Thermal hydrolysis of urea

Abstract

An experimental investigation was undertaken to study the thermal hydrolysis of urea. Aqueous solutions of urea (1-5% w/w) were made to hydrolyze in an electrically heated hydrolyzer setup under pressure (1-5 kg/em'g) with conversion of 1.18-44% of the urea to ammonia and earbon dioxide. Design, construction and operation of the hydrolyzer setup constituted the major part of this study. The initial volume of urea solutions fed to the hydrolyzer was 900 ml. The product from the hydrolyzer consisted of a liquid mixture of ammonia, carbon dioxide, water and unconverted urea. Temperature and pressure of the operations were recorded. pH of the feed and product were measured. The urea content of the feed and product were spectrophotometrically determined. From the conversion vs. pressure plots it was observed that conversion of urea to ammonia increased with increasing pressure. Conversion was the lowest for atmospheric hydrolysis. From the measurement of pll, it was observed that pH of the hydrolyzed solutions was more than the pH of the original urea solution.