OPERATION OF STEAM TURBINE PROCEDURE

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OPERATION OF STEAM TURBINE PROCEDURE

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• A well-organized and properly operated plant should have an operating plan that includes instructions for all plant equipment and for interacting systems, of which turbine operation is a part. 

• Before starting the turbine, the operator should become familiar with the general piping layout, the operating characteristics of the unit, and the manufacturer's operating instructions. These instructions will utilize the following general procedures: 

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Starting a small non condensing turbine (like that 

1. Fill all grease cups and oil the governor and other miscellaneous parts. 

2. Open drains on the steam line, separator, casing, and exhaust lines. If these are 

equipped with traps, open the bypass line. 

3. Slowly open the exhaust-line shutoff valve. 

4. If the turbine has a pressure lubricating system with an auxiliary oil pump, 

start the pump. 

5. Inspect the bearings for ample flow of oil; check the oil pressure and see if the 

pump is operating properly (3-5 psi pressure is sufficient). 

6. Turn on the cooling water for the bearings or oil cooler. 

7. Open the throttle quickly to start the turbine. During this time observe the 

turbine carefully for signs of rubbing (a small pipe or rod placed between the 

ear and the points to be checked will aid in detecting unusual noise and rubbing, 

or check the vibration monitoring equipment, if provided). 

8. Slowly bring the turbine up to speed, approximately 300 rpm, and operate it at 

this speed for a period of 15 to 30 min. 

9. Trip the emergency valve by hand to see that it closes properly. 

10. Open the throttle wide and allow the governor to regulate the speed; keep a 

close check to prevent over speeding. Note: If the governor will not control the 

speed at no load, the hand throttle may be used until the load is on. 

11. Inspect the bearings to make certain that they are getting oil. Oil should be up 

to the level recommended by the manufacturer. Usually the level drops when 

oil fills all the various cavities in the system. 

12. The drains, which were opened before the turbine was started, should now be 

closed or arranged to discharge through the trap. 

13. Gradually increase the load on the turbine while keeping a close check on the 

oil, cooling water, and bearing temperatures. 

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Starting a medium-sized or large condensing turbine: 

1. Inspect the governor mechanism, fill all grease cups, and oil as required. 

2. If the boiler stop valve is not open, open it to permit as much heating of the 

steam line as possible and avoid condensation in the line. 

3. Open drains on the following: steam line, separator, throttle, and turbine casing. 

4. Open the stop valve in the steam supply to the auxiliary oil pump. Note: The 

operation of this pump is controlled by a governor to shut off the supply of 

steam after the main oil pump has delivered oil at normal pressure; it opens 

when the pressure fails. 

5. Adjust needle valves to obtain 10 to 15 psi oil pressure on the main bearings 

and 15 to 20 psi oil pressure on the thrust bearing; make sure gauges are in 

operating condition and have been calibrated. 

6. Start the condensing equipment, circulating pumps, and dry vacuum pump; 

operate the condensate pumps as necessary to remove water during the 

warming-up period. 

7. The turbine steam or water seal should be turned on and the vacuum maintained 

at 24 to 26 in. Hg during the warmup period; maintain approximately 1 psi 

pressure in the packing chamber. 

8. Turn on the water to the generator air cooler, and see that water flows properly 

to this and other points requiring water. 

9. If the drain ahead of the throttle valve has been closed for any reason, open it 

again and keep it open until all water from condensation has been removed. 

10. Now open the throttle valve quickly to set the rotor in motion. 

11. As soon as the turbine is rolling, trip the over speed by using the hand lever. 

This is to determine if the tripping mechanism operates properly and to prevent 

the turbine from accelerating too rapidly. 

12. Reset the emergency over speed valve, and before the turbine comes to rest, 

adjust the throttle so that the turbine will operate between 200 and 300 rpm. 

13. While the rotor revolves slowly, use a metal rod or listening device to determine 

rubbing or mechanical difficulty, or observe the vibration monitoring equipment, if provided. 

