Case Study of Reconditioning of Air Preheater Gear Box

8/12/2019 Case Study of Reconditioning of Air Preheater Gear Box

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CASE STUDY OF RECONDITIONING OF AIRPREHEATER GEAR BOX

AtDr SHYAMA PRASAD MUKHARJEE THERMAL

POWER STATIONSubmitted by

NARENDRA PATELEASE KORBA


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DR SHYAMA PRASAD MUKHARJEE THERMALPOWER STATION AT A GLANCE

Dr Shyama Prasad Mukharjee thermal power station is operated by Chhattisgarh

state power Generation Company limited.

Dr Shyama Prasad Mukharjee thermal power station, Korba is situated in the heart

of the city. It is built in the place where the first power plant of Korba was built in 1958.

It has a installed capacity of 5oo megawatts consisting of two coal fired Bhel boilers of 250

megawatts each. The first unit was commissioned on 30thMarch 2007 and the second unit

was commissioned on December 11 of the same year.

Dr Shyama Prasad Mukharjee thermal power station has always welcomed new

ideas and concepts for improvising its efficiency. Reformation of process is a regular feature

at KTPS. The plants officials are always ready to adopt newer technologies and believe in

continual improvement and setting newer bench marks. EWAC Association goes hand in

hand from last 3 decades. EWAC services are regarded very high at Dr Shyama Prasad

Mukharjee thermal power station. Various technologies have been offered to the plant

which has been very well accepted by the plant


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ABOUT THE JOB

The gear box is situated in the primary air fan area to reduce the rpm of electrical

motor to that required for fan. During the changing of bearing the bearing sitting area of

the gear box cracked due to miss handling.

(crack of air preheater gear box)


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Application detailsNature of problem- crack developed due to improper handling

Base metal- cast iron

Recommended electrode-

Eutectrode 27 and Xuper 2240

Reason for recommending these electrodes

The gear box contains oil inside for lubrication of gears. Since the base metal is cast iron, it

soaks oil so a buffering layer of eutectrode 27 is required because it can seal the impurities

and the bonding between the base metal and required joining electrode should be perfect.

Xuper 2240 has a nodular cast iron deposit which provides improved crack resistivity.

It is highly machinable.

It provides a tensile strength of 57000 Psi which ensures a high safety of margin.

The weldability of the electrode is excellent.


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STEP BY STEP WELDING PROCEDURE1st step

The cracked metal part is removed by grinding. The grinding is done till the complete

crack is removed.

2nd stepDye penetration test is done to check that the crack is removed completely.

3rdstepThe preheating is done with oxy- acetylene flame to 200 degree Celsius and welding

is started.


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A single layer of eutectrode 27 is deposited to seal the contaminants inside. Due to

use of eutectrode 27 the next phase of welding become easier because it sealed all the oil and

impurities.

4thstepWelding current is set to as low as possible to burn the electrode to preserve the

quality of weld deposit and to prevent over heating of electrode.

Short stringer beads of Xuper 2240 are welded and after welding the bead peening is

done with a ballpin hammer to remove the internal stress and flux is removed with the help

of a chipping hammer and with the help of stainless steel wire brush. This process is done

till a complete layer is overlaid and then the weld overlay is slightly grinded to remove anyflux residues. Then temp of job is checked and preheating is done once again to bring the job

temp to again 200 degree Celsius. The process is continued till the total area is completly

buildup to required thickness.


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Final view of job after welding


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For Further Information Please Contact

NARENDRA PATEL

EASE KORBA

Ph-07509572413

Mail- [email protected]

The only way to do great work is to love what you do

Case Study of Reconditioning of Air Preheater Gear Box

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