V. True or False: For each statement below, circle True or False.

1	T	F	On arrival in port and when the signal “Finished with engine” is received from the Bridge, the turning gear should be engaged.
2	T	F	Warming up of the main turbine should be commenced only when loading arms are connected.
3	T	F	Opening the manoeuvring valve bypass allows a small quantity of steam to pass through the turbine and heat it.
4	T	F	In extreme cases vibration can lead to a blade breaking away from the rotor at high velocity.
5	T	F	All the turbine-casing and main steam-line drain valves should be closed.
6	T	F	All the steam control valves at the manoeuvring station and around the turbine are opened.
7	T	F	The turbine must be run ahead only.
8	T	F	While waiting for the first movements from the bridge, and between movements, the turbine must be turned ahead and astern once every five minutes by steam blasts.
9	T	F	Once warmed through, the turbine rotor must not remain stationary more than a few minutes at a time because the rotor could sag or distort, which would lead to failure, if not regularly rotated.
10	T	F	In cases of abnormal stop (boiler trip or black out) the turning gear should be en-gaged and operated immediately.
11	T	F	Packing steam supply to turbine glands should be always maintained especially when condenser vacuum is high as air will flow into the turbine and might distort the rotor.
12	T	F	The vacuum pumps should be supplied with sealing and cooling water.
13	T	F	Manoeuvring revolutions are usually about 50% of the full away or full speed condition.

 

Translate from Russian into English.

1. Подготовку турбинной установки к прогреванию и пуску необходимо производить, руководствуясь указаниями инструкции завода-изготовителя и дополнительными указаниями старшего механика, в следующей последовательности:

a) осмотреть турбину, зубчатую передачу, обслуживающие механизмы и системы;

b) подготовить и ввести в действие масляную систему;

c) подготовить валопровод и произвести пробное проворачивание турбоагрегата;

d) подготовить паропроводы и систему управления;

e) подготовить конденсационную установку.

2. Прогревание судовых турбин производят при вращении роторов вначале валоповоротным устройством.

3. После окончания прогревания турбин масляный, циркуляционный и конденсатный насосы переводят на нормальный режим работы, поднимают вакуум в конденсаторе до указанного в инструкции значения.

4. После команды дать ход, плавным открытием маневрового клапана повышают частоту вращения ротора до заданной.

5. Во время работы турбинной установки вахтенный механик контролирует: температуру и давление свежего пара, вакуум в конденсаторе, температуру и давление масла, температуру подшипников, частоту вращения валов и т.д.

6. Вахтенный механик записывает в вахтенном журнале все получаемые команды, показания контрольно-измерительных приборов (не реже одного раза в час), все сведения о выявленных неисправностях и время записи.

7. О предстоящих маневрах вахтенный механик должен быть предупрежден не менее чем за полчаса (кроме аварийных случаев и команды «человек за бортом»).

8. Вахтенный механик обязан доложить о предстоящих маневрах старшему механику, подготовить котельное оборудование и вспомогательные механизмы к новому режиму работы.

9. При полном заднем ходе контролируют работу конденсатора и температуру корпусов турбины.

10. Длительность режима заднего хода и частота вращения ротора не должны превышать значений, указанных в инструкциях завода-изготовителя.

 

 

UNIT 11

TURBINE PROTECTION AND CONTROL

Turbine control

The valves which admit steam to the ahead or astern turbines are known as 'manoeuvring valves'. There are basically three valves, the ahead, the astern and the guarding or guardian valve. The guardian valve is an astern steam isolating valve. These valves are hydraulically operated by an independent system employing a main and standby set of pumps. Provision is also made for hand operation in the event of remote control system failure.

Operation of the ahead manoeuvring valve will admit steam to the main nozzle box. Remotely operated valves are used to open up the remaining nozzle boxes for steam admission as increased power is required. A speed-sensitive control device acts on the ahead manoeuvring valve to hold the turbine speed constant at the desired value.

Operation of the astern manoeuvring valve will admit steam to the guardian valve which is opened in conjunction with the astern valve. Steam is then admitted to the astern turbines.

Turbine protection

A turbine protection system is provided with all installations to prevent damage resulting from an internal turbine fault or the malfunction of some associated equipment. Arrangements are made in the system to shut the turbine down using an emergency stop and solenoid valve.

Operation of this device cuts off the hydraulic oil supply to the manoeuvring valve and thus shuts off steam to the turbine. This main trip relay is operated by a number of main fault conditions which are:

1. Low lubricating oil pressure.

2. Overspeed.

3. Low condenser vacuum.

4. Emergency stop.

5. High condensate level in condenser.

6. High or low boiler water level.

Other fault conditions which must be monitored and form part of a total protection system are"

1. HP and LP rotor eccentricity or vibration.

2. HP and LP turbine differential expansion, i.e. rotor with respect to casing.

3. HP and LP thrust bearing weardown.

4. Main thrust bearing weardown.

5. Turning gear engaged (this would prevent starting of the turbine).

Such 'turbovisory' systems, as they may be called, operate in two ways. If a tendency towards a dangerous condition is detected a first stage alarm is given. This will enable corrective action to be taken and the turbine is not shut down. If corrective action is not rapid, is unsuccessful, or a main fault condition quickly arises, the second stage alarm is given and the main trip relay is operated to stop the turbine.

EXERCISES

 

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