HOW TO TURBINE ROLLING THROUGH EHTC & SYNCHRONISATION

Here you'll know the process of TURBINE ROLLING THROUGH EHTC & SYNCHRONISATION

E.1 PRE-ROLLING CHECKS

E.1.1 MS Pressure = 40-45 kg/cm2; Temp = 350°C

E.1.2 HRH Pressure = 12 kg/cm2; HRH Temp = 330°C.

E.1.3 Get clearance from Chemistry Dept. for MS and drum silica content.

E.1.4 Condenser Vacuum > -0.9 mmwc.

E.1.5 All SLCs ON.

MAL drain

TG Lube oil system

HPCF system

PW system

Vacuum Pumps

Seal Oil System

LP Bypass system

E.1.6 HP and LP bypass in service and steam dumping to condenser in process.

E.1.7 Control Fluid TCV in AUTO.

E.1.8 TG Lube Oil temp TCV in AUTO and temp maintained at 42°C.

E.1.9 Gen seal oil system is in service and seal oil DP is 1.2-1.2 kg/cm2.

E.1.10 Gen primary water system is in service and temp control in AUTO (PW temp = 5°C

+ Cold gas temp).

E.1.11 TSC/TSE is in service and keep it ON always.

E.1.12 H2 temp control is in AUTO and hydrogen coolers are charged (set point = 38°C).

E.1.13 All lube oil filters of TG, BFPs, Seal oil system are cleaned with standby filter ready

E.2 TURBINE ROLLING THROUGH EHTC

E.2.1 Get criteria X1 and X2 fulfilled for opening of HP ESVs during HP/LP bypass charged.

X1: MS temp at SH outlet > Saturation Temp of steam (at current MS pressure)

X2: MS temp at SH outlet > Middle wall temp of HPT control valve casing.

E.2.2 RESET the ‘turbine protection’ in turbine protection page and ensure no ‘fault’ or ‘trip’ is being displayed.

E.2.3 Select the turbine ‘EHG’ on from EHTC graphics page and check ‘EHG’ selected is being displayed.

E.2.4 Bring starting device to ‘ZERO’ position; that will generate start up oil and successively trip oil, check pressure of trip oil 8 bar.

E.2.5 Bring speeder gear to ‘maximum’ position.

E.2.6 Raise starting device position to 35-40% and check HP ESVs and IP Turbine IVs are fully opened. Check and ensure that TSE influences is switched ON and available margins are greater than ±30K.

E.2.7 Further raise starting device position to 60% and check HP and IP secondary oil generation.

E.2.8 Check that HPCV body metal temp/HP casing temp are increasing.

E.2.9 Raise the Speeder gear up to 100%. This is will bring EHG in effect

E.2.10 Get criteria X1, X2, X3, X4 & X5 satisfied for speeding up turbine from barring gear to 360 rpm. Turbine is now ready for rolling.

X3: MS saturation temp ahead of HP turbine > Mid wall temp of HPCV

X4: MS temp ahead of HP turbine > Mid wall temp of HPT casing (simulated middle phase shaft temperature)

X5: HRH temp > Simulated midwall temp of IPT shaft.

E.2.11 Checks before speeding up to 360 rpm

E.2.11.1 Check 2nd set of ID & FD fans. (If not started earlier)

E.2.11.2 Start one PA fan and keep PA header pressure control in auto. (Set Pr. 750 mmwc )

E.2.11.3 When hot PA header temperature > 150°C, 1st mill can be taken into service.

E.2.11.4 Start one mill & keep it warmed up, also start 2nd mill & keep it warmed up.

E.2.11.5 Check all other mills & feeders are lined up & all necessary permissive as per the interlock page is available. Acknowledge all faults.

E.2.11.6 Take TDBFPs to service

E.2.11.6.1 Ensure TDBFPs are on barring gear with lube oil supply to bearings and Feedwater side lined up from deaerator to FCS

E.2.11.6.2 Open gland-steam inlet station drain valve & Aux steam block valve is open and downstream temp is in rising trend

E.2.11.6.3 Charge gland steam to TDBFPs at GS temp >200 deg C

E.2.11.6.4 Open casing drain, casing cross drain, gland-steam header drain and GS dump drain to flash tanks. Close inlet station drain to maintain a GS header pressure of 300 mmwc.

E.2.11.6.5 Open Turbine exhaust block valve to condenser gradually , observe condenser vacuum

E.2.11.6.6 Reset turbine and start governing mechanism to open ESV

E.2.11.6.7 Open Aux control valve and maintain live steam pressure approx. 3-4 ksc.

E.2.11.6.8 Give speed demand of 1000 rpm through speed reference and wait for warming up of turbine; casing 50%-100% temp to raise as per live steam temp and diff not greater than 40 deg C.

E.2.11.6.9 Increase speed gradually and take TDBFPs on load when required.

E.2.11.7 Open SH/RH attemperation isolation valves & maintains the temp even by giving spray. Operate the burner tilt as per requirement

E.2.11.8 Check clearance for MS/boiler drum chemistry from chemical lab.

