galyatova_v_n_lelet_i_a_angliyskiy_yazyk

Selection of marine power plants

1.Good reliability

2.Good maintainability

3.Weight and volume

4.Type of fuel and fuel consumption

5.Cost

6.Vibration and noise

7.Level of experience for personnel

Types of marine power plants

1.Diesel engine driven

2.Gas turbine driven

3.Steam turbine driven

The propulsion system of a diesel-driven ship includes main en­ gines and supporting systems: fuel system, lubricating (oil) system, cooling system supercharging system, starting and reversing system as well as couplings, reduction gear, shafting and a propeller - fixed pitch or variable-pitch propeller (controllable-pitch propeller - CPP).

The power plant of a gas turbine driven ship is made up of three components: the air compressor, the combustion chamber and the gas turbine. On gas turbine driven ships, the conventional gas turbine is combined with a power turbine which provides the power to the ship’s propeller. The gas turbine drive shaft contains the turbine starter, and the auxiliary pump drives for the different systems. Hot exhaust gases from the gas turbine are fed into the power turbine. The power turbine is much slower running than the gas turbine. It has blades, rotors as noz­ zles similar to that of a normal steam turbine.

The propulsion machinery on a steam turbine driven ship includes the propulsion turbines, the boilers, the condensers, the reduction gears, and the pumps, blowers, deaerating feed tanks, and other auxiliary ma­ chinery components, which serve the major propulsion units.

The propulsion machinery spaces may be arranged in several ways. Some ships have fire rooms (containing boilers and the stations for operating them) and engine-rooms (containing main engines and stations for operating them). Many large ships of recent design have spaces, which are called machinery spaces. Each machinery space contains the boilers and the main engines.

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Exercise III.

Translate into English.

1.Энергетическая установка газотурбохода состоит из воз­ душного компрессора, камеры сгорания и газовой турбины.

2.Вал привода газовой турбины содержит стартер турбины и привода вспомогательного насоса для различных систем.

3.Горячие отработанные газы от газовой турбины подаются в силовую турбину.

4.Главная ЭУ паротурбохода включает в себя главные турби­

ны, котлы, конденсаторы, насосы и некоторые другие вспомога­ тельные механизмы.

5. Машинно-котельное отделение - помещение на судне, в ко­ тором размещены главные двигатели и котлы.

Exercise IV.

Read and translate text В in written form.

Text B.

Engine room

In a ship, an engine room is where the main engine(s), generators, compressors, pumps, fuel/lubrication oil purifiers and other major ma­ chinery are located. It is sometimes referred to as the "machinery space". Engine Rooms are typically towards the stern, or rear, of the boat from the crews living accommodations. On modern ships, a sound-proofed, air-conditioned engine control room (ECR) is situated next to the engine room (HR), for the ship's machinery control systems.

Engines

An engine room will usually contain multiple engines, either diesel or heavy fuel. The engines are used to provide mechanical power to generators (which generate power) and the main propulsion propeller (the "screw"). Several different layouts exist, some involving gear boxes. As well as the main engine (or 'prime mover'), an engine room will often contain numerous other engines. For example, a typical steamship's engine room will also contain smaller steam engines driving ballast-trim pumps, water circulating pumps, boiler feed pumps, fuel oil

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pumps etc. On modern ships these functions are usually performed by smaller diesel engines or electric motors.

The electricity generating plant powers the ships electrics and pumps. This often runs on separate engines, with an array of smaller generators contributing towards the ships required power levels. A mar­ gin of error will be allowed, e.g. a ship requiring 3000 kW of power might employ four 1000 кW generators.

Engine cooling

The engine(s) get their required cooling by means of liquid-to- liquid heat exchangers connected to fresh seawater or divertible to recir­ culate to tanks in the engine room which are also full of sea water. Both supplies are used to draw heat from the engines via the coolant and oil lines. The heat exchangers are plumbed in so that oil is represented by a yellow mark on the flange of the pipes, and relies on paper type gaskets to seal the mating faces of the pipes. Sea water or brine, is represented by a green mark on the flanges and internal coolant is represented by blue marks on the flanges.

Thrusters

In addition to this array of equipment is the ships thruster system, typically operated by electric motors controlled from the bridge. These thrusters are laterally mounted propellers that can suck or blow water from port to starboard (i.e. left to right) or vice versa. They are normally used only in maneuvering, e.g. docking operations, and are often banned in tight confines, e.g. dry docks.

Thrusters, like main propellers, are reversible by hydraulic opera­ tion. Small embedded hydraulic motors rotate the blades up to 180 de­ grees to reverse the direction of the thrust.

Safety

Engine rooms are hot, noisy, sometimes dirty, and potentially dan­ gerous. The presence of flammable fuel, high voltage (HV) electrical equipment and internal combustion engines (ICE) means that a serious fire hazard exists in the engine room, which is monitored continuously by the ship's engineering staff and various monitoring systems.

Exercise V.

Put 10 questions to the text.

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UNIT IX.

Main and Auxiliary Turbines

Text A.

Main and Auxiliary Turbines

Steam turbines are used for ship propulsion and for driving auxi­ liary machinery units associated with the propulsion plant, such as lubri­ cating oil pumps, condensate pumps, feed pumps, circulating pumps, fuel oil pumps, forced draft blowers, and electric generators.

Steam turbines can be classified as follows:

-by the purpose they are designed for:

•main - Main steam turbines are used for ship propulsion.

