NTPC/ TSTPP
OPERATION DEPARTMENT
TS-II/OPN/OI/BLR/10
AREA : Boiler
OPERATING INSTRUCTIONS FOR APH Water Washing
Rev 0.00
STAGE - II (4X500 MW units)
A
Date 30//08/06
PURPOSE :This document is prepared to guide the operating personnel while carrying out the APH water washing in Stage- II .
B
SCOPE: :This shall be applicable to all the 4 units of Stage – II (4X 500 MW units ) , TSTPP, NTPC Ltd.
C
INTRODUCTION : In cases when residual deposit accumulations cannot be removed readily by soot blowing, it becomes necessary to water wash the heating surfaces to maintain acceptable draft losses through the air preheater. In some instances, this may be required more frequently than during the scheduled boiler outage. Most deposit accumulations forming on the air pre heater heat transfer surface are highly insoluble in water and, therefore , are easily removed by washing provided sufficient quantity of water is used. Washing devices are located at both the hot and cold ends of the air preheater and they should be operated simultaneously to provide effective removal of the deposit. The stationary multi-nozzle washing devices consist of a straight pipe with (15 degree spray angle) flat spray nozzle spaced to distribute the wash water evenly over the heating surface. Washing pipes are located on the gas side both at CE & HE . Similarly the Fire Fighting system is provided at the CE & HE of the FG side & HE of the air side . Hence in total 5 connections are provided in every air heater .The FD fan and PA fan duct drains must be kept open through out the washing period to avoid water accumulation. The APH wash water is provided from the service water network in each unit with a main isolating valve located at 8.5 mtr near “C: Row . However the individual line isolating valves are provided near the respective air heaters. The scheme is enclosed for reference. Similarly the Fire Hydrant water is provided from the FH net work with the main isolating valve located near the Mill – K . The individual line isolating valves are provided near the APH.
D Sl no
TECHNICAL DATA OF THE SYSTEM Description
PRIMARY AIR PREHEATER (PAPH)
SECONDARY AIR PREHEATER (SAPH)
1.
Make
BHEL
BHEL
2.
Type
Ljungstrom Bisector (Regenerative)
Ljungstrom Bisector (Regenerative)
3.
Air heater size
30 VIM 2000
30 VIM 2000
4.
No. of Air Preheater
2 per Boiler
2 per Boiler
HOT End
Intermediate End
COLD End
HOT End
Intermediate End
COLD End
5.
Type
Double Corrugated
Double Corrugated
Notched Flat
Double Corrugated
Double Corrugated
Notched Flat
6.
Height
850 mm
850 mm
300 mm
850 mm
850 mm
300 mm
7.
MATERIAL
Carbon Steel
Carbon Steel
Corten Steel
Carbon Steel
Carbon Steel
Corten Steel
Sheet 1 Of 4 Prepared By R.N.Das , SS(O)
Approved By D.Sarkar DGM(O)
NTPC/ TSTPP
OPERATION DEPARTMENT
TS-II/OPN/OI/BLR/10
AREA : Boiler
OPERATING INSTRUCTIONS FOR APH Water Washing
Rev 0.00
STAGE - II (4X500 MW units)
Sl no
Description
Date 30//08/06
PRIMARY AIR PREHEATER (PAPH) Squirrel Cage, induction motor, 11KW, 415V, 3ϕ, 50hZ, 1450 rpm, Frame size 160-L, Insulation Class-F
SECONDARY AIR PREHEATER (SAPH) Squirrel Cage induction motor, 18.5KW, 415V, 3ϕ, 50hZ, 1475 rpm, Insulation Class-F
8.
MAIN DRIVE Electric Motor
9.
Speed Reducer Ratio
110 : 1
130.36 : 1
10.
Speed Reducer
Type-IA (3 in put) ;up shaft
Type-2, input Down Shaft.
11.
Final Speed
1.42 rpm
1.12 rpm
3KW, 3020 rpm, Air flow 0.18 3 NM /Sec. at inlet Pressure of 2 6.33 kg/cm
3KW, 4070 rpm, Air flow 0.22 3 NM /Sec. at inlet Pressure of 6.33 2 kg/cm (g).
12.
Air Motor
Water Wash & Fire
13.
Fighting Connections
No of Water wash Lines FG Side HE /CE No of Fire Fighting Lines FG Side HE /CE No of Fire Fighting Lines Air Side HE Total Connections
E
1/1
1/1
1/1
1/1
1
1
5
5
RESPONSIBILITY : UCE /SCE /Recommissioning Group
F
PRELIMINARY CHECKS :-
1.
