JUNE 2012
1
TS TIDINGS
Published by Technical Services / PSSR
For internal circulation
PAGUHTAN CCPP
JUNE 2012
VOLUME : 16.01
HIGHLIGHTS
NEYVELI TS II EXP CFBC, 2 X 250 MW, UNIT 2:
™ TG OIL FLUSHING COMPLETED
NORTH CHENNAI TPS II
2 X 600 MW: UNIT 2 :
™ BOILER LIGHTED UP
™ BOILER CHEMICAL
COMPLETED.
CLEANING
WITH
AMMONIATED
EDTA
WAS
--ooOOoo-TECHNICAL SERVICES / PSSR
JUNE 2012
2
TS TIDINGS
INSIDE
1. STATUS OF PROJECTS COMMISSIONED / TO BE COMMISSIONED DURING
2010 - 2012.
2. SERVICE RENDERED TO OTHER REGIONS/SAS/PROJECTS AFTER CONTRACT
CLOSING/CUSTOMER TRAINING.
3. APPRECIATION FROM CUSTOMER FOR SERVICES RENDERED.
4. FEED BACK ON EQUIPMENTS FROM SITES.
5. LET US KNOW. CHEMICAL TREATMENT FOR SEA WATER USED AS COOLING
MEDIUM
Feed backs and suggestions from all departments of BHEL for improvement of TS
TIDINGS are welcome and may please be addressed to ADDL. GENERAL MANAGER
(TSX)/BHEL-PSSR/CHENNAI
TECHNICAL SERVICES / PSSR
JUNE 2012
3
TS TIDINGS
STATUS OF PROJECTS COMMISSIONED / TO BE COMMISSIONED DURING
2010 – 2012:
BELLARY 500 MW UNIT 2:
™
Mill – G interlock & protection was demonstrated
to customer. Mill – G
coupled trial run was done. Roller setting completed on 02.06.2012
™
SGC logics of TG DMCW for two pumps was demonstrated to customer.
™
CW-C motor - 8 hours trial run completed.
™
Main Turbine lift check with jacking oil was carried out jointly with
customer and Turbine was put on barring gear on 07.06.12. TG waste
fluid tank level switch calibration completed.
™
SAT 02
Transformer
completed on 07.06.12.
™
AHP dry ash system TAC 02 motor no load trial run was completed.
™
Generator Primary water level transmitter calibration was carried out.
™
RODM HCL transfer pump motor was commissioned and run on 09.06.12.
RODM-UF plant was started
on 12.06.12 for DM water generation and
flushing of RO stages 1 & 2 MB system was carried out.
™
FD fan – A 3.3 KV HT cable
™
Clarifier
water
second
source
scheme checking completed.
™
PA fan – A 3.3 KV HT cable HV test was carried out.
™
Boiler blow down pump – 01 motor no load trial run was carried out.
™
TDBFP – B : Barring gear trial run was carried
out for four hours.
Recirculation
valve commissioned from remote. Leak off steam control
valve fine tuning completed.
Exhaust-hood spray line flushing completed.
Turbine interlocks & protection jointly checked with customer. Turbine
rolled with auxiliary PRDS on 27.06.12 for solo run trial.
stability
test, REF
differential
relay setting
HV test was completed on 11.06.2012.
Transformer
interlock protection
and
TECHNICAL SERVICES / PSSR
JUNE 2012
4
TS TIDINGS
™
After attending to actuator defects by M/s Rotork Engineer, 7 nos. of
bunker outlet gate remote operation was demonstrated to customer.
™
SADC remote checking with customer Engineers was carried out.
™
ESP B pass – 2 transformer
cable HV test completed.
™
ESP A pass : ACE 1 upstream, downstream and incomer breakers
completed. CERM/ EERM motors module testing completed.
testing
™
Logic equalization
completed.
purge
circuit
™
Clean air flow test of Mills – E, F & G completed.
™
After replacement of Mills – D & E motor
were run and trial run completed.
NDE bearings, both the
motors
™
AHP – 2 nos. fluidizing
completed.
™
All ( 7 nos. ) mills steam inert line steam blowing
was completed.
™
HBP panel
to HT board synchronization
demonstrated to customer and charged.
for
™
CRH to deaerator pressure control valve CRHV 06 & CBD level control valve
BD 06 commissioned from remote.
™
Mills E, F & G – PA duct leak test (repeat test) was carried out.
™
Turbine rotor axial float of thrust bearing was more (0.47 mm), the same was
corrected by adding shims and bearing pedestal was boxed up.
™
PT plant : 2 nos.
commissioned.
™
Coal flow monitors of feeders – A, C & D were commissioned.
™
RAPCON panel of ESP B, C & D pass checking completed.
™
Raw water
completed.
PH
of
and ESP D pass transformer # 1 11 KV HT
unit 2
air
sodium
transformer
with
blower
unit 1 of
motors
MFT and
no
load
circuit
hydro chlorite dosing
- 2
11 KV
trial run
OBD
pumps
income
cable
to
board
was
was
RW
was
HV test
was
TECHNICAL SERVICES / PSSR
JUNE 2012
5
TS TIDINGS
CPCL PHASE 3 - UNIT 4:
™
GT alignment
03.06.12.
correction was
done
and
boxed up.
