High-vacuum equipment, inorganic

Effective solutions to the problems of the vacuum residue hydrodesulfurization unit equipped with the fixed bed reactors, such as a hot spot, pressure-drop buildup, and catalyst deactivation by coke fouling, were discussed. Improving liquid distribution can prevent hot spot occurrence. Dispersing inorganic solids throughout the reactors can control a pressure-drop increase in the first bed. For a high conversion operation, controlling the conversion in each bed can minimize the coke deactivation in the fourth bed. 

MEG and some of its analogues are used for drying natural gas to prevent the formation of methane hydrate. MEG picks up water from the gas and is recycled through a simple continuous still of a few trays in which the MEG is dried. This operation can enable the desiccant to be used many times but it eventually is so contaminated by inorganic salt (mostly NaCl) that it must be evaporated. This can be done in a wiped surface evaporator under vacuum but this involves fairly expensive equipment and it can be done in a thick wall mild steel pot with an anchor stirrer provided high enough steam pressure or hot oil temperature is available. 

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