FIELD: chemical engineering. SUBSTANCE: reactor has: barrier (8) arranged horizontally at specified height and separating reactor into lower and upper reaction spaces (9 and 10); means 11 for accumulation and isolation from reactor portion of gas phase containing vapor with high pressure and temperature values, preliminarily introduced into lower reaction space 9; and means 15 for feeding second portion of gas phase with high pressure and temperature values into upper reaction space 10. EFFECT: reduced content of urea below 10 ppm at low steam and power consumption. 13 cl, 3 dwg
