power generation unit having coal supply from

SECL Kusmunda circuit. The plant has been conceptualised for BALCOs internal

power requirement for Aluminium production. Out 540 MW only a small pie of

power is being contributed to the state power grid for distribution.

SEPCO (Shanghai Engineering & Power Company Ltd) has designed the power

plant.

ABOUT THE COMPONENT:

Induced Draft fan is a component of air circuit in Power Plant whose prime

function is to suck out the flue gases from the furnace and release them into

atmosphere. It is a dynamic component which finds it place before the chimney and

after ESP (Electro Static Precipitator). This particular ID fan is of backward curved

centrifugal design and has a aerofoil design. As the picture indicates air is being

sucked from the centre and is delivered radially out. The fan is composed chiefly ofthe casing, air suction box, air inlet, driver, and

impeller, bearing box, damper and the electric

driven part. And it is directly driven by the

electric motor through a foil coupling. The type of

the motor is YKS560-6.

Specifications of the ID fan:

Make : Shanghai BlowersPvt ltd.

Volume of Air

Handled:

512820 m3/hr

Pressure rating: 5357 Pa

Prime Mover : 1120 KW

Size: 1768 mm(Diameter)

Base Metal: Alloy Steel( SAE 8640)

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ABOUT ITS FUNCTION:

IDs fan main function is to create a draft such that the flue gases after passing

through the ESP can be easily released into the atmosphere. In order to achieve

this, fan rotates at high speed (1080 rpm) thus the high velocity of air and pressurecreates a negative pressure of -1700 mm of Hg inside the boiler. This not only

prevents from backfiring but also creates a draft that is capable of sucking out the

flue gases from the boiler. The fan is subjected to maximum temperature of 200C.

AREA OF CONCERN:

Since fan is rotating equipment it comes into the range of dynamic auxiliaries. The

balancing plays a vital role in the performance of the equipment which in turn

reflects in the overall performance of the plant. Here in this case fan has a

backward curved aerofoil design hence the blades have a hollow section in between.

As it handles fly ash borne high pressure air, fly ash particles being highly abrasive

in nature erodes the blades surfaces and also it makes fine holes, through it

particles enters into the hollow section and it results into unbalancing of the fan.

The air flows at very high pressure and the ash particles erode the blades surface of

the fan severely. In this case particularly the sides of the fan body which is in

contact with the edges of the blades faces severe brunt of erosion.

The customer faces main problem of repeated balancing of the fan after only a

period of 30-35 days.

It is the main area of concern where due to

puncturing, ash was being accumulated inside the

blades.

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Our Solution:

After studying wear out pattern we have suggested combination of Chrome Carb

6006 and Endotec DO 390N. The following reason justifies our recommendations.

It faces severe erosion due to fly ash particles.

Unable to create necessary draft as it was bound to be rotated at below ratedrpm.

It has service temperature of 150C - 200C Changing of the keeper plates at inner radius area with the new MS plates. Chrome Carb 6006 and DO 390 N can easily take care of the service

temperature.

Chrome Carb 6006 has very minimal stress relieving cracks which preventsthe fly ash particles to enter into the hardfacing layer and help in protecting

the erosion.

The dense microstructure of DO 390 N at the inner edges of the blades willprevent the severe erosion and puncturing of the blades

Protection of the fan blades from puncturing saves the time of repeatedbalancing and the downtime cost.

ID Fan After Reclamation

Area of Chrome Carb N*6006 Area of Endotec DO 390 N

After reclamation with Chrome Carb 6006 & DO 390N the fan is running

successfully at rated speed of 1080 rpm without puncturing and balancing for 60

days and still onSavings For The Customer:

Downtime Cost(+) Rs 30000000

Cost of New Part(+) Rs 1500000

Cost of Reclamation(-) Rs 550000

Hence Total savings(+) Rs 30950000

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SERVICE REPORT