Cooling Water Treatment
The makeup water used in cooling systems contains dissolved minerals, suspended solids, debris, bacteria and other impurities. Among other dissolved solids, water contains calcium and magnesium salts; commonly referred to as "hardness." These salts have only limited solubility; that is, only a certain amount will be soluble in a given volume of water. Water is capable of dissolving a wide variety of solids and gases in infinite combinations and amounts. As the water continues to circulate throughout the system, the contaminants begin to concentrate.
There is another problem with cooling towers; this occurs when air is brought into intimate contact with the cooling water as it passes over the cooling tower. Because of pollution, the air contains a wide variety of impurities; both solids and gases. As it passes through the water in a cooling tower, the air is effectively "scrubbed" and the impurities are transferred to the water. Thus, the dirt picked up from the air along with the precipitated hardness and suspended solids make up the major cooling tower water contaminants.
Another problem results when the moist surfaces of the tower are exposed to sunlight. This promotes the growth of algae, bacteria and fungal slime. Large masses of slime or algae growth can accumulate rapidly, causing clogging, reduced flow, and reduced heat transfer. This "fouling" must be prevented.
The operating efficiency of a cooling tower system is adversely affected by scaling, corrosion and organic fouling. Effective cooling water operation and treatment can prevent such an occurrence.
A major objective of a cooling tower treatment program is to keep the water quality sufficient to prevent scaling, corrosion and biological fouling that can affect normal productive operations. The problem of water impurities is controlled in two ways:
1) By introduction of chemicals which prevent the dissolved solids from precipitating as scale, and which prevent corrosion.
2) By bleed-off which limits the solids concentration at a level which can be successfully handled by chemical treatment.
Ответьте на вопросы к тексту:
What does the makeup water used in cooling systems contain?
Why do the contaminants begin to concentrate?
What does the air contain?
How are the impurities transferred to the water?
What makes up the major cooling tower water contaminants?
What may the moist surfaces of the tower be exposed to?
How can large masses of slime or algae growth reduce heat transfer?
What is the operating efficiency of a cooling tower system affected by?
What can prevent the problems occurring in cooling water operation?
What is a major objective of a cooling tower treatment program?
How is the problem of water impurities controlled?
Упражнение 2. Переведите слова и словосочетания на русский язык.
Makeup water; contain (v.); dissolved mineral; suspended solid; debris (n); bacteria (n); impurity (n); calcium (n); magnesium salt; refer to (v.); limited solubility; contaminant (n); occur (v.); occurrence (n); intimate contact (v.); pollution; expose to (v.); prevent (v.); algae (n); fungal (n); operating efficiency; adversely (adv.); affect (v.); scaling (n); corrosion (n); organic fouling; objective (n); water quality; sufficient; biological fouling; water impurity; way (n); limit (v.); level (n); successfully (adv.); handle (v); chemical treatment.
Among; as; that is; with; such; thus; from; which; another; along with.
Упражнение 3.Переведите слова и словосочетания на английский язык.
Загрязнитель; подвергать; эффективность эксплуатации; неблагоприятно, отрицательно; примеси воды; загрязнения, содержащиеся в воде; химическая очистка; химическая обработка; подпиточная вода; свежая вода; дебрис, обломочный материал, продукты разложения; жесткость; ограниченная растворимость; бесконечное сочетание; загрязняющая примесь; непосредственный контакт; очищать; осажденные соли жесткости; взвесь, взвешенные твердые вещества; грибковое обрастание, грибковая слизь; засорение, закупорка; образование накипи, окалины; накипь; регулировать, управлять, обращаться; загрязнение, примесь.
Упражнение 4. Образуйте прилагательные и существительные с указанными суффиксами и назовите значения производных слов:
-able
to consider; to observe; to avail; to move; to suit; to accept; to vary; value; comfort; rely;
-ity
possible; special; probable; reliable; rapid; able; capable; dense; flexible; durable; stable; impure.
Упражнение 5. Сгруппируйте синонимы по образцу:
to begin- to start.
To accumulate; to advance; to affect; to alter; to change; to contain; to contaminate; to collect; to complete; to compose; to comprise; to decrease; to decompose; to differ; to dissolve; to expose; to finish; to get; to handle; to happen; to hold; to influence; to keep; to let; to limit; to make; to make up; to observe; to obtain; to occur; to operate; to pick up; to pollute; to remain; to reduce; to restrict; to promote; to transfer; to transport; to stay; to store; to subject; to regulate; to vary; to watch; to work.
Упражнение 5. Найдите в тексте предложения с неличными формами глагола, определите функцию и переведите на русский язык.