Cooling Tower Materials (1)

Cooling tower structures are constructed using a variety of materials. While package cooling towers are generally constructed with fiberglass, galvanized steel (or stainless steel in special situations), many possibilities exist for field-erected structures. Field-erected towers can be constructed of douglas fir, redwood, fiberglass, steel or concrete (Figure 3.18). Each material has advantages and disadvantages.

Wood - In early days, towers were constructed primarily of redwood because of its natural tendency to inhibit decay. As the redwood resources diminished, douglas fir come into existence. Douglas fir however supports the growth and proliferation of micro-organisms causing rapid diglinification (eating of wood). Various methods of pressure treatment and incising are used to prevent micro-organisms attack to wood, which includes chrome copper arsenate and acid copper chromate treatment. Chromate copper arsenate was initially used as a preservative but because of its arsenic content, acid copper chromate has replaced it. Irrespective of any treatment, the leaching of chemicals is still a concern to the environment and sometimes extensive additional water treatment of blowdown and tower sediment is needed. Some drawbacks of wooden towers are stated below:

• The wooden structure is less durable and its life expectancy is low. Delignification (eating of wood) is controlled by adjusting the pH strictly between 7 and 7.5.

• The drift losses are over 1%.

• The tower has a larger footprint and needs more space when compared to other alternatives.

• Algae formation is a continuous problem in this type of Cooling Tower.

• The wooden structure is less durable.

• The wooden tower usually requires a large concrete tank that involves more cost, time and labor. Since this type of cooling tower is extremely heavy, it has to be installed on ground only.

• The nozzles on the wooden tower consume a significant amount of pressure head, which results in pressure drop.

Figure 3.18 Cooling towers.

Ответьте на вопросы к тексту:

1. What are package cooling towers generally constructed with?

2. What can field-erected towers be constructed of?

3. What advantages does wood have?

4. What are the drawbacks of wooden towers?

5. What does the wooden tower usually require?

6. Where does it have to be installed?

Упражнение 2. Переведите слова и словосочетания на русский язык.

Cooling tower structure; fiberglass (n.); galvanized steel; stainless steel; field-erected structure; douglas fir; redwood (n.); wood (n.); inhibit (v.); decay (v.); diminish (v.); support (v.); proliferation (n.); pressure treatment; prevent (v.); chrome copper arsenate; acid copper chromate; irrespective; chemical (n.); concern (n.); environment (n.); blowdown (n.); sediment (n.); drawback (n.); durable; life expectancy; strictly (adv.); algae formation; extremely (adv.); heavy (adj.); nozzle (n.); significant (adj.); amount (n.); result in (v.).

Below; between; which; still; while; for; however; into.

Упражнение 7. Найдите перевод списка А в списке В.

А

Pressure treatment; fiberglass; various; replace; results in; significant; involve; durable; initially; support; concern; diminish; irrespective; prevent; wooden; source; promote; distribute; footprint; inhibit; decay; erect; consume; adjust; require; primarily; field-erected; advantage; media; provide; properly; throughout; term; dumped into; mean; proliferation; life expectancy; drawback; content; come into existence; collectively; delivery device; approach; interface.

В

Подход; обработка под давлением; преимущество; возводить; оцинкованная сталь; различный; потреблять; перемещать; приводить к; существенный; включать, предполагать; недостаток; вещество; долговечный; первоначально; поддерживать; опасение, беспокойство; называть; снижать; регулировать; средство; быстрое разрастание; безотносительный; содержание; обеспечивать; предотвращать; деревянный; требовать; срок службы; надлежащим образом; главным образом; источник; повышать; распределять; повсюду, по всему; зона обслуживания; выводить в (атмосферу); возникнуть, начать существование; в собирательном значении, обобщенно; подающее устройство; контактная поверхность; препятствовать, подавлять; гниение, разложение; монтируемый на месте.

Упражнение 8. Переведите текст письменно.

HVAC delivery equipment

1. The heating or cooling effect produced at a source and distributed by a central system to spaces throughout a building needs to be properly delivered to each space to promote comfort. 2. In air-based systems, heated or cooled air could theoretically just be dumped into each space. 3. Such an approach, however, does not provide the control over air distribution. 4. In water-based systems, the heated or cooled media (water or steam) cannot just be dumped into a space. 5. Some means of transferring the conditioning effect from the media to the space is required. 6. Devices designed to provide the interface between occupied building spaces and distribution components are collectively termed delivery devices.

Найдите в тексте:

1. Participles I, functions; Participles II, functions; Infinitives, functions.

2. Participles II, functions; modal verb; passive voice.

3. Subject; predicate.

4. Participles II, functions; passive voice.

5. Subject; predicate; Gerund, function.

6. Subject; predicate; Participles II, functions; Infinitive, function.