GOOD PRACTICES IN INSTALLATION

AND OPERATION OF VACUUM

PUMPS AT SITE

PRESENTED BY:

HEAT EXCHANGER ENGG.HARIDWAR (20/04/09)

INTRODUCTION:

� CONDENSER AIR EVACUATION SYSTEM COMMONLY CALLED VAC UUM PUMPS, ARE INSTALLED AT VARIOUS THERMAL POWER PLANT S TO

- CREATE INITIAL VACUUM BY REMOVING AIR PRESENT IN THE SYSTEM (HOGGING MODE)

- DURING OPERATION, ASSIST CONDENSER IN MAINTAINING VACUUM BY REMOVING LEAKED IN AIR & NON-CONDENSIBLE GASES FROM THE SYSTEM (HOLDING MODE).

� VACUUM PUMPS ARE EFFICIENT & RUGGED UNITS AND ARE H IGHLY PREFERRED FOR HIGHER RATING SETS AS THEY PROVIDE TROUBLE FREE SERVICE.

BHEL HAS SUPPLIED MORE THAN 400 VACUUM PUMPS TO VAR IOUS SITES SINCE 1985 WHICH ARE OPERATING SATISFACTORILY .

BEST PRACTICES IN SITE OPERATIONVACUUM PUMPS

INTRODUCTION (CONTD):

� REDUCED COMMISSIONING CYCLES REQUIRE RELIABLE DESIG N & MANUFACTURING, SHORTER DELIVERIES & PROPER STORAGE & PRESERVATION AT SITES.

� IN THE LAST 2 YEARS THERE HAVE BEEN SOME INSTANCES WHERE POWER STATIONS HAVE EXPERIENCED PROBLEMS DURING INI TIAL START-UP OF THE PUMPS CAUSING AVOIDABLE DELAYS.

� IN VIEW OF THE ABOVE, NEED TO ADOPT “GOOD PRACTICES ”DURING VARIOUS STAGES HAS BECOME NECESSARY FOR TROU BLE FREE OPERATION OF THESE CRITICAL EQUIPMENTS.

BEST PRACTICES IN SITE OPERATIONVACUUM PUMPS

CONDENSER

Air Leaks

CoolingWater

Vacuum Pump

Heat Exchanger

TYPICAL VACUUM PUMP ARRANGEMENT

BEST PRACTICES IN SITE OPERATIONVACUUM PUMPS

VACUUM PUMP PACKAGE VIEW

PUMP SKID

SEPARATOR

CHECK VALVE

ROTAMETER

MOTOR

PUMP

R/C PUMP

CONTROLS

LEVEL SWITCH

AIR INLET

BEST PRACTICES IN SITE OPERATIONVACUUM PUMPS

WORKING OF LIQUID RING VACUUM PUMP

BEST PRACTICES IN SITE OPERATIONVACUUM PUMPS

SOME COMMON PROBLEMS ENCOUNTERED AT SITES :

1. JAMMING OF VACUUM PUMPS (NASH MODEL TC-11E, E DWARDSMODEL SHR 22500) FOUND DURING INITIAL COMMISSIONING .

2. JAMMING OF VACUUM PUMP DURING OPERATION.

3. TRIPPING OF VACUUM PUMP ON OVERLOAD.

4. IMPELLER AND CONE CRACKING IN VACUUM PUMPS (N ASH MODEL TC-11E).

5. CONTINUOUS DISCHARGE THROUGH SEPARATOR OVERFL OW LINE (PUMP MODEL TC-11E) DURING OPERATION.

6. DURING HOGGING, SEAL WATER POURING OUT HEAVIL Y FROM SEPARATOR AIR EXHAUST.

BEST PRACTICES IN SITE OPERATIONVACUUM PUMPS

� THIS PRESENTATION FOCUSES ON THE FOLLOWING ASPECTS OF VACUUM PUMPS:

� CARE ON MATERIAL RECEIPT.

� STORAGE AND CONSERVATION.

� ERECTION / INSTALLATION.

� COMMISSIONING AND OPERATION.

� STORAGE DURING SHUT-DOWN.

BEST PRACTICES IN SITE OPERATIONVACUUM PUMPS

MATERIAL RECEIPT:

1. VISUAL INSPECTION TO ESTABLISH RECEIPT OF PACKAGE IN GOOD CONDITION.

2. CHECK FOR COMPLETENESS OF THE PACKAGE.

ANYTHING MISSING/ APPARENTLY DAMAGED MUST BE REPORT ED SO THAT IT CAN BE TAKEN UP WITH VENDOR WITHIN WARRANTY PERIOD.

