| 摘要 |
<p>THE INVENTION RELATES TO A HIGH-PRESSURE PROCESS FOR PREPARING PURE MELAMINE BY PYROLYSIS OF UREA IN A VERTICAL SYNTHESIS REACTOR, CHARACTERIZED IN THAT THE SYNTHESIS REACTOR HAS THREE STAGES ARRANGED VERTICALLY ONE ON TOP OF ANOTHER, AND A) IN THE FIRST, UPPERMOST STAGE, THE SMALLER PORTION OF THE TOTAL AMOUNT OF UREA IS INTRODUCED INTO THE CENTRAL TUBE OF A FIRST TANK REACTOR AND A FIRST MELAMINE-CONTAINING REACTION MEDIUM IS FORMED, B) IN THE SECOND, MIDDLE STAGE, THE FIRST MELAMINE- CONTAINING REACTION MEDIUM AND THE LARGER PORTION OF THE TOTAL AMOUNT OF UREA IS INTRODUCED INTO THE CENTRAL TUBE OF A SECOND TANK REACTOR AND A SECOND MELAMINE-CONTAINING REACTION MEDIUM IS FORMED, AND THEN C) IN THE THIRD, LOWERMOST STAGE, THE SECOND MELAMINE-CONTAINING REACTION MEDIUM IS INTRODUCED INTO A VERTICAL FLOW TUBE REACTOR AND A CRUDE MELAMINE MELT IS FORMED WHICH IS SUBSEQUENTLY WORKED UP IN ANY DESIRED MANNER AND PURE MELAMINE IS OBTAINED. THIS MAKES IT POSSIBLE TO ACHIEVE MORE UNIFORM UREA CONVERSION, GENTLER AND CORROSION-REDUCING SUPPLY OF THE HEAT OF REACTION AND OPTIMAL REACTION CONTROL, AND ALSO RESIDUE-FREE REACTION OF THE UREA IN THE MELAMINE SYNTHESIS REACTOR. IN COMPARISON TO OTHER MELAMINE 3) PROCESSES, THIS RESULTS IN A MORE COMPACT, LESS EXPENSIVE AND MORE EFFICIENT MELAMINE SYNTHESIS.</p> |
