SEAL AIR FAN COMMISSIONING - BOILER COMMNG PART-VIII -ABC OF THERMAL POWER STATION.

Seal air fans are located  at zero metre level between first pass and second pass. These are high

speed fans and prone to high vibration and risk. Therefore it needs special care to commission

these fans. All individual items to be checked during assembly and protocoled that includes brg

lubrication for DE ,NDE of motor and fans and other c&i items.

The Seal air fan system consists of the following items.

Cold Primary air Suction duct.

2 Nos of  filter & its associated dampers & bleed air lines.

2 Nos. fan with motor.

Suction Dampers of Seal Air Fan

Discharge Dampers of Seal Air Fan

Discharge Ducts up to Mill Seal air points

Seal Air Fan basically functions as booster fan taking suction from primary air fan discharge (cold

primary air before AH-A&B) boosting up the air pressure and supplying seal air to various  sealing

points of Bowl Mills.

Seal Air Fan Suction Pressure       : 580 mmwc  ( for 500 MW units only)

Seal Air Fan Discharge Pressure  :  1088 mmwc ( ----do)

Filters are provided in the Suction line of the Seal air fan with a provision to continuously bleed any

dusty air in to furnace through Secondary air duct-wind box.(WB)

Objective  to Commission Seal Air Fan and make it available for Bowl Mill Commissioning.

The Commissioning of Seal Air Fans and its system is carried out as follows:

a.            Cleaning of Suction Duct through  filter up to fan suction point.

b.            Trial run of fans & cleaning of discharge ducts up to Mill Seal Air input points.

SAFETY PRECAUTIONS:

Debris in and around Fan and Duct area to be removed.

Approach / Stair Case / Platform where ever required are made available.

The Test team should know well about the procedure to be adopted in case of damage to machinery

or injury to personnel connected to the activity.

The Commissioining team should be well aware of procedures to be adopted in case of any

abnormality.

STATE OF THE PLANT:

The Seal Air Fan and its associated duct system are erected as per recommended drawing.

Filter erected with its bleed line to WB.

Power Supply system for the fans are commissioned and available for operation.

Required Local / Remote I & C Inputs are made available .

Inlet and outlet dampers of fan and  damper erected and are freely operating.

Small duct piece at Suction of the Seal Air Fan removed for cleaning the Suction duct or Suitable

opening to be made at suction header of the fan for cleaning the fan suction duct.

All the hoses connected the Mill Sealing locations are kept removed for discharge duct cleaning / Fan

trial run.

Suction / Discharge ducts support completed as per drawing.

PA Fans and primary System available for operation from control Room.

Required local / Remote C & I inputs are available (list to be prepared at site)

Primary air inlet / outlet dampers of Primary APH are kept at suitably modulated position for this

cleaning activity.

System made ready  : PA Fan (A/B) cold Primary air before APH –  filter ( A/B) – Seal Air Fan

suction Duct.

Start any one of the PA fan and gradually load the fan to reach discharge pressure of about 500

mmwc.

Sufficiently blow the duct from cold primary Air before APH take-off point to Seal Air Fan suction.

Air blowing to be continued till clean air observed at Seal Air fan suction point.

(Duration : About  15 mts)

Parallel, open the valve in the bleed line of Filters one by one and blow the bleed line into WB.

(Duration : about 10 mts)

Release the system for Seal Air Fan Trial run / cleaning of Seal Air Fan discharge System.

System made ready: PA Fan (A/B) discharge duct with one man hole door opened – Filters – Seal Air

Fan suction duct – Seal Air Fan – Discharge duct up to mill Sealing location. (PA Fans in switched

off condition).

Keeping the suction damper in open and discharge damper in close condition, start one Seal Air Fan,

Keeping the other fan in isolated condition.

Open the discharge damper slowly and ensure that the Seal lines to the Mills are blown.

Put the Seal air Fan under 8 Hrs trial run and during this period, measure Fan load current and

vibrations and other parameters for records.

Cleaning of all Seal lines to mills are done one by one or by pair and for this, the main inlet damper

to individual mills are opened keeping the dampers of other mills in closed condition.

Once or twice, the Seal air lines to Mills are gently tapped to dislodge all the loose particles from the

piping.

Stand by Seal air fan also put on 8 Hrs trial run as explained above.