Ratcheting
done
on
™
GT was synchronized
™
Graphics modification in DCS completed.
™
Hazardous
™
M/s
Bentley Nevada
established.
™
Off base skid fuel oil leak test was completed.
™
CEMS ( Chimney Emission Monitoring System ) was commissioned.
™
GT was taken upto base load of 21.5 MW and the
mm/sec. Report has been sent to BHEL/Hyderabad.
™
GT was synchronized on 30.06.12 and loaded upto 14 MW with HSD fuel.
on 04.06.12 and reached full load.
gas monitor for GT was commissioned.
vibration
system
to
DCS
communication
vibration was
was
9
MRPL:1XFr.5 GTG, 2X28.5 MW STG, 4X270 TPH UTILITY BOILERS, 1X85 TPH
HRSG, ADDITIONAL ORDER: 1XFr.6B GTG, 1X85 TPH HRSG-GT1.
™
GT 1-Mist eliminator fan - B trial run was done. ELOP no load trial
run was done. Auxiliary hydraulic oil pump trial run was completed. Starting
diesel engine was commissioned. GT 1 was put on ratchet from Mark – VI
panel. GT 1 was made ready for cranking through Mark – VI with charging
of fire water in cooling water system. Customer insisted for commissioning of
FRP cooling water system and fire hydrant system around GT building before
proceeding for cranking.
™
6.6V bus differential testing was completed
™
All the tests were completed in PMCC – 1 & 3.
™
125 V DC battery charger ten
successfully.
hours
inspection
was
carried
out
TECHNICAL SERVICES / PSSR
JUNE 2012
6
TS TIDINGS
NEYVELI TS II EXP CFBC, 2 X 250 MW, UNIT 1:
™
Unit was boxed up on 20/03/12 due to SH 1.2a in FBHE-2 tube leakage.
Repair works are in progress.
™
LRSBs
were commissioned from DCS.
NEYVELI TS II EXP CFBC, 2 X 250 MW, UNIT 2:
™
Acid cleaning
completed .
for
™
SA fan – 2A: Oil
completed.
™
PA fan A – Lube oil system flushing was completed.
™
TG OIL FLUSHING COMPLETED ON 06.06.12.
™
DMCW – A & B motor 8 hours trial run was completed.
™
CEP –2A and 2B motors - 8 hrs. trial run was completed.
™
BFP – 2C : Lube oil flushing was completed.
™
TG Central lub oil system : Oil piping air blasting was completed.
™
RAPH – A – Support bearing and Guide bearing lube oil lines acid cleaning
was completed.
™
ID fan – 2A lube oil system normalization was completed and
kept in service through bearings for flushing pedestals.
™
Detergent flushing of feed water system was completed.
NORTH CHENNAI TPS II
fans
flushing
- SAF 2A & PAF 2A
was
completed. 8 hours
lube
oil
motor
system
trial
oil
run
was
was
system
2 X 600 MW: UNIT 2 :
™
ID fan- 2A motor protection and auxiliary relay testing was completed.
™
RODM : HP pump motor relay testing was completed.
™
ID fan – 2A CH-1 Transformer was charged.
™
VFD panel testing completed.
™
BCW motor HIPOT test
3 nos. completed.
TECHNICAL SERVICES / PSSR
JUNE 2012
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TS TIDINGS
™
OCT - To2 cable HIPOT test was completed.
™
Bottom ash silo MCC relay testing completed.
™
DC scanner fan trial run was carried out.
™
TG AOP 2A & 2B motor
motor trial run done.
™
Generator Bushing and Stator testing completed.
™
Unit service PMCC Transformer
™
Station service PMCC Transformer ODAT01 testing carried out.
™
Condenser transfer pump 2A motor trial run was completed.
™
Boiler drum air vent, super heater vent & reheater vent commissioned from
DCS.
™
EDTA pump – 3 was commissioned.
™
Boiler second cold rinsing completed.
™
LOTV commissioned from remote.
™
DC scanner fan operation
™
RODM : HP pump – A bumped and pump B & C motor no load trial run was
completed.
™
Generator stator
™
Temporary line for fire fighting of APH was completed.
™
Furnace boxing up was completed.
™
Boiler
™
BOILER chemical cleaning with AMMONIATED EDTA AND
COMPLETED.
™
ESP Service transformer 2DBT01 testing was carried out.
™
Raw water
trial run completed. Jacking oil pump ( 2A & 2B )
1DAT02 testing carried out.
checking from remote was completed.
ELCID test was carried out.
was lighted up on 22.06.12 for EDTA.
RINSING
transformer protection checking completed.
TECHNICAL SERVICES / PSSR
JUNE 2012
8
TS TIDINGS
RINL:
™
TB- 4 is in service.
™
LTMCC (5DA & ODA) under voltage relays (ABB Make) testing was
completed.
™
Testing of all HT motors completed.
™
Fixing of
completed.
™
Mill A : Stage – 1
™
11 KV board cleaning and bus bar tightness was done. 11 KV board
breaker penetration and inter changeability test was carried out. 11 KV &
6.6 KV (OBA & OCA) bus duct HIPOT test was completed.
™
ID fan – B hydraulic coupling oil flushing was completed.
