Process for preparing melamine by converting urea in the presence of a solid catalyst in one reactor or in a plurality of reactors connected in series in the temperature range from 370 C. to 430 C., cooling and filtering the gas formed in the urea conversion, removing the melamine by desublimation and recycling a portion of the gas present after the melamine removal (cycle gas) into the reactor or the reactors, which comprises performing all of the above stages at a pressure in the range from 4 bar abs. to 10 bar abs.

Process for preparing melamine by converting urea in the presence of a solid catalyst in one reactor or in a plurality of reactors connected in series in the temperature range from 370 C. to 430 C., cooling and filtering the gas formed in the urea conversion, removing the melamine by desublimation and recycling a portion of the gas present after the melamine removal (cycle gas) into the reactor or the reactors, which comprises performing all of the above stages at a pressure in the range from 4 bar abs. to 10 bar abs.

The present invention relates to a process for the production of melamine and the production plant including an off-gas condensation step carried out at a pressure of 70 to 220 bar by feeding gaseous and liquid streams at the same pressure, converting the liquid stream from the off-gas condensation step to a first stream, followed in succession by a high pressure decomposition step, a medium pressure decomposition step, a low pressure decomposition step, and urea concentration step.

Reactor for the synthesis of melamine from urea, in accordance with the high-pressure non-catalytic process, comprising: a vertical reactor body (1), at least one inlet (2) for the urea melt, a set of heating elements (3), and a central duct (7), said set of heating elements (3) being arranged inside said central duct.

A process for the high-pressure non-catalytic synthesis of melamine from urea wherein various heat inputs of the process are provided electrically, the process comprises reacting urea to form melamine in a synthesis reactor provided with electrical heating elements, the process further comprises heating the melamine melt electrically during transport and/or using electrically produced heat to remove water from melamine crystals.

A process for the high-pressure non-catalytic synthesis of melamine from urea wherein various heat inputs of the process are provided electrically, the process comprises reacting urea to form melamine in a synthesis reactor provided with electrical heating elements, the process further comprises heating the melamine melt electrically during transport and/or using electrically produced heat to remove water from melamine crystals.

The disclosure pertains to a process for the production of urea and melamine, wherein off-has from a high pressure melamine plant is combined with a urea liquid obtained from flashing of a urea synthesis solution. Also disclosed is a system for the combined production, and the modification of an existing plant or system.

The disclosure pertains to a process for the production of urea and melamine, wherein off-has from a high pressure melamine plant is combined with a urea liquid obtained from flashing of a urea synthesis solution. Also disclosed is a system for the combined production, and the modification of an existing plant or system.

The disclosure pertains to melamine production coupled to urea production, using a melamine off-gas condenser operating at a pressure of at least 25 bar. In embodiment, carbamate solution from a recovery section of the urea production is supplied to the melamine off-gas condenser. In an embodiment, carbamate solution from melamine mother liquor treatment is supplied to the LP carbamate condenser of the recovery section.

The disclosure pertains to melamine production coupled to urea production, using a melamine off-gas condenser operating at a pressure of at least 25 bar. In embodiment, carbamate solution from a recovery section of the urea production is supplied to the melamine off-gas condenser. In an embodiment, carbamate solution from melamine mother liquor treatment is supplied to the LP carbamate condenser of the recovery section.