Procedure for Condenser Flood Test and Vacuum Tightness Test

Station: NTPC- Simhadri

BHEL Ref No.PS-DC-186-500-0016 NTPC Ref no SIM/1/TS/2/004

Sheet 1 of 12

Plant area: TURBINE PROCEDURE FOR CONDENSER FLOOD TEST AND VACUUM TIGHTNESS TEST SLNO

1.0

PLANT DETAILS

2.0

OBJECTIVE

3.0

PROPOSAL

4.0

SERVICES REQUIRED

5.0

SAFETY PERECAUTIONS

6.0

EMERGENCY PROCEDURE

7.0

STATE OF THE PLANT

8.0

METHOD

9.0

COMPLETION CRITERIA



Sheet 2 of 12

Plant area: TURBINE PROCEDURE FOR CONDENSER FLOOD TEST AND VACUUM TIGHTNESS TEST STATUS SLNO

1.0

PLANT DETAILS:

1.1

The plant consists of condenser, Hotwell, 2 Nos, of vacuum Pumps and drains and vents from different specified systems to condenser. Vacuum system is mainly to condense steam exiting the LP Turbine at subatmospheric pressure so that the over all efficiency of the cycle is improved. Also the condensed steam is re-cycled with out wastage. Functions of the main equipment system are as given below.

1.2

Condenser : It is mainly to condense the steam coming out of LP turbine last stage by admitting cooling water in the tubes. The steam loose its enthalpy to cooling water while condensing.

1.3

Hot well : This is to store the condensate arising out of cooling of steam and give the suction head to condensate pumps.

1.4

Vacuum Pump :This is to evacuate the air-vapour mixture from the condenser and create a negative pressure to improve the cycle efficiency.

1.5

Plant item completion list for mechanical, Electrical and C & I to be prepared at site.

1.6

Signed copy of SRCC to be enclosed.

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BHEL



Sheet 3 of 12


2.0

OBJECTIVE: The objective of the procedure is to check the system for air ingress points and to achieve the desired rated vacuum.

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BHEL



Sheet 4 of 12


3.0

TESTING PROPOSAL: The objective is achieved by carrying out the following test proposals.

3.1

STAGE – I Water Fill Test The tightness of the system shall be established by water fill test. Under this all the equipments and systems coming in contact with condenser are filled with DM water and leaks are noticed. Then the leakage points are arrested to prevent the air ingress while vacuum is raised.

3.2

STAGE – II Vacuum Pulling Vacuum is raised to check the tightness of the system which were not included in the water fill test. During this test, the parts which were not subjected to water fill test are examined for any air ingress and the same will be arrested after identification. By this, the entire system is tested thoroughly to obtain the desired rated Vacuum for better performance of the steam cycle.

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Sheet 5 of 12


4.0

SERVICES REQUIRED:

4.1

Availability of DM water for water fill test.

4.2

Availability of proper illumination around the equipments in the test area.

4.3

Availability of Condenser cooling water system.

4.4

Availability of H.T/L.T Power supply (for operating CEP, Vaccum Pumps)

4.5

Availability of communication facility at test area.

4.6

Availability of Man Power and T & P for leak detection and attending.

4.7

Availability of Portable fire extinguisher at test area.

4.8

Availability of dewatering pump near test area and a pit for dewatering.

4.9

Availability of flexible polythere tube for level monitoring in condenser steam space.

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Sheet 6 of 12


5.0

SAFETY PRECAUTIONS :

5.1

Ensure the availability of first Aid Box near the test area

5.2

Ensure that the personnel deployed to check the system leakage are provided with required safety gears, such as helmets, safety belts etc.

5.3

Ensure proper temporary scaffolding is provided to reach condenser neck portion and other unapproachable areas wherever required.

5.4

Ensure the test area is clean and devoid of obstruction and the required flooring completed.

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Sheet 7 of 12


6.0

EMERGENCY PROCEDURE:

6.1

The personnel for this operation shall be well aware of the layout of this system.

6.2

They shall be in a position to use the safety devices while searching for leaks during testing.

6.3

Test Team should be aware of emergency steps to be taken on the event of any accidents occurring to men and material while conducting the test.

6.4

During the test, all precautions to be taken at local and remote to observe the running CEP, Vacuum pump and any tend in increase in bearing temperature or vibration should be communicated to control room for appropriate follow up action.

