Answer the questions. Supply prepositions

Supply prepositions.

E x e r c I s e s

1. Fuel oil characteristics should be taken … consideration when burning fuel.

2. A furnace fuel oil system consists … a fuel tank from which fuel is drawn … a strainer … a pump.

3. Fuel is ignited … the furnace.

4. Fuel is delivered … pressure … the burners.

5. Suction system is used … transferring fuel … remote tanks.

6. The fuel passes … the holes and then through the orifice … a conical spray … the furnace.

1. What does a furnace provide?

2. What fuel oil characteristics should be taken into consideration when burning fuel?

3. Where is fuel drawn from?

4. Where does fuel mix with air?

5. What does the complete furnace fuel oil system consist of?

6. What is oil fuel filling system used for?

7. What system is used to deliver fuel under pressure to the burners?

8. What is the principle of burner operation?

UNIT 5

TEXT A

FEED WATER

Feed water is the water supplied to a boiler to generate steam or hot water. It is delivered to the boiler by the feed pump. As the water is evaporated, the impurities in it remain in the boiler in the form of the salt deposits.

Water containing impurities may lead to the following problems in boilers: scale, foaming, priming and corrosion.

The chief salts forming scale are those of calcium and magnesium. Magnesium sulphate is a salt commonly found in boiler water and it forms a soft, sludgy mass, not very harmful, which can be removed by blowing down. Calcium sulphate produces a hard brittle scale.

Alkalis or phosphate are sometimes put into marine boilers to prevent scale.

Foaming may be the result of dirty water, certain types of organic matter, oils in solution, the presence of excess alkalinity. Oil is very injurious to a boiler: it adheres to the tube surfaces and causes overheating and rupture of tubes.

Priming may be due to improper construction of boiler or extremely high ratings. The most common measure to prevent foaming and priming is to maintain the water at the lowest level. Avoiding high water levels, excessive boiler loads, and sudden load changes also helps. If foaming and priming occur, the blow off is opened several times, and fresh water is added.

The main cause of boiler corrosion results from the dissolved gases, oxygen and carbon dioxide, found in feed water. They will react with the metals in the boiler system and lead to boiler corrosion. In order to protect the boiler from these contaminants, they should be controlled or removed, usually by use of a deaerator.

Acids due to oils in solution may be neutralized by the addition of sodium carbonate.

For efficient boiler operation a chemical analysis of the feed water must be run at least once a day.

Vocabulary

feed water питательная вода

evaporate, v испаряться

impurity, n примесь; загрязнение

remain, v оставаться

salt deposits отложения солей

scale накипь

foaming вспенивание

priming вскипание

softsludge мягкий шлак; шлам

brittle scale хрупкая, ломкая накипь

harmful, adj вредный

blowing down нижнее продувание

alkali, n щелочь

organic matter органическое вещество

solution, n раствор

excessal kalinity избыточная щелочность

injurious, adj вредный

adhere, v прилипать; приставать

rupture, n разрыв

rating, n мощность

load, n нагрузка

blow off верхнее продувание

freshwater свежая; пресная вода

dissolve, v растворять

contaminant, n загрязняющее вещество; примесь

deaerator, n деаэратор

acid, n кислота

sodium chloride хлорид натрия

E X E R C I S E S

1. Give English equivalents:

Питательная вода; подавать; питательный насос; содержать примеси; приводить к проблемам; коррозия; образовывать; кальций; магний; сульфат магния; мягкая масса; предотвращать образование накипи; наличие; вызывать перегрев; мера; избегать; чрезмерные нагрузки; углекислый газ; карбонат натрия, проводить химический анализ.

2.Change these sentences using the modal verbs may, can, must:

Model. Priming is due to high ratings. Priming may be due to high ratings.

