Put questions to the sentences.

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1. Hot gases heat water in the steam-generating tubes.

2. Saturated steam is drawn off from the top of the drum.

3. The steam enters the furnace through a superheater to become superheated.

4. Water droplets can severely damage turbine blades.

5. Cool water at the bottom of the steam drum returns to the water drum through large-bore downcomer tubes.

TEXT C

PARTS OF WATER-TUBE BOILERS

All water-tube boilers have the following essential parts:

1. The steam drum, which provides a reservoir for the water, its distribution to the tubes, a place for separation of steam and water and collection of the steam for delivery.

2. The water drum, which provides the distribution of water, entering it from the downcomers, to the screen and generating tubes.

3. Headers, which perform a similar duty to that of the drums. In general, the drums are large enough to be entered through manholes, and access to the interior of the headers is provided by hands.

4. Generating tubes, which consist of numerous small diameter tubes around which the hot gases circulate and in which the water receives heat to become steam.

5. The furnace, which is used for combustion of fuel and generating hot gases.

6. The superheater, which superheats the steam.

7. The air heater, which is used to heat the air.

8. The economizer, which heats the feed water before the drum.

9. Various appliances to control the operation and to safeguard the boiler and personnel from possible damage. These include safety valves, gauge glasses, blowdown valve, feed water stop and check valves, steam stop valves, salinometer cock, pressure gauges and soot blowers.

Vocabulary

essential, adj основной

distribution, n распределение

delivery, n снабжение; доставка

generating tubes водогрейные (испарительные) трубки котла

similar, adj подобный; сходный

distinction, n различие

manhole, n лаз; горловина; отверстие для доступа

access, n доступ; вход

interior, n внутренняя часть

appliance, n устройствo

safeguard, v предохранять

damage, n повреждение

gauge glass водомерное (водоуказательное) стекло

blowdown valve клапан продувки котла

stop valve стопорный (запорный) кран

check valve обратный (невозвратный) клапан

steam stop valve паровой стопорный (запорный) клапан

salinometer cock солемерный кран

pressure gauge манометр; датчик давления

soot blower сажеобдуватель

E X E R C I S E S

1. Give answers to the questions:

1. Enumerate the parts of a water-tube boiler.

2. What function do the steam and water drums perform?

3. What is the difference between the drums and the headers?

4. Where are generating tubes placed?

5. Speak about the functions of the furnace, the superheater, the air heater and the economizer.

6. Why are various appliances installed in the boiler?

7. What devices are fitted to control the boiler operation?

2. Translate into English:

1. Часть установки, где сгорает топливо, называется топкой.

2. Перегрев пара осуществляется в особых устройствах, называемых пароперегревателями.

3. Воздухоподогреватель служит для подогрева воздуха перед подачей в топку.

4. Экономайзер – это подогреватель питательной воды.

5. Для обеспечения безопасной работы котлов на них оборудуется ряд устройств.

6. К ним относятся предохранительные клапаны, клапан продувки котла, стопорный и обратный клапаны питательной воды, паровые стопорные клапаны, солемерный кран, водомерные стекла, манометры и сажеобдуватели.

UNIT 4

TEXT A

FUEL OIL

The quality of fuel is determined by its elementary composition, calorific (heat) value, viscosity, specific gravity, flash point, ignition temperature, pour point and some other characteristics.

Fuel oil is composed of carbon, hydrogen, oxygen, sulphur and nitrogen, the amount of each depending on the grade of oil. The chief constituents are carbon and hydrogen.

The calorific value of fuel oil fuel is the heat available from that fuel when it is completely burned. There are two values:

• Higher Calorific Value - the water of combustion is entirely condensed and the heat contained in the water vapor is recovered;

• Lower Calorific Value - the products of combustion contains the water vapour and the heat in the water vapour is not recovered.

The practical method of determining the B.t.u. equivalent of oil fuel is by means of a calorimeter. The B.t.u. equivalent varies from 17, 000 to 20, 000 per lb. of oil.

Viscosity is the resistance of oil to flow. As temperature affects the flow, the viscosity is usually determined at 50-75-80°C. depending on fuel. Heavy oils usually have high viscosity and light oils low viscosity at 50°C. Viscosity is obtained by means of a viscosity meter. In Europe to measure viscosity they use either Redwood or Saybolt seconds.

Specific gravity is a relation between the weights of a definite volume of oil and water, both liquids being at the same temperature. The specific gravity is obtained by means of a hydrometer.

Flash point is the temperature at which the fuel is ignited with a small open flame. This flame disappears immediately after ignition.

Ignition temperature is the minimum temperature required to ignite fuel oil vapour in air without a flame being present.

Pour point is the lowest temperature at which the fuel can be easily handled.

Such fuel characteristics as carbon content, ash content, sulphur content, water content, mechanical impurities, total acidity, alkali content, content of vanadium and sodium are also very important.

