Instrumentos

1. PRE-COMMISSIONING CHECKS - MECHANICAL

1.1 Internal checks: Caution - Use only portable lamp operated by dry cells to avoid electric shocks.

a. Shock bar bolt welding.

b. Free movement of shock bar in guides. c. Straightness of collecting electrodes rows.

d. Check for- any foreign material between the electrodes. e. Correct position of gas screen.

f. Correction of collecting electrode guide.

1.2 Concentricity of suspension tube with respect to screen tube. a. Emitting electrodes in centre of the collecting electrodes. b. Gap between collecting electrodes and vertical beams. c. Tension of emitting electrodes.

d. Distance between collecting electrodes and vertical beams. e. Tack welding of all bolts and nuts.

1.3 Rapping system of collecting Electrode

a. Hammer hitting position on the shock pads.

b. Lateral shift of hammers with reference to shock pad centre max. allowed ± 5 mm.

c. No fouling of hammers with the gables, walls etc. d. Setting fixing.

e. Tack welding of fasteners on rapping system. 1.4 Emitting Rapping

a. Condition of shaft insulator.

c. Direction of rotation of screws. d. Tack welding of all fasteners. e. Set ring fixing.

t. Axial play of shaft insulators 10 mm.

1.5 Check for presence of foreign material and cleanliness of the hopper and walls.

1.6 Check the doors to ensure free swinging easiness to open and close no seizing of nuts.

1.7 Check the gaskets (asbestos rope) on the Inspection door for proper tightness.

1.8 Conduct gas tightness test before the gas distribution test and the insulation work is done.

1.9 Gas distributor screen.

Conduct gas distribution test and ensure following:

a. Check for the positioning and locking of deflection elates and throttling plates on the screen sheets.

b. Check for removal of all temporary arrangements (rounds of ladder etc.)

c. Check for minimum distance of 100 mm between the bottom screen and the front cable to prevent dust deposits in the inlet dust of EP.

1.11 Top of EP Insulator Housing

a. Condition of support insulators. b. Heater location and fixing. c. Tight fixing of bare conductors. d. Plugging of lifting tool inlet. e. Check earthing cables.

f. Proper closing of housing cover.

2. PRE-COMMISSIONING CHECKS - ELECTRICAL

2.1 Geared Motors

a. Check insulation value. Note down the value.

b. Check winding resistance 40 to 50 ohm equal in all 3 phases. Note down the values.

c. Check oil levels.

d. Check cable connection from panel to motors. 2.2 Heaters

a. Check heater continuity and resistance - Note the values. b. Check insulation - Note the values.

c. Check thermostats and its connection.

d. Check cable connection from panel to heater and thermostats. 2.3 Auxiliary Control Panel :

2.3.1 Precommissioning

a. Check insulation value. Megger R.Y.B. of incomer, outgoing cable and main switch between phases and phase to earth values greater than 2 Megaohms acceptable.

b. Check fuses.

c. Check wiring and components. d. Clean by air blowing.

2.3.2 Commissioning of Auxiliary Control Panel a) Disconnect heaters, motors from panel. b) De-couple motors from rapping mechanism. c) Remove programmer from the module.

d) Switch on supply to panel. Supply on bulb should glow. e) Press rapping mechanism start button.

g) Keep the switches on the programmer module in continuous operation.

h) check all protections for motors and heaters. In case of motor check fault indication.

i) Switch off panel.

j) Press start push button for rapping motors.

k) Connect out going terminal for motors and heaters.

l) Check direction of rotation of motor. Ensure proper rotation before coupling to rapping mechanism.

m) Check if all motors run for 1 minute before stopped by the timer. 2.4 Testing of transformer rectifier set: Open circuit test (at partial loading)

should be carried out by authorised engineers.

In this case, the results of the test should be tallied with (he results in the test certificate. Equipments and instruments required for this purpose are :

a) Voltmeter 0- 500 Volts AC

b) Ammeter 0- 5 amps (C.T. ratio 50:5) c) Suitable cables and leads for instruments.

d) Air cooled portable type single phase, 50c/s, 28 amps. 0-470 volts variable auto transformer.

3. BEFORE THE FIRST LIGHT UP OF THE BOILER

a) Civil work of control room for EP should be ready in all respects like inside plastering, white washing, lighting, with proper ventillation as agreed upon.

b) Electrical power supply should be availed to put at least all rapping, motors into operation. It is preferable to make available the total required power.

c) Pre-commissioning check - Mechanical is done. d) Pre-commissioning check - Electrical

i) Electrical motors are done.

ii) Rapping motors are put into trial run and continuously thro' Auxiliary control panel during oil firing.

4. GAS DISTRIBUTION TEST

4.1 Test is conducted preferably before first light up. 4.1.1 Gas Distribution Test of E.P.

The E.P. being in the gas path, is not available for mechanical adjustments once the boiler is lighted up. Its satisfactory performance from the very beginning ensures a long life of ID fan and hence it is desirable to commission E.P. in a systematic way in all respects before the first light up of boiler. It is recognised that it would be possible to commission E.P. before first light up of boiler by proper scheduling the jobs from the beginning. Gas distribution test, normally called as G.D. test, is one of the tests to be conducted after interval erection of EP is completed in all respects.

The purpose of the gas distribution test is to check and correct the gas flow inside E.P. chamber by fixing deflection plates on the distribution screen at suitable locations. The best time to conduct CD test is prior to first light up of boiler. Ensure erection of E.P. internals is completed and availability of I.D. & F.D. Fans. To start the G.D. test, ID AND FD fans are kept running and gas flow is adjusted with the inlet vane control of fan,

such that average air velocity obtained is m/sec. in one of the panes. The velocity readings are to be taken by an anemometer in the rear end of first field. Where first field is a dummy, these readings are to be taken in the second field. Each field is divided into number equal zones and velocity measured at various heights in each zones. The velocities and flow pattern are to be studied to determine to fix the deflector plates in the gas distribution screen. These deflector supplied by Trichy can be easily hooked . in the zones very high velocities are noted. Velocity measurements are to be repeated after fixing the plates to calculate the efficient of variations which is limited to 20%. The GD test as described above for one path is to be repeated in on the remaining three paths. 4.1.2 Air Load Test of E.P.

Air load test of E.P. is also to be conducted prior to first up of boiler to indicate the alignment of internal healthiness of insulators and the transformers/rectifiers. As the test is conducted in the medium of air prior to first light up, the test is called as air load test. Detail checks to commission EP rectifier transformer and control panels are separately given. All the electrical equipments are commissioned and available for air load test. To conduct air load test, ID/FS fans are kept in service and all the E.P. zones are charged. Volt-ampere characteristic of each field is tabulated.

Steam coil Air Preheater should be put into operation to obtain flue gas temperature at the inlet of EP to 105°C during initial operation.