™
ACW line charging & flushing of ID fan – A & B, FD fan – A & B, PA fan –
A & B, Mills and APH system were completed.
™
6.6 KV board ( OCB ) out going feeder inter lock and protection checking
was completed.
10 MVA and 20 MVA transformer seal off bushing flexible
lube oil flushing was completed.
SIMHADRI STAGE II, 2 X 500 MW, UNIT 4:
™
PAPH – A : Soot blower swing checking and lance setting completed. Air
motor air line from air receiver tank outlet to air motor inlet air blowing
completed. Fire fighting lines water flushing completed. 4 hours trial run
completed. Soot blower line steam blowing completed.
™
SCAPH lines steam blowing for SAPH 4A & 4B completed.
™
PA fan – A : Lube oil motors – 4
lube oil flushing was completed.
™
Unit was lighted up on 07.06.12.
™
Unit was synchronized and loaded upto 150 MW. TG was hand tripped on
08.06.12 due to high vibration. Balancing of exciter rotor was carried out
to reduce the vibration levels.
™
LRSB lines hydro test and steam blowing completed.
™
ESP – B pass air leak test was done.
hours
trial
run
carried
out.
Stage – I
TECHNICAL SERVICES / PSSR
JUNE 2012
9
TS TIDINGS
STERLITE - 2 X 80 MW UNIT 1 :
™
RAPH – 1
progress.
™
Oil filling was completed in BFP - 1A lube oil tank.
™
DCS system OWS and
was established.
™
MAX panels MFT1, MFT2, UNIT/PURGE and OAB CAB ( Oil AB coal AB ) were
energized and communication with EWS was established.
™
Card board blasting of LDO line from pump house was completed.
™
DCS panels were charged and communicated with EWS.
™
GT was back charged and kept in idle charging (Customer scope)
™
FD fan – 1A motor trial run was completed.
VALLUR
guide
bearing and
EWS
support
PCs
were
bearing
lube
charged and
oil
flushing
is in
communication
panel
3 X 500 MW, UNIT 1:
™
TDBFP A: Oil filling was completed. Lube oil line hydro test completed.
™
TG DMCW system hydro test was carried out.
™
Self
cleaning strainer
signed by customer.
™
Auxiliary Boiler was lighted up on 06.06.12 and run for four hours.
™
TDBFP – B: Turbine bearing normalization and
Booster pump suction line flushing was completed.
™
Acid cleaning of lube oil lines of Mill – G & F was completed.
™
Mill – G main motor 8 hours trial run was done.
™
Seal air fan – B trial run was carried out.
™
ESP – C pass 18 fields
were completed.
™
Boiler hydro test demonstration
Inspector of Boiler.
™
ESP – D pass 13 fields were charged.
™
Boiler was lighted up on 27.06.12.
™
Unit was loaded upto 100 MW and Unit tripped at 1500 hrs. on 30.06.12
due to no coal in bunker and machine came on barring gear on 1600
hours.
of
ACW system
was
commissioned
and
alignment
protocol
completed.
were charged and ESP – D pass OCC & SCC tests
was
carried out in the
presence
of
TECHNICAL SERVICES / PSSR
JUNE 2012
10
VALLUR
™
™
™
™
™
™
™
™
™
™
™
™
TS TIDINGS
3 X 500 MW, UNIT 2
FD fan A : Blade pitch controller setting completed. Trial run was
carried out.
Instrument air line header card board blasting was carried out.
Mill – F: Lube oil motor trial run completed.
SG DMCW : Cooling water lines flushing completed upto ID fan.
SAPH – A: Motor trial run was done.
Service air line and instrument air line header and
branch piping flushing
completed.
CC pump cavity water line stage – 1 purging completed.
SAPH – 2A : Oil draining of support bearing and guide bearing was completed.
LDO lines & atomizing air lines air blasting was carried out.
CC pump stage – II purging was completed.
Furnace Air Tightness Test was carried out.
LDO system : All corner valves termination and commissioning in progress.
SERVICE RENDERED TO OTHER REGIONS/SAS/PROJECTS AFTER CONTRACT
CLOSING.
--- NIL --CUSTOMER TRAINING & TECHNICAL PAPER PRESENTED:
Shri.P Madhusudhan, Manager/Commissioning, Vallur site was deputed to TNEB
Thermal training institute as guest faculty on 16/06/2012 for delivering Lecture on
“Heat Rate improvement in Thermal stations”. Operation and Maintenance engineers
from various power stations of TNEB have attended the training program.
APPRECIATION FROM CUSTOMER FOR SERVICES RENDERED :
--- NIL ---
TECHNICAL SERVICES / PSSR
JUNE 2012
11
TS TIDINGS
FEED BACK NO.1
PROJECT: SIMHADRI SUPER THERMAL POWER PROJECTS, NTPC, UNIT-3, 500MW
PROBLEM: DAMAGE OF STAGE II FAN BLADES AND FIXED GUIDE VANES IN PA
FAN 3B.