Vocabulary

quality, n качество

determine, v определять

elementary composition элементарный состав

calorific (heat) value теплотворная способность;

теплотворность; теплота сгорания

available, adj зд. полезный

viscosity, n вязкость

specific gravity удельный вес

flash point температура вспышки

ignition temperature температура воспламенения

pour point температура застывания

carbon, n углерод

hydrogen, n водород

oxygen, n кислород

sulphur, n сера

nitrogen, n азот

constituent, n составная часть

release, n освобождать; выделять

resistance, n сопротивление

flow, n течение; текучесть

viscosity meter вискозиметр

relation, n отношение

weight, n вес

volume, n объем

ignite, v зажигать; воспламенять

disappear, v исчезать

handle, v зд. перекачивать

carbon content содержание углерода

ash content зольность

mechanical impurities механические примеси

total acidity общая кислотность

alkali щелочь

E X E R C I S E S

1.Give English equivalents:

Состоять из; топливо; основные составляющие; величина; высшая теплота сгорания (теплотворность); низшая теплота сгорания (теплотворность); с помощью калориметра; меняться, варьироваться; так как; в зависимости от; вискозиметр; измерять; секунды Редвуда или Сейболта; на 40° выше; самая низкая температура; содержание влаги; ванадий; натрий.

2. Ask questions according to the model:

Model. The physical characteristics of this oil should be determined at once. What should be determined at once?

1. The specific gravity should be obtained by means of a hydrometer.

2. The viscosity of oil should be determined at 50°-80°C.

3. The constituents of oil should be burnt in suspension.

4. The fuel oil and the air should be preheated for complete combustion.

3. Complete the sentences:

1. We determine the quality of fuel by such characteristics as ….

2. Fuel oil is composed of ….

3. The Higher Calorific Value is ….

4. The Lower Calorific Value is ….

5. We determine the B.t.u. equivalent of oil fuel by ….

6. Viscosity is ….

7. A viscosity meter is a device ….

8. Specific gravity is a relation ….

9. The flash point is the temperature ….

10. Pour point is the temperature ….

4. Answer the questions:

1. What characteristics should be known to determine the quality of fuel?

2. What is oil composed of?

4. What does the grade of oil depend on?

5. What is the calorific value?

6. How do we measure the heat value of fuel oil?

7. Is viscosity essential for fuel practicability?

8. Does the temperature affect the flow?

9. What is the specific gravity?

10. What is the difference between the flash point and the ignition temperature?

11. Why is it necessary to know the pour point?

12. What other characteristics should we know?

Translate into English.

1. Качество топлива определяется его элементарным составом, теплотой сгорания, вязкостью, удельным весом, температурой вспышки, температурой воспламенения и застывания, а также некоторыми другими характеристиками.

2. Топливо состоит из следующих химических элементов – углерода, водорода, кислорода, азота и частично серы.

3. Теплота сгорания топлива – это тепловая энергия, высвобождаемая во время сгорания.

4. Различают две теплоты сгорания: высшую и низшую.

5. Вязкость – это сопротивление при течении жидкости.

6. Вязкость определяют с помощью вискозиметров.

7. Тяжелое топливо обычно характеризуется высокой вязкостью.

8. Удельный вес - это соотношение веса определенных равных объемов топлива и воды.

9. При температуре воспламенения топливо начинает гореть.

10. Температура застывания – это самая низкая температура, при которой топливо можно перекачивать.

11. Следует также принимать во внимание следующие характеристики топлива: содержание золы, серы, влаги, содержание механических примесей, общую кислотность и некоторые другие характеристики.

TEXT B

Fuel oils characteristics

Fuel oils have various characteristics which determine their performance and are quoted in specifications.

The specific gravity is the weight of a given volume of fuel compared to the weight of the same volume of water expressed as a ratio, and measured at a fixed temperature.

Viscosity is a resistance to flow. A highly viscous fuel will therefore require heating in order to make it flow. Measurement of viscosity is by Redwood, Saybolt seconds for a given volume of fuel.

The ignition quality of fuel is measured by the time delay between injection and combustion, which should be short for good controlled burning.

The flash point is the temperature at which the fuel is ignited with a small open flame.

The pour point is slightly above the temperature at which the fuel just flows under its own weight. It is the lowest temperature at which the fuel can be easily handled.

Sulphur content is of importance since it is considered a cause of engine wear. A maximum limitis usually included in specifications.

The calorific value of a fuel is the heat energy released during combustion. Two values are used, the more common being the Higher Calorific Value, which is the heat energy resulting from combustion. The Lower Calorific Value is a measure of the heat energy available and does not include the heat energy contained in steam produced during combustion but passing away as exhaust. The measurement is obtained from a calorimeter test where a small fuel quantity is burnt under controlled conditions.

E X E R C I S E S

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