ID, FD,PA FANS,AIR HEATER , MILLS LUBE OIL BOILER COMMNG PART IX -ABC OF THERMAL POWER

I am going to describe the commissioning procedures of ID<FD and PA fans for a boiler.

As  the procedure of commissioning is more or less same therefore commissioning

procedure will be common.

While writing  it was felt that before start commissioning procedures of fans ,the

commissioning procedures of lubrication units to be discussed . As these lubrication units

are more or less same for all the fans therefore any one can be discussed out of all

lubrication units. These units are also same for AH (air heater) and Mills. So if we discuss

one lubrication unit then other units are automatically covers.

Number of lubrication units used in Boiler

-  One Number /Fan /unit – Total requirement is six numbers ( ID-2 ,FD-2 and PA-2)

-  One Number / Mill /unit- Total number 9 or 10 as per number of Mills.

-  Two Number /Air Heater/Unit ( Support & Guide bearing) – Total 8 numbers ( SAPH and

PAPH).

Rotary equipment in Boiler like Fans ( except scanner and seal air) ,Air heaters and Mills

are provided with external lube oil system for supplying lubrication to the bearings. This

lubrication units also serves as coolant for equipment bearings.

The external lubrication system consists of Oil Tank , Pumps (02 nos) , suction

strainers ,duplex filters , oil coolers , connecting pipelines valves (isolating and relief),

instrumentation for local measurement and remote logic and measurement etc. Logic of

auto changeover and emergency change over by hand are also been provided.

Generally all  the lubrication unit comes as a skid (i.e totally fabricated with input / output

connection at the end.

Our main objectives will be clean the lube oil unit pipeline and associated equipment free

from dust and foreign materials so that lube oil going to bearing  is very clean.

All the equipment and pipelines to be erected as per drawing . Drain oil pipes ( from Bearing

to tank should have minimum slope towards  the tank).

Site erected pipelines are dismantled from flange joints ,end connection etc to make it

smaller pieces. Then these pipelines are manually cleaned and air blown. Then wooden

plugs placed in one end tightly and flushed with DM water number of times to check that      

there is no leakage from wooden plugs.

 All the coolers to be hydro tested 1.5 times  of the design pressure.

 Following chemicals are required for acid cleaning of pipeline ( soaking method)

 a. HCL 30% b. Rhodine 213 SPL  c. Sodium Nitrite d. Liquor ammonia 25%

 e. Lime Power.

 

5% hydrochloric acid with 0.2% inhibitor ( Rodine 213 SPL) is filled in the pipes.

The solution is allowed to soak in the pipes for four hours and then drain to pit and with

plenty of service water and lime to neutralized.

The pipes are flushed with DM water for 5 to 10 minutes .

Pipes are again filled with DM water containing 2.0% sodium nitrite and 5% liquor

ammonia . The solution is allowed to soak for 30 minutes and then drained to pit.

The pipe is rinsed with DM water till PH of discharged water is between 6.5 and 7.5.

 The internal surface is dried with compressed air.

 The line filled with lube oil and then drain . This will fill the pipeline with a uniform fill of oil.

 ( Any cutting ,welding after acid cleaning of the pipe is strictly prohibited. )

 Oil Flushing is carried out in two stages

 Stage-I - without bearing in circuit

 stage –II – Bearings included in the flushing circuit.

 The Oil Tank is filled with recommended oil

 Direction of motor is checked by dismantling the pump and again assembled.

 Centrifuge also placed in position and connected with temporary lines.

 Start the pumps with recirculation valves wide open.

 Pressure to lube oil lines is brought to 1.0 to 1.5 kg/cm2 by throttling recirculation valve.

 The system is checked for leakage. Flushing should continue with one pump in service .

Both the pumps should be tried alternatively. Centrifuge should be on service to clean the

oil.

Time to time DP filter is checked and if required cleaned/replaced.  DP across filter should

be less than 0.2 Kg/cm2

Mechanical impurities should be less than 100 ppm in flushing oil for three consecutive

reading taken at interval of four hours.

Before taken Bearing into circuit clean the oil tank again so that all sludge accumulated

during stage –I flushing gets cleaned.

All the measurements during commissioning to be recorded and protocoled.

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