Simhadri unit 3 PA fanB 8 hr trial runs was completed on 20.4.11. Unit -3 was
handed over to customer after trial run completion on 04.11.11
Trial run vibration data of PA fan 3B is as below:
PA FAN
3B- LOCAL VIBN MEASUREMENT DETAILS –
Unit- MM/S
RMS
PA 3B-20.4.11
MNDE
MDE
FAN DE
FAN NDE
H
0.4
0.4
1.6
1.3
V
0.4
0.3
0.9
0.8
A
0.4
0.7
1.8
1.6
blade
pitch%
29
Details of PAF-3B
Type - AP2 -20/12
Speed (rpm) : 1480
;
Capacity (m3/s) : 186,
Total head
(mmwc) : 1195 ;
PROBLEM DETAILS:
On 25/10/2011, high vibration was observed (near alarm limit -7 mm/s rms) and this
was reported to M/sBHEL Ranipet .
On 10/11/2011,
NTPC/ Simhadri STPS informed, M/S BHEL Ranipet
that the
vibration in PA fan 3B is about 10 mm/s (rms) in Local and about 15 mm/s (pk) at
Control room. Also customer informed that the vibration analysis indicates looseness
and miss-alignment and suggested for checking the same
PAF-3B was stopped
on 10/11/2011 checked for alignment and tightness all
fasteners and found OK. The fan was restarted on 11/11/2011 and local vibration
reading along with FFT analyzer was taken. The vibration level was found to be same
TECHNICAL SERVICES / PSSR
JUNE 2012
12
TS TIDINGS
as earlier and subsequently found rising to 16-17 mm/s pk close to trip level of 19.8
mm/s –pk
This problem was reported to Ranipet through CAR.
Ranipet engineer reached site on 17/11/2011
and recorded vibrations and ,
informed that there are possibility of internal looseness and mechanical rubbing
inside the fan area. Beside above the following Data were also checked by Ranipet
Engr in detail –
a) Operation parameter for Stalling problem if any but no such operational problem
was noticed.
b) Parameters during paralleling of both fans.
c) Blade pitch checking for local and control room reading matching.
MOM was made with NTPC, Site and Ranipet on 19/11/2011m and requested to send
specialist to open and inspection of fan
The fan was stopped and opened for inspection on 25/06/2012 and the following
observations were made .
1. Second stage outlet guide vanes inlet side 25 Nos. blades & Outlet side 2 Nos.
blades semi-circular portion to a diameter of about 70-100mm parent material
got detached as shown in the photograph attached.
2. Crack in 2 no of vanes in OGV of stage-1 impeller.
3. 05 Nos. blade on 2nd stage impeller torn and 05 Nos. blade bent.
4. 04 Nos. blade on 1st stage impeller bent.
5. Oxides formed on all blades at various levels.
6. Blue paint on blades also got eroded at various levels.
7. PA Fan 3B housing was checked for bearing housing flange seating and found
OK.
BHEL/ Ranipet suggested:
1. Since most of the blades are damaged, PA Fan 3B OGV cannot be used as it is
and hence it is to be replaced.
2. Damaged OGV may be sent to Ranipet for further investigations.
3. All the Fan blades to be thoroughly cleaned and check for any crack by DPT at
site. The results of DPT will be intimated to BHEL Ranipet.
TECHNICAL SERVICES / PSSR
JUNE 2012
13
TS TIDINGS
4. Since some of the blades in 2nd stage impeller torn; they are not to be used.
5. BHEL Ranipet will give new serial number after re-moment sorting on getting the
information from site. The new serial number to be suitably punched on blade at
site.
6. Site intimated that as per the mail and preliminary report ( annexure 2) from
AGM /FES/Ranipet; OGV assembly & blades 2sets will be taken from Unit 4 for
re-commissioning of PA Fan 3B.
7. Replacing of impeller housing assembly since
to avoid complication of repair /
replacement of cracked vanes at site
The following components were cannibalized from PA Fan-4A:
1.Impeller housing
-
1 set
1. Stage-II OGV
-
1 set
2. Blades
-
46 nos.
3. Rectangular ring
-
46 nos.
4. Blade fixing screen
-
184 nos.
5. ELA Pipe
-
2 nos.
6. Joint Pin dia 12 x 75
-
1 No.
7. M30 nut and washer (for foundation stud) 8. Spring washer (SC-16)
-
5 sets.
16 nos.
Apart from the above components PA Fan rotor assembly was taken from customer
spares, Lube oil drain pipe reoriented to reduce the stresses in ELA pipe. Fan re
erection /repair work completed on 12.07.12 and fan was run for 30 minutes with
63% blade opening
VIBRATION READING (VRMS – IN MM/S) IS GIVEN BELOW
locations
Motor NDE
Motor DE
Fan DE
Fan NDE
H
0.6
0.7
1.4
2.1
V
0.3
0.4
1.3
1.3
A
0.3
0.7
1.2
1.3
TECHNICAL SERVICES / PSSR
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JUNE 2012
TS TIDINGS
Total PA flow – 310TPH, Discharge pressure – 735mmwc
Control room vibration reading – X – 1.5 mm/s, Y – 1.3 mm/s (Vpk)
On 07/07/2012, NTPC provided the material composition the guide vanes which got
cracked. This analysis was made with spectrometer available with their FQA dept.
MATERIAL COMPOSITION.
However M/s BHEL /Ranipet is requested to check the material composition
further necessary action and analysis.
for
CONCLUSION:
The damaged materials need to be checked whether they are in order as per drawing.