BEST PRACTICES IN SITE OPERATIONVACUUM PUMPS

INITIAL STORAGE AND CONSERVATION:

1. VACUUM PACKAGES SHOULD BE PLACED ON PUCCA/ SEMI PUCCA GROUND UNDER SHED / TARPAULIN.

2. PACKAGE OPENED FOR INSPECTION SHALL BE SUBSEQUEN TLY COVERED WITH TARPAULIN TO SAVE IT FROM RAIN, DUST A ND PHYSICAL DAMAGE.

DUST AND DIRT HARMS THE DELICATE INSTRUMENTS & FITT INGS

3. PRIOR TO SHIPMENT FROM WORKS, VACUUM PUMP IS FLUS HED WITH WATER SOLUBLE PRESERVATIVES WHICH CAN LAST ABO UT 6 MONTHS (IT CAN THEN DRY UP AND SEIZE THE PUMP); PUM P IMPELLER SHOULD THEN BE ROTATED BY 1 OR 2 TURNS MAN UALLY ONCE IN 15 DAYS.

THIS IS TO PREVENT ANY SEIZURE/ JAMMING OF PUMP TIL L COMMISSIONING.

BEST PRACTICES IN SITE OPERATIONVACUUM PUMPS

ERECTION/ INSTALLATION:

1. THE UNIT IS TO BE LEVELED BY SHIMMING AT THE FOU NDATION BOLTS. PUMP & MOTOR SHAFTS ARE TO BE FIELD ALLIGNED .

2. FOREIGN MATTER LIKE PIPE SCALES, SCRAP METAL, CO TTON WASTE ETC. SHOULD BE REMOVED BY FLUSHING AIR INLET ANDMAKE-UP WATER PIPING, BEFORE CONNECTING TO THE UNIT .

3. THE SCREEN AT THE AIR-INLET SHOULD NOT BE REMOVE D FOR AT LEAST 3-MONTHS OF INITIAL OPERATION.

FOREIGN MATTER CAN DAMAGE/ BREAK PUMP INTERNALS ANDDAMAGE MAKE-UP WATER SOLENOID VALVE.

4. AIR & WATER PIPING SHOULD BE ERECTED SUCH THAT I T IS CONNECTED TO PUMP UNIT WITHOUT SPRINGING OR PULLING

ON THE PIPING.

THIS IS TO AVOID FORMATION OF ANY AIR GAPS IN PIPE JOINTS

BEST PRACTICES IN SITE OPERATIONVACUUM PUMPS

DEBRIS ON MAKE-UP SOLENOID VALVE

BEST PRACTICES IN SITE OPERATIONVACUUM PUMPS

OPERATION & COMMISSIONING:

1. VACUUM PUMP SHOULD NOT BE OPERATED WITHOUT ADEQU ATE INITIAL PRIMING AND SEALWATER AND COOLING WATER FLO W.

POOR EVACUATION CAPACITY, DAMAGED GLAND PACKINGS.

2. SEAL WATER TEMPERATURE DROP IN HEAT EXCHANGER SH OULD BE ABOUT 8 DEG. C. CHECK STRAINER, ORIFICE UNION, S PRAY NOZZLES (IF PROVIDED) FOR BLOCKAGE AND CLEAN, IF REQUIRED. CW TEMP. RISE SHOULD BE ABOUT 2-3 DEG.C.

HIGH SEAL WATER TEMPERATURE RESULTS IN CAVITATION.

BEST PRACTICES IN SITE OPERATIONVACUUM PUMPS

OPERATION & COMMISSIONING: (CONTINUE)

3. THERE SHOULD BE A LEAKAGE OF ABOUT 60 TO 100 DRO PS OF WATER PER MINUTE FROM THE GLANDS (NOT APPLICABLE FO R PUMPS WITH MECHANICAL SEALS).

THIS IS TO AVOID AIR INGRESS THROUGH VACUUM PUMP.

4. DO NOT START THE PUMP IF LEVEL OF SEALING WATER IS ABOVE THE PUMP CENTRE LINE (EXCESSIVE SEAL WATER) OR LESS THAN “LOW LEVEL” (INADEQUATE SEAL WATER).

