Урок 2.5

Упражнение № 1.Прочитайте слова.

[»] nitrogen, large, oxygen, strategy, major;

[¸:] call, small, all, form.

Упражнение № 2. Сопоставьте слов с переводом и соответствующей ему транскрипцией.

nitrogen	['¸ÐÉI»¶Í]	имеющийся в наличии
combustion	[q 'ÈÂIqÎÄÎ]	азот
oxygen	[q'ÐE:]	кислород
available	[ÐqÅ'ĵsÀ(q)Í]	происходить
occur	['ÍÕIËÏq»¶Í]	горение

Текст А

NOx emission

Smaller systems, which are running on gases or liquids, are allowed to have larger emissions than larger systems. As a result smaller systems are not required to treat their flue gases afterwards. Because of the strict laws the amount of exhausted emissions by the large industrial systems has decreased very much. The emission of NOx is one of the major sources for acidification and smog. NOx formation in a boiler can occur in two ways. NOx is mainly formed in the boiler during the combustion process. During the combustion process oxidation of nitrogen that is available in the supplied air is taking place. The NOx formed in this way is called thermal NOx. The rate of the oxidation depends on the temperature and of course the amount of oxygen available. It is also possible for NOx to be formed in a different way. The NOx formed in this way is called fuel NOx. In this case NOx is formed because of the nitrogen that is organically bonded in the fuel. Coal contains relatively large amounts of nitrogen. As a result around 80 % of the NOx formed in a coal boiler will be fuel NOx. The amount of fuel NOx formed does not depend on the temperature, but on the amount of oxygen available. There are different strategies to reduce the amount of NOx. Lowering the temperature of the combustion can reduce the forming of thermal NOx. The lower temperature makes nitrogen and oxygen less reactive with each other. Especially if peek temperatures occur during combustion NOx will be formed. Peek temperatures may occur when fuel and air are not properly mixed.

Notes:

NOx (Nitrogen oxide) оксид азота.

Ответьте на вопросы к тексту:

1. Why has the amount of exhausted emissions by the large industrial systems decreased?

2. What is one of the major sources for acidification and smog?

3. How can NOx formation occur in a boiler?

4. What does the rate of the oxidation depend on?

5. How can the amount of NOx be reduced?

6. What makes nitrogen and oxygen less reactive with each other?

7. When may peek temperatures occur?

Упражнение № 3. Переведите слова и словосочетания на русский язык.

Treat (v.); because of (prep.); strict law; exhausted emission; decrease (v.); major source; acidification (n.); formation (n.); occur (v.); way (n.); mainly (adv.); combustion process; oxidation (n.); nitrogen (n.); available (adj); supplied air; depend on (v.); organically (adv.); bond (v.); contain (v.); relatively (adv.); reactive (adv.); each other; especially (adv.); peek temperature; form (v.); properly (adv.); mix (v.).

Упражнение № 4. Переведите слова и словосочетания на английский язык.

Очищать; образование; выброс вещества (в окружающую среду); уменьшать; подаваемый воздух; реактивный; происходить; главным образом; оксид азота; процесс сгорания; оксидирование; впоследствии; подаваемый воздух; возникать; особенно; относительно; источник.

Упражнение № 5. Сопоставьте слово (А) с его определением (В).

А

1. air;

2. law;

3. reduction;

4. to mix;

5. to contain;

В

1. system of rules that people in a particular country or area must obey (соблюдать);

2. to combine in order to become a single substance, and they cannot be easily separated;

3. to have or hold (someone or something) within;

4. the mixture of gases around the Earth, that we breathe;

5. a decrease in the size, price, or amount of something, or the act of decreasing something.

Упражнение № 6. Какой из перечисленных переводов является ошибочным.

A	В	А	В
afterwards	впоследствии	reduce	сокращать
emission	выброс	properly	надлежащим образом
relatively	относительно	mainly	главным образом
because of	из-за	formation	образовать
thermal	термальный	mix	смешивать

Упражнение № 7. Переведите предложения с объектным инфинитивным оборотом.

1. The governments allowed smaller systems, which are running on gases or liquids, to have larger emissions than larger systems.