Based on the operational data stall operational condition could not be found. Also the
PA flow at fan
inlet to be considered for stall checking instead of flow at mill
inlet
The high vibration found is a secondary effect of damages, detailed inspection of the
fan internal need to be done if the vibration
problem persists and necessary
rectification to be done.
COURTESY
SRI.S.S.SAHU, DGM, COMMISSIONING, SIMHADRI SITE
TECHNICAL SERVICES / PSSR
15
JUNE 2012
TS TIDINGS
PHOTOS
TECHNICAL SERVICES / PSSR
16
JUNE 2012
TS TIDINGS
TECHNICAL SERVICES / PSSR
17
JUNE 2012
TS TIDINGS
FEED BACK NO. 2
PROJECT: CHENNAI PETROLEUM CORPORATION LIMITED, GT 4, FRAME 5
PROBLEM: GT HYDRAULIC RATCHET TROUBLE ALARM DUE TO SLOW RATCHET
CYCLE AND SUBSEQUENTLY IT FURTHER DETERIORATED LEADING TO
STOPPING OF RATCHETING AND CLUTCH DISENGAGEMENT.
Problem detail: CPCL GT 4 was put on mechanical ratcheting for the first time on
21/09/2011. The machine was first synchronized on 29/03/2012. The ratcheting
cycle was normal during initial commissioning. Subsequently during start ups in May
2012 for HRSG commissioning, the ratcheting trouble alarm appeared due to time
taken for completion of ratchet cycle was more than 30 seconds. In some occasions of
start ups, the clutch found disengaged. But when the clutch was moved with manual
assistance along with ratchet pump ‘ON’ and energising of solenoid, it got engaged and
ratcheting was ok, but the time taken for the cycle was around 40 seconds. After
sometime, the ratchet was stopped and the clutch did not engage at all.
How the ratchet operates?
The scheme of hydraulic ratchet mechanism is given below for reference.
TECHNICAL SERVICES / PSSR
18
JUNE 2012
TS TIDINGS
The hydraulic ratchet consists of DC ratchet supply pump, hydraulic self sequencing
valve assembly, torque converter mounted ratchet, starting clutch. The most
important part of the ratchet mechanism is the hydraulic self sequencing assembly
which controls the sequencing of the hydraulic ratchet. The self sequencing assembly
consists of
1. Three way poppet solenoid valve (PV).
2. Four way fully pilot operated valve (POV-1).
3. Four way fully pilot operated valve with limit switch (POV-2).
The ratchet cycle starts with the ratchet timer L2HR going high. This in turn will
energize the L20CSX (command to clutch solenoid) and L4HR (the master signal to the
hydraulic ratchet motor). This starts the forward stroke in the ratchet cycle. The
20CS-1 solenoid is energized and ports oil to engage the clutch. Only after the clutch
is engaged, pressure impulse will be build up to the poppet valve (PV) and this valve
will allow oil to port to POV-1. The oil also ports to POV-2 causing the hydraulic
ratchet to operate on forward stroke. This happens for about 12 sec.
Once the forward stroke is completed, the limit switch L33HRF goes high, signaling
the end of the forward cycle. upon completion a port is opened inside the ratchet
assembly which allows a pilot signal to shift POV-1. This causes a shift in POV-2
which will then port oil to the reverse stroke port.
The reverse stroke when completed a port opens inside the ratchet assembly allowing
a pilot signal to shift POV-1 back to its original position. this in turn shifts the POV2 back to its original position. This takes about 8-10 sec and the Limit switch 33HR1 switches back to zero, Signifying the end of the reverse stroke and completion of
the POV's returning to the initial position. This is when the Ratchet timer (3 min
usually) is initiated.
Two sec after the 33HR-1 comes back to the initial 0 position, the clutch solenoid
was deenergised and the hydraulic ratchet motor is stopped. This two second time
delay insures that all the appropriate lines are full of oil for the next ratchet
sequence. This cycle continues after 3 mins once again.
The suction and discharge lines of hydraulic ratchet pump is provided with filters of
40 microns brass filter elements. The differential pressure indication or the switch
are not provided generally in this system. Also, there was no pressure gauge provided
in the pump discharge for regular monitoring. The ratchet pump discharge pressure
relief valve is provided, which is normally factory set (at 93 KSC).
TECHNICAL SERVICES / PSSR
19
JUNE 2012
TS TIDINGS
Analysis:
When the filter elements were cleaned, clutch engages and ratcheting occurs slowly.
After few cycles, the clutch slowly disengages automatically.
The alignment of the jaw clutch and gap adjustments was checked as per product
standard and adjusted. Even after adjustment, the behavior was same.
As the filter elements were physically not having any dirt, the discharge pressure
relief valve was tested in a test bed for its operation. It was found operating at 68
KSC. The same was adjusted to operate at 93 KSC as per the device summary. The
detail of the relief valve and adjustment procedure was given below:
As the figure indicates, there are two nuts in the assembly. One is the adjusting nut
with which the tension of the spring can be varied and thereby set the cracking
pressure for the relief valve. The other is a lock nut to jam and lock the adjusting
TECHNICAL SERVICES / PSSR
JUNE 2012
20
TS TIDINGS
nut at the desired setting. For adjusting the spring tension, the lock nut should be
first loosened separated from the adjusting nut. (this done by limiting the Allen key
depth to engage only the lock nut). Then for adjusting the spring tension the Allen
key is to be inserted further in to engage both the nuts (now since the nuts are apart
both nuts can be rotated to get the desired setting of the adjusting nut. Finally after
the desired setting is achieved, the lock nut alone is to be tightened to jam with the
set adjusting nut (this time again the Allen key is to be inserted to only engage the
lock nut) so that the setting doesn’t get disturbed later.
