Answer the questions. Choose the proper verb form

Choose the proper verb form.

1. A steam power plant /convert; converts; is converted/ the energy of fuel into mechanical energy.

2. The heat generated in the furnace /transmit; is transmitted; transmits/ to the boiler.

3. Temperature and pressure of the steam /drops; drop; is drop/ in passing through the turbine.

4. The steam from the turbine /pass; passes; passing/ to the condenser.

5. The mechanical energy /is expressed; express; are expressed/ in horsepower.

1. What is a steam power plant used for?

2. What units does s steam power plant consist of?

3. How is the steam in the steam power plant formed?

4. Where is the energy of steam converted into kinetic energy?

5. What energy is the kinetic energy converted into at the turbine moving blades?

6. Where is the steam from the turbine changed into water?

7. What ships is the steam power plant installed in?

UNIT 2

TEXT A

CLASSIFICATION OF MARINE BOILERS

Marine boilers are classified in different ways:

1. By the purpose they are designed for marine boilers are classified as main and auxiliary, or donkey boilers.

The main steam boilers generate steam for the main engines, driving the propeller and for auxiliaries. The auxiliary boilers generate steam only for the auxiliaries, heating of oil and fuel tanks and other ship’s needs.

2. By their structure boilers are classified as the fire-tube boilers and the water-tube boilers.

The fire-tube boiler, or a Scotch boiler, consists of a cylindrical steel shell, which contains a furnace at the bottom. Two or more furnaces may be fitted, depending on the size of the boiler. The furnace is connected to a combustion chamber, situated in the middle part of the boiler. The furnace, the combustion chamber and the tubes are all surrounded by water.

Water-tube boilers have replaced fire-tube boilers. In the water-tube boiler feed water passes through the tubes surrounded by hot gases. It is used for high pressure, high temperature, and high capacity steam applications, e.g. providing steam for the main propulsion turbine or cargo pump turbines.

3. By the principle of water and steam water mixture motion the boilers are classified as natural and forced circulation boilers.

The process of natural circulation occurs due to density difference of water and steam water mixture.

If the working fluid is forced through the boiler by an external pump, the circulation is called the forced one.

4.By the way they are supplied with air boilers are classified as natural draft, forced draft and supercharged boilers.

In natural draft boilers fuel is burnt under the pressure equal to the atmospheric pressure; forced draft is produced by placing a fan in the uptake, and exhausting through the furnaces; in supercharged boilers the pressure is much higher than the atmospheric pressure.

NOTES:

depending on – в зависимости от

e.g. = for example – например

Vocabulary

auxiliary (donkey) boiler вспомогательный котел

propeller, n гребной винт; движитель

shell, n кожух

natural circulation boiler котел с естественной циркуляцией

forced circulation boiler котел с принудительной циркуляцией

density difference разность плотностей

rate, n скорость; степень

natural draft boiler котел на естественной тяге

forced draft boiler котел с вентиляционным дутьем

supercharged boiler котел с наддувом

fan, n вентилятор

uptake, n дымоход

E X E R C I S E S

1. Give English equivalents:

По назначению; классифицировать; главный двигатель; обогрев топливных и масляных цистерн; судовые нужды; цилиндрической формы; внизу; средняя часть котла; заменять; движение воды и пароводяной смеси; происходить; по способу подачи воздуха; под давлением; равный; атмосферное давление.

2. Complete the sentences:

1. By the purpose they are designed for marine boilers can be classified as ….

2. By their structure boilers are classified as ….

3. In a Scotch boiler the furnace ….

4. The number of furnaces in the fire-tube boilers depends on ….

5. The water-tube boiler is used for ….

6. The process of natural circulation occurs due to ….

7. The circulation in the boiler is called the forced one because ….

8. By the way they are supplied with air boilers are classified as ….

3. Give English equivalents to the words in brackets:

1. (По назначению котлы делятся на) main and auxiliary boilers.

2. (По конструктивному исполнению) boilers may be classified as the fire-tube and the water-tube boilers.

3. (По принципу движения воды и пароводяной смеси) all boilers can be classified as natural and forced circulation boilers.

4. (По способу подачи воздуха на горение топлива, т.е. подавлению в топке) boilers are classified as natural draft, forced draft and supercharged boilers.

4.Self-assessment questions:

1. How are marine boilers classified by the purpose they are designed for?

2. Can you compare main and auxiliary boilers?

3. How are boilers classified by their structure?

4. Explain the difference between the fire-tube and the water-tube boilers.

5. What can you say about natural and forced circulation boilers?

6. What do you know about natural draft, forced draft and supercharged boilers?

5. Translate into English:

1. Главные котлы обеспечивают паром главный двигатель, приводящий в движение гребной винт.

2. Вспомогательный котел выдает пар только для вспомогательных механизмов.

3. По конструктивному исполнению котлы могут быть разделены на огнетрубные и водотрубные.

4. В огнетрубном котле топка со всех сторон окружена водой.

5. В водотрубных котлах питательная вода движется внутри труб, которые окружены горячими газами.

6. По принципу движения воды и пароводяной смеси все котлы можно разделить на агрегаты с естественной циркуляцией и с принудительным током воды.

7. Процесс естественной циркуляции происходит за счет разности плотностей воды и пароводяной смеси.

8. По способу подачи воздуха на горение топлива котлы можно разделить на обычные и с наддувом.

TEXT B

BOILER CLASSIFICATION

Boilers vary considerably in detail and design.

In the following paragraphs, the classification of marine boilers according to intended service, location of fire and water spaces, type of circulation are considered.

Intended service

By this method of classification, marine boilers are divided into two classes, propulsion boilers and auxiliary boilers. Propulsion boilers are used to provide steam for ships' propulsion and for vital auxiliaries’ services. Auxiliary boilers are installed in diesel-driven ships and in many steam-driven ships. They supply the steam and hot water for galley, heating etc. and for other auxiliary requirements in port.

Location of fire and water spaces

One of the basic classifications of boilers is according to the location of the fire and water spaces. By this method of classification, boilers are divided into two classes, fire-tube boilers and water-tube boilers.

In the fire-tube boilers, the gases of combustion flow through the tubes and heat the water that surrounds the tubes. In water-tube boilers, the water flows through the tubes and is heated by the gases of combustion that fill the furnace and heat the outside metal surfaces of the tubes.

All propulsion boilers are of the water-tube type. Auxiliary boilers may be either fire-tube or water-tube boilers.

Type of circulation

Water-tube boilers are further classified according to the method of water circulation. Water-tube boilers may be classified as natural circulation boilers or forced circulation boilers.

In natural circulation boilers, the circulation of water depends on the difference between the density of an ascending mixture of hot water and steam and a descending body of relatively cool and steam-free water.

Forced circulation boilers are quite different in design from the boilers that use natural circulation. Forced circulation boilers depend upon pumps, rather than upon natural differences in density, for the circulation of water within the boiler.

E X E R C I S E S

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