2. Fouling considers the deposits to be formed as a result of chemical reactions within the fluid.

3. They expected water tube boiler to work in high steam pressure and capacities.

4. The government expects programs to reduce the amount of emission.

5. The designers expect the required heat rate to be calculated due to the heat balance equation.

6. They know the heat transferring area to give a relation between the diameter of the pipe and the length of the heat exchanger.

7. The government forced the designers to use lower fluid velocities to maintain the pressure drop limitations.

8. They consider the efficiency of a shell-and-tube heat exchanger to be an important parameter in heat exchanger design.

9. The research and development departments of a company consider lots of costs to be prevented.

Упражнение № 8. Переведите следующие предложения, определите форму и функцию инфинитива.

1. The modern manufacturing methods are used to fabricate a particular material into required shapes.

2. Welding problems have to be overcome.

3. An industrial boiler can be found in a large range of applications.

4. The low-water security system has to be tested.

5. It is also possible for NOx to be formed in a different way.

6. It is necessary to make a restriction.

7. The device forces air to blow vertically against the plates in order to cool the fluid inside.

8. Gas-to-gas exchangers are usually much larger and heavier if it is necessary to transfer the same amount of heat.

9. Frequently it is necessary to get an idea of how big a heat exchanger will be for a certain performance.

Упражнение № 9. Задайте пять общих вопросов к тексту А.

Текст B

NOx reduction

By controlling the mixing process in the right way the combustion can be made more uniform. It can prevent the appearance of peek temperatures and limit the production of NOx. The forming of NOx will also be decreased if the oxygen concentration is limited. Thermal NOx is formed because of the amount of nitrogen and other pollution in coal. These amounts depend on the place where the coal is found. Although it is not a real solution, emissions of NOx can be reduced if a coal from a different mine is used. The amount of fuel NOx can also be reduced if the amount of oxygen available during the combustion process is limited. Another way to reduce NOx production is by flue gas recirculation. Using this technology means that 20-30 % of the flue gases with a temperature of 350-400 C is recirculated and mixed with the combustion air. The resulting dilution in the flame decreases the temperature and the availability of oxygen. As a result the formation of thermal NOx is reduced. For a coal boiler the amount of NOx reduction is limited if only flue gas recirculation is used (< 20 %). This is due to the low ratio of thermal NOx in the total NOx emissions. If the amount of recirculation gases is increased too much the flame can become instable. Also the increased flow of gases through the boiler may affect the performances.

Ответьте на вопросы к тексту:

1. How can the combustion be made more uniform?

2. What will be decreased if the oxygen concentration is limited?

3. Why is thermal NOx formed?

4. When can emissions of NOx be reduced?

5. What does the dilution in the flame decrease?

6. When is the amount of NOx reduction for a coal boiler limited?

7. In what case can the flame become instable?

Упражнение № 1. Переведите слова и словосочетания на русский язык.

Mixing process; uniform (adj.); prevent (v.); appearance (n.); limit (n.); decrease (v.); oxygen (n.); concentration (n.); thermal (adj.); nitrogen (n.); pollution (n.); coal (n.); depend on (v.); although (conj.); solution (n.); reduce (v.); mine (n.); use (v.); fuel (n.); available (adj.); availability (n.); combustion process; application (n.); technique (n.); level (n.); recirculation (n.); recirculate (v.); mean (v.); mix (v.); dilution (n.); due to (prep.); ratio (n.); instable (adj.); through (prep.); affect (v.); performance (n.).

Упражнение № 2. Переведите слова и словосочетания на английский язык.

Разжижение; наличие; характеристик; циркуляция по замкнутой траектории; благодаря; из-за; равномерный; концентрация; сокращать; увеличивать; становиться; влиять; хотя; другой;

Упражнение № 3. . Найдите перевод слов списка А в списке В.

А	В	А	В
increase	благодаря	ratio	азот
reduce	кислород	availability	нестабильный
use	использовать	instable	соотношение
due to	увеличивать	oxygen	наличие
though	сокращать	nitrogen	хотя
solution	равномерный	dilution	решение
through	разжижение	uniform	через

Упражнение № 4. Найдите в тексте инфинитивы. Определите их функции.

Упражнение № 5. Найдите в тесте условные предложения. Переведите их на русский язык.