Preparation of Commissioning,Trail run of various equipments,Air & Gas Tightness test of Boiler

A.R.SAOJI, arsaoji@gmail.com

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COMMISSIONING

Commissioning is the term to describe activities involved during later stage of erection up to the completion of 72 hours trial run on full load leading to commercial operation of plant.

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COMMISSIONING ACTIVITIES

Before declaration of commercial operation of unit, it is essential to ensure that the plant has been thoroughly tested prior to normal operation so that initial performance can be guaranteed and all the remaining defects and omissions are identified.Separate team that one handling the project activities is necessary to monitor commissioning activities and to set up organization/ systems for subsequent regular O&M of the plant.

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PURPOSE OF COMMISSIONING

Target dates should be achievedTo ensure that plant is supplied and

erected as per design.Quality of erection and

commissioning should be maintained.To check that plant operates reliably,

safely and meets the design performance.

To establish reasons for any failure to achieve design performance or any other limitations.

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ORGANIZATION/ SYSTEMS

Commissioning Group is formed 18 months prior to scheduled commissioning of the unit.

To identify O&M staffs. To set up O&M organization. To collect Operating instructions, Manuals,

schematics and drawings etc. To prepare commissioning documents and

operating instructions. To train manpower for O&M function. To associate in commissioning. To prepare plant completion reports.

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VARIOUS TEAMS

Working teams are formed early in erection stage to perform various tasks.

1. To promote quick & effective communication.

2. To support erection team & contractors in efficient & safe commissioning of the plant.

3. To make clear, operational & safety requirements

4. To implement policies & priorities decided by Incharge

5. To report progress, shortage & delays due to staff shortages, safety requirements, plant access, incorrect test procedures, lack of coordination & incorrect plans.

6. To define operation procedures.

7. To define safety requirements.

8. To define maintenance requirements.

9. To define drawings & manuals to be handed over.

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10. To define, agree and provide the number, type & contents of commissioning documents

11. To define an erection and commissioning program

12. To define formats for progress, defects and omissions

13. To decide joint testing teams and terms of tests.

14. To monitor performance & effectiveness of test teams

15. To define and issue necessary certificates which record the stage of completion of erection and commissioning in accordance with agreed procedure.

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BOILER & AUXILARIES

Pre-commissioning check ups.Trial Run of equipmentsGas Tightness and air leak test of BoilerHydraulic Test of BoilerAlkali Boil OutThermal Flow testChemical cleaning of BoilerSteam Boil OutSafety Valve settingCommissioning of BoilerReliability run of boiler

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TYPICAL COMMISSIONING SCHEDULE FOR BOILER LIGHT UP.

Trial of ID & FD Fans Trial run of Air Heater & readiness of AH soot

blowing system- Fire Fighting system. Readiness of light Oil System for Firing. Trial run of ignitor Fans. Trial run of rapping mechanism of ESP. Gas Distribution test on ESP. Air Load test of ESP. Readiness of Feed Pumps. FSSS simulation for bottom elevation. Boiler Interlock & Protection checks. Readiness of bottom Ash Protection and water

seal. Trial run Acid Circulation System

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TRIAL RUNS OF FANS, AH & MILLS All equipments are run independently at least for 8 hours before declaring these available for regular use. Firstly motor is run as per Manufacturer's guidelines. After motor is proven OK then it is coupled with equipment for coupled trials. Trials of all instruments, interlocks and protections are taken.

