| 摘要 |
1. Process for preparing melamine from urea at elevated temperature and in the presence of a catalyst, in which a gaseous product stream is obtained which is contacted with a liquid coolant in a cooling zone, characterized in that the temperature in the scrubbing section is lowered by applying an extra cooling step. 2. Process according to Claim 1, characterized in that the temperature in the scrubbing section is lowered by passing the liquid from the scrubbing section to a heat exchanger, cooling the liquid in the heat exchanger with the aid of a liquid coolant and then returning the cooled liquid to the cooling zone. 3. Process according to Claims 1-2, characterized in that the temperature in the scrubbing section is reduced by at least 5 degree C. 4. Process according to Claim 3, characterized in that the temperature in the scrubbing section is reduced by at least 10 degree C. 5. Process according to Claims 1-4, characterized in that the gas coming from the reactor has a pressure of between 0.6 and 2.5 MPa. 6. Process according to Claim 5, characterized in that the gas coming from the reactor has a pressure of between 0.7 and 2.2 MPa. 7. Technique for modifying existing melamine plants by application of the process according to Claims 1-6.
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