Even after adjustment of the relief valve to the required value, the clutch did not
engage. One pressure gauge was provided in the discharge of ratchet pump for
observation during operation. The pressure developed was only around 40 ksc with
clutch in engaged position manually and in disengaged position, the pressure developed
was less than 10 ksc. It was suspected to be insufficient oil flow from the pump. It
was decided to remove the filter element from pump suction filter temporarily for
observation. On removing the filter element, the behaviour of ratchet cycle was
normal and the cycle completed within 30 seconds as explained above. New filter was
arranged from BHEL,Hyderabad and the ratchet problem was totally resolved.
Conclusion:
The root cause of the problem of slow ratcheting and disengagement was clogged
filter in the suction of ratchet pump. These filters are brass filters and to be
replaced on clogging. During commissioning, the timings of the forward, reverse stroke
of the ratchet cycle is to be ensured for proper operation as per the scheme
explained above. Any deviation to be rectified and the probable cause of defects in
ratchet mechanism are:
1. Clogging of filters
2. Improper setting of pressure relief valve.
3. Improper setting of limit switches (Clutch engage/Forward stroke of sequencing
valve).
4. Solenoid valve malfunctioning like passing/jamming.
5. Failure of sealing rings in self sequencing valve.
6. Jaw clutch misalignment/ Jamming of clutch in spline shaft.
7. Logic mistakes in mark VI system.
8. Choking in oil ports/pipelines/orifice etc.,
Courtesy:
Shri. M V Baskaran/DGM/Technical services, PSSR, Chennai
TECHNICAL SERVICES / PSSR
JUNE 2012
21
TS TIDINGS
CHEMICAL TREATMENT FOR SEA WATER USED AS COOLING MEDIUM
Sea water is used as cooling medium in condensers of power plants all over the word
either in open cycle or closed cycle with cooling tower. In due course sea water usage
will have biological growth in canal , pipelines , condensers and cooling towers which
leads to blockage of flow path and poor heat transfer in condenser.
To avoid this biological growth different type of chemicals are dosed in the sea
water
1. Chlorination
a. Gas chlorination b.Electro chlorination
2. Chlorine di oxide
3. Ozone
In TS tidings of June 2012, THEPROCESS GAS CHLORINATION is explained in
detail. The other types dosing like ELECTROCHLORINATION, CHLORINE DIOXIDE
and OZONE will be explained in the next issues of TS tidings
Use of chlorine for control of biological fouling in power plant cooling water system is
the most effective way of controlling bio-fouling at reasonable concentration as
chlorine is available at a low cost. Chlorine Gas feeders are simple and easy to control
at low capital cost and requires minimum maintenance. The chlorine residual for shock
dosing can be relatively short and in expensive. De-toxification (dechlorination)
systems can be installed at a very nominal cost to meet the environmental
requirement.
Total residual chlorine (TRC) as expressed in red book of United States of
Environmental Protection Agency (EPA) specifies 0.2 mg/liters TRC. It should not
exceed 160 minutes for 24 hours.
Point of chlorine dosing in Sea Water
Normally the sea water for power plant is taken deep in the sea at Sea water intake
head. The sea water travels through intake pipe and reaches the CW pump sump from
where the water is pumped to the condenser.
TECHNICAL SERVICES / PSSR
22
JUNE 2012
TS TIDINGS
Continuous and Shock dosing chlorination
In Sea water application both continuous and shock dosing chlorination are applied for
effective bio fouling.
Continuous chlorination
At sea water intake head of inlet pipe, continuous dosing of approx. 1 - 2 ppm will be
effective in control of Mollusks, algae, slime and weed. They constrict the flow of
Sea water in the intake pipe. It also prevents sea shell deposition in the pipeline
which is a most trouble-some to remove.
Continuous chlorine dosing is done near to the pump house ahead of bar racks and
traveling water screen. 1-2 ppm is recommended so that the complete bar racks and
traveling water screen can be kept clean and free from any bio fouling. This will also
ensure the pump sump and pump suction side free from any slime growth. The free
residual chlorine and the condenser outlet can be measured to determine the chlorine
dosing as the chlorine demand of sea water varies according to the season and also
the quality of the sea water.
Shock dosing chlorination - Dosing point No.3
Shock dosing of chlorination is done effectively at 1 - 5 ppm depending upon the
quality of sea water. The recommended dosing time is one cycle time for every 8
hours shift which would be sufficient to keep the condenser cooling surface free from
bio fouling and maintain the efficiency of the condenser and power generation.
Theory of Sea Water chlorination
In Sea water at pH 7.4 - 8.1 less than 50% of chlorine is available as fast acting
Hypochlorous acid. However Sea water also contains 60 mg/liter (ppm) bromide ion
which displaces the chlorine, being a stronger oxidizing agent to produce hypobromous
acid.