Trials of FANsTrials of AIR HEATERSTrials of MILLS

Constructional TestsPre Commissioning TestsCommissioning Tests

Trials of ESPsPre-Commissioning Checks – Mechanical: For internal checks use only portable lamps to avoid electrical shocks Shock Bar bolt welding Free Movement of Shock Bars in guides

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Straightness of collecting electrodes rows Check for any foreign materials between electrodes Correct position of gas screen Correction in collecting electrodes guides

Connectivity of suspension tube w.r.to screen tube Emitting electrodes in centre of collecting electrodes Gap between collecting electrodes and vertical beams Tension of emitting electrodes Tack welding of all Nuts and Bolts

Rapping system of Collecting Electrodes Hammer hitting position on the shock pads Lateral shifts of hammers with in +/- 5 mm Setting Fixing

Emitting Rapping Condition of shaft insulator Hammer Hitting position & other settings

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TRIAL RUNS OF FANS Constructional, pre-commissioning & commissioning checks

Constructional:All erection protocols are to be checked for quality audit and handing over note is prepared covering all drawings, T&P and commissioning spares supplied with equipments.

Pre-commissioning: Inspection of Fans (Mechanical, Electrical & instruments) Ensure tightness of all bolts those fixing impeller, bearings, motor

as well as tightness of pressure parts. Lubrication checks on the pump & motor. Checking on the setting of relief valves (Lubricating system) Operational checks on valves & fittings Rotational checks on motor Flushing of oil system & cooling system Final inspection of Fan.

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Commissioning: The starting & operation of Lubrication Oil system

with protection & interlocks.

Operational checks of inlet vanes and discharge

dampers

Operational checks of all valves, strainers and other

devices.

Starting and operational checks of Fan along with its

major components

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AIR & GAS TIGHTNESS TESTSmoke Generators (Type 24 MKS, 40 IBS) are used for easier detection of air leak and ingress points which are sealed containers having chemicals producing huge quantity of smoke when ignited. 1.Furnace Zone: It covers up to goose neck & penthouse. 4 Nos of Gas Generators can be used for this zone by burning just above water seal of water walls on two sides.2.Second Pass of Boiler: This covers area after Goose neck up to air pre heaters. Flue Gas dampers at inlet of both APH are kept closed. 2 Nos of Gas Generators can be used by burning just above Air Pre Heaters.3.Electrostatic Precipitators: This covers area after APH, ESP and up to outlet Dampers of ID Fans. It is divided in to 4 sub section for test purpose. 2 Nos of Gas Generators can be used for each sub section. 4.FD Fan Gas Ducts: HOT AIR DUCT – duct above APH upto burner wind box on each side. COLD AIR DUCT – ducts from FD Fans up to APH.5.PA Fan Ducts: HOT & COLD AIR DUCTs up to Coal Mills.

Air and gas tightness test of boiler is conducted, prior to taking up insulation work, to detect air ingress / leakage points through the fin, attachment welds, flange joints etc, and attend the same. The total area covered is boiler combustor – pass, wind box for burners, Duct works and entire ash path up to economizer outlet damper.

Prior to start of the test ensure work completion on the following fronts: Completion of welding – area wise. Completion of hydraulic test. Refractory areas/ Pour able, cast able insulation works.

The test is carried out in two stages

I. Visual inspection.

II. Tightness test by pressurization with air.

I) Visual Inspection Visual inspection of the entire system is carried out first and noted defects, erection omissions are attended. This work is done by an identified supervisory audit team and Protocol made accordingly.

The critical areas checked are for Completion of fin to fin welding.

•Completion of fin to fin welding.

•Proper closing of all doors - Access Doors and Inspection doors

with asbestos, rope etc.)

•Closing of all corner openings etc.

•Closing of instrument tappings and soot blower openings

•Closing of openings in burner block, respective wing boxes.

ii) Air Tightness Test

The entire system, after executing necessary blanking arrangements, is pressurized and checked for air leakage points, physically and later on with soap solution.

The boiler is checked is stages and the leakage points, elevation wise, are noted. Depressurize and attend to all the identified defects. Repeat the test, till all the all the points are attended to the satisfaction of the supervisory audit team

A protocol is made and boiler is normalized and released for insulation work.

THANKS FOR YOUR VALUABLE TIME

A.R.SAOJI,

arsaoji@gmail.com