Учебные материалы для студентов заочной формы обучения по специальности:
1–36 20 04 «Вакуумная и компрессорная техника» (летняя сессия)
Pre-reading Exercises
Read the following words, guess their meanings.
ideal situation medium product
material design control protect
temperature system potential method
atmospheric dynamic period problem
2. Match English and Russian equivalents.
1. drying a) опасные материалы
2. moisture b) загрязнение воздуха
3. pressure c) сушильное оборудование
4. boiling point d) потеря
5. contaminant e) привести к
6. high temperature f) сталкиваться с проблемой
7. loss g) влага
8. result in h) сушка
9. air pollution i) высокая температура
10. hazardous materials g) давление
11. face the problem h) точка кипения
12. drying equipment i) загрязняющее вещество
3. Read the text carefully and translate it into Russian.
TEXT А. Vacuum Drying Equipment & Benefits
Vacuum drying is ideal for materials that would be damaged or changed if exposed to high temperatures. The vacuum removes moisture while preventing the oxidation or explosions that can occur when certain materials combine with air. Vacuum drying is also ideal in situations where a solvent must be recovered or where materials must be dried to very low levels of moisture.
Vacuum drying saves time. Unlike atmospheric drying, drying under reduced pressure lowers the boiling point and provides a greater temperature difference between the heating medium and product. This results in faster drying and more efficient heat recovery.
Vacuum drying saves money. Drying at lower temperatures reduces energy consumption. The dryers' closed-system design allows costly solvents to be recovered, eliminates expenses for additional air pollution control or exhaust systems, and minimizes product loss caused by atmospheric contaminants, dusting, oxidation, discolouration, and chemical change.
Vacuum drying protects workers. Since drying occurs in a closed system, hazardous materials and fumes are not released into the air. The potential for explosions is reduced because of the lower temperatures and the lack of dust and air in the dryer.
T
his
vacuum shelf dryer is designed with two independent chambers for
drying two types of materials at the same time.
Drying equipment. At present there appear new companies dealing with food and wood processing. These companies face the problem of fast and high quality drying of food and wood. For solving the problem different methods (techniques) and chamber types, such as convective, microwave, air-dynamic, dielectric and vacuum drying chambers are used.
Convective chambers have a number of drawbacks - long-drying time, high power consumption and low quality.
Vacuum drying chambers have more prospects. In other words they are better because they provide high-quality drying within a short period of time. Besides, they have available price. Moreover, their mounting and dismantling can be done quickly.
Notes: shelf dryer – стеллажная сушилка; chamber – камера, convective – конвективный; mounting – установка, монтаж; dismantling – демонтаж, разборка; solvent – растворитель; heat recovery – регенерация тепла
Comprehension Check