•auxiliary - Auxiliary steam turbines are used to drive the auxi­ liary machinery units such as pumps, electric generators, etc.

-bv the action of steam:

•impulse - These turbines have fixed nozzles that direct the steam flow into high speed jets. These jets contain significant kinetic energy, which the rotor blades convert into shaft rotation as the steam jet changes direction. A pressure drop occurs across only the stationary blades, with an increase in steam velocity.

•reaction - In these turbines the steam expands in both the sta­ tionary and moving blades. The moving blades are designed to utilize the steam jet energy of the stationary blades and to act as nozzles them­ selves. Because they are moving nozzles, a reaction force produced by the pressure drop across them supplements the steam jet force of the sta­ tionary blades. These combined forces cause rotation.

•impulse and reaction combined - The combination of impulse and reaction types.

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-bv the drive connection:

•geared units - In the geared-turbine drive, reduction gears are employed in the shaft between the turbine and the propeller. In installa­ tions where the high pressure and low pressure turbines are geared to the same shaft, it is common practice to incorporate the astern turbine in the exhaust end of the low pressure casing.

•turbo-electric installations - In the electric drive, the necessary speed reduction is done electrically. The steam turbine drives electric generators, which in turn supply power to motors for dri-ving the propel­ ler shaft. The advantage of the turbo-electric installation is that it allows the adoption of high-speed turning turbines to the slow turning propel­ lers without the need of a heavy and complex gearbox. This system also provides excellent manoeuvrability, elimination of astern turbine, in­ creased economy at reduced powers and reduction in shafting if the mo­ tor is located in the after end of the ship.

Marine steam turbines are required to be reversible. This is nor­ mally achieved by the use of several rows of astern blading fitted to the high-pressure and low-pressure turbine shafts to produce astern turbines. About 50% of full power is achieved using these astern turbines. When

the turbine is operating ahead the astern blading acts as an air compres­ sor, resulting in windage and friction losses.

Exercise I.

Match each item in column A with an appropriate item from column B.

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Exercise И.

Complete the sentences with the correct form of the verb in bra­ ckets. Some verbs are passive.

1.The two principal types of steam turbine ship propulsion plants in use today (be) the geared-turbine drive and the turbo-electric drive.

2.Steam turbines (use) for ship propulsion and for driving auxi­ liary machinery units associated with the propulsion plant.

3.Auxiliary steam turbines (drive) the auxiliary machinery units such as pumps, electric generators, etc.

4.The turbo-electric installations (have) a single turbine unit for each installed shaft.

5.In the geared-turbine drive, reduction gears (employ) in the shaft between the turbine and the propeller.

Exercise III.

Put questions to the sentences.

1.In impulse turbines steam energy is transferred to the rotor by the steam jet.

2.These stationary nozzles expand the steam from a high pressure

to a lower pressure.

3.In reaction turbines the steam is directed into the moving blades by the fixed blades.

4.Expansion in the nozzles produces maximum possible velocity of the steam jet.

Exercise IV.

Answer the questions.

1.What are steam turbines used for?

2.How can steam turbines be classified by the purpose they are designed for?

3.What is the function of the auxiliary steam turbines?

4.What is the difference between impulse and reaction turbines?

5.How are steam turbines classified by the drive connection?

6.What is the advantage of the turbo-electric installation?

Exercise V.

Read and translate text В in written form.

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Text В.

Instruction for Operation

Starting the Turbine

Before staring a unit certain precautions should be taken to make sure that the unit is ready for operation. The unit should be absolutely clean inside and out, and all parts securely fastened.

The following procedure for starting the unit should be observed: measure clearances where indicators are installed. See that the turbine rotors and gears move freely. This may be done by turning the units by means of a motor-driven turning gear.

All valves and cocks for draining water from the main steam pipe, maneuvering valves and turbine casings should be opened.

All steam valves at the maneuvering gear and about the turbines should be closed.

The cocks to the pressure and vacuum gauges on the turbine and condenser should be open.

Determine that there is a supply of circulating water through the oil cooler by turning on the water and then turning it off.

Inspect the lubricating system carefully. It sometimes happens that the oil in the system becomes cold and viscous because of the weather or of the location of the oil tanks. Therefore, before starting the equipment it may be necessary to heat the oil in the tanks sufficiently to allow it to flow freely. The initial temperature of oil should not be generally lower than 90 °F.

Warm up turbine by running slowly, alternately ahead and astern. It is desirable to allow a reasonable time for warming up, say for one hour. If conditions preclude alternate running ahead and astern, it is preferable to omit the warming operation entirely. In this event it is es­ pecially important that the first opening of the throttle valve be sufficient to start the turbine turning at once, to avoid unequal heating of the rotor and consequent warping. If the unit has been shut down for a few hours only, and the turbine is still warm, it is essential to carry out rolling al­ ternately ahead and astern before bringing the unit up to speed.

Start first stage of the air ejectors, bringing vacuum up to normal. Unit is now ready to maneuver or operate.

Exercise VI.

Put 10 questions to the text.

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Text A.

Turbine Construction

The impulse turbine rotor carries the various wheels around which are mounted the blades. The steam decreases in pressure as it passes along the shaft and increases in volume requiring progressively larger blades on the wheels. The astern turbine is mounted on one end of the rotor and is much shorter than the ahead turbine. The turbine rotor is

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