failure of rotary flow divider

8/10/2019 Failure of Rotary Flow Divider

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Project : CPCL Frame V GT, units 1 & 2

Problem: Failure of rotary flow dividers of fuel supply line toGT Combustion chamber

The flow dividers of M/s Ropar make supplied to Gas Turbines atCPCL site were not performing well during commissioning phase of theGas Turbines, due to various reasons. All the four flow dividers

supplied in both On base and Off base skids have failed. The

condition of the flow dividers were such that one or two could not beeven rotated slightly. There were no flow dividers available with

manufacturing units or with any authorized service agency.

Complete commissioning was held up leading to non-completion ofcontractual obligations. Replacement against insurance will be a long-

drawn affair, which will not meet neither BHEL nor CPCLs

requirements. Hence the flow dividers were serviced at site.

All the flow dividers have been working satisfactorily since servicing,

for around 10000 hours and hence it was strongly felt that servicing

would restore the healthiness.

Engineers from hyderabad have also felt that servicing had

extended the life of flow dividers beyond the normal 8000 working

hours. The entire works were carried out in a controlled, closed andclean environment. Sufficient care was taken to ensure availability of

proper tools, required lifting arrangements, etc. Before disassembly,

all the components were match marked. The self-locking bolts werereplaced in the probe gear wheel.

During assembly at every stage of plates assembly, care was taken to

check the freeness for rotation, condition of O rings, etc. The gears


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in the gear pumps were very high degree of finish and the clearances

were very close, at the order of less than 0.l mm. Even a minorscratch affects the freeness of rotation. The sun gear locks all the

planetary gears and does not allow differential flow. All the ring

plates are isolated with O rings.

Collection of paste like ferrous matter on the needle bearing holding

areas was observed. The bearings were soaked in naphtha and the

paste like ferrous matter was cleared. The bearings are to beabsolutely clean and in good condition, after cleaning. Initially it took

3-4 days to service one flow divider. But later on one flow divider

could be easily serviced in a day. By now, the customer & HyderabadEngineers have been acquainted with the art of servicing after

witnessing the servicing of flow dividers carried out by our Engineers.Thus, we could save the total cost of replacements, cost of contract

extensions and insurance, etc.

The figures in the next few pages explain the various steps in assembly

and the construction features


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10 NO. OUTLET

TO COMB.

CHAMBER1 NO.

FUEL OILINLET

RING TYPE

SOLID PLATES

W IT H L IF T ING

LUGS, 'O' RINFOR

ISOLATION

I

I I

I I I

IV

V

A

BBUSH IN ALLHOLES SHALL BE FREE


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I TOP PLATE WITH SPEED PICK

UP WHEEL

II PLATE WITH GEAR PUMP

SPINDLE, BUSH AND LOCKING

ARRANGEMENT

III PLATE HOUSING 10 NO. GEAR

PUMPS

IV PLATE HOUSING 20 NO.

NEEDLE BEARINGS FOR PUMPS

V BOTTOM END PLATE WITH OIL INLET AND OUTLET

CONNECTIONS

LIFTING LU

TOP PLATE

I

I I

I I I

I V

V


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RING PLATE WHERE

NEEDLE BEARINGS LOCATED

'O' RING

GEAR OF

ONE PUMP

NEEDLE BEARINGS

PLATE HOUSING GEAR PUMPS

MESHED WITH PANETARY GEAR

10 NO. GEAR PUMPS

PLANETARY GE


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The following important precautions to be taken to ensure good servicing

of the flow divider.

01. During assembly the bush inserted in all the holes shall go free.

02. All the bolts shall be tightened uniformly.03. All O rings of required dimensions, new and required quality shall

be used.

04. Gear pumps and gear shall be checked for scratches, clearancesare in the order of 0.015 mm.

05. During assembly at every stage check for free rotation of gears.

For this, just if the probe stem is rotated with thumb and finger

it shall rotate the gears.06. In a good serviced divider with the index finger and middle finger

in the probe gears, it shall be possible to rotate freely.07. Ensure the divider is not dummied/blocked in suction and dischargesides.

08. Servicing shall be carried out in a clean and closed environment.

09. Pure naphtha was filled in vessels and bearings were soaked for 24hours.

10. Plastic toothbrushes were used for removing contaminants.

11. Uniformly free rotation is important than free rotation itself.


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failure of rotary flow divider

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