At the end of 8 Hrs trial run, the Seal air lines to Mills are normalised

The drawing shows the location of seal air fan at Boiler and its ducting and piping.
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COMMISSIONING OF SCANNER FAN -BOILER -ABC OF THERMAL POWER STATION

The scanner fan consists of following equipment and system

Suction Filters

2 Nos. fans with motor. (AC and DC Scanner fans)

Suction Dampers

Discharge Dampers

Auto Dampers (Emergency damper) and individual scanner air line.

Discharge Ducts

Local Instruments

The Commissioning of Scanner Air Fans and its system is carried out as follows:

a.   Flushing of Suction Duct and Discharge Duct

b.   Trial run of fans. Following common service to be arranged before commissioning. - Adequate manpower for commissioning ( generally arranged by erection vendor) - Readiness of LTMCC for scanner fan motor. - Availability of safe platform with adequate illumination. -Clean surroundings i.e without any debris nearby or loose material.                                                     -Mechanical cleaning /manual cleaning of circular duct completed. - Ensure duct system and other equipment are erected as per drawing. -Filter element are removed ,cleaned and kept outside. - Inlet /outlet dampers erected and fully operational from local/ remote. - Emergency damper erected and operation. - Logics of fan start stop checked . - End piece of scanner suction duct has been removed. - All final connection like hoses etc are removed and kept open. Suction and Discharge Duct Air flushing -After removing the suction filter element and suction duct piece, start any one of the FD Fan and load the fan to maintain 300 Discharge Pressure. Open the suction damper of scanner fan and flush the duct up to fan suction for 10 minutes. Close the suction damper and again open and flush for 10 minutes. This is repeated till the duct is clean as seen from blown out air. -Restore the suction duct with fan. Start and complete the trial run of fan & motor for 4 hours. For this trial run, FD Fan need not be in service. For the first 2 hours, the fan trial run carried out with FD discharge as suction to the fan and next 2 hours, the emergency damper in fan suction kept opened. During this trial run, load current of the fan noted down once. -Normalise the filter and scanner hoses.  Start the scanner Air fan and complete the trial run for 4 hours. (Suction from FD discharge for 2 hours and Emergency damper in open condition for 2 hours). Load current of the fan again noted down once. - Arrange calibrated vibration reading meter to measure vibration of Fans   and motors ( DE and NDE) - Calibrated tongue tester to measure no load and other load current. - If all the instruments are in place then measure the suction pressure   when FD fan is running and also corresponding discharge Pressure. - Record ,protocol all the reading and status for further use. - Before start check the lubrication status of all bearings and freeness   motor and fan separately.  ( value given based on 500MW set.) P.S If  you are looking to earn few legitimate extra money from the comfort of your home then please click on the link given below LINK 1 - PLEASE CLICK HERE  LINK 2 - PLEASE CLICK HERE ( value given based on 500MW set.)

SOIL INVESTIGATION REPORT REQUIREMENT FOR DESIGNING.

Up to last blog about soil   investigation  we have seen the places in the thermal station needs soil  investigation and also type of field in-situ testing is to be done. Also we have seen the type of laboratory test to be carried out. Now we will see what are the essential part to be included in the report so that it becomes a comprehensive report at the end.

REPORT

At first draft report will be submitted  to the authority and after discussion Final reports are submitted..

The report should contain following items.

a. All the location wherever  field test were conducted should be plotted on GLP.

b General Geological information of site ( Topographical survey).

c.Character and Genesis of Soil.

d. Procedure of investigation and method followed for conducting the test.

e. Details of bore logs ( coordinate), RL ( reduced level) , water table, SPT ( in situ) , laboratory test etc.

f. Generalised soil profile of the strata below.

g. All the field and lab data placed in depth wise.

h.Summary of results obtained from various tests and other interpretation to evaluate various soil parameters.

i. Recommendation of foundation of different tanks.

j.Recommendation of depthe foundations for for misc. building , roads , railway sidings etc.

k.Recommendation of suitable foundation system with bearing capacity of soil.

l.Recommendation of filling materials after excavation.

m. Ultimate safe bearing capacity considering shear and settlement.

n. Recommendation of pile foundation (if necessary) including type, size and depth of pile and also

    indicate safe load in vertical ,lateral and pullout.

o. Chemical composition  of water an its effect on concrete , steel etc of the plant . Remedial measure.

p. Recommendation of CBR value for design of road, pavement etc.

q. Recommendation of soil resistivity to be considered for design purpose.

r. Recommendation of foundations after considering Pressure meter test.

s. Recommendation of ground water fluctuation . Horizontal ,vertical permeability of the land.

