The disclosure pertains to a urea production plant and process using a high-pressure CO.sub.2 stripper, downstream medium-pressure treatment unit and a medium-pressure dissociator receiving urea synthesis solution from the reactor, wherein gas from the treatment unit and dissociator are condensed in a first condenser and off-gas from the synthesis section is condensed separately in a second condenser. A revamping method is also described.

A reactor for carrying out a chemical reaction has a reactor vessel, one or more reaction tubes and means for the electrical heating of the one or more reaction tubes. The reactor vessel has one or more discharge orifices which are permanently open or are set up to open above a preset pressure level, and gas feed means are provided, which are set up to feed an inerting gas into an interior of the reactor vessel.

Methods and systems for producing vinyl acetate may use flammability limit (FL) formulas with improved efficiencies at more than one location in the vinyl acetate production process. Herein, FLs can be used at one or more of four portions of the vinyl acetate production process: the reactor, the process-to-process heat exchangers, the carbon dioxide removal system, and the ethylene recovery system. Such FLs are functions of operating conditions and include at least one interaction term that represents the interrelation of two or more of the operating conditions (e.g., temperature, pressure, and component concentration) on the FL.

A sector marker for placement over a tubesheet and defining an opening for performing maintenance on an open tube located below the sector marker, the sector marker positioned over the tubesheet by at least two pins extending below the sector marker and respectively received in tube openings below the sector marker. A device and a method for easily and accurately marking and identifying the location of the tubes in a reactor vessel and for keeping track, in real-time, of the tasks performed on the tubes.

The present invention provides a multistage single reactor system for hydroprocessing and a process of carrying out multistage hydroprocessing in the said reactor assembly consisting of, a fixed bed solid catalyst system, a feed injection system enabling axial flow of hydrogen saturated hydrocarbon feed, a hydrogen dispensing system inside the reactor enabling minimum required hydrogen flow in cross-flow pattern, also using multitudes of integrated separation and withdrawal limbs for continuous staging. The innovative reactor disclosed in the present invention enables continuous separation and withdrawal of gaseous products along the reactor length by means of combined horizontal reactor orientation and vertical separation limbs provided at the top of the horizontally oriented reactor. The advantage of the reactor assembly includes effective heat sink of exothermic reactions and lower severity of operation due to removal of inhibitory gaseous products.

A process and equipment assembly for reacting a substituent precursor with a cyclodextrin starting material to provide a raw product comprising a cyclodextrin derivative and 1% or less of an initial amount of the substituent precursor is provided. The process of the present invention provides cyclodextrin derivatives in substantially shorter time and with fewer side products than previous processes that utilize substantially the same starting materials.

An easily polymerizable substance handling device is provided that can prevent generation of irregularities and steps between a pipeline and a cover member due to the cover member being installed at an opening part of the pipeline. A cover part 3 is formed to have a curved surface 3a on a side closer to inside of a pipeline 1. The shape of the surface 3a on the pipeline 1 side is preferably a concave shape when viewed from inside of the pipeline 1. The shape of the surface 3a of the cover part 3 on the pipeline 1 side is more preferably the shape of a curved surface having a curvature radius equal or approximate to that of the internal circumference of the pipeline 1. With this configuration, a polymer material is unlikely to be generated at the cover part 3 and around a gap 1b at an opening part 1a, and the frequency of cleaning can be reduced as compared to conventional cases.

Disclosed herein too is a method comprising charging to a reactor system a feed stream comprising a catalyst, a monomer and a solvent; reacting the monomer to form a polymer; where the polymer is contained in a single phase polymer solution; transporting the polymer solution to a pre-heater to increase the temperature of the polymer solution; charging the polymer solution to a liquid-liquid separator; reducing a pressure of the polymer solution in the liquid-liquid separator and separating a polymer-rich phase from a solvent-rich phase in the liquid-liquid separator; transporting the polymer-rich phase to a plurality of devolatilization vessels located downstream of the liquid-liquid separator, where each devolatilization vessel operates at a lower pressure than the preceding devolatilization vessel; and separating the polymer from volatiles present in the polymer rich phase.

In a production system for vapor-grown carbon nanofibers includes a static mixer and a micro mist nozzle for preventing un-uniform input material from forming impurities, an anti-adhering coating covering an inner wall of a vertical tubular reactor for preventing a catalyst, raw material and carbon fibers from adhering to the inner wall of the vertical tubular reactor, and a sedimentation device into which a dispersant and water are inputted to separate produced carbon fiber compositions from particulate impurities in water.

The invention provides a shut down method for a process for the preparation of glycols from a starting material comprising one or more saccharides in the presence 5 of hydrogen and a catalyst system comprising one or more retro-aldol catalysts comprising tungsten and one or more catalytic species suitable for hydrogenation in a reactor, said method comprising removing the one or more retro-aldol catalysts from the reactor whilst also in the presence of one or more agents suitable to suppress tungsten precipitation.