A high pressure melamine plant comprising a synthesis section and a melamine purification section, wherein the synthesis section provides a first melamine-containing stream (6), and said melamine purification section comprises: a quencher (2) receiving said first melamine-containing stream (6) from the synthesis section; a stripper (3) fed with a second melamine-containing stream (7) from said quencher (2), wherein purified melamine (11) is collected and vapours (10) are extracted; a heat exchanger (12), wherein said vapours (10) are condensed providing a condensed stream (14); an absorber (4) fed with said condensed stream (14) providing an aqueous solution (15) comprising ammonia and carbon dioxide, at least a portion (15b) of said aqueous solution being exported from the purification section (200) of the plant.

Disclosed is an integrated process for the production of urea and melamine, as well as a system for carrying out the process. The invention thereby pertains to an integrated process of the type wherein off-gas obtained from the production of melamine is entered into the process for the production of melamine, by condensation in the presence of water. A typical embodiment thereof is the condensation in the presence of an aqueous carbamate solution obtained from urea recovery. In accordance with the invention, said condensation takes place at a substantially lower pressure than the pressure at which the melamine off-gas is obtained. To this end, the pressure of the off-gas is reduced typically by 2-10 bar. In connection herewith, the system of the invention comprises a pressure reducing unit downstream of an outlet for the melamine off-gas, and upstream of a section for the condensation of the off-gas. The invention also includes a method for the modernization of an integrated system for the production of melamine and urea. This is accomplished by adding the aforementioned pressure reducing unit to a pre-existing system.

Disclosed is an integrated process for the production of urea and melamine, as well as a system for carrying out the process. The invention thereby pertains to an integrated process of the type wherein off-gas obtained from the production of melamine is entered into the process for the production of melamine, by condensation in the presence of water. A typical embodiment thereof is the condensation in the presence of an aqueous carbamate solution obtained from urea recovery. In accordance with the invention, said condensation takes place at a substantially lower pressure than the pressure at which the melamine off-gas is obtained. To this end, the pressure of the off-gas is reduced typically by 2-10 bar. In connection herewith, the system of the invention comprises a pressure reducing unit downstream of an outlet for the melamine off-gas, and upstream of a section for the condensation of the off-gas. The invention also includes a method for the modernization of an integrated system for the production of melamine and urea. This is accomplished by adding the aforementioned pressure reducing unit to a pre-existing system.

Combustion gas of an internal combustion engine passes through an exhaust system to an outlet opening. A detection device generates a state signal that describes an engine noise of the internal combustion engine. A control apparatus actuates at least one loudspeaker to produce a sound at the outlet opening based on the state signal to compensate for the engine noise or produce another engine noise, independently of the state signal based on predetermined audio data and thereby to use the at least one loudspeaker to audibly output an advisory signal described by the audio data.

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 a coupled plant process for the production of urea and melamine, with a urea synthesis section with HP CO.sub.2 stripping, and with a part of the CO.sub.2 feed supplied to a recovery section.

The disclosure pertains to a coupled plant process for the production of urea and melamine, with a urea synthesis section with HP CO.sub.2 stripping, and with a part of the CO.sub.2 feed supplied to a recovery section.

A process for the synthesis of urea and melamine, wherein urea synthesized in a urea plant is used to produce melamine in a melamine plant connected to the urea plant, according to a high-pressure non-catalytic melamine synthesis process, and offgas (16) liberated during the synthesis of melamine are returned to the urea plant after offgas processing (8) which includes a condensation and a urea formation step so that a urea-containing recycle stream (19) is returned to the synthesis section of the urea plant.

A process for the synthesis of urea and melamine, wherein urea synthesized in a urea plant is used to produce melamine in a melamine plant connected to the urea plant, according to a high-pressure non-catalytic melamine synthesis process, and offgas (16) liberated during the synthesis of melamine are returned to the urea plant after offgas processing (8) which includes a condensation and a urea formation step so that a urea-containing recycle stream (19) is returned to the synthesis section of the urea plant.