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The urea production uses CO2 gas and liquid ammonia as raw materials supplied from an Ammonia plant. This article will divide urea production into six sections: 1) Synthesis & HP Recovery; 2) MP Purification & Recovery; 3) LP Purification & Recovery, 4) Vacuum Concentration; 5) Condensate treatment; and 6) Prilling. SYNTHESIS AND HIGH PRESSURE (HP) RECOVERY In addition to the HP machinery required to feed ammonia and carbon dioxide and to recycle ammonium carbamate solution, this section includes: the reactor where urea is formed; the stripper necessary to strip out as vapors, from the urea solution leaving the reactor, a large amount of ammonia and carbon dioxide not converted to urea in the reactor; the carbamate condenser that condenses these vapors; the ejector that recycles the ammonium carbamate solution to the reactor. In this equipment the pressures are of a similar level, 150 bar, while the temperatures of the outlet solutions are 188, 205 and 155°

Competition between Ammonia technology suppliers is quite fierce. Three technology licensors — KBR (Kellogg Brown and Root), Haldor Topsøe, and ThyssenKrupp Industrial Solutions (TKIS) — currently dominate the market. Ammonia Casale, which offers an axial-radial catalyst bed design, is a market leader in revamps of existing plants. Most of the ammonia plants recently designed by KBR utilize its Purifier process, which combines low-severity reforming in the primary reformer, a liquid N 2 wash purifier downstream of the methanator to remove impurities and adjust the H 2 :N 2 ratio, a proprietary waste-heat boiler design, a unitized chiller, and a horizontal ammonia synthesis converter. Depending on the configuration of the plant, energy consumption can be as low as 28 GJ/m.t. Because the secondary reformer uses excess air, the primary reformer can be smaller than in conventional designs. The cryogenic purifier, which consists of an expander, condenser, feed/efflu

INTRODUCTION TO PET PRODUCTION PET may be produced from ethylene glycol and either dimethyl terephthalate (DMT) or terephthalic acid. High purity is required of all raw materials. In either case, the first step of the reaction is the formation of a prepolymer, bis-hydroxyethyl terephthalate (bis-HET). Subsequent polymerization of this material (with the removal of ethylene glycol) forms the polymeric polyethylene terephthalate. The extent of polymerization (apparent from the molecular weight of the polymer) is a function of the polymerization conditions and significantly affects the properties of the resin that is produced. Until the mid-1960s, DMT had been the preferred feedstock for PET manufacture, partly because the ester could generally be made in purer form than the acid. With the development of high-purity terephthalic acid processes, notably by Amoco, the free acid gained acceptance and is now the preferred feedstock. The use of high purity terephthalic acid (purified te