6.5

Test team should be aware of operation of portable fire extinguishers.

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Sheet 8 of 12

Plant area: TURBINE PROCEDURE FOR CONDENSER FLOOD TEST AND VACUUM TIGHTNESS TEST SLNO STATUS

7.0

STATE OF THE PLANT:

7.1

For water fill test; The following are completed.

7.1.1

Erection of condenser and connected piping of vacuum system as per recommended drawing.

7.1.2

The erection work in LP casing exhaust.

7.1.3

Removal of temporary platform, if any erected in LP casing exhaust.

7.1.4

The permanent hangers and supports for connected piping.

7.1.5

Removal of temporary supports.

7.1.6

Make up water line to condenser for filling the condenser steam space.

7.1.7

Installation of flexible polythene tube for monitoring the water level in condenser steam space.

7.1.8

Locking of the jack bolts of condenser springs before starting water fill test so as to arrest the spring action.

7.1.9

Locking of all the hangers of drain flash tanks and connected pipe Lines in vaccum system.

7.1.10

Installation of level gauge glass of hot well, LP heaters and HP heaters.

7.1.11

Cleaning of hot well.

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Sheet 9 of 12


7.1.12

Installation of level switches and level transmitters for hotwell level & LP Heaters & HP heaters.

7.1.13

The piping & tanks under vacuum system are not to be insulated including at welding joints and flange joints, manholes, root valves, stubs etc.

7.2

For actual vacuum pulling: The following are completed

7.2.1

Vacuum pumps are ready for operation.

7.2.2

Gland seal steam exhauster fans trial run completed.

7.2.3

CEP trial run completed with required interlock and protections. (The list of minimum interlocks and protections to be mutually prepared at site).

7.2.4

Gland steam control valves commissioning.

7.2.5

Availability of mercury manometer/calibrated gauge.

7.2.6

Charging of cooling water to condenser water boxes.

7.2.7

Vacuum breaker valve commissioning.

7.2.8

Barring gear with interlocks & protections should be ready.

7.2.9

Gland sealing water lines for valves coming under vacuum system are completed.

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Sheet 10 of 12


8.0

METHOD:

8.1

Water fill test

8.1.1

Start filling water in system gradually. Release the air of LP Heaters, HP Heater, Drain cooler and Gland steam condenser by opening their vent valves during filling.

8.1.2

Check for leakages in the system after every 1 M rise in water level.

8.1.3

Drain and attend leakage wherever leaks are noted.

8.1.4

Check the leakages upto 1 M above tube nest and maintain this level during this test.

8.1.5

Drain the system and attend all leakages.

8.1.6

After the completion of leak test, clean hot well and release the jack bolts of condenser springs.

8.1.7

Fill Hot wall up to normal level.

8.2

Vacuum Pulling

8.2.1

Run one CEP on recirculation.

8.2.2

Put machine on barring gear.

8.2.3

Line up seal steam supply and gland steam cooler.

8.2.4

Start one seal steam exhauster fan and both vacuum pumps. After achieving about 0.2 kg/cm 2 vacuum, charge seal steam to turbine glands. Downstream parameters to be maintained are: Pressure : 0.01 KSC and temp > 160 oC

8.2.5

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Sheet 11 of 12


8.2.6

Check system for air ingress points if proper vacuum is not achieved and same shall be rectified.

8.2.7

Stop one vacuum pump when desired vacuum is achieved and stabilised. However, if with one vacuum pump, vacuum is not holding then check for air ingress and attend the leakages.

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Sheet 12 of 12


9.0

COMPLETION CRITERIA:

9.1

Condenser Flood Test and Vacuum tightness test is completed with following completion criteria.

9.2

Condenser Flood Test is completed after satisfactorily attending all the identified leakages.

9.3

After achieving the required vacuum, stop both vacuum pumps and record the rate of fall of vacuum 10 minutes. The rate of fall of vacuum should be 2 to 3 mm of Hg per minute.

9.4

After attending all the leakages, total hogging time taken for achieving full vacuum shall be noted down by running each vacuum pump separately one by one and by running both the vacuum pumps together.

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PROCEDURE FOR CONDENSER FLOOD TEST AND VACUUM TIGHTNESS TEST

Procedure for Condenser Flood Test and Vacuum Tightness Test

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