Urea
Summary
Urea is a major nitrogen fertilizer produced from ammonia and carbon dioxide as raw material. Its application is not only for fertilizer but also for cattle feed, industrial purpose of resin/plastic/adhesive glue and recently expanded into reducing agent (“AdBlue®”) for SCR (Selective Catalytic Reduction) to decrease the emission of NOx from diesel engine vehicles. In addition the increasing of demand of bio-energy causes more demand of urea fertilizer. In this way, Urea is one of the most important product to solve the issues of “Food”, “Environment” and “Energy”.
The Urea Plant consists of Synthesis Unit and Granulation Unit.
Features
Urea synthesis from NH3 and CO2 is exothermic chemical reaction as shown below.
Practically, for the industrial application, stoichiometrically excess NH3 (NH3 /CO2 = 2.9 ~ 4.1, molar ratio) is used to promote urea formation in an equation (3) in the Reactor. Resultantly, the synthesis mixture composes urea, excess NH3, ammonium carbamate and water.
Therefore, separations of excess NH3, decomposition of unconverted ammonium carbamate and evaporation of water from the synthesis mixture are required to obtain solid urea as the final product.
Process Flow Diagram of Urea Process
