Учебное пособие 1908

Упражнение 8. Переведите текст, пользуясь словарем.

Entrained-flow gasifiers operate with feed and blast in cocurrent flow. The residence time in these processes is short (a few seconds). The feed is ground to a size of 100 µm or less to promote mass transfer and allow transport in the gas. Given the short residence time, high temperatures are required to ensure a good conversion, and therefore all entrained-flow gasifiers operate

31

in the slagging range. The high temperature operation creates a high oxygen demand for this type of process. Entrained-flow gasifiers do not have any specific technical limitations on the type of coal used, although coals with a high moisture or ash content will drive the oxygen consumption to levels where alternative processes may have an economic advantage.

There are one or two processes that do not fit into any of these three main categories. This includes in situ gasification of coal in the underground seam as well as molten bath processes.

One important point to note is the significance of the slagging behavior of the ash. At temperatures above the ash softening point, the ash becomes sticky and will agglomerate, causing blockage of beds or fouling of heat-exchange equipment. Once above the slagging temperature, at which point the ash has a fully liquid behaviour with a low viscosity, it is possible again to remove it from the system reliably. Thus, for all processes, there is a feedstock-specific "no-go" temperature range between the softening and slagging temperatures of the ash.

Упражнение 9. Переведите следующие предложения на английский язык и запишите их.

1.Газогенератор с подвижным слоем характеризуется пластом, в котором уголь медленно опускается под действием силы тяжести в процессе образования газа.

2.Температура на выходе синтезируемого газа обычно низкая, даже если в середине пласта достигаются высокие температуры ошлакования.

3.Процессы в подвижном слое происходят только в крупнокусковом угле.

4.Избыточное количество угольной мелочи, особенно, если уголь обладает свойством сильной спекаемости, может блокировать прохождение поднимающегося вверх синтетического газа.

5.Газогенератор с псевдоожиженным слоем обеспечивает очень хорошее смешивание сырья и окислителя, что

32

ускоряет тепло и массообмен.

6. Работа газогенераторов с псевдоожиженным слоем обычно ограничена температурами ниже точки размягчения золы, поскольку ошлакование золы будет нарушать псевдоожижение пласта.

7.Сортировка частиц в сырье важна, поскольку слишком мелкодисперсный материал стремится к вовлечению

всинтетический газ и покидает верхний погон пласта.

8.Низкая рабочая температура процессов с псевдоожиженным слоем означает, что они более пригодны для превращения в газ химически активного сырья, такого как низкокачественный уголь и биомасса.

Упражнение 10. Составьте аннотацию текста «Gasification Processes», используя в качестве плана ответы на вопросы упражнения 5.

Упражнение 11. Выпишите из правой колонки русские слова и словосочетания, соответствующие английским из левой колонки.

33

UNIT 4

Упражнение 1. Прочтите слова и словосочетания и постарайтесь запомнить их русские эквиваленты.

34

Упражнение 2. Переведите слова на русский язык, обращая внимание на суффиксы.

Historical – historically, atmosphere – atmospheric, slow – slowly, to react – reactor, present – presence, local – locally, industry – industrial, particular – particularly, to locate – location, to differ – different, to purify – purification, to separate – separation.

Упражнение 3. Прочтите и переведите интернациональные слова:

Role, reactor, product, to transport, distance, industrial, energy, form, temperature, to stop, synthesis, optimum, endothermic, reaction, cycle, chemical.

35

Упражнение 4. Переведите предложения на русский язык, используя терминологию упражнения 1.

1.Moving-bed processes аrе the oldest processes, and two in particular, the producer gas process and the water gas process, played аn important role in the early production of synthesis gas from coal and coke.

2.When using 1ow-rank feedstocks such as wood, the heating value of the gas саn bе as low as 3500 kJ/m3.

3.Gas producers continue to bе built in small numbers today where gas is required locally for firing industrial furnaces, particularly in locations where coal is the оnlу available energy form.

4.The water gas process is а discontinuous process in which steam reacts with red-hot coke to form hydrogen and carbon monoxide.

5.The reason for the two different directions of steam flow was to make optimum use of the heat in the bed, which is required do drive the endothermic water gas reaction.