Cl2 + H20 --------- HOCL + H+ + ClHOCL + Br ---------- HOBr + ClWhen chlorine is dissolved in water, it hydrolyzes rapidly according to the above
equation. The rapidity of the reaction can be expressed that the chlorine molecule
reacting with hydroxyl ion rather than with the water molecule.
TECHNICAL SERVICES / PSSR
JUNE 2012
23
TS TIDINGS
Cl2 + OH- ------- HOCL + Cl
CHLORINE DOSING POINTS
This reaction is of great practical important relating to the chemistry of aqueous
chlorine solution discharging from chlorination equipment. From the chlorinator outlet
the chlorine solution is always limited by design to less than 3500 mg./liter of chlorine
in water. At this concentration the most highly buffered solution will result pH of not
more than 3. At this pH the amount of molecular chlorine in equilibrium with HOCl is
substantial. Concentration higher than 3500 mg/l causes excessive chlorine gas
release, at the point of application which is not desired.
Considering sea water at pH 8 the reaction by addition of chlorine with sea water will
result in the presence of HOCl, OCl, HOBr and OBr and will act to create the hostile
environment for living organism. We will have 70% to 90% HOBr as extremely rapid
toxicant.
The aim of chlorination is to achieve Hypochlorous acid (HOCL) and hypochlorite
ion(OCl which will be effective in preventing fouling of the cooling water circuits. The
fundamental objective in water chlorination is to create hostile environment which will
discourage marine organisms from establishing themselves and growing on the internal
surfaces of PIPE WORK AND CONDENSER SURFACE. The hostile environmental is
created and maintained by continuous chlorination.
Fouling control with chlorine dosage
The control of algae and slime in the pipe work and condensers can be achieved by
shock/intermittent chlorination. The level of continuous chlorination and level of
frequency and duration of intermittent shock chlorination varies from one area to
another. It also depends upon the season of the year depending on biological activity
and quality of water. The optimum treatment is achieved by operating experience.
TECHNICAL SERVICES / PSSR
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JUNE 2012
TS TIDINGS
Continuous chlorination dosing level is in the region of 0.3-2 ppm.
Shock chlorination dosing level is practiced at 2-5 ppm for 1 cycle time for every 4-8
hours. The practice with natural sea water chlorination is to monitor the total 30
minutes demand. The water is dosed with certain quantity of equivalent chlorine. The
residual is measured after 30 minutes. The difference between the initial dose level
and the residual level is reported as the chlorine demand.
Only shock dosing chlorination is not sufficient for effectively treating the sea water
in some areas. When shell forming organisms grow in the water, they attach
themselves to the piping. Even if the organism is killed by Shock chlorination, the dead
remains attached to the piping and subsequently can break free and clog the piping
with disastrous results. Continuous chlorination prevents settlement and growth of
marine organisms. Various tests conducted indicates residual of 0.1 mg/litter will
prevent the growth of marine organisms.
GAS CHLORINATION
TECHNICAL SERVICES / PSSR
JUNE 2012
25
INPUTS
OUTPUTS
TS TIDINGS
Liquid chlorine line (20NB)
Make up water line
Motive water line
JB 220 V Supply
JB 400 V Supply
Chlorine solution line
Gas vent lines
Drain line
TP1
TP2
TP3
TP7
TP8
TP4
TP5
TP6
1. CHLORINATOR 2. VAPOURIZER 3. SAFTY & CONTROLS 4. VALVES
Chlorinator parts
1A Remote vacuum
regulator
1B Cabinet
1C
Flow meter
1D
Flow
control
valve
Differential
pressure
regulator
Vacuum relief
valve
1E
1F
1G
1J
Low
pressure
relief valve
Emergency
drain
relief
valve
Check valve
1K
1L
Injector
Ball valve
1H
Vapourizer Parts
Vapourizing
EC
chamber
Water
bath LCP
chamber
Heater
B1
Vent / Drain line B2
& valve
Insulation
PUF RD1
MAT
FRP Cover
PRV
Expansion Chamber
(V1)
Local Control Panel
(V2&
V3)
Blank Flange Gas
(V4,
V5)
Blank
Flange (V6)
Solution
Rupture Disc
(V7)
Pressure Regulating (V8)
Valve
Ball valve - Cl2
Liquid
Ball
valve
GAS
Inst. Isolation
valve
Electric
solenoid valve
Auto shut off
valve
Butterfly valve
(V9)
Inst. Isolation
valve
(V10) Pressure relief
valve
(V11) Skid
mounting
for
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JUNE 2012
26
LI
Level
indicator
LS
Low
switch
TI/1
Pressure
P1/2
indicator
Level
FT
Filter
Temperature
indicator
VG
Vacuum
gauge
TI/2
Temperature
indicator
C
Cathode
protection
TSC
Temperature
A
contort switch
TSL
TSH
PS
PI/1
Low
Temperature
High
Temperature
switch
Pressure
switch High
Pressure
indicator
Alarm
Chlorine
capacity In
Kg/hr
Connected
load KW
Motive
water line
NB
Chlorine
solution
Line NB
Make
up
waterline
NB
Vent (gas)
line NB
Drain
NB
line
TS TIDINGS
50 75 100 150 200 300
5
8
10
15
20
30
50 65 80
100 150 150
50 65 80
100 150 150
15 15 15
15
20
20
15 15 20
25
25
32
25 25 25
25
25
32
PRINCIPLE OF WORKING OF GAS CHLORINATOR
Liquid chlorine supply from the manifold of tonners to the unit by a 20 NB pipe. The
liquid chlorine enters into the vaporizing chamber at the bottom.