The above information and after discussion will contain all the logs , test sheet , calculation sheet , graph plotting etc will form a report based on which designer will design the project.

We conclude the soil investigation report and we will continue with civil basics and problem faced during construction. We are enclosing some photographs below for information only.

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BOILER COMMISSIONING - MISC TANKS SMALL ,LARGE OF THERMAL POWER PLANT

There are different sizes of tanks are available in boiler ( Fuel oil storage tank , LDO tank , day tank

CBD tank , IBD tank , CC pump emergency tank , Drain oil tank , FST (feed storage tank & Deaerator) 

etc.  These tank can be divided according to their size and there process requirement . However Feed 

Storage tank comes under pre-boiler system and need separate chapter for its erection and 

commissioning . This I will discuss when I will be discussing turbine erection and commissioning.

STORAGE TANK ( SMALL AND MEDIUM) –GENERAL CHECK LIST

Access to the plant item is adequate

Illumination in the plant area is adequate.

Any other requisite safety provision is adequate for the immediate commissioning activity.

Plant item is in a clean condition.

All necessary locks and keys for padlocks interlocks etc. are available.

Hot surfaces lagged for screened sufficiently to provide protection for personnel.

Check the installation as per drawing specially orientation of nozzles.

Check that all internal items, grills, trays filter elements etc. are installed.

Check that float valves if fitted are correctly installed and operating freely.

Check that tank is internally clean, free from debris, and that the internal and external protective coating.

Check that all external fittings, gauges and indicators are as per drawing and securely fitted and supported. Unused bosses to be plugged or blanked off.

Check that all pipe work systems connected to the tank are complete at least to isolating valves.

Check that filling, overflow, vent and drains are complete, at least to isolating valve.

Hydraulically test tank as appropriate and check for leaks. Record if tank settlements are made.

Check that heating arrangements (steam heating or electrical heating) is fitted, is to specification and complete.

Check that lagging and cladding (if required) is complete to specification.

Check that support structure, ladders and handrails are satisfactory.

Check access doors (if fitted). Sealing arrangement of access door to be checked.

All the checks to be made and protocol for future use.

STORAGE TANKS LARGE –GENERAL CHECK LIST – A FEW MORE ADDITION TO ABOVE

Check all valves, switches, pressure switch etc. as per drawing and check list.

Check  tank is internally clean and finished as per drawing.

Check the  fire protection arrangements available or not available.

Check all the access manhole covers fitted . Specially check roof manhole cover and locking arrangements.

Confirm that the vent area is at least 1.5 times the filling pipe or suction pipe area (whichever is the greater) and fitted with a 4 mm mesh non ferrous wire cage.

Oil tanks, check the  combined water draw off and clean-out sump drainage arrangement

Check  the tank drain valves locking arrangements.

Check all the lines (overflow ,drain etc) connected to designated sump .

Check the gradient also for these lines.

Check  the local and remote, high and low level alarms together with the testing facility

For oil tanks, Check the heater trip and other protection logic as per approved scheme.

Check the operation of pneumatic valve as per check list given in earlier dispatch.

Check the tank earthling arrangements comply with the requirements specified for the particularly size of the tank. (Tanks up to 30m dia, 2 opposite spared earth strips; tanks over 30m dia, 3 equally spaced earthling strips).

Check the tank calibration certificate ( if available)

Check the level gauge and the level on tank body on big letters so that same can be seen from distance.

Check the bund arrangement of the tank . It should have been completed and free from debris.

Fill tank, proving manual and automatic system of control (if applicable)

1.            Record rate of filling; Height/minute

2.            Record rate of filling: Quantity/minute

3.            Record operation level of low level alarms.

4.            Record cut in level of auto filling

5.            Record cut out level of auto filling

6.            Record operation level of high level alarms.

With all points of consumption at maximum flow and inlet valve shut, measure:

1.   Rate of emptying: Height/minute

2.   Rate of emptying: Quantity/minute

Protocol all the reading for future use. During commissioning all big tanks reading to be taken as such tank does not get empty very often. If you miss to note them you may not get chance to do that in near future. Therefore all the activities to be completed once for all.

continued to part-vi

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