Pages

Showing posts with label Chemistry. Show all posts
Showing posts with label Chemistry. Show all posts

Aug 4, 2009

Why is liquid ammonia used in ice plants?

Liquid ammonia acts as a refrigerant in ice plants. Evaporation of a liquid needs heat energy. When liquid ammonia vapourizes, it absorbs large quantities of heat without changing its temperature. For these reasons, ammonia is widely used as a refrigerant. About 17 g of liquid ammonia absorbs 5,700 calories of heat from the

Why is calcium sulphate hemihydrates called Plaster of Paris?

Plaster of Paris is obtained by heating gypsum or calcium sulphate dihydrate to about 140-180 degree Celsius. When heated to such a temperature, gypsum forms Plaster of Paris. The name is derived from the large deposits of gypsum in the Montmartre hill in Paris.

Aug 13, 2008

What is hydrocracking technology in petroleum refining?

Hydrocracking technology is an important conversion technology for producing high-value naphtha or distillate products from a wide range of refinery feedstocks. Conventional hydrocracking technologies have a difficult time handling low-quality feedstocks that are rich in undesirable asphaltene molecules, for example heavy oil, bottom of the