EXCESSIVE SEAL WATER RESULTS IN TRIPPING OF PUMP.INADEQUATE SEAL WATER REDUCES EVACUATION CAPACITY.

5. CHECK FOR ANY BLOCKAGE OF EXHAUST CHECK VALVE OR ITS LEVER AND MAKE IT FREE.

BEST PRACTICES IN SITE OPERATIONVACUUM PUMPS

STORAGE DURING SHUT DOWN:

1. SHORT TERM STORAGE: DRAIN PUMP OF SEAL WATER AND ONCE IN EVERY TWO WEEKS, MANUALLY ROTATE THE PUMP BY 1-2 TURNS.

2. LONG TERM STORAGE: AFTER DRAINING PUMP OF SEAL WATER, SPRAY A SUITABLECORROSION INHIBITOR (SUCH AS MOBIL- OIL) THROUGH PUMP INLET AND DISCHARGE OPENINGS. ONCE IN A MONTH, MANUALLY ROTATE THE PUMP BY 1-2 TU RNS.

THIS IS TO PREVENT SEIZURE/ JAMMING.

BEST PRACTICES IN SITE OPERATIONVACUUM PUMPS

SUMMARY OF RECOMMENDATIONS/ GOOD PRACTICES FOR TROUBLEFREE OPERATION OF VACUUM PUMPS

� DURING INITIAL START-UP :

- WASH AWAY INTERNAL PRESERVATIVE USING WATER, THRU’TEMPORARY LINES, TILL CLEAR WATER DRAINS OUT.

- IN CASE OF PROLONGED STORAGE, REMOVE CORROSION SCA LES WITH DIESEL. DRAIN OUT DIESEL.

- MANUALLY ROTATE THE IMPELLER TO ENSURE IT ROTATES FREELY.

- THE SCREEN PROVIDED WITH PUMP PACKAGE AT AIR INLET IS TO BE RETAINED FOR AT LEAST 3-MONTHS AND ITS CLEANL INESSENSURED.

BEST PRACTICES IN SITE OPERATIONVACUUM PUMPS

SUMMARY OF RECOMMENDATIONS/GOOD PRACTICES(..contd)

- DM WATER MAKE-UP LINE TO BE FLUSHED THOROUGHLY BEFORE CONNECTING TO MAKE-UP SOLENOID VALVE.

- VACUUM SYSTEM SHOULD BE LEAK TIGHT TO PREVENT SUCT ION OF LARGE AIR QUANTITY CONTINUOUSLY.

- VACUUM PUMP TO START AFTER CHECKING WATER LEVELIN SEPARATOR MORE THAN ‘MINIMUM’ AS INDICATED BY LOWLEVEL SWITCH.

- SEAL WATER PUMP TO START SIMULTANEOUSLY AFTER CHECKING ‘MAIN MOTOR’ HAS STARTED.

- THE EXHAUST CHECK VALVE SHOULD BE CHECKED FOR ITS FREE MOVEMENT AND PROPER CLOSING.

BEST PRACTICES IN SITE OPERATIONVACUUM PUMPS

SUMMARY OF RECOMMENDATIONS/GOOD PRACTICES(..contd)

- THE AIR PRESSURE TO INLET VALVE ACTUATOR SHOULD BE ENSURED TO BE MORE THAN 5 kg/sq.cm.

� DURING OPERATION / SHUT DOWN:

- SHIFT OPERATION TO STAND-BY PUMP ONCE EVERY WEEK O REARLIER.

- DRAIN OUT SEAL WATER COMPLETELY FROM THE SYSTEMDURING SHUT DOWN & DRY-OUT COMPLETELY.

- THE PUMP SHOULD BE ROTATED MANUALLY AT LEAST ONCE EVERY 15 DAYS TO PREVENT HARD SCALE FORMATION.

- MAINTAIN DM WATER QUALITY.

BEST PRACTICES IN SITE OPERATIONVACUUM PUMPS

SUMMARY OF RECOMMENDATIONS/GOOD PRACTICES(..contd)

� OTHER INITIATIVES:

- SUPERVISION BY VENDOR DURING INITIAL COMMISSIONING .

- INTRODUCTION OF PRE-COMMISSIONING LOG SHEETS.

BEST PRACTICES IN SITE OPERATIONVACUUM PUMPS