E.2.12 Ensure Speed Control mode is active in EHTC

E.2.13 Raise the speed set point to 360 rpm and watch the actual speed. Ensure tracking device is switched ON, starting device position will automatically track the EHC position. (Speed will increase as per available margin; 100 % margin = 600 rpm/min)

E.2.14 Hold the speed at 360 rpm for about 35 to 40 minutes. Ensure closure of gate valve for turning gear at 240 rpm. Monitor bearing vibrations, bearing temperatures, shaft vibrations, TSE margins and Turbovisory readings.

E.2.15 Get the criteria X1, X2, X3, X4, X5 and X6 fulfilled for rolling at 3000 rpm.

X6: MS temp ahead of turbine > Mid-wall temp of HPT casing/simulated midwall temp of HP shaft.

E.2.16 Raise starting device to 100%

E.2.17 Raise the speed set point to 3000 rpm.

E.2.18 Observe the following

E.2.17.1 Barring gear valve closed at 240 rpm.

E.2.17.2 JOP stops at 540 rpm and AOP stops at 2950 rpm.

E.2.17.3 Record the max bearing & shaft vibration during ramp up.

E.2.17.4 Check bearing vibrations, bearing temp and turbovisory parameters.

E.2.17.5 Check PW parameters (flow/temp/pressure/conductivity/level etc.)

E.2.17.6 Check seal oil parameters & LLD.

E.2.17.7 Check H2 gas system parameters.

E.2.17.8 Check the TG lube oil filters status, if required changeover before synchronization. Clean the standby immediately.

E.2.19 Start hydrogen gas purging in generator and bring purity to >98% (H2/Air).

E.3 SYNCHRONISATION/LOADING

E.3.1 Get X1, X2, X3, X4, X5, X6 & X7 criteria satisfied for synchronization.

X7: HRH temp > Simulated midwall temp of IP turbine shaft.

E.3.2 Get synchronization code from grid

E.3.3 Close Field Breaker and Put DAVR on auto channel (keep ready other channels on standby).

E.3.4 Switch ON excitation system and observe voltage build up to 18.5 kV automatically. Increase excitation by pulses to obtain 21 kV generated voltage.

E.3.5 Now insert the key for synchronization in ECP & Select “ECP” position, then select the synchronization breaker (GCB/401CB/402CB), and select “check” position. Turn on the synchroscope and watch the pointer.

E.3.6 The pointer of the synchroscope will indicate "fast" or "slow" speed of the generator with respect to the grid. Set manually generator voltage & frequency in accordance to grid voltage & frequency by controlling the speed of turbine.

E.3.7 Close GCB (401 CB/402 CB) manually to synchronize the unit when the pointer in the synchroscope slowly approaches the in-phase point/in phase indication glows.

E.3.8 Switch OFF the synchroscope.

E.3.9 Enter load gradient value up to 10MW/Min & load set point as 70MW.

E.3.10 Increase speed reference to achieve the block load ASAP.

E.3.11 Change the mode from SPEED CONTROL to LOAD CONTROL and ensure LOAD CONTROL ON is displayed on EHTC screen.

E.3.12 Adjust MVAR from dAVR panel so that PF is on lagging side (+ve) from leading side (-ve )

E.3.13 INFORM ALL CONCERNED AND GIVE MESSAGE ACCORDINGLY.

E.4 POST SYNCHRONISATION ACTIVITIES

E.4.1 Close HP bypass manually slowly as MS pressure drops after load pickup keeping close monitoring on drum level rapid fluctuation. If kept open for prolonged period then the HP exhaust temp will rise. (Watch HP exhaust temp)

E.4.2 Ensure HPBP warm up valves BP- 01/02 are closed.

E.4.3 LP bypass closes on auto immediately after synchronization. Otherwise close it & put it on auto after making the deviation -ve (by reducing the fixed set-point if required)

E.4.4 Close drains of MS, CRH, and HRH keeping SLC drains 'ON'. Drain pot drains of MS, CRH, HRH and extraction steam lines will operate as per the actuation of level switches. (Check the temp of these drains, if passing suspected after close indication then manually close them further.

E.5 LOAD INCREASE TO FULL LOAD

E.5.1 Unit Load 80 MW

E.5.1.1 Slowly close the HP/LP Bypass & raise load at a faster rate (maximum 60 MW/ Min based on the TSE margin)

E.5.1.2 Ensure that the HP/LP BP has closed.

E.5.1.3 Raise the HPBP pressure set point to 100 kg/cm2 & raise it further along with load.

E.5.1.4 Take mill-B into service. (MS pressure = 55 kg/cm2 and temp = 350°C)

E.5.1.5 Charge deaerator from APRDS by opening ASV-44. Maintain pressure of 3.5 kg/cm2 & temp of 100-110 deg C

E.5.2 Unit Load >150 MW:

E.5.2.1 Start 2nd PA fan & Check PA fans are getting equally loaded & not entering into the stalling zone.

