OIL FLUSHING ,STEAM BLOWING ,COMMISSIONING OF LDO,HFO SYSTEM OF BOILER PART III-ABC OF THERMAL POWER STATION.

In continuation of Part -I and II of FO,LDO system description and commissioning this article

will cover the oil flushing and Steam Blowing of the system.

To remove debris and clean the internal surface of oil lines in the LFO/HFO system,

including atomising steam lines and steam tracing lines oil flushing and steam blowing

are being carried out in systematic manner . This will prevent particle to be passed into

screw pumps and burner nozzle.

  

Auxiliary Boiler or Low temperature APRDS will be used for steam blowing the Fuel Oil

lines. Now -a days auxiliary boiler with requisite parameter is available on rent .They will

bring their boiler and cater all the pre-requisite steam for the system. APRDS can only be

used if there is an existing running boiler.

 

Steam blowing the Fuel Oil line by continuous blowing method for the duration of 20-30

minutes at a pressure of 10-12 Kg/cm² and a super heat of at least 50⁰C at source.

Depending upon the site conditions, the different sections / circuits for steam blowing may

be decided by consulting PIDs of the system ,equipment manufacturer's recommendation.

Following are pre-requisite for steam blowing

Hydraulic test ,support work and insulation completed on all the lines where steam blowing

is to conducted.

All safety precautions and emergency safety precaution are in place .

 

Auxiliary boiler is fully ready for supplying steam for steam blowing F.O. lines.

 

Steam drawn either directly from Aux. Boiler outlet through a temporary lines connected to

F.O lines or from APRDS. This is to be decided at site as per the erection readiness of

these system.

 

Trip valves, control valves, flow elements are not erected and suitable spool pieces are

erected at these places. A check list will be prepared for activities of their type which will be

used during restoration.

 

Filter elements and NRV internals are removed.

Temporary exhaust pipes lines are erected avoiding equipment and buildings.

 

All vents and drains are properly routed and supported.

Day Tanks and storage tanks for LFO and HFO are ready for operation.

All steam lines as well as oil lines are insulated.

No permanent instruments has been installed in the lines being steam blown/oil flushed.

They are totally isolated from steam blowing / oil flushing, in case erected.

SL.             PIPELINES                                         PR       DURATION    NO.OF BLOWS(min)

1.   Steam lines from Aux .Boiler/APRDS             10.0          20-30 min             3

2.  FO lines from Pump House to Boiler               10.0          20-30 min             3

3.  LFO lines from Pump House to Boiler             10.0          20-30 min             3

4.  Steam lines from Boiler to Pump House          10.0          20-30 min             3

5. Steam tracing & Condensate lines                     6.0           20-30 min             3

6. All the other FO /LDO Lines                              10.0          20-30 min             3

7. FO unloading Header                                         2.0           10  min                 3.  

Brief method of Steam Blowing

Auxiliary Boiler is lighted up as per O & M manual start up procedure after attaining steam

pressure about 10-12 kg/cm²  carry out the warnming of the line to be steam blown at a

lower pressure. Raise the steam pressure at the drum to 10-12 kg/cm²  and give the blow

for a duration of 20-30 minutes. Maintain the pressure during the blowing period.

 

Allowing it to cool down for 2 hours, above process is repeated for another one or two times

till it meets the completion criteria. Between every blows, 2 hours cooling time will be given.

Keeping the line pressure 5 kg/cm²  carry out the purging of drains/vents & instrument

taping points for 10 minutes each.

 

Similarly, repeat other loops/sections/sub-sections are steam blown.

 

Drains/vents of F.O lines are kept open as required during steam blowing and after, for

draining condensate. Allow to cool down the piping. Dry them with compressed air.

NOTE: During the cooling period of one section, other section as per convenience, will be steam blown.

After completion of steam blowing, all spool pieces are removed and Trip valves, control

valves and flow elements, filler elements and NRV internals are restored / normalized. Pipe

connections to LFO/HFO pumps are normalized and pumps are commissioned.

continued to Part -iv oil flushing and final commissioning

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