Method for preparing melamine

A technology of melamine and high pressure, applied in the field of preparing melamine, can solve the problems of difficult to maintain continuously, and achieve the effect of good color characteristics

Inactive Publication Date: 2003-12-03
DSM IP ASSETS BV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0003] According to EP-A-747366, the purity of the final product of melamine is above 98.5%, but this result is difficult to continuously maintain at a constant level in large-scale industrial production
This is a disadvantage of this method, especially when melamine is used to prepare melamine-formaldehyde resins for laminates and / or coatings

Method used

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Examples

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Embodiment Construction

[0017] The above object of the invention is achieved by using a plant suitable for the preparation of melamine from urea. Apparatus suitable for the purposes of the present invention may comprise a scrubber, a reactor, a vapor-liquid separator, optionally an afterreactor and a cooling vessel.

[0018] In one embodiment of the invention, melamine is produced from urea in a plant comprising a scrubber, a melamine reactor, a vapor-liquid separator and a cooling vessel. The urea melt coming out of the urea plant is sent into a washing device at a pressure of 5 to 25 MPa, preferably 8 to 20 MPa, and a temperature higher than the melting point of urea. The washing unit can be provided with a cooling jacket for additional cooling of the washing unit. The washing device can also have an integrated cooling body. In the scrubber liquid urea is brought into contact with the reaction gas phase from the melamine reactor, or from a separate vapor-liquid separator downstream of the reactor...

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Abstract

Method for preparing melamine from urea via a high-pressure process in which solid melamine is obtained by transferring the reactor product comprising liquid melamine, CO2 and NH3 to a gas / liquid separator and subsequently transferring the melamine melt coming from the separator to a vessel where the melamine melt is cooled with an evaporating cooling medium, characterized in that, the gas / liquid separation is conducted by addition of 5.10<-4> - 2.10<-2> mole of water per mole of melamine.

Description

technical field [0001] The present invention relates to a method for preparing melamine from urea under high pressure, wherein by including liquid melamine, CO 2 and NH 3 The reactor product is transferred to the vapor-liquid separator, and then the melamine melt coming out of the vapor-liquid separator is transferred to a container, wherein the melamine melt is cooled with a cooling medium to obtain a melamine solid. Background technique [0002] This method is described, inter alia, in European patent EP-A-747366. This document describes a process for the high-pressure preparation of melamine from urea. Specifically, EP-A-747366 describes how urea is thermally decomposed in a reactor at a pressure of 10.34-24.13 MPa at a temperature of 354 to 454° C. to obtain a reactor product. The obtained reactor products include liquid melamine, CO 2 and NH 3 , the product is transferred to a vapor-liquid separator under the pressure of the mixed vapor. In the vapor-liquid separa...

Claims

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Application Information

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IPC IPC(8): C07D251/60C07D251/62
CPCC07D251/60
Inventor 王寅
Owner DSM IP ASSETS BV
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