Plant for the synthesis of melamine starting from urea, wherein the stream of offgas containing NH3 and CO2 produced by the synthesis of melamine is converted into urea in a dedicated urea plant.

An ethylbenzene dehydrogenation plant for producing styrene which comprises a reaction section in which one or more adiabatic reaction apparatuses are positioned in series, and a steam circuit in which there is at least one first steam heat exchange apparatus; said plant being characterized in that it comprises heating equipment in which there is a heating circuit by means of recirculation of the fumes formed during dehydrogenation processes of ethylbenzene to give styrene, wherein said heating equipment comprises the following apparatuses in fluid communication with each other by means of said heating circuit: one or more ultra-heating apparatuses, one or more combustion devices in which at least one steam diffuser, one burner and at least one mixing apparatus are inserted, one or more ventilation device(s).

The present invention provides an annular centrifugal contactor, having a housing to receive a plurality of liquids; a rotor inside the housing; an annular mixing zone, with a plurality of fluid retention reservoirs; and an adjustable stem that can be raised to restrict the flow of a liquid into the rotor or lowered to increase the flow of liquid into the rotor. The invention also provides a method for transferring moieties from a first liquid to a second liquid, the method having the steps of combining the fluids in a housing whose interior has helically shaped first channels; subjecting the fluids to a spinning rotor to produce a mixture, whereby the channels simultaneously conduct the mixture downwardly and upwardly; and passing the mixture through the rotor to contact second channels, whereby the channels pump the second liquid through a first aperture while the first fluid exits a second aperture.

A method for revamping a self-stripping urea plant comprising the installation of a new CO2-stripping synthesis section (6), wherein at least part of the aqueous urea solution (10) leaving said new section (6) is directed to the existing low pressure recovery section (4) of the self-stripping plant, by-passing the existing self-stripping high-pressure section (2) and medium pressure treatment section (3).

The invention provides a method and a plant for producing urea ammonium nitrate (UAN). The method involves the use of a condensation section, optionally in combination with a medium pressure decomposition section, between the dissociation and neutralization sections. The invention further provides a method of modifying an existing UAN plant. The advantages of the process of the invention are that the emission of CO.sub.2 can be reduced, the plant capacity can be increased and the high capital expenditure needed for CO.sub.2 compression equipment is reduced.

A method for revamping an ammonia plant including a steam system, said steam system comprising at least a high-pressure section operating at a first pressure and a medium-pressure section operating at a second pressure lower than said first pressure, the revamping including: the provision of at least one additional heat recovery by means of a steam flow at a third pressure which is intermediate between said first and second pressure, and the provision of a steam export line arranged to export outside the ammonia plant at least a portion of said steam flow at said third pressure.

A process for synthesis of urea from CO.sub.2 and NH.sub.3 wherein a steam flow (13) produced in the condenser (3) of a high-pressure synthesis loop is compressed to raise its pressure and temperature before using the steam as a heat source for a downstream step of the process.

A refractory-lined equipment includes a vessel defining an interior at least partially lined with a refractory material, and a nozzle assembly coupled to the vessel and extending into the interior. The nozzle assembly includes an outer sleeve fixed to the sidewall and extending through an aperture defined in the sidewall, the outer sleeve defining a central passageway, and a nozzle cartridge assembly positionable within the central passageway and including an inner sleeve, a refractory lining disposed about the inner sleeve, and a nozzle positioned within the inner sleeve. The nozzle cartridge assembly is removably coupled to the outer sleeve external to the vessel.

A method for revamping a catalytic converter wherein: said catalytic converter comprises a pressure vessel and a catalytic cartridge containing at least one catalyst bed, the pressure vessel includes a cylindrical shell with a full aperture and includes a removable cover of said aperture, and the catalytic cartridge is removable through said upper aperture, and the method includes: installing an additional shell over the aperture of the original shell, thus obtaining an axially extended shell of the pressure vessel; providing an axially extended catalytic cartridge having an axially extended room for holding catalyst in the so obtained axially extended shell.

Proposed are a process and a plant for producing a hydrogen- and carbon oxides-containing synthesis gas by partial noncatalytic oxidation of a fluid or fluidizable carbon-containing input stream of fossil origin as a first input stream in the presence of an oxygen-containing oxidant and optionally a moderator to obtain a CO-rich raw synthesis gas. According to the invention a second input stream including a pyrolysis oil obtained from biomass is reacted simultaneously with the first input stream in the noncatalytic partial oxidation.