E.5.2.2 Take 3rd mill to service. Reduce LDO pressure accordingly. (MS pressure = 65-70 kg/cm2 and temp = 350°C)

E.5.2.3 Increase load to 220 MW.

E.5.3 Unit Load 200-250 MW:

E.5.3.1 Take changeover of 30% line to 100 % line at load 200 MW

Open valve FDV-16 and close FDV-14 for feed water system

Open valve CDV-22 and close valve CDV-21 for condensate system (if not done earlier)

E.5.3.2 Open SMV-13 & 16 of LPH-2 & LPH-3 and charge them from steam side gradually by opening extraction NRVs-2a, 2b, 3a & 3b and MOVs EXV-11 for LPH-2 and EXV-12 for LPH-3

E.5.3.3 Maintain LP heaters level normal by controlling normal drip valves (Ensure emergency drip valves are ready for operation)

E.5.3.4 Ensure condensate temp is in rising trend (approx. 130-140 deg C)

E.5.3.5 Close SMVs after extraction is fully opened.

E.5.3.6 Charge deareator from IPT extraction by opening MOV EXV-13 & NRV 4.1.1 & 4.1.2.

Close ASV-44 gradually and maintain FST pressure of 4 kg/cm2 and temp 100-110 deg C

E.5.3.7 Take 4th mill into service and raise load to 350 MW. (MS pressure = 90 kg/cm2 and temp = 370-420°C)

E.5.3.8 Remove one elevation oil gun at about 290 MW load. (LDO header pressure to be reduced accordingly)

E.5.4 Unit Load 320 MW:

E.5.4.1 Charge TDBFPs from IP turbine extraction by EXV-15 MOV and Ext NRVs 4.2.1 & 4.2.2

E.5.4.2 Close Aux control valves of TDBFPs by observing live steam pressure in range of 4-5 kg/cm2

E.5.4.3 Take one by one TDBFPs on load and put drum level control on auto.

Stop MDBFP and make it available on Rapid start up-stand by selection

E.5.4.4 Close all drains of TDBFP connected to flash tank A & B after loading

E.5.4.5 Open SMV-1, 4, 7 & 10 of HP Heaters 5A/B & 6A/B & gradually charge the steam side by opening Extraction NRV-5 and MOVs EXV-21, 22, 23 & 25 for HPH 5A, 5B, 6A & 6B respectively

E.5.4.6 Maintain HP heaters level normal by controlling normal drip valves (Ensure emergency drip valves are ready for operation)

E.5.4.7 Watch feed water temp rising at HP heater outlet and Eco inlet (approx. 220-230 deg C)

E.5.4.8 Close SMVs after extractions are fully opened

E.5.4.9 Take 5th mill in service and raise load to 400 MW. (MS pressure = 110 kg/cm2 and temp = 450-500°C)

E.5.4.10 Remove all oil guns.

E.5.4.11 Charge ESP fields & inform Ash handling plant, ensure rapping sequence is in auto (Observe opacity of stack emission)

E.5.5 Unit Load 420 MW:

E.5.5.1 Take 6th mill into service and raise load to 520 MW. (MS pressure = 135 kg/cm2 and temp = 530°C)

E.5.6 Unit Load 520 MW:

E.5.6.1 Take 7th & 8th mill in to service and raise the load to 600 MW ( MS pressure = 165 kg/cm2 and temp = 530°C)

E.5.7 Unit Load 600 MW:

E.5.7.1 Check all systems are on auto as per the scheme.

Furnace draft

Total Air Flow

PA Header Pressure

All Mills Temp & Flow Control

Drum level Control

SH & RH temp Control

HPH 5A/B & 6A/B level control

LPH 1A/B, 2 & 3 Level control

Seal steam control for TG

Seal steam for TDBFPs

Aux PRDS (HT & LT) header pressure & temp control

Deaerator pressure, level & flow control

Hot well make up

E.5.7.2 Monitor all parameters & checks they are in line with full load parameters.

E.5.7.3 Close CBD by consulting chemist.

E.5.8 Observations after achieving full load:

E.5.8.1 Check all boilers, turbine area parameters at full load. Take local round at individual system to check for any abnormal sound, water/steam leakage etc.

E.5.8.2 All boiler side & TG side valves for any leakage, passing, sound etc.

E.5.8.3 Check for any oil, air, coal dust & FG leakage.

E.5.8.4 Check APH area for any leakage.

E.5.8.5 All turbovisory parameters are within limit.

E.5.8.6 All critical parameters are within limit.

E.5.8.7 Bottom & fly ash evacuation are normal.

E.5.8.8 All electrical systems (switchboards, metering & protective devices etc.) are healthy.

E.5.8.9 ESP fields and its auxiliaries are in service.

E.5.8.10 CEMS is in service and emissions are under permissible level.

E.5.8.11 All ventilation system / AC system are in service.

E.5.8.12 Ensure presence of operator and firemen near each individual system.