14. When the oil leaving the bearing reaches a temperature of approximately 110 to 

120°F, start the circulating water through the oil cooler to maintain these 

temperatures. At this time, the bearing oil pressure should again be checked. 

15. Gradually increase the speed. The rate depends on the size of the turbine. Follow 

the manufacturer's instructions. 

16. Adjust the water seal on the turbine and the atmospheric relief valve. 

17. When normal operating speed has been reached and the turbine is under the 

control of the governor, test the emergency governor by opening the valve in 

the oil line to it. See that all valves controlled by this tripping mechanism 

close promptly. Reset, open the throttle valve, and restore speed to normal. 

18. If high-pressure packing is of the water-seal type, adjust the water to 15 psi 

pressure and shut off the steam. 

19. Close the drains mentioned in step 3. 

20. Open the leak-off from the high-pressure packing so that any excess steam may 

flow to the feed water heater or to one of the lower stages of the turbine. 

21. Synchronize the generator and tie it in the line. 

22. With the throttle valve wide open, the speed is controlled by the governor. The 

turbine is now ready for load and is regulated from the turbine control panel. 

• It must be remembered that a large turbine has close clearances and that expansion or improper operation is likely to cause more damage than in the case of a small unit. Large turbines are provided with instruments, including oil-pressure gauges, temperature indicators, and vibration monitors. These instruments should be observed at frequent intervals and the readings recorded on the log sheet or plant computer. 

• In addition to the turbine, the condenser and other auxiliaries require attention, and this phase of the operation must not be forgotten. 

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The turbine in motion: 

1. Apply the load gradually. 

2. Observe the oil level; check to see if an ample supply of oil is going to the 

bearings and the hydraulic cylinder. This can best be observed by watching the 

pressure gauge and sight indicator on the oil discharge. 

3. Watch the oil-bearing temperature. This is always a good indication of over￾heating and mechanical trouble. Temperatures of approximately 140 to 150°F 

are desirable; above 175°F, serious operating difficulties may be experienced. 

4. Observe the turbine for any unusual noise, vibration, etc. 

Shutting the turbine down: 

1. Gradually reduce the load to zero. 

2. Start the auxiliary oil pump, and make certain that the proper pressure is 

maintained while the turbine is coming to a stop. 

3. Trip the emergency valve. In most cases this valve also operates the vacuum breaker. 

4. Close the leak-off from the high-pressure packing; admit steam to the chamber 

at approximately 1 psi, and shut off the water. 

5. Shut off the supply of cooling or condensing water. 

6. Shut down the condensing equipment, and open the drains on the turbine piping 

and casing. 

7. Continue the auxiliary oil pump in operation until the turbine rotor has stopped. 

8. If the turbine is to be left idle for a period long enough for it to cool to room 

temperature, operate the condenser air pump to dry it out. In this way corrosion 

can be avoided. 

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• While a turbine is operating, it is good practice to keep a log sheet or a computerized record of the hourly readings of the instruments. These readings should be taken by the operator while making a regular inspection. On modern units such information is identified to the operator as part of the electronic control system, where the information is also permanently recorded. Such a procedure prevents the operator from neglecting some important inspection, and the data make a valuable record for future reference. 

• The number of readings to be taken depends on the size of the turbine and the number of instruments installed. Some of the readings that might prove valuable are load on the generator in megawatts, throttle steam pressure and temperature, exhaust pressure, extraction pressure, temperature of cooling water entering and leaving the cooler, bearing oil pressure and temperature, and the throttle steam-flow rate. 

• The proper application of oil to the bearings and a continuous flow of cooling water are the main requirements of a turbine while it is operating. The operator detects trouble on the inside of the turbine by noise or vibration or both. An appreciable drop in oil pressure can be corrected by operating the auxiliary oil pump until there is an opportunity to investigate the cause of the trouble. 

• Some small turbines have a number of hand-controlled individual nozzles for admitting the steam. The operator can improve the economy by having a minimum number of these nozzles open for the load at which the turbine is operating.