对二甲苯的发展现状分析及其对的环境的影响.pptVIP

Analysis and influence of paraxylene on living environment;;About p-Xylene;Technology development and process improvement;Paraxylene is primarily used as a basic raw material in the manufacture of terephthalic acid (TPA), purified terephthalic acid (PTA) and dimethyl-terephthalate (DMT). TPA, PTA and DMT are used to manufacture polyethylene terephthalate (PET) saturated polyester polymers. Polyesters are used to produce fibers and films. PET bottles are widely used for water because of its non-breakage properties as well as carbonated beverages because of good carbon dioxide barrier properties. In addition, they are light-weight, shatter-resistant and possess high tensile strength. Polyester uses include ;Historically, crystallization technology was perceived to suffer from disadvantages of requiring low temperature refrigerants for the freezing process and requiring more rotating mechanical equipment. BP Corporation North America, Inc. (formerly Amoco Chemical Company) has continually improved their para-xylene crystallization process since commissioning their first commercial para-xylene unit in 1967, such that they now claim that their new crystallization technique has lower energy use and unit capital cost than other para-xylene production methods. ;para -Xylene separation from mixed xylene feedstocks requires first stage crystallization temperatures as low as -90 °F (-68 °C). The conventional crystallization processes use cascaded ethylene/propane or ethylene/propylene (C 2/C 3) vapor compression refrigeration systems. The C 3 compressor is an expensive piece of equipment, and a large user of electricity. This report describes a new energy efficient technique that uses waste heat powered ammonia absorption refrigeration (AAR) instead of conventional C 3 refrigeration. ; Sources of pollution Pxylene is an important chemical raw materials. The waste water and gas in organic synthesis, synthetic rubber, paints and dyes, synthetic fibers, petroleum processi