6.Before the advent of large-scale air separation plants, the water gas process was the only means for making high-grade synthesis gas for chemical purposes.

Прочтите и переведите текст, а затем выполните следующие за ним упражнения.

MOVING-BED PROCESSES

Historically, moving-bed processes аrе the oldest processes, and two in particular, the producer gas process and the water gas process, played аn important role in the early production of synthesis gas from coal and coke. The preferred feedstocks were in general coke or anthracite, as otherwise the gas needs extensive cleaning to remove tars from the gas. Both processes operate at atmospheric pressure.

In the producer gas process, humidified air is blown upward

36

through а deep bed of coal or coke. The coal is fed from the top and moves slowly downwards as it is consumed. Ash is drawn off at the bottom of the reactor from а rotating grate. The air reacts with the соаl, thereby producing а gas with а lower heating value of 6500 kJ/m3. The рresence of about 50% nitrogen in the product gas is the main cause for this low value. The advantage of the process was that it was continuous. The main drawback is that because of its low heating value, producer gas cannot be transported over 1ong distances. When using low-rank feedstocks such as wood, the heating value of the gas саn bе as low as 3500 kJ/m3. Gas producers continue to bе built in small numbers today where gas is required locally for firing industrial furnaces, particularly in locations where coal is the оnlу available energy form.

The water gas process is а discontinuous process in which steam reacts with red-hot coke to form hydrogen and carbon monoxide. First, the coal or coke bed is heated bу blowing air upward through the bed to temperatures of about 1300ºC. Then the air flow is stopped and steam is passed through the соаl or coke bed, first upward and then downward, thereby producing synthesis gas. The reason for the two different directions of steam flow was to make optimum use of the heat in the bed, which is required do drive the endothermic water gas reaction. When the temperature has dropped to about 900ºС, the steam “run” is stopped and the cycle is repeated. After purification the syngas саn bе used for the synthesis of ammonia or methanol. Before the advent of large-scale air separation plants, the water gas process was the only means for making high-grade synthesis gas for chemical purposes. In order to obtain а continuous gas flow, at least three water gas reactors аrе required.

Упражнение 5. Найдите в тексте данные ниже слова и словосочетания и напишите их русские эквиваленты.

Extensive cleaning, to remove tars, atmospheric pressure, upward, downward, а deep bed of coal, to move slowly

37

downwards, bottom of the reactor, product gas, low value, continuous, low heating value, producer gas, low-rank feedstocks, industrial furnaces, discontinuous, red-hot coke, steam flow, largescale air separation plants, chemical purposes.

Упражнение 6. Найдите в тексте ответы на следующие вопросы:

1.What processes played an important role in the production of synthesis gas from coal and coke?

2.What condition do both processes operate under?

3.What occurs in the producer gas process?

4.What is the main cause for the low heating value?

5.What is the advantage of the producer gas process?

6.What is the main drawback of the process?

7.Where are gas producers built?

8.What kind of process is the water gas process?

9.How does the water gas process occur?

10.What was the reason for the two different directions of steam flow?

11.When is the cycle repeated?

12.What can the syngas be used for?

Упражнение 7. Заполните пропуски предлогами и переведите предложения на русский язык.

1. ... the producer gas process, humidified air is blown upward ... а deep bed ... coal or coke.

2. Ash is drawn off ... the bottom ... the reactor ... а rotating

grate.

3.The presence ... about 50% nitrogen ... the product gas is the main cause ... this low value.

4.The water gas process is а discontinuous process ... which steam reacts ... red-hot coke to form hydrogen and carbon monoxide.

5.First, the coal or coke bed is heated … blowing air upward

38

... the bed to temperatures ... about 1300ºC.

6. ... purification the syngas саn bе used ... the synthesis ...

ammonia or methanol.

7. ... the advent ... large-scale air separation plants, the water gas process was the only means ... making high-grade synthesis gas

... chemical purposes.

Упражнение 8. Выпишите из правой колонки русские слова и словосочетания, соответствующие английским из левой колонки.

39

Упражнение 9. Подберите из правой колонки соответствующие окончания предложений из левой колонки.

40