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Method for continuously producing melamine

A technology of melamine and isocyanic acid, applied in organic chemistry and other directions, can solve problems such as cost increase and interference with urea deposits, and achieve the effects of low cost, product yield and product purity optimization.

Active Publication Date: 2012-07-18
LURGI
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Problems solved by technology

[0006] The disadvantage of this treatment of the entire process gas in the scrubber is that the feed mechanism of the fluidized bed reactor is thus also supplied with urea-saturated process gas, so that a disturbing effect is repeatedly formed at the inlet of the feed mechanism urea deposits
A gas temperature of about 200° C. should not be exceeded, since the requirements on the feed mechanism and thus the costs increase considerably at high temperatures

Method used

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  • Method for continuously producing melamine
  • Method for continuously producing melamine

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Embodiment Construction

[0031] Liquid urea is fed into the gas separator (19) as raw material for the production of melamine and is led in the circuit through the cooling device (21). In the scrubber ( 18 ), the isocyanic acid residues present in the process gas stream ( 15 ) are converted into urea by an exothermic chemical reaction. The heat of reaction formed here is dissipated from the urea conducted in the circuit by means of a cooler ( 21 ). A urea stream ( 2 ) is branched off from the urea circuit of the scrubber, which is mixed with an ammonia stream ( 3 ) and fed into a fluidized bed reactor ( 24 ). A process gas stream (5) is formed from the process gas stream (4) treated in the scrubber (18) and the process gas stream (16) directed past the scrubber, which is supplied to Compressor or fan (22). In this case, the mixing ratio of the material streams ( 4 ) and ( 16 ) is adjusted such that the process gas stream ( 5 ) with a temperature of 200° C. is supplied to the compressor or fan ( 22 ...

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Abstract

The invention relates to a method for continuously producing melamine from urea by means of a fluidized bed reactor, wherein process gas conducted in the process circuit is used as the fluidizing gas, and wherein the temperature of the process gas at the inlet of the conveying element for the fluidizing gas is adjusted by adjusting the mixture ratio of a process gas flow conducted through a scrubber and a process gas flow conducted past the scrubber.

Description

technical field [0001] The invention relates to a process for the continuous production of melamine, in which liquid urea used as raw material is converted in a fluidized bed reactor in the presence of a catalyst, with supply of heat and addition of ammonia into a process gas mainly consisting of melamine, ammonia, carbon dioxide, intermediate product isocyanic acid and by-products, and wherein, after the by-products and melamine have been separated from the process gas, the process gas is led into a scrubber, In the scrubber, the process gas is cleaned with liquid urea and the isocyanic acid component is removed, wherein the process gas is partly used as fluidizing gas in the fluidized bed reactor after leaving the scrubber, It is partly used as cooling gas in the crystallizer and partly discharged from the process gas circuit. Background technique [0002] Processes for the continuous production of melamine from urea are known. An example of this is the so-called BASF lo...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07D251/60
CPCC07D251/60
Inventor 弗兰克·卡斯提罗-维尔他克里斯托弗·施泰登多米尼克·瓦尔塔格奥尔格·爱尔铃马丁·米勒-哈斯基
Owner LURGI
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