CHECK FG IN LET TEMP at SAPH in let is \< 1500 C
2.
All Fans ID/FD/PA are stopped .
3.
FG I/L damper is closed. (Optional) . Here not to be closed . ( Closing of these dampers (flap type) will lead to lot of ash falling on APH .
4.
FG O/L damper is closed. ( all 4 )
5.
Air I/L damper is not to be closed , Keep in Maint Mode . This is to allow the water falling on the Fan discharge duct .
6.
Air O/L dampers are closed.
7.
Air receiver pressure is adequate for all APH > 6 ksc
8.
Availability of all Service Water pump & at least two pumps are to be kept in service for water washing.
Sheet 2 Of 4 Prepared By R.N.Das , SS(O)
Approved By D.Sarkar DGM(O)
NTPC/ TSTPP
OPERATION DEPARTMENT
TS-II/OPN/OI/BLR/10
AREA : Boiler
OPERATING INSTRUCTIONS FOR APH Water Washing
Rev 0.00
STAGE - II (4X500 MW units)
Date 30//08/06
9.
At a time two APH can be water washed from any one source i.e Fire Water Or Service Water . So all four APH water washing can be started simultaneously .
10.
SW & Fire water pressure is adequate ( 6 & 10 ksc respectively ) .
11.
All PG at water washing Inlet to APH is calibrated.
12.
BMD HAS GIVEN CLEARANCE AFTER FOLLOWING JOBS.
FD/PA Fan discharge duct drain at 0 Mtr. is opened. ( all 4 nos)
Ladder is provided for inspection.
Manhole before discharge damper is opened. For APH hopper drain the Dummy at Hopper outlet is open All water washing valves are greased. Strainers are cleaned on preventive basis by BMD. FG inlet & outlet duct man holes are opened to check the performance of nozzles at hot & cold end respectively.
Additional fire hoses are available . Air motor lubricator oil is filled. Adequate manpower is available for water wash operation
13.
Chemistry section is informed for taking sample . ( Both clean water & APH drain water )
G
APH WATER WASHING PROCEDURE :-
14.
Stop EM & take air motor in to service .
15. 16. 17. 18.
Keep 2 pumps each i.e SW & Fire Hydrant pumps running . Inform Unit- 1 Control room for maintaining the fire water pressure . The ASPH seal water supply to be changed over to BAHP water . ( Valve near PA Fan- 3A) . One BAHP pump from Unit- 3 &4 to be kept in service on continuous basis till the completion of APH water washing . This will avoid the tripping of ASPS on seal water pressure LO during SW valve operation for APH . Now after ensuring the above line up start water washing in one by one APH . 2 APH from service water wash line & 2 from Fire Hydrant line . The cycle of valve opening is as follows in FG side Only . The Air side valve at HE is not to be operated .
19.
1st one Hour From HE Next one hour From CE Next one hour from both side
Last One hour from HE ( Total operation is for 4 hrs ) Each time the status of Nozzle inside is to be checked for free water flow . Otherwise they are to be noted down for repair/cleaning after wards .
Sheet 3 Of 4 Prepared By R.N.Das , SS(O)
Approved By D.Sarkar DGM(O)
NTPC/ TSTPP
OPERATION DEPARTMENT
TS-II/OPN/OI/BLR/10
AREA : Boiler
OPERATING INSTRUCTIONS FOR APH Water Washing
Rev 0.00
STAGE - II (4X500 MW units)
Date 30//08/06
20.
The condition of all drain points are to be ensured for proper discharge & no water accumulation is taking place either inside the hopper or inside the PA/FD discharge duct . .
21.
Monitor the Boiler “0” Mtr drain for water draining out .
H
DRYING OUT PROCESS :-
22.
The Fans are not be run for drying of APH .
23.
After water washing is declared completed , put them on high speed EM . The natural drying of the APH will continue .
24.
After drying out the Air inlet damper can be closed as desired by Maintenance Group . drying out process :-
CARE DURING THE PROCESS :-
I 25.
Always ensure the water is coming through the hopper drain & duct drain .
26.
If they are choked at any point stop the washing & clear them first .
27.
Water should not be allowed to flow towards the fan .
Sheet 4 Of 4 Prepared By R.N.Das , SS(O)
Approved By D.Sarkar DGM(O)