1. Foaming is due to the presence of dirty water in the boiler.

2. Oil in the feed water is very injurious to the boiler.

3. Priming is also due to a poorly designed steam drum.

4. Acids are neutralized by the addition of sodium carbonate.

5. A little of the chemicals is added at a time.

3. Change these sentences into the passive:

Model. Chemicals remove scale from the boiler. Scale from the boiler is removed by chemicals.

1. The addition of alkalis prevents scale formation.

2. The presence of oils in solution causes foaming.

3. Some of the salts produce a soft sludge.

4. The chlorides of sodium and magnesium and the sulphate of iron cause corrosion.

5. We may neutralize acids by the addition of sodium carbonate.

4. Supply prepositions:

1. Feed water is the water supplied … a boiler … the feed pump.

2. The impurities … the boiler remain … the form of the salt deposits.

3. Alkalis or phosphate are put … marine boilers to prevent scale.

4. Oil is very injurious … a boiler as it adheres … the tube surfaces.

5. Priming may be due … improper construction of boiler.

6. To prevent priming it is necessary to maintain the water … the lowest level.

7. Corrosion results … the dissolved gases found … feed water.

8. Acids may be neutralized … the addition of sodium carbonate.

5. Answer the questions:

1. What is feed water?

2. By what device is the feed water supplied to the boiler?

3. What substances remain in the boiler as the water is evaporated?

4. What problems may water containing impurities lead to?

5. How can a soft sludge be removed?

6. What salt produces a hard scale?

7. What may foaming be the result of?

8. What may priming be due to?

9. What gases cause corrosion?

10. How often must a chemical analysis of the feed water be run?

6. Translate into English:

1. Питательная вода подается в котел насосом.

2. Примеси воды остаются в котле в виде отложений.

3. Мягкий шлак может быть удален из котла продуванием.

4. Некоторые соли образуют твердую накипь.

5. Для предотвращения накипи в котле используются щелочи и фосфаты.

6. Содержание в воде органических веществ может привести к вспениванию.

7. В случае вскипания применяется продувание и добавляется свежая вода.

8. Растворенные в питательной воде кислород и углекислота вызывают

коррозию стенок котлов.

9. Химический анализ питательной воды должен производиться на судне не

реже одного раза в день.

TEXT B

Purity of boiler feed water

Modern boilers require very pure feed water. The water required for boiler feed purposes, i.e. for steam generation should be of very high quality and thus requires a lot of treatment. Untreated water, containing impurities may lead to the following problems in boilers.

Most pure water will contain some dissolved salts. These salts then adhere to the heating surfaces as a scale and reduce heat transfer, which can result in local overheating and failure of the tubes. Other salts remain in solution and may produce acids which will attack the metal of the boiler. An excess of alkaline salts in a boiler will cause cracking of the metal which may lead to serious failure.

The presence of dissolved oxygen and carbon dioxide in boiler feed water can cause considerable corrosion of the boiler and feed systems. When boiler water is contaminated by suspended matter, an excess of salts or oil, foaming may occur. This is foam which collects on the water surface in the boiler drum. Foaming leads to priming which is the carry-over of water with the steam leaving the boiler drum. Any water present in the steam entering a turbine will do considerable damage.

Various amounts of different metal salts can be found in water. These include the chlorides, sulphates and carbonates of calcium, magnesium. These dissolved salts in water make up the 'hardness' of the water. Calcium and magnesium salts are the main causes of hardness.

E X E R C I S E S

1. Find the corresponding Russian translation. Memorize the phrases.

1. to require pure feed water	a. вести к проблемам
2. to contain impurities	b. прилипать к поверхности
3. to lead to the problems	c. приводить к местному перегреву
4. to adhere to the surface	d. содержать примеси
5. to result in local overheating	e. требовать чистой воды
6. to cause cracking of the metal	f. собираться на поверхности воды
7. to collect on the water surface	g. вызывать растрескивание металла
8. to cause corrosion	h. составлять жесткость воды
9. to enter a turbine	i. вызывать коррозию
10. to make up the ‘hardness’ of water	j. поступать в турбину

Дата добавления: 2015-03-29