•
The water bath chamber is heated by electric immersion heater to maintain
temperature of water bath at 80°.C. The Temperature control switch is
interlocked with heater for temperature control.
•
Low temperature switch set at 65°.C is interlocked to the ASV (auto shut off
valve) to prevent liquid chlorine flooding the gas line. The High temperature
switch provides alarm and cuts off the heaters.
•
Level switch controller maintains constant minimum level in the water bath
chamber interlocked with solenoid valve on make up water line.
TECHNICAL SERVICES / PSSR
JUNE 2012
27
TS TIDINGS
•
The expansion chamber and liquid chlorine line with a rupture disc and pressure
switch assembly protects the line from rupture due to the thermal expansion of
locked liquid chlorine in the pipeline. The pressure switch provides alarm.
•
Local control panel of vapourizer provides required interlocks indicating lamp and
annunciation for high & low temperature of water bath, low level in water bath
& high pressure in liquid line.
•
The pressure relief valve is provided as safety valve. The filter is provided to
eradicate solid impurities. Pressure regulating valve reduces the chlorine gas
pressure from 8 Kg/cm2 normal inlet pressure to 2.5 Kg/cm2. on the downstream
of PRV
•
The chlorinator part - Vacuum regulator is normally closed and opens only in
case of sufficient vacuum present. The vacuum in chlorinator is created by a
motive water supply operated injector. The vacuum from the injector extends
through the vacuum line up to the vacuum regulator. The flow meter of
chlorinator is calibrated in Kg/hr. of chlorine.
•
The flow control valve on the chlorinator is for manual setting of required flow
in the chlorinator. The Differential pressure regulator maintains a constant
differential pressure across the flow control valve. The Vacuum relief valve is
to maintain maximum vacuum in the system. If the vacuum exceeds it takes
atmospheric air inside for vacuum reduction.
•
The emergency drain relief valve is vacuum to close and will open any water
accumulation in the line more than 300 mm WC. The check valve prevents water
entering.
•
The chlorine solution line is taken to the point of application through a diffuser.
The entire unit is skid mounted with pre-fabricated pipelines with all interconnecting
fittings as shown in the scheme.
TECHNICAL SERVICES / PSSR
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JUNE 2012
TS TIDINGS
UNITS WHICH HAVE ACHIEVED 100% OA
THERMAL
500 MW
RAMAGUNDAM UNIT – 5
TALCHER UNITS – 1, 2, 3, 4 & 5
210 MW
VIJAYAWADA UNITS – 1, 2, 3, 4 & 5
MUDDANUR UNIT – 3 & 4
RAICHUR UNIT – 3 & 4
METTUR UNITS – 3 & 4
TUTICORIN UNIT - 2
NEYVELI UNIT – 7
TECHNICAL SERVICES / PSSR
JUNE 2012
29
TS TIDINGS
UNITS WHICH HAVE ACHIEVED PLF BETWEEN 90 & 100%
THERMAL
500 MW
RAMAGUNDAM UNITS – 4, 5, 6 & 7
TALCHER UNIT– 1 & 2
SIMHADRI UNIT – 1
SIPAT UNIT - 4
VTPS UNIT - 7
250 MW
KOTHAGUDEM UNIT - 9 & 10
210 MW
VIJAYAWADA UNITS –
1, 2, 3, 4, 5 & 6
MUDDANUR UNITS – 3, 4 & 5
RAICHUR UNITS – 3 & 4
METTUR UNITS - 1, 2, 3 & 4
TUTICORIN
UNITS – 2 ,3, 4 & 5
NORTH CHENNAI UNIT – 1 & 3
NEYVELI
UNITS -
4 & 7
.
TECHNICAL SERVICES / PSSR
JUNE 2012
30
TS TIDINGS
PERFORMANCE OF BHEL THERMAL SETS IN SR (210 MW AND ABOVE)
FOR THE PERIOD FROM 01/04/2012 TO 30/06/2012 COMPARED WITH THE
CORRESPONDING PERIOD IN THE PREVIOUS YEAR.
( PLF IN PERCENTAGE )
120.00
STATION
2011-2012
2012-13
North Chennai
90.91
92.51
Neyveli
95.10
93.34
Raichur
81.58
66.40
Tuticorin
87.94
94.22
Ramagundam
89.52
97.20
Muddanur
89.53
85.01
Kothagudam
89.30
88.54
Vijayawada
93.44
95.45
VTPS - 7
98.46
92.88
Mettur
98.07
82.16
Talcher
91.44
92.72
Simhadri
101.62
90.28
Sipat
91.18
98.82
Amarkantak
95.10
90.34
Bellary-1
--
85.37
2011‐12
2012‐13
100.00
80.00
60.00
40.00
20.00
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TECHNICAL SERVICES / PSSR