Process for the synthesis of urea
US4208347A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | May 1, 1978 |
| Grant date | Jun 17, 1980 |
| Priority date | — |
| Expiry date | May 1, 1998 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY02P20/141
- WIPO fieldOrganic fine chemistry
- WIPO sectorChemistry
Abstract
An improved isobaric double-recycle process is disclosed for synthesizing urea with the formation of ammonium carbamate as an intermediate, comprising effecting reaction between ammonia and carbon dioxide at high NH.sub.3 :CO.sub.2 molar ratios, a heat-treatment of the synthesis product at substantially the same pressure as that of the synthesis step and in the presence of a stripping gas, and two distinct isobaric recycles of the residual substances and of the substances in excess released from said synthesis product, said process being characterized in that: PA1 (a) said heat-treatment of the synthesis product is carried out in two consecutive stages which are isobaric or substantially isobaric with respect to the synthesis step, in the first of which stages said synthesis product is heated, whereby substantially all the residual ammonium carbamate is decomposed and the decomposition products are displaced together with part of the excess NH.sub.3, while in the second stage the remaining part of the NH.sub.3 excess is displaced by supplying supplemental heat and by injecting thereto a CO.sub.2 stream; and PA1 (b) the gas phase stripped in the